• The Journal of Engineering Geology
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• v.27 no.4
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• pp.417-427
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• 2017

This study aims to present cases of rock slope failures caused by geological structures. Status of slope failures, results of cause analysis and stabilizing methods are introduced, focusing primarily on rock slope failures caused by specific geologic structures, such as intersection of faults infilled with clay, foliation and fault shear zone by dike intrusion and deep-seated clayey layer along lithologic boundary. Detailed geological survey, geophysical exploration and boring survey were conducted for cause analysis. Stabilizing method to prevent further slope failures and to ensure long-term stability of slopes were established, considering characteristics of geological structures, types of failure and geological conditions.

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.93-93
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• 2011

연육 연도교에 주로 건설되는 초장대교량은 시설물 특성상 이용객들의 대피공간이 제약받고 태풍, 해일 등 자연재해에 노출이 많기 때문에 다른 공공시설물보다 재난에 취약한 구조물이다. 최근 공공시설물의 건설동향이 구조물의 장대화로 되어감에 따라 재난 발생시 예상 위험이 점점 더 커져가고 있다. 본 연구는 이전 연구를 통해서 구축된 재난관리 시나리오를 토대로 재난관리 알고리즘을 개발하였다. 초장대교량의 재난은 자연재해와 인적재해로 구분할 수 있다. 여러 가지 재해 중 본 연구에서 제시한 재난관리 알고리즘은 자연재해의 경우 안개, 강설, 결빙, 강풍, 지진, 해일 및 풍수해이며 인적재해의 경우 화재, 교통사고, 구조물파괴 및 테러이다. 이 재난관리 알고리즘은 재난관리 전산 프로그램 구축의 기초로 사용될 것이다. 본 연구는 국내외 재난관리 관련 사례조사를 토대로 재난 수준별 평가방법을 수립하였다. 안개, 강설, 결빙, 강풍, 지진, 해일 및 풍수해와 같은 자연재난은 심각한 재난 발생전에 교통통제가 가능한 형태로 분류될 수 있으며 사례조사를 통해 교통통제 관리기준을 설정하였다. 화재, 교통사고, 구조물 파괴 및 테러와 같은 인적재난은 상황 발생시부터 비상대응을 취해야할 재난의 형태로 분류될 수 있으며 사고발생 시나리오를 통해 대응 단계별 평가방법을 설정하였다. 또한 재난 수준별 평가방법을 토대로 재난관리 알고리즘을 개발하였다. 자연재해와 같이 사고 발생 전에 교통통제가 가능한 재해는 교통통제 모듈로 구분하여 재난관리 알고리즘을 설정하였다. 인적재해와 같이 사고 발생 즉시 비상대응을 실시해야할 재해는 비상대응 모듈로 구분하여 재난관리 알고리즘을 설정하였다. 교통통제 모듈과 비상대응 모듈은 원칙적으로 국가재난관리등급에 따라 관심, 주의, 경계, 심각의 4단계로 구분하였다. 교통통제 모듈과 비상대응 모듈은 AAD에 의해 관리자, 외부기관 및 이용자 각각의 세부 행동지침 및 요령을 제시하였다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.6
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• pp.36-44
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• 2003

In this paper, an analytic solution method is proposed to overcome the numerical problems when the slewing dynamics of hybrid coordinate systems is investigated via time finite element analysis. It is shown that the dynamics of the hybrid coordinate systems is governed by the coupled dual differential equations for both slewing and structural modes. Structural modes are transformed into the time-based modal coordinates and analytic spatial propagation equations are derived for each space-dependent time mode. Slew angle history is obtained analytically by appropriate applications of the boundary conditions and structural propagation is re-calculated using the slew angle. Numerical examples are demonstrated to validate the proposed analytic method in comparison to the existing state transition matrix method.

• Journal of the Korean Society of Propulsion Engineers
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• v.11 no.4
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• pp.46-51
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• 2007

The irregular fuel surface was observed by the visualization of hybrid rocket combustion. Even though the test condition maintained oxidizer rich environment, the irregular dark fuel surface was formed as the result of incomplete combustion. In order to investigate the correlation of the characteristics of oxidizer flow and the irregular fuel surface, various flow conditions were imposed such as swirl flow, induced swirl flow by helical fuel configuration and straight flow. Test results revealed no correlation was found between oxidizer flow condition and irregular fuel surface. And this can be a commonly observed phenomena in the tests with different fuel/oxidizer combination. Thus, the irregular fuel surface can be a result of the interaction of blowing flow of vaporized fuel and the boundary layer of oxidizer flow. A further study will be required to confirm the assumption for the formation of irregular fuel surface.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.359-363
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• 2011

In this paper, the characteristic of pressures had been analyzed with a series of shapes that are pressure probes used in supersonic wind tunnel. When a performance of supersonic wind tunnel is evaluated, the Mach number is calculated by using the ratio of static pressure in test section wall to total pressure in settling chamber. Also the flow condition can be visualized by schlieren system. However a number of limitations exist to measure pressure of test section due to high speed and boundary layer effect. Therefore a specific pressure probe is needed for evaluating flow condition in test section at a various of positions. In the paper, experiments were conducted in terms of some pitot probes and the results were compared and analyzed.

• Proceedings of KOSOMES biannual meeting
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• 2005.11a
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• pp.159-163
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• 2005

This experimental study was performed to investigate internal flow and unsteady flow characteristics using a model for actual shape of a plate heat exchanger and visualization of flow through the particle image velocimetry. Seven Reynolds numbers were selected by calculation with the height of grooved channel and sectional mean velocity of inlet flow in the experiment, and instantaneous velocity distributions and flow characteristics were experimently investigated. The triangular grooved channel had a compound flow consisting of the flow in lower channel and the groove flow receiving shear stress by the channel flow in the experiment. The sheared mixing layer, in the boundary between the triangular groove and the channel, affected main flow to raise turbulent in the channel.

• Proceedings of KOSOMES biannual meeting
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• 2005.11a
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• pp.153-158
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• 2005

The turbulent shear flaw around a surface-mounted vertical wall was investigated using the two-frame PIV(CACTUS 3.1) system. From this study, it is revealed that at least 500 instantaneous velocity field data are required for ensemble average to get reliable turbulence statistics, but only 200 field data are sufficient for the time-averaged mean velocity information The flow has an unsteady recirculation region post vertical wall with bottom gap, followed by a slow relaxation to the fiat-plate boundary layer flow. The time-averaged reattachment length estimated from the streamline distribution is about x/H=3H. The large eddy structure in the separated shear layer seems to have signification influence on the development of the separated shear layer and the reattachment process.

• Journal of the Korean Society of Marine Environment & Safety
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• v.17 no.1
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• pp.29-37
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• 2011

PIV measurements of the velocity field, pressure field, vorticity, and turbulent intensity in the rear of curved section of an oil fence with current speed showed that the flow directions in the rear of flow boundary area were similar to those in the front of it. As the current speed increased, the patterns of pressure distribution were changed, and the turbulent flow became more irregular. CFD simulations under the same conditions as the PIV tests showed that the flow patterns of the wake were similar to those by PIV tests in speed of 0.3 m/s and less, but were distinctively deviated from those in 0.4 m/s due to the flexibility of the oil fence, which was not properly taken care of in CFD modeling.

• Journal of the Korean Society for Marine Environment & Energy
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• v.4 no.2
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• pp.35-42
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• 2001

We demonstrated the importance of initial estimates of model parameters and the utility of an optimization approach of the uncertain forcing of wind-driven circulation off the southeastern coastal waters of Korea. The wind stress represents the upper boundary condition in this model and enters in the model equation as a forcing term in the numerical formalism. The wind field contributes to maintain the almost time-independent distribution of the upper layer thickness feature in a north-south direction and negative wind stress curl to maintain the formation of warm eddy off the southeastern coastal waters of Korea. Elucidated is the variational characteristics of the East Korean Warm Current due to the variations of the zonally averaged wind stress (southward transport) from the seasonal variations of the meridional transport by the Ekman transport.

• The Journal of the Korea Contents Association
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• v.14 no.6
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• pp.428-441
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• 2014

The Han river flowing the southern boundary of Hangyang city wall was known for scenic remote villa spot. This research is about a study on the historical and cultural landscape value of Apgujung built on hills of the Han river by Han Myeong Hoe in the mid-15th century. The results are as follows. First, the Han river has been a cultural poetical place. Second, the pavilion of west river was built as thatched roof at 1454-1456, while that of east river was erected as grand villa at 1469-1473. Third, there are characteristics of periodical landscape and origin was included on historical and cultural landscape, therefore, Apgujuing-dong has been recognized with the story. Han river where Apgujung was built has beautiful water landscape in spite of the landscape of modem downtown. Fourth, there are placeness and Han river of main landscape text streams nearby Apgujung site. Historical and cultural landscape of Apgujung should be changed, but, the landscape value could be progressed with the application as cultural contents while the Han river flows. It could be cultivated on the application of various culture contents and story of Apgujung when the historical landscape of water system be restored in Han river.