• 제어로봇시스템학회논문지
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• 제20권1호
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• pp.42-47
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• 2014

This paper investigates an adaptive approximation design problem for the tracking control of output-constrained non-affine pure-feedback systems. To satisfy the desired performance without constraint violation, we employ a barrier Lyapunov function which grows to infinity whenever its argument approaches some limits. The main difficulty in dealing with pure-feedback systems considering output constraints is that the system has a non-affine appearance of the constrained variable to be used as a virtual control. To overcome this difficulty, the implicit function theorem and mean value theorem are exploited to assert the existence of the desired virtual and actual controls. The function approximation technique based on adaptive neural networks is used to estimate the desired control inputs. It is shown that all signals in the closed-loop system are uniformly ultimately bounded.

• 로봇학회논문지
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• 제17권1호
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• pp.76-85
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• 2022

One of the most fundamental challenges when designing controllers for dynamic systems is the adjustment of controller parameters. Usually the system model is used to get the initial controller, but eventually the controller parameters must be manually adjusted in the real system to achieve the best performance. To avoid this manual tuning step, data-driven methods such as machine learning were used. Recently, reinforcement learning became one alternative of this problem to be considered as an agent learns policies in large state space with trial-and-error Markov Decision Process (MDP) which is widely used in the field of robotics. However, on initial training step, as an agent tries to explore to the new state space with random action and acts directly on the controller parameters in real systems, MDP can lead the system safety-critical system failures. Therefore, the issue of 'safe exploration' became important. In this paper we meet 'safe exploration' condition with Control Barrier Function (CBF) which converts direct constraints on the state space to the implicit constraint of the control inputs. Given an initial low-performance controller, it automatically optimizes the parameters of the control law while ensuring safety by the CBF so that the agent can learn how to predict and control unknown and often stochastic environments. Simulation results on a quadrotor UAV indicate that the proposed method can safely optimize controller parameters quickly and automatically.

• 한국해안해양공학회지
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• 제16권1호
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• pp.1-9
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• 2004

본 연구에서는 원전어항에서 채용하고 있는 강제 부방파제에 비해 소요재료량의 변화가 크지 않은 범위에서 전후연직판의 위치와 형식의 변화 및 수평판의 부착 유무에 따른 여러 형식의 부방파제에 의한 투과율과 반사율을 Green 함수법으로부터 계산한 결과에 기초하여, 원전어항의 강제 부방파제보다 단주기파 및 장주기파를 보다 효과적으로 제어할 수 있는 새로운 형식의 부방파제를 검토하였다. 이로부터 연직커튼판 하부에 수평판을 부착한 형태의 부방파제가 파랑제어기능이 우수한 것으로 판명되었고, 이는 원전어항 부방파제보다 파랑제어기능이 탁월하다는 것을 알 수 있었다. 또한, 본체에 부착된 전후연직판 및 수평판의 크기와 간격을 조절함으로써 적합한 투과파를 얻을 수 있다는 것도 알 수 있었다.

• 드라이브 ㆍ 컨트롤
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• 제14권4호
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• pp.61-70
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• 2017

In this study, an extended-state-observer (ESO) based non-linear servo control is introduced for an electro-hydrostatic actuator (EHA). Almost hydraulic systems not only are highly non-linear system that has mismatched uncertainties and external disturbances, but also can not measure some states. ESO that only use an output signal can be used to compensate these uncertainties and estimate unmeasurable states. To improve the position tracking performance, the barrier Lyapunov function (BLF) that can guarantee an output tolerance is introduced for the position tracking error signal of back stepping control procedures. Finally, the proposed servo control is compared with the proportional-integral (PI) control.

• 대한한방소아과학회지
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• 제34권3호
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• pp.67-75
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• 2020

Objectives This study is conducted to evaluate Th2 skewed condition control through skin fat barrier formation from the treatment using Coptidis Rhizoma and Glycyrrhiza uralensis extract. Methods The 6-week-old NC/Nga mice were divided into 4 groups: Control group (Ctrl), lipid barrier eliminate treatment group (LBET), Coptidis Rhizoma and Glycyrrhiza uralensis feeding treatment after lipid barrier elimination group (CGFT), dexamethasone feeding treatment after lipid barrier elimination group (DxFT). After 3 days, differences in skin condition, improvement of skin fat barrier, and control of Th2 skewed condition of each group were observed. Results Pathologic skin damage and tissue changes were less in the CGFT group than in the LBET and DxFT groups, and Transepidermal water loss (TEWL) and pH were also significantly decreased (p < 0.05). The filaggrin intensity and positive response also increased significantly in the CGFT group (p < 0.05). Kallikrein-related peptidase (KLK) 7, Protease activated receptor (PAR)-2, Thymic stromal lymphopoietin (TSLP), Interleukin (IL)-4, and the products of the Th2 differentiation process also showed a significant decrease compared to the LBET and DxFT groups (all p < 0.05). Conclusions The Coptidis Rhizoma and Glycyrrhiza uralensis extract causes skin barrier recovery and function recovery through the formation of skin fat barrier. This leads to the conclusion that Coptidis Rhizoma and Glycyrrhiza uralensis extract can control Th2 differentiation through the formation of skin fat barrier.

• 대한한의학회지
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• 제28권4호
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• pp.18-26
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• 2007

Objective : To study the effect of the Insamyangyoung-tang(ISYT) extract on the skin barrier function, the skin pH, skin humidity and transepidermal water loss(TEWL) were measured and histological changes were observed in DNCB(2,4-dinitrochloro-benzen)-induced contact dermatitis(CD) hairless mice. Methods : The male hairless mice were divided into three groups. Each group consisted of 15 mice. The normal group which had acetone- olive oil applied. The control group which had intentionally induced CD by DNCB and it was fed normal saline orally. The ISYT group which had intentionally induced CD by DNCB and it was fed ISYT extract orally for 7 days. The three groups were checked 24h, 48h and 72h later after inducing CD, and the skin pH, skin humidity and TEWL were observed. Tissue samples were taken, and damage to the epithelial cell was observed. Statistical analysis was performed by using one way-ANOVA: significance was set at p values less than 5% (p<0.05). Results : ISYTextract efficiently maintained the pH balance, it kept the skin humidity at a normal level, and it inhibited TEWL of the DNCB-induced CD hairless mouse. The damage to the epithelium was decreased and the regeneration power of the skin was increased in the ISYT group. Conclusion : Insamyangyoung-tang has a good effect on the skin barrier function of DNCB induced contact dermatitis hairless mice.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 추계학술대회 논문집
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• pp.115-119
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• 2011

Instead of very expensive sound record and professional measurement microphones the low cost Surface Mounted Device (SMD) microphones are proposed for practical barrier ANC system. FRF of the microphones and theirs sensitivity to the wind interferences are evaluated in semi anechoic chamber. The improvement of feedforward algorithm noise reduction index was evaluated based on measured coherence function between tested SMD and reference microphone. Test was performed at various wind speed from 1 m/s to 5 m/s.

• Asian-Australasian Journal of Animal Sciences
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• 제16권4호
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• pp.596-608
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• 2003

Weaning is a complex phase when the mammal suffers the action of different stressors that contribute to negatively affect the efficiency of the intestinal mucosa and of the whole local integrated system, that acts as barrier against any nocuous agent. The components of this barrier are mechanical, chemical, and bacteriological; immunological and not. The development of contact with a saprophyte microflora and the maintenance of feed intake after the interruption of motherly nutrition are essential for the maturation of an equilibrated local immune function and for a functional integrity of villi. Opportunities and limits of some dietary strategies that can contribute to reduce negative effects of weaning on health and performance are discussed. Knowledges on the possible mechanism of action of probiotics are upgraded, particularly for their supposed role in the balance between different immune functions (effectory/regulatory). Some tools to control pathogen microflora are reviewed (acids, herbs, immunoglobulin sources) and practical feeding systems are proposed.

• 대한한의학회지
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• 제29권1호
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• pp.117-133
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• 2008

Objectives : Since ancient times, Koreans have applied medicinal spabaths for treatment of various diseases. The objective of this study was to investigate the effect of strontium, one of the common ingredients of such baths, experimentally on acute skin barrier damage. Materials and Methods : Male hairless mice, average weight 20g, were divided into six groups. Each group consisted of five mice. The first was the normal, non-treated group. The second was the control group with acute skin barrier damage intentionally induced by TS. The third was the Ba-Sr1 group bathed in 1mg/L strontium chloride before and after inducing acute skin barrier damage by TS. The fourth was the Ba-Sr7 group bathed in 7mg/L strontium chloride before and after inducing acute skin barrier damage by TS. The fifth was the Sr1 group bathed in 1mg/L of strontium chloride only after intentionally inducing acute skin barrier damage by TS. The sixth was the Sr7 group bathed in 7mg/L of strontium chloride only after intentionally inducing acute skin barrier damage by TS. External changes of skin, skin erythema level, transepidermal water loss level, and GOT and GPT level of each group were checked immediately before and after TS, 3 hrs, 5 hrs and 24 hrs after inducing acute skin barrier damage. Then, tissue samples were made and examined for damage to epithelial cells, stratum corneum, change of mucous polysaccharide in dermis and amount of mast cells. Statistical analysis was performed by one way-ANOVA, Scheffe and Duncan for a post hoc test and pairwise comparison for comparing for difference between each time. Statistical significance was achieved if the probability was less than 5% (p<0.05) Results : 1. From skin erythema and TEWL level indicating the function of the skin barrier, we can know that it is helpful to the skin barrier to bathe in a water solution including a low concentration of strontium. 2. In the control group with acute skin barrier damage induced by TS, skin barrier damage persisted until 3-5 hrs and recovered after 5-24 hrs. Differently from the control group, in the case of taking a bath in a water solution including strontium, skin barrier damage recovered after only 3-5 hrs. Therefore, the bath with a water solution including strontium can promote recovery of the skin barrier. 3. Bathing in water solution including a higher concentration of strontium was more beneficial to recovery of skin barrier damage. 4. There was no influence on serum GOT and GPT from bathing in a water solution including strontium. Conclusions : The strontium was effective for recovery and mitigation of acute skin barrier damage induced by tape stripping. I suggest that strontium (Sr) can be used as an external treatment medicine, addedinto bath water to treat acute skin barrier damage.

• Biomolecules & Therapeutics
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• 제29권2호
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• pp.175-183
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• 2021

The mitogen-activated protein kinase (MAPK) pathway controls intestinal epithelial barrier permeability by regulating tight junctions (TJs) and epithelial cells damage. Heme oxygenase-1 (HO-1) and carbon monoxide (CO) protect the intestinal epithelial barrier function, but the molecular mechanism is not yet clarified. MAPK activation and barrier permeability were studied using monolayers of Caco-2 cells treated with tissue necrosis factor α (TNF-α) transfected with FUGW-HO-1 or pLKO.1-sh-HO-1 plasmid. Intestinal mucosal barrier permeability and MAPK activation were also investigated using carbon tetrachloride (CCl4) administration with CoPP (a HO-1 inducer), ZnPP (a HO-1 inhibitor), CO releasing molecule 2 (CORM-2), or inactived-CORM-2-treated wild-type mice and mice with HO-1 deficiency in intestinal epithelial cells. TNF-α increased epithelial TJ disruption and cleaved caspase-3 expression, induced ERK, p38, and JNK phosphorylation. In addition, HO-1 blocked TNF-α-induced increase in epithelial TJs disruption, cleaved caspase-3 expression, as well as ERK, p38, and JNK phosphorylation in an HO-1-dependent manner. CoPP and CORM-2 directly ameliorated intestinal mucosal injury, attenuated TJ disruption and cleaved caspase-3 expression, and inhibited epithelial ERK, p38, and JNK phosphorylation after chronic CCl4 injection. Conversely, ZnPP completely reversed these effects. Furthermore, mice with intestinal epithelial HO-1 deficient exhibited a robust increase in mucosal TJs disruption, cleaved caspase-3 expression, and MAPKs activation as compared to the control group mice. These data demonstrated that HO-1-dependent MAPK signaling inhibition preserves the intestinal mucosal barrier integrity by abrogating TJ dysregulation and epithelial cell damage. The differential targeting of gut HO-1-MAPK axis leads to improved intestinal disease therapy.