• 한국실내디자인학회논문집
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• 제25호
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• pp.262-271
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• 2000

Nowadays tiles are widely used as architectual material because of their external beauty, solidity with fire-resisting and water-resisting qualities, and convenience for construction, preservation and repairs. Owing to the improvement of living standard and makers scramble for tile markets, we regard tiles as art and culture. Tiles have been developed with technical improvement, based on mutual relation of material and design. The purpose of the third firing is to create high value added as we show artistic merit and decorative effect. For this reason, researches on new material and design have been carried out widely. I made researches whole process from design to printing by means of computer and experiment with color and vetroza of the third firing. I hope that tile makers will share the achievement of university researchers and this paper will be useful for those who are interested in tiles.

• Journal of Power Electronics
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• 제12권6호
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• pp.925-934
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• 2012

Three-phase controlled converters have many applications in the utility interfacing of renewable energy sources and adjustable speed drives as a rectifier or inverter. The utility line currents of these converters have a high harmonic distortion, which is more than the harmonic standards. This paper introduces a new technique for circulating the third harmonic currents from the dc-link to the line currents to reduce their harmonic contents. The proposed system uses a single-phase PWM converter to control the angle and amplitude of the injection current for each of the firing angle of a three-phase converter. A detailed analysis is introduced to achieve a relationship between the firing angle of the three-phase controlled converter and the power angle of the PWM converter. In addition, a detailed design for the other injection path components is introduced. A simulation and experimental work is introduced to prove the mathematical derivations. Analysis, simulation and experimental results prove the superiority of the proposed technique.

• 한국세라믹학회지
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• 제27권2호
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• pp.179-186
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• 1990

Silicon carbide porous materials used for hot gas filters were prepared using oxide binder. Chamotte, frit and H3PO4 were starting materials to synthesize the oxide binder for high temperature-use. Room temperature bending strength of the silicon carbide porous body was increased with increasing firing temprature or with the amount of the content of frit in the oxide binder. However, in the oxidebinder fired above132$0^{\circ}C$, cristobalite form of AlPO4 phase which undergoes rapid inversion became more prominent with increasing firing time. the average pore size of the silicon carbide filter materials was found to be about one third of the average grain size of the silicon carbide powder used in this study.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2012년도 제38회 춘계학술대회논문집
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• pp.493-497
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• 2012

한국형발사체 3단 엔진에 사용될 7톤급 액체로켓엔진의 연소기의 연소시험을 위해 한국항공우주연구원에 있는 지상연소시험장을 유지 및 운용의 편리성, 유연성, 안전성을 고려하여 개량하였다. 본 논문에서는 개량된 시험 시험설비 주요 변경과 기능에 관하여 서술하였다.

• 품질경영학회지
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• 제43권3호
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• pp.289-298
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• 2015

Purpose: This study examined the problem of crack formation in the fire control system(FCS) of the K11 objective individual combat weapon(OCIW), using design of experiment analysis. Three hypothesis were considered. The first hypothesis is that bolted joint has an effect on impulse caused by firing the weapon and the second hypothesis is that a short time interval of shooting has an effect on impulse and lastly, the third hypothesis is that a positive correlation has between the bolted joint of the FCS and the impulse. Methods: The relationship between the bolted joint and the impulse cause by firing the weapon were examined experimentally. The first and second hypothesis was tested using correlation analysis and the t-test. Results: Using ANOVA, the first null hypothesis was rejected and the alternative hypothesis was accepted. ANONA confirmed the second null hypothesis. Correlation analysis dismissed the last null hypothesis. A positive correlation between the bolted joint and the impulse caused by shooting the weapon was verified. Conclusion: The bolted joint of the K11 FCS and the barrel of the K11 affect the impulse caused by firing the weapon. A positive correlation was established between the bolted joint of the FCS and the impulse on firing the K11 OICW.

• The Journal of Advanced Prosthodontics
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• 제6권6호
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• pp.427-433
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• 2014

PURPOSE. Surface color is one of the main criteria to obtain an ideal esthetic. Many factors such as the type of the material, surface specifications, number of firings, firing temperature and thickness of the porcelain are all important to provide an unchanged surface color in dental ceramics. The aim of this study was to evaluate the color changes in dental ceramics according to the material type and glazing methods, during the multiple firings. MATERIALS AND METHODS. Three different types of dental ceramics (IPS Classical metal ceramic, Empress Esthetic and Empress 2 ceramics) were used in the study. Porcelains were evaluated under five main groups according to glaze and natural glaze methods. Color changes (${\Delta}E$) and changes in color parameters (${\Delta}L$, ${\Delta}a$, ${\Delta}b$) were determined using colorimeter during the control, the first, third, fifth, and seventh firings. The statistical analysis of the results was performed using ANOVA and Tukey test. RESULTS. The color changes which occurred upon material-method-firing interaction were statistically significant (P<.05). ${\Delta}E$, ${\Delta}L$, ${\Delta}a$ and ${\Delta}b$ values also demonstrated a negative trend. The MC-G group was less affected in terms of color changes compared to other groups. In all-ceramic specimens, the surface color was significantly affected by multiple firings. CONCLUSION. Firing detrimentally affected the structure of the porcelain surface and hence caused fading of the color and prominence of yellow and red characters. Compressible all-ceramics were remarkably affected by repeated firings due to their crystalline structure.

• 터널과지하공간
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• 제8권1호
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• pp.8-16
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• 1998

The first purpose of this study is to verify the application of computer modelling to a enclosed space fire. The second one is to determine temperature distribution for the three different ventilation types in case of a enclosed space fire. The third one is to find out the ventilation direction and ventilation quantity to remove effectively heat and combustion products generated by a fire in variable air volume(VAV) system. Firstly, compared with experimental results of Lawrence Livermore National Laboratory(LLNL), numerical results show good agreements. Secondly, among three different ventilation types, the numerical analyses show the highest temperature distribution in occupied zone(up to 1.8 m from bottom) from firing moment to 100 sec. when supply ducts are placed in ceiling and extract duct is placed close to the bottom on side walls. This is due to disadvantageous position of extract duct in ventilating high temperature air which rise because of buoyancy force. Thirdly, this study finds out effective ventilation direction and ventilation quantity to remove heat and combustion products generated by a fire by using VAV system. $CO_2$ concentration is used as a fire fume removal index. As soon as a fire happens, ventilation direction is changed in order to gather and drive out fire fumes. In case of three times ventilation quantity of ordinary one, $CO_2$ concentration and temperature have begun to decrease at 120 sec. after firing, i.e.fire fumes have begun to be removed.

• Journal of international Conference on Electrical Machines and Systems
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• 제3권3호
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• pp.317-324
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• 2014

The forces involved in the firing of the electromagnetic rail gun may be analyzed from Amperian, Maxwellian and Einsteinian approaches. This paper discusses these different paradigms with regard to rail gun performance modeling relating to the generation and balance of the forces caused by the currents and their induced magnetic fields. Recent experimental work on model rail guns, where the armature is held static, shows very little recoil upon the rails, thereby indicating a possible violation of Newton's Third Law of Motion. Dynamic testing to show this violation, as suggested by the authors in an earlier paper, has inherent technical difficulties. A purpose-built finite element C/C++ simulator that models that suspended rail gun firing action shows a net force acting upon the entire rail gun system. A new effect in physics, universal in scope, is thus indicated: a current circulating in an asymmetric and rigid circuit causes a net force to act upon the circuit for the duration of the current. This conclusion following from computer simulation based upon Maxwellian electrodynamics as opposed to the more modern relativistic quantum electrodynamics needs to be supported by unambiguous experimental validation.

• 보존과학연구
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• 통권23호
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• pp.5-39
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• 2002

The scientific analysis and provenance study of potteries excavated from kiln sites at Jeonla Nam. Buk-do were carried out using XRD,ICP-AES and NAA. We can summarize the following consequence. First, as a result of XRD analysis, it showed that soft potteries consist of quartz, feldspar and clay minerals while hard potteries consist of high temperature crystals such as mullite, tridymite, cristobalite. In case of firing temperature which are determined by crystals using XRD, potteries are composed of quartz, feldspar and clay minerals had very low firing temperature. While potteries having only cristobalite ranged above$1200^{\circ}C$. Second, as a result of correlation analysis using trace element, the selected characteristic elements which was able to distinguish from each kiln site was Ce, Lu, Cs, Sc, Eu. Third, discriminant analytical results showed that kiln site of the Jeonla Namdo were classified into five groups and that of the Jeolna Buk-do into three groups. This suggests that there are no correlations between the raw materials used in each kiln sites.

• 헤리티지:역사와 과학
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• 제37권
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• pp.349-369
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• 2004

20세기에 들어와 컴퓨터의 발달로 문화재를 복원하는데 있어 다양한 자연과학적 방법이 시도되고 있다. 문화재에 적용되는 통계학을 비롯한 자연과학적인 방법을 통해 문화재의 재질에 대한 주성분 및 미량성분을 분석하여 산지추정을 할 수 있고, 더 나아가 고대의 교역 및 교류관계를 규명하고, 생산지와 소비지 사이의 정치 경제 문화관계 등 다양한 정보를 밝혀내고 있어 그 필요성이 더욱 요구되고 있다. 본 연구는 흡수율 및 광물결정분석, 편광현미경분석, 통계분석 등의 자연과학적인 방법을 이용하여 경기도 하남시 천왕사지 유적내 기와 가마로 추정되는 소성유구의 성격과 유구 및 주변 건물지에서 출토된 기와들에 대해 상호관계를 밝히고자 시도되었으며, 연구결과 다음과 같은 결론을 얻었다. 경질 기와 편들을 제외한 연질 기와 편들은 다른 기와에서 볼 수 있는 흡수율(10%이상)과 비슷한 수치를 보였으며, 흡수율이 낮은 일부시료에서는 Mullite, Tridymite, Cristobalite와 같은 고온 결정상 등이 존재하는 것으로 보아 다른 기와편에 비해 소성온도가 높았음을 알 수 있었다. 또한 미량성분을 통한 통계분석결과 소성유구와 천왕사지 내에서 출토된 기와는 한 군으로 분류된 것으로 보아, 밀접한 관련성을 가지고 있음을 알 수 있었고, 천왕사 축조시 원거리에서 기와를 공급받은 것이 아닌 사지 내에 가마를 설치한 후 공급하였음을 알 수 있었다.