• Wind and Structures
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• 제19권6호
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• pp.687-708
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• 2014

The performance of the $k-{\varepsilon}$ and $k-{\omega}$ two-equation turbulence models was investigated in computational simulations of the neutrally stratified atmospheric boundary layer developing above various terrain types. This was achieved by using a proposed methodology that mimics the experimental setup in the boundary layer wind tunnel and accounts for a decrease in turbulence parameters with height, as observed in the atmosphere. An important feature of this approach is pressure regulation along the computational domain that is additionally supported by the nearly constant turbulent kinetic energy to Reynolds shear stress ratio at all heights. In addition to the mean velocity and turbulent kinetic energy commonly simulated in previous relevant studies, this approach focuses on the appropriate prediction of Reynolds shear stress as well. The computational results agree very well with experimental results. In particular, the difference between the calculated and measured mean velocity, turbulent kinetic energy and Reynolds shear stress profiles is less than ${\pm}10%$ in most parts of the computational domain.

• 시스템엔지니어링학술지
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• 제11권1호
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• pp.55-65
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• 2015

In steel making plant, sampling system for raw material such as iron ore, limestone is necessary for quality control purpose. For the sake of efficiency and productivity, automation of the sampling system is highly desirable. From technical standpoint, the development of the automated system requires multi-disciplinary domain knowledge such as mechanical engineering, industrial engineering, information technology and computer engineering. Up to present time, the development has been mainly carried out by a single domain expert with project manager. The automated system developed in this way caused problems in the final system. This paper suggests a systems engineering approach to the development of automation for raw material sampling plant via a tailored process called Plant Systems Engineering (PSE) Process based on ISO/IEC 15288. Through the PSE process, we could derive right requirements and architecture of the Systems Of Interest (SOI), and we were convinced that the PSE Process can be applied to many other Plant Systems.

• 정보처리학회논문지C
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• 제9C권3호
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• pp.421-430
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• 2002

본 논문에서는 PC나 라우터, 서버 장비 등 모든 정보자윈 시스템을 통합 관리하기 위한 시스템을 제안한다. 이 시스템은 PC 및 라우터의 회선에 대한 성능 분석 항목을 정의하고 분석하며, 서버 장비에 대한 자산 관리를 수행한다. 관리자는 분석된 데이터를 바탕으로 현재 시스템이나 회선에 대한 상태를 파악하기 위한 자료로 활용할 수 있다. 시스템의 구조는 차후 관리 도메인의 증설이 쉽고, 효율적으로 관리하기 위해 3계층으로 구분하여 관리하고자 한다.

• 전자공학회논문지T
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• 제35T권1호
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• pp.59-66
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• 1998

본 논문은 에러 정정 코드로서 가장 많이 사용하는 RS(Reed-Solomom)코드를 이용한 고속 복호기 설계에 관한 논문이며 VHDL을 사용하여 실행을 하였으며, 이 RS 복호기는 시간 영역 대신 변환 영역에서 설계하였다. 변환 복호기는 구조의 단순성 때문에 VLSI칩 설계가 용이하며, 모든 설계에 대하여 systolic 배열을 적용하기 쉬운 파이프라인 아키텍춰를 사용하였다. 변환 RS 복호기는 고속 데이타 전송율을 갖는 복호기에 적합하여 FPGA 기술로 합성 한 후 복호율은 43MByte/s 보다 더 크고 범위는 1853 LCs(Logic Cell)을 갖는다. 파이프라인을 갖는 다른 아키텍춰와 비교하여 볼 때 이러한 결과는 다른 기술과 비교하여 우수한 기술이며, 에러 정정 능력과 파이프라인 성능은 컴퓨터 시뮬레이션을 통하여 검증하였다.

• 한국해양공학회지
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• 제38권2호
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• pp.53-63
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• 2024

Submerged breakwaters can be installed underneath floating structures to reduce the external wave loads acting on the structure. The objective of this study was to establish an optimization analysis framework to determine the corresponding shape and position of the submerged breakwater that can minimize or maximize the external forces acting on the floating structure. A two-dimensional frequency-domain boundary element method (FD-BEM) based on the linear potential theory was developed to perform the hydrodynamic analysis. A metaheuristic algorithm, the advanced particle swarm optimization, was newly coupled to the FD-BEM to perform the optimization analysis. The optimization analysis process was performed by calling FD-BEM for each generation, performing a numerical analysis of the design variables of each particle, and updating the design variables using the collected results. The results of the optimization analysis showed that the height of the submerged breakwater has a significant effect on the surface piercing body and that there is a specific area and position with an optimal value. In this study, the optimal values of the shape and position of a single submerged breakwater were determined and analyzed so that the external force acting on a surface piercing body was minimum or maximum.

• 대한조선학회논문집
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• 제49권1호
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• pp.60-67
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• 2012

This study considers the numerical analysis on parametric roll for container ships. As a method of numerical simulation, an impulse-response-function approach is applied in time domain. A systematic study is carried out for the parametric roll of two container ships, particularly observing the sensitivity of computational results to some parameters which can affect the analysis of parametric roll. The parameters to be considered are metacentric height (GM), simulation time window, and the discretization of wave spectrum. Based on the result of parametric roll simulation, numerical sensitivity and uncertainty in computational analysis are discussed.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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• pp.795-797
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• 2003

GIS can supply large quantitiy of useful information about spacial relationship, consequently there exists great potential of GIS support ing for decision making strategies related to urban design and environmental planning. In different discipline areas there exist different information representation methods and considerations having direct or indirect relationship with spacial information, how to use GIS as a tool for facilitating the work in other discipline field, there are two basic questions crucial to the success of these interdiscipline applications. The first one is interoperatability among GIS and other applications, the second is the paradigm difference between GIS and other domain field regarding problem solving. In this paper, we investigate the spatial information of the urban environment provided in the analyses of the urban visual sustain ability, urban daylighting environment and urban wind environment. We also discuss the challenges and opportunities for cross-disciplinary GIS application regarding the aspect of Information Collection, Information Generation, Information Analysis and Information Visualization.

• Earthquakes and Structures
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• 제7권6호
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• pp.1025-1044
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• 2014

In this paper, a systematic technique is proposed for the optimal placement and design of nonlinear dampers for building structures. The concept of Output Frequency Response Function (OFRF) is applied to analytically represent the output frequency response of a building frame where nonlinear viscous dampers are fitted for suppression of vibration during earthquakes. An effective algorithm is derived using the analytical representation to optimally determine the locations and parameters of the nonlinear dampers. Various numerical examples are provided to verify the effectiveness of the optimal designs. A comparison of the vibration suppression performance with that of the frame structure under a random or uniform damping allocation is also made to demonstrate the advantages of the new designs over traditional solutions.

• 전자공학회논문지A
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• 제32A권12호
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• pp.220-228
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• 1995

An optimized 4-stage 12-bit pipelined CMOS analog-to-digital converter (ADC) architecture is proposed to obtain high linearity and high yield. The ADC based on a multiplying digital-to-analog converter (MDAC) selectively employs a binary-weighted-capacitor (BWC) array in the front-end stage and a unit-capacitor (UC) array in the back-end stages to improve integral nonlinearity (INL) and differential nonlinearity (DNL) simultaneously whil maintaining high yield. A digital-domain nonlinear error calibration technique is applied in the first stage of the ADC to improve its accuracy to 12-bit level. The largest DNL error in the mid-point code of the ADC is reduced by avoiding a code-error symmetry observed in a conventional digitally calibrated ADC is reduced by avoiding a code-error symmetry observed in a conventional digitally calibrated ADC is simulated to prove the effectiveness of the proposed ADC architecture.

• 대한조선학회논문집
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• 제50권5호
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• pp.343-348
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• 2013

When a natural frequency of the trailing edge of a wing is close to a vortex shedding frequency, an amplitude of the edge oscillation becomes maximal; it makes intensive noise called singing. Motion of the trailing edge may also feedback to the vortex shedding so that self-sustained oscillation appears, and a resonant frequency is locked in some interval of the speed of the incident flow. In this study, we first evaluate main features of oscillating characteristics of the wing. Second we simulate fluid-structure interaction of the wing with a flap using a commercial code, ANSYS-CFX, and investigate lift characteristics in a frequency domain.