• KIEE International Transactions on Power Engineering
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• v.4A no.4
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• pp.201-206
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• 2004

With the advent of distributed generation, power systems in general are impacted in regards to stability and power quality. Distributed generation has positive impacts on system restoration following a fault, higher reliability, and mitigation of effect due to voltage sag. However, distributed generation also has negative impacts on the decrease of reliability such as changes of protective device setting and mal-operation. Because bulk power systems consist of various sources and loads, it is complicated to analyze power systems that have distributed generation. The types of distributed generation usually are classified as the rotating machinery system and the inverter-based system. In this paper, distributed generation is designed as a synchronous generator, and the distribution system with its distributed generation model is simulated using EMTP. In addition, this paper shows the simulation results according to the types of distributed generation

• The Journal of the Korean dental association
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• v.52 no.8
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• pp.472-477
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• 2014

The new paradigm of dentistry require the detection of caries in their earlier stages. To achieve this, a high technology detection device and systematic and organized caries management system are needed. Caries management by risk assessment (CAMBRA) model is representative caries management system that satisfied new paradigm. Dental caries prevention and treatment according to CAMBRA model is patient-centered, risk-based, evidence-based practice. Therefore, individual caries management such as CAMBRA should be performed through accurate assessment of caries disease indicators and comprehensive assessment of caries risk factors and protective factors. Based on the CAMBRA better effectiveness of comprehensive dental caries management including non-surgical treatment will be accomplished.

• Journal of Korean Institute of Industrial Engineers
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• v.18 no.2
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• pp.1-9
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• 1992

The purpose of this paper is to investigate the dynamic situation of the biomechanical responses of a pilot that occur before the black out during high gravity maneuvering. The computer biodynamic simulations using the Articulated Total Body(ATB) model show the following results : 1) the center of gravity(c. g) offsets of a helmet have significant effects on the head deflection angle which is closely connected with the head down : 2) the average and maximum gravity forces are smaller in the curvilinear type of an acceleration than in the straight type of the acceleration, and it is applied to the case of the head deflection angle. We suggest that the new concept of protective device should be necessary to prevent the head down during high gravity maneuvering.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.05a
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• pp.285-288
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• 2009

WAN을 기반으로 하는 초고속 정보통신망이 구축되면서 컴퓨터를 기초로 하는 정보기술에 대한 의존도가 증가하고 있다. 그에 따라 컴퓨터를 비롯한 초고속 정보통신 설비 사고 가운데 뇌 서지에 기인하는 비중이 늘어나고 있다. 정보화 시스템의 일시적 기능 정지나 고장은 그 파급효과가 대단히 크고 경제적 손실이 막대하여 안정적인 서지 보호대책의 필요성이 높아지고 있다. 이에 뇌 보호 관련 규정이 KS C IEC 62305로 개정되면서 선택사항에 불과했던 내부 뇌 보호 시스템인 서지보호기 (Surge Protective Device 이하 SPD)가 필수사항이 되었다. 하지만 약 30%가 SPD 설치 후에도 서지로 인한 피해를 입고 있는 것이 현실이다. 이는 설치 후에도 SPD가 제대로 작동하는지의 동작 상태와 경년에 따른 SPD의 특성 변화를 알 수 없어 문제 발생 시 정확한 원인 분석이 불가능하여 효과적인 대책수립이 어렵기 때문이다. 따라서 기존 SPD 기술의 한계점을 극복하여 유입되는 외부 서지의 특성을 파악하고 고장 예측이 가능한 차세대 뇌서지 보호대책을 고려하여야 한다.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.617-618
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• 2012

Recently as the inactive response characteristics of the existing RCD(Residual Current protective Device) used on low voltage power distribution system, so control of overload and electric short circuit faults, major causes of electrical fires, are not enough. Therefore, this paper is proposed a prevention apparatus using neutral line voltage and semiconductor switching devices for the prevention of electrical disasters in low voltage power distribution system caused by overload or electric short circuit faults. The proposed prevention apparatus confirms the excellent characteristics in response velocity and accuracy in comparison with the conventional circuit breaker(RCD) through various operation performance analysis.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.57 no.4
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• pp.444-450
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• 2008

There are several ways to bond to building grounding systems for reducing GPR(ground potential rise) and EMI resulting from power system faults or lightning stroke to building. In order to verify effective bonding practice, the GPR and voltage of equipment due to the direct stroke to building are calculated with ATP-EMTP model for transformer, transmission line and MOV(Metal oxide varistor). The simulated model shows a satisfactory accuracy compared with experimental result for the $8/20{\mu}s$ simulated current pulse. It is observed that separate grounding can cause dangerous voltage to the building equipment and the performance of surge protective device can improve when it is installed to the protected equipment in distance as short as possible.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.951-953
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• 2005

The current transformer is used for the insulation of measuring instrument, enlargement of measurement scope, standardization of measuring instrument, control of protective device. It's required various performance as the intention of service, site of establishment, insulation. especailly, current transformer has small ratio errors. if current transformer has large ratio error, it's caused a electricity failure. so in this paper, we examine the theory of current transformer, major factor of errors, output performance on over-current.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.252.1-252.1
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• 2013

Hexagonal boron nitride (h-BN) is a two dimensional material which has high band-gap, flatness and inert properties. This properties are used various applications such as dielectric for electronic device, protective coating and ultra violet emitter so on. 1) In this report, we were growing h-BN sheet directly on sapphire 2"wafer. Ammonia borane (H3BNH3) and nickel were deposited on sapphire wafer by evaporate method. We used nickel film as a sub catalyst to make h-BN sheet growth. 2) During annealing process, ammonia borane moved to sapphire surface through the nickel grain boundary. 3) Synthesized h-BN sheet was confirmed by raman spectroscopy (FWHM: ~30cm-1) and layered structure was defined by cross TEM (~10 layer). Also we controlled number of layer by using of different nickel and ammonia borane thickness. This nickel film supported h-BN growth method may propose fully and directly growing on sapphire. And using deposited ammonia borane and nickel films is scalable and controllable the thickness for h-BN layer number controlling.

• Vacuum Magazine
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• v.3 no.3
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• pp.19-23
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• 2016

BNNTs (Boron nitride nanotubes) is an analogue of CNTs (Carbon Nanotubes) in terms of lattice structure. In BNNTs, a boron atom forms sp2 hybridized bonding with three nitrogen atoms, and so does a nitrogen with three boron atoms in the honeycomb structure. Its innovative properties, such as high thermal conductivity, neutron shielding capability, superb oxidation resistance at $900^{\circ}C$, excellent chemical resistance, and superior mechanical properties are advantageous for a wide range of applications, especially for electric device packages, neutron shielding, protective coating materials, and functional composites. In this paper, boron nitride nanotube synthesis, properties and application are reviewed.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.236-237
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• 2021

In the waterproofing of the rooftop of reinforced concrete buildings, it is difficult to solve perfectly according to the proficiency of waterproofing materials, methods, and mechanics. Therefore, this study applies a Tricot Fabric Mesh to the behavior of the bottom concrete. In addition, it responds to the behavior of the concrete cracking, and the waterproofing and protective layer has developed a method to provide convenience for rooftop floor use by adhesion between the base and the waterproof layer with the use of high viscosity urethane to effectively move the surface deformation and surface vapor and install a airvent device on the wall.