1,721,889 research outputs found
Deflection of reinforced concrete beam under low-velocity impact loads
No full textAccidents due to low-velocity impact loading are no longer uncommon these days. Accordingly, although evaluation criteria for regulating the global behavior of major structures are required to ensure sufficient impact resistance, to date the criteria have not been specified. Although several studies have suggested empirical formulae for evaluating the deflection of reinforced concrete (RC) beams from drop weight impact tests, the derivation of these formulae suffer limited impact energy ranges and few investigated parameters. To overcome these limitations, 15 RC beams were tested in this study under drop weight impact loading with five variables: impact energy, drop weight momentum, static flexural capacity, cross-section size, and concrete strength. The limitations of the previous studies were experimentally verified, and an empirical formula was newly proposed based on the test results. Furthermore, the validity of both the experimental results and our new empirical formula was analytically verified through parametric studies.N
공동에 포획된 원자를 이용한 양자정보처리
No full text학위논문(박사) - 한국과학기술원 : 물리학과, 2005.2, [ vi, 64 p. ]Quantum information processing has originated from new insight that a quantum state serves as a sort of information. The peculiar nature of the quantum world opens up the way to achieve a number of tasks which have no classical counterparts. They include perfectly secure communication, exponential speedup of some computations, and so on. Despite the fruitful results, quantum information processing is very difficult to be realized with a physical system due to the sensitivity of quantum states and quantum operations.
In this dissertation, quantum information processing is briefly introduced, and systems of cavity-trapped single atoms are considered as candidates for physical realization of it. Especially, various single photon input-output processes in the atom-cavity system are presented, and it is shown that they can serve as the essential ingredients for various modes of quantum information processing, such as for conversion and controlled unitary operation between an atomic qubit and a photonic qubit. In that context, new schemes for quantum teleportation of atomic states and for quantum gates between distant atomic qubits are proposed and analyzed both theoretically and numerically concerning various physical and experimental aspects.한국과학기술원 : 물리학과
A study on the real-time feedrate optimal adjustment system for CNC end milling
No full text학위논문(석사) - 한국과학기술원 : 기계공학전공, 2003.2, [ x, 62 p. ]한국과학기술원 : 기계공학전공
Quantum-classical correspondence in the delta kicked rotator
No full text학위논문(석사) - 한국과학기술원 : 물리학과, 2001.2, [ [ii], 22 p. ]한국과학기술원 : 물리학과
Effect of maximum coarse aggregate size on dynamic compressive strength of high-strength concrete
No full textDynamic increase factor (DIF) is a measure of the rate effect in the analysis and design of structures subjected to impact or impulsive loads. A variety of DIFs have been suggested based on the results of split Hopkinson pressure bar (SHPB) tests, which is the test technique most commonly used to obtain dynamic material properties. However, due to the lack of a standard test method and some limitations in the SHPB equipment, most SHPB tests have been conducted for mortar or concrete specimens containing small size coarse aggregate that is very different from the actual concrete used in construction. The DIFs that are provided in most structural design codes are based on these test results. Therefore, it is necessary to investigate the effect of coarse aggregate size on the dynamic concrete compressive strength. In this study, a series of SHPB tests were conducted for mortar and concrete specimens with various maximum aggregate sizes. The test results indicated that the larger maximum coarse aggregate sizes induce larger heterogeneity of specimens. On the other hand, the pure rate DIFs did not exhibit a dependency on the maximum coarse aggregate size. Based on these results, guidance as to the maximum coarse aggregate size of concrete specimens for SHPB tests is provided.N
Effect of Reinforcing Steel on the Impact Resistance of Reinforced Concrete Panel Subjected to Hard-Projectile Impact
No full textExperimental and numerical studies were conducted to investigate the effect of reinforcing steel on the impact resistance of reinforced concrete structures and to reveal its mechanism. Hard-projectile impact tests using a single-stage gas gun were performed with reinforced concrete panels to simulate a nuclear power plant structure. Parametric analysis was conducted with a numerical model that applied a finite element method coupled with smoothed particle hydrodynamics using the following four variables: the impact velocity of the projectile as well as yield strength, spacing and diameter of the reinforcing steel. The experimental and numerical analysis results indicated that the impact resistance was significantly affected by the spacing of the reinforcing steel, but not by the yield strength or the diameter of the reinforcing steel. Narrower rebar spacing improved the impact resistance due to the enhanced confining and fragment trapping effects.N
Influence of friction on the dynamic increase factor of concrete compressive strength in a split Hopkinson pressure bar test
No full text© 2022 The AuthorsThis study includes the experimental and numerical research conducted to establish a standardized lubrication technique for a concrete split Hopkinson pressure bar (SHPB) test. Concrete SHPB tests were conducted using different quantities of high-vacuum grease, petroleum jelly, and Teflon to determine a desirable lubrication method. Subsequently, follow-up concrete SHPB tests with different specimen dimensions were performed to validate the proposed lubrication method and obtain a dynamic increase factor (DIF) exclusively with respect to the rate effect (that is, pure rate DIF). Furthermore, the pure rate DIF was verified through finite element analysis of the SHPB tests. The experimental and numerical outcomes demonstrated that the frictional effect was eliminated in the concrete SHPB test when a lubricant more than or equal to 12 mg/cm2 was applied to the specimen irrespective of the lubricant type.Y
Scaled Model Test for Efficient Arrangement of Steel Reinforcement in Bridge Pier Caps
No full textBecause variations associated with the strut-and-tie model (STM) in the design of pier caps could lead to over-reinforcement of steel rebars, special attention should be paid to using STMs for reasonable rebar arrangements. Here, static loading tests were conducted on three scaled-model specimens of bridge pier caps to investigate the efficient arrangement of steel reinforcement in the bridge pier cap design. To determine the effect of the loading condition on the pier cap behavior, T-type pier caps with two or four support bearings were tested under realistic boundary conditions, using three hydraulic actuators. The tested load-resistance capacities were compared with the STM predictions. The study revealed that the arrangement of vertical ties in the STM along the shear critical section in the column's vicinity could induce excessive vertical shear reinforcement. The experimental results showed that all specimens designed using the STM with no unnecessary vertical ties exhibited flexure failure without any sudden shear failure. The effect of load distribution on the pier cap behavior was evaluated using different numbers of support bearings.N
초파리 모델 시스템에서 파킨 단백질이 매개하는 감염과 상처 발생에 대한 생체 내 반응과 TSPO-VDAC 복합체의 상호작용
No full textParkin, an E3 ubuquitin ligase associated with Parkinson's disease (PD), has recently been implicated in mediating innate immunity. However, molecular details regarding parkin-mediated immune response remain to be elucidated. Here, we identified mitochondrial TSPO-VDAC complex to genetically interact with parkin in mediating responses against infection and wound in Drosophila. The loss-of-function mutation in parkin results in defective immune response against bacterial infection. Additionally, parkin mutant larvae showed hypersensitivity against wound regardless of bacterial infection. Interestingly, the combinatorial trans-heterozygotic mutations in parkin and TSPO, or parkin and VDAC showed similar lethal tendency with parkin homozygous mutants. Furthermore, knockdown of TSPO alone also resulted in defective responses to infection and wound analogously to parkin mutants. Taken together, we propose that parkin cooperates with TSPO-VDAC complex to mediate responses against infection and wound. ⓒ 2016 DGISTⅠ. INTRODUCTION 1 --
Ⅱ. MATERIALS AND METHOD 3 --
2.1. Fly strains 3 --
2.2. Prediction of transmembrane domain of dTSPO 3 --
2.3. Infection and injury experiment 3 --
2.4. Analysis of survival rate 4 --
2.5. Single colony isolation of remaining bacteria inside the body after infection 4 --
2.6. RNA extraction, cDNA synthesis, reverse transcription-PCR (RT-PCR) and quantitative PCR (qPCR) 5 --
Ⅲ. RESULT 6 --
3.1. Parkin loss-of-function mutation induces defects in immune defense and wound repair 6 --
3.2. Parkin and mitochondrial protein TSPO genetically interact in mediating immune response 8 --
3.3. Loss of TSPO function shows similar defects to parkin mutants in responses to infection and wound 10 --
3.4. Mitochondrial TSPO-VDAC complex is involved in parkin-mediated immune defense 12 --
IV. DISCUSSION 13 --
Figures 16 --
References 35 --
Summary in Korean 39파킨슨 씨 병 (Parkinson’s disease)의 주요 발병 원인 단백질로 알려진 Parkin은 최근 선천성 면역 (Innate immunity) 반응의 매개에 관여한다고 보고 되고 있다. 하지만 parkin 단백질이 매개하는 선천성 면역 반응의 자세한 분자 수준적 기전은 아직까지 분명히 밝혀진 바가 없다. 본 연구에서 우리는 미토콘드리아 막 (mitochondrial membrane)에 존재하는 TSPO-VDAC 복합체가 감염 (infection)과 상처 (wound)로 인하여 유도 되는 선천성 면역반응의 매개 수준에서 유전적으로 parkin과 함께 상호작용하여 관여한다는 것을 초파리 모델 시스템 (Drosophila model system)을 사용하여 밝혀 내었다. Parkin 유전자에 돌연변이 (mutation)이가 발생하여 기능을 상실하게 되면 박테리아 감염 (bacterial infection) 시 발생하는 면역 반응에 결함이 생긴다는 것을 알게 되었다. 게다가, 이 단백질의 돌연변이가 생긴 초파리 애벌래 (larvae)는 박테리아 감염이 일어나지 않고 상처만 생겨도 과민감성 (hypersensitivity)을 보여서 높은 치사율 (lethality)을 보이는 것을 관찰할 수 있었다. 흥미롭게도, 박테리아 감염 시 parkin과 TSPO 혹은 parkin과 VDAC 각각의 이형 접합적 돌연변이체 (heterozygous mutant)가 결합하여 만들어진 이중 이형 접합적 돌연변이체 (trans-heterozygotic mutations)가 parkin 단백질 단독의 동형 접합적 돌연변이체 (homozyogous mutant)와 유사한 치사율 경향성 (lethal tendency)을 보이는 것을 발견하였다. 이는 parkin과 TSPO 그리고 parkin과 VDAC이 서로 유전적으로 상호작용할 수 있음을 간접적으로 보여주는 결과이다. 더욱이, TSPO 유전자의 활성화를 낮춘 실험군 (knockdown of TSPO) 또한 감염과 상처에 대한 면역 반응에 결함이 parkin 단백질 단독의 동형 접합적 돌연변이체 실험군과 같은 경향성으로 나타나는 것을 확인하였다. 종합하면, 우리는 parkin이 TSPO-VDAC 복합체와 함께 외부 위험물질로 인한 감염과 상처에 방어를 위해 유도되는 면역 반응을 매개한다는 것을 새롭게 밝혀내었다. ⓒ 2016 DGISTMasterdCollectio
압전센서를 사용한 인공와우시스템 신호처리설계
No full textToday, the cochlear implant system is the most successful auditory prosthesis for the patients suffering hair cell loss or damage. The current cochlear implant system consists of an implantable electrode array for the stimulation and an external signal processor includ-ing a microphone and a battery. However, the conventional cochlear implant system is composed of a heavy signal processor. Furthermore, the exposure of an external signal processor causes a cosmetic problem to the patients. Therefore, the cochlear implant sys-tem is required to reduce size and power consumption.
In the thesis, to realize the implementation of an entirely implantable cochlear sys-tem, the signal processing system is studied when a piezoelectric sensor is employed. When a mechanical stress is applied, the piezoelectric sensor produces an electrical charge. The acoustic sounds picked up by the piezoelectric sensor are amplified and transmitted to the microprocessor. The microprocessor used the CC430F6137. This system is a multi-channel system and applied the continuous interleaved sampling (CIS) algorithm to make a charge-balanced biphasic pulse. Also, this system is referred to as miniaturized system comprised of sensing, processing, and actuating functions which are combined on-to a single board. Building a complete printed circuit board (PCB) involves hardware (H/W) and software (S/W) design. The proposed signal processing system embedded with PCB has been tested and verified for future animal experiment. ⓒ 2014 DGISTⅠ. Introduction 1
--
Ⅱ. Backgrounds 3
--
2.1 Auditory System 3
--
2.2 Hearing Loss 6
--
2.3 History of Cochlear Implant Systems 8
--
Ⅲ. Cochlear Implant System 10
--
3.1 Typical Cochlear Implant System 11
--
3.1.1 Microphone & Signal Processor 11
--
3.1.2 Transmission Link 12
--
3.1.3 Electrode Array 13
--
3.2 Biphasic Pulse 13
--
3.2.1 Continuous Interleaved Sampling Algorithm 14
--
3.3 Entirely Implantable Cochlear System 16
--
3.3.1 Piezoelectric Sensor 17
--
3.3.2 Proposed System 19
--
Ⅳ. System Implementation 20
--
4.1 Block Diagram 20
--
4.2 MATLAB Simulation 21
--
4.3 System Development 23
--
4.3.1 Component Selection 24
--
4.3.2 Hardware Design 26
--
4.3.3 Software Design 30
--
4.4 Result of Printed Circuit Board (PCB) 31
--
4.5 Experiment of Signal Processing Board 32
--
Ⅴ. Conclusion & Future Work 34
--
Ⅵ. References 35
--
Korean Abstract 38
--
Acknowledgement 40감각신경성 난청질환은 인간의 내이에 있는 청각세포가 손상되어 발생되는 증상으로써 현재 가장 적절한 치료법으로는 인공와우 시술이 있다. 인공와우는 청각신경에 직접 전기적 자극을 주는 방식으로 난청을 해결한다. 이와 같은 인공와우 시스템은 외부의 소리를 전기적 자극의 형태로 변환해주는 외부 신호처리부가 핵심이다. 하지만 인공와우를 사용하고 있는 환자들은 외부 신호처리부가 쉽게 노출되는 것을 꺼리며, 자주 배터리를 교체하는 것에 불편함을 느낀다.
인공와우 연구에서 외부 신호처리부를 작고 저전력으로 동작하게 하려는 연구가 활발히 진행 중이다. 최근 압전소자를 활용한 인공와우 시스템이 제안되었으며, 본 연구에서도 압전센서를 사용한 완전삽입형 인공와우 시스템을 다루었다. 제안된 시스템에서 압전효과는 외부의 물리적 힘에 의해 압전소자가 기계적 변형을 일으키면서 전기적 신호를 발생시키는 원리이다. 이와 같은 압전소자는 기존 시스템에서 많은 비중을 차지하고 있는 마이크로폰 및 외부 신호처리부의 소형화뿐만 아니라 저전력동작을 가능하게 한다.
본 연구에서 사용된 압전센서는 미세전자기계시스템 (micro electro me-chanical systems, MEMS)을 통해 제작되며, 인공와우 신호처리에서 주파수 분리 기능을 수행한다. 따라서 완전삽입형 인공와우 시스템에서 신호처리는 압전센서의 주파수 분리 기능을 제외한 나머지 역할을 처리한다. 현재 제작된 압전센서는 주파수 대역별로 여러 채널이 존재하며, 해당 대역의 신호가 인가되면 특정 빔이 반응하여 전기적 신호를 발생시킨다. 이에 신호처리부는 이 신호를 사용하여 청각신경이 자극 받을 수 있는 형태로 변환해주는 것이 목적이다.
본 연구의 목표는 기존 마이크로폰의 역할을 대체하는 압전센서를 사용한 신호처리부의 구현이며, 향후 동물 청각인지 실험에서 사용 될 프로토타입 (prototype) 형태의 신호처리 보드의 제작이다. 개발된 신호처리 보드는 다 채널 시스템에서 성능이 입증된 CIS (continuous interleaved sampling) 알고리즘을 적용하였다. 다만 기존의 CIS 알고리즘과 비교하였을 때, 본 시스템에서는 압전센서가 대역 통과 필터 역할을 수행하는 차이점이 있다. 결론적으로 완전삽입형 인공와우 시스템에서 압전센서를 적용한 현재의 보드는 신호처리의 기능적 구현이었다. 향후 제작될 신호처리 보드에서는 ASIC (applica-tion specific integrated circuit)을 적용하여 현재 시스템의 크기 및 전력소모량을 개선시킬 것이다.
ⓒ 2014 DGISTMasterdCollectio
- …
