• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.6
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• pp.136-143
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• 2018

Recently, with the rapid development of virtual reality technology, there have been more and more applications of virtual reality technology in various fields. In order to realize a virtual reality, a method of implementing a visualization environment through an HMD (Head Mounted Display) is widely used. However, in the current visualization environment through the HMD, the user feels dizziness when worn, It has the disadvantage of imposing restrictions on. In this study, it is aimed to realize virtual reality visualization environment through multi-screen environment which improves the experience effect of virtual environment by using existing screen instead of visualization through HMD, and compensates for shortcomings of HMD method. In order to realize a multi-screen environment as a highly visualized environment, a technique for matching the spatial position of the multi-screen with the spatial position of the virtual environment is required. To do this, we need an efficient method to precisely measure the position of the space, and we propose a spatial position compensation methodology that can efficiently and precisely measure the position of the real space and reflect it in the virtual environment.

• Journal of Convergence for Information Technology
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• v.12 no.3
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• pp.294-301
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• 2022

In this study, a multi-layer cascade (MLC) electrical array configuration method for thermoelectric generator consisting of plural number of thermoelectric modules (TEMs) was proposed to reduce mismatch loss caused by temperature maldistribution on the surfaces of the TEMs. To validate the effect of MLC on the mismatch loss reduction, a numerical model capable of reflecting multi-physics phenomena occuring in the TEMs was developed. MLC can be employed by placing a group of TEMs experiencing relatively low temperature differences in an electric layer with more electrical branches while locating a group of TEMs experiencing relatively high temperature differences in an electric layer with less electrical branches. The TEMs were classified using the temperature distribution obtained by the numerical model. A MLC with an optimal electrical branch ratio showed a 96.5% of electric power generation compared to an ideal case.

• Journal of Korean Neurosurgical Society
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• v.66 no.4
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• pp.382-392
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• 2023

Objective : The use of indocyanine green videoangiography (ICG-VA) to assess blood flow in the brain during cerebrovascular surgery has been increasing. Clinical studies on ICG-VA have predominantly focused on qualitative analysis. However, quantitative analysis numerical modelling for time profiling enables a more accurate evaluation of blood flow kinetics. In this study, we established a multiple exponential modified Gaussian (multi-EMG) model for quantitative ICG-VA to understand accurately the status of cerebral hemodynamics. Methods : We obtained clinical data of cerebral blood flow acquired the quantitative analysis ICG-VA during cerebrovascular surgery. Varied asymmetric peak functions were compared to find the most matching function form with clinical data by using a nonlinear regression algorithm. To verify the result of the nonlinear regression, the mode function was applied to various types of data. Results : The proposed multi-EMG model is well fitted to the clinical data. Because the primary parameters-growth and decay rates, and peak center and heights-of the model are characteristics of model function, they provide accurate reference values for assessing cerebral hemodynamics in various conditions. In addition, the primary parameters can be estimated on the curves with partially missed data. The accuracy of the model estimation was verified by a repeated curve fitting method using manipulation of missing data. Conclusion : The multi-EMG model can possibly serve as a universal model for cerebral hemodynamics in a comparison with other asymmetric peak functions. According to the results, the model can be helpful for clinical research assessment of cerebrovascular hemodynamics in a clinical setting.

• Progress in Medical Physics
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• v.21 no.2
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• pp.137-144
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• 2010

The purpose of this study was to evaluate the usefulness of reducing of craniofacial radiation dose using automatic exposure control (AEC) technique in the 64 multi-detector computed tomography (MDCT). We used SOMATOM Definition 64 multi-detector CT, and head of whole body phantom (KUPBU-50, Kyoto Kagaku CO. Ltd). The protocol were helical scan method with 120 kVp, 1 sec of rotation time, 5 mm of slice thickness and increment, 250 mm of FOV, $512{\times}512$ of matrix size, $64{\times}0.625\;mm$ of collimation, and 1 of pitch. The evaluation of dose reducing effect was compared the fixed tube current of 350 with AEC technique. The image quality was measured the noise using standard deviation of CT number. The range of craniofacial bone was to mentum end from calvaria apex, which devided three regions: calvaria~superciliary ridge (1 segment), superciliary ridge~acanthion (2 segment), and acanthion~mentum (3 segment). In the fixed tube current technique, CTDIvol was 57.7 mGy, DLP was $640.2\;mGy{\cdot}cm$ in the all regions. The AEC technique was showed that 1 segment were 30.7 mGy of CTDIvol, 340.7 $mGy{\cdot}cm$ of DLP, 2 segment were 46.5 mGy of CTDIvol, $515.0\;mGy{\cdot}cm$ of DLP, and 3 segment were 30.3 mGy of CTDIvol, $337.0\;mGy{\cdot}cm$ of DLP. The standard deviation of CT number was 2.622 with the fixed tube current technique and 3.023 with the AEC technique in the 1 segment, was 3.118 with the fixed tube current technique and 3.379 with the AEC technique in the 2 segment, was 2.670 with the fixed tube current technique and 3.186 with the AEC technique in the 3 segment. The craniofacial radiation dose using AEC Technique in the 64 MDCT was evaluated the usefulness of reducing for the eye, the parotid and thyroid with high radiation sensitivity particularly.

• ETRI Journal
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• v.26 no.3
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• pp.189-194
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• 2004

We demonstrate a high-speed recording based on field-induced manipulation in combination with an optical reading of recorded bits on Au cluster films using the atomic force microscope (AFM) and the near-field scanning optical microscope (NSOM). We reproduced 50 nm-sized mounds by applying short electrical pulses to conducting tips in a non-contact mode as a writing process. The recorded marks were then optically read using bent fiber probes in a transmission mode. A strong enhancement of light transmission is attributed to the local surface plasmon excitation on the protruded dots.

• Publications of The Korean Astronomical Society
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• v.27 no.4
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• pp.305-310
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• 2012

AKARI's all-sky survey resolves the far-infrared emission in many thousands of nearby galaxies, providing essential local benchmarks against which the evolution of high-redshift populations can be measured. This review presents some recent results in the resolved galaxy populations, covering some well-known nearby targets, as well as samples from major legacy surveys such as the Herschel Reference Survey and the JCMT Nearby Galaxies Survey. This review also discusses the prospects for higher redshifts surveys, including strong gravitational lens clusters and the AKARI NEP field.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.209-209
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• 2012

전자의 에너지를 측정하기 위한 분석장치는 원자핵물리뿐만 아니라 화학과 생물학 등 다양한 분야에 걸쳐 매우 유용하게 사용될 수가 있다. 특히 최근에 극고속 과학과 관련해서 매우 짧은 펄스인 아토초 펄스의 발생에 대한 특성평가를 위해 매우 중요한 장치로 사용되고 있다. 그 중 VMI (Velocity Map Imaging) 방법은 TOF (Time of Flight) 방법과 유사하지만, CCD 카메라를 추가로 사용하여 이차원 이미지를 얻음으로써 전자의 운동에너지 및 각도 분포에 대한 정보를 얻을 수 있고 또한 전극에 인가되는 전압은 TOF와 달리 매우 높다. 이번 개발에서는 기존의 전극 렌즈의 geometry와 비교해서 VMI Spectrometer 전극 렌즈의 수를 늘려 multi-electrode concept을 도입함으로써 높은 운동에너지(~1000 eV)를 가진 전자들을 MCP detector상에서 imaging 하는데 있어 높은 공간 분해능(resolution)을 갖도록 설계하고, 또한 높은 사양의 MCP detector 및 CCD 카메라를 이용하여 시간 분해능을 높임으로써 아토초 펄스를 이용한 극고속 실험에 이용 가능하도록 제작하였다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.139-142
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• 2005

The Digital Meister is an advisory system to help the designer using the knowledge obtained from design and analysis data. In this paper, Taguchi method was applied to analyze the design parameters of automotive engine pulley. As a finite element method (FEM), ALGOR Multi-physics was used for analyzing the static analysis. As a result, two bending positions and material thickness were highly related to the maximum stress. These correlations between design parameters and analysis result will be used for supporting the design process of Digital Meister.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.12
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• pp.1017-1021
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• 2015

Induction heating has been applied to the preheating process in various industrial fields. It has been used as a simple device structure, limiting the heating zone through controlled variables, and free-welding positions. It would be helpful to weld thick plates with arc welding such as GMAW. The induction heating process is well suited to this process. In this study, in order to find suitable induction heating parameters, a simulation was conducted with multi physics S/W. Three kinds of material were heated by induction coils designed specially for thick plate. Consequently, steel and nimonic alloy were the most efficient materials for preheating by induction. It can be concluded that the induction heating process is a good method for preheating the thick plate.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.131-136
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• 2004

스피커는 진동판의 크기와 형태 외에도 소재 또는 내부구조에 따라 구동 특성이 달라진다. 본 연구에서는 동일한 신호가 입력되는 두 진동판 사이에 공동을 형성시킨 경우, 다공성 흡음재를 삽입한 경우 스피커의 특성 변화를 관측하였다. 특히, 다공성 흡음재를 삽입한 경우, 다공성 물질의 체적을 동일하게 하고 진동판 표면 상태에 따른 영향과 진동판 상의 진동 전달 경로에 의한 영향을 제거하여 내부물질에 따른 특성의 변화를 측정하였다.