• Advances in environmental research
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• 제6권1호
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• pp.53-65
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• 2017

Assessment of seasonal changes in surface water quality is an important aspect for evaluating temporal variations of river pollution due to natural or anthropogenic inputs of point and non-point sources. In this study, surface water quality data for 15 physico-chemical parameters collected from 7 monitoring stations in a river during the years from 2014 to 2016 were analyzed. The principal component analysis technique was employed to evaluate the seasonal correlations of water quality parameters, while the principal factor analysis technique was used to extract the parameters that are most important in assessing seasonal variations of river water quality. Analysis shows that a parameter that is most important in contributing to water quality variation for one season may not be important for another season except alkalinity, which is always the most important parameters in contributing to water quality variations for all three seasons.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 춘계학술대회 논문집 센서 박막재료연구회 및 광주 전남지부
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• pp.91-97
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• 2008

Polymers submitted to thermo/electrical stress suffer from ageing that can drastically affect their functional behaviour. Understanding the physico/chemical processes at play during ageing and defining transport regimes in which these mechanisms start to be critical is therefore a prime goal to prevent degradation and to develop new formulation or new materials with improved properties. It is thought that a way to define these critical regimes is to investigate under which conditions (in terms of stress parameters) light is generated in the material by electroluminescence (EL). This can happen through impact excitation/ionization involving hot carriers or upon bi-polar charge recombination (a definition that excludes light from partial discharges, which would sign an advanced stage in the degradation process). After a brief review of the EL phenomenology under DC, we introduce a numerical model of charge transport postulating a recombination controlled electroluminescence. The model output is critically evaluated with special emphasize on the comparison between simulated and experimental light emission. Finally, we comment some open questions and perspectives.

• 한국환경과학회지
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• 제11권4호
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• pp.339-346
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• 2002

Physico-chemical properties of the activated sludges(Suyoung and Changlim treatment plant), such as SVI(sludge volume index), absorbance, specific surface area, and specific resistance using Buchener funnel test were investigated with changing anaerobic storage time. This experimental condition was found that it was possible to estimate a linear relationship between their parameters such as specific surface area specific resistance, and sludge volume index(SVI). The specific surface area and the specific resistance to filtration of the activated sludges of Suyoung and Changlim treatment plant were found as 123.6~136.6$m^2$/gDS and 41.5~44.9$m^2$/gDS(dry solid), and 1.09$\times$10$^{14}$ ~5.48$\times$10$_{14}$ m/kg and 1.05$\times$10$^{14}$ ~2.48$\times$10$^{14}$ m/kg, respectively. The results gave a good linear relationship between the specific surface area and the specific resistance, r=2.25$\times$10$^{12}$ s-8.10$\times$10$^{13}$ ($R^2$=0.8885) at Suyoung treatment plant and r=1.26$\times$10$^{13}$ s-4.75$\times$10$^{14}$ ($R^2$=0.8756) at Changlim treatment plant.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.351-352
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• 2007

Polymers submitted to thermo/electrical stress suffer from ageing that can drastically affect their functional behaviour. Understanding the physico/chemical processes at play during ageing and defining transport regimes in which these mechanisms start to be critical is therefore a prime goal to prevent degradation and to develop new formulation or new materials with improved properties. It is thought that a way to define these critical regimes is to investigate under which conditions (in terms of stress parameters) light is generated in the material by electroluminescence (EL). This can happen through impact excitation/ionization involving hot carriers or upon bi-polar charge recombination (a definition that excludes light from partial discharges, which would sign an advanced stage in the degradation process). After a brief review of the EL phenomenology under DC, we introduce a numerical model of charge transport postulating a recombination controlled electroluminescence. The model output is critically evaluated with special emphasize on the comparison between simulated and experimental light emission. Finally, we comment some open questions and perspectives.

• 한국생명과학회:학술대회논문집
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• 한국생명과학회 2007년도 제48회 학술심포지움 및 추계국제학술대회
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• pp.107.2-107.2
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• 2007

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• 한국물환경학회지
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• 제26권1호
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• pp.10-18
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• 2010

Water quality and the distribution of ammonia oxidizing bacteria were characterized in constructed wetland of Shihwa lake. Both physico-chemical parameters and fecal indicator microorganisms including total coliforms, E.coli, Enterococcus spp. were measured. In addition, denaturant gradient gel electrophoresis (DGGE) was carried out after PCR amplification of amoA gene from input, output, and wetland sites of the Banwol, Donghwa, and Samhwa stream in Shihwa lake area. Physico-chemical parameters were in proper range for typical nitrifying bacteria to grow and perform their biological activities. Average concentrations of fecal indicator microorganisms of wetland samples were lower than those of input sites. These results suggested that microbial water quality improved by the process of constructed wetland. According to phylogenetic information obtained from DGGE from study sites, distribution of nitrifying bacteria from each of input, output, and wetland were generally distinctive one another. In addition, distribution of nitrifying bacteria between Banwol and Donghwa streams showed higher similarity (52.6%) than this of Samhwa stream (15.2%). These results indicated that characteristics of ammonia oxidizing bacteria in Samhwa were unique in comparison with those of Banwol and Donghwa stream.

• 생약학회지
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• 제36권3호통권142호
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• pp.209-219
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• 2005

In this study, we carried out the preparing standardization and regulation of processed Glycyrrhizae Radix (PGR) which have been widely used in oriental medicines. Glycyrrhizae Radix(GR) have been generally prepared by the stir-frying, or mix-frying with honey for the purpose of decreasing sweetness and augmenting vitality. Firstly, we tried to standardize PGR prepared by the stir-frying. We purchased 14 kinds of PGR and non-processed GR(NPGR) at oriental physician's offices and oriental pharmacies on a nation scale, respectively. The amounts of dry on loss, water extract, diluted ethanol extract, ether extract, total ash, acid insoluble ash, glycyrrhizin(GL), glycyrrhetic acid(GA) and liquiritin(LQ) of them were examined. The amounts of dry on loss, GL and LQ in commercial PGRs showed remarkable decrease, while GA showed increased as compared with NPGR. In order to standardize preparing method of PGR, the effect of heating time on physico-chemical parameters and biological activities were examined. Physico-chemical parameters such as dry on loss, extract amount, GL and LQ contents in PGRs showed decrease, however, GA was increased with heating time as compared with NPGR. Also, GA, obtained from heat-treated GR, was found as an artifact in PGRs. PGR was more effective than NPGA in vitro test of DPPH scavenging effect and TBA-Rs reducing effect. PGR and NPGR showed potent hepatoprotective effect on $CCl_4-intoxicated$ rats. Especially, PGR prepared by 80 min of heating was the most effective. Considering these results, the optimal condition for PGR preparation was $150^{\circ}C$ for 80 min.

• 한국해안해양공학회지
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• 제18권4호
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• pp.283-293
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• 2006

본 연구의 목적은 금강 하구역 표층에 분포하는 점착성 퇴적물의 침식특성을 정량적으로 산정하고, 그 침식특성의 계절적 변화와 타 지역 침식특성 결과와의 비교/분석을 통한 공간적 변화를 해석하는데 있다. 또한 점착성 퇴적물의 침식특성은 퇴적물 자체의 물리 화학적 기본특성에 의해 크게 영향을 받으므로, 본 연구에서는 이러한 퇴적물의 기본특성이 침식특성에 미치는 영향에 대해서도 해석하였다. 침식실험은 균일저면 조건에서 1개 지점에 대해 계절별로(가을과 겨울) 4회씩 총 8회의 실험이 환형수조를 사용하여 수행되었으며 그 결과 저면밀도 $1.15{\sim}1.34g/cm^3$ 범위에서 침식한계전단응력(${\tau}_{ce.s}$)은 $0.12{\sim}0.36N/m^2$, 침식률 계수(${\varepsilon}_{M.S}$)는 $120.91{\sim}6.72mg/cm^2{\cdot}hr$ 범위의 값을 갖는 것으로 확인되었으며, 산정된 침식특성 매개변수들은 다른 점착성 퇴적물(Okeechobee호, Kaolinite)과 비교해 정량적으로 상당한 차이를 보였으나 금강 하구역 내에서의 계절적 변화는 미미한 것으로 나타났다.

• 대한토목학회논문집
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• 제28권1B호
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• pp.125-135
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• 2008

본 연구의 목적은 금강하구의 표층에 분포하는 점착성 퇴적물의 침식매개변수를 정량적으로 산정하는 것이다. 또한 본 연구는 침식매개변수들의 금강하구역 내에서의 지엽적 계절적 변화에 대한 조사와 타 지역 분석 결과와의 비교/분석을 통한 공간적 변화에 대한 조사를 포함한다. 점착성 퇴적물의 침식특성은 기본적으로 퇴적물 자체의 물리 화학적 특성에 의해 크게 영향을 받으므로, 본 연구는 또한 퇴적물의 이러한 기본특성이 침식특성에 미치는 영향에 대한 정성적 분석을 포함한다. 침식실험은 전북대 환형수조를 이용하여 균일저면 조건하에서 수행되었으며, 저면밀도와 바닥전단응력을 변화시키면서 총 16회의 실험이 수행되었다. 실험결과에 따르면, 금강하구역 점착성 퇴적물은 저면밀도 $1.14{\sim}1.38g/cm^3$ 범위에서 침식한계전단응력(${\tau}_{ce,s}$)은 $0.19{\sim}0.41N/m^2$, 침식률 계수(${\varepsilon}_{M,s}$)는 $54.26{\sim}7.70mg/cm^2{\cdot}hr$ 범위의 값을 갖는 것으로 나타났다. 또한 산정된 침식 매개변수들은 타 지역 점착성 퇴적물과 비교시 정량적으로 그 값이 크게 다른 것으로 나타났으나, 금강하구역 내에서의 지엽적/계절적 변화는 미미한 것으로 나타났다.

• Natural Product Sciences
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• 제11권4호
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• pp.213-219
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• 2005

The leaves of Annona squamosa Linn. (Annonaceae), commonly called as custard apple, are popularly used for the treatment of diabetes by various tribes in India. The leaves are also used for their powerful insecticidal activity, especially for destroying lice. This paper present a detailed pharmacognostical study of the crude drug folium Annona squamosa. The samples were studied using procedures of light, confocal microscopy, WHO recommended physico-chemical determinations and authentic phytochemical procedures. The physicochemical, morphological and histological parameters presented in this paper may be proposed as parameters to establish the authenticity of Annona squamosa leaf and may possibly help to differentiate the drug from its adulterants.