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용융염법을 이용한 저차원 구조의 금속 칼코겐 화합물의 합성 및 구조 특성연구
최덕수,윤혜식,오화숙,김돈,윤호섭,박윤봉,Choi, Duc-Su,Yun, Hye-Sik,Oh, Hwa-Suk,Kim, Don,Yun, Ho-Seop,Park, Youn-Bong 대한화학회 2004 대한화학회지 Vol.48 No.5
구리 금속 분말과 혼합 알칼리금속 다셀레늄화물 용융염 ($KNaSe_x$) 과의 반응을 통하여 판상형태의 결정을 갖는 $KCu_4Se_3$ 화합물을 얻었다. $KCu_4Se_3$화합물의 구조는 X-선 단결정 회절법에의해 결정되었으며 사반면상을 갖는다. (P4/mmm, a=4.013(1)${\AA}$, c=9.712(1)${\AA}$, z=1, R=6.7%). 그 구조는 안티 PbO 구조를 갖는 $Cu_2Se_2$ 층이 겹쳐짐으로서 만들어지는 $[Cu_4Se_3]_n^{n-}$의 이중층으로 구성되어있다. $KCu_4Se_3$의 단결정에 대한 온도 변화에 따른 저항 측정을 통하여 전도체의 특성을 확인하였으며 300 K에서 $1.8{\times}10^{-4}{\Omega}{\cdot}cm$과 20 K에서 $1.0{\times}10^{-6}{\Omega}{\cdot}cm$의 저항 값을 갖는다. The reaction of Cu metal with mixed alkali metal polyselenide flux ($KNaSe_x$) produced large plate-like crystals of $KCu_4Se_3$. The structure of $KCu_4Se_3$, determined with X-ray single crystal diffraction techniques, is tetragonal (P4/mmm, a=4.013(1))${\AA}$, c=9.712(1))${\AA}$, z=1, R=6.7%). The structure is composed $[Cu_4Se_3]_n^{n-}$double layers which are made of fused anti PbO-type Cu2Se2 layers. Temperature variable resistivity measurement on single crystal of $KCu_4Se_3$ shows metallic behavior ranging from $1.8{\times}10^{-4}{\Omega}{\cdot}cm$ (at 300 K) to $1.0{\times}10^{-6}{\Omega}{\cdot}cm$ (at 20 K).
Mg(OH)2 를 이용한 습식배연탈황공정에서 흡수탑의 특성
박영수,이형근,조항대,최병문,윤혜식 한국화학공학회 2000 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.38 No.5
수산화마그네슘을 이용하여 산업체의 보일러에서 발생하는 연소가스를 처리하는 배연탈황공정을 개발하기 위하여 bench 규모의 실험장치를 이용하여 여러 형태의 흡수탑의 특성과 성능에 관한 실험을 수행하였다. 흡수탑의 종류에 따라 기상물 질전달계수(k_Ga) 값을 기상 Reynolds number 21,000-33,000과 액상 Reynolds number 950-2,400 범위에서 경험적 상관관계식을 얻었다. Dual Flow Tray(DFT)를 설치한 흡수탑에서 SO₃ 농도가 0.2-0.3wt% 정도로 낮은 경우에는 L/G ratio의 변화에 따라 SO₂제거효율이 크게 변화함을 보여 주지만, SO₃ 농도가 0.7wt% 이상인 조건에서는 L/G ratio나 SO₃ 농도가 증가하여도 별 영향을 받지 않았다. DFT의 hole 상부에 일정한 각도의 plate가 붙어 있는 Cycloid Dual Flow Tray (CDFT)는 DFT에 비해 성능이 다소 높지만 각도에 따라 흡수탑내의 압력차의 변화가 컸다. CDFT#3, CDFT#4를 이용한 경우에 비교적 낮은 압력을 유지하면서도 SO₂ 제거효율이 95% 정도를 유지할 수 있었다. To develope the flue gas desulfurization process using magnesium hydroxide, which is used in industries to treat the flue gas from boilers, the performance of different types of gas-liquid contactors was experimentally investigated using a bench scale system. Emperical correlations for the gas phase mass transfer coefficient(k_Ga) was determined at gas-phase Reynolds numbers from 21,000 to 33,000 and liquid-phase Reynolds numbers from 950 to 2,400. SO₂removal efficiency obtained at the Dual Flow Tray(DPT) was varied by L/G ratio when S03 concentration was 0.2-0.3 wt%, but was not affected by L/G ratio and SO₃ concentration when SO₃ concentration was more than 0.7 wt%. Not only was the performance of Cycloid Dual Flow Tray(CDFT) which has an inclined plate above each plate hole higher than DPT but the pressure drop was larger. 95% SO₂ removal efficiency was obtained using CDFT#3, CDFT#4 with a mild pressure drop.
Occupational Lead Exposure from Indoor Firing Ranges in Korea
박원주,이석호,이세호,윤혜식,문재동 대한의학회 2016 Journal of Korean medical science Vol.31 No.4
Military personnel often use ammunitions that contain lead. The present study aimed to identify the risks for lead exposure and lead poisoning among workers at indoor firing ranges. A special health examination, including blood lead level (BLL) testing, was performed for all 120 workers at the indoor firing ranges of the Republic of Korea’s Air Force, Navy, and Armed Forces Athletic Corps. The overall mean BLL was 11.3 ± 9.4 μg/dL (range: 2.0-64.0 μg/dL). The arithmetic mean of the BLL for professional shooters belong to Armed Forces Athletic Corps was 14.0 ± 8.3 μg/dL, while those of shooting range managers and shooting range supervisors were 13.8 ± 11.1 μg/dL and 6.4 ± 3.1 μg/dL, respectively. One individual had a BLL of 64 μg/dL, and ultimately completed chelation treatment (with CaNa2-ethylenediaminetetraacetic acid) without any adverse effects. These findings indicate that indoor firing range workers are exposed to elevated levels of lead. Therefore, when constructing an indoor firing range, a specialist should be engaged to design and assess the ventilation system; and safety guidelines regarding ammunition and waste handling must be mandatory. Moreover, workplace environmental monitoring should be implemented for indoor firing ranges, and the workers should undergo regularly scheduled special health examinations.