• 자원환경지질
• /
• 제35권3호
• /
• pp.229-239
• /
• 2002

본 연구는 직류전원(DC)과 zero valent iron(ZVI)을 이용한 실험실 규모의 투수성 반응벽의 모사를 통하여 야외규모의 반응벽 설치시 반응벽과 전원의 설치 위치에 따른 trichloroethylene(TCE)의 처리시 효율성과 반응벽 사용가능 수명을 알아보고자 하였다. 실험결과 12개의 컬럼 type 중 ZVI와 DC를 동시에 사용하는 경우, ZVI만을 사용하는 경우의다. TCE의 환원적 탈염소화는 촉진되었다. 설치된 ZVI충진물질의 양을 고려할 경우, 하류에 ZVI를 설치하고, 전극배열은 상류에 양극을, 하류에 음극을 배열하는 것이 가장 적은 실비로 높은 처리 효율을 나타냄이 밝혀졌다.

• 대한환경공학회지
• /
• 제27권1호
• /
• pp.59-66
• /
• 2005

[ $TiO_2$ ]박막은 DC 마그네트론 스퍼터링법을 이용하여 다양한 스퍼터링 파라미터(전력 $0.6{\sim}5.2\;kw$, 기판온도 실온${\sim}350^{\circ}C$, 산소량 $0{\sim}50\;sccm$($O_2+Ar$ 90 sccm, 압력은 약 1 mtorr))를 통하여 증착되었다. TiO-N박막도 가스의 유량비를 제외하고는 $TiO_2$박막과 같은 스퍼터링 조건하에서 증착되었다. 이러한 스퍼터링 파라미터에서 증착된 박막의 전기적 특성을 분석하기 위하여 시트저항을 측정하였고, 박막의 두께(${\alpha}$-step), 표면 거칠기(AFM), 형성 조직(FE-SEM, XRD)을 분석하여 최적 스퍼터링 파라미터를 도출하였다. 최적 스퍼터링 파라미터에서 제조된($TiO_2$, TiO-N)박막을 이용하여 광활성도를 평가하기 위하여 VOCs물질 중 toluene, 반응성 염료인 Suncion Yellow를 대상 물질로 선정하여 적용성 연구를 수행하였다. 실험에서 광촉매 박막은 적용물질에 대해서 광활성을 양호하게 보였으며, 특히 TiO-N광촉매 박막은 가시광 영역에서도 최대 33%의 톨루엔(5 ppm) 제거 효율을 나타내었다.

• Plant Resources
• /
• 제1권1호
• /
• pp.53-59
• /
• 1998

Laboratory experiments for the removal efficiency of heavy metals in land application of sludge, the accumulation and translocation of heavy metals in x plants after transplanting, and the responses of Minari growth with different ratio of land application of sludge were conducted to determine the potential ability of bioremediation with Minari plants. The removal rate and translocation of copper. zinc. lead. and cadmium in soil and plants were compared after transplanting the Minari plants to soil treated with different ratio of sludge. The removal efficiency of heavy metals in soil incorporated with sludge was different with application ratio, but increased with growing periods of Minari plants. The removal efficiency of Cu, Zn, Pb, and Cd ranged from 67 to 74% from 51% to 63%, from 37% to 71%. and from 15% to 25% after 45 days of transplanting. respectively. The amount removed the copper value. 65.9 mg/kg, observed to be highest in soil incorporated 3% sludge after 45 days. The translocation of Cu. Zn. Pb. and Cd from shoots to roots ranged from 18 to 53%, from 17 to 32%, from 14 to 49%, and from 23 to 38% over growing periods. respectively. In plant responses it appeared to be inhibited the plant growth in the treatment compared with the control at early stage of growth. However, the fresh weights of Minari plant increased from 12.5 to 62.5% in the sludge application after 45 days relative to the control. Therefore the Minari might play a useful role in bioremediation of Cu, Zn, Pb, and Cd in the land application of sludge.

• 한국태양에너지학회 논문집
• /
• 제32권spc3호
• /
• pp.255-261
• /
• 2012

Since PV PCS uses output current sensor for ac output current control, the sensor's sensing value includes unnecessary offset inevitably. If PV inverter is controlled by the included offset value, it's output current will generate DC offset. The DC offset of output current for trans-less PV inverter is fatal to grid, which results in saturating grid side transformer. Usually DSP controller of PV inverter reads several times sensing value during initial operation and, finally, it's average value is used for offset calibration. However, if temperature changes, the offset changes, too. And also, the switch device is not ideal, both each switching element of the voltage drop difference and on & off time delay difference generate DC offset. Thus, to compensate for deadtime and the switch voltage drop, feedback control by output current DC offset should be provided to compensate additional distortion of the output current. The validity of the proposed method is confirmed through PSIM simulation.

• JSTS:Journal of Semiconductor Technology and Science
• /
• 제16권6호
• /
• pp.825-831
• /
• 2016

In this paper, a transimpedance amplifier based on a new DC offset cancellation (DCOC) method is proposed for WCDMA/LTE applications. The proposed method applies a sample and hold mechanism to the conventional DCOC method with a DC feedback loop. It prevents the removal of information around the DC, so it avoids signal-to-noise ratio degradation. It also reduces area and power consumption. It was designed in a $0.13{\mu}m$ deep n-well CMOS technology and drew a maximum current of 1.58 mA from a 1.2 V supply voltage. It showed a transimpedance gain of $80dB{\Omega}$, an input-referred noise current lower than 0.9 pA/${\surd}$Hz, an out-of-band input-referred 3rd-order intercept point more than 9.5 dBm, and an output DC offset lower than 10 mV. Its area is $0.46mm{\times}0.48mm$.

• 전기전자학회논문지
• /
• 제23권1호
• /
• pp.310-313
• /
• 2019

This paper used the majority function to digitally filter back-electromotive force as an explanation of the Brushless DC MOTOR control algorithm. The cause and improvement of motor noise, which are operating in close proximity to high frequency sources, did not use conventional low pass filter and comparator elements. Also, they repeatedly output a noise-free BEMF signal for the input value of the majority detection filtering. These filtering steps can help reduce costs and minimize the area of a PCB by requiring relatively little hardware.

• E2M - 전기 전자와 첨단 소재
• /
• 제11권11호
• /
• pp.17-21
• /
• 1998

The surface potential distribution on insulating polymers was measured by scanning of the probe of an electrostatic voltmeter. The measurements were done for two measured by scanning of the probe of an electrostatis voltmeter. The measurements were done for two cases. In the first case, it was measured on the free surface of insulating films which had been inserted between plane electodes after the removal of the upper brass disk electrode. In the second case, we measured the charging region between a circular and its opposing concentric ring electrodes after the removal of dc ramp voltage in air and nitrogen gas.

• 한국전기전자재료학회논문지
• /
• 제17권2호
• /
• pp.156-161
• /
• 2004

We investigated the effects of oxidizer additive on the performance of Cu-CMP process using commonly used tungsten slurry. In order to compare the removal rate and non-uniformity as a function of oxidizer contents, we used alumina-based tungsten slurry and copper blanket wafers deposited by DC sputtering method. According to the CMP removal rates and particle size distribution, and the microstructures of surface layer by SEM image as a function or oxidizer contents were greatly influenced by the slurry chemical composition of oxidizers. The difference in removal rate and roughness of copper surface are believed to cause by modification in the mechanical behavior of $Al_2$O$_3$abrasive particles in CMP slurry.

• 한국환경보건학회지
• /
• 제23권4호
• /
• pp.121-126
• /
• 1997

Peroxidase as one of the organic enzyme catalyst is useful for the oxidation treatment of various aromatic compounds such as phenols. The peroxidase content of Oenanthe javanica was 24.85 unit/g-fw in leaf, 5.74 unit/g-fw in stem, and 34.69 unit/g-fw in root respectively. The crude peroxidase extracted from Oenanthe javanka can be kept under low temperature (-70$\circ$C) condition for 6 months with the maximum 1% activity reduction. The optimum conditions of removal for 100 ppm phenol was pH 6, hydrogen peroxide 3.5 mM, peroxidase activity 8 unit/ml, temperature 20$\circ$C respectively. In the wide range of concentration from 50 ppm to 750 ppm phenol reveals average 54% removal rate under the same peroxidase activity (8 unit/ml) and different amount of hydrogen peroxide proportional to phenol concentration. Especially at the concentration of 100 ppm the maximum phenol removal rate was 72%.

• 한국작물학회지
• /
• 제39권5호
• /
• pp.480-488
• /
• 1994

White clover는 기존초지에 도입시 정착이 불량한 것이 단점으로 지적되어 왔다. 본시험은 white clover의 발아직후 자엽 및 단엽제거가 건물생산과 형태적 특성에 미치는 영향을 조사하여 기존초지로 도입되는 white clover의 유묘기 관리에 관한 정보를 제공하고자 잎의 크기가 다른 4개 품종(Regal, La. S-1, Huia, S184)을 자엽기에 1개 또는 2개의 자엽을 제거하거나, 단엽기에 단엽, 단엽과 1개의 자엽 또는 단엽과 2개의 자엽을 모두 제거한 후 8주동안 개체당 건물중과 형태적 형질(엽수, 엽면적, 엽병장, 포복경장 및 분지경수)의 변화와 개체당 건물중과 이들 형질과의 관계를 밝히고자 실시하였던 바, 그 결과를 요약하면 다음과 같다. 1. 무탈엽에 비하여 자엽 및 단엽제거는 clover의 개체당 건물중과 형태적 형질을 현저히 감소시켰다. 2. 건물중과 형태적 형질은 단엽기에 단엽과 자엽 제거에 의하여 더욱 감소되고 자엽제거가 많을수록 감소가 큰 것으로 나타났다. 3. 자엽 및 단엽제거 후 생장기간이 증가함으로써 건물중과 형태적 형질이 증가한다 할지라도 포복경장과 분지경수는 처리 6주후부터 급격히 증가하였다. 4. 건물중, 엽면적 및 엽병장은 대엽종일수록 크나, 포복경장, 분지경수 및 엽수는 소엽종일수록 큰 경향을 보였다. 5. 건물중 증가는 엽면적 증가와 밀접한 관련이 있었으나 자엽기에 자엽제거가 단엽기에 단엽과 자엽제거, 그리고 탈엽이 심할수록 증가율(기울기)감소가 큰 것으로 분석되었다.