• Korean Journal of Plant Resources
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• v.12 no.3
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• pp.204-208
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• 1999

We carried out this study to confirm the possibility of C. wilfordii cultivation using crop as a substitute for stake or net, and tested sit support crops, i.e., soybean, peanut, Perilla frutescens var. acuta Kudo, Job's tears, sorghum, and corn compared with net support. Effects of support crops on growth and root yield of C. wilfordii were as follows. Attracting efficiency of vine showed 94∼100% among crops. The number of branches per plant was 1 or 2 more in p. frutescens var. acuta Kudo, Job's tears, and sorghum support than in net support. Fresh root yield per 10a was 919kg in net support, while it was 717kg in P. frutescens var. acute Kudo, 656kg in Job' tears, and 652kg in sorghum support. However, the problem of decreased yield in these support crops could be overcome by cost saving of staking installation and by harvesting support crops. Therefore, C. wilfordii cultivation using P. frutescens var. acute Kudo, Job's tears, and sorghum as support crops showed most effective in labor and cost saving.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1993.10a
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• pp.129-138
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• 1993

The shortage of agricultural labour due to industrial growth has greatly induced the mechanization in Korean agriculture. However small and scattered land holdings have been the main constraints in the process of mechanization. This paper describes the interrelationships of farm land structure, machinery selection and machinery operation areas. The sandy silt loam irrigated paddy land having single crop a year was selected as a target areas for this study. Machine operation cost is greatly influenced by operation period, plot geometry and operation area. On the improved geometry plots, optimal machine size increases slowly with increase in operation area. Operable area increases due to increased effective machine capacity on better geometry plot. The difference between the effects of operation period and plot geometry is that in the former case, the cost reduction is caused by delay in increase of machine size, whereas in the latter case timeliness cost is reduced by increase ffective capacity. The effect of farmland consolidation is greater on small plots than that on big plots. Increasing wage rates have induced the adoption of more labor saving machinery. Bigger labor saving machines require enlargement of operation area and larger plots through improvement in farm land structure. Machine cost on poor plot geometry increases more rapidly than that on the good plot geometry and as operation area increases machine cost reduces significantly. It is concluded that the development of agricultural mechanization ion Korea will depend on the improvement in farm land structure and enlargement of operation area.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.49 no.3
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• pp.291-300
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• 2013

The main purpose of this study is to analyse economic feasibility of low-carbon-oriented gear for anchovy boat seine. The results of benefit/cost analysis showed that use of the low-carbon fishing gear is economically feasible. Considering the fuel saving and relatively low $CO_2$ emission by reducing the resistance of gear, net present value by such type 1 gear improvement was estimated about -2,490 ~ -1,580 million won with the benefit-cost ratio 0.81~ 0.88. And net present value by such type 2 gear improvement was estimated about 6,540 ~ 7,780 million won with the benefit-cost ratio 1.79 ~ 1.94. Development of lowcarbon trawl gear would render significant contributions to reducing $CO_2$ emission in fishing operations and lead to reduce fishing costs due to fuel savings.

• Journal of Biosystems Engineering
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• v.31 no.5 s.118
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• pp.430-435
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• 2006

Greenhouse horticulture in South Korea covered about 52,000 ha in 2005. Greenhouse area of about 12,000 ha has been heated during winter season with heating cost of $20{\sim}40%$ of total Production cost. Farmers engaged in greenhouse horticulture were changed into aged people. Therefore the laborsaving of working process and the saving of greenhouse heating cost should be accomplished simultaneously to increase income of greenhouse horticulture. The best method for saving of greenhouse heating cost is to install thermal tunnels into greenhouse. Then hot air heaters using fossil fuel should be changed into hot water heaters. In other words air heating using forced convection should be changed into natural convection system. In this research coil tube made of flexible PE pipe was designed as hot water heat exchanger and its heat exchanging characteristics were analyzed. This new heat exchanger has been adopted as a natural convection system for hot water heating of greenhouse horticulture.

• Journal of the Korean Dietetic Association
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• v.15 no.3
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• pp.262-277
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• 2009

Fresh-cut foods have been widely used in the school foodservice industry due to their convenience and saving effects of labor and working hours. This study evaluated the effectiveness of using fresh-cut foods in school foodservice with respect to cost efficiency, customer satisfaction, employee satisfaction, and productivity. First, in terms of cost efficiency, the cost of the fresh-cut food per meal price significantly increased by 2.6% via the new production plan. Meanwhile, the costs of labor and food wastes significantly decreased by 3.0% and 0.3%, respectively, after implementing the new plan. Second, customer satisfaction towards foodservice significantly increased, from 2.94 points prior to the new plan to 3.45 points. Third, foodservice productivity such as of the number of meals per full-time equivalent employee increased by 5.7 meals, from 143.0 meals to 148.7 meals after intervention. The productivity index of work hours for producing a meal also increased and was reflected by a work time reduction of 0.77 minutes, specifically from 4.25 minutes to 3.48 minutes. The labor cost per meal also decreased by 29.9 won, from 331.91 won to 301.97 won, but there was no significant difference. Through these results, we identified that using pre-process foods in school foodservice has positive effects on labor saving, customer satisfaction, and employee work satisfaction.

• Magazine of the Korea Concrete Institute
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• v.28 no.2
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• pp.10-13
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• 2016

• Journal of the Korean Society for Heat Treatment
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• v.2 no.3
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• pp.46-54
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• 1989

• Geotechnical Engineering
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• v.24 no.10
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• pp.9-22
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• 2008

• The Transactions of the Korean Institute of Electrical Engineers
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• v.36 no.12
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• pp.839-847
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• 1987

The probabilistic production cost is calculated by the Expected Incremental Generation Cost Curve(EIGC) method based on the multi-state and multi-block operating conditions. For this, A new algorithm for determining production cost by the EIGC and the generation availability curve (GAC) had been developed in order to realize better economic olad dispatch and better reliability for power system operation. The simpler method for determining the EIGC and the GAC is proposed for convenience and saving in computation time.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.418-421
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• 2008

Because of steep rise of international energy cost in recent years high efficiency has been emphasized in energy policy. As far as injection molding machine is concerned, hybrid method using hydraulic and electric systems became the key to this energy saving. the energy saving and molding reproducibility of hybrid injection molding process were shown experimentally, power consumption of hybrid machine is 38% as compared with that of hydraulic machine. Furthermore, the molding reproducibility showed between two methods.