• Journal of Astronomy and Space Sciences
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• 제27권4호
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• pp.377-382
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• 2010

In lunar explorer development program, computer simulator is necessary to provide virtual environments that vehicle confronts in lunar transfer, orbit, and landing missions, and to analyze dynamic behavior of the spacecraft under these environments. Objective of simulation differs depending on its application in spacecraft development cycle. Scope of use cases considered in this paper includes simulation of software based, processor and/or hardware in the loop, and support of ground-based flight test of developed vehicle. These use cases represent early phase in development cycle but reusability of modeling results in the next design phase is considered in defining requirements. A simulator architecture in which simulator platform is located in the middle and modules for modeling, analyzing, and three dimensional visualizing are connected to that platform is suggested. Baseline concepts and requirements for simulator development are described. Result of trade study for selecting simulation platform and approaches of defining other simulator components are summarized. Finally, characters of lunar elevation map data which is necessary for lunar terrain generation is described.

• 한국디지털건축인테리어학회논문집
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• 제13권4호
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• pp.5-12
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• 2013

Conceptual and technical design designated as digital architecture has been discussed with disorderly meaning as a conception only. Thus, this study aims at verification of development possibility for the digital architecture by analyzing how works of Frank Gehry have effect on nonlinearity of the digital architecture. Nonlinear characteristics appeared on works of Frank Gehry analyzed on the basis of expression techniques and modeling principle are as follows: 1) Initial works show a trend to gradually change and develop from horizontal and vertical linear structure to nonlinear pattern. 2) From a nonlinear modeling principle, initial works appear the primary deformation elements only, while afterwards, they are gradually developing to a pattern to mix the primary and secondary deformation elements as introduction of digital architecture. 3) Through specific cases, Frank Gehry has conducted attempts with various method for nonlinear pattern expression. 4) From the initial works to the latest works, continuity becomes higher and changed to nonlinear pattern. This study is significant from a viewpoint that it has verified development possibility of digital architecture by analyzing nonlinear trend of digital architecture for Frank Gehry and it is required to conduct multilateral researches related to the digital architecture.

• 한국추진공학회지
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• 제15권1호
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• pp.45-54
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• 2011

액체로켓엔진 시스템에 대한 동특성 예측 프로그램을 작성하였다. 이 프로그램을 통해 얻은 펌프 시동 시 압력 및 유량 변화 결과를 수류시험장치를 구축하여 실험적으로 검증하였다. 수류시험장치는 실제 개방형 액체로켓엔진 추진제 공급 계통에서 구성품의 형태와 배치위치, 가스발생기와 주연소실로 분기되는 유량비를 기준으로 모사되었다. 동특성 예측 프로그램의 작성을 위해 구성품별 동특성 모델링을 수행하고 엔진 시스템을 기준으로 각 모델링을 순차적으로 통합하였다. 예측 프로그램에 구성품의 동특성 파라미터를 측정 반영하였고 천이 작동 상태에서 엔진 시스템 내의 작동 파라미터 변화 결과를 실험적으로 측정하고 비교 분석하였다.

• 한국지리정보학회지
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• 제4권2호
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• pp.46-60
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• 2001

본 논문은 객체분산 시스템인 Web GIS시스템를 구축하고 UML을 이용하여 가시화, 시스템 구조와 행동을 명세화하였다. GIS의 UML 개념모델의 연구는 Shapefile를 모델개념으로 클래스도와 스테레오타입으로 추상화하였다. 통합된 모델인 UML을 사용하여 아키텍처와 역공 학을 중심으로 모델링하였다. 본 연구는 시스템을 구축하고 기본 형태를 제공하며, 시스템 분석/설계의 문서화를 통하여 S/W시스템의 기본 요소를 객체 또는 클래스로 파악하여 문제 영역과 해결 영역을 모델링함으로써 요구사항 변화시 적응력을 높이고 대규모 시스템에서 유지 보수들을 포함한 관리를 보다 능동적으로 관리할 수 있음을 제시할 수 있었다.

• 한국군사과학기술학회지
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• 제9권1호
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• pp.135-143
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• 2006

This paper describes a requirement architecture modeling for the front end of KT-1 export version requirement definition processes to construct SDS(system development specification). The requirement definition process is a highly conceptual process that is difficult to carry out. This paper focuses on how to perform the KT-1 export version requirements definition process including the integration of process, methods and tools for the front-end activity of requirements definition process. This requirement model is structured in four segments, including requirement layering, requirement categorization, life cycle stakeholder and requirement definition process using Computer-Aided Systems Engineering tool(CORE).

• 한국실천공학교육학회논문지
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• 제4권2호
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• pp.129-135
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• 2012

전기자동차들을 수학적으로 모델링하고 시뮬레이션 하는 많은 방법들이 있다. 전기 자동차의 각 요소들은 다른 물리적인 배경과 모델들을 갖고 있으나, 하나의 수학적 모델로 구성하기란 어려우므로 다양한 물리적 모델이 요구된다. 시뮬레이션이 목적에 따라 수행할 시뮬레이션에 관한 디양한 레벨들이 있다. 즉, 개념 체계 레벨, 회로 레벨, 더 상세한 요소레벨로 구성된다. 본 연구에서는 전기 자동차에서 여러 가지 요소들에 대한 다양한 물리적 모델들과, 다중레벨 시뮬레이션에 관하여 연구하고자 한다. 또한, 본 시뮬레이션 방법은 공학교육에 학습효과를 향상 시킬 수 있다.

• Journal of Hydrospace Technology
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• 제2권1호
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• pp.41-54
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• 1996

Sculptured surface structures such as ship hulls are traditionally formed up to the required double curved shape by line heating method. The nature of the line heating process is a transient thermal process, followed by a thermo-elastic-plastic stress field. The permanant shape is dependent on many factors involved in the process, Among them are torch speed and path, supplied heat type and amount , and plate size. Thus, the work is essentially leaded by experts with lots of experiences. However, in order to effectively improve productivity through automation, each factor should be clearly examined how much it affects the final shape. This can not be done only by experiments, but can be achieved by a mechanics-based approach. In this paper, we propose a conceptual configuration for plate forming system, and then present simulations of the line heating process with numerical data in practices and suggest a computerized process of the line heating for practical applications. The modeling of heating torch, water cooling, and the plate to be formed is proposed for the finite element analysis after the mechanics of line heating is studied. Parametric studies are given and discussed for the effects of plate thickness, torch speed and initial curvature in forming a saddle typed surface.

• 지질공학
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• 제5권2호
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• pp.155-165
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• 1995

열극암반내의 지하수유동 및 용질이동 해석을 위해서는 추계론적인(Simulation Techique) 3차원 불연속체 모형(Discrete Fracture Model)이 요구된다. Monte Carlo 모의기법(Simulation Techique)에 의해 구성된 추계론적 불연속체모형을 지하 유류저장공동의 기밀성평가를 위한 지하수유동 및 용질이동 모의에 적용하였다. 불연속체모형구성에 영향을 미치는 열극 특성요소는 방향서 및 크기로 분석되었으며, 구성도니 모형(Model)에서의 지하수유동에 영향을 미치는 요소는 투수성 열극밀도로 분석되었다. Particle Tracking 기법을 사용한 불연속체모형의 용질이동 모의에서는 열극의 투수성에 의해 이동경로 및 이동속도에 많은 차이가 관찰되었다. 검증된 추계론적 불연속체모형은 지하 유류저장공동 기밀성평가에 적용이 가능함이 부분적으로 인정되었다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.1060-1066
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• 2008

Bi-modal tram is a new conceptual transit mean for public transportation integrating thoroughfare and railroad vehicle's characteristics together. This paper describes about a software design which will be applied to an automatic driving system, which is called NCS (Navigation Control System), considering such multiplicity of mechanical characteristic. The NCS adopts propulsion, braking, and direction control functions for a tram and utilizes various sensors to fully take control over such functions. In this paper, we defined and analyzed the capabilities of the NCS. Those capabilities are designed with a UML 2.0 based object-oriented modeling technique. Moreover, to ensure the complete operation of such capabilities, a communication protocol (which is capable of controlling sensors, propulsion, brakes, and traveling directions) is designed here. Throughout the paper, firstly, all the NCS related functions are discussed in accordance with the equipments they are belonged to; secondly the UML modeling application techniques for the defined functions and protocols for the communications between equipments are introduced; and lastly a validation process for the design specifications is going to be discussed.

• ETRI Journal
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• 제27권4호
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• pp.341-354
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• 2005

The adaptation of video according to the heterogeneous and dynamic resource constraints on networks and devices, as well as on user preferences, is a promising approach for universal access and consumption of video content. For optimal adaptation that satisfies the constraints while maximizing the utility that results from the adapted video, it is necessary to devise a systematic way of selecting an appropriate adaptation operation among multiple feasible choices. This paper presents a general conceptual framework that allows the formulation of various adaptations as constrained optimization problems by modeling the relations among feasible adaptation operations, constraints, and utilities. In particular, we present the feasibility of the framework by applying it to a use case of rate adaptation of MPEG-4 video with an explicit modeling of adaptation employing a combination of frame dropping and discrete cosine transform coefficient dropping, constraint, utility, and their mapping relations. Furthermore, we provide a description tool that describes the adaptation-constraint-utility relations as a functional form referred to as a utility function, which has been accepted as a part of the terminal and network quality of service tool in MPEG-21 Digital Item Adaptation (DIA).