• Nuclear Engineering and Technology
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• v.25 no.3
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• pp.371-380
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• 1993

A model free controller utilizing a set of linguistic fuzzy logic of the human operator's experience is developed to control the steam generator water level in a pressurized water reactor. Only 9 rules for control action are generated from the inputs of water level error and mass flow error implicitly representing the time variation of the collapsed water level. The bell type membership functions of the premise side and the result side are tuned by the sensitivity study. This compact fuzzy logic controller shows a robust control during transient and no offset error and oscillation during steady state operation. For a multi-ramp power increase from start-up to full power, the proposed controller shows good performance for the entire range.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.4
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• pp.311-317
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• 2015

This paper describes how to apply one-dimensional simulation to predict unsteady state characteristics of the cold-gas pintle thruster. Mass flow rate, chamber pressure, and nozzle exit pressure are key parameters for thrust control. Chamber pressure rose and fell monotonously with the pintle stroke variation, while thrust variation was different from chamber pressure variation. During the forward pintle stroke operation, the thrust value tended to decrease initially and returned to increase when pintle speed and chamber free volume exceed some specified value. Even though one-dimensional simulation has the limitations to predict unsteady state characteristics, it is still useful for initial performance assessment of various thrusters which adopt an altitude compensation nozzle such as a dual-bell nozzle, prior to experiment or numerical analysis.

• Journal of Communications and Networks
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• v.16 no.1
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• pp.1-9
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• 2014

Block diagonalization (BD) has been proposed as a simple and effective technique in multiuser multiple-input multiple-output (MU-MIMO) broadcast channels. However, when channel state information (CSI) knowledge is limited at the transmitter, the performance of the BD may be degraded because inter-user interference cannot be completely eliminated. In this paper, we propose an efficient CSI quantization technique for BD precoded systems with limited feedback where users supported by a base station are selected by dynamic scheduling. First, we express the received signal-to-interference-plus-noise ratio (SINR) when multiple data streams are transmitted to the user, and derive a lower bound expression of the expected received SINR at each user. Then, based on this measure, each user determines its quantized CSI feedback information which maximizes the derived expected SINR, which comprises both the channel direction and the amplitude information. From simulations, we confirm that the proposed SINR-based channel quantization scheme achieves a significant sum rate gain over the conventional method in practical MU-MIMO systems.

• Journal of the Korean Society of Costume
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• v.44
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• pp.131-141
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• 1999

The purpose of this study was to investigate the various expressions with materials in fashion illustration using CAD comparing with hand work. The design motive for this study is to be selected from Bell Epoque era which was the revolutionary period in fashion illustration. The results of this study were as follows: 1. By using CAD, water color was well expressed to repeat brushing for the clarity, darkness, and brightness. It was more effective to use CAD in layering or duplicating complex and intricate patterns because the base color gets to be concealed under the repeated oil pastel. Acryl, like oil pastel, was easily absorbed in canvas, so it is effective to repeat brushing for expressing pure color. It was inconvenient to use wax crayon for controlling the moderate opacity because wax crayon absorbed water color dye stuffs, so crayon line was concealed when repetitions were being done. 2. The advantage of using CAD was convenience for getting rid of troublesome process and inefficient works. Also, CAD had a good tool like oil pastel in the use of coloring work by using pure color. By using CAD, various expressions on materials and texture of surface can be achieved effectively. Also, it is very strong substitute for time-saving, convenience, economic aspects from providing simple instrument, and production in the state of various kinds of paper and canvas as a method of visualization. Therefore, fashion illustration using CAD provides effective way of producing works, and gives promising vision in the future.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.2 no.3
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• pp.243-255
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• 1990

The objective of this study is to present an efficient measurement method of the effective thermal diffusivity for the fibrous insulation material. The non-linear parameter estimation (NPE) method is adapted for this analysis because of its accuracy and its results are compared with those by other direct methods such as CTP, CHP and STD method. A experimental system is constructed with bell-jar vaccum chamber, diffusion pump, tube type furnace, control unit and data acquisition system included with A/D converter and IBM XT/AT personal computer. The typical results obtained from this study are as follows; 1) NPE method can be recommended as an useful and accurate method to measure the effective thermal diffusivity of insuation material because it is shown that the measurement error compared with those by other direct methods is reduced for standard material, NBS-1450b. 2) NPE method can minimize the effects of ill-measured temperature due to external disturbance, because the final value is found by point to point estimating. 3) NPE method dose not depend on the kinds of heat flux, since the surfac temperature are used to estimate the thermal diffusivity. 4) With NPE method, compared with the steady state method, a measuring time and a sample size could be reduced.

• Smart Structures and Systems
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• v.14 no.2
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• pp.191-207
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• 2014

In this research, an internal model based method is proposed to estimate the structural displacements and velocities under ambient excitation using only acceleration measurements. The structural response is assumed to be within the linear range. The excitation is assumed to be with zero mean and relatively broad bandwidth such that at least one of the fundamental modes of the structure is excited and dominates in the response. Using the structural modal parameters and partial knowledge of the bandwidth of the excitation, the internal models of the structure and the excitation can be respectively established, which can be used to form an autonomous state-space representation of the system. It is shown that structural displacements, velocities, and accelerations are the states of such a system, and it is fully observable when the measured output contains structural accelerations only. Reliable estimates of structural displacements and velocities are obtained using the standard Kalman filtering technique. The effectiveness and robustness of the proposed method has been demonstrated and evaluated via numerical simulations on an eight-story lumped mass model and experimental data of a three-story frame excited by the ground accelerations of actual earthquake records.

• Korean journal of food and cookery science
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• v.15 no.3
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• pp.272-287
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• 1999

Elementary schools students'degree of satisfaction on school food service and food preference were surveyed from 352 sixth-grade students in Kwangju and Chonnam area from June 22 to July 3 to enhance the quality of foodservice. The degree of satisfaction was high with cooked rice and soup in terms of temperature and serving state. There were significant differences in the degree of satisfaction depending upon the types of foodservice (p<0.001). There was significant differences in degree of satisfaction for side dishes depending upon the temperature (p<0.05), kinds (p<0.01) and amount (p<0.001). The degree of satisfaction with Kimchi was generally high in the serving state (p<0.05) and the amounts (p<0.01). The degree of satisfaction with desserts were high in the amount (p<0.001). The amount of leftover was high with soup, side dishes, kimchi, cooked rice, and desserts in order. The improvements made on children's behavior after the implementation of the school foodsevice were the adaptation to balanced diet and spending less money on sweets. The factors of influencing the school foodservice and the children's food intake were the education in school (teachers and dietitians) and the health status of their bodies (p<0.001). Children's favorite foods were sweet and sour pork, pork cutlets, oranges, watermelons, and strawberries in order. The least preferred foods were garlic seasoned with soy sauce, raw vegetables of broad bell-flowers, crown daisy greens, and steamed peppers. Children's favorite food types were fried food, desserts, one course meal, and bread. The least preferred types were pickled food, green and seasoned vegetables, cooked rice, and hard-boiled food in order. Generally, the children in the rural area favored most foods compared with those from urban area.

• Korean Journal of Social Welfare
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• v.39
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• pp.350-373
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• 1999

The patient population of U. S. state mental hospitals has changed drastically since the 1960s, when the deintstitutionalization movement began. This paper is designed to look at what happened to the number of inpatients of state hospitals in California during the last 150 years and, from this, to explore implications for the future of the mental health system in Korea, especially for the viability of mental hospitals. The data had been collected by field research(visits to state hospitals and State Department of Mental Health, and interviews with mental health administrators) and accessing statistical publications and various reports. Since the first state hospital opened in 1851 the statewide inpatient population of individuals who were mentally disabled has grown and peaked at 37,489 in 1959. The number of patients in state hospitals, however, began declining in the early 1960s and was reduced to 10,874 by 1971, and to 4,973 by 1986. As of 1997, there were only 4, 263 inpatients remaining in the state hospital system. This dramatic decrease slowed down somewhat in 1980s and 1990s, but this trend seems irreversible except for the inpatients referred by the court. Now the beds in state hospitals are filled with more and more forensic patients, which constitutes nearly 70% of the total inpatient population. Based on these findings, it is well expected that the number of inpatients of mental hospitals in Korea will also be reduced in a significant way as the community-based mental health care system is gradually replacing the traditional one. Mental hospitals need to introduce more diversified programs for the care of the mentally ill, and concurrently more vigorous aftercare programs are required in the community.

• Journal of the Korean Professional Engineers Association
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• v.24 no.6
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• pp.106-112
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• 1991

Electronics has different meanings to different people and in different countries. Hence, let me difine the term in the sense that it is used here. Electronics in the science and the technology of the passage of charged particles in a gas, in a vacumn, or in a semiconductor. The beginning of electronics came in 1895 when H. A. Lorentz postulated the existence of discrete charges called electrons. Two years later J.J. Thompson found these electrons experimentally. In the same year (1897) Braun built what was probaly the first electron tube, essentially a primitive cathode-ray tube. It was not until the start of the 20th century that electronics began to take technological shape. In 1904 Fleming invented the diode which he called a valve. This era begins with the invention of the transistor about 30 years ago. The history of this invention is interesting. M.J. Kelly, director of research(and later president of Bell Laboratories), had the foresight to realize that the telephone system needed electronic switching and better amplifiers. Vacuum tubes were not very reliable, principally because they generated a great deal of heat even when they were not being used, and, particularly, because filaments burned out and the tubes had to be replaced. In 1945 a solid-state physics group wa formed. The foregoing completes the history of electronics and electronic industries up to 1978. There is already a start toward a merging of the computer and the communication industries which might be called information manipulation. This includes storage of information, sorting, computation, information retrieval, and transmission of data. This combination of the computer and the communication fields will penetrate many disciplines. Applications will be made in the fields of law, medicine, biological sciences, engineering, library services publishing banking, reservation systems, management control, education, and defense.

• Journal of Acupuncture Research
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• v.19 no.5
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• pp.112-123
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• 2002

Background and Objective : The evaluation of facial nerve function is a complex procedure. The House-Brackmann facial nerve grading system(H-B grade)and the Yanagihara grading system(Y-system) have been recommended as universal standards for assessing the degree of facial nerve palsy. The purpose of this study is to compare the effectiveness of Y-system and H-B system and to know the advantages of each system for each stage of incomplete recovery or sequelae of facial paralysis. Materials and Methods : A comparison between H-B grade and Y-system was studied with 137 evaluations of 61 cases of incomplete recovery or sequelae of peripheral facial paralysis. Each case was graded by using H-B system as a gross system and Y-system as a regional system before treatment, after 12 weeks and 6 months Results and Conclusions : The range of score in the Y-system 0-6, 8-16, 14-22, 24-34, 32-38, 38-40 were matched with grade VI, V, IV, III, II and I in the H-B system. The percentage of H-B grade III was the greatest among 137 evaluations and y-system showed the greatest score range. H-B system is easy to use but Y-system is more objective, quantitative and convenient to use in the incomplete recovery or sequelae state.