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기상 공정에 의한 구형 형상의 헥사알루미네이트계 형광체 제조
정대수 ( Dae Soo Jung ),홍승권 ( Seung Kwon Hong ),구혜영 ( Hye Young Koo ),주서희 ( Seo Hee Ju ),강윤찬 ( Yum Chan Kang ) 한국화학공학회 2005 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.43 No.5
The morphology and photoluminescence characteristics of green light emitting hexaaluminate phosphor particles prepared by high temperature spray pyrolysis from spray solution with and without ammonium dihydrogen phosphate flux were investigated. The particles prepared from spray solution without flux material had hollow morphology at preparation temperatures between 900˚C and 1,650˚C. Ammonium dihydrogen phosphate flux added into spray solution enabled the formation of particles with spherical shape and filled morphology at preparation temperatures between 900˚C and 1,650˚C. The hexaaluminate phosphor particles with magnetoplumbite structure were directly prepared by spray pyrolysis from spray solution with ammonium dihydrogen phosphate flux above 1,600˚C. Ammonium dihydrogen phosphate flux was effective in improving the photoluminescence intensity of the phosphor particles at low preparation temperatures. The phosphor particles prepared from spray solution with and without flux material by spray pyrolysis under reducing atmosphere at 1,650˚C had comparable photoluminescence intensities with that of the phosphor particles optimized by post-treatment.
Windows mobile 연동 USB 메모리 스틱 데이터 전송용 보드 개발
정대수(Dae-Soo Jung),하윤수(Yun-Su Ha),정재오(Jae-Oh Jeong) 한국마린엔지니어링학회 2010 한국마린엔지니어링학회 학술대회 논문집 Vol.2010 No.10
Most modern people has a mobile phone, a PC and USB memory sticks for academic and business data storages. In the data of USB can not confirm without a PC, People face problems when they have to confirm or move quickly the files. To solve this problem we will develop small board for conjunction with a mobile phone and Windows Mobile Application for viewable USB system on screen and transfer files to another USB. So we're going to build system whenever and wherever you want see or transfer the files.
수크로스 함유 분무용액으로부터 분무열분해 공정에 의한 미세 Ba-Nd-Ti-O 분말 합성
고유나,정대수,구혜영,강윤찬,Ko, You-Na,Jung, Dae-Soo,Koo, Hye-Young,Kang, Yun-Chan 한국재료학회 2010 한국재료학회지 Vol.20 No.3
Nano-sized $BaNd_2Ti_5O_{14}$ powders were prepared by the spray pyrolysis process. Sucrose used as the organic additive enabled the formation of nano-sized $BaNd_2Ti_5O_{14}$ powders. The powders prepared from the spray solution without sucrose had a spherical shape, dense structure and micron size before and after calcination. However, the precursor powders prepared from the spray solution with sucrose had a large size, and hollow and porous morphology. The precursor powders had an amorphous crystal structure because of the short residence time of the powders inside the hot wall reactor. The complete decomposition of sucrose did not occur inside the hot wall reactor. Therefore, the precursor powders obtained from the spray solution with sucrose of 0.5M had a carbon content of 39.2wt.%. The powders obtained from the spray solution with sucrose of 0.5M had a slightly aggregated structure of nano-sized primary powders of $BaNd_2Ti_5O_{14}$ crystalline phase after calcination at $1000^{\circ}C$. The calcined powders turned into nano-sized $BaNd_2Ti_5O_{14}$ powders after milling. The mean size of the $BaNd_2Ti_5O_{14}$ powders was 125 nm.
분무열분해 공정에서 붕소 농도에 따른 Gd<sub>2</sub>O<sub>3</sub>:Eu 형광체의 GdBO<sub>3</sub>:Eu 형광체로의 전환
구혜영,정대수,주서희,홍승권,강윤찬,Koo, Hye-Young,Jung, Dae-Soo,Ju, Seo-Hee,Hong, Seung-Kwon,Kang, Yun-Chan 한국재료학회 2006 한국재료학회지 Vol.16 No.3
The transition of europium-doped gadolinium oxide phosphor to gadolinium borate phosphor with the concentration of boron in the spray pyrolysis was investigated. The particles prepared from spray solution below 10 wt% boric acid of prepared phosphor had crystal structure of $Gd_2O_3:Eu$ phosphor, in which the crystallinity of the particles decreased with increasing the boron concentration. A single phase $GdBO_3:Eu$ phosphor particles were prepared from spray solution above 50 wt% boric acid of prepared phosphor. The phosphor particles prepared from spray solution with 20 wt% boric acid of prepared phosphor had no XRD peaks of $Gd_2O_3:Eu$ and $GdBO_3:Eu$ Therefore the phosphor particles prepared from spray solution with 20 wt% boric acid of prepared phosphor had the lowest photoluminescence intensity under ultraviolet and vacuum ultraviolet. $GdBO_3:Eu$ and $Gd_2O_3:Eu$ phosphor particles prepared from spray solutions with proper concentrations of boric acid had good photoluminescence intensity under vacuum ultraviolet. The morphology of the phosphor particles were strongly affected by the concentrations of boric acid added into spray solution.
NH<sub>4F</sub> 융제가 바륨 스트론튬 실리케이트계 형광체의 특성에 미치는 영향
강희상,구혜영,정대수,주서희,홍승권,강윤찬,정경열,박승빈,Kang Hee Sang,Koo Hye Young,Jung Dae Soo,Ju Seo Hee,Hong Seung Kwon,Kang Yun Chan,Jung Kyeong Youl,Park Seung Bin 한국재료학회 2005 한국재료학회지 Vol.15 No.6
[ $Ba_{1.5}Sr_{0.5}SiO_4:Eu$ ] phosphor particles with high photoluminescence intensity under long wavelength ultraviolet were prepared by spray pyrolysis. We investigated the effect of $NH_4F$ flux added into starting solution on the morphology and photoluminescence intensity of $Ba_{1.5}Sr_{0.5}SiO_4:Eu$ phosphor prepared by spray pyrolysis. $Ba_{1.5}Sr_{0.5}SiO_4:Eu$ phosphor particles prepared from starting solution containing $NH_4F$ flux had the maximum photoluminescence intensity at the post-treatment temperature of $1200^{\circ}C$ and the maximum photoluminescence intensity of $Ba_{1.5}Sr_{0.5}SiO_4:Eu$ phosphor particles prepared from the starting solution containing $NH_4F$ flux was $137\%$ of that of the phosphor particles prepared from the starting solution without flux material. $Ba_{1.5}Sr_{0.5}SiO_4:Eu$ phosphor particles prepared from starting solution containing $NH_4F$ flux had larger size and more aggregated morphology than those prepared from starting solution without flux material. The photoluminescence intensity of $Ba_{1.5}Sr_{0.5}SiO_4:Eu$ phosphor particles prepared from starting solution containing $NH_4F$ flux above $3wt.\%$ had high photoluminescence intensities. The addition amount of $NH_4F$ flux showing the maximum photoluminescence intensity was $12wt.\%$. The optimum amount of $NH_4F$ flux was $5wt.\%$ when we considered the morphological and photoluminescence characteristics of $Ba_{1.5}Sr_{0.5}SiO_4:Eu$ ohosphor particles prepared by spray pyrolysis.
입자 크기에 따른 물/에틸렌글리콜 기반 알루미나 나노유체의 열전도도
최태종(Tae Jong Choi),김수빈(Soo Bin Kim),장석필(Seok Pil Jang),정대수(Dae Soo Jung),임형미(Hyung Mi Lim) 대한기계학회 2018 大韓機械學會論文集B Vol.42 No.3
본 논문에서는 입자 크기에 따른 물/에틸렌글리콜 기반 알루미나 나노유체의 열전도도 특성을 실험적으로 연구하였다. 이를 위해 물/에틸렌글리콜 기반 알루미나 나노유체를 Modified two-step method를 이용하여 제작하였다. 나노유체 속에 분산된 입자의 크기는 Particle Size Analyzer(PSA)로 분석하였으며, 나노유체의 열전도도는 비정상열선법(Transient Hot Wire Method)을 이용하여 측정하였다. 나노입자의 크기는 RCF×h가 증가할수록 감소하는 것을 확인하였으며, 입자의 크기가 감소할수록 온도에 따라 열전도도가 상승하는 온도 의존성이 나타나는 것을 확인하였다. 또한, 단위부피당 열전도도 측정 결과, 입자의 크기가 작을수록 열전도도 향상 폭이 더 높은 것을 실험적으로 확인하였다. This paper experimentally reports the effect of particle size on the thermal conductivity of water/ethylene glycol-based alumina nanofluids. For this study, the water/ethylene glycol-based alumina nanofluids was manufactured using the modified two-step method. The particle size dispersed in nanofluids was measured by the particle size analyzer, and thermal conductivity of nanofluids was measured by the transient hot wire method. The particle size decreased with total RCF and the temperature dependence of nanofluids was observed as the particle size decreased. Moreover, it was experimentally confirmed that the nanofluids exhibit higher thermal conductivity as the particle size decreased.
이혜영,이기정,전은희,신상현,이재헌,김도훈,정대수,정용모,조용조,김정국,정영수,Lee, Hye-Young,Lee, Ki-Jung,Jeon, Eun-Hee,Shin, Sang-Hyun,Lee, Jai-Heon,Kim, Doh-Hoon,Chung, Dae-Soo,Chung, Yong-Mo,Cho, Yong-Cho,Kim, Jeong-Kook,Chung, You 한국식물생명공학회 2006 식물생명공학회지 Vol.33 No.1
본 연구에서는 거베라 형질전환 기초기술개발을 위한 연구를 수행하였다. 경남원예화훼시험장에서 육성된 국내 거베라 18품종 중, Agrobacferium 감염에 순응적인 품종을 선발하기 위하여 18개의 국내 거베라 품종을 스크린하여 011, 016, GM023 등 12개의 순응형 계통을 스크린 하였으며 효율적인 형질전환을 위한 제균 항생제로는 cefotaxime이 선택되었다. 더 많은 캘러스 유도를 위한 전처리 배지의 호르몬 농도는 BA 2 ppm, Zeatin 2 ppm, IAA 0.2 ppm (2 x media)이 효율적이었고 재분화 배지의 호르몬 농도도 전처리 배지 호르몬의 농도와 동일하게 BA 2 ppm, Zeatin 2 ppm, IAA 0.2 ppm (2 x media)에서 효율적이었으나 GUS 발현에는 다른 차이가 없었다. 고효율 형질전환 체계 확립을 위하여 네 가지 다른 전처리 기간 처리와 두 가지 다른 Agrobacterium tumerfaciens 사용, 두 가지 다른 공배양 기간을 처리한 결과 전처리 하지 않은 엽병과 엽신을 LBA4404 Agrobacterium tumerfaciens을 사용하여 5일 간 공배양 기간을 가졌을 때와 dipping 처리하여 접종한 엽병과 엽신에서 높은 GUS 발현빈도를 나타냈다. Gerber (Gerbera hybrida) is a valuable ornamental species grown as a potted plant and cut flowers. However, genetic variability within the gerbera genus is very limited. So it is absolutely needed to introduce and widen genetic resources into gerbera lines by genetic transformation. For the purpose, 18 Korean gerbera lines were screened to establish Agrobacterium-mediated genetic transformation procedure. In an experiment to select Korean gerbera lines which are amenable to Agrobacterium-inoculation, 12 lines turned out to be positive in Agrobacterium-inoculation. More callus were produced from BA 2ppm, Zeatin 2ppm, IAA 0.2ppm in pre-culture and regeneration medium (2X media) but there was no difference in the frequency of GUS expression rate. In another experiment to find out optimal condition for highly efficient Agrobacterium-inoculation, petiole and leaf explants have been treated with four different pre-culture periods, two different co-culture periods and two different Agrobacterium strains. As a result, high GUS expression has been showed from petiole and leaf explants treated no pre-culture period with LBA4404 Agrobacterium tumerfaciens, 5 day co-culture period and dipping treatment.
김동헌(Dong-Heon Kim),정진섭(Jin-Sup Jung),정대수(Dae Soo Jung) 한국의학교육학회 1999 Korean journal of medical education Vol.11 No.1
PBL은 교수중심이 아닌 학생중심의 강의이며 적절한 문제를 개발하여 효율적으로 적용할 경우 기존의 교과개념을 넘어서서 의학에 대한 기초지식이 없는 학생들을 대상으로도 PBL을 중심으로한 통합교육을 실시할 수도 있다. 그러나, 이를 효과적으로 적용하기 위해서는 효율적인 교과과정의 개편이 선행되고 학습목표를 달성하기 위하여 PBL을 적용할 범위를 사전에 명확히 하는 것이 필요하며 유용한 학습자료의 확보, 교수진의 수와 학생의 수, 예산등 기타요인도 이에 영향을 미칠 수 있을 것이다. A key factor in successful application of PBL is creation of good problems. Unfortunately, published collections of problems do not exist for many subjects. Consequently, instructors usually write their own problems and case studies if they want to use problem-based instruction. In this study we proposed principles for creation of PBL problems and presented its example. If effective problems suitable to educational goals are engaged, PBL can be introduced to the first grade medical students who do not have any knowlege about medicine. However, additional factors such as number of faculties and students, budget, availability of learning materials also affect successful implementation of PBL.