• Title/Summary/Keyword: control period

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Analysis and Control of Low Frequency Oscillation using TCSC Small Signal Model by Control of Firing Angles (TCSC의 소신호 모형을 이용한 점호각 제어에 의한 저주파 진동 감쇠 효과 해석 및 제어)

  • Kim, Tae-Hyun;Seo, Jang-Cheol;Park, Jong-Keun;Moon, Seung-Ill;Han, Byung-Moon
    • Proceedings of the KIEE Conference
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    • 1995.11a
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    • pp.120-124
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    • 1995
  • TCSC can not only increase power flow but also damp low frequency oscillation by controlling firing angles of thyristors. But, a model considering voltage, current firing angles is not derived. This paper used a small signal model considirng these variables which was derived in paper [1]. TCSC model is combined with swing equation. Being related to rotor angles and firing angles of thyristors, current and synchronizing torque coefficient is reformulated. Because firing angles of thyristors can be controlled only twice within one period, swing equation is transformed to discrete time model. It is shown that low frequency oscillation can be damped by controlling firing angles in one machine infinite bus power system.

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Robust Discretization of LTI Systems with Polytopic Uncertainties and Aperiodic Sampling

  • Lee, Dong Hwan;Park, Jin Bae;Joo, Young Hoon
    • Journal of Electrical Engineering and Technology
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    • v.10 no.3
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    • pp.1255-1263
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    • 2015
  • In the previous work, the authors studied the problem of robust discretization of linear time-invariant systems with polytopic uncertainties, where linear matrix inequality (LMI) conditions were developed to find an approximate discrete-time (DT) model of a continuous-time (CT) system with uncertainties in polytopic domain. The system matrices of obtained DT model preserved the polytopic structures of the original CT system. In this paper, we extend the previous approach to solve the problem of robust discretization of polytopic uncertain systems with aperiodic sampling. In contrast with the previous work, the sampling period is assumed to be unknown, time-varying, but contained within a known interval. The solution procedures are presented in terms of unidimensional optimizations subject to LMI constraints which are numerically tractable via LMI solvers. Finally, an example is given to show the validity of the proposed techniques.

Development of Piano Playing Robot (피아노 연주 로봇의 개발)

  • Park, Kwang-Hyun;Jung, Seong-Hoon;Pelczar, Christopher;Hoang, Thai V.;Bien, Zeung-Nam
    • Proceedings of the KIEE Conference
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    • 2007.04a
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    • pp.334-336
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    • 2007
  • This paper presents a beat gesture recognition method to synchronize the tempo of a robot playing a piano with the desired tempo of the user. To detect an unstructured beat gesture expressed by any part of a body, we apply an optical flow method, and obtain the trajectories of the center of gravity and normalized central moments of moving objects in images. The period of a beat gesture is estimated from the results of the fast Fourier transform. In addition, we also apply a motion control method by which robotic fingers are trained to follow a set of trajectories, Since the ability to track the trajectories influences the sound a piano generates, we adopt an iterative learning control method to reduce the tracking error.

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Peri-Parturient Nematode Egg Rise in Indonesian Ewes

  • Batubara, A.;Dorny, P.;Pandey, VS.;Romjali, E.;Feldman, K.
    • Asian-Australasian Journal of Animal Sciences
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    • v.10 no.3
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    • pp.293-297
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    • 1997
  • Studies were designed to study the peri-parturient rise in strongyle faecal egg counts (FEC) in ewes grazing in a rubber plantation in North Sumatra, Indonesia. In three consecutive lambing seasons strongyle FEC of peri-parturient ewes and dry ewes were monitored from 2 to 3 weeks before lambing until 7 to 9 weeks post lambing to measure the magnitude and duration of the peri-parturient rise. A significant rise in FEC was observed during the post-parturient period in two of the three studies. FEC increased in the three studies from lambing day, and were elevated until 5 to 9 weeks following lambing. Lactating ewes shed on average 3 times more eggs than dry ewes. Lactating ewes were therefore considered as an important source of pasture infection. These findings are discussed in relation to the epidemiology and control of gastrointestinal nematodes in the humid tropics.

Obviously Increasing Incidence Trend for Males but Stable Pathological Proportions for Both Genders: Esophageal Cancer in Zhongshan of China from 1970-2007

  • Wei, Kuan-Grong;Liang, Zhi-Heng
    • Asian Pacific Journal of Cancer Prevention
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    • v.13 no.5
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    • pp.1783-1786
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    • 2012
  • Objectives: To analyze esophageal cancer incidence and pathological data of Zhongshan in China in 1970-2007, and to provide scientific information for its prevention and control. Methods: From Zhongshan Cancer Registry esophageal cancer incident and pathological data were obtained. Pathological proportions and trends were calculated and analyzed. Results: Although there was a continuously and obviously increasing trend for male incidence rates in 1970-2007 in Zhongshan, squamous cell carcinoma (SCC) and adenocarcinoma (AD) incident proportions during 1990-2007 remained relatively stable. Moreover, SCC was the major pathological type, accounting for 70.6 percent of all new cases, while AD were relatively few and accounted for only 2.66 percent throughout the period. Conclusion: The male esophageal cancer incident pattern in Zhongshan in 1970-2007 was quite different from most other domestic areas. The data suggest that etiological analysis should be enhanced for improved control in Zhongshan.

Epidemiology of Esophageal Cancer in Kazakhstan

  • Igissinov, Saginbek;Igissinov, Nurbek;Moore, Malcolm A.;Kalieva, Zhansaya;Kozhakhmetov, Saken
    • Asian Pacific Journal of Cancer Prevention
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    • v.13 no.3
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    • pp.833-836
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    • 2012
  • The incidence of esophageal cancer in Kazakhstan was analysed for the period of 1989-2010 years, with a focus on trends by age, gender and region. The highest rates of incidence were evident in the Western regions. The dynamics for cancer of the esophagus in the Republic demonstrated decrease, except in the Karaganda region, where a tendency for increase was noted. Considerable variation between regions pointed to differences in risk factor exposure which need to be targeted for future control efforts.

Effects of Heated Oil on Lipid Peroxidation in Rat Liver (가열유가 흰쥐 간장폐의 지질과산화에 미치는 영향)

  • 이경숙
    • Journal of Nutrition and Health
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    • v.20 no.1
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    • pp.15-24
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    • 1987
  • To study effects of heated oil on lipid peroxidation in rat liver, rats were fed 3 and 6 weeks by intubating oils heated for l1(HA group) and 24 hours (HB group) at 18$0^{\circ}C$. The contents of lipid peroxides and vitamin E, and the activities of super oxide dismutase and glutathione peroxidase in liver were measured. Histological changes of the liver tissue were observed. In both HA and HE groups, the contents of lipid peroxides and the activities of superoxide dismutase were increased, but the activities of glutathione peroxidase and the contents of vitamin E in liver were decreased when compared to the control group which was fed fresh cora oils. During the oil feeding period, the activities of superoxide dismutase and the contents of vitamin E were not significantly changed, but the activities of glutathione peroxidase were decreased, and lipid peroxides were increased in the 3 weeks than in 6 weeks. In HB liver, the heterochromatin of nucleus increased, mitochondria swellen, cristae in mitochondria disappeared, fat droplet and secondary lysosome increased and lumen of rough endoplasmic reticulum enlarged, compared with that of the control group. These phenomena in HA group were less pronounced.

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The Effects of a Weight Control Program with Competence (유능감 강화 체중 조절 프로그램의 효과)

  • Seo, Yeong-Mi;Suh, Sun-Lim
    • Journal of Korean Academy of Nursing
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    • v.37 no.7
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    • pp.1177-1183
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    • 2007
  • Purpose: The purpose of this study was to identify the effects of a weight control program and compliancy in overweight women. Method: This program was composed of strategies to modify diet and exercise and to change compliance and self determination over an 8 week period. The subjects were 19 overweight women who participated in our project voluntarily. Data was collected from May 4 to Jun 30 of 2007. The program consisted of regular rapid walking exercise, diet, mobile phone messages and e-mail. The data was analyzed by Repeated Measures ANOVA using the SPSS WIN program. Result: According to 3 assessment periods, there were significant differences in body weight, body mass index, and compliance. There were no significant differences in self determination. Conclusion: These findings suggest that more intensive interventions may be needed to demonstrate a change in self determination.

Beneficial effects of Phellodendri Cortex extract on hyperglycemia and diabetic nephropathy in streptozotocin-induced diabetic rats

  • Kim, Hye-Jeong;Kong, Min-Kyu;Kim, Young-Chul
    • BMB Reports
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    • v.41 no.10
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    • pp.710-715
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    • 2008
  • This study investigated the effect of Phellodendri Cortex extract on hyperglycemia and diabetic nephropathy in streptozotocin-induced diabetic rats. Male Sprague-Dawley rats were divided into normal control (NC), diabetic control (DC), and diabetic treatment with Phellodendri Cortex extract (DP). Over a 4-week experimental period, Phellodendri Cortex extract was administered orally at 379 mg/kg BW/day. The final fasting serum glucose level, urine total protein level, and relative left kidney weight in the DP group were significantly lower than the DC group. Renal XO and SOD activities in the DP group were significantly lower than the DC group and renal CAT activity in the DP group was significantly higher than the DC group. Tubular epithelial change was reduced in the DP group compared to the DC group. These results indicated that Phellodendri Cortex can reduce glucose level and prevent or retard the development of diabetic nephropathy in streptozotocin-induced diabetic rats.

A Switching Technique for Common Mode Voltage Reduction of PWM-Inverter System using the DSP320F240 (DSP320F240을 이용한 PWM-Inverter구동 시스템에서의 전도노이즈 저감을 위한 스위칭 기법)

  • Park Hyun Seok;Park Kyu Hyun;Kim Lee Hun;Han Sung Yong;Won Chung Yuen;Kim Young Real
    • Proceedings of the KIPE Conference
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    • 2002.07a
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    • pp.355-359
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    • 2002
  • Much attention has been given to EMI effects created in variable speed ac drive system. Zero switching states of inverter control invoke large common mode voltage. This paper focuses on the switching techniques to mitigate common mode voltage. This paper proposes a common-mode voltage reduction method based on sinusoidal pulse width modulation in three phase PWM inverter system. By using three carriers wave displaced by 120 degrees, it is possible to eliminate a common mode voltage pulse In one control period. Simulation and experimental results show that common mode voltages In the proposed technique are reduced more than conventional technique.

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