• Applied Chemistry for Engineering
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• v.27 no.4
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• pp.444-448
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• 2016

Hollow silicon/carbon (H-Si/C) composites as anode materials for lithium ion batteries were investigated to overcome the large volume expansion. H-Si/C composites were prepared as follows; hollow $SiO_2\;(H-SiO_2)$ was prepared by adding $NaBH_4$ to $SiO_2$ synthesized using $st{\ddot{o}}ber$ method followed by magnesiothermic reduction and carbonization of phenolic resin. The H-Si/C composites were analyzed by XRD, SEM, BET and EDX. To improve the capacity and cycle performance, the electrochemical characteristics of H-Si/C composites synthesized with various $NaBH_4$ contents were investigated by charge/discharge, cycle, cyclic voltammetry and impedance tests. The coin cell using H-Si/C composite ($SiO_2:NaBH_4=1:1$ in weight) in the electrolyte of $LiPF_6$ dissolved in organic solvents (EC : DMC : EMC = 1 : 1 : 1 vol%) has better capacity (1459 mAh/g) than those of other composition coin cells. It is found that the coin cell ($SiO_2:NaBH_4=1:1$ in weight) has an excellent capacity retention from 2nd cycle to 40th cycle.

• Food Science and Preservation
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• v.11 no.3
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• pp.325-330
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• 2004

This study was conducted to investigate optimal processing conditions, cooking characteristics, antioxidant activity and packaging method of rice coated with bamboo extract. In sensory evaluation of cooked rice, rice coated with bamboo ethanol extract was higher smell and taste than the other extraction methods, but texture showed no difference. As coating concentration increasing, L, a and b values of coated rice were increased. But L value of coated rice after cooking was decreased. On sensory evaluation of cooked rice, smell and taste were best in 10$\%$ coated with bamboo ethanol extract. Mineral contents of coated rice with bamboo extract were higher than those of uncoated. Water absorption and volume expansion of coated rice were lower than uncoated rice but showed higher toyo value. Hardness, gumminess and chewiness values of cooked rice with coated rice were higher than uncoated rice. Antioxidant activity of coated rice was higher than uncoated rice about twice times. Toyo values and alkali digestive values of coated rice were highest in paper package than the other packaging conditions. The total bacterial counts of rice coated with bamboo extract after cooking was lower than uncoated rice during storage at 25 and 6O$^{\circ}C$.

• Journal of the Korean Association of Geographic Information Studies
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• v.18 no.2
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• pp.149-160
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• 2015

This study aims to estimate the forest volumes of the upper region of Nam-Han River in ecosystem zoning by forest types and age classes, and to suggest the optimal estimation method through the comparison of the standard errors according to the spatial unit. In the estimation of forest volumes, we used both of direct estimation, which uses sample plots of the target area only, and synthetic estimation, which includes sample plots of the expanded areas as well as those of the target area. As for the spatial expansion, we applied four standards for synthetic estimator: Mountainous zone, Neighbor ecosystem region, Gangwon province, and Buffer zone. The results show that average forest volume per ha, calculated by direct estimation, was $143.5m^3/ha$, while that by synthetic estimation with each standard, was estimated at $146.9m^3/ha$ by Gangwon province, $144.8m^3/ha$ by Buffer zone, $139.8m^3/ha$ by Neighbor ecosystem region, and $138.6m^3/ha$ by Mountainous zone, respectively. The standard errors of direct estimation was $1.79m^3/ha$, while those of synthetic estimation showed not a great difference among the errors. Meanwhile, considering the standard errors by forest type, the lowest was ${\pm}2.3m^3/ha$ of broad-leaved forest, followed by ${\pm}3.3m^3/ha$ of mixed forest, and ${\pm}4.8m^3/ha$ of coniferous forest.

• International Commerce and Information Review
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• v.17 no.3
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• pp.299-322
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• 2015

Generally Container can be seperated from FCL and LCL. The LCL cargo can be evaluated as a cargo that makes it possible to attract a relatively stable volume and create added value. The aim of this study is to suggest improvement plan for atrracting LCL cargo in Pyeongtaek Port. In order to achieve the object of the study, The research structure is following. 1) analyzing a movement path of the LCL cargo occurring in Pan Yellow-Sea. 2) analyzing the problems to handle LCL cargoes in Pyeongtaek Port. The basic data for analyzing the movement path of LCL Cargoes utilize the data of the Customs Service. and the problems of LCL freight handled suggested from forwarder, carferry liners, and bonded warehouse companies by interview. In this study, We use Fuzzy-AHP as the methodology to analyze the importance of attracting major improvement for LCL shipments in Pyeongtaek Port. As the result, The expansion of inspection equipment and personnel was presented as the most important improvement too solve the clearance problems that is the most serious problems in Pyeongtaek Port. and The realization of incentive payments that local government pay for Profitability of related companies are needed.

• International Commerce and Information Review
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• v.19 no.3
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• pp.3-23
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• 2017

With the globalization of the world economy, international trade networks are expanding beyond geographical proximity, and the expansion of such trade networks is playing a role in promoting globalization. Korea has established itself as a strong FTA for the past 13 years, starting with the Korea-Chile FTA. Successful establishment of a short-term FTA network has shown positive economic effects such as increased trade volume with partner countries and market share in overseas markets. Other countries are also turning to the paradigm of economic development through the formation of a regional economic integration and a bilateral trade agreement network, and it is time to investigate new opportunities through understanding the entire RTA and FTA network. In this study, we analyzed the status of RTA and FTA from the 1960s to 2010s, analyzed network structure and centrality through SNA(social network analysis). The results of the study show that the structure of the FTA network is gradually expanding, and the FTA network, which has been expanding to the center of the early European countries, is changing toward the Asian countries such as Korea, China and Japan. As a result of the analysis of the degree of centrality, Korea was ranked as the top in all the degree of centrality(Degree, Betweenness, Closeness and Eigenvector) indicators for a short period of time and it means that Korea's FTA strategy was evaluated as very successful. This study examines the FTA among the global RTAs, assesses the structure of the FTAs and evaluates Korea's FTA strategies and the FTA network from a network perspective.

• Journal of the Korean Recycled Construction Resources Institute
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• v.2 no.3
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• pp.196-201
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• 2014

As political circumstances in oversea countries and Korea varies, the risk of vulnerability from unexpected extreme loading conditions, such as explosions or extreme impacts, also increased. In addition, construction companies in Korea recently have taken chances of overseas expansion to countries where their domestic situations are not in rest. Therefore, the resistance of construction materials for blast or impact loading become taking more consideration from engineering field. This study is a part of the research to develop a high performance fiber reinforced cementitious composite materials with high volume steel fibers and primary purpose of this study is to find an optimum mix proportions of in-fill slurry. In order to accomplish the tasks this study performed experimental investigations on the slurry for consistency, compressive strength, flowability, J-penetration, bleeding and rheology properties as well as mechanical properties, compressive and flexural strength, with respect to different mix proportions.

• The Journal of Engineering Geology
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• v.26 no.1
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• pp.79-85
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• 2016

A concrete silo plays an important role in subsurface low- and intermediate-level waste facilities (LILW) by limiting the release of radionuclides from the silo geosphere. However, due to several physical and chemical processes the performance of the concrete structure decreases over time and consequently the concrete loses its effectiveness as a barrier against groundwater inflow and the release of radionuclides. Although a number of processes are responsible for degradation of the silo concrete, it is determined that the main cause is corrosion of the reinforcing steel. Therefore, the time it takes for the silo concrete to fail is calculated based on two factors: the initiation time of corrosion, defined as the time it takes for chloride ions to penetrate through the concrete cover, and the propagation time of corrosion. This paper aims to estimate the time taken for concrete to fail in a LILW disposal facility. Based on the United States Department of Energy (DOE) approach, which indicates that concrete fails completely once 50% of the volume of the reinforcing steel corrodes, the corrosion propagation time is calculated to be 640 years, which is the time it takes for corrosion to penetrate 0.640 cm into the reinforcing steel. In addition to the corrosion propagation time, a diffusion equation is used to calculate the initiation time of corrosion, yielding a time of 1284 years, which post-dates the closure time of the LILW disposal facility if we also consider the 640 years of corrosion propagation. The electrochemical conditions of the passive rebar surface were modified using an acceleration method. This is a useful approach because it can reduce the test time significantly by accelerating the transport of chlorides. Using instrumental analysis, the physicochemical properties of corrosion products were determined, thereby confirming that corrosion occurred, although we did not observe significant cracks in, or expansion of, the concrete. These results are consistent with those of Smartet al., 2006 who reported that corrosion products are easily compressed, meaning that cracks cannot be discerned by eye. Therefore, it is worth noting that rebar corrosion does not strongly influence the hydraulic conductivity of the concrete.

• Korean Journal of Clinical Pharmacy
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• v.13 no.2
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• pp.82-90
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• 2003

Dopamine is an effective pressor for the treatment of shock and hypotension when patients do not respond to plasma volume expansion. Two dopamine intravenous delivery systems are currently available in Korea. The objective of this study was to compare dopamine premixed with prefilled system in terms of supply costs (preparation costs + personnel time), contamination rates and convenience. Time-and-motion studies were conducted to determine the time and costs associated with preparation and administration of the two systems. They were analyzed and compared by Mann-Whitney test. To evaluate the contaminaton rates of the two systems, both systems were prepared in an open environment similar to that of practical situations. Premixed and compounded solutions were then filtered by $0.22{\mu}m$ membrane filters, which were cultured at $37^{\circ}C$ for 10 days and their contents were visually checked for bacterial contamination. The convenience of the two systems was compared by itemized user assessments on preparation, dose calculation, admixture, administration and disposal of waste matters. They were analyzed by Wilcoxon's signed rank test and 100 part percentage. It was found that the preparation costs $(mean{\pm}SD)$ for premixed and prefilled systems were $271.70\pm293.55\;Won$ (Korean currency) and $1521.04\pm510.63\;Won$, respectively. The preparation time $(mean{\pm}SD)$ for premixed system was $68.10\pm35.69\;sec.$ while at for prefilled system was $154.03\pm50.06\;sec.$ (n=59 each, p<0.001). No bacterium was observed in the samples of both systems (n=20, each). User assessments indicated that the premixed system was more convenient than the prefilled system except for the item of dose calculation (n=24, p<0.001). Subjective evaluations have proven that the use of the dopamine premixed system resulted in increased efficiency of intravenous preparation by allowing personnel to devote more time to other labor-intensive duties and lower total medical costs.

• Journal of the Korea Concrete Institute
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• v.17 no.1 s.85
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• pp.77-84
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• 2005

The steel slag, a by-product which is produced by refining pig iron during the manufacture of steel, is mainly used as road materials after aging. It is necessary to age steel slag for long time in air because the reaction with water and free-CaO in steel slag could make the expansion of volume. This problem prevents steel slag from being used as aggregate for concrete. However, steel slag used in this study was controled by a air-jet method which rapidly cools substance melted at a high temperature. The rapidly-chilled method would prevent from generation of free-CaO in steel slag. This study dealt with the influence of the using rate of rapidly-chilled steel slag on flow, dosage of SP, W/C ratio, and strength of mortar by statistical experimental design. Also, the results of this experiment were approved by statistical analysis methods, such as analysis of variance and F-testing. As results of F-testing, this paper proved at $1\%$ level of significance that the more the using rate of rapidly-chilled steel slag increased, the more this affected the enhancement of flow, the decrease of dosage of SP and W/C ratio, and the development of compressive strength. Also, considering the fluidity and compressive strength of mortar, it is desirable to use $75\%$ of rapidly-chilled steel slag for river sand.

• Journal of the Korean Institute of Gas
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• v.15 no.5
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• pp.50-56
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• 2011

A preliminary experimental study of new concept air hybrid engine, which stores compressed air in the tank during braking and re-use it to propel vehicle during crusing or acceleration, was carried out in this study. A single cylinder engine was modified to realize the concept of air hybrid engine. Independent variable valve lift system was adopted in one of the exhaust valves to store the compressed air into the air tank during compression period. An air injector module was installed in the place of spark plug, and the stored compressed air was supplied during the expansion period to realize air motoring mode. For air compression mode, the tank with volume of 30 liter could be charged up to more than 13 bar. By utilizing this stored compressed air, motoring work of 0.41 bar of IMEP(Indicated mean effective pressure) at maximum can be generated at the 800rpm conditions, which is higher than the case of normal idle condition by 1.1 bar of IMEP.