• Macromolecular Research
• /
• 제14권2호
• /
• pp.173-178
• /
• 2006

Poly(3-(2-hydroxyethyl)thiophene) (P3HET) was synthesized using oxidative coupling polymerization that involved the protecting and deprotecting of hydroxyl groups but not the chlorine substitution or oxidative decomposition of the hydroxyl groups. The resulting P3HET exhibited good solubility in aprotic solvents, in contrast to the insoluble polymer product synthesized directly from the monomer, 3-(2-hydroxyethyl)thiophene (3HET). P3HET had low conductivity due to the strong hydrogen bonding of its hydroxyl groups. The ester-functionalized poly(3-(2-acetoxyethyl)thiophene) and poly(3-(4-pentylbenzoateethyl)thiophene) were also prepared with reasonably high molecular weights in order to examine how this functionalization modified the physical and chemical properties of P3HET. These polymers exhibited better solubility in common solvents and higher conductivity than P3HET. All these polymers exhibited bathochromic shifts of their film state absorption maxima with respect to those found in the UV-visible spectra of their solution phases. The extent of the bathochromic shift was found to vary with the lengths of the side chains of the ester-functionalized polymers.

• 한국토양비료학회지
• /
• 제44권1호
• /
• pp.146-159
• /
• 2011

The continuous increase in the production of metals and their subsequent release into the environment has lead to increased concentration of these elements in agricultural soils. Because microbes are involved in almost every chemical transformations taking place in the soil, considerable attention has been given to assessing their responses to metal contaminants. Short-term and long-term exposures to toxic metals have been shown to reduce microbial diversity, biomass and activities in the soil. Several studies show that microbial parameters like basal respiration, metabolic quotient, and enzymatic activities, including those of oxidoreductases and those involved in the cycle of C, N, P and other elements, exhibit sensitivity to soil metal concentrations. These have been therefore, regarded as good indices for assessing the impact of metal contaminants to the soil. Metal contamination has also been extensively shown to decrease species diversity and cause shifts in microbial community structure. Biochemical and molecular techniques that are currently being employed to detect these changes are continuously challenged by several limiting factors, although showing some degree of sensitivity and efficiency. Variations and inconsistencies in the responses of bioindicators to metal stress in the soil can also be explained by differences in bioavailability of the metal to the microorganisms. This, in turn, is influenced by soil characteristics such as CEC, pH, soil particles and other factors. Therefore, aside from selecting the appropriate techniques to better understand microbial responses to metals, it is also important to understand the prevalent environmental conditions that interplay to bring about observed changes in any given soil parameter.

• 한국광학회지
• /
• 제9권3호
• /
• pp.162-167
• /
• 1998

CF4 이온빔보조증착법으로 굴절률이 유리보다 낮은 SiOxFy 박막을 제작하고 광학적, 구조적 및 화학적 특성을 연구하였다. End-Hall 이온총의 양극전압의 간소에 따라 SiOxFy 박막의 굴절률은 1.455까지 변하였으며, 이온빔 전류밀도의 증가에 따라서 굴절률은 1.462에서 1.430까지 변하였다. XPS와 FT-IR 분석으로부터 SiOxFy 박막의 F양이 증가함에 따라 Si-O 결합은 파수가 높은 쪽으로 이동하였고, F이 약 8.5at.%인 SiOxFy 박막은 OH 결합이 매우 감소하였으여, 박막 표면의 F이 H2O와 결합하여 탈착되는 것을 알았다. SiOxFy 박막의 응력은 0.3GPa 이하의 압축응력이었으며, 결정구조는 비정질이었다. SiOxFy 박막의 응용으로서 SiOxFy 박막과 흡수층 Si 박막을 이용하여 2층 반사방지막을 제작하였다.

• 대한인간공학회지
• /
• 제22권3호
• /
• pp.13-26
• /
• 2003

The purpose of this study is to investigate the present conditions of the night work and shift work systems in the heavy chemical industrial complexes found in Changwon, Masan, and Chinhae. Korea. We will attempt to define and classify their problems; and to discover further ways to improve their systems. Fifty production factories were carefully selected as the subjects for this study. The shift systems were classified into five categories. The consecutive night shifts were long in almost all cases with 6 days (36 factories) and 7 days (13 factories). It was found that the night work of about] 2 hours continues for a long period in the weekly rotation full-day shift systems and the night-including non-full-day shift systems, and there was no holiday during a shift cycle in the continuous full-day shift systems. The work time in most shift systems was longer than the 44-hours/week permitted by Korean law. Considering the characteristics of these various types of shift systems, the most essential thing to reduce the shift workers' work load may be to shorten their working hours and improve the schedule of shift systems. It is highly recommended as a fundamental solution. to reduce the portal-to-portal hours from 12 to 8 in the night-including non-full-day shift systems and the weekly rotation full-day shift systems, and at least to employ a 4-team 3-shift system in the continuous full-day shift systems. In addition to this, it should from now on be taken as a goal to restructure the types of shift systems by taking such measures as avoiding continuous night work if possible, providing sufficient off-duty intervals both before and after night shift, providing increased opportunities for workers to nap during night work. and increasing the number of holidays.

• 한국환경과학회지
• /
• 제26권9호
• /
• pp.1013-1021
• /
• 2017

Exposure to Diesel Particulate Matter (DPM) potentially causes adverse health effects (e.g. respiratory symptoms, lung cancer). Due to a lack of data on Elemental Carbon (EC) exposure levels in underground copper ore mining (unlike other underground mining industries such as non-metallic and coal mining), this case study aims to provide individual miners' EC exposure levels, and information on their work practices including use of personal protective equipment. EC measurement was carried out during different work activities (i.e. drilling, driving a loader, plant fitting, plant operation, driving a Specialized Mining Vehicle (SMV)) as per NIOSH Method 5040. The copper miners were working 10 h/day and 5 days/week. This study found that the most significant exposures to EC were reported from driving a loader (range $0.02-0.42mg/m^3$). Even though there were control systems (i.e. water tanks and DPM filters) on the diesel vehicles, around 49.5% of the results were over the adjusted recommendable exposure limit ($0.078mg/m^3$). This was probably due to: (1) driver's frequently getting in and out of the diesel vehicles and opening the windows of the diesel vehicles, and (2) inappropriate maintenance of the diesel vehicles and the DPM control systems. The use of the P2 type respirator provided was less than 19.2%. However, there was no significant difference between the day shift results and the night shift results. In order to prevent or minimize exposure to EC in the copper ore mine, it is recommended that the miners are educated in the need to wear the appropriate respirator provided during their work shifts, and to maintain the diesel engine and emission control systems on a regular basis. Consideration should be given to a specific examination of the diesel vehicles' air-conditioning filters and the air ventilation system to control excessive airborne contaminants in the underground copper mine.

• 한국의학물리학회지:의학물리
• /
• 제8권2호
• /
• pp.103-109
• /
• 1997

위암뇨에서 7 ppm과 8 ppm 사이에 네 개의 특성 핵자기공명신호가 나타남을 최근의 핵자기공명분석으로 알게 되었고 , 이 신호들은 정상뇨와 타질병 환자뇨에 비하여 자주 일어남을 발견하였다. 이 네 개의 신호들은 각각 7.25 ppm, 7.38 ppm, 7.63 ppm 그리 고 7.80 ppm이었다. 스핀결합상수의 계산에 의하면, 이 네 개의 공명신호는 종래에 알려졌던 p-hydroxyphenyl이 아니라 m-hydroxyphenyl 임이 밝혀졌다. 본 연구에서는 핵자기공명신호가 자주 일어남을 이용하여 암진단을 가능케 하였고, 이들 네 방향족 핵자기공명신호의 체적자화율을 측정하여 타 목적에 기여할 수 있게 하였다. 체적자화율의 측정 결과는 각각 10.01$\times$$10^{-6}$, 10.07$\times$$10^{-6}$, 10.19$\times$$10^{-6}$ 그리고 10.27$\times$$10^{-6}$이었고, m-hydroxyphenyl의 총체적자화율은 10.27$\times$$10^{-6}$이었다.

• 센서학회지
• /
• 제1권2호
• /
• pp.131-145
• /
• 1992

본 논문은 SOI트랜스듀서 및 회로를 위해, Si 직접접합과 M-C국부연마법에 의한 박막SOI구조의 형성 공정을 기술한다. 또한, 이러한 박막SOI의 전기적 및 압저항효과 특성들을 SOI MOSFET와 cantilever빔으로 각각 조사했으며, bulk Si에 상당한다는 것이 확인되었다. 한편, SOI구조를 이용한 두 종류의 압력트랜스듀서를 제작 및 평가했다. SOI구조의 절연층을 압저항의 유전체분리층으로 이용한 압력트랜스듀서의 경우, $-20^{\circ}C$에서 $350^{\circ}C$의 온도범위에 있어서 감도 및 offset전압의 변화는 자각 -0.2% 및 +0.15%이하였다. 한편, 절연층을 etch-stop막으로 이용한 압력트랜스듀서에 있어서의 감도변화를 ${\pm}2.3%$의 표준편차 이내로 제어할 수 있다. 이러한 결과들로부터 개발된 SDB공정으로 제작된 SOI구조는 집적화마이크로트랜스듀서 및 회로개발에 많은 장점을 제공할 것이다.

• 공업화학
• /
• 제3권2호
• /
• pp.312-317
• /
• 1992

디옥소우라늄(VI) (우라닐) 이온과 질산 이온과의 상호작용을 산소-17 핵자기공명분광법으로 연구하였다. $UO_2NO_3{^+}$의 우라닐 산소 원자(이후 우라닐 산소)의 산소-17 공명신호는 우라닐 이온의 그것보다 낮은 자기장에서 나타났다. $UO_2NO_3{^+}$의 안정도상수를 5, 15, 25, $35^{\circ}C$에서 질산 이온 농도에 따른 산소-17 화학적 이동의 변화로부터 구했으며, 그 값은 이온강도에 따라 달랐다. 안정도상수의 온도 의존성으로부터 계산한 열역학적 파라미터는 다음과 같다: ${\Delta}H=-(27.2{\pm}1.7)kJ\;mol^{-1}$와 ${\Delta}S=-(110{\pm}7)JK^{-1}mol^{-1}$. 우라닐 이온과 여러가지 음이온의 배위자와의 1:1 착물형성 반응에 대한 엔탈퍼와 엔트로피 사이에는 직선관계가 있었다.

• 생약학회지
• /
• 제40권2호
• /
• pp.109-117
• /
• 2009

We examined the purity of six heparin samples by using heparinase, chondroitinase, $^{1}H-NMR$, and polyacrylamide gel electrophoresis. To obtain high molecular weight contaminants from heparin samples, heparinase I - digested samples were subjected to the exhaustive microcon filtration. The filtration process removed heparin-derived di- and oligosaccharides effectively. By combining chondroitinase ABC treatment and strong anion exchange - high performance liquid chromatography, the result showed all six samples contained chondroitin sulfate as a contaminant ranging from 1.3 to 14.9%. Among them, sample S3 showed the highest content of 14.9%, which was further analyzed by chondroitinase AC treatment to confirm chondroitin sulfate B (dermatan sulfate). $^{1}H-NMR$ chemical shifts of N-acetyl groups clearly suggested the existence of chondroitin sulfate B (sample S3) and oversulfated chondroitin sulfate (samples S2 and S4) as contaminants. In addition, polyacrylamide gel electrophoresis was useful for qualitative detection on the sample's purity. These results suggest that the tools of heparinase I and chondroitinase ABC in combination with NMR spectroscopy would give very useful information for investigation of heparin contaminants such as oversulfated chondroitin sulfate and dermatan sulfate in heparin samples.

• 한국자기학회지
• /
• 제16권1호
• /
• pp.92-97
• /
• 2006

C 1s에너지 스캔 방식 광전자회절을 이용하여 Ni(111)$(2\times2)$-O/CO에 공동 흡착된 CO의 흡착구조를 시편의 준비 온도에 따라 연구하였다. 실온근방에서 준비한 시편의 경우 표면진동분광결과와 잘 일치하는 결과인 atop 흡착을 얻었으나, 저온시편의 경우 atop흡착 외에 상당량의 CO가 hollow 흡착으로 해석되었다. 일부분의 hollow 흡착 CO는 미리 흡착된 산소의 precoverage가 적거나 없는 곳에 흡착된 곳으로 해석된다. 유사한 결과가 C 1s와 O 1s를 통행 얻은 고 분해능 XPS에서 얻은 흡착위치에서도 확인되었다.