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Lee, Soon Chang,Jeong, Yesul,Kim, Youn Jung,Kim, Hyeran,Lee, Hyun Uk,Lee, Young-Chul,Lee, Sang Moon,Kim, Hae Jin,An, Ha-Rim,Ha, Myoung Gyu,Lee, Go-Woon,Lee, Young-Seak,Lee, Gaehang Elsevier 2018 Journal of hazardous materials Vol.354 No.-
<P><B>Abstract</B></P> <P>In this study, hierarchically three-dimensional (3D) nanotubular sea urchin-shaped iron oxide nanostructures (3D-Fe<SUB>2</SUB>O<SUB>3</SUB>) were synthesized by a facile and rapid ultrasound irradiation method. Additives, templates, inert gas atmosphere, pH regulation, and other complicated procedures were not required. Dense 3D-Fe<SUB>2</SUB>O<SUB>3</SUB> with a relatively large Brunauer–Emmett–Teller (BET) surface area of 129.4 m<SUP>2</SUP>/g was synthesized within 23 min, and the BET surface area was further improved to 282.7 m<SUP>2</SUP>/g by a post heat-treatment process. In addition, this post processing led to phase changes from maghemite (γ phase) to hematite (α phase) Fe<SUB>2</SUB>O<SUB>3</SUB>. Subsequent characterization suggested that the growth mechanism of the 3D-Fe<SUB>2</SUB>O<SUB>3</SUB> follows self-assembly and oriented attachment. The prepared 3D-Fe<SUB>2</SUB>O<SUB>3</SUB> was applied to wastewater purification. Ultrasound-irradiated 3D-Fe<SUB>2</SUB>O<SUB>3</SUB> can eliminate a As(V) and Cr(VI) from water with 25 times faster removal rate by using a one third smaller amount than commercial α-Fe<SUB>2</SUB>O<SUB>3</SUB>. This was attributed to the inter-particle pores and relatively positively charged surface of the nanostructure. In addition, post heat treatment on ultrasound-irradiated 3D-Fe<SUB>2</SUB>O<SUB>3</SUB> significantly influenced the photocatalytic degradation of methylene blue and phenol, with a 25 times higher removal efficiency than that of commercial α-Fe<SUB>2</SUB>O<SUB>3</SUB>, because of both high BET surface area and good crystallization of the prepared samples.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The 3D- Fe<SUB>2</SUB>O<SUB>3</SUB> can be mass-produced by ultrasound irradiation method. </LI> <LI> The 3D-Fe<SUB>2</SUB>O<SUB>3</SUB> possesses high BET surface area and interconvertible phase. </LI> <LI> The 3D-Fe<SUB>2</SUB>O<SUB>3</SUB> exhibits rapid adsorption rates for heavy metals. </LI> <LI> The 3D-Fe<SUB>2</SUB>O<SUB>3</SUB> exhibits excellent photocatalytic activities toward the dyes. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Preparation and Characterization of Cobalt/Graphene Composites Using Liquid Phase Plasma System.
Kim, Sang-Chai,Kim, Byung Hoon,Kim, Sun-Jae,Lee, Young-Seak,Kim, Hwan-Gi,Lee, Heon,Park, Sung Hoon,Jung, Sang-Chul American Scientific Publishers 2015 Journal of nanoscience and nanotechnology Vol.15 No.1
<P>Liquid phase plasma (LPP) method was applied, for the first time, to the impregnation of cabalt nanoparticles onto graphene. Nanoparticles were dispersed uniformly on the surface of the two-dimensional graphene sheet. The electron miocroscopy observation showed approximately 2-7 nm sized spherical nanoparticles deposited on the surface of graphene sheets. The XPS and EDX analyses revealed that both metal Co and CoO were present in the Co/graphene composites synthesized by the LPP method.</P>
이경민 ( Kyeong Min Lee ),김민지 ( Min-ji Kim ),이상민 ( Sangmin Lee ),여상영 ( Sang Young Yeo ),이영석 ( Young-seak Lee ) 한국화학공학회 2017 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.55 No.2
피치계 흑연섬유의 발열특성을 향상시키기 위하여 흑연섬유에 무전해법을 이용하여 구리 도금하였다. 구리 도금된 흑연섬유는 공기 분위기에서 열중량분석법을 실시하여 도금 시간에 따라 흑연섬유 표면에 구리가 도입된 양을 계산하였다. 또한, 전압에 따른 발열 온도는 섬유 가닥을 이용하여 열화상카메라로 관찰하였다. 무전해 도금의 시간이 증가함에 따라 도입된 구리의 양은 증가하였다. 20분 동안 무전해 도금한 섬유의 전기 전도도는 1594.3 S/cm이며, 발열 온도는 최대 57.2 ℃로 가장 크게 나타났다. 이러한 결과는 도금시간이 증가함에 따라 전기 전도성이 우수한 구리가 흑연섬유 표면에 성장하고, 이에 따라 발열특성이 향상된 것으로 판단된다. To improve heating characteristics of graphite fibers, graphite fibers were copper-plated by electroless plating. The Cu-plated graphite fibers were investigated by thermos-gravimetric analysis in air to calculate quantities of copper on surface of graphite fiber according to plating time. Also, the surface temperature with applied voltage was observed by thermos-graphic camera using a strand of graphite fiber. According to the increment of plating time, the higher quantities of plated copper on graphite fiber were obtained. The electric conductivity of plated graphite fiber for 20 minutes was resulted in 1594.3 S/cm, and surface temperature of this sample showed the maximum temperature 57.2 ℃. These result could be attributed that copper having great electric conductivity are growing on graphite fiber and followed improving heating characteristics.
Micropore‑structured activated carbon prepared by waste PET/ petroleum‑based pitch
Sang Wan Seo,Yun Jeong Choi,Ji Hong Kim,Jong Hoon Cho,Young‑Seak Lee,Ji Sun Im 한국탄소학회 2019 Carbon Letters Vol.29 No.4
In this study, pitch crosslinked by oxygen function groups was made into activated carbon (AC) and pore structure was observed. The oxygen functional groups were introduced by the addition of waste PET for pitch synthesis. Activation agent ratios used to obtain the AC during the activation process were 1:1, 1:2 and 1:4 (pitch:KOH, w/w). The oxygen content in the prepared pitch was characterized by elemental analysis. Also, the molecular weight of pitch was investigated by MALDITOF. Specific surface area and micropore volume of the prepared AC were determined by the argon adsorption–desorption analysis and calculated using the Brunauer–Emmett–Teller and Horvath–Kawazoe equations, respectively. Micropore fraction of PET-free AC was smaller than that of PET-added AC. At high activation agent ratio, mesopores were created when the micropore structure collapsed. However, in the PET-added AC, due to the oxygen crosslinking effect, the micropore structure and micropore size were maintained even at a high activation agent ratio. Therefore, PET AC was found to have a higher micropore fraction than that of PET-free AC.
이상주,박경일,김원술,정갑열,김준연,김양석,홍영습 동아대학교 부설 산업의학연구소 1995 산업의학연구소 논총 Vol.- No.2
For the purpose of presenting the basic data for the establishment of control measures on the long-term noise exposed workers, this study was carried out on the relationship between personal noise exposed dose and hearing loss on the 67 male workers whose hearing threshold had exceeded 40 dB in 4,000Hz, from 1990 to 1992. Conclusively, the level of hearing loss was significantly related to personal noise exposed dose in follow-up period. We considered that personal noise exposed dose which was measured by the personal noise dosemeter was more efficient rather than the noise level of workplace for the evaluating the long-term change of hearing acuity. And although in the case of not-diagnosed as noise induced hearing loss, it was suspected that the active control programs such as improvement of noisy environment or early transfer to proper workplace were needed on the workers who exposed with over 90dB in personal noise exposed dose.
Anion co-doped Titania for Solar Photocatalytic Degradation of Dyes
Lee, Young-Seak,Kim, Sang-Jin,Venkateswaran, P.,Jang, Jeen-Seok,Kim, Hyuk,Kim, Jong-Gyu Korean Carbon Society 2008 Carbon Letters Vol.9 No.2
In order to investigate the effect of doping C, N, B and F elements on $TiO_2$ for reducing the band gap, the heat treatment of $TiO_2$ was carried out with tetraethylammonium tetrafluoroborate. Through XRD and XPS analysis, the C, N, B and F doped anatase $TiO_2$ was confirmed. According to the increase of temperature during treatment, the particle size was increased due to aggregation of $TiO_2$ with elements (B, C, N and F). To investigate the capacity of photocatalyst for degradation of dye under solar light, the degradation of acridine orange and methylene blue was conducted. The degradation of dyes was carried out successfully under solar light indicating the effect of doping elements (B, C, N and F) on $TiO_2$ for reducing the band gap effectively.