• Smart Media Journal
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• v.4 no.3
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• pp.38-43
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• 2015

The increased number of smart devices leads users to share multimedia contents with others. Smart device users transmit multimedia files using apps. For multimedia file transfer under NAT (Network Address Translator), a lot of apps exploit a server with public IP or short range communication technologies such as WiFi Direct or Bluetooth because smart devices with private IP address cannot communicate each other directly. We first proposed the push service based file transmission scheme without an additional server and distance limitation. Second, for the push service based transmission, we proposed congestion control scheme to adapt transmission rate to the receiver's link bandwidth. Third, we considered bandwidth aware transmission for senders with different bandwidth. We implemented apps to evaluate the proposed scheme, and conducted experiments with smart devices.

• Proceedings of the KSR Conference
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• 2000.11a
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• pp.243-249
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• 2000

This experimental study is shows speed-up possibility for the conventional railway vehicle. We appraise derailment coefficient then increase the velocity of the kyungbu line, honam line, changhang line, kyungjeon line.

• Journal of the korean academy of Pediatric Dentistry
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• v.43 no.1
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• pp.36-43
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• 2016

The aim of this study was to evaluate the effect of blood contamination on the push-out bond strength and surface morphology of tricalcium silicate materials; Biodentine$^{(R)}$, Theracal$^{(R)}$ and mineral trioxide aggregate. The standardized lumens of root slices prepared from extracted single-root human teeth were filled with Biodentine$^{(R)}$, Theracal$^{(R)}$ and mineral trioxide aggregate by manufacturer's instruction. The specimens were randomly divided into 2 groups (n = 20) for each material and then incubated for 4 days at $37^{\circ}C$; control group (phosphate buffered saline solution) and experimental group (fetal bovine serum). The push-out bond strengths were then measured by a universal testing machine and the surface morphology of each experimental group was analyzed by scanning electron microscope. Biodentine$^{(R)}$ and Theracal$^{(R)}$ showed higher push-out bond strength compared with mineral trioxide aggregate after exposure to fetal bovine serum. A substantial change in the surface morphology of each material was observed after exposure to fetal bovine serum. In conclusion, the push-out bond strengths of Biodentine$^{(R)}$ and Theracal$^{(R)}$ were higher than mineral trioxide aggregate when exposed to blood contamination. Therefore, it is supposed that the use of Biodentine$^{(R)}$ and Theracal$^{(R)}$ is appropriate in the presence of blood.

• Journal of the Korean Society of Safety
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• v.19 no.2
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• pp.125-129
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• 2004

In masive concrete placement, cracking problem due to hydration heat is frequently encountered. One of measure to solve this problem is to make a construction joint. However, it is cumbersome to make it by chipping the surface of joint. In this study, push-out test for 18 specimens was conducted to compare the interface shear strength of consturction joints whose surfaces were prepared with three methods; chipping, rib-lath, folded rib-lath. Compared to the specimens made with conventional surface chipping, those with rib-lathe showd excellent preformance increasing shear resistance capacity and the role of shear key conceived by folding rib-lath played important role in enhancing shear resistance.

• Journal of Korean Society of Steel Construction
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• v.18 no.2
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• pp.279-288
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• 2006

A stud connector was used by the shear connector of a composite beam. The shear connector is an important element in heightening the composition rate of a composite beam .study was based on the experiments conducted on 15 specimens using the push-out test.In this paper, through an experiment, the shear connector of other forms was analyzed instead of the stud connector. It is hoped that this application can be used in composite beams.

• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.6 s.58
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• pp.75-87
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• 2009

In this study, FEM analysis has been performed based on the results from domestic experimental researches regarding to material and member characteristics of masonry. After validation of reliability for the used FEM analysis method, this study is progressed the evaluation of seismic capacity for existing prototype masonry building in Korea. According to the evaluation for the prototype masonry building, the horizontal shear force and the average shear stress are similar to those of previous studies.

• Proceedings of the KIPE Conference
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• 2013.11a
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• pp.29-30
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• 2013

본 논문에서는 수중통신용 Parametric Array Transducer를 구동하기 위한 고효율 전력증폭기를 제안한다. 수중전력증폭기는 증폭부와 전원부로 나뉘며 증폭부는 Class B push-pull type의 전력증폭기를 사용하며 전력증폭기 구동을 위한 전원부는 기존의 일정전압이 아닌 가변전압을 얻는 Phase-shifted PWM AC/DC 컨버터를 사용하여 고효율로 동작한다. 증폭부는 Class B push-pull type 증폭기를 사용함으로써 뛰어난 선형성이 보장되며 전원 또한 ET(Envelope Tracking)기술을 적용한 가변전압 AC/DC컨버터를 사용하여 고효율로 동작한다. 본 논문에서는 고 효율 수중전력증폭기와 가변전압 AC/DC컨버터의 전력회로를 제시하고 시뮬레이션과 실험을 통하여 특성을 확인하였으며, 수중음향센서를 위한 전력증폭기로 유용하게 사용 될 것을 예상한다.

• Journal of the Korean Society of Safety
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• v.23 no.3
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• pp.42-50
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• 2008

This study, push-off tests for the initially uncracked specimens were conducted to investigate shear transfer mechanism in reinforce concrete elements. Experimental programs for shear transfer were undertaken to investigate the effect of the concrete compressive strength, the presence of steel stirrups as shear reinforcement and the amount of steel stirrups. As the shear plane is loaded, several cracks form in a direction inclined to the shear plane, creating compression struts in the concrete. For this stage, shear is being transferred through a truss-like action produced by the combination of the compressive force in the concrete struts and the tensile force that the steel reinforcement crossing the shear plane develops. In the normal strength concrete specimens with steel stirrups, ultimate failure occurred when the compression struts crushed in concrete. In the high strength concrete specimens, on the other hand, ultimate failure occurred when the steel stirrups developed their yield strength.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.11 no.4
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• pp.100-108
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• 1997

A combined buck and boost push-pull quantum series resonant rectifier(PPQSRR) is newly proposed to achieve a power factor correction without start-up inrush current. Based on the developed dynamic modeling of the proposed rectifier, an inrush current elimination control technique is proposed and the usefullness of the proposed rectifier and control method are verified by computer simulation and experimental results. With the proposed control method, a high power factor and wide range of output voltage can be obtained.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.513-518
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• 1999

The objective of this experiment is to observe the elastic and inelastic behaviors of high-rise reinforced concrete frame with infilled masonry. To do this a building frame designed according to Korean seismic code and detailed in the Korean conventional manner was selected. An 1:12 scale plane masonry-infilled frame model was manufactured according to similitude law. Push-over test were performed under the roof displacement control. To simulate the earthquake effect, the lateral force distribution was maintained to be an inversed triangular by using whiffle tree. From the tests, story displacements, lateral story forces, local plastic rotations and the relations between inter-story drift versus story shear are obtained. Based on the test results, conclusions on the characteristics of the elastic and inelastic behaviors of a high-rise reinforced concrete frame with infilled masonry are drawn.