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암반소켓된 소구경 현장타설말뚝의 정재하시험과 양방향재하시험 분석법 비교연구
송명준(Myungjun Song),송영훈(Younghun Song),정민형(Minhyung Jung),박영호(Youngho Park),박재현(Jaehyun Park),이주형(Juhyung Lee),정문경(Moonkyung Chung) 한국지반환경공학회 2013 한국지반환경공학회논문집 Vol.14 No.9
이 논문에서는 정재하시험과 양방향재하시험의 하중-침하거동을 비교하기 위하여 인접한 위치에서 직경 480mm인 암반에 소켓된 현장타설말뚝을 시공하고 각각 정재하시험과 양방향재하시험을 실시하였다. 양방향재하시험 해석법 중 기존의 탄성압축량을 고려하지 않은 등가하중곡선법은 정재하시험 결과와 비교할 경우 침하량을 과소평가하는 것으로 나타났기 때문에, 정확한 하중-침하 곡선 산정을 위해서는 반드시 탄성압축량을 고려해야 한다. 또한 기 제안된 여러 탄성압축량을 고려한 등가하중곡선법들을 정재하시험 결과와 비교검토한 결과, 충분한 적용성을 가지는 것으로 판단되었다. 또한 정재하시험과 양방향재하시험의 지지력을 비교한 결과, 양방향재하시험은 말뚝재료의 극한강도를 반영하지 못하고 지반의 극한지지력만을 평가하므로 반드시 재료강도에 대한 검토를 실시하여야 한다. In this study, each top-down load test and bi-directional load test has been performed on the 480mm diameter of two rock socketed drilled shafts, which are located next to each other, and the results have been compared. The result shows that the settlement from the equivalent load-settlement curve of bi-directional load test is smaller than one from top-down load test, because elastic is not considered in equivalent load-settlement curve of bi-directional load test. Therefore elastic shortening should be considered to obtain appropriate equivalent load-settlement curve. Three existing methods used to obtain equivalent load-settlement curve with consideration of elastic shortening has been compared with the result of top-down load test. The result shows that those existing methods are sufficiently applicable to the design. In addition, result of comparison between top-down load test and bi-directional load test shows that bi-directional load test was found to overestimate bearing capacity because it does not consider pile body failure.
김진규(Jinkyoo Kim),송명준(Myungjun Song),남진영(Jinyoung Nam),이재준(Jaejun Lee),임현우(Hyunwoo Lim) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Automobile seats playa crucial role of protecting passengers securing them from a car accident. And also those should provide comfort, back-and-forth movement, height adjustment, and many safety and functional parts like side airbag, seatbelt, heater, ventilation device and so on. FEA is one of powerful tools to verify seat strength with complex structures in an early stage of seat development time. To check if the seat meets requirements and safety standards like FMVSS(Federal Motor Vehicle Safety Standards) and ECE, the whole CAD model of seat structure should be prepared for the FEA. In this study, the maximum forces that seat fails at the conditions of rail section peeling test, track pulling test, seat belt anchorage test, and frontal impact sled test have been conducted and compared each other. Main deformed parts at the analysis of whole seat structure were investigated looking at the graph of internal energy of all parts. It is found that reliable relationship exists between component or sub-assembly level test and assembly level test results. The deformed shape of the parts with high internal energy was very similar to the track pulling analysis result. It is found that failure or peeling load of seat belt anchorage analysis ranges 80-85% of the one of track pulling analysis result. Seat belt anchorage test result can be predicted after the analysis of track pulling test. As a result, engineers can reduce their development time and improve their design by ensuring the meet of requirement of full seat structure in advance.
다구찌법을 이용한 시트벨트 앵커리지 시험의 준정적 해석 방법 구현
김진규(Jinkyoo Kim),송명준(MyungJun Song) 한국자동차공학회 2005 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2005 No.11_3
To ensure proper strength of seat and seatbelt anchorage systems. some regulations such as FMVSS207/210 and ECE R14 established. FEA users released several methods to simulate quasi-static phenomena of ECE R14 test using explicit codes like LS-DYNA. On this study, the features of factors which affect dynamic characteristics of LS-DYNA were examined by the aid of Orthogonal Array and Analysis of Variables (ANOVA). Ramp time and global damping coefficient are selected as factors and have three levels for each factor. ECE R14 analysis for the changed model has done with best levels of each factor and the result of the analysis shows good correlation with test result.
동축류 초음속 추력편향 유동의 특성 및 적용성에 관한 연구
박상훈(SangHoon Park),송명준(MyungJun Song),이열(Yeol Lee) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12
The performance-characteristics of the supersonic co-flowing fluidic thrust vector control technique are studied by Schlieren flow visualizations and accurate multi-component force measurements. The technique utilizes the coanda effects of the secondary flow blowing parallel to the primary flow at the nozzle exit, and it is found that it can deflect the primary jet’s direction to some extents. In the present study, it is noticed that the technique is applicable for limited ranges of the over-expanded primary jet condition, and that the activation of the secondary flows of relatively low total pressures can hinder both the back-step effects of the primary jet onto the coanda flap surface and the primary jet’s entrainments at the downstream.
변용훈(Yonghoon Byun),김영호(Youngho Kim),송명준(Myungjun Song),이종섭(Jongsub Lee) 한국지반환경공학회 2013 한국지반환경공학회논문집 Vol.14 No.1
사질토 지반에 근입된 말뚝의 주변부에서는 말뚝의 수직하중에 의한 전단변형 시, 반경방향으로의 변위가 구속된다. 이러한 연직변위 구속상태에서의 전단강도는 기존의 직접전단실험으로는 모사하는데 어려움이 있다. 본 연구의 목적은 직접전단동안 연직변위를 허용하는 연직변위 허용조건(Free Normal Displacement: FND)의 직접전단실험과 연직변위를 허용하지 않는 연직변위 구속조건(Constrained Normal Displacement: CND)의 직접전단실험을 통하여 연직변위 구속여부가 전단강도에 미치는 영향을 평가 하는 것이다. 직접전단실험은 균등한 입도분포를 갖는 주문진 표준사를 사용하여, 연직변위의 구속여부에 따라 다양한 상대밀도와 초기응력조건 상태에서 수행되었다. 실험결과, CND 직접전단실험에서 얻은 전단강도는 FND 직접전단실험에서 얻은 전단강도보다 크게 나타났다. 또한, 상대밀도가 클수록 연직변위의 구속효과로 인한 전단강도의 증분이 더욱 늘어남을 보여주었다. 반면, 초기 연직응력의 증가는 구속효과로 인한 전단강도 증분의 감소로 나타나는 것을 관찰하였다. 본 연구에서는 경계부가 구속된 사질토지반의 안정성 평가 시, 전단강도에 대한 연직변위의 구속효과를 고려해야 함을 보여준다. Soils around a pile are highly constrained when the vertical load is applied to the pile. However, the conventional direct shear test cannot evaluate the shear strength of the soils under the normal confinement condition. The goal of this study is to evaluate the shear behaviors according to the normal displacement confinement condition including free normal displacement (FND) and constrained normal displacement (CND) during direct shearing. Jumunjin sands were prepared at the different relative densities and loaded at the different normal stresses. The specimens were sheared according to the normal confinement conditions. Experimental results show that shear strengths obtained by the CND tests are higher than those obtained by the FND tests. In addition, for the constrained normal displacement condition, the increment of shear strength increases with the increase of relative density, while the increment of shear strength decreases with the initial normal stress. This study suggests that the effect of confinement condition on the shear strength should be considered when the stability of constrained soils is analyzed.
설계민감도 해석을 이용한 안전기준 별 자동차용 시트의 설계변수 결정
이재준(Jaejun Lee),김진규(Jinkyoo Kim),남진영(Jinyong Nam),임현우(Hyunwoo Lim),송명준(Myungjun Song) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
The automobile seat must satisfy various safety regulations for the passenger's safety. In many design practices, each component is independently designed by concentrating on a single related regulation. However, since multiple regulations can be involved in a seat component, there may be design confliction among the various safety regulations. Therefore, a new design methodology is required to effectively design an automobile seat. Design sensitivity analysis is calculation of the rate of change of responses with respect to design variables. Designer can choose the effective design variables and get the information for direction of improved design with design sensitivity analysis. So, design sensitivity analysis is used determination of design variables of automobile seat. In addition, non-linear analysis is used determination of design variables of automobile seat by safety regulations. There was comparison between design sensitivity and non-linear analysis results.