• 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 Biosystems Engineering
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• v.19 no.4
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• pp.329-342
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• 1994

In order to reduce the production cost and improve the quality of dairy feed, several dairy feed mill models suitable for Korean farm size were developed. 6 TMR models were developed for the 1000, 600, 200 head of dairy cattle, and evaluated for capital investments and production costs to suggest the best model. Followings are summary of this study : 1. TMR terminal models were designed that dairy production capacity of TMR1000 models are 40 ton/day, TMR600 model is 20 ton/day and TMR200 models are 10 ton/day. Also, they can be extended their capacity up to twice. 2. Capital investment of TMR terminal models is 145 million won for TMR200-1,205 million won for TMR600 and 609 million won for TMR1000-3 model. 3. The bigger TMR terminal model has the more advantage in production cost. The best model for 1000 head of dairy cattle farm was TMR1000-3 with 10,849 won/ton of production cost, TMR600 for 600 head of dairy cattle farm with 13,829 won/ton, TMR200-1 for 200 head of dairy cattle farm with 16,943 won/ton of production cost, so feed production cost for the 200 head farm was 50% higher than 1,000 head size farm.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.2
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• pp.97-105
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• 2008

This paper presents simulated and experimental test results of optimal control algorithm for an encapsulated ice thermal storage system with full capacity chiller operation. The algorithm finds an optimal combination of a chiller and/or a storage tank operation for the minimum total operation cost through a cycle of charging and discharging. Dynamic programming is used to find the optimal control schedule. The conventional control strategy of chiller-priority is the baseline case for comparing with the optimal control strategy through simulation and experimental test. Simulation shows that operating cost for the optimal control with chiller on-off operation is not so different from that with chiller part load capacity control. As a result from the experimental test, the optimal control operation according to the simulated operation schedule showed about 14 % of cost saving compared with the chiller-priority control.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.28 no.2
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• pp.47-52
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• 2020

Air transport demand is on a sharp rise due to growth in the aviation market. To prepare for this rapidly growing demand for aviation, airport operators are interested in the processing airport capacity. Airport throughput is determined to be the smallest of the facility capacities that make up the airport, but it is customary to determine the cost and time consuming runway capacity as airport capacity. Previous studies have shown that while recent studies have been conducted on airport capacity, there is little research on the criteria for determining capacity. In this study, we would like to determine the extent to which airport capacity is affected by the airport's operating hours and the resulting delays.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.10a
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• pp.381-388
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• 1999

The existing methods for installation of long steel pipe pile have some uneconomical problems such as increase of installation cost and period due to the welding of two piles and removal of soil plug, and decrease of driving efficiency due to the increase of driving resistance by time effect during the welding of piles and removal of soil plug, etc. Thus, in this study, new installation method for long steel pipe pile is suggested to work out the existing problems, and calibration chamber tests are peformed to investigate both driving and economical efficiency for the suggested method. The test results showed that the new installation method has increase bearing capacity as well as reduce installation cost and period for long steel pipe piles as compared with existing methods.

• Journal of Korean Society for Quality Management
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• v.36 no.2
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• pp.20-27
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• 2008

Tolerance design has been identified as an important research area and a number of models have been proposed in the literature. This paper investigates the effect of limited capacity on tolerance design for products with nominal-the-best type (N-type) quality characteristics. The model is developed under the assumption that the reprocessed and nonreprocessed items are produced by the same manufacturing process and therefore their quality characteristics are identically and independently distributed. Profit models are constructed which involve four price/cost components; selling price, cost incurred by imperfect quality, reprocessing and quality inspection costs. Methods of finding the optimal tolerance limits are presented, and a numerical example is given. Sensitivity analyses are also performed to study the effect of a process standard deviation on this model.

• Proceedings of the KIEE Conference
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• 2007.11b
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• pp.255-257
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• 2007

Korea electricity market consists of two payment systems, capacity and energy. Capacity payments are given to the generators according to its hourly availability considering hourly and seasonal weighting factors. Energy payments are settled at the marginal generation cost based on generator variable cost. In 2007, base load energy market is closed and single capacity payment system is begun to apply in electricity market. In this revised market rule, energy price cap for base load generators is newly introduced. We analyze impact of market rule revision in 2007 on base load generators and suggest improvement scheme to enforce market system in this study.

• Journal of Korean Institute of Industrial Engineers
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• v.27 no.4
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• pp.328-336
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• 2001

In this paper, an approach is presented for determining the required storage capacity of a warehouse with leased public space. Storage assignment policies considered are randomized and class-based storage assignment policies. An analytic model for each of the storage policies is formulated with the objective of minimizing the cost of owned storage space and leased space while satisfying a desired service level of protection against space shortages. Cost functions used in the models are piecewise liear with fixed costs. For the models, algorithms are developed to generate optimal solutions. The approach is applied to the systems where the standard economic-order-quantity inventory model is used for all items being stored in the warehouse.

• Journal of Korean Society for Quality Management
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• v.36 no.4
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• pp.77-86
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• 2008

Due to the rapid growth in automated testing and manufacturing systems, screening inspection becomes very attractive. In this paper, we investigate the effects of limited capacity on screening inspection using a surrogate variable. The model is developed under the assumption that the reprocessed and nonreprocessed items are produced by the same manufacturing process and therefore their quality characteristics are independently and identically distributed. Profit models are constructed which involve four price/cost components; selling price, cost incurred by imperfect quality, reprocessing and quality inspection costs. Methods of finding the optimal screening limits are presented, and a numerical example is given. Sensitivity analyses are also performed to study the effect of a process standard deviation on this model.

• Proceedings of the KIEE Conference
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• 1988.11a
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• pp.102-106
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• 1988

Generally, average invest cost is widely used for expansion planning of generation in power system. But, other cost which is followed by adding generating capacity in electric system is increased in accordance with increasing plant reasons. In this study, we represent the invest cost with quadratic function and analyze its effect on the expansion planning. It is hoped that this method is used in expansion planning of generating system.