• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2011.05a
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• pp.80-80
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• 2011

세계 기후 변화와 불안정한 유가 변화에 대응하고 국내산업의 저탄소 녹색성장을 위해 신재생에너지 개발이 활발하게 이루어지고 있다. 해양에너지 중에서 조류발전은 대규모 댐을 건설할 필요가 없어 비용이 적게 소요되고 특히 날씨 변화나 계절에 관계가 없고, 발전량이 예측 가능하므로 신뢰성 있는 에너지원으로 적용이 가능하다. 조류발전기 블레이드에 폴리머계 복합재료와 스테인리스강이 대부분인데, 이 재료는 특정 회사에서만 제작 가능하며, 충격에 약하고, 균열전파 속도가 빠르며, 대단히 고가이며, 수입에 의존하고 있는 실정이다. 이러한 조류발전에 사용되는 블레이드는 가혹한 부식, 캐비테이션 그리고 침식환경에 노출되어 있어 내구성이 우수한 제품개발이 대단히 중요하며, 조류발전 블레이드를 동합금으로 제작시, 내식성이 뛰어나며 구리의 특성상 해양생물 서식을 방지할 수 있고, 내캐비테이션 특성, 내구성, 가공성 및 유지보수가 용이한 장점이 있다. 이러한 동합금에 WC-27NiCr와 WC-10Co4Cr를 초고속 화염용사(HVOF)를 이용하여 코팅층의 캐비테이션 특성 및 전기화학적 거동을 연구하였다. 본 연구에서는 조류발전용 블레이드의 재료로 사용하려는 동합금에 WC-27NiCr와 WC-10Co4Cr이 용사코팅된 시험편을 사용하였다. 다채널 부식시험기인 WonA-tech WMPG-1000을 이용하여, 자연전위를 측정하였으며, 분극실험은 자체 제작한 홀더를 사용하여 $0.3318cm^2$를 노출 시켜 실험하였다. 기준전극은 은/염화은 전극을, 대극은 백금 전극을 사용하였다. 양분극과 음분극 실험을 통해 개로전위에서의 부식거동을 확인하였고, 정전위 실험도 실시하였다. 실험 종료 후 3D현미경 및 전자주사현미경(SEM)을 사용하여 코팅층 표면의 손상거동을 관찰하였다. 캐비테이션 실험은 ASTM-G32 규정에 의거하여 압전효과를 용한 진동발생 장치(RB 111-CE)를 사용하였다. 수조는 전기화학적 부식의 영향을 고려하여 아크릴로 제작하였고, 시험편은 실험장비에 맞게 파인커팅머신을 이용하여 $20mm{\times}20mm$로 절단하여 사용하였으며 혼과 대향하도록 하여 1mm 간격을 두어 실험하였다. 실험 실시 전, 미소전자저울을 사용하여 무게감소량을 측정하였으며 표면관찰을 통하여 캐비테이션 거동을 관찰하였다.

• Science of Emotion and Sensibility
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• v.17 no.3
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• pp.75-82
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• 2014

This study investigated the physical properties of aramid/nylon ATY and aramid ATY for protective garments according to the aramid and nylon characteristics fed on the core and effect components of air jet texturing equipment. Tenacity decrease of aramid ATY was much more higher than that of nylon ATY because of slick of aramid filament surface. Tenacity of aramid/nylon ATY was most affected by the tenacity of nylon on the effect component of ATY. Breaking strain of nylon ATY was two times higher than that of nylon before air jet texturing, then, in case of aramid ATY and aramid/nylon ATY, were 5.9-6.7 times higher than those before air jet texturing. Initial modulus decrease of aramid ATY showed 86.5% of initial modulus of aramid before air jet texturing, then aramid/nylon hibrid ATY showed arithmetic average value of initial modulus of aramid and nylon ATY. Wet and dry thermal shrinkages of aramid/nylon hybrid ATY were dominated by those of nylon filament on the effect component of ATY.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.124-124
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• 2000

다이아몬드에 버금가는 높은 경도뿐만 아니라 높은 화학적 안정성 및 열전도성 등 우수한 물리화학적 특성을 가진 입방정 질화붕소(cubic boron nitride)는 마찰.마모, 전자, 광학 등의 여러 분야에서의 산업적 응용이 크게 기대되는 재료이다. 특히 탄화물형성원소에 대해 안정하여 철계금속의 가공을 위한 공구재료로의 응용 또한 크게 기대된다. 이 때문에 각종의 PVD, CVD 공정을 이용하여 c-BN 박막의 합성에 대한 연구가 광범위하게 진행되어 많은 성공사례들이 보고되고 있다. 그러나 c-BN 박막의 유용성에도 불구하고 아직 실제적인 응용이 이루어지지 못한 것은 c-BN 박막의 증착직후 급격한 박리현상 때문이다. 본 연구에서는 평행자기장을 부가한 ME-ARE(Magnetically Enhanced Activated Reactive Evaporation)법을 이용한 c-BN 박막의 합성에서 적용한 증착공정 인자들의 변화에 따른 박리특성 고찰과 함께 다층박막화 및 제 3원소 혼입 방법을 적용하여 박리특성 향상 정도를 조사하였다. BN 박막합성은 전자총에 의해 증발된 보론과 (질소+아르곤) 플라즈마의 활성화반응증착(Activated Reactive Evaporation)에 의해 이루어졌다. 기존의 ARE 장치와 달리 열음극(got cathode)과 양극(anode) 사이에 평행자기장을 부가하여 플라즈마의 증대시켜 반응효율을 높였다. 합성실험용 모재로는 p-type으로 도핑된 (100) Si웨이퍼를 30$\times$40mmzmrl로 절단 후, 10%로 희석된 완충불산용액에 10분간 침적하여 표면의 산화층을 제거한 후 사용하였다. 박막실험실에서의 주요공정변수는 기판바이어스 전압, discharge 전류, Ar/N2가스유량비이었다. 합성된 박막의 결정성 분석을 FTIR을 이용하였으며, BN 박막의상 및 미세구조관찰을 위해 투과전자현미경(TEM;Philips EM400T) 분석을 병행하였고, 박막의 기계적 물성 평가를 위해 미소경도를 측정하였다. 박리특성의 고찰은 대기중에서의 자발적 박리가 일어나 90%이상의 박리가 진행된 시점까지의 시간을 측정하였고, 증착직후 박막의 잔류응력 변화와 연관하여 고찰해 보았다.

• Industry Promotion Research
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• v.4 no.2
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• pp.1-8
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• 2019

This research is a technology for cutting the insulation of the busbar (busbar) installed in the distribution panel or switchboard, the results of the study, first, the cutting unit and frame of the cutting unit including a housing attached to the upper and lower cutters, respectively Busbar coating laser cutting machine is installed on the top, characterized by consisting of a stopper for adjusting the coating cutting distance of the busbar. Second, the frame is installed with the guide bar in the longitudinal direction at the top so as to be located at the rear side end of the table, the post is installed vertically at the front and rear at the upper middle part, respectively, and cut to the table at the outer side of the front post. It is characterized by the formation of holes. Third, the supporter is fixedly installed on the upper part of the guide bar arranged in the frame, and is characterized by consisting of a cylinder and a support plate. The meaning of this study is to prevent the safety accidents of workers, to improve the efficiency of cutting work, and to prevent the occurrence of scratches on the surface of the busbar.

• Journal of the Korean Society of Propulsion Engineers
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• v.26 no.1
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• pp.1-11
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• 2022

In a gas turbine, fuel is exposed to a high temperature environment until it is fed to the combustor through the injector. Hydrocarbon fuels can coke under high temperature conditions, which can cause coking material to deposit on fuel lines or block the injector passages. In this study, a specimen simulating a fuel line located inside a gas turbine and Jet A-1 were heated using electric devices. Jet A-1 coking tests were performed by changing the wall temperature of the stainless steel specimen and the temperature of Jet A-1 supplied to the specimen. After the coked specimens were cut, the coking material and the inner surface were analyzed using an energy dispersive X-ray spectrometer and a field emission scanning electron microscope.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.5
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• pp.430-436
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• 2014

The mission objective of STEP Cube Lab. (Cube Laboratory for Space Technology Experimental Project) classified as a pico-class satellite is to verify the technical effectiveness of payloads such as variable emittance radiator, SMA washer, oscillating heat pipe and MEMS based solid propellant thruster researched at domestic universities. In addition, the MEMS concentrating photovoltaic power system and the non-explosive holding and separation mechanism with the advantages of high constraint force and low shock level will be developed as the primary payloads for on-orbit verification. In this study, the feasibility of the mission actualization has been confirmed by the preliminary system design.

• Journal of the korean academy of Pediatric Dentistry
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• v.38 no.3
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• pp.284-289
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• 2011

Lesch-Nyhan syndrome is a disease caused by metabolic disorder of purine. General muscle stiffness and hyposomia are shown from infancy and symptoms can include involuntary or irregular movements of arms and legs, mental retardation, and compulsive self-mutilating behaviors. Self-mutilating behaviors begin at approximately the first year or sometimes at late teens. The patients bite their lips, especially lower lip, tongue, buccal mucosa, hands and fingers. Tongue and lips can be injured or mutilated in severe cases. As the patient gets older, self-mutilating behaviors become more serious and extensive and secondary infection of injured areas is possible. Periodic soft tissue damage due to self-mutilating may evolve to cancer. Medical treatment, appliance treatment, extraction of tooth and surgical operation was attempted to control self-mutilaing behaviors. We hereby report the case of child Lesch-Nyhan syndrome patient who has self-inflicted labial damage as chief complaint. When patient was treated with conservate therapy, such as removable or fixed appliance, the frequency of labial damage could be subdued and yielded favorable results.

• Applied Microscopy
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• v.40 no.4
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• pp.177-183
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• 2010

A focused ion beam (FIB) system produces a beam of positive ions (usually gallium) which are heavier than electrons and can be focused by electrostatic lenses into a spot on the specimen. With its ability milling of the specimen material by 10 to 100 nm with each pass of the beam, FIB is widely adopted in materials science, semiconductor industry, and ceramics research. Recently, FIB has been increasingly employed in the field of biomedical sciences. Here we provide a brief introduction to FIB and its applications for a wide variety of biomedical research. The surface of specimen can be in situ processed and quasi-real time visualized by two beam combination of FIB and field emission scanning electron microscope (FESEM). Due to its milling process, internal structures can be exposed and analyzed: yeast cells, fungus-inoculated wheat leaf, mannitol particles in inhalation aerosols, and oyster shell. Serial blockface tomography with the system kindles 3-dimensional reconstruction researches in the realm of nervous system and life sciences. Two-beam system of FIB/FESEM is a versatile tool to be utilized in the biomedical sciences, especially in 3-dimensional reconstruction studies.

• Journal of the korean academy of Pediatric Dentistry
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• v.32 no.2
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• pp.244-250
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• 2005

Self-injurious behavior is defined as deliberated harm to one's own body without suicidal intent. It usually occurs as head banging or hitting, body hitting, skin cutting, or finger biting and includes ocular, genital, and self-inflicted oral mutilation. Self-injurious behavior can occur with mental retardation, coma, psychotic problem, poisoning, or character disorders. In pediatric patients, self-injurious behavior usually is reported to lip, cheek and tongue biting, and many kinds of dental management methods have been introduced to prevent self-injurious behavior patients from self biting. This report presents two self-inflicted oral mutilation patients who were all treated successfully with appliances such as modified activator without wire for retention, modified tongue-rake appliance and mouth guard.

• Korean Journal of Crystallography
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• v.4 no.2
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• pp.74-85
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• 1993

Single crystals of LiNbO3 have found extensive application in electro-optic and nonlinear optic devices. However, laser-induced refartive index inhomogeneities, which have been labeled opical damage impose limits on device optical damage in LiNbO3 is imporved if more than 4.5 rml% MgO is added to the melt The laser damage thrueshold increased as much as 100 times better then that of undoped crystals. The MgO doped cystal has thus been urterlsiv81y studied since then. In the study, Mgo:LiNbOs(MLA) single crystals dopsd with 0, 2.5, 5.0, 7.5, 10.0 mol% MgO have been grown by the czocrualski technique. The metls were prepared in the platinum crluible and 15∼20mm diameter crystals were grown with a length of 20∼30mm in a resitance heater. The growth rate was 2.5mm/hr, the rotation speed 15rpn. Before sawing MLN single crystals were annealed for 24 hours under atmosphere at a temperature of 1080℃. After sawing, we have found an annual ring cross section of MNA crystals only in the direction of perpendicilar to the c-axis. Nonuniform dispusion of MgO was pointed out that the cuties of the state of oxide were strongly affected by oxygen partial pressure in.