• Journal of rehabilitation welfare engineering & assistive technology
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• v.11 no.4
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• pp.299-306
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• 2017

The Korean medical device industry has increased dramatically due to various investments in the domestic medical device industry and the introduction of new technologies, but the domestic medical device usage rate in great hospital is still low. In this paper, improvement point for domestic medical device was suggested by domestic medical device usage rate and user and manager's perception survey in great hospitals in Korea. To do this, a survey on the types of medical devices and domestic medical device usage rates were conducted at four national university hospitals in Korea. From this results, the priority survey medical devices were selected. Improvements of Korean medical devices were suggested by failure mode analysis and user awareness surveys for the priority survey medical devices.

• The Journal of the Korea Contents Association
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• v.13 no.4
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• pp.137-144
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• 2013

As the propagation of smart devices has increased and the variety of the devices also has been diversified, various existing functions are concentrated on these smart devices. One of the phenomena is that the paper-book market has partially transferred into an e-Book market. As the demand of the e-Book has increased over time, the improvement of the types of e-Book on the market can be observed. In this study, the usability evaluation on the interface of the e-Book viewer for the types of application, which can be installed in the smart devices, has been conducted. The items for the usability evaluation of the e-Book were defined, the usage patterns were observed objectively and a questionnaire technique was applied. By analyzing the usability evaluation of e-Book interface, the directions for production and improvement of e-Books have been suggested.

• Journal of Electrical Engineering and Technology
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• v.7 no.5
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• pp.672-680
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• 2012

This paper proposes the control strategy of the shunt Flexible AC Transmission System (FACTS) devices to improve transient stability in multimachine power system. The multimachine power system has high nonlinear response after severe disturbance. The concept of Lyapunov energy function is applied to derive nonlinear control strategy and it was found that the time derivative of line voltage is not only can apply to control the shunt FACTS devices in multimachine system but also is locally measurable signal. The fuzzy logic control is also applied to overcome the uncertainty of various disturbances in multimachine power system. This paper presents the method of investigating the effect of the shunt FACTS devices on transient stability improvement. The proposed control strategy and the method of simulation are tested on the new England power system. It was found that the shunt FACTS devices based on the proposed nonlinear control strategy can improve transient stability of multimachine power system.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.2
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• pp.94-97
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• 2018

Lead zirconate titanate/poly-vinylidene fluoride (PZT/PVDF) piezoelectric devices were fabricated by incorporating carbon nanotubes (CNTs), for use as flexible energy harvesting devices. CNTs were added to maximize the formation of the ${\beta}$ phase of PVDF to enhance the piezoelectricity of the devices. The phase transition of PVDF induced by the addition of CNTs was confirmed by analyzing the X-ray diffraction patterns, scanning electron microscopy images, and atomic force microscopy images. The enhanced output efficiency of the PZT/PVDF piezoelectric devices was confirmed by measuring the output current and voltage of the fabricated devices. The maximum output current and voltage of the PZT/PVDF piezoelectric devices was 200 nA and 350 mV, respectively, upon incorporation of 0.06 wt% CNTs.

• Journal of Biomedical Engineering Research
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• v.39 no.6
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• pp.268-277
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• 2018

With drastic change in the market and technology of medical devices, a comparative analysis is necessary in advanced systems internationally in order to prepare domestically applicable plans for improvement in classification and differential grade management for items of medical devices. This research examines and analyzes the differences of definition and legal systems of medical devices among Korea, United States, EU, Japan and China, and investigates classification and grading system of each country to identify disadvantages of classification and grading structures for medical device in Korea. This research suggests ways to supplement the disadvantages of domestic classification and grading system of medical devices, and elicits differential management plans for medical devices.

• International Journal of Highway Engineering
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• v.10 no.4
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• pp.235-245
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• 2008

Since rapidly increase of tunnel with increasing of expressway, the study on safety improvement of safety device at entrance of expressway tunnels is necessary. The existence of tunnel occurs more speed reduction than an upward slope by itself, the collision accident of tunnel entrance causes heavier damage than that of general accident on the road. So, many kinds of safety devices such as poly-ethylene barrier, guard-rail are placed on the road side. But these devices affect the drivers as an obstacle. Although there are various safety devices that are placed at tunnel entrance, this study is related to following 2-cases. One is that the poly-ethylene barrier is placed and the other is that a safety devices is not placed. The reason that these two cases are selected, is that poly-ethylene barrier is usually placed at many tunnel entrances and safety devices can affect the drivers as an obstacle. This study is related to the difference of right-hand side clearance between inside tunnel and outside tunnel, too. The average difference observed car speed and VDS(vehicle detect system) speed nearby the tunnel is analysed. Through the statistical analysis of the average difference, this study suggests an alternatives on safety improvement of safety devices at entrance of expressway tunnels. It is concluded that the small difference of right-hand side clearance is desirable to drivers when a poly-ethylene barrier is placed. And when the difference of right-hand side clearance is large, no safety devices is desirable, and when the difference of right-hand side clearance is small, poly-ethylene barrier should be placed to improve safety.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.05a
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• pp.189-192
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• 2004

To improvement life-time of the organic light emitting diodes(OLEDs). We investigate the inorganic composite film based on MgO and $SiO_2$ to protect from the moisture and oxygen. The inorganic composite films are added the base materials to the co-operate materials using the mixed process and it is deposited on plastic substrate by e-beam evaporator. In order to analyze as kinds of inorganic materials, Water Vapor method of Transmission Rate (WVTR) and Oxygen Transmission Rate (OTR) are measured by Permatran equipment(MOCON Corp.). For comparison. an MgD- and $SiO_2$-based composite film has lower values of WVTR and OTR than inorganic composite/compound films of ones. The results obtained here shows that this film is suitable for passivation layer to extend the life-time of OLEDs.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.178-181
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• 2001

The organic light-emitting devices (OLEDs) based on fluorescence have low efficiencies due to the requirement of spin-symmetry conservation. By using the phosphorescent material, the internal quantum efficiency can reach 100 %, compared to 25 % in the case of the fluorescent material. Thus, the phosphorescent OLEDs have recently been extensively studied and showed higher internal quantum efficiencies then the conventional OLEDs. In this study, we investigated the characteristics of the phosphorescent OLEDs, with the green emitting phosphor, Ir(ppy)$_3$ (tris(2-phenylpyridine)iridium). The devices with a structure of ITO/TPD/Ir(PPy)$_3$ doped in the host material/BCP/Alq$_3$/Li:Al/Al were fabricated, and its electrical and optical characteristics were studied. By changing the doping concentration of Ir(PPy)$_3$ and the host materials, we fabricated several devices and investigated the device characteristics.

• Journal of the Korean Vacuum Society
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• v.4 no.1
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• pp.60-66
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• 1995

• Proceedings of the Korean Nuclear Society Conference
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• 2003.10a
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• pp.477.2-477.2
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• 2003