• Journal of Advanced Marine Engineering and Technology
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• 제39권4호
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• pp.489-494
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• 2015

본 연구의 목적은 선박의 충돌에 의해 발생하는 원형단면을 갖는 실린더형 해양구조물의 충격손상을 최소화 시키기 위한 것이다. 기존의 설계기준, 코드 및 선급규정 등에 명시된 충격해석은 해수유체영역이 고려되지 않은 상태로 계산을 수행해 왔다. 본 연구에서는 해수유체영역을 고려한 모델링방법과 동적응답, 변형률, 내부에너지 등의 응답파라미터를 고찰하여 기존에 고려하지 않은 결과와 비교분석하였다. 충돌선박의 선속을 변화시켜 다양한 상태의 하중케이스를 고려하였고 가장 큰 충격하중상태인 2.0m/s에서의 선속에서의 응답결과를 비교분석하였다. ALE방법을 이용하여 해수유체영역을 고려한 경우 해수영역에서의 충격에너지 흡수와 유체감쇠를 통해 응답크기가 더 작고 구조물의 응력과 소성영역의 분포가 고르게 나타났다. 해수유체영역을 고려하지 않은 경우 보다 보수적인 설계가 될 수 있음을 알 수 있었다.

• 해양환경안전학회지
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• 제25권7호
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• pp.961-967
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• 2019

본 연구에서는 큰 침하량과 동적트림을 가지는 선박에 대하여 전산유체역학(CFD)을 기반으로 하여 효율적인 저항성능 추정 방법을 제시하였다. 본 방법에서 효율적이라 함은 점성 유동해석 이전에 비 점성 유동해석의 침하량과 동적트림 결과를 이용하여 선박의 큰 자세를 설정하고 DFBI(Dynamic Fluid Body Interaction) 방법에 의한 점성 유동해석을 수행한 것이다. 본 방법을 방법I로 명하였다. 방법I는 해석 전에 큰 자세를 설정함으로 인해 중첩격자(Overset Mesh) 기법을 사용하지 않는 단순한 격자시스템(Fig. 3 참고)을 사용하면 된다. 이로 인해 방법I는 계산시간 단축 및 계산의 정도를 높일 수 있는 장점이 있다. 점성 유동해석은 상용 CFD 코드인 STAR-CCM+를 사용하였다. 방법I의 첫 번째 점성 유동해석 결과는 최종 수렴된 결과와 비교하였을 때 저항 값에서 최대 1 % 내에서 차이를 보임을 확인 하였다. 중첩격자가 아닌 단순 격자시스템에 의한 STAR-CCM+에서 제공하는 DFBI 기법을 활용하여 계산단계 별로 변화된 자세에 대하여 매번 격자를 변경하여 수렴된 결과를 도출하였다. 본 방법을 방법II로 명하였다. 방법II의 저항 값과 비교하였을 때 방법I은 선속에 따라 0.03 % ~ 0.6 %의 차이를 보였다. 방법I의 결과는 수조모형시험과의 비교를 통해서 정성적 그리고 정량적으로 타당함을 확인하였다.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2004년도 학술대회지
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• pp.79-84
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• 2004

Initial hull form of 10 G/T and 40 knots class coastal patrol boat is newly developed. The resistance performances are experimentally and numerically investigated by model test at high speed circulating water channel(CWC) and CFD technique. The effect of a fin attached at hull side and initial trim are studied together. Wave patterns are observed to make clear the relation between the resistance performance and the wave characteristics. it can be found that the initial trim plays a role to increase the resistance performance above a certain velocity.

• 한국해양공학회지
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• 제31권3호
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• pp.219-226
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• 2017

In this study, the impact characteristics of subsea pipelines that were installed in various soil types and burial depths were evaluated by a numerical method. An impact scenario replicated a dropped ship anchor that fell vertically and impacted an installed subsea pipeline. In order to calculate the impact force through terminal velocity, FLUENT, a computational fluid dynamic program and MDM (Moving Deforming Mesh) technique were applied. Next, a dynamic finite element program, ANSYS Explicit Dynamics, was used for impact analysis between the anchor and pipeline (or, subsea if they were buried). Three soil types were considered: loose sand, dense sand and soft clay by applying the Mohr-coulomb model to the seabed. The buried depth was assumed to be 0 m, 1 m and 2 m. In conclusion, a subsea pipeline was the most stable when buried in dense sand at a depth of 2 m to prevent impact damage.

• Ocean and Polar Research
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• 제28권4호
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• pp.467-473
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• 2006

The EM 120, a newly installed multibeam echo sounder on RM Onnuri, has several advantages over the previously installed SeaBeam 2000 in performance and thus data quality. The EM 120 system provides a bottom topographic map with high resolution by (1) increasing the number of beams, (2) increasing the across track swath range, (3) measuring the more accurate sound velocity within the water column, and (4) improving stabilization for pitching, rolling, and yawing of the ship. This study compares EM 120 and SeaBeam 2000 echo sounders in terms of the data quality from the same survey area in the Clarion-Clipperton Zone, NE Pacific. Our result shows that the EM 120 provides more precise topographic data than the SeaBeam 2000. Although overall trends of data, such as topographic direction and relief, are similar for both echo sounders, the water depths measured by the EM 120 are shallower than that of SeaBeam 2000 by 80 to 90 meters.

• 한국생산제조학회지
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• 제25권1호
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• pp.42-47
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• 2016

This paper presents the development of a floating outboard type of compact water jet propulsion system. The planning case of the water jet system is developed by performing precision processing after manufacturing FRP (Fiber Reinforced Plastics) from plug mold casting. This system is composed of an intake, impeller, diffuser, reverse bucket, and main shaft. In addition, a rebuilt engine was applied through marine engineering. The water jet propulsion system performance was verified to discharge a maximum $0.29m^3/s$ of flow rate and 37 m/s of flow velocity in a test pool on land. A field test was performed by installing the water jet propulsion device on board a ship that was tested off the coast of Korea. The weight of the hull, engine, and other equipment was approximately 1.2 tons, and the sailing speed was a maximum 22 knots at 3,600 rpm.

• 대한조선학회논문집
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• 제43권4호
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• pp.504-511
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• 2006

In this paper a modern sailing boat for our costal area was developed by using the traditional boat hull form. Main particulars of design ship were determined by using the statistical values. Hull form was varied from the traditional boat hull form which was selected by the previous study and modified to fit Lateen sail. The appendage, rudder and keel were designed for good performance of against wind sailing. The performance of hull form was examined and the results were shown.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1351-1354
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• 2005

Recently, as the feasibility study shows that trans-Korea railway and trans-continental railway are advantageous, interest in high speed railway system is increasing. Because railway vehicle is environment-friendly and safe compared with airplane and ship, its market-sharing increases gradually. Korean High Speed Train has been developed by KRRI for last 7 years to satisfy the need. Korean High Speed Train (350km/h), composed of 2 power cars, 2 motorized car and 3 trailer cars, has been developed and is under trial test. To verify the design requirements for the functions and traction performances of the train, KRRI (Korea Railroad Research Institute) decided to evaluate traction performances of the train during trial test. For this purpose, torque, velocity, voltage and current must be measured. KRRI has developed a measurement system that can measure vast and various signals effectively. In this paper, we introduce traction performances of Korean High Speed Train. The traction measurement items are focused on the verification of motor block performances. Motor block consists of 2 motors. By this test, we verified traction performances of Korean High Speed Train

• 한국해양공학회지
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• 제22권4호
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• pp.84-89
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• 2008

It is hard to find experimental data for a model test of small high-speed planning boats. It is difficult to verify the performance seen in a model test for a high-speed boat because the ship-model scale-ratio is very small and the flow velocity of the circulating water channel and the X-carriage speed of the towing tank are restricted. Therefore most hull-form designs for high-speed small boats depend on the sea-trial test result for similar boats or evaluation through numerical calculations. This study investigated the anti-rolling effect of the stern sub-body in a 50-knot doss planning boat. To carry out this work, new model test procedures were set up in the actual sea. Using this method, the anti-rolling effect of the stern sub-body was investigated. A stern sub-body attached to a planning boat was proved to be effective in reducing the roll and pitch angle.

• 한국생산제조학회지
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• 제24권4호
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• pp.394-399
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• 2015

Because flow uniformity affects the life cycle and performance of the catalyst, it is an important design factor for selective catalytic reduction (SCR) systems. We examined how the diffuser angle and the area ratio of the inlet of the SCR reactor to the front of the catalyst affect flow uniformity. For the numerical analysis, we used STAR-CCM+, a common CFD software program. Analysis results showed that the larger the area ratio was, the less the flow uniformity was, and that the longer the diffuser length was, the greater the flow uniformity was. When the area ratio was greater than 1:5, the flow uniformity appeared very similar at the front of the catalyst. As a result, the spread time of the exhaust gas increased and the flow velocity decreased.