• 한국진공학회:학술대회논문집
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• 한국진공학회 2000년도 제18회 학술발표회 논문개요집
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• pp.146-146
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• 2000

We have studied the etching of Si(100)-2xl by Cl and Br, using scanning tunneling microscopy to obtain morphological information that can be related to reaction and desorption pathways. Clean surfaces were exposed to molecular halogens at room temperature to produce well-defined chemisorption structures for coverages in the range 0.2-1.0 ML. Heating to 750-750 K induced etching by thermal desorpton. Analysis of the halogen concentration before and after heating indicated that the rates of desorption for SICl2 or SiBr2 were greatest for intermediate coverages and that etching was suppressed as saturation was reached. Hence, desorption is not simply proportional to the concentration of species that can form adsorbed precursors SiX2(a). Instead, it is directly coupled to the creation of monomer vacancies adjacent to the SiX2 (a) unit because this increases the lifetime of the excited state and increases the likelihood of its desorption. Increasing the surface concentration of halogens reduces the rate of vacancy formation. We show that these rates are also affected by a re-dimerization process in the high temperature Br-stabilized Si(100)-3xl reconstruction that increases the likelihood of siBr2(a) formation and enhances its desorption. I will also discuss recent result for F etching on Si(100)-2xl.

• KIEAE Journal
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• 제16권3호
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• pp.121-128
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• 2016

Purpose: The vacuum glazing should constantly retain the gap in vacuum state to maintain high thermal performance. To do so, pillars are used to prevent the glazing from clinging to each other by the atmospheric pressure and therefore surface of the vacuum glazing is consistently affected by residual stress. The vacuum glazing could be applied to curtain wall systems at spandrel area to fulfill a rigorous domestic standard on U-value of the external wall. However, this can lead to high glazing temperature increase by heat concentration at a back panel and finally thermal stress breakage. This study experimentally determined weakness of the vacuum glazing systems on the thermal stress breakage and investigated effect of the residual stress. Method: The experiment first built two scale-down mock-up facilities that replicate the spandrel area in curtain wall, and then installed single low-e glass and vacuum glazing respectively. The two mock-up facilities were exposed to outside to induce the thermal stress breakage. Result: The experiment showed that the temperature occurred the thermal stress breakage was $114.4^{\circ}C$ for the single low-e glass and $118.9^{\circ}C$ for the vacuum glazing respectively. The result also showed the vacuum glazing reached the critical point earlier than the single low-e glass, which means that the vacuum glazing has high potential to occur the thermal shock breakage. In addition, the small temperature difference between two glazing indicates that the residual stress scarcely affects breakage of the vacuum glazing.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.208.2-208.2
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• 2016

Many researchers have paid attention to the studies on the interaction between non-thermal plasma and aqueous solutions for biomedical applications. The gas composition in the plasma is very important. Oxygen and nitrogen are the main gases of interest in biological applications. Especially, we focus on the oxygen concentration. In this experiment, we studied the role of oxygen concentration in plasma induced chemical reactions in solution. At first, the amount of ions are measured according to changing the oxygen concentration. And we checked the relationship between these ions and pH value. Secondly, when the oxygen concentration is changed, it identified the type and amount of radical generated by the plasma. In order to confirm the effect of these chemical property change to biological material, hemoglobin and RBCs are chosen. RBCs are one of the common basic biological cells. Thirdly, when plasma treated according to oxygen concentration in nitrogen feeding gas, oxidation of hemoglobin and RBC is checked. Finally, membrane oxidation of RBC is measured to examine the relation between hemoglobin oxidation and membrane damage through relative hemolysis and Young's modulus. Our results suggest that reactive species generated by the plasma differsdepending on the oxygen concentration changes. The pH values are decreased when oxygen concentration increased. OH decrease and NO increase are also observed. These reactive species makes change of chemical properties of solution. We also able to confirm that the difference in these reactive species to affect the oxidation of the Hb and RBCs. The Hb and RBCs are more oxidized with the high oxygen concentration conditions. But membrane is damaged more by plasma treatment with only nitrogen gas. It is shown that red blood cells membrane damage and oxidation of hemoglobin are not directly related.

• 에너지공학
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• 제12권3호
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• pp.216-222
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• 2003

실험실 규모의 진공 증발 수분 제거 시스템을 이용하여, 압력, 윤활유의 온도, 초기 수분농도 및 윤활유 분사 노즐의 형태 등 폐윤활유 속에 포함된 수분 제거 성능에 영향을 미치는 각각의 운전 변수들에 대한 실험적인 연구를 수행하였다. 연구의 결과 압력 및 폐윤활유 온도의 증가는 수분 제거 성능에 매우 중요한 변수임을 확인하였으며, 또한 진공 증발실로 폐윤활유를 분사하기 위한 노즐의 형태는 다공성 매질의 노즐 형상인 경우가 가장 우수한 수분 증발 성능을 나타내었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.100-100
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• 2010

Because of power consumption increase, global wanning, and limitation of installation, not only high reliability and interruption capability but also compact and light power apparatuses are needed. To improve the insulation performance, the high E field concentration phenomena was considered. Breakdown mechanism in vacuum is different from that in other insulation materials. therefore, It is necessary to understand the electric field distribution and insulation characteristics. This paper discusses the simulation and LI(light impulse) test of the shield of outside vacuum interrupter As a result, FEM simulation and LI test show that improve distribution of electrical field and equi-potential line. due to external shield. in this case, outside shield induced electric field of triple junction point.

• 한국식품저장유통학회지
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• 제4권2호
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• pp.139-146
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• 1997

The influence of packaging methods(0.03mmPE, 0.05mmPE, 0.1mmPVC, VACUUM) and marketing temperatures(2$0^{\circ}C$, 1$0^{\circ}C$) on the shelf-life and quality were investigated in yam(Dioscorea). Respiration, weight-loss and rotting-rate was reduced in polyethylene film packaging in the order of VACUUM, 0.1mmPVC, 0.05mmPE, 0.03mmPE and the effect was more outstanding at 1$0^{\circ}C$ than 2$0^{\circ}C$. The ethylene concentration of PVC packaging group was higher than that of other packaging methods, which was related with sprouting. firmness was higher in low-temperature than in room-temperature. PPO activity was lower in vacuum than in other packaging methods, which was associated with browning. The shelf-life of yam was the longest in vacuum Packaging, 3 weeks at 2$0^{\circ}C$ and more than 4 weeks at 1$0^{\circ}C$.

• 한국분말재료학회지
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• 제14권5호
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• pp.315-319
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• 2007

Pure WC or WC with low Co concentration less than 0.5 wt.% is studied to fabricate high density WC/Co cemented carbide using vacuum sintering and post HIP process. Considering the high melting point of WC, it is difficult to consolidate it without the use of Co as binder. In this study, the effect of lower Co addition on the microstructure and mechanical properties evolution of WC/CO was investigated. By HIP process after vacuum sintering, hardness and density was sharply increased. The hardness values was $2,800kgf/mm^2$ using binderless WC.

• 한국전기전자재료학회논문지
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• 제20권4호
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• pp.374-380
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• 2007

In this paper a nobel optimum design method is presented for a shield in a vacuum interrupter which is equipped in switchgear to improve its electric insulation capability. The design of Taguchi experiment method which is based on the results by finite element method is used to find optimum design conditions. The important design factors are chosen at first and the concept of signal to noise ratio is applied to evaluate the vacuum interrupter performance, and the optimal values of each parameters are determined. From the results of various analyses, it is shown that the shield plate in circuit circuit breaker compartment of switchgear can reduce the concentration of electric field intensity. This method is very useful to design the construction of a shield in a short time. Consequently, the insulation capability of circuit breaker compartment in a gas insulated switchgear is improved by adopting an additional optimized shaped shield.

• Applied Science and Convergence Technology
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• 제25권2호
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• pp.25-27
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• 2016

The surface flatness of metal meshes in a deflector of particle beam mass spectrometer (PBMS) required ideally flat, and this can specify the particle trajectories which goes through the detector. In this research, charged particle current was measured using the different surface roughness deflectors. NaCl particles were generated monodispersed in its size by using differential mobility analyzer and the whole processes were followed the way calibrating PBMS. The results indicate that the mesh surface morphology in the deflector can affect to the particle size and the concentration errors, and sensitivity of PBMS.

• 한국안전학회지
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• 제22권4호
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• pp.32-36
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• 2007

When the vacuum system for the process of $SiH_{4}$ gas used in the semiconductor and FPD field is partially vented from vacuum to atmospheric state, a fire often occurs due to auto-ignition of $SiH_{4}$ gas. In order to prevent the fire, the concentration of $SiH_{4}$ should be kept under LFL. This means that the higher capacity pump is needed to meet the process conditions as well as the condition that the concentration of $SiH_{4}$ should be kept under LFL. In this article, we conducted the injection of the dilution gas at the manifold between booster pump and dry pump compared with the typical method that the dilution gas was injected into inlet port of booster pump using computer simulation. According to the result, we can flow further more purge gas for safety without any change of the condition in the process chamber, which means that the higher capacity pump is not required for safety in some cases.