• 자원환경지질
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• 제42권6호
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• pp.541-548
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• 2009

한반도 남동부에 위치한 동래온천은 우리나라의 대표적인 고온성 온천중의 하나이다. 동래온천수의 수질형태는 Na-Cl형이고, 상부의 일반 천부지하수는Ca(-Na)-$HCO_3$ 형으로서 서로 간에 연결성이 매우 미약하다. 이 논문에서는 동래 온천수의 $^{87}Sr/^{86}Sr$비와 AMS를 이용하여 측정한 $^{14}C$ 동위원소 년대를 토대로 동래온천수의 나이 즉 온천수-지하수-지표수-천수간의 순환속도를 토의하고자 한다. 연구결과, 2008년도의 2차례에 걸쳐 채취된 동래온천수의 $^{87}Sr/^{86}Sr$비는 0.705663-0.705688로 매우 안정된 값을 갖고 있으며, 이는 천부지하수, 지표수, 해수 및 천수보다 낮은 값이다. $^{14}C$ 동위원소 연대에 의하면, 온천수는 1271년에서 2467년 비보정연대(BP)를 보여주고, 지표수는 -495년으로 나타났다. 이는 동래온천수의 순환속도가 적어도 2500년 이상임을 지시해준다. 이와 같은 순환연대는 현재 사용되고 있는 동래온천수는 과거에 가열된 고온의 물과 현재의 천부지하수와의 혼합수임을 지시해주는 것이다.

• 생태와환경
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• 제42권4호
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• pp.422-431
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• 2009

This study was to provide basic data for aquatic ecosystem research using fishes. Field sampling was carried out at five selected sites of Gap Stream, and fish samples, especially for a selection of sentinel species were collected three times in June, September, and October 2007. We analyzed total length distribution of Zacco platypus in relation with the season and the sampling sites, and then compared with total body weight, condition factor (K), and age distribution of the fish. The fish population data were compared with physico-chemical water quality, obtained from the Ministry of Environment, Korea. Water quality analysis showed a significant nutrient enrichment, based on total nitrogen (TN) and total phosphorus (TP), and organic matter pollution, based on biological oxygen demand (BOD) and chemical oxygen demand (COD) in the Site 5, which is directly influenced by wastewater disposal plant (WDP). Population analysis of the sentinel species showed that the total number of individuals, age distribution, and the population size-structure were influenced by the effluents from the WDP, and that reproductive failure of young-age population were evident in Site 5. According to the relation analysis of total weight to K, the disturbed population was mainly attributed to combined effects of habitat modifications and chemical degradations. Regression analysis of K values against water quality parameters showed significant (p<0.05) positive relations with nutrient and organic matter contents. Our data suggest that the population structure using a sentinel fish species reflected the ambient water quality in the stream and that diagnosis of aquatic ecosystem health using Z. platypus population may be practical for water resource and ecosystem conservations.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 봄 학술발표회 논문집
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• pp.277-280
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• 2003

Material, mix proportion, curing condition, temperature, humidity and wind velocity have an influence on drying shrinkage of concrete. In this paper, to evaluate the effect of curing condition at early age on the drying shrinkage of concrete was investigated varying curing age for different binder. The principal conclusions from this research were as follows: 1) In case of 14 days of water curing, the drying shrinkage of concrete is smaller than 7 days of water curing, independence of type of binder. 2) In case of 4 days of water curing, the ratio of increase of drying shrinkage of concrete using fly-ash and slag powder is more remarkable than using portland cement alone, comparing the drying shrinkage of 7 days of water curing.

• Toxicological Research
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• 제11권2호
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• pp.261-266
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• 1995

Age-related change in the frequency of spontaneous sister chromatid exchange (SCE) and chromosornal aberrations were investigated in bone marrow cells of accelerated senescence-resistant mice (SAM R1) and senescence accelerated ones (SAM P1). And the effect of chronic treatment of ginseng extract (Panax ginseng C.A. Meyer) on these chromosomal abnormalities was tested in SAM P1. SCE frequency in the cells was progressively increased with age in both mice, but it was consistently higher in SAM P1 than in SAM R1 at all corresponding age. Chromosomal aberrations were, however, not significantly changed with age except that it was slightly increased in only aged SAM P1. Interestingly, the rate of these genetic instabilities in SAM P1 was remarkably retarded by long-term administration of ginseng water extract (0.05% in drinking water). These results suggest that frequency of spontaneous SCE in bone marrow cells increase in parallel with senescence of the mice, and SAM P1 is in the condition of being more exposed than SAM R1 to DNA damaging factors. These also indicate that long-term treatment of ginseng may reduce the genetic damage.

• 한국농공학회지
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• 제16권3호
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• pp.3472-3476
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• 1974

This test was attempted to investigate the effects of some mix designs of concreteon the compressive strengths and corrosive rates when exposed to sea water of the West Sea. In this test, concrete mixes consisted of an ordinary concrete, a pozzolan concrete and concretes with different admixtures such as fly ash, pozzolith and vinsol resin. Compressive strengths of the concrete were measured at ages of 1-year and 2-years when exposed to both sea water and fresh water. Corrosive rate was tested at ages of 1-year and 2-years when exposed to sea water only. The results obtained from the test may be summarized as follows: (1) When all of concretes were exposed to fresh water, compressive strength of an ordinary concrete was the lowest at all mixes of concretes, and all of them showed higher strength as the exposing age is longer. It was evidance that the uses of pozsolan cement, fly ash, pozzolith and vinsol resin in mix design of concrete had an effect on increasing compressive strength and that fresh water also had an effect on curing concretes even though at a long-time age. (2) When concretes were exposed sea water, a concrete with fly ash was the highest in compressive strength and its strength was increasing as the exposing age is longer, but the other concretes were decreased at 2-year exposure. It was found that a concrete with fly ash was the most effective on compressive strength of all concrete, but the other concretes were attacked by action of the sea water. (3) The use of vinsol resin admixture was the most resistant to corrosion by sea water, while the use of pozzolith was the most serious at corrosion and the others were corroded to almost same extent. (4) The relationship between corrosions and compressive strengths of concretes was not clearly correlated yet. It was known that the corrosive rate of concretes could not affect to compressive strengths by 2-year exposure of the sea water. (5) Pozzolan concrete was the most effective in compressive strength when exposed to fresh water only, However, the use of a fly ash admixture was available for compressive strength when exposing to both fresh water and sea water. It was also noticed that the use of vinsol resin was not available for strengths of concrete but for resistance to corrosion when exposed to sea water. (6) It was found that the use of pozzolith was so defective in compressive strengths and corrosiive resistance when exposing to sea water that it was only available for fresh water.

• Asian-Australasian Journal of Animal Sciences
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• 제27권7호
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• pp.974-980
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• 2014

In semi-arid areas of Southern Africa, dehydration can compromise the performance and welfare of local chickens, particularly during the growing period when confinement is curtailed and birds are left to scavenge for feed and water. The effect of water restriction on the growth performance was compared in Naked Neck (NNK) and Ovambo (OVB) chickens that are predominant in Southern Africa. A total of 54 eight-wk-old pullets each of NNK and OVB chickens with an initial average weight of $641{\pm}10g/bird$ were randomly assigned to three water intake treatments, each having six birds for 8 wk. The water restriction treatments were ad libitum, 70% of ad libitum and 40% of ad libitum intake. Nine experimental pens with a floor space of $3.3m^2$ per strain were used. The pens were housed in an open-sided house with cement floor deep littered with a 20 cm layer of untreated wood shavings. Feed was provided ad libitum. Average daily water intake (ADWI), BW at 16 weeks of age (FBW), ADG, ADFI, feed conversion ratio (FCR) and water to feed ratios (WFR) were determined. Ovambo chickens had superior (p<0.05) FBW, ADG and ADWI than NNK chickens. Body weight of birds at 16 weeks of age, ADG, ADFI, ADWI, and WFR declined progressively (p<0.05) with increasing severity of water restriction while FCR values increased (p<0.05) as the severity of water restriction increased. Naked Neck chickens had better FCR at the 40% of ad libitum water intake level than Ovambo chickens. The dressing percentage per bird was higher in water restricted birds than those on ad libitum water consumption, irrespective of strain. Heart weight was significantly lower in birds on 40% of ad libitum water intake than those on ad libitum and 70% of ad libitum water intake, respectively. In conclusion, NNK chickens performed better than OVB chickens under conditions of water restriction and would be ideal to raise for meat and egg production in locations where water shortages are a major challenge.

• 한국패류학회지
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• 제24권3호
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• pp.175-188
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• 2008

본 연구는 말백합, Meretrix petechialis의 기초 생리, 생태학적 정보를 파악하기 위한 일환으로 수온 및 염분의 변화가 이들의 여과율에 어떠한 영향을 미치는지 파악하고자 수행되었다. 말백합은 전라북도 김제시 거전리 갯벌에서 채집하였고, 먹이생물은 Phaeodactylum tricornutum(KMCC B-128)을 실내에서 단일종 배양하여 사용하였으며, 여과율 측정은 Coughlan(1969)의 간접측정법을 사용하였다. 먹이생물의 농도는 혈구계산판을 이용하여 광학현미경하에서 직접 계수하였다. 전체적인 실험과정은 Shin and Lim(2003)과 동일하였다. 수온별 말백합의 여과율 변동의 경우 연령에 관계없이 $25-30^{\circ}C$에서 대체적으로 높은 여과율을 나타내었고, 전반적으로 $5^{\circ}C$에서 최소 여과율을 나타내는 경향이었다. 염분별 말백합의 여과율 변동의 경우 전반적으로 20-35 psu의 염분구간에서 비교적 높은 여과율을 나타내는 경향이었다. 연령별 여과율 변동의 경우 대체적으로 연령이 낮을수록 건중량당 여과율은 상대적으로 높은 경향이었다. $Q_{10}$ 값의 경우 전반적으로 낮은 수온 구간($5-15^{\circ}C$)에서 높은 값을 나타내는 경향이었다.

• Computers and Concrete
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• 제24권2호
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• pp.151-158
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• 2019

The sustainable development principle of replacing natural resources with renewable material is an important research topic. In this study, waste LCD (liquid crystal display) glass powder was used to replace cement (0%, 10%, 20% and 30%) through a volumetric method using three water-binder ratios (0.47, 0.59, and 0.71) to make cement mortar. The compressive strength was tested at the ages of 7, 28, 56 and 91 days. The test results show that the compressive strength increases with age but decreases as the water-binder ratio increases. The compressive strength slightly decreases with an increase in the replacement of LCD glass powder at a curing age of 7 days. However, at a curing age of 91 days, the compressive strength is slightly greater than that for the control group (glass powder is 0%). When the water-binder ratios are 0.47, 0.59 and 0.71, the compressive strength of the various replacements increases by 1.38-1.61 times, 1.56-1.80 times and 1.45-2.20 times, respectively, during the aging process from day 7 to day 91. Furthermore, a prediction model of the compressive strength of a cement mortar with waste LCD glass powder was deduced in this study. According to the comparison between the prediction analysis values and test results, the MAPE (mean absolute percentage error) values of the compressive strength are between 2.79% and 5.29%, and less than 10%. Thus, the analytical model established in this study has a good forecasting accuracy. Therefore, the proposed model can be used as a reliable tool for assessing the design strength of cement mortar from early age test results.

• 한국해양학회지
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• 제18권2호
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• pp.161-168
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• 1983

淺水灣에 書式하는 전어의 體長, 年齡 및 成熟度를 分析하여 年齡造成과 繁殖期에 대하여 考察하였다. 資料는 1981年 5月부터 1982年 12月 사이 灣入口에서 小型定置網으로 收集하였다. 전어는 봄에 水溫이 8$^{\circ}C$ 程度로 上昇하였을 때 灣으로 들어 온다. 여름 동안 이곳에서 자란 후, 가을에 水溫이 8$^{\circ}C$ 以下가 되기 전에 灣을 빠져 나간다. 전어는 태어난 첫해에 가장 빨리 자라며, 1-4歲群의 平均體長은 각각 12.2, 15.8, 17.6 및 20.9cm 이었다. 觀察된 가장 큰 個體는 22.0cm었고 나이는 4歲 이었다. 淺水灣 전어는 태어난지 2年이 지나면 夙成되며, 이때 體長은 14cm에 이른다. 成熟年齡과 體長을 分析한 缺課 전어의 成熟은 年齡에 의하여 決定되지 않고 體長에 左右됨이 밝혀 졌다. 전어는 水溫이 8-15$^{\circ}C$인 4月末에서 5月末 사이 産卵한다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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• pp.635-640
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• 2001

In this study, a mathematical model is established for prediction of chloride penetration in unsaturated cracked early-age concrete. The model is combined with models for thermo-hygro dynamic coupling of cement hydration, moisture transport and micro-structure development. Chloride permeability and water permeability at cracked early-age concrete specimens are evaluated using a rapid chloride permeability test and a low-pressure water permeability test, respectively. Then, a homogenization technique is introduced into the model to determine equivalent diffusion coefficient and equivalent Permeation coefficient. Increased chloride transport due to cracks at the specimen could be predicted fairly well by characterizing the cracks using proposed model. Proposed model is verified by comparing diffusion analysis results with test results.