• Title/Summary/Keyword: 높이 축소형

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Studies on the Performance Evaluation of Downsized High-efficiency Cooling Module (높이 축소형 고효율 냉각모듈의 성능 평가에 관한 연구)

  • Jung, Jung-Hun;Shin, Yoon-Hyuk;Park, Sung-Wook;Jeong, Sun-An;Kim, Sung-Chul
    • Transactions of the Korean Society of Automotive Engineers
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    • v.19 no.6
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    • pp.61-67
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    • 2011
  • The cooling module needs enough space (or distance) from hood to absorb the energy from any pedestrian collision. Downsized cooling module for pedestrian protection is important to reduce the severity of pedestrian injury. When a vehicle collision happens, the downsized cooling module is required to reduce the risk of injury to the upper legs of adults and the heads of children. In this study, the performance of cooling module to cool the engine was investigated under 25% height reduction. The heat dissipation and pressure drop characteristics have been experimentally studied with the variation of coolant flow rate, air inlet velocity and A/C operation ON/OFF for the downsized cooling module. The results indicated that the cooling performance was about 94% level compared to that of the conventional cooling module. Therefore, we checked that the cooling module had good performance, and expected that the cooling module could meet the same cooling performance as conventional cooling module through optimization of components efficiency.

Experimental Analysis of Towing Attitude for I-type and Y-type Tail Fin of Active Towed SONAR (I 형 및 Y 형 꼬리 날개 능동 예인 음탐기의 예인 자세에 대한 실험적 분석)

  • Lee, Dong-Sup
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.8
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    • pp.579-585
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    • 2019
  • Increasing the detection probability of underwater targets necessitates securing the towing stability of the active towed SONAR. In this paper, to confirm the effects of tail wing fin on towing attitude and towing stability, two scale model experiments and one sea trials were conducted and the results were analyzed. The scale model tests measured the towing behavior of each of the tail fin shapes according to towing speed in a towing tank. The shape of the tail fin used in the scale model test was tested with an I-type tail fine and four Y-type tail fins, totaling five tail fins of the two kinds. The first scale model test confirmed that the Y-type tail fin was superior to the I-type tail fin in towing attitude and towing stability. The second scale model test confirmed the characteristics of the vertical tail fin height increase and the lower horizontal tail fin inclination angle application shape based on the Y-type tail fin. The shape of the application of the lower horizontal tail fin inclination angle showed the best performance. In order to verify the results of the scale model test, a full size model was constructed, sea trials were performed, and the towing attitude was measured. The results were similar to those of the scale model test.

Studies on the Cooling Performance of Front End Module for Pedestrian Protection (보행자 보호용 프론트 엔드 모듈(FEM)의 냉각성능에 관한 연구)

  • Shin, Yoon-Hyuk;Kim, Sung-Chul
    • Transactions of the Korean Society of Automotive Engineers
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    • v.20 no.6
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    • pp.67-72
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    • 2012
  • Novel Front End Module(FEM) with improved pedestrian protection is very important to reduce the severity of pedestrian injury. The FEM needs to have enough space from hood to absorb the energy from any pedestrian collision. In this study, the cooling performance of the FEM to cool the engine was investigated under 25% height reduction. The results indicated that the cooling performance analysis was about 86% level compared to that of the conventional FEM. Also, good qualitative agreement between CFD predictions and experimental measurements was found. This FEM needs the cooling performance enhancement for changed air flow path at the frontal part of vehicle. Therefore, we showed an improved performance using air guide setup and shape modification under the high load condition.

An analyses of the noise reduction effect of vegetation noise barrier using scaled model experiments (모형실험을 통한 식생형 방음벽의 소음저감 효과 분석)

  • Haan, Chan-Hoon;Hong, Seong-Shin
    • The Journal of the Acoustical Society of Korea
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    • v.35 no.3
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    • pp.223-233
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    • 2016
  • Design of a vegetation type sound barrier was presented as a noise barrier on the boundary of neighborhood facilities including schools, and apartments. The suggested noise barrier is made of unit blocks that are to be formed by stacking over the wall structure containing the plant and soils in the blocks. The advantage of the vegetation noise barrier is to acquire not only sound absorptive effects of plants and soils, but also sound diffusive effect caused by the irregular surface of the barrier which could eventually mitigate the noise. First, the optimum size of the units to obtain the highest noise reduction was investigated using 1/10 scaled model experiment, and sound attenuation experiments were carried out using a 1/2 mock-up model which is 2 m high and 5 m long. Total 1,137 unit blocks were made of synthetic woods with the size of $10{\times}10{\times}9cm$. These unit blocks were installed on the both side of the 1/2 mock-up steel framed noise barrier. As a result, it was revealed that the block typed vegetation noise barrier has 7 dB higher insertion loss in comparison with the general plane noise barrier. Also, it was found that the appropriate size of unit blocks is $20{\times}20cm$ which has large effect of sound insertion loss.

Aerodynamic Performance Test and Evaluation by Using the Subscale HAWT Blade Model (축소모델 공력실험에 의한 수평축 풍력발전 시스템용 블레이드의 공력성능 평가에 관한 연구)

  • 공창덕;방조혁;김하봉;김종식
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 1998.10a
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    • pp.39-39
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    • 1998
  • 본 연구는 500KW급 수평축 풍력발전기용으로 개발된 회전날개의 시제품 제작에 앞서 축소모델에 대한, 이론적으로 예측된 공력성능과 신축에 의한 공력성능을 비교 검토함으로서, 설계결과를 검증하고, 필요한 경우 설계를 보완하여 개발위험도를 최소화하기 위해 수행되었다. 시험모델의 크기는 실제의 5%로서 직경이 2.1m이며 날개의 시위길이는 0.2r/R에서 0.101m, 날개끝에서 0.043m 이고, 날개단면형 상온 FX-S-03-182이다. 블레이드의 재질은 Glass/Epoxy 복합재료로 제작되었으며, 실제 풍황을 모사하기 위해 자연풍 상태에서 실험하였다. 실험장치의 구성은 15m 높이의 타워에 회전날개와 전자브레이크 및 각종 센서를 장착하였고, 날개가 회전하기 시작하면 제동장치에 의해 부하를 주면서 토크, 회전수, 풍속 등을 각각의 센서로부터 자료획득장치를 통해 자료처리를 할 수 있도록 하였다. 실험하는 동안 풍속은 4m/s-13m/s 정도로서 시동 풍속인 4m/s와 정격풍속인 12m/s를 포함하여 회전날개의 전체적인 특성을 파악하기 용이하였고, 이론적인 예측성능과 측정된 성능을 비교 검토한 결과 비슷한 결과를 얻어 공력설계 및 해석 방법을 검증하였다.

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2D CFD for determining optimal location of wind turbine on Korean mountain (한국형 산악지형에서의 풍력발전 최적지 선정을 위한 2차원 유동분석)

  • Kim, Dae-Hyeong;Kim, Pyo-Jin;Lee, Chang-Hun;Choe, Jeong-Il
    • Proceeding of EDISON Challenge
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    • 2012.04a
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    • pp.41-44
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    • 2012
  • 본 연구에서는 풍력발전에 충분한 가능성을 가진 산악 지형을 모델링하여 유동의 흐름을 분석하였다. 실제 지형(설악산, 점봉산)에 대한 1/500 축소모형을 Gaussian 함수로 표현하였다. EDISON_CFD을 사용하여 산악지형의 난류유동을 해석하였으며, 해석결과의 신뢰성 확인을 위해 격자분해능에 따른 속도분포를 비교하였다. 산악지형에 따른 유동현상을 속도분포 및 유선함수 등에 의해 분석하였다. 또한 풍력터빈 설치 높이 기준에 의거하여 지형변화에 따른 주 유동방향 속도분포를 살펴보았다. 지형효과에 따른 유동해석결과를 기반으로 풍력 발전 가능 영역이 논의되었다.

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A Study on the Drum Water Level Versus Incoming Water Quantities for Small Vertical Hydraulic Water Turbine Plant (종축소수력발전소의 인입수량과 드럼수위와의 관계에 관한 연구)

  • Che, Gyu-Shik;Jung, Ju-One
    • Journal of Advanced Navigation Technology
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    • v.18 no.3
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    • pp.254-260
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    • 2014
  • We studied water level rising of drum versus time in the small hydraulic vertical water turbine system in this paper. The water level rises continuously up to a certain point with the passage of time if the constant incoming water is supplied, while it stops rising and maintains equilibrium state without any more rising because it increases position energy and evatually makes outgoing velocity and outgoing water quantities of runner area. The water level of drum is determined independent of size, height, width, figure of drum or runner configuration. It comes out that the water level is dependent only on the incoming and outgoing water quantities, and the output power has similar behavior. Therefore, desirable water level and output power are not available unless incoming water quantities is abundant. We validate this phenomina through applyng our methodolgies to the real small hydraulic vertical water turbine system under constructing and testing in industrial facilities in Korea.

The Study on the Non-Point Pollutants Reduction Using Friendly Bank Protection Anaerobic/Aerobic Contact Filtration Zone (혐기/호기 접촉여과대를 이용한 자연형 하천호안공법의 비점오염 저감 특성 연구)

  • Chang, HyungJoon;Kim, SungDuk
    • Journal of Korean Society of Disaster and Security
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    • v.12 no.1
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    • pp.23-34
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    • 2019
  • It is an urgent issue to manage and reduce non-point pollution sources for improving the water quality of stream and lakes in rural areas. In this study, in order to reduce non-point pollution sources in rural area, Gabion mattresses was proposed to provide protection of riverbanks with anaerobic and aerobic area. The utilization of this was assessed by lab scale model test and pilot plant test. After filling the inside of the gabion mattresses with aggregate, the filtration zone under anaerobic and aerobic conditions was formed to treat the contaminants. In addition, vegetation was deposited on the surfae of the gabion to prevent the inflow of soil and to promote purification by the plant. COD and nitrogen content (T-N, $NH_4{^+}$, -N, $NO_3{^-}N$) were monitored in model and field tests. The lab scale model test showed removal efficiency of 17% of TCOD, 35% of SCOD, 14% of TN, 62% of $NH_4{^+}$, -N, and 33% of $NO_3{^-}$ N. Also, pilot plant test showed removal efficiency of 24% of TCOD, 29% of SCOD, 47% of TN, 50% of $NH_4{^+}-N$, 33% of $NO_3{^-}$, N and 29% of TP.

The Earth Pressure Distribution of Crib Wall (Crib Wall의 토압분포)

  • Oh, Sewook;Kwon, Youngcheul;Bae, Wooseok
    • Journal of the Korean GEO-environmental Society
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    • v.7 no.5
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    • pp.41-48
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    • 2006
  • Crib wall is one of the segmental grid retaining walls using headers and stretchers to establish the framework of the wall. In this method, grids formed by the intersection of headers and stretchers are generally filled with the gravel to maintain the weight of the wall. Therefore, the construction can be carried out with higher speed and much economically when compared with the concrete retaining wall. Furthermore, it has high drain capacity, and environmentally friendly aspects also have been pointed out because the possibility of the planting at the front of the wall. However, in the crib wall method, the relative movement between the individual headers and stretchers was generally recognized, and stress redistribution in the gravel filling was also observed when subjected to the external loading and self-weight of filling. Therefore, it has been thought that the distribution of the earth pressure in the crib wall system differ from that of the concrete retaining wall. In this study, the surcharge tests using the scaled model crib wall was carried out to observe the distribution of the earth pressure in the segmental grid retaining wall. The earth pressure was measured in the six specified height of wall, and the distribution of the pressure was analyzed. Furthermore, the earth pressure by computation or by the test using the concrete retaining wall was also considered to make comparison.

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Effects of Vertical Spacing and Length of Reinforcement on the Behaviors of Reinforced Subgrade with Rigid Wall (보강재 간격 및 길이가 강성벽 일체형 보강노반의 거동에 미치는 영향)

  • Kim, Dae-Sang;Park, Seong-Yong;Kim, Ki-Hwan
    • Journal of the Korean Geosynthetics Society
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    • v.11 no.4
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    • pp.27-35
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    • 2012
  • Facings of mechanically stabilized earth retaining walls have function to fix the reinforcement and prevent backfill loss, but the walls are lack of structural rigidity capable of resisting applied loads. The reinforced subgrade with rigid wall was developed to have the structural functions under train loading. Though it has lots of advantages such as small deformation after construction, its negative side effects of economics and difficult construction were mainly mentioned and not practically used. To apply it for railroad subgrade, this study focus on the construction cost down and the enhancement of constructability without functional loss. To do so, the behaviors of reinforced subgrade with rigid wall were evaluated with the change of the vertical spacing and length of reinforcement. Small scale model tests (1/10 scale) and 3 m full scale tests were performed to evaluate deformation characteristics of reinforced subgrade under simulated train loading. Even though it uses short reinforcement, it showed small horizontal displacement of wall and plastic settlement of subgrade. Also, it was verified that not only 30 cm but also 40 cm of vertical spacing of reinforcement had good performance in serviceability aspects.