• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.14-15
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• 2006

Application of the parallel Build-up is increasing continuously. This report presents about the PCB Build-up technology since 2000. Among the parallel build-up technologies, PALAP application - after making the via, filling the via with electric conductive paste, then expose to make wiring pattern and put them by layer without any glue or middle - is actively developing, especially DENSO company.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2015년도 추계학술발표대회
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• pp.1369-1371
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• 2015

본 논문은 전도성섬유 압력센서로 보행신호를 획득하고 걷기, 서기, 앉기, 계단오르기, 계단내려오기 등 총 5가지 행동을 인식하는 시스템을 개발하는 것이 목적이다. 시스템은 Capacitive pressure 센서, CDC(Capacitive to Digital Converter), 마이크로프로세서, 블루투스 모듈, 스마트 폰으로 구성되고 획득한 데이터 패턴을 분류한 결과 평균 99.5%의 높은 인식률을 보였다. 각 발당 한 개의 채널만을 이용해 행동패턴을 인지함으로써 적은 수의 채널로도 행동인지의 가능함을 확인할 수 있었다.

• 전자공학회논문지
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• 제53권8호
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• pp.119-126
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• 2016

본 논문에서는 의복용 무선전력전송 시스템을 구축을 위한 평면형 직물공진기를 제안하고, 공진기에 사용된 의복용 직물기판의 재질별 특성을 분석하였다. 평면형 직물공진기는 공진주파수가 1-10 MHz가 되도록 직물기판 위에 전도성 물질로 루프 및 코일을 평면 설계하였다. 의복용으로 많이 사용되고 있는 폴리에스테르 섬유와 면을 직물기판으로 사용하였으며, 평면 루프와 코일은 동테이프(copper tape)와 실버페이스트(silver paste)로 설계하였다. 자기공진형 무선전력전송 시스템에 적용된 직물의 재질별 특성을 분석하기 위해 송신부와 수신부를 대칭으로 설계하였다. 실험 결과, 낮은 유전상수 및 비교적 두꺼운 두께를 가진 직물기판과 표면저항이 작은 도체성 재질의 패턴(루프 및 코일)으로 제작되었을 때, 의복용 무선전력전송 시스템이 높은 전송효율을 보였다. 본 연구를 통해 제안된 평면형 직물 공진기는 무선전력전송 기술의 영역을 의복용으로 넓힐 수 있는 가능성을 보여주었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.421-421
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• 2008

Generally, the polymer thick-film resistors for embedded organic or hybrid substrate are patterned by screen printing so that the accuracy of resistor pattern is not good and the tolerance of resistance is too high(${\pm}$20~30%). To reform these demerits, a method using Fodel$^{(R)}$ technology, which is the patterning method using a photosensitive resin to be developable by aqueous alkali-solution as a base polymer for thick-film pastes, was recently incorporated for the patterning of thermosetting thick-film resistor paste. Alkali-solution developable photosensitive resin system has a merit that the precise patterns can be obtained by UV exposure and aqueous development, so the essential point is to get the composition similar to PSR(photo solder resist) used for PCB process. In present research, we made the photopatternable resistor pastes using 8 kinds of epoxy acrylates and a conductive carbonblack (CDX-7055 Ultra), evaluated their developing performance, and then measured the resistance after final curing. To become developable by alkali-solution, epoxy acrylate oligomers with carboxyl group were prepared. Test coupons were fabricated by patterning copper foil on FR-4 CCL board, plating Ni/Au on the patterned copper electrode, applying the resistor paste on the board, exposing the applied paste to UV through Cr mask with resistor patterns, developing the exposed paste with aqueous alkali-solution (1wt% $Na_2CO_3$), drying the patterned paste at $80^{\circ}C$ oven, and then curing it at $200^{\circ}C$ during 1 hour. As a result, some test compositions couldn't be developed according to the kind of oligomer and, in the developed compositions, the measured resistance showed different results depending on the paste compositions though they had the same amount of carbonblack.

• Journal of Electrochemical Science and Technology
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• 제5권1호
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• pp.32-36
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• 2014

The $0.3Li_2MnO_3{\cdot}0.7LiMn_{0.55}Ni_{0.30}Co_{0.15}O_2$ cathode material was prepared via a co-precipitation method. The vapor grown carbon fiber (VGCF) was used as a conductive material and its effects on electrochemical properties of the $0.3Li_2MnO_3{\cdot}0.7LiMn_{0.55}Ni_{0.30}Co_{0.15}O_2$ cathode material were investigated. From the XRD pattern, the typical complex layered structure was confirmed and a solid solution between $Li_2MnO_3$ and $LiMO_2$ (M = Ni, Co and Mn) was formed without any secondary phases. The VGCF was properly distributed between cathode materials and conductive sources by a FE-SEM. In voltage profiles, the electrode with VGCF showed higher discharge capacity than the pristine electrode. At a 5C rate, 146 mAh/g was obtained compared with 232 mAh/g at initial discharge in the electrode with VGCF. Furthermore, the impedance of the electrode with VGCF did not changed much around $9-10{\Omega}$ while the pristine electrode increased from 21.5${\Omega}$ to $46.3{\Omega}$ after the $30^{th}$ charge/discharge cycling.

• 대한지하수환경학회지
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• 제5권2호
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• pp.80-87
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• 1998

지하수의 유동로가 시설의 성능에 미치는 영향이 큰 방사성폐기물처분시설에서는 암반블럭규모의 흐름은 단열망개념으로 해석하고 있다. 본 연구는 연구지역의 지하수유동 해석을 위하여 3차원 투수성단열망모델을 구축하기 위한 것으로서, 단열의 기하학적 인자 및 수리인자에 대한 확률분포함수를 도출하고, 3차원 단열망모델링과 수리시험 결과를 이용한 모델 교정까지의 과정을 포함한다. 구간별 정압주입시험의 결과를 Cubic law로서 해석한 결과 단열투수량계수는 lognormal분포일 때 6.12$\times$$10^{－7}$ $m^2$/sec이다. 부정류해석에 의한 유동차원은 주로 방사상 내지 구상유동 특성을 보인다. FracMan 코드를 이용해서 추정된 투수성단열밀도는 1.73이고, 이때 암반블럭규모(l00 m$\times$100 m$\times$100 m)로 모사된 투수성단열의 수는 3,080개이다.다.

• 한국재료학회지
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• 제21권6호
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• pp.341-346
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• 2011

In this study, we inserted a Zn buffer layer into a AZO/p-type a-si:H layer interface in order to lower the contact resistance of the interface. For the Zn layer, the deposition was conducted at 5 nm, 7 nm and 10 nm using the rf-magnetron sputtering method. The results were compared to that of the AZO film to discuss the possibility of the Zn layer being used as a transparent conductive oxide thin film for application in the silicon heterojunction solar cell. We used the rf-magnetron sputtering method to fabricate Al 2 wt.% of Al-doped ZnO (AZO) film as a transparent conductive oxide (TCO). We analyzed the electro-optical properties of the ZnO as well as the interface properties of the AZO/p-type a-Si:H layer. After inserting a buffer layer into the AZO/p-type a-Si:H layers to enhance the interface properties, we measured the contact resistance of the layers using a CTLM (circular transmission line model) pattern, the depth profile of the layers using AES (auger electron spectroscopy), and the changes in the properties of the AZO thin film through heat treatment. We investigated the effects of the interface properties of the AZO/p-type a-Si:H layer on the characteristics of silicon heterojunction solar cells and the way to improve the interface properties. When depositing AZO thin film on a-Si layer, oxygen atoms are diffused from the AZO thin film towards the a-Si layer. Thus, the characteristics of the solar cells deteriorate due to the created oxide film. While a diffusion of Zn occurs toward the a-Si in the case of AZO used as TCO, the diffusion of In occurs toward a-Si in the case of ITO used as TCO.

• 한국재료학회지
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• 제29권1호
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• pp.37-42
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• 2019

This study investigates Ag coated $Cu_2O$ nanoparticles that are produced with a changing molar ratio of Ag and $Cu_2O$. The results of XRD analysis reveal that each nanoparticle has a diffraction pattern peculiar to Ag and $Cu_2O$ determination, and SEM image analysis confirms that Ag is partially coated on the surface of $Cu_2O$ nanoparticles. The conductive paste with Ag coated $Cu_2O$ nanoparticles approaches the specific resistance of $6.4{\Omega}{\cdot}cm$ for silver paste(SP) as $(Ag)/(Cu_2O)$ the molar ratio increases. The paste(containing 70 % content and average a 100 nm particle size for the silver nanoparticles) for commercial use for mounting with a fine line width of $100{\mu}m$ or less has a surface resistance of 5 to $20{\mu}{\Omega}{\cdot}cm$, while in this research an Ag coated $Cu_2O$ paste has a larger surface resistance, which is disadvantageous. Its performance deteriorates as a material required for application of a fine line width electrode for a touch panel. A touch panel module that utilizes a nano imprinting technique of $10{\mu}m$ or less is expected to be used as an electrode material for electric and electronic parts where large precision(mounting with fine line width) is not required.

• Journal of electromagnetic engineering and science
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• 제12권1호
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• pp.101-106
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• 2012

In this study, we investigated the effect of groove pattern and gap-fill with lossy materials at 15 GHz frequency of Ku-band. We used Epoxy/MWCNT composite materials as gap-fill materials. Although epoxy does not have an absorbance capability, epoxy added conductive fillers, which are multi-walled carbon nanotubes (MWCNT), can function as radar absorbing material. Specimens were fabricated with different MWCNT mass fractions (0, 0.5, 1.0, 2.0 wt%) and their permittivity in the Ku-band was measured using the waveguide technique. We investigated the effect of gap-fill on monostatic RCS by calculating RCS with and without gap-fill. For arbitrarily chosen thickness and experimentally obtained relative permittivity, we chose the relative permittivity of MWCNT at 2 wt% (${\varepsilon}_r$=8.8-j2.4), which was the lowest reflection coefficient for given thickness of 3.3 mm at V-pol. and $80^{\circ}$ incident angle. We also checked the monostatic RCS and the field intensity inside the groove channel. In the case of H-pol, gap-fill was not affected by the monostatic RCS and magnitude was similar with or without gap-fill. However, in the case of V-pol, gap-fill effectively reduced the monostatic RCS. The field intensity inside the groove channel reveals that different RCS behaviors depend on the wave polarizations.

• Composites Research
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• 제16권2호
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• pp.68-73
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• 2003

Fragmentation 시험법과 전기저항 측정을 통하여 탄소 및 SiC 섬유강화 에폭시 복합재료의 계면물성과 섬유파단에 대한 전기적 감지능을 연구하였다. 섬유 함침 각이 증가함에 따라서 계면전단강도는 감소하였고, 섬유파단에 의한 전기저항도 값이 무한대로 증가하는 시간은 길어졌다. 높은 함침 각에서 전기저항도의 초기 기울기는 급격히 증가한 반면. 낮은 각에서는 점차적으로 증가하였다. 또한 낮은 함침각의 두 섬유 모두에서 stress whitening pattern을 뚜렷하게 관찰할 수 있었지만, 높은 함침 각에서는 그렇지 못했다. 섬유 함침 각이 감소함에 따라서 섬유 파단 간격과 debonding된 길이는 두 섬유 모두에서 증가하였다. 본 연구에서 사용한 electro-micromechanical 시험법은 전도성 섬유강화 복합재료의 섬유 함침 각에 따른 계면 감지능 측정을 위해서 비파괴적 평가방법으로 실행 가능하였다.