• Polymer(Korea)
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• v.34 no.1
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• pp.84-87
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• 2010

Copper-indium-diselenide (CIS) particles were prepared by the electrochemical reduction from the mixture solution of corresponding ion compounds. The prepared CIS was used as an insertion layer or a blending component in the organic photovoltaic bulk heterojunction cells composed of poly(3-octylthiophene) and fullerene. The increase of CIS content resulted in the rapid decrease of the open-circuit voltage as well as short-circuit current. The photovoltaic parameters were analyzed in relation to the structures, composition, and morphology of the photovoltaic blends.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.275.1-275.1
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• 2014

The effects of the interfacial buffer layer and temperature on the organic bulk heterojunction (BHJ) nanostructures of copper phthalocyanine (CuPc) and fullerene (C60) systems were investigated using real time in-situ x-ray scattering. In the CuPc:C60 BHJ structures, standing-on configured ${\gamma}$-CuPc phase was formed by co-deposition of CuPc and C60. Once formed ${\gamma}$-phase was thermally stable during the annealing upon $180^{\circ}C$. Meanwhile, the insertion of CuI buffer layer prior to deposition of the CuPc:C60 BHJ layer induced lying-down configured CuPc crystals in the BHJ layer. The lying CuPc peak intensity and the lattice parameter were increased by the thermal annealing. This increment of the intensity seemed to be related to the strain at the interface between CuPc:C60 and CuI, which was proportional to the enhancement of the power conversion efficiency of the device.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.5
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• pp.1029-1034
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• 2012

This paper presents a cost-effective and high-performance film bulk acoustic resonator (FBAR) duplexer module for US-PCS handset applications. The FBAR device uses a glass wafer level packaging process, which is a more cost-effective alternative to the typical silicon capping process. The maximum insertion losses of the FBAR duplexer at the Tx and Rx bands are of 1.9 and 2.4 dB, respectively. The total thickness of the duplexer module is 1.2 mm, including the glass-wafer bonded Tx/Rx FBAR devices, PCB board, and transfer molding material.

• Carbon letters
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• v.1 no.1
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• pp.36-40
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• 2000

The initial irreversible capacity (IIC) of a hard carbon during the charge/discharge reaction is strongly affected by both the initial irreversible capacity on the carbon surface $(IIC_S)$ and the initial irreversible lithium insertion into carbon $(IIC_B)$. The initial coulombic efficiency of the insertion and the desertion of lithium (IIE) can be used as a performance to classify $IIC_B$ of the carbon. The $IIC_B$ was proportional to the specific discharge capacity with a slope, $IIE^{-1}$ - 1. The IIE of hard carbon had four regions. $IIE_A$ for the region of 0~95 mAh/g of $Q_{D1}$ was 60.2%. $IIE_B$ and $IIE_C$ for the regions of 95~172 mAh/g and 172~308 mAh/g had 84.9% and 91.5%, respectively. $IIE_D$ was appeared above 308 mAh/g. But, the $IIE_D$ was reduced to 82.1% compared with $IIE_C$. These IIE might be corresponding to lithium desertion from carbon at the region of 0~172 mAh/g range, lithium desertion from the micropore of carbon at the region of 172~308 mAh/g range, and to the lithium stripping of the plated lithium for the region above 308 mAh/g, respectively.

• ETRI Journal
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• v.36 no.2
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• pp.317-320
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• 2014

A balanced RF duplexer with low interference in an extremely narrow bandgap is proposed. The Long-Term Evolution band-7 duplexer should be designed to prevent the co-existence problem with the WiFi band, whose fractional bandgap corresponds to only 0.7%. By implementing a hybrid bulk acoustic wave (BAW) structure, the temperature coefficient of frequency (TCF) value of the duplexer is successfully reduced and the suppressed interference for the narrow bandgap is performed. To achieve an RF duplexer with balanced Rx output topology, we also propose a novel balanced BAW Rx topology and RF circuit block. The novel balanced Rx filter is designed with both lattice- and ladder-type configurations to ensure excellent attenuation. The RF circuit block, which is located between the antenna and the Rx filter, is developed to simultaneously function as a balance-tounbalance transformer and a phase shift network. The size of the fabricated duplexer is as small as $2.0mm{\times}1.6mm$. The maximum insertion loss of the duplexer is as low as 2.4 dB in the Tx band, and the minimum attenuation in the WiFi band is as high as 36.8 dB. The TCF value is considerably lowered to $-16.9ppm/^{\circ}C$.

• Proceedings of the Korean Information Science Society Conference
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• 2006.10c
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• pp.177-182
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• 2006

최근 무선 통신 구조가 확산대면서, 모바일 기기와 다양한 모바일 GIS 서비스가 일반화되었다. 그래서 모바일 기기에서 효과적으로 GIS 자료들을 검색할 수 있는 모바일용 GIS DBMS가 필요하다. 물론 모바일 GIS DBMS는 환경적 제약사항과 GIS 자료들의 특성들을 극복하기 위한 대량삽입 기법이 필요하며 이 기법은 모바일 GIS DBMS를 개발하는데 있어서 가장 중요하다. 이 제약사항은 낮은 대역폭, 작은 저장공간 그리고 비공간 데이터 보다 상대적으로 매우 큰 공간 데이터의 특징을 포함한다. OBO기법을 이용하는 GIS DBMS로의 데이터의 삽입은 차례대로 삽입된다. 그러나 대부분의 공간데이터들은 전송비용과 긴 로딩시간으로 인해 서비스를 지연시키기 때문에 공간 인덱스를 기반으로 하는 대량삽입을 선택한다. 본 논문에서는 높은 성능과 안전성을 가진 동적인 공간 인덱스 R*-tree을 이용하는 대량 삽입 기법을 제공한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.7
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• pp.1321-1325
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• 2001

In this article, piezoelectric films and their application for film bulk acoustic resonator (FBAR) devices are presented. The FBAR is composed of piezoelectric film sandwiched between top and bottom electrodes and an acoustic reflector of SiO2/W stacked multilayers. Various FBAR devices were fabricated and evaluated through simulation and measurement. The insertion loss, return loss and Q-factor were observed to be reasonably high and good. The FBAR technology seems very promising particularly for RF band filter application.

• Proceedings of the IEEK Conference
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• 2001.06b
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• pp.17-20
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• 2001

In this paper, film bulk acoustic resonator(FBAR) with an air-gap is fabricated by removing ZnO sacrificial layer and its characteristics as a various dimension of ZnO sacrificial and piezoelectric layer is evaluated. The center frequency of the FBAR device with the ZnO film is about 1.9 GHz. Because of mass-loading effect, a dimension of sacrificial layer and piezoelectrc layer affect frequency response such as center frequency, insertion loss, band separation, attenuation and so on.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.10a
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• pp.621-625
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• 2001

In this article, piezoelectric films and their application for film bulk acoustic resonator (FBAR) devices are presented. The FBAR is composed of piezoelectric film sandwiched between top and bottom electrodes and an acoustic reflector of SiO$_2$/W slatted multilayers. Various FBAR devices were fabricated and evaluated through simulation and measurement. The insertion loss, return loss and Q-factor were observed to be reasonably high and good. The FBAR technology seems very promising particularly for RF band filter application.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2395-2397
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• 2005

A low voltage operated piezoelectric RF MEMS in-line switch has been realized by using silicon bulk micromachining technologies for advanced mobile/wireless applications. The developed RF MEMS in-line switches were comprised of four piezoelectric cantilever actuators with an Au contact metal electrode and a suspended Au signal transmission line above the silicon substrate. The measured operation dc bias voltages were ranged from 2.5 to 4 volts by varying the thickness and the length of the piezoelectric cantilever actuators, which are well agreed with the simulation results. The measured isolation and insertion loss of the switch with series configuration were -43dB and -0.21dB (including parasitic effects of the silicon substrate) at a frequency of 2GHz and an actuation voltage of 3 volts.