• Proceedings of the KIEE Conference
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• 1990.11a
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• pp.371-374
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• 1990

This paper presents the speed control of dc motor based on deadbeat response. The deadbeat response is that the output reaches the final value in the minimum possible settling time and stays there. This results demonstrate that the output reaches final value in one sampling time for the unsaturated region, and in one sampling time after getting free from the saturation state for the saturated region.

• Communications of the Korean Mathematical Society
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• v.18 no.3
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• pp.515-519
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• 2003

Let M be a hyperkahler manifold with the hyperkahler structure (g, I, J, K). In [5], D. Huybrechts suggests that it is an open and interesting question whether any Kahler class that stays Kahler in the twister family can actually be represented by an harmonic Kahler form. In this paper we will consider both this problem and the set of all the primitive harmonic Kahler forms on M.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.1031-1038
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• 2002

In this paper the erection method of the Seohae Bridge starter is presented. The erection method of starter for cable stayed bridge was changed from conventional bracket supported erection to heavy lifting supported directly by stays. There was the need to reduce the erection time drastically. The cost saving was obtained as a bonus.

• Journal of applied mathematics & informatics
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• v.28 no.1_2
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• pp.531-537
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• 2010

In this paper, some vacation policies are considered, which can be related to the past behavior of the system. The server, after serving all customers, stays idle or to wait for some time before a vacation is taken. General formulas for the waiting time and the amount of work in the system are derived for a vacation policy. Using the analysis on the vacation system, we derived the waiting time in the sequential bottleneck station.

• Journal of applied mathematics & informatics
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• v.5 no.1
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• pp.1-12
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• 1998

We consider G/M/1 queues with multiple vacation disci-pline where at the end of every busy period the server stays idle in the system for a period of time called changeover time and then follows a vacation if there is no arrival during the changeover time. The vaca-tion time has a hyperexponential distribution. By using the methods of the shift operator and supplementary variable we explicitly obtain the queue length probabilities at arrival time points and arbitrary time points simultaneously.

• 한국전산유체공학회:학술대회논문집
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• 2006.05a
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• pp.263-267
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• 2006

The path of a flapping airfoil during upstroke and down-stroke is optimized for maximum thrust and propulsive efficiency. The periodic flapping motion in combined pitch and plunge is described using Non-Uniform B-Splines(NURBS). A gradient based algorithm is employed for optimization of the NURBS parameters. Unsteady, low speed laminar flows are computed using a Navier-Stokes solver in a parallel computing environment based on domain decomposition. It is shown that the thrust generation is significantly improved in comparison to the sinusoidal flapping motion. For a high thrust generation, the airfoil stays at a high effective angle of attack for short durations.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.14 no.24
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• pp.43-52
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• 1991

The short-term production planning of an automated manufacturing system is to determine the production rate of each part type or family of part types. The purpose of this paper is to develop an optimal algorithm for solving the short-term production planning problem while machine failures, repairs. and changes in demand requirements are anticipated. The problem is formulated by LP and it shows that the production surplus is approached or stays at the hedging point. In addition, the long-term average frequencies of set-us with relation to a multilevel hierarchical production planing scheme are considered An example to show the effectiveness of the algorithm is presented.

• Proceedings of the Korea Information Processing Society Conference
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• 2004.05a
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• pp.1453-1456
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• 2004

PARO, a power-aware routing optimization mechanism, is proposed in [1] to minimize the transmission power needed to forward packets between wireless devices in ad hoc network. The mechanism works by redirecting the route to pass through one or more intermediate nodes on behalf on source-destination pairs, then reducing the end-to-end transmission power. This paper will show an extension of this model and provide an analysis of the geometrical area lying between source and destination in which the intermediate node elects to perform redirection. The duration the intermediate node stays in that area is also computed.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2020.11a
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• pp.75-77
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• 2020

There was an outbreak of COVID-19 on the Diamond Princess cruise ship. Distinguishing close contacts is the important problem to be addressed. Close contacts mean people who stays with the patients of disease like COVID-19 over a period of time. The passenger position on board can be obtained by indoor positioning technology. The feature of close contacts is similar location with COVID-19 patients. Therefore, this paper proposed the idea of distinguishing close contacts on board based on DBSCAN algorithm.

• Journal of Preventive Medicine and Public Health
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• v.26 no.4 s.44
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• pp.650-660
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• 1993

This study aims to describe the causes of medically unnecessary hospital stay at a teaching tertiary hospital, using modified version of Delay Tool in which the causes of delay are divided into slx major categories : delay related to test scheduling, test results, surgery, medical staff, patient/family, and administration. For the analysis of hospital stay, 6,479 inpatient-days were reviewed in two medical and four surgical departments for one month. Initially inappropriate hospital stays were identified using Appropriateness Evaluation Protocol (AEP), and causes of delay listed in Delay Tool were assigned to each of them. In both medical and surgical services, the most important cause of delay was related to medical staffs, ranging from 3.6% to 51.6% of total inpatient days. Next important category was delay related to test scheduling in medical services ($4.7{\sim}9.2%$), and delay related to surgery in surgical services ($7.3{\sim}15.0%$). Among subcategories of delay related to medical staffs, delay due to conservative care was the most important cause of inappropriate hospital stay ($2.9{\sim}6.4%$). Each clinical departments had different distribution among delay categories, which could not be fully justified by their clinical charateristics. The Delay Tool would be helpful in exploring factors related to the inefficient use of hospital beds. As a measurement tool of inappropriate hospital stay, however, the Delay Tool should be refined in the definitions of categories and its contents.