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고상법을 이용한 Y<sub>3</sub>Al<sub>5</sub>O<sub>12</sub>:Ce<sup>3+</sup>의 제조에서 BaF<sub>2</sub>가 미치는 영향
원형석,원창환,원형일,Won, Hyung-Seok,Hayk, Nersisyan,Won, Chang-Whan,Won, Hyung-Il 한국재료학회 2011 한국재료학회지 Vol.21 No.11
The effect of $BaF_2$ flux in $Y_3Al_5O_{12}:Ce^{3+}$(YAG:Ce) formation was investigated. Phase transformation of $Y_3Al_5O_{12}$(YAG) was characterized by using XRD, SEM, and TEM-EDS, and it was revealed that the sequential formation of the $Y_4Al_2O_9$(YAM), $YAlO_3$(YAP) and $Y_3Al_5O_{12}$(YAG) in the temperature range of 1000-1500$^{\circ}C$. Single phase of YAG was revealed from 1300$^{\circ}C$. In order to find out the effect of $BaF_2$ flux, three modeling experiments between starting materials (1.5$Al_2O_3$-2.5$Y_2O_3$, $Y_2O_3$-$BaF_2$, and $Al_2O_3$-$BaF_2$) were done. These modeling experiments showed that the nucleation process occurs via the dissolution-precipitation mechanism, whereas the grain growth process is controlled via the liquid-phase diffusion route. YAG:Ce phosphor particles prepared using a proposed technique exhibit a spherical shape, high crystallinity, and an emission intensity. According to the experimental results conducted in this investigation, 5% of $BaF_2$ was the best concentration for physical, chemical and optical properties of $Y_3Al_5O_{12}:Ce^{3+}$(YAG:Ce) that is approximately 10-15% greater than that of commercial phosphor powder.
고상법에 의한 Sr<sub>3</sub>Al<sub>2</sub>O<sub>6</sub> 형광체의 분말합성 및 발광특성
김수진,원형일,원창환,Kim, Sue-Jin,Won, Hyung-Il,Won, Chang-Whan,Nersisyan, Hayk 한국세라믹학회 2011 한국세라믹학회지 Vol.48 No.3
A red strontium aluminate phosphor ($Sr_3Al_2O_6:Eu^{3+},Eu^{2+}$) is synthesized using a solid state reaction method in air and reducing atmosphere. The investigation of firing temperature indicates that a single phase of $Sr_3Al_2O_6$ is formed when the firing temperature is higher than $1300^{\circ}C$. The effect of firing temperature and doping concentration on luminescent properties are investigated. $Sr_3Al_2O_6$ phosphor exhibits the typical red luminescent properties of $Eu^{3+}$ and $Eu^{2+}$.
자전연소합성법에 의한 SiC 분말 제조시 반응변수의 영향
신창윤,원형일,원창환,Shin, Chang-Yun,Won, Hyung-Il,Nersisyan, Hayk,Won, Chang-Whan 한국세라믹학회 2006 한국세라믹학회지 Vol.43 No.7
The preparation of SiC powder by SHS in the system of $SiO_2-Mg-C$ was investigated in this study. The effects of various processing parameters such as the initial pressure of inert gas in reactor, the content of Mg and C in mixture and the size of $SiO_2$ particles on the synthesis of SiC by SHS methode were investigated. The minimum initial pressure of inert gas in reactor for SHS reaction in this system was 5 atm, and as the pressure increased, and the concentration of unreacted Mg decreased. At 50 atm of the initial inert gas pressure in reactor, the optimum composition for the preparation of pure SiC was $SiO_2+2.5Mg+1.2C$. SiC powder synthesized in this condition had a mixture of ${\alpha}-SiC\;and\;{\beta}-SiC$ with an irregular shape and the particle size of $0.5{\sim}0.8{\mu}m$.
고상법에 의한 Zn<sub>2</sub>SiO<sub>4</sub>:Mn<sup>2+</sup>녹색 형광체의 제조와 특성에 관한 연구
유현희,원형일,원창환,Yoo, Hyeon-Hee,Nersisyan, Hayk,Won, Hyung-Il,Won, Chang-Whan 한국재료학회 2011 한국재료학회지 Vol.21 No.6
[ $Zn_{2(1-x)}Mn_xSiO_4$ ]$0.07{\leq}x{\leq}0.15$) green phosphor was prepared by solid state reaction. The first heating was at $900^{\circ}C-1250^{\circ}C$ in air for 3 hours and the second heating was at $900^{\circ}C$ in $N_2/H_2$(95%/5%) for 2 hours. The size effect of $SiO_2$ in forming $Zn_2SiO_4$ was investigated. The temperature for obtaining single phase $Zn_2SiO_4$ was lowered from $1100^{\circ}C$ to $1000^{\circ}C$ by decreasing the $SiO_2$ particle size from micro size to submicro size. The effect of the activators for the Photoluminescence (PL) intensity of $Zn_2SiO_4:Mn^{2+}$ was also investigated. The PL intensity properties of the phosphors were investigated under vacuum ultraviolet excitation (147 nm). The emission spectrum peak was between 520 nm and 530 nm, which was involved in green emission area. $MnCl_2{\cdot}4H_2O$, the activator source, was more effective in providing high emission intensity than $MnCO_3$. The optimum conditions for the best optical properties of $Zn_2SiO_4:Mn^{2+}$ were at x = 0.11 and $1100^{\circ}C$. In these conditions, the phosphor particle shape was well dispersed spherical and its size was 200 nm.
자전연소합성법에 의해 제조된 BaTiO<sub>3</sub> 분말의 소결특성에 미치는 첨가제의 영향
임성재,신창윤,원형일,원창환,Lim Sung-Jae,Shin Chang-Yun,Won Hyung-Il,Won Chang-Whan 한국분말야금학회 2006 한국분말재료학회지 (KPMI) Vol.13 No.2
In this study, high purity fine $BaTiO_3$ powders were prepared by SHS (Self-propagating High-temperature Synthesis). We would examinate the study of sintering properties and characteristics as a function of temperature with various additives (binder, sintering agent). In separately binder addition, the green and sintered density of specimen were increased as binder content increases. The increased porosity resulted in fine grain size due to the inhibition of grain boundary moving. The $Al_{2}O_{3},\;TiO_{2}$ and MgO playa role of increasing dielectric constants at room temperature. These values were decreased at curie temperature. In case of $SiO_2$, the Curie temperature was decreased. In this study, a high dielectric ceramic capacitor material with temperature stability was synthesized by using various additives.
해외 태권도 시범공연 품질이 국가이미지, 한국태도 및 한국방문의도에 미치는 영향
노동연 ( Dong Yun Roh ),원형진 ( Hyung Jin Won ),김태일 ( Tae Il Kim ) 대한무도학회 2013 대한무도학회지 Vol.15 No.3
이 연구는 2013년 1월 미국 동부와 북부에서 태권도 시범공연을 관람한 관중을 대상으로 태권도 시범공연 품질이 국가이미지, 한국태도 및 한국방문의도에 미치는 영향을 알아보기 위하여 편의표본추출법(convenient sampling method)을 이용하여 246명의 자료를 사용하였으며, SPSS 18.0 프로그램과 AMOS 18.0 프로그램을 이용하여 빈도분석, 신뢰도분석, 확인적 요인분석, 상관분석, 구조방정식모형분석을 실시한 결과 다음과 같은 결론을 얻었다. 첫째, 태권도 시범공연 품질의 하위요인인 시범환경과 시범우수성은 국가이미지에 긍정적인 영향을 미치는 것으로 나타났으며, 관중배려는 국가이미지에 영향을 미치지 않는 것으로 나타났다. 둘째, 국가이미지는 한국태도에 긍정적인 영향을 미치는 것으로 나타났다. 셋째, 국가이미지는 한국방문의도에 긍정적인 영향을 미는 것으로 나타났다. 넷째, 한국에 대한 태도는 한국방문의도에 긍정적인 영향을 미치는 것으로 나타났다. The purpose of this study is learning the impact of overseas Taekwondo demonstration performance quality on state image, attitude toward Korea and intention to visit Korea. The study objects were audience who attended the Taekwondo demonstration performances held in the east and the north of United States during January 2013. Data from 246 audiences were collected by convenience sampling method. SPSS 18.0 and AMOS 18.0 were used on frequency analysis, reliability analysis, confirmatory factor analysis, correlation analysis and structure equation model analysis to get following conclusions. First, the demonstration environment and demonstration excellence, which are the sub-factors of Taekwondo demonstration performance quality, do not have positive impact on state image. Consideration on audience also does not have impact on state image. Second, state image has positive impact on attitude toward Korea. Third, state image has positive impact on intention to visit Korea. Fourth, attitude toward Korea has positive impact on intention to visit Korea.
연정운 ( Jung Woon Yeon ),원창환 ( Chang Whan Won ),원형일 ( Hyung Il Won ),( H. H. Nersisyan ) 대한금속재료학회 ( 구 대한금속학회 ) 2012 대한금속·재료학회지 Vol.50 No.6
YAG:Ce phosphor were prepared in a self-propagating high-temperature synthesis (SHS) using a 1.5Y2O3+2.5Al2O3+0.116CeO2+3.0KClO3+kCO(NH2)2+m(C2F4)n precursor mixture. The heat for the combustion propagation was provided by the reaction of a KClO3+CO(NH2)2+(C2F4)n mixture. Pure-phase YAG phosphor was synthesized at the combustion temperature of 1210℃ from k=3.6 mole and m=0.3 mole. The as-prepared YAG:Ce phosphor had a particle size of 2-10 ㎛. The addition of Teflon to the precursor mixture increased the YAG particle size and its luminescent intensity. The emission peak of the YAG phosphor was blue-shifted with an increase of Teflon concentration.
허건일(Gean Il Heo),강지원(Ji Won Kang),박원형(Won Hyung Park) 한국IT서비스학회 2013 한국IT서비스학회지 Vol.12 No.1
As the kind of IT service on the internet is more and more diversifying and increasing, IT service's adverse effects also consistently occurring. Among them the incident of private information exposure is becoming social issues. especially the exposure of private information entered on-line resume is very serious. This paper investigates whether or not data is encrypted in data transfer section of major on-line job-search sites of Korea by using the packet analyzer such as "Wireshark." This paper judges whether or not the vulnerability, private information exposure. exists from the result of the investigation above and suggests countermeasures.