71,348 research outputs found
Synthetic Aperture Imaging Using High-Frequency Convex Array for Ophthalmic Ultrasound Applications
No full textHigh-frequency ultrasound (HFUS) imaging has emerged as an essential tool for pre-clinical studies and clinical applications such as ophthalmic and dermatologic imaging. HFUS imaging systems based on array transducers capable of dynamic receive focusing have considerably improved the image quality in terms of spatial resolution and signal-to-noise ratio (SNR) compared to those by the single-element transducer-based one. However, the array system still suffers from low spatial resolution and SNR in out-of-focus regions, resulting in a blurred image and a limited penetration depth. In this paper, we present synthetic aperture imaging with a virtual source (SA-VS) for an ophthalmic application using a high-frequency convex array transducer. The performances of the SA-VS were evaluated with phantom and ex vivo experiments in comparison with the conventional dynamic receive focusing method. Pre-beamformed radio-frequency (RF) data from phantoms and excised bovine eye were acquired using a custom-built 64-channel imaging system. In the phantom experiments, the SA-VS method showed improved lateral resolution (>10%) and sidelobe level (>4.4 dB) compared to those by the conventional method. The SNR was also improved, resulting in an increased penetration depth: 16 mm and 23 mm for the conventional and SA-VS methods, respectively. Ex vivo images with the SA-VS showed improved image quality at the entire depth and visualized structures that were obscured by noise in conventional imaging.11Ysciescopu
Six unrecorded macrofungi from the Royal Tombs (Donggureung and Seooreung) of the Joseon Dynasty and Jongmyo Shrine, Korea
No full textCho, Hae Jin, Lee, Hyun, Li, Vladimir, Jargalmaa, Suldbold, Kim, Nam Kyu, Lim, Min-Ji Kim and Young Woon (2018): Six unrecorded macrofungi from the Royal Tombs (Donggureung and Seooreung) of the Joseon Dynasty and Jongmyo Shrine, Korea. Journal of Species Research 7 (1): 1-8, DOI: 10.12651/JSR.2018.7.1.00
A Study on the Gastronomic Writings of Lim Kim Chern the Sinophone Malaysian Writer
No full textIn recent years, Chinese Malaysian gastronomic writings continues to expand in scope. This thesis chooses Chinese Malaysian writer Lim Kim Chern's gastronomic writings as the study subject. With the aid of Chinese Malaysian historical background knowledge, this thesis analyzes the main topics and connotation of Lim Kim Chern's gastronomic writings to peek at his ideas and feelings in order to understand the development of contemporary Chinese Malaysian gastronomic writings.
Although Lim Kim Chern's gastronomic writings focuses on food, I believe that the emphasis beneath the surface is on "tradition" and "culture" in Malaysia, as well as Chinese Malaysian's sense of identity. These three topics are extremely important for Chinese Malaysian, so this thesis's second chapter expounds the three topics to provide an insight into the central idea behind his gastronomic writings.
Lim Kim Chern's gastronomic writings repeatedly emphasizes the two ideas that "food is a mobile historical relic" and "it is a journey of taste", both of which has mobility as a common theme. Food is like a historical relic, but it's a kind of historical relic that can travel around the world. What we are tasting is not just delicious food, but also history and culture. "Journey of taste" includes everything mentioned above. More importantly, a large part of people's feelings towards food derives from their own ethnic background and traditions. Therefore, no matter where in the world we are, hometown food always invokes a sense of nostalgia. I will explore the writer's emotional memory and his views on gastronomic writings.
Chinese Malaysian's sense of identity has always been one of the key topics explored by Chinese Malaysian writers. Chinese Malaysian's position in society is complex and diverse, so we must study the past and present in order to understand it. I found that Lim Kim Chern's choice of words in his writings occasionally relates to Chinese Malaysian identity, so this paper will also analyze the relationship between the writer's literature and Chinese Malaysian's sense of identity.
Lim Kim Chern's gastronomic writings includes both food journals and prose, so I will use both "form" and "heart" (the latter as a metaphysical description) to carefully analyze Lim Kim Chern's gastronomic writings. The objective of the analysis is to bring out the writer's central idea. I hope that this thesis will be able to contribute to Chinese Malaysian gastronomic writings
A multi-scale non-deterministic approach to composite curing process simulation
No full textThermosetting matrix composite materials are often subject to a curing process to enhance the mechanical properties of the final product.In recent years computational models of the curing process allowed for a remarkable time and cost compression with respect to trial and error procedures. Most of the proposed models, however, rely on deterministic hypothesis. In this paper a multi-scale non deterministic approach to cure process simulation has been proposed, evidencing the effect of stochastic perturbations of fibers distribution on simulative results on macro-scale
Acoustic Power Transfer Using Self-Focused Transducers for Miniaturized Implantable Neurostimulators
No full textAn emerging neurostimulation therapy utilizes electroceuticals to treat numerous neurological disorders. With the aim to discover novel clinical applications of neural stimulation, device miniaturization has been a key challenge for successful clinical translation of implantable stimulators. The battery size has been a limiting factor in further miniaturization, so wireless power transfer without the use of an implanted battery has gained interest. Among various power transfer techniques, acoustic power transfer (APT) provides substantial benefits for powering implantable devices due to its proven safety and efficiency for human body penetration. In this study, we proposed an APT-based neurostimulator with an integrated self-focused 3.6 MHz acoustic transducer and a receiver circuit composed of a power management module and pulse generator. The size of the entire device was 8 mm × 8 mm ×8.6 mm, which is small enough to be implanted with a small incision. A focused beam generated by an external transmitter was received by another focused beam from a receiver transducer, and this optimized pair of transducers with a receiver circuit generated 1.5 V, 1.3 ms pulse trains, which successfully transmitted stimulation pulses. We adopted a 1–3 composite with a piezolayer to implement a curved aperture, which enabled less-attenuated, focused, and matched beams for maximization of power transfer efficiency. We evaluated APT performance through rigorous bench-top and phantom tests and demonstrated the feasibility of stimulation through an in vivo experiment of sciatic nerve stimulation using a rat model.11Ysciescopu
Mechanical Characterization of AA2024-T3 FSWed Butt Joints
No full textIn recent years friction stir welding process has received a great deal of attention from the transport industry. During the process, heat generation and material stirring induce significant microstructural alteration in the base material, affecting the properties of the welded assembly. In this paper the influence of process parameters, namely rotating speed and welding speed, on mechanical properties of AA2024-T3 friction stir butt welds is experimentally investigated. An increase of the yield stress has been found decreasing the heat input, while an opposite variation was measured for the elongation
Interventions for Neglect With Stroke: A Systematic Review
No full textAbstract
Date Presented 3/31/2017
Using the key terms stroke, neglect, and intervention, we systematically examined 14 studies included in our analysis. This review will provide direction and an evidence base for occupational therapy in hospital settings.
Primary Author and Speaker: Seok Beom Ko
Additional Authors and Speakers: Ju Hee Kim, Moon Young Kim, Hae Yean Park</jats:p
Jong Lim, Kim
No full text학위논문(석사)--아주대학교 일반대학원 :경영학과,2010. 2본 논문의 목적은 통화옵션인 키코(KIKO : Knock-In-Knock-Out) 옵션의 개념과 구조를 이해하고 KIKO 옵션의 가격을 결정하는 것이다. 환율이 기하브라운 운동(Geometric Brownian Motion)을 따른다고 가정하고, 몬테칼로 시뮬레이션(Monte Carlo Simulation)을 이용하여, 4가지 이자율 모형 하에서 키코 옵션의 발행자입장(예: 은행)에서의 가격을 비교한다.
칼만 필터(Kalman Filter) 방법을 적용하여 국내·국외 이자율 기간구조의 모수를 추정한다. 국내·국외 이자율은 각각 1요인 바시첵 모형(1-factor Vasicek model), 무상관 2요인 바시첵 모형(uncorrelated 2-factor Vasicek model), 1요인 CIR 모형(1-factor CIR model), 무상관 2요인 CIR 모형(uncorrelated 2-factor CIR model)으로 4가지 경우의 이자율 모형을 따른다고 가정한다.
실증분석에서 이자율 모수추정의 결과는 2-factor 모형 하에서 추정한 국내·국외 이자율의 모수들이 1-factor 모형 하에서 보다 이자율을 정확하게 추정한다는 것을 보여준다. 그러나 Vasicek 모형과 CIR 모형 중 특정한 하나의 모형이 더 정확하게 이자율을 추정한다고 볼 수 없다.
키코 옵션 가격 결정의 결과는 환율의 변동성이 증가할수록 각각의 이자율 모형 하에서 키코 옵션 가격이 단조 증가하는 결과를 보여주고, 양국(한/미)간에 이자율 차이가 클수록 키코 옵션 가격의 크기가 높게 나타난다. 또한 이자율이 무상관 2요인 바시첵 모형을 따르는 경우 나타날 수 있는 음(-)의 이자율이 키코 옵션 가격을 높이는 경향을 보인다.
키코 옵션은 환율의 변동성이 증가할수록 발행자가 이익을 얻을 확률이 크게 증가하고 또 그 이익 규모 역시 크게 증가하는 것으로 나타난다. 하지만 이는 본 논문에서 가정한 특정한 모형 하에서의 결과이므로 이를 일반적으로 받아들일 수는 없다. 추후 다른 모형 하에서의 연구가 필요할 것이다.[본문 차례]
제 1장 서 론 6
제 1절 연구의 배경 및 목적 6
제 2절 논문의 구성 7
제 2장 KIKO 옵션 8
제 1절 KIKO 옵션이란 8
제 2절 KIKO 옵션 구조 8
- 수출기업의 KIKO (Knock-In-Knock-Out) 옵션거래의 예시
제 3절 KIKO 옵션의 가격결정 11
- 몬테칼로 시뮬레이션(Monte Carlo Simulation)을 이용하여
제 3장 이자율 기간구조 모형 16
제 1절 이자율 기간 구조 16
1항. single-factor 지수-선형 기간구조 모형 16
2항. multi-factor 지수-선형 기간구조 모형 17
제 2절 이자율 모형 18
1항. 1-factor Vasicek 모형 18
2항. Uncorrelated 2-factor Vasicek 모형 20
3항. 1-factor CIR 모형 21
4항. Uncorrelated 2-factor CIR 모형 22
제 4장 이자율 모수 추정 24
제 1절 칼만 필터(Kalman Filter) 24
제 2절 칼만 필터를 이용한 이자율 모수 추정 과정 28
제 5장 실증분석 32
제 1절 표본자료 32
제 2절 이자율 기간구조 모수 추정 결과 36
제 3절 KIKO 옵션 가격결정 결과 44
제 6장 결론 50
[그림 차례]
KIKO 옵션의 손익구조(발행자 입장) 10
칼만 필터(Kalman Filter) 과정 27
국내 금리 32
미국 금리 33
국내 금리의 시계열 34
미국 금리의 시계열 34
2002년 1월 ~ 2007년 12월 환율 35
2008년 3월 31일 ~ 2008년 3월 31일 환율 35
국내 금리의 1-factor Vasicek model 칼만 필터 추정 40
미국 금리의 1-factor Vasicek model 칼만 필터 추정 40
국내 금리의 1-factor CIR model 칼만 필터 추정 41
미국 금리의 1-factor CIR model 칼만 필터 추정 41
국내금리의 Uncorrelated 2-factor Vasicek model
칼만 필터추정 42
미국금리의 Uncorrelated 2-factor Vasicek model
칼만 필터추정 42
국내금리의 Uncorrelated 2-factor CIR model
칼만 필터추정 43
미국금리의 Uncorrelated 2-factor CIR model
칼만 필터추정 43
KIKO 옵션 가격결정 결과 그래프 45
[표 차례]
KIKO 옵션거래의 예시 9
이자율 프로세스 가정 11
1-factor Vasicek model 12
Uncorrelated 2-factor Vasicek model 12
1-factor CIR model 12
Uncorrelated 2-factor CIR model 13
국내 금리 수익률의 기초 통계량 33
미국 금리 수익률의 기초 통계량 33
1-factor Vasicek model 모수 추정결과 36
1-factor CIR model 모수 추정결과 36
Uncorrelated 2-factor Vasicek model 모수 추정결과 37
Uncorrelated 2-factor CIR model 모수 추정결과 37
KIKO 옵션 가격결정 결과 44
이자율 차이() 통계량 48
음(-)의 이자율을 0으로 제한했을 때의 KIKO 옵션 가격결과 49MasterThe purpose of this paper is to understand the concept and structure of KIKO (Knock-In-Knock-Out) options, which is known as one of currency options, and to price KIKO options. We assume that the exchange rate follows Geometric Brownian Motion. Using 4 interest rate models, we compute and compare KIKO option's prices, in option writer's view, using Monte Carlo Simulation.
We used Kalman Filter method to estimate parameters of domestic and foreign interest rates term structure. Domestic and foreign interest rate is assumed to follow 4 interest rate models, such as 1-factor Vasicek model, uncorrelated 2-factor Vasicek model, 1-factor CIR model, and uncorrelated 2-factor CIR model.
Empirical results show that (i) parameters of interest rate models estimated under 2-factor models are more accurate than under 1-factor model in estimating interest rates. But, (ii) we can't say that which one model of Vasicek and CIR, is better to estimate interest rates.
According to the results of KIKO option pricing, (i) KIKO option prices increases monotonically as volatility of the exchange rate increases under all 4 models, and secondly, (ii) KIKO option prices are likely to be high when the difference of domestic and foreign interest rates are large. Thirdly, (iii) negative interest rates tend to yield greater KIKO option price under uncorrelated 2-factor Vasicek model.
In KIKO options, as volatility of the exchange rate increases, the probability that option writers would be better-off increases and also the volume of profit can be huge. However, this result is based on the certain models assumed in this paper, so we can't accept this as a general result. Further research under different models will be needed
Piptoporellus soloniensis B. K. Cui, M. L. Han & Y. C. Dai, Fungal Diversity
No full textPiptoporellus soloniensis (Dubois) B.K. Cui, M.L. Han & Y.C. Dai, Fungal Diversity 80(1): 343 (2016) Hierarchy: Basidiomycota, Polyporales, Fomitopsidaceae Specimens examined: KOREA, Gyeonggi-do, Guri-si, Donggureung, 37°36 ʹ 50 ʺ N, 127°07 ʹ 51 ʺ E, 11 Aug 2015, Hae Jin Cho, Young Woon Lim, SFC20150811-40 (GenBank accession No. MF445223), on the dead branch of broad-leaved tree; KOREA, Seoul, Jongmyo shrine, 37°34 ʹ 26 ʺ N, 126°59 ʹ 44 ʺ E, 9 Jun 2016, Nam Kyu Kim, Young Woon Lim, SFC20160609-02 (GenBank accession No. MF 445224), on the dead log of Quercus spp.; KOREA, Gyeonggi-do, Guri-si, Donggureung, 37°37 ʹ 15 ʺ N, 127°07 ʹ 33 ʺ E, 12 Aug 2016, Young Woon Lim, SFC 20160812-18 (GenBank accession No. MF 445225), on the fallen branch of broad-leaved tree. Basidiocarps annual, pileate, solitary, corky, hard corky and light in weight when dry. Pileus 70-200 mm, dimidiate, semicircular, applanate to slightly convex, surface sponge-like when young, warty in age, sometimes slightly zonate near margin, orange white (6A2) to light orange (5A5), partly orange red (8A7) when young. Pore surface yellowish white to cream, pores round to angular or irregular, 3-4 per mm, dissepiments entire. Hyphal system dimitic, generative hyphae with clamp connections. Generative hyphae in context rare, hyaline, thin-walled, sometimes branched, 2.5-3.5 μm in diam. Skeletal hyphae in context abundant, thick-walled, sometimes branched, 2-6 μm in diam. Generative hyphae in tube hyaline, thin-walled, sometimes branched, 2.5-3.5 μm in diam. Skeletal hyphae in tube dominant, thick-walled, flexuous, 2-3 μm in diam. Cystidia absent. Cystidioles present. Basidia 14.0-17.2-22.4 × 5.6-6.6- 7.6 μm, clavate, 4-spored, clamp connection at the base. Basidiospores 5.2-5.4-5.7 × 3.0-3.1-3.3 μm, Q = 1.43- 1.56-1.67, ellipsoidal to oval, apiculus acute. Remarks: Piptoporellus soloniensis was misidentified to Laetiporus sulphureus in Korea. However, they can be distinguished by type of attachment to the substratum and basidiospore shape. Piptoporellus soloniensis forms almost solitary basidiocarps and its shape is applanate to slightly convex and has ellipsoidal to oval basidiospore. However, L. sulphureus forms almost imbricate and has a guttate basidiospore shape (Ota et al., 2009).Published as part of Cho, Hae Jin, Lee, Hyun, Li, Vladimir, Jargalmaa, Suldbold, Kim, Nam Kyu & Lim, Min-Ji Kim and Young Woon, 2018, Six unrecorded macrofungi from the Royal Tombs (Donggureung and Seooreung) of the Joseon Dynasty and Jongmyo Shrine, Korea, pp. 1-8 in Journal of Species Research 7 (1) on pages 6-7, DOI: 10.12651/JSR.2018.7.1.001, http://zenodo.org/record/812041
Defect-related luminescence of Mg-doped n-GaN grown by hydride vapour-phase epitaxy
No full textWe study photoluminescence (PL) and photoluminescence excitation (PLE) spectra of Mg-doped n-GaN grown by hydride vapour-phase epitaxy. Defect-related red and blue emission bands around 1.85 eV and 2.90 eV, respectively, are observed in addition to the yellow emission band. The red and the blue emission bands are attributed to the recombinations involving the same Mg-related defects according to the result of the thermal annealing experiment. The PLE spectra of the red, the yellow,and the blue emission bands show that all of these emission bands can be interpreted in terms of a configuration coordinate (CC) diagram. The blue emission at 2.90 eV is attributed to the transition from the conduction band to the Mg-related deep accepters. The CC diagram shows that the yellow luminescence is due to the transition from a deep donor state to a shallow acceptor state. A possible origin of the deep donor level is also discussed.This work was partially supported by the KOSEF through the SPRC in Jeonbuk National
University and the BSRI program (97-2419) of the Korean Ministry of Education
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