• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.3
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• pp.73-81
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• 2020

Today's massively multiplayer online games(MMOGs) can contain millions of synchronous players scattered across the world and participating with each other within a single shared game. The increase in the number of players in MMOGs has led to some issues with the demand of server which generates a significant increase in costs for the game industry and impacts to the quality of service offered to players. In dealing with a considerable scale of MMOGs, we propose a cloud computing and peer-to-peer(P2P) hybrid architecture in this paper. Given the two nearly independent functionalities of P2P and cloud architectures, we consider the possibility of fusing these two concepts and researching the application of the resultant amalgamation in MMOGs. With an efficient and effective provisioning of resources and mapping of load, the proposed hybrid architecture relieves a lot of computational power and network traffic, the load on the servers in the cloud while exploiting the capacity of the peers. The simulation results show that MMOGs based on the proposed hybrid architecture have better performance and lower traffic received compared with MMOGs based on traditional client-server system.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.1
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• pp.78-85
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• 2023

This study evaluates the performance of reinforced concrete columns using hybrid fiber sheets for structural behavior. The purpose of this method is to improve the load-bearing capacity of the reinforced structure by impregnating a hybrid fiber sheet, which is woven by arranging aramid and glass fibers uniaxially and attached to an aged concrete structure requiring reinforcement with epoxy. In particular, not only the weight reduction of the material obtained by using a fiber lighter than the steel material, but also the low-strength, high-toughness fiber element among the fibers used delays the brittle fracture of the high-strength, low-toughness fiber element. The low-strength, high-toughness fiber element among the fibers used delays the brittle fracture of the high-strength, low-toughness fiber element, resulting in weight reduction compared to steel. The study conducted structural tests on four specimens, with the hybrid reinforcement method and failure mode as main variables. Specimen size and loading conditions were chosen to be comparable with previous studies. The structural performance of the specimen was evaluated using energy dissipation capacity and ductility. Analysis shows that excellent results can be obtained with the hybrid fiber sheet reinforcement.

• Composites Research
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• v.17 no.1
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• pp.18-28
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• 2004

In order to evaluate the strength of carbody structures of railway rolling stock made of laminated fiber-reinforced composite materials, total laminate approach was introduced. Structural analyses were conducted to check the basic design of hybrid composite carbody structures of the Korean Tilting Train eXpress(TTX) with the service speed of 180km/h. The mechanical tests were also conducted to obtain strengths of composite laminates. The results show that all stress components of composite carbody structures are inside of failure envelopes and total laminate approach is recommended to predict the failure of hybrid composite carbody structures at the stage of the basic design.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.25 no.6
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• pp.357-364
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• 2013

In previous study, the hybrid floating structure composed of a pontoon and a semi-submersible was suggested to reduce the motions of floating structure. It was reported that the suggested hybrid floating structure could reduce the motions. However, the hybrid floating structure could not support enough buoyancy. In this study, the combination floating structure is newly suggested to resolve the problem. In order to adopt the shape of floating structures reducing the motions, the hydrodynamic analysis of various floating structures such as the pontoon, the hybrid and the combination of floating structure is carried out through hydrodynamic analysis program ANSYS AQWA. It is found that the combination floating structure is remarkably effective to reduce the motions compared to the other cases. Thus, the suggested combination floating structure may be a useful offshore structure for constructing a very large floating structure.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.595-595
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• 2013

본 연구에서는 brush painting공법을 이용하여 인쇄형 유기태양전지에 적용이 가능한 ITO nanoparticle/Ag nanowire/ITO nanoparticle (Nano IAI) 다층 하이브리드 투명 전극의 전기적, 광학적, 구조적 특성을 연구하였다. 평균 25 nm 사이즈의 ITO 나노 입자로 구성된 ITO 나노 잉크와 직경 20~25 nm의 Ag nanowire 잉크를 기반으로 Brush painting 기술을 적용해 상온, 상압에서 낮은 면저항과 높은 투과도를 가지는 Nano IAI 하이브리드 투명 전극을 제작하였다. Nano IAI 투명 전극 제작 시 일정한 두께에서 Ag nanowire 코팅을 위한 brush painting 횟수를 변수로 하여 최적화 공정을 진행하였으며, Ag nanowire가 2번 brush painting 된 Nano IAI 다층 하이브리드 투명전극은 $3.4{\times}10^{-3}$ ohm-cm의 비저항과 52.33 ohm/square의 낮은 면저항을 나타내었다. 이를 통해 효과적으로Ag nanowire를 ITO nanoparticle 사이에 삽입할 경우, 고온의 열처리 공정을 통하지 않고 낮은 면저항을 가지는 인쇄형 투명 전극을 구현할 수 있음을 확인할 수 있었다. 특히 Nano IAI 다층 하이브리드 전극은 83.83%의 높은 투과도를 나타내는데 이는 삽입된 Ag Nanowire의 폭과 길이가 나노 사이즈이기 때문에 입사되는 빛이 흡수되기보다 대부분 투과하기 때문으로 사료된다. 또한, XRD 분석과 HRTEM 분석을 통해 Nano IAI 다층 하이브리드 투명전극의 전도 메커니즘을 설명하였다. 이와 같은 우수한 전기적, 광학적 특성은 brush painting 기법으로 제작된 Nano IAI 다층 하이브리드 투명 전극의 인쇄형 유기태양전지 적용 가능성을 나타낸다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.5 s.120
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• pp.547-552
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• 2007

In this paper, the coupled microstrip lines of hairpin type are applied to design a compact microstrip ring hybrid. When the gap decreases, three attenuation poles are created by coupling between the lines. The proposed structure can achieve a significant reduction of size and suppression of the harmonics. And it has the same frequency responses of conventional ring hybrid at 2.55 GHz. The harmonics are suppressed to below -20 dB up to 12 GHz, including the third harmonic. The ring part size of the proposed ring hybrid is reduced to one forth of the conventional ring hybrid. The measured frequency responses agree well with simulated ones.

• Journal of the Earthquake Engineering Society of Korea
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• v.9 no.1 s.41
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• pp.61-70
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• 2005

Shaking table tests are carried out on a single-degree-of-freedom mass that is equipped with a hybrid base isolation system. The isolator consists of a set of four specially-designed friction pendulum systems (FPS) and a magnetorheological (MR) damper. The structure and its hybrid isolation system are subjected to various intensities of near- and far-fault earthquakes on a large shake table. The proposed fuzzy controller uses feedback from displacement or acceleration transducers attached to the structure to modulate resistance of the semi-active damper to motion. Results from several types of passive and semi-active control strategies are summarized and compared. The study shows that a combination of FPS isolators and an adjustable MR damper can effectively provide robust control of vibration for a large full-scale structure undergoing a wide variety of seismic loads.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.6
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• pp.1-10
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• 2014

In this study, thirteen reinforced concrete beams, ground granulated blast furnace slag, replacing recycled coarse aggregate with PVA fiber (BSPG series) and recycled coarse aggregate with hybrid fiber ($BSPGR_1$, $BSPGR_2$ series), and standard specimen (BSS) were constructed and tested under monotonic loading. Experimental programs were carried out to improve and evaluate the Structural performance of such test specimens, such as the load-displacement, the failure mode, and the maximum load carrying capacity. All the specimens were modeled in 1/2 scale-down size. Test results showed that test specimens ($BSPGR_1$, $BSPGR_2$ series) was increased the compressive strength by 13%, the maximum load carrying capacity by 4~21% and the ductility capacity by 4~28% in comparison with the standard specimen (BSS). And the specimens ($BSPGR_1$, $BSPGR_2$ series) showed enough ductile behavior and stable flexural failure.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.6A
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• pp.425-433
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• 2011

In this study, in order to investigate the wave-induced buoyancy effects, experimental studies were conducted on pontoon-type floating structures. A series of small-scale tests with various wave cases were performed on the pontoon models. A total of four small-scale pontoon models with different lateral shapes and bottom details were fabricated and tested under the five different wave cases. Six hydraulic pressure gauges were attached to the bottom surfaces of the pontoon models and the wave-induced hydraulic pressure was measured during the tests. Finally, hydraulic pressures subjected to the bottoms of the pontoon models were compared with each other. As the results of this study, it was found that whereas the waffled bottom shape hardly influenced the wave-induced hydraulic pressure, the hybrid lateral shape significantly influenced the wave-induced hydraulic pressure subjected on the bottoms of floating structures. The air gap effects of the hybrid shape contribute to decreasing the wave-induced hydraulic pressure due to absorption of wave impact energy. Compared with box type, the hydraulic pressures of the hybrid type were about 83% at the bow, 74% at the middle, and 53% at the stern.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.2
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• pp.274-279
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• 2021

Since conventional massive antenna systems require too many RF chains, they have disadvantages of high implementation cost and complexity. To overcome this problem, hybrid precoding schemes have been proposed. But, they are still of high implementation cost and complexity because RF chains are connected to all antenna elements. In this paper, we consider massive MIMO systems with overlapped sub-array (OSA) structure and then, propose a hybrid precoding scheme. In the overlapped subarray structure, RF analog precoding matrix has a sparse structure where many elements of RF analog precoding matrix are zeros. Using this sparse property, we propose a GTP-based precoder design method for RF and baseband digital precoding. Through simulation, we show that the proposed scheme has more than 85% of the spectral efficiency of the fully-connected structure while having 20~30% of complexity of it.