• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.1
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• pp.80-88
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• 2018

The function of a vehicle holding device (VHD) is to securely hold a launch vehicle on the launch pad and release the launch vehicle at maximum thrust after engine ignition to allow lift-off of the launch vehicle. During the release of the launch vehicle, to prevent the Ka doing a doing a doing mode, which is the vertical oscillation of the entire liquid propellant, the release of the launch vehicle should be gradual. In this study, for the gradual release of a launch vehicle, a hydraulic system comprising an accumulator and pyro valve to operate a hydraulic cylinder and control the speed of the cylinder with an orifice is introduced. Through a test, the influence of design variables on the cylinder speed is analyzed. Based on this, the design values of the hydraulic cylinder are determined. Through this study, the engineering basis for developing a VHD releasing a launch vehicle at maximum thrust is provided.

• Journal of information and communication convergence engineering
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• v.15 no.1
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• pp.37-42
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• 2017

The constrained application protocol (CoAP) can be used for remotely controlling various sensor devices in Internet of Things (IoT) networks. In CoAP, to support the handover of a mobile sensor device, service discovery and message transmission needs to be repeated, although doing so would increase the handover delay significantly. To address this limitation of CoAP, a centralized CoAP scheme has been proposed. However, it tends to result in performance degradation for an inter-domain handover case. In this letter, we propose a distributed CoAP handover scheme to support the inter-domain handover. In the proposed scheme, a distributed mobility agent (DMA) is used for managing the location of mobile sensors in a domain and performing handover control operations with its neighboring DMAs in a distributed manner. A performance comparison reveals that the proposed scheme offers a performance improvement of up to 29.5% in terms of the handover delay.

• Journal of the Semiconductor & Display Technology
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• v.13 no.1
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• pp.91-95
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• 2014

(F,Ga) co-doped ZnO thin film on glass substrate was fabricated via a simple non-alkoxide sol-gel spin-coating. Contrary to the F single doped ZnO thin film, the (F,Ga) co-doped thin film showed a significant reduce in electrical resistivity after a second post-heat-treatment in reducing environment. The resulting decrease in electrical resistivity with Ga co-doping is considered to be resulted from the increases both carrier density and mobility. The optical transmittance of the (F,Ga) co-doped thin film in the visible range showed higher transmittance with Ga co-doping compared with F single doped ZnO thin film.

• Therapeutic Science for Rehabilitation
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• v.11 no.4
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• pp.7-22
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• 2022

Objective : This study aims to provide clinical evidence by systematically reviewing domestic CO-OP intervention studies. Methods : 13 papers suitable for selection criteria were finally selected and conducted. The analysis was divided into general characteristics and qualitative levels. Results : As a result of analyzing the contents of study, research has been conducted continuously since 2015, and the level of evidence for CO-OP intervention study was mainly single subject design. The subjects of the study were applied to both children and adults, and as the target activity areas of CO-OP intervention, children were shown to be play and leisure, and adults were instrumental daily living. COPM/PQRS were frequently used for evaluation to examine effectiveness of interventions. For domain specific strategies, children used body position, attention to doing, task specification, and verbal motor mnemonic. For adults, body position, attention to doing, task specification, and feeling to movement, verbal motor mnemonic, verbal rote script were used. Conclusion : It was found that CO-OP intervention is continuously being applied in occupational therapy, and age and diagnosis group are expanding. It is significant in that it provided evidence for implementing CO-OP interventions in clinical practice through a systematic review of domestic CO-OP intervention studies.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.277-280
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• 1991

We have developed 154kV OF cable accessories from 1987. 4 to 1990. 10 by doing assembly design, investing equipment, manufacturing inspecting parts, type testing in labortary, in our company, in KEPCO. The one of those accessories. Oil Stop Joint, has been developed by using Shield Metal Embeded Type Epoxy Unit. This is More reliable than old type.

• IEMEK Journal of Embedded Systems and Applications
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• v.10 no.3
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• pp.119-127
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• 2015

In the IoT(Internet of Things) environment, methods that user can access sensor node directly to collect sensing data or manage sensor in a gateway have a limitations. To solve this problem, cloud based sensor network architectures are proposed. In this paper, we proposed CoAP based IoT architecture that a lightweight gateway is used for data gathering instead of using a heavy traditional one and users can request sensing data through IoT applications running in the cloud environment and analyze signaling message cost. By doing so, our system can reduce message cost compared to the traditional gateway based system.

• Proceedings of the KIEE Conference
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• 1997.07a
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• pp.51-53
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• 1997

Even though, many types of induction motors are known, most of the single phase induction motors being used are of squirrel cage type. However, basic structure of the machine has not been changed a lot during the past century. Author had been experienced many experiments with modified rotor. The modification was completed by doing two procedures: an elimination of lamination in central pan of the rotor and filling of melted aluminium in it instead. This paper demonstrates the reason for higher efficiency.

• Elastomers and Composites
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• v.30 no.3
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• pp.185-194
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• 1995

Membrane process has been employed to separate a specific substance from gas or liquid mixture, and treat wastewater. This is due to the fact that the substance of mixture can be permeated and separated selectively by membrane. Since Initial equipment and operation costs are not expensive, membrane process has been adopted in various fields such as petroleum Industry, chemistry, polymer, electronics, foods, biochemical industry and wastewater treatment. In this study, $CaCO_3$ particles impregnated in silicone rubber network were extracted by using supercritical carbon dioxide and pore distribution of silicone $rubber-CaCO_3$ was investigated with varying amount of extract. Silicone rubber has excellent mechanical properties such as heat-resistance, cold-resistance etc. and $CaCO_3$ has microporous structure. It is possible to make silicone $rubber-CaCO_3$ composite sheets via work-intensive kneading processes. In so doing $CaCO_3$ particles become distributed and impregnated in silicone rubber network. Supercritical carbon dioxide diffuse through composite sample, then sample is swollen. $CaCO_3$ in silicone rubber network Is dissolved in supercritical carbon dioxide, and its sites become pores. Pore distribution, pore shape and surface area are observed by SEM(scanning electron microscope) micrograph and BET surface area analyzer examination respectively. Pore characteristics of membrane suggest the possibilities that the membrane can be used for process of mixture separation and wastewater treatment.

• Korean Journal of Microbiology
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• v.19 no.4
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• pp.186-191
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• 1981

Protoplast production from Trichoderma koningii ATCC 26113 was investigated for the purpose of doing basic and applied researches by protoplast fusion of the cellulolytic filamentous fungus. High yields of protoplast were obtained by using the 18hr. old mycelia treated with the lytic enzyme Driselase of Kyowa Fermentation Co., Japan, in 0.6M $MgSO_4\;or\;(NH_4)_2SO_4$ as osmotic stabilizers. The optimum temeprature of mycelial digestion was about $28^{\circ}C$ and the number of protoplast increased rapidly after 3hr. digestion. Protoplasts produced at different periods showed distinct morphological heterogeneities in the whole size and the size of vacuole.

• Proceedings of the KAIS Fall Conference
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• 2010.05a
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• pp.269-272
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• 2010

In this paper, we propose the computation reduction methods of delta pitch search that is used in G.723.1 vocoder. In order to decrease the computational amount in delta pitch search the characteristic of proposed algorithms is as the following. First, scheme to reduce the computation amount in delta pitch search uses NAMDF. Developed the second scheme is the skipping technique of lags in pitch searching by using the threshold value. By doing so, we can reduce the computational amount of pitch searching more than 64% with negligible quality degradation.