• Journal of the Korean Geotechnical Society
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• v.31 no.12
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• pp.71-76
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• 2015

Recently, people are increasingly interested in horizontal directional drilling (HDD) to construct oil and gas pipeline and utility pipeline in the urban area as one of trenchless methods. One of major issues during the HDD is the collapse of borehole, which may be the potential causes of ground collapse. This study investigated the effect of mud pressure on the borehole stability, using finite element analysis. Since the borehole is being drilled with a certain angle, three dimensional analysis should be performed. The borehole stability was examined by applying two different types of mud pressures, i.e., uniform and non-uniform, to the exterior surface of borehole. The results show that the high mud pressure at the beginning of drilling, i.e., at shallow depth, causes the borehole collapse, whereas the borehole was stable even at high mud pressure as the drilling depth increases. It can be said that the determination of maximum mud pressure is strongly related to the drilling depth.

• Journal of the Korea Institute of Building Construction
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• v.18 no.1
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• pp.17-24
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• 2018

The pullout test, a nondestructive testing(NDT), for pre-installed inserts is perhaps the most widely used technique to estimate the in-situ compressive strength of concrete. It measures the force needed to pullout a standardized metal insert embedded into concrete members. The pullout test was certified by the American Society for Testing and Materials(ASTM) and Canadian Standards Association(CSA) as a reliable method for determining the strength of concrete in concrete structures under construction. To easily estimate the strength of ultra-high-strength concrete, a simplified pullout tester, primarily composed of a standard 12mm bolt with a groove on the shaft as a break-off bolt, an insert nut, and a hydraulic oil pump without a load cell, was proposed. Four wall and two slab specimens were tested for two levels of concrete strength, 80MPa and 100MPa, using a simplified pullout tester with a load cell to verify the advantages of the pullout test and simplified pullout test. The compressive strength of concrete, pullout load, and the rupture of the break-off bolt were measured 11 times, day 1 to 7, 14, 21, 28, and 90. The correlation of the pullout load and the compressive strength of each specimen show a higher degree of reliability. Therefore, a simplified pullout test can be used to evaluate the in-place strength of ultra-high-strength concrete in structures. The prediction equation for the groove diameter of the break-off bolt(y) with the concrete strength(x) was proposed as y=0.0184x+5.4. The results described in this research confirm the simplified pullout's utility and potential for low cost, simplicity, and convenience.

• Korean Journal of Construction Engineering and Management
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• v.10 no.6
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• pp.146-153
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• 2009

The year 2008 was a hard year for Korea's construction companies. The real estate downturn resulted in halting new construction and stopping existing work, and inflation of global oil prices caused price hikes in rebar and concrete materials. As a solution to reducing the budget, the newly appointed government announced plans to increase low cost bid contracts from 10 billion to 30 billion won. When such economical and political factors negatively impact the construction market, projects based on low cost contracts are the hardest hit. Many problems already inherent in low cost bid contracts become accentuated. Consequently, this provides an opportune time to actually study and analyze the issues in these projects. This paper introduces the findings made from investigating four projects struggling to make ends meet in the year 2008. Results show that flow of cash (i.e., liquidity), or lack thereof, was the root cause which in turn was hampered by failed mechanisms for design changes, material inflation. Attributing cash flow risk to the bottom of the production structure (i.e., small business subcontractors) was also a problem within the industry. Contractors need a better way to prepare against material price fluctuations, and owners need to assist in expediting payment during times of extreme downturn.

• Journal of Environmental Policy
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• v.9 no.1
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• pp.57-81
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• 2010

Since the Republic of Korea is highly dependent on fossil fuels despite high oil prices, it urgently needs to renew its economic and social system to cut carbon emissions and achieve green growth. Therefore, reforming or eliminating subsidies related to the use of fossil fuels is a timely and oppropriate policy recommendation for Korea. It would be a win-win deal for Korean society as it would not only reduce the use of environmentally harmful fossil fuels but also enhance economic efficiency. In particular, cross-subsidies for industrial, agricultural and night thermal-storage power services make up more than 80 percent of all subsidies provided to the entire electric power industry sector of Korea. Of these cross-subsidies, this paper analyzes the electricity subsidy for industries, which takes up the largest share (about KRW 1.6583 trillion yearly), among the environmentally harmful subsidies in the electric power sector. Thus, the paper focuses on the analysis of ripple effect anticipated when this is reformed. To examine the effects of this subsidy reform, price elasticities were estimated using the ARDL (autoregressive distributed lag) model and quarterly data from 1990 to 2007. The main results of this study show that 1) annual energy demand for electric power in the industrial sector would drop by 12,475,930MWh and 2) $CO_2$ emissions would plummet by 2,644,897 tons per year if the subsidy were reformed. We can deduct from this that the abolition of environmentally harmful subsidies in the electric power sector in the Republic of Korea would considerably contribute to $CO_2$ emissions abatement in the country.

• Journal of Environmental Policy
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• v.13 no.2
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• pp.99-129
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• 2014

This research estimates the impact of population aging on energy use and carbon emissions by energy sources and by industrial sectors in Korea until 2035. For the estimation, the structural change in household consumption expenditure identified by the age-specific consumption pattern was analyzed in conjunction with energy and environment input-output tables. The estimation result presents that, despite the population aging, energy use and carbon emissions induced by household consumption continue to increase until 2026, and then that elevated levels of energy use and carbon emissions will be maintained for a considerable period of time. According to the estimation by energy sources, the use of natural gas will show substantial increase while the use of crude oil will switch to a downturn at a relatively early period. According to the estimation by industrial sectors, carbon emissions in the sectors with relatively high consumption share of old households such as medical health, dwelling, lighting, heating, air-conditioning, and food will have substantial increase, whereas those in the sectors associated with education, transport, catering, and accommodation services will turn downward relatively early. In addition, the study analyzes through policy simulation the impact of aging-related policy similar to the basic pension system, which is recently being discussed for legislation, on energy use and carbon emissions.

• Korean Journal of Community Nutrition
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• v.5 no.2
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• pp.297-306
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• 2000

In order to examine the relationship between the number of different foods consumed and nutrient intake, one-day food consumption were surveyed by 24-hour recall from a sample of 287 individuals(20-49 years) living in Daejon City. The number of consumed food items did not include seasonings except red pepper power, sugar, oil, and soybean paste when used in large amounts(DVS). The number, including all seasonings except salt and vinegar(DVSS), was also counted. Of the total subjects, 43.6%(DVS) or 39.0%(DVSS) consumed 18-23 daily different foods with an average of 20.2 or 22.9, respectively. As the DVS increased, daily intakes of total foods and most food groups were elevated. Cereals however were not changed and eggs were decreased with increasing DVS. Energy and nutrient intakes and their mean adequacy ratio(MAR) and index of nutritional quality(INQ) also show positive correlations with DVS. MAR equal to or greater than($\geq$) 0.75 was taken as a cut-off point for nutritional adequacy. In that case, the mean INQ was shown to be $\geq$1. MRI(10) for energy and 9 nutrients and MAR(3) for Ca, vitamin A, and riboflavin were estimated. Form a regression analysis, when MAR(10) was 0.75, the DVS and DVSS were assumed to be 19.6 and 22.2, respectively. And when MAR(3) was 0.75, the DVS and DVSS were assumed to be 31.6 and 34.6, respectively. However the subjects whose MAR(3) was 0.75(0.7-0.8) 23.8(DVS) or 26.6(DVSS) different foods in average, and their mean intakes of energy and all nutrients, except vitamin A, were ranged at 85-100% of the RDA. Of the 74 subjects who consumed DVS$\geq$24, 24 to 42 numbers took 〈75% RDA of Fe, Ca, riboflavin, and vitamin A. And five of 7 who consumed DVS$\geq$32 took $\geq$125%RDA of protein, which showed concerns of overnutrition in case of DVS$\geq$32. Form the above results it could be suggested that a daily intake of 24-32(or 28) of DVS or 27-35(or 31) of DVSS was recommendable for an optimal nutritional of all nutrients if the variety of food groups and sufficient intake of vitamin A and calcium were emphasized together.

• Korean Journal of Environmental Agriculture
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• v.30 no.4
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• pp.466-472
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• 2011

BACKGROUND: Soybean [Glycine max (L.) Merrill] is a legume and an important oil crop worldwide. This study was conducted to evaluate the possible impact of transgenic soybean cultivation on the soil microbial community. METHODS AND RESULTS: Microorganisms were isolated from the rhizosphere soils. Microbial community was identified based on the culture-dependent and molecular biology methods. The total numbers of bacteria, fungi, and actinomycete in the rhizosphere soils cultivated with transgenic and non-transgenic soybeans were similar to each other, and there was no significant difference between transgenic and non-transgenic soybeans. Dominant bacterial phyla in the rhizosphere soils cultivated with transgenic or non-transgenic soybeans were Actinobacteria, Firmicutes, and Proteobacteria. The microbial communities in transgenic and non-transgenic soybean soils were characterized using the denaturing gradient gel electrophoresis (DGGE). The DGGE profiles showed the different patterns, but didn't show significant difference to each other at 0.05 significance level. DNAs were isolated from soils cultivating transgenic or non-transgenic soybeans and analyzed for persistence of transgenes in the soil by using PCR. PCR analysis revealed that there were no amplified ${\gamma}$-tmt and bar gene in soil DNA. CONCLUSION(S): The results of this study suggested that microbial community of soybean field were not significantly affected by cultivation of the transgenic soybeans.

• Journal of Korean Society of Transportation
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• v.28 no.5
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• pp.91-106
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• 2010

Recently, interest in supply chain management is rising along with the increasing oil prices and traffic congestion. In particular, people started studying the issue, but realized that advantageous strategies for suppliers and retailers are not always advantageous to a carrier. Therefore, in this study the atuhors set up a simulation scenario to understand delivery vehicle routing problems under various inventory policies, namely Economic Order Quantity (EOQ) and Periodic Order Quantity (POQ) and network configurations. First, the authors made a virtual supply chain. Then they analyzed characteristics of delivery vehicle routing under various inventory policies (EOQ and POQ) and network configurations. As a result, the POQ inventory policy decreases the number of vehicles, the number of drivers, and the service time of vehicles. Also, the centralized network increases the load factor of vehicles and decreases the service time of vehicles. In other words, the centralized network and the POQ inventory policy are better for the carrier. These results show a savings of 15,556,806 won ($13,389.10) in a month: a reduction of 17%.

• Journal of Preventive Medicine and Public Health
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• v.40 no.2
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• pp.155-161
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• 2007

Objectives : Bisphenol A diglycidyl ether (BADGE) is the major component in commercial liquid epoxy resins, which are manufactured by co-reacting bisphenol A with epichlorohydrin. This study was performed to show the developmental effects of prenatal and postnatal exposures to BADGE in male rat offspring. Methods : Mated female rats were divided into four groups, each containing 12 rats. The dosing solutions were prepared by thoroughly mixing BADGE in corn oil at the 0, 375, 1500 and 3000 mg/kg/day concentrations. Mated females were dosed once daily by oral gavage on gestation day (GD) 6 - 20 and postnatal day (PND) 0 - 21. Pregnant female dams were observed general symptoms and body weight. Also, male pups were observed the general symptoms, body weight, developmental parameters (e.g. anogenital distance, pina detachment, incisor eruption, nipple retention, eye opening, testis descent), organ pathologic changes and hormone levels of plasma. Results : Pregnant rats treated with BADGE died at a rate of about 70% in the 1500 mg/kg/day group and all rats treated with 3000 mg/kg/day died. Body weight, for male pups treated with doses of 375 mg/kg/day, was significantly lower than in the control group at PND 42, 56, and 63 (p<0.05). Evaluation of body characteristics including; separation of auricle, eruption of incisor, separation of eyelid, nipple retention, descent of testis, and separation of the prepuce in the BADGE treated group showed no difference in comparisons with the control group. AGD and adjusted AGD (mm/kg) for general developmental items in BADGE 375 mg/kg/day treated pups tended to be longer than in controls, however, these differences were not statistically significant. Relative weights of adrenal gland, lung (p<0.05), brain, epididymis, prostate, and testis (p<0.01) were heavier than in control in measures at PND 9 weeks. There were no significant changes in comparisons of histological findings of these organs. Loss of spermatids was observed in the seminiferous tubule at PND 9 weeks, but no weight changes were observed. The plasma estrogen levels were similar in the control and treatment groups at PND 3, 6 and 9 weeks. The plasma testosterone levels in the control group tended to increase with age. However, in the BADGE 375 mg/kg/day treated male pups it did not tend to increase. Conclusions : These findings suggest that BADGE is a chemical that has developmental effects consistent with it being an endocrine disruptor.

• Korean Journal of Food Science and Technology
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• v.6 no.4
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• pp.193-198
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• 1974

The antioxidant activity of ground red pepper, ethyl alcohol extracts of ground red pepper peel and alcohol extracts plus organic acid was studied by using edible soybean oil as a substrate. All the substrates were stored in a dark place at $45.0{\pm}0.5^{\circ}C$ respectively. The results of the study were as follow: 1. Ground red pepper, black pepper and cassia exhibited slight antioxidant activity and there was no significant difference in antioxidant activity among them. 2. Although both ground red pepper peel and red pepper seed showed antioxidant activity, ground red pepper peel exhibited greater antioxidant activity than ground red pepper peel did. 3. Ethyl alcohol extracts of red pepper peel showed strong antioxidant activity, but the residue did not show the antioxidant activity. 4. The antioxidant activity of the ethyl alcohol extracts of red pepper peel increased in direct proportion to the concentration of the extracts. 5. In connection with the synergistic effect of organic acid to the ethyl alcohol extracts of red pepper peel, citric acid showed a very strong synergistic effect on the antioxidant activity of red pepper, while ascorbic acid showed a weak effect. On the other hand, phosphoric acid showed an accelerating effect on the oxidation of oils. 6. The maximum antioxidant activity of the ethyl alcohol of ground red pepper peel was observed at the citric acid concentration of 0.04%, when tested at various concentration of citric acid.