• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.36-41
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• 2014

Electro-Mechanical Actuator installed on aircraft consists of a decelerator which magnifies the torque to rotate an axis connected with aircraft control surface, a control section which controls the motor assembly through receiving orders from cockpit and a motor assembly which rotates the decelerator. EMA controls aircraft attitued, position, landing, takeoff, etc. It is important part of a aircraft. Aircraft maneuvering make vibration of EMA. Vibration may cause the vibration fatigue. For that reason, it is necessary to analyze the system safety. In this paper, first EMA is modeled in finite element method and analyzed the response from input vibration. second EMA is tested and analyzed from modal experimental data. third EMA Fe model is updated and re analyzed. and EMA is verified safety with $3{\sigma}$ stress and S/N curves.

• 한국정밀공학회지
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• 제18권5호
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• pp.98-104
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• 2001

A dynamic fracture toughness test method with a chevron notched ceramic specimens is proposed. The notch angles of the chevron specimens were 90, 100$^{\circ}$and 110$^{\circ}$. Finite element analysis(FEA) were done to determine the geometrical properties of chevron-notch specimens according to notch angles. The static fracture toughness of the chevron notched alumina specimen was 3.8MP$\alpha$√m similar to that of the general fracture specimen with a precrack. Dynamic fracture toughness was 4.5 MP$\alpha$√m slightly higher than the static one. These research showed the possibility of the split Hopkinson pressure bar test method using the newly proposed chevron notched specimens to get the dynamic fracture toughness of extremely brittle materials such as ceramics.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2005년도 추계학술발표대회 개요집
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• pp.79-81
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• 2005

Bridges constructed recently are preferred to have long spans and simple structure details considering not only the function as bridge but scenic beauty, maintenance, construction term and life cycle cost, etc. Therefore, they require high performance steels like extra-thick plate steels and TMCP steels. A TMCP steel produced by themo-mechanical control process is now spot lighted due to the weldability for less carbon equivalent. It improved at strength and toughness in microstructure. Recently, the SM570-TMC steel which is a high strength TMCP steel whose tensile strength is 600MPa has been developed and applied to steel structures. But, for the application of this steel to steel structures, it is necessary to elucidate not only the material characteristics but also the mechanical characteristic of welded joints. In this study, the characteristics of residual stresses in welded joints of SM570-TMC steel were studied through the three-dimensional thermal elastic-plastic analyses on the basis of mechanical properties at high temperatures obtained from the elevated temperature tensile test.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.1044-1048
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• 2006

Nuclear power generation is very dangerous in occasion that skirt of structure by earthquake although it is high effective generation that can make a lot of energies with few raw material. when design, it must consider a lot of problems caused by an earthquake. The seismic analysis of the structure has been great concern in the engineering society with an effort to reduce the severe damages from an earthquake. So the earthquake resistant design is one of the crucial design procedures of a gate valve used in nuclear power generation. The gate valve which has the contact area between stem and bellows. Because of the contact area. The gate valve should be given high stress and frictional wear. In this thesis, Considering the gate valve which has some contact distance between stem and bellows. The gate valve which has some contact distance is analyzed by a commercial FEM code of Ansys and Then compared to the gate valve behavior which doesn't have contact distance.

• 한국자동차공학회논문집
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• 제13권1호
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• pp.45-50
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• 2005

Stick type ignition coil(called a Cigar coil) is a kind of transformer for an automobile modulaized of distributer and electric cable. A material of cigar coil is PBT $GF30\%$ resin. This is an excellent engineering plastic with both mechanical and electrical properties. When we insert an HV terminal into the PBT $GF30\%$ resin jacket, it breaks the jacket, because the HV terminal is bigger than the jacket. It is a fatal on durability of a part. In this study, We used ANSYS FEM tool in order to stress analysis by contact. In order to automatically estimate possible maximum diameter of an HV terminal, we used an APDL. In the contact part, we considered the relation of the HV terminal's diameter with the amount of stress that occurred. This relation is able to be applied, in part, to the dimensions of the part design.

• 한국안전학회지
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• 제20권1호
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• pp.1-6
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• 2005

Stick type ignition coil is new development that connect directly with ECU(Electronic control unit), without needing a spark plug cable and distributor. Glass-fiber reinforced ploymeric composites provide the desirable properties of high stiffness and strength as well as low specific weight. Stick type ignition coil jacket is using PBT CF30 resin. PBT CF30 resin is a kind of electric insulation which is a superior engineering plastic that is used to prevent the leakage of the electrical current. If PET receive a mistake of design or excessive force when HV terminal oppress on jacket, it can happen to crack. Local stress concentrations occurring on the contact surface, the contact phenomenon becomes a direct cause to the wear and failure of mechanical structures. When it is cracked, it can allow a leakage of the electrical current. So, in this study, we analyze the contact stress to PBT jacket using ANSYS program, when HV terminal oppress on jacket. We suppose PBT to be Jacket and we analyzed contact stress that happens in PET like PBT analysis method. We compared the use of PBT and PET.

• 한국해안해양공학회지
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• 제3권3호
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• pp.152-162
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• 1991

하구유출유의 유동특성을 조사하기 위한 목적으로 3차원 표층밀도 분류에 관한 자유수표면을 갖는 수치 모델을 개발하였다. 난류전단응력 및 난류부력 유속은 과동점성 및 과동확산의 항으로 표현되었다. 방류수와 주위수와의 밀도차에 기인하는 성층안정효과는 경험공식에 의해 고려되었다. 기발표되어 있는 많은 실험결과와 본 모델에 의한 계산결과와의 비교로부터 본 모델의 타당성을 확인하고 최적한 성층화 함수를 확정하였다. 표층밀도분류의 3차원적인 거동특성을 조사하고, 밀도 Froude수, 방류구의 형상비 및 수표면의 변동이 유동에 미치는 영향에 대하여 토의하였다.

• 한국자동차공학회논문집
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• 제21권5호
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• pp.104-112
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• 2013

This study investigates the structural analysis result with vibration and fatigue on 3 kinds of bicycle saddle models. When the static load applies on the upper plane of model, maximum stress becomes within the allowable stress in case of model 1. As the value of Stress or deformation becomes lower on the order of model types 1, 2 and 3, these models become more stabilized or safer at durability in this order. On the vibration analysis, model type 1 has the maximum stress or deformation more than 5 times by comparing with model type 1 or 2. Model type 1 becomes most excellent on vibration durability. As maximum displacement due to vibration happens in case of model type 3, it becomes unstabilized. But the stresses of model types 1, 2 and 3 become within the allowable stress and these models are considered to be safe. At the status of the severest fatigue load, model type 3 becomes safer than model type 1 or 2. This study result is applied with the design of safe bicycle saddle and it can be useful to improve the durability by predicting prevention against the deformation due to its vibration and fatigue.

• 한국항공우주학회지
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• 제39권8호
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• pp.711-718
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• 2011

본 논문에서는 열화학적 분해 및 열기계학적 변형이 고려된 구성 방정식을 사용하여 다공성 탄소/페놀릭 복합재료의 열탄성 거동을 예측하였다. 다공성 복합재료의 온도 의존성 및 열화학적 분해 과정에서의 기공도, 분해 가스에 의한 기공 압력, 재료의 수축을 고려하였다. 기공도와 기공 압력이 고려된 대표 체적 요소 모델의 유한요소 해석을 통해 산출된 거시적 기공 탄성 계수를 구성 방정식에 적용하였다. 간단한 수치 실험을 통해 기공탄성 계수가 다공성 재료의 열탄성 거동에 미치는 영향을 분석하였으며, 재료 내부에 형성된 기공과 기공 압력에 의한 응력 구배 및 변형을 확인하였다.

• 지질공학
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• 제4권2호
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• pp.139-151
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• 1994

암반은 서로 다른 입자 및 미소크랙과 같은 미소구조의 개별요소로 구성되어 있다. 이러한 미소구조에 대한 연구는 대심도 지하공간개발과 관련된 지질공학 및 토목공학분야등에 있어서의 관심이 증대되고 있다. 따라서, 단순한 연속체역학에 의한 접근보다는 구성입자들에 대한 역학적성질 및 개별구조요소등이 고려되어야 할 것이다. 그러나, 단순한 유크리드 공간에서 아들 구조를 표현하기는 매우 어렵다. 그래서 Mandelbrot에 의해 자연에 있어서 규칙성이 거의 없는 물체를 정량적으로 표현하기위한 Fractal이론이 개발되었다. 본 연구에는, 크랙의 진전과 응력의 관계를 평가하기위해 미소구조의 기하학적 성질이 Fractal차원에 의해 계산되었다. 암반의 역학적 성질을 평가함에 있어 그 구조의 복잡성을 Fractal이론에 의해 단순화 및 수치화시켜 균질화이론에 적용시키므로서 그 평가를 보다 용이하고 효과적으로 할 수 있다.