• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.993-1000
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• 2009

In general, a drilled shaft embedded in weathered rock has a large load bearing capacity. Therefore, most of the load tests are performed only up to the load level that confirms the pile design load capacity, and stopped much before the failure load of the pile is attained. If a reliable failure load value can be extracted from the premature load test data, it will be possible to greatly improve economic efficiency as well as pile design quality. The main purpose of this study is to propose a standard for judging the reliability of the failure load of piles that is obtained from extrapolated load test data. To this aim, eleven static load test data of load-displacement curves were obtained from testing of piles to their failures from 3 different field sites. For each load-displacement curve, loading was assumed as 25%, 50%, 60%, 70%, 80%, and 90% of the actual pile bearing capacity. The limited known data were then extrapolated using the hyperbolic function, and the failure load was re-determined for each extrapolated data by the ASCE 20-96 method (1997). Statistical analysis was performed on the reliability of the re-evaluated failure loads. The results showed that if the ratio of the maximum-available displacement to the failure-load displacement exceeds 0.6, the extrapolated failure load may be regarded as reliable, having less than a conservative 20% error on average. The applicability of the proposed standard of judgment was also verified with static load test data of driven piles.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.7
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• pp.1531-1539
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• 2014

Premature ventricular contraction(PVC) is the most common disease among arrhythmia and it may cause serious situations such as ventricular fibrillation and ventricular tachycardia. Nevertheless personalized difference of ECG signal exist, performance degradation occurs because of carrying out diagnosis by general classification rule. In other words, the design of algorithm that exactly detects abnormal signal and classifies PVC by analyzing the persons's physical condition and/or environment and variable QRS pattern is needed. Thus, PVC classification by personalized abnormal signal detection and QRS pattern variability is presented in this paper. For this purpose, we detected R wave through the preprocessing method and subtractive operation method and selected abnormal signal sets. Also, we classified PVC in realtime through QS interval and R wave amplitude. The performance of abnormal beat detection and PVC classification is evaluated by using MIT-BIH arrhythmia database. The achieved scores indicate the average of 98.33% in abnormal beat classification error and 94.46% in PVC classification.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.2
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• pp.391-398
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• 2009

In this study, we introduce the design methodology of an optimized fuzzy cascade controller with the aid of hierarchical fair competition-based genetic algorithm(HFCGA) for ball & beam system. The ball & beam system consists of servo motor, beam and ball, and remains mutually connected in line in itself. The ball & beam system determines the position of ball through the control of a servo motor. The displacement change the position of ball leads to the change of the angle of the beam which determines the position angle of a servo motor. Consequently the displacement change of the position of the moving ball and its ensuing change of the angle of the beam results in the change of the position angle of a servo motor. We introduce the fuzzy cascade controller scheme which consists of the outer(1st) controller and the inner(2nd) controller as two cascaded fuzzy controllers, and auto-tune the control parameters(scaling factors) of each fuzzy controller using HFCGA. The inner controller controls the position of lever arm which corresponds to the position angle of a servo motor and the outer controller decides the set-point value of the inner controller. HFCGA is a kind of parallel genetic algorithms(PGAs), and helps alleviate the premature convergence being generated in conventional genetic algorithms (GAs). For a detailed comparative analysis from the viewpoint of the performance results and the design methodology, the proposed method for the ball & beam system which is realized by the fuzzy cascade controller based on HFCGA, is presented in comparison with the conventional PD cascade controller based on serial genetic algorithms.

• Korean Journal of Agricultural Science
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• v.39 no.4
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• pp.467-471
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• 2012

In this study, we investigated the antioxidative and antiaging activity of Perilla frutescens using LLC-$PK_1$ porcine renal epithelial cell and WI-38 human diploid fibroblast cell. The extract from Perilla frutescens showed strong protective effect against nitric oxide (NO) and superoxide ($O_2{^-}$)-induced oxidative stress generated by sodium nitroprusside (SNP) and pyrogallol, respectively. The result showed that P. frutescens increased the cell viability and showed scavenging activity of NO and $O_2{^-}$. In addition, the extract of P. frutescens exerted the protective effect against peroxynitrite ($ONOO^-$) induced by 3-morpholinosydnonimine. It suggests that P. frutescens would have the protective role against $ONOO^-$ itself and its precursors, NO and $O_2{^-}$. Furthermore, the aging model of hydrogen peroxide ($H_2O_2$)-treated WI-38 human diploid fibroblast was employed to investigate the anti-aging effect of P. frutescens. $H_2O_2$-treated WI-38 cells showed the loss of cell viability, however before-treatment with P. frutescens to WI-38 cells under premature senescence could delay the cellular aging process. The present study suggests the antioxidative and antiaging potential against free radical-induced oxidative damage of P. frutescens.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.19 no.1 s.71
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• pp.27-37
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• 2006

A Metropolis genetic algorithm (MGA) is developed and applied for the structural design optimization. In MGA, favorable features of Metropolis criterion of simulated annealing (SA) are incorporated in the reproduction operations of simple genetic algorithm (SGA). This way, the MGA maintains the wide varieties of individuals and preserves the potential genetic information of early generations. Consequently, the proposed MGA alleviates the disadvantages of premature convergence to a local optimum in SGA and time consuming computation for the precise global optimum in SA. Performances and applicability of MGA are compared with those of conventional algorithms such as Holland's SGA, Krishnakumar's micro GA, and Kirkpatrick's SA. Typical numerical examples are used to evaluate the computational performances, the favorable features and applicability of MGA. The effects of population sizes and maximum generations are also evaluated for the performance reliability and robustness of MGA. From the theoretical evaluation and numerical experience, it is concluded that the proposed MGA Is a reliable and efficient tool for structural design optimization.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.21 no.5
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• pp.483-491
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• 2008

The effectiveness of a new fiber-steel composite plate designed specifically to be used for strengthening of reinforced concrete members has been investigated. Twelve reinforced concrete beams were tested. Seven of the beams were strengthened with carbon fiber-steel composite plate(CSP), four of the beams were strengthened with glass fiber-steel composite plate(GSP), and one beam was used as a control specimen. The experimental results showed that new strengthening system controls the premature debonding and provides a more ductile failure mode than other conventional strengthening systems. The observed ductility ratios were $3.01\sim3.81$ and $3.55\sim4.95$ for strengthened beam with CSP and GSP, respectively. The maximum load was increased by 115% and 107% for strengthened beam with CSP and GSP, respectively, comparing with control beam. In addition, experimental and analytical results were well agreed.

• Journal of the Earthquake Engineering Society of Korea
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• v.8 no.3
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• pp.87-96
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• 2004

Recent test results on reduced beam section (RBS) steel moment connections showed that specimens with a bolted web tended to perform poorly due to premature brittle fracture of the beam flange at the weld access hole. The measured strain data appeared to imply that a higher incidence of base metal fracture in bolted-web specimens is related to, at least in part, the increased demand on the beam flanges due to the web bolt slippage and the actual load transfer mechanism which is completely different from that usually assumed in connection design. In this paper, the practice of providing web bolts uniformly along the beam depth was brought into question. A new seismic design procedure, which is more consistent with the actual load path identified from the analytical and experimental studies, was proposed together with improved connection details.

• Clinical and Experimental Reproductive Medicine
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• v.41 no.1
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• pp.29-32
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• 2014

Objective: To investigate the causes of amenorrhea in Korean women. Methods: Medical records from 1,212 women with amenorrhea who visited the Department of Obstetrics and Gynecology, Asan Medical Center, between January 1989 and December 2011 were retrospectively reviewed. Amenorrhea was categorized as either primary or secondary. Results: Primary amenorrhea was identified in 132 of the patients (10.9%) and secondary amenorrhea in 1,080 (89.1%). The most frequent causes of primary amenorrhea were gonadal dysgenesis (28.0%, 37/132); Mayer-Rokitansky-K$\ddot{u}$ster-Hauser syndrome (20.0%, 27/132); and constitutional delay and androgen insensitivity syndrome (8.3%, 11/132; 8.3%, 11/132, respectively). Secondary amenorrhea was due to polycystic ovary syndrome (48.4%, 523/1,080); premature ovarian insufficiency (14.0%, 151/1,080); and nutrition-related hypogonadotropic hypogonadism (8.3%, 90/1,080). Conclusion: In this retrospective study, gonadal dysgenesis was the most common cause of primary amenorrhea and polycystic ovary syndrome was the most common cause of secondary amenorrhea in Korean women.

• STI Policy Review
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• v.7 no.2
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• pp.60-84
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• 2016

What impact does the sharing economy have on existing businesses? This paper empirically examines how Uber transformed the taxi industry in New York City. Using a regression model controlling various potential influencing factors, we find no direct evidence that daily trips or revenue per taxi driver decreased since Uber entered the taxi industry. However, a closer investigation into other dimensions of taxi trips reveals that taxi drivers were forced to change their way of doing businesses to retain existing daily trips and revenue. Since Uber crowded out yellow taxis from the central area of Manhattan, yellow taxis responded by serving customers outside of the Manhattan borough. From enlarging their geographical coverage and serving customers that were previously ignored, yellow taxis were able to retain their previous level of taxi trips and market share. We also find that yellow taxis responded by improving their service quality to better serve customers' needs. Our result suggests that incumbents actively responded to Uber's entry and provided substantial benefit to consumers. Combined with the incumbent's response, the sharing economy transformed the existing market in a welfare-enhancing way. This paper provides managerial and policy implication on how incumbents affected by the disruptions of the sharing economy should respond. Even though it might be yet premature to examine the impact of Uber, results suggest that incumbents have effectively defended against Uber's entry so far. We conclude that the sharing economy and the existing economy can create positive value in our society through well-intentioned competition, complementing each other's weaknesses and strengths.

• Journal of the Korea Society of Computer and Information
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• v.10 no.4 s.36
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• pp.165-171
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• 2005

High speed computer, large scale storage device and high speed computer network are computing infrastructure which we can easily access to in these days. However, many computer simulations in natural or applied science such as molecular simulation require more computing power as well as larger scale of storage. Grid computing which is a next generation of distributed computing environment, is one of solution for the new requirements. Even though many researches have been going on Grid computing, those are oriented to communication interface and protocols, and middleware like globus tool kits[2, 3]. Therefore research on application level platform or application itself is yet premature and it makes real users be difficult to utilize Grid system for their research. In this paper, we suggest a new user environment and an abstract job model for simulation experiments on MGrid(Molecular Simulation Grid). It will make users be able to utilize Grid resources efficiently and reliably.