• Journal of the Korean Society for Precision Engineering
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• v.23 no.4 s.181
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• pp.75-82
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• 2006

In this paper, we propose an optimal trajectory for biped robots to move up-and-down stairs using a genetic algorithm and a computed-torque control for biped robots to be dynamically stable. First, a Real-Coded Genetic Algorithm (RCGA) which of operators are composed of reproduction, crossover and mutation is used to minimize the total energy. Constraints are divided into equalities and inequalities: Equality constraints consist of a position condition at the start and end of a step period and repeatability conditions related to each joint angle and angular velocity. Inequality constraints include collision avoidance conditions of a swing leg at the face and edge of a stair, knee joint conditions with respect to the avoidance of the kinematic singularity, and the zero moment point condition with respect to the stability into the going direction. In order to approximate a gait, each joint angle trajectory is defined as a 4-th order polynomial of which coefficients are chromosomes. The effectiveness of the proposed optimal trajectory is shown in computer simulations with a 6-dof biped robot that consists of seven links in the sagittal plane. The trajectory is more efficient than that generated by the modified GCIPM. And various trajectories generated by the proposed GA method are analyzed in a viewpoint of the consumption energy: walking on even ground, ascending stairs, and descending stairs.

• IEMEK Journal of Embedded Systems and Applications
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• v.10 no.5
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• pp.325-333
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• 2015

Vision based night-time vehicle detection has been an emerging research field in various advanced driver assistance systems(ADAS) and automotive vehicle as well as automatic head-lamp control. In this paper, we propose night-time vehicle detection method based on multi-class support vector machine(SVM) that consists of thresholding, labeling, feature extraction, and multi-class SVM. Vehicle light candidate blobs are extracted by local mean based thresholding following by labeling process. Seven geometric and stochastic features are extracted from each candidate through the feature extraction step. Each candidate blob is classified into vehicle light or not by multi-class SVM. Four different multi-class SVM including one-against-all(OAA), one-against-one(OAO), top-down tree structured and bottom-up tree structured SVM classifiers are implemented and evaluated in terms of vehicle detection performances. Through the simulations tested on road video sequences, we prove that top-down tree structured and bottom-up tree structured SVM have relatively better performances than the others.

• Clinical and Experimental Reproductive Medicine
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• v.29 no.4
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• pp.251-258
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• 2002

Objective : The aim of this study was to evaluate the outcomes of the GnRH antagonist (Cetrotide) minimal stimulation protocol comparing with GnRH agonist combined long step down stimulation protocol in PCOS patients. Materials and Method: From Apr 2001 to May 2002, 22 patients (22 cycles) were performed in controlled ovarian hyperstimulation using by GnRH antagonist and GnRH agonist for PCOS patients. GnRH antagonist (Cetrotide) combined minimal stimulation protocol was administered in 10 patients (10 cycles, Study Group) and GnRH agonist long step down stimulation protocol was administered in 12 patients (12 cycles, Control Group). We compared the pregnancy rate/cycle, total FSH (A)/cycle, Retrieved oocyte/cycle, the incidence of ovarian hyperstimulation syndrome, multiple pregnancy rate between the two groups. Student-t test were used to determine statistical significance. Statistical significance was defined as p<0.05. Results: Group of GnRH antagonist (Cetrorelix) minimal stimulation protocol produced fewer oocytes (6.4 versus 16.3 oocytes/cycle) using a lower dose of FSH (22.2 versus 36.1 Ample/cycle) and none developed OHSS and multiple pregnancy. Although the trends were in favour of the GnRH antagonist (Cetrorelix) protocol, the differences did not reach statistical significance. This was probably due to small sample size. Conclusion: The use of GnRH antagonist reduce the risk of ovarian hyperstimulation and multiple pregnancy. We suggest that GnRH antagonist might be alternative controlled ovarian hyperstimulation method, especially in PCOS patients who will be ovarian high response.

• Journal of the Korean Institute of Gas
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• v.16 no.2
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• pp.31-37
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• 2012

This paper describes to analyze the ventilation performance of a room air conditioner for indoor comfort control. An experimental apparatus consists of a test room, the room air conditioner, a tracer gas measurement system, a supply fan and a controller. Ventilation performance as a function of human occupancy is evaluated with supply ventilation air using a tracer gas technique of CO2 gas in the test room. The ventilation performance is evaluated in a step-down method based on ASTM Standard E741-83 and is found to increase with increasing supply ventilation rate. The CO2 gas concentration is decayed rapidly without human occupancy. The ventilation performance without human occupancy increases up to 55% and the ventilation performance with one person increases up to 25% at the supply air of 570 lpm comparing with a natural reduction after one hour. A modeling for ventilation performance of a room air conditioner in a test room is presented using experimental datum.

• Journal of KIISE:Information Networking
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• v.28 no.4
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• pp.611-620
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• 2001

To meet the requirements of reliable service for various applications, a Reliable Multicast Transport Protocol should be implemented over IP Multicast where currently best-effort service is provided. Among the current researches, hierarchical tree-based mechanism has been proposed and actively studied. This mechanism is known to provide high scalability as well as reliability, but needs an additional tree configuring mechanism for building an efficient logical tree in transport layer. Bottom-up approach has been used for creating such a tree. This method has benefits from parallel tree construction for receivers, while it has some drawbacks such that it does not guarantee a loop-free tree and brings heavy message overhead during tree creation process. Therefore, this paper proposes a top-down based mechanism for constructing a control tree, which can guarantee loop-freeness by step-wise mannered tree building. From experimental simulations, it shows that the proposed mechanism has less message overhead. It is recommended that the bottom-up and the proposed top-down will be selectively used in real networks, according to the requirements of the concerned multicast applications.

• Journal of Powder Materials
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• v.17 no.1
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• pp.23-28
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• 2010

HDDR treated anisotropic Nd-Fe-B powders have been widely used for the sheet motors and the sunroof motors of hybrid or electric vehicles, due to their excellent magnetic properties. Microstructural alignment of HDDR treated powders are mostly depending on the hydrogen reaction in disproportionation step, so the specific method to control hydrogenation reaction is required for improving magnetic properties. In disproportionation step, hydrogenation pressure and reaction time were controlled in the range of 0.15~1.0 atm for 15~180 min in order to control the micorstructural alignment of $Nd_2Fe_{14}B$ phase and, at the same time, to improve remanence of HDDR treated magnet powders. In this study, we could obtain a well aligned anisotropic Nd-Fe-B-Ga-Nb alloy powder having high remanence of 12 kG by reducing hydrogen pressure down to 0.3 atm in disproportionation step.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.20 no.4
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• pp.277-293
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• 2016

We develop an efficient numerical method for pricing the Derivative Linked Securities (DLS). The payoff structure of the hybrid DLS consists with a standard 2-Star step-down type ELS and the range accrual product which depends on the number of days in the coupon period that the index stay within the pre-determined range. We assume that the 2-dimensional Geometric Brownian Motion (GBM) as the model of two equities and a no-arbitrage interest model (One-factor Hull and White interest rate model) as a model for the interest rate. In this study, we employ the Monte Carlo simulation method with the Compute Unified Device Architecture (CUDA) parallel computing as the General Purpose computing on Graphic Processing Unit (GPGPU) technology for fast and efficient numerical valuation of DLS. Comparing the Monte Carlo method with single CPU computation or MPI implementation, the result of Monte Carlo simulation with CUDA parallel computing produces higher performance.

• The Korean Journal of Elementary Counseling
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• v.5 no.1
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• pp.93-118
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• 2006

The aim of this research is to find out the common emotional factors that elementary school teachers feel when they experience in teaching children with ADHD and to know their responding process through experiential analysis. Seven elementary school teachers took part in this research as co-investigators, and I led the experiential approach. The co-investigators have analyzed their emotional experiences during 4 sessions. They learnt about the method of experience analysis and discussed their emotional experiences of children with ADHD. And they found out some factors concerning their emotional experiences and had the time to discuss in odor to search for the common factors of that process. Finally the co-investigators took part in a session to examine the factors which they have all agreed in, and then I verified this result. 1 interpreted the factors found and constructed a psychological resolution process. Two main objectives and the results of this research are as follows. First, are there any common factors among teachers who experience in treating children with ADHD? This research showed that elementary school teachers get angry and irritated with ADHD children's troubles. Second, what kind of psychological process is there in teachers' experiences children with ADHD? The psychological process of teachers dealing children with ADHD could be conceptualized in 5 steps, the step of recognizing an action of children with ADHD, the step of first cognitive consideration, the step of giving meaning and cognitive appraisal, the step of experiencing emotion, and the step of dealing with emotion. Teachers seemed to experience a little bit different psychological process. According to whether they thought about children's behavior positively or negatively in the second step, they had different emotional experiences. If they had a positive thought, they could take children's nonadaptive behaviors as personal characteristics. However, if they took them negatively, they considered them impolite and disobedient. Even when the teachers experienced negative emotions, their responses were divided into two groups whether they took it positively or negatively. This research showed that if teachers could control their negative emotional experiences, they could calm down with children with ADHD and treat them positively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.1
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• pp.107-112
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• 2010

When we design the control system used Programmable Logic controller(PLC), if we program a Sequential Function Chart(SFC), It is easy to understand the sequential flow of control, to maintenance the controller and to describe a program. SFC language is programmed by a single sequence, a select sequence and a parallel sequence. In a select sequence, when the select step is error, the whole process is stopped. If the error step has no connection the whole process, the loss is down when we debugging the program without stopping the whole process. Therefore, this thesis shows the efficient method of remote control for select sequence and we confirmed its feasibility through actual example.

• The Transactions of the Korean Institute of Power Electronics
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• v.20 no.5
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• pp.395-401
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• 2015

This paper proposes a new bidirectional DC-DC converter with high efficiency. The proposed converter is composed of a flyback and a tapped-inductor boost converter to satisfy extreme operating conditions with low cost. The outputs are connected in series to achieve a high-voltage step-up. In the reverse direction, the proposed converter has an extreme step-down voltage. In this study, the proposed converter was employed with a 100 W hardware prototype. To design the controller, a small-signal transfer function of the proposed converter is derived. For PV power conditioning systems, a maximum power point tracking method is applied with perturb and observe method. To verify the operation of the bidirectional power flow, the current controller is applied. All of the controllers are employed with a digital signal processor.