• Journal of Korea Water Resources Association
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• v.55 no.6
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• pp.405-419
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• 2022

Flood frequency analysis commonly used to design the hydraulic structures to minimize flood damage includes uncertainty. Therefore, the most appropriate design flood within a uncertainty should be selected in the final stage of a hydraulic structure, but related studies were rarely carried out. The total expected cost function introduced into the flood frequency analysis is a new approach for determining the optimal design flood. This procedure has been used as UNCODE (UNcertainty COmpliant DEsign), but the application has not yet been introduced in South Korea. This study introduced the mathematical procedure of UNCODE and calculated the optimal design flood using the annual maximum inflow of hydroelectric dams located in the Bukhan River system and results were compared with that of the existing flood frequency. The parameter uncertainty was considered in the total expected cost function using the Gumbel and the GEV distribution, and the Metropolis-Hastings algorithm was used to sample the parameters. In this study, cost function and damage function were assumed to be a first-order linear function. It was found that the medians of the optimal design flood for 4 Hydroelectric dams, 2 probability distributions, and 2 return periods were calculated to be somewhat larger than the design flood by the existing flood frequency analysis. In the future, it is needed to develop the practical approximated procedure to UNCODE.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.207-207
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• 2010

Both ZnO and GaN have excellent physical properties in optoelectronic devices such as blue light emitting diode (LED), blue laser diode (LD), and ultra-violet (UV) detector. The ZnO/GaN heterostructure, which has a potential to achieve the cost efficient LED technology, has been fabricated by using radio frequency (RF) sputtering, pyrolysis, metal organic chemical vapor deposition (MOCVD), direct current (DC) arc plasmatron, and pulsed laser deposition (PLD) methods. Among them, the PLD system has a benefit to control the composition ratio of the grown film from the mixture target. A 500-nm-thick ZnO film was grown by PLD technique on c-plane GaN/sapphire substrates. The post annealing process was executed at some varied temperature between from $300^{\circ}C$ to $900^{\circ}C$. The morphology and crystal structural properties obtained by using atomic force microscope (AFM) and x-ray diffraction (XRD) showed that the crystal quality of ZnO thin films can be improved as increasing the annealing temperature. We will discuss the post-treatment effect on film quality (uniformity and reliability) of ZnO/GaN heterostructures.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.271-274
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• 2005

Under competitive power markets, various long-term and short-term contracts based on spot price are used by producers and consumers. So an accurate forecasting for spot price allow market participants to develop bidding strategies in order to maximize their benefit. Artificial Neural Network is a powerful method in forecasting problem. In this paper we used Radial Basis Function(RBF) network to forecast spot price. To learn ANN, in addition to price history, we used some other effective inputs such as load level, fuel price, generation and transmission facilities situation. Results indicate that this forecasting method is accurate and useful.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.169.4-169
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• 2001

Conventional methods to solve the nonlinear programming problem range from augmented Lagrangian methods to sequential quadratic programming (SQP) methods. NPSOL, which is a SQP code, has been widely used to solve various optimization problems but is still subject to many numerical problems such as convergence to local optima, difficulties in initialization and in handling non-smooth cost functions. Recently, many evolutionary methods have been developed for constrained optimization. Among them, CEALM (Co-Evolutionary Augmented Lagrangian Method) shows excellent performance in the following aspects: global optimization capability, low sensitivity to the initial parameter guessing, and excellent constraint handling capability due to the benefit of the augmented Lagrangian function. This algorithm is ...

• Journal of Korean Society of Industrial and Systems Engineering
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• v.28 no.4
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• pp.94-101
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• 2005

This paper presents a data-mining aided heuristic algorithm development. The developed algorithm includes three steps. The steps are a uniform selection, development of feature functions and clustering, and a decision tree making. The developed algorithm is employed in designing an optimal multi-station fixture layout. The objective is to minimize the sensitivity function subject to geometric constraints. Its benefit is presented by a comparison with currently available optimization methods.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.14 no.24
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• pp.31-41
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• 1991

The producer's to tolerance concept (in contrast to the consumer's tolerence) fellows naturally from the notion of continuous loss function Emerging producer tolerance methodology has proceeded without benefit of carefully defined assumptions. We rectifg this omission and consider the process mean deviation. Then develope the models for which determine the tolerenes in cases of the-nominal-the-best, the-smaller-the-better and the-larger-the-better. Finally the numerical examples are Presented to illustrated these results and also the sensitivity analysis to apprehend the changes of loss tolerances varying with mean is presented.

• Korean Journal of Adult Nursing
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• v.24 no.4
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• pp.398-405
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• 2012

Purpose: The purpose of this study was to develop spaced retrieval training as a nursing intervention for patients having an mild alzheimer's disease and to determine the effects of the program on their memory and cognitive function across training sessions. Methods: A non-equivalent control group pre test-post test design was used in this study. Participants were recruited from a local community: 14 patients were allocated into experimental group and 12 patients were allocated into control group. The experimental group was asked to participate in spaced retrieval training over 4 weeks, with seven times a week and 1 hour a session based. The study was conducted from June 20, 2011 to July 17, 2011. Data was analyzed with descriptive statistics, $x^2$-test and t-test using the SPSS/WIN 19.0 program. Results: After spaced retrieval training, the experimental group showed significant increases in scores for memory (t=12.40, p<.001) and cognitive function (t=7.69, p<.001) in comparison to the control group. Conclusion: Spaced retrieval training was effective in increasing cognitive function and memory of patients having mild alzheimer's disease. Therefore spaced retrieval training could be benefit the mild alzheimer's disease.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.23 no.2
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• pp.49-56
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• 2012

Methylphenidate is a widely used stimulant for treatment of attention-deficit hyperactivity disorder (ADHD). In addition to core symptoms of attention and behavioral symptoms, methylphenidate is even effective for executive functions. However, abuse and misuse of stimulants, including methylphenidate, for the purpose of cognitive enhancement is an issue of concern worldwide. Some prejudices and misunderstandings against methylphenidate are popular ; however, little attention has been given to the neuropsychiatric evidence of methylphenidate for enhancement of cognitive function among healthy populations. In this article, our aim was to conduct a review of previous studies investigating the effect of methylphenidate in healthy populations. Findings from several recent studies have demonstrated the effectiveness of methylphenidate for enhancement of cognitive function in healthy populations. The mechanisms of cognitive enhancement are thought to be associated with motivation and the reward circuit in the brain. However, when considering the risk to benefit, an official discussion of the use of methylphenidate among healthy members of the population would be premature. Instead, investigation of epidemiological studies of the prevalence of misuse of stimulants among healthy members of the population, particularly adolescents and college students, is needed. In addition, based on achievements reported in previous studies, investigation of the effect of an approach using non-pharmacological enhancing motivation, which will in turn result in increased cognitive function would be helpful.

• Physical Therapy Rehabilitation Science
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• v.11 no.2
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• pp.165-171
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• 2022

Objective: Nonspecific low back pain (NSLBP) is experienced worldwide by many age groups. Yoga is recommended as an exercise to reduce back pain and stress because it is a breathing exercise, posture, and meditation as key elements. The aim of this study is to compare the effects of yoga and stabilization exercise on pain intensity, function, and depression. Design: An open-label, parallel arm, randomized controlled trial Methods: Twenty-four participants were allocated to the experimental and the control group in a ratio of 1:1. Yoga (experimental group) and stabilization exercise (control group) were received twice a week for 6 weeks Participants were assessed at baseline and post-intervention for pain intensity (numeric pain rating scale), function (Aberdeen low back pain scale, flexibility,and strength), and depression (Beck depression inventory). Results: When the experimental group (Yoga) and control group (stabilization exercise) were performed twice a week for 6 weeks, numeric pain rating scale, Aberdeen low back pain scale, and flexibility in post-intervention showed significant improvement in both groups (P<0.05), However, in all variables, the experimental group showed a positive benefit compared to the control group (P<0.05). Conclusions: The results of this study show that yoga has more positive benefits compared to stabilization exercise in pain intensity, function, and depression in individuals with NSLBP.

• Korean Journal of Biological Psychiatry
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• v.13 no.3
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• pp.191-201
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• 2006

Objectives : The purpose of this study was to investigate whether the cognitive functions would be correlated with psychotic symptoms and whether antipsychotic treatments would affect the cognitive functions after 8 weeks. Methods : The thirty-five schizophrenic patients were conducted in this study. The psychopathology was measured using PANSS. The memory function, executive function, and sustained attention were measured using Memory Assessment Scale(MAS), Wisconsin Card Sorting Test(WCST), and Vigilance(VIG) and Cognitrone(COG) in Vienna Test System. After 8 weeks of antipsychotic treatment, we retested the cognitive tests. Results : 1) The cognitive tests after the 8 week's treatment showed significant improvements in memory and executive function in the schizophrenic patients. On the other side, sustained attention did not show improvement. 2) The change of PANSS were correlated with perseverative response, perseverative error and total correct in WCST at baseline. WCST scores at baseline were correlated with negative symptoms, but not positive ones. Conclusion : These study suggests that 1) the impaired sustained attention could be a vulnerability marker in schizophrenia, 2) memory & executive function deficit could be reversible after treatment, and 3) medication might have a benefit in improving the cognitive functions in schizophrenia. Furthermore, the data supports that the better premorbid executive function was, the more favorable was the treatment response in schizophrenic patients. Finally, this study indicates that executive function might be an index of treatment improvement.