• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1990년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 26-27 Oct. 1990
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• pp.406-410
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• 1990

This paper presents an approximate analysis of the serial production lines using decomposition technique. A serial production line consists of a series of unreliable machines separated by finite buffers. The serial production line is evaluated by approximation method, the results of which are compared with those examined by the discrete time event simulation, based on this approximation method, a gradient technique is proposed, which improves the efficiency of an operation of production line through the re-allocation of buffers.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2020년도 춘계학술대회
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• pp.16-16
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• 2020

• Journal of Microbiology and Biotechnology
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• 제26권4호
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• pp.739-747
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• 2016

The rational utilization of crop straw as a raw material for natural gas production is of economic significance. In order to increase the efficiency of biogas production from agricultural straw, seasonal restrictions must be overcome. Therefore, the potential for biogas production via anaerobic straw digestion was assessed by exposing fresh, silage, and dry yellow corn straw to cow dung liquid extract as a nitrogen source. The characteristics of anaerobic corn straw digestion were comprehensively evaluated by measuring the pH, gas production, chemical oxygen demand, methane production, and volatile fatty acid content, as well as applying a modified Gompertz model and high-throughput sequencing technology to the resident microbial community. The efficiency of biogas production from fresh straw (433.8 ml/g) was higher than that of production from straw silage and dry yellow straw (46.55 ml/g and 68.75 ml/g, respectively). The cumulative biogas production from fresh straw, silage straw, and dry yellow straw was 365 l^-1 g^-1 VS, 322 l^-1 g^-1 VS, and 304 l^-1 g^-1 VS, respectively, whereas cumulative methane production was 1,426.33%, 1,351.35%, and 1,286.14%, respectively, and potential biogas production was 470.06 ml^-1 g^-1 VS, 461.73 ml^-1 g^-1 VS, and 451.76 ml^-1 g^-1 VS, respectively. Microbial community analysis showed that the corn straw was mainly metabolized by acetate-utilizing methanogens, with Methanosaeta as the dominant archaeal community. These findings provide important guidance to the biogas industry and farmers with respect to rational and efficient utilization of crop straw resources as material for biogas production.

• 한국지구과학회지
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• 제34권7호
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• pp.633-644
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• 2013

풍력 발전단지의 효율성 평가를 위하여 풍력-기상자원지도로부터 이론적 잠재량을 계산하고 행원 발전단지 발전량과 비교하였다. 풍력-기상자원지도는 기상청 국립기상연구소에서 개발된 1 km 해상도 자료를 이용하였다. 풍력-기상자원지도와 AWS(구좌) 풍속의 비교 검증 결과는 풍속이 과대 모의되었으며, 행원 발전단지 풍속의 일 변동성은 해륙풍의 영향으로 오후에 최대가 되는 일 변동 특성을 보였다. 풍력-기상자원지도로부터 산출된 발전량과 행원 발전단지 발전량의 비율은 24.8%이나, 발전량 빈도수 분포 형태는 유사하였다. 발전량 차이의 원인은 터빈의 기계적 오류, 풍력-기상자원지도 풍속의 과대 모의에 기인한 것으로 생각된다. 본 연구는 향후의 발전단지 효율성 증가를 위한 터빈의 재배치에 기여 할 것이다.

• 반도체디스플레이기술학회지
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• 제13권2호
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• pp.29-35
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• 2014

In this study general solar cell production process was complemented, with research on improvement of solar cell efficiency through surface structure and thermal annealing process. Firstly, to form the pyramid structure, the saw damage removal (SDR) processed surface was undergone texturing process with reactive ion etching (RIE). Then, for the formation of smooth pyramid structure to facilitate uniform doping and electrode formation, the surface was etched with HND(HF : HNO3 : D.I. water=5 : 100 : 100) solution. Notably, due to uniform doping the leakage current decreased greatly. Also, for the enhancement and maintenance of minority carrier lifetime, antireflection coating thermal annealing was done. To maintain this increased lifetime, front electrode was formed through Au plating process without high temperature firing process. Through these changes in two processes, the leakage current effect could be decreased and furthermore, the conversion efficiency could be increased. Therefore, compared to the general solar cell with a conversion efficiency of 15.89%, production of high efficiency solar cell with a conversion efficiency of 17.24% was made possible.

• 디지털융복합연구
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• 제19권10호
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• pp.339-348
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• 2021

본 연구의 목적은 2010년부터 2019년까지 우리나라 10개의 서비스산업을 중심으로 자료포락분석 (DEA)을 이용하여 생산효율성을 측정하고 단절토빗회귀모형과 중도절단토빗회귀모형을 이용하여 그 결정요인을 분석하는 것이다. 분석결과, 첫째, 추정된 서비스산업의 효율성은 대체적으로 매우 낮았고 양극화되어 있었으며, '하수·폐기물 처리, 원료재생업'의 경우 기술적 비효율성이 규모의 비효율성에 기인하는 것을 알 수 있었다. 둘째, 결정요인 분석에서는 투자와 연구개발비는 기술효율성에 정(+)의 관계에 있고, 해외직접투자와 접대비는 부(-)의 영향을 주는 것으로 측정되었다. 또한, 규모가 큰 산업일수록 효율성도 높은 것으로 나타났다. 따라서, 우리나라 미래의 산업인 서비스산업의 발전을 위한 정부의 경제정책은 투자와 연구개발활동을 통한 거시정책과 해외직접투자와 인적자본의 융합 등 미시적인 부문이 동시에 고려되는 보다 융합적 정책이 필요하다.

• 대한교통학회지
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• 제24권5호
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• pp.45-56
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• 2006

우리나라 철도산업의 생산특성과 효율성에 관하여 충분히 검토된 양질의 정보가 축적되기 위해서는 다양한 각도에서 다양한 방법으로 검토가 필요하다. 본 논문에서는 거리함수를 이용한 우리나라 철도산업의 생산특성 및 기술효율성 분석결과를 제시한다. Shephard(1953)가 처음 소개한 거리함수는 가격에 관한 정보를 필요로 하지 않는다. 따라서 가격에 관한 자료를 구하기 어렵거나 또는 공공부문의 경우처럼 가격에 대한 통제가 존재하는 상황에서 효과적인 분석수단이 될 수 있다. 또한 다수투입 다수산출 생산기술을 다룰 수 있으며 생산특성과 효율성을 동시에 분석할 수 있는 장점을 갖고 있다. 한국철도의 1963년부터 2004년까지의 연도별 자료로부터 이차계획법모형을 사용하여 거리함수를 추정하였다. 추정된 기술효율성은 1980년 이후 2004년까지 점진적으로 개선되고 있는 것으로 나타났다. 간접 Morishima대체탄력성 추정결과는 노동을 다른 투입으로 대체하는 것이 매우 어렵거나 또는 불가능한 것으로 나타났다. 평균 규모탄력성은 2.7로 나타났으며 이는 규모를 1%증가시켰을 때 산출이 2.7%증가함을 의미한다. 즉 한국철도에 규모의 경제가 존재함을 의미한다.

• 식물조직배양학회지
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• 제26권1호
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• pp.49-52
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• 1999

고추 (Capsicum annuum L.)의 일대잡종을 이용하여 모본의 유전자형 및 생태형이 약배양 효율에 미치는 영향을 조사하였다. 모본의 유전자형에 따라 약배양 효율에 차이를 보였다. 또한 약배양 효율은 모본으로 배 발생률이 낮은 계통보다 높은 계통을 사용한 교배조합에서 높아 약배양 효율에 세포질 효과가 있는 것으로 나타났다. 또한 생태형에 따른 배 발생 효율은 재래종$\times$피망 교배조합에서 배 발생률이 17.8~46.1%로 가장 높았고, 피망$\times$재래종 조합은 5.4~8.5%의 배발생률을 보여 가장 낮았다. 재래종 $\times$남방계, 남방계 $\times$재래종, 남방계 $\times$피망, 피망 $\times$남방계 교배조합의 배 발생률은 10.5～23.1%로 비교적 중간값을 보였다.

• Asian-Australasian Journal of Animal Sciences
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• 제13권5호
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• pp.686-693
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• 2000

Biomass yield, nutritive value and nutrient utilization efficiency of different genera of duckweed (DW, Lemnaceae) under the same nutritional and management conditions were studied. Three genera of DW namely: Lemna perpusilla, Spirodela polyrhiza and Woljfia arrhiza, were cultivated in 18 plastic sinks each of $59{\times}54{\times}35cm^3$ size. Each sink contained approximately 80 L of water and was charged once with 6.648 kg of anaerobically fermented cow dung effluent. The seed rate for Spirodela, Lemna and Wolffia were 600, 400 and $600g/m^2$ respectively. Duckweed were harvested at 48 hours intervals. Media total N concentration for Lemna and Wolffia gradually increased with time. Growth of duckweed was measured by subtracting the inoculum from the total biomass production. Growth of Spirodela ceased within 4 days but Lemna and Wolffia continue to grow up to 34 days. Bio-mass yield was significantly (p<0.05) higher in Wolffia (906 kg/ha/d) than Lemna (631 kg/ha/d). Dry matter (DM) yield was very similar in Lemna (14.80 kg/ha/d) and Wolffia (14.57 kg/ha/d). The N content was non-significant higher in Lemna (5.45%) than Wolffia (5.00%) and Spirodela (4.6%). The crude protein (CP, $N{\times}6.25$) yield was non-significantly higher in Lemna (4.83 kg/ha/d) than Wolffia (4.32 kg/ha/d). The acid detergent fibre (ADF) content was the highest in Wolffia (28.59%), followed by Spirodela (19.47%) and Lemna (12.39%). Utilization efficiency of CP was 273 and 314% respectively for Wolffia and Lemna. However, similar efficiency values for Spirodela was only 1.5%. Considering the bio-mass yield, nutritive value and nutrient utilization efficiency, production performance of DW were in the order of Lemna>Wolffia>Spirodela under the present experimental conditions.

• Animal Bioscience
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• 제34권4호
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• pp.613-620
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• 2021

Objective: This study aimed at studying the potential use of Flemingia (Flemingia macrophylla) as a protein source fodder to improve nutrients digestibility and ruminal fermentation efficiency in beef cattle. Methods: Four, Thai native beef cattle were randomly assigned in a 4×4 Latin square design. Four levels of Flemingia hay meal (FHM) were used to replace soybean meal (SBM) in the concentrate mixtures in four dietary treatments replacing levels at 0%, 30%, 60%, and 100% of SBM. Results: The experimental findings revealed that replacements did not effect on intake of rice straw, concentrate and total dry matter (DM) intake (p>0.05). However, the apparent digestibilities of DM, organic matter, crude protein, acid detergent fiber, and neutral detergent fiber were linearly increased up to 100% replacement levels. Moreover, the production of total volatile fatty acids, and propionate concentration were enhanced (p<0.05) whereas the concentration of acetate was reduced in all replacement groups. Consequently, the CH4 production was significantly lower when increasing levels of FHM for SBM (p<0.05). Furthermore, rumen bacterial population was additionally increased (p<0.05) while protozoal population was clearly decreased (p<0.05) in all replacement groups up to 100%. In addition, microbial nitrogen supply and efficiency of microbial nitrogen synthesis were enhanced (p<0.05), as affected by FHM replacements. Conclusion: The findings under this experiment suggest that 100% FHM replacement in concentrate mixture enhanced rumen fermentation efficiency, nutrients digestibilities, bacterial population, microbial protein synthesis, and subsequently reduced CH4 production in beef cattle fed on rice straw.