• International Journal of Industrial Entomology and Biomaterials
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• 제27권2호
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• pp.282-288
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• 2013

In nature, the population of Nosema bombycis (Microsporidia) causing pebrine disease is small and their development is extremely slow and only few ultimately producing spores. Pebrine infected silkworm, Bombyx mori larvae collected from sericulture field were alive till $3^{rd}$ generation though the concentration of N.bombycis spore was very high ($2.4-3.0{\times}10^8$ spores. $mL^{-1}$). All larvae were died during $4^{th}$ generation with extremely high concentration of pebrine spores ($3.0-4.0{\times}10^9$ spores. $mL^{-1}$) and mostly contain long polar tube (LT). Alternately, all larvae were died immediately (at $3^{rd}$ stage of $1^{st}$ generation) when it was artificially inoculated with same concentration of N.bombycis spores harvested from field ($2.4-3.0{\times}10^8$ spores. $mL^{-1}$) though concentration of spores harvest was very less ($3.0-4.0{\times}10^6$ spores. $mL^{-1}$) and mostly contain short polar tube (ST). Artificially pebrine infected male moth when mated with healthy female moth took six generations to develop pebrine disease and all larvae were died at the $2^{nd}$ stage with very less spore harvest ($3.0-10.0{\times}10^6$ spores. $mL^{-1}$). Survival percentage was increased in all generations (~92.0% at $4^{th}$ generation) when silkworm rearing was conducted under new integrated disease management system.

• 한국해안해양공학회지
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• 제14권2호
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• pp.108-115
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• 2002

만경강·동진강 유역의 오염물질 유출모형을 수립·적용하였다. 모형의 입력자료인 유역정보 및 오염원 정보는 GIS도구를 이용하여 추출·분석한 자료를 이용하였으며, 월별 유출량 및 하천의 오염물질 농도 관측자료와 모형의 계산결과를 비교·분석하였다. 분석결과, 유역유출량은 여름철에 약간 과소 추정하고 있으나 전체적인 변화경향은 일치하고 있다. 또한 모형에서 계산된 오염물질 농도는 10년 평균 수질자료와 1999년도 월별 수질자료를 이용하여 비교하였다. 그 결과, 익산천에서는 크게 과소 추정하고 있으나, 전체적으로는 양호한 정도로 일치하고 있는 것으로 파악되었다 익산천에서 과소 추정하는 이유는 오염퇴적물에 의한 국지적 영향으로 사료되며, 오염퇴적물이 수층에 미치는 영향을 규명하기 위해서는 하천의 퇴적물 오염도 관측·분석을 통한 심도깊은 연구가 수행되어야 할 것이다

• 한국자원식물학회지
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• 제18권1호
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• pp.198-206
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• 2005

애완견의 털에 부착되어 있는 세균을 분리 동정한 후, 이 분리 세균들에 대한 항세균효과가 있는 생약재 추출물을 탐색하였다. 애완견의 털에서 76개의 세균을 분리한 결과, Staphylococcus속이 41균주로 가장 많았으며 그 다음으로 Micrococcus속이 21균 주, Enterococcus속이 8균주, Bacillus속이 3균주, Exiguobacterium속 of 2균주, Shigella속과 Zoogloea속이 각각 1균주씩으로 동정되었다. 이러한 결과는 개의 털에 존재하는 세균들이 사람에게 감염을 일으킬 수 있는 원인이 될 수 있음을 시사한다. 분리균주들에 대한 항생제 저항성과 생약재 추출물의 항세균 활성은 디스크 확산법으로 확인하였다. 황금의 추출물이 애완견의 털로부터 분리한 세균들에 대해 높은 항세균 활성을 나타내어 항생제 저항성이 있는 세균들에 대한 새로운 항미생물제로 사용학 수 있을 것으로 기대된다.

• 한국세라믹학회지
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• 제49권6호
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• pp.608-613
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• 2012

We investigated the property changes of MgO powders sintered at temperatures ranging from $700^{\circ}C$ to $1900^{\circ}C$ for 5minutes at a pressure of 2.7 GPa for a high-pressure high-temperature(HPHT) diamond synthesis process. The physical properties of the sintered MgO powders were characterized by optical microscopy, field emission scanning electron microscopy (FE-SEM), Vickers hardness tests, and by the apparent density, and X-ray diffractometry. An optical micro-analysis showed that white MgO powders became black after sintering due to carbon contamination from the graphite heat source. FE-SEM revealed the growth in the grain size of the MgO powders from $0.3{\mu}m$ to $50{\mu}m$ after sintering at $1700^{\circ}C$. The hardness and apparent density increased to $1800^{\circ}C$ while the samples were dedensified at $1900^{\circ}C$ due to the growth of isolated pores. According to the XRD analysis, no phase transformation occurred in the MgO powders. These results suggest that HPHT-sintered MgO powders can show an accelerated sintering process characterized by grain neck growth, pore connections, isolated pore growth and dedensification in 5 minutes, while these processes with the conventional sintering process take at least 5 hours.

• 대한환경공학회지
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• 제22권1호
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• pp.149-157
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• 2000

깅릉 남대천 수계에서 처음으로 용존 비소(As)의 분포와 거동에 관한 연구가 수행되었다. 풍수기인 1997년 8월 28일(최종 방류량; $1.97{\times}10^6$ 톤/일)과 갈수기인 동년 11월 21일(최종 방류량; $0.13{\times}10^6$ 톤/0일). 두 차례에 걸쳐 조사된 As의 농도 분포는 같은 시기에 조사된 다른 중금속들과 다소 차이를 보인다. 도암댐 보다 오봉댐 유출수의 농도가 미소하게 높았고, 갈수기인 11월 하류부의 농도 급증현상도 나타나지 않았을 뿐 아니라 풍수기인 8월 하류부의 농도보다도 낮았다. 그리고 두 조사기간사이의 농도차가 미비하며, 원시적인 강들과 세계평균치에 비해서도 비교적 낮은 농도로서 남대천 수계에서는 As의 인위적인 오염원이 없고, 자연적인 배경농도(background level) 수준임을 알 수 있다. 하구에서 담수와 해수가 혼합되는 과정에서는 외부 유입이나 제거 기작없이 염분과 함께 직선적으로 증가하는 보존적인 분포를 보이며, 남대천을 통하여 동해로 유출되는 As의 양은 연간 65.12kg 정도이다.

• 한국환경농학회지
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• 제34권1호
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• pp.14-20
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• 2015

BACKGROUND: Contamination of source water by odorous compounds are one of the problems related to the water quality management, especially in Korea where surface water is used as drinking water. Geosmin (1, 10-trans-dimethyl-trans-9-decalol) and 2-MIB (2-methyl isoborneol : 1,2,7,7-tetramethyl-exo-bicycloheptan-2-ol) are commonly recognized earthy-musty odor compounds produced by algae causing serious problems to the drinking water purification facilities. METHODS AND RESULTS: In this study, spatial and temporal distribution of the odor compounds, geosmin and 2-MIB were investigated along with the development of phytoplankton in the Daechung reservoir from July 2012 to October 2013. CONCLUSION: Concentrations and frequencys of detection of both compounds increased from April to October which were related to cyanobacterial bloom periods. However, concentrations of odor compounds were not related to the number of cyanobacteria. Concentrations of both cyanobacteria and geosmin showed similar trends with depth. Pearson correlation analyses showed that geosmin concentration exhibited significant correlation with the count of Anabaena macrospora and Aphanizomenon flos-aquae. On the other hand, 2-MIB concentration showed a significant correlation with the count of Anabaena smithii.

• 대한지하수환경학회지
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• 제6권3호
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• pp.107-110
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• 1999

제주도 지하수중 질산염농도가 높은 지점을 선정하여 1995년부터 1996년까지 4차에 걸쳐 질소안정등위원소의 자연존재를 측정하고. 오염원별 기여율을 계산한 결과는 다음과 같다. 화학비료에 의한 영향이 뚜렸하게 나타나는 지점은 T-3, L-1. O-1∼O-4. F-2∼F-5. G-2의 11개소로써 화학비료 질소성분이 지하수 질산염농도 중 약 60% 이상을 차지하는 것으로 조사되었다. 그리고. 동물성 유기물질에 의한 영향이 많은 지하수는 T-4, T-5. G-2지점 3개소이며, T-4, T-5지점은 생활하수에 의한 영향으로, G-2지점은 쓰레기매립장 침출수의 영향으로 사료된다. 또한. 화학비료와 동물성 유기물질에 의한 영향을 비슷하게 받는 지하수는 T-1, T-2. L-2. F-1지점 4개소로 조사되었다.

• Mycobiology
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• 제45권4호
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• pp.240-254
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• 2017

Cereal grains are the most important food source for humans. As the global population continues to grow exponentially, the need for the enhanced yield and minimal loss of agricultural crops, mainly cereal grains, is increasing. In general, harvested grains are stored for specific time periods to guarantee their continuous supply throughout the year. During storage, economic losses due to reduction in quality and quantity of grains can become very significant. Grain loss is usually the result of its deterioration due to fungal contamination that can occur from preharvest to postharvest stages. The deleterious fungi can be classified based on predominance at different stages of crop growth and harvest that are affected by environmental factors such as water activity ($a_w$) and eco-physiological requirements. These fungi include species such as those belonging to the genera Aspergillus and Penicillium that can produce mycotoxins harmful to animals and humans. The grain type and condition, environment, and biological factors can also influence the occurrence and predominance of mycotoxigenic fungi in stored grains. The main environmental factors influencing grain fungi and mycotoxins are temperature and $a_w$. This review discusses the effects of temperature and $a_w$ on fungal growth and mycotoxin production in stored grains. The focus is on the occurrence and optimum and minimum growth requirements for grain fungi and mycotoxin production. The environmental influence on aflatoxin production and hypothesized mechanisms of its molecular suppression in response to environmental changes are also discussed. In addition, the use of controlled or modified atmosphere as an environmentally safe alternative to harmful agricultural chemicals is discussed and recommended future research issues are highlighted.

• Toxicological Research
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• 제33권4호
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• pp.291-297
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• 2017

This study was performed to investigate the dose-response relationship between average daily cadmium dose (ADCD) from rice and the occurrence of urinary cadmium (U-Cd) in individuals eating that rice. This was a retrospective cohort designed to compare populations from two areas with different levels of cadmium contamination. Five-hundred and sixty-seven participants aged 18 years or older were interviewed to estimate their rice intake, and were assessed for U-Cd. The sources of consumed rice were sampled for cadmium measurement, from which the ADCD was estimated. Binary logistic regression was used to examine the association between ADCD and U-Cd (cut-off point at $2{\mu}g/g$ creatinine), and a correlation between them was established. The lowest estimate was $ADCD=0.5{\mu}g/kg\;bw/day$ [odds ratio (OR) = 1.71; with a 95% confidence interval (CI) 1.02-2.87]. For comparison, the relationship in the contaminated area is expressed by $ADCD=0.7{\mu}g/kg\;bw/day$, OR = 1.84; [95 % CI, 1.06-3.19], while no relationship was found in the non-contaminated area, meaning that the highest level at which this relationship does not exist is $ADCD=0.6{\mu}g/kg\;bw/day$ [95% CI, 0.99-2.95]. Rice, as a main staple food, is the most likely source of dietary cadmium. Abstaining from or limiting rice consumption, therefore, will increase the likelihood of maintaining U-Cd within the normal range. As the recommended maximum ADCD is not to exceed $0.6{\mu}g/kg\;bw/day$, the consumption of rice grown in cadmium-contaminated areas should not be more than 246.8 g/day. However, the exclusion of many edible plants grown in the contaminated area from the analysis might result in an estimated ADCD that does not reflect the true level of cadmium exposure among local people.

• 한국지하수토양환경학회지:지하수토양환경
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• 제23권3호
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• pp.27-42
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• 2018

It is important to identify the contaminant sources and to evaluate the fate and transport of heavy metals to crops in agricultural lands. This study was conducted to evaluate metal sources and its transfer and accumulation to crop in agricultural soils. Pollution indices were calculated and multivariate analysis was performed to identify metal sources. To evaluate transfer and accumulation of metals to crops, the contents of phytoavailable metals were evaluated by using single extraction method and the correlation between metal content and soil properties was analyzed. Also the BCF was quantitatively evaluated for investigating the metal transition to each crop grown in the research area. As a result, Cr, Ni, and Co were expected to be mainly derived from geologic factors due to weathering of certain parent rocks. The content of nickel in soils of the research area was slightly higher than that of the concern level criteria based on total concentration, but the amount transferred and accumulated in the crops was actually low. Understanding the contamination characteristics by investigating the pollution sources of heavy metals and its transfer and accumulation to crops through various evaluation techniques could provide important information for proper management of the agricultural land.