• Journal of the Korean Operations Research and Management Science Society
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• v.38 no.2
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• pp.95-115
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• 2013

In traditional inventory models, purchase prices of raw materials are assumed to be fixed and have no effect on the optimal choice of inventory policies. However, when purchase prices fluctuate continuously over time, inventory costs are heavily affected by purchasing prices. Risk-averse inventory model decides order quantity and ordering time by considering not just purchase prices but also the risk from the discrepancy between estimated prices and realized prices. In this paper, we propose a myopic inventory policy which incorporates price risk into deciding ordering time and quantities. While the existing risk-averse model has no mechanism to reallocate inventories already purchased for a specific future period, the revised one reallocates initial inventories of each period to other future periods so that it can avoid purchasing raw materials at high prices. Experimental results demonstrate that the revised model outperforms the existing one in respect of total cost and variability.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.12
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• pp.1150-1156
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• 2007

Multidisciplinary design optimization methodologies play an essential role in modern engineering design which involves many inter-related disciplines. These methodologies usually require very long computing time and design tasks are hard to finish within a specified design cycle time. Parallel processing can be effectively utilized to reduce the computing time. The research on the parallel computing performance of MDO methodologies has been just begun and developing. This study investigates performances of MDF, IDF, SAND and CO among MDO methodologies in view of parallel computing. Finally, the best out of four methodologies is suggested for parallel processing purpose.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.3
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• pp.187-193
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• 2015

When developing a vehicle control system, simulation methods are widely used to validate the whole system in the early development phase. With this regard, the simulator should correctly behave just like the real parts that are not yet implemented while interacting with already implemented parts in real-time. However, most simulators cannot provide functionally and temporally accurate behaviors of the target system. In order to overcome this limitation, this paper proposes a novel real-time simulation technique that can efficiently simulate the temporal behavior as well as the functional behavior of the simulation target system.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.1
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• pp.139-145
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• 1996

The input estimation method estimates maneuvering input acceleration in order to track a maneuvering target. In this paper, the optimal input estimator is derived by choosing the MAP hypothesis among maneuvering input transition hypotheses under the assumption that a maneuvering input acceleration is a semi-Markov process. The optimal input estimation method cannot be realized because the optimal filter should consider every maneuver onset time hypothesis from filter starting time to current time which increase rapidly. Hence the suboptimal filter using a sliding window is proposed. Since the proposed method can consider all hypotheses of input transitions inside the window, it is general enough to include Bogler's input estimation method. Simulation results show, however, that we can obtain a good performance even when the filter considering just one input transition in the window is used. (author). 9 refs., 3 figs., 1 tab.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.20 no.42
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• pp.131-141
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• 1997

The purpose of this study is to certify the actual state of JIT(Just-in-Time) production system's implementation of Korean manufacturing industries and to exhibit the appropriate JIT system considering the company's characteristics, for attain the superior competitiveness. To understand the current situations of JIT system's implementation a questionnaire study is performed. Total 152 valid questionnaires are collected by personal visit and mailing method. All the data is statistically analyzed by SPSS PC+ and SAS program and reviewed to develop a strategy for JIT implementation of Korean manufacturing companies.

• Proceedings of the Korean Information Science Society Conference
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• 2010.11a
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• pp.13-14
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• 2010

• Journal of Korea Technology Innovation Society
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• v.2 no.3
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• pp.145-160
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• 1999

This study analyzed the stock brokers to find how they use the automatic stock trading through internet based on a comparison of U.S.A and Korea. And we reviewed the changing appearance of internet stock trading with one year time lag. The internet stock trading in Korea had been started in 1998 but it was a common trading just after one year.

• Journal of the Korean Data and Information Science Society
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• v.22 no.5
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• pp.961-966
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• 2011

Circular variables are those that have a period in its range. Their examples include direction of animal migration, and time of drug administration, just to mention a few. Statistical analysis of circular variables is quite different from that of linear variable due to its periodic nature. In this paper, the author proposes new circular regression models using geodesic lines on the surface of the sample space of the response and the predictor variables.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.472-474
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• 2005

In WDM/SCM-PON system more than thousand signals must be gathered to monitor for operation. We have implemented IEEE STD 1149.1 JTAG serial interface bus to gather and monitor analog signals. Required area is just $5{\times}5mm^2$. Gathering time per one signal is $1.75{\mu}$ second. Performance to gather is better than that defined in SFF-8472.

• Journal of Chest Surgery
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• v.12 no.3
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• pp.240-246
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• 1979

A 15-year-old boy having a small VSD was readmitted with clinical manifestations of acute endocarditis and aortic regurgitation one month after open heart surgery. In spite of vigorous treatment with broad-spectrum antibiotics, high fever persisted. Pseudomonas aeruginosa was isolated just one time among several blood cultures. Progressive pulmonary infarction due to embolization. Progressive congestive heart failure and D.I.C. caused patient`s death. Aspergillus was found in autopsy specimen.