• Geomechanics and Engineering
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• 제30권5호
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• pp.461-469
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• 2022

One of the most important factors that should be considered for using any ground improvement technique is the stability of stabilized soil and the durability of the provided solution for getting the required engineering properties. Generally, most of the earth structures that are constructed on clayey soils are exposing movements due to the long periods of drying or wetting cycles. Over time, environmental changes may result in swells or settlements for these structures. In order to mitigate this problem, this research has been performed on mixtures of high plasticity clay with traditional additives such as lime, cement and non-traditional additives such as polypropylene fiber. The purpose of the research is to assess the most appropriate ground improvement technique by using commercially available additives for resisting the developed desiccation cracks during the drying process and resisting the volume changes that may result during wet/dry cycles as an attempt to simulate the changes of environmental conditions. The results show that the fiber-reinforced samples have the lowest volumetric deformation in comparision with cement and lime stabilized samples, and the optimum fiber content is identified as 0.38%. In addition, the desiccation cracks were not visible on the samples' surface for both unreinforced and chemically stabilized samples. Regarding cracks resistance resulting from the desiccation process, it is observed, that the resistance is connected with the fiber content and increases with the increase of the fiber inclusion, and the optimum content is between 1% and 1.5%.

• 한국산학기술학회논문지
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• 제19권4호
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• pp.633-641
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• 2018

최근 들어 홍수와 가뭄과 같은 자연 재해의 위험이 증가하고 있다. 이러한 위험을 저감하기 위하여 신뢰할 수 있는 수문자료는 수자원 분석 및 수공구조물 설계에 있어 매우 중요하다. 한국의 중부에 위치한 용담 구량천 유역은 K-water와 UNESCO IHP의 연구유역으로써 신뢰 할 수 있는 강수량, 유출량, 증발산량 등의 수문자료를 제공하고 있다. 본 연구는 실측된 수문자료를 바탕으로 우리나라의 산지 유역의 유출 특성을 분석하기 위하여 용담 구량천 유역에서의 유출특성을 Probability Distributed Model을 적용하여 분석하였다. 분석 결과, 유역 유축을 홍수기(6월-9월), 평수기(10-5월)로 기간 분리하여 분석하는 것이 필요함을 확인하였다. 유역 유출비가 홍수기에는 0.27~0.41, 평수기에는 0.30~0.45의 분포를 나타내고 있다. Probability Distributed Model은 적용기간에 따라 차별화된 검정 매개변수를 제시하고 있다. 또한, 2015년 평수기를 제외하고 다른 기간은 유역의 유출을 모두 적합(Nash Surcliffe Efficiency >0.7)하게 모의하고 있어 모형의 적용성을 확인하였다. 본 연구는 Probability Distributed Model을 활용한 기간분리를 통한 소규모 산지 유역의 유출특성방법을 제시한다.

• 공업화학
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• 제20권5호
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• pp.486-492
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• 2009

퀴놀린 습식산화는 $225^{\circ}C$와 $250^{\circ}C$에서 수행되었다. $250^{\circ}C$에서의 습식산화에서 퀴놀린은 30 min 내에 완전히 분해되었으며 총 유기탄소(TOC)는 120 min 내에 63% 감소하였다. 반면에 $225^{\circ}C$에서의 습식산화에서는 TOC는 240 min 동안 13% 감소하였다. 퀴놀린 산화 중 니코틴산과 초산이 주 중간생성물로 생성되었다. 균일촉매 $CuSO_4$ 또는 쉽게 산화되는 페놀을 첨가하여 온화한 반응조건인 $200^{\circ}C$에서의 퀴놀린 습식산화도 수행하였다. $CuSO_4$를 0.20 g/L 사용한 촉매 습식산화는 $250^{\circ}C$ 습식산화에서와 비슷한 퀴놀린 및 TOC 제거속도를 보였다. $200^{\circ}C$에서의 퀴놀린과 페놀 혼합물 습식산화에서는 퀴놀린과 페놀의 분해 개시에 필요한 자유라디칼이 생성되는 유도기간이 나타났다. 주어진 퀴놀린 초기농도에서 페놀 초기농도를 증가시킴에 따라, 퀴놀린과 페놀 분해를 위한 유도기간은 짧아졌고 습식산화 180 min 동안의 TOC 감소율은 60%에서 75%까지 증가하였다. 유도기간의 감소율은 퀴놀린에 대한 페놀 초기농도비를 증가시킴에 따라 감소하였다. 반면에 퀴놀린과 페놀 혼합물 습식산화에서의 페놀분해는 페놀 습식산화에서 보다 긴 유도기간을 필요로 하였고 서서히 진행되었다.

• 응용통계연구
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• 제5권2호
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• pp.123-137
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• 1992

측우기와 근대 우량계로 관측한 서울의 연강수량 시계열을 분석하였다. 측우기로 관측된 1771년부터 1907년 사이의 강수량과 1908년 이후부터 1990년까지의 근대 우량계에 의한 강 수량 시계열을 특별한 보정없이 연결하여 사용하였다. 근대 우량계에 의한 후반부 자료는 기상청 발표자료이며 전반부의 고대 관측 자료는 와다가 측우기 자료를 이용하여 계산한 월 별 강수량을 단위 환산후 수록한 그의 저서 내부의 표1을 이용하였다. 전 분석기간을 3 부 분으로 분리가능하였으며 이를 객관화하기 위하여 원시 계열을 9년 이동평균하여 구한 시계 열과 년강수량 1050mm를 기준으로 사용하였다. 우리는 분석기간의 대부분을 습윤시기1, 건 조시기, 습윤시기2 로 분리 명명하였다. 통계적인 특성상 습윤시기1 과 2는 동일집단으로 간 주 가능하나 습윤시기와 건조시기는 그렇지 못하다. 통계적인 특성상 습윤시기 1과 2의 강 한 동질성은 측우기 자료의 신빙성을 높이는 것으로 해석할 수 있다. 이러한 결과는 고대 측우기 관측에 동반 되었을지 모르는 여러 가지 제약들, 예를 들면 관측 장소와 측정단위의 불명확성 그리고 서울의 도시화와 관련된 제반 기후 변화등을 고려하면 더욱 더 그러하다. 그러나 건조시기와 습윤시기의 강수 변동성을 정확하게 파악하기 위하여는 승정원 일기와 같은 고 문서에 산재하는 측우기로 관측된 일 강수량을 재 발굴하여 분석하는 것이 시급하다.

• 한국토양동물학회지
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• 제5권2호
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• pp.63-70
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• 2000

영국의 고원지대 (Moorland)의 이탄토양 (blanket bog peat soil에 서식하는 애지렁이 정량조사를 위한 수분갈때기추출법의 효율에 미치는 수온, 물의 량, 추출시간의 복합적인 효과를 조사하였다. 이탄 토양에서 애지렁이 추출을 위한 최적조건은 물의 양과 초기 수온에 관계없이 표면수의 최종 온도는 35$^{\circ}C$이고, 추출시간은 6시간이었다. O'Connor의 방법 (최종 온도 40-45$^{\circ}C$,열의 점진적인 증가, 3시간 추출)은 비교적 늪은 온도와 짧은 추출시간으로 인해, 추출효율에 변이가 심하였다. 열을 가하지 않고 장시간 추출하는 방식은 열을 가하는 방식에 비해 추출효율이 현저히 낮았다.

• 한국제4기학회지
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• 제21권2호
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• pp.69-73
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• 2007

Inorganic geochemical and mineralogical analyses from the trench sediments of the Hwayang wetland were carried out to verify the wet/dry conditions during 6000 - 5000 yr BP and abnormal event of 6300 yr BP of Korean west coast. Lithostratigraphy, mineralogy and major element concentrations of the sediments of the trench indicate that during 6000 - 5000 yr BP, a wet/dry conditions might be repeated at an interval of 200 years. Carbonate minerals precipitated with the decrease of water depth in the lake or wetland after about 6000 yr BP. On the other hand, the sediments coarser in mean grain size and larger in standard deviation were corresponded with periods of 6300 yr BP and 6230 yr BP. Especially, such a feature of grain size distribution of 6300 yr BP appears in other wetlands situated in the west coast, e.g., Hwangsan wetland and Cheollipo coastal wetland. During the period, the coarse sediments seem to have been delivered by a high energy like storming.

• Journal of Nutrition and Health
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• 제40권5호
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• pp.419-427
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• 2007

This study explored the effects of dietary calcium level and Hijikia fusiforme supplementation on bone indices and serum lipid levels using 36 female Sprague-Dawley rats as a model. Rats received low Ca diet for 3 weeks after ovariectomy. The rats were then divided into six dietary groups and fed low (0.1% Ca), normal (0.5% Ca) and high (1.5% Ca) Ca diets (CaL, CaN, CaH) and low, normal, high Ca diets with Hijikia fusiforme supplementation (CaLH, CaNH, CaHH) for 3 weeks. After each experimental periods, 24 hour urine and/or blood samples, left and right femurs were collected for analysis. Serum Ca concentration showed no significant difference by dietary Ca levels and Hijikia fusiforme supplementation. Alkaline phosphatase activity was significantly higher in normal and high Ca group compared to low Ca group. Serum total cholesterol, triglyceride and total lipid were not significantly different among groups. HDL-cholesterol showed no significant difference by Hijikia fusiforme supplementation. However, the normal and high Ca groups showed significantly higher HDL-cholesterol compared to the low Ca group. Urinary hydroxyproline and hydroxyproline/creatinine ratio were not significantly different among groups. The wet weight of the femur was significantly higher in low Ca group compared to normal or high Ca group. The dry weight, wet weight/body weight, length and breaking force of the femur were not significantly different among groups. Ash contents/wet weight of the femur was significantly increased as dietary Ca levels up and significantly higher in Hijikia fusiforme supplementation groups. The Ca content of the femur were significantly higher in the normal and high Ca groups than the low Ca group. However, there was no significant difference in Ca content by Hijikia fusiforme supplementation.

• 한국약용작물학회지
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• 제23권5호
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• pp.370-378
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• 2015

Background : Aruncus dioicus var. kamtschaticus, functional wild vegetable, is perennial herb and young leaves with soft texture are generally used as edible food. So the demand for the vegetable has increased recently. This study was carried out to determine the effects of temperature and shading on germination characteristics of A. dioicus. Methods and Results : The experiment was performed by temperature and shading treatments. Seed pre-treatment before the germination experiment was carried out by the storage in low temperature ($4^{\circ}C$) under wet condition (LTW) for 0, 15, 30, 45 and 60 days and shading treatment were 35%, 50%, and 75% under control, BA (6-benzyladenine) and $GA_3$ (gibberellic acid) condition for 24 hours. Increasing the length of the storage periods led to increases seed germination percent in low temperature ($4^{\circ}C$) under wet condition (LTW), germination rate of A. dioicus seed was the highest at $15^{\circ}C$ with 60 days of seed pre-treatment. In the case of seeds pre-treatment with LTW, the more temperature went up, the more days to 50% of Germination of Final Germination Rate ($T_{50}$) went down. As a result of surveying shading treatment, germination rate was the highest in control of 35% shading and the next higher was in control of 50% shading. Conclusions : It is concluded that the temperature and shading are important factors to produce A. dioicus. Also, We suggest these results as basic data of A. dioicus for sexual propagation.

• 한국방재학회 논문집
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• 제7권4호
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• pp.107-113
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• 2007

The Kuem-River, one of the largest rivers in Korea, is the primary water source for more than 4 million people in Kongju city and surrounding area. To study the effect of stormwater runoff to CSOs, twelve monitoring sites were selected in two large cities (City of Kongju and City of Buyeo) near the Kuem-River. Monitoring was reformed by collecting grab samples, measuring flow rates during dry and wet seasons during over two rainy seasons. Generally the flow rate of wastewater in combined sewers was rapidly decreased after 23:00 P.M. and gradually increased from 06:30 A.M. in all sites during the dry season. The concentrations of pollutant increase approximately 5 to 7 fold for TSS and 1.5 to 2.5 fold for BOD during the rainy season. Monitoring and statistical analysis show that the groundwater contributes on sewage volume increase (average 25-45% more) during dry periods and the stormwater runoff contributes approximately 51-72% increase during rainy periods. Generally the concentrations of combined sewage were more polluted during the first flush period than after the first flush during a storm event.

• 한국임상수의학회지
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• 제11권2호
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• pp.553-560
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• 1994

This experiment was conducted to evaluate the feed value of Macol meal, which is one of the byproducts from the extraction of liquid syrup from barley grain, on lactating dairy cows. All of the lactating dairy cows feeding in eight dairy farms were used in feeding experiment and fed concentrates plus Macol meal 5Kg as wet basis. The milk yields and milk fit during the periods of 10 months were investigated and blood picture, blood chemistry and diseases occuring frequency before and after feeding Macol meal were analyzed. The results obtained were as follows ; 1. In the proximate compositions, the contents of moisture, crude protein, crude fat, crude fiber, crude as and nitrogen free extracts was 68.8%, 7.43%, 1.04%, 7.08%, 1.56% and 14.09% respectively. On the other hand, the contents of NDF, ADF and cellulose was 36.68%, 35.71% and 10.85%, as dry matter basis, respectively. 2. The daily milk yield per head was 22.84kg during two months before feeding Macol meal and 23.89 kg during the periods of ten months after feeding Macol meal. 3. The blood picture and blood chemistry were not affected by feeding Macol meal. 4. The diseases occuring frequency were not significantly affected by feeding Macol meal. from the results of this experiment it could be concluded that Macol meal can be used in lactating dairy cows rations without any adverse effects.