• 자원리싸이클링
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• 제17권3호
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• pp.3-9
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• 2008

하수슬러지 소각재를 대상으로 화학 조성과 물리화학적 물성을 측정하고 재활용을 위한 경량재료 제조실험을 수행하였다. 경량재료는 하수슬러지 소각재를 원료로 하여 경량충진제와 무기바인더를 첨가하여 성형 및 소성하는 방법으로 제조하였으며, 제조 조건에 따른 비중과 압축강도 변화를 측정하였다. 비산재의 pH 경우 배기가스 중화를 위한 알칼리 첨가로 인하여 알칼리성인 pH 8.69로 나타났으나 바닥재는 중성인 pH 6.48이었다. 공정시험법에 근거하여 하수슬러지 소각재에 대한 중금속 용출실험 결과, Cd, Cu, Pb, As, Cr의 5개 원소 모두에 대하여 용출량이 검출한계치 이하로 나타났다. 동일한 혼합비율의 경우 비산재를 사용한 경량재료 시편의 압축강도가 바닥재에 비해 높게 나타나 비산재를 원료로 사용하는 것이 보다 효과적임을 알 수 있었다.

• Journal of Applied Biological Chemistry
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• 제53권3호
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• pp.132-138
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• 2010

B. pseudomycoides로 부터 alanine racemase로 추정되는 유전자를 분리한 다음 6xHistidine 이 결합된 pET-21 운반체를 이용하여 E. coli BL21(DE3)에서 발현시키고 생화학 특성을 조사하였다. 재조합된 alanine racemase는 affinity chromatography를 이용하여 분리하였으며 SDS-PAGE 분석에서 약 46 kDa의 단일밴드를 나타내었다. 분리된 효소는 여러 아미노산 중에서 L-alanine에 대하여 가장 높은 활성도를 보이고 D-alanine에 대하여 두번째로 높은 활성도를 보였다. 따라서 분리된 효소는 alanine racemase로 판단되었다. 분리된 효소는 D-cysteine에 하여 상당히 저해가 되었다. 효소의 최적 활성도는 pH 9.0 근처에서 관찰되었고 산성의 조건보다는 알칼리의 조건에서 보다 안정하였다. 보효소인 PLP 0.3mM의 첨가에 의해 효소의 활성도는 약 70% 가량 증대되었다.

• 대한방사선기술학회지:방사선기술과학
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• 제38권4호
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• pp.337-345
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• 2015

2011년 발생한 후쿠시마 원전 사고 이후, 국민의 방사선에 대한 관심이 급속히 증가하였으며 그에 따른 방사선의 위험성에 대한 우려 또한 증대되고 있다. 따라서 본 연구에서는 일상생활 속에서 접할 수 있는 물질의 방사선 및 환경방사선을 측정하여 그 실태를 알아봄으로써, 국민의 방사선에 대한 올바른 이해를 돕고 더불어 방사선 피폭에 대한 우려를 경감하고자 하였다. 본 연구에서는 'Captus - 3000 갑상샘 섭취율 측정장치'를 이용하여 일상생활에서 쉽게 접할 수 있는 17가지 시료들을 대상으로 방사능을 측정하였으며, 측정에는 우물형 계수기를 이용하였다. 측정한 시료로는 연탄, 표고버섯, 명태, 전지분유, 알카라인 건전지, 단추형 건전지, 표토, 아스팔트, 휘발유, 솔잎, 현무암, 흑연(석탄), 고추냉이, 천일염, 담배, 맥주, 참치(캔)으로 선정하였고 각각의 시료에 대하여 토양자원, 수자원, 식품, 기타자원으로 분류하였다. 수자원으로 선정한 맥주는 식품으로 분류하였다. 또한 우물형 계수기의 감도측정을 위하여 기준선원으로 선 선원 형태의 137Cs을 이용하였다. 우물형 계수기로 137Cs 선선원의 계수값(cpm)을 측정한 후, 각각의 시료에서 얻은 계수값과 스펙트럼을 분석하였고, 식품의 경우에는 식약처의 방사능 허용기준단위인 Bq/Kg으로 환산하여 그 안전성을 판단하였다. 실험 결과, 측정한 시료들 중 유의할 만한 시료들을 집단 A로 분류하였고, 그 외에 배후 방사능과 큰 차이를 보이지 않은 시료들을 집단 B로 분류하였다. 집단 A의 경우 배후 방사능에 비해 알카라인 건전지가 7.67 %, 단추형 건전지가 4.65 %, 아스팔트가 8.03 %, 표토가 3.76 %, 연탄이 7.46% 높은 값을 보였다. 사용된 시료들 모두에서 측정된 방사능이 생활용품의 일부와, 식품의 경우에는 식약처에서 제시한 방사능 허용기준치 이내에 들어 있음을 확인하였다.

• 펄프종이기술
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• 제48권3호
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• pp.66-72
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• 2016

The applicability of rice husk fiber as a raw material for eco-friendly pulp mold was evaluated in this study. The higher demand of environmental friendly packaging material resulted in the more interest for the natural fiber based pulp mold. The rice husk which is an abundant agricultural byproduct in Asia could be defiberized by an alkaline digestion process. The changes in the pulp mold making process and the properties of pulp mold by the addition of the rice husk were investigated. The addition of rice husk fiber to the pulp mold made with OCC or UBKP resulted in the increase in drainage at the pulp mold forming process. In case of UBKP pulp mold, the addition of rice husk fiber increased the drying efficiency after pulp mold forming since the structure of pulp mold became more bulkier by the addition of the rice husk fiber. Those results showed the rice husk fiber could be applied to the pulp mold manufacturing as one of the eco-friendly natural fiber resources.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 춘계학술대회 논문집 전자세라믹스 센서 및 박막재료 반도체재료 일렉트렛트 및 응용기술
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• pp.1-5
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• 2000

As the semiconductor devices are miniaturized, the number of the unit cleaning processes increases. In order to processes by conventional RCA cleaning process, the consumption of volume of liquid chemical and DI water became huge. Therefore, the problem of environmental issues are evolved by the increased consumption of chemicals. To resolve this matter, an advanced cleaning process by Electrolyzed Water was studied in this work. The electrolyzed water was made by an electrolysis equipment which was composed of three chambers of anode, cathode, and middle chambers. In the case of electrolyzed water with electrolytes in the middle chamber, oxidatively acidic water of anode and reductively alkaline water of cathode were obtained. The oxidation/reduction potentials and pH of anode water and cathode water were measured to be +l000mV and 4.8, and -530mV and 6.3, respectively. The Si-wafers contaminated with metallic impurities were cleaning with the electrolyzed water. To analysis the amounts of metallic impurities on Si-water surfaces, ICP-MS(Inductively Coupled Plasma-Mass spectrometer) was introduced. From results of ICP-MS measurements, it was concluded that the ability of electrolyzed water was equivalent to that of the conventional RCA cleaning.

• 한국전기전자재료학회논문지
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• 제33권5호
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• pp.367-372
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• 2020

As packaging processes for atomic gyroscope vapor cells, the glass tube tip-off process, anodic bonding, and paste sealing have been widely studied. However, there are stability issues in the alkali metal which are caused by impurity elements and leakage during high-temperature processes. In this study, we investigated the applicability of a vapor cell low-temperature packaging process by depositing Au on a Pyrex cell in addition to forming an Au-Sn thin film on a cap to cover the cell, followed by laser irradiation of the Au/Au-Sn interface. The mechanism of the thin film bonding was evaluated by XRD, while the packaging reliability of an Ne gas-filled vapor cell was characterized by variation of plasma discharge behavior with time. Furthermore, we confirmed that the Rb alkaline metal inside the vapor cell showed no color change, indicating no oxidation occurred during the process.

• Journal of Microbiology and Biotechnology
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• 제22권8호
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• pp.1084-1091
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• 2012

Xylooligosaccharides are functional foods mainly produced during the hydrolysis of xylan by physical, chemical, or enzymatic methods. In this study, production of xylobiose was investigated using oil palm empty fruit bunch fiber (OPEFB) as a source material, by chemical and enzymatic methods. Xylanase-specific xylan hydrolysis followed by xylobiose production was observed. Among different xylanases, xylanase from FXY-1 released maximum xylobiose from pretreated OPEFB fiber, and this fungal strain was identified as Aspergillus terreus and subsequently deposited under the accession Number MTCC- 8661. The imperative role of lignin on xylooligosaccharides enzymatic synthesis was exemplified with the notice of xylobiose production only with delignified material. A maximum 262 mg of xylobiose was produced from 1.0 g of pretreated OPEFB fiber using FXY-1 xylanase (6,200 U/ml) at pH 6.0 and $45^{\circ}C$. At optimized environment, the yield of xylobiose was improved to 78.67 g/100 g (based on xylan in the pretreated OPEFB fiber).

• 한국전기전자재료학회논문지
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• 제26권2호
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• pp.140-143
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• 2013

Lowering surface reflectance of silicon wafer by texturization is one of the most important processes to improve the efficiency of silicon solar cells. Generally, the texturing of crystalline silicon was carried out using alkaline solution. The average reflectance of this method was 11% at the wavelength between 400 and 1,000 nm. In this study, the wafers were first texturing by NaOH solution at $80^{\circ}C$ for 35 min. Then the wafers were texturing by $SF_6$ and $O_2$ plasma in RIE (Reactive Ion Etching). The average reflectance of two step texturing was reduced to below 5% at the wavelength between 400 and 1,000 nm.

• 한국전기전자재료학회논문지
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• 제14권5호
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• pp.423-429
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• 2001

PbS, CuS and (Pb,Cu)S thin films were chemically deposited on glass from alkaline baths containing lead acetate, copper chloride, thiourea and triethanolamine. The deposition, optical, resistivity and thermal electric properties of these films were studied. PbS thin films showed a hexagonal structure and CuS thin films showed amorphous. The crystalline of (Pb,Cu)S thin films was obtained by heat treatment at 200$\^{C}$ and the deposition ratio of Pb to Cu showed 7:3. The energy gap of PbS, CuS and (Pb,Cu)S thin films were 1.7, 2.1 and 2.4 eV, respectively. Sheet resistance of PbS thin films was less affected on thermal annealing, but hose of (Pb,Cu)S and CuS thin films were more reduced about 3 orders of magnitude. All of those thin films indicated p type semiconductor in temperature ranging 30$\^{C}$ to 150$\^{C}$.

• 한국전기전자재료학회논문지
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• 제29권8호
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• pp.455-460
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• 2016

A textured front surface is required in high efficiency silicon solar cells to reduce reflectance and to improve light trapping. Wet etching with alkaline solution is usually applied for mono crystalline silicon solar cells. However, alkali texturing method is not appropriate for multi-crystalline silicon wafers due to grain boundary of random crystallographic orientation. Accordingly, acid texturing method is generally used for multi-crystalline silicon wafers to reduce the surface reflectance. To reduce reflectivity of multi-crystalline silicon wafers, double texturing method with combination of acid and reactive ion etching is an attractive technical solution. In this paper, we have studied to optimize RIE condition by different RF power condition (100, 150, 200, 250, 300 W).