해양미세조류의 라디칼소거활성 검색

최진석,이원갑,김동수,최홍대,최재수,정지형,임광식,최원철,손병화,Choi, Jin-Seok,Lee, Won-Kap,Kim, Dong-Soo,Choi, Hong-Dae,Choi, Jae-Sue,Jung, Jee H.,Im, Kwang-Sik,Choi, Won-Chul,Son, Byeng-Wha 한국생약학회 2000 생약학회지 Vol.31 No.2

In order to screen new radical scavenging principle which is expected to be antiaging drug lead, we have investigated 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity of the marine microalgae, greenalgae(10 speices), diatom (10 speices) and blue-green algae (10 speices). The significant activities$(IC_{50}:\;<100\;{mu}g/ml)$ were observed in 4 species of green algae (MA002, 006, 009, 010), 1 species of diatom (MA015) and 5 species of blue-green algae (MA017, 018, 019, 024, 025). Within the scope of family tested, MA009 $(IC_{50}:\;=78\;{mu}g/ml)$, MA015 $(IC_{50}:\;=38\;{mu}g/ml)$ and MA019 $(IC_{50}:\;=41\;{mu}g/ml)$ displayed the most significant activity. Among the marine microalgae tested at family level, cyanophycean blue-green algae was shown to be the most active family on screening of new bioactive compounds.

국내에서 개발된 3차원 임플란트 가상시술 시스템에 의한 영상재구성상의 정확도

최진석,김은경,한원정,Choi Jin-Seok,Kim Eun-Kyung,Han Won-Jeong 대한영상치의학회 2003 Imaging Science in Dentistry Vol.33 No.3

Purpose: To compare the measurements of the mandible and the detectability of the mandibular canal on reformatted images using a newly developed 3-dimensional implant simulation program with traditionally used CT multiplanar reconstruction program and true measurements. Materials and Methods: Ten dry dog mandibles were used in this study. Occlusal templates for CT examination were fabricated and marked with gutta perch a at ten sites. Axial CT scans were taken and reconstructed using DentaScan (D group) and Vimplant program (V group), and each mandible was sectioned at the previously marked sites (R group). Maximum vertical height (H) and maximum width (W) of the mandible, the distances from buccal border of the mandibular canal to the most buccal aspect of the mandible (X), and the distance from the superior border of the mandibular canal to the alveolar crest (Y) were measured, and the mandibular measurements in each group were compared. Detectability of mandibular canal was evaluated using a 3-point scale in both V and D groups by three oral radiologists and compared. Results: H in the V group was slightly greater than that in the D group, and Wand X in the V group was slightly less than those in the D group. H in the V group was less than that in the R group, and Wand X in the V group was larger than those in the R group. The detectability of the mandibular canal did not show statistically significant differences between V and D groups. Conclusion: The results of the experiment show that the newly developed, inexpensive Vimplant/TM/ simulation program can be used as an alternative to the traditionally used, and more expensive CT multiplanar reconstruction program.

레저스포츠로 인한 안외상의 역학적 고찰

최진석,신경환,Jin Seok Choi,Kyung Hwan Shin,Ph,D 대한안과학회 2008 대한안과학회지 Vol.49 No.10

Purpose: We investigated the epidemiological and clinical characteristics of leisure activity- and sports-related ocular trauma for application to its treatment and prevention. Methods: A retrospective chart review was conducted on 121 patients who visited Gachon University Gil Medical Center from January 2006 to December 2007 because of leasure activity- and sports-related ocular trauma. The incidence of ocular injuries, sex and age, monthly and seasonal distribution, causes, diagnosis, and visual acuity were reviewed. Results: Among the 1592 patients of ocular trauma, 121 patients (7.6%) were related to leasure activity- and sports. The incidence was higher in males (81.8%; 4.5-fold) than in females. The mean age of patients was 23.7±7.1 years. Ocular injuries occurred least in winter (19.8%) and occurred more during the week than on weekends (1.6-fold). The most common cause was soccer (39.7%), more specifically being hit with the soccer ball (47.1%). The initial LogMAR visual acuity was worse in the females and in the patients older than 30 years. Traumatic hyphema (19.7%) was the most common cause of visual disturbance, and corneal erosion (11.3%) occurred frequently. Conclusions: Leasure activity- and sports-related ocular trauma is becoming an increasingly significant cause of ocular morbidity, and trends relating to characteristics such as sex and age were found. These outcomes can be put to practical use in the prevention and treatment of sports-relatedocular injuries. J Korean Ophthalmol Soc 2008;49(10):1658-1664

실시간 XRD와 TEM을 이용한 MAPbI₃의 온도 변화에 따른 구조 분석

최진석,엄지호,윤순길,Choi, Jin-Seok,Eom, Ji-Ho,Yoon, Soon-Gil 한국전기전자재료학회 2019 전기전자재료학회논문지 Vol.32 No.1

Methylammonium lead triiodide ($MAPbI_3$)-based perovskite solar cells potentially have potential advantages such as high efficiency and low-cost manufacturing procedures. However, $MAPbI_3$ is structurally unstable and has low phase-change temperatures ($30^{\circ}C$ and $130^{\circ}C$); it is necessary to solve these problems. We investigated the crystal structure and phase separation using real-time temperature-change X-ray diffraction, transmission electron microscopy, and electron energy loss spectroscopy. $MAPbI_3$ has a tetragonal structure, and at about $35^{\circ}C$ the c-axis contracts, transforming $MAPbI_3$ into the related cubic crystal structure. In addition, at $130^{\circ}C$, phase separation occurs in which $CH_3NH_2$ and HI at the center of the unit cell of the perovskite structure are extracted by gas, leavingand only $PbI_2$ of the three-component structure, is produced as the final solid product.

물유리를 이용한 나노실리카 제조 시 pH가 미치는 영향

최진석,안성진,Choi, Jin Seok,An, Sung Jin 한국재료학회 2015 한국재료학회지 Vol.25 No.4

Synthesis of nano-silica using water glass in a Sol-Gel process is one of several methods to manufacture nano-silica. In nano-silica synthesized from water glass, there are various metal impurities. However, synthesis of nano-silica using water glass in a Sol-Gel process is an interesting method because it is relatively simple and cheap. In this study, nano-silica was synthesized from water glass; we investigated the effect of pH on the synthesis of nano-silica. The morphology of the nanosilica with pH 2 was flat, but the surface of the nano-silica with pH 10 had holes similar to small craters. As a result of ICP-OES analysis, the amount of Na in the nano-silica with pH 2 was found to be 170 mg/kg. On the other hand, the amount of Na in the nano-silica with pH 10 was found to be 56,930 mg/kg. After calcination, the crystal structure of the nano-silica with pH 2 was amorphous. The crystal structure of the nano-silica with pH 10 transformed from amorphous to tridymite. This is because elemental Na in the nano-silica had the effect of decreasing the phase transformation temperature.

폴리스타이렌을 이용한 그래핀 합성 및 산화 붕소가 그래핀 합성에 미치는 영향

최진석,안성진,Choi, Jinseok,An, Sung Jin 한국재료학회 2018 한국재료학회지 Vol.28 No.5

Graphene is an interesting material because it has remarkable properties, such as high intrinsic carrier mobility, good thermal conductivity, large specific surface area, high transparency, and high Young's modulus values. It is produced by mechanical and chemical exfoliation, chemical vapor deposition (CVD), and epitaxial growth. In particular, large-area and uniform single- and few-layer growth of graphene is possible using transition metals via a thermal CVD process. In this study, we utilize polystyrene and boron oxide, which are a carbon precursor and a doping source, respectively, for synthesis of pristine graphene and boron doped graphene. We confirm the graphene grown by the polystyrene and the boron oxide by the optical microscope and the Raman spectra. Raman spectra of boron doped graphene is shifted to the right compared with pristine graphene and the crystal quality of boron doped graphene is recovered when the synthesis time is 15 min. Sheet resistance decreases from approximately $2000{\Omega}/sq$ to $300{\Omega}/sq$ with an increasing synthesis time for the boron doped graphene.

Octamethylcyclotetrasiloxane를 이용한 광섬유 클래드 프리폼 형성

최진석,이태균,박성규,이가형,전구식,안성진,Choi, Jinseok,Lee, Tae Kyun,Park, Seong Gyu,Lee, Ga Hyoung,Jun, Gu Sik,An, Sung Jin 한국재료학회 2018 한국재료학회지 Vol.28 No.1

There are various manufacturing processes for pure $SiO_2$ that is used as abrasives, chemicals, filters, and glasses, and in metallurgy and optical industries. In the optical fiber industry, to produce $SiO_2$ preform, $SiCl_4$ is utilized as a raw material. However, the combustion reaction of $SiCl_4$ has caused critical environmental issues, such as ozone deficiency by chlorine compounds, the greenhouse effect by carbon dioxide and corrosive gas such as hydrochloric acid. Thus, finding an alternative source that does not have those environmental issues is important for the future. Octamethylcyclotetrasiloxane (OMCTS or D4) as a chlorine free source is recently promising candidate for the $SiO_2$ preform formation. In this study, we first conducted a vaporizer design to vaporize the OMCTS. The vaporizer for the OMCTS vaporization was produced on the basis of the results of the vaporizer design. The size of the primary particle of the $SiO_2$ formed by OMCTS was less than 100 nm. X-ray diffraction patterns of the $SiO_2$ indicated an amorphous phase. Fourier-transform infrared spectroscopy analysis revealed the Si-O-Si bond without the -OH group.

이온 주입법을 이용한 ZnO 박막의 As 도핑

최진석,안성진,Choi, Jin Seok,An, Sung Jin 한국재료학회 2016 한국재료학회지 Vol.26 No.6

ZnO with wurtzite structure has a wide band gap of 3.37 eV. Because ZnO has a direct band gap and a large exciton binding energy, it has higher optical efficiency and thermal stability than the GaN material of blue light emitting devices. To fabricate ZnO devices with optical and thermal advantages, n-type and p-type doping are needed. Many research groups have devoted themselves to fabricating stable p-type ZnO. In this study, $As^+$ ion was implanted using an ion implanter to fabricate p-type ZnO. After the ion implant, rapid thermal annealing (RTA) was conducted to activate the arsenic dopants. First, the structural and optical properties of the ZnO thin films were investigated for as-grown, as-implanted, and annealed ZnO using FE-SEM, XRD, and PL, respectively. Then, the structural, optical, and electrical properties of the ZnO thin films, depending on the As ion dose variation and the RTA temperatures, were analyzed using the same methods. In our experiment, p-type ZnO thin films with a hole concentration of $1.263{\times}10^{18}cm^{-3}$ were obtained when the dose of $5{\times}10^{14}$ As $ions/cm^2$ was implanted and the RTA was conducted at $850^{\circ}C$ for 1 min.

물유리를 이용한 고순도 나노실리카 제조

최진석,이현권,안성진,Choi, Jin Seok,Lee, Hyun-Kwuon,An, Sung Jin 한국재료학회 2014 한국재료학회지 Vol.24 No.5

Silica nano-powder (SNP) is an inorganic material able to provide high-performance in various fields because of its multiple functions. Methods used to synthesize high purity SNP, include crushing silica minerals, vapor reaction of silica chloride, and a sol-gel process using TEOS and sodium silicate solution. The sol-gel process is the cheapest method for synthesis of SNP, and was used in this study. First, we investigated the shape and the size of the silica-powder particles in relation to the variation of HCl and sodium silicate concentrations. After drying, the shape of nano-silica powder differed in relation to variations in the HCl concentration. As the pH of the solution increased, so did the density of crosslinking. Initially, there was NaCl in the SNP. To increase its purity, we adopted a washing process that included centrifugation and filtration. After washing, the last of the NaCl was removed using DI water, leaving only amorphous silica powder. The purity of nano-silica powder synthesized using sodium silicate was over 99.6%.

한국실명예방재단의 2003년도 노인 안 검진과 개안수술사업 결과

최진석,김신자,장병원,신경환,Jin Seok Choi,Sin Ja Kim,Byung Won Jang,Kyung Hwan Shyn 대한안과학회 2005 대한안과학회지 Vol.46 No.1