• 한국재료학회지
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• 제15권12호
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• pp.824-828
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• 2005

In this study the effect of the content of $TiB_2$ on wear properties was investigated. $Cu-TiB_2$ composites have been fabricated by hot extrusion. Sliding wear tests were peformed by a pin-on-disk type wear test machine under dry condition and loads varied with from 20N to 80N at sliding speed 3.5Hz. The test results showed that the wear losses and the friction coefficients decreased with increasing $Cu-TiB_2$ volume fraction and increasing the size of $Cu-TiB_2$ particle. Wear property of $10{\mu}m,\;5 vol\%\; TiB_2$ specimen was excellent all of the wear specimens. It is thought that the increase of plastic flow resistivity due to uniform distribution of $10{\mu}m,\;5 vol\%\; TiB_2$ wear specimen would improve wear property. The worn surface and wear debris were examined by optical microscope and scanning electron microscope.

• 동의생리병리학회지
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• 제26권5호
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• pp.610-614
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• 2012

This study was done to identify correlates of carotid artery ultrasonography's measurement and Inyoung pulse in college students. We measured the amplitude of Inyoung pulse, Chongu pulse, ratio of Inyoung to Chongu and ratio of Chongu to Inyoung on 30 college students. Also, We measured the Distance, Diameter), RI(resistivity index), S/D(systolic, diastolic ratio), PI(pulsatility index), PSV(peak systolic velocity), EDV(End diastolic velocity), Vmean using carotid artery ultrasonography. The data was analyzed by Pearson's correlation coefficient using SAS program. The results were as follow. Results showed a positive correlation between Inyoung pulse and diameter by carotid artery. It showed a positive correlation between Inyoung pulse and S/D. Also, It showed a positive correlation between Inyoung pulse and PSV. As a result, the strength of Inyoung pulse related with the diameter of carotid artery and blood flow velocity.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 춘계학술대회 논문집 방전 플라즈마 유기절연재료 초전도 자성체연구회
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• pp.76-81
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• 2004

This paper presents the results of spectral analysis of leakage current waveforms on contaminated insulators under various fog and environment conditions(salt fog, clean fog, rain) The larger the leakage current during 200ms, the higer the power spectrum at 60Hz. For almost equal maximum current during 200ms, however, the spectrum at 60hz and the odd order harmonics increase emphatically when discharges occur continuously for several half-waves. If contaminated insulators suffers from high salt-density fog, the leakage current occurs with high crest value intermittently, results in the low spectrum. Analysis of leakage current data showed that this electrical activity was characterized by transient arcing behavior contaminants are deposited on the insulator surface during salt fog tests. This provides a path for the leakage current to flow along the surface of the insulator. It is important to have an indication of the pollution accumulation in order to evulate the test performance of a particular insulator. If the drop in surface resistivity is severe enough, then the leakage current may escalate into s service interrupting flashover that degrade power quality.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.376-377
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• 2006

This paper presents the characteristics of Ta-N thin film strain gauges that are suitable for harsh environemts, which were deposited on thermally oxidized Si substrates by DC reactive magnetronsputtering in an argon-nitrogen atmosphere (Ar-$N_2$ (4 ~ 16 %)). These films were annealed for 1 hr in $2{\times}10^{-6}$ Torr in a vacuum furnace with temperatures that ranged from 500 - $1000^{\circ}C$. The optimized deposition and annealing conditions of the Ta-N thin film strain gauges were determined using 8 % $N_2$ gas flow ratio and annealing at $900^{\circ}C$ for 1 hr. Under optimum formation conditions, the Ta-N thin film strain gauges obtained a high electrical resistivity, ${\rho}\;=\;768.93\;{\mu}{\Omega}{\cdot}cm$, a low temperature coefficient of resistance, $TCR\;=\;-84\;ppm/^{\circ}C$ and a high temporal stability with a good longitudinal gauge factor, GF=4.12. The fabricated Ta-N thin film strain gauges are expected to be used inmicromachined pressure sensors and load cells that are operable under harsh environments.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.356-357
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• 2006

Tin oxide thin films have been prepared on display glass from mixtures of dibutyl tin diacetate as a tin source, oxygen as an oxidant by Plasma Enhanced Chemical Vapor Deposition (PECVD) method. The relationships between the properties of tin oxide thin films and various reaction parameters such as the deposition temperature, deposition time and the oxygen gas flow rate were studied. As the deposition temperature increased, the texture plane of $SnO_2$ changed from (200) plane to denser (211) and (110) planes. Lower deposition temperature and thinner thickness of deposited film led to decreasing grain size, surface roughness and electrical resistivity of the formed thin films at $325{\sim}425^{\circ}C$. The properties of fabricated $SnO_2$ films are highly changed with variations of substrate temperature and deposition time.

• 한국표면공학회지
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• 제40권4호
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• pp.165-169
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• 2007

Compared to conventional Indium Tin Oxide (ITO) film deposition methods, cesium (Cs) assisted sputtering offers higher film characteristics in terms of electrical, mechanical and optical properties. However, it showed highly non-linear characteristics between process input factors and equipment responses. Therefore, to maximize film quality, optimization of manufacturing process is essential and process characterization is the first step for process optimization. For this, we designed 2 level design of experiment (DOE) to analyze ITO film characteristics including film thickness, resistivity and transmittance. DC power, pressure, carrier flow, Cs temperature and substrate temperature were selected for process input variables. Through statistical effect analysis methods, relation between three types of ITO film characteristics and five kinds of process inputs are successfully characterized and eventually, it can be used to optimize Cs assisted sputtering processes for various types of film deposition.

• 한국결정성장학회지
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• 제8권4호
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• pp.599-604
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• 1998

본 논문은 PZT 박막의 기억소자 응용을 위한 Pt 그리고 RuO2 박막을 조사하였다. 초고주파 마그네트론 스퍼터링 방법을 이용하여 하부전극을 성장하였으며, 조사된 실험변수는 기판온도, 가스 부분압, RF 전력 그리고 후열처리 등이다. 기판온도는 Pt, $RuO_2$박막의 결정구조 뿐만 아니라 표면구조 및 비저항 성분에 크게 영향을 주었다. Pt 박막의 XRD 분석으로 기판온도가 상온에서 $200^{\circ}C$까지는 (111) 그리고 (200) 면이 혼재하는 결과를 보였으나 $300^{\circ}C$에서는 (111) 면으로 우선 방위 성장 특성을 보였다. XRD와 AFM 해석으로부터 Pt 박막 성장시 기판온도 $300^{\circ}C$, RF 전력 80W가 추천된다. 산소 분압비를 0~50%까지 가변하여 조사한 결과 산소가 5% 미만으로 공급되면 Ru 금속이 성장되고, 산소 분압비가 10 ~40%까지는 Ru와 $RuO_2$ 상이 공존하였으며 산소 분압비가 50%에서는 순수한 $RuO_2$상만이 검축되었다. 이 결과로부터 RuO2/Ru 이층 구조의 하부전극 형성이 산소 가스 부분압을 조절하여 한번의 공정으로 성장 가능하며, 이런 구조를 이용하면 금속의 낮은 비저항을 유지하면서도 PZT 박막의 산소 결핍에 의한 기억소자의 피로도 문제를 완화할 것으로 사료된다. 후 열처리 온도를 상온에서부터 $700^{\circ}C$까지 증가할 때 Pt와 $RuO_2$의 비저항 성분은 선형적 감소 추세를 보였다. 본 논문은 강유전체 기억소자 응용을 위한 최적화된 하부전극 제적조건을 제시한다.

• Journal of Radiation Protection and Research
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• 제24권2호
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• pp.73-86
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• 1999

현재 경수로형 원자력발전소의 일차계통 냉각수 정화를 위해 사용되는 이온교환방법은 제염효과가 우수하고 공정이 단순하며 조작이 간편하기 때문에 광범위하게 활용되고 있으나 비금속성분도 함께 제거하여 수지의 수명이 단축되고 폐이온교환수지가 발생되는 단점이 있다. 본 연구에서는 일차계통 냉각수 정화를 위해 사용되는 이온교환수지의 대체공정으로서 전기투석과 이온교환이 결합된 전기탈이온법의 사용가능성을 조사하기 위해 모의 용액을 이용하여 다양한 실험조건하에서 수행하였다. 실험결과 유입유량이 증가할수록 제거율은 증가하고 전력소모는 감소하였다. 금속성분 제거율에서 제염계수 1000으로 일정한 경향을 나타내었으며 전력소모 면에서는 TDS 3 ppm이하를 기준으로 유입유량이 $2.0{\ell}/min$일 때 $40.3mWh/{\ell}$ 이었다. 유입유속이 동일한 조건에서는 희석실에 채운 이온 교환수지의 함량이 증가할수록 금속성분 제거율과 전력소모에서 효과적인 것으로 평가되었다. 이온 교환수지를 채운 전기탈이온 공정은 이온교환수지 자체에 의한 수리적 저항과 현탁질에 의한 수지의 오염으로 인해 운전이 계속될수록 유량이 감소하게 된다. 이러한 단점을 극복하기 위해 이온교환수지 대신 이온전도성 스페이서를 설치하여 실험한 결과 유입유량 문제는 해결할 수 있었으나 전력소모와 금속성분 제거율 및 전류효율 면에서 비효율적인 것으로 평가되었다. 전기탈이온 공정의 연속운전에서도 금속성분 제거율에서 제염계수가 1000으로 안정적인 수준을 유지하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.151-151
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• 2009

Recently, there has been increasing interest in amorphous oxide semiconductors to find alternative materials for an amorphous silicon or organic semiconductor layer as a channel in thin film transistors(TFTs) for transparent electronic devices owing to their high mobility and low photo-sensitivity. The fabriction of amorphous oxide-based TFTs at room temperature on plastic substrates is a key technology to realize transparent flexible electronics. Amorphous oxides allows for controllable conductivity, which permits it to be used both as a transparent semiconductor or conductor, and so to be used both as active and source/drain layers in TFTs. One of the materials that is being responsible for this revolution in the electronics is indium-zinc-tin oxide(IZTO). Since this is relatively new material, it is important to study the properties of room-temperature deposited IZTO thin films and exploration in a possible integration of the material in flexible TFT devices. In this research, we deposited IZTO thin films on polyethylene naphthalate substrate at room temperature by using magnetron sputtering system and investigated their properties. Furthermore, we revealed the fabrication and characteristics of top-gate-type transparent TFTs with IZTO layers, seen in Fig. 1. The experimental results show that by varying the oxygen flow rate during deposition, it can be prepared the IZTO thin films of two-types; One a conductive film that exhibits a resistivity of $2\times10^{-4}$ ohm${\cdot}$cm; the other, semiconductor film with a resistivity of 9 ohm${\cdot}$cm. The TFT devices with IZTO layers are optically transparent in visible region and operate in enhancement mode. The threshold voltage, field effect mobility, on-off current ratio, and sub-threshold slope of the TFT are -0.5 V, $7.2\;cm^2/Vs$, $\sim10^7$ and 0.2 V/decade, respectively. These results will contribute to applications of select TFT to transparent flexible electronics.

• 한국재료학회지
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• 제21권5호
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• pp.255-262
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• 2011

This paper has relatively high technical standard and experimental skill. The fabrication of TCO film with high transparency, low resistance and low chromaticity require exact control of several competing factors. This paper has resolved these problems reasonably well, thus recommended for publication. Indium tin oxide(ITO) thin films were by D.C. magnetron roll-to-roll sputter system utilizing ITO and $SiO_2$ targets of ITO and $SiO_2$. In this experiment, the effect of D.C. power, winding speed, and oxygen flow rate on electrical and optical properties of ITO thin films were investigated from the view point of sheet resistance, transmittance, and chromaticity($b^*$). The deposition of $SiO_2$ was performed with RF power of 400W, Ar gas of 50 sccm and the deposition of ITO, DC power of 600W, Ar gas of 50 sccm, $O^2$ gas of 0.2 sccm, and winding speed of 0.56m/min. High quality ITO thin films without $SiO_2$ layer had chromaticity of 2.87, sheet resistivity of 400 ohm/square, and transmittance of 88% and $SiO_2$-doped ITO Thin film with chromaticity of 2.01, sheet resistivity of 709 ohm/square, and transmittance of more than 90% were obtained. As a result, $SiO_2$ was coated on PET before deposition of ITO, their chromaticity($b^*$) and transmittance were better than previous results of ITO films. These results show that coating of $SiO_2$ induced arising chromaticity($b^*$) and transmittance. If the thickness of $SiO_2$ is controlled, sheet resistance value of ITO film will be expected to be better for touch screen. A four point probe and spectrophotometer are used to investigate the properties of ITO thin films.