• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.3
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• pp.308-310
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• 2022

Ultrawide bandgap gallium oxide (Ga₂O₃) semiconductors are known to have excellent photocatalytic properties due to their high redox potential. In this study, CO₂ reduction is demonstrated using nanostructured Ga₂O₃ photocatalyst under ultraviolet (254 nm) light source conditions. After the CO₂ reduction, C₂H₄ remained as a by-product in this work. Nanostructured Ga₂O₃ photocatalyst also showed an excellent endurance characteristic. Photogenerated electron-hole pairs boosted the CO₂ reduction to C₂H₄ via nanostructured Ga₂O₃ photocatalyst, which is attributed to the ultrawide and almost direct bandgap characteristics of the gallium oxide semiconductor. The findings in this work could expedite the realization of CO₂ reduction and a simultaneous C₂H₄ production using a low cost and high performance photocatalyst.

• Journal of Hydrogen and New Energy
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• v.27 no.4
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• pp.447-461
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• 2016

Recently, the Renewable Fuel Standard(RFS) has been commenced from July 31, 2015 in the New and Renewable Energy Act for expanding the supply of renewable energy and reduction of national GHG target in Korea. The biodiesel is only a means of implementation for the RFS, therefore the biodiesel supply expansion is important for fulfilling the RFS obligation policy. The major key points of the biodiesl supply are expanding domestic feedstocks due to the over 60% dependence on foreign feedstock and reducing the price of feedstock because of the over 70% occupation of feed stock price in the biodiesl production cost. Therefore, we estimated actual amount of potential feedstocks which are possible to use for biodiesl production in Korea and investigated technical and political improvements for expanding biodiesl. For estimating a potential feedstocks, first selected the potential biodiesl feedstocks by investigating the status of global biodiesl feedstocks and then analyzed the possible potential amount of each feedstock by surveying the generation situations, the distribution structures and the technical level.

• Ocean and Polar Research
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• v.28 no.1
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• pp.25-35
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• 2006

Fisheries buyback programs have been implemented from 1994 in Korea, and its scale is estimated to have a value of 930 billion won, which is compounded for eight years since 1994. The paper evaluates the programs' economic and financial viability, and predicts efficient ways about how much and how long to reduce fisheries vessels so as to pursue a target biomass at MSY, For the specific purpose of the paper, aggregate fisheries stock dynamics and catch functions are specified and estimated by yearly catch and fishing effort data from 1970 to 2001, using ASPIC model and Schaefer's logistic production model. Results show that the fisheries stock in Korea has steadily declined since 1970, and that Korean fisheries overexploitation has steadily increased. Using cost-benefit analysis method, the buyback program holds the economic and financial feasibility even if the scale of buyback programs is not sufficient to avoid the downward trend in fisheries stock and harvest. The potential investment scale is predicted in several alternative scenarios using the sensitivity analysis method. The results recommend the annual reduction of 46%, 12% or 20% for the next one year, five years or three years, respectively so that the target biomass at MSY may be reached in 25 years.

• Environmental Engineering Research
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• v.19 no.4
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• pp.363-367
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• 2014

One chambered sediment microbial fuel cell (SMFC) was equipped with Fe, brass (Cu/Zn), Fe/Zn, Cu, Cu/carbon cloth and graphite felt anode. Graphite felt was used as common cathode. The SMFC was membrane-less and mediator-less as well. Order of anodic performance on the basis of power density was Fe/Zn ($6.90Wm^{-2}$) > Fe ($6.03Wm^{-2}$) > Cu/carbon cloth ($2.13Wm^{-2}$) > Cu ($1.13Wm^{-2}$) > brass ($Cu/Zn=0.24Wm^{-2}$) > graphite felt ($0.10Wm^{-2}$). Fe/Zn composite anode have twisted 6.73% more power than Fe alone, Cu/carbon cloth boosted power production by 65%, and brass (Cu/Zn) produced 65% less power than Cu alone. Graphite felt have shown the lowest electricity generation because of its poor galvanic potential. The estuarine sediment served as supplier of oxidants or electron producing microbial flora, which evoked electrons via a complicated direct microbial electron transfer mechanism or making biofilm, respectively. Oxidation reduction was kept to be stationary over time except at the very initial period (mostly for sediment positioning) at anodes. Based on these findings, cost effective and efficient anodic material can be suggested for better SMFC configurations and stimulate towards practical value and application.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.152-157
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• 2003

Diesel-contaminated soils were ozonated for different times (0 - 900 min) and incubated for 9 wk to monitor petroleum hydrocarbons (PH)-degradative potential of indigenous microorganisms in the soils. Increased ozonation time decreased not only concentration of PH but also number of microorganisms in the soils. Microorganisms in the ozonated soils increased during 9-wk incubation as monitored by culture- and nonculture-based methods. Higher (1-2 orders of magnitude) cell number was observed by quantitative analysis of soil DNA using probes detecting genes encoding 165 rRNA(rrn), naphthalene dioxygenase (nahA), toluene dioxygenase (todC), and alkane hydroxylase (alkB) than microbial abundance estimated by culture-based methods. Such PH-degraders were relatively a few or under detection limit in 900-min ozonated soil. Further PH-removal observed during the incubation period supported the presence of PH-degraders in ozonated soils. Highest reduction (25.4%) of total PH (TPH) was observed in 180-min ozonated soil white negligible reduction was shown in 900-min ozonated soil during the period, resulting in lowest TPH-concentration in 180-min ozonated soil among the ozonated soils. Microbial community composition in 9-wk incubated soils revealed slight difference between 900-min ozonated and unozonated soils as analyzed by whole cell hybridization using group-specific rRNA-targeted oligonucleotides. Results of this study suggest that appropriate ozonation and subsequent biodegradation by indigenous microorganisms may be a cost-effective and successful remediation strategy for PH-contaminated soils.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.40 no.3
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• pp.42-47
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• 2008

For the purpose of reduction of production cost in the industrial papermaking process, the use of waste paper has been more and more increased as a fibrous raw material, and the closed system of white water became closed more than ever. "Scum" indicates the floated sludge by a flotation during primary wastewater treatment process in paper mills. If the scum is used as the raw material, it could reduce both the raw material and solid waste treatment cost with even small quantity. In this study, the element survey and the toxicity measurement was carried out for recycling scum. A load factor of stock preparation process in paper mills was measured by somerville screen. Physical properties of paper sheet containing the accepted scum from the stock of AOCC or KOCC were evaluated. The result of this study shows that recycling scum has potential to be used in paper making system. It also might be able to reduce the required energy used by the pressing or drainage process, the raw material cost, and solid waste treatment cost due to the recycling of scum.

• Journal of Korean Society for Atmospheric Environment
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• v.19 no.E1
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• pp.21-28
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• 2003

An auxiliary device, called Post Cyclone (PoC). had been introduced and primarily examined in earlier works which proved the reduction of the emission of fine dust from the gas-solid cyclones without incurring significant increase of cost and pressure drop. It has been known that the PoC has some advantages over other secondary dust treatment devices such as (a) simple design, (b) low cost of manufacture, (c) minimum additional pressure drop, (d) high recoverbility of the product dust, and (e) simplicity of operation. Despite the potential advantage, however, lack of practical data confined its plausible application in wide areas. Thus, in this work, a few serial experiments were conducted in terms of a few operation conditions, and the particle trajectories throughout the cyclone set-up were visually analyzed by using a commercial computer simulation program (FLUENT).

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.209-209
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• 2006

Ultra-fine fibers are spun by expensive fiber spinning technology using special spinnerets. Ultra-fine fibrous materials have attracted considerable attentions because of their potential applications as high performance wiping cloths, water absorbent sound proofing materials and moisture transfer sporting good. However, production expense of ultra-fine fibers is 5 to 7 times higher than general textile materials. The objective of this research is to develop cost-effective recycling process to produce multi-functional ultra-fine fibrous material in terms of the development of garnetting and carding machines for ultra-fine fibrous material waste and scrap. The efficiency of sound absorption for the recycled polyester nonwoven increased with decreasing length and thickness of component fibers, which was attributed to the reduction of air permeability. It is expected that high value and cost-effective textile products are developed using ultra-fine fibrous wastes and that sound proofing material and oil absorbent f

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.1
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• pp.51-58
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• 2001

The use of tailor welded blanks (TWB) in automotive applications is increasing due to the potential of weight and cost saving. The object of this study is development of the front side member by static analysis and crash simulations. Accord-ing to the results , energy absorption and barrier force is very important parameter to control passenger safety and deforma-tion shape. A energy absorbability point of view, tailor welded blanks is most effective to absorb energy than non-twb. Non-TWB front side member and TWB applied front side member were simulated. It shows reduce stmping parts weight reduction and cost down.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.403-408
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• 2000

The use of tailor welded blanks(TWB) in automotive applications is increasing due to the potential of weight and cost saving In this study, the front side member of passenger car is developed by typical analysis and crash simulations. According this results, energy absorption and barrier force is very important to control passenger safety and deformation shape. For that purpose, it is most effective to absorb energy more tailor welded blanks front side member than non-twb. The front side member with twb is simulated, in which reduced stamping parts, weight reduction and cost down.