• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2001년도 Proceedings of 6th International Joint Symposium on Microeletronics and Packaging
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• pp.35-43
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• 2001

Flip chip assembly on organic substrates using ACAs have received much attentions due to many advantages such as easier processing, good electrical performance, lower cost, and low temperature processing compatible with organic substrates. ACAs are generally composed of epoxy polymer resin and small amount of conductive fillers (less than 10 wt.%). As a result, ACAs have almost the same CTE values as an epoxy material itself which are higher than conventional underfill materials which contains lots of fillers. Therefore, it is necessary to lower the CTE value of ACAs to obtain more reliable flip chip assembly on organic substrates using ACAs. To modify the ACA composite materials with some amount of conductive fillers, non-conductive fillers were incorporated into ACAs. In this paper, we investigated the effect of fillers on the thermo-mechanical properties of modified ACA composite materials and the reliability of flip chip assembly on organic substrates using modified ACA composite materials. Contact resistance changes were measured during reliability tests such as thermal cycling, high humidity and temperature, and high temperature at dry condition. It was observed that reliability results were significantly affected by CTEs of ACA materials especially at the thermal cycling test. Results showed that flip chip assembly using modified ACA composites with lower CTEs and higher modulus by loading non-conducting fillers exhibited better contact resistance behavior than conventional ACAs without non-conducting fillers. Microwave model and high-frequency measurement of the ACF flip-chip interconnection was investigated using a microwave network analysis. ACF flip chip interconnection has only below 0.1nH, and very stable up to 13 GHz. Over the 13 GHz, there was significant loss because of epoxy capacitance of ACF. However, the addition of $SiO_2filler$ to the ACF lowered the dielectric constant of the ACF materials resulting in an increase of resonance frequency up to 15 GHz. Our results indicate that the electrical performance of ACF combined with electroless Wi/Au bump interconnection is comparable to that of solder joint.

• 한국세라믹학회지
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• 제38권11호
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• pp.1042-1045
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• 2001

Ba(Zn$_{1}$3/Nb$_{2}$3/) $O_3$-Sr(Zn$_{1}$3/Nb$_{2}$3/) $O_3$계에 대하여 소결 온도 변화와 Zr $O_2$첨가량에 따른 마이크로파 유전특성을 조사하였다. 동일 조성에서 소결 온도가 증가함에 따라 밀도가 향상되고 공진 주파수의 온도계수($ au$$_{f}$)는 감소하는 경향을 보였으나, 유전상수(K)와 품질계수(Q$\times$f)는 커다란 변화가 없었다. 또한 Zr $O_2$첨가량이 증가함에 따라 소결 시편의 밀도가 향상되었고 더불어 유전상수, 품질계수가 증가하는 경향을 보였으며, 공진 주파수의 온도계수가 감소하는 우수한 특성이 나타났다. 특히, 소결온도 1575$^{\circ}C$, 0.6 wt% Zr $O_2$를 첨가했을 때 유전상수가 최대($\varepsilon$$_{r}$=41)로 나타났으며, 공진 주파수의 온도계수는 1.0wt% Zr $O_2$를 첨가했을 때 최소($\tau$$_{f}$=+0.8ppm/$^{\circ}C$)로서 양호한 값을 얻을 수 있었다.었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.174-174
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• 2008

Non-volatile memories using ferroelectric-gate field-effect transistors (Fe-FETs) with a metal/ferroelectric/semiconductor gate stack (MFS-FETs) make non-destructive read operation possible. In addition, they also have features such as high switching speed, non-volatility, radiation tolerance, and high density. However, the interface reaction between ferroelectric materials and Si substrates, i.e. generation of mobile ions and short retention, make it difficult to obtain a good ferroelectric/Si interface in an MFS-FET's gate. To overcome these difficulties, Fe-FETs with a metal/ferroelectric/insulator/semiconductor gate stack (MFIS-FETs) have been proposed, where insulator as a buffer layer is inserted between ferroelectric materials and Si substrates. We prepared $SrBi_2Ta_2O_9$ (SBT) film as a ferroelectric layer and $LaZrO_x$ (LZO) film as a buffer layer on p-type (100) silicon wafer for making the MFIS-FET devices. For definition of source and drain region, phosphosilicate glass (PSG) thin film was used as a doping source of phosphorus (P). Ultimately, the n-channel ferroelectric-gate FET using the SBT/LZO/Si Structure is fabricated. To examine the ferroelectric effect of the fabricated Fe-FETs, drain current ($I_d$) versus gate voltage ($V_g$) characteristics in logarithmic scale was measured. Also, drain current ($I_d$) versus drain voltage ($V_d$) characteristics of the fabricated SBT/LZO/Si MFIS-FETs was measured according to the gate voltage variation.

• Journal of Preventive Medicine and Public Health
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• 제34권1호
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• pp.55-60
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• 2001

Objectives : The SERVQUAL scale is based on gap theory, which suggests the difference between consumers' expectations and the quality of the medical service actually received. However, problems in the implementation of the SERVQUAL scale have been identified by several researchers. Some researchers have proposed a simple performance-based measure (SERVPERF) or au exportation-controlled performance-based measure(Non-Diff) as alternatives to the SERVQUAL scale. On the basis of the theoretical concerns discussed, we examined the capability of each of the three scales(SERVQUAL, Non-Diff, SERVPERF) to explain variations in consumer satisfaction. Methods : Data was gathered from a self-administered questionnaire in a 430 bed hospital. Questionnaires evaluating medical services were distributed to 180 ambulatory patients. A total of 167 usable questionnaires were gathered. The questionnaire was composed of 10 expectation, performance and expectation-controlled performance items. In addition, overall satisfaction and purchase intention were measured. Results : Compared with the SERVQUAL scale, the Non-Diff and SERVPERF scales better explained the observed variations in consumer satisfaction(SERVOQUAL, $R^2=0.29;\;Non-Diff,\;R^2=0.51;\;SERVPERF,\;R^2=0.48$) and purchase intention(SERVQUAL, $R^2=0.22;\;Non-Diff,\;R^2=0.33;\;SERVPERF,\;R^2=0.34$). Conclusion : The maier conclusion from our study is that the Non-Diff and SERVPERF scales are more efficient in assessing consumer satisfaction than the SERVQUAL scale. Therefore we suggest that consumer satisfaction he measured by the Non-Diff or SEVPERF scales.

• 마이크로전자및패키징학회지
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• 제24권2호
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• pp.37-41
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• 2017

$Cu_2O$는 초저가 태양전지의 흡수층으로 적용될 수 있는 물질 중 하나로 direct band gap($E_g={\sim}2.1eV$)을 갖고 있으며 최대 650 nm 파장의 빛을 흡수 할 수 있는 높은 흡수율을 가지고 있다. 또한 무독성, 풍부한 매장량으로 낮은 비용 등의 여러 장점을 가지며 간단하고 저렴한 방법으로 대량으로 제작이 가능하다. 본 연구에서 Au가 증착된 $SiO_2/Si$ 기판 위에 전착법을 통해 $Cu_2O$ 박막을 제작하였다. 우리는 용액의 pH와 작업전극에 인가되는 전위, 용액의 온도와 같은 공정조건을 바꾸어주었고 최종적으로 XRD와 SEM 사진 분석을 통해 박막의 특성을 확인하였다.

• 정보처리학회논문지C
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• 제15C권2호
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• pp.133-140
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• 2008

본 논문에서는 $GF(2^{163})$타원곡선 암호 프로세서를 제안한다. 제안한 암호 프로세서는 타원곡선 정수 곱셈을 위해 수정된 Loez-Dahab Montgomery 알고리즘을 채택하고, $GF(2^{163})$상의 산술 연산을 위해 가우시안 정규 기저(Gaussian Normal Basis: GNB)를 이용한다. 높은 처리율을 위해 Lopez-Dahab 방식에 기반한 규칙적인 주소화 방식의 병렬 타원곡선 좌표 덧셈 및 배 연산 알고리즘을 유도하고 $GF(2^{163})$상의 연산을 수행하는 두 개의 워드-레벨 산술 연산기(Arithmetic Unit: AU)를 설계한다. 제안된 타원곡선 암호 프로세서는 Xilinx사의 XC4VLX80 FPGA 디바이스에 구현되었으며, 24,263개의 슬라이스를 사용하고 최대 동작주파수는 143MHz이다. 제안된 구조를 Shu 등의 하드웨어 구현과 비교했을 때 하드웨어 복잡도는 약 2배 증가 하였지만 4.8배의 속도 향상을 보인다. 따라서 제안된 타원곡선 암호 프로세서는 네트워크 프로세서와 웹 서버등과 같은 높은 처리율을 요구하는 타원곡선 암호시스템에 적합하다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.16-17
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• 2010

Molecular spintronics has attracted attentions, which combines molecular electronics with the spin degree of freedom in electron transport. Among various molecules as candidates of the molecular spintronics, single molecule magnet (SMM) is one of the most promising material. SMM molecules show a ferromagnetic behavior even as a single molecule and hold the spin information even after the magnetic field is turned off. Here in this report, we show the spin behavior of SMM molecules adsorbed on the Au surface by combining the observation of Kondo peak in the STS and ESR-STM measurement. Kondo resonance state is formed near the Fermi level when degenerated spin state interacts with conduction electrons. ESR-STM detects the Larmor frequency of the spin in the presence of a magnet field. The sample include $MPc_2$ and $M_2Pc_3$ molecules ($M\;=\;Tb^{3+}$, $Dy^{3+}$, and $Y^{3+}$ Pc=phthalocyanine) whose critical temperature as a ferromagnet reaches 40 K. A clear Kondo peak was observed which is originated from an unpaired electron in the ligand of the molecule, which is the first demonstration of the Kondo peak originated from electron observed in the STS measurement. We also observed corresponding peaks in ESR-STM spectra. [1] In addition we found that the Kondo peak intensity shows a clear variation with the conformational change of the molecule; namely the azimuthal rotational angle of the Pc planes. This indicates that the Kondo resonance is correlated with the molecule electronic state. We examined this phenomena by using STM manipulation technique, where pulse bias application can rotate the relative azimuthal angle of the Pc planes. The result indicates that an application of ~1V pulse to the bias voltage can rotate the Pc plane and the Kondo peaks shows a clear variation in intensity by the molecule's conformational change.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.380-380
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• 2010

Currently, organic light-emitting diodes (OLEDs) have been proven of their readiness for commercialization in terms of lifetime and efficiency. In accordance with emerging new technologies, enhancement of light efficiency and extension of application fields are required. Particularly inverted structures, in which electron injection occurs at bottom and hole injection on top, show crucial advantages due to their easy integration with Si-based driving circuits for active matrix OLED as well as large open area for brighter illumination. In order to get better performance and process reliability, usually a proper buffer layer for carrier injection is needed. In inverted top emission OLED, the buffer layer should protect underlying organic materials against destructive particles during the electrode deposition, in addition to increasing their efficiency by reducing carrier injection barrier. For hole injection layers, there are several requirements for the buffer layer, such as high transparency, high work function, and reasonable electrical conductivity. As a buffer material, a few kinds of transition metal oxides for inverted OLED applications have been successfully utilized aiming at efficient hole injection properties. Among them, we chose 2 nm of $WO_3$ between NPB [N,N'-bis(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine] and Au (or Al) films. The interfacial energy-level alignment and chemical reaction as a function of film coverage have been measured by using in-situ ultraviolet and X-ray photoelectron spectroscopy. It turned out that the $WO_3$ interlayer substantially reduces the hole injection barrier irrespective of the kind of electrode metals. It also avoids direct chemical interaction between NPB and metal atoms. This observation clearly validates the use of $WO_3$ interlayer as hole injection for inverted OLED applications.

• Bulletin of the Korean Chemical Society
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• 제22권8호
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• pp.801-806
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• 2001

A study has been carried out on the separation of gold, iridium, palladium, rhodium, ruthenium and platinum in chromite samples and their quantitative determination using inductively coupled plasma atomic emission spectrometry (ICP-AES). The dissolution condition of the minerals by fusion with sodium peroxide was optimized and chromatographic elution behaviour of the rare metals was investigated by anion exchange chromatography. Spectral interference of chromium, a matrix of the minerals, was investigated on determination of gold. Chromium interfered on determination of gold at the concentration of 500 mg/L and higher. Gold plus trace amounts of iridium, palladium, rhodium and ruthenium, which must be preconcentrated before ICP-AES was separated by anion exchange chromatography after reducing Cr(Ⅵ) to Cr(III) by H2O2. AuCl4- retained on the resin column was selectively eluted with acetone- HNO3-H2O as an eluent. In addition, iridium, palladium, rhodium and ruthenium remaining on the resin column were eluted as a group with concentrated HCl. However, platinum was eluted with concentrated HNO3. The recovery yield of gold with acetone-HNO3-H2O was 100.7 ${\pm}2.0%$, and the yields of palladium and platinum with concentrated HCl and HNO3 were 96.1 ${\pm}1.8%$ and 96.6 ${\pm}1.3%$, respectively. The contents of gold and platinum in a Mongolian chromite sample were 32.6 ${\pm}$ 2.2 ${\mu}g$/g and 1.6 $\pm$ 0.14 ${\mu}g$/g, respectively. Palladium was not detected.

• 융합정보논문지
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• 제11권4호
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• pp.203-210
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• 2021

본 연구는 의료기관의 설립운영 관리주체에 따라 운영자금 조달방법별 조달비율과 이들이 경영성과에 미치는 영향을 살펴보고자 의료기관 회계정보 공시시스템에 등록된 재무정보를 이용하여 분석하였다. 분석방법은 설립운영 관리주체별 차이비교를 위하여 분산분석을 실시하였으며, 운영자금 조달방법별 조달비율이 경영성과에 미치는 영향은 로지스틱 회귀분석과 회귀분석을 실시하였다. 연구결과, 운영자금 대비 총수익 비율은 설립운영 관리주체에 따라 유의한 차이가 있었다. 그리고 운영자금 조달방법별 조달비율은 경영결과(적자, 흑자)와 유의하게 인과관계가 있는 것으로 확인되었으며, 운영자금 조달방법 조달비율이 경영성과에 미치는 영향은 설립운영 관리주체에 따라 차이가 있었다. 이상의 결과 의료기관의 운전자금 관리는 운영자금에 대한 수익의 비율을 고려한 비용관리를 우선적으로 적용하고 그 다음으로 내부운영자금을 활용하는 방안의 적용이 적절할 것으로 사료된다.