• Journal of the Korean Institute of Educational Facilities
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• v.25 no.1
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• pp.3-12
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• 2018

Educational facilities are more uncertain about maintenance costs due to their comprehensive and long life-cycle compared to commercial buildings. In addition, maintenance of the existing post management system can not maintain the original function of education facilities continuously and economically. In order to overcome this problem, it is necessary to analyze the repair and replacement cost for the uncertainty factor in maintenance. This study propose a model to determine repair and maintenance cost and cycle of educational facility based on probabilistic estimation concept. For the analysis, Monte Carlo simulation, a probabilistic analysis method, was applied based on the repair and maintenance history data of the educational facilities in Florida. The results of this study can be used as a guideline for quantitative facility management and facility management research.

• Journal of Korean Society for Atmospheric Environment
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• v.22 no.3
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• pp.297-307
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• 2006

During January $2002{\sim}April\;2004$, hydrogen peroxide ($H_{2}O_{2}$) measurements were performed at the campus of Korea University, which is located in the northeastern part of Seoul. Gas phase hydroperoxide was collected in aqueous solution and separated by HPLC. Concentrations were determined by fluorescence using postcolumn enzyme derivatization. This measurement system was improved to be run automatically from sample collection at every 10 minutes through chemical analysis for data collection. Detection limits of $H_{2}O_{2}$ is $10{\sim}17\;pptv$, and the overall uncertainty of the measurements is better than 8%. Two-year measurements of $H_{2}O_{2}$ show typical seasonal variations. Concentrations of $H_{2}O_{2}$ were higher during $June{\sim}October$ and lower during $January{\sim}February$. Maximum concentration of 1-hour averaged $H_{2}O_{2}$ was 6.5 ppbv, which was observed in August and September. In general $H_{2}O_{2}$ concentrations were well correlated with $O_{3}$ concentrations and largely affected by meteorological factors such as temperature and wind direction.

• Korean Management Science Review
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• v.33 no.1
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• pp.101-117
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• 2016

In 2000s, incidence of natural disaster is increasing continuously. Therefore, the necessity of research on the effective disaster response is emphasized. Korea is not safe from natural disaster. Natural disasters like torrential downpours, typhoons have occurred more frequently than before. In addition disasters like droughts and MERS has also occurred. Therefore, needs for effective systems and algorithms to respond disaster are increased. This study covers the vehicle routing problem for effective logistics in disaster situations caused by natural disasters. The emergency vehicle route problem has different property from the general vehicle route problem. It has the property of the importance of deadline, the uncertain and dynamic demand information, and the uncertainty in information transfer. In this study, a solution that focused on the importance of deadline. In this study, the heuristic solution using the genetic algorithm are suggested. Finally the simulation experiment which reflects the actual environment are conducted to verify the performance of the solution.

• Journal of Distribution Science
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• v.14 no.9
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• pp.5-13
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• 2016

Purpose - This study proposes a framework for service innovation strategy to cope with the emergence of electric vehicles. Research design, data, and methodology - This study designs an electric-vehicle lease program and collects the resulting data to analyze. By analyzing the previous studies on the electric-vehicle market with cases, a theoretical framework based on existing theories is to be set. Results - This study proposes a strategy for the rapid diffusion of electric vehicles. First, a partitioned-pricing system is proposed to create an advantage for electric vehicles in terms of initial purchasing cost relative to traditional internal combustion vehicles. Second, focusing on reducing switching costs is important because electric vehicles have relatively low resale values due to the uncertainty of battery life. Third, a battery-leasing strategy is supposed to reduce the cost of switching from a traditional internal combustion vehicle to an electric vehicle. Conclusions - This paper can provide strategic guidance for decision makers in firms that have already entered the electric-vehicle leasing market by making a recommendation such as a service innovation strategy. The proposed strategy can be considered as an electric vehicle market in the future and can contribute to the wider diffusion of electric vehicles.

• International Journal of Control, Automation, and Systems
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• v.3 no.1
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• pp.70-78
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• 2005

This paper presents hybrid control of displacement and force in a Medical Tele-Analyzer by disturbance observer-based controller which is robust to internal and external disturbances; model uncertainty, load, and friction for instances. The developed Medical Tele-Analyzer consists of 2 subsystems; doctor-side subsystem and patient-side subsystem. In the doctor side subsystem, an array of displacement sensor is equipped to detect movement of doctor's hand and fingers. The detected information is transmitted to the patient side to be used in medical analysis. On the other hand, the patient-side subsystem consists of an array of displacement actuators, which is used to follow displacement of doctor's hand and fingers. An array of force sensors is used to detect forces between patient and the equipment. Since displacement control in patient side is coupled with force control in doctor side and vice-versa, design of the controller has to take into account this coupling. Not only using in medical tele-analysis, the proposed system can also be used in any tele-displacement-force controls of industrial processes.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.6
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• pp.417-423
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• 2016

Using a sliding mode controller and observer techniques, this paper presents a robust current controller for a DC motor in the presence of parametric uncertainties. One of the most important issues in the practical application of sliding mode schemes is the chattering phenomenon caused by switching actions. This paper presents a novel sliding mode controller that incorporates an integral control with a sliding mode disturbance observer to attenuate the chattering by reducing the controller/observer switching gains. The proposed sliding mode disturbance observer is designed to estimate a relatively slow varying signal in the equivalent lumped disturbance owing to system uncertainties. Combining the estimated uncertainty with the sliding mode control input, the proposed controller can achieve the control objective by using the relatively low gain of the controller. The proposed disturbance observer does not include the switching control input of the baseline sliding mode controller to reduce the observer switching gain. In the proposed approach, the integral sliding mode control is used to improve the steady state control performance. Comparative computer simulations are carried out to demonstrate the performance of the proposed method. Through the simulation results, the proposed controller realizes the robust performance with reduced current ripples.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.41 no.3
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• pp.79-90
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• 2004

Systematical robust stability analysis and design scheme for the feedback linearization control systems via fuzzy modeling are proposed. It is considered that uncertainty and disturbances are included in the Takagi-Sugeno fuzzy models representing the nonlinear plants. Robust stability of the closed system is analyzed by casting the systems into the diagonal norm bounded linear differential inclusions and by converting the analysis and design problems into the linear matrix inequality optimization, a numerical method for finding the maximum stable ranges of the fuzzy feedback linearization control gains is also proposed. To verify the effectiveness of the proposed scheme, the robust stability analysis and control design examples are given.

• Child Health Nursing Research
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• v.13 no.4
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• pp.454-466
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• 2007

Purpose: To explore the experiences of parenting from the mothers of children with severe CHD and to develop a grounded theory about their experiences. Method: Grounded theory method guided the data collection and analysis. A purposeful sample of 16 mothers of children with severe CHD participated during the period 2003. The data were collected by semi-structured individual interviews. Results: "Raise with dignity" emerged as the core phenomenon. 'Powerlessness' came up as the central concept. The causal conditions working on powerlessness was 'living with a bomb in the heart': uncertainty and the context were 'confronting people's eyes', 'developing child's adaptability'. An intervening condition was 'forming a support system' and consequences for coping with powerlessness were 'overcome' or 'ambivalence' using the strategies for mother's positive personality, care role perception, accepting, acknowledgement, and managing the body and mind. Conclusions: In the results of this study, the mothers of children with severe CHD are continue to struggle with life during children's growth and repeated attacks of disease. They need to be provided with skills to cope with physical and mental problems in rearing the children with expertized information for the entire period of growth.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.73.2-73.2
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• 2016

We present the results of KaVA SgrA* observation together with Takahagi(32m), Yamaguchi(32m) and Nobeyama(45m) telescopes at 22 and 43GHz, respectively. In early 2014, G2 cloud was expected to encounter with SgrA* and to make a significant flux variation, but it has not been measured yet. So it's worth to check our amplitude calibration method to confirm if we have a missing flux caused by uncertainty in measuring it. We have tested both a standard method using system noise temperature(Tsys) with antenna gain information, and a template method in order to calibrate antenna gain using nearby maser source. As a result, we found that the latter method is useful for antennas which have inaccurate gain information or poor Tsys measurements, and is especially effective for sources at low elevation like SgrA*. In addition, the comparison shows that the amplitude calibration by standard method can be improved up to 10% with a correction factor using a template method. This result implies we can get more accurate flux from a standard method when any maser source not exists around target.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.10 no.1
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• pp.12-18
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• 2010

This paper proposes an adaptive robust fuzzy control scheme for path tracking of a wheeled mobile robot with uncertainties. The robot dynamics including the actuator dynamics is considered in this work. The presented controller is composed of a fuzzy basis function network (FBFN) to approximate an unknown nonlinear function of the robot complete dynamics, an adaptive robust input to overcome the uncertainties, and a stabilizing control input. Genetic algorithms are employed to optimize the fuzzy rules of FBFN. The stability and the convergence of the tracking errors are guaranteed using the Lyapunov stability theory. When the controller is designed, the different parameters for two actuator models in the dynamic equation are taken into account. The proposed control scheme does not require the accurate parameter values for the actuator parameters as well as the robot parameters. The validity and robustness of the proposed control scheme are demonstrated through computer simulations.