• 한국산학기술학회논문지
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• 제15권8호
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• pp.5333-5341
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• 2014

최근 실내공간정보 기반의 시설물 운영관리에 대한 관심이 고조되면서 BIM과 GIS를 연계한 시설물 유지관리에 대한 다양한 연구가 진행되고 있다. 특히 대용량 데이터에 대한 형상정보의 가시화 처리는 중요한 이슈로, 유지관리 시스템 운영에 중요한 요소이다. 따라서 본 연구는 GIS 기반 BIM 모델의 효과적 가시화 구현을 위하여 IFC 스키마 기반의 시나리오를 통한 공간인덱싱 알고리즘을 설계하고, OcTree 기법을 적용하여 공간인덱싱 알고리즘을 일부 구현하였다. 구현된 결과를 IFC 샘플데이터에 테스트한 후 최종적으로 BIM 데이터의 효과적 가시화를 위한 공간인덱싱 기법을 제안한다.

• Journal of Biosystems Engineering
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• 제19권2호
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• pp.124-137
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• 1994

Visual features of a mushroom(Lentinus Edodes, L.) are critical in grading and sorting as most agricultural products are. Because of its complex and various visual features, grading and sorting of mushrooms have been done manually by the human expert. To realize the automatic handling and grading of mushrooms in real time, the computer vision system should be utilized and the efficient and robust processing of the camera captured visual information be provided. Since visual features of a mushroom are distributed over the front and back sides, recognizing sides and states of the stalk including the stalk orientation from the captured image is a prime process in the automatic task processing. In this paper, the efficient and robust recognition process identifying the front and back side and the state of the stalk was developed and its performance was compared with other recognition trials. First, recognition was tried based on the rule set up with some experimental heuristics using the quantitative features such as geometry and texture extracted from the segmented mushroom image. And the neural net based learning recognition was done without extracting quantitative features. For network inputs the segmented binary image obtained from the combined type automatic thresholding was tested first. And then the gray valued raw camera image was directly utilized. The state of the stalk seriously affects the measured size of the mushroom cap. When its effect is serious, the stalk should be excluded in mushroom cap sizing. In this paper, the stalk removal process followed by the boundary regeneration of the cap image was also presented. The neural net based gray valued raw image processing showed the successful results for our recognition task. The developed technology through this research may open the new way of the quality inspection and sorting especially for the agricultural products whose visual features are fuzzy and not uniquely defined.

• 한국초등수학교육학회지
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• 제14권3호
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• pp.701-722
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• 2010

기하를 학습하기 위해 학생들은 일상생활에서 접하는 대상과 다른 구체적 자료를 사용해서 조사하고, 실험하고, 탐구해 보아야 한다. 구체적 조작활동은 수학적 모델링을 하는 과정에서 수학적 개념이나 절차를 이해하게 하고 이것을 기호로 나타내 주는 것을 도와주고 컴퓨터를 활용한 실험활동은 추상적인 학습내용을 시각화하여 직관적, 탐구적 활동에 초점을 둘 수 있게 한다. 따라서 본 연구는 구체물과 탐구형소프트웨어를 활용하여 구체적 조작 실험 활동을 할 수 있는 활동지를 개발하여 평면도형의 성질을 탐구할 수 있는 방안을 제시하고 그 효과를 검증하였다. 구체적 조작 실험의 수업은 중위 수준과 하위 수준의 학생들에게 평면도형의 성질 이해하는데 효과가 있었으며 상위수준 및 하위수준의 학생들에게 수학적 의사소통 능력을 향상시키는데 효과가 있는 것으로 나타났다. 학생들은 조작 실험 활동을 할 때 활동에 필요한 자료의 특성을 먼저 파악해야 하며 학생들에게 활동을 선택하게 할 때 교사의 치밀한 계획과 관찰이 요구된다. 또한 조작활동 후 수학적 의미를 연결짓기 위한 토론 활동이 요구된다.

• 천문학회보
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• 제36권2호
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• pp.115.1-115.1
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• 2011

We analyzed the line profiles of the planetary nebula (PN) NGC 7009 secured with the Keck I HIES and BOES's spectral data. The 5 positions were taken over the nebular image, 4 points on the bright rim plus 1 point at the central position. The covered spectral wavelength range was $3250{\AA}-8725{\AA}$ in these observations. We decomposed the lines of HI, HeI, HeII, CII, NIII, [ClIII], [NII], [OII], [OIII], [SII], [SIII], [ClIII], and [ArIII] using the IRAF and StarLink/Dipso. After correcting the Earth's movement and the PN's radial velocities, -48.6 & -48.9 km/s, respectively, for the Keck & BOES, we produced the line profiles in a velocity scale. The zero velocity at each line profile clearly indicates which part of the components is approaching or receding, giving a general information of the kinematical structure. Almost all of the low-to-medium excitation lines, such as [NII], [SII], [O III], and [ArIII], secured at the central position and four positions along the major & minor axes, showed 3 components, double peak + a wide wing component, suggesting the fast outflow structures are present. The overall geometry is a prolate shell which also has a fainter outer shell in the halo zone, but there appears to be some peculiar sub-structures inside the main shell. The high excitation He I, HeII, NIII lines which might be formed close to the inner boundary of the shell show unusual features, completely different from the other lines. The HeII and these high excitation lines may be indicative of a relative recent fast outflow from the central star and the permitted lines such as NIII might be affected by the innermost structure. We discuss a possible presence of a jet-like fast outflow structure in an out-flow axis different from the main axis of the spheroid shell.

• 대한전자공학회논문지
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• 제25권9호
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• pp.1115-1124
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• 1988

A two-dimensional systolic array for fast Fourier transform, which has a regular and recursive VLSI architecture is presented. The array is constructed with identical processing elements (PE) in mesh type, and due to its modularity, it can be expanded to an arbitrary size. A processing element consists of two data routing units, a butterfly arithmetic unit and a simple control unit. The array computes FFT through three procedures` I/O pipelining, data shuffling and butterfly arithmetic. By utilizing parallelism, pipelining and local communication geometry during data movement, the two-dimensional systolic array eliminates global and irregular commutation problems, which have been a limiting factor in VLSI implementation of FFT processor. The systolic array executes a half butterfly arithmetic based on a distributed arithmetic that can carry out multiplication with only adders. Also, the systolic array provides 100% PE activity, i.e., none of the PEs are idle at any time. A chip for half butterfly arithmetic, which consists of two BLC adders and registers, has been fabricated using a 3-um single metal P-well CMOS technology. With the half butterfly arithmetic execution time of about 500 ns which has been obtained b critical path delay simulation, totla FFT execution time for 1024 points is estimated about 16.6 us at clock frequency of 20MHz. A one-PE chip expnsible to anly size of array is being fabricated using a 2-um, double metal, P-well CMOS process. The chip was layouted using standard cell library and macrocell of BLC adder with the aid of auto-routing software. It consists of around 6000 transistors and 68 I/O pads on 3.4x2.8mm\ulcornerarea. A built-i self-testing circuit, BILBO (Built-In Logic Block Observation), was employed at the expense of 3% hardware overhead.

• Nuclear Engineering and Technology
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• 제48권4호
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• pp.847-858
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• 2016

An overview is given on the work of the Laboratory of Nuclear Energy Systems at ETH, Zurich (ETHZ) and of the Laboratory of Thermal Hydraulics at Paul Scherrer Institute (PSI), Switzerland on tight-lattice bundles. Two-phase flow in subchannels of a tight triangular lattice was studied experimentally and by computational fluid dynamics simulations. Two adiabatic facilities were used: (1) a vertical channel modeling a pair of neighboring sub-channels; and (2) an arrangement of four subchannels with one subchannel in the center. The first geometry was equipped with two electrical film sensors placed on opposing rod surfaces forming the subchannel gap. They recorded 2D liquid film thickness distributions on a domain of $16{\times}64$ measuring points each, with a time resolution of 10 kHz. In the bubbly and slug flow regime, information on the bubble size, shape, and velocity and the residual liquid film thickness underneath the bubbles were obtained. The second channel was investigated using cold neutron tomography, which allowed the measurement of average liquid film profiles showing the effect of spacer grids with vanes. The results were reproduced by large eddy simulation + volume of fluid. In the outlook, a novel nonadiabatic subchannel experiment is introduced that can be driven to steady-state dryout. A refrigerant is heated by a heavy water circuit, which allows the application of cold neutron tomography.

• Nuclear Engineering and Technology
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• 제41권7호
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• pp.945-952
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• 2009

The Three Mile Island Unit 2 (TMI-2) accident provides unique full scale data, thus providing opportunities to check the capability of codes to model overall plant behavior and to perform a spectrum of sensitivity and uncertainty calculations. As part of the TMI-2 analysis benchmark exercise sponsored by the Organization for Economic Cooperation and Development Nuclear Energy Agency (OECD NEA), several member countries are continuing to improve their system analysis codes using the TMI-2 data. The Republic of Korea joined this benchmark exercise in November 2005. Seoul National University has analyzed the TMI-2 accident as well as the currently proposed alternative scenario along with a sensitivity study using the Modular Accident Analysis Program Version 4.03 (MAAP4.03) code in collaboration with the Korea Hydro and Nuclear Power Company. Two input files are required to simulate the TMI-2 accident with MAAP4: the parameter file and an input deck. The user inputs various parameters, such as volumes or masses, for each component. The parameter file contains the information on TMI-2 relevant to the plant geometry, system performance, controls, and initial conditions used to perform these benchmark calculations. The input deck defines the operator actions and boundary conditions during the course of the accident. The TMI-2 accident analysis provided good estimates of the accident output data compared with the OECD TMI-2 standard reference. The alternative scenario has proposed the initial event as a loss of main feed water and a small break on the hot leg. Analysis is in progress along with a sensitivity study concerning the break size and elevation.

• 지적과 국토정보
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• 제45권1호
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• pp.137-150
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• 2015

전국적으로 지적도면을 디지털 지적정리(세계측지계 변환)를 하려는 움직임 가운데 그 대상 중 우선적으로 도로, 하천과 같은 대규모 국 공유지로 논의되고 있어 이에 대한 방법론이 필요하게 되었다. 대규모 국 공유지의 디지털 지적정리를 위한 지적도면 정비방안을 중심으로 유사사례와 문헌 조사를 통하여 종합적으로 검토한 결과 세계측지계로 변환하기 전에 미리 지적도면의 정비가 필요하다. 그 정비내용은 도형 및 속성오류의 정비와 현황조사를 통해 필요한 부분은 분할 및 현황측량을 실시하고 군소필지와 지목불일치 해소를 위한 지목변경 및 합병정리가 필요함을 제시하였다. 대규모 국 공유지의 디지털 지적정리에 세계측지계 변환만으로는 지적도면의 부실성은 해소되지 못하며 근본적으로 지적도면의 체계적인 정비가 필요하다고 판단된다.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2004년도 한국우주과학회보 제13권2호
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• pp.347-350
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• 2004

A space radiation analysis has been used to evaluate an ability of electronic equipment boxes or spacecrafts to endure various radiation effects, so it helps design thicknesses of structure and allocate components to meet the radiation requirements. A comparison study of space radiation dose analysis programs SPENVIS Sectoring Tool (SST) and SIGMA II is conducted through some structure cases, simple sphere shell, box and representative satellite configurations. The results and a discussion of comparison will be given. A general comparison will be shown for understanding those programs. The both programs use the same strategy, solid angle sectoring with ray-tracing method to produce an approximate dose at points in representative simple and complex models of spacecraft structures. Also the particle environment data corresponding to mission specification and radiation transport data are used as input data. But there are distinctions between them. The specification of geometry model and its input scheme, the assignment of dose point and the numbers, the prerequisite programs and ways of representing results will be discussed. SST is a web-based interactive program for sectoring analysis of complex geometries. It may be useful for a preliminary dose assessment with user-friendly interfaces and a package approach. SIGMA II is able to obtain from RSICC (Radiation Safety Information Computational Center) as a FOR-TRAN 77 source code. It may be suitable for either parametric preliminary design or detailed final design, e.g. a manned flight or radiation-sensitive component configuration design. It needs some debugs, recompiling and a tedious work to make geometrical quadric surfaces for actual spacecraft configuration, and has poor documentation. It is recommend to vist RSICC homepage and GEANT4/SSAT homepage.

• 대한전자공학회논문지TC
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• 제45권2호
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• pp.119-126
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• 2008

본 논문에서는 엔드론치형 구형도파관 어댑터 해석을 위하여 루프 결합 모델을 제안하고, 이를 토대로 입력 임피던스의 모드 해석식을 유도하였다. 구형도파관 내의 전파모드와 고차모드들에 따른 입력 임피던스의 영향을 분석하고, 설계변수에 대하여 고찰하였다. 또한 선행 연구에서 제안된 방식과 상용 해석 툴인 HFSS의 해석결과를 바탕으로 제안한 해석식이 타당함을 검증하였다. 제안한 엔드론치형 구형도파관 어댑터는 특성 임피던스 $50{\Omega}$을 갖는 동축선의 내부도체와 WR90 상용도파관내에서 길이가 17.6mm인 급전루프가 연결된 결합구조이다. 이러한 구조에서 앤드론치형 어댑터는 정재파비(VSWR)가 2.0이하인 기준에서 7.5GHz에서 10.6GHz 대역을 갖는다.