• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.176-176
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• 2011

환형수조는 점착성 퇴적물의 이송특성 연구를 위해 가장 선호되는 실험 장치로 알려져 있다. 과거 많은 연구자들은 퇴적물의 이송특성, 특히 침식/퇴적 특성 조사를 위해 주로 수로를 이용한 실험적 연구를 수행하였는데, 최초의 실험적 연구들은 주로 직선수조에서 수행되었다. 그러나 입자간의 응집이 중요한 역할을 하는 점착성 퇴적물의 경우에, 직선수조 끝단에서의 자유낙하 및 재순환 펌프의 날개에 의해 응집된 토사가 쉽게 분리될 수 있어 그 타당성이 의문시 되어 왔으며, 이러한 단점을 보완하기 위해 환형수조가 고안되었다. 환형수조는 수면과 접하여 회전하는 상부링의 마찰력에 의해 흐름이 생성되기 때문에 시간의 제약 없이 흐름조건을 동일하게 만들 수 있다는 큰 장점을 갖는다. 그러나 환형수조는 원주유속의 속도차이 및 원심력으로 인한 2차 순환류를 형성시켜 반경 방향(radial direction)에서의 바닥전단응력을 불균일하게 하는 단점을 갖는다. 이러한 2차 순환류와 바닥전단응력의 불균일을 저감시키기 위하여 환형수조의 몸체를 상부링의 회전 방향과 역방향으로 직접 회전시키는 방법이 채택되어져 왔다. 한편, 환형수조의 상부링과 몸체를 서로 역방향으로 동시에 회전시키는 양방향 회전(counter-rotation)의 적용을 위해서는 2차 순환류가 최소가 되며 바닥전단응력이 균일해지는 최적 회전속도비에 대한 분석은 필수적 사항이다. 이를 위하여, 상부링과 몸체의 회전속도에 따라 변화하는 수조내부의 흐름특성 및 평균바닥전단응력에 대한 연구가 선행되어야만 한다. 이에 본 연구에서는 전산유체역학을 이용하여 전북대에 설치된 환형수조의 상부링과 몸체의 회전속도에 따라 변화하는 수조내부에서의 흐름특성 및 바닥전단응력에 대한 분석이 수행되었다. 또한, 이를 기초로, 환형수조의 최적 회전속도비 산출을 위한 연구가 수행 중에 있다. 이러한 결과들은 추후 환형수조를 이용한 점착성 퇴적물의 침식/퇴적 등과 같은 이송특성 연구시, 퇴적물에 작용하는 흐름조건의 정밀산정을 위한 기초자료로 활용될 수 있을 것이다.

• Journal of the Korea Organic Resources Recycling Association
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• v.16 no.3
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• pp.75-82
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• 2008

Two UASB reactors were operated to investigate the effect of high concentration of sulfate on anaerobic digestion of propionate using an upflow anaerobic sludge blanket (UASB) reactor. An organic loading rate of $1.2kg\;COD/m^3{\cdot}d$ and a hydraulic retention time of 1.6 d were maintained during this study. In the absence of sulfate, the UASB reactor achieved about 95% removal of chemical oxygen demand whereas in the presence of $2,000\;SO_4^{2-}mg/L$, the COD removal rate decreased to 83% due probably to the inhibition of dissolved sulfide inhibition. Interactions between the methane producing bacteria (MPB) and sulfate reducing bacteria (SRB) were measured to investigate the competition between MPB and SRB. The MPB consumed average 58% of the available electron donors at $COD/SO_4^{2-}$ ratio of 1. Propionate was consumed mainly by SRB, converting sulfate into sulfide and suppressing the methane production. The specific methanogenic activity (SMA) using acetate and propionate increased as microorganism acclimated to the substrate.

• Korean Journal of Environmental Biology
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• v.20 no.1
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• pp.46-54
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• 2002

We observed zooplankton community to understand variations in the species composition and abundance in Gangjin Bay. Samples were collected bimonthly from February to November 1999 at 10 stations in Gangjin Bay of the southern part of Korea. Zooplankton communities consisted to nine taxa and mean biomass was 2,028 indiv. $m^{-3}$. The maximum abundance was observed to be 5,496 indiv. $m^{-3}$ in February and the minimum in November, 78 indiv. $m^{-3}$. Copepods dominated and most diverse in Gangjin Bay. Seasonal fluctuation in the copepod abundance varied between 42 and 4,159 indiv. $m^{-3}$. Dominant species are Acartia omorii, Centrophages abdominalis, Paracalanus indicus and A. steueri. Cladoceran also dominated and the maximum abundance was 765 indiv. $m^{-3}$ in April. A. omorii and Oithona davisae dominated in February, A. omorii, Eurytemora pacifica, Evadne nordmanni and Podon polyphemoides in April, Tortanus dextrilobatus and decapod nauplius in June, Paracalanus indicus, E. tergestina and Penitia avirostris in August and A. erythraea and P. indicus in October. In November, P. indicus and Sagitta crassa dominated.

• Korean Journal of Food Science and Technology
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• v.50 no.1
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• pp.55-60
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• 2018

Microbial communities of four commercial Korean nuruks were analyzed by the 454 pyrosequencing method to correlate different characteristics of rice wine fermentation. The total and average sequencing reads of fungi in the four nuruks were 14,800 and 3,494, respectively. At the phylum level, Ascomycota was dominant in three nuruks, namely, SH, SS, and JJ, while Zygomycota was dominant in SJ. Saccharomycopsis was dominant in nuruks subjected to longer fermentation periods, such as SH and SS. The total and average sequence reads for bacteria were 31,485 and 7,871, respectively. Bacteria belonging to the phylum Firmicutes were dominant in all samples. SH showed several genera of lactic acid bacteria, such as Lactobacillus, Leuconostoc, Pediococcus, and other minor bacteria. Staphylococcus and Bacillus were the dominant bacteria in JJ and SJ, respectively.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.240-240
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• 2023

홍수시 교각이나 교량 상판에 집적되는 유송잡물은 하천통수단면을 급격히 축소시켜 수위 상승을 일으키고 교량에 가해지는 유수압을 가중시켜 교량 파괴를 발생시킨다. 이러한 흐름의 변화는 교각 기초부의 세굴 깊이와 면적을 증가시키고 교각 및 교량 상판에 대한 유수압을 증가시켜 교량 자체의 안전성을 위협할 뿐 아니라 수위 상승으로 인한 범람 및 인근 구조물 파손 위험도 초래한다. 이에 대한 대책 마련을 위해서는 교량에 유송잡물이 집적된 경우 변화하는 흐름 특성을 파악하고 그에 대한 이해가 먼저 이루어져야 한다. 기존 연구는 교량에 유송잡물이 집적된 경우 발생하는 교각 기초부의 세굴 양상의 변화에만 초점을 두거나, 교량 인근의 국부적 범위에 대한 흐름 특성 변화에만 집중하여 조사한 경우가 대부분이다. 그러나 하천 내 횡단 구조물 특성 변화로 인한 흐름의 변화는 해당 구조물이 위치한 지점뿐 아니라 상하류의 상당한 범위에 걸쳐 지속적으로 해당 구조물 및 주변 시설에 영향을 미칠 수 있다. 본 연구에서는 실험용 개수로에 교량 모형을 설치하여 수리모형실험을 수행하였고 유송잡물로 인한 교량 폐색이 발생한 경우와 그렇지 않은 경우의 두 가지 조건을 고려하였다. 관찰 구간은 유송잡물이 집적된 교량의 상하류에 발생하는 흐름 변화를 상류는 교량 상판 길이의 약 3.33배 떨어진 위치까지 관찰하였으며 하류로는 교량 상판 길이의 10배 떨어진 위치까지 아우르는 구간에 대하여 관찰하였다. 두 가지 경우의 교량 모형에 동일한 흐름 조건을 적용하여 3차원 초음파 유속계를 이용하여 순간유속을 측정하였고, 시간평균유속, 레이놀즈 응력 및 난류 운동 에너지를 계산하여 평균 흐름 및 난류 특성의 변화를 비교 분석 하였다. 수리모형실험을 통해 유송잡물 집적으로 인한 교각 전면부와 후면부에서 하강류의 크기가 약 2배 정도 증가하는 것을 확인하였다.

• Journal of Food Hygiene and Safety
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• v.13 no.3
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• pp.201-205
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• 1998

In Korea, a small proportion of fishery products are contaminated with a considerable amount of potentially hazardous contaminants. So, there is generally a high risks to consumers. Inorganic contaminants with the greatest potential for toxicity are Sb, As, Cd, Pb, Hg, Se and the Sulfides. As appears to be much more variable than the others. This study was performed to assess the levels of the As in fisheries caught from the waters of the western coast of Korea. The samples included 26 kinds of fishes, 18 kinds of Mollusca, 3 kinds of Crustacea and 7 kinds of salted fishes. The Moisture content of molluscans was significantly higher than that of others (p<0.05). And the As contents of crustaceans were significantly higher than those of fishes, molluscans and salted fishes (p<0.05). The As content of Turban shell was 51.62 ppm, which was the highest among the samples. Also, the As contents of eel, cuttle fish and blue crab were found to be higher than in other fisheries. This variability offers a solution for the reduction of exposure to As through restricting the harvest of aquatic organism from the western coast of Korea.

• Journal of Nutrition and Health
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• v.35 no.4
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• pp.464-472
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• 2002

This study was conducted to investigate dietary and other factors affecting bone mineral density in young Korean collage women. Thirty subjects were recruited; the mean age was 22.1 years and the mean age at menarche was 12.6 years. Bone mineral density (BMD) was measured in the spine (LS), femoral neck (FN), ward's triangle (WT), and femoral trochanter (FT) by Dual Energy X-ray Absorptiometry (DEXA), and physical activity was assessed by a questionnaire. Dietary intake data were obtained 8 times by using a 24 hour recall method to evaluate the subjects' usual diet. Bone mineral densities of lumbar spine, femoral neck, ward's triangle and femoral trochanter were 1.149 g/$\textrm{cm}^2$, 0.980 g/$\textrm{cm}^2$, 0.936 g/$\textrm{cm}^2$ and 0.759 g/$\textrm{cm}^2$ respectively. The met energy intake of subjects was 1,790 kcal, and calcium and iron intakes were found to be inadequate compared to the Korean RDA. The BMD of the lumbar spine was significantly and positively related to the BMI and intake of vitamin C, carbohydrate, potatoes, fruits and plant food. The BMD of the femur (FN, WT, FT) was positively related to the BMI, to carbohydrate and fruit intake, and to the percentage of plant food in total food intake. Multiple recession analysis showed that fruit intake was significantly related to the BMD of the LS. The subjects'ages and fruit intakes were significantly related to the BMD of the femur (FN, WT, FT). These results indicate that higher fruit intakes may have a beneficial effect on bone mineral density.

• Journal of Nutrition and Health
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• v.52 no.6
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• pp.618-627
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• 2019

Purpose: This study evaluated the dietary quality of lunches consumed through home meals, institutional meals, and eating-out at restaurants in Chinese adults. Methods: The total of 3,708 people (aged 20 ~ 64) were selected from the data of the 2011 China Health and Nutrition Survey and divided into three groups: the home (HM, 2,845 people), institutional (IM, 579 people), and eating-out (EO, 284 people) meal groups. Dietary intakes of eight food groups, the frequency of eating certain foods, food group intake pattern, dietary diversity and the variety score of lunches were analyzed. Results: The meat intake of IM and EO were higher than that of HM (p < 0.05), and the vegetable intake was the highest in HM, followed by IM and EO (p < 0.05). The intake of fruit and milk·dairy products were extremely low in all the groups. Compared with 1/3 daily recommended intake, the meat intake was above the standard in all the groups and the vegetable intake was insufficient only in EO. The most frequently consumed food in all the groups was rice, followed by pork. The relatively desirable food group pattern, "grain + meat + vegetable", was highest in IM (66.0%) and lowest in EO (48.2%). The "grain + vegetable" pattern in HM and the "grain + meat" pattern in EO were relatively higher than that in the other groups. The dietary diversity score (p < 0.001) and dietary variety score (p < 0.001) were significantly higher in IM than that in the HM or EO. Conclusion: The lunches of Chinese adults had common problems in excess meat intake and a severe lack of fruit and milk·dairy products. Even institutional meals were not ideal as single meals for Chinese adults, although they were better in food diversity. Customized dietary educational programs based on balanced meal plans need to be established, especially for those Chinese people having lunch at home or eating out. In addition, a systematic food service program should be developed and firmly implemented.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.2
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• pp.203-211
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• 2013

The purpose of this study was to investigate the perception of aseptic foods (sterilized foods with radiation technology) in cancer patients in Busan. The subjects were 192 cancer patients at a hospital. This study was performed through interviews using questionnaires. Patients had perception scores on the need to develop aseptic foods (4.30 points out of 5.00), use aspetic foods (4.06/5.00), and intake aseptic foods (4.04/5.00). Patients less than 59 years old had significantly higher perception scores than those over 60 years old (p<0.05). The scores on aseptic food indicated the importance of various factors, including sanitation (4.86/5.00), good materials (4.82/5.00), nutritional value (4.79/5.00), unused of monosodium glutamate (MSG) (4.66/5.00), taste (4.61/5.00), and reasonable prices (4.60/5.00). The patients who were college graduates showed significantly higher scores and importance in good materials, proper packaging unit, simple cooking methods, food diversity, and familiar foods (p<0.05). In the aseptic menu items, patients wanted to include seasoned raw vegetables (4.11/5.00), a set menu (including cooked grain, soup, and a side dish) (4.08/5.00), seasoned cooked vegetables (4.04/5.00), low sodium kimchi (3.98/5.00), and fermented sauces (3.92/5.00). The patients with gastrointestinal cancer and other cancers (e.g. breast, thyroid, and renal cancer) had significantly higher necessity scores than lung patients for stew, seasoned raw vegetables, salad, low sodium kimchi, and a set menu (p<0.05).

• Journal of Food Hygiene and Safety
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• v.25 no.4
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• pp.402-409
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• 2010

The study was conducted to estimate the contents of heavy metal in commercial herbal medicines (1047 samples of 132 species) which were collected from markets in Seoul and to analyze the contents of heavy metals of herbal medicines by classifying them by parts. The samples were digested using microwave method. The contents of heavy metal (Pb, Cd, and As) and Hg were determined using Inductively coupled plasma-Mass spectrometer (ICP/MS). And the contents of Hg were obtained by Mercury analyzer. The average values of heavy metal in herbal medicines were as follows [mean (minimum-maximum), mg/kg]; Pb 0.870 (ND-69.200), As 0.148 (ND-2.965), Cd 0.092 (ND-2.010), and Hg 0.007 (ND-0.B7). And the average values of heavy metal by parts in herbal medicines were as follows [mean (minimum-maximum), mg/kg]; Ramulus 2.046 (0.065-4.474), Herba 1.886 (0.048-10.404), Flos 1.874 (0.052-5.393), Cortex 1.377 (0.011-4.837), Radix 1.165 (0.012-70.111), Rhizoma 1.116 (0.016-5.490, Fructus 0.838 (0.017-4.527), Perithecium 0.729 (0.013-4.953), Semen 0.646 (0.006-4.416). The average values of heavy metal of imported herbal medicines except Radix were higher than domestic ones. By decoction of herbal medicines exceeding the tolerances, average intake rates of Pb, As, Cd and Hg were obtained as 6.1%, 40.3%, 4.7%, and 2.2%, respectively.