• 한국컴퓨터정보학회논문지
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• 제26권2호
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• pp.1-9
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• 2021

본문에서는 순수 함수형 언어인 하스켈로 작성된 심볼릭 실행의 병렬화를 위한 상태 모나드 기반의 라이브러리에 결정적 병렬화를 적용하기 편리한 API를 설계/구현하고 멀티코어 컴퓨터에서 벤치마크를 통해 실제 성능을 향상을 확인해 본다. 일반적으로 순수 함수형 프로그램은 병렬화가 쉽다고 알려져 있으나 실제 구현에서 핵심 알고리듬 외적인 부분에서 의도치 않은 순차적 데이터 의존성의 발생으로 병렬화가 어려워질 수 있다. 심볼릭 실행 구현에서는 지금껏 사용했던 변수와 겹치지 않는 새 이름을 생성함으로써 서로 다른 범위의 이름이 같은 변수끼리 혼동하는 착오를 피하는 방식을 종종 활용한다. 그런데 이를 순차적 상태 관리로 구현한 경우가 많아 병렬화에 걸림돌이 된다. 이 논문에서는 하스켈의 범용적 이름 관리 라이브러리인 unbound-generics의 새 이름 생성 기능에 순차적 의존성을 회피할 수 있는 확장 기능을 제공함으로써 병렬적 심볼릭 실행 구현을 간소화하는 데 기여하였다. 우리가 구현한 병렬화 확장의 특징은 기존 unbound-generics 라이브러리의 내부 구현을 그대로 유지한 상태의 확장이라는 점으로, 기존에 unbound-generics로 작성된 순차적 심볼릭 실행기의 성능 저하 우려가 전혀 없다는 점이다. 따라서 병렬화가 필요한 부분에만 확장 기능을 적용하는 방식으로 활용하여 성능을 개선할 수 있다.

• 대한토목학회논문집
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• 제44권2호
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• pp.161-172
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• 2024

일반적으로 수문기상변량의 상관관계를 파악하기 위해서는 Copula 기법을 활용하여 의존관계를 규명하고 있으나, 단순히 Copula 기법을 다변량으로 확장하는 것은 분석결과가 유연하지 않으며 Copula 기법에 대한 수학적인 가정을 확인하여 만족 여부를 판단해야 하는 등 복잡해지는 단점이 있다. 또한, 기존의 이변량 Copula 기법을 활용하여 기후변화모델의 지속시간에 따른 설계강우량을 추정하는 과정은 주로 일별 자료만을 활용하여 분석하므로 24시간 최대강우량에 대한 정보와의 의존관계를 규명하여 추정하는 방법을 채택하고 있다. 그러나, 24시간 최대강우량만을 활용하여 다른 지속시간에 대한 설계강우량을 산정하는 것은 다른 지속시간에 대한 의존관계 정보는 제공되지 않아 지속시간에 따른 강우 강도가 역전되는 현상이 야기되는 원인이다. 따라서, 본 연구에서는 변수간의 쌍구조 관계를 연결하는 Vine Copula 기법을 활용하여 다른 지속 시간에 대한 정보를 반영하여 미래 강우강도의 변화를 전망하고자 한다.

• Wind and Structures
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• 제12권4호
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• pp.349-381
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• 2009

Since 1998, several institutions have deployed mobile instrumented towers to collect research-grade meteorological data from landfalling tropical cyclones. This study examines the wind flow characteristics from seven landfalling tropical cyclones using data collected from eight individual mobile tower deployments which occurred from 1998-2005. Gust factor, turbulence intensity, and integral scale statistics are inspected relative to changing surface roughness, mean wind speed and storm-relative position. Radar data, acquired from the National Weather Service (NWS) Weather Surveillance Radar - 1988 Doppler (WSR-88D) network, are examined to explore potential relationships with respect to radar reflectivity and precipitation structure (convective versus stratiform). The results indicate tropical cyclone wind flow characteristics are strongly influenced by the surrounding surface roughness (i.e., exposure) at each observation site, but some secondary storm dependencies are also documented.

• 한국초전도ㆍ저온공학회논문지
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• 제3권1호
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• pp.6-10
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• 2001

Stress/stram dependencies of the critical current $I_c$ in AgMgNi sheathed multifilamentary Bi(2212) superconducting tapes were evaluated at 77K, 0T. The external reinforcement was accomplished by soldering Ag-Mg tapes to sin91e side or both sides of the sample. With the external reinforcement. the strength of tapes increased but $I_c$, decreased The $I_c$, degradation characteristic according to the external reinforcement was improved markedly in terms of the stress although it appeared less rectal.table on the basis of the strain. Effects of external reinforcement were discussed in a viewpoint of monitoring sensitivity of cracking in superconducting filaments by considering n-value representing the transport behavior of the current. It is closely associated with the location of them relative to the voltage-monitoring region in the tape.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2002년도 춘계 학술발표회 논문집
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• pp.373-382
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• 2002

In this paper, the characteristic dependencies of LRB(lead rubber bearing) were studied by various prototype tests on LRB for buildings. The characteristics of LRB were dependent on displacements, repeated cycles, frequencies, vertical pressures and temperatures. The prototype test showed that the displacement was the most governing factor influencing on characteristics of LRB. The effective stiffness and equivalent damping of LRB were decreased with large displacement, and increased with high frequency. After the repeated cyclic test with 50 cycles, the effective stiffness and equivalent damping of LRB were reduced by approximately 20% compared with those of the 1$^{st}$ cycle. The effective stiffness was decreased with high vertical pressure, while the equivalent damping was increased. In which, the equivalent damping was more dependent on the vertical pressure than the effective stiffness.s.

• 설비공학논문집
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• 제8권4호
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• pp.451-462
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• 1996

In this study, which focuses on ice storage, a fundamental study in cooling and solidification was performed, including the interesting phenomena of density inversion, supercooling and dendritic ice. A numerical study was performed for natural convection and ice formation considering existence of subcooling and dendritic ice were analyzed numerically by using finite difference method and boundary fixing method. In the mesh, the solid fraction was introduced with adding as a term to the energy conservation equation. A flow in the dendrite was modelled as a flow in a porous medium, and the momentum conservation equation was modified to incorporate resistance forces involved in flows through porous media. A numerical solution of the time dependencies of dendrite area and dense ice front was successfully obtained, and the numerical results were good agreement with experimental results. Based on this methodology, a discussion was made of phenomena and characteristics of cooling and freezing processes under various conditions.

• Advances in aircraft and spacecraft science
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• 제3권4호
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• pp.503-521
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• 2016

Variances in turbomachinery blades caused by manufacturing, operation or regeneration can result in modified structural behavior. In this work, the scatter of geometrical and material properties of a turbine blade and its influence on structure performance is discussed. In particular, the vibration characteristics and the lifetime of a turbine blade are evaluated. Geometrical variances of the surface of the blades are described using the principal component analysis. The scatter in material properties is considered by 16 varying material parameters. Maximum vibration amplitudes and the number of load cycles the turbine blade can withstand are analyzed by finite element simulations incorporating probabilistic principles. The probabilistic simulations demonstrate that both geometrical and material variances have a significant influence on the scatter of vibration amplitude and lifetime. Dependencies are quantified and correlations between varied input parameters and the structural performance of the blade are detected.

• 대한수학회지
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• 제35권3호
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• pp.539-557
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• 1998

This paper is concerned with the performance evaluation of loss networks. We shall review the Erlang Fixed Point (EFP) method for estimating the blocking probabilities, which is based on an assumption that links are blocked independently. For networks with linear structure, the behaviour of adjacent links can be highly correlated. We shall give particular attention to recently-developed fixed-point methods which specifically account for the dependencies between neighbouring links. For the network considered here, namely a ring network with two types of traffic, these methods produce relative errors typically $10^{-5}$ of that found using the basic EFP approximation.

• 한국컴퓨터산업학회논문지
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• 제6권2호
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• pp.365-372
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• 2005

일반적으로 응용프로그램에서 병렬성 추출에 대한 핵심 부분은 루프이고 루프내의 첨자변수들 사이에는 자료종속성이 존재한다. 특히 문장들 사이에 가변 및 불변종속거리를 갖는 종속관계는 매우 복잡하다. 따라서 이 경우 컴파일 시 병렬성 추출은 매우 어렵다. 따라서 본 논문에서는 기존에 제시되어있는 병렬성 추출 방법들 중에서 unimodular방법과 non-unimodular방법에 대하여 분석하고 이들의 장단점을 파악하여 향후 효율적인 종속성 제거방법을 제안하는데 도움이 되고자한다.

• 한국정보과학회논문지:소프트웨어및응용
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• 제26권1호
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• pp.139-139
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• 1999

In most application programs, loops usually comprise most of the computation in a program and the most important source of parallelism. When the data dependency relation is uniformin terms of distance, several compile time parallelization methods were introduced. On the otherhand,when the data dependency relation is non-uniform in distance, the compile time extraction ofparallelism is much complicated. In this paper, a general method the extracting parallelism in nestedloops is presented. This algorithm can be applicable where the dependency relation is both uniform andnon-uniform in distance. According to execution repeatedly the statements in nested loops, thealgorithm which effectively removes these kind of data dependencies is developed in order to presentthe total parallelization of nested loops.