• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2006년도 제27회 추계학술대회논문집
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• pp.169-174
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• 2006

본 연구는 재생냉각형 고압 축소형 연소기 설계에 관한 것으로 이 연소기를 제작하기 전에 열유속측정을 위한 물냉각 고압 축소형 연소기를 제작하였다. 물냉각 고압 축소형 연소기의 연소시험결과 높은 연소성능 및 냉각성능이 검증된 설계 조건을 얻었고 이를 바탕으로 재생냉각형 고압 축소형 연소기의 형상을 설계하였다. 설계된 연소기의 형상은 제작이 완료된 후 연소시험을 수행하여 실용성을 검증 할 예정이다.

• 한국태양에너지학회 논문집
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• 제37권2호
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• pp.67-75
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• 2017

We have investigated the operating characteristics of $1,600m^2$ large-scale solar thermal system installed in an eco-friendly energy town in Chungbuk Innovation City. The operation criteria of the collecting pump and storage pump were different from the existing standard, and it was confirmed that each pump works well according to the changed criteria. Based on the data of the representative day, the daily collecting heat (efficiency) and the production (storing) heat (efficiency) were estimated. It was confirmed that the daily collecting heat (efficiency) of the flat plate type was higher than that of the evacuated tube type, but the useful heat production was more in evacuated tube type collector.

• 한국유체기계학회 논문집
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• 제18권2호
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• pp.37-42
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• 2015

In the purpose of this study, we investigate the characteristics of the pilot-scale wastewater treatment system applied to BAF, MBR and IPNR as examining the removal efficiency of organic pollutants and operating factors in small decentralized wastewater treatment systems, and operating factors. For long-term operation period of more than nine months, pilot-scale plant operating results appeared very stable. This results were the removal efficiency of BOD was 80.3% above and removal efficiency of COD with an average of about 91.0%, satisfied the final effluent water quality standards. TN in the final effluents was the average concentration of 7.9 mg/L, was satisfactory water quality standards 10 mg/L of TN.

• 한국방재학회:학술대회논문집
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• 한국방재학회 2007년도 정기총회 및 학술발표대회
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• pp.579-582
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• 2007

In this paper, the inundation simulations were carried out by using GIS tools for the analysis of detention efficiency based on the results of runoff analysis according to location and scale of regional detention facilities. The inundation maps could be drawn by the inundation simulations, and the locations and magnitude of inundation areas could be estimated through the inundation maps. The inundation simulations with GIS tools are approved to be the one of the useful method in designing optimized location and scale of regional detention facilities.

• 통합자연과학논문집
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• 제2권4호
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• pp.237-242
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• 2009

As semitransparent dye-sensitized solar cells (DSSCs) have advanced to large-scale applications from lab-level research, the large-scale performance has attracted much attention. Modules of DSSCs have been investigated to optimize the efficiency as a $TiO_2$ systhesis temperature and a surface treatment of $TiCl_4$ aqueous solution. Essentially, these semitransparent modules have an extended structure with lab-scale works with the exception of the dimensions and methods for the series connection. The $5cm{\times}6.5cm$ modules have shown an efficiency of about 6% without a scattering layer. While the fill factors of modules depend on the width of each $TiO_2$ unit cell, they are much less dependent on the lengths of the unit cells.

• KIEAE Journal
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• 제15권5호
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• pp.75-82
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• 2015

Purpose: The first grade of Korea's Building Energy Efficiency Rating System(BEERS) is required for new government office buildings as a mandatory measure to reduce greenhouse gas emission. However, there is no specific criteria about performance that which level should apply to energy-saving design element for obtaining Building Energy Efficiency Rating 1st grade. Therefore, Certification status should be analyzed firstly, about the office building which is certificated. Certification analysis for office buildings acquired certification therefore should be done first. Method: In this study, Certification status(Office buildings acquired Building Energy Efficiency Rating Certification)was analyzed by classified year, region, specific scale etc. And we analyzed statistically by eliciting an average value of each element influencing to the amount of energy. Result: Energy demands were gradually decreased due to revision of thermal insulation standards for enhanced u-value. Energy consumptions were different from the kind of equipment and yearly trends applied depending on the size of the building. Total primary energy consumptions were influenced by heat source types and the primary energy scale factors.

• 한국물환경학회지
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• 제31권4호
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• pp.418-427
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• 2015

This study was carried out to evaluate the performance of a lab-scale novel septic tank system for improving the conventional septic tank in the developing countries of water shortages. The lab-scale novel septic tank system consists of sepetic tank, aeration tank with HBC-ring, and sand filter. Optimum HRT was reguired about 1.5days to get a total COD removal efficiency of 90%, COD, BOD and SS removal efficiency was about 70%, 60%, and 85% in sepetic tank only. The structure of sepetic tank with two stages results in the high removal efficiency of organic matter. When sepetic tank, aeration tank, and sand filter were more than HRT 1.5days, 18hrs, and 12hrs, respectively, final effluent was less than 20 mg/L of BOD, 14 mg/L of SS, so that there is a high potential of its use for reusing water in flush toilet. There is no significant effect of HRT change on nutrient removal. Total nitrogen removal efficiency was about 40%, final effluent was 30~40 mg/L of TN, total phosphorus removal efficiency was about 11~25%, final effluent was 9~12 mg/L of TP. Because there is very small amounts of organic nitrogen and phosphorus in effluent, it was possible to reuse water for agricultural use.

• Advances in Energy Research
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• 제5권3호
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• pp.207-217
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• 2017

Energy consumption in agriculture is responsible for greenhouse gas emission but it can be reduced after efficient utilization of energy inputs. Therefore, the present study aims for the estimation of energy efficiency and extent of greenhouse gas reduction after benchmarking of inefficient farms in off-season tomato in Punjab province of Pakistan. Primary data were collected from 70 farmers with simple random sampling. By using data envelopment analysis, the average value of technical, pure technical and scale efficiency was 0.80, 0.92 and 0.87, respectively while increasing, constant and decreasing return to scale was observed in 33, 26 and 11 farmers, respectively. Total input energy was reduced by $12,688.91MJ\;ha^{-1}$ (13.89%) if inefficient farms used the energy inputs according to recommendations or benchmarking. A major portion of energy saving comes from fertilizers (68.79%) followed by diesel (15.70%), chemicals (5.91%), machinery (4.37%) and water (4.00%). Total greenhouse gases reduction was $499.17kg\;CO_2\;eq.ha^{-1}$ (14.57%) as a result of improvement in energy efficiency or benchmarking of inefficient farms. Agricultural extension staff should visit the vegetable farms on regular basis and give necessary information about efficient utilization of energy inputs. The government should create awareness about the optimum use of input through seminars and pamphlets.

• 한국산학기술학회논문지
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• 제17권2호
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• pp.265-271
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• 2016

본 연구는 콩 농가들의 경영효율성을 분석하고 이 경영효율성에 미치는 요인을 제시함에 목적이 있다. 분석결과 재배면적이 넓을수록 콩 규모효율성에 정(+)의 효과를 주지만 규모수익체증을 해야 하는 농가가 대부분이었다. 노동력과 관련성이 큰 자가노력비, 임차료, 고용노력비를 합하면 54.6%로 생산비의 절반이상을 차지하고 있으며 점차 증가하는 추세에 있다. 또한 고용노동비율이 높을수록 총효율성, 기술효율성, 규모효율성에 긍정적인 영향을 미치므로 효율적인 노동력 이용과 확보가 중요하다. 친환경농업의 척도인 유기질비료 비율은 총효율성과 배분효율성을 떨어뜨리고 관행농업의 척도인 농약비는 총효율성과 배분효율성을 높이는 것으로 분석되었지만 무기질비료 투입과 농약 저투입을 통한 고품질 농산물 가격을 반영하지 않아 향후 이를 반영한 연구가 필요하다.

• 한국IT서비스학회지
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• 제16권4호
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• pp.15-31
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• 2017

This study analyzes 45 Korea IT service companies from 2012 to 2016 using DEA analysis. Large enterprises, medium enterprises and small and medium enterprises (SMEs). CCR model and BCC model were used for efficiency analysis. Among the various analytical objects, the decision objects which yield the maximum output with minimum input are compared with other analysis objects. The relative inefficiency was measured through this, and Technical Efficiency (TE), Pure Technology Efficiency (PTE), Scale Efficiency (SE), scale profit, reference frequency were analyzed. Also, we analyzed the Technology Gap Ratio (TGR), which is the distance between production function and Meta-Frontier for each firm, using Meta-Frontier analysis. Finally, the Tobit model is used to analyze the sources of efficiency and inefficiency. The inputs are assets, capital, and employees, and the output factor is sales. The analysis shows that large firms are achieving technological achievements more efficiently than small and medium enterprises. As a result, medium-sized enterprises and SMEs can improve efficiency overall through efficient operation of workforce and appropriate combination of inputs such as assets and capital. Also, as a result of the influence factor analysis, it was found that the ratio of the managed asset ratio and the management cost ratio were significant factors influencing the efficiency of the IT service companies. This study suggests the efficiency analysis using DEA for many Korea IT service companies. Inefficient parts of each company are classified according to size and technology. Also, we identify the most efficient companies and analyze the causes of those companies whose profits are lower than their size.