• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.4
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• pp.28-34
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• 2012

Installing surge protection devices for a low-voltage system is important to ensure the survival of electric or electronic devices and systems. If surge protection devices (SPD) are installed without consideration of the concept of lightning protection zones, the equipment to be protected might be damaged despite the correct energy coordination of SPDs. This damage is induced by the reflection phenomena on the cable connecting an external SPD and the load protected. These reflection phenomena depend on the characteristics of the output of the external SPD, the input of the loads, and the cables between the load and the external SPD. Therefore, the SPD has an effective protection distance under the condition of the specific load and the specific voltage protection level of SPD. In this paper, PSCAD/EMTDC software is used to simulate the residual voltage characteristics of SPD Entering the low-voltage device. And by applying a certain voltage level, the effective protection distances of SPD were analyzed according to the each load and length of connecting cable, and the effectiveness of SPD were verified.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.9
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• pp.52-59
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• 2014

The aims of this paper are to characterize the transient overvoltages(TOVs) and to evaluate the risk occurring at 22.9kV consumer's substation. The measurements of lightning- and switching-caused TOVs were made during Mar. 2013 and Feb. 2014. As a consequence, 47 events of TOVs were recorded and 4 of them were higher than the input voltage envelope(IVE) of the information technology industry council(ITI) curve. The measured TOVs are characterized by longer front times and longer durations compared to the $1.2/50{\mu}s$ standard impulse voltage waveform, and some of them represent bipolar waves with lower oscillation frequencies. It suggests that the test of non-standard impulse voltage waveforms is needed for effective risk assessments of power apparatus. Lightning- and switching-caused TOVs exceeding IVE of ITI curve are induced at the secondary of 22.9kV potential transformer(PT). We may, therefore, conclude that the surge protection devices should be applied at the secondary of PT and the surge absorbers should be installed at the primary of VCB or PT. The results presented in this paper could be useful to design the reasonable insulation coordination for 22.9kV consumer's substation.

• Journal of the Korean Operations Research and Management Science Society
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• v.37 no.3
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• pp.79-94
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• 2012

According to the higher dependence of contemporary firms on data digitalization and the information technology, the role and importance of Information Security Management (ISM) is getting higher. Thus, there is a need to arrange proper procedure and a series of device within the organization in order to reduce diverse security risks, which take place from the inside and the outside of firm. In other words, prior examination for reinforcing recognition of ISM, and of a systematic performance method in the refined form is important. This study investigate the key variables influencing the ISM. Thus, this study suggests firm environmental factors that include four exogenous variables, market volatility, task interdependence, perceived benefits, and coordination mechanism affecting awareness of ISM. In addition, it proposes a concept of the ISM process with awareness, development, and performance, and examines the moderating effects of regulatory influence. The research model was tested by using Structural Equation Modeling, via SmartPLS 2.0 analysis on a sample collected from 186 employees in various industries. The research results provide the evidence that supports the tested hypotheses except significance of coordination mechanism. The implications of the findings suggest a new theoretical framework of the ISM and offers important solutions for the practical application guidelines.

• Journal of the Korea Society for Simulation
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• v.22 no.1
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• pp.1-8
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• 2013

A higher penetration of renewable energy sources and adoption of renewable portfolio standard(RPS), the penetration of distributed generators(DGs) into power distribution network is becoming a threat for the safe operation of distribution network. The ground fault current of DGs can cause parasitic trip and mal-trip of protective device in the power distribution network. KEPRI has developed a simulation program for current setting of protective devices in DGs connected distribution network. In this study, we analyzed fault currents of a sample network in two cases, i.e. case 1 is for no DG connection, case 2 for a DG connection. We performed protection coordination for relays installed in the network and analyzed the contribution of a DG.

• The Korean journal of sports medicine
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• v.36 no.4
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• pp.189-196
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• 2018

Purpose: The purpose of this study was to compare the difference of body mass index (BMI) to smart phone proficiency in men and women over the age of 60. Methods: Patients were divided into three groups with high (n=33), average (n=34), and low (n=33) smart phone proficiency. Fitness characteristics related to smart phone usage were evaluated by measuring cardiorespiratory endurance, grip strength, eye-hand coordination. As well, smart phone proficiency was evaluated by a self-reported questionnaire and a smart phone usability task that was composed of two categories: usage of the smartphone device itself and usage of phone applications. The differences in BMI of the subjects was analyzed by analysis of covariance adjusting for independent variables including age, smartphone usage period, eye-hand coordination, education and income. Results: There was a significant difference in BMI among the three groups after adjustment of age, eye-hand coordination, smartphone usage period, education and income. The results showed that the self-reported questionnaire showed a significant difference in BMI between high proficiency and low proficiency groups (high $24.88{\pm}2.46$, low $23.37{\pm}2.56$; p=0.037). Smart phone usability test results also showed a significant difference in BMI among the three groups (high $25.18{\pm}2.58$, low $23.15{\pm}2.6$; p=0.000 and high $25.18{\pm}2.58$, middle $23.57.7{\pm}1.69$; p=0.010). Conclusion: Our results suggest that high smart phone proficiency shows increased BMI in the elderly. This study suggests that people over the age of 60 who have high smartphone proficiency should be cautious of an increased BMI score.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.13 no.6
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• pp.562-567
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• 2020

In this paper, this is a study on the correction of protection relays to monitor temporary power facilities for storage tanks especially transformers to block and protect faults such as insulation breakdown. When an abnormality such as a short circuit or a ground fault occurs in the power system, it is important to detect this quickly cut off the device and equipment in which the fault occurred and separate it from the power system to correct the protection relay so that it does not interfere with power supply. In addition the fault current calculation that accurately applies the fault type and the cause of the fault for protection cooperation will be the most important factor in the correction of the protection relay. For protection coordination a study was conducted on the method of coordination for protection of power facility protection for storage tanks such as over current relay, ground over current relay, under voltage relay, and ground over voltage relay applied to temporary.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.4
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• pp.93-102
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• 2018

This paper reports a Surge Protective Device (SPD) that is used to protect an automatic metering interface (AMI) power supplies of communication equipment on a low-voltage distribution system from a lightning current. The surge protective device (SPD) can be classified as one-port SPDs and two-port SPDs with decoupling elements depending on the connection type. The protection of internal systems against the lightning current may require a systematic approach consisting of coordinated SPDs. To deal with this, the definition of a lightning protection zone (LPZ) was studied and interpreted through a theoretical review. Because the lightning current resulting from a lightning surge is considerably high, there is limited protection from one SPD; therefore, coordinated cascaded MOV-based SPDs are installed to solve this problem. Regarding the power grid mentioned in this paper, a class II SPD for the low-voltage distribution system installed on the border of LPZ1 and LPZ2, which establish a protection coordination with the Arrester (LA, SA) that corresponds to the LPZO installed on the MOF stage connected to one system were designed to protect various communication (control) equipment, including the automatic meter reading system inside the branch-type electric supply panel of a building, not the incoming side of one system. In addition, performance-related tests were done by a comparison with the existing method through testing, and the optimal design was achieved for the 1-port SPD that uses a series connection and can bleed load current without any decoupling element.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.4
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• pp.461-466
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• 2016

In this paper, a capsule body shaped surveillance/monitoring device is developed. The device includes a camera and GPS module to transmit live video data and real time GPS coordinates respectively using the Intel Edison module. A control application is developed for the smart phones and tablets to wirelessly view the live video stream and location of the capsule device and also to switch between the multiple capsule devices installed at different locations. The coordination between the developed device and the smart phone / tablet is done using the wireless function of the Intel Edison module.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.39 no.2
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• pp.11-16
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• 2002

In this paper, single-layer white organic light emitting device was fabricated on ITO glass substrate using PVK as host, Bu-PBD as electron transport layer, Nile Red, Coumarin 6, TPB as red, green, blue color fluorescent dyes. The red, green, blue organic light emitting devices were fabricated respectively. After the characteristic analysis of each color device, the white organic light emitting device was fabricated with optimized condition of each color device by spin coating method. we obtained white emission CIE coordination of (0.32, 0.34) and luminescence of 785cd/$m^2$ at driving voltage of 20V with condition of PVK(70wt%), Bu-PBD(30wt%), Nile Red(0.015mol%), Coumarin 6(0.04mol%), TPB(3mol%). 

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.799-802
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• 2007

최근에 웹 기술은 PC를 념어 휴대폰, PDA, 정보가전, 로봇 등 모든 디바이스로 적용이 확대되고 있으며, 웹에 대한 국제 표준을 주도하고 있는 W3C(World Wide Web Consortium)는 2007년 상반기에 유비쿼터스 웹 응용을 위한 표준 개발을 시작하였다. 이를 담당하고 있는 유비쿼터스 웹 응용 워킹그룹은 탁상용 컴퓨터뿐 아니라 사무용품, 가정 매체 기구, 이동 전화, RFID나 바코드를 포함하는 센서나 이펙터(effector) 등의 유비쿼터스 디바이스들이 다양하게 흩어져 있는 환경에서 쉽게 웹 응용 개발을 가능하게 하는 표준 개발을 목표로 한다. 본 워킹그룹의 활동은 크게 가지로 나누어 볼 수 있다. 첫 번째는 디바이스 독립 워킹그룹(Device Independence Working Group)의 활동이 종료됨에 따라 이 워킹그룹에서 완성하지 못한 표준들을 이어받아 마무리 하는 활동이다. 두 번째는 리모트 이벤팅(remote eventing), 디바이스 코디네이션(device coordination) 그리고 의향 기반 이벤트(intent-based events) 등 유비쿼터스 웹 응용을 위해 펼요한 새로운 표준 개발을 하는 것이다. 본 논문에서는 최근에 W3C에 서 추진되고 있는 유비쿼터스 웹에 대한 표준화 동향을 설명한다.