• 한국응용과학기술학회지
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• 제29권4호
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• pp.653-658
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• 2012

고농도 유기질 폐수처리를 위해 전기화학적 방법의 사용에 있어 관심이 고조되고 있다. 전기화학적 방법의 기술은 음식물폐수 및 공업적 폐수 문제를 해결하는데 이상적 처리 방법이다. 다른 화학적 처리 방법과는 다르게 전기화학적 처리장치는 2차 폐수의 부피를 증가시키지 않고 용수와 유기질 비료로 재활용한다. 전기화학적 방법은 전해부상장치를 무기화학적 약품과 병행하여 더욱 효과적으로 음식물 폐수를 처리한다. 이 연구는 2차 처리로 초음파와 오존처리로 탈색, COD와 BOD가 격감함으로 용수 및 유기질 비료로 활용하도록 실험하였다.

• 한국산학기술학회논문지
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• 제5권6호
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• pp.588-591
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• 2004

축산 폐수처리를 위해 전기화학적 방법의 사용에 있어 관심이 고조되고 있다. 전기화학적 방법의 기술은 축산폐수 및 공업적 폐수 문제를 해결하는데 이상적 처리 방법이다. 다른 화학적 처리 방법과는 다르게 전기화학적계는 2차 폐수의 부피를 증가시키지 않고 용수와 유기질 비료로 활용한다. 전기화학적 방법은 전해부상장치를 무기화학적 약품과 병행하여 더욱 효과적으로 축산폐수를 처리한다. 이 연구는 2차 처리로 초음파와 오존처리로 탈색, COD와 BOD가 격감함으로 용수 및 유기질 비료로 활용하도록 실험하였다.

• 한국주조공학회지
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• 제15권3호
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• pp.283-290
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• 1995

Molybdenum ingot of 50mm in diameter were obtained from sintered Mo bars by EB drip melting technique. Macroscopic observation of EB remelted ingot indicates that coarse and columnar grains grow in the direction parallel to ingot pulling direction. This can be explained by slow solidification (3mm/min), large temperature gradient and heat flow to this direction. The orientation of columnar structure was found to be <110>, <200> and <211> by the analysis of X-ray diffraction patterns. The contents of typical metallic impurities in Mo sintered bar are 1.2ppm Cr, 3ppm Fe, 44ppm Zr, 150ppm W. Most of metallic impurities were reduced below the order of ppm except zirconium and tungsten by the selective evaporation. In the removal of nonmetallic impurities, oxygen and carbon impurities were lowered from 120 to 6ppm and from 157 to 106ppm, respectively, after first melting. Although the purification effect was not significant with the number of remelting, Vickers hardness was reduced from 217 to 195 and 184 in sequence with increasing the number of remelting.

• 대한화학회지
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• 제27권4호
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• pp.268-272
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• 1983

${\beta}$-디페닐글리옥심으로 침윤시킨 폴리우레탄 포옴을 사용하여 수용액에서 Pt(IV) 및 Ni(II) 이온으로부터 Pd(II) 이온의 추출을 시도하였다. Pd(II) 이온은 $0.01{sim}0.05M$ HCl 농도범위에서 정량적으로 추출이 되었으며 반면 같은 농도 범위에서 Pt(IV) 이온은 단지 미량 추출이 되었으나 Ni(II) 이온은 전혀 추출되지 않았다. 따라서 뱃치법에 의하여 $0.01{sim}0.05M$ HCl 용액에서 Pd(II)이온을 Pt(IV) 및 Ni(II)이온으로부터 선택적으로 분리가 가능하였으며 또한 용리법으로 Pd(II)의 제거 및 회수도 가능하였다.

• 마이크로전자및패키징학회지
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• 제12권2호
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• pp.181-186
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• 2005

Polystyrene(PS)과 poly(methyl methacrylate)(PMMA)에 대하여 동일한 계면 특성을 갖는 3-(p-methoxyphenyl)propyltrichlorosilane(MPTS)의 자기조립 단분자막(self-assembled monolayer, SAM) 을 실리콘 웨이퍼 표면에 형성시켜 표면 특성을 개질하였다. 개질된 실리콘 웨이퍼에 PMMA 또는 PS가 원통형 나노구조를 형성하는 PS-b-PMMA 블록공중합체 박막을 코팅하여 원통형 나노구조가 실리콘 웨이퍼 표면에 대하여 수직 배향된 박막을 제조하였다. 수직 원통형 나노구조를 갖는 박막에 자외선 조사와 세척을 통하여 PMMA 블록을 선택적으로 제거하여 수직 나노기공 필름과 수직 나노막대 배열을 제조하였다. 제조된 나노기공 필름은 나노리소그래피 마스크로 사용이 가능하다.

• 대한화학회지
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• 제40권5호
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• pp.347-356
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• 1996

트리플산에 의한 phenylsilane 의 선태적 분해반응에서는 silyltriflate ester 결합을 형성하였다. 1 혹은 2당량배의 트리플산에 의한 $Ph_3SiH$과 carbosilane 고분자$(Ph_2SiCH_2CH_2CH_2)n$의 Ph기 치환반응에서는 1 혹은 2치환 silyltriflate ester 결합을 형성하였으며 이들과 allylmagnesium bromide와의 반응에 의해 이에 상응되는 화합물을 높은 수율로 얻었다. Carbosilane 고분자의 나무가지꼴 실란거대분자를 allylation 과 hydrosilation법에 의해 제3세대(G3)까지 합성하였다.

• Journal of electromagnetic engineering and science
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• 제11권4호
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• pp.239-249
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• 2011

In this paper, we propose a reliable $8{\times}8$ up-down switching polar relay code based on 3GPP LTE standard, motivated by 3GPP LTE down link, which is 30 bps/Hz for $8{\times}8$ MIMO antennas, and by Arikan's channel polarization for the frequency selective fading (FSF) channels with the generator matrix $Q_8$. In this scheme, a polar encoder and OFDM modulator are implemented sequentially at both the source node and relay nodes, the time reversion and complex conjugation operations are separately implemented at each relay node, and the successive interference cancellation (SIC) decoder, together with the cyclic prefix (CP) removal, is performed at the destination node. Use of the scheme shows that decoding at the relay without any delay is not required, which results in a lower complexity. The numerical result shows that the system coded by polar codes has better performance than currently used designs.

• Journal of Electrical Engineering and Technology
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• 제7권3호
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• pp.396-400
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• 2012

Novel fabrication method of nanobridge array of various materials was proposed using suspended silicon nanowire array as a sacrificial template structure. Nanobridges of various materials can be simply fabricated by direct deposition with thermal evaporation on the top of prefabricated suspended silicon nanobridge arrays, which are used as a sacrificial structure. Since silicon nanowire can be easily removed by selective dry etching, nanobridge arrays of an intended material are finally obtained. In this paper, metal nanobridges of Ti/Au, around 50-200 nm in thickness and width, 5-20 ${\mu}m$ in length were fabricated to prove the advantages of the proposed nanowire or nanobridge fabrication method. The nanobridges of Ti/Au after complete removal of sacrificial silicon nanowire template were well-established and bending of nanobridge caused by the tensile stress was observed after silicon removing. Up to 50 nm and 10 ${\mu}m$ of silicon nanowire in diameter and length respectively was also very useful for nanowire templates.

• Membrane and Water Treatment
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• 제6권3호
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• pp.173-187
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• 2015

The goal of present work is the preparation of a novel positively charged nanofiltration (NF) membrane and its development for the cation removal of aqueous solutions. This NF membrane was fabricated by the surface modification of polysulfone (PSf) ultrafiltration support. The active top-layer was formed by interfacial cross-linking polymerization of poly(ethyleneimine) (PEI) with p-xylylene dichloride (XDC) and then quaternized with methyl iodide to form a perpetually positively charged layer. In order to improve the efficiency of nanofiltration membrane, the concentration of PEI, XDC and methyl iodide solutions, PEI coating and cross-linking time have been optimized. As a result, a high water flux and high $CaCl_2$ rejection (1,000 ppm) was obtained for the composite membrane with values of $18.29L/m^2.h$ and 93.62% at 4 bar and $25^{\circ}C$, respectively. The rejections of NF membrane for different salt solutions followed the order of $Na_2SO_4$ < $MgSO_4$ < NaCl < $CaCl_2$. Molecular weight of cut off (MWCO) was calculated via retaining of PEG solutions with different molecular weights that finally, it revealed the Stokes and hydrodynamic radius of 1.457 and 2.507 nm on the membrane selective layer, respectively. The most efficient positively charged nanofiltration membrane exhibited a $Ni^{2+}$ rejection of 96.26% for industrial wastewater from Shamse Hadaf Co. (Kashan, Iran).

• Carbon letters
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• 제9권1호
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• pp.23-27
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• 2008

The adsorption and reduction of Cr (VI) to Cr (III) by surface modified activated carbon (AC) in an aqueous solution was studied. The effects of surface modifications on the properties of the carbons were investigated by the analysis of specific surface area, carbon surface pH, acid/base surface values and functional groups. In order to understand the Cr(VI) adsorption and reduction ratio from Cr(VI) to Cr(III), the Cr adsorption capacity of AC was also measured and discussed by using inductively coupled plasma and UV spectrophotometer. The modifications bring about substantial variation in the chemical properties whereas the physical properties such as specific surface area, pore volume and pore size distribution nearly were not changed. Total Cr adsorption efficiency of as-received activated carbon (R-AC) and nitric acid treated activated carbon (N1-AC and N2-AC) were recorded on 98.2, 99.7 and 100%. Cr(III) reduction efficiency of R-AC increased largely from 0.4% to 28.3% compared to N1-AC and N2-AC.