• 한국환경과학회지
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• 제16권6호
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• pp.683-688
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• 2007

In this study, N doped $TiO_2$ (TiO-N) thin film was prepared by DC magnetron sputtering method to show the photocatalytic activity in a visible range. Various gases (Ar, $O_2\;and\;N_2$) were used and Ti target was impressed by 1.2 kW -5.8 kW power range. The hysteresis of TiO-N thin film as a function of discharge voltage wasn't observed in 1.2 and 2.9kW of applied power. Cross sections and surfaces of thin films by FE-SEM were tiny and dense particle sizes of both films with normal cylindrical structures. XRD pattern of $TiO_2$ and TiO-N thin films was appeared by only anatase peak. Red shift in UV-Vis adsorption spectra was investigated TiO-N thin film. Photoactivity was evaluated by removal rate measurement of suncion yellow among reactive dyes. The photodegradation rate of $TiO_2$ thin film on visible radiation was shown little efficiency but TiO-N was about 18%.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2004년도 학술논문집
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• pp.32-42
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• 2004

Recently, plasma surface-cleaning or surface-etching techniques have been focused in respect of the decontamination of spent or used nuclear parts and equipment. In this study the removal rate of metallic cobalt surface is experimentally investigated via its surface etching rate with a $CF_4-o_2$mixed gas plasma. Experimental results reveal that a mixed etchant gas with about 80% $CF_4$-20% $O_2$ (molar) gives the highest reaction rate and the rate reaches 0.06 ${\mu}m$/min at $380^{\circ}C$ and ion-assisted etching dramatically enhances the surface reaction rate. With a negative 300 V DC bias voltage applied to the substrate, the surface reaction initiation temperature lowers and the rate increases about 20 times at $350^{\circ}C$ and up to 0.43 ${\mu}m$/min at $380^{\circ}C$, respectively. Surface morphology analysis confirms the etching rate measurements. Auger spectrum analysis clearly shows the adsorption of fluorine atoms on the reacted surface. From the current experimental findings and the results discussed in previous studies, mechanistic understanding of the surface reaction, fluorination and/or fluoro-carbonylation reaction, is provided.

• 한국기계가공학회지
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• 제13권2호
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• pp.89-93
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• 2014

Variable polarity (VP) arc welding is known as an effective solution for aluminum thanks to the cleaning effect, which means oxide removal, during the DCEP (direct current electrode positive) period. In this research, VP GTAW (gas tungsten arc welding) is adopted for lap joint fillet welding of 3mm thickness 5052 aluminum alloy. Various welding currents and DCEP duty cycles are applied as welding conditions with a fixed welding speed to investigate the influence of DCEP characteristics on weld bead formation. Results show a tendency of higher heat input for higher DCEP duty cycle, which result does not follow conventional arc theory because it is known that DCEN (DC electrode negative) polarity is more efficient for heat input than is DCEP. This phenomenonhas recently been reported by several VP-GTA researchers and is still controversial because the mechanism of oxide removal is not yet clear except for the previous, well-known idea of "ion bombardment", which cannot explain the situation. Finally, proper usage conditions for VP-GTAW are suggested; then, further, related theoretical topics in the field of cathode physics are brieflyintroduced.

• 방송공학회논문지
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• 제21권2호
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• pp.261-267
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• 2016

본 논문에서는 타이밍 오프셋 보상을 위한 위상 전 왜곡 기법, 파일럿 성분 추정과 제거를 위한 직류 제거기, 송수신 신호 사이의 상관도를 기반으로 귀환 신호의 지연 시간을 추정하는 기법을 이용한 DAB(Digital Audio Broadcasting)용 간섭 제거 기반 동일 채널 중계기를 제안하고, 이를 ATSC(Advanced Television Systems Committee)시스템에 적용한다. 제안한 간섭 제거 기반의 동일 채널 중계기는 주송신 신호보다 간섭 신호가 더 큰 환경에서의 간섭 제거 능력이 확인되었으며, 이에 따라 중계기의 송출 능력의 개선, 짧은 처리 지연 시간과 더불어 양호한 신호 품질이 얻어짐을 시뮬레이션을 통하여 확인한다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제12권2호
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• pp.37-46
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• 2007

본 연구에서는 플라스틱과 Woodchip을 주원료로 하여 복합플라스틱계 담체를 개발하고 성능평가를 실시하였다. 개발담체는 기존상용화 담체에 비하여 처리효율 및 미생물 부착성 등은 유사하였으나, 경제적인 측면에서 우수한 것으로 평가되었다. 담체의 성능평가는 Lab scale의 바이오트리클링필터에 개발담체를 충진하여 톨루엔과 황화수소를 대상으로 제거효율 및 운전인자 등을 평가하였다. 본 연구에서 톨루엔 제거효율은 가스유입량 $1.5\;m^3/hr$, 유입농도 260ppm, 공탑체류시간 42s 운전조건에서 90% 이상으로 높게 나타내었으며, 톨루엔 최대제거능은 $77\;g/m^3{\cdot}hr$이었다. 황화수소와 톨루엔 동시제거 실험에서는 $H_2S$와 톨루엔이 효과적으로 제거되었다. $H_2S$의 최대제거능은 $100\;g-S/m^3{\cdot}hr$이었으며, $H_2S$ 농도가 100 ppm까지는 톨루엔제거에 영향을 주지 않았으나 $H_2S$ 농도가 증가함에 따라 톨루엔 제거효율은 감소되었다.

• 한국컴퓨터정보학회논문지
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• 제19권5호
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• pp.43-52
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• 2014

최근, 다양한 형태의 웨어러블 컴퓨팅 디바이스와 이에 따른 응용 프로그램이 개발되고 있으며, 이들 중에서 헬스 케어의 한 영역으로 웨어러블 컴퓨팅 디바이스를 이용하여 개인의 운동량은 측정하는 다양한 연구가 진행되고 있다. 본 논문에서는 가장 기초적인 운동인 걸음걸이 측정 알고리즘으로 중력 제거 및 백터 회전(Gravity Removal and Vector Rotation) 알고리즘을 제안하고, 이를 위한 실험으로 보행 또는 주행 중인 개인의 다양한 위치에 부착한 웨어러블 디바이스에 장착된 3축 MEMS 가속도 센서로부터 획득된 가속도 값을GRVR 알고리즘을 이용하여 걸음 수를 측정한다. GRVR은 가속도 센서로 획득된 3축 가속도 값으로 부터 중력에 의한 가속도 분은 저대역 필터를 이용하여 제거 하고, 이 후 각각의 가속도 값에서 직류 성분 제거 및 센서 축 회전 보상인 GRVR 알고리즘으로 보행 혹은 주행 중에 순수하게 걸음걸이에 의하여 발생하는 가속도 변화분 만을 추출한다. 실험 결과로 웨어러블 디바이스를 개인의 허리 중앙 혹은 우측에 부착한 경우 GRVR 알고리즘을 이용한 걸음 수 측정은 99.4%의 정확도, 또한 손목에 부착한 경우 상용 3축 가속도 만보계의 83%보다 정확한 91.1%의 정확도를 확인하였다.

• 전자공학회논문지A
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• 제31A권4호
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• pp.63-69
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• 1994

The Ultrahigh Vacuum Electron Cyclotron Resonance Chemical Vapor Deposition(UHV-ECRCVD) system whose base pressure is 1${\times}10^{9}$ torr has been constructed. In-situ cleaning prior to the epitaxial growth was carried out at 56$0^{\circ}C$ by ECR generated uniform hydrogen plasma whose density is $10^{10}/cm{3}$. The natural oxide was effectively removed without damage by applying positive DC bias(+10V) to the substrate. RHEED(Reflection High Energy Electron Diffraction) analysis has been used to confirm the removal of the surgace oxide and the streaky 2$\times$1 reconstruction of the Si surface, and the suppression of the substrate damage is anaylized by X-TEM(cross-sectional Transmission Electron Microscopy). Surface cleaning technique by ECR hydrogen plasma confirmed good quality epitaxial growth at low temperature.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 C
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• pp.1910-1912
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• 1996

This paper presents the results of laboratory experimentals to remove $SO_2$ and $NO_x$ by a pulsed corona discharge in the wire-plate reactor. A rotating spark gap switch was used to generate the pulse by chewing the dc high voltage. Repetition frequency of the pulse was 60Hz and rising time of 50ns. The photo pictures of positive streamer corona taken by ICCD camera, pulse voltage and current were measured using a digital oscilloscope. Simultaneous effects of $C_{2}H_{4}$ injection and heterogeneous chemical reactions on nonthermal plasma process to remove $SO_2$ and $NO_x$ from flue gas were investigated in the present study

• 대한전기학회:학술대회논문집
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• 대한전기학회 2015년도 제46회 하계학술대회
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• pp.547-548
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• 2015

In order to reduce error of the distance relay, we propose an improved fault locating scheme using DC offset removal filter. We were modeled 154 kV transmission system using ATP software in order to demonstrate the usefulness of proposed scheme, and applied to the proposed scheme using collected voltage signal and current signal by line-to-ground fault.

• 한국세라믹학회지
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• 제36권12호
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• pp.1374-1380
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• 1999

The cause of Scond Harmonic Generation (SHG) in thermally poled silica glass is suggested basedon the electrical and dielectric relaxation measurements. The absorption currents as functions of time were measured for various types of silica glasses and analyzed by the theory of Space Charge Polarization. Space charge polarization occurs when an ionic conducting material is subjected to dc electric field with blocking electrode. Thermal poling performed to induce SHG in silica glass is basically identical to the process generating space charge polarization. Hence it was found that gene-ration removal reproduction and temperature dependence of SHG in poled silica is directly related to those of space charge polarization. It turned out that the fundamental parameters governing the SHG in poled silica are charge carrier concentration and mobility. Based on the theory of space charge polarization and experimental results of electrical rela-xation the method to increase the intensity of SHG is proposed.