• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.422-422
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• 2021

현대사회에서 플라스틱의 요구량은 꾸준히 증가하고 있으며 이에따라 생산량 역시 맞춰 증가하고 있다. 이에 따라 전세계적으로 플라스틱으로 인해 발생하는 폐기물의 양 역시 증가하고 있으며 이로 인해 플라스틱 재질의 폐기물이 많아지고 있다. 이 중 가장 문제가 되는 폐기물이 바로 미세플라스틱이다. 미세플라스틱은 1㎛ ~ 5mm 미만의 플라스틱으로 그 물리 화학적인 특성으로 인해 회수가 어려우며 외부 환경에 잔류시 독성을 유발할 수 있다. 플라스틱의 약한강도와 열악한 내열성 그리고 유기용매에 취약하다는 단점을 보완하기 위해 첨가하는 화학물질로 인해 내분비계교란물질을 발생시켜 생명체의 내분비계를 교란시켜 최종적으로 성기능장애를 유발한다. 또한 미세플라스틱의 표면은 유기염류성 살충제와 같은 잔류성오염물질(POPs persistent organic pollutants)사이의 흡착성이 크기 때문에 미세플라스틱은 POPs 농도를 주변보다 최대 백만배 높게 만들 수 있다. 미세플라스틱의 분석은 표준화된 방식이 없어서 제각각이지만 대체로 미세플라스틱 표면에 응집된 유기물을 처리하는 전처리, 미세플라스틱의 농도를 분석하는 정량분석, 그리고 미세플라스틱의 성분을 분석하는 정성분석의 과정을 거쳐서 진행된다. 이러한 미세플라스틱의 분석법을 기반으로 하수처리장에 유입되는 하수의 미세플라스틱 분석방법을 제안하면 다음과 같다. 우선 유입수로부터 미세플라스틱을 따로 분리하기 위해 체거름을 진행했다. 이후 유입하수의 성상에 맞는 적정 전처리 방법을 알아내기 위해 유기물을 제거하기 위한 산화방식으롷서 과산화수소수, 80℃의 과산화수소수, 그리고 펜톤산화의 서로 다른 3가지 방식을 사용했다. 이후 이어지는 정량분석과 정성분석결과를 비교하여 유입하수에 가장 최적인 미세플라스틱 측정방법을 알아보고자 한다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2023.11a
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• pp.175-176
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• 2023

1973년 최초로 서비스를 시작한 GPS는 전 세계 60억명 이상이 사용 중이며 거의 모든 사업에 큰 영향을 미치고 있으며, 자동차, 농업, 해양, 일반 안전, 레저활동, 지형공간정보, 항공, 금융, 통신 등 산업 전반에 걸쳐 경제적 이익이 약 1조4천억 달러에 이르는 글로벌 시스템이라 할 수 있다. 최근에는 미국의 GPS 뿐만 아니라 유럽, 러시아, 중국 등 세계 주요국들은 자국의 독자 위성항법시스템을 구축하고 있으며, PNT 정밀성 향상을 위한 위성항법보강시스템의 개발 또한 주요국 중심으로 이루어지고 있다. 4차산업기술의 발달로 인해 다양한 산업의 상용화와 대중화에 따라 PNT 정보의 고정밀, 고신뢰에 대한 수요도 급증하고 있으며, 이에 대한 응용기술 분야에 대한 시장도 급속하게 성장하고 있다. 우리나라에서도 KASS와 같은 위성항법보강시스템 구축을 추진하고 있으며, 향후 독자 위성항법시스템인 KPS의 개발도 진행중에 있다. 그러나 고도 23,000km에서 송출하는 위성신호의 전파교란·기만에 대한 취약성과, 도심지와 같은 위성신호 수신이 열악한 환경에서는 고정밀·고신뢰 PNT 정보를 제공하기가 현실적으로 어려운 실정이다. 이러한 GPS의 취약성을 보완하기 위해 지상기반의 PNT 정보제공 시스템 구축의 필요성이 증대되고 있으며, 전세계적으로 상호보완적 PNT 시스템의 구축·기술개발에 대한 연구가 다양하게 이루어지고 있다.

• Journal of the Korean Data and Information Science Society
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• v.28 no.1
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• pp.109-117
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• 2017

This study aims to identify the effect for exercise intensity on hypertension using propensity score based on the sixth Korea National Health and Nutrition Examination Survey data and to provide an evidence for the most effective exercise intensity for prevention or treatment of hypertension. Specifically, we select 3,486 subjects who aged between 18 and 65 years after excluding some subjects who are expected to have limited athletic ability. We estimate propensity scores for exercise intensity based on the confounders such as sex, age, smoking, drinking, and natrium intake. Considering the complex survey design, we conduct a descriptive analysis and multiple logistic regression for hypertension with propensity score as a covariate. Although the results of the study did not show statistically significant relationship between exercise intensity and hypertension, we expect that it can be used as a basis evidence that the appropriate exercise of moderate intensity may be more effective for the prevention and treatment of hypertension rather than strong intensity exercise and non-exercise.

• Weed & Turfgrass Science
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• v.7 no.3
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• pp.219-229
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• 2018

We isolated Streptomyces scopuliridis KR-001 that produced herbicidal active metabolite(s) against several grass and broad leaf weeds. In this study, potential as natural herbicide of mutant N-29 broth filtrate of S. scopuliridis KR-001 was investigated to Ambrosia artemisiifilia in a greenhouse and field condition. The broth filtrate of mutant N-29 by foliar application showed a strong herbicidal activity to A. artemisiifilia with leaf stage in a greenhouse condition. Also, field trial of foliar application within treatment range had effectively controlled with early and middle stage of A. artemisiifilia at the natural habitats. Phytotoxic symptoms of mutant N-29 broth filtrate by foliar application were wilting and discoloration, and burn-down of leaves and finally plant death. These results suggest that mutant N-29 broth filtrate is considered possible as a natural herbicide for controlling environmentally friend to invasive alien plant such as A. artemisiifilia and may provide a new lead molecule for a more efficient herbicide.

• The Korean Journal of Pesticide Science
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• v.7 no.3
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• pp.188-197
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• 2003

Endocrine disrupting chemicals (EDCs) can alter hormone regulation that control reproductive system in animals. The effects of endosulfan, molinate, and alachlor that suspected to have examined disruption EDCs effect on a fish species of interest, Xiphophorus helleri (swordtail fish), were studied using vitellogenin (Vtg) and aromatase as diagnostic biomarkers. Induction of Vtg proteins was detected by RT-PCR in male fish treated with alachlor, and mixture of endosulfan and molinate in dose response manner. Also, induction of aromatase was detected by RT-PCR in male fish treated with alachlor, endosulfan, and mixture of endosulfan and molinate in sinlilar manner. In this study, swordtail fish exposed to endosulfan or molinate individually did not show any adverse effects. However, Vtg and aromatase expressions and apoptosis were detected in swordtail. fish exposed to the mixture of endosulfan and molinate. These results suggested that low concentrations of mixture of molinate and endosulfan individually do not affect swordtail fish, but may influence genital system, and induce apoptosis.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.11
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• pp.65-73
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• 2005

The compressible flow of reactive fluid is investigated by using the transonic small-disturbance (TSD) model and the one-step first-order Arrhenuis chemical reaction. The fluid flow is restricted to dilute premixed reactions with small heat release. The effects of channel shape and Mach number on transonic combustion are studied by numerical analysis. The results show that the channel divergence increases the chemical reaction within the given channel length whereas the channel convergence inhibits the chemical reaction near the outlet and that increasing the inlet flow Mach number at a fixed reaction rate causes the flow acceleration in a diverging channel and the appearance of weak shock waves which do not show in the inert flow case. It also helps to increase the pressure and temperature near the diverging channel outlet and to consume the reactant within the given channel length.

• Journal of Korean Society of Forest Science
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• v.102 no.3
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• pp.355-364
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• 2013

This study was conducted to investigate the population structure and dynamics of the Picea jezoensis stands which are located in Mt. Gyebangsan and surveyed from March to October 2012. Results showed that the diameter class distribution of P. jezoensis presented a reverse J-shaped distribution pattern with 32 trees less than 10 cm DBH, 20 trees in 10~30 cm DBH, and 11 trees more than 30 cm DBH. It showed seedlings and saplings of P. jezoensis seem to prefer areas with more sun light or with open upper layer. It was also observed that P. jezoensis preferes areas with organic soils and abundant water such as areas around stumps. Also, occurrences of P. jezoensis stands were analyzed through annual mean radial growth of the trees. And the results showed that the growth naturally or artificially occurred approximately on the years 1854, 1915, 1918, 1993 and 2002 years. Most of the gap-makers were classified as standing dead type with 23 individuals (45.1%).

• Korean Journal of Ecology and Environment
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• v.38 no.3 s.113
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• pp.289-296
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• 2005

The fish fauna and community structure at 20 stations in streams of the Mt. Biseul were investigated from June 2003 to May 2004. During the study period, 29 species, 25 genera belonging to 9 families were collected. Cyprinid fish occupied 48.3% (14 species) and cobitid fish had 13.8% (4 species). Six species (22.2%) were korean endemic and two species of Micropterus salmoides and Lepomis macrochirus were exotic. It was found that the population density of carnivorous fish (Opsariichthys uncirostris amurensis) increased in the lower-reach of small streams in the Mt. Biseul area since it had been introduced from the other native rivers in the middle 1990s. As the result of analyzing fish community in the surveyed area, the species diversity ranged from 0.553 to 1.023. The findings showed that the Geumpo, Chacheon and Hyeonpung streams had higher species diversity indicies of 0.936 ${\sim}$ 1.023 than the Sincheon and Gisegok streams with 0.553 ${\sim}$ 0.727.

• Journal of Radiation Protection and Research
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• v.20 no.2
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• pp.123-128
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• 1995

The concentration of Cs-137 and Sr-90 has been analyzed in soils around Taejon region. A correalation was found between the concentration of Cs-137 and the organic matter content. The mean value of Cs-137 was 14.37Bq/kg-dry and that of Sr-90 was 7.95Bq/kg-dry in undisturbed soils around Taejon region. The concentration ratio of Cs-137/Sr-90 was 1.99. The distribution of Cs-137 and Sr-90 was similar to cumulative fallout level and had been more affected by nuclear weapons test than by the chernobyl accident.

• Korean Journal of Plant Taxonomy
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• v.47 no.4
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• pp.322-327
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• 2017

We report the distribution of Sparganium subglobosum Morong (Typhaceae) for the first time in Korea. Sparganium subglobosum is readily distinguishable from other Korea Sparganium species by having a short plant height, narrow leaves (${\leq}4mm$), thin inflorescence branches, and a ripe fruiting head globose and ca. 1 cm in diam. The species is under great threat of local extinction due to a recent disturbance of one of only two known distribution sites. Further conservation plans for S. subglobosum and surveys are needed. We provide a revised key to five Sparganium species of Korea, with descriptions, pictures, and figures of S. subglobosum.