• Earthquakes and Structures
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• v.19 no.2
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• pp.91-101
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• 2020

This work presents an efficient and original hyperbolic shear deformation theory for the bending and dynamic behavior of functionally graded (FG) beams resting on Winkler - Pasternak foundations. The theory accounts for hyperbolic distribution of the transverse shear strains and satisfies the zero traction boundary conditions on the surfaces of the beam without using shear correction factors. Based on the present theory, the equations of motion are derived from Hamilton's principle. Navier type analytical solutions are obtained for the bending and vibration problems. The accuracy of the present solutions is verified by comparing the obtained results with the existing solutions. It can be concluded that the present theory is not only accurate but also simple in predicting the bending and vibration behavior of functionally graded beams.

• Journal of Korea Multimedia Society
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• v.15 no.10
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• pp.1212-1220
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• 2012

In this paper, a collision-free resource reservation scheme for WUSB (Wireless Universal Serial Bus) networks with WiMedia D-MAC (Distributed Medium Access Control). Since distributed characteristic of the WiMedia D-MAC supporting DRP (Distributed Reservation Protocol) scheme may cause lots of conflicts, overall performances of the WUSB with WiMedia D-MAC can be deteriorated. In addition, when we consider multi-hop environment, "mobile" hidden node problem due to mobility of WUSB devices can be happened, and it is a critical problem to mobile WUSB devices transceiving real-time QoS (Quality of Service) traffic. To tackle the problem, we propose a new DRP reservation mechanism to prevent DRP conflicts for multi-hop mobility support in WUSB networks with WiMedia D-MAC and show its improved performance via simulation results.

• 한국연소학회:학술대회논문집
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• 2012.11a
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• pp.205-206
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• 2012

A novel torrefaction process is suggested to improve energy efficiency and to produce high quality biomass fuel. Major developments for novel torrefaction process are as follows. To maximize the energy efficiency in heat transfer, flue gas is directly used for heat source in the torrefier. To accomplish the oxygen free environment in the torrefaction reactor, a burner is developed and it can be runned with fuel rich state. To use the calorific gases produced from torrefier, another burner is developed to combust them. In the test, the novel torrefaction process leads low energy consumption and the quality of torrefied fuel becomes better.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.39 no.4
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• pp.403-413
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• 1990

A collision free trajectory control for multiple mobile robots in obstacle-resident workspace is proposed. The proposed method is based on the concept of neural optimization network which has been applied to such problems which are too complex to be handled by traditional analytical methods, and gives good adaptibility for unpredictable environment. In this paper, the positions of the mobile robot are taken as the variables of the neural circuit and the differential equations are derived based on the performance index which is the weighted summation of the functions of the distances between the goal and current position of each robot, between each pair of robots and between the goal and current position of each robot, between each pair of robots and between obstacles and robots. Also is studied the problem of local minimum and of detour in large radius around obstacles, which is caused by inertia of mobile robots. To show the validity of the proposed method an example is illustrated by computer simulation, in which 6 mobile robots with mass and friction traverse in a workspace with 6 obstacles.

• Progress in Superconductivity and Cryogenics
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• v.3 no.2
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• pp.55-61
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• 2001

A free piston and free displacer (FPFD) Stirling cryocooler for cooling infrared and cryo-sensor is currently under development at korea Institute of Machinery & Materials. The FPFD Stirling cryocooler consists of two compressor pistons driven by linear motors which make pressure waves and a pneumatically driven displacer piston with regenerator. It is the most suitable design for a mechanical cryocooler utilized in night vision environment In this study, performance test of the Stirling cryocooler with different length of the split tube and operating frequency were performed to get characteristics of the cryocooler.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2001.02a
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• pp.33-36
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• 2001

A free piston and free displacer(FPFD) Stirling cryocooler for cooling infrared and cryo-sensors is currently under development at KIMM(Korea Institute of Machinery & Materials). The FPFD Stirling cryocooler employs 1) the Stirling cycle for refrigeration, 2) linear motors for driving the cryocooler, 3) spring and gas support systems, and 4) fine gap for clearance seals. It is the most suitable design for a mechanical cryocooler utilized in night vision environment. The experimental results show KIMM-E1 Stirling cryocooler (with expander manufactured by KIMM) has the higher cooling power and faster response time at optimum charging pressure.

• Human Ecology Research
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• v.58 no.2
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• pp.239-253
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• 2020

This study explored a sandplay therapy case of a woman maturing through conflicts with an adolescent son. The goal of the therapy was to relieve her from conflicts with going through individuation process under a free and protected space in sandplay therapy. Forty-six therapy sessions were held. The client exhibited that she needed a conversation with her feminity and maternity in the initial phase of therapy (1-5, regression). In the intermediate phase of therapy (6-43, struggle), she displayed the scenes of meeting of opposites, shadow, death, nurturing and integration of opposites. In the final phase of therapy (44-46, transformation), she showed the acception of her life with leaving her situations to God. Through sandplay therapy in the free and protected space, this study showed the effectiveness of sandplay therapy since the client achieved individuation by showing the acceptance of her life and could control her enraged feelings.

• International Commerce and Information Review
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• v.9 no.1
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• pp.313-331
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• 2007

In a rapidly changing environment of international trade, the purpose of this study is to examine economic benefits and losses of each country involved in the negotiation on the Free Trade Agreement (FTA) in Northeast Asia and to prepare strategies for the negotiation in the FTA between Korea and China. Previous researches on FTA have been made mainly from the macroeconomic perspective. The approach in this study is a combination of regulatory, reviewing regulations, and economic making quantitative analysis of the economic effects of FTA, which are the basic background of FTA. In economic analysis, I estimated the macroscopic economic effects of FTA by examining the effects of FTA on the trade balance, GDP and production of focal countries through the Computable General Equilibrium(CGE) model using GTAP data set.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.96.6-96
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• 2002

In this study an image processing system is designed and developed, which can detect and assort some defects on the surface of an object moving with high speed. For real time surface detection of high speed moving object, the fast processing should be managed and the image information including some surface features should be captured. It is difficult to acquire the noise free image due to various light sources and high speed moving materials under the environment of the general industrial site. In general, because pre-processing methods are employed for getting a noise free feature, the image processing speed has some limitation and the expensive image processing devices are required. This...

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.4
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• pp.425-429
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• 2009

The protection for copper tarnish was developed by surface treatment method and volatile corrosion inhibiting (VCI) technology. The performance of surface treatment and VCI material is also examined in simulated test environment. Benzotriazole (BTAH) solution that contained molybdate showed best performance than others. Usage of VCI materials with surface treatment was more effective. The protection film foamed on the surface of copper was investigated by auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS). Molybdate does not participate in the formation of the protective film but promotes the passivation effect. This facilitates the stabilization of the cuprous oxide film, and strengthens the adsorption of BTAH.