• Journal of Microbiology and Biotechnology
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• v.10 no.4
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• pp.554-558
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• 2000

Bacteria were isolated and identified from an advanced high-purity water system that supplies ultra-high purity water (UHPW) for 16-megabyte DRAM semiconductor manufacturing. Scanning electron microscopic and microbiological observations revealed that the primary source of the bacteria isolated from the UHPW was detached cells from biofilms developed on the pipe wall through which the UHPW, a man-made and extremely nutrient poor environment, was passing. About 63-65% of the bacteria isolated from the UHPW and the pipe wall were Gram-positive, whereas only 10% of the bacteria isolated from the feed water were Gram-positive. The of Gram-positive bacteria and seven genera of Gram-negative bacteria. Strains of the UHPW bacteria effectively adhered to and formed a biofilm on the surface of polyvinyl chloride (PVC) pipe.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.1281-1283
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• 2001

An investigation into power conditioners that interface with photovoltaic array and utilities has been completed. The rating for this investigation is residential system(3-5kW) that interface with a 220V single phase utility connection. As the result of this investigation, a 3kW high frequency PWM IGBT inverter feeding a high frequency isolation transformer with a sinusoidal current wave was selected. The output of the transformer rectified with a diode bridge rectifier four IGBT, used as 60Hz switched, reverse the polarity of the rectified current on every other half cycle of the utility voltage. Even though the high frequency link system used more power semiconductors a net size, weight, and parts cost saying result compared to the other systems due to elimination of 60Hz transformer.

• Proceedings of the KIEE Conference
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• 1998.07d
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• pp.1324-1326
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• 1998

To drive motor or heating machine, it needs the electric power system like the apparatus of inverter. This electric power system obviously comprises power switching devices and drivers to run them. And this system has the topology comprised one/many arm(s), - each arm has high side switching device and low side switching device. Transformer, photocoupler, and HVIC having functions of isolation and level shift which are important thing to drive high side switching device are used as component of drivers in conventional apparatus. Piezoelectric transformers are proposed in this paper, and applied to drive high side swiching device. Through experiments, the possiblities of driving high side switching device are presented and the problems are mooted concurrently. But, we also consider a counterplan for solving the mooted trouble issues.

• JSTS:Journal of Semiconductor Technology and Science
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• v.3 no.1
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• pp.33-41
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• 2003

In this work, process optimization techniques for high frequency performance of HBTs are presented. The techniques are focused on reducing parasitic base resistance and base-collector capacitance, which are key elements determining the high frequency characteristics of HBTs. Several fabrication techniques, which can significantly reduce the parasitic elements of the HBTs for improved high frequency performance, are proposed and verified by the measured data of the fabricated devices.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.946-949
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• 1999

In this research we have developed a reliable, effective and feasible HEI(High-Energy Ion Implantation) process 3D-simulation tool, and then by using it we can predict and analyze the effect of HEI process on characteristics of the standard CMOS device. high-energy ion implantation above 200 keV is inevitable process to form retrograde well and buried layer to prevent leakage current, to conduct field implant for field isolation, and to perform after-gate implantation. The feasible analysis tool is a product of the HEI process modeling verified by comparison of the SIMS experiments with the simulation results. Especially, in this paper, we present the predicting capability of HEI-induced impurity and damage profiles compared with the published SIMS data in order to acquire the reliability of our results ranging from few keV to several MeV for phosphorus and boron implantation.

• Journal of IKEEE
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• v.7 no.1 s.12
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• pp.1-8
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• 2003

In this study, the high performance BCD device structure which satisfies the high voltage and fast switching speed characteristics is devised. Through the process and device simulation, optimal process spec. & device spec. are designed. We adapt double buried layer structure, trench isolation process, n-/p-drift region formation and shallow junction technology to optimize an electrical property as mentioned above. This I.C consists of 20V level high voltage bipolar npn/pnp device, 60V level LDMOS device, a few Ampere level VDMOS, 20V level CMOS device and 5V level logic CMOS.

• Proceedings of the KIPE Conference
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• 2003.07b
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• pp.511-515
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• 2003

This paper presents a novel prototype of the utility-interfaced sinusoidal pulse width modulated (SPWM) inverter using the high-frequency flyback transformer fur the small-scale solar photo-voltaic power conditioner (1kW - 4kW). The proposed SPWM power conditioner circuit with a high-frequency link has a function of electrical isolation, which is vital fur solar photovoltaic power conditioner systems with the viewpoint of safety and convenience. The discontinuous conduction mode (DCM) operation of the flyback transformer is also maintained to simplify the topology of the inverter circuit and control scheme. First, the operating principle of the proposed circuit is described far the understanding of the circuit parameters establishment. Then, the digitally constructed SPWM control scheme is presented. The proposed circuit is verified by the computer simulation and the prototype experiment.

• Proceedings of the KIEE Conference
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• 2001.04a
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• pp.467-469
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• 2001

An investigation into power conditioners that interface with photovoltaic array and utilities has been completed. The rating for this investigation is residential system(3-5kW) that interface with a 220V single phase utility connection. As the result of this investigation, a 3kW high frequency PWM IGBT inverter feeding a high frequency isolation transformer with a sinusoidal current wave was selected. The output of the transformer rectified with a diode bridge rectifier, four IGBT, used as 60Hz switched, reverse the polarity of the rectified current on every other half cycle of the utility voltage. Even though the high frequency link system used more power semiconductors, a net size, weight, and parts cost saving result compared to the other systems due to elimination of 60Hz transformer.

• Proceedings of the KIEE Conference
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• 1998.07g
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• pp.2458-2460
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• 1998

To drive motor or heating machine, it needs the electric power system like the apparatus of inverter. This electric power system obviously comprises power switching devices and drivers to run them. And this system has the topology comprised one/many arm(s), - each arm has high side switching device and low side switching device. Transformer, photocoupler, and HVIC having functions of isolation and level shift which are important thing to drive high side switching device are used as component of drivers in conventional apparatus. Piezoelectric transformers are proposed in this paper, and applied to drive high side swiching device. Through experiments, the possiblities of driving high side switching device are presented and the problems are mooted concurrently. But, we also consider a counterplan for solving the mooted trouble issues.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1050-1052
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• 2000

An investigation into power conditioners that interface with photovoltaic array and utilities has been completed. The rating for this investigation is residential system (3-5kW) that interface with a 220V single phase utility connection. As the result of this investigation. a 3kW high frequency PWM IGBT inverter feeding a high frequency isolation transformer with a sinusoidal current wave was selected. The output of the transformer rectified with a diode bridge rectifier four IGBT, used as 60Hz switched, reverse the polarity of the rectified current on every other half cycle of the utility voltage. Even though the high frequency link system used more power semiconductors, a net size, weight, and parts cost saving result compared to the other systems due to elimination of 60Hz transformer.