• The Transactions of the Korea Information Processing Society
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• v.4 no.9
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• pp.2366-2377
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• 1997

An Adaptive Usage Parameter Control(UPC) mechanism using a Variable Token Pool(VTP) which is kind of preventive traffic control in the Asynchronous Transfer Mode(ATM) networks is described. The VTP mechanism can monitor violations of the average bit rate and burst duration as well as peak bit rate for the ON-OFF type traffic. The VTP can vary the token pool size by monitoring burst duration and silence duration for a long term. It also improves the sensitivity against the violation of burst duration and average bit rate and enables to response for the violating traffic situation quickly. The variable token pool size is varied in step size by every burst duration and silence duration. Two important parameters for controlling token pool size are Down_size and Up_size. We compare the performance of LB and JW mechanism with the proposed VTP mechanism by computer simulations. We have known that the proposed method is more effective than the previous mechanisms. It is shown that the cell loss rate of the VTP quite depends on the value of Down_size and Up_size. The two parameters should be decided as a propr value according to traffic situations.

• Proceedings of the KIEE Conference
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• 2002.11d
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• pp.3-11
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• 2002

This paper presents the trend of low voltage and high current technology for DC-DC converters. It can be said that the output voltage of the on-board power supply has been rapidly moving forward a low voltage in proportion to the minuteness of the semiconductors. As for as its speed is concerned, the change of the market situation seems to be faster than that of R&D for the low voltage and high current products put out by power supply manufacturers. Here, the present situation and the trend of non-isolated type step-down DC-DC converter and isolated type DC-DC converter called "Brick" will be taken up mainly from the fellowing point of view. -low voltage and high current keeping up with the current demand for the latest telecommunication networks and broadband. -build-up of the total solution for dispersion system power supply. In this paper, an explanation is given to mainly concerning to the newest products in the supplier's position.

• Journal of the Semiconductor & Display Technology
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• v.19 no.4
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• pp.18-21
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• 2020

Undetected wafer slip during the lift pin-down motion in semiconductor equipment may affect the center to edge variation, wafer warpage, and pattern misalignment in plasma equipment. Direct measuring of the amount of wafer slip inside the plasma process chamber is not feasible because of the hardware space limitation inside the plasma chamber. In this paper, we demonstrated a practice for the wafer lift pin-up and down motions with respect to the gear ratio, operating voltage, and pulse width modulation to maintain accurate wafer position using remote control linear servo motor with an experimentally designed chamber mockup. We noticed that the pin moving velocity and gear ratio are the most influencing parameters to be control, and the step-wised position control algorithm showed the most suitable for the reduction of wafer slip.

• 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 Korean Biological Nursing Science
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• v.4 no.1
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• pp.5-23
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• 2002

Purpose: To determine the effect of the Fall Prevention Program(EPP) on gait, balance and muscle strength in elderly women at a nursing home. Method: The subjects of this consisted of 38 elderly women between the ages of 70 to 89 years living at a nursing home located in Seoul. Each of the experimental group and control group was composed of 19 subjects. The subjects in experimental group have participated in FPP for the 8 weeks which consisted of exercise, education and foot care. They started to exercise for 40 minutes per session, 3 sessions a week during the 1st week at 40% of age adjusted maximum heart rate. From the 2nd week to the 4th week, they increased the duration of exercise to 50 minutes per session and the intensity to 60% of age-adjusted maximum heart rate. They participated in 50 minutes at 60% of age-adjusted maximum heart rate from the 5th week to the 8th week. Each exercise session consisted of 10 minutes of warming-up exercise, 30 minutes of conditioning exercise and 10 minutes of cooling-down exercise. They participated in education for 20 minutes per week from the 1st week to the 4th week. Then they participated in a 30-minute foot care program per week from the 5th week to the 8th week. Gait, balance and muscle strength for each subject were measured before and after FPP. Gait was evaluated by step length, step width, gait speed and walking distance. Balance was measured by the duration of standing on one leg with their eyes closed and open each, and a get-up and go test. Grip strength was measured by hand dynamometer. Hip extensor and flexor strength, knee extensor and flexor strength and ankle plantarflexor and dorsiflexor strength were measured by manual muscle tester. Data was analyzed using SPSS form Windows. t-test and Chi square test were utilized as a homogeneity test. Repeated measure ANOVA was used to test the effect of FPP. Result: 1) Step width significantly decreased, and step length, gait speed and walking distance significantly increased in the experimental group compared with the control group after FPP(p<0.005). 2) There was no significant change in standing time on one leg with their eyes closed after FPP. The standing time on leg with their eyes open and the time of "get-up and go" significantly decreased in the experimental group compared with the control group after FPP(p<0.005). 3) Muscle strength-grip strength, hip extensor and flexor strength-significantly increased in the experimental group compared with the control group after FPP(p<0.005). 4) There was no significant difference of frequency of fall between the experimental group and control group during the period of FPP. Conclusion: These results suggest that FPP can increase gait, balance and muscle strength of elderly women at a nursing home.

• Reproductive and Developmental Biology
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• v.35 no.1
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• pp.77-83
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• 2011

One-step dilution and direct transfer would be a practical technique for the field application of frozen embryo. This study was to examine whether Jeju Black Cattle (JBC, Korean Cattle) can be successfully cloned from vitrified and one-tep diluted somatic cell nuclear transfer (SCNT) blastocyst after direct transfer. For vitrification, JBC-SCNT blastocysts were serially exposed in glycerol (G) and ethylene glycol (EG) mixtures [10%, (v/v) G for 5 min., 10% G plus 20% EG (v/v) for 5 min., and 25% G plus 25% EG (v/v) for 30 sec.] which is diluted in 10% FBS added D-PBS. And then SCNT blastocysts were loaded in 0.25 ml mini straw, placed in cold nitrogen vapor for 3 min. and then plunged into $LN_2$. One-step dilution in straw was done in $25^{\circ}C$ water for 1 min, by placing vertically in the state of plugged-end up and down for 0.5 min, respectively. When in vitro developmental capacity of vitrified SCNT blastocyst was examined at 48 h after one-step dilution, hatched rate (56.4%) was slightly lower than that of control group (62.5%). In field trial, when the vitrified-thawed SCNT blastocysts were transferred into uterus of synchronized 5 recipients, a cloned female JBC was delivered by natural birth on day 299 and healthy at present. In addition, when the short tandem repeat marker analysis of the cloned JBC was evaluated, microsatellite loci of 11 numbers was perfectly matched genotype with donor cell (BK94-14). This study suggested that our developed vitrification and one-step dilution technique can be applied effectively on field trial for cloned animal production, which is even no longer in existence.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.2
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• pp.305-310
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• 2012

Planetary gear box is a power transmitter having very high gear ratio in compact volume. The planetary step-down gear box converts high speed and low torque into low speed and high torque, which is widely used in constructional and industrial machinery field. And, the planetary step-up gear box does vice versa working, which is used as main gear box of large sized wind mill system. The large sized planetary gear box must be performed the normal-opposite rotation test as a its durability test for achieving the reliability. The large sized planetary gear box is composed by triple gear trains of sun gear, carrier, and ring gear. If input power is supplied into one of them and the other is fixed, and then another becomes the output part. In this paper, we designed a new test equipment which can do rapid normal and opposite rotational change with only small displacement by supplying test power using the above rotation (driving) characteristics and hydraulic cylinder and link, and also compared and analyzed with existing method through various experiments.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.2
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• pp.75-81
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• 2015

At the end of the 19th century, Edison's DC power system and Tesla's AC power system was debated in power market. Finally, AC system became the primary system of the power market because both step-up and step-down of voltage by using transformer and long-distance power transmission are easily possible. However, nowadays the power market takes some action for introducing DC system. Both domestic and foreign researchers are conducting the study on the DC system as well. Some researchers have conducted the studies on power quality and economic evaluation of the DC distribution system but DC distribution system is still controversial in terms of the effectiveness and reliability. In this paper, we calculate the reliability indices of the Low Voltage Direct Current(LVDC) distribution system considering arrangement of power electronics, layout of the distribution system, and distance between load points.

• Proceedings of the IEEK Conference
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• 2002.07b
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• pp.1121-1124
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• 2002

In this paper, an IC realization of a cell-network type SC DC-DC converter is reported. To achieve small and low-cost realization, the converter is designed by using a 1.2 $\mu\textrm{m}$ CMOS technology. The CMOS implemented converter will be useful as a building block of various mobile equipments since step-up and step-down voltages can be provided at one time. Concerning the proposed DC-DC converter, SPICE simulatiorls are performed to investigate the characteristics of the circuit. The SPICE simulations show that, the efficiency of the simulated circuit is more than 95 %. From the layout design using a CAD tool, MAGIC, the VLSI chip is fabricated in the chip fabrication program of VLSI Design and Education Center(VDEC), the University of Tokyo with the collaboration by On-Semiconductor. The proposed circuit is integrable by a standard 1.2 $\mu\textrm{m}$ CMOS technology.

• Journal of Power Electronics
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• v.15 no.2
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• pp.356-365
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• 2015

This paper presents a new single phase front-end ac-dc bridgeless power factor correction (PFC) rectifier topology. The proposed converter achieves a high efficiency over a wide range of input and output voltages, a high power factor, low line current harmonics and both step up and step down voltage conversions. This topology is based on a non-inverting buck-boost (Zeta) converter. In this approach, the input diode bridge is removed and a maximum of one diode conducts in a complete switching period. This reduces the conduction losses and the thermal stresses on the switches when compare to existing PFC topologies. Inherent power factor correction is achieved by operating the converter in the discontinuous conduction mode (DCM) which leads to a simplified control circuit. The characteristics of the proposed design, principles of operation, steady state operation analysis, and control structure are described in this paper. An experimental prototype has been built to demonstrate the feasibility of the new converter. Simulation and experimental results are provided to verify the improved power quality at the AC mains and the lower conduction losses of the converter.