• 한국정밀공학회지
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• 제21권10호
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• pp.170-179
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• 2004

A vibration model of powder transfer equipment is developed by the lumped parameter method. A Powder transfer equipment does surging motion, bouncing motion and pitching motion. Motion equation becomes decoupling and removed vibration exciting source about pitching motion, and therefore designers presented the optimum design plan to be able to do adjustment with motion trajectory of powder transfer equipment. That is, way for design to be able to do motion trajectory of powder transfer equipment through change of design element as installation position and direction of motor, driving speed, mass unbalance, stiffness coefficient and installation position of support coil spring is presented. The design results, powder transfer equipment were able to know that fatigue destruction does not occur, and the reason is because maximum stress working on a basket structure is more very than fatigue strength small.

• International Journal of Precision Engineering and Manufacturing
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• 제7권2호
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• pp.60-65
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• 2006

A vibrational model of powder transfer equipment based on the lumped parameter method was developed, in which the operating motion consists of surging, bouncing, and pitching. After decoupling the equation of motion, the vibrational excitation source of the pitching motion was removed. So the designers are able to plan the optimum design to adjust the motion trajectory of the powder transfer equipment. That is, a procedure to adjust the motion trajectory of powder transfer equipment by changing design specifications such as the installation position, the direction of the motor, the driving speed, the mass unbalance, the stiffness coefficient, and the installation position of the support spring, is presented in this paper. The powder transfer equipment manufactured according to the results of this study did not suffer fatigue destruction, since the maximum stress on the basket structure was sufficiently small.

• 한국공작기계학회논문집
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• 제17권1호
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• pp.92-97
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• 2008

The safety and the durability of the shock absorber as an automotive chassis part under the fatigue load can be predicted in this study. The fatigue life becomes constant from 0.5 to 0.75 at the change of load which is the amplitude load divided by average load. But its life is sharply decreased at the change of load from 0.75 to 1.5. The influence of fatigue life according to the change of load can be predicted by these results. As the value of maximum damage is 9.61 at the middle part of upper side on shock absorber under the concentrated load, there is the greatest possibility of destruction at this part. The spring of shock absorber becomes nearly the state of pure shear and the uniaxial or biaxial stress exists at the rest part of it under the fatigue load.

• 한국기계가공학회지
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• 제6권3호
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• pp.92-97
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• 2007

The overlay welding the automobile where the durability is demanded, it is used in the vessel engine valve, plant valve and pump parts. Cause of damage public opinion one what is thought is the fatigue load due to the opening and shutting operation right time repetition of the engine valve. The damage cause of the engine valve or explanation of destruction mechanism is very difficult. The research which it sees to make clear a overlay welding of Co-alloy by Plasma Transferred Arc Weld Surfacing Process reconsideration fatigue crack initiation and fatigue crack growth mechanism at high temperature.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집A
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• pp.199-204
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• 2001

Big accidents of flyings, vessel, subways, gas equipments, buildings and bridge happens frenquently. Therefore many people are suffering harm of property. The destruction cause of macaine components is almost accused by fatigue. This study is test for STS304 specimen using pure and cantilever bending state. Rounded specimen and notched specimen including fracture surface investigation was comparatively experimented, fatigue life according to degree of surface finishing was examined. Fatigue fracture probability of notched canilever specimens were predicted by P-S-N curve, median rank and Weibull distribution. And at the relation with the rotational speed and stress, the fatigue life of the test specimen was higher at high speed than low speed.

• 한국방재학회 논문집
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• 제11권2호
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• pp.15-21
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• 2011

복합재료가 건설 분야에서 보다 광범위하게 이용되기 위해서는 일반 기술자에게 이론을 쉽게 하기 위한 연구와 시험을 통한 데이터의 축적이 필요하다. 따라서 본 논문에서는 복합재료인 FRP 바닥판 부재의 따른 정적 및 피로성능을 평가하고 향후 FRP 바닥판의 해석 및 설계기준의 기초 자료를 제공하여 복합재료의 구조재 활용을 위한 기반기술을 제공하고자 하였다. 정적시험 결과 섬유방향 시험체가 섬유직각방향 시험체보다 큰 강성을 갖고 있으며 데이터 값이 훨씬 수렴되는 경향을 보이는바 이는 파괴과정에서 기지 배열에 따른 구조 특성으로 보다 안정적인 거동을 보이는 것을 알 수 있었다. 피로시험 결과 섬유방향 시험체는 섬유직각방향 시험체가 초기에 균열이 발생하는 것과 달리 시험체의 반복횟수가 증가하면서 파괴 직전에 균열을 확인할 수 있었으며, 접착면이 떨어지는 양상을 보였다.

• 대한기계학회논문집A
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• 제31권12호
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• pp.1214-1220
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• 2007

The vertical roller mill, which performs the grinding and partly blending of raw material, is the one of the important machine to produce ordinary portland cement. It has been reported that an unexpected fatigue failure occurred in a table liner in the course of grinding portland cement. The life of table liner is estimated to $4{\times}10^7$ cycles in the design stage, but at the field, when its operating time reaches to $2{\times}10^6{\sim}8{\times}10^6$ cycles, the fracture of table liner begins to be found. The fracture of table liner is initiated from the outside edge of grinding path contacting with the grinding roller. Its maintenance normally take 30 % of the total maintenance costs of the roller mill. Therefore, this study shows the clarification of the reasons occurring the fatal destruction of the table liner by fatigue fracture analysis utilizing fracture mechanics and by the finite element method. And, the results from Goodman diagram illustrate relationship of including information on the transition between tensile and bending fatigue strength in the fatigue characterization of table liner.

• Journal of Advanced Marine Engineering and Technology
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• 제35권7호
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• pp.899-906
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• 2011

Generally, load conditions of machine or structure in fatigue destruction is occurred not under single load conditions but under mixed load conditions. However, the experiment under mixing mode is insufficient because of no having test standard to the behavior of crack under mixing mode and variety of test methods, and many tests are required. In this paper measured crack direction path by created figure capture system when a experiment. Also, we studied by comparison the behavior of crack giving the change of stress ratio and inserting beach mark. Through the test under mixing mode, advancing path of crack is indicated that advancing inclined angle ${\Theta}$ (direction of specimen length) has increased depending on the increase of mixed mode impaction. It is indicated that according to the increase of mixed mode loading condition impaction under mixing mode, advancing speed of crack gets slow. Also, we found that inner crack(cross section of specimen) is progressed more rapidly than outer crack based on data through beach mark.

• 한국산학기술학회논문지
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• 제8권3호
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• pp.427-431
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• 2007

본 연구를 통하여 피로를 받는 자동차 섀시 부분인 암에 대한 안전성과 내구성을 예측할 수 있다. 하중의 변화는 하중의 진폭을 평균 하중으로 나눈 값으로서 하중의 변화가 0.5부터 0.75에서는 급격하게 피로 수명이 감소되나 0.75이상부터 1.5까지는 그 수명이 완만하게 변화된다. 이러한 결과들에 의하여 하중의 변화에 대한 피로 수명의 영향을 예측할 수 있다. 또한 집중 하중을 받는 로드 엔드의 연결 부분에서 최대의 손상값인 2.2를 보이고 있어 이 연결 부분에서 파단의 가능성이 가장 큼을 보이고 있다. 또한 이 부분에서는 $-6.93{\times}10^{-3}$의 압축 변형율로서 최대의 압축 응력이 349 Mpa이 되어 압축으로 인하여 파단 될 가능성이 큼을 알 수 있다.

• 한국철도학회논문집
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• 제20권5호
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• pp.658-667
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• 2017

철도는 여객을 수송하기 위한 수단으로, 열차의 주행안정성과 탈선방지 등 절대적인 승객의 안전을 확보하는 것이 중요하다. 철도에서 사용하고 있는 레일은 여객을 안전하게 수송하는데 있어 가장 중요한 역할을 담당하는 궤도의 구성품이며, 안전을 위하여 레일의 피로, 파괴에 대한 신뢰성 확보가 엄격히 요구되고 있다. 본 논문에서는 콘크리트 궤도(STEDEF)의 현장측정을 통해 레일표면요철과 레일휨응력이 선형적인 상관관계가 있음을 확인하였으며, 레일표면요철, 궤도지지강성, 열차속도에 따른 레일의 휨응력예측식을 제시하였고, 실내 피로시험을 통해 S-N선도를 도출하여 레일 피로수명을 산정하였다.