• 폴리머
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• 제26권1호
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• pp.105-112
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• 2002

연구는 electro-active polymer(EAP)의 특성을 가지는 ion-exchange polymer metal composite(IPMC)을 이용하여 지능형 대장내시경 개발에 목적을 두고 있다. IPMC는 낮은 구동전압과 빠른 반응속도로 인하여 매우 매력적인 물질이다. 본 연구에서는 IPMC구동기의 전극을 무전의 도금 방법을 이용하여 용액함침-환원방법(impregnation-reduction method)으로 제조하였으며 코팅된 백금전극의 횟수에 따라 변위와 변화를 측정하였다. 구동특성을 알아보기 위하여 길이, 주파수에 대한 변위, 힘을 측정하였으며, 주파수 대역은 저주파 대역과 공명주파수 대역을 사용하는 것이 적합하다는 결론을 얻었다. 또한 다양한 구동적 특성과 수분의 함량에 따른 영향에 대해 고전적 적층 이론 (classical laminate theory, CLT)을 이용하여 이방성 IPMC의 응력분포와 수분이동에 따른 모멘트, 변형률, 곡률(cuvature)을 모델링 하였다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2005년도 제25회 추계학술대회논문집
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• pp.121-131
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• 2005

고속 수중 어뢰의 추진을 위해 외부에서 공급 받은 물과 증기로 연소 하는 수(水)반응성 연료를 이용하고 있다. 수(水)반응성 연료의 주성분은 마그네슘과 알루미늄처럼 반응성이 큰 금속들을 이용하며, 이 금속들은 수증기와 높은 열량과 함께 로켓 추력 실에서 연소 시킨다. 위 금속들의 연소 속성에 대한 해석은 이미 완료되었다. 수반응성 추진제의 가능성 있는 변형체에 대한 개념들은 수반응성 추진제 설계의 기초적인 제안들을 기하학 및 열역학적 연소 조건을 이용하여 논의 할 것이다.

• 한국재료학회지
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• 제9권2호
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• pp.199-204
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• 1999

As the engine design change to get high efficiency and performance of commercial diesel engine, surface wear of the cam follower becomes an important issues as applied load increasing at the contact face between cam follower and cam. Purpose of this study is the developing of the ceramic cam follower made of silicon nitride ceramic which is more wear resistant than the cast iron and sintered cam follower. Ceramic cam follower was made by direct brazing of thin ceramic disk to steel can follower body using active bracing alloy. Effect of joining condition on the interfacial phases and joining strength wer examined at bvarious joining temperatures, times, and cooling rates. Crowning resulted from the difference of thermal expansion coefficient after direct brazing without using any stress-relieving inter layer was measured. Interfacial phases are mainly titanium silicide and titanium nitride which are the products between active metal(Ti) in brazing alloy and silicon nitiride. Maximum joining strength of the ceramic metal joint, measured by DBS method, was 334MPa. Crowning(R) of the prototype ceramic cam follower was 1595mm. As machining for crowning is not necessary, production cost can be reduced.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2000년도 전력전자학술대회 논문집
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• pp.581-586
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• 2000

Gas metal arc welding(GMAW) uses a continuously fed electrode as a filler metal. The arc is shielded from atmospheric contamination by an inert gas active or inert/active gas mixture delivered through the welding gun and cable assembly. The recent research topics on $CO_2$ are welding machines are focused mainly on the reduction method of generated spatter by using new type consumable electrode metal or inverter control method. The various current waveform control methods have been researched for welding performance improvement. Until now current waveform control methods reduce to spatter occurred by instantaneous short circuiting,. but these methods is drawback that no reduce spatter occurred by arc reignition. In this paper the previous arc reignition current control method for welding performance improvement of inverter arc welding machine is studied and compared the various current control methods with the previous arc reignition current control method.

• 제어로봇시스템학회논문지
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• 제10권11호
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• pp.981-990
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• 2004

Specialized propulsors for naval applications have numerous opportunities in terms of research, design and fabrication of an appropriate propulsor. One of the most important components of any propulsor is the actuator that provides the mode of locomotion. Ionomeric electro-active polymer may offer an attractive solution for locomotion of small propulsors. A common ionomeric electro-active polymer, ionic Polymer-Metal Composites (IPHCs) give large true bending deformations under low driving voltages, operate in aqueous environments, are capable of transduction and are relatively well understood. IPMC fabrication and operation are presented to further elucidate the use of the material for a propulsor. Various materials, including IPMCs, are investigated and a simplified propulsor model is explored.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1989년도 하계종합학술대회 논문집
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• pp.333-334
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• 1989

Electrically active part of the piezoelectric sound element is a ceramic thin circular disk cemented to a metal base plate (using a type of thermosetting epoxy). The active part is a thin lead zirconate titanate disk (PZT). The piezoelectric sound element is so dimensioned that its basic resonance frequency is approximately if the center of the audible frequency band: This frequency is mainly determined by the geometry and the sort of the metal base plate materials. In this study, four kinds of PZT ceramic and two classes of thin metal base plate were prepared. It is observed that dielectric and pizoelectric properties relate to acoustical properties (particularly sound pressure level).

• 전자공학회논문지SC
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• 제49권3호
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• pp.75-81
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• 2012

최근에 소개된 능동 FSS(active frequency selective surface) 또는 ESS(electromagnetic smart screen)는 2차원 금속섬유 복합재료에서 금속섬유의 부하저항을 변화시킴으로써 복합재료의 분산특성을 변경시키는 기술이다. 본 논문에서는 부하저항의 변화에 따른 ESS의 분산특성을 효율적으로 계산하기 위해 GEC(generalized equivalent conductor) 기법을 기반으로 수정하여 적용한다. 부하저항에 따른 ESS의 투과계수와 유효유전율을 1~40 GHz의 범위에서 시뮬레이션 한다. 또한, 부하저항을 변경함으로써 공진주파수와 대역폭을 변경할 수 있음을 보인다.

• Bulletin of the Korean Chemical Society
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• 제30권10호
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• pp.2283-2286
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• 2009

A convenient route for the preparation of water soluble polythiophenes is described. Reactions involving highly active zinc metal show unique properties, viz. tolerance of the ester group and regioselectivity to the thiophene ring. Poly [3-(ethyl-n-alkanoate)thiophene-2,5-diyl]s, poly [3-(n-carboxyalkyl)thiophene-2,5-diyl]s, and poly [3-(potassium- n-alkanoate)thiophene-2,5-diyl]s were easily prepared by utilizing highly active zinc.

• 한국군사과학기술학회지
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• 제11권5호
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• pp.99-106
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• 2008

Metal ions such as Cu and Cr were extracted from the Cu, Cr and Ag impregnated active carbon by contacting the solid surfaces with supercritical carbon dioxide(Sc-$CO_2$) containing chelating agents. About 10g of the active carbon sample were loaded in a vertical tube extractor contacting with $CO_2$ flowing from the bottom of the tube for 6hrs. The ligands used were acetyl acetone(AA) and Cyanex-302(C-302). Water and methanol were used as entrainers to study the effect of co-solvent to $CO_2$. Experimental results showed that C-302 was more effective than AA in removing Cu with the maximum extraction of 42.0wt%, while 57.6wt% of Cr was extracted with AA from the sample.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 춘계학술대회 논문집
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• pp.514-517
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• 2008

Water gas shift(WGS) is an important step in fuel process for fuel cells, and improperness of commercial WGS catalysts for use in fuel cell systems has prompted numerous researches on noble metal catalysts. A selected noble metal catalyst for water gas shift reaction(WGS) was prepared with various metal loadings. The prepared catalysts were tested under two feeding conditions. At moderate residence time, carbon monoxide conversion was much higher on the noble metal catalysts as compared to commercial high-temperature shift catalyst. Effects of metal loading were examined by activity tests at short residence time. Higher metal loading effected higher reaction rate. The kinetic data was fitted to simple reaction equations and effectiveness factor was estimated. The results suggest the necessity of a structural design for the highly active noble metal catalysts.