• Journal of Korean Society of Environmental Engineers
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• v.31 no.11
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• pp.1007-1018
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• 2009

Hydrocyclone is widely used in industry, because of its simplicity in design, high capacity, low maintenance and operational cost. The separation action of a hydrocyclone treating particulate slurry is a consequence of the swirling flow that produces a centrifugal force on the fluid and suspended particles. In spite of hydrocyclone have many advantage, the application for treatment of urban stormwater case study were rare. We conducted a laboratory scale study on treatable potential of micro particles using hydrocyclone filter (HCF) that was a combined modified hydrocyclone with perlite filter cartridge. Since it was not easy to use actual storm water in the scaled-down hydraulic model investigations, it was necessary to reproduce ranges of particles sizes with synthetic materials. The synthesized storm runoff was made with water and addition of particles; ion exchange resin, road sediment, commercial area manhole sediment, and silica gel particles. Experimental studies have been carried out about the particle separation performance of HCF-open system and HCF-closed system. The principal structural differences of these HCFs are underflow zone structure and vortex finder. HCF was made of acryl resin with 120 mm of diameter hydrocyclone and 250 mm of diameter filter chamber and overall height of 800 mm. To determine the removal efficiency for various influent concentrations of suspended solids (SS) and chemical oxygen demand (COD), tests were performed with different operational conditions. The operated maximum of surface loading rate was about 700 $m^3/m^2$/day for HCF-open system, and 1,200 $m^3/m^2$/day for HCF-closed system. It was found that particle removal efficiency for the HCF-closed system is better than the HCF-open system under same surface loading rate. Results showed that SS removal efficiency with the HCF-closed system improved by about 8~20% compared with HCF-open system. The average removal efficiency difference for HCF-closed system between measurement and CFD particle tracking simulation was about 4%.

• Journal of Soil and Groundwater Environment
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• v.13 no.4
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• pp.30-39
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• 2008

The uranium removal efficiency of rhizofiltration was investigated in lab scale experiment. Three plants such as sunflower (Helianthus annuus L.), bean (Phaseolus vulgaris var.), and Indian mustard (Brassica juncea (L.) Czern.) were cultivated in artificially contaminated solution by uranium at 30 ${\mu}g$/L and 80 ${\mu}g$/L for 72 hours. The removal efficiencies of three cultivars were calculated from the ICP/MS analysis of uranium mass in solution and the plant. For Helianthus annuus L., more than 80% of initial uranium were removed from the solution and the uranium concentration of residual solution maintained lower than 10 ${\mu}g$/L. For Phaseolus vulgaris var. and Brassica juncea (L.) Czern., their uranium removal efficiencies ranged from 60 to 80%. Even the uranium concentration of solution was higher than 500 ${\mu}g$/L, these cultivars removed more than 70% of initial uranium by rhizofiltration, suggesting that the rhizofiltration has a great capability to remove uranium in the contaminated groundwater. The removal efficiency of rhizofiltration by using Brassica juncea (L.) Czern decreased from 83% to 42% with the increase of pH in solution. From the results of the analysis for the uranium accumulation in plants, 99% of uranium transferred into the plant from solution were accumulated in the root and only 1% of uranium existed in the shoot part (including leaves), suggesting that the cost and the time to treat massive grown plants after the rhizofiltration could be dramatically cut down because only their root parts needs to be treated. Finally, the genuine groundwater having high uranium concentration (81.4 ${\mu}g$/L), sampled from Daejoun area, was used in the experiment. The uranium removal efficiency of Helianthus annuus L. for the real groundwater was higher than 95%, investigating that the rhizofiltration is the very useful method to remediate uranium contaminated groundwater.

• Journal of the Korean Institute of Landscape Architecture
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• v.39 no.6
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• pp.98-109
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• 2011

Habitat restoration initiative is an important factor for the on-site preservation of butterflies. A new habitat necessitates the investigation of the ecology of the butterfly, the landscape of the habitat, the work process, and a cost analysis. In this study, these factors were analyzed through1) re-consideration of the secured results from three years of field work, and 2) a habitat area estimation conducted according to the presence or absence of larvae and adults via a Parnassius bremeri Bremer survey. The investigation of the natural habitat, done for both larvae and adult butterflies found in South Korea, suggested that multiple patches with a minimum size exceeding $300m^2$ and with an average size of about $1,600m^2$were required for survival of this butterfly. Therefore, more than five patches should be considered for butterfly habitat and patches should have similarity to the present habitat environment with transplantation plans for diet plants and honeydew plants. In addition, to activate the migration of the butterfly, cutting down trees that are obstacles to migration, minimizing the distance between patches and the addition of a stepping patch are also required. A patch connectivity analysis showed that patches should be located within 300m of neighboring patches, as the migration of the butterfly will fail if it is more than 600m. Additionally, more than $10,000m^2$ for a single patch or a patch network composed more than five patches over $1,600m^2$ in size were recommended, with a total patch size of $8,000m^2$. Additionally, neighboring multiple patch networks are more desirable than a single habitat in the event a cyclic habitat pattern arises. In this study, we suggest a habitat restoration and optimal prerequisites for a butterfly habitat. It is expected that this research will lead to the creation of a good model for the restoration of butterfly species.

• Environmental and Resource Economics Review
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• v.24 no.3
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• pp.573-605
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• 2015

This study proposed scenarios of tax reform regarding taxation on bituminous coal for power generation since July 2015 and July 2014, estimated its impact on SMP, settlement price, tax revenue from year 2015 to year 2029. These scenarios are compared with those of the standard scenario. To estimate them, the power system simulation was performed based on the government plan, such as demand supply program and the customized model to fit Korea's power system and operation. Imposing a tax on bituminous coal for power generation while maintaining tax neutrality reducing tax rate on LNG, the short-term SMP is lowered than the one of the standard scenario. Because the cost of nuclear power generation is still smaller than costs of other power generation, and the nuclear power generation rarely determines SMPs, the taxation impact on SMP is almost nonexistent. Thus it is difficult to slow down the electrification of energy consumption due to taxation of power plant bituminous coal in the short term, if SMP and settlement price is closely related. However, in the mid or long term, if the capacity of coal power plant is to be big enough, the taxation of power plant bituminous coal will increase SMP. Therefore, if the tax reform is made to impose on power plant bituminous coal in the short term, and if the tax rate on LNG is to be revised after implementing big enough new power plants using bituminous coal, the energy demand would be reduced by increasing electric charges through energy tax reform. Both imposing a tax on power plant bituminous coal and reducing tax rate on LNG increase settlement price, higher than the one of the standard scenario. In the mid or long term, the utilization of LNG complex power plants would be lower due to an expansion of generating plants, and thus, the tax rate on LNG would not affect on settlement price. Unlike to the impact on SMP, the taxation on nuclear power plants has increased settlement price due to the impact of settlement adjustment factor. The net impact of energy taxation will depend upon the level of offset between settlement price decrease by the expansion of energy supply and settlement price increase by imposing a tax on energy. Among taxable items, the tax on nuclear power plants will increase the most of additional tax revenue. Considering tax revenues in accordance with energy tax scenarios, the higher the tax rate on bituminous coal and nuclear power, the bigger the tax revenues.

• Korean Journal of Environmental Agriculture
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• v.21 no.3
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• pp.178-188
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• 2002

Constructed wetlands typically cost less to build and operate, and require less energy than standard mechanical treatment technology but they have similar performance to centralized wastewater treatment plants. Therefore, they were constructed especially many in rural areas, where are small villages but not industries. Plantless column tests were performed to investigate the possibility on using zeolite as a filter medium of constructed wetland for the wastewater treatment. Removal efficiency was $COD_{Cr}$ 94.63% T-P 41.41% and $NH_4^+-N$ 99.75% at hydraulic load 314 $L/m^2{\cdot}d$ and filtering height 100 cm filled with a zeolite mixture. This zeolite mixture consisted of 1 : 1 by volume of zeolites in the diameter range of 0.5 to 1 mm and 1 to 3 mm. Accordingly, hydraulic load 314 $L/m^2{\cdot}d$ was considered as optimal. Three zeolite mixtures were used to determine the optimal mixing ratio by volume of a zeolite (A) in the diameter range of 0.5 to 1 mm to a zeolite (B) in the diameter range of 1 to 3 mm 1 : 3, 1 : 1 and only B in A to B by volume were tested at hydraulic load 314 $L/m^2{\cdot}d$ and filtering height 100 cm $COD_{Cr}$ removal efficiency was more than 89% at mixing ratios of 1 : 3 and 1 : 1 in A to B. That of T-P ranged 56.42 to 58.72% and, that of T-N and $NH_4^+-N$ was 87% and 99% regardless of mixing ratios of two zeolites. Removal efficiency was lower at the column filled with only B. Removal efficiency was better at Inter medium filled with mixing ratio 1 : 1 in A to B than with the other mixing ratios. Thus, it was found that the mixture of mixing ratio 1 : 1 in A to B was appropriate far Inter medium of constructed wetland Removal efficiency was higher in down-flow than in up-flow, and all contaminants were removed most in 20 cm filter height near feeding area.

• Journal of Internet Computing and Services
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• v.16 no.2
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• pp.49-55
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• 2015

According to the statistics of traffic accidents over recent 5 years, traffic accidents during the night times happened more than the day times. There are various causes to occur traffic accidents and the one of the major causes is inappropriate or missing street lights that make driver's sight confused and causes the traffic accidents. In this paper, with smartphones, we designed and implemented a lane luminance measurement application which stores the information of driver's location, driving, and lane luminance into database in real time to figure out the inappropriate street light facilities and the area that does not have any street lights. This application is implemented under Native C/C++ environment using android NDK and it improves the operation speed than code written in Java or other languages. To measure the luminance of road, the input image with RGB color space is converted to image with YCbCr color space and Y value returns the luminance of road. The application detects the road lane and calculates the road lane luminance into the database sever. Also this application receives the road video image using smart phone's camera and improves the computational cost by allocating the ROI(Region of interest) of input images. The ROI of image is converted to Grayscale image and then applied the canny edge detector to extract the outline of lanes. After that, we applied hough line transform method to achieve the candidated lane group. The both sides of lane is selected by lane detection algorithm that utilizes the gradient of candidated lanes. When the both lanes of road are detected, we set up a triangle area with a height 20 pixels down from intersection of lanes and the luminance of road is estimated from this triangle area. Y value is calculated from the extracted each R, G, B value of pixels in the triangle. The average Y value of pixels is ranged between from 0 to 100 value to inform a luminance of road and each pixel values are represented with color between black and green. We store car location using smartphone's GPS sensor into the database server after analyzing the road lane video image with luminance of road about 60 meters ahead by wireless communication every 10 minutes. We expect that those collected road luminance information can warn drivers about safe driving or effectively improve the renovation plans of road luminance management.

• Journal of the Korean Chemical Society
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• v.54 no.5
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• pp.556-566
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• 2010

A new kinetic spectrophotometric method is developed for the measurement of Mn(II) in natural water samples. The method is based on the catalytic effect of Mn(II) with the oxidation of Gallocyanin by $KIO_4$ using nitrilotriacetic acid (NTA) as an activation reagent at 620 nm. The optimum conditions obtained are $4.00{\times}1^{-5}\;M$ Gallocyanin, $KIO_4$, $1.00{\times}10^{-4}\;M$ NTA, 0.1 M HAc/NaAc buffer of pH = 3.50, the reaction time of 5 min and the temperature of $30^{\circ}C$. Under the optimum conditions, the proposed method allows the measurement of Mn(II) in a range of $0.1\;-\;4.0\;ng\;mL^{-1}$ and with a detection limit of down to $0.025\;ng\;mL^{-1}$. The recovery efficiency in measuring the standard Mn(II) solution is in a range of 98.5 - 102%, and the RSD is in a range of 0.76 - 1.25%. The newly developed kinetic method has been successfully applied to the measurement of Mn(II) in both some environmental water samples and certified standard reference river water sample, JAC-0031 with satisfying results. Moreover, few cations and anions interfere with the measurement of Mn(II). Compared with the other catalytic-kinetic methods and instrumental methods, the proposed kinetic method shows fairly good selectivity and sensitivity, low cost, cheapness, low detection limit and rapidity. It can easily and successfully be applied to the real water samples with relatively low salt content and complex matrices such as bottled drinking water, cold and hot spring waters, lake water, river water samples.

• International Commerce and Information Review
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• v.13 no.4
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• pp.177-201
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• 2011

Myanmar had fallen behind other southeast asian nations since Burmese way to Socialism settled down. However, historically second election in Myanmar hold in 2011 and dramatic changes in areas such as Special Economic Zone announcement, the very huge inflows of foreign direct investment in a year of 2009, the infrastructure building projects, a permit of the right to strike for Labour Organization in Myanmar etc. Particularly, Foreign investments and trade with neighbouring countries are actively growing and also with Korea. But investments of Korea in Myanmar relatively are not diversity, with limited sectors such as mining and sewing manufacturing. In this point of view, this paper is trying to make implications for strategies of entry and investments of Korea in Myanmar by using previous papers related to Myanmar economies, trade and foreign investments with updated statistical data. The implications for Korea is that recently Myanmar economy is in its early stages of development. Although it can occur huge demand of railway, road, communications and constructions related to social infrastructures essentially needed for development of a country, these sectors relatively need huge investments. On the other hands, textile and sewing industry relatively need smaller investments in which investors can utilize low labour cost and a position for export to third countries. But those firms which set up for those purpose in Myanmar might have trouble creating domestic markets in future. Moreover, due to demand which occur in the early stage of growth in Myanmar, trade volume tend to increase and trading is also possible to invest but Myanmar still have lots of problems with infrastructure such as road and logistics and we need to make pre-survey for the costs and benefits of our products Finally, Myanmar government is trying to promote and encourage some of industries such as export-oriented industry, import substitution industry and labour-intensive industry. It can also means they will accumulate capital which can be sources for Myanmar economic growth.

• Journal of the Korean Electrochemical Society
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• v.9 no.3
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• pp.124-131
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• 2006

For commercialization of molten carbonate fuel cell (MCFC), it has some problems to be overcome such as decrease of porosity and thickness of the anode under the operating condition (at $650^{\circ}C$ and working pressure of more than 2 $kg_f/cm^2$). Recently, Ni-Al alloy anode has been proposed to replace the conventional Ni-Cr anode as an alternative material to resist a creep and inhibit the sintering. The objective of this research is to sinter the green sheet of Ni-Al alloy anode during single cell pre-treatment process, which has several advantages like cost down and simplification of manufacturing process. However, the Ni-Al alloy anode prepared with a conventional pre-treatment process showed the phase separation of Ni-Al alloy and formation of micropore(${\leqq}0.4{\mu}m$), resulting in low creep resistance and high electrolyte re-distribution. In order to prevent the Ni-Al alloy anode from phase-separating, nitrogen gas was used in the process of pre-treatment. Introducing the nitrogen, the phase separation from Ni-Al alloy into nickel and alumina was minimized and increased creep resistance. However, there was some micropore formation on the surface of Ni-Al alloy anode during the cell operation due to creation of lithium aluminate. Addition of more amount of electrolyte into a cell, especially at cathode, made the cell performance stable for 2,000 hrs. Consequently, it was possible to make the Ni-Al alloy anode with good creep resistance by the modified in-situ sintering technique.

• Journal of Korean Society of Transportation
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• v.24 no.5 s.91
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• pp.89-108
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• 2006

Korea has been entering the ageing society as the population of age over 65 shared over 7% since the year 2000. The ageing society needs to have transportation facility considering elderly people's travel behavior. This study aims to understand the elderly people's travel behavior using recent data in Korea. The activity schedule approach begins with travel outcomes are part of an activitv scheduling decision. For tho?e approach. used discrete choice models (especially. Nested Logit Model) to address the basic modeling problem capturing decision interaction among the many choice dimensions of the immense activity schedule choice set The day activity schedule is viewed as a sot of tours and at-home activity episodes tied togather with overarching day activity pattern using the Seoul Metropolitan Area Transportation Survey data, which was conducted in June, 2002. Decisions about a specific tour in the schedule are conditioned by the choice of day activity pattern. The day activity scheduling model estimated in this study consists of tours interrelated in a day activity pattern. The day activity pattern model represents the basic decision of activity participation and priorities and places each activity in a configuration of tours and at-home episodes. Each pattern alternative is defined by the primary activity of the day, whether the primary activity occurs at home or away, and the type of tour for the primary activity. In travel mode choice of the elderly and non-workers, especially, travel cost was found to be important in understanding interpersonal variations in mode choice behavior though, travel time was found to be less important factor in choosing travel mode. In addition, although, generally, the elderly was likely to choose transit mode, private mode was preferred for the elderly over 75 years old owing to weakened physical health for such things as going up and down of stairs. Therefore. as entering the ageing society, transit mode should be invested heavily in transportation facility Planning tor improving elderly transportation service. Although the model has not yet been validated in before-and-after prediction studies. this study gives strong evidence of its behavioral soundness, current practicality. and potential for improving reliability of transportation Projects superior to those of the best existing systems in Korea.