• 제어로봇시스템학회:학술대회논문집
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• 1990.10a
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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.

• Proceedings of the Korean Society of Crop Science Conference
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• 2020.06a
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• pp.16-16
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• 2020

• Journal of Microbiology and Biotechnology
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• v.26 no.4
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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.

• Journal of the Korean earth science society
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• v.34 no.7
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• pp.633-644
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• 2013

This study evaluates wind farm efficiency at Haengwon in Jeju Island. The actual energy production at Haengwon wind farm is compared with the estimated energy production based on Korean wind map which is developed at the National Institute of Meteorological Research/KMA. The validation of wind map at Gujwa located near the Haengwon wind farm shows that the wind speed is overestimated. The diurnal variation of wind speed shows a maximum value in the afternoon due to the effect of sea-land breeze. The ratio of the actual energy production at Haengwon wind farm and the estimated energy production based on the Korean wind map is 24.8%, while the distribution of energy frequency is similar each other. The difference of energy production is caused by mechanical error of the turbine and the overestimation of the simulated wind map. This study will contribute to the repowering of turbines for improving the efficiency of wind farm in the future.

• Journal of the Semiconductor & Display Technology
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• v.13 no.2
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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.

• Journal of Digital Convergence
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• v.19 no.10
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• pp.339-348
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• 2021

This paper aims to analyze the production efficiency in Korea's ten service sectors using DEA and its determinants utilizing a truncated-Tobit regression model and a censored-Tobit regression model in 2010-2019. This paper found: First, the Korean service sector's production efficiency in general has been significantly low and polarized. Especially, the inefficiency resulted from the scale inefficiency in the 'sewerage waste management industry.' Second, in the determinants analysis, the results show the positive effect of the investment and R&D expenses on technical efficiency, while FDI and lobbying expenses illustrate the negative impact. Moreover, it seems that the larger the industry, the higher the efficiency. Thus, the future Korean government's economic policy for the service sectors requires a mixed and integrated policy of the macroeconomic aspect such as active investment and R&D activities with microeconomic aspect including a convergence of FDI and human capital.

• Journal of Korean Society of Transportation
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• v.24 no.5 s.91
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• pp.45-56
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• 2006

In order to construct an information pool on the production characteristics and efficiency of Korean railroad industry, various alternative approaches have to be applied. In this paper we present an empirical application of the distance function to measure the technical efficiency and the production characteristics of Korean railroad industry, The distance function firstly introduced by Shephard (1953) provides the advantage that it does not need information about prices, so it can accommodate the multiple output nature of the railway only using the quantifies as data. This is of great relevance in the context of the public sector such as railroad industry where there are often distinct control mechanisms on input prices. Also the distance function allows us to obtain a measure of technical efficiency as well as a measure of production characteristics. From annual data on Korean railroad industry during 1964-2004, multiple output distance function is estimated using quadratic programming model. The resulting technical efficiency estimates has tended to be improved over the period $1980{\sim}2004$. The indirect Morishima elasticities of substitution indicate that the substitutabilities for labor are relatively very low or impossible. The average scale elasticity is 2.7 which means that increasing the scale by 1per cent will result in an output increase by 2.7 percent. This result indicates that economies of scale are present in the Korean railroad industry.

• Korean Journal of Plant Tissue Culture
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• v.26 no.1
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• pp.49-52
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• 1999

The influence of genotype and ecotype on the anther culture efficiency using hybrid of hot pepper (Capsicum annuum L.) was investigated. Anther culture efficiency was differently dependent on the genotype of parents. In the efficiency of embryo production, the cross combination using female parents with high embryo inducing ability was higher than those with low embryo inducing ability. It was shown that genotype and cytoplasm has effect on embryo production. Also the embryogenic ability was different according to ecotype of cross lines. The frequency of embryo production were the highest in Local variety $\times$ pimento cross combinations with 17.8~46.1 and the lowest in Pimento $\times$ Local variety cross combinations with 5.4~8.5%. Embryo inducing frequency was the middle value with 10.25~23.1% in Local variety $\times$ Tropical variety, Tropical variety $\times$ Local variety, Tropical variety $\times$ Pimento, and Pimento $\times$ Tropical variety cross combinations.

• Asian-Australasian Journal of Animal Sciences
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• v.13 no.5
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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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• v.34 no.4
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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.