• Journal of Korean Society of Environmental Engineers
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• v.30 no.8
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• pp.839-846
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• 2008

The flocculation characteristics of polyacrylamide base flocculants were estimated to reduce the moisture content of the dehydrated cakes. The dewaterability for sewage sludge was found to have a marked effect depending on the flocculant type, agitating speed and time, kind of dissolution water, etc. The optimal agitating speed and time were 700 rpm and 3 sec, respectively, in this experimental condition. and the dewaterability was proportion to the agitating speed upto 700rpm. When recycle water as the dissolution water was used, the solution viscosity of all kind of flocculants was decreased. However, the change of its viscosity are not proportioned to the dewaterabilities for each flocculant. Flocculation system of combinations of the first and sencond flocculation using single flocculant was investigated. Effects of the ratio of first and second dosage for dual flocculation on the dewaterability were also investigated. The optimum conditions of dual flocculation system are 75% and 50% as first dosages for low and high viscous flocculant for total dosage of common flocculation, respectively. Based on the results, an overall mechanism of dual flocculation system is proposed and it is envisaged that optimization of flocculation processes in this way can result in considerable savings in cost.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.2D
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• pp.111-119
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• 2012

In this study, the effect of safety improvement project was analyzed, and a decision making model for traffic accident reduction measures was suggested. The results of this study are as follow; First the overall number of traffic accidents and casualties were reduced, especially reduced the number of unauthorized crossing and centerline encroachments was remarkable. Second, the priorities of traffic accident reduction measures. through hazards roadway section improvement projects were determined. As, higher level evaluation items of AHP hierachy structure include civil facilities and transportation facilities. The civil facilities has 6 lower level evaluation items and transportation facilities has 4 items. The results of this study, It was revealed that traffic experts prefer civil facilities more than transportation facilities and the top 2 items of the each data (or index) took over 50%. In addition, one of the last evaluation contents through the verification, the top 3 items of civil facilities took 55.38%. The project according to the improvement projects for hazards roadway reduced traffic accidents and casualties as well as saving the cost. So these results should be available for basic information for the countermeasure about reducing the traffic accidents by local governments.

• Journal of Climate Change Research
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• v.1 no.3
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• pp.205-210
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• 2010

LED light has various advantages such as an energy saving effect of over 80% compared to existing lighting and environmentally friendly characteristics; however, there has been no affordable market for LED lighting because of its expensive price. This study discussed the validity of the expansion of distribution of LED lighting through an assessment of economic efficiency concerning LED lightening in order to analyze its efficiency in terms of energy savings and maintenance and repair, which will be generated as a result of the change from existing incandescent bulbs to LED lighting in the public sector. As to the target of analysis, the paper reviewed the validity of change to LED lighting as a result of the elimination of existing incandescent bulbs, by referring to 'the current incandescent bulb use and elimination performance' published by the Ministry of Knowledge Economy based on the "Elimination management system" executed by Korea Energy Management Corporation. The paper considered expenses for change, annual power savings amount and electric charges savings amount, repair and maintenance cost, $CO_2$ reduction volume, and the profit from the sale of CER (certified emission reduction). As a result of analyzing economic efficiency, when the discount rate during the change of existing incandescent bulb lighting to LED lighting is 3.26%, the profit was 8,648,400,000 won. Accordingly, NPV was analyzed to have a 'positive (+)' value, which means that this change is profitable.

• KDI Journal of Economic Policy
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• v.12 no.2
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• pp.81-94
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• 1990

Illegal transactions such as blackmarketing and smuggling allegedly result from too restrictive trade policies. A recent U.S. Senate hearing on the blackmarketing of American goods imported into Korea for the purpose of supporting United States troops and their dependents stationed in Korea concluded with the allegation that Korea's highly restrictive trade practices are responsible for the emergence of the black market. It has also suggested that the removal of such restrictive trade policies would eliminate black market activities. This study addresses the relationship between trade policy and blackmarketing by investigating whether trade liberalization results in the reduction of illegal transactions, and whether the eradication of blackmarketing indeed improves social welfare. When both legally imported goods and illegally exchanged items command the same price, trade liberalization, meaning a decrease in tariff rates or an increase in import quotas, will increase the quantity of legal imports at the expense of illegally transacted goods on the black market. But the price of legally imported goods usually differs from that of illegally sold ones. In this case, a change in the relative prices of these two groups of goods due to a change in trade policy will give rise to income, as well as substitution, effects. Initially, a decrease in the import price due to a decrease in import tax rates or an increase in the allotted quota will reduce illegal transactions, since the decrease in the import price will induce the substitution of legal imports for illegally exchanged, but otherwise, identical goods. On the other hand, the demand for the illegally transacted goods will rise, because of the income effect of the reduced import price. Thus, assuming the positive income effect overwhelms the negative substitution effect, the demand for illegal goods will increase, thwarting the reduction of blackmarketing through trade liberalization. Yet, stepping up the enforcement measures which are geared to preventing blackmarketing itself will drastically reduce the extent of illegal transactions, since it increases the cost of blackmarketing and hence the price of the illegally transacted goods. What this study suggests is that the emergence of the black market in Korea should be attributed more to the excessive supply of duty-free goods imported through U.S. commissaries and exchanges than to the excessive demand for foreign goods. On the other hand, blackmarketing, in most cases, improves economic welfare, since it constitutes an increase in the "actual" amount of imported goods. Suppressing blackmarketing through stepped-up enforcement methods is beneficial only when the substitution effect of the legally transacted goods resulting from the increase in the price of the illegal goods prevails, since the increase in the demand for legal imports must override the decrease in the demand for black market goods as well as the negative income effect.

• Asia pacific journal of information systems
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• v.20 no.3
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• pp.139-166
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• 2010

The supply chain management (SCM) systems have emerged as strong managerial tools for manufacturing firms in enhancing competitive strength. Despite of large investments in the SCM systems, many companies are not fully realizing the promised benefits from the systems. A review of literature on adoption, implementation and success factor of IOS (inter-organization systems), EDI (electronic data interchange) systems, shows that this issue has been examined from multiple theoretic perspectives. And many researchers have attempted to identify the factors which influence the success of system implementation. However, the existing studies have two drawbacks in revealing the determinants of systems implementation success. First, previous researches raise questions as to the appropriateness of research subjects selected. Most SCM systems are operating in the form of private industrial networks, where the participants of the systems consist of two distinct groups: focus companies and vendors. The focus companies are the primary actors in developing and operating the systems, while vendors are passive participants which are connected to the system in order to supply raw materials and parts to the focus companies. Under the circumstance, there are three ways in selecting the research subjects; focus companies only, vendors only, or two parties grouped together. It is hard to find researches that use the focus companies exclusively as the subjects probably due to the insufficient sample size for statistic analysis. Most researches have been conducted using the data collected from both groups. We argue that the SCM success factors cannot be correctly indentified in this case. The focus companies and the vendors are in different positions in many areas regarding the system implementation: firm size, managerial resources, bargaining power, organizational maturity, and etc. There are no obvious reasons to believe that the success factors of the two groups are identical. Grouping the two groups also raises questions on measuring the system success. The benefits from utilizing the systems may not be commonly distributed to the two groups. One group's benefits might be realized at the expenses of the other group considering the situation where vendors participating in SCM systems are under continuous pressures from the focus companies with respect to prices, quality, and delivery time. Therefore, by combining the system outcomes of both groups we cannot measure the system benefits obtained by each group correctly. Second, the measures of system success adopted in the previous researches have shortcoming in measuring the SCM success. User satisfaction, system utilization, and user attitudes toward the systems are most commonly used success measures in the existing studies. These measures have been developed as proxy variables in the studies of decision support systems (DSS) where the contribution of the systems to the organization performance is very difficult to measure. Unlike the DSS, the SCM systems have more specific goals, such as cost saving, inventory reduction, quality improvement, rapid time, and higher customer service. We maintain that more specific measures can be developed instead of proxy variables in order to measure the system benefits correctly. The purpose of this study is to find the determinants of SCM systems success in the perspective of vendor companies. In developing the research model, we have focused on selecting the success factors appropriate for the vendors through reviewing past researches and on developing more accurate success measures. The variables can be classified into following: technological, organizational, and environmental factors on the basis of TOE (Technology-Organization-Environment) framework. The model consists of three independent variables (competition intensity, top management support, and information system maturity), one mediating variable (collaboration), one moderating variable (government support), and a dependent variable (system success). The systems success measures have been developed to reflect the operational benefits of the SCM systems; improvement in planning and analysis capabilities, faster throughput, cost reduction, task integration, and improved product and customer service. The model has been validated using the survey data collected from 122 vendors participating in the SCM systems in Korea. To test for mediation, one should estimate the hierarchical regression analysis on the collaboration. And moderating effect analysis should estimate the moderated multiple regression, examines the effect of the government support. The result shows that information system maturity and top management support are the most important determinants of SCM system success. Supply chain technologies that standardize data formats and enhance information sharing may be adopted by supply chain leader organization because of the influence of focal company in the private industrial networks in order to streamline transactions and improve inter-organization communication. Specially, the need to develop and sustain an information system maturity will provide the focus and purpose to successfully overcome information system obstacles and resistance to innovation diffusion within the supply chain network organization. The support of top management will help focus efforts toward the realization of inter-organizational benefits and lend credibility to functional managers responsible for its implementation. The active involvement, vision, and direction of high level executives provide the impetus needed to sustain the implementation of SCM. The quality of collaboration relationships also is positively related to outcome variable. Collaboration variable is found to have a mediation effect between on influencing factors and implementation success. Higher levels of inter-organizational collaboration behaviors such as shared planning and flexibility in coordinating activities were found to be strongly linked to the vendors trust in the supply chain network. Government support moderates the effect of the IS maturity, competitive intensity, top management support on collaboration and implementation success of SCM. In general, the vendor companies face substantially greater risks in SCM implementation than the larger companies do because of severe constraints on financial and human resources and limited education on SCM systems. Besides resources, Vendors generally lack computer experience and do not have sufficient internal SCM expertise. For these reasons, government supports may establish requirements for firms doing business with the government or provide incentives to adopt, implementation SCM or practices. Government support provides significant improvements in implementation success of SCM when IS maturity, competitive intensity, top management support and collaboration are low. The environmental characteristic of competition intensity has no direct effect on vendor perspective of SCM system success. But, vendors facing above average competition intensity will have a greater need for changing technology. This suggests that companies trying to implement SCM systems should set up compatible supply chain networks and a high-quality collaboration relationship for implementation and performance.

• Asian-Australasian Journal of Animal Sciences
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• v.13 no.6
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• pp.802-810
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• 2000

A total of 120 finishing crossbred pigs ($Landrace{\times}Large$ $White{\times}Duroc$) with equal numbers of barrows and gilts weighing 58.5 kg body weight were used in a feeding trial, and 6 pigs (three of each sex) were used in a metabolic trial to investigate the effect of phase feeding. Finishing period was divided into two phases and 4 different diets were fed for those periods. Growth performance was not significantly different among treatments within the same sex. This result showed that 16% crude protein for early finishing period and 14% crude protein diet for late finishing period should be optimum. During the early finishing period, only feed intake was significantly different between sexes (p<0.01), but in late finishing period daily weight gain (p<0.001) and feed intake (p<0.01) of barrows were significantly higher than those of gilts. During the early finishing period, digestibilities of dry matter, protein and phosphorus were significantly higher in gilts than in barrows (p<0.05). However, there was no treatment effect within same sex during the early and late finishing period. During early finishing period, excretion of N of pigs fed 16% CP diet in early and 14% CP diet in late-finishing period was less than that of pigs fed 17% CP diet in early and 15% CP diet in late-finishing period (p<0.05), but the difference was not significant. During the late finishing period, N excretion with two phase feeding was reduced by 8.5% compared with single feeding. In gilts, total cost reduction by two phase feeding compared to single feeding was 9.1%, but in barrows it was just 3.19%. Relative margin increased with two phase feeding by 2.5% in gUts and 0.2% in barrows. There was a tendency that backfat thickness at 10th rib of gilts was thinner than that of barrows (p>0.05). Within the same sexes, there was no treatment effect on back fat thickness (p>0.05). Carcass grade was improved by two phase feeding compared to single feeding. Carcass grade of gilts was significantly better than that of barrows (p<0.001). From this results, it is concluded that finishing pigs could be fed two-phase diets to improve profit and reduce pollution.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.12
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• pp.5151-5156
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• 2010

In the previous researches for storm sewer design, the flow paths in overall network were determined to minimize the construction cost and then, it was not considered the superposition effect of runoff hydrographs in the sewer pipes. However, in this research, the flow paths are determined considering the superposition effect to reduce the inundation risk by controlling and distributing the flows in the sewer pipes. This is accomplished by distributing the inflows that enter into each junction by changing the flow path in which pipes are connected between junctions. In this paper, the superposition effect and peak outflows at outlet were analyzed considering the changes of the flow paths in the sewer network. Then, the flow paths are determined using genetic algorithm and the objective function is to minimize the peak outflow at outlet. As the applied result for the sample sewer network, the difference between maximum and minimum peak outflows which are caused by the change of flow path was about 5.6% for the design rainfall event of 10 years frequency with 30 min. duration. Also, the typhoon 'Rusa' which occurred at 2002 was applied to verify the reduction of inundation risk for the excessive rainfall, and then, the amount of overflows was reduced to about 31%.

• Korean Journal of Construction Engineering and Management
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• v.16 no.6
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• pp.101-111
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• 2015

The modular construction method has been getting more attention followed by global eco-friendly trend as the domestic construction industry has focused more on remodeling and extension work. The modular construction method is an industrialized construction system which is not likely as the existing construction method it manufactures more than 70% modules at the factory then assembling can be completed in a short amount of time on site. The modular construction method has various strengths; shortening of construction period by on-site work decrease, weight pressure reduction by usage of light steel frames and cost saving by repetitive manufacturing. However, it is currently not expanded due to the existing commercialized construction method. Therefore, this research is in order to help the related authorities make decisions to select the construction method and motivate expansion of modular construction method which can be utilized effectively in the extension works. The intention of this research is to stress differentiation from other construction methods in construction period, construction expenses, labor and forces by comparing and analyzing actual cases, to inform competitiveness of modular construction method by concrete effect analysis and to support adoption of the modular construction method into the domestic industry.

• Land and Housing Review
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• v.12 no.3
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• pp.39-50
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• 2021

This research aims to provide guidelines with the appropriate type of smart bus stop to reduce the concentration of fine dust. To this end, we divided smart bus stops into two types: closed and open bus stops. The estimated reduction effect was compared and analysed by measuring the estimated PM₁₀ and the estimated PM_2.5 at five locations inside and outside a smart bus stop located in Gangnam gu, Seoul. The effect of reducing the amount of the fine dust concentration in external space was insignificant for both types of bus stops. The different effect of reducing the concentration of the amount between in internal space was relatively significant: the fine dust concentration was 26.0 ㎍/m³ for PM₁₀ and 20.2 ㎍/m³ for PM_2.5 at open-type bus stops; whilst was 2.4 ㎍/m³ for PM₁₀ and 1.8 ㎍/m³ for PM_2.5 at closed type bus stops. Based on the findings, a closed type bus stop is recommended when considering the cost of reducing fine dust. In addition, due to the ineffectiveness of reducing the amount of fine dust from the outside of the bus stop, additional provision of smart bus stops is required particularly in locations where demand exceeds the capacity of the inside. A clear definition of smart bus stop and it's minimum standard should also be considered.

• Korean Journal of Weed Science
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• v.30 no.3
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• pp.272-281
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• 2010

The objective of this research was to find out the weed management techniques in environment-friendly rice paddy fields through the study on herbicidal effects and problems of various organic materials. This experiment was conducted under different conditions of weed species and weed densities in environment-friendly rice paddy fields. There was no difference in weedy efficacy on golden apple snail (GAS), paper mulching (PM), and machine weeding (MW) between low and high weed densities. However, the effect of weed control in rice bran (RB) and effective microorganism (EM) + molasses was higher in high weed density than in low weed density. In general, the effect of weed control as affected by various organic materials was in the order of GAS (97-100%) > PM (93-98%) > RB (15-80%) > EM (7-31%). GAS provided excellent control of all weed species tested except for Persicaria hydropiper. PM gave acceptable control of the weed species except for Echinochloa crus-galli, Ludwigia prostrata, and Eleocharis kuroguwai. However, MW gave fair control (70% biomass reduction) of all weed species tested. BR followed by MW or EM followed by MW treatments had similar effect on weed control compared to each treatment alone. However, BR followed by GAS or EM followed by GAS provided 100% control of weed species tested. The level of rice foliar injury caused by various organic materials was in the order of GAS and MW (10-20%) > RB (10-15%) > PM and EM (5-7%). Typical symptoms of organic materials are wilting, inhibition of growth, missing hill, and reduction of tiller. Cost for weed control of GAS, RB, EM, and PM were 2.1, 3.1, 2.3, and 13.2 times higher than that of the herbicide. These data indicate that GAS was the best method for weed management in environmentfriendly rice paddy fields. Further study is required to elucidate the mechanisms underlying the rice injury as affected by GAS.