• Proceedings of the KSME Conference
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• 2004.04a
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• pp.302-307
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• 2004

This paper reviewed characteristics of fatigue crack behavior observed by changing various shapes of initial crack and magnitudes of loading in compact tension shear(CTS) specimen subjected to shear loading. In the high-loading condition, fatigue crack under shear loading propagated branching from the pre-crack tip. Meanwhile, the secondary fatigue crack in the low-loading condition which was created in the notch root due to friction on the pre-crack face grew to a main crack. Influenced by the mode II loading condition, fatigue crack propagation retardation appeared in the initial propagation region due to the reduction of crack driving force and friction on crack face. In both cases, however, fatigue cracks grew in tensile mode type. Propagation path of fatigue crack under the shear loading was 70 degree angle from the initial crack regardless of its shape and load magnitude.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.14 no.6
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• pp.117-124
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• 2005

This study developes the vibration model to estimate the vibration energy of compact disc player's mainbase assembly which is supported by dampers and springs, and this model is verified by experiment. From frequency response function, we investigate the natural frequency and mode shape in the up/down direction for mainbase assembly. In order to determine the analysis frequency band, we investigate the excitation frequency of road from the vehicle test. As the characteristics of dampers and springs are changed, we carry out the sensitivity analysis of vibration energy for mainbase assembly which include optical pick-up and feeding system. And we found out that the properties of damper were dominant element in the vibration energy of mainbase assembly's CG(center of gravity).

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.4
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• pp.126-132
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• 2008

The vibration and disturbances from operating the compact disk layer have an effect on the play ability. As the excitation sources of the compact disk player, there are the vibration of the motors and gears, impact by mechanical parts and the external excitations. So, most of the compact disk player have a anti-vibrational system, which is included some rubber or oil dampers. In this study, the vibration characteristics of rubber damper which is used home compact disk player are investigated. The materials and shape of rubber damper are changed, and the transmissibility is measured. As a conclusion, the natural frequency is moved to higher frequency and the transmissibility is reduced by the increasing rubber stiffness. In comparison to butyl rubber damper, the transmissibility of silicon damper was increased by larger restitution elasticity. The hollow damper was effective to reduced the transmissibility.

• Proceedings of the Korea Society for Simulation Conference
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• 1999.10a
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• pp.56-61
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• 1999

The Simulation of Boiler System for Hadong Fossil power plant has been made by Korea Electric Power Research Institute (KERRI) in an attempt to develop Windown NT based full scope replica simulator for Hadong Fossil power plant, 500MWe once-through boiler. In the project KERRI developed Once Through, Super Critical type Boiler System, the core part of the Simulation and integrated the system with other process systems such as BOP System, and AUX System. This paper is to introduce the basic concept of the simulation for the Boiler System. It will also introduce PRO-TRAX System, for used as a modeling tool.

• Journal of the Korea Safety Management & Science
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• v.9 no.5
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• pp.111-116
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• 2007

The objective of this paper is to calculate the minimum scale of management for transportation business in order to achieve a form of enterprise. In this study the tracking minimum scale of business is the minimum number of operating trucks. Transportation companies should ensure the number of trucks for a type of business model rather than a means of livelihood model. The method to calculate the minimum number of trucks for the transportation business model can use an approach of either the qualitative and the quantitative technique. This study chooses the quantitative technique to calculate the minimum number of trucks through the analysis of break-even point.

• Korean Journal of Plant Taxonomy
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• v.49 no.4
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• pp.374-379
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• 2019

In this study, we report a new record of the clustered bur-reed Sparganium glomeratum (Laest. ex Beurl.) Beurl., from Yongneup Moor of Daeamsan Mt. in Gangwon-do, Korea. This species is distributed in the cool temperate and circumboreal regions of the Northern Hemisphere. As we recorded this species in a high-altitude wetland, we named it "Du-me-heuk-sam-neung" after the Korean word that translates to "Sparganium found in deep mountains." We provide descriptions of the morphological characteristics, photographs, and detailed illustrations of S. glomeratum, as well as a key to allied taxa in Korea.

• Proceedings of the KSR Conference
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• 2003.10c
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• pp.103-108
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• 2003

Among welded structure bogies in use for high speed freight car, a part of bogies manufactured in 1999 and 2000 have found problems that failure occurs in its end beam. In case of a freight car a difference of weight between empty and loading conditions are worse than in case of a passenger car. Moreover its brake system is tread brake without second suspension system. A failure of end beam is supposed to be due to loading by brake rather than vertical loading by freight. This failure can make brake system useless and may be a cause of derailment in the worst case. In this study, in order to be proved the cause of failure and to solve the problem it is described that we have measured load history acted on end beam and set up the procedures.

• ICROS
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• v.21 no.2
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• pp.31-38
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• 2015

의족은 선천적 또는 후천적으로 하지의 일부를 상실한 사람의 신체를 대신하는 보조기구이며, 의족의 가장 이상적인 목표는 사람의 신체를 온전히 대체하는 것이다. 기존의 수동 의족은 신체의 구조적인 해석과 기계적인 에너지 보존을 통하여 절단 환자의 움직임을 보조하는 선에서 그쳤지만, 최근에는 로봇 공학과 반도체 공학 등 다양한 기술의 발전에 따라 의족에서도 동력을 사용하여 근육의 역할을 대신하기 위한 시도가 이루어지고 있다. 본 기술 논문에서는 하지 절단 환자를 보조하기 위한 동력 의족을 사람의 신체와 비교하여 어떤 기구적인 제약조건을 가지고 있는지 설명하고, 정상인의 보행과 동력 의족의 구동 알고리즘을 비교함으로써 동력 의족에서 사용하고 있는 유한 상태 제어기의 한계점에 대해 언급한다. 마지막으로 근전도를 활용한 동력 의족을 통해 새로이 시도되고 있는 의지적 제어에 대해 소개하고, 동력 의족의 연구가 앞으로 나아갈 방향을 제시한다.

• Proceedings of the Korean Society of Sericultural Science Conference
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• 2005.11a
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• pp.48-48
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• 2005

• Proceedings of the Korean Society of Sericultural Science Conference
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• 2005.11a
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• pp.50-50
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• 2005