• Journal of Magnetics
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• v.9 no.2
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• pp.37-39
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• 2004

Polycrystalline Ni-Mn-Ga films have been deposited onto mica substrates held at 720 K by flash-evaporation method. At room temperature the films have a tetragonal structure with a = b = 0.598 and c = 0.576 nm typical for bulk $Ni_2MnGa$ below a martensitic transformation. Temperature measurements of ferromagnetic resonance reveal a martensitic phase transformation at 310 K. The transformation brings about a substantial decrease in the effective magnetization and a drastic increase in the ferromagnetic resonance linewidth due to a strong increase in the magnetic anisotropy in the martensitic phase.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1917-1919
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• 1996

This paper aims to extract the air clearance in 22.9KV the metal enclosed switchgear. First, we investigated the actual conditions on the clearance in the metal enclosed switchgear which has been used in domestic. The test model and 9 test electrodes for the air insulation strength tests have been designed and manufactured based on the investigation results. To find optimal clearance in the metal enclosed switchgear, we performed 50% flash-over test by the up and down method and lightning impulse withstand voltage test. And we obtained results that the clearance or phase-to-phase is 230 [mm] and clearance or phase-to-earth is 210[mm].

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.6
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• pp.462-466
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• 2012

In this paper, heat-releasing composite sheets made of AlN, graphite, Al powder and acryl binder as thermoset were prepared using tape casting method. The crystal structure, morphology, thermal conductivity of heat-releasing composite sheet were measured by using X-ray diffractometer, field emission-scanning electron microscopy and laser flash instrument. It was found thermal conductivity of sheet was decided by solid content, composition including AlN, graphite, Al in heat-releasing composite sheets. As a result, 4.56 W/mK of thermal conductivity could be obtained by using LFA 447.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.6
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• pp.431-434
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• 2012

In this paper, heat-releasing sheets made of AlN powder and acryl binder as thermoset were prepared using tape casting method. The crystal structure and morphology, the thermal properties as nonvolatile solid content and thermal conductivity, and the surface resistance of heat-releasing sheet were measured by using X-ray diffractometer, field emission-scanning electron microscopy, thermo gravimetric analyzer and laser flash instrument, and surface resistance meter. It was proved that thermal conductivity is greatly affected by the content of binder in heat-releasing sheet. Superior thermal conductivity above 3.5 W/mK and suface resistance were obtained at heat-releasing sheet with above 90% of AlN powder.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.760-765
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• 2000

The study deals with the development of a computational procedure for evaluating the temperature rise in dry and lubricated multi-layered contacts of head/disk interface. A transient computational model with a transformed rectangular computational domain is utilized. A model and a computational method for micro-contact with sub-lubricated zone, including friction heat generation, have been presented. The model was applied, taking full account of the changes in contact area and contact load due to frictional heating. The computational distribution of temperature is obtained with the analytical findings for various composition and contact conditions. Especially, a rapid rise ($220^{\circ}C$ or above) in read head temperature lese to a saturation in the influence of a thermal spike on signal performance. This general class of problems can be treated provided that heat generation distribution and layer properties are known.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.117-120
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• 2005

The SONOS devices have been fabricated by the conventional $0.35{\mu}m$ complementary metal-oxide-semiconductor (CMOS) process with NOR array. Two-bit operation using conventional process achieve the high density memory compare with other two-bit memory. Lateral diffusion phenomenon in the two-bit operation cause soft error in the memory. In this study, the programming conditions arc investigated in order to reduce lateral diffusion for two-bit operation of CSL-NOR type SONOS flash cell.

• Proceedings of the Korean Information Science Society Conference
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• 2008.06c
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• pp.41-44
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• 2008

플래시 메모리 환경에서는 디스크 환경과는 달리 논 클러스터링 방법의 성능이 클러스터링 방법에 비해 우수하다. 그러나 논 클러스터링 방법 역시 플래시 메모리의 특성을 고려하여 설계된 것이 아니므로, 성능 저하 요인이 많이 존재한다. 본 논문에서는 이를 바탕으로 플래시 메모리 환경에서 효율적인 레코드 관리방법을 제안한다. 제안하는 레코드 관리 방법은 빈 공간이 큰 페이지에 레코드들을 최대한 모아 한 번의 쓰기 연산으로 저장함으로써, 쓰기 연산을 크게 줄일 수 있다. 실험 결과에 의하면, 제안하는 방법은 기존 방법의 성능을 최대 1.8배까지 향상시키는 것으로 나타났다.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.5
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• pp.104-111
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• 2005

With increasing use of SUH35/SUH3 dissimilar materials for automotive engine valves, it is required that stress singularities under residual stress on an interface for friction welded dissimilar materials analyzed to establish strength evaluation. The stress singularity $index{\lambda}$ and stress singularities $factor{\Gamma}$ were calculated from using the results of stress analysis to consider residual stress and loads. The stress singularities on variations for shapes and thickness of welded flashes were analyzed and discussed. This paper suggested that the strength evaluation by using the stress singularity factors as fracture parameters, considering the stress singularity on an interface edge of friction welded dissimilar materials will be useful.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2011.11a
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• pp.167-170
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• 2011

화재현장에서 소방공무원은 화염, 증기, 또는 고온물 등에 의하여 화상사고를 당하고, 이로 인하여 극심한 고통 받고 있다. 따라서 화상 예측에 대한 연구를 통해 화상을 방지할 수 있는 방법을 개발하여야 한다. 본 연구에서는 화재시 고온 열유속 조건하에서의 화상 발생에 대한 예측을 수치해석적 방법으로 수행하였다. 생체 열전달 방정식(Bio-heat transfer)을 이용하여 지배방정식을 유도하였으며, 유한차분법(Finite Difference Method)을 활용하여 피부조직에 대한 온도분포를 얻었다. 이를 바탕으로 한 손상함수를 이용하여 2도 화상의 발생 유무를 예측하였으며, 기존의 실험 결과[Stoll and Chianta]와 비교하여 좋은 예측 결과를 얻을 수 있었다.

• Proceedings of the SAREK Conference
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• 2005.11a
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• pp.451-456
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• 2005

The mathematical model for the heat exchangers of absorber and desorber is made in the elementary control volume method and the thermodynamic properties of working fluid. water/ammonia mixture. are calculated by some fundamental subroutines in RefProp 7.0 and flash subroutines made by authors The simulation results show that two-stage cycle has higher COP than single stage if temperature lift is high: the performance of single stage compression cycle can be improved by increase of absorber pressure. but the performance of two-stage compression cycle can not be improved in this way : the compressor discharging temperature of two-stage compression is much lower than that of single stage cycle. which is very important to the safety operation of CA heat pump. Major parameter comparison between the cycles at their optimal configurations is also given.