• Bulletin of the Korean Chemical Society
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• 제21권4호
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• pp.434-440
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• 2000

We present the results of computer simulation for the steady shear flows of rodlike molecules using nonequi-librium molecular dynamics simulation (NEMD) method. The model particle is a rigid rod composed of lin-early connected 6-sites and the Lennard-Jones 12-6 potential governs interactions between sites in different molecules. The system of rodlike molecules exhibits the change of orientational structure, that is, isotropic-nematic transition at high shear rates. We elucidate the nature of the ordered system developed from an isotro-pic phase by steady shear through an analysis of various quantities: orientational order parameters, orientational pair correlation functions, orientational distribution function, and snapshots of configurations. The effects of temperature and density on the shear rate dependence of orientational structure are described.

• 반도체디스플레이기술학회지
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• 제16권2호
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• pp.70-74
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• 2017

Given two stereo images of a scene, it is possible to recover a 3D understanding of the scene. This is the primary way that the human visual system estimates depth. This process is useful in applications like robotics, where depth sensors may be expensive but a pair of cameras is relatively cheap. In this work, we combined our interests to implement a graph cut algorithm for stereo correspondence, and performed evaluation against a baseline algorithm using normalized cross correlation across a variety of metrics. Experimental trials revealed that the proposed descriptor exhibited a significant improvement, compared to the other existing methods.

• Annals of Clinical Neurophysiology
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• 제19권2호
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• pp.125-130
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• 2017

Background: Routine nerve conduction study (NCS) can only be used to evaluate the function of large fibers, and the results of NCS are often normal in patients with distal sensory polyneuropathy. The measurement of the current perception threshold (CPT) has been reported to represent a variety of peripheral nerve fiber functions. This study was performed to investigate the value of measuring CPT in patients with diabetic sensory polyneuropathy who have no abnormalities in routine NCS. Methods: Twenty-seven diabetic patients with sensory polyneuropathy and normal routine NCS and 18 age-matched control subjects participated in this study. The CPT was measured on the unilateral index finger and great toe of each subject at frequencies of 5 Hz, 250 Hz, and 2,000 Hz. Results: CPT values were significantly higher in the patient group than in the control group, especially with stimuli at the lowest frequency of 5 Hz (p < 0.05). There were significant correlations between the CPT values obtained at three different frequencies in the patient group, whereas the correlation was only significant in the pair of 250 Hz/5 Hz (both in the hands and feet), and in the pair of 2,000 Hz/250 Hz (in the feet) for the control group. Conclusions: Our data suggest that the CPT test, especially at a stimuli frequency of 5 Hz, may be a useful screening tool for diabetic polyneuropathy in patients who show no abnormalities in routine NCS.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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• pp.587-592
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• 2002

A new digital correlator fur an airborne synthetic aperture radiometer was designed in order to replace the conventional analog correlator unit which will become very complicated while the number of channels is increasing. The digital correlator uses digital IQ demodulator instead of the intermediate frequency (IF) phase shifter to make the correlation processing performed digitally at base band instead of analogly at IF. This technique has been applied to the digital receiver in softradio. The down-converted IF signals from each pair of receiver channels become low rate base-band digital signals after under-sampled, Digitally Down-Converted (DDC), decimated and filtered by FIR filters. The digital signals are further processed by two digital multipliers (complex correlation), the products are integrated by the integrators and finally the outputs from the integrators compose of the real part and the imaginary part of a sample of the visibility function. This design is tested by comparing the results from digital correlators and that from analog correlators. They are agreed with each other very well. Due to the fact that the digital correlators are realized with the help of Analog-Digital Converter (ADC) chips and the FPGA technology, the realized volume, mass, power consumption and complexity turned out to be greatly reduced compared with that of the analog correlators. Simulations show that the resolution of ADC has an influence on the synthesized antenna patterns, but this can be neglected if more than 2bit is used.

• 한국광학회지
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• 제17권1호
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• pp.47-53
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• 2006

미국 등 세계 여러 나라에서 사용되는 기존의 총기 인식 시스템(Integrated Ballistic Identification System)은 탄흔을 2차원 현미경을 통해 측정, 해석하기 때문에 여러 가지 한계를 가지고 있다. 대표적으로 측정 표면의 거칠기나 기울기 성분, 빛의 조명 각도, 조명 광량의 균일 정도, 표면의 다중 반사나 광학적 특성에 의해 측정 결과가 크게 영향을 받는다. 이로 인해 부정확한 해석을 할 수밖에 없고, 결국 총기 인식 결과의 신뢰성이 떨어진다. 본 연구에서는 이와 같은 단점을 극복하기 위해 조명이나 표면 조건에 영향을 적게 받는 삼차원 형상 측정을 도입했다. 대표적으로 백색광 주사간섭계와 동초점현미경이 사용되었으며, 이런 측정기들은 미국 표준연구소 (National Institute of Standards and Technology, NIST)의 교정 단계를 밟아 보정했다. 그 결과 반복성과 재현성이 뛰어난 측정 결과를 얻을 수 있었다. 또한 본 논문에서 제안하는 3차원 형상 비교 알고리즘을 통해 보다 높은 신뢰도를 갖는 총기 인식이 가능해졌다.

• Progress in Superconductivity
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• 제12권2호
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• pp.110-113
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• 2011

We have grown a Nb/Gd bilayer on a$SiO_2$/Si substrate by using a DC magnetron sputtering system, which was fabricated in situ with silicon stencil masks. In order to investigate proximity effect of the Nb/Gd bilayer, we used a planar tunnel junction with an AlOx tunnel barrier by oxidizing the Al ground electrode at the bottom. A $Co_{60}Fe_{40}$ backing of Al was deposited so as to reduce the superconductivity of the Al, ensuring a normal counterelectrode. With a 50-nm-thick Nb layer, we have measured dI/dV (dynamic conductance) by varying the thickness of Gd, which can reveal the density of states (DOS) of the Nb/Gd bilayer as a function of the Gd thickness resulting from the proximity effect of a superconductor/ferromagnet bilayer (S/F). The SF proximity effect in Nb/Gd will be discussed in comparison to our previous results of the CoFe/Nb, Ni/Nb and CuNi/Nb proximity effect; Gd is expected to show different effects since Gd has f-electrons, while CoFe, Ni, and CuNi have only d-electrons. Our studies will focus on the triplet correlation in a superconducting pair.

• 한국멀티미디어학회논문지
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• 제9권1호
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• pp.11-22
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• 2006

얼굴 검출은 개인 인증이나 보안 등 그 응용분야가 다양하여 활발히 연구가 진행되고 있다. 본 논문에서는 분포맵에 기반한 얼굴 검출의 새로운 방법을 제안한다. 제안한 방법은 먼저, 빈도수를 고려한 피부색 분포맵을 입력 영상에 적용하여 일차적으로 얼굴 후보영역을 구하고, 이 영역에서 눈동자색 분포맵을 이용하여 눈후보영역을 결정함으로써 얼굴 구성 요소를 탐색하는 탐색공간을 축소한다. 결정된 눈 후보영역에서 가중치가 있는 윈도우를 이용하여 휘도성분과 색상성분의 상관값을 특징벡터로 한 템플릿 정합 방법으로 눈 후보점을 검출한다. 최종적으로 각 눈 후보점 쌍에 대하여 눈과 입의 위치관계 정보와 입을 인식하는 평가함수를 이용하여 얼굴을 검출하였다. 실험 결과, 제안된 방법은 좋은 성능을 보였다.

• 정보관리연구
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• 제40권2호
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• pp.95-115
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• 2009

저자식별은 학술문헌에 출현한 동명저자명들을 실세계의 서로 다른 사람들로 대응시키는 것이다. 이를 위해 임의의 동명저자명쌍의 유사도를 계산하고 이를 바탕으로 동명저자명 개체들을 군집화하는 단계를 거친다. 저자명의 군집화 기법으로 주로 계층적 군집법이 사용되었으나 다양한 계층적 군집법에 대한 비교 평가는 미흡했다. 이 연구는 다이스계수, 코사인유사도, 유클리디안 거리, 자카드계수, 피어슨 상관계수 등의 다양한 개체거리/유사도수식과 계층적 군집법들의 상관관계와 계층적 군집기법들의 한글 저자식별 성능에 대한 비교/분석을 다룬다.

• Bulletin of the Korean Chemical Society
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• 제16권9호
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• pp.873-885
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• 1995

The local structural and thermodynamical properties of blends A-B/H of a diblock copolymer A-B and a homopolymer H are studied using the polymer reference interaction site model (RISM) integral equation theory with the mean-spherical approximation closure. The random phase approximation (RPA)-like static scattering function is derived and the interaction parameter is obtained to investigate the phase transition behaviors in A-B/H blends effectively. The dependences of the microscopic interaction parameter and the macrophase-microphase separation on temperature, molecular weight, block composition and segment size ratio of the diblock copolymer, density, and concentration of the added homopolymer, are investigated numerically within the framework of Gaussian chain statistics. The numerical calculations of site-site interchain pair correlation functions are performed to see the local structures for the model blends. The calculated phase diagrams for A-B/H blends from the polymer RISM theory are compared with results by the RPA model and transmission electron microscopy (TEM). Our extended formal version shows the different feature from RPA in the microscopic phase separation behavior, but shows the consistency with TEM qualitatively. Scaling relationships of scattering peak, interaction parameter, and temperature at the microphase separation are obtained for the molecular weight of diblock copolymer. They are compared with the recent data by small-angle neutron scattering measurements.

• 한국제4기학회지
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• 제14권1호
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• pp.65-71
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• 2000

굴거리나무의 연륜생장과 기후와의 관계를 조사하기 위하여 굴거리나무의 분포상 북방한계선 지역인 내장산에서 연륜분석을 실시하였다. 연륜분석을 실시하기 위하여 연자봉 지역에 분포하고 있는 18그루의 굴거리나무에서 생장편을 각 2개씩 채취하였다. 굴거리나무의 연륜을 분석한 결과 마스터 연대기의 연대 구간은 1915년부터 생장편의 채취시기인 1998년으로 작성되었으며, 생장이 매우 저조했던 시기는 1920년, 1932년, 1934년, 1937년, 1942번, 1946년, 1964년, 1969년, 1985년으로 나타났다. 반응 함수를 이용하여 연륜 지수와 기후요소와의 관계를 분석한 결과, 8월 및 9월 강수량과 음의 관계를 갖는 것으로 나타났다. 굴거리나무의 생장이 8월 및 9월 강수량과 음의 관계를 갖는 것은 이 시기에 강수량이 많아 상대적으로 일사량이 적어지고 적은 일사량은 광합성량을 감소시켜 굴거리나무의 생장에 부정적인 영향을 미쳤기 때문인 것으로 추정된다.