• Journal of Power Electronics
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• v.10 no.1
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• pp.27-33
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• 2010

This paper presents a bidirectional DC-DC converter suitable for low-voltage super capacitor-based electric energy storage systems. The DC-DC converter presented here consists of a full-bridge circuit and a current-fed push-pull circuit with a high frequency (HF) transformer-link. In order to reduce the device-conduction losses due to the large current of the super capacitor as well as unnecessary ringing, synchronous rectification is employed in the super capacitor-charging mode. A wide range of voltage regulation between the battery and the super capacitor can be realized by employing a Phase-Shifting (PS) Pulse Width Modulation (PWM) scheme in the full-bridge circuit for the super capacitor charging mode as well as the overlapping PWM scheme of the gate signals to the active power devices in the push-pull circuit for the super capacitor discharging mode. Essential performance of the bidirectional DC-DC converter is demonstrated with simulation and experiment results, and the practical effectiveness of the DC-DC converter is discussed.

• International Journal of Railway
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• v.3 no.1
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• pp.1-6
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• 2010

The steel plate-girder bridges with concrete gravity piers have possibilities of overturning by lateral inertial force which can be reproduced by sudden earthquake attack. This paper explores an overturning mechanism of existing concrete gravity pier onto the sandy soil in the event of lateral push-over load by in-situ experimental observation. The in-situ push-over experiment for pier with earth anchors between spread footing and rock beds exhibits a reasonable enhancement of ductility against overturning. In unanchored system, a flexural crack at cold joint of concrete pier is not developed because of the over-turning of the pier. This leads a global instability (rotation) of pier-footing system with relatively low stresses in pier itself. While a lateral load is persistently increased in anchored system, the successive flexural cracking failure at cold joint is observed even after the local shear failure of soil due to redistribution of stress equilibrium between soil and pier structure as long as a tensile action of anchor cable is active.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.6B
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• pp.921-929
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• 2010

Group communication that involves the setup of a list of users has been a topic of interest in mobile industry. Push to Talk over Cellular (PoC), a group communication service for cellular phone network, is a type of half duplex communications that allows a single person to reach an active talk group without making several calls, but a single button press. Based on this service, we build a new protocol called Push to Talk over Mobile Wimax that uses group communication service in 802.16e network. Also, weper formed simulation to verify and evaluate performance of the designed service in Mobile Wimax network. From the results of performance evaluation, network administrators can evaluate the stability of network and make a better of network's shortcoming and have decision to build the robust network.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.4 no.2
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• pp.267-282
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• 1997

This study was to test the relationship between regular physical exercise and physical fitness in nursing students. These subjects were 54 volunteers who agreed with intention of this study and were composed of 24 active group and 30 non-active group. The selected physical fitness tests were grip strength and back strength for measuring muscular strength, sargent jump and standing broad jump for measuring power, push-up, sit-up, and heart rate for measuring total endurance, reaction time and side step test for measuring agility, stick test and stork stand for measuring balance, and trunk flexion and trunk extension for measuring flexibility. The conclusion acquired was as follows : 1) Grip strength had significant difference between active group of $29.5{\pm}5.9kg$ and non-active group $25.4{\pm}7.2kg$(t=2.283, p=.027), and back strength between active group of $54.1{\pm}13.7kg$ and non-active group of $44.7{\pm}15.7kg$(t=2.310, p=.025), 2) Sargent jump was lower with non-active group($44.9{\pm}8.6cm$) than with active group($45.3{\pm}8.8cm$), however, was not significant(t=.182, p=.856). Standing broad jump was significantly lower with non-active group of $161.3{\pm}28.7cm$ than with active group of $191.4{\pm}27.0cm$(t=3.939, p=.000). 3) Push-up showed significant difference between active group of $25.3{\pm}12.3times$ and non-active group of $11.5{\pm}5.1times$(t=5.572, p=.000), and sit-up between active group of $21.8{\pm}7.4times$ and non-active group of $17.1{\pm}5.8times$(t=2.631, p=.011), and heart rate between actvie group of $110.5{\pm}12.8$beats/min and non-active group of $121.5{\pm}9.5$beats/min(t=-3.648, p=.001). 4) Reaction time was significantly higher with non-active group of $.300{\pm}.051sec$ than with active group of $.341{\pm}.041sec$(t=-3.285, p=.002). Side step test was lower with non-active group($8.8{\pm}1.1times$) than with active group($9.2{\pm}1.2times$), however, was not significant (t=1.309, p=.196). 5) Stick test showed not significant difference between active group of $25.8{\pm}14.8sec$ and non-active group of $30.7{\pm}17.9sec$(t=-1.058, p=.295), and stork stand between active group of $4.5{\pm}3.2sec$ and non-active group of $3.7{\pm}3.5sec$(t=.918, p=.363). 6) Trunk flexion came out not significant difference between active group of $14.2{\pm}5.0cm$ and non-active group of $15.8{\pm}7.3cm$(t=-.927, p=.358), and trunk extension between active group of $67.1{\pm}6.5cm$ and non-active group of $67.3{\pm}6.6cm$(t=-.140, p=.889). 7) Power was shown to be significantly related to total endurance(r=.717, p=.000 ; r-.739, p=.000). 8) Total endurance was shown to be significantly related to agility(r=-.752, p=.000 ; r=.684, p=.000 ; r=-.664, p=.000 ; r=.598, p=.002 ; r=.864, p=.000 ; r=-.536, p=.007). These results suggest that regular physical exercise is effective in promoting and maintaining physical fitness. As the further study, it is necessary to reinvestigate the effect with more refined design.

• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.148-149
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• 2010

본 논문에서는 친환경 차량용 보조배터리 충 방전을 위한 3상 양방향 DC-DC컨버터를 제안한다. 제안한 컨버터는 클램프 스위치의 동작으로 전압 및 전류공진을 최소화하고 대전류단의 순환전류를 감소시켜 전류정격을 줄였다. 제안하는 컨버터의 이론적 해석과 시뮬레이션을 통해 타당성을 검증하였다.

• Journal of the Korean institute of surface engineering
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• v.32 no.4
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• pp.487-495
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• 1999

In order to form metallic electrodes on PZT (Pb (Zr, Ti)O$_3$) ceramics, plating conditions for optimal electroless Ni deposition were investigated. Pb in PZT is the major component to inhibit the electroless deposition, because it plays a active role of catalytic poison in plating solution. Adhesion of the electroless Ni deposits is measured by push-pull scale test and peel test. Results such as deposition ability, deposition rate, and thickness of deposits showed in terms of concentration of etchant, composition of catalyzing solution, and composition and pH of electroless bath solution.

• Proceedings of the IEEK Conference
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• 2001.06e
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• pp.119-122
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• 2001

This paper deals with new type of active magnetic bearing (AMB) for the linear motors. We adopted optical sensing mechanism for the gap sensing. Using the laser and the PSD (Position Sensitive Device), the absolute rotor position is obtained independent of the profile of the guide rail. With this measurement, the rotor can be controller to follow the straight beam of the laser. Another advantage of optical sensing mechanism might be the elimination of the possible interference between the proximity sensor and the electro-magnet. By adopting the push-full actuating mechanism, the bearing stiffness is increased near the equilibrium position. For the simplicity, distributed control system is constructed. Eight independent PID control algorithm is used with the full order observer. Several simulation md test results are presented.

• Journal of Korean Society of Steel Construction
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• v.18 no.3
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• pp.361-371
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• 2006

In recent years, to overcome drawbacks related to the aplicati on of classical structural optimization algorithms, various drift design methods based on factores of member displacement participation factors have been developed to size members if they satisfy stiffness criteria. In particular, a resizing algorithm based on dynamic displacement participation factors from the response spectrum analysis has been applied in the drift design of steel structures subjec ted to seismic lateral forces. In this aproach, active members are selected for displacement control based on the displacement participation fa ve members may be taken out and added to the active members for the drift control. The resizing algorithm can be practically and effectively applied to drift design of high-rise buildings however, the inelastic behavior o f the resizing algorithm has not ben evaluated yet. To develop the resizing algorithm considering the performance of nonlinearity as well a s elastic stifness, the evaluation model of resizing algorithm s is developed and aplied to the examples of moment-resisting steel frame, which is one of the simplest structural systems. The inelastic behavior of moment-resisting steel frame designed by the resizing algorithm is also discussed.

• Journal of Korean Society of Steel Construction
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• v.13 no.5
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• pp.557-566
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• 2001

Composite slab with deckplate needs sufficient bond strength between deckplate and concrete to conduct composite behavior Composite slab can transfer the shear by either chemical adhesion interface interlock, or active friction. There are several way of mechanical shear connection in composite slab. that is embossments shear connector shape of deckplate etc. Effect of mechanical interaction is deped on shape of deckplate which is to prevent peeling between deckplate and concrete and an amount of shear connector. The behavior and strength of the connection between the decking and the concrete slab due to embossments and end anchorage may be estimated using the push-off tests described in this paper We proposed the equation of shear bond strength in the composite slab It will be use to design by basic data in composite slab.

• Physical Therapy Korea
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• v.25 no.3
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• pp.1-11
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• 2018

Background: Lumbopelvic stability is highly important for exercise therapy for patients with low back pain and shoulder dysfunction. It can be attained using a pelvic compression belt. Previous studies showed that external pelvic compression (EPC) enhances form closure by reducing sacroiliac joint laxity and selectively strengthens force closure and motor control by reducing the compensatory activity of the stabilizer. In addition, when the pelvic compression belt was placed directly on the anterior superior iliac spine, the laxity of the sacroiliac cephalic joint could be significantly reduced. Objects: This study aimed to compare the effects of EPC on lumbopelvic and shoulder muscle surface electromyography (EMG) activities during push-up plus (PUP) and deadlift (DL) exercise, trunk extensor strength during DL exercise. Methods: Thirty-eight subjects (21 men and 17 women) volunteered to participate in this study. The subjects were instructed to perform PUP and DL with and without the EPC. EMG data were collect from serratus anterior (SA), pectoralis major (PM), erector spinae (ES), and multifidus (MF). Trunk extensor strength were tested in DL exercise. The data were collected during 3 repetitions of all exercise and the mean of root mean square was used for analysis. Results: The EMG activities of the SA and PM were significantly increased in PUP with pelvic compression as compared with PUP without pelvic compression (p<.05). In DL exercise, a significant improvement in trunk extensor strength was observed during DL exercise with pelvic compression (p<.05). Conclusion: The results of this study indicate that lumbopelvic stabilization reinforced with external pelvic compression may be propitious to strengthen PUP in more-active SA and PM muscles. Applying EPC can improve the trunk extensor strength during DL exercise. Our study shows that EPC was beneficial to improve the PUP and DL exercise efficiency.