• 융합신호처리학회논문지
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• 제6권3호
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• pp.148-156
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• 2005

본 논문은 혼합 $H_2/H_{\infty}$ 제어를 이용한 강인한 서보시스템의 설계법을 제안하고 이것을 3관성 벤치마크문제에 적용하여 이 방법의 유용성을 확인한다. 먼저 내부모델의 원리를 이용하여 혼합 $H_2/H_{\infty}$ 제어기법을 적용할 수 있는 구조를 제안하고 이 구조의 타당성을 검토한다. 다음에 강인한 서보시스템의 설계조건을 각각 $H_2$ 및 $H_{\infty}$의 설계사양으로 분리한 뒤 제안된 혼합 $H_2/H_{\infty}$ 설계법에 적용하여 설계를 LMI이론에 의하여 실행한다. 마지막으로 3관성벤치마크 문제에서 부가된 몇 가지의 사양을 제안된 혼합 $H_2/H_{\infty}$법에 맞도록 수정한 뒤 제어기의 설계를 통한 설계사양의 만족도를 확인한다.

• International Journal of Control, Automation, and Systems
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• 제4권5호
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• pp.653-659
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• 2006

The design of $H_2$-optimal control with regional pole assignment via state feedback in linear time-invariant systems is investigated. The aim is to find a state feedback controller such that the closed-loop system has the desired eigenvalues lying in some desired stable regions and attenuates the disturbance between the output vector and the disturbance vector. Based on a proposed result of parametric eigenstructure assignment via state feedback in linear systems, the considered $H_2$-optimal control problem is changed into a minimization problem with certain constraints, and a simple and effective algorithm is proposed for this considered problem. A numerical example and its simulation results show the simplicity and effectiveness of this proposed algorithm.

• 조명전기설비학회논문지
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• 제17권4호
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• pp.36-44
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• 2003

전동기와 부하가 강성이 작은 축으로 연결되는 산업용 전동기 구동시스템에 있어서 전동기의 관성과 부하의 관성에 의해 축에 비틀림 진동이 발생한다. 이러한 문제를 해결하기 위하여 기존에 2자유도 H$_{\infty}$제어기가 제안되었다. 그러나 이 제어기는 구현하는데 어려움이 있다. 본 논문에서는 부분적인 상태궤환과 공진비제어를 이용한 2관성계의 H$_{\infty}$제어가 제안되었다. 제안된 제어기는 간단하면서도 외란 및 진동억제 성능을 만족한다.어기는 간단하면서도 외란 및 진동억제 성능을 만족한다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.1509-1512
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• 1996

This paper presents an intelligent autopilot for STT missiles with multiple controllers. The mixed H$_{2}$/H$_{\infty}$ control technique is applied for each controller and implemented by using the genetic searching algorithm. To facilitate automatic switching of multiple controllers under different operating conditions, an error based switching scheme is also combined with the multiple controllers at the higher level, which constitutes a hierarchical intelligent control system. It is shown via computer simulation that the proposed autopilot outperforms the conventional one..

• 융합신호처리학회 학술대회논문집
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• 한국신호처리시스템학회 2000년도 하계종합학술대회논문집
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• pp.133-136
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• 2000

The objective of this paper is to present a method for designing robust positioning control systems of a flexible arm using $H_2/H_{\infty}$ and $\mu$ theory. We begin with a description of the flexible arm based on the model identification method and discuss the derivation of the model uncertainty. The validity of the obtained model is confirmed experimentally Next, a robust controller is designed based on the $H_2/H_{\infty}$ and $\mu$ theory by which we can improve robustness of the entire system. On this occasion, we also propose a general plant formation suitable to $H_2/H_{\infty}$ control. Finally, the effectiveness of the proposed design method is verified through experimentation.

• Journal of Microbiology and Biotechnology
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• 제19권11호
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• pp.1355-1363
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• 2009

In the present study, the neuroprotective effects of astaxanthin on $H_2O_2$-mediated apoptotic cell death, using cultured mouse neural progenitor cells (mNPCs), were investigated. To cause apoptotic cell death, mNPCs were pretreated with astaxanthin for 8 h and followed by treatment of 0.3 mM $H_2O_2$. Pretreatment of mNPCs with astaxanthin significantly inhibited $H_2O_2$-mediated apoptosis and induced cell growth in a dose-dependent manner. In Western blot analysis, astaxanthin-pretreated cells showed the activation of p-Akt, p-MEK, p-ERK, and Bcl-2, and the reduction of p-P38, p-SAPK/JNK, Bax, p-GSK3b, cytochrome c, caspase-3, and PARP. Because $H_2O_2$ triggers caspases activation, this study examined whether astaxanthin can inhibit caspases activation in $H_2O_2$-treated mNPCs. After $H_2O_2$ treatment, caspases activities were prominently increased, but astaxanthin pretreatment significantly inhibited $H_2O_2$-mediated caspases activation. Astaxanthin pretreatment also significantly recovered the ATP production ability of $H_2O_2$-treated cells. These findings indicate that astaxanthin inhibits $H_2O_2$-mediated apoptotic features in mNPCs. Inhibition assays with SB203580 ($10\;{\mu}M$, a specific inhibitor of p38) and PD98059 ($10\;{\mu}M$, a specific inhibitor of MEK) clearly showed that astaxanthin can inhibit $H_2O_2$-mediated apoptotic death via modulation of p38 and MEK signaling pathways.

• 동력기계공학회지
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• 제2권2호
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• pp.67-72
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• 1998

To improve control performance, especially positioning speed, of a pneumatic positioning system, dynamic characteristics of a control valve should be considered. In case we design controller including dynamic characteristics of a control valve, it's not easy to design controller gain using simple state feedback because degree of a control system is increased. This study designed controller using loop shaping of $H_{\infty}$ control theory for a model composed of a pneumatic actuator and a control valve, and positioning experiment using this controller was performed. As a result, it was verified that the controller is useful for high speed positioning of a pneumatic positioning system.

• 한국발생생물학회지:발생과생식
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• 제21권2호
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• pp.151-156
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• 2017

High-fructose corn syrup (HFCS) is widely used as sweetener, and its overconsumption is become a major health problem. In the present study, we used adult female rats and applied a 28 days HFCS feeding model to monitor the estrous cycle and changes in tissue weights and histology. Adult female rats were divided into three groups. Animals were fed with ad libitum normal chow and (1) 24 hours tap water (Control group), (2) 12 hours HFCS access during dark period and 12 hours tap water (12H group), and (3) 24 hours HFCS only access (24H group). Total exposure period was 28 days. There is no significant change in body weight between control and HFCS-fed animals. Both absolute and relative weights of ovary in 24H animals were significantly heavier than those in control or 12H animals. The absolute and relative weights of the kidney and liver in 24H groups were significantly heavier than those in control or 12H animals. The estrous cycles of the 24H animals were significantly longer. Histological analyses revealed that 24H ovaries were relatively bigger and possessed more corpus lutea than control ovaries. Uterine sections of 12H and 24H animals showed a well-developed stratum vasculare between inner and outer myometrial layers. The number of endometrial glands were decreased in 12H uteri, and recovered in 24H uteri compared to control. Numbers of convoluted tubule in distal region increased in 12H and 24H kidney samples. Liver specimens of 12H and 24H showed the increased number of fat containing vacuoles. In conclusion, our study demonstrated that HFCS treatment for 28 days could induce (1) changes in length of estrous cycle with extended estrous and diestrous stages, (2) altered ovarian and uterine histology, and (3) liver and renal lipid accumulation. These findings reveal the adverse effects of HFCS drinking on the reproductive function and lipid metabolism of female rats.

• BMB Reports
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• 제35권6호
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• pp.547-552
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• 2002

The aim of our study was to investigate the protective effects of intraperitoneally-administrated vitamin E, dl-alpha lipoic acid, and linalool on the level of total lipid and fatty acid in guinea pig brains with oxidative stress that was induced by $H_2O_2$. The total brain lipid content in the $H_2O_2$ group decreased when compared to the $H_2O_2$ + vitamin E (p<0.05), $H_2O_2$ + linalool (p<0.05), ALA (p<0.05), control (p<0.01), linalool (p<0.01), and vitamin E (p<0.01) groups. While the proportion of total saturated fatty acid (${\Sigma}SFA$) in the $H_2O_2$ group significantly increased (p<0.005) when compared to the vitamin E group, it only slightly increased (p<0.01) when compared to the control and $H_2O_2$ + vitamin E groups. The ratio of the total unsaturated fatty acid (${\Sigma}USFA$) in the $H_2O_2$ groups was lower (p<0.05) than the control, vitamin E, and $H_2O_2$ + vitamin E groups. The level of the total polyunsaturated fatty acid (${\Sigma}PUEA$) in the $H_2O_2$ group decreased in when compared to the control, vitamin E, and $H_2O_2$ + vitamin E groups. While the proportion of the total w3 (omega 3), w6 (omega 6), and PUFA were found to be lowest in the $H_2O_2$ group, they were slightly increased (p<0.05) in the lipoic acid group when compared to the control and $H_2O_2$ + lipoic acid groups. However, the level of ${\Sigma}SFA$ in the $H_2O_2$ group was highest; the level of ${\Sigma}USFA$ in same group was lowest. As the proportion of ${\Sigma}USFA$ and ${\Sigma}PUFA$ were found to be highest in the linalool group, they were decreased in the $H_2O_2$ group when compared to the control group. Our results show that linalool has antioxidant properties, much the same as vitamin E and lipoic acid, to prevent lipid peroxidation. Additionally, vitamin E, lipoic acid, and linalool could lead to therapeutic approaches for limiting damage from oxidation reaction in unsaturated fatty acids, as well as for complementing existing therapy for the treatment of complications of oxidative damage.

• 상하수도학회지
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• 제20권2호
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• pp.215-223
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• 2006

The internal corrosion of water distribution systems is the main cause for the problem of the public health threat as well as water leakage in the damaged pipeline, red water, and odor and taste of the tap water. This study was examined the effect of chemicals used for pH and alkalinity control and corrosion inhibitors for producing the optimal corrosion control method. Corrosion study at different pH and alkalinity indicated that these control using alkaline chemicals was effective in corrosion rate, Fe release reduction, but examined to be increased in turbidity and corrosion-by-products(TTHMs) problems. The turbidity was slightly increased, requiring caution in controlling corrosion with $Ca(OH)_2$. At pH 9.0, TTHMs concentration is increased two times corn pared with non-control of pH. Using the pipe which had experienced 28 years of exposure, iron release was decreased with the corrosion inhibitor. Consequently, pH, Alkalinity control method using alkaline chemicals must be complemented by corrosion inhibitor application for efficient corrosion control.