• 한국공간구조학회논문집
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• 제18권4호
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• pp.81-88
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• 2018

Seismic isolation systems have typically been used in the form of base seams in mid-rise and low-rise buildings. In the case of high-rise buildings, it is difficult to apply the base isolation. In this study, the seismic response was analyzed by changing the installation position of the seismic isolation device in 3D high - rise model. To do this, we used 30-story and 40-story 3D buildings as example structures. Historic earthquakes such as Mexico (1985), Northridge (1994) and Rome Frieta (1989) were applied as earthquake loads. The installation position of the isolation device was changed from floor to floor to floor. The maximum deformation of the seismic isolation system was analyzed and the maximum interlaminar strain and maximum absolute acceleration were analyzed by comparing the LB model with seismic isolation device and the Fixed model, which is the base model without seismic isolation device. If an isolation device is installed on the lower layer, it is most effective in response reduction, but since the structure may become unstable, it is effective to apply it to an effective high-level part. Therefore, engineers must consider both structural efficiency and safety when designing a mid-level isolation system for high-rise buildings.

• Computers and Concrete
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• 제20권4호
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• pp.419-427
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• 2017

A methodology, based on fragility functions, is proposed to evaluate the seismic performance of seismic isolated $45^{\circ}$ skewed concrete bridge: 1) twelve types of seismic isolation devices are considered based on two different design parameters 2) fragility functions of a three-span bridge with and without seismic isolation devices are analytically evaluated based on 3D nonlinear incremental dynamic analyses which seismic input consists of 20 selected ground motions. The optimum combinations of isolation device design parameters are identified comparing, for different limit states, the performance of 1) the Seismic Isolated Bridges (SIB) and 2) Not Seismic Isolated Bridge (NSIB) designed according to the AASHTO standards.

• IEIE Transactions on Smart Processing and Computing
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• 제5권3호
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• pp.164-168
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• 2016

A low insertion-loss, high-isolation switch based on single pole double throw (SPDT) for a 2.4GHz Bluetooth low-energy transceiver is presented in this paper. In order to increase isolation, the body floating technique is implemented. Based on characteristics whereby the ratio of the sizes of the shunt and the series transistors significantly affect the performance of the switches, the device sizes are optimized. A simple matching network is also designed to enhance the insertion loss. Thus, the SPDT switch has high isolation and low insertion loss without increasing the complexity of the circuit. The proposed SPDT is designed and simulated in a complementary metal-oxide semiconductor 65nm process. The switch has a $530{\mu}m{\times}270{\mu}m$ area and achieves 0.9dB, 1.78dB insertion loss and 40dB, 41dB isolation of transmission, reception modes, respectively.

• 국제초고층학회논문집
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• 제11권3호
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• pp.207-219
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• 2022

During the structural design of urban over-track high-rise buildings, two problems are most likely encountered: the abrupt change of story stiffness between the podium and the upper towers, as well as the demand for train-induced vibration control. Traditional earthquake-resistant structures have to be particularly designed with transfer stories to meet the requirement of seismic control under earthquakes, and thus horizontal seismic isolation techniques are recommended to solve the transfer problem. The function of mitigating the vertical subway-induced vibration can be integrated into the isolation system including thick rubber bearings and 3D composite vibration control devices. Engineering project cases are presented in this paper for a more comprehensive understanding of the engineering practice and research frontiers of urban over-track high-rise buildings in China.

• ETRI Journal
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• 제31권3호
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• pp.342-344
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• 2009

From a hydrodynamic device simulation for the pseudomorphic high electron mobility transistors (pHEMTs), we observe an increase of maximum extrinsic transconductance and a decrease of source-drain capacitances. This gives rise to an enhancement of the switching speed and isolation characteristics as the upper-to-lower planar-doping ratios (UTLPDR) increase. On the basis of simulation results, we fabricate single-pole-double-throw transmitter/receiver monolithic microwave integrated circuit (MMIC) switches with the pHEMTs of two different UTLPDRs (4:1 and 1:2). The MMIC switch with a 4:1 UTLPDR shows about 2.9 dB higher isolation and approximately 2.5 times faster switching speed than those with a 1:2 UTLPDR.

• 전기학회논문지
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• 제62권10호
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• pp.1413-1420
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• 2013

This paper proposes a novel compact MIMO antenna which has miniaturized radiators and their row correlation coefficient, working for the LTE mobile communication, and its SAR is observed. Each of the proposed radiators has a shape of staircase and the bandwidth is twice larger than the conventional PIFA as 600MHz(21%) in 2.5 GHz - 3.15 GHz. And the area of the radiators is $16.5mm{\times}9.7mm$ proper for a handheld device. Also, by adding a planar mushroom decoupling structure between the radiators, the isolation is improved. The design has been carried out using the commercial full-wave time-domain EM solver and the finalized MIMO antenna has the return loss less than -10 dB in the LTE band, the isolation better than 20 dB and the efficiency more than 90% with the gain of 4.3 dB. Regarding the SAR of the antenna, it is observed that the average SAR value of 1g is estimated as 1.37W/Kg, which is lower than the SAR standard.

• Structural Engineering and Mechanics
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• 제61권6호
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• pp.795-806
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• 2017

According to the characteristics of continuous beam bridges, the relative displacement is too large to collision or even girder falling under earthquakes. A device named Cable-sliding Modular Expansion Joints(CMEJs) that can control the relative displacement and avoid collision under different ground motions is proposed. Working principle and mechanical model is described. This paper design the CMEJs, establish the restoring force model, verify the force model of this device by the pseudo-static tests, and describe and analyze results of the tests, and then based on a triple continuous beam bridge that has different heights of piers, a 3D model with or without CMEJs were established under Conventional System (CS) and Seismic Isolation System (SIS). The results show that this device can control the relative displacement and avoid collisions. The combination of isolation technology and CMEJs can be more effective to achieve both functions, but it need to take measures to prevent girder falling due to the displacement between pier and beam under large earthquakes.

• 한국전자파학회논문지
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• 제27권3호
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• pp.229-238
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• 2016

본 논문에서는 배열안테나의 성능개선의 한 방법으로 표면파제어를 통한 격리도 개선에 관한 연구를 진행하였다. 배열의 소자 간 격리도 개선을 위해 Perfect Magnetic Conductor(PMC)와 SOFT-표면을 도입하였으며, 접지면의 중앙부에 이들을 삽입하여 모의실험을 진행함으로써 격리도 변화와 성능개선 유무를 알아보았다. 모의실험 결과, E-plane 배열에서 PMC와 SOFT-표면 모두 최대 40 dB 이상의 격리도 향상과 더불어 최대 2.2 dBi 정도의 이득 개선을 확인하였으며, H-plane 배열의 경우, 표면파 전파를 통한 상호결합보다 공기 중의 field를 통한 상호결합이 보다 크게 작용하는 것을 확인하였다. 이 연구는 향후 소형 배열안테나 개발 및 배열안테나의 성능개선 등에 유용하게 사용될 것이다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.50-51
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• 2009

This paper presents integrated passive device (IPD) based on Wilkinson power divider. The simulated 2-way power divider has the insertion loss of 3.123 dB, output isolation of -24.576 dB, input return loss of 26.415 dB, and output return loss of 33.478 dB. The power divider is based on IPD process design simulation at 2.5 GHz for WiMAX (Worldwide Interoperability for Microwave Access) applications. The chip size of power divider is $1\;\times\;1.2\;mm^2$, which is under fabrication.

• Journal of electromagnetic engineering and science
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• 제14권4호
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• pp.411-414
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• 2014

A switch is one of the most useful circuits for controlling the path of signal transmission. It can be added to digital circuits to create a kind of gate-level device and it can also save information into memory. In RF subsystems, a switch is used in a different way than its general role in digital circuits. The most important characteristic to consider when designing an RF switch is keeping the isolation as high as possible while also keeping insertion loss as low as possible. For high isolation, we propose leakage signal cancellation and inductive switching for designing a singlepole double-throw (SPDT) RF switch. By using the proposed method, an isolation level of more than 23 dB can be achieved. Furthermore, the heterojunction bipolar transistor (HBT) process is used in the RF switch design to keep the insertion loss low. It is demonstrated that the proposed RF switch has an insertion loss of less than 2 dB. The RF switch operates from 1 to 8 GHz based on the $0.18-{\mu}m$ SiGe HBT process, taking up an area of $0.3mm^2$.