• 한국지리정보학회지
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• 제22권4호
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• pp.215-228
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• 2019

해양관측 정지궤도 위성인 GOCI(Geostationary Ocean Color Imager) 데이터는 대용량 산출물을 효과적으로 저장, 배포하기 위해 HDF5 자료 형식을 사용하고 있다. 해양위성센터에서는 HDF5(Hierarchical Data Format version5) 포맷에 익숙지 않은 일반 사용자를 위해 GDPS(GOCI Data Processing System)를 개발하여 관측자료와 함께 제공하고 있다. 그럼에도 불구하고 위성데이터 특성에 대한 이해와 GDPS의 사용법을 익혀야 하는 점, 그리고 위치정보와 속성정보가 분리되어 있는 HDF5 형식의 자료를 병합하고 가공하는 일은 쉽지 않은 일이다. 따라서 본 연구에서는 오픈소스 R과 rhdf5, data.table, matrixStats 패키지를 이용하여 GDPS를 이용하는 과정 없이도 HDF5 형식의 위성데이터를 손쉽게 활용할 수 있는 알고리즘을 개발하였다.

• International journal of advanced smart convergence
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• 제8권3호
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• pp.39-45
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• 2019

This paper presents an optical technique for the three-dimensional (3D) shape inspection of micro solder balls used in ball-grid array (BGA) packaging. The proposed technique uses an optical source composed of spatially arranged light-emitting diodes (LEDs) and the results are derived based on the specular reflection characteristics of the micro solder balls for BGA A vision system comprising a camera and LEDs is designed to capture the reflected images of multiple solder balls arranged arbitrarily on a tray and the locations of the LED point-light-source reflections in each ball are determined via image processing, for shape inspection. The proposed methodology aims to determine the presence of defects in 3D BGA shape using the statistical information of the relative positions of multiple BGA balls, which are included in the image. The presence of the BGA balls with large deviations in relative position imply the inconsistencies in their shape. Experiments were conducted to verify that the proposed method could be applied to inspection without sophisticated mechanism and productivity problem.

• 대한지리학회지
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• 제45권4호
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• pp.431-443
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• 2010

한반도 남부 13개 선상지를 일본, 대만, 필리핀의 690개 선상지와 비교, 분석하였다. 선상지 경사와 함양역 면적, 선상지 경사와 함양역 기복비, 선상지 면적과 함양역 면적, 그리고 함양역 면적과 함양역 기복비와의 관계를 정량적으로 검토한 결과, 한반도 남부의 선상지는 아시아의 선상지 특성과 잘 부합되지만, 선상지 빈도와 밀도가 낮다. 또한 선상지 하천의 함양역 규모가 작고, 기복비가 커서 선상지 규모가 작고 경사가 급하다. 36개 주요 하천 곡구부에서 선상지가 형성되지 않는 것은 상대적으로 낮은 산지고도와 함양역의 기복비 때문이다. 한국의 선상지에서는 Blair and McPherson이 주장한 지형면 경사의 공백을 확인할 수 없으며, 경주 선상지는 경사가 완만한 하성 선상지의 가능성이 높다.

• 가족자원경영과 정책
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• 제16권1호
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• pp.67-83
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• 2012

Baby boomers are often defined by their support of their parents and their devotion to their children's educational success by providing financial and emotional aids. Now, 7.12 million baby boomers in South Korea are retiring, or are about to retire, without any retirement plans. Similar to financial stability, health, and leisure life, social capital is another important element in the quality life after retirement. This is because social capital can function as a potential resource network. Social capital is a source that provides money, information, goods, services, emotional aids, social relational opportunities etc. In the past, family and community provided social capital for the aged. However, the baby boomer generation cannot expect the same. The baby boomers have the task of creating new social capital that can assure their quality of life. Therefore, this study examines cohort characteristics of the baby boomer generation and, based on the examination, seeks an alternative for social capital. The results are as follows: First, social capital from the local community can be an alternative source of caring for the baby boomers in old age. Second, among the social capital of the local community, elderly care supported by a family friendly community is proposed. In addition, baby boomers must become the primary social capital that contributes to a mature civil society rather than a beneficiary of welfare for the aged.

• 통합자연과학논문집
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• 제1권2호
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• pp.79-83
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• 2008

As a new standard for performance measurement, NEMA NU2-2001 was presented recently. In this study, I investigated the spatial resolution, sensitivity, scatter fraction, and noise equivalent count ratio (NECR) in order to know the information of physical characteristics and system performance of GE discovery ST using this new standard. Bismuth germinate crystals ($6{\times}6$ array, $6.3mm{\times}6.3mm{\times}30mm$) were used in discovery ST (energy window:375-650 keV, coincidence window:11.7 nsec). To measure the sensitivity, five aluminum sleeves (Data Spectrum Corp., Chapel Hill, NC., USA, thickness:1.25 mm)-NEMA sensitivity phantom- filled with F-18 solution were used. Successive measurements in 2D and 3D acquisition mode were made with a line source at the center of transaxial field of view and 10 cm off from the center until the count was over 500,000. Spatial resolution was estimated using a point source (F-18, 0.1 mCi) at different locations in the FOV. Scatter fraction and NECR was tested using a NEMA scatter phantom. Dynamic data were acquired for 7 half-lives using F-18 solution. And true to background ratio was averaged at last three frames when the random rate was as small as ignorable for the calculation of scatter fraction. We anticipate this overall evaluated results could be used for the quality assurance and optimized image acquisition for clinical research.

• 한국전기전자재료학회논문지
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• 제25권9호
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• pp.671-676
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• 2012

In this paper, TCAD assessment of 30-V class n-channel EDMOS (extended drain metal-oxide-semiconductor) transistors with DWFG (dual work function gate) structure are described. Gate of the DWFG EDMOS transistor is composed of both p- and n-type doped region on source and drain side. Additionally, lengths of p- and n-type doped gate region are varied while keeping physical channel length. Two-dimensional device structures are generated trough TSUPREM-4 and their electrical characteristics are investigated with MEDICI. The DWFG EDMOS transistor shows improved electrical characteristics than conventional device - i.e. higher transconductance ($g_m$), better drain output current ($I_{ON}$), reduced specific on-resistances ($R_{ON}$) and higher breakdown characteristics ($BV_{DSS}$).

• 전자공학회논문지A
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• 제31A권4호
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• pp.116-126
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• 1994

In this paper, the switch-level fault simulator for CMOS circuits with a gate-to-drain/source short fault is implemented. A fault model used in this paper is based on the graphical analysis of the electrical characteristics of the faulty MOS devices and the conversion of the faulty CMOS circuit to the equivalent faulty CMOS inverter in order to find its effect on the successive stage. This technique is very simple and has the increased accuracy of the simulation. The simulation result of the faulty circuit using the implemented fault simulator is compared with the result of the SPICE simulation.

• 실내환경 및 냄새 학회지
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• 제17권4호
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• pp.303-314
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• 2018

The urban railway system is a convenient public transportation system, as it carries many people without increasing traffic congestion. However, air quality in urban railway environments is worse than ambient air quality due to the internal location of the source of air pollutants and the isolated space. In this paper, characteristics of particulate matter (PM) pollution in urban railway environments are described from the perspective of diurnal variation, chemical composition and source apportionment of PM. PM concentrations in concourse, platform, passenger cabin, and tunnel are summarized through an analysis of 34 journal articles published in Korea and overseas. This information will be helpful in developing effective policies to reduce PM pollution in urban railway environments.

• JSTS:Journal of Semiconductor Technology and Science
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• 제17권1호
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• pp.156-161
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• 2017

This work presents a novel structure for junction-less tunneling field effect transistor (JL-TFET) with a floating gate over the source region. Introduction of floating gate instead of fixed metal gate removes the limitation of fabrication process suitability. The proposed device is based on a heavily n-type-doped Si-channel junction-less field effect transistor (JLFET). A floating gate over source region and a control-gate with optimized metal work-function over channel region is used to make device work like a tunnel field effect transistor (TFET). The proposed device has exhibited excellent ID-VGS characteristics, ION/IOFF ratio, a point subthreshold slope (SS), and average SS for optimized device parameters. Electron charge stored in floating gate, isolation oxide layer and body doping concentration are optimized. The proposed JL-TFET can be a promising candidate for switching performances.

• JSTS:Journal of Semiconductor Technology and Science
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• 제13권6호
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• pp.569-575
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• 2013

An improved non-quasi-static gate-source impedance model including a parallel RC block for short-channel MOSFETs is developed to simulate RF MOSFET input characteristics accurately in the wide range of high frequency. The non-quasi-static model parameters are accurately determined using the physical input equivalent circuit. This improved model results in much better agreements between the measured and modelled input impedance than a simple one with a non-quasi-static resistance up to 40GHz, verifying its accuracy.