• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.05a
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• pp.154-155
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• 2014

Small photovoltaic equipment spreads to the detached house owing to the support of government. This study analyzed the payback period of small photovoltaic equipment, and presented a plan of spreading PV equipment by electricity consumption according to the results. The results of payback period analysis showed that a household of 500kWh or above in the average monthly electricity consumption could produce an economic effect without the subsidies of government, and a household of 300kWh or above could secure economical efficiency in case of receiving the subsidies of government and municipality. However, it was shown that the economic effect was not large in case of a household of less than 250kWh. Therefore, the analysis showed that it would be necessary to be supported by additional subsidies or to develop a new supporting policy with regard to a household of less than 250kWh.

• Journal of the KSME
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• v.22 no.6
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• pp.471-476
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• 1982

1.열펌프 시스템의 성능은 최적설계를 하므로서 이론적, Rankine C.O.P에 접근시킬 수 있다. 2.. 산업체 중저온 폐열회수이용에는 열펌프가 매우 유망하며 냉온수를 동시에 이용하는 경우는 더욱 유리하다. 3. 우리나라 산업계에서 보통 투자회수기간을 3년으로 본다면 전력시설용량을 500kw 이상의 산업용 소동력, 대동력의 경우 열펌프의 성적계수는 약 3.5 정도가 하한으로 볼 수 있다. 4. 공기 또는 물 열원의 가정용 열펌프는 전력비가 비싸므로 아직은 실용성이 없다.

• Resources Recycling
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• v.23 no.3
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• pp.3-12
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• 2014

This study aims at providing an economic assessment for incineration plants which recover heat during its incineration process. In this study, Life Cycle Cost(LCC) of incineration plants is performed based on each regression analysis formula for construction cost, operation cost, and heat generation in order to compare economic feasibility. The result shows that the incineration plant recovering waste heat while processing 80 tons of waste per day increases both initial investment and operation cost but this type of an incineration plant has economical predominance from the recovered waste heat over the one that does not recover heat when being operated for more than eleven years if the retrieved heat replaces the use of LNG. And its payback time reaches more than 19 years in case of selling heat and performing emission trading.

• Journal of Korean Society of Transportation
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• v.34 no.5
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• pp.421-436
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• 2016

Public-Private-Partnerships tend to be committed high project development cost and recover the cost through future revenue during the operation period. In general, long-term concession can bring on more revenue to private investors, but short-term concession less revenue due to the short recovering opportunities. The concession period is usually determined by government in advance or by the private sectors's proposal although it is a very crucial factor for the PPPs. Accurate traffic forecasting should be most important in planing and evaluating the operation period in that the forecasted traffic determines the project revenue with user fees in PPPs. In this regards, governments and the private investors are required to consider the traffic forecast risk when determining concession period. This study proposed a model for the optimal concession period in the PPPs transportation projects. Monte Carlo simulation was performed to find out the optimal concession period while traffic forecast uncertainty is considered as a project risk under the expected return of the private sector. The simulation results showed that the optimal concession periods are 17 years and 21 years at 5.5% and 7% discount level, respectively. This study result can be applied for the private investors and/or any other concerned decision makers for PPPs projects to set up a more resonable concession period.

• Journal of Digital Convergence
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• v.20 no.4
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• pp.215-224
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• 2022

This study tried to examine the effect of cost asymmetry on food service companies and what characteristics affect such cost behavior. This study analyses cost behavior for cost of good sold, selling, general and administrative cost over the 2019-2020 period. Also, the rate of change in activity level was measured using change in sales. This study measures the behavior of cost using the research model of [1]. As a result of the analysis, it was found that food service companies exhibited cost asymmetric behavior as their sales level decreased. In addition, the cost asymmetric behavior has been strengthened since the corona virus, and the shorter the operating cycle. Lastly, the shorter the inventory holding period and the collection period of accounts receivable, which are components of the operating cycle, more strengthen asymmetric behavior of costs. These results seem to be meaningful in examining the cost structure and factors that may affect the structure for food service industry. This has approached the cost aspect of the situation faced by service food companies due to COVID-19, and it can be suggested that this pandemic can lead to cost reduction due to a decrease in corporate sales.

• The Korean Journal of Soil Zoology
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• v.5 no.2
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• pp.97-100
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• 2000

We report here an improved collecting method of the infective juveniles multiplied in the host insect with the entomopathogenic nematodes, Steinernema carpocapsae Weiser. The specific characteristics of this method involved the opening of the host insect hemocoel after the population of their infective juveniles reached at the maximum (6 days at 25$\^{C}$ after nematode treatment to nonimmunized host insects) to facilitate the escape of the multiplied nematodes. It also used 'Baermann funnel'method to select the infective juveniles effectively. This improved 'Baermann funnel'method was compared with a traditional collecting method, which was characterized with a combination of untreated host insects and 'White trap'collecting method, in both yield and pathogenicity of the collected infective juveniles to the fifth instar larvae of beet armyworm, Spodoptera exigua (H bner). More than 95% of the nematode populations collected by the two methods represented the morphological infective juveniles. To prove the nematodes to be infective juveniles functionally, pathogenicity and infective activity were compared in the nematodes collected by the two methods. They were not different in both pathogenicities and infective activities which were measured by the numbers of nematodes penetrated into the hemocoel of the insect hosts after exposure for the specific times to the same dote of infective juveniles. Significant difference between two collecting methods was found in the total yields of the infective juveniles per host insect About 50,000 infective juveniles per infected fifth instar larva of S. exigua after 6 day incubation at 25$\^{C}$ were collected only for 2 days by the improved 'Baermann funnel'method, while about 20,000 infective juveniles per host were collected for 10 days by the classical 'White trap'method.

• KSBB Journal
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• v.20 no.4
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• pp.317-322
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• 2005

Various recovery methods were investigated to maximize hemicellulose recovery from lignocellulosic material hydrolyzed by pure water. The pretreatment conditions of water hydrolysis were $170\~180^{\circ}C$ and 1 hour of reaction time. The percentage of hemicellulose solubilized increased as the temperature increased from 170 to $180^{\circ}C$. However, significant decomposition of sugar was observed at temperature of $180^{\circ}C$. From the results of water hydrolysis, the total amount of glucan in solid residue and liquid hydrolyzate was close to the total glucan in the original biomass. For hemicellulose, however, there was a significant difference between both contents. To prove this difference, various recovery methods were proposed. From the total sugar accountability (sugar in liquid + sugar in solid), it was confirmed that hemicellulose recovery in the hydrolyzate was increased if the product including both hydrolyzate and solid residue was physically stimulated by such as heating and ultrasound irradiation. This indicated that, in commercial scale processes that much bigger substrate sizes are used and a sufficient amount of leaching solvent can not be used after pretreatment, a significant amount of oligomers could be trapped in the solid matrix.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.7
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• pp.903-907
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• 2006

Frozen stability of proteins recovered from white croaker and jack mackerel have been tested by measuring oxidation of residual lipid, browning, total plate count, and texture of gel during storage at $-20^{\circ}C$. The oxidation of residual lipid in recovered protein from Jack mackerel increased up to 60 days, and then decreased. Both browning values significantly was increased after 90 days. Total plate count was $1.2{\times}10^4\;CPU/g$ for proteins recovered from white croaker and $3.2{\times}10^4\;CPU/g$ for proteins recovered from jack mackerel in 60 days. The breaking force, deformation, and whiteness of gel formed from proteins recovered from white croaker did not change up th 120 days significantly, while proteins recovered from jack mackerel did not form heat-induced gel in 120 day. Frozen storage of the recovered protein was limited to 90 days for white croaker and to 60 days for jack mackerel considering the gelling ability and textural properties.

• Journal of the Korean Applied Science and Technology
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• v.38 no.4
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• pp.1010-1019
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• 2021

Petroleum oil in reservoir has been acquired by primary, secondary and tertiary oil recoveries. Microbial enhanced oil recovery (MEOR) classified to tertiary oil recovery has been evaluated in two ways of in-situ and ex-situ options. In-situ MEOR injects microbes into a depleted oil reservoir and stimulates those to generate metabolites. Among metabolites, biosurfactants play an important role to make heavy residues flow. Ex-situ MEOR injects microbial metabolites instead of microbes into a reservoir to recover oil. Even though both in-situ MEOR and ex-situ MEOR are eco-friend processes, in-situ MEOR can be preferred because it is more economic. Even though MEOR have been evaluated for a long time, it is still in the state of evaluating in a pilot-scale. Among microbes, bacteria have been widely evaluated in MEOR purpose. In this paper, bacteria for MEOR were summarized and their metabolites were qualitatively evaluated.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.241-243
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• 2005

효율적인 전력 부하관리기기인 산업분야로의 축냉기기보급은 국가와 전력회사, 그리고 고객 모두에게 편익이 극대화 되어야 한다. 하지만 국가와 전력회사 모두에 편익이 기대된다고 해도 고객의 투자 Merit가 적은 경우 기기보급효과는 얻기 어렵다 전력시장에서 고객이 스스로 본 부하기기를 도입하고, 관련 선비투자를 확대하기 위해서는 초기 설비투자비 대비 적정 투자 비회수 시기, 적정 지원금, 설비신뢰성 및 효율성에 대한 객관적 평가자료 확보 및 정부의 관련정책시행 일관성이 요구된다. 본 논문에서는 산업용 전력을 사용하는 일반 고객이 비축냉 Chiller가 아닌 축냉기기를 도입한 경우의 경제성을 평가할 수 있는 설비투자비 회수기간 평가 알고리즘과 이 프로그램의 실제 적용결과에 대해 기술하였고, 이들 연구결과를 통해 효과적인 부하관리사업을 촉진할 수 있는 기틀을 마련하였다.