• 한국전기전자재료학회논문지
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• 제23권10호
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• pp.788-792
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• 2010

The yttrium-barium-copper-oxide (YBCO) coated conductor, which supplement the fault of the existing superconducting current-limit materials YBCO thin film, bismuth-strontium-calcium-copper-oxide(BSCCO) wire and bulk, has been improved its mechanical weakness and has high index; hence, after quench YBCO coated conductor could limit the fault current effectively because of fast resistance occurrence speed. Furthermore, it has wide applicable area as an current limit material because it shows different resistance occurrence tendency by the thickness and kind of stabilization material sputtered on the superconducting layer. Therefore, many researchers are carrying out the study of application of YBCO coated conductor to superconducting fault current limiter (SFCL) for making high quality current limit element, based on resistance type. On the other hand, the study for other type except resistance type has been rarely conducted for the application of YBCO coated conductor to SFCL as an current limit element. Consequently, in this study, YBCO coated conductor with different stabilization layer Cu and Stainless steel, is applied to SFCL using iron core and coil, and examine the many index points as an current limit element, such as current limit characteristic, the tendency of resistance occurrence, response time, the temperature trend for stability.

• 한국가구학회지
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• 제19권6호
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• pp.439-446
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• 2008

High Tech Design manner is a design concept that had been constantly discussed in constitution process of the West art history and modem ideology and had been experimented in industry, having started from futurism and structuralism in the early 20th century through Kinetic Art & Technology Art and up to now. High Tech Design had a great influence also on Post Modernism and more important is that this manner of design will be existing continually in the future too. From the modem times when machine civilization started, the artist and designers expressed a utopia will showing the future world with help of High Tech Design and modem people are realizing technology images as a utopia, in the space and material presented by this high tech design. And this utopia imply the images of dynamic power, speed making a voyage in universe, dream of future, hope, mass production, earth's environment, wealth etc. High Tech furniture was lightly designed by using thin steel wire, structure stressing the metallic characteristic and tempered glass, and it was used for presenting a convenient interior space visually, and with that it can make a unified sense in High Tech interior space, and a contrary effect compared with minimal space. High Tech Design equipped with glass and metal materials looking inappropriate for our interior space due to their sharp and cold image has been regularly used as living furniture, not only decoration function, and then there must be reasons for that. This study intends to research how High Tech Design has been changed and developed in the design history & West art history from the early 20th century, and to present it's value of development as data orienting, namely a direction for the industry of the next-generation and furniture design.

• 한국응용과학기술학회지
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• 제23권2호
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• pp.137-146
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• 2006

We investigated the electrochemical properties for Langmuir-Blodgett (LB) films mixed with fatty acid (8A5H) and phospholipid (DLPE, DMPC, and DPPA). LB films of 8A5H monolayer and 8A5H-phospholipid mixture were deposited using the Langmuir-Blodgett method on the indium tin oxide(ITO) glass. The electrochemical properties measured using cyclic voltammetry with three-electrode system, an Ag/AgCl reference electrode, a platinum wire counter electrode and LB film-coated ITO working electrode at various concentrations(0.1, 0.5, and 1.0 mol/L) of $NaClO_4$ solution. A measuring range was reduced from initial potential to -1350 mV, continuously oxidized to 1650 mV and measured to the initial point. The scan rate was 50, 100, 150 and 200 mV/s, respectively. As a result, LB films of fatty acid and phospholipid (8A5H/DLPE and DPPA) appeared irreversible process were caused by only the reduction current from the cyclic voltammogram and LB film of 8A5H-DMPC mixture was found to be caused by a reversible oxidation-reduction process.

• 대한기계학회논문집B
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• 제25권6호
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• pp.799-803
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• 2001

Miniature heat pipe(MHP) with woven-wired wick was used to cool the CPU of a notebook PC. The pipe with circular cross-section was pressed and bent for packaging the MHP into a notebook PC with very limited compact packaging space. A cross-sectional area of the pipe is reduced about 30% as the MHP with 4mm diameter is pressed to 2mm thickness. In the present study a performance test has been performed in order to review varying of operating performance according to pressed thickness variation and heat dissipation capacity of MHP cooling module that is packaged on a notebook PC. New wick type was considered for overcoming low heat transfer limit when MHP is pressed to thin-plate. The limiting thickness or pressing is shown to be within the range of 2mm∼2.5mm through the performance test with varying the pressing thickness. When the wall thickness of 0.4mm is reduced to 0.25mm for minimizing conductive thermal resistance through the wall of heat pipe, heat transfer limit and thermal resistance of MHP were improved about 10%. In the meantime, it is shown that the thermal resistance and heat transfer limit for the MHP with central wick type are higher than those of MHP with existing wick types. The results of performance test for MHP cooling modules with woven-wired wick to cool a notebook PC shows the stability as cooling system since T(sub)j(Temperature of Processor Junction) satisfy a demand condition of 0∼100$\^{C}$ under 11.5W of CPU heat.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1643-1646
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• 2003

Drawing is a mechanical operation that attenuates thick material to an appropriate thickness for the next processing or end usage. When the input material has the form of a bundle or bundles made of very thin and long shaped wire or fibers, this attenuation operation is called "bundle drawing" or "drafting" Drafting is being used widely in manufacturing staple yarns. which is indispensable for the textile industry. However, the bundle processed by this operation undertake more or less defects in the evenness of linear density. Such irregularities cause many problems not only for the product quality but also for the efficiency of the next successive processes. Since long there have been many researches tying to find out factors affecting the irregularity of linear desity, to obtain optimal drafting conditions, to develop efficient measuring and analysis methods of linear density of bundle, etc., but there exists yet no fundamental equation describing the dynamic behavior of the flowing bundle during processing. In this research a mathematical model for the dynamic behavior of the bundle fluid is to be set up on the basis of general physical lows representing physical variables, i.e. linear density and velocity as the dynamic state of bundle. The conservation of mass and momentum balance was applied to the fluid field of bundle. while the movement of′ individual material was taken into account. The constitutive model relating the surface force and the deformation of bundle was introduced by considering a representative prodedure that stands for the bundle movement. Then a fundamental equations system could be simplified considering a steady state of the process. On the basis of the simplified model, the simulation was performed and the results could be confirmed by the experiments under various conditions.

• 한국진공학회지
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• 제14권3호
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• pp.132-137
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• 2005

국내 유일의 연구용 원자로인 하나로에 중성자 반사율 측정장치를 개발 설치하였다. 하나로 중성자 반사율 측정장치는 수직형 시료 배치를 가지며 입사 중성자 빔의 파장은 $2.459\;\AA$이다. 원자로 출력 24 MW에서 금줄방사화법을 이용하여 측정한 단색기 및 시료위치에서의 중성자속은 각각 $4.5\times10^9\;n/cm^2/sec,\;6.64\times10^6\;n/cm^2/sec4이었다. 또한 하나로 중성자 반사율 측정장치를 이용하여 d-PS, $SiO_2$등의 일부 기준 박막 시료에 대하여 반사율을 측정하고 구조 분석을 수행하였다. 장치 성능 평가 결과 장치 최소 반사율은 $\sim10^{-6}$, 측정 가능한 Q 영역은 $0.003\sim0.3\;\AA^{-1}$이었다.

• 한국태양에너지학회 논문집
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• 제31권6호
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• pp.1-7
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• 2011

Sound waves and acoustic energy generated by two identical TA (ThermoAcoustic) lasers were analyzed and studied. One end of the ceramic stack was heated by a thin NiCr wire wound around that end. The other end of the stack was cooled by natural convection of atmospheric air. The wavelength of the sound waves generated by a single TA laser was four times the tube length and the amplitude of the waves increased with the heating rate. SPL (SoundPressure Level) meters and microphones were employed to measure and study the sound waves at different distances from the glass tube opening and at the focusing point of the TA laser pair for different laser position arrangements. The sound waves of the two TA lasers at the focusing point were found to be almost 180 degrees out of phase when the openings of the two lasers were very close to each other and the angle between the laser axes was small. When the two TA lasers were placed far apart, the sound wave amplitudes and the phase difference between the two laser outputs varied periodically with time. The frequencies of the sound waves changed when the openings of the two TA lasers were in close vicinity and the angle between the laser axes exceeded a certain value. In this case, the glass tube opening was no longer a pressure anti-node and the wavelength of the fundamental mode was not equal to four times the tube length.

• 한국건축시공학회지
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• 제4권1호
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• pp.89-96
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• 2004

Porous concrete is used of various parts by advantage of porous. Example of growing of plant is possible, and dwelling of creature, and filter functions of various contaminant, and decrease of noise, and so on. This research is for porous concretes that were used by four aggregate rubble, refreshing aggregate, expanded clay, orchid stone. This research estimate that physical and mechanical characteristics of fresh concrete and hardened concrete. The purpose of this research is to make environment-friendly porous concrete. This research's conclusion is as following : 1. Porous Concrete's slump was measured 12~14cm with rubble, 12~16cm with refreshing aggregate, 11~13cm with expanded clay, 11~13cm with orchid stone. Weight of aggregate was bigger, slump price appeared by bigger thing. Because placed Porous Concrete is low viscosity and small resistance between aggregate, it estimated that have high workability. 2. Porous Concrete's unit weight was measured 1.71~1.75t/$\textrm{m}^3$ with rubble, 1.58~1.62t/$\textrm{m}^3$ with refreshing aggregate, 1.19~1.20t/$\textrm{m}^3$ with expanded clay, 0.98~1.06t/$\textrm{m}^3$ with orchid stone. Showed aspect such as weight of aggregate. 3. Porous Concrete's compressive strength was measured 76~102kgf/$\textrm{cm}^2$ with rubble, 51~60kgf/$\textrm{cm}^2$ with refreshing aggregate, 30~40kgf/$\textrm{cm}^2$ with expanded clay, 13~16kgf/$\textrm{cm}^2$ with orchid stone. 4. Tendency of tensile strength and bending strength showed generally similarly with compressive strength, but showed low value fewer than 15kgf/$\textrm{cm}^2$ Therefore, wire mesh, reinforcing rod, such as establishment of frame is considered to need in reinforcement about tensility or flexures in case receive tensility or produce product of thin absence form. It concludes by speculating on the consequences of extrapolating the results of study to remodelling the office building being already existence.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.215-216
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• 2007

Semiconducting layers are thin rubber film between electrical cable wire and insulating polymer layers having a volume resistivity of ${\sim}10^2{\Omega}cm$. A new semiconducting material was suggested in this study based on the carbon nanotube(CNT)-reinforced polymer nanocomposites. CNT-reinforced polymer nanocomposites were prepared by solution mixing with various polymer type and dual filler system. The mechanical, thermal and electrical properties were investigated as a function of polymer type and dual filler system based on CNT and carbon black. The volume resistivity of composites was strongly related with the crystallinity of polymer matrix. With decreased crystallinity, the volume resistivity decreased linearly until a critical point, and it remained constant with further decreasing the crystallinity. Dual filler system also affected the volume resistivity. The CNT-reinforced nanocomposite showed the lowest volume resistivity. When a small amount of carbon black(CB) was replaced the CNT, the crystallinity increased considerably leading to a higher volume resistivity.

• 대한기계학회논문집B
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• 제20권6호
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• pp.1931-1940
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• 1996

The effect of periodic passing wake on the film-coolant flow issuing normally from a flat plate was investigated experimentally. The passing wake was generated by rotating thin circular bars. Depending on the rotational direction the test plate could be simulated as a pressure surface or a suction surface of a gas turbine blade. The phase-averaged velocity components were measured using an X-type hot-wire probe. The Reynolds number based on the free-stream velocity and injection hole diameter was 23, 500 and the velocity ratio which is the ratio of film coolant velocity to free-stream velocity was 0.5. The velocity-triangle induced by the wake was similar to that induced by the one generated at the blade trailing edge. The vertical velocity component induced by the passing wake, which approaches to the suction surface and moves away from the pressure surface, played a dominant role in the variation of the flow field. The variation in the phase-averaged velocity on the pressure surface was greater than on the suction surface, but the turbulence kinetic energy variation on the suction surface appeared larger than on the pressure surface.