• Journal of Environmental Health Sciences
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• v.23 no.2
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• pp.64-71
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• 1997

This study was performed to investigate the effect of co-existence of carbofuran and chlorothalonil on the short-term bioconcentration factor in Brachydanio rerio(zebrafish). The fishes were exposed to the single and combined treatment of carbofuran and chlorothalonil for 1, 3 and 5 days. Experimental concentrations of carbofuran were 0.05 and 0.10 ppm under the single treatment. And those of chlorothalonil were 0.005 and 0.010 ppm. Experimental concentrations of the combined treatment of carbofuran and chlorothalonil were 0.05 ppm+0.005 ppm, 0.05 ppm+0.010 ppm, 0.10 ppm+0.005 ppm for 1, 3 and 5 days, respectively. Carbofuran and chlorothalonil in fish and in test water were extracted with n-hexane and acetonitrile. GC-ECD was used to detect and quantitate carbofuran and chlorothalonil. 1-day, 3-day and 5-day bioconcentration factors(BCF$_1$, BCF$_3$ and BCF$_5$) of each pesticide were obtained from the quantitation results. The depuration rate of each pesticide was determined over the 24-h period after combined treatment. The results were as follows: Carbofuran did not bioaccumulate in zebrafish under the single and combined treatment for testing periods. BCF$_1$ values of chlorothalonil in concentration of 0.005 and 0.010 ppm under the single treatment were 0.508, 0.621, BCF$_3$ were 1.327, 1.511 and BCF$_5$ were 1.331, 1.597, respectively. BCF$_1$ values of chlorothalonil were 0.512, 0.520 and 0.619, respectively, when the concentration of carbofuran and chlorothalonil in combined treatment were 0.05+0.005, 0.05+0.010 and 0.10+0.005 ppm. BCF$_3$ values of chlorothalonil 1.341, 1.338 and 1.513, respectively, and BCF$_5$ values of chlorothalonil were 1.332, 1.327 and 1.521, respectively, under the above combined treatment. Depuration rate constants of chlorothalonil in concentration of 0.005 and 0.010 ppm under the single treatment were 0.011 and 0.012. Depuration rate constants of chlorothalonil were 0.011, 0.010 and 0.011, when the concentration of carbofuran and chlorothalonil in combined treatment were 0.05+0.005, 0.05+0.010 and 0.10+0.005 ppm. It was observed that no significant difference of carbofuran and chlorothalonil concentration in fish extracts, test water, BCFs and depuration rate constants of carbofuran and chlorothalonil between combined treatment and single treatment. It was considered that no appreciable interaction at experimental concentrations due to lower concentrations than LC$_{50}$. It is suggested that the difference of BCFs between carbofuran and chlorothalonil due to those of fat composition of fish and solubility of carbofuran and chlorothaionil.

• Korean Journal of Construction Engineering and Management
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• v.15 no.1
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• pp.28-38
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• 2014

Construction value engineering(VE) is often performed in the form of a short term review of designs, rather than during a regular workshop with a standardized work plan, and its application method is limited. Thus, tasks are performed by applying the method in reverse depending on the VE results, and function analysis, a key VE method, is omitted or only applied for the sake of formality. In addition, it is hard to expect great results from VE because of insufficient time and budget allowed to perform VE and a lack of understanding of VE procedures and methods. In particular, the methods used to store and reuse the tremendous amount of ideas and information created during the process of VE implementation is not systematic. Even the Korea Expressway Corporation, which has produced relatively systematic VE performance compared to other institutions, has had the above-mentioned problems. Therefore, this study aims to improve existing VE processes and suggest a method to efficiently store and retrieve VE information by analyzing the limitations of construction VE practice and the characteristics of VE for highway facilities as part of improving design VE performance.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.119-119
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• 2010

무한 지속 가능한 지열 에너지를 활용한 공조시스템인 지열원 냉난방 시스템은 기존의 공조 시스템보다 열원이 안정적이기 때문에 높은 효율과 우수한 성능을 가지므로, 기후변화협약 대응의 주요수단으로서 기술개발과 보급이 증대되고 있다. 본 연구에서는 대수층 축열 지열원 열펌프 시스템에 대한 실증 연구를 통하여 대수층 축열 지열원 열펌프 시스템의 하절기 냉방 성능을 분석하였다. 대수층 축열 냉난방 시스템은 주입정과 양수정의 2개의 우물공이 설치되어 있으며, 겨울 난방 운전 중에 한 개의 우물공으로부터 지하수를 열펌프로 유입한 후 낮은 온도의 지하수를 타 우물공에 축열하고, 하절기에 겨울에 저온으로 축열된 우물공으로부터 지하수를 열펌프로 유입하여 온도가 증가된 지하수를 타 우물공에 주입한다. 즉, 계절별로 열펌프에서 생성된 냉수와 온수의 대수층 축열을 위하여 계절별로 주입정과 양수정이 바뀌게 된다. 본 연구의 대수층 축열 지열원 열펌프 시스템의 2009년 8월의 주요일자별 시스템 운전 중의 평균 냉방 열펌프 유닛 COP와 냉방 시스템 COP는 각각 4.7과 3.4이상의 우수한 성능을 나타냈다. 또한, 모든 일자에 대하여 외기온도가 $31.6^{\circ}C$서 $22^{\circ}C$까지 변화가 크게 나타났지만 열펌프 유닛 COP와 시스템 COP의 변화는 미소하였다. 이는 양수정으로부터의 지중 순환수가 운전기간 중에 $17.5^{\circ}C$로 일정하게 유지되었기 때문이다. 양수정과 주입정 사이에 5개의 관측공을 설치하였으며, 양수정 측에 인접한 관측공의 온도는 거의 변화가 없었으며, 단기간이지만 널리 사용되고 있는 수직밀폐형 시스템과 달리 지속적인 냉방운전 중의 양수 온도의 증가는 발생하지 않아 안정적인 성능을 나타냈다. 주입정에 인접한 모니터링 홀의 온도는 심도가 깊은 곳의 온도가 낮은 곳보다 높게 나타났다. 이는 냉방 운전 시 열펌프 유닛의 실외열교환기에서 지중 순환수가 냉매로부터 열을 취득하여 온도가 상승하면서 주입정측에 온열이 축열이 진행되었기 때문으로 분석되며, 하절기의 냉방 운전 시간이 증가할 경우 축열 효과는 더욱 증가할 것으로 예상된다. 양수정과 주입정 중간의 모니터링 홀의 온도는 2009년 8월 가동 중에 온도변화는 없었는데, 이는 양수정과 주입정 사이의 열간섭이 발생하지 않았기 때문으로 분석된다. 일자별로 운전 중의 열펌프 유닛 COP는 차이가 없었지만, 운전 및 정지 시간을 모두 포함한 시스템 소비전력과 냉방용량을 모두 합산하여 산정한 일일 평균 냉방 열펌프 유닛 COP와 냉방 시스템 COP는 일자별로 다소 차이가 발생하였는데, 이는 각 일자별로 열펌프 유닛 가동율의 차이로 인하여 열펌프 유닛 가동 전에 먼저 작동되는 지중순환펌프의 운전 소비전력의 차이와 열펌프의 단속운전 시의 열손실과 추거 소비전력의 차이 때문이다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.6
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• pp.1001-1008
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• 2017

This study was to evaluate the stream depletion rate from groundwater pumping with varying stream-well distance, aquifer transmissivity, storage coefficient, leakage coefficient, streambed hydraulic conductance using the Zlotnik and Tartakovsky analytical solution which considers a two-layer leaky aquifer-stream-well system. For the hydraulic conditions applied in this study, the streambed hydraulic conductance and the aquitard leakage coefficient were assessed to have a dominant influence on the stream depletion rate. In order to evaluate the applicability of Zlotnik and Tartakovsky analytical solution ignoring the change in the drawdown in the lower aquifer and applying the fixed head boundary condition, the solution was compared with Hunt analytical solution derived from the more practical conditions simultaneously taking into account the drawdown changes in the upper and lower aquifers. As a result, the Zlotnik and Tartakovsky analytical solution is suitable for predicting short-term effects of less than one year in the pumping period, and when the stream depletion factor (SDF) is greater than 2,500 days, or when the product of the leakage coefficient and the stream-well distance is less than 10 cm/s.

• Journal of the Korean Wood Science and Technology
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• v.44 no.5
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• pp.785-808
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• 2016

The objective of this study was to investigate the effect of the short-term weathering on the flame retardant performance of wood coated with Dancheong. Flame retardants were applied on the Dancheong coated Korean red pine. Flame retardants applied panels were layed at the two conditions of outdoor exposure and artificial aging to assess the reliability of artificial aging. Flame retardants used were commercial products developed for historical wooden buildings. Scanning electron micrographs revealed the forming of carbonized membrane by melting of flame retardant on wood surface. These carbonized membranes may help delay the further combustion of wood. Flame retardant performance was assessed by measuring heat release rate (HRR) and total heat release (THR) by cone calorimetry. There was no difference in flame retardant performance between before and after 6-month outdoor exposure tests. And also no difference in flame retardant performance between before and after 2-week artificial aging which corresponds to 6-month outdoor exposure. Both tests showed the similar results of combustion characteristics.

• Journal of Korean Society of Transportation
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• v.20 no.1
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• pp.55-63
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• 2002

It has been known well that Traffic Conflict Technique(TCT) used to evaluate the safety of intersections in the case of shortage of traffic accidents data and surveying time. Because data for using in traffic conflict technique that is collected by trained surveyors, it is rely on the knowledge, experience and the characteristics of them. The data of surveying generate varying result. So, its variance must minimize and then it is considered of calculating in traffic conflict technique however obviously technique to minimize has not developed until now. So, this paper has a focus on the technical method to minimize the variance. For this, it applied the fuzzy reasoning theory to the existed traffic conflict technique that is the most comprehensive method in the country and then developed the new traffic conflict technique model. Fuzzy reasoning theory is a very appropriate method for minimizing the variance among surveyors because it can systematically calculate the uncertainty of surveyors by approximation reasoning structure. The result of analysis from pilot study, the new Procedure in this Paper minimized the variance by 53 Percentiles and it increased the value of conversion factor two times than the exited traffic conflict technique. The method proposed in this paper, it can be used for evaluating the safety of intersection, and before and after analysis of improving Project of black spots.

• Food Science and Preservation
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• v.6 no.2
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• pp.153-160
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• 1999

This study was carried out to investigate the production of C$_2$H$_4$ and CO$_2$, and the change of flesh firmness and peel color in 'Fuji' apples during CA storage. ACC oxidase activity was more inhibited by the low O$_2$ concentration, and the low level of internal C$_2$H$_4$ in apples was maintained under the low O$_2$ conditions during 8 months storage. Especially, the level of internal C$_2$H$_4$ in apples was maintained below 1 ppm during storage under 1% O$_2$+1% CO$_2$ at 0$^{\circ}C$, and not much changed for 7 days in air at 20$^{\circ}C$ after storage. The influence of CO$_2$ on the C$_2$H$_4$ production was dependent on the O$_2$ concentration. Increasing of CO$_2$ concentration with 3% O$_2$ decreased the C$_2$H$_4$ Production during storage, but that with 1% O$_2$increased. Internal C$_2$H$_4$ concentration and the rate of CO$_2$ evolution in apples showed the close correlation. Internal CO$_2$ concentration of apples was positively related to the rate of CO$_2$ evolution and maintained the lower level in 1% O$_2$+1% CO$_2$ than the other conditions during storage but nu different in the increment after storage. The relationship between C$_2$H$_4$ and CO$_2$ production was exhibited in CA and the short-term air stored apples, but not in the long-term air stored apples. Loss of flesh firmness and green color in apples was more less in storage condition retarded effectively the production of C$_2$H$_4$ and CO$_2$.

• Journal of the korean academy of Pediatric Dentistry
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• v.44 no.1
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• pp.1-10
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• 2017

The present study aimed to evaluate the validity of resin infiltration in improving color stability after tooth whitening. Enamel samples were extracted from 40 healthy bovine upper incisors, and primary staining and whitening were performed. After that, specimens were randomly divided into 3 groups : resin infiltration group (n = 15, RI group), resin adhesive group (n = 15, RA group), and control group (n = 10). Secondary staining was performed on all samples. Coloration was assessed 5 times as follows: initial color, immediately after staining, after whitening, after resin application, and after secondary staining. Color was measured using a spectrophotometer and recorded by using the CIE $L^*a^*b^*$ color space. The color changes after primary staining for the RI, RA, and control groups were $12.16{\pm}3.50$, $12.16{\pm}3.38$, and $15.81{\pm}6.39$, whereas those after secondary staining were $15.21{\pm}7.19$, $15.93{\pm}4.31$, and $26.62{\pm}17.89$. Color changes after secondary staining showed a significant difference between the RI and control groups. In the within-group comparison between primary and secondary staining, there was no significant difference found in the RI group only (p = 0.26). The results suggest that Color stability after tooth whitening can be improved using resin infiltration.

• Journal of Radiation Protection and Research
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• v.18 no.1
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• pp.9-24
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• 1993

The time-dependent radioecological model applicable to Korean environment has been developed in order to assess the radiological consequences following the short-term deposition of radionuclides in an accident of nuclear power plant. Time-dependent radioactivity concentrations in foodstuffs can be estimated by the model called 'KORFOOD' as well as time-dependent and time-integrated ingestion doses. Three kinds of critical radionuclides and thirteen kinds of foodstuffs were considered in this model. Dynamic variation of radioactivities were simulated by considering several effects such as deposition, weathering and washout, resuspension, root uptake, translocation, leaching, senescence, intake and excretion of soil by animals, intake and excretion of feedstuffs by animals, etc. The input data to the KORFOOD are the time of the year when the deposition occurs, the kinds of radionuclides and foodstuffs for estimation. The time-dependent specific activities in rice and the ingestion doses due to the consumption of all considered foodstuffs were calculated with deposition time using agricultural data-base in Kori region. In order to validate results of KORFOOD, the calculated results were compared with those by a leading German model, ECOSYS-87. The comparison of results shows good agreements within a factor of ten.

• Journal of Korean Society of Forest Science
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• v.84 no.4
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• pp.489-494
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• 1995

Seedlings and grafts of Betula pendula and Betula platyphylla var. japonica were grown under partially controlled environments in a greenhouse and in a plastic-greenhouse installed inside a laboratory. Plant growth conditions such as photoperiod, temperature, nutrient supply were partially controlled to enhance the vegetative and reproductive growth of the birch seedlings and grafts. By the treatments twenty and seventy one percents of the seedlings, respectively, for the Betula pendula and Betula platyphylla var. japonica developed visible floral organs between 250 to 508 days after seeding. By the same treatments eighty and fifty three percents of the grafts, respectively, for Betula pendula and Betula platyphylla var. japonica developed visible male catkins between 51 to 497 days and female catkins between 365 to 396 days after grafting. Breeding cycle of birch species can be reduced to a great extent by the induction of precocious flowering at early stages of seedling and graft development.