• 한국정보처리학회논문지
• /
• 제3권6호
• /
• pp.1433-1442
• /
• 1996

자료 분산은 SPMD(Single Program Multiple Data)형태의 병렬성을 제공하는 HPF (High Performance Fortran)의 주기능으로 구현 방법에 따라 컴파일러 성능을 좌우한 다. 본 논문에서는 SPAX(Scalable Parallel Architecture computer based on X-bar network)상에 자료 분산 기능을 제공하기 위한 설계 주안점과 효율적인 모델에 관하 여 기술하였다. SPAX는 분산공유 메모리 (DSM:distributed shared memory)를 사용한 계층적 클러스터링 구조를 가진다. 이러한 메모리 구조에서는 분산 메모리 자료 분산 (DMDD:Distributed Memory Data Distribution)이나 공유 메모리 자료 분산(SMDD: Shared Memory Data Distribution)방법으로는 시스템 가용성을 만족할 수 없다. 그래 서 계층적 마스터-슬래브 형태의 분산공유 메모리 자료분산(DSMDD:Distributed Shared Memory Data Distribution)모델을 설계하였다. 이 모델은 각 노드에 원격 마 스터와 슬래브들을 할당하고 노드내에서는 공유 메모리를 그리고 노드간에는 메세지 전달 인터페이스를 사용한다. 시뮬레이션을 수행한 결과, 시스템 성능 저하를 최소화 하는 노드 크기로 DSMDD를 수행하였을 때 SMDD나 DMDD보다 훨씬 더 효율적이였다. 특 히, 논리적 프로세서 갯수가 많을수록, 분산된 자료들 간의 자료 종속성이 적을수록 성능이 우수하였다.

• 한국지하수토양환경학회지:지하수토양환경
• /
• 제8권4호
• /
• pp.21-26
• /
• 2003

황과 Powers(2003)는 입도분포와 공극크기분포에 로그분포함수를 적용하여, 입도분포로부터 토양수분특성을 직접 추정하는 간단한 모형을 개발하였다. 본 연구의 목적은 황과 Powers(2003)가 개발한 모형의 추정능력이 토성에 의해 영향을 받는가를 밝히는 것이다. 연구결과, 모형은 토성에 의해 영향을 받았고, 특히 토양내 세립질 분율이 커질수록 모형의 추정능력은 감소하였다. 또한 입도와 공극크기사이의 관계를 비선형으로 가정한 비선형모형이 선형모형보다 토성에 관계없이 그 추정능력이 크게 나타났다.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2005년도 추계 학술대회논문집(수송기계편)
• /
• pp.114-117
• /
• 2005

In the reactive concentric resonator, perforated inner tubes are widely used for various purposes related to noise reduction, flow guiding, and structural aspects. Perforation distribution patterns influence both the acoustic performance and mechanical performance. In this study, the influence of distribution patterns on acoustic performance are explained by adopting the concept of extended inlet/outlet length. Predicted transmission with varying extended inlet/outlet length is compared with prediction by varying distribution patterns. The transmission loss difference due to perforation distribution patterns can be explained by changing the extended inlet/outlet length of the uniformly perforated resonator.

• Computers and Concrete
• /
• 제10권2호
• /
• pp.105-119
• /
• 2012

This paper presents the mix composition and production method that was applied to an extruded Ductile Fiber Reinforced Cement Composite (DFRCC) panel, as well as the flexural performance, represented by deformation hardening behavior with multiple cracking. The effect of fiber distribution characteristics on the flexural behavior of the panel is also addressed. In order to demonstrate the fiber distribution effect, a series of experiments and analyses, including a sectional image analysis and micromechanical analysis, was performed. From the experimental and analysis results, it was found that the flexural behavior of the panel was highly affected by a slight variation in the mix composition. In terms of the average fiber orientation, the fiber distribution was found to be similar to that derived under the assumption of a two-dimensional random distribution, irrespective of the mix composition. In contrast, the probability density function for the fiber orientation was measured to vary depending on the mix composition.

• Journal of Electrical Engineering and Technology
• /
• 제9권1호
• /
• pp.45-51
• /
• 2014

Distribution system is a critical link between customer and utility. The control of power loss is the main factor which decides the performance of the distribution system. There are two methods such as (i) distribution system reconfiguration and (ii) inclusion of capacitor banks, used for controlling the real power loss. Considering the improvement in voltage profile with the power loss reduction, later method produces better performance than former method. This paper presents an advanced evolutionary algorithm for capacitor inclusion for loss reduction. The conventional sensitivity analysis is used to find the optimal location for the capacitors. In order to achieve a better approximation for the current candidate solution, Opposition based Differential Evolution (ODE) is introduced. The effectiveness of the proposed technique is validated through 10, 33, 34 and85-bus radial distribution systems.

• 조명전기설비학회논문지
• /
• 제25권6호
• /
• pp.115-121
• /
• 2011

Intelligent distribution equipment is inevitable to realize self-healing which is one of smart grid functions in distribution network. Therefore, most of distribution equipment have been developed with self diagnostic sensors. However, it is not effective to construct on-line monitoring system for underground distribution cable because of high cost and low sensitivity. Recently, optical fiber composite cable is being considered for communication and power delivery in order to cope with increasing communication in distribution network. This paper presents the design and performance assessment results of underground cable on-line monitoring system using DTS(Distributed Temperature Sensing) and optical fiber composite underground cable.

• 콘크리트학회논문집
• /
• 제23권3호
• /
• pp.365-376
• /
• 2011

현행 콘크리트구조설계기준(2007)은 콘크리트 구조물의 설계에 적용하는 콘크리트의 압축응력 분포로 ACI 318의 등가 직사각형 응력 분포를 규정하고 있다. 단면의 휨강도 해석에는 등가 직사각형 응력 분포가 충분하겠지만, 성능 중심 설계의 한계 상태 검증에는 실제와 가까운 압축응력-변형률 관계가 필요하다. 또 등가 직사각형 응력 분포는 고강도 콘크리트 기둥의 휨강도 해석에 비안전측의 결과를 준다는 것이 알려져 있으므로, 이를 대신하는 새로운 응력 분포 모델이 필요하다. 이 연구에서는 Eurocode와 일본 토목학회의 설계기준에서 채택하고 있는 포물선-직선 형상의 새로운 모델을 제안하였다. 이 응력 분포 모델은 이 연구에서 수행된 압축응력 분포 실험과 타 연구자들의 실험 결과를 분석하여 도출된 것으로서, 보통 강도뿐만 아니라 고강도 콘크리트를 포함한 것이다. 제안 모델의 특성은 미국 ACI 318, 캐나다 CSA, 유럽의 Eurocode, 일본 토목학회 설계기준의 응력 분포 모델과 함께 실험 결과와 비교하여 정리하였다.

• 한국자동차공학회논문집
• /
• 제22권7호
• /
• pp.48-56
• /
• 2014

Engine oil is an oil used for lubrication of various internal combustion engines. The main function is to reduce wear on moving parts; it also cleans, inhibits corrosion, improves sealing, and cools the engine by carrying heat away from moving parts. In engines, there are parts which move against each other. Otherwise, the friction wastes the useful power by converting the kinetic energy to heat. Those parts were worn away, which could lead to lower efficiency and degradation of the engine. It increases fuel consumption, decreases power output, and can induce the engine failure. This study was conducted to evaluate the relation between engine oil property changes and engine performance for the diesel engine. This test was performed by using 12L, 6 cylinder, heavy duty engines. Low SAPS 10W30 engine oil (two type engine oils) was used. Test procedure and method was in accordance with the modified CEC L-57-T97 (OM441LA) method. In this study, TAN, TBN, KV and metal components, engine power, blowby gas, A_F were presented to evaluate the relation with engine oil property changes and engine performance. TAN, TBN, KV and metal We found that the components were generally increased but engine performance did not change. This results mean that property changes did not affect on engine performance because those were not enough to affect engine performance.

• International Journal of Naval Architecture and Ocean Engineering
• /
• 제13권1호
• /
• pp.367-378
• /
• 2021

This paper develops a dynamic regression model to quantify the contribution of key external factors to operational energy efficiency of ships. On this basis, kernel density estimation is applied to explore distribution patterns of fluctuations in operational performance. An empirical analysis based on these methods show that distribution of fluctuations in Energy Efficiency Operational Indicator (EEOI) is leptokurtic and fat tailed, rather than a normal one. Around 85% of fluctuations in EEOI can be jointly explained by capacity utilization and sailing speed, while the rest depend on other external factors largely beyond control. The variations in capacity utilization and sailing speed cannot be fully passed on to the energy efficiency performance of ships, due to complex interactions between various external factors. The application of the methods is demonstrated, showing a potential approach to develop a rating mechanism for use in the legally binding framework on operational energy efficiency of ships.

• 설비공학논문집
• /
• 제30권3호
• /
• pp.143-148
• /
• 2018

In this study the performance and humidity variation for 2 unit cells connected in series were experimentally measured. The relative flow direction of hydrogen and air was changed from parallel flow to counter flow. Internal humidity distribution was then measured by 5 embedded sensors on each channel. In all experimental conditions, the former unit cell showed a better performance and the gap is noted to be higher when counter flow is applied. The performance was noted to be higher at high humidification case in the parallel flow. However, in the counter flow, the difference of performance according to the humidification is negligible. Hydrogen and air are discharged from the PEMFC unsaturated with water vapor at parallel flow/low humidification condition, which explains lower performance of the PEMFC than other conditions. The humidities in hydrogen and air streams of counter flow were noted to increase rapidly even at low humidification condition and the consequential even hydration of membrane is the reason of higher performance.