• Proceedings of the Korean Operations and Management Science Society Conference
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• 2000.04a
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• pp.253-256
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• 2000

In general, Automated Storage/Retrieval Systems (AS/RS ) have racks of equal sized cells to utilize the concept of unit-load. Most of the techniques for the performance estimation of a unit-load AS/RS are a static model or computer simulation. Especially, their models were developed under assumption that the Storage/Retrieval (S/R) machine performs only single command (SC) or dual command (DC). In reality, defending on the operating policy and the status of the system at a particular time, the S/B machine performs a SC or a DC, or becomes .: idle. In order to resolve these weak points, we propose a stochastic model for the performance estimation of unit-load AS/RS by using a single-server queueing model. Expected numbers of waiting storage and retrieval commands are found

• Journal of Energy Engineering
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• v.22 no.2
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• pp.205-210
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• 2013

Cycle-to-cycle variation has long been recognized as limiting the range of operating conditions of spark ignition engines, in particular, under lean and highly diluted operation conditions. At a part load, some of the cycles tend to knock, while others may have incomplete combustion by the time the exhaust valve opens. An experimental study has been performed in order to evaluate the relative contribution of several relevant parameters on the cyclic variability in spark ignition engines. In general, the stability of engine operation is improved with fuel injector according to the optimal injection timing, but the stability of engine operation at idle is not improved compared with a practical gasoline engine. In this study, we investigated the relationship of the effect of operating conditions for the stability at low speed and load.

• Journal of Satellite, Information and Communications
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• v.8 no.3
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• pp.6-9
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• 2013

Cognitive Radio is an intelligent interference avoidance idle spectrum communication system for your environment and actively determine the frequency bandwidth recycling by sharing the spectrum in a way that maximizes the efficiency of radio resource technology. At this time, this does not cause interference to the PU spectrum sensing technology is important. If you can choose, depending on the state of the channel spectrum sensing algorithm will be more efficient sensing. Matched filter detection system model that reflects the individual sensing through a fuzzy controller in this paper, energy detection and self-correlation detection are proposed and analyzed.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.26 no.2
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• pp.68-74
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• 2003

Modem automated manufacturing processes employ automated guided vehicles(AGVs) for material handling, which serve several machining centers(MCs) in a factory. Optimal scheduling of AGVs can significantly help to increase the efficiency of the manufacturing process by minimizing the idle time of MCs waiting for the raw materials. In this paper, we will analyse the requirements for an optimal schedule and then provide a mathematical framework for an efficient schedule of material delivery by an AGV. With this model, the optimal number of MCs to be utilized will also be determined. Finally, the material delivery schedule employing multiple journeys to the MCs by the AGV will be carried out. Through rigorous analysis and simulation experiments, we shall show that such a delivery strategy will optimize the overall performance.

• Korean Journal of Agricultural Science
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• v.25 no.1
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• pp.138-147
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• 1998

U-turn migration is one of the prominent phenomenon after IMF controlled Korean economy. However a number of U-turn migrants were settled in rural area before that time. This paper is aims at studying the socio-economic effects of U-turn migration in rural area. The study results are summarized as follows; First, migrants are relatively young and engaged in overall parts of the farming. The farmer with age under 50 is represented at 71.4% of migrants comparing with 53.7% of those farmers in rural area. Second, owing to the increasing number of U-turn migrants, the decreasing price of rural wages, the decreasing of idle land, and the increasing price of farm land are the outstanding phenomenon at present. Third, even though there are many kinds of supporting systems for U-turn migrants, the systems are not so successfully functioned. For the successful supporting system they must be changed for the individual migrant rather than target group.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.9
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• pp.76-84
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• 1994

This paper presents a new high-performance VLSI architecture and VLSI implementation for full-search block matching algorithm. The proposed VLSI architecture has the feature of two directional parallel and pipeline processing, thereby reducing the PE idle time at which the direction of block matching operation within the search area is changed. Therfore, the proposed architecture is faster than the existing architectures under the same clock frequency. Based on HSPICE circuit simulation, it is verified that the implemented procesing element is operated successfully within 13 ns for 75 MHz operation.

• International Journal of Railway
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• v.5 no.1
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• pp.22-28
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• 2012

This report is devoted to the problems of Mongolian Railway Transportation Safety such as high length of wagon service life, defects due to the more factors of exploitation, idle time, increase of faults, poor condition of repairing shops and more hand and mechanical operations and these conditions are quite difficult to meet the safety and reliability of increasing transportation from day to day. The paper discusses that the most optimum solution is diagnosing before occurring wear, breakdown, and defects on the basis of studying characteristics of structural material breakdown, residual methods of voltage, effects of material hardness and linear defects of a crystal net and the reform of machines is very important to implement it. It focuses the structures, characteristics of the material transportation and tests and analyses of the wagon cart which has to meet the traffic safety of wagons and slow and soft movement. The study is done on the wagon chassis which has to meet the traffic safety of luggage wagons.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2000.10a
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• pp.210-215
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• 2000

Presently, one or several tugboats guide a ship in the port or canal, during the ship's engines and steering mechanism kept idle. This method has insufficient ability keeping the ship on course, danger of collision with waterside structures, tugging preparation time consuming, as well as the need expending substantial resources to acquire and maintain tugboats and associated facilities. Therefore, a new technology and system for ship's guiding to be needed and introduced instead of traditional guiding and tugging system.

• Journal of Korea Multimedia Society
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• v.23 no.2
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• pp.227-240
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• 2020

This paper proposes a novel CTC technology, CB-sense. The CB-sense guarantees a dedicated period for the CTC that results in low duty cycle of the receiver device. In addition, it send a lot of information explosively during the dedicated CTC period. Thus, it can achieve high throughput. The CB-sense uses Clear to Send (CTS) packets to transmit information bits to the heterogeneous wireless technologies. The CTS packets block the neighboring node transmissions, so it reduces co-channel interference. In experiment results, CB-sense represents 20 times more throughput than FreeBee and below 5% symbol error rate in the interference environment.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.196-201
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• 2003

Axial fans are widely used for automotive engine cooling device due to their ability to produce high flow rate to keep engine cool. At the same time, the noise generated by these fans causes one of the most serious problems. Especially, engine cooling fan noise in idle condition of a car is noticeable. Therefore, the high efficient and low-noise fan is seriously needed. When a new fan system is designed, system resistance and non-uniform inflow are the key factors to get the high performance and low noise fan system. In this study, experimental study on the fan and system was carried out and brought a successful result of performance and noise from a designed fan. And through the modification of the fan system, the fan produced more flow rate and became less noisy.