• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2494-2499
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• 2007

Self-blast circuit breakers utilize the energy dissipated by the arc itself to create the required conditions for arc quenching during the current zero. The high-current simulation provides information about the mixing process of the hot PTFE cloud with $SF_6$ gas which is difficult to access for measurement. But it is also hard to simulate flow phenomenon because the flow in interrupter with high current, $SF_6$-PTFE mixture vapor and complex physical behavior including radiation, calculation of electric field. Using a commercial computational fluid dynamics(CFD) package, the conservation equation for the gas and temperature, velocity and electric fields within breaker can be solved. Results show good agreement between the predicted and measured pressure rise in the thermal chamber.

• Progress in Superconductivity and Cryogenics
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• v.3 no.1
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• pp.11-15
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• 2001

Stability of a Bi-2223/Ag tape was studied by using a numerical model considering the temperature distribution of cross-sectional area. The dynamic evolution of normal zone of a HTS tape can be shown by the developed two-dimensional Program using finite difference method. Two kinds of analyses are compared to quantify the critical disturbance energy for quenching HTS tapes. One is the length-thickness(x-r) side and the other is the length-width(x-z) side. For each case. the governing energy balance equations and corresponding boundary conditions are formulated. The results of analyses shows that the critical disturbance energies for each cases seem to be very close for considered Bi-2223/Ag tape .

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.263-263
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• 2009

The microtstructures and properties of alloys in the pseudo-binary $Bi_2Te_3-PbTe$ system were investigated as a first step towards the design of nanostructured materials with enhanced thermoelectric properties. The liquid alloys were cooled by water quenching method. Dendritic and lamellar structures were observed clearly by using environmental scanning electron microscope(eSEM) and electron probe micro analyzer(EPMA) take into account composition ratio between $Bi_2Te_3$ and PbTe. The compound $Pb_2Bi_6Te_{11}$ precipitated as a metastable phase under all conditions. The structure of those samples changed from dendritic to lamellar by increasing $Bi_2Te_3$ ratio of composition.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.10a
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• pp.260-263
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• 2001

Mechanical properties have been accepted to be major factor to improve wear resistance. The effect of mechanical properties on wear resistance of 0.27C-0.70Ni-1.42Cr-0.20Mo steel was studied under various test conditions. It is clear that yield strength, tensile strength, impact value, and hardness are strongly related each other. Wear resistance tests as pin on plate type and dry sand / rubber wheel type proved to be that wear depends on mechanical properties. Microstructures were also observed to make clear the wear properties. At quenching and low temperature tempering, the specimen has a good wear resistance.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1998.05a
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• pp.37-42
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• 1998

석탄가스화복합발전(IGCC; Integrated Gasification Combined Cycle) 공정이 80년대 들어 선진외국을 중심으로 석탄발전기술로 많이 연구되고 실용화를 위해 막대한 자금을 국가주도로 투입하고 있는 이유는 IGCC공정이 고체시료인 석탄을 가장 환경적합적으로 쓸 수 있는 방법이라고 판단하였기 때문이다. 또한, 장기적으로 연료전지에 석탄가스를 연계시키면 플랜트효율이 60%에 달하면서 현재까지 알려진 석탄이용 발전기술의 모든 idea중에서 가장 환경오염을 저감시킬 수 있는 향후 50년 이상을 내다볼 수 있는 발전기술이기 때문에 기술개발에 선진 각국이 국가적으로 노력하고 있는 것이다. (중략)

• Journal of the Korean Society for Precision Engineering
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• v.2 no.2
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• pp.60-68
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• 1985

The Surface roughness is affected by the factors such as elements of grinding wheel, grinding conditions, and so on. Of all these factors, we studied surface roughness variation in accordance with grain size of grinding wheel and grinding depth of cut on the surface grinding. Tempered, annealed, quenched, and non-heat treated materials were used as specimen. The results obrained in these experiments are as follows: 1) The smaller the hardness is, the better the grinding surface roughness becomes. 2) Tempered materials after quenching shows the finest finished surface on grinding.

• Journal of Ocean Engineering and Technology
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• v.6 no.2
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• pp.35-40
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• 1992

A recently developed new technique for measuring the fraction of wetted area has applied to pool boiling of water. The basis of the new applied technique of ultrasonic makes use of the reflection of ultrasonic from the vapour surface to measure the fraction of wetted area values. The results are the measured fraction of wetted area values in nucleate and transition boiling and the pool boiling curve for water under steady state conditions. The measurement of this paper shows a fraction of wetted areaf around 0.98 at the critical heat flux for water.

• Clean Technology
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• v.4 no.2
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• pp.11-22
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• 1998

The photo-sensitized oxidation of benzene in water was investigated under various reaction conditions using persulfate, sulfate, nitrate, nitrite and chloride ions as sensitizers. Persulfate ion was proved to be the most effective sensitizer, while sulfate and nitrite could not play any sensitizing role on the benzene photooxidation. When exited together with other ions, the nitrite ion inhibited the photooxidation of benzene by quenching the produced hydroxyl radicals.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1355-1359
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• 2006

Due to its efficient red emission, $Eu^{3+}$ ion has been doped in various host materials. $GdCa_4B_3O_{10}:Eu^{3+}$ phosphor for red emission has been prepared by solid state reaction. Photoluminescence properties for the phosphor under UV and VUV excitation were investigated. The $GdCa_4B_3O_{10}:Eu^{3+}$ phosphor under both excitation conditions shows typical red emission spectrum centered at 611 nm with several weak peaks due to energy transfer from $^5D_O\;to\;^7F_J(J=1,2,3,4)$ of $Eu^{3+}$ ion. On the other hand, the activator content exhibiting the concentration quenching under UV and VUV irradiation is 10 mole% and 2.5 mole%, respectively.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.883-886
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• 2001

The mechanical properties such as the Young's modulus, damping ratio, vibration mode and hardness of the disk materials heat-treated under various conditions are measured, and the relations between there properties and the cutting characteristics such as early tip fracture are examined. The results obtained from this study are as follows. The circular saw with the V-Cr added disk has higher young's modulus and damping ratio than the saw with STC5 disk, preventing the early fracture of tungsten carbide due to the above properties. The circular saw with the disk which is subjected to the heat treatment at the quenching temperature of $830^{\circ}C$ and at the temperature of $550^{\circ}C$ have the best tool life and surface roughness.