• Title/Summary/Keyword: balancing control

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Power Compensator Control for Improving Unbalanced Power of AC Electric Railway (교류전기철도 불평형 전력 개선을 위한 전력보상장치 제어)

  • Woo, Jehun;Jo, Jongmin;Lee, Tae-Hoon;Cha, Hanju
    • The Transactions of the Korean Institute of Power Electronics
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    • v.25 no.3
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    • pp.213-218
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    • 2020
  • In this study, we propose a control algorithm to reduce the unbalanced characteristics of a three-phase system power caused by the unbalanced load of the AC electric railway. Then, we verify its performance through the design of a power compensator and experiments applying it. Like electric railway systems, a Scott transformer is applied, and the load and single-phase back-to-back converters are connected to the M-phase and T-phase outputs. The back-to-back converter monitors the difference in active power between the unbalanced loads in real-time and compensates for the power by using bidirectional characteristics. The active power is performed through PI control in the synchronous coordinate system, and DC link overall voltage and voltage balancing control are controlled jointly by M-phase and T-phase converters to improve the responsiveness of the system. To verify the performance of the proposed power compensation device, an experiment was performed under the condition that M-phase 5 kW and T-phase 1 kW unbalanced load. As a result of the experiment, the unbalance rate of the three-phase current after the operation of the power compensator decreases by 58.66% from 65.04% to 6.38%, and the excellent performance of the power compensator proposed in this study is verified.

Chronic pain control in patients with rheumatoid arthritis (만성통증 환자의 통증 조절)

  • Eun, Young
    • Journal of muscle and joint health
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    • v.2 no.1
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    • pp.17-40
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    • 1995
  • Rheumatoid arthritis is the one of the chronic diseases, one of its major symptoms is a chronic pain. Despite developing medical treatment and surgical techniques, it is suggested that to control the pain is the goal of the treatment. But pain is an inner experience and even those closest to the patient cannot truly observe its progress or share in its suffering. The National Academy of Sciences Institute of Medicine's report on Pain and Disability concluded that there is no objective measure of pain-(exactly) no pain thermometer-nor can there ever be one, because the experience of pain is inseparable from personal perception and social influence such as culture. To explore chronic pain experience is to understand the process and property of the patient's perception of pain through the response to pain, the coping with pain, and the adaptation to pain. Therefore a qualitative study was conducted in order to gain an understanding of pain experience of patients with RA in korea. I used naturalistic inquiry as a research methodology, which had 5 axioms, the first is that realities are multiple, constructed, and holistic, the second is that knower and known are interactive, inseparable, the third is only time and context bound working hypotheses(idiographic statements) are possible, the forth is all entities are in a state of mutual simultaneous shaping, so that it is impossible to distinguish causes from effects and the last is that inquiry is value-bound. Purposive sampling was conducted as a sampling. 20 subjects who experienced pain over 10 years, lived in middle-sized city and big city in Korea, and 17 women and 3 men. The subject's age was from 32 to 62 (average 48.8), all were married, living with their spouse and children, except two-one divorced and the other widow before they became ill. I collected data using In depth structured interview. I had interviews two or three times with each subject, and the interviews were conducted at each subject's home. Each interview lasted about two hours an average. A recording was taken with the consent of the subject. I used inductive data analysis-such as unitizing and categorizing. unitizing is a process of coding, whereby raw data are systematically transformed and aggregated into units. Categorizing is a process wherby previously unitized data are organized into categories that provide descriptive or inferential information about the context or setting from which the units were derived. This process is used constant comparative method. The pain controlling process is composed of behavior of pain control. The behaviors of pain control are rearranging of ADL, hiddening role conflict, balancing treatment, and changing social relation. Rearranging of ADL includes diet management, sleep management, and the adjustment of daily life activities. The subjects try to rearrange their daily activities by modified style of motions, rearranging time span & range of activities, using auxillary facilities, and getting help in order to keep on the pace of daily life. Hiddening role conflict means to reduce conflicts between sick role and their role as a family member. In this process, the subjects use two modes, one is to control the pain complaints, and the other is to internalize the value which is to stay home is good for caring her children and being a good mother. To control pain complaints is done by 'enduring', 'understanding' the other family members, or making them undersood in order to reduce pain. Balancing treatment is composed of two aspects. One is to keep the pain within the endurable level, the other is to keep in touch with medical personnel in order to get the information of treatment and emotional support. Changing social relation is made by information seeking and sharing, formation of mutual support relation, and finally simplification of social relationships. The subjects simplify their social relationships by refraining from relations with someone who makes them physically and psychologically strained. In particular the subjects are apt to avoid contact with in-laws, and the change of relation to in-laws results in lessening the family boundary. In the course of this process, they confront the crisis of family confict result in family dissolution. This crisis is related to the threat of self-existence. Findings from this study contribute to understanding the chronic pain experience. To advance this study, we should compare this result with other cases in different cultural contexts. I think to interpret these results, korean cultural background should be considered. Especially the different family concept, more broader family members and kinship network, and the traditional medical knowledge influences patients' behavior.

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The Study of the Design and Control for the Hydrogen Recirculation Blower Noise and Vibration Reduction (수소 재순환 블로어 소음 진동 저감을 위한 설계 및 제어에 관한 연구)

  • Bae, Ho June;Ban, Hyeon Seok;Noh, Yong Gyu;Jang, Seok Yeong;Lee, Hyun Joon;Kim, Chi Myung;Park, Yong Sun
    • Transactions of the Korean hydrogen and new energy society
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    • v.25 no.5
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    • pp.509-515
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    • 2014
  • At the fuel processing system (FPS) of fuel cell vehicle, hydrogen recirculation blower (HRB) is used for the recirculation of remained hydrogen after reaction. In this paper, noise and vibration improvement of HRB is studied by changing design and control. It is checked the campbell diagram and critical speed for stability of rotor, and housing stiffness is improved using simulation of frequency response function (FRF). A method is suggested that can decrease the unbalance amount of the rotor and impeller which main source of noise and vibration. In order to reduce the noise during deceleration of blower, electrical braking is applied and tested the risk impact of durability. Founded the optimum switching frequency of the motor control, and reduced the idle rpm by increasing of aerodynamic performance. The superiority of paper is proved by measurement of the improved product's noise and vibration.

Replication and Consistency Control in Hybrid Architectures for Multiplayer Online Games (멀티플레이어 온라인 게임을 위한 하이브리드 구조의 복제와 일관성 제어 기법)

  • Kim, Jin-Hwan
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.16 no.4
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    • pp.73-80
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    • 2016
  • Multiplayer Online Games(MOG) using the Internet are typically organized based on a CS(client-server) or P2P(peer-to-peer) architecture. We then propose a method that combines a P2P architecture with a CS architecture in order to utilize their advantages. Most MOGs use a primary-copy replication approach that provides strong consistency control over an object. For each object and character there exists an authoritative copy, called primary copy and all other copies are secondary copies or replicas. Any update to the object has to be first performed on the primary copy. In the proposed hybrid architecture, primary copies may reside on the server or be held by clients. In this architecture, load balancing between a server and clients can be achieved by reducing the number of objects maintained by the server. Games consist of various types of actions with different consistency requirements. A multi-level approach to game consistency is sensible as it provides the best trade-off between consistency and performance. The performance for the hybrid game architecture with the primary-copy model is evaluated through simulation experiments and analysis in this paper.

The Effects of Aroma Inhalation Therapy on Anxiety and Heart Rate Variability in the Patients Undergoing Urodynamic Study (아로마 흡입요법이 요역동학검사 환자의 불안과 심박변이도에 미치는 효과)

  • Kim, Myung-Wan;Yoo, Yang-Sook;Cho, Ok-Hee;Jo, Seong-Jun
    • Journal of Korean Biological Nursing Science
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    • v.11 no.1
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    • pp.32-41
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    • 2009
  • Purpose: This study was to identify the effects of aroma inhalation therapy on heart rate variability and anxiety in the context of urodynamics study. Method: The data were collected from 64 patients who were receiving urodynamics at the C University Medical Center in Seoul, 23 in the experimental group, 22 in the placebo group and 19 in the control group. In the experiment, the subjects of the experimental group inhaled a mixture of lavender and bergamot for 5 min, the subjects of the placebo group inhaled geranyl acetate oil for 5 min and the subjects of the control group relaxed for 5 min. The instruments used in this study included the state anxiety inventory and heart rate variability. Result: The score of state anxiety was no significant differences between the three groups after aroma-inhalation. Also, the sympathetic nerve activity and parasympathetic nerve activity was no significant differences between the three groups after aroma-inhalation. Autonomic nerve balance was maintained significantly in the experimental group as compared to the control groups after aroma-inhalation. Conclusion: The aroma inhalation therapy was very effective in balancing the autonomic nervous system in the patients undergoing urodynamic study.

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An experimental study on instability and control of co-flow diffusion flames (동축류 확산화염의 불안정성과 제어에 관한 실험적 연구)

  • Lee, Hyeon-Ho;Hwang, Jun-Yeong;Jeong, Seok-Ho;Lee, Won-Nam
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.21 no.1
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    • pp.153-164
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    • 1997
  • Flame oscillation phenomena in a co-flow diffusion flame was experimentally studied with periodic fuel supply using a solenoid valve. The degree of excitation was controlled by changing the volume flux of fuel passing through the valve. Flame oscillation frequencies were measured utilizing a photodiode, a spectrum analyzer, video and high speed movies. Laser planar visualization was employed to study the correlation between the flame oscillation and the toroidal vortices. Observed are three regimes of flame oscillation, where the oscillation frequencies are for the multiples of excitation, the excitation itself and the flame natural oscillation. Both periods of natural oscillation and of excitation induced oscillation exist over one cycle of the excitation in the frequency multiplied regime. It is considered as an effect of balancing the influence of buoyancy driven vortex with that of excitation induced vortex near the excitation rate of 0.2. Flame shapes are become monotonous as increasing the excitation frequency to the range of over two fold of the natural oscillation. The flame oscillation can be modulated to the frequency of either multiples of excitation or excitation itself under certain conditions. This implies that the flame oscillation could be modulated to avoid the resonance frequency of the combustor, and shows the possibility of active control of the flame oscillation.

Total Diet Study: For a Closer-to-real Estimate of Dietary Exposure to Chemical Substances

  • Kim, Cho-il;Lee, Jeeyeon;Kwon, Sungok;Yoon, Hae-Jung
    • Toxicological Research
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    • v.31 no.3
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    • pp.227-240
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    • 2015
  • Recent amendment on the Food Sanitation Act in Korea mandated the Minister of Food & Drug Safety to secure the scientific basis for management and reevaluation of standards and specifications of foods. Especially because the current food safety control is limited within the scope of 'Farm to Market' covering from production to retail in Korea, safety control at the plane of true 'Farm to Fork' scope is urgently needed and should include 'total diet' of population instead of individual food items. Therefore, 'Total Diet Study (TDS)' which provides 'closer-to-real' estimates of exposure to hazardous materials through analysis on table-ready (cooked) samples of foods would be the solution to more comprehensive food safety management, as suggested by World Health Organization and Food and Agriculture Organization of the United Nations. Although the protection of diets from hazards must be considered as one of the most essential public health functions of any country, we may need to revisit the value of foods which has been too much underrated by the meaningless amount of some hazardous materials in Korea. Considering the primary value of foods lies on sustaining life, growth, development, and health promotion of human being, food safety control should be handled not only by the presence or absence of hazardous materials but also by maximizing the value of foods via balancing with the preservation of beneficial components in foods embracing total diet. In this regard, this article aims to provide an overview on TDS by describing procedures involved except chemical analysis which is beyond our scope. Also, details on the ongoing TDS in Korea are provided as an example. Although TDS itself might not be of keen interest for most readers, it is the main user of the safety reference values resulted from toxicological research in the public health perspective.

Development of Super-capacitor Battery Charger System based on Photovoltaic Module for Agricultural Electric Carriers

  • Kang, Eonuck;Pratama, Pandu Sandi;Byun, Jaeyoung;Supeno, Destiani;Chung, Sungwon;Choi, Wonsik
    • Journal of Biosystems Engineering
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    • v.43 no.2
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    • pp.94-102
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    • 2018
  • Purpose: In this study, a maintenance free super-capacitor battery charging system based on the photovoltaic module, to be used in agricultural electric carriers, was developed and its charging characteristics were studied in detail. Methods: At first, the electric carrier system configuration is introduced and the electric control components are presented. The super-capacitor batteries and photovoltaic module used in the experiment are specified. Next, the developed charging system consisting of a constant current / constant voltage Buck converter as the charging device and a super-capacitor cell as a balancing device are initiated. The proposed circuit design, a developed PCB layout of each device and a proportional control to check the current and voltage during the charging process are outlined. An experiment was carried out using a developed prototype to clarify the effectiveness of the proposed system. A power analyzer was used to measure the current and voltage during charging to evaluate the efficiency of the energy storage device. Finally, the conclusions of this research are presented. Results: The experimental results show that the proposed system successfully controls the charging current and balances the battery voltage. The maximum voltage of the super-capacitor battery obtained by using the proposed battery charger is 16.2 V, and the maximum charging current is 20 A. It was found that the charging time was less than an hour through the duty ratio of 95% or more. Conclusions: The developed battery charging system was successfully implemented on the agricultural electric carriers.

A Development of Floating Dock Controller for Skid Launching System (Skid Launching System을 위한 Floating Dock Controller의 개발)

  • Kim, Jee-Hun;Lee, Jang-Yong;Park, Sok-Chu
    • Journal of Navigation and Port Research
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    • v.33 no.6
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    • pp.375-380
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    • 2009
  • The authors had consisted the construction of shipyard must be investigated under the consideration of long term ship's demand and so the Floating Dock might be an alternative to the dry dock. This paper shows a development of Floating Dock Controller for Skid Launching System(SLS). While loading out a block to the Floating Dock and launching ship from the Floating Dock, the balancing of the ship and the dock is very important and achieved by adjusting the Ballast tank of the Floating Dock In this paper a Floating Dock Controller for SLS was developed through the on-line interface of VRC(Valve Remote Control), Tank Level & Draft Measuring System and Valve Control algorithm on Tank Plan. The control system developed was applied to a shipbuilding and verified good and stable.

Effects of Trunk-Stabilization Exercise Program on Static and Dynamic Balance of Elderly With History of Leprosy Patients According to Sole Sensory Conditions (체간안정화 운동프로그램이 한센병력노인의 발바닥 감각상태에 따른 정적·동적 균형에 미치는 영향)

  • Jung, Soon-Mi
    • Physical Therapy Korea
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    • v.18 no.1
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    • pp.18-27
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    • 2011
  • This study was to investigate the positive effects of specially designed trunk-stabilization exercise program on lower extremity balance of elderly with history of leprosy. In this participants, lower extremity functions has been undermined by the development of damage in peripheral nerves. A total of 40 elderly with history of leprosy were divided into 2 groups of equal size ($n_{1,\;2}=20$): a group that participated in the exercise program, and a control group that did not exercise but did continue to engage in normal daily activities (including walking). The exercise group exercised for 60 minutes 2 days a week for 12 weeks. Static balance ability was measured by asking study participants to a one leg standing test: dynamic balancing ability was measured with a tandem walking test and a timed up-and-go test. The participants in the exercise program and the control group were tested before and after completion of the exercise program for comparison, and then divided according to their ability to feel sensory in the soles of their feet into the categories of normal sensory group: group with sensory loss in one foot: and group with sensory loss in both feet. The participants in the exercise program showed a positive, statistically significant difference in static balance compared with the control group (p<.05) as measured using the one leg standing test. Similarly, the participants in dynamic balance (p<.05) as measured using the tandem walking and timed up-and-go tests. Finally, these improvements were related to the severity of sensory loss in the soles of the feet for all study participants.