• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.6
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• pp.660-665
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• 2002

In Korea, an olive flounder is very popular fish food item. However, due to the increasing human population, the present catches of the olive flounder may not be sufficient to satisfy the present demand. To increase the supply of the olive flounder, aquaculture has been begun. An interest in the aquaculture of the olive flounder has been increased recently because of its characteristics of good growth and high price in the market, However, the productivity of the olive flounder aquaculture depends on economic inputs such as fuels, facilities, and labor. The rapid growths of the olive flounder aquaculture and the concerns about economic and ecological sustainability have focused peoples attention on the aquaculture industry. In this study, an energy systems model was built to simulate the variation of sustainability on the aquaculture of olive flounder, The results of simulation based on calibration data in 1995 show that olive flounder production yield and asset slowly increase to steady state because of the law of supply and demand. The results of simulation based on the variation of oil price show that the more increase the oil price, the more decrease the olive flounder economic yield and asset. Energy sources required for systems determine the sustainability of systems. Conclusionally, the present systems of the olive flounder aquaculture should be transformed to ecological-recycling systems or ecological engineering systems which depend on renewable resources rather than aquaculture systems which depend on fossil fuels, and be harmonized with the fishing fisheries by the sustainable use of renewable resources in the carrying capacity.

• Analyses & Alternatives
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• v.5 no.2
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• pp.77-105
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• 2021

Natural gas consumption in Asia is growing at fast tempo because of various factors such as economic growth in the region, urbanization, coal-to-gas switch at power and industry sector. Due to geographical characteristics and lack of international pipeline connections between countries in the continent, majority of natural gas exported to Asian consumers is transported by tankers on the sea in the form of liquefied natural gas. As Asian market is the most lucrative market with the fastest demand growth, the competitions between LNG sellers for market share in Asian market are strengthening. The competitions accelerated, especially after the introduction of large volume of incremental supply into the market by new exporters from the U.S., Australia, and Russia. Cheniere Energy, the first exporter of liquefied natural gas (LNG) in the lower 48 states of U.S. has not adopted the traditional price formation mechanism and business model. Traditionally, prices of long-term LNG contracts have been indexed to the price of competing fuels, such as crude oil. The company adopted a pricing mechanism and business model based on a cost-plus system. Cheniere Energy opted for the safer and the risk-free pricing system, that annually guarantees a fixed amount of revenue to the seller. The company earns the same amount of money, regardless of natural gas price dynamics in the domestic and international market, but possibly with less revenue. However, by introducing and successfully implementing the safer and risk- free business model, Cheniere Energy, a company of a relatively smaller size in comparison with major oil and gas companies, became an example to other smaller-sized companies in the U.S. The company's business model demonstrated how to enter and operate LNG business amid increasing competitions among sellers in the U.S. and international market.

• Journal of the Korean Society of Food Culture
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• v.22 no.4
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• pp.454-461
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• 2007

Antioxidative and antimicrobial activities were carried out on the Citrus Unshju peel solvent extracts in order to discover new functional activities. The amounts of polyphenol in 70% metanol extract (MtEx) was measured as 836.8 mg% in Citrus Unshju peel. The EDA (electron donating ability) of 0.01, 0.02 and 0.1% MtEx in Citrus Unshju peel were measured as levels of 81.3, 86.0 and 89.6%. The nitrite scavenging effects of Citrus peel were also determined as the levels of 34.4% (pH 1.2) and 19.5% (pH 7.0). The pH of react solution was more acidic, the nitrite scavenging effect was more increased. The order of antioxidatives was shown as TBHQ > BHT > TOC > ChEx > EaEx > EtEx > WaEx > Control in corn germ oil and TBHQ > ChEx > EaEx > BHT > EtEx > WaEx > TOC > Control in canola oil. A number of the extracts were certified to have antimicrobial activities for a small number of micro-organisms, similar gram negative and positive micro-organisms. According to the results above, it was summerized that Citrus Unshju peel had the higher total polyphenol, EDA, nitrite scavenging effects and antimicrobial activities. Also isolated extract from ChEx and EaEx had high antioxidative, these effects were very similar to that of ${alpha}$-tocopherol and BHT. It would be proposed that Citrus peel can become a new natural source for antioxidative agents in future food industry.

• Journal of Energy Engineering
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• v.25 no.1
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• pp.29-42
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• 2016

This study analyzes the economic efficiency of utilizing hot waste water at a thermoelectric power plant, which is part of recent projects supported by the Korean government to foster new energy industry. The author proposes an institution that provides economic incentives to promote the project. Based on a method of calculating Levelized cost of energy (LCOE), this study finds that the LCOE of using hot waste water at power plants is higher than that of oil boiler, biomass and a power plant's auxiliary steam but similar to that of the geothermal system. Also, according to sensitivity analysis on the LCOE of each element in the system of using hot waste water, a distance of heat supply is most sensitive. Therefore, this study shows that when the government devises an incentive-based institution to expand the project of utilizing hot waste water, it is necessary to establish Renewable Energy Certificate (REC) weights that are differentiated by a distance of heat supply.

• Korean Journal of Agricultural Science
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• v.43 no.5
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• pp.761-768
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• 2016

Recently, swine production costs have increased due to increased feed cost, especially the price of corn and soybean meals. Soybean meal is traditionally an expensive ingredient, but the price of corn has dramatically increased because of increased biofuel production. This change has resulted in the swine industry looking for alternatives in order to reduce feed cost, resulting in decreased production costs. Thus, various alternatives have been used as feed ingredients to replace corn, soybean meal, or other expensive ingredients. One othercandidate may be palm kernel co-products that are a by-product of oil extraction from palm fruits. Palm kernel co-products have not been used in swine diets due to high fiber content and imbalanced amino acids compared with corn and soybean meal. However, recent studies showed that palm kernel co-products did not have any negative effects on growth performance of pigs when they replaced some proportions of corn and soybean meal. In addition, palm kernel co-products may provide some physiological properties to pigs by modifying gut microbiota and/or immunity of pigs, resulting in improvement of growth and health of pigs. Therefore, the value of palm kernel co-products were reviewed as one of the alternatives for corn, soybean meal, or other major ingredients in swine diets.

• Carbon letters
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• v.22
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• pp.1-13
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• 2017

Porous materials play a vital role in science and technology. The ability to control their pore structures at the atomic, molecular, and nanometer scales enable interactions with atoms, ions and molecules to occur throughout the bulk of the material, for practical applications. Three-dimensional (3D) porous carbon-based materials (e.g., graphene aerogels/hydrogels, sponges and foams) made of graphene or graphene oxide-based networks have attracted considerable attention because they offer low density, high porosity, large surface area, excellent electrical conductivity and stable mechanical properties. Water pollution and associated environmental issues have become a hot topic in recent years. Rapid industrialization has led to a massive increase in the amount of wastewater that industries discharge into the environment. Water pollution is caused by oil spills, heavy metals, dyes, and organic compounds released by industry, as well as via unpredictable accidents. In addition, water pollution is also caused by radionuclides released by nuclear disasters or leakage. This review presents an overview of the state-of-the-art synthesis methodologies of 3D porous graphene materials and highlights their synthesis for environmental applications. The various synthetic methods used to prepare these 3D materials are discussed, particularly template-free self-assembly methods, and template-directed methods. Some key results are summarized, where 3D graphene materials have been used for the adsorption of dyes, heavy metals, and radioactive materials from polluted environments.

• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.1
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• pp.57-70
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• 2017

In this study, we investigated the wear measurement methods for slurry pipe applied in the field of mining and oil sand industry and theoretical equations related to the prediction of wear in slurry pipe through literature review. Average daily wear rate and wear rate per excavated distance were determined from slurry discharge pipe thickness measurement data periodically measured at the actual slurry shield TBM site in Singapore. The wear rate of slurry pipe for Bukit Timah Granite was obtained. The wear rates for G (V) grade and mixed zone were 1.5 times higher than that of G (I) to G (IV) grade. Slurry pipe wear rate tends to increase in proportion to the slurry discharge velocity. The optimal slurry pipe replacement or rotation frequency can be estimated through the selection of the pipe wear rate considering geological condition and the reasonable pipe management thickness.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.150-150
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• 2016

Mankind is enjoying a great convenience of their life by the rapid growth of secondary industry since the Industrial Revolution and it is possible due to the invention of huge power such as engine. The automobile which plays the important role of industrial development and human movement is powered by the Engine Module, and especially Diesel engine is widely used because of mechanical durability and energy efficiency. The main work mechanism of the Diesel engine is composed of inhalation of the organic material (coal, oil, etc.), combustion, explosion and exhaust Cycle process then the carbon compound emissions during the last exhaust process are essential which is known as the major causes of air pollution issues in recent years. In particular, COx, called carbon oxide compound which is composed of a very small size of the particles from several ten to hundred nano meter and they exist as a suspension in the atmosphere. These Diesel particles can be accumulated at the respiratory organs and cause many serious diseases. In order to compensate for the weak point of such a Diesel Engine, the DPF(Diesel Particulate Filter) post-cleaning equipment has been used and it mainly consists of ceramic materials(SiC, Cordierite etc) because of the necessity for the engine system durability on the exposure of high temperature, high pressure and chemical harsh environmental. Ceramic Material filter, but it remains a lot of problems yet, such as limitations of collecting very small particles below micro size, high cost due to difficulties of manufacturing process and low fuel consumption efficiency due to back pressure increase by the small pore structure. This study is to test the possibility of new structure by direct infiltration of SiC Whisker on Carbon felt as the next generation filter and this new filter is expected to improve the above various problems of the Ceramic DPF currently in use and reduction of the cost simultaneously. In this experiment, non-catalytic VS CVD (Vapor-Solid Chemical Vaporized Deposition) system was adopted to keep high mechanical properties of SiC and MTS (Methyl-Trichloro-Silane) gas used as source and H2 gas used as dilute gas. From this, the suitable whisker growth for high performance filter was observed depending on each deposition conditions change (input gas ratio, temperature, mass flow rate etc.).

• KOREAN JOURNAL OF CROP SCIENCE
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• v.59 no.4
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• pp.492-497
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• 2014

Soybean (Glycine max L.) is crucial legume crop as source of high quality vegetable protein and oil, and Korea is regarded as a part of center of soybean origin. To expand the information of conserved genetic diversity, we analyzed the genetic variability of soybean collection mainly introduced Korean accessions using 75 microsatellite markers. A total of 1,503 alleles with an average value of 20.0 alleles were detected among 644 accessions. Korean collection revealed average allele number of 13.4 while Chinese, Japanese and Southeast Asian accessions showed 9.0, 5.4 and 6.5 mean alleles, respectively. Especially, Korean accessions showed more number of private allele per locus as 3.4 contrary to other geographical groups. The mean expected heterozygosity and polymorphic information content was 0.654 and 0.616, respectively, and expected heterozygosity values were not significantly distinguished according to the geographical groups. The phylogenetic dendrogram and deduced population structure based on DNA profiles of 75 SSR loci showed Korean accessions formed distinct gene pool against Chinese accessions, and could be divided into five subpopulations. Korean soybean accessions have specific genetic diversity and might be serve the valuable alleles for bio-industry as a part of the center of soybean origin.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.39 no.4
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• pp.26-39
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• 2016

Korea's main manufacturing industries, which have led its economy for the past three decades, are faced with a serious downturn and loss of competitive advantages due to the current economic depression, China's rise, and the drop of oil prices. Korean business firms must adopt the paradigm shift in their value strategies, along with a government-led industrial restructuring in order to gain sustainable competitive advantages. Business firms allocate their limited resources between value creation and value appropriation, however, what effect does strategic emphasis on value creation versus value appropriation have on a business firm's financial performance? This paper empirically addresses this issue by examining the effect of shifts in strategic emphasis on stock return. Furthermore, this study examines appropriate choices of strategic emphasis to gain differential financial performance. The data set used in this regression analysis comes from the KISLINE database of NICE Information Service. The variables that form the basis of this analysis are stock return, ROA, and Strategic Emphasis [(advertising expenditures-R&D expenditures)/assets]. The interactive effect with situational factors regarding the firm and the type of technological environment in which the firm is operating was also analyzed. Our results show that investors acknowledge a shift of strategic emphasis as a sign of stock valuation. In comparison to US, Korean business firms have weak value creation capabilities in high-technology industries, and weak value appropriation capabilities in low-technology industries. This proves Korean firms are fast followers in the global market. Our findings suggest that Korean firms have to adopt a balanced value strategy, nurturing value creation and developing value appropriation for overcoming the current economic downturn and becoming a first mover in the dawn of "Industry 4.0."