• Journal of Navigation and Port Research
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• v.37 no.2
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• pp.155-163
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• 2013

This study explores the structural behavior of module joints in floating concrete structures subjected to shear. Crack patterns, shear behavior and shear capacity of shear keys in joints of concrete module were investigated. Test parameters included shear key shape, or inclination of shear keys, confining stress levels and compressive strength of concrete. Test results showed that shear strength of joints increased as shear key inclination increased. Test results also showed that shear strength of concrete module joints increased with the increase of confining stress levels. The equation for predicting shear strength of joints was suggested, which was based on the test results. Shear strength prediction by using the equation suggested in this study showed good agreement with test results.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.881-882
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• 2006

선형전동기(linear motor)는 일반 회전형 모터에 비해 직선 구동력을 직접 발생시키는 특유의 장점이 있으므로 직선 구동력이 필요한 시스템에서 회전형에 비해 절대적으로 우세하다. 선형전동기의 성능인 추력을 스테이터, 코어, 영구자석 등의 구성요소의 형상과 치수, 코어와 영구자석의 극간격, 공극, 코일의 권수에 따라서 결정된다. 본 논문에서 제안한 2kW급 단상 구동형 횡자속 선형전동기는 압축기 제작에 필요한 직경 50mm, 구동 스트로크 18mm로 설계하였다. 또한 pole pitch가 20mm로 설계하였으며 요구되는 평균추력은 940N이다. 제작된 압축기의 특징은 고정자와 이동자가 맞닿는 flux path를 넓히기 위해서 최대한 경사진 각도의 형상으로 제작하였으며 경사의 각도가 커지면 커질수록 압축기로 구동하는 이동자와 고정된 부위사이에서 발생하는 흡인력이 상쇄되는 구조이기 때문에 진동의 원인으로 가장 크게 작용한다는 디텐트력이 작다는 것이 특징이며, 진동특성 등에 유리한 것으로 판단된다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1998.10a
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• pp.33-33
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• 1998

2차 유동 분사에 의한 추력 방향 제어 방법은 기존의 기계적인 장치를 이용한 방향제어 방법에 비해 부가적인 복잡한 기계적 작동장치와 이에 따른 무게의 증가를 배제할 수 있다. 본 연구에서는 전산 유동해석을 이용하여 2차원 초음속 수축-행창 노즐 유동에 2차 유동을 분사하여, 2차 유동의 분사우치 및 분사 유량 및 분사 각도 등이 추력의 방향 및 크기에 미치는 영향을 밝혀 이들 상호간의 상관관계를 구하여 추력 방향 제어를 위한 최적의 2차 분사 조건을 제시하였다. 유동 해석 견과 2차 유동의 분사 위치는 생성된 경사 충격파가 노즐 출구까지 분포되는 지점이 최대 전향각과 횡추력을 가지는 분사 위치임을 알 수 있었다

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1995.10a
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• pp.172-178
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• 1995

보강평판은 평판에 각종 보강재를 용접등의 방법에 의해서 종방향, 횡방향, 경사 또는 임의의 방향으로 부착시켜 굽힘 및 비틀림 강성을 향상시킨 구조요소이다. 이러한 구조요소는 구조적 필요성이나 경량화 설계에 따라 선박의 deck, 철도 차량, 항공기 및 자동차 등의 각종 구조물에서 부하능력 및 경제성을 증대시키기 위하여 널리 사용되고 있고, 또한 자동차용 오일팬, 가전기기의 케이싱과 모터의 케이싱등에도 사용되고 있다. 최근 현장에서는 이러한 구조물의 진동 감소 및 방진 문제가 큰 관심사가 되고 있다. 본 논문은 정사각형 알루미늄 평판에 +자 형태의 Box Beam 보강재를 편면 보강하고 4변 자유단의 경계 조건을 설정하였다. 보강재는 유한요소 정식화 과정을 통하여 평판 요소에 등가시키고, 2차원의 평판 구조로 보강 평판을 모델링하고 구조해석 프로그램인 ANSYS를 이용하여 해석하였다. 실험은 Impact Test에 의해서 주파수 응답 함수(FRF)를 각 시편에 대해서 구하고 이를 해석의 고유진동수와 비교하였다. 그리고 보강재가 임의의 각도로 평판에 부착되었을 때 고유진동수의 변화와 진동 모드(mode shape)를 분석하였다.

• Journal of the Korean Geotechnical Society
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• v.39 no.12
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• pp.47-60
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• 2023

At present, in South Korea, there is a growing concern regarding solar power facilities installed on slopes because they are prone to damage caused by natural disasters, such as heavy rainfall and typhoons. Each year, these solar power facilities experience soil erosion due to heavy rainfall and foundation damage or detachment caused by strong wind loads. Despite these challenges, the interaction between the ground and structures is not adequately considered. Current analyses primarily focus on the structural stability under external loads; the overall facility site's stability-excluding the solar structures-in relation to its surrounding slopes is neglected. Therefore, in this study, we use finite-difference method analysis to simulate the behavior of the foundation and piles to assess changes in lateral displacement and bending stress in piles, as well as the safety factor of sloped terrains, in response to various influencing factors, such as pile diameter, spacing between piles, pile-embedding depth, wind loads, and dry and wet conditions. The analysis results indicate that pile spacing and wind loads significantly influence lateral displacement and bending stress in piles, whereas pile-embedding depth strongly influences the safety factor of sloped terrains. Moreover, we found that under certain conditions, the design criteria in domestic standards may not be met.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.1
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• pp.85-92
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• 2015

It is well known that axial tension decreases the shear strength of RC & PSC beams without transverse reinforcement, and axial compression increases the shear resistance. What is perhaps not very well understood is how much the shear resistance capacity is influenced by axial load. RC beams without shear reinforcement subjected to large axial compression and shear may fail in a very brittle manner at the instance of first diagonal cracking. As a result, a conservative approach should be used for such members. According to the ACI Code, the shear strength in web is calculated by effect of axial force and the vertical force in the stirrups calculated by $45^{\circ}$ truss model. This study was performed to examine the effect of axial force in reinforced concrete beams by nonlinear FEM program (ATENA-2D).

• Journal of the Society of Naval Architects of Korea
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• v.44 no.3 s.153
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• pp.248-257
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• 2007

Turbulent flows around a sailing yacht hull were calculated using CFD technique. Grid system was generated by using Gridgen package and Fluent package was used to calculate flows around a 30ft-class yacht hull designed by MOERI. The drafts at starboard and port sides of a yacht. when the hull was heeled, were determined by adjusting the same displacement in the generated grid system. Pressure distribution on the sailing yacht hull was obtained and the changes of drag and side force by heel and leeway variation were shown. The flow calculations have been carried out both with and without free surface, and keel and rudder were included for both cases. It was found that the calculated results with free surface gives better agreement with experiments than those without free surface, although there are still a room for the improvement in correct prediction of forces.

• Journal of the Korean Society of Propulsion Engineers
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• v.4 no.1
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• pp.13-21
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• 2000

The advantages of the SITVC (Secondary Injection for Thrust Vector Control) technique over mechanical thrust vectoring systems include a reduction in both the nozzle weight and complexity due to the elimination of the mechanical actuators that are used in conventional vectoring. The optimal operating conditions of SITVC were investigated using in-house developed compressible flow analysis codes. Numerical experiments were used to examine the impact of the thrust vector direction with a variety of injection positions, mass flow rates, and injection angles on the two-dimensional expansion cone of a supersonic nozzle. The computational results showed that the optimal position of the secondary injection, with the maximum deviation angle and side thrust, was where the oblique shock generated by the secondary injection reached the end of the nozzle exit.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2022.11a
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• pp.155-155
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• 2022

유조선 우이산호 부두시설 접촉사고는 광양항 원유 2부두에 접근 중 과도한 속력 등 도선사의 부적절한 도선으로 좌회두를 적절하게 통제하지 못해 발생한 사고이다. 광양항 원유 2부두에 접안하고자 하는 VLCC는 부두 법선을 감안하여 약 10도 이내의 경사각으로 서서히 속력을 감속하면서 부두 전면 해상으로 접근하여 부두로부터 선폭의 약 2~3배 거리에 정선시킨 다음 예선의 도움을 받아 접안 예정 선박을 횡방향으로 5~10 cm/s 속도로 평행 이동시켜 부두에 계류시키는 것이 통상적인 접안 방법이다. 하지만, 우이산호의 부두 접근 시 속력을 살펴보면, 부두 1마일 전에서 8.4노트, 부두 0.5마일 전에서 7.1노트, 그리고 부두 0.2마일 전에서 5.2노트로 정상적인 타 선박의 속력보다 2~3배 빠른 속력으로 부두에 접근하면서 예선을 사용하였음에도 속력제어에 실패하여 부두와 접촉한 사고이다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.4
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• pp.1523-1531
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• 2011

Multi-axle driving vehicle are favored for military use in off road operations because of their high mobility on extreme terrains and obstacles. Especially, Military Vehicle needs an ability to driving on hills of 60% angle slope. This paper presents the improvement of the ability of hill climbing for 6WD/6WS vehicle through the optimal tire force distribution method. From the driver's commands, the desired longitudinal force, the desired lateral force, and the desired yaw moment were obtained for the hill climbing of vehicle using optimal tire force distribution method. These three values were distributed to each wheel as the torque based on optimal tire force distribution method using friction circle and cost function. To verify the performance of the proposed algorithm, the simulation is executed using TruckSim software. Two vehicles, the one the proposed algorithm is implemented and the another the tire's forces are equivalently distributed, are compared. At the hill slop, the ability to driving on hills is improved by using the optimum tire force distribution method.