• 한국초전도ㆍ저온공학회논문지
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• 제7권3호
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• pp.21-28
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• 2005

Superconducting synchronous motors and generators have the field coil composed of superconductor with almost zero resistance at superconducting state. Therefore, copper loss at the conventional field coil is eliminated and the superconducting machine gets higher efficiency. The armature coil of the superconducting machine is composed of copper wire and supported by non-magnetic material such as FRP (Fiber Reinforced Plastic) This paper contains the design Procedure of a 1MW superconducting synchronous motor using high-temperature superconductor only for the field coil. Especially, the armature coil is designed by water-cooling in order to dissipate Joule heat easily. Moreover, 3-dimensional electromagnetic design is conducted to get a proper design result and reduce design errors from 2-dimensional approach.

• Journal of Mechanical Science and Technology
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• 제20권8호
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• pp.1232-1239
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• 2006

In the present study, the unsteady Hartmann flow with heat transfer of a viscous incompressible electrically conducting fluid under the influence of an exponentially decreasing pressure gradient is studied. The parallel plates are assumed to be porous and subjected to a uniform suction from above and injection from below while the fluid is acted upon by an external uniform magnetic field applied perpendicular to the plates. The equations of motion are solved analytically to yield the velocity distributions for both the fluid and dust particles. The energy equations for both the fluid and dust particles including the viscous and Joule dissipation terms, are solved numerically using finite differences to get the temperature distributions.

• 대한전기학회논문지
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• 제37권1호
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• pp.55-62
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• 1988

The variation of electrical resistivity of silver particle-filled polymers with the volume percent of silver particles was investigated. Also, the relationships between the surface tension of polymer and dispersion effect of silver particles were studied to find the steep drop of electrical resisivity, in view of agglomerate morphology. The critical volume precent of silver particles varied depending on the polymer species and increased with the increasing surface tension of polymer. The steep variation of resistivity with the increasing temperature was explained with the expansion of polymer at the melting temperature of polymer. The conductive break down current increased with the increasing volume percent of silver particles in the Ag/LDPE system and that was attributed to heat of Joule taken througn the contact area between the silver particle.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 Techno-Fair 및 추계학술대회 논문집 전기물성,응용부문
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• pp.102-103
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• 2007

Recently, the dependence of the electric energy is increased in accordance with a growth of industry. Therefore, scientific investigation is needed for the security of electrical safety and the judgement of accident causes. Accordingly, this paper consist of the analysis for the carbonization patterns of phenolic resin and the mechanism. As the follows, spider-legs as a carbide are generated around the rods, when the electric current flows on the surface of phenolic resin. The IR absorption peak generated by the thermal effects is appeared at about $1720cm^{-1}$. As the case of Joule's heat, the crystal of a carbide is generated beca use of the rarefied oxygen. It's estimated that the formation of carbonization conductivity as the currents are easily flowed.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.97-98
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• 2007

In this paper, we analyzed the reset current variation of PRAM device with top electrode using the 3-D finite element analysis tool. As thickness of phase change material thin film decreased, reset current caused by phase transition highly increased. Joule's heat which was generated at the contact surface of phase change material and bottom electrode of PRAM was given off through top electrode to which was transferred phase change material. As thermal conductivity of top electrode decreased, heating temperate was increased.

• 한국전기전자재료학회논문지
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• 제20권11호
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• pp.1004-1008
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• 2007

The ice coats are built on 25 kV overhead contact wire when the temperature is lower than $0^{\circ}C$. It generates shockwaves at the mechanical interface of the collecting strips of the pantograph and the contact wire. The de-icing processes should be performed to avoid shockwaves which are generated by a pulsed high-voltage arc discharge. This paper presents temperature analysis of the de-icing effects which could be applied to the overhead contact wire of railways using Joule heat. The results show that 350 A is the proper current for $0^{\circ}C$ conductor according to environmental condition such as velocity of air stream, ambient temperature and moisture.

• International Journal of Railway
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• 제2권4호
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• pp.170-174
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• 2009

Super speed tube train is introduced to increase the speed of ground transportation. The super speed tube train levitates magnetically and runs in a partial vacuum tube, which can reduce the air resistance significantly. However, the strong magnetic force enough to propel the massive train can affect to the tube infrastructure. In this paper, authors have analyzed the leakage flux patterns and induced eddy current on the tube by using 3-dimensional Finite Element Method. These effects are investigated, especially by varying the materials and diameters of the tube. From the simulation results, the aluminum tube with the diameter of 3[m] is needed to be concerned because the induced eddy current produces joule heat, raises the inside temperature of the tube, and might be able to lead to electro-chemical corrosion on the tube, consequently reduce the durability.

• 한국전기전자재료학회논문지
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• 제35권5호
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• pp.452-458
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• 2022

The electro-thermal erasing (ETE) configuration utilizes Joule heating intentionally generated at word-line (WL). The elevated temperature by heat physically removes stored electrons permanently within a very short time. Though the ETE configuration is a promising next generation NAND flash memory candidate, a consideration of power efficiency and erasing speed with respect to device structure and its scaling has not yet been demonstrated. In this context, based on 3-dimensional (3-D) thermal simulations, this paper discusses the impact of device structure and scaling on ETE efficiency. The results are used to produce guidelines for ETEs that will have lower power consumption and faster speed.

• 한국진공학회지
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• 제16권5호
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• pp.388-396
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• 2007

KSTAR (Korea Superconducting Tokamak Advanced Research) 전류인입선(CL; Current Lead)은 4.5 K의 저온에서 운전되는 초전도 버스라인과 300 K의 실온에서 운전되는 MPS (Magnet Power Supply)를 전기적으로 연결하는 장치이다. 초기 플라즈마 발생시험을 위하여 TF (Toroidal Field) 및 PF (Poloidal Field) 리드박스에 전류인입선이 설치된다. TF 자석용 CL은 17.5 kA급 4 개의 CL에 최대 35 kA의 DC 전류가 인가되며, PF 자석용은 13 kA급 14 개의 CL에 350초간 $20\;{\sim}\;26\;kA$의 펄스 전류가 인가된다. 각각의 전류인입선은 TF 및 PF 자석에 전류를 인가하기 위한 버스라인이 연결되어 있으며, 전류인입선을 통해 초전도 버스라인으로 전달되는 전도열 및 전류인가시 발생되는 주울(Joule) 열을 차단하기 위한 헬륨냉매 제어시스템이 KSTAR 주장치와는 별도로 설치되어 있다. 리드박스 내 외부의 배관 및 제어시스템 설치완료 후 고진공 배기, 헬륨 누설검사, 전류인입선 유량 검사 및 액체질소 냉각시험을 실시하여 장치의 성능검증을 완료하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 추계학술대회 논문집 학회본부
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• pp.321-324
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• 1991

In this study, $(Sr{\cdot}Pb)TiO_3$ series ceramics which is used in high voltage were fabricated by the mixed oxide method, and the electrical conduction mechanism and D.C. breakdown voltage characteristics of the specimens in accordance with the contents of $Bi_2O_3{\cdot}3TiO_2$ were investigated. As a result, the leakage current was increased with the contents of $Bi_2O_3{\cdot}3TiO_2$ and the measuring temperature. At room temperature, the leakeage current was showed a tendency of saturating when D.C. electrical field of $l5{\sim}30$[kV/cm] was applied to the specimen. As a result of breakdown voltage characteristics. breakdown strength was decreased when the contents of $Bi_2O_3{\cdot}3TiO_2$ were increased. On the other hand, in the temperature region below $60[^{\circ}C]$, the electronic breakdown was occured, and in the temperature region from 60 to $200[^{\circ}C]$, the thermal breakdown was occured by the Joule heat and the dissipation factor.