• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권1호
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• pp.845-848
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• 2007

Analysis of point defects invisible by a microscope has been studied on the a-Si thin film transistor panel. The point defects which were named Invisible Point Defect (IPD) is characterized by no particles or distortion of patterns on a pixel structure and randomly distributed on panels. To investigate the IPD, measurements were carried out: gray level driving, transistor transfer characteristic, focused ion beam (FIB), and secondary ion mass spectrometry (SIMS). The results showed that a contamination layer had a bad influence on an active surface. The contamination layer consisted of oxygen and iron from a water supply line during cleaning process. After the process tuning, IPD has been stabilized.

• Journal of Power Electronics
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• 제11권5호
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• pp.751-758
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• 2011

This paper presents an effective robust predictive control scheme for the active power filter (APF) using a smith-predictor based current regulator, which show superior features when compared to proportional-integral (PI) controllers in terms of an enhanced closed-loop bandwidth and an improved current tracking accuracy. A moving average filter (MAF) is implemented using a field programmable gate array (FPGA) for signal pre-processing to eliminate the switching ripple contamination. An adaptive linear neural network (ADALINE) is used for individual harmonic estimation to achieve selective compensation purpose. The effectiveness and validity of the devised control algorithm are confirmed by extensive simulation and experimental results.

• 방사선산업학회지
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• 제5권2호
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• pp.185-189
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• 2011

As nuclear industry has been developed, a various types of radiological contamination has occurred. After 9.11 terror in U.S.A., it has been concerned that terrorists' active area has been enlarged to use nuclear or radioactive substance. Recently, the most powerful earth-quake stroke, which triggered a massive tsunami in Japan and then Fukushima nuclear power plant reactor has suffered from a serious accident in history. The Fukushima reactor accident has occurred an anxiety of radiation leaks and about 170,000 people have been evacuated from the accidental area near the nuclear power plant. For these reasons, a social chaos can be occurred if radiological contamination occurs to the supply system for the drinking water. As such, the establishment of the radiation monitoring system for the city main water system is compelling for the national security. In this study, a feasibility test of radiation monitoring system which consists of unified hybrid-type radiation detectors was experimented for multi detection system by using gamma-ray imaging. The hybrid-type radiation sensors were fabricated with CsI(Tl) scintillators and photodiodes. A preamplifier and amplifier was also fabricated and assembled with the sensor in the shielding case. For the preliminary test of detection of radiological contamination in the river, multi CsI(Tl)-PIN photodiode radiation detectors and $^{137}Cs$ gamma-ray source were used. The DAQ was done by Linux based ROOT program and NI DAQ system with Labview program. The simulated contamination was assumed to be occurred at Gapcheon river in Daejeon city. Multi CsI(Tl)-PIN photodiode radiation detectors were positioned at the Gapcheon river side. Assuming that the radiological contaminations flows in the river the $^{137}Cs$ gamma-ray source has been moved and then, the contamination region was reconstructed.

• Pediatric Infection and Vaccine
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• 제22권3호
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• pp.147-153
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• 2015

목적: 본 연구는 신생아중환자실에 입원한 환자에서 혈액 배양 오염률을 조사하고, 오염유무에 따른 임상적 특성을 비교하고자 하였다. 방법: 고신대학교복음병원 신생아중환자실에 입원한 환자들을 대상으로 시행한 830건의 혈액 배양 검사 결과에 대해 분석하였다. 혈액 배양 오염률과 채혈부위별 오염률을 조사하였고, 말초혈액 배양 시 오염 유무에 따른 임상적인 특성을 비교하기 위해 의무기록을 조사하였다. 결과: 연구기간 중 오염률은 3.6%였다. 채혈 부위별 오염률은 말초정맥 15.6%, 말초동맥 2.6%, 배꼽동맥 도관 0%였다. 실명제가 시행되지 않았던 기간의 오염률은 2.7% (4/149), 시행 기간에는 4.4% (25/573)로 오염률의 차이가 없었다(P=0.484). 시술자별 오염률은 0-11.1%로 시술자간 차이가 있었다(P=0.038). 채혈 시 몸무게가 1,000 g 미만인 경우 오염률이 유의하게 높았다(P<0.001). 결론: 몸무게가 적은 미숙아에서 혈액 배양 오염률이 더 높을 수 있으므로 채혈 방법에 주의가 필요하며, 오염률이 높은 시술자를 관리해야 한다. 신생아에서 혈액 배양 오염률을 감소시킬 수 있는 인자들을 파악하고 실제 임상에서 적용하기 위한 전향적이고, 체계적인 연구가 필요할 것으로 보인다.

• Korean Chemical Engineering Research
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• 제49권1호
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• pp.15-20
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• 2011

고분자전해질 연료전지에 유입되는 공기가 톨루엔에 오염되었을 때 전지 성능에 미치는 영향을 여러 톨루엔 농도와 운전 조건에서 연구하였다. 그리고 청정한 공기에 의한 전지 성능 회복과 활성탄 흡착에 의한 공기 중 톨루엔의 제거에 대해서도 연구하였다. 본 연구에서 실험한 톨루엔의 농도 범위는 0.1~5.0 ppm이었고 전지 성능감소와 회복은 일정전류에서 전압변화 측정법과 전기화학적 임피던스 측정법(EIS)에 의해 측정하였다. KOH 첨착활성탄의 톨루엔 흡착용량은 등온흡착곡선으로 구했다. 톨루엔 농도가 증가할수록, 전류밀도가 증가할수록, 공기유량이 증가할수록 톨루엔 오염에 의한 성능감소가 심했다. 그러나 상대습도가 증가할수록 톨루엔 오염에 의한 성능감소는 작았다. 가습된 청정 공기 중의 산소와 수분에 의한 톨루엔의 산화에 의해 전지의 성능이 회복되었다. 톨루엔의 백금 표면 흡착에 의한 전하 전달 저항 증가가 전지 성능을 주로 감소시킴을 EIS가 보였다. 첨착활성탄의 톨루엔 흡착 용량은 KOH 첨착량이 증가할수록 감소하였다.

• Journal of Pharmaceutical Investigation
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• 제39권4호
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• pp.263-267
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• 2009

The purpose of this study is to evaluate the efficacy of stipulated cleaning process, and the prohibition of cross-contamination and microbiological contamination, which inadequate cleaning in multi-production could occur, through cleaning validation of multi-purpose facility used to produce five biopharmaceutical products as sterile injection. After production of five biopharmaceutical products such as hGH, rhGCSF, rhEPO, rhFSH and rhIFN using vial filling machine, the cleaning validation such as residual analysis of active ingredients or human serum albumin, measurement of total organic carbon (TOC), residual analysis of detergent and microbiological contamination were carried out. In the case of rhGH and rhGCSF clean validations, drug residues were not detected. Furthermore, in the case of rhEPO, rhFSH and rhIFN clean validations, human serum albumin residues were not detected. At TOC (total organic carbon) analysis, all clean validations gave the TOC of about average 137.93%, not more than 150% of acceptance criteria. At sodium analysis for the checking of residues of cleaning agent, sodium residues were not detected. In sterility test, they showed no microbiological contamination of bacteria and fungi. Thus, this cleaning validation was determined as successful in protection of cross-contamination and induction of safety in multi-purpose facility.

• Membrane and Water Treatment
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• 제9권5호
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• pp.335-342
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• 2018

Micelle-Enhanced Ultrafiltration (MEUF) is a membrane separation processes that improving ultrafiltration process with the formation of micelles of the surface active agents. Surface active agents are widely used to improve membrane processes due to the ability to trap organic compounds and metals in the treatment of industrial waste water. In this study, surface active agents are used to improve micelle-enhanced ultrafiltration (MEUF) to reduce chemical oxygen demand (COD), total dissolved solid (TDS), turbidity and clogging the membrane in dairy wastewater treatment. Three important operational factors (anionic surface active agent concentration, pressure and pH) and these interactions were investigated by using response surface methodology (RSM) and Box-Behnken design. Results show that due to the concentration polarization layer and increase the number of Micelles; the anionic surface active agent concentration has a negative effect on the flux and has a positive effect on the elimination of contamination indices. pH, and the pressure have the greatest effect on flux. On the other hand, it could be stated that these percentages of separation are in the percentages range of Nano-filtration (NF). While MEUF process has higher flux than NF process. The results have been achieved at lower pressure while NF process needs high pressure, thus making MEUF is the replacement for the NF process.

• Journal of Radiation Protection and Research
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• 제33권1호
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• pp.27-34
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• 2008

국내 환경을 고려하여 개발된 도시환경 방사능오염 평가모델 METRO-K (${\underline{M}}odel$ for ${\underline{E}}stimates$ the ${\underline{T}}ransient$ Behavior of ${\underline{R}}adi{\underline{O}}active$ Materials in the ${\underline{K}}orean$ Urban Environment)는 IAEA (${\underline{I}}nternational$ ${\underline{A}}tomic$ ${\underline{E}}nergy$ ${\underline{A}}gency$) 주관 국제공동 연구프로그램 EMRAS (${\underline{E}}nvironmental$ ${\underline{M}}odelling$ for ${\underline{RA}}diation$ ${\underline{S}}afety$)의 도시환경 방사능오염평가 분과에서 체르노빌 원전사고로 오염된 Pripyat 지역과 가상 방사능테러로 인한 오염 시나리오의 평가에 참여해 오고 있다. 본 논문에서는 EMRAS 프로그램의 일환으로 수행된 Pripyat 지역에 대한 METRO-K의 평가 결과를 제시하였고 다른 모델의 예측값과 비교, 논의함으로써 만일의 도시환경 방사능오염시 대응행위 결정지원을 위한 동 모델의 실용성을 고찰하였다. METRO-K를 사용한 평가결과에서 방사성물질의 오염 후 신속한 대응행위는 무엇보다 중요하다는 것을 알 수 있었다. EMRAS 프로그램에 참여한 각기 다른 모델로 평가된 예측값의 차이는 1) 모델의 수학적 구조와 관련 변수값, 2) 모델에 반영된 피폭경로, 3) 피폭영향을 주는 오염표면의 종류, 표면의 넓이 등과 같은 평가에 대한 가정, 4) 각기 다른 문헌으로부터 선택된 대응행위 관련인자의 적용값 등의 차이에 기인하였다. METRO-K을 사용하여 EMRAS 프로그램에서 요구하는 다양한 오염 시나리오에 대해 대부분의 결과를 제출하여 상호 비교되었으며, 이를 통해 METRO-K는 만일의 도시환경 방사능오염으로 인한 대응행위 결정지원에 유용한 도구가 될 수 있음을 확인하였다.

• 한국습지학회지
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• 제9권1호
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• pp.79-89
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• 2007

This paper provides a comprehensive overview of the present status of several environmental problems caused by emerging toxic substances such as persistent organic pollutants (POPs), endocrine disrupting chemicals (EDCs), and arsenic in various environmental media in Vietnam. Monitoring data reported during the 1990s demonstrated elevated contamination of DDTs in most of these compartments in Vietnam. Studies in frame of the Asia-Pacific Mussel Watch Program revealed that fish, mussels and resident birds from Vietnam contained higher concentrations of DDTs as compared to other countries in region, suggesting the role of Vietnamese environment as a significant emission source of DDT in the Southeast Asian region. The estimated dietary intakes of PCBs and DDTs for Vietnamese were relatively high among Asian developing countries, suggesting potential risk for humans posed by thesechemicals. Widespread contamination of some endocrine active compounds such as alkylphenols and phthalates was observed at various sites along the coasts of northern and middle Vietnam. The presence of significant source of bisphenol-A along Red River estuary was revealed with the concentrations comparable to those reported for developed nations. A case study on seasonal variation of alkylphenols and phthalates in surface water of river delta and estuary of north and middle Vietnam indicated the differences in distribution of these compounds between dry and rainy seasons. Higher concentrations of alkylphenols and phthalates were found in dry season in estuary; while the contrasting pattern was observed in the river delta, showing elevated residues in rainy season. This result suggests the different behavior of alkylphenols and phthalates in river delta and coastal environment. From ecotoxicological perspectives, concentrations of bis-phenol A and di(2-ethylhexyl)phthalates [DEHP] in surface water from some locations in Vietnam exceeded the guideline values for Ecotoxicological Effects and the Environmental Risk Limit, respectively, suggesting potential for toxic implications on aquatic wildlife. Widespread and elevated arsenic contamination was discovered inour recent surveys in groundwater in a large area of suburban areas of Hanoi city, the capital of Vietnam. The most recent investigation in 4 villages showed about more than 50 % of groundwater samples contained As concentrations exceeding 50 g/L (the WHO and Vietnamese standard). In particular, in Son Dong villages, 58 % of samples analyzed contained As concentrations higher than 200 g/L. Good correlations were found in As concentrations in water and hair and urine of peoples in corresponding families, suggesting the chronic exposure to As by people living in As-contaminated ground water areas. In Son Dong village, As levels in hair (mean: 1.7 mg/kg dry wt) and urine (g/g creatinine) exceeding the reference values recommended by WHO, suggesting potential for human risk posed by long term accumulation of As in human body. Future studies should be focused on the time trends of POPs and EDCs in biota in Vietnam in order to predict future trend of contamination and to reveal new clues for understanding possible toxic impacts on aquatic organisms. The issues of arsenic contamination in groundwater and their chronic toxic implications on human health should be systematically investigated in the future.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2000년도 전력전자학술대회 논문집
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• pp.581-586
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• 2000

Gas metal arc welding(GMAW) uses a continuously fed electrode as a filler metal. The arc is shielded from atmospheric contamination by an inert gas active or inert/active gas mixture delivered through the welding gun and cable assembly. The recent research topics on $CO_2$ are welding machines are focused mainly on the reduction method of generated spatter by using new type consumable electrode metal or inverter control method. The various current waveform control methods have been researched for welding performance improvement. Until now current waveform control methods reduce to spatter occurred by instantaneous short circuiting,. but these methods is drawback that no reduce spatter occurred by arc reignition. In this paper the previous arc reignition current control method for welding performance improvement of inverter arc welding machine is studied and compared the various current control methods with the previous arc reignition current control method.