• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.1175-1177
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• 2003

In this paper, an application of the ZVT-PWM(zero-voltage-transition) boost converter, which has great advantage on miniaturization and high power density, to the power factor correction circuit of the EFL(electrodeless fluorescent lamp) inverter is studied. The operation principles of the converter are described to identify the power factor correction characteristic of the inverter. Experimentally obtaining the high power factor above 0.99, it is verified that the power factor correction of the EFL inverter successfully achieved.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2000년도 제32회 추계학술대회 정기총회
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• pp.280-288
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• 2000

In this study, flow factors are evaluated in terms of kurtosis using random rough surface generated numerically. As h/$\sigma$become large øx, øy, øfp approach to 1 and øs, øfs to 0 asymptotically regardless of kurtosis. øx, øy, øfp increase with increasing kurtosis in the mixed lubrication regime. øs, øfs is associated with an additional flow transport due to the combined effect of sliding and roughness. As h/$\sigma$ decreases øs, øfs increase up to a certain point, and then decrease toward zero. This behavior can be attributed to the increasing number of contacts in the mixed lubrication regime. øx in the presence of elastic deformation on the surface is larger than øx in the absence of it because local film thickness( h$\_$T/) increases by elastic deformation.

• Bulletin of the Korean Chemical Society
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• 제14권1호
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• pp.38-42
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• 1993

Factor analysis was applied to study the thermal decomposition of barium titanyl oxalate (BTO) which is used as the precursor of barium titanate. BTO was synthesized in $H_2O$ solvent and calcined at various temperatures. The X-ray diffraction patterns were obtained to make the data matrix of peak intensity vs. 2${\theta}$. Abstract factor analysis and target transformation factor analysis were applied to this data matrix. It has been found that the synthesized BTO consists of the crystals of $BaC_2O_4{\cdot}0.5H_2O\;and\;BaC_2O_4{\cdot}2H_2O$ as well as the amorphous solid of TiO-oxalate. The results also indicate that the BTO was transformed via $BaCO_3\;to\;BaTiO_3\;and\;Ba_2TiO_4$ during the thermal decomposition.

• 대한환경공학회지
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• 제36권8호
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• pp.534-541
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• 2014

본 논문은 먹는물 처리공정에 적합한 고도산화공정 중 하나인 자외선/과산화수소공정의 효율적인 운전을 위한 최적 운전 조건을 도출하는 방법을 연구하였다. 자외선/과산화수소 공정에서 대상물질의 제거효율을 예측하고 그에 따른 운전조건을 도출하기 위한 핵심 인자인 수산화라디칼 소모인자를 보다 쉽고 빠르게 측정하기 위해 새로운 지표물질인 로다민 비(Rhodamin B, RhB)를 선정하여 검증하였다. 그 결과, 기존 지표물질인 para-Chlorobenzoic acid (pCBA)와 비교해 약 1.1% 이하의 오차율로 높은 신뢰성을 가진 것을 확인하였다. 검증된 RhB를 이용하여 측정한 수산화라디칼 소모인자 및 모델링을 통해 대상물질(Ibuprofen)의 제거효율 예측 가능성을 평가한 결과, 실제 실험값과 평균 오차율 약 5% 내외로 거의 일치하였다. 약 8개월간의 자외선/과산화수소공정 파일럿 플랜트 유입수의 수산화라디칼 소모인자 모니터링 결과, 최대 두 배 정도의 차이로 크게 변화하였다. 이 차이는 미량오염물질 중 하나인 Caffeine의 목표 제거율을 만족하기 위한 자외선 에너지를 약 1.7배 증가시켜야 할 정도로 큰 값이다. 이상의 결과를 통해 자외선/과산화수소 공정을 안전하고 효율적으로 운전하기 위해서는 수산화라디칼 소모인자의 측정이 매우 중요하며, 측정된 소모인자, 자외선 흡광도($A_{254}$), 대상물질의 정보만 입력하면 자외선/과산화수소 공정을 쉽게 제어할 수 있음을 확인하였다.

• 한국발생생물학회:학술대회논문집
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• 한국발생생물학회 2003년도 제3회 국제심포지움 및 학술대회
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• pp.102-102
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• 2003

Embryonic stem (ES) cells proliferate extensively in the undifferentiated state and have the potential to differentiate into a variety of cell types in response to various environmental cues. The generation of functional dopaminergic neurons from ES cells is promising for cell replacement therapy to treat Parkinson's disease. We compared the in vitro differentiation potential of pluripotent human embryonic stem (hES, MB03) cells induced with basic fibroblast growth factor (bFGF) or retinoic acid (RA). Both types of treatment resulted in similar neural cell differentiation patterns at the terminal differentiation stage, specifically, 75% neurons and 11% glial cells. Additionally, treatment of hES cells with brain derived neurotrophic factor (BDNF) or transforming growth factor (TGF)- $\alpha$ during the terminal differentiation stage led to significantly increased tyrosine hydroxylase (TH) expression, compared to control (P<0.05). In contrast, no effect was observed on the rate of mature or glutamic acid decarboxylase-positive neurons. Immunostaining and HPLC analyses revealed the higher levels of TH (20.3%) and dopamine in bFGF and TGF-$\alpha$ treated hES cells than in RA or BDNF treated hES cells. The results indicate that TGF-$\alpha$ may be successfully used in the bFGF induction protocol to yield higher numbers of functional dopaminergic neurons from hES cells.

• Journal of Microbiology and Biotechnology
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• 제16권12호
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• pp.1940-1946
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• 2006

The influence of environmental conditions on the ganoderic acid (GA) content in the fungus Ganoderma lucidum was investigated using a one-factor-at-a-time design and orthogonal design. Among the various medium components examined, sucrose, soybean powder or peptone, ferrous sulfate, and pH 6.0 were the most suitable carbon source (factor A), nitrogen source (factor B), mineral source (factor C), and initial pH (factor D), respectively, for the GA content in the one-factor-at-a-time design. According to the orthogonal design, the order of effect for the four factors on the GA content was A>C>D>B. The best level of factor A was $A_2$ (sucrose) with a value of +0.34 mg/100 mg DW. The optimal treatment combination was $A_2B_1C_3D_1$ with which the GA content reached up to 2.63$\pm$0.011 mg/100 mg DW. The interactions between the mineral ion and the nitrogen source, and the mineral ion and the pH were both highly significant (P<0.01). The highest interaction effect was ($B_2{\times}D_2$) with a value of +0.19 mg/100 mg DW, which was higher than the level effect value for $B_2$ (peptone) and D$_2$ (pH 5.0). Therefore, the results proved that interactions between factors cannot be ignored. The results also indicated the importance of the interactions between the factors, which may help to understand the metabolic pathway leading to triterpene biosynthesis and the expression and regulation of the key enzymes involved.

• 한국대기환경학회지
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• 제15권4호
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• pp.385-392
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• 1999

This study was carried out to investigate the constituents of inorganic ions of precipitation in Mokpo and Yeochon area from Jan. 1996 to Dec. 1997. The volume-weighted mean pH of precipitation was 5.7(4.8~7.8) at Mokpo, and 5.6(5.1~7.4) at Yeochon area, respectively. The non-seasalt(nss) anion concentrations were found in order of $nss-SO^{2-}_4>NO^-_3>nss-Cl^-$ at two areas. The portion of $nss-SO^{2-}_4;and;NO^-_3$ was 71~84% out of anions. The the non-seasalt cation concentrations were found in order of $NH^+_4>nss-Ca^{2-}>nss-Mg^{2+}>nss-K^-$ at two areas. The portion of $NH^+_4;and; nss-Ca^{2+}$ was 85~92% out cations. Compared regionally the year concentraton of $nss-SO^{2-}_4$, the result of Yeochon was 3 times higher than that of Mokpo in 1996, while the results of two regions were almost similar in 1997. The reason was that Yeochon was restricted area of the use of 0.5% sulfur B-C oil, controlled air pollution emission area, controlled semitotal amounts of air pollution emission area and partial operating of factories in 1997. There were no ions having high correlation with $H^+,;but;nss-SO^{2-}_4,;NO^-_3,;NH^+_4;and;nss-Ca^{2+}$ showed high correlation coefficient each other. It seems that these ions have little correlation with $H^+$ because they are washed out on binding state. Factor analysis showed that the first factor was complicated factor containing anthropogenic and soil resource, the second factor was sea-salt resource and the third factor was independent behavior of hydrogen at Mokpo. While, the first factor was complicated factor containing anthropogenic and sea-salt resource, the second factor was $Ca(NO_3)_2$ salt and the third factor was $NH^+_4;and;SO^{2-}_4$ synergied by resource and combination at Yeochon.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2000년도 제31회 춘계학술대회
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• pp.243-250
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• 2000

In the partial lubrication regime, the roughness effects are most important due to the presence of interacting asperities. An average Reynolds equation using flow factors is very useful to determine effects of surface roughness on partial lubrication. In this paper, the pressure flow factors for Gaussian and non-Gaussian surfaces are evaluated in terms of kurtosis. The effect of kurtosis on pressure flow factor is investigated using random rough surface generated numerically. The pressure flow factor increases with increasing kurtosis in partial lubrication regime(h/$\sigma$<3). As h/$\sigma$increases, the pressure flow factor approach to 1 asymptotically regardless of kurtosis.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 춘계학술대회 논문집
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• pp.290-292
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• 2008

we applied Wind Field Module of PHRLM so that disaster prevention agency concerned can effectively estimate the possible strong wind damages by typhoon. In this study, therefore, we estimated wind speed at 300m level using 700hPa wind according to the research method by Franklin(2003), PHRLM(2003), and Vickery and Skerlj(2005). Then we calculated wind speed at 10m level using the estimated wind speed at 300m level, and finally, peak 3.second gust on surface. The case period is from 18LST August 31 to 03LST September 1, 2002, when the typhoon Rusa in 2002 was the most intense. Among disaster prediction models in the US, Wind Field Module of PHRLM in Florida was used for the 2002 typhoon Rusa case. As a result, peak 3.second gust on the surface increased $10\sim20%$ in the typhoon's 700hPa wind speed.

• 전자공학회논문지B
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• 제33B권2호
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• pp.20-27
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• 1996

In this paper, we propose a coprime factor model reduction method to get a reduced order controller in $H^{\infty}$ mixed sensitivity problem with frequency weighting functions. for this purpose, the given $H^{\infty}$ mixed sensitivity problem is transformed into robust stabilization problem with coprime factor uncertainty of given plant. This method is to define frequency weighted coprime factors of plant in CSD (chain scattering description) form and reduce the coprime factors using weighted balanced truncation. then a controller is designed to the reduced order coprime factors using J-lossless coprime factorization method. Using this approach, the robust stability condition is derived and good performance is preserved in closed loop system with the given plant and the reduced order controller. Also the order of reduced controller for guaranteeing the robust stability can be determined before designing the reduced controller. The proposed method behaves well in both stable and unstable plant.