• Journal of the Korean Ceramic Society
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• v.38 no.4
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• pp.325-330
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• 2001

고상반응법으로 이론 밀도의 약 97%의 소결 밀도를 갖는 N $d_{1-x}$S $r_{x}$G $a_{1-x}$M $g_{x}$ $O_{3{\delta}}$(x=0, 0.03, 0.07, 0.1) 고체전해질을 제조하였다. X선 회절 분석 결과, x=0.03일 때의 X선 회절도는 순수한 NdGa $O_3$와 같았으나, x=0.07, 0.1일 때에는 불순물이 나타났다. 교류 복소임피던스는 4$50^{\circ}C$~90$0^{\circ}C$의 온도 범위에서 공기 중에서 측정하였으며, 각 조성에 대하여 상호 비교 분석하기 위하여 복소비저항 스펙트럼으로 변환하여 해석하였다. 전기전도도는 N $d_{0.93}$S $r_{0.07}$G $a_{0.93}$M $g_{0.07}$ $O_{0.97}$(x=0.07) 시편이 90$0^{\circ}C$에서 6$\times$$10^{-3}$ S$cm^{-1}$ /로 가장 우수하였으며, 활성화 에너지는 저온 영역에서는 1 eV, 고온 영역에서는 0.74 eV이었다.다.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.7 no.4
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• pp.654-666
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• 1995

R502 has been extensively used as a working fluid in transport refrigerating vehicles and low temperature refrigerating machines but is to be phased out by the end of 1995 due to ozone layer depletion problem. In this study, both theoretical cycle analysis and experiments were carried out to examine the best substitutes for R502. Theoretical results indicate that the alternatives available in the market today may replace R502 without significant changes in the system without suction line heat exchanger(SLHX). When the system contains a SLHX, however, COPs of the alternatives increase up to approximately 15~20% than those without the SLHX. But simultaneously, the discharge temperatures of the compressor also increrease significantly with the SLHX. Actual test results obtained from the experiment with a transport vehicle's refrigerator indicate the similar trend as those of the theoretical results. Especially, HFCs and their mixtures show lower discharge temperature than those of R502, which is one of the desirable features. Further research is needed to study the effect of the SLHX on the performance of the real machine as well as on the oil return for reliability of the system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.05a
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• pp.441-444
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• 2018

In this paper, a microstrip antenna for LTE / WiMAX is designed for UWB communication. The proposed antenna is designed for FR-4 (er = 4.3), 29[mm] x 45[mm], and can be used in the LTE frequency band of 1.82[GHz] and the WiMAX frequency band of 3.5[GHz]. Studio 2014 was used. The simulation results show 1.785[dB] at 1.82[GHz] and 1.720[dB] at 3.5[GHz]. S-parameters were also found to be less than -10dB (WSWR2: 1) in the desired frequency band. In order to achieve broadband, miniaturization, low cost and low loss, Width, length, width of transmission line, etc. were calculated. Therefore, it is considered that the applicable antenna can be applied satisfying the desired condition.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.4
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• pp.279-288
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• 2014

Second throat supersonic exhaust diffusers (STEDs) were designed to simulate high-altitude conditions according to the normal-shock model. Experimental studies were performed on the STEDs to investigate how performance characteristics varied with the length and diameter of the STED using high-pressure nitrogen gas. The variation in performance due to length indicated that the performance of the STED could be very slightly improved by adjusting the diffuser inlet length ($L_d$), and it could be significantly improved by optimizing the second throat length ratio ($L_{st}/D_{st}$) and the divergence length ($L_s$). The starting and vacuum chamber pressures exhibited the highest level of performance near ($A_d/A_{st}$) of the design point.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1999.11a
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• pp.390-394
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• 1999

In this paper, we have evaluated BER performance of digital subscriber line(DSL) using the twisted-pair channel model by means of Semi-analytic simulation technique. As a result, it was known that the Semi-analytic simulation was proved to be a good technique because of the attenuation of 0.5dB. To keep the BER=10$\^$-7/, 4dB of E$\^$b//N$\^$0/ is needed more when the DSL length extends to 5000m, while 2dB increase of E$\^$b//N$\^$0/ is required when Nyquist frequency goes to 512kb/s with the keeping same distance. In addition, the effect by FEXT noise is serious, when the FEXT noise damping constant, k is over 10/sup-10/ in DSL length and 10$\^$-14/ in the aspect of Nyquist frequency. As the basic, results of this analysis can be used in setting in internal and external standardization of DSL system in the future.

• Proceedings of the Technology Innovation Conference
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• 1996.12a
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• pp.241-264
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• 1996

This article introduces the five functions of the national innovation system (NIS). As the national innovation system is a kind of social systems in the national level, the five generic functions of open system-production boundary spanning, maintenance, adaptation management functions-are applied to the NIS. The production function is the primary process, which produces innovative products and services of the NIS. The boundary spanning function is the function of procuring the input and disposing the innovation output or aiding in these process. Experienced R&D human resources, R&D funds, technology etc. belong to the input of the NIS. The maintenance function is responsible for the smooth operation and upkeep of the system in terms of various conditions. The adaptive function is to help the system change and adapt, scan the environment for problems, opportunities, and technological developments. It faces outward for the survival of the system from the long-term view. The management function carries out planning and controlling the overall activities for the other four functions in order to run the system. Finally it discuses implications for the diagnosis and the decision making process of S&T policy.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.8
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• pp.38-43
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• 1998

An analytical model for the surface field distribution of the RESURF (reduced surface field)LD(lateral double-diffused) MOS is presented in terms of the doping concentration, the thickness of the n epi layer, the p substrate concentration, and the epi layer length. The reuslts are used to determine the breakdown voltage due to the surface field as a function of the epi layer length. The maximum breakdown voltage of the device is found to be that of the vertical n$^{+}$n$^{[-10]}$ p$^{[-10]}$ junction. Analytical results of the breakdown voltage vs. the epi layer length agree well with the numerical simulation results using MEDICI.I.

• Journal of ILASS-Korea
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• v.2 no.1
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• pp.8-17
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• 1997

A study has been carried out on the instability of a conical liquid sheet by using the linear instability theory. Various analytical methods using the Kelvin-Helmholtz instability theory were tried to examine the wave growth on cylindrical liquid sheets. Cylinderical liquid sheets were extended to the case with the conical sheets. Perturbations due to tangential motion as well as longitudinal one were taken into account. And it was assumed the the breakup occurs when amplitude ratio exceeds exp(12), drop sizes were predicted only by theoretical approach. The predicted drop size agreed well with the measured Sauter mean diameter, $D_{32}$.

• Fire Science and Engineering
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• v.16 no.3
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• pp.56-60
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• 2002

Recently, with the growth of software for electro-thermal analysis, it has been studied the precise analysis and investigation of cause for the electrical fire using computer simulation on the basis of theory for electro-thermal analysis. But it is very lacking for the precise analysis and investigation of cause for the electrical fire. In this paper, we have simulated the thermal analysis for electrical wire according to the value of current in a overload and a short with the electrical wire of the L's company product(600 V VVF) using the electro-thermal finite element method(Flux2D).

• Journal of the Korean Society of Clothing and Textiles
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• v.25 no.7
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• pp.1281-1292
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• 2001

This is a study on the dualism of gender through the costume in the Middle Age. Jeanne d'Arc was an existential person in the Hundred Year's war(1338-1453). She persisted in retaining male attire and armour at her own request. One of the points for which she had been condemned was the wearing of male apparel. It was judged as an evil spirit and rendered Jeanne a witch and a heretic therefore she was burned to death in the market place at Rouen, on the 30th May, 1431. It is one of the evidence which represent dualism of gender through the costume.