• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 C
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• pp.1778-1780
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• 2004

Microwave heating system of KSTAR consists of ECH and LHCD. ECH and LHCD offer the reliability of operation in the beginning of plasma formation and non-inductive current drive for long time steady state operation with maintaining MHD stability, respectively. LHCD demands 5 GHz of frequency and consists of c-band waveguide, 4-port circuitor, dry dummy load, dual directional coupler, E-bend, arc detector. Our system is a lineup type pulse modulator that has 45 kV of output pulse voltage, 90 A of pulse current, 4 us of pulse width. 1:4 step-up pulse transformer, 7 stages of PFN and thyratron tube (E2V, CX1191D) are used in this modulator. The purpose of this paper is to show the modulator design and experimental result.

• 대한기계학회논문집A
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• 제26권11호
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• pp.2297-2304
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• 2002

Two-dimensional and three-dimensional finite element methods have been used to analyze the deformation behavior of a shadow mask due to thermal and tension load. The shadow mask inside the Braun tube of a TV set has numerous slits through which the electron beams are guided to land on the designed phosphor of red, green or blue. Its thermal deformation therefore causes landing shift of the electron beam and results in decolorization of a screen. For the realistic finite element analysis, the effective thermal conductivity and the effective elastic modulus arc calculated, and then the shadow mask is modeled as shell without slits. Next a transient thermal analysis of the shadow mask is performed, wherein thermal radiation is a major heat transfer mechanism. Analysis of the resulting thermal deformation is followed, from which the landing shift of the electron beam is obtained. The present finite element scheme may be efficiently used to reduce thermal deformation of a shadow mask and in developing prototypes of a large screen flat TV.

• Journal of Astronomy and Space Sciences
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• 제29권1호
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• pp.79-84
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• 2012

After a visit by Peter Waddell from the University of Strathclyde, Glasgow, UK in 1991, Robert H. Koch launched a program at the University of Pennsylvania to build lightweight pneumatic membrane mirrors, initially for balloon flight observations where weight is at a premium. Mirror cells were fabricated from sizes 0.18 m to 1.77 m, and experiments conducted to characterize the mirror figure and stability. Most of the work stopped after Prof. Koch's retirement in 1996 until 2006 when the authors expressed an interest in building an array of medium-aperture portable telescopes. The program restarted in earnest at Gravic, Inc. in Malvern, PA in 2008 with Koch using his extensive observational astronomy experience to guide the fabrication of a fully operational 1.07 m membrane mirror telescope with an optical tube assembly weighing under 45 Kg. Residual wavefront aberrations remediation resulted in Koch and the authors investigating membrane tensioning techniques with different cell designs, active secondary wavefront correction, photometric algorithms for aberrated images, and the use of additional lightweight mirror substrates from the Alt-Az Initiative Group, such as foamed glass. The best result for the lightweight mirrors was a point spread function spot size of several arc seconds. A lightweight 1.6 m cast aluminum cell alt-az telescope was subsequently designed by Koch and the authors for prime focus use.

• 한국전기전자재료학회논문지
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• 제24권1호
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• pp.76-80
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• 2011

The ITO/Cabon Nano Tube (CNT) nano composites were deposited by nano cluster deposition (ITO) and arc discharge deposition (CNT) on glass substrates. The structural, optical and photovoltaic performance of ITO/CNT nano composites as a counter electrode of dye-sensitized solar-cells (DSSCs) such films were investigated. At low temperature below $250^{\circ}C$, the ITO films deposited on CNT. The ITO/CNT nano composit showed a good optical and electrical property for the counter electrode of DSSCs. When the as-prepared ITO/CNT nano composites are used for the counter electrodes, the photovoltaic parameters are $V_{OC}$ = 0.69 V, $J_{SC}$ = 5.69 mA/$cm^2$, FF = 0.32, and $\eta$ = 0.53 %. The ITO/CNT nano composites showed the possibility for the counter electrode applications of DSSCs.

• 대한기계학회논문집A
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• 제27권3호
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• pp.381-386
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• 2003

Gradually engineering designers are determined based on computer simulations. Modeling of the computer simulation however is too expensive and time consuming in a complicate system. Thus, designers often use approximation models called metamodels, which represent approximately the relations between design and response variables. There arc general metamodels such as response surface model and kriging metamodel. Response surface model is easy to obtain and provides explicit function. but it is not suitable for highly nonlinear and large scaled problems. For complicate case, we may use kriging model that employs an interpolation scheme developed in the fields of spatial statistics and geostatistics. This class of into interpolating model has flexibility to model response data with multiple local extreme. In this study. metamodeling techniques are adopted to carry out the shape optimization of a funnel of Cathode Ray Tube. which finds the shape minimizing the local maximum principal stress Optimum designs using two metamodels are compared and proper metamodel is recommended based on this research.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2002년도 Proceedings
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• pp.379-381
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• 2002

A single CdZnTe detector is tested for suitability in a prototype CT/ SPECT system designed to acquire both emission and transmission data. The detector has the size of 1${\times}$l-cm$^2$ with 4${\times}$4 1.5${\times}$l.5mm$^2$ pixellated anodes. Since the detector is smaller than imaged object, we translated it in an arc centered at the x-ray tube to image larger objects. Pulse counting electronics with very short shaping time (50 ns) are used to satisfy high photon rates in x-ray imaging, and response linearity up to 3${\times}$10$\^$5/ counts per second per detector element is achieved. The energy resolution of 122-keV gamma-ray is measured to be 14%. We have characterized the system performance by scanning a radiographic resolution phantom .and the Hoffman brain phantom. The spatial resolution of CT and SPECT are about 1 mm and 7 mm, respectively.

• 조명전기설비학회논문지
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• 제18권3호
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• pp.7-14
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• 2004

현재까지 HID 램프는 광원이 가진 많은 장점에도 불구하고, 고온 순시 재 점등과 음향 공명 현상으로 인해서 실내 광원으로서의 사용이 제한되어왔다. 하지만 많은 연구를 통해서 램프가 뜨거운 상태에서도 순시 재 점등이 가능한 방법이 제시되어 왔고, 실제로 사용되어지고 있다. 하지만 이러한 방법은 램프 상태와 무관하게 200[kV] 정도의 전압을 램프에 인가하는 방법으로, 일반적으로 램프 수명이 감소하는 특징을 가지고 있다. 그러므로 순시 재 점등과 수명 문제는 중요한 연구대상으로 인식되어왔다. 본 논문에서는 램프가 차가운 상태에 필요한 점화 전압과 램프가 뜨거운 상태에서 점등에 필요한 점화 전압을 발생시키는 독립적인 2개의 점화기를 사용함으로써, 램프 상태에 따라 각기 다른 점화 전압을 램프에 인가하는 방법을 제안하고자 한다.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2008년도 춘계학술대회 논문집
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• pp.121-125
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• 2008

최근들어 메탈핼라이드램프의 아크튜브에 사용되던 석영관을 내열성 및 내식성이 우수한 alumina ceramic 재질의 아크튜브에 교체한 세라믹 메탈핼라이드램프가 개발되었다. 이러한 세라믹 메탈핼라이드램프는 기존 석영관 메탈핼라이드램프에 비해 고효율, 고연색성 및 장수명 등 우수한 특성을 가지고 있어 램프의 compact화를 통해 150W이하의 옥내 상업용 조명시설에 급속한 보급이 이루어지고 있으며 국내에서도 이러한 세라믹 메탈핼라이드램프 개발을 위한 연구가 진행 중이다. 이에 본 논문에서는 국내 세라믹 메탈핼라이트램프(Ceramic Metal Halide lamp)의 개발에 필요한 국외 선진 제품에 대한 특성 DB구축을 위하여 150W급 세라믹 메탈핼라이드램프의 아크튜브 구조 및 치수를 측정하고 weibull++6을 이용한 성능열화데이터 분석을 통해 세라믹 메탈핼라이드램프의 수명을 예측해 보았다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 C
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• pp.1628-1630
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• 2002

In this paper, we measured 3-dimensional temporal behavior of the light emitted from discharge cell of plasma display panel(PDP) as a function of the pressure using the scanned point detecting system. The detected light signal through the PM tube is sent on the oscilloscope and oscilloscope which is connected to PC with GPIB. The whole system is controlled by a PC. From the temporal behavior results, we could analyze the discharge behavior of panel with Ne-Xe(4%) mixing gas and 300torr, 400torr, 500torr pressure. The top view of panel shows that the discharge moves from inner edge of cathode electrode to outer cathode electrode forming arc type. At the 300torr, initial emission time is very fast. The side view of panel shows that the light is detected up to $150{\mu}m$ height of barrier rib. In the panel of 300torr, emission distribution is wider than the others.

• 한국초등과학교육학회지:초등과학교육
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• 제18권1호
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• pp.65-73
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• 1999

The purpose of this study is tile development of tile observation Assessment criteria that is used to assess manipulative skills in elementary science. The procedures of developing observation Assessment criteria are as follows. First, we investigated the actual condition about science process skills assessment with tile questionnaire. Second, we selected 7 experimental apparatus through the analysis of the science textbooks. The selected experimental apparatus are dropper, alcohol lamp, thermometer, test tube, filtering device, able balance, graduated cylinder Third, the observation Assessment criteria arc developed through tile analysis of the related experimental textbooks, the demonstrations, and the questionnaire, Forth, tile validity is verified by science education specialists and graduate students who major in science education. Fifth, the first jilter-rater agreement is investigated in the result of the field with observation criteria of which the validity was verified. The second inter-rater agreement is investigated through the revision and the addition of the criteria with the low agreement. In result, the jilter-rater agreement ranged from 0.86 to 0.98. One of the major problems in observation assessment is the rater's subjective viewpoint. So, this research shows a more specified scale and criteria for the assessment. This suggests that the observation Assessment criteria developed in tile study satisfies the high reliability and validity requirements. Considering the results, this criteria call be used effectively for assessing manipulative skills of elementary school students.