• Journal of Korean Society of Industrial and Systems Engineering
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• v.43 no.4
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• pp.150-160
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• 2020

In this paper, we introduce a pilot's scheduling model which is able to maintain and balance their capabilities for each relevant skill level in military helicopter squadron. Flight scheduler has to consider many factors related pilot's flight information and spends a lot of times and efforts for flight planning without scientific process depending on his/her own capability and experience. This model reflected overall characteristics that include pilot's progression by basis monthly and cumulative flight hours, operational recent flight data and quickly find out a pinpoint areas of concern with respect to their mission subjects etc. There also include essential several constraints, such as personnel qualifications, and Army helicopter training policy's constraints such as regulations and guidelines. We presented binary Integer Programming (IP) mathematical formulation for optimization and demonstrated its effectiveness by comparisons of real schedule versus model's solution to several cases experimental scenarios and greedy random simulation model. The model made the schedule in less than 30 minutes, including the data preprocessing process, and the results of the allocation were more equal than the actual one. This makes it possible to reduce the workload of the scheduler and effectively manages the pilot's skills. We expect to set up and improve better flight planning and combat readiness in Korea Army aviation.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.5
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• pp.363-372
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• 2002

In ship operation, the roll motions can seriously degrade the performance of mechanical and personnel effectiveness. So many studies for the roll stabilization system design have been performed and good results have been achieved. In many studies, the stabilizing fins are used. Recently rudders, which have been extensively modified, have been used exclusively to stabilize the roll. But, in the roll stabilization control system, the control performance is very sensitive to the ship speed. So, we can see that it is important to consider the ship speed in the rudder roll control system design. The gain-scheduling control technique is very useful in the control problem incorporating time varying parameters which can be measured in real time. Based on this fact, in this paper we examine the;$H_{\infty}$-Gain Scheduling control design technique. Therefore, we assume that a parameter, the ship speed which can be estimated in real time, is varying and apply the gain-scheduling control technique to design the course keeping and anti-rolling control system far a ship. In this control system, the controller dynamics is adjusted in real-time according to time-varying plant parameters. The simulation result shows that the proposed control strategy is shown to be useful for cases when the ship speed is varying and robust to disturbances like wind and wave.

• Journal of the Korea Institute of Military Science and Technology
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• v.17 no.4
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• pp.501-509
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• 2014

In NCW(Network Centric Warfare) environment, mobile nodes communicate through wireless link. But wireless link provides limited networking performance due to signal interferences or mobility of nodes. So it is quite challenge to acquire enough networking resources and use the resources efficiently. In this paper, we have proposed a P2P based tactical information sharing system which provides satisfactory visual information playout for mobile nodes(i.e., military personnel, vehicle,..) in NCW environment. Our proposed system consists of two components. One is caching-enabled switch which stores tactical information segments at its internal storage and then transports them to mobile nodes when require. Another is centralized scheduling algorithm which exploits networking resources more efficiently. To validate performance of proposed system, we performed series of experiments in wireless network testbed. Results show improved performance in terms of segment-missing ratio, networking resources usage, sharing time, and number of simultaneous playout mobile nodes with acceptable playout continuity(i.e., over 95%).

• Korean Journal of Construction Engineering and Management
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• v.23 no.6
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• pp.3-14
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• 2022

Quantitative analysis of the number of construction workers and construction period can present a new standard for appropriate personnel. This study presents a Queueing model that predicts the execution time of work procedures, the most important factor among work efficiency indicators. During the working cycle of apartment frame construction the same process tends to be repeated the volume of contruction. Based on these characteristics, this study used a Queueing Model and analyzed reference layer cycle of the delayed frame construction. After adjusting the number of people and the construction period, the performance of the model was analyzed and suggested. This study aims to support the decision making of personnel distribution according to the volume of construction by performing a performance analysis of the Queueing Model.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.43 no.4
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• pp.116-122
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• 2020

Human and material resource planning is one representative example of Operations Research. Resource planning is important not only in civilian settings but also in military ones. In the Air Force, flight scheduling is one of the primary issues that must be addressed by the personnel who are connected to flight missions. However, although the topic is of great importance, relatively few studies have attempted to resolve the problem on a scientific basis. Each flight squadron has its own scheduling officers who manually draw up the flight schedules each day. While mistakes may not occur while drafting schedules, officers may experience difficulties in systematically adjusting to them. To increase efficiency in this context, this study proposes a mathematical model based on a binary variable. This model automatically drafts flight schedules considering pilot's mission efficiency. Furthermore, it also recommends that schedules be drawn up monthly and updated weekly, rather than being drafted from scratch each day. This will enable easier control when taking the various relevant factors into account. The model incorporates several parameters, such as matching of the main pilots and co-pilots, turn around time, availability of pilots and aircraft, monthly requirements of each flight mission, and maximum/minimum number of sorties that would be flown per week. The optimal solution to this model demonstrated an average improvement of nearly 47% compared with other feasible solutions.

• Journal of Korean Institute of Industrial Engineers
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• v.21 no.4
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• pp.463-477
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• 1995

This paper presents a decision model that will estimate the expected number of failed units in a repair facility in accordance with the varying demand, and determine the required number of personnel for repairing components. The demand is related to the failure process which follows a reliability growth phenomenon in service. The information in this paper is useful for selecting appropriate scheduling rules and spares stocking policies. SIMAN and FORTRAN were used for computing the time dependent performance measures in the repair facility. The numerical integration method that is presented in this paper will provide accurate performance measures with any dynamic pattern of demand, service rates, and any number of servers.

• Korea Journal of Hospital Management
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• v.23 no.3
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• pp.87-103
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• 2018

Purpose: This study investigates the best appointment pattern which can enhance customer's satisfaction and hospital's efficient management reflecting plastic surgery clinic's service characteristics. Methodology: The data of this study is obtained from Plastic surgery Clinic which is located in the civic center. By collecting and analyzing the data, we build the simulation model using ARENA. Based on 5 appointment patterns that was suggested in formal appointment scheduling studies, we experiment 3 simulation models; 'Basic Appointment Pattern' that has no restriction, 'Restriction on Second Customer' that restricts the number of second customer's in each slot, 'Restriction on Process Time' that restricts the number of second customer who has long process time in each slot. We can check robustness of the appointment patterns by experimenting on off-peak day and peak day, during peak season. Findings: This study confirms that these 2 restrictions can give a better result than 'Basic Appointment Pattern' that just simply distributes customers by number. Especially, the performance of Triangle-like pattern which is the best appointment pattern in the formal study has been improved by adding restrictions. Based on 'DET', 'Restriction on Second Customer' shows a better result. Meanwhile, based on 'E(WT)', 'Restriction on Process Time' shows a better result. Overall, based on 'DET+E(WT)', 'Restriction on Second Customer' shows a better result. Practical Implications: The purpose of each hospital may alter as demand for plastic surgery grows increasingly. Thus, each hospital should be always prepared to introduce appointment pattern for changed purpose. In order to respond flexibly to these changes, it is necessary for medical personnel to improve the awareness or for hospital to create an environment by constructing appointment program so that medical personnel does not need to put more labor on work.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.16 no.4
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• pp.225-237
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• 2016

In conventional transportation problem (TP), all the parameters are always certain. But, many of the real life situations in industry or organization, the parameters (supply, demand and cost) of the TP are not precise which are imprecise in nature in different factors like the market condition, variations in rates of diesel, traffic jams, weather in hilly areas, capacity of men and machine, long power cut, labourer's over time work, unexpected failures in machine, seasonal changes and many more. To counter these problems, depending on the nature of the parameters, the TP is classified into two categories namely type-2 and type-4 fuzzy transportation problems (FTPs) under uncertain environment and formulates the problem and utilizes the trapezoidal fuzzy number (TrFN) to solve the TP. The existing ranking procedure of Liou and Wang (1992) is used to transform the type-2 and type-4 FTPs into a crisp one so that the conventional method may be applied to solve the TP. Moreover, the solution procedure differs from TP to type-2 and type-4 FTPs in allocation step only. Therefore a simple and efficient method denoted by PSK (P. Senthil Kumar) method is proposed to obtain an optimal solution in terms of TrFNs. From this fuzzy solution, the decision maker (DM) can decide the level of acceptance for the transportation cost or profit. Thus, the major applications of fuzzy set theory are widely used in areas such as inventory control, communication network, aggregate planning, employment scheduling, and personnel assignment and so on.

• Korea Journal of Hospital Management
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• no.spc
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• pp.1-13
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• 2016

In a situation where competition becomes intense, health care organizations constantly strive to provide more services with given personnel and time. While not only the 'quantity' of the services but also the 'quality' becomes increasingly important, various problems that can occur during the 'process' of service provision can be effectively managed by applying the methods of management science. In this study, we introduce the cases where the methods of management science can be applied for the management of health care organizations in Korea and abroad. There are many cases where various scenarios for improving the patients' accessibility to the services and for maximizing the efficient use of limited resources are established, and simulation or basic statistical analysis methods are used to solve the problems more systematically or to develop improvement plans. In this study, several exemplary cases, such as no-show of patients, crowding in the emergency room, prediction of the number of available beds in the intensive care units, nurse scheduling, delay of arrival of patients, and ordering of the proper amount of therapeutic materials, are introduced and discussed. From the perspective of administrators or clinicians, however, it may not be easy to master the methodology that requires considerable mathematical background or apply the theories to practice directly. Therefore, it is suggested that more practical and relatively simple analytical methods should be applied. Also, having a more positive attitude toward improving the current performance (e.g., a belief that 'we can always be better than now'), and paying attention to improving the job satisfaction by addressing problems, with experimental spirit and data-driven decision management.

• Quality Improvement in Health Care
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• v.4 no.1
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• pp.116-124
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• 1997

Background : As parking problem caused by increasing owner-driver and patients concentrating to a general hospital is becoming one of the dissatisfactions in medical care. It is time that a general hospital should solve the parking problem in a desirable way. The purpose of this survey is to let the clients understand the basic motivation of the pay parking and develop the better parking system. Methods : Clients of a tertiary care hospital in Chon-ju were surveyed by means of a questionnaire. All in all, 193 subjects answered the questionnaire. Results : In relation to previous experiences, 39.6% of the subjects experienced inconvenience with confused parking lot and the shortage of parking space. Under the current parking system, the subjects who felt the available parking space was enough were more than those who didn't 62.7% of the subjects answered that they could find the parking lot easily. 33.2% of the subjects mentioned that it was not easy to drive in the parking area ; The reasons were pointed out the shortage of space, disordered parking, and insufficient guide. 12.8% of the subjects satisfied with the current administering system of parking lot. The outpatients were more affirmative than the admitted patients about the charging system. As for the parking fee, 64% of the subjects answered that it is expensive, and 89.5% of the subjects thought imposing of parking fee is irrational. Conclusion : To say as a whole, the basic purpose of the charging system are more or less accepted. However, the management details like parking facilities and payment method are dissatisfactory, so it is necessary to improve the management system. It is also noted that the inpatients showed more negative attitude than the outpatients with the charging system. To secure a more convenient parking, the parking system should be considered in relation to the information service, kind guidance, improve facilities, personnel cooperation, fix outpatient scheduling system, etc.