• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1995년도 춘계학술대회논문집
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• pp.124-130
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• 1995

An upper-bound elemental stream function technique(UBST) is proposed for solivng forging and backward extrusion problems that are geometrically complex or need a forming simulation . And in the forging problems, this study investigates that layer of elements effects dissipation of total energy and load. The element system of UBSTuses the curve fitting property of FEM and the fluid incompressiblity of the stream function . The foumulated optimal design problems with constraints ae solved by the flixible toerance method. In the closed-die forging and backward extrusion, the result of layer of element by this study produces a lower upper-bound solution than that fo UBET and conventional layer of element . And the main advantage of UBST program is that a computer code, once written , can be used for a large variety problems by simply changing the input data.

• 한국항행학회논문지
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• 제17권3호
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• pp.292-297
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• 2013

본 논문에서는 혼돈 스트림 발생기에 사용되는 혼돈합성함수의 디지털 회로설계를 연구 하였다. 혼돈키 스트림 발생기의 수학적 모델에 기인하는 전반적인 설계 개념과 절차를 자세히 설명하였다. 또한 혼돈 함수에 대한 이진화 2진 진리표를 보였다. 결과로서 1차원과 2차원 두 종류의 혼돈맵들-텐트맵과 삐뚤어진 로지스틱 맵-을 연결시켜 합성맵으로 사용하는 합성상태머신의 설계를 제시하였다.

• 물과 미래
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• 제29권4호
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• pp.139-147
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• 1996

유역의 하천형태학적 특성은 그 유역의 수문 및 수리학적특성과 밀접한 관계를 가지고 있다. 본연구는 우리나라 중부지방의 중소하천에 대한 계획하폭을 산정하는 공식을 제시하는데 목적이 있다. 계획홍수량과 유역면적 및 하천연장의 자료로서 하폭을 얻는데 다음과 같은 결론을 얻었다. : (1) 계획홍수량(Q)과 하폭(B)의 관계로 나타낸 하폭식은 $B=1.532A^{0.644.}$; (2) 유역면적(A)과 하폭(B)과의 관계로 나타낸 하폭식은 $B=12.392A^{0.511}$; (3) 하천연장(L)과 하폭(B)과의 관계로 나타낸 하폭식은 $B=10.509l^{0.852}$.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 1996년도 학술발표회 논문집
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• pp.514-520
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• 1996

• 한국환경생태학회:학술대회논문집
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• 한국환경생태학회 2010년 학술대회 논문집
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• pp.112-117
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• 2010

• 한국시뮬레이션학회논문지
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• 제12권4호
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• pp.95-102
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• 2003

Stream servers are for supplying multimedia stream data to users through the internet such as movies and music without discontinuation. A typical stream server is designed roughly by considering the characteristics of stream services and by employing processors, memory, PCI bus, Ethernet, TOE and disks. This study focuses on deciding the priority for using resources such as PCI bus, buffer memory and TOE buffer, which have limited capacities in a typical stream server. When the priorities for using limited resources are not given properly, the stream servers may not even function as originally designed. The simulation study shows that the top priority for using PCI bus for normal streaming services should be given to the operation that sends data from buffer memory to TOE buffer. Giving priority for using PCI bus to other operation such as sending data from disks to memory results in a deadlock phenomenon.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2009년 추계학술대회논문집
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• pp.49-55
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• 2009

This paper evaluates performances of a recently developed divergence-free finite element method based on Hermite interpolated stream functions. Velocity bases are derived from Hermite interpolated stream functions to form divergence-free basis functions. These velocity basis functions constitute a solenoidal function space, and the simple gradient of the Hermite functions constitute an irrotational function space. The incompressible Navier-Stokes equation is orthogonally decomposed into a solenoidal and an irrotational parts, and the decoupled Navier-Stokes equations are projected onto their corresponding spaces to form proper variational formulations. To access accuracy and convergence of the present algorithm, three test problems are selected. They are lid-driven cavity flow, flow over a backward-facing step and buoyancy-driven flow within a square enclosure. Hermite interpolation functions from cubic to quintic are chosen to run the test problems. Numerical results are shown. In all cases it has shown that the present method has performed well in accuracies and convergences. Moreover, the present method does not require an upwinding or a stabilized term.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 1983년도 제25회 수공학 연구발표회 논문초록집
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• pp.78-79
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• 1983

It is well known that small amplitude wave theory, a first approximation to the complete theoretical description of wave behavior, yields a maximum investment in mathematical endeavor. But, if the wave amplitude is large, the small amplitude considerations are not valid, and finite amplitude wave theory which retains higher-order terms to obtain an accurate representation of the wave motion is numercal theory. The Stream function wave theory, one of the numerical methods, was developed by Dean for use with asymmetric measured wave profiles and with symmetric theoretical wave profiles. Dalrymple later improved the comjputational procedure by adding two Lagrangian constraints so that more efficient convergence of the iterative numerical method to a specified wave heigh and to a zero mean free surface displacement resulted. This paper introduces in details the Dean and Darlymple Stream Function Method in case of the symmetric theoretical wave, because in design purposes, wave height and wave period are given.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.329-332
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• 2002

The upper bound analysis by stream function is used to study the torsional forward extrusion. The torsional forward extrusion process not only reduces forming load but also increase optimal die angle. Optimal die angle is determined by the optimization technique. The advantages of this process are that the low capacity of pressing machine can be used and the process with a large die angle can be applied. To verify the theoretical result, we have carried out experiments using model material (plasticine) and FE simulations using DEFORM3D.

• 한국농공학회논문집
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• 제55권6호
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• pp.177-186
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• 2013

The purpose of this study was to analyze the temporal and spatial characteristics of the stream flow of small rural streams for investigating the status of stream depletion located downstream of irrigation reservoir. Bonghyun and Hai reservoirs and each downstream were selected for this study. Streamflow was measured for 8 stations downstream from two reservoirs from 2010 to 2012. The water quality samples were collected monthly from the 8 stream stations and 2 reservoir stations from 2011 to 2012. The stream depletion was found in most of the downstream of reservoirs for the non-irrigation period and even in the irrigation period when there were a lot of antecedent precipitation. We found that the stream segments where there were few streamflow, vegetation covers the stream and block the streamflow which makes the stream lost its original function as a stream. Water quality monitoring results of Bonghyun stream indicated that the concentration of SS, Turbidity, TOC, COD were decreased as the stream flows from the reservoir to downstream while the TN and TP were increased. The correlation analysis for water quality data indicated that the correlation between T-N and T-P was high for Bonghyeon and Sukji streams, respectively. Continuous monitoring for rural streams located in downstream of reservoirs are required to quantify the status of stream flow depletion and determine the amount of environmental flows.