• Journal of the Korean Society for Precision Engineering
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• v.12 no.7
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• pp.92-98
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• 1995

In the cluster tool, it is necessary to precisely control the vacuum pressure for the wafer transportation between transport module and cassette or process modules with the range of 1*10$^{-4}$ to 5*10$^{-5}$ torr. So we have designed the pressure control system for the transport module of the cluster tool and have evaluated its performance. Digital PID is utilized with the weighted sum of both three previous errors and one current error. The feedback signal is put into the nitrogen mass flow controller using the transport module controller. This pressure control system can prevent the transport module from the particle generation and backstreaming of hazardous process gases of the process chamber.

• Journal of the Korean Vacuum Society
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• v.10 no.4
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• pp.411-415
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• 2001

Using the plasma that we developed to generate a low-temperature plasma at atmospheric pressure, we have investigated the etching possibility of tin oxide $(SnO_2)$ thin films. Hydrogen and methane radicals generated from the plasma were observed and their intensity was found to be dependent on the cathode material by an analysis with optical emission spectroscopy as well as by the plasma impedance. The etching ability of this plasma was evaluated by an emission intensity as well as by the evaluation of impedance using a plasma I-V curve.

• Journal of the Korean Vacuum Society
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• v.3 no.2
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• pp.166-172
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• 1994

박막이 성장하는 동안 박막성장 상태를 관찰하기 위한 in-냐셔 타원해석기를 제작하였다. 이 타 원해석기는 He-Ne 레이저를 광원으로 사용하며 회전검광자형으로 광량측정방식을 채택하였다. 이 타원 해석기는 편광자 모듈과 검광자 모듈 및 제어부로 구성되어 있으며 이들 모듈은 각각 스퍼터링 챔버에 부착되었다. c-Si 기판 위에 열산화 과정으로 성장시킨 SiO2 박막을 표준시료로 사용하여 보정 및 성능 평가를 하였다 또한 RF 스퍼터링으로 c-Si 기판 위에 SiO2 박막을 성장시키면서 타원해석상수 ΨΔ를 측정하고 근사적 모델에 의한 ΨΔ의 전산모의 성장곡선과 비교해 보았다.

• Journal of the Korean Vacuum Society
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• v.8 no.4B
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• pp.530-535
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• 1999

W made a near-field optical microscope(NSOM) apparatus and evaluated it. To control the distance between a tip and a sample, we used a piezoelectric translator and a He-Ne laser, and consequently obtained the spatial resolution better than 100nm. For the semiconductor spectroscopic applications, we performed photoluminescence and photocurrent experiments on the GaAs/AlGaAs MQWs samples. In the case of PL experiment, we obtained the low signal to nose ration due to the extremely small power of a light source passing through the nanometric optical fiber tip. However photocurrent experiment shows a hundred times better signal to noise than that of PL experiment. This suggests that photocurrent experiment using NSOM have the possibility to provide the spatial resolution better than 10nm.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.1256-1263
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• 2010

Suction Drain Method is soft ground improvement technique, in which a vacuum pressure can be directly applied to the Vertical Drain Board to promote consolidation and strengthening the soft ground. This method does not require a surcharge load, different to embankment or Preloading Method. In this study, ground improvement efficiency of suction drain method was estimated when duplex loading pressure with vacuum and pressure. During suction drain method process, surface settlement and pore pressure were monitored, and cone resistance test as well as water content were also measured after the completion of Suction Drain Method treatment.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.1400-1407
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• 2005

There are a number of approaches to in situ remediation that are used at contaminated sites for removing contaminants from the contaminated zone without excavating the soil. These include soil flushing, dual phase extraction, and soil vapor extraction. Of these techniques, soil flushing is the focus of the investigation in this paper. The concept of using prefabricated vertical drains(PVDs) for remediation of contaminated sites with fine-grained soils is examined. The PVD system is used to shorten the drainage path or the groundwater flow and promote subsurface liquid movement expediting the soil flushing process. The use of PVDs in the current state of practice has been limited to soil improvement. The use of PVDs under vacuum conditions is investigated using sample soil consisting of silty sand.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.10a
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• pp.33-37
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• 2002

Recently, composites have been widely applied in the sporting goods, automobile, aerospace industry. As the use of advanced composites increase, specific techniques have been developed to repair damaged composite structures. In order to repair the damaged part, it is required that the material in the damaged area be removed first by utilizing the proper method, and prepreg be laid up in the area and cured under vacuum using the vacuum bagging materials. In curing process, either in an oven or autoclave is to be delamination can be occurred in the sound areas during and/or after the exposure to the elevated curing temperature in case that the repair process is repeated. Therefore, this study was conducted to evaluate the degree of degradation of properties of the cured parts and how it affects to the delamination phenomenon between laminated skin and honeycomb core.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.32-32
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• 2010

Since the characteristics of plasmas depend strongly on the interactions between plasma particles such as electron, ions, and neutrals, a well-established atomic and molecular database is needed to understand and produce various types of plasma. Thus, National Fusion Research Institute (NFRI) started to establish the plasma property DB for fusion and industrial plasma from last 2002. Here we describe our recent data evaluation activities regarding to production of atomic and molecular data that are needed for modeling plasma in fusion tokamaks and also low temperature industrial plasmas.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.3
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• pp.53-58
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• 2008

This study was conducted to evaluate the flatness of the porous type of dicing chuck. Two measurement systems for a vacuum chuck with a porous type of ceramic plate were prepared using a digital indicator and a laser interferometer. 6 inch of silicon and glass wafer were also used. Vacuum pressure from 100mmHg to 700mmHg by 100mmHg was increased. From experiments, chucked-wafer flatness was converged to the dicing chuck flatness itself even though the repeatability of contact method using indicator was unstable. Finally, the chuck flatness was estimated below $2{\mu}m$ with peak-to valley value.

• Proceedings of the Korean Vacuum Society Conference
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• 2003.08a
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• pp.108-108
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• 2003