• Journal of computational fluids engineering
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• v.15 no.4
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• pp.53-59
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• 2010

Preliminary design of a ground plate, a device installed close to the aircraft model for wind tunnel test to simulate the ground effect, was performed by a numerical simulation. A two-dimensional numerical study was performed initially to decide the optimal leading edge and flap configurations. Then, three-dimensional studies were conducted to decide the optimal flap deflection angle for pressure distribution reduction since the plate and the plate supporting system generate static pressure difference between the upper and lower flow regions. Three-dimensional simulation additionally studied the effect of the clearance between the plate and the wind tunnel side wall. For the efficiency of computation, half model was simulated and a symmetric boundary condition was applied on the center plane. Based on the preliminary design, a ground plate was designed, manufactured and tested at the Korea Aerospace Research Institute(KARI) wind tunnel. The measured pressure differences versus flap deflection angle agreed well with the predicted results.

• Journal of Energy Engineering
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• v.9 no.1
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• pp.60-67
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• 2000

본 연구는 열에너지 교환을 목적으로 이용되는 환상휜의 비등열전달에서 간섭판의 영향을 고찰한 실험적인 연구이다. 휜과 인접한 간섭판의 간격과, 휜 높이의 변화에 따라 비등열전달에 미치는 영향을 구했다. 휜 간격은 단독 환상휜에 간섭판을 0.05mm에서 2mm 가지 6가지 종류, 그리고 휜 높이는 3 mm , 8mm, 13 mm 의 3 종류로 변화시켰다. 실험결과 휜 높이가 제일 큰 13 mm 간섭판 간격이 0.25mm 로 비교적 좁은 간격임에도, 핵비등영역에서는 열전달 촉진효과가있었다. 그러나 간섭판의 간격이 0.05mm 로 더좁아지면 저열류속 영역에서는 휜 간격 내에 유체가 유입이 어려워 휜 선단만에서의 비등열전달과 일치한다. 이러한 경향은 휜 높이가 작아져도 비슷하다. 또한 휜과 간섭판의 간격이 0.25mm이상이면 간섭판의 영향이 적어, 확대 전열면으로서 전열 촉진효과를 얻을 수 있다.

• KLA journal
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• v.39 no.1 s.308
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• pp.54-74
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• 1998

이 글은 DDC에 대한 포괄적인 이해를 돕기 위한 것이다. 앞으로 DDC 제21판의 성격과 구조, 7개 보조표와 각 주류의 특성과 사용법에 관한 글을 지면이 허락하는대로 연재할 예정이다. DDC는 십진식 분류법의 원조로서 우리의 KDC에도 많은 영향을 미치고 있다는 점에서, DDC에 입문하는 사람들은 물론 KDC를 사용하는 독자들에게도 유익한 정보를 제공할 수 있을 것으로 생각한다. ■ 편집자주

• 공원문화
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• s.42
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• pp.42-42
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• 1989

본지41호(99.12.31.간)13p"제언"에서 편집자는 국립공원내의 명소.희귀식물에 대한 안내판의 내용은 학술적가치와 정확한 명칭을 기술할것을 주장하면서 지면과 시간관계로 많은 임학자의 소론을 열거하지 못했읍니다. "나무백과"의 저자이며(전본회 학술부회장) 서울대농대교수를 지난후 현재 원광대 농대임학과 교수이신 임경빈박사께서 늦게나마 이에대한 질의에 알뜰한 설명을 편지로 보내주셨기에 싣습니다.

• Journal of Ocean Engineering and Technology
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• v.12 no.2 s.28
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• pp.87-96
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• 1998

A numerical simulation was done to investigate the performance of thin wings in close vicinity to ground. The simulation is based on Vortex Lattice Method(VLM) and freely deforming wake elements are taken into account for a sudden acceleration case. The parameters covered in the simulation are angle of attack, aspect ratio, ground clearance, sweep angle and taper ratio. In addition, the effect of the wing endplate on the ground effect is included. The wing sections used for present computations are uncambered, cambered and S-types. The present computational results are compared with other published computational results and experimental data.

• Ecology and Resilient Infrastructure
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• v.3 no.2
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• pp.126-129
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• 2016

The risk of flooding and groundwater depletion is increasing due to the increase of impervious area in an urban area that reduces the volume of infiltration and increases the outflow of rainwater. The objective of this study is to examine the impact of installation of roadside tree protectors with infiltration pipes in terms of the change of the infiltration rate. Through this study, it has been attested that roadside tree protectors with infiltration pipes increased the infiltration rate and decreased water level on the ground, and could be applied in an urban area as the low impact development (LID) facilities.

• Journal of KSNVE
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• v.3 no.3
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• pp.192-198
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• 1993

옥외에서 발생하는 소음은 음원과 수음점 사이의 시선을 차단하는 장애물을 설치하는 방법이외에는 달리 방도가 없는 경우가 많다. 빛과 마찬가지로 소리도 시선이 차단되면 소리의 그늘이 지는데 빛의 경우보다는 상당히 강한 음장이 이 그늘에 존재한다. 그늘 영역에서의 음장은 소리의 회절현상에 기인하는 것으로서 회절음장은 곧 방음벽의 차음효과를 좌우한다. 방음벽의 차음효과는 잉여감쇠(excessive attenuation)로 표시되는데 잉여감쇠에 영향을 주는 인자는 방음벽의 기하학적 조건, 음향학적 성질, 설치지면, 주변지형, 풍속 및 온도분포와 같은 기상조건, 음원의 특성 등 다양하지만 가장 기본적인 인자는 기하학적인 조건이다. 본고는 방음벽의 원리에 국한하여 살펴보기 위해 기술된 것이므로 주로 판 또는 쐐기 형태의 물체에 의한 회절현상을 취급하였다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.11
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• pp.1157-1162
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• 2011

The parking brake is an essential unit embedded in the track-driving motor of an excavator. The parking brake plays an important role in keeping the excavator in place not only when it is parked, but also during the digging operation. In fact, the load placed on the parking brake during the digging operation is significantly higher than the parking load, because the impact and rating loads caused by the bucket digging force cycle frequently and have very high load ranges. Therefore, the load conditions during the digging operation should be taken into account in the parking brake certification test. In this study, a series of experiments was carried out in which various operating pressures were applied to the parking brake, where repeated loads were reciprocally placed on the brake by locking the multifriction disc and releasing the hydraulic cylinder. The characteristics of the parking brake were investigated by comparing the obtained experimental results and the theoretical design specifications.

• Journal of Korean Library and Information Science Society
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• v.36 no.1
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• pp.353-370
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• 2005

The purpose of this study aims to provide possible suggestions for the improvement of the korean Decimal Classification System in 21th century through the analysis of history field as the subject of study. As a result of this study, some problems(for example, irrational classification number system, very simplicity of $\lceil$Table of Geographic Areas. Historical Periods. Persons$\rfloor$. improper development of class 900, necessity of some internal tables and $\lceil$Table of Racial, Ethnic, National Groups$\rfloor$, insufficiency of note etc.) were found out. This study can be useful for the future revision of KDC4 because a revolutionary improvement were provided.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.17 no.4
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• pp.70-75
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• 2009

According to the aviation statistics, tail strike incidents and accidents are cyclic. Although many tail strikes occurred during takeoff, these are less than during landing cases. Many cases are related on human factors. In my opinion it is possible to analyze the causes of takeoff tail strikes to some extent. There are major casual factors of tail strike during takeoff such as; (1) Mis-trimmed horizontal stabilizer (2) premature rotation prior to $V_R$ (3) Excessive pitch up rate during rotation (4) Improper use of the flight director. Among these causes improper use of flight director is excluded in this paper because it is recommended that pilot should use flight director after airborne. So I analyzed the other three causes as following. Firstly, because mis-trimmed stabilizer is related to center of gravity(CG), the relationship between stabilizer and CG is reviewed. Secondly, concerned premature rotation prior to $V_R$ I reviewed the background of rotation speed($V_R$) establishment and analyzed theoretically what speed leads to tail strikes. Thirdly, concerning excessive pitch up rate during rotation I analyzed what excessive pitch up rate can decrease ground clearance while using FDR data.