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Czochralski법을 이용한 금속 단결정의 성장과 구조적, 전기적 성질에 관한 연구
박정훈,차수영,박상언,김성규,조채룡,박혁규,김형찬,정명화,정세영,Park, Jeung-Hun,Cha, Su-Young,Park, Sang-Eon,Kim, Sung-Kyu,Cho, Chae-Ryong,Park, Hyuk-K.,Kim, Hyung-Chan,Jeong, Myung-Hwa,Jeong, Se-Young 한국결정학회 2005 韓國結晶學會誌 Vol.16 No.2
It is well known that the general metals have a lot of grain boundaries. The grain boundaries play a negative role to increase the resistivity and to decrease the conductivity. The small resistivity and the large conductivity have been a goal of the material scientists, and no signal noise, perfect signal transfer, and the realization of the real sound are the dream of electronic engineers and audio manias. Generally, oxygen free copper (OFC) and Ohno continuous casting (OCC) copper cables have been used for the purpose of the precise signal transfer and low noise. However they still include a lot of grain boundaries. In our study, we have grown the single crystal by the Czochralski method and succeeded to produce single crystal wires from the crystal in the dimension of $0.5{\times}0.5{\times}2500mm$. The produced wire still possesses very good single crystal properties. We observed the structure of the wire, and measured the resistance and impedance. Glow Discharge Spectrometer (GDS) was used for analyzing the compositions of copper single crystals and commercial copper. Current-Voltage curve, resistance, total harmonic distortion and speaker frequency response were measured for comparing electrical and acoustic properties of two samples.
Sulfur removal from coal with supercritical fluid treatment
박정훈,Yong Ou Joung,Sang Do Park 한국화학공학회 2007 Korean Journal of Chemical Engineering Vol.24 No.2
Conversion and sulfur removal of coal in sub- and supercritical water was studied in a micro reactor in the temperature range of 340-400°C and water density 0-0.27 g/cm3 for 0-90 min under N2 atmosphere. The experiments were conducted to investigate the effect of reaction temperature, pressure, time and density of water on the sulfur removal in gaseous and liquid effluents, respectively. The results show that supercritical condition is more effective than sub-critical condition to remove the sulfur from coal. It is possible to reduce 57.42% of the original sulfur in coal for the reaction time of 90 min at 400°C and 30 MPa. The main gas containing sulfur in the gaseous effluent is not SO2 but H2S, irrespective of operating condition. The sulfur removal in liquid effluents is much greater than that in gas effluents. Compared with temperature, the influence of water density and pressure is less significant.
Mouse cell에서 형개연교탕(荊芥連翹湯)의 iNOS 생성 억제 효과
박정훈,김종채,홍승욱,Park, Jung-Hoon,Kim, Jong-Che,Hong, Seung-Ug 대한한방안이비인후피부과학회 2011 한방안이비인후피부과학회지 Vol.24 No.1
Background and Objectives : The aim of this study was to investigate anti-inflammatory and anti-oxidant effects of Hyunggaeyungyo-tang(HYT) on RAW 264.7 cells. Material and Methods : Two types of experiments were implemented for this study: first, the experiment to study the anti-oxidant effect of HYT using riboflavin; second, in vitro experiment to investigate the suppression of NF-${\kappa}$B activation using RAW 264.7 cells (I${\kappa}$B kinase and induce nitric oxide synthase mRNA expression) Results : 1. The anti-oxidant effects of HYT was dose-dependantly increased. 2. The RAW 264.7cells were treated with LPS for 1 hours prior to the addition of indicated concentrations(0.4,-1.0mg/$m\ell$) of HYT, and the cells were further incubated for 24 hours. The LPS-induced IKK & iNOS mRNA expression were dose-dependantly decreased in HYT treated RAW 264.7cells. Conclusion : The results suggest that HYT is significantly effective in the treatment of inflammation through the suppression of NF-${\kappa}$B activation and iNOS production.
박정훈,이옥민,Park, Jung-Hoon,Lee, Ok-Min 한국조류학회(藻類) 2004 ALGAE Vol.19 No.2
Six taxa of unrecorded Korean species of genus Cosmarium were collected from several freshwater sites of South Korea in 2003. They were 3 species and 3 varieties of Genus Cosmarium. Genus Cosmarium of Korea was reported to totally 273 taxa 125 species, 113 varieties and 35 forms including this study.
La<sub>0.07</sub>Sr<sub>0.3</sub>Co<sub>0.2</sub>Fe<sub>0.8</sub>O<sub>3-δ</sub> 분리막의 제조 및 산소투과 특성
박정훈,김종표,백일현,Park, Jung Hoon,Kim, Jong Pyo,Baek, Il Hyun 한국공업화학회 2008 공업화학 Vol.19 No.5
$La_{0.7}Sr_{0.3}Co_{0.2}Fe_{0.8}O_{3-{\delta}$ oxide was synthesized by a citrate method and a typical dense membrane of perovskite oxide has been prepared using as-prepared powder by pressing and sintering at $1300^{\circ}C$. Precursor of $La_{0.7}Sr_{0.3}Co_{0.2}Fe_{0.8}O_{3-{\delta}$ prepared by citrate method was investigated by TGA and XRD. Metal-citrate complex in precursor was decomposed into perovskite oxide in the temperature range of $260{\sim}410^{\circ}C$ but XRD results showed $SrCO_3$ existed as impurity at less than $900^{\circ}C$. Electrical conductivity of membrane increased with increasing temperature but then decreased over $700^{\circ}C$ in air atmosphere ($Po_2=0.2atm$) and $600^{\circ}C$ in He atmosphere ($Po_2=0.01atm$) respectively due to oxygen loss from the crystal lattice. The oxygen permeation flux increased with increasing temperature and maximum oxygen permeation flux of $La_{0.7}Sr_{0.3}Co_{0.2}Fe_{0.8}O_{3-{\delta}$ membrane with 1.6 mm thickness was about $0.31cm^3/cm^2{\cdot}min$ at $950^{\circ}C$. The activation energy for oxygen permeation was 88.4 kJ/mol in the temperature range of $750{\sim}950^{\circ}C$. Perovskite structure of membrane was not changed after permeation test of 40 h and the membrane was stable without secondary phase change with 0.3 mol Sr addition. 구연산법을 이용하여 $La_{0.7}Sr_{0.3}Co_{0.2}Fe_{0.8}O_{3-{\delta}$ 산화물을 합성하였으며, 합성된 분말은 압축 성형 후 $1300^{\circ}C$에서 소결하여 치밀한 페롭스카이트 분리막을 제조하였다. 구연산법으로 제조한 $La_{0.7}Sr_{0.3}Co_{0.2}Fe_{0.8}O_{3-{\delta}$의 전구물질은 TGA와 XRD로 분석하였다. $260{\sim}410^{\circ}C$ 온도 영역에서 전구물질의 금속-구연산 복합체가 분해되며 페롭스카이트 산화물이 얻어지나 XRD 분석결과 $900^{\circ}C$ 이하에서는 $SrCO_3$가 불순물로 존재하였다. 분리막의 전기전도도는 온도가 증가함에 따라 증가하다. 결정격자의 산소 손실로 인해 공기분위기에서는 $700^{\circ}C$ ($Po_2=0.2atm$)부터, 헬륨분위기에서는 $600^{\circ}C$ ($Po_2=0.01atm$) 부터 각각 감소하였다. 산소투과량은 온도가 증가할수록 증가하였고, 두께 1.6 mm의 $La_{0.7}Sr_{0.3}Co_{0.2}Fe_{0.8}O_{3-{\delta}$ 분리막은 $950^{\circ}C$에서 $0.31cm^3/cm^2{\cdot}min$의 최대 투과도를 보였다. 산소투과에 대한 활성화 에너지는 $750{\sim}950^{\circ}C$ 온도 영역에서 88.4 kJ/mol이었다. 40 h의 투과실험 후에 분리막의 페롭스카이트 결정 구조는 변하지 않았으며 0.3 mol Sr doping 시 2차상이 생성되지 않고 안정하였다.
C<sub>12</sub>A<sub>7</sub>계 알루미나시멘트 및 아질산염을 사용한 저온환경 보수시공용 시멘트 모르타르의 특성
박정훈,Park, Jung-Hoon 한국구조물진단유지관리공학회 2017 한국구조물진단유지관리공학회 논문집 Vol.21 No.4
본 연구는 저온환경에서 경화가 가능한 알루미나시멘트 및 아질산염을 사용한 보수용 시멘트 모르타르의 기초성능을 평가하고자 하였다. 이를 위해 국내 건설현장에서 사용되고 있는 보수용 모르타르를 조사 및 선정하였으며, 이를 대상으로 알루미나시멘트, 아질산염을 치환하여 혼입량 조절에 따른 실험평가를 실시하였다. 그 결과, 알루미나시멘트, 아질산염을 보수용 모르타르에 치환하여 사용할 경우 초기 강도발현이 증진되었다. 또한 내화학성이 개선되었고 수축거동이 감소하였으며 동결융해에 대한 저항성이 증대되었다. 알루미나시멘트와 아질산염을 2:1의 비율로 7.5% 치환하여 외부구조물에 시공한 결과 표면상태가 5개월 이상 양호하게 유지되었으며, 실제 외부구조물에 사용성이 우수한 것으로 판단된다. The purpose of this study is to evaluate the basic performance of cement mortar for repair using alumina cement and nitrite can be cured in low temperature environment. For this purpose, the repair mortar used in the domestic construction site was selected and the experimental evaluation was carried out by adjusting the mixing amount by substituting alumina cement and nitrite for the blending ratio. The experimental test results confirmed that alumina cement and nitrite were replaced with the repair mortar, the initial strength was improved. Also, the chemical resistance was improved, the shrinkage behavior was decreased, and the resistance to freezing and thawing was increased. As a result, applying alumina cement and nitrite at a ratio of 2:1 at 7.5%, the surface condition was maintained for 5 months or longer and it was judged to be excellent in practical use for external structures.