• Nuclear Engineering and Technology
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• 제51권5호
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• pp.1272-1278
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• 2019

A lumped kinetic modeling platform is developed to investigate the coupled nuclear/thermo-fluid features of the closed natural circulation loop in a low power lead cooled fast reactor. This coolant material serves a reliable choice with noticeable thermo-physical safety characteristics in terms of natural convection. Boussienesq approximation is resorted to appropriately reduce the governing partial differential equations (PDEs) for the fluid flow into a set of ordinary differential equations (ODEs). As a main contributing step, the coolant circulation speed is accordingly correlated to the loop operational power and temperature levels. Further temporal analysis and control synthesis activities may thus be carried out within a more consistent state space framework. Nyquist stability criterion is thereafter employed to carry out a sensitivity analysis for the system stability at various power and heat sink temperature levels and results confirm a widely stable natural circulation loop.

• 한국CDE학회논문집
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• 제18권1호
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• pp.58-70
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• 2013

This study for establishing specific standards of atrium design aims to discuss design of atrium to consider energy performance atrium in office buildings. In order to evaluate a type and a scale of atrium at the early design stage, modeling details of mass design were set as standards of conceptual design. In the experiment, Project Vasari was used to analyze modeling and energy consumption, based on the LOD 100-step suggested by AIA, because there is no guideline to specify a level of modeling details at each design process. From this analysis, the correlation among a simple-typed atrium and scale and energy load was considered. The result of this research is as follows: First, the single-sided atrium reduced energy the most, and it was followed by three-sided, two-sided, four-sided and continuous-typed ones. On the whole, they could decrease energy by up to about 15%. Also, the atrium with a wide facade facing in the south was more favorable to reduce energy. Second, planning the atrium within 10~30% of the whole building area was more energy efficient. Third, rather than the depth, adjusting the length in designing an atrium could reduce cooling and heating loads by 1.5% per 1m. As explained above, energy performance evaluation considering types and planning elements of atrium helps to assess alternatives in a reasonable way. In particular, considering the use of building needs to be preceded to select a type of atrium, although it is also important to consider its planning elements.

• 한국BIM학회 논문집
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• 제4권2호
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• pp.25-32
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• 2014

Today, there is a growing need of environment-friendly buildings, so-called 'green', facilities, and energy saving buildings to decrease environmental pollutants released into cities by construction activities. Green-Building Information Modeling (Green-BIM) is a purpose-built solution which supports to forecast energy consumption of 3-D model of a building by augmenting its primary 3-D measurements (width, height and depth) with many more dimensions (e.g. time, costs, social impacts and environmental consequences) throughout a series of sequential phases in the lifecycle of a building. The current study was carried out in order to integrate vegetation systems (particularly green roof and green wall systems) and investigate thermal performance of the new Sainsbury's building which will be built on Melton road, Leicester, United Kingdom. Within this scope, a 3-D building model of the news Sainsbury's building was first developed in $Autodesk^{(R)}$ $Revit^{(R)}$ and this model was then simulated in $Autodesk^{(R)}$ $Ecotect^{(R)}$once weather data of the construction site was obtained from $Autodesk^{(R)}$ Green Building $Studio^{(R)}$. This study primarily analyzed data from (1) solar radiation, (2) heat gains and losses, and (3) heating and cooling loads simulation to evaluate thermal performance of the building integrated with vegetation system or conventionally available envelops. The results showed that building integrated vegetation system can potentially reduce internal solar gains on the building rooftops by creating a 'bioshade'. Heat gains and losses through roofs and walls were markedly diminished by offering greater insulation on the building. Annual energy loads for heating and cooling were significantly reduced by vegetation more significantly through the green roof system in comparison to green wall system.

• 전력전자학회논문지
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• 제16권6호
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• pp.533-541
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• 2011

본 논문에서는 PSCAD/EMTDC 프로그램을 통해 제주 80kV Pilot HVDC 시스템을 구현하고 제어기를 모델링하였다. ac 계통 연계 시뮬레이션을 위해 제주 ac 계통을 축약하였으며, dc 계통 시뮬레이션을 위해 컨버터 변압기, 고조파 필터 및 dc 전송선로의 설계 파라미터를 적용하였다. HVDC 제어기는 컨버터의 운전모드에 따라 인버터 제어기와 정류기 제어기로 나뉘며, 인버터 제어기는 전류제어기, 전압제어기, 소호각 제어기로 구현하였고, 정류기의 제어기는 전류제어기 및 전압제어기로 구현하였다. 인버터와 컨버터의 V-I 특성곡선에 VDCOL을 적용하여 전압에 따른 전류의 의존 특성을 반영하였다. 제어기의 단위 응답, ac 계통 단상 지락 고장, 3상 지락 고장에 대해 시뮬레이션하여 설계한 제어기의 정상상태 및 과도상태시 동특성을 검증하였다.

• 한국전자통신학회논문지
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• 제7권6호
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• pp.1567-1572
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• 2012

자동차용 IPC는 운전자에게 차량의 속도, RPM, 주행 거리 등의 운행 정보를 제공하는 장치이다. 기존의 전통적인 IPC의 경우 주로 기계식으로 구현되고 있으나 현재 사용자의 편의성 증대를 위한 요구 증가에 따라 IPC에도 그래픽 요소와 효율적인 정보제공을 위한 사용자친화적인 형태로의 변화가 필요하다. 이를 위해서는 모델링 기법을 이용하여 소프트웨어의 유연성과 강건성을 갖는 IPC의 소프트웨어 구조가 필요하다. 이에 본 논문에서는 MVC 모델과 UML을 이용하여 IPC 소프트웨어 구조를 설계하고 구현한다. 뷰를 분리하여 개발함으로써 다양한 형태의 정보 화면을 개발할 수 있고 또한 UML의 상태 다이어그램을 통해 뷰의 전환 등을 간단한 상태의 변화로 처리하여 개발이 용이하다. 제안하는 IPC 시스템은 개발 기간의 단축을 통한 비용 절감 및 MVC 모델 구조에 따른 유지보수의 용이성을 기대할 수 있다.

• 한국전자통신학회논문지
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• 제7권6호
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• pp.1321-1326
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• 2012

자동차용 IPC는 운전자에게 차량의 속도, RPM, 주행 거리 등의 운행 정보를 제공하는 장치이다. 기존의 전통적인 IPC의 경우 주로 기계식으로 구현되고 있으나 현재 사용자의 편의성 증대를 위한 요구 증가에 따라 IPC에도 그래픽 요소와 효율적인 정보제공을 위한 사용자친화적인 형태로의 변화가 필요하다. 이를 위해서는 모델링 기법을 이용하여 소프트웨어의 유연성과 강건성을 갖는 IPC의 소프트웨어 구조가 필요하다. 이에 본 논문에서는 MVC 모델과 UML을 이용하여 IPC 소프트웨어 구조를 설계하고 구현한다. 뷰를 분리하여 개발함으로써 다양한 형태의 정보 화면을 개발할 수 있고 또한 UML의 상태 다이어그램을 통해 뷰의 전환 등을 간단한 상태의 변화로 처리하여 개발이 용이하다. 제안하는 IPC 시스템은 개발 기간의 단축을 통한 비용 절감 및 MVC 모델 구조에 따른 유지보수의 용이성을 기대할 수 있다.

• 청정기술
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• 제22권4호
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• pp.225-231
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• 2016

본 연구에서는 2중 효용 증발관을 이용하여 21.0 wt%의 NaCl 수용액에서 고형물의 NaCl을 $1,524.58kg\;h^{-1}$만큼 석출시키는 공정에 대해서 증기 재압축을 활용하여 스팀 소모량을 $3,139kg\;h^{-1}$에서 $496kg\;h^{-1}$로 줄이는 공정에 대한 전산모사 및 최적화 작업을 수행하였다. 디에틸렌 글리콜(diethylene glycol)을 포함한 NaCl 수용액을 농축시키기 위한 증발농축 공정의 전산모사를 위해서는 AspenTech사의 Aspen Plus V8.8을 활용하였으며, 중간에 냉각기를 가지는 증기 재압축 공정의 전산모사를 위해서는 Schneider Electric사의 PRO/II with PROVISION V9.4를 이용하였다. 증기 재압축 공정에 대해서는 1기의 압축기를 사용한 공정과 중간에 냉각기를 가지는 2단 압축 공정을 상호 비교하였다.

• 한국안전학회지
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• 제37권6호
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• pp.166-173
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• 2022

A variety of input parameters are taken into consideration while performing a Level 3 PSA. Some parameters related to plume segments, spatial grids, and particle size distribution have flexible input formats. Fine modeling performed by splitting a number of segments or grids may enhance the accuracy of analysis but is time-consuming. Analysis speed is highly important because a considerably large number of calculations is required to handle Level 2 PSA scenarios for a single-unit or multi-unit Level 3 PSA. This study developed a sensitivity analysis supporting interface called MACCSsense to compare the results of the trials of plume segmentation with the results of the base case to determine its impact (in terms of time and accuracy) and to support the development of a modeling approach, which saves calculation time and improves accuracy. MACCSense is an automation tool that uses a large amount of plume segmentation analysis results obtained from MUST Converter and Mr. Manager developed by KAERI to generate a sensitivity report that includes impact (time and accuracy) by comparing them with the base-case result. In this study, various plume segmentation approaches were investigated, and both the accuracy and speed of offsite consequence analysis were evaluated using MACCS as a consequence analysis tool. A simultaneous evaluation revealed that execution time can be reduced using multi-threading. In addition, this study can serve as a framework for the development of a modeling strategy for plume segmentation in order to perform accurate and fast offsite consequence analyses.

• 국제학술발표논문집
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• The 5th International Conference on Construction Engineering and Project Management
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• pp.260-266
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• 2013

This study for establishing specific standards of atrium design aims to discuss design of atrium to consider energy performance according to the types of atrium of office building. In order to evaluate a type and a scale of atrium at the early design stage, modeling details of mass design were set as standards of conceptual design. In the experiment, Project Vasari was used to analyze modeling and energy consumption, based on the LOD 100-step suggested by AIA, because there is no guideline to specify a level of modeling details at each design process. From this analysis, the correlation among a simple-typed atrium and scale and energy load was understood, and the followings are the considerations for designing an atrium. First, the single-sided atrium reduced energy the most, and it was followed by three-sided, two-sided, four-sided and continuous-typed ones. On the whole, they could decrease energy by up to about 15%. Also, the atrium with a wide facade facing in the south was more favorable to reduce energy. Second, planning an atria within 10~30% of the whole building area was more energy efficient. Third, rather than the depth, adjusting the length in designing an atrium could reduce cooling and heating loads by 1.5% per 1m. As explained above, energy performance evaluation considering types and planning elements of atrium helps to assess alternatives in a reasonable way. In particular, considering the use of building needs to be preceded to select a type of atrium, although it is also important to consider its planning elements.

• 대한기계학회논문집A
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• 제27권5호
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• pp.681-687
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• 2003

Terrain surfaces have to be modeled in very detail and wheel-surface contacting geometry must be well defined in order to obtain proper ground-reaction and friction forces fur realistic simulation of off-road vehicles. Delaunay triangulation is one of the most widely used methods in modeling 3-dimensional terrain surfaces, and the T-search is a relevant algorithm for searching resulting triangular polygons. The T-search method searches polygons in a successive order and may not allow real-time computation of off-road vehicle dynamics if the terrain is modeled with many polygons, depending on the computer performance used in the simulation. The dynamic T-search, which is proposed in this paper, combines conventional T-search and the concept of the dynmaic-window search which uses reduced searching windows or sets of triangular surface polygons at each frame by taking advantage of the information regarding dynamic charactereistics of a simulated vehicle. Numerical tests show improvement of searching speeds by about 5% for randomly distributed triangles. For continuous search following a vehicle path, which occurs in actual vehicle simulation, the searching speed becomes 4 times faster.