• 한국환경과학회지
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• 제15권2호
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• pp.141-155
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• 2006

This study is aimed at the development of a runoff forecasting model to solve the uncertainties occurring in the process of rainfall-runoff modeling and improve the modeling accuracy of the stream runoff forecasting, The study area is the downstream of Naeseung-chun. Therefore, time-dependent data was obtained from the Wolpo water level gauging station. 11 and 2 out of total 13 flood events were selected for the training and testing set of model. The model performance was improved as the measuring time interval$(T_m)$ was smaller than the sampling time interval$(T_s)$. The Neuro-Fuzzy(NF) and TANK models can give more accurate runoff forecasts up to 4 hours ahead than the Feed Forward Multilayer Neural Network(FFNN) model in standard above the Determination coefficient$(R^2)$ 0.7.

• International Journal of Control, Automation, and Systems
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• 제2권3호
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• pp.263-278
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• 2004

This paper reviews dynamic programming (DP), surveys approximate solution methods for it, and considers their applicability to process control problems. Reinforcement Learning (RL) and Neuro-Dynamic Programming (NDP), which can be viewed as approximate DP techniques, are already established techniques for solving difficult multi-stage decision problems in the fields of operations research, computer science, and robotics. Owing to the significant disparity of problem formulations and objective, however, the algorithms and techniques available from these fields are not directly applicable to process control problems, and reformulations based on accurate understanding of these techniques are needed. We categorize the currently available approximate solution techniques fur dynamic programming and identify those most suitable for process control problems. Several open issues are also identified and discussed.

• 한국지능시스템학회논문지
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• 제4권1호
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• pp.35-49
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• 1994

It is well known that, for nominimum phase systems, a conventional linear controller of PID type or an adaptive controller of this structure shows limitation in achieving a satisfactory performance under tight specifications. In this paper, we combine a neuro-controller with a PI-controller with off-line learning capability provided by the Genetic Algorithm to propose a novel neuro-controller to control nonminimum phase systems effectively. The simulation results show that our proposed model is more efficient with faster rising time and less undershoot effect when the performances of the proposed controller and a conventional form are compared.

• Computers and Concrete
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• 제28권6호
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• pp.567-583
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• 2021

The use of waste materials as a binder or aggregate in the concrete mixture is a great step towards sustainability in the construction industry. Waste rubber (WR) can be used as coarse and fine aggregates in concrete and improves the crack resistance, impact resistance, and fatigue life of the produced concrete. However, the mechanical properties of rubberized concrete degrade significantly by replacing the natural aggregate with WR. To have accurate estimations of the mechanical properties of rubberized concrete, two machine learning methods consisting of artificial neural network (ANN) and neuro-fuzzy system (NFS) were served in this study. To do this, a comprehensive dataset was collected from reliable literature, and two scenarios were addressed for the selection of input variables. In the first scenario, the critical ratios of the rubberized concrete and the concrete age were considered as the input variables. In contrast, the mechanical properties of concrete without WR and the percentage of aggregate volume replaced by WR were assumed as the input variables in the second scenario. The results show that the first scenario models outperform the models proposed by the second scenario. Moreover, the developed ANN models are more reliable than the proposed NFS models in most cases.

• Journal of Korean Neurosurgical Society
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• 제63권5호
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• pp.566-578
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• 2020

Objective : Radiation is known to induce autophagy in malignant glioma cells whether it is cytocidal or cytoprotective. Dexamethasone is frequently used to reduce tumor-associated brain edema, especially during radiation therapy. The purpose of the study was to determine whether and how dexamethasone affects autophagy in irradiated malignant glioma cells and to identify possible intervening molecular pathways. Methods : We prepared p53 mutant U373 and LN229 glioma cell lines, which varied by phosphatase and tensin homolog (PTEN) mutational status and were used to make U373 stable transfected cells expressing GFP-LC3 protein. After performing cell survival assay after irradiation, the IC₅₀ radiation dose was determined. Dexamethasone dose (10 μM) was determined from the literature and added to the glioma cells 24 hours before the irradiation. The effect of adding dexamethasone was evaluated by cell survival assay or clonogenic assay and cell cycle analysis. Measurement of autophagy was visualized by western blot of LC3-I/LC3-II and quantified by the GFP-LC3 punctuated pattern under fluorescence microscopy and acridine orange staining for acidic vesicle organelles by flow cytometry. Results : Dexamethasone increased cell survival in both U373 and LN229 cells after irradiation. It interfered with autophagy after irradiation differently depending on the PTEN mutational status : the autophagy decreased in U373 (PTEN-mutated) cells but increased in LN229 (PTEN wild-type) cells. Inhibition of protein kinase B (AKT) phosphorylation after irradiation by LY294002 reversed the dexamethasone-induced decrease of autophagy and cell death in U373 cells but provoked no effect on both autophagy and cell survival in LN229 cells. After ATG5 knockdown, radiation-induced autophagy decreased and the effect of dexamethasone also diminished in both cell lines. The diminished autophagy resulted in a partial reversal of dexamethasone protection from cell death after irradiation in U373 cells; however, no significant change was observed in surviving fraction LN229 cells. Conclusion : Dexamethasone increased cell survival in p53 mutated malignant glioma cells and increased autophagy in PTEN-mutant malignant glioma cell but not in PTEN-wildtype cell. The difference of autophagy response could be mediated though the phosphatidylinositol 3-kinase/AKT/mammalian target of rapamycin signaling pathway.

• 한국산림과학회지
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• 제104권2호
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• pp.277-284
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• 2015

본 연구는 산림치유가 청소년 인터넷 중독 위험군의 신경인지, 심리사회, 생리적 측면에 어떤 영향을 주는지 알아보고자 진행되었다. 이를 위해 2013년 5월부터 7월까지 서울시 지역사회 및 상담센터, 병원에 왕래하는 청소년들을 대상으로 한국형 인터넷 중독 자가진단척도를 실시하였고, 본 척도의 기준에 따라 고위험 사용자군, 잠재적 위험 사용자군, 일반 사용자군으로 분류하였다. 이후 고위험 사용자군과 잠재적 위험 사용자군을 인터넷 중독 위험군으로 정의하였고, 본 연구의 대상자로 포함하였다. 산림치유캠프 참여와 대조군 검사는 서면으로 본인과 부모의 동의 및 참여의사를 밝힌 총 25명으로 진행되었으며, 무작위 배정을 통해 산림치유캠프 참여 13명, 대조군 검사 12명으로 분류하였다. 이들을 대상으로 신경인지적 측면은 Continuous Performance Task(CPT), 심리사회적 측면은 Kimberly S. Young Scale(KYS), Connor-Davidson Resilience Scale(RSC), Relationship Change Scale(RCS), 생리학적 측면은 Heart Rate Variability(HRV)와 Cortisol 검사를 실시하였고, 최종적으로 산림치유는 인터넷 중독 위험군의 신경인지적, 심리사회적 측면에 영향을 주는 것을 확인할 수 있었다. 신경인지적 측면의 경우 산림치유캠프에 참여한 집단은 산림치유캠프에 참여하지 않은 집단에 비해 지속수행검사(CPT)의 주의력 결핍(AQ), 청각주의력 결핍(AAQ)에서 감소효과를, 청각조심성(AP)에서는 향상 효과를 보였다. 심리사회적 측면에서는 대인관계 변화척도(RCS)에서 산림치유캠프 집단이 통계적으로 유의미하게 증가되었으며, 인터넷 중독(KYS)과 회복탄력성(RSC)에서는 통계적으로 완화 및 향상되는 경향성을 보였다. 생물학적인 측면에서는 심박수(HR)의 증가를 제외하고 통계적으로 유의미한 결과는 나타나지 않았다.

• Molecules and Cells
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• 제40권7호
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• pp.495-502
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• 2017

The $5-HT_6R$ has been considered as an attractive therapeutic target in the brain due to its exclusive expression in the brain. However, the mechanistic linkage between $5-HT_6Rs$ and brain functions remains poorly understood. Here, we examined the effects of $5-HT_6R$-mediated cell morphological changes using immunocytochemistry, Western blot, and live-cell imaging assays. Our results showed that the activation of $5-HT_6Rs$ caused morphological changes and increased cell surface area in HEK293 cells expressing $5-HT_6Rs$. Treatment with 5-HT specifically increased RhoA-GTP activity without affecting other Rho family proteins, such as Rac1 and Cdc42. Furthermore, live-cell imaging in hippocampal neurons revealed that activation of $5-HT_6Rs$ using a selective agonist, ST1936, increased the density and size of dendritic protrusions along with the activation of RhoA-GTP activity and that both effects were blocked by pretreatment with a selective $5-HT_6R$ antagonist, SB258585. Taken together, our results show that $5-HT_6R$ plays an important role in the regulation of cell morphology via a RhoA-dependent pathway in mammalian cell lines and primary neurons.

• Biomolecules & Therapeutics
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• 제24권3호
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• pp.338-345
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• 2016

Neurodegenerative diseases are often associated with oxidative damage in neuronal cells. This study was conducted to investigate the neuro-protective effect of methanolic (MeOH) extract of Perilla frutescens var. japonica and its one of the major compounds, rosmarinic acid, under oxidative stress induced by hydrogen peroxide ($H_2O_2$) in C6 glial cells. Exposure of C6 glial cells to $H_2O_2$ enhanced oxidative damage as measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and thiobarbituric acid-reactive substance assays. The MeOH extract and rosmarinic acid prevented oxidative stress by increasing cell viability and inhibiting cellular lipid peroxidation. In addition, the MeOH extract and rosmarinic acid reduced $H_2O_2-indcued$ expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) at the transcriptional level. Moreover, iNOS and COX-2 protein expression was down-regulated in $H_2O_2-indcued$ C6 glial cells treated with the MeOH extract and rosmarinic acid. These findings suggest that P. frutescens var. japonica and rosmarinic acid could prevent the progression of neurodegenerative diseases through attenuation of neuronal oxidative stress.

• 동의신경정신과학회지
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• 제18권2호
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• pp.13-24
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• 2007

Objective : Recent studies indicate that the deposition of ${\beta}-amyloid$ ($A{\beta}$) is related in the pathogenesis of Alzheimer's disease (AD), but the underlying mechanism is still not clear. Method : To investigate the potential cellular functions of APP and water extract of the JangwonHwangagambang (JWHG), we use as in vitro model, neuro 2A cells were treated with either JWHG or its oriental medicines, and the effect in APP expression was determined by MTT and LDH assay. JWHG have been shown to be neuroprotective in different model systems. We asked whether JWHG treatment would influence cell survival and AD-like pathology in APP-induced neuronal cells. Result : JWHG and water extracts of some oriental medicine has attenuated high cell death in vitro. JWHG-treated cells increased percentage of cell survival more longly than controls. JWHG had significantly increas neurite outgrowth in the as compared to control cells. Conclusion : These results suggest that JWHG prevent APP-induced neurotoxicity through attenuating oxidative stress, and may be useful as potential therapeutic agents for AD.

• 한국전자통신학회논문지
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• 제5권3호
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• pp.262-268
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• 2010

본 논문은 카메라의 고정 초점방식 렌즈를 통해 얻은 영상의 왜곡을 보상하여 왜곡된 이미지 좌표에서 본래의 좌표를 갖는 원영상으로 복원하는 연구이다. 이미지 센서의 다양한 영상 기기 발달과 활용으로 다방면의 산업분야에 확대 이용되고 있으나, 카메라의 소형화와 경량화 필요로 인해 렌즈의 굴곡에 의한 수신 영상의 왜곡이 영향을 미치는 경향이 많다. 특히, 입체 영상 카메라 응용 기기인 경우 좌, 우측 렌즈의 서로 다른 왜곡으로 입체감 저하 및 좌우 이미지 왜곡 등이 수반된다. 좌, 우측 카메라 수신 영상의 각 부분별로 본래의 좌표로 환산하는 근사식을 세우고 이들을 종합하는 방식으로 접근했다. 적응 뉴로-퍼지 추론시스템을 구성하여 소속 함수를 통해 분할하고 1차 Sugeno fuzzy 모델식으로 추정하여 좌, 우측 본래의 영상에 근접한 결과를 얻었다. 이로서 저가이며 소형 렌즈를 활용한 영상으로도 정확한 입체 영상 센싱 기능과 판별을 기대할 수 있게 된다.