• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.6
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• pp.859-866
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• 2010

Generally, a fixed type guide-bush system is installed during machining miniature work-pieces with high precision in the multi-task CNC lathe. But a conventional guide-bush system does not provide a constant clamping force under the condition of varying work-piece diameters. It is important to maintain a constant clamping force for guaranteeing machining precision. This paper proposes a new guide-bush system with a pneumatic clamping device for the CNC Swiss-turn lathe to keep constant clamping force with changes in work-piece diameters. Through performance tests, new clamping system developed in the study showed better machining precision at the cost of a small increase in the temperature of the system than conventional systems due to an increase in the frictional heat and a change in the heat transfer route.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1411-1414
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• 2008

It is reported that mechanical stimulation takes a role in improving cell growth in skeletal system. And various research groups have showed that developed bioreactor to stimulate cell-seeded and threedimensional scaffold. In this study, we designed a custom-made bioreactor capable of applying controlled compression to cell-seeded agarose gel. This device consisted of a circulation system and compression system. In circular system, culture chamber was sealed for prohibiting contamination and media solution was circulated by pump. In compression system, mechanical stimuli were controlled by LabVIEW software and mechanical transfer system. Cell-encapsulated agarose gels were cultured for up to 7 days. There were significant differences between the number of cells grown in dynamic cell culture and in static cell culture from 3 days to 7 days.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.5
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• pp.430-436
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• 2008

This paper proposes a way to predict electrical lifetime of a relay using Accelerated Life Testings (ALTs). The relay of interest mounting on printed circuit boards is usually under an inrush current stress. The inrush current is generated and accelerated through controlling a lamp switching device in the ALT. We find that the dominant failure mechanism under high levels of inrush current would be contact welding in the contact surface of the relay and the contact welding process is accelerated according to increase in inrush current. The electrical lifetime model based on Inverse Power Law in term of inrush current is proposed, and parameters characterizing relay's lifetime distribution are statistically estimated using ALTA 6 PRO software.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.31-36
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• 2003

Recently, the power consumption and heat generation in an electronic equipment increase as the components are miniaturized and the computing speed becomes faster. Effective cooling method is required to ensure the guaranteed performance and reliable operation of the electronic devices. The aim of the present study is to investigate the cooling characteristics of a pin-fin heat exchanger as a candidate for cooling system of the electronic devices. Various configuration of the pin-fin array is selected in order to find out the effect of spacing and diameter of the pin-fin on the heat transfer characteristics. The results are compared with the experimental data or correlations of several researchers for the channel flow with pin-fin arrays.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.441-441
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• 2014

The characteristics of hybrid conductive films based on multilayer graphene and silver grid have been investigated for the high-performance and flexible organic solar cells. The hybrid conductive films have been prepared on glass and polyethylene terephthalate (PET) substrates using conventional photolithography process and transfer process of graphene. The optical and electrical properties of prepared conductive films show transmittance of 87% at 550nm and sheet resistance of $28{\Omega}/square$. The electromechanical properties were also investigated in detail to confirm the flexibility of the hybrid films. OSCs have been fabricated on the hybrid conductive films based on graphene and silver grid on glass substrate. The power conversion efficiency of 2.38%, a fill factor of 51%, an open circuit voltage of 0.58V and a short circuit current of $8.05mA/cm^2$ were obtained from the device on glass substrate. The PCE was enhanced 11% compared with OSCs on the MLG films without silver grid.

• Proceedings of the KIPE Conference
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• 2003.07b
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• pp.908-912
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• 2003

The waste heat recovery system using heat pipe was tested for the consideration of developing the high-efficiency waste heat recovery technology. Heat pipe, a effective device that can quickly transfer large amounts of heat energy using the phase change of the working fluid and the characteristics of Electric Heater Bars used for alternative heating system are introduced In this paper. In order to increase energy efficiency, the system which controls the status of electric heater bars and the temperature of heat pipe installed has developed.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.7
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• pp.351-363
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• 2001

This paper presents an experimental investigation on the heat trensfer characteristic of micro pipe (MHP) array with 38 triangular microgrooves. A heat pipe is an effective heat exchanger operating without external power. The heat pipe transfers heat by means of the latent heat of vaporization and two-phase fluid flow driven by the capillary force. The overall size of the MHP array can be put undermeath a microelectonic die and integrated into the electrronic package of a microelectronin device to dissipate the heat from the die. The MHP array is fabricated by micromachining with a silicon wafer and a glass substrate. The MHP was filled with water and sealed. The experimental results show the temperature decrease of 12.1$^{\circ}C$ at the evaporator section for the input power of 5.9 W and the improvement of 28% in the heat transfer rate.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1539-1541
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• 2002

When did Metal (Au, Al) electrode differently, it is spread already that it is by energy level of electrode difference of electrical conductivity. This paper, experiment manufactures device of Metal/Organic Films/Metal structure using PBDG and I-V properties by electrode analyzed comparison. Also, measure energy level by electrode by propertiesy electrochemistry and studied about electron transfer of organic thin film in LUMO level relation with HOMO level.

• Journal of the Korean Operations Research and Management Science Society
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• v.21 no.2
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• pp.17-33
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• 1996

Automatic transfer defined as an integrated system with a number of workstations, interstation storage buffers, automatic device and a control system, play a major role in ass production systems. Due to high capital investment needed for an automatic transferline, greater care should be taken in its design so as to maximize the system performance. One may to control the system performance is to control buffer storage. To control the interstation work-in-process inventory, we propose dual limit switches which control the buffer storage with two parameters, R and r. Under the policy, proceding station is forced down when the inventory level in the buffer reaches R until the level falls to r. For the model developed, we analyze the system characteristics and find the optimal control parameters with a serach procedure.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.291-291
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• 2000

A vehicle driving simulator is a virtual reality device which a human being feels as if the one drives a vehicle actually. Driving Operation System acts as an interface between a driver and a driving simulator. This paper suggests the driving operation system for a driving simulator. This system consists of a controller, DC geared motor, MR brake, rotary encoders, steeping motor and bevel gear box. Reaction force and torque on the steering system were made by DC_Motor and MR_Brake. Reaction force and torque on the steering system were compare between real car and a driving simulator. The controller based on the 80C196KC micro processor that manage and transfer signal.