• Journal of Advanced Navigation Technology
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• v.19 no.3
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• pp.230-236
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• 2015

In this paper, the electric potential of electrode surface is investigated by assuming them as two dimensional sets of point current sources. And, the simulated water tank is manufactured as a reduced scale of the earth. Henceforth, the adequate model electrode for test is decided to decrease experimental errors relevant to the limitation of the size of the water tank. The one of important things of this work, the deduction method of the potential interference factor is proposed, which used as the criterion of the potential interference according to the shape of conductors and the laying conditions, when multiple grounding conductors are situated at the same resistance grounding area. Also, the validity of this theory is verified from a numerical simulation of the grounding electrode to be used in experiments, and this study is realized by the verified theory and the simulated experiments.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.16 no.1
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• pp.111-118
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• 1998

Today Geo-Spatial Information System(GSIS) has developed and used more widely, and especially it has been more greatly asked for Land Information System as a part of GSIS. Now it has been planning and monitoring for remaking of cadastral maps by the Ministry of Government Administration and Home Affairs. But this is long term project because of the importance of itself. And then it has been needed to computerize cadastral maps for implementation of relative tasks and services. Cadastral maps have some problems; for example, map join in different scales, different administration boundary and so on. In this study General topology algorithm, Polygonization algorithm and Pseudo-topology algorithm was adapted in computerization of cadastral maps. This is called digital map. The area and shape of parcels do not change. As a result it was found that Polygonization algorithm is the best of 3 algorithm and General topology algorithm is the worst.

• Spatial Information Research
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• v.1 no.1
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• pp.17-28
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• 1993

In order to minimize vectorizing tasks, which require huge reso¬urces and time and to support the census mapping effectively, the geographic information databases structure has been studied. The steps of the new approach are as follows. : Step 1, Scanning the maps of the whole country and storing the image data in raster format. Step 2, Vectorizing the data of specific items for Census operation such as Enume¬ration District, and then linking to attribute data in the text format. Step 3, Designing the database with a Tile and Multi-layer structure to make a continuous map logically. Step 4, Implement Censlls Mapping System(CMS) for efficient mapping and retrieving. As a consequence of this study, the cost, manpower and time effectiveness was proved and it was confirmed to produce lIseful and high-qual ified maps for the Census. In the future, this system wi II be able to provide many organizations and individuals with the various data based on geographical statistical information.

• Journal of Korea Water Resources Association
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• v.35 no.2
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• pp.203-212
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• 2002

The purpose of this study was to examine the effect of vegetation on the flood plain in the Taewha river on the changes of flood level using a hydraulic physical model experiment. To simulate 9.0 km river, 1/300 horizontally and 1/72 vertically distorted model was used. The vegetation areas were divided by three sub -areas and the flood level changes were examined according to the locations of vegetation as well as the transverse Profile. As a result, the flood level changes were not significantly affected by the densely distributed vegetation. It was concluded that additional adjustable vegetation in urban river could make useful hydrophilic space.

• Journal of the Korean Society for Marine Environment & Energy
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• v.15 no.2
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• pp.142-149
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• 2012

This study deals with the investigation of the scale effect for the vertical-axis tidal stream turbine by evaluating the hydrodynamic efficiency of turbine rotors of different diameters at different flow conditions. Numerical analyses are made for the turbine rotors with a same shape, but different sizes obtained using the diameter evaluation equation suggested in this paper. It is shown that the performance of turbine is clearly dependent upon the rotor size and inflow velocity, i.e. Reynolds number dependency of different-scaled turbines showing better efficiency with increasing Reynolds number. The sudden decrease of efficiency is also noticed around the transition region of Reynolds number. The hydrodynamic capacity evaluation method needed at initial stage of turbine design is suggested and exercised with some test cases. It is recommended that the method is expected to be useful for turbines with demanding powers between 10 kW and 300 kW.

• Proceedings of the Korea Water Resources Association Conference
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• 1993.07a
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• pp.107-113
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• 1993

도시가 발달함에 따라 늘어나는 교통량과 주차공간 등의 부족을 해소하기 위해 하천에 교량을 증설하건 복개를 하는 경우가 많아지고 있다. 이와 같은 현상은 수리학적으로 바람직한 현상이 아니므로 과연 하천에 장애물을 설치할 경우 이들 장애물에 의하여 하천 흐름이 어떻게 영향을 받는지를 실험적으로 분석해 보았다. 모형은 중랑천과 한천로상의 교량 형태를 점검하고 이들을 7개의 형태로 분류 1/50의 축척을 사용하여 제작하였다. 실험장치는 국립 건설시험소에 있는 직선 개수로를 이용하였으며 실험을 위하여 하천의 경사는 1/500, 1/750과 1/1000을 그리고, 하천 유량은 200, 350, 500 CMS를 각각 선택하였다. 하천에 교량의 장애물 설치시 구조물 형태에 따라 6~30%의 수위 상승효과가 있었으며 표면 유속은 7~23%의 감속 효과가 있었다.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.328-333
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• 2011

최근 하천사업에는 자연친화적인 설계기법이 도입되고 있으며 호안공법도 과거 제방보호 기능만을 가진 단순한 호안에서 식생을 활용한 다양한 종류의 호안공법이 개발되어서 각종 하천공사에 도입되고 있다. 그러나 호안공법을 도입할 때 공법에 따른 선택기준이나 구체적인 설계기준이 현재 사용되고 있는 지침에 제시 되어있지 않은 실정이다. 이에 본 연구에서는 호안 재료의 적합성에 대한 객관적이고 정량적인 판단기준인 수리학적 특성인자를 파악해보고자 수리모형실험을 수행하였다. 실험은 길이 15m, 폭 0.8m, 높이 0.8m의 수로를 이용하였다. 사용한 호안재료는 흙, 실제모형의 1/50의 축척으로 제작한 호안블록모형과 실제 식생으로서 잔디를 이용하였다. 수로의 상류구간에 대리석을 이용하여 6m의 안정화구간을 만들었고, 실험은 동일한 수위에 유량을 변화시키면서 유속을 계측하였다. 계측 내용을 분석한 결과 식생과 무식생을 비교했을 때 하상에서 식생높이(약 9cm) 범위에서 식생이 최대 97% 유속저감효과를 나타났으며, 식생과 블록을 비교한 결과도 하상에서 식생높이(약 9cm) 범위에서 식생이 최대 97% 유속저감효과를 나타낸 것을 확인할 수 있었다. 이는 호안재료가 식생일 때 유속저감효과가 크게 나타남을 알 수 있었고 향후 다양한 식생형태에 대한 실험이 필요할 것으로 보이며, 본 연구가 호안공법에 도입되는 다양한 식생의 수리적인 특성인자를 규명하는데 도움이 될 것으로 판단된다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.10
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• pp.899-904
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• 2007

During the conceptual design phase of fighter class aircraft, the high speed wind tunnel test with 1/20 scale wing-body-tail model has been conducted to investigate the effects of leading edge flap deflection on the supersonic cruise performance of the aircraft. To select the proper leading edge flap deflection for the wind tunnel test, the aerodynamic characteristics due to various leading edge flap deflections have been analyzed by using corrected supersonic panel method. Based on the results obtained from the experimental and numerical approaches, the effects of leading edge flap deflection have shown to be useful to enhance the supersonic cruise performance of fighter class aircraft.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.7
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• pp.575-580
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• 2007

During the conceptual design phase of a canard type high maneuverable aircraft, the low speed small scale wind tunnel test was conducted to investigate the high angle-of-attack static stability of the aircraft. In this study, 1/50th scale generic canard-body-wing model was used for the small scale wind tunnel test. For the analysis of static stability including high angle-of-attack nonlinear characteristics, the vertical tail effects were studied due to canard deflections. In addition, the nose chine effects were studied at high angle-of-attack. Based on the results obtained from the experimental study, the configuration change effects for canard type aircraft on high angle-of-attack static stability have been able to analyze.

• Journal of the Korean Society for Marine Environment & Energy
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• v.14 no.4
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• pp.230-238
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• 2011

The experimental study for the performances of 100 kW marine current turbines (Horizontal Axis Turbine) has been conducted with three cases of 700 mm diameter model in PNU 100 m towing tank. Three cases of impeller have been designed according to the variation of section configuration and tip shape. The model tests have been carried out at different speed of revolution to find out the scale effect (Reynolds number effect). The designed rake impeller was the best among them in the efficiency point of view especially at high Tip Speed Ratio (TSR). The present study is expected to be extended to conduct at high reynolds number as well as the computational study for the validation.