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Texture Segmentation Using Wavelet Frame and Spatial Information
Get PDFThis paper introduces a texture segmentation method that relies on envelope values of discrete wavelet frame coefficients and spatial information. A texture is characterized by a set of channel variances estimated at the output of the corresponding filter bank. Wavelet transform that is combination of filter banks is usefully tool for feature extraction of texture. We use envelope of discrete wavelet frame for feature extraction of texture using wavelet transform. But this method is sensitive to filter selection and have problem that calculation is complicated.
The proposed method removes these problems. We use wavelet frame instead of wavelet packet frame to reduce expenditure and add Coordinate Values to feature for efficient segmentation. In experiment, this method is proved that is efficient than the previous method using wavelet packet frame.목차
제1장 서론 = 5
제2장 웨이브렛 패킷 프레임을 이용한 질감 영상 분할 = 8
2.1 웨이브렛 변환 = 8
2.1.1 연속 웨이브렛 변환 = 11
2.1.2 이산 웨이브렛 변환 = 12
2.1.3 다중해상도 분석 = 16
2.2 웨이브렛 패킷 프레임과 포락선을 이용한 질감의 특징 추출 = 19
2.3 질감 영상 분할 = 23
제3장 웨이브렛 변환과 공간 정보를 이용한 질감 영상 분할 = 24
3.1 질감 영상 분할을 위한 특징 추출 = 24
3.1.1 이산 웨이브렛 프레임을 이용한 질감 특징 추출 = 24
3.1.2 공간 정보를 이용한 질감 특징 추출 = 28
3.2 웨이브렛 프？뮌緞？ 공간 정보를 이용한 질감 영상 분할 = 28
제4장 실험 및 고찰 = 31
제5장 결론 = 4
3D-PTV Construction Based on Genetic Algorithm and Its Application to the Wake Characteristics Near Circular Cylinder
Get PDFIn order to verify the capability of the constructed measurement system, a performance test was made using a set of virtual images on a impinging jet. After confirming the performances of the constructed system, the system was applied to the measurement of flow characteristics of the wake of a circular cylinder.
The belows are the summary of the thesis.
GA based 3D-PTV system for the measurement of complex flow structure are constructed in the first half of the thesis.
The performances test on the constructed system is made using the sets of virtual images generated by a LES data set on a impinging jet flow. Through this test it is verified that the vector recovery ratio becomes higher three times than those of other studies. It is shown that about 1,100 three-dimensional instantaneous velocity vectors is obtained in an actual experiment, which implies that the recovery ratio is more than over about 65%. This percentage is most highest among other three-dimensional PTV techniques.
The constructed system having the above performances is applied to the measurement of the flow field near the wake of a circular cylinder and turbulent characteristics of the flow such as turbulent intensity, Reynolds stresses, turbulent kinetic energy are measured by the constructed system. Good qualitative and quantitative results on the turbulent properties are shown.
Lastly, it is shown that the constructed 3D-GA-PTV system will be able to be used for the investigation of the turbulent characteristics of complex flows since the number of 3D velocity vectors obtained by the system is big enough than the limits, 700, for probing the turbulences of complex flows.List of Figures = ⅰ
List of Tables = ⅳ
Abstract = ？？
기호 설명 = ⅶ
제 1 장 서론 = 1
1.1 연구 배경 및 관련 연구 = 1
1.2 연구 목적 및 내용 = 4
제 2 장 3 차원 PTV 속도장 측정시스템 및 구성 = 6
2.1 유동장 가시화 장치와 구성 = 6
2.2 카메라의 교정작업 = 8
2.3 3 차원 위치 계측의 원리 = 13
2.4 화상 처리 = 17
2.4.1 전처리 과정 = 17
2.4.2 화상의 보정 = 18
2.4.3 도심의 검출 (Centroid calculation) = 19
제 3 장 유전적 알고리듬 기반 3 차원 속도벡터 계측 = 21
3.1 일반적인 유전적 알고리듬 = 21
3.2 PTV 에서의 유전 알고리듬 = 22
3.2.1 유전자적 표현 방법 = 22
3.2.2 초기 개체의 결정 = 22
3.2.3 목적함수의 설정 = 23
3.2.4 유전연산자의 사용 = 25
3.3 후처리 과정 = 29
3.4 오차해석 = 31
3.5 가상영상에 의한 성능평가 = 34
3.5.1 가상영상의 구현 = 34
3.5.2 제트유동의 가상영상 = 44
제 4 장 원주 근접후류 계측 = 50
4.1 계측 시스템 = 50
4.2 계측방법 및 실험조건 = 52
제 5 장 연구결과의 비교 및 검토 = 54
5.1 3 차원 평균 및 순시 속도장 = 54
5.2 각 단면에서의 난류 강도 분포 = 64
5.3 각 단면에서의 난류운동에너지 분포 = 100
5.4 각 단면에서의 레이놀즈 응력 분포 = 112
제 6 장 결론 = 148
참고문헌 = 15
A Hybrid QoS Guarantee Scheme for High-Quality Internet Audio Streaming Services
Get PDFThis paper describes a hybrid QoS guarantee scheme for high quality audio streaming services on the Internet. One of the continuous multimedia data, digital audio, has the timing restrictions on transmission and playback over the packet switching networks. The continuous playback of the audio data requires the isochronous transmission of the audio data packet through the Internet. In order to retain the QoS at the ultimate destination (client) as the same as servers provide, the transmission protocols should consider the error conditions such as packet loss, and out of order delivery. Generally, the protocols supporting the transmission of continuous multimedia data do not recover the errors due to the packet loss, and out of order delivery. These are working good for the audio and video streaming services with the toll quality, but not for the high quality streaming services, such as the surround hi-fi sound/music playback. The hybrid QoS guarantee scheme includes the three mechanisms to overcome the problem. First, the selective retransmission is adopted to recover the packet loss with the minimal
overhead. Second, the adaptive buffering at client-side is designed to prevent from the starvation of audio data during the retransmission. Finally, the adaptive transmission rate at server-side is also used to maintain the isochronous transmission even after the retransmission due to packet loss. The experiments haven good results of the hybrid QoS guarantee scheme for the high quality audio streaming services on the Internet.목차
제1장 서론 = 1
1.1 연구 배경 = 1
1.2 연구 목적 및 제안기법 = 2
제2장 관련 연구 = 4
2.1 오디오 스트리밍 서비스 개요 = 4
2.2 RTP (REAL-TIME TRANSPORT PROTOCOL) = 6
2.3 멀티미디어 데이터 스트리밍 서비스 QOS 보장 기법 = 8
제3장 오디오 스트리밍 서비스 관련 기초 실험 = 12
3.1 인터넷 데이터 손실률 = 12
3.2 왕복시간 = 15
3.3 전송률에 따른 패킷 간격 = 17
제4장 복합적 QOS 보장 기법 = 19
4.1 선택적 재전송 = 20
4.2 클라이언트 버퍼 동적 할당 = 22
4.3 전송률 동적 제어 = 23
제5장 실험 및 결과 = 26
5.1 재전송 소요시간 = 26
5.2 재전송 완료시 버퍼 내의 남은 재생시간 = 28
5.3 2분 동안 재생시 수신측 재생되지 않은 버퍼량 변화 = 29
5.4 재전송시 송신측 패킷 간격 변화 = 30
5.5 재전송시 수신측 패킷 간격 변화 = 31
제6장 결론 및 향후 연구과제 = 32
참고문헌 = 3
(A) Study on the Development of the Electric Furnace Controller For Heat Treatment based on the Internet
Get PDFThe control based on the internet is just getting started: the first commercial projects appeared less than ten year ago but are now finding widespread application.
In this paper, we have developed the electric furnace controller for heat treatment using the internet.
The internet provides a low-cost and widely-available interface that can make teleoperated resources accessible to anyone with Web Brower.
Clients are connected the system which is electric furnace controller by using remote access watch for condition of electric furnace on real-time and it is controlled by them precisely. The system is consisted of WWW(World Wide Web) server, DB(DataBase) server, control server and controller. They are connected to the internet but the communication between control server to controller are transmitted using RS-232C.
The WWW server algorithm has been designed to include log-in function, furnace watch function, etc. The DB server has been used relational database of 2-tire structure supported SQL(Structured Query Language). And it is constituted four tables that saved process-data. The control server has been designed to base on auto-tuning method algorithm for self-controlling.
The controller that embedded in 8-bit RISCA(Reduced Instruction Set Computer Architecture) chip is consisted of distributed temperature sensing module and electric furnace driver module.
It was confirmed that the system is able to control precision temperature, ramp time and holding time for electric furnace. This controller based on the internet has a variety functions for heat treatment. The validity of these functions is confirmed experimentally.Abstract = ⅲ
제1장 서론 = 1
1.1 연구배경 = 1
1.2 연구개요 = 2
제2장 알고리즘 및 서버 구축 = 4
2.1 알고리즘 = 4
2.1.1 네트웍 알고리즘 = 4
2.1.2 전용망 구축 알고리즘 = 7
2.1.3 전기로 제어 알고리즘 = 10
2.2 서버 구축 = 12
2.2.1 WWW서버 = 12
2.2.2 DB서버 = 15
2.2.3 제어서버 = 17
제3장 제어시스템 구성 = 20
3.1 인터넷 제어시스템 구성 = 20
3.1.1 DB 설계 = 21
3.1.2 웹프로그램 = 22
3.1.3 제어프로그램 = 24
3.2 열처리용 전기로 제어기 구성 = 29
3.2.1 개요 = 29
3.2.2 데이터 처리 장치 = 30
3.2.3 분산형 온도감지 모듈 = 34
3.2.4 전기로 스위칭 모듈 = 38
제4장 실험 및 고찰 = 41
4.1 실험장치 = 41
4.2 인터넷 운용 특성 실험 = 44
4.3 전기로 특성 실험 = 47
4.4 제어기 성능 실험 = 48
제5장 결론 = 52
참고문헌 = 54
감사의 말씀 = 5
A Study on the Development of Deterioration Diagnostic Techniques for Lightning Arresters
Get PDFIn this dissertation, the changes of electrical properties and new diagnostic techniques for lightning arresters have been studied. Generally, lightning arresters deteriorate as the result of a repetitive application of AC over-voltages or lightning impulse currents. The resistive leakage current of arresters increases as the deterioration of the arrester progresses, showing an increase in the 3^rd harmonic component of the leakage current. The deteriorated lightning arrester is brought to a thermal runaway, where it can cause a line-to-earth fault. It is, therefore, important to estimate the change of electrical properties and the expected lifetime of lightning arresters.
To study the change of electrical properties in lightning arresters, a multiple-lightning impulse generator which can produce a quadruple with impulse current of 8/20[㎲] 5[kA] at an interval of 30~120[ms] has been designed and fabricated. The generator generates almost same thing as natural lightning ground flash. The total energy applied to the arrester at each pulse is about 1,200[J]. In the experiment, various parameters such as leakage current, reference voltage, and temperature were measured with the number of applied impulse currents. Also, micro-structures of the ZnO blocks were investigated 200 times after applying the single- and the multiple-lightning impulse currents.
The experimental results indicated that the arrester blocks are more vulnerable to deterioration or damage from the multiple-lightning impulse currents. Therefore, it is necessary for lightning arresters used in power systems to be tested by applying not only a single-impulse current but also a multiple-impulse current. Also, to deduce the parameters necessary for diagnosing arrester deterioration, the accelerated deterioration tests were carried out.
In the test, leakage current components were measured, and the wave height distributions of leakage current were analyzed according to the progress of deterioration in the arrester.
The wave height distributions of the leakage current showed conspicuous differences even though the deterioration of arrester was progressed a little. Consequently, the use of wave height distributions in the leakage current for a deterioration diagnostic technique is valuable because it makes a more accurate diagnosis than the conventional method of using only a leakage current value.
The expert system for diagnosing the deterioration of arresters has been designed, and the system can diagnose lightning arresters by measuring the leakage current magnitude and its wave height distribution.
Today, arrester diagnostic techniques based on total leakage current and/or the 3^rd harmonic leakage current as a reference parameter of deterioration are widely used. The technique, however, includes an error due to the harmonics of power system voltage. Therefore, the influence of the harmonics on arrester diagnostics should be considered.
In this dissertation, an arrester model was designed to simulate the influence of the voltage harmonics described above. A pure sinusoidal voltage and its the 3^rd harmonic voltage were applied to the model, and the leakage current components were analyzed.
From the simulation results, it was confirmed that the peak value of resistive leakage current depends not only on the phase of the 3^rd harmonic voltage but also on the magnitude of it. Consequently, the errors caused by the harmonic voltage could be minimized by correcting the magnitude of leakage current upon analyzing the harmonics.목차
목차 = i
그림 및 표목차 = iii
Abstract = vi
제1？？ 서론 = 1
1.1 연구 배경 및 필요성 = 1
1.2 연구 목적 및 내용 = 6
제2장 이론 = 9
2.1 피뢰기의 특성 = 9
2.2 열화진전기구 = 15
2.3 열화진단기술 = 26
2.3.1 전체 누설전류에 의한 열화진단기술 = 28
2.3.2 저항분 누설전류에 의한 열화진단기술 = 29
제3장 뇌충격전류에 의한 가속열화 실험 = 34
3.1 실험장치 및 측정계 = 35
3.2 실험방법 = 50
제4장 열화진단기술 개발 = 52
4.1 열화진단기술 = 53
4.1.1 누설전류 파고분포 분석 = 53
4.1.2 저항분 누설전류 분석 = 56
4.2 열화진단장치의 설계 및 제작 = 58
4.2.1 파고분포를 이용한 열화진단장치 = 58
4.2.2 저항분 누설전류를 이용한 열화진단시스템 = 66
제5장 실험 결과 및 고찰 = 76
5.1 가속열화 실험 = 76
5.1.1 기본특성 실험 = 76
5.1.2 뇌충격전류 실험 = 79
5.2 열화진단기술 = 88
5.2.1 누설전류의 파고분포에 의한 열화진단 = 88
5.2.2 저항분 누설전류에 의한 열화진단 = 97
5.3 전원고조파에 의한 영향 고찰 = 99
제6장 결론 = 107
[참고문헌] = 11
A Study on the Electronic Bills of Lading
Get PDFAfter the middle of 20TH century, Electronic commerce is now becoming prevalent rapidly. And the development of transport techniques and environmental changes in international trade has caused many problems concerning the use of traditional Bills of Lading.
In particular, modern and efficient methods of transportation have in effect become commodity services in most parts of the developed world as a result of the introduction of the container in the 1960's due to as above situation one of transport documents of Bills of Lading face with crisis in the international trade.
So, Traditional Bills of Lading has tended to become an obstacle to the development of trade and in the end restricting the expeditious flow of goods for solve Bills of Lading's crisis international trade.
Therefore, Today's Bills of Lading is requested its change.
The one aspect is the crisis of Bills of Lading, one of the most important documents and the typical systems, which is produced for commercial products. Bills of Lading plays an important role as currency trades and a indispensable document in international trading, it is working as a receipt of the goods, as a document of title, and as a evidence of contract, therefore the consignee of goods must introduce a Bill of Lading to accept the goods, but the current situation in international trade, the goods arrived at their destination before Bills of Lading, because of transport technology development which represented by the development of containerization and the turn up of the fast container ship.
The flow of goods was more faster by two progresses of technology, but the flow of Bills of Lading was not developed and passed through the bank to examine the document in letter of credit transactions.
The other aspect is the rapid introduction of Electronic data interchange(EDI) system. Today, as electronic data interchange system comes into a wide use, international trade which has been traditionally carried out with documents is gradually being transformed into a paperless transaction.
The Bills of Lading can also be issued electronically, it can therefore be easily expected that, by the introduction of EDI system, the paper Bills of Lading will soon disappear in practice and the efficiency in international transaction be promoted. The use of EDI is more effective, cheaper and more rapid than paper document system. Thus the environment of trade was changed by EDI.
However, Other trade documents can be replaced by EDI messages without problem, but the Bills of Lading has several impediments in converting EDI message. Because Bills of Lading is a document of title, therefore Electronic Bills of Lading has to prove the right.
To encourage the use of Electronic Bills of Lading , CMI Uniform Rules for the Electronic Bills of Lading was enacted in 1990 and other related international rules were revised to in corporate the use of Electronic Bills of Lading. Despite there international efforts to promote the use of Electronic Bills of Lading, the actual utilization in practice has been very minimal, due to various problems and limitations.
In order to proliferation of Electronic Bills of Lading, legal confirmation is needed. That is to say Electronic Bills of Lading must has the same legal status as the existing Bills of Lading in the aspect of international regulations. But current situation, Electronic Bills of Lading is not a new form of Bills of Lading a kind of contract which governs carriage of goods by sea.
The legal problems of Electronic Bills of Lading are evidential issue of EDI such as request of writing, authentication, electronic signature, and contractual issue of EDI transactions, liability issues of the parties.
Even though Bolero(Bills of Lading Electronic Registry Organization) international developed the Bolero style Bills of Lading among some of europe countries and shipping companies, it couldn't settle above problems in Electronic Bills of Lading.
Despite the fact that paper transactions have gradually been transformed into EDI system, it may not be possible that the paper Bills of Lading will fully be substituted by electronic one owing to the inherent nature of Bills of Lading as being the document of title.
For the full utilization of Electronic Bills of Lading, therefore this study brings focus to the solution of Bills of Lading crisis and looks into the legal problems and seeks new legislation about Electronic Bills of Lading.목차
第1章 序論 = 1
第1節 硏究의 目的 = 1
第2節 硏究의 範圍 및 方法 = 3
第2章 電子式 船荷證券의 意義와 出現 背景 = 5
第1節 電子式 船荷證券의 意義 = 5
I. EDI의 定義와 生成 背景 = 5
II. 船荷證券의 EDI화 = 7
III. 電子式 船荷證券의 意義 = 8
第2節 船荷證券 機能의 限界와 解決方案 = 11
I. 船荷證券의 機能 = 11
II. 船荷證券의 限界 = 13
III. 船荷證券의 機能的 危機의 解決方案 = 14
IV. 電子式 船荷證券의 導入 背景 및 目的 = 24
第3章 電子式 船荷證券과 관련된 國際協約 = 26
第1節 電子式 船荷證券의 統一에 관한 國際協約 = 26
I. CMI 統一規則의 適用範圍 및 用語定義 = 26
II. 電子式 船荷證券의 發行 = 29
III. 電子式 船荷證券의 記載事項 = 33
IV. 電子式 船荷證券에 의한 運用節次 = 36
V. 書面形式의 서류를 選擇할 權利 = 40
VI. 電子式 船荷證券의 法的 效力 = 42
第2節 船荷證券과 관련된 旣存의 國際規範과 電子式 船荷證券의 關係 = 45
I. 헤이그·비스비 規則 = 46
II. 함부르크 規則 = 47
III. UN國際物品複合運送條約 = 48
IV. INCOTERMS 1990 = 48
V. 화환신용장 統一規則(UCP 500) = 50
第4章 볼레？嬌？ 船荷證券 = 51
第1節 볼레로式 船荷證券의 構成과 運用 = 51
I. 볼레로式 船荷證券의 基本構圖 = 53
II. 重要裝置와 道具 = 55
III. 볼레로의 加入과 登錄 = 57
IV. 볼레로式 船荷證券의 運用 = 57
第2節 볼레로式 船荷證券에 관한 규정집의 主要內容 = 59
I. 準據法 및 管轄 = 59
II. 船荷證券의 債權的 效力 = 60
III. 船荷證券의 物權的 效力 = 61
IV. 約款의 編入(Incorporation by Reference) = 63
第3節 볼레로式 船荷證券이 海商法에 미칠 影響 = 64
I. 責任主體確定의 問題 = 65
II. L/G 制度 = 66
III. 荷渡指示書(Delivery order)의 必要性 = 67
IV. 海商法 船荷證券編에 미칠 影響 = 67
V. 볼레로式 船荷證券의 長點 및 短點 = 69
第5章 電子式 船荷證券의 限界와 改善方案 = 70
第1節 電子式 船荷證券의 사용시 예상되는 問題點 = 71
I. 賣渡人의 契約物品引渡機能上의 問題點 = 71
II. 換어음의 擔保機能上의 問題點 = 72
III. 運送中인 貨物의 轉賣機能上의 問題點 = 73
IV. 貨物의 引渡請求權機能上의 問題點 = 74
V. 運送人의 責任增加와 費用上의 問題點 = 75
第2節 電子式 船荷證券？？ 實用方案 = 75
I. 電子式 船荷證券의 限界 = 76
II. 電子式 船荷證券의 改善方案 = 85
第6章 結論 = 87
參考文獻 = 9
Optimization of Testing Method in Comparison with the Coated Composites and Metals by Vibratory Cavitation Test
Get PDFCavitation is a hydrodynamic phenomenon which results in the formation and collapse of vapor bubbles in a liquid.
In recent year, an equipment, an automobile, an aeroplane, ship and many industrial fields show a tendency of high output and lightweight along with industrial growth. In fluid machinery, if the speed of running fluid and rotative speed of machine become increase, the cavitation erosion happens because of partial cavitation bubbling with decreasing of static pressure and fluid shock.
Cavitation damage is encountered in a wide variety of fluid handling machinery and over a broad range of liquid pressures and temperatures.
Laboratory tests to establish the relative resistance of materials are usually made in experimental facilities standardized to their most appropriate operating conditions. The vibratory facility is the most commonly used of these and has generated most of the available data.
At the first test, cavitation test(ASTM G-32) was compared with coated composite material and metals, but coated composite material specimens appeared to generating a low bubbles due to damping vibration and having a hard time testing for many hours due to interface delamination between metal and composite material.
In this study, to use cavitation apparatus, such as the piezoelectric vibrator with 20kHz, 50㎛ to cavity generation, we compared with the traditional cavitation testing method (ASTM G-32) and modified cavitation testing method.
Throughout this test, we investigated the optimization of testing method in comparison with the coated composites and metals by vibratory cavitation test.
The main results obtained from this cavitation erosion test are as follows:
(1) Test liquid temperature of nearby specimen was measured by using digital thermometer, and observation time was done at 1min. later of testing and 1min. before of finishing. In the result, the case of standard test show up changing temperature of ±2℃, but modified test appear to change temperature of ±9℃.
(2) Weight loss between metals and coated composite materials was compared with standard test(ASTM G-32) and modified test. Weight loss of metals obtained from modified test was 40-60% lower than that of standard test. On the other hand, the weight loss of coated composite materials obtained from modified test has a tendency to decrease and below 30% than that of standard test.
(3) It was calculated to estimate weight loss of standard test with weight loss of coated composite materials obtained from modified test. And cavitation erosion between metals and coated composite materials was compared with standard test.
(4) MDPR(Mean depth penetration rate) between metals and estimated amount of coated composite materials by standard test compared with distilled-water and sea-water. Erosion rate was in the order of DL < SUS316L < SS400 ≒ Bronze < Cast iron < CL in distilled-water and in the order of DL ≒ SUS316L < SS400 ≒ Bronze < Cast iorn < CL in the sea- water.
(5) The optimized test condition looked out for comparing with temperature change and weight loss according to various space in modified test.목차
Abstract = 1
Nomenclature = 4
제1장 서론 = 5
1.1 연구배경 및 목적 = 5
1.2 캐비테이션 발생 원인 및 종류 = 7
1.3 진동캐비테이션 실험장치 = 12
1.4 캐비테이션 침식에 대한 방지 대책 = 14
제2장 시험편 제작 및 실험방법 = 15
2.1 실험재료 및 시험편의 제작 = 15
2.1.1 실험재료 = 15
2.1.2 시험편의 제작 = 17
2.2 캐비테이션 실험방법 = 20
2.2.1 표준시험 = 20
2.2.2 개선된 시험 = 23
2.2.3 실？癰疫？ = 28
제3장 실험결과 및 고찰 = 29
3.1 표준시험시 피복복합재 와 금속재 시험편의 파손 원인 = 29
3.2 무게감소량에 의한 시험법의 비교 = 32
3.2.1 금속시험편의 비교 = 32
3.2.2 피복복합재의 비교 = 33
3.3 피복복합재의 추정치와 금속재간의 침식량 비교 = 35
3.3.1 증류수중에서의 캐비테이션 침식거동 = 35
3.3.2 해수중에서의 캐비테이션 침식거동 = 39
3.4 표준시험과 개선된 시험에서 유체온도의 변화 = 42
3.5 개선된 시험에서 시험거리에 따른 시험유체의 온도와 침식량 변화 = 44
3.5.1 개선된 시험에서 거리에 따른 유체온도 변화 = 44
3.5.2 개선된 시험에서 거리에 따른 침식량 변화 = 45
3.6 환경에 따른 캐비테이션 침식표면 형상 비교 = 46
3.6.1 금속재의 침식표면 = 46
3.6.2 피복복합재의 침식표면 = 56
3.6.3 개선된시험에서 거리에 따른 침식 표면 = 62
3.7 캐비테이션 침식에 의한 재료의 표면조직 손상 특성 = 64
3.7.1 환경에 따른 침식면 = 64
3.7.2 표준시험과 개선된 시험에서의 침식면 = 68
3.7.3 개선된 시험에서 거리에 따른 침식면 = 70
제4장 결론 = 72
참고문헌 = 7
A Study on the Treatment of Shipborne Waste Oils by Cavity FluidFluctuation
Get PDFThe rapid growth of world's population and the distinctive development of industrial technologies have recently accelerated marine pollutions. This led to stringent regulations on the marine pollutions. Among the marine pollutions, especially oil-caused pollution has become a severe issue with direct damage such as the demolition of marine ecosystem. Petroleum hydrocarbon, however, is widely applied in large volume, which increases continuously.
Waste oils are one of the sources of marine oil pollution generated from ships. It was currently difficult to treat them the whole quantity within a ship so that they are transferred to a shore treating facility after being collected inside the ship's sludge tank mostly. However, shore transferring method causes cost generation in the economic standpoint, consumes much time, and entails the risk of oil pollution. Accordingly, a fundamental measure in the light of prevention of marine oil pollution would be self treatment in respective ships.
Ultrasonic vibrator is an equipment which atomizes and homogenization the oils by breaking the oil particles with ultrasonic vibration cavity, and would improve the properties. But it has not been yet applied to treat waste oil.
This study intended to investigate a method, as a fundamental preventive measure against oil pollution from ships, to self treat sludge and waste oils unavoidably generated in operating ships. For this, the matrix structures of fuel oil, lubricating oil and sludge oil, which are marine oils, were investigated. These oil solutions from various environments were irradiated with ultrasonic vibration and then observed the aspects of the change of oil particles. From these, the recycling feasibility of sludge oil for usable oil to be burnt was determined.
And, in order to analyze erosion aspect on transducer horn tip, which is a principle part of ultrasonic vibrator, the erosion damage was investigated on weight loss and weight loss rate mainly using SS41, as horn tip material. Also, the erosion damage of metallic material and the homogenization of oil caused by cavitation in the sludge oil environment were identified by investigating the aspect of the erosion of SS41 specimen caused by the impact pressure generated from the demolition of the cavity of ultrasonic vibrator horn.
The important findings from this study are as follows.
1) Waste oils go through homogenization of oil particle by cavitation from ultrasonic vibration, and the effects are good according to the oil temperature increased and the experimental time takes long.
2) Viscosity, pH value, and specific gravity of marine oil decrease by repetition of cavity flow fluctuation. The decrement is larger in the oil with fuel oil property than in the oil with lubricant oil property.
3) The ratio of erosion damage at amplitude 50㎛ was larger over 2 times than that of 24㎛, and the value of rate was larger in fuel oil sludge than in lub. oil sludge.
4) The erosion damage to the increase of oil temperature was decreased in lub. oil sludge but increased in fuel oil sludge to the contrary. Therefore, the demolition pressure of cavity is lower to the increase of oil temperature in lub. oil sludge environment.
5) It was the largest effect of cavity at immersion depth 3mm of transducer horn at oil temperature 30℃ in sludge oil environment. But in case of oil temperature 50℃, 70℃ and 90℃, the effect of cavity was the largest at immersion depth 6mm.
6) As the space of between transducer horn and specimen decreased, the erosion damage and the effect of demolition pressure of cavity were increased.
7) The effect of cavity fluid fluctuation on the homogenization of sludge oil and erosion of SS41 acted larger in the oil environment with fuel oil property than the lubricant oil property.
As these experimental results, it was found that the possibility on the development of ultrasonic breaking systems to recycle waste oils from ships. Also, the optimum conditions were ascertained to obtain the best efficiency according to the environment of oil properties. In addition, it would help investigate the aspect of cavitation erosion damages in varieties of equipment, metallic materials of different operating environment and material characteristics, and also would help establish the countermeasures of cavitation erosion damages.목차
List of Figures = v
List of Photographs = xiii
List of Tables = xiv
Abstract = 1
제1장 서론 = 5
1.1 연구의 배경 및 목적 = 5
1.2 연구의 동향 = 9
1.3 논문의 구성 및 연구방법 = 11
제2장 기본 이론 = 13
2.1 선박 폐유 = 13
2.1.1 선박유류 및 슬러지 = 13
2.1.2 슬러지 발생 = 14
2.2 초음파 = 18
2.2.1 초음파와 응용 = 18
2.2.2 초음파 발생장치 = 19
2.2.3 초음파 강도 = 21
2.3 캐비테이션 = 23
2.3.1 캐비테이션의 정의 = 23
2.3.2 캐비티의 발생 = 24
2.3.3 캐비테이션 거동 = 25
2.3.4 초음파 캐비테이션 = 29
제3장 캐비티 유체 유동에 의한 유류의 균질 효과 및 성상변화 = 32
3.1 서언 = 32
3.2 실험방법 = 34
3.2.1 시료유의 특성 = 34
3.2.2 실험방법 = 35
3.2.3 실험장치 = 36
3.3 결과 및 고찰 = 42
3.3.1 캐비티 유체 유동에 의한 선박유류의 균질 효과 = 42
3.3.2 폐유의 균질 작용에 미치는 유속의 영향 = 52
3.3.3 폐유의 유온 변화에 따른 균질 효과 = 55
3.3.4 폐유 균질 효과에 미치는 진동자 혼의 침지깊이 = 58
3.3.5 캐비티 유체 유동에 의한 선박유류의 성상변화 = 61
3.4 결언 = 65
제4장 = 슬러지유 환경에서 캐비티 유체 유동에 의한 초음파 진동자 혼 선단의 침식 특성 = 67
4.1 서언 = 67
4.2 실험에 응용된 이론 = 69
4.3 실험방법 = 70
4.3.1 시료유 및 시험편의 특성 = 70
4.3.2 실험방법 = 72
4.3.3 실험장치 = 73
4.4 결과 및 고찰 = 75
4.4.1 진동자의 혼 디스크의 캐비테이션 침식에 미치는 유온의 영향 = 75
4.4.2 유온 변화 환경에서 진폭에 따른 무게감소량의 비교 = 80
4.4.3 진폭 24㎛에 대한 50㎛에서의 유온에 따른 무게감소율의 비 = 83
4.4.4 유온 변화에 따른 최고침식율 및 발생시간에 대한 특성 = 86
4.4.5 유온 변화 환경에서 진동자 혼의 침지깊이에 따른 침식양상 = 89
4.4.6 진폭 50㎛인 경우의 최고침식율 및 이에 이르는 시간 비교 = 123
4.5 결언 = 128
제5장 슬러지유 환경 중 일반강의 침식에 미치는 캐비티 유체 유동의 영향 = 130
5.1 서언 = 130
5.2 실험방법 = 132
5.2.1 시료유 및 시험편의 특성 = 132
5.2.2 실험방법 및 장치 = 133
5.3 결과 및 고찰 = 136
5.3.1 유온 변화 환경에서 진동자 혼과의 간격에 따른 시험편의 침식특성 = 136
5.3.2 유온 변화 및 진동자 혼과의 간격에 따른 최고침식율 비교 = 169
5.3.3 진동자 진폭 50㎛와 24㎛에 따른 최고침식율 비교 = 174
5.4 결언 = 175
제6장 결론 = 177
참고문헌 = 180
Appendix = 191
Appendix A = 191
Appendix B = 193
Appendix C = 20
(A) Study on the Risk Management of Container Transport at Sea
Get PDFA Study on the Risk Management of Container
Transport at Sea
This paper aimed to select the appropriate risk management techniques on the risks of container transport at sea based on risk and risk management theory.
Risks are defined as uncertainty concerning the occurrence of a loss. There are several kinds of risks, but they are mainly divided into pure risks and speculative risks. Speculative risks are those risks where there is a chance for gain as well as loss, but pure risks have no chance of gain but only the possibility of loss.
Risk management can be defined as a systematic process for the identification and evaluation of pure loss exposure faced by an organization or individual, and for the selection and administration of the most appropriate techniques for treating such exposures.
Risk management places greater emphasis on the identification and analysis of pure risks. The major types of pure risks are associated with personal risks, property risks, and liability risks.
In order to attain the preceding goals and objectives, the risk manager must take certain steps in the risk management process as follows.
① Identifying potential losses
② Evaluating potential losses
③ Selecting the appropriate techniques or combination of techniques for treating loss exposures
Risks of container at sea transport are widely divided into three categories, such as, risk of container itself, risk of container cargo and liability to third party. This paper places emphasis on the risks of container transport at sea as well as limits its scope from container terminal to container terminal.
In this study, container accidents were analysed by Heinrich's Domino theory centering around case study through the Damage Report of Surveyor on container accidents at sea transport carried out.
In conclusion, according to Damage Report, most cases are wet damages and burning etc., which are usually covered by insurance less customary deductible. So in this papers studied about insurance management for container transport at sea. Therefore we have to make a constant effort to prevent such loss as a pre-loss control
A Study on the Restructure of Multi-Platform Databases for MIRAS
Get PDFIt is important to retrieve information that a user requires on the web. The web is an open system. The amount of information is increasing rapidly. While each of information was compiled into the database piece at a single platform in the past, it is now compiled into complicated structure at a multi-platform. Restructuring the multi-platform database is needed to efficiently retrieve information. MIRAS (Meta Information Retrieval Agent System) has a multi-platform database on the web. This study applies the classification of the existing sites' categories to restructure the database systematically. The empirical analysis shows that the suggested method is effective for information retrieval and multi-platform database restructuring. This study helps users to save on time-cost of searching information.목차
I 서론 = 1
1. 연구의 개요 = 1
2. 연구의 목적 및 범위 = 1
3. 논문의 구성 = 2
II 이론적 배경 = 3
1. 에이전트 = 3
1.1 에이전트의 정의 = 3
1.2 고객-서버 모형에서의 에이전트의 필요성 = 3
2. 정보검색 = 4
2.1 단일플랫폼의 정보검색 = 4
2.2 다중플랫폼의 메타 검색 = 4
2.3 데이터베이스의 선택문제 = 5
2.4 문서 분류 및 카테고리 = 6
3. MIRAS의 정의 및 구조 = 7
III MIRAS의 실험설계 및 데이터베이스 구조 분석 = 10
1. MIRAS 실험설계 = 10
2. MIRAS의 성능 평가 = 11
3. 사전(事前) 카테고리 구조 = 12
4. 실험검색키워드 = 14
IV 데이터 수집 및 분석 = 16
1. 데이터 수집 환경 = 16
2. 카테고리간의 관련도 = 17
3. 키워드와 카테고리간의 관련도 = 20
V MIRAS의 검색 및 성능 평가 = 22
1. MIRAS의 검색 = 22
2. MIRAS의 데이터 분석 = 24
3. MIRAS의 성능 분석 = 28
VI 결론 = 3