• KSCE Journal of Civil and Environmental Engineering Research
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• v.7 no.3
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• pp.111-119
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• 1987

Scale effects of stability, run-up, run-down and reflection of layered coastal structures are investigated through the experiments with 7 kinds of hydraulic scale models. The occurrence mechanism and the control method of scale effects are also discussed. As a result, it is found that the similarity of permeability of inner layers plays an important role in the occurrence of scale effects, which has been neglected in the most of conventional model tests. To assure the best scale effects for permeable coastal structures, control of Reynolds numbers of the porous media flow in each layer is recommended. It is also found that Reynolds numbers in revetment, filter, and core layer must be greater than $2{\times}10^4$, $3{\times}10^3$, and $1{\times}10^3$, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.6
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• pp.39-44
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• 2016

Recently, there has been increasing concern regarding the collapse of hydraulic structures due to abnormal climate conditions. Therefore, numerous studies of the collapse of hydraulic structures have been carried out. In particular, the velocity of the propagation of a flood wave-front is important for predicting the inundation safety and establishing an EAP (Emergency Action Plan). Although many hydraulic tests have been conducted for precise predictions of a flood wave-front, the scale effect from downsizing has not considered. In this study, the relationships between surface tension and the concentration of surfactant, between surface tension and the velocity of flood wave propagation, and between surface tension and the Weber Number were derived through hydraulic tests using a surfactant and image analysis equipment. Based on these relations, the modification factor for the scale effect of the front of flood wave propagation was suggested. The results highlight the necessity of a modification factor when the Weber Number is lower than 12.2, but the scale effect can be ignored when the Weber Number over 12.2.

• Proceedings of the Korean Information Science Society Conference
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• 1999.10a
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• pp.198-200
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• 1999

공간 데이터베이스 구축을 효과적으로 하는 방법중의 하나는 대축척 공간 데이터베이스를 이용하여 여러 종류의 다중축척 데이터베이스를 구축하는 것이다. 다중축척 데이터베이스의 구축에는 많은 작업들이 포함된다. 기하학적 변형이나 불필요한 객체의 단순화, 삭제 등의 일반화와 데이터 모델의 변형, 그리고 데이터베이스의 전환 과정에 포함된다. 이 작업은 매우 다양한 처리과정을 요구하기 때문에 자동화된 도구의 도움을 필요로 한다. 본 논문에서는 다중축척 데이터베이스 구축에 이용되는 작업을 지원하는 CASE 도구를 소개한다. 이 도구는 지도 일반화에 의해 발생되는 데이터 모델의 변화에 대한 규칙에 따라 새로운 소축척의 데이터베이스의 데이터 모델을 설계하는 작업을 지원하며, 이 데이터 모델에 따라 대축척의 데이터베이스를 소축척의 데이터베이스로 전환하는 기능을 지원한다.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.5 no.4
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• pp.271-278
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• 1993

Sand ripple. the smallest bottom configuration, is one of the most important factors in the mechanism of sand transport. This paper deals with characteristics of ripple geometry generated by regular and irregular waves. Especially. rearrangement of ripple spacing caused by increasing or decreasing waves is investigated through movable bed experiments. Nondimensional length of rearranged ripples becomes very close to that of measured ripples in the field Furthermore, stochastic characteristics and occurrence limits of three dimensional ripples are investigated through the wave number spectrum calculated from the measured bottom topography.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.4
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• pp.538-549
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• 2021

In this study, a trim tab on the stern hull of a small high-speed vessel of approximately 10 m length sailing at a Froude number of 1.0 was designed for energy efficiency. The running attitude and resistance performance of the bare hull and trim tab hull at several angles to the base line were analyzed for model and full scale ships using computational fluid dynamics, and compared to investigate the scale effect. The analysis results for the bare hull were quite similar, but a difference in the attitude control under same conditions of the trim tab was observed, resulting in the total resistance error. However, there was no significant difference in tendency of the variation in the resistance with the attitude. Thus, the optimum running attitude could be determined from the tendency despite the scale effect, but a full scale analysis is required to analyze the control of the attitude by the trim tab and flow characteristics near the full scale ship.

• Journal of Korean Society for Geospatial Information Science
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• v.14 no.4 s.38
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• pp.37-44
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• 2006

To use surveying data obtained from different sensors and different techniques, it is a pre-requite step that register them in a common coordinate system. For this purpose, we developed methodologies to register airborne photos, ALS (Airborne Laser Scanning) data and digital maps. To achieve this, conjugate features from these data should be extracted in advance. In this study, linear features are chosen as conjugate features. Based on such a selection strategy, a simple and robust algorithm is proposed for extracting such features from ALS data. Then, to register them, observation equations are established from similarity measurements of the extracted features and the results was evaluated statistically. The results clearly demonstrate that the proposed algorithms are appropriate to register these data.

• Journal of Yeungnam Medical Science
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• v.10 no.2
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• pp.287-297
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• 1993

생활수준의 향상과 식생활의 개선으로 복부지방의 과다축척은 여성에게 체형의 불균형을 초래하고, 심하면 요척추관절에 퇴행성병변이 유발되어 요통과 운동장애가 올 수 있다. 이러한 복부지방의 과다축척을 성형외과적 복벽 성형수술 방법으로는 지방흡인술(liposuction)과 피부지방절제술(dermolipectomy)의 2가지 방법이 있는데 적당한 환자의 선택, 적당한 수술방법의 선택 혹은 두가지 방법을 적당히 병용함으로 복부지방제거와 더불어 체형의 개선에 좋은 효과를 얻을 수 있다.

• Proceedings of the Korean Information Science Society Conference
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• 2001.10a
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• pp.94-96
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• 2001

기존의 대축척 지리정보 데이터베이스로 부터 새로운 소축적 지리정보 데이터베이스를 유도하는 방법 중의 하나는 일반화이다. 이는 대축적 공간데이터를 소축척에 적합하도록 변형시킨다. 즉, 일반화를 통해서 지리정보 데이터의 공간 및 비공간적 특성이 변형되고 그 결과 데이터 모델로 변하게 된다. 본 연구는 이러한 변형에 따른 파급효과를 제어할 수 있는 규칙들을 제시한다. 특히 여섯 가지 일반화 연산자들이 모델에 미치는 영향을 조사하여, 이를 바탕으로 모델 변형을 제어할 수 있는 규칙을 제시하였다.

• Journal of the Society of Naval Architects of Korea
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• v.48 no.3
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• pp.222-232
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• 2011

This article examines the scale effect of the flow characteristics, resistance and propulsion performance on a 317k VLCC. The turbulent flows around a ship in both towing and self-propulsion conditions are analyzed by solving the Reynolds-averaged Navier-Stokes equation together with the application of Reynolds stress turbulence model. The computations are carried out in both model- and full-scale. A double-body model is applied for the treatment of free surface. An asymmetric body-force propeller is used. The speed performances including resistance and propulsion factors are obtained from two kinds of methods. One is to analyze the computational results in model scale through the revised ITTC' 78 method. The other is directly to analyze the computational results in full scale. Based on the computational predictions, scale effects of the resistance and the self-propulsion factors including form factor, thrust deduction fraction, effective wake fraction and various efficiencies are investigated. Scale effects of the streamline pattern, hull pressure and local flow characteristics including x-constant sections, propeller and center plane, and transom region are also investigated. This study presents a useful tool to hull-form and propeller designers, and towing-tank experimenters to take the scale effect into consideration.

• The Journal of the Acoustical Society of Korea
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• v.15 no.6
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• pp.66-72
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• 1996

In order to the sound effects and acoustics estimation of PANSORI hall, we are researched into the impulse response measuring and convolution integral of dry music(PANSORI) by using 1/10 scale model. Results are as follwo. First, impulse responses are measured by spark sound of electrodes and it is absolutely necessary many times of synchronous calculating for the obtain to enough S/N ratio. Second, a simulation technique of scale model is confirmed one of an effectual method of indoor acoustics estimation. Further, using the these new techniques and hearing test, its are recognized that reverberation time of PANSORI hall is about $1.0{\sim}$12.$ second suitable.