• 대한전기학회논문지:전력기술부문A
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• 제52권6호
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• pp.325-332
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• 2003

The loss minimization is one of the most important problems to save the operational cost in distribution systems. This paper presents an efficient method for optimal feeder reconfiguration of distribution systems. Chaos search algorithm (CSA) is used to reconfigure distribution systems so that active power losses are globally minimized with turning on/off sectionalizing switches. In optimization problem, the CSA searches the global optimal solution on the basis of regularity in chaotic motions and easily escapes from local or near optimal solution. The CSA is tested on 15 buses and 32 buses distribution systems, and the results indicate that it is able to determine appropriate switching options for global optimum reconfiguration.

• 대한기계학회논문집B
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• 제29권8호
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• pp.887-894
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• 2005

This paper describes effects of incidence angle on the wake turbulent flow of a high-turning turbine rotor blade. For three incidence angles of -5, 0 and 5 degrees, energy spectra as well as profiles of mean velocity magnitude and turbulence intensity at mid-span are reported in the wake. Vortex shedding fiequencies are obtained from the energy spectra. The result shows that as the incidence angle changes from -5 to 5 degrees, the suction-side wake tends to be widened and the deviation angle is increased. Strouhal numbers based on the shedding fiyequencies have a nearly constant value, regardless of the tested incidence angles.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.436-441
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• 2003

The present study investigates heat/mass transfer characteristics in rotating two-pass ducts of three different aspect ratios with 90-ribbed surfaces. The results show that the flows generated by the 180-turn, rib turbulators, and duct rotation. The curvature of the 180-turn produces Dean vortices causing high heat/mass transfer in the turning region and in the upstream region of the second-pass. The rib turbulators disturb the main flow by producing reattachment and separation near the ribbed surfaces, and increase heat/mass transfer in the region between the ribs. As the rotation number increases, the heat/mass transfer discrepancy between the leading and the trailing surfaces become larger.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2006년도 추계공동학술대회
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• pp.523-529
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• 2006

Nowadays, a logistics and distribution center plays an important role in all industries. In addition to its traditional functions as a storage and unloading facility the distribution center serves as an assembly place for information, a source of information, and a turning point for the flow of information. On account of the above-mentioned reasons, each and every industry has increasing need of logistics distribution center. At this juncture, the present author thinks that it is necessary to make a study of the establishment and maximization of a ceramics logistics distribution center as a way for activating the ceramics industry.

• International Journal of Fluid Machinery and Systems
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• 제4권1호
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• pp.97-103
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• 2011

With the aim to increase blade loadings and stable operating range in highly loaded compressors, this article has been conducted to explore, through a numerical parametric study, the potential of passive control using slotted bladings in cascade configurations. The objective of this numerical investigation is to analyze the influence of location, width and slope of the slots and therefore identify the optimal configuration. The approach is based on two dimensional cascade geometry, low speed regime, steady state and turbulent RANS model. The results show the efficiency of this passive technique to delay separation and enhance aerodynamic performances of the compressor cascade. A maximum of 28.3% reduction in loss coefficient have been reached, the flow turning is increased with approximately $5^0$ and high loading over a wide range of angle of attack have been obtained for the optimized control parameter.

• 한국실내디자인학회:학술대회논문집
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• 한국실내디자인학회 2008년도 춘계학술발표대회 논문집
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• pp.196-202
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• 2008

The interest in natural environment as a new living culture is turning to the programs that give us direct experience rather than indirect one. This change demands new sort of analysis on space in order to design hotel lobby space which satisfies contemporarians' emotion. Hereupon, this article has its purpose of studying the characteristics of environment-friendly expression as a means to approach to the space design of hotel lobby space in which men and nature can coexist and men can be richer in their emotion. Moreover, through the flow and types of environment-friendly design, this study intends to emphasize the importance of introducing natural factors and suggest the possibility of diversification in environment-friendly expression.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2002년도 학술발표회 논문집(II)
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• pp.1027-1033
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• 2002

The solute transport in a two-dimensional heterogeneous porous medium is numerically studied by using a random walk particle tracking (RWPT) method. Lognormally isotropic hydraulic conductivity fields are generated by using the turning band methods with mean zero and four different values of standard deviation. The numerical transport experiments are carried out to investigate the large time and spatial effects of the variable pore velocity field on solute plumes. The behavior of the solute plume through numerical simulations is presented in terms of longitudinal and transverse spatial moments: displacement of center-of-mass, plume spread variance and skewness coefficient. It was observed that the dispersive behavior of the solute plume is strongly affected by the degree of heterogeneity in the flow domain.

• 한국산림과학회지
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• 제82권2호
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• pp.152-165
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• 1993

본(本) 연구(硏究)는 heat pulse법(法)을 이용하여 낙엽송 임분(林分)의 증산량(蒸散量)을 알기 위한 기초 연구로써, 일사량(日射量), 온도(溫度), 습도(濕度) 등의 변화에 따른 heat pulse 속도(速度)의 일변화와 계절변화, 방위별 heat pulse 속도(速度)의 차이, 변재부(邊材部)에 있어서 깊이별 heat pulse 속도(速度)의 차이, 우세목(優勢木), 준우세목(準優勢木), 열세목(劣勢木)의 heat pulse 속도(速度)의 차이, 엽(葉)의 수분(水分)포텐셜과 heat pulse 속도(速度)와의 관계, 줄기에 있어 수분상승의 방향, heat pulse법(法)으로 추산한 임분(林分)의 증산량(蒸散量)등에 대하여 측정 고찰하였다. 얻어진 결과를 요약하연 다음과 같다. 1 낙엽송의 heat pulse 속도(速度)(V)와 수액유속(樹液流速)(SFR)과의 관계는 SFR=1.37V($r=0.96^{**}$)의 식으로 나타냈다. 2. 우세목(優勢木), 준우세목(準優勢木), 열세목(劣勢木)의 heat pulse 속도(速度)를 비교하면, 수액유속(樹液流速)은 우세목(優勢木)이 가장 높고, 준우세목(準優勢木), 열세목(劣勢木) 순위였다. Heat pulse 속도(速度)는 일사량(日射量), 온도(溫度), 대기포차(大氣飽差) 등의 크기에 따라 심한 변화(變化)를 나타냈다. 3. 입목(立木) 개체간(個體間)의 heat pulse 속도(速度)의 차이는 이른 아침과 밤에는 거의 없으나, 일사량(日射量)이 높은 12시부터 16시 사이에는 약간의 차이를 나타냈다. 4. Heat pulse 속도(速度)와 수분(水分)포텐셜은 거의 비슷한 일변화 경향을 나타냈다. 5. Heat pulse 속도(速度)의 계절변화는 8월에 가장 높았고, 10월이 가장 낮았다. 그리고 6, 7, 9월의 heat pulse 속도(速度)는 거의 비슷한 값을 나타냈다. 6. 줄기에 있어 방위별 heat pulse 속도(速度)는 동측이 가장 높았고, 서측과 북측은 비슷한 속도를 나타냈으며, 남측의 속도가 가장 낮았다. 7. 변재부(邊材部)에 있어서 깊이별 heat pulse 속도(速度)의 차이는 수피(樹皮)로부터 2cm 깊이에서 가장 높고, 다음이 1cm 깊이, 그리고 3cm 깊이에서 가장 낮았다. 8. 줄기에 있어 수분이동방향(水分移動方向)은 5본 모두 오른쪽 나선상승(螺旋上昇)(spiral ascent turning right)을 나타내고 있었다. 특히 지상의 3m까지는 매우 느린 회선(回旋)을 나타내다가 그 이상의 수고(樹高)에서는 매우 빠른 회선(回旋)으로 상승됨을 알 수 있었다. 9. 수액유량(樹液流量)(SF)은 SF=1.37AV 식(式)으로 나타났고, 이 식으로 구한 수액유량(樹液流量)은 우세목(優勢木)이 준우세목(準優勢木)과 열세목(劣勢木)보다 현저히 높았다. 10. 1ha의 임분(林分)에 대한 1일의 증산량(蒸散量)의 구성비율(構成比率)은 낮이 83%, 밤이 17%였고, 증산량(蒸散量)은 약 30.8ton/ha/day이었다. 11. 1ha의 월별(月別) 증산량(蒸散量)은 8월이 1,194ton/ha/month로 가장 많았고, 5월이 386ton/ha/month로 가장 낮았다. 또 1ha의 연간(年間) 증산량(蒸散量)은 3,983ton/ha/yr이었다.

• 한국컴퓨터정보학회논문지
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• 제27권11호
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• pp.181-190
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• 2022

이 논문에서 우리는 기존의 영상식 또는 루프식 좌회전 감응 시스템과는 달리 라이다(LiDAR)센서 및 영상 카메라를 이용하여, 좌회전 대기 차량을 2중으로 검지하고 좌회전 차선의 대기 길이에 대응하는 좌회전 교통신호체계를 효율적으로 부여할 수 있는 시스템을 소개하였다. LiDAR 센서에 의해 송수신된 LiDAR 신호에 대해서는 실시간으로 좌회전 대기 차량을 검지하고, 영상 카메라에 의한 영상에 대해서는 실시간 또는 일정한 주기별로 분석하도록 구성함으로써 불필요한 연산 처리를 절감시켜 실시간 감응 처리가 가능하도록 하였다. 실제 신호처리기를 이용한 교차로 시뮬레이션으로 1주일 동안 매일 5시간 성능 테스트를 해 본 결과 기존 방식에 비해 3%~5% 향상된 99.9%의 검지율을 기록하였다. 장점으로는 LiDAR 센서로 99.9% 좌회전 대기 차량이 검지되었으며 의도적인 검지 누락을 발생시키더라도, 영상에 의한 자체 보정을 통해 즉각적인 대응이 가능하여 좌회전 대기 차량의 과도한 대기시간을 조절시켜 교차로 내 모든 차선의 교통흐름을 원활하게 유도할 수 있었다. 또한 좌회전 차량이 뜸한 외곽의 교차로에 적용 시 불필요한 신호 비용을 줄이는 등 서비스 신뢰도 및 효율성을 높일 수 있다.

• 수산해양기술연구
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• 제47권4호
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• pp.411-418
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• 2011

As a fish way is a structure for fish migrating well toward upper stream due to breaking river flow by a dam or dammed pool, the specific fish's swimming ability is one of the main factors in making a plan and managing it. In addition, it also needs to understand the current field in fish road to evaluate its performance. This study is aimed to analyze the swimming patterns with current velocity changes using a Particle Imaging Velocimetry (PIV) in order to understand the swimming ability of silver fish (Plecoglossus altivelis) that is one of the fishes migrating through the fish way of Nakdong River, and to analyze the 2 dimensional current field near to silver fish at swimming momentum. The results showed that average values of tail beat frequencies for continuous swimming with current velocity were 2.8 Hz at 0.3 m/s, 3.2 Hz at 0.4 m/s, 3.8 Hz at 0.5 m/s, respectively. The wake would be produced by direction turning of fish's tail fin and its magnitude would be verified by the difference of pressure. The pressure turbulent flow produced by its tail beat would be made in both sides, and then, the magnitude of wake should be the source of moving direction. The swimming momentum will help to support the primary factor in making a suitable design for specific fish species migrating toward the district river.