• Korean Journal of Materials Research
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• v.32 no.3
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• pp.132-138
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• 2022

Zintl phase Mg₃Sb₂ is a promising thermoelectric material in medium to high temperature range due to its low band gap energy and characteristic electron-crystal phonon-glass behavior. P-type Mg₃Sb₂ has conventionally exhibited lower thermoelectric properties compared to its n-type counterparts, which have poor electrical conductivity. To address these problems, a small amount of Sn doping was considered in this alloy system. P-type Mg₃Sb₂ was synthesized by controlled melting, pulverizing, and subsequent vacuum hot pressing (VHP) method. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to investigate phases and microstructure development during the process. Single phase Mg₃Sb₂ was successfully formed when 16 at.% of Mg was excessively added to the system. Nominal compositions of Mg_3.8Sb_2-xSn_x (0 ≤ x ≤ 0.008) were considered in this study. Thermoelectric properties were evaluated in terms of Seebeck coefficient, electrical conductivity, and thermal conductivity. A peak ZT value ≈ 0.32 was found for the specimen Mg_3.8Sb_1.994Sn_0.006 at 873 K, showing an improved ZT value compared to intrinsic one. Transport properties were also evaluated and discussed.

• Proceedings of the KIEE Conference
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• 1999.07g
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• pp.2920-2922
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• 1999

본 논문에서는 유리 용해로의 온도 제어 문제에 있어서, 퍼지 이론의 응용 방식을 제시한다. 유리용해로의 동특성을 분석하고, 이에 적합하도륵 기존 고전적인 제어기와 퍼지 로직을 결합하는 알고리듬을 제시한다. 제시된 제어기는 실제 용해로의 생산공정에 효율적으로 적용되었다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.12
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• pp.1724-1729
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• 2015

Chlorosulfonated polyethylene (CSPE) was not flooded seawater and flooded seawater & freshwater for 5 days, respectively, and these samples are referred to as BSF(before seawater flooding) and ASFF(after seawater & freshwater flooding), respectively. The apparent density, dissipation factor, relative permittivity, melting temperature, dielectric breakdown time and increased time of applied voltage are higher than those of BSF, but the insulating resistance, dielectric strength, percent elongation and glass transition temperature of ASFF are lower than those of BSF. The differential temperature of those is $0.026{\sim}0.028(^{\circ}C)$ after AC and DC voltage is applied to ASFF, respectively, and the differential temperature of those is $0.013{\sim}0.037(^{\circ}C)$ after AC and DC voltage is applied to BSF, respectively. In the case AC and DC voltage is applied to ASFF as well as BSF, the variations in temperature of AC voltage are higher than those of DC voltage. It is investigated that dielectric loss due to dissipation factor ($tan{\delta}$) is related to electric dipole conduction current. It is certain that the ionic (electron or hole) leakage current was increased by conducting ions such as $Na^+$, $Cl^-$, $Mg^{2+}$, $SO_4^{2-}$, $Ca^{2+}$ and $K^+$, those are related to cured atoms of O and S that relatively increased after seawater flooding.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.4
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• pp.532-534
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• 2009

The ceramics superconductor may have a high degree of homogeneity and a more open structure through which atoms can easily diffuse without having to overcome the high activation barrier. Infrared detectors of ceramic superconductor materials have been studied. Ceramic superconductor have smaller reflection coefficient than metal superconductor and therefore infrared light can more easily penetrate into bulks. YBCO thick films show sensitivity of 250 V/W. The accumulation of particles decrease the superconducting energy gap.

• 전기의세계
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• v.22 no.3
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• pp.79-80
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• 1973

This is the abstract of lecture on Electro-optic characteristics of D-KDP crystal and its application for high speed shutter made by Dr. Naomi Furuya; The professor of Yamanashi University in Kofu Japan on March 31, 1973 for KEEI in the auditorium of Korea Electric Company. His lecture is listened by KEEI members that KDP Z-cut crystal can be utilized as a high speed shutter of 10$^{-6}$ second, combining special camera and 2-3KV electrical impulse generator and also recording slide photographs on tungoten lamp crystal voltage and melting fuse phenomena due to over-current taken by this special equipment had been demonstrated.

• Proceedings of the KIEE Conference
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• 2002.07d
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• pp.2507-2509
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• 2002

본 논문에서는 유리 용해로의 온도 제어를 위한 동역학 행렬 제어 (Dynamic Matrix Control, DMC) 기법의 적용 사례를 소개한다. 다양한 제약조건들과 긴 시간지연 응답을 갖는 유리 용해로는 DMC외 좋은 적용 분야가 될 수 있다. 먼저 용해로 테스트를 통하여 입출력 데이터를 생성하고 이를 바탕으로 용해로의 동역학 행렬 모델을 결정한다. 그 후, 모의 실험을 통하여 제어기의 설계변수들을 결정한다. 마지막으로, 제시된 제어기를 실제 용해로 생산 공정에 적용된 결과를 제시한다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.657-658
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• 2005

Flame retard of polymers was studied for prevention from burning by various additives stimulated the char formation during heating and thermal degradation of polymer materials. Forming char have high porosity, low thermal conductivity and act as thermal shield for heat transmission from the flame to the polymer and. oxygen towards the polymer. The results showed that various additives may regulate the processes of intumecsence. The efficient fire protective intumescent char was result of processes of melting, gas evolution, cross-linking, carbonization etc.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.8
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• pp.79-87
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• 2012

Currently, The method to produce a brewing body for dentistry supplementation water produces a brewing body by fabrication, burying and it is heat wish in city gas and oxygen. It uses an original judgment found airplane the brewing body uses a spring of the back wait that melting temperature dissolved various alloys in by a blow pipe, and to generate centrifugal force and produces it. In addition, because it uses preheating to dissolve an alloy in general, it is hard to regulate the appropriate melting temperature of the alloy and brewing time and generates a brewing defect hereby same as gas industry and pinhole and shows the defect of the supplementation thing due to the super-heating. In this paper, We developed the high induction heating system which it could set brewing time,temperature and had durability and security,by the kind of the alloy to produce a high quality prosthetic thing brewing body.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.4
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• pp.149-153
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• 2005

We have investigated thermal properties showed by changing the content of carbon black which is the component parts of semiconductive shield in underground power transmission cable. Specimens were made of sheet with the nine of those for measurement. Heat capacity (${\Delta}$H), glass transition temperature (Tg) and melting temperature (Tm) were measured by DSC (Differential Scanning Calorimetry). The ranges of measurement temperature were from -100($^{\circ}C$) to 100($^{\circ}C$), and heating rate was 4($^{\circ}C$/min). And then thermal diffusivity was measured by LFA 447. The dimension of measurement temperature was 25[$^{\circ}C$]. Glass transition temperature of specimens was showed near -25[$^{\circ}C$] and the heat capacity and the melting temperature from the DSC results were simultaneously decreased according to increasing the content of carbon black, while thermal diffusivity was increased according to increasing the content of carbon black. Because ionic impurities of carbon black having Fe, Co, Mn, Al and Zn are rapidly passed kinetic energy increasing the number of times breaking during the unit time with the near particles according to increasing vibration of particles by the applied heat energy.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.73-76
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• 2004

High-temperature Superconductor(HTS) tubes were fabricated in term of different processing variables such as preheating temperature, speed of mold rotation and cooling rate by centrifugal forming method. For powder melting by induction the optimum range of melting temperatures and preheating temperature were $1050^{\circ}C{\sim}1100^{\circ}C$ and $550^{\circ}C$ for 30min, respectively. The mould roating speed was 1000rpm. A tube was annealed at $840^{\circ}C$ for 72hours in oxygen atmosphere. The plate-like grains were well developed along the roating direction and typical grain size was about more than $40{\mu}m$. It was found that Ic values increased with increasing the preheating temperature and speed of mold rotation. While Ic decreased with increasing the cooling rate. The measured Ic in $50mm{\times}70mm{\times}2.5mm$ tube was about 896Amp.