• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.5
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• pp.589-598
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• 1995

Filtering rates of Crassostrea gigas were experimentally investigated with reference to effects of water temperature and size. Absorptiometric determinations of filtering rates with oysters being fed diatom Chaetoceros calcirtans were carried out in a closed system. Optical density of 675nm in path length 100mm cell used as the indication of food particles absorption was appeared directly In proportion with the concentration of diatom pigment $chlorophyll-\alpha$. In the closed system where $C_0$ is $OD_{675}$ at initial time 0, $C_t$, at time t, and Z is the decreasing coefficient of OD as meaning of instantaneous removal speed, then $C_t=C_0{\cdot} e^{-2t}$, $Z=In(C_t/C_0)/t$. On the assumption that the filtering rate is constant, then removal rate per unit time (d) is $d=-e^{-z}$. If t is used to time unit of hour (hr), the filtering rate (FR) in I/hr is given by $FR=V{\cdot}d=V(1-e^{-z})$, where V is the water volume (I) of the experimental vessel. Filtering rate increased as exponential function with increasing temperature while not over critical limit. The critical temperature for filtering rate was assumed to be between $28^{\circ}C$ and $29^{\circ}C$. And the weight exponent for filtering rate is 0.223. The model formula derived from the results as FR, $Ihr^{-1}$ = $Exp(0.208{\cdot}T-4.324){\cdot} (DW)^{0.223}$ (T<29 $^{\circ}C)$ where T is water temperature $(^{\circ}C

• Journal of the Korea Concrete Institute
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• v.27 no.4
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• pp.419-426
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• 2015

The purpose of this study is to investigate experimentally the optimum mix design and site application case of soil mixing wall (SMW) method which is cost-effective technique for construction of walls for cutoff wall and excavation support as well as for ground improvement before constructing LNG storage tank typed under-ground. Considering native soil condition in site, main materials are selected ordinary portland cement, bentonite as a binder slurry and also it is applied $1,833kg/m^3$ as an unit volume weight of native soil, Variations for soil mixing wall are as followings ; (1) water-cement ratio 4cases (2) mixing velocity (rpm) 3levels (3) bleeding capacity and ratio, compressive strength in laboratory and site application test. As test results, bleeding capacity and ratio are decreased in case of decreasing water-cement ratio and increasing mixing velocity. Required compressive strength (1.5 MPa) considering safety factors in site is satisfied with the range of water-cement ratio 150% below, and test results of core strength are higher than those of specimen strength in the range of 8~23% by actual application of element members including outside and inside in site construction work. Therefore, optimum mix design of soil mixing wall is proposed in the range of unit cement $280kg/m^3$, unit bentonite $10kg/m^3$, water-cement ratio 150% and mixing velocity 90rpm and test results of site application case are satisfied with the required properties.

• Journal of Environmental Health Sciences
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• v.47 no.4
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• pp.366-377
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• 2021

Background: Polycyclic aromatic hydrocarbons (PAHs) are generated in petrochemical complexes, can spread to residential areas and affect the health of residents. Although harmful PAHs are mainly present in particle phase, gas phase PAHs can generate stronger toxic substances through photochemical reaction. Therefore, the risk assessment for PAHs around the petrochemical complex should consider both particle and gas phase concentrations. Objectives: This study aimed to investigate the concentration characteristics of particle and gas phase PAHs by season in residential areas around petrochemical complexes, and to assess the risk of PAHs. Methods: Samples were collected for 7 days by seasons in 2014~2015 using a high volume air sampler. Particle and gas phase PAHs were sampled using quartz filter and polyurethane foam, respectively, analyzed by GC-MS. Chronic toxicity and probabilistic risk assessment were performed on 14 PAHs. For chronic toxicity risk assessment, inhalation unit risk was used. Monte-Carlo simulation was performed for probabilistic risk assessment using the mean and standard deviation of measured PAHs. Results: The concentration of particle total PAHs was highest in autumn. The gas phase concentration was highest in autumn. The average gas phase distribution ratio of low molecular weight PAHs composed of 2~3 benzene rings was 85%. The average of the medium molecular weight composed of 4 benzene rings was 53%, and the average of the high molecular weight composed of 5 or more benzene rings was 9%. In the chronic toxicity risk assessment, 7 of the 14 PAHs exceeded the excess carcinogenic risk of 1.00×10^-6. In the Monte-Carlo simulation, Benzo[a]pyrene had the highest probability of exceeding 1.00×10^-6, which was 100%. Conclusions: The concentration of PAHs in the residential area around the petrochemical complex exceeded the standard, and the excess carcinogenic risk was evaluated to be high. Therefore, it is necessary to manage the air environment around the petrochemical complex.

• International Journal of Highway Engineering
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• v.8 no.1 s.27
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• pp.89-98
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• 2006

The weight-to-power ratio of the standard truck for the climbing lane design is known to be 200lb/hp. The value was known to be assumed based on constant trucks' capability and regional distributions in stead of widely varied distributions region by region. Additionally, this value was assumed after investigating registered vehicles' statistics instead of investigating real portions of truck volumes. Therefore, it may be said that the value of the current standard truck does not reflect regional or industrial diversity and proportions of truck volumes. To resolve these issues, the present paper studies diversified standard trucks which consider regionally or industrially diversified and observed-volume based weigh-to-power ratios. For this purpose, individual trucks' weigh-to-power ratios obtained at toll-gates of national expressways were used. For regionally based study, the whole nation are divided into 8 regions, then each region is characterized by a unit of a weigh-to-power ratio. The applicability of each value is provided. Results show that the single value for the nationwide standard truck may be 208 lb/hp, 8 lb/hp higher than the current value of 200 lb/hp. Results also show that regional values ranged widely from 170 lb/hp to 230 lb, 30 lb/hp higher/lower than the current value. Conclusively, regional diversity of trucks' weigh-to-power ratios was identified then three types of standardized weigh-to-power ratios which may represent regional characteristics were suggested. As the diversified standard truck are applied to the design standard, two benefits are expected such as decrease of rear-end accident rates or decrease of climb lane construction costs.

• Journal of the Korean Institute of Landscape Architecture
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• v.28 no.5
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• pp.48-57
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• 2000

This paper is dealing with the fundamental properties of planting concrete, replacing the existing cover concrete on the roof of a building. This study is to find out the physical characteristics of the planting concrete and rearing characteristics of the grass throughout the modeling experimental materials. As the results of the experiment, the physical properties of planting concrete show the following results; when the paste to aggregate ratio is 0.2~ 0.4, voids volume : 30~17%, unit weight: 1,710~2,010kg/m3, compressive strength : 45~145kgf/$\textrm{cm}^2$, its pH is more than 11, but is reduced to the proper degree for planting after being neutralized. Kentucky bluegrass covered with planting concrete is grown well. The planting concrete used with blast furnace slag cement shows a better properties at the height, the width and the covering rate by 1.1cm, 0.5mm and 7%, respectively, than those used with ordinary portland cement. Also, the less the paste to aggregate ratio is, the better the plant grows. The orders of the effects of temperature control are as follows; the system of planting concrete with grass>the system of planting concrete without grass>the system of mixed soil>the existed roof system. In case, the planting concrete is placed to the roofs of buildings instead of normal concrete slab, and a number of favorable effect can be expected such as the improvement os environmental factors, the reduction of construction cost, the saving of energy and the reduction of environment load. The future research on the change of a variety of the aggregate conditions and the application of the practical structures should be made, and also the research of the endurance also be performed.

• Journal of Korean Home Economics Education Association
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• v.9 no.1
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• pp.133-143
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• 1997

The purposes of the study is to see as to how much of changes has occurred in the newly revised Home Economics Textbooks required by the 6th Curriculum as compared to those by the former the 5th Curriculum, and to seek future policy directions which can be improved even better, if any, for further revision. To implement this proposal, the study employs 8 different textbooks published in 1997 geared for the 6th Curriculum for data base. The components of the contents divides into two major parts. The first part falls into a category of holistic analysis of the textbooks, which gives a general perspective of the changes in the textbook revised. It includes those areas of changes in the total number of pages, cover page, illustrations, table of contents, appendices, unit cover, introductory remarks, summary and evaluation, etc. It also covers the information on authors of textbook. The latter part consists of several specific areas of major changes occurred in the textbooks for the 6th Curriculum. It covers such areas of changes in the composition of category and its weight, laboratory experiences, and illustrations and tables. To conclude the study, among many findings, two major points are of great importance to mention here. First, the new textbooks have adopted more of varieties in physical appearances and contents per se as to the older ones. And yet, there still found a weakness in numbers of authors participated to a full reflection of contents variety. In addition, the background of authors reflected on an unrealistic idealism which lacks the on-site information provided by the school teachers. Second, the strict regulations created by the Ministry of Education for developing textbook found restricting the authors creativity and thus contents variety of textbooks. Those restricting factors include letter type and size, coloring, paper quality, and volume size.

• Journal of Korean Home Economics Education Association
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• v.8 no.1
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• pp.79-91
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• 1996

The purpose of the study is to see as to how much of changes has occurred in the newly revised Home Economics Textbooks required by the 6th Curriculum as compared to those by the former 5th Curriculum, and to seek future policy directions with can be improved even better, if any, for further revision. To implement this proposal, the study employs 8 different textbooks published in 1995 geared for the 6th Curriculum for data base. The components of the contents divides into two major parts. The first part falls into a category of holistic analysis of the textbooks, which gives a general perspective of the changes in the textbook revised. It includes those areas of changes in the total number of pages, cover page, illustrations, table of contents, appendices, unit cover, introductory remarks, summary and evaluation, etc. It also covers the information on authors of textbook. The latter part consists of several specific areas of major changes occurred in the textbooks for the 6th Curriculum. It covers such areas of changes in the composition of category and its weight, laboratory experiences, and illustrations and tables. To conclude the study, among many findings, two major points are of great importance to mention here. First, the new textbooks have adopted more of varieties in physical appearances and contents per se as to the older ones. And yet, there still found a weakness in numbers of authors participated to a full reflection on contents variety. In addition, the background of authors reflected on an unrealistic idealism which lacks the on-site information provided by the school teachers. Second, the strict regulations created by the Ministry of Education for developing textbook found restricting the authors creativity and thus contents variety of textbooks. Those restricting factors include letter type and size, coloring, paper quality, and volume size.

• Journal of Korea Port Economic Association
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• v.24 no.3
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• pp.57-77
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• 2008

The aim of this paper is to make projection of the demand for export loaded container throughput originating at Incheon port in Korea over the period in question. Systematic analysis is used as a forecasting method instead of quantitative analysis. First of all, the method explores coincident indicators which may reflect the square measure of neighboring industrial complexes which originate/destinate general cargo in export traffic trends. It is noted that in terms of the export loaded container throughput, per unit production scale is intermediated transforming from square measure of production facilities to freight weight in Korea. Consequently, the future progress of the volume can be anticipated relying on the development schemes for developing square measure out of the total square of the industrial complexes. Thus, moving-into percentage of the industrial complexes, percentage of business categories, percentage of capacity and percentage of passing through via Incheon port are adopted and the future traffic demand is projected taking advantage of them.

• Korean Journal of Community Nutrition
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• v.4 no.1
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• pp.103-110
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• 1999

The purpose of this study was to determine the effects of taurine supplementation and taurine depletion on blood glucose and blood lipid concentrations in insulin-treated diabetic rats. Four groups of Sprague-Dawley male rats were fed the purified diet for 3 weeks ; nontaurine-supplemented diabetic rats(E0), nontaurine-supplemented diabetic rats with insulin treatment(E0＋I), 1% taurine-supplemented diabetic rats with insulin treatment(E1＋I) and taurine-depleted diabetic rats with insulin treatment(EA＋I). Diabetes was induced by streptozotocin injection(50mg/kg B.W.). Isophane insulin was given subcutaneously into the abdominal wall of the diabetic rats(4 unit/rat/day). E1＋I were supplemented with 1% taurine in drinking water. To induce taurine depletion, EA＋I were treated with 5% $\beta$-alanine in drinking water. E1＋I had significantly higher body weight compared to that of E0. The food intakes of E1＋I and E0＋I were significantly decreased compared to that of E0. There was no sigfniciant difference in food intake between E1＋I and E0＋I. The water intake of rats was significantly different among the groups ; E0>E0＋I>E1＋I>EA＋I. The urine volume of E0 was significantly increased compared to those of insulin-treated goups. The blood glucose concentration of E0 was significantly increased compared to those of insulin-treated groups. In the oral glucose tolerance test(OGTT), E0＋I and E1＋I had significantly lower blood blucose concentrations compared to E0 after 30 min. Also EA＋I had significantly lower bloodglucose concentrtion compared to E0 and E0＋I. The plasma total cholesterol and LDL-cholesterol concentratons of EA＋I were significantly incrased compared to those of other groups. Therefore, it may be suggested that tuarine supplementation is useful for insulin-dependent diabetes in order to prevent diabetic complications suchas cardiac vascular diseases.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.1131-1137
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• 2004

With the recent continuous expansion of subways, newly created subways tend to have lower locations and wider sections. Furthermore. since box structures and evacuating tunnels are classified into a category of mass-concrete. the thermal-stress, emitted from the inside. causes cracks to structures from the inception of constructing. In this paper, thermal-stress analysis and durability evaluation of box structure were carried out to investigate relationship between durability and parameter causing the heat of hydration. Through the examination, this paper tries to find out satisfactory solutions to regulated thermal crack and ensure the required duration period. The results of this paper showed that to control thermal crack and guarantee the required duration period it was more effective to use low-heat-portland cement and moderateheat-portland cement. As cement volume due to reduction of water-cement ratio increased, the possibility of thermal cracks occurrence increased but results of durability evaluation was different depending on evaluation method. The results showed that the appropriate water-cement ratio to control the heat of hydration and satisfy the required durability was $45\∼55\%$. And it was showed that during placement of concrete blocks ambient temperature affect the heat of hydration. thermal crack and long-term durability largely and when concrete was placed at low temperature to control thermal crack. it need to try to guarantee the required duration period. Henceforth, by studying not only internal and external conditions, such as the relative humidity and the unit weight. but also methods, to evaluate durability, in accordance with domestic situations, more reasonable design of durability should be achieved.