• 한국기계가공학회지
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• 제11권2호
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• pp.137-143
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• 2012

This study analyzes flywheel through the analyses of stress, fatigue and vibration. Maximum equivalent stress is 15.271MPa at the mid round shape and maximum deformation is 0.02264mm at the outer teeth. Among the cases of nonuniform fatigue loads, 'SAE bracket history' with the severest change of load becomes most unstable but 'Sample history' becomes most stable. In case of 'Sample history' with the average stress of -$10^4$MPa and the amplitude stress of 1000 to 2900MPa, the possibility of maximum damage becomes 30%. This stress state can be 20 times greater than the damage possibility of 'SAE bracket history' or 'SAE transmission'. The range of natural frequencies becomes 200 to 820Hz and the values of these deformations are not more than 10mm. The structural result of this study can be effectively utilized with the design of flywheel by investigating prevention and durability against its damage.

• 한국수학사학회지
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• 제17권3호
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• pp.1-12
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• 2004

해석학에서는 위상 구조와 고른 구조를 거리 공간에서 다루었기 때문에 많은 혼동이 있었다. 거리 공간의 개념은 위상 구조로 일반화되었지만 '고르다'는 개념은 그 후에 앙드레 베이유에 의해서 고른 구조로 일반화되었다. 우리는 먼저 베이유의 삶과 그의 수학적 업적을 살피고 고른 구조의 역사와 발달에 대해서 알아볼 것이다.

• 한국기계가공학회지
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• 제12권2호
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• pp.8-13
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• 2013

This study analyzes about poclain bucket through fatigue durability analysis. Maximum equivalent stress and total deformation are shown at the lower of bucket and edge part respectively. Among the cases of nonuniform fatigue loads, 'SAE bracket history' with the severest change of load becomes most unstable but 'Sample history' becomes most stable. In case of 'Sample history' with the average stress of -10000Pa to 5000MPa and the amplitude stress of 0 to 6000MPa, the possibility of maximum damage becomes 3%. This stress state can be shown with 5 or 6 times more than the damage possibility of 'SAE bracket history' or 'SAE transmission'. The structural result of this study can be effectively utilized with the design of poclain bucket by investigating prevention and durability against fatigue damage.

• 한국생산제조학회지
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• 제21권1호
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• pp.51-57
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• 2012

This study investigates structural and fatigue analyses at bicycle pedal. Maximum deformation at model 1 is 2 times as much as model 2 at static analysis. Models 1 and 2 have the possibility of the weakest strength at the part of contact with chain gear. Among the cases of nonuniform fatigue loads at Models 1 and 2, 'SAE bracket history' with the severest change of load becomes most unstable but 'Sample history' becomes most stable. In case of 'Sample history' with the average stress of 0 to $-10^4$ MPa and the amplitude stress of 0 to $10^4$ MPa, the possibility of maximum damage becomes 4%. This stress state can be shown with 5 to 7 times more than the damage possibility of 'SAE bracket history' or 'SAE transmission'. The analysis result of this study can be effectively utilized with the safe design of pedal.

• 한국생산제조학회지
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• 제20권3호
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• pp.239-244
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• 2011

This study analyzes the behaviors on stress, fatigue and vibration about bulldozer in operation. Maximum equivalent stress is shown with the frequency of 100 Hz in case of the harmonic vibration analysis applied with force. Among the cases of nonuniform fatigue loads, 'SAE bracket history' with the severest change of load becomes most unstable but 'Sample history' becomes most stable. In case of 'Sample history' with the average stress of 0 to -105MPa and the amplitude stress of 0 to $1.617{\times}105MPa$, the possibility of maximum damage becomes 3.23%. This stress state can be shown with 5 times more than the damage possibility of 'SAE bracket history' or 'SAE transmission'. The structural result of this study can be effectively utilized with the design of bulldozer by investigating prevention and durability against its damage.

• 기술사
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• 제43권5호
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• pp.43-47
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• 2010

The epoch-making event of history called "JE JU 4.3" took place in JE JU beautiful island on liberation political situation in 1948. The cruelties of this event were reported awful life loss over 30,000, cruel slaughter by government, scorched villages in mountain area, silence exaction and disadvantage of implication for long time over 40 years. But, the real features are in still a fog.. Recently, the searching movement has arised owing to democracy atmosphere and literature works with "JE JU4.3" materials were published from 1988 and the government announced official apologies in 2003. The novel "The Sun-set on Halla Mt", one of those works, is accessible to real history due to its time/space back ground and the real name of persons who were related with this event. It is important for readers to consider the difference between real history and fiction story. Because a historical novel should be evaluated by writer's theme rather than history character.

• 한국기계기술학회지
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• 제13권3호
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• pp.87-92
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• 2011

This study analyzes structural stress and fatigue on control arm of automobile under nonuniform load. Maximum equivalent stress at bolt part is shown with 419.1MPa and the corner is deformed with maximum displacement of 1.1628mm. Among 3 cases of nonuniform fatigue loads applying on control arm, 'SAE bracket history' with the severest change of load becomes most unstable but 'Sample history' becomes most stable. In case of 'Sample history' with the average stress of $-10^5MPa$ to $10^5MPa$ and the amplitude stress of 0 MPa to $10^5MPa$, the possibility of maximum damage becomes 3%. This stress state can be shown with 6 times more than the damage possibility of 'SAE bracket history' or 'SAE transmission'. Safety and durability on automobile can be effectively improved by applying the fatigue analysis result on control arm.

• 한국정밀공학회지
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• 제14권6호
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• pp.22-27
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• 1997

In general, the load which acts on the structure is almost independent of time in many locations. In this case. It is difficult to estimate the life with the service load history, because the structure is on the multi- axial and multi-point loading states. In this study, the service load of the excavator which is widely used in industry field was calculated using measured cylinder pressures and displacements. The fatigue life was estimated using the multi-axial and multi-point load counting method. Service load history of 4 pin joint which act independently each other is yielded by mult-axial and multi-point load counting method. The stress spectrum is yielded by superposition of the results of FEM stress analysis applied unit load. Palm- gren-Miner's cumulative Damage is 0.000804 for Von Mises equivalent stress sequence by one side fillet weld S-N curve. This result agress with Bench test results. As a result of this study, the fatigue life esti- mation using the multi-axial and multi-axial and multi-point load counting method is useful.

• Structural Engineering and Mechanics
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• 제35권3호
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• pp.283-299
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• 2010

This paper addresses the numerical simulation of fatigue crack growth in arbitrary 2D geometries under constant amplitude loading by the using a new finite element software. The purpose of this software is on the determination of 2D crack paths and surfaces as well as on the evaluation of components Lifetimes as a part of the damage tolerant assessment. Throughout the simulation of fatigue crack propagation an automatic adaptive mesh is carried out in the vicinity of the crack front nodes and in the elements which represent the higher stresses distribution. The fatigue crack direction and the corresponding stress-intensity factors are estimated at each small crack increment by employing the displacement extrapolation technique under facilitation of singular crack tip elements. The propagation is modeled by successive linear extensions, which are determined by the stress intensity factors under linear elastic fracture mechanics (LEFM) assumption. The stress intensity factors range history must be recorded along the small crack increments. Upon completion of the stress intensity factors range history recording, fatigue crack propagation life of the examined specimen is predicted. A consistent transfer algorithm and a crack relaxation method are proposed and implemented for this purpose. Verification of the predicted fatigue life is validated with relevant experimental data and numerical results obtained by other researchers. The comparisons show that the program is capable of demonstrating the fatigue life prediction results as well as the fatigue crack path satisfactorily.

• 수산해양교육연구
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• 제24권6호
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• pp.1013-1026
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• 2012

The 2007 revised social studies curriculum emphasizes history education in particular. Thus the contents of the history section previously scattered through 3rd, 4th, 5th and 6th grades are now integrated into the first and second semesters of the 5th grade in elementary social studies. Therefore, this research intend to gain insights that could be used as a reference when making next social textbooks by analyzing social textbooks of the 7th and the 2007 revised curriculum. The conclusions of comparative analysis on social textbooks of the 7th and the 2007 revised curriculum are as follows: The textbook units according to the 2007 revised curriculum were a reorganization of the contents from the 7th's 6th grade 1st semester contents per unit in a chronological flow. Meanwhile, the topic was introduced to supplement historic contents afresh. The 2007 revised curriculum focused on the life history, cultural history, personal history.