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정명화,김재민,권용성 성균관대학교 기초과학연구소 1995 論文集 Vol.46 No.1
Dense Kondo계인 CeTe와 정상금속인 LaTe의 크기 양질인 단결정을 개선된 Bridgeman방법으로 성장시켰다. 이 단결정을 이용하여 0.05∼8eV의 광범위한 에너지 영역에서 반사율을 측정하여, Kramers-Kronig변환을 통해 광학전도도를 얻었다. 광학전도도의 스펙트럼을 분석한 결과, CeTe와 LaTe의 경우 모두 p-d 전이에 의한 두 개의 피크가 3.6eV와 5.1eV에서 발견되었다. 이 두 피크의 형성 mechanism은 5d-band의 입방결정장에 의한 것임을 알았다. 그리고 CeTe의 경우는 LaTe에 없었던 4f-5d전이에 의한 피크가 0.4eV에서 발견되었다. 이는 XPS 스펙트럼으로부터 얻은 bare 4f-전자의 binding 에너지(약 1.5eV)에 비해 매우 작은 값이다. 이 편차는 local field를 고려한 Lorentz모델을 적용함으로서 잘 설명되었다. 또한, localization의 정도로 약 0.4의 값을 얻었다. 끝으로, 띠내전이의 해석으로부터 LaTe의 경우보다 CeTe의 경우가 전도전자의 유효질량이 무겁다는 사실을 얻었다. 이것으로부터 CeTe의 여기상태인 Γ_8와 전도전자 간의 Kondo 교환상호작용의 에너지가 매우 크다는 것을 알았다. We had grown the high quality single crystals of dense Kondo system CeTe and normal metal LaTe by using the advanced Bridgeman method. The reflectivities of the single crystals were measured in wide energy range from 0.05 to 8eV, and their optical conductivities were obtained using Kramers-Kronig transformation. By the result of their optical conductivity spectra, two peaks due to p-d transition were discovered at about 3.6 and 5.1eV, respectively. The double peaks were explained by cubic crystalline electric field. And in case of CeTe, extraordinary peak due to f-d transition, which LaTe had not, was appeared around 0.4eV. This value was well explained by the Lorentz model considering the local field. The degree of screening due to conduction electrons was evaluated to be about 0.4. The effective mass of conduction electron of CeTe was large compared with that of LaTe. From this, we could obtain the fact that in CeTe, Kondo exchange energy between conduction electron and excited Γ_8 state was very large
희토류 monoantimonides에서 캐리어들과의 적외흡수 correlation
정명화,이경렬,조은상,권용성 성균관대학교 기초과학연구소 1996 論文集 Vol.47 No.1
The optical conductivity spectra were obtained in the single crystals LaSb, PrSb, GdSb and DySb at several temperatures. In these materials excepting LaSb, the spectra show Drude's behaviors with the hump due to an anomalous absorption lied at about 0.25eV. For quantitative analysis, we decomposed the spectrum into two parts; the free-electron absorption and the infrared absorption. The sum of the number of the effective electrons due to the Drude absorption and that due to the infrared absorption well agrees with the number of carriers obtained from their band calculations or their dHvAs. Thus, it is concluded that the infrared absorption is due to the transition of carriers.
희토류 monoantimonides에서의 특이한 적외흡수의 온도 의존성
정명화,조은상,권용성 성균관대학교 기초과학연구소 1996 論文集 Vol.47 No.1
The optical reflectivity spectra were measured on the single crystals LaSb, PrSb, GdSb and DySb at several temperatures. In the spectra of these materials excepting LaSb, the dip due to an anomalous absorption was found at about 0.25eV. The number of the effective electron N_LA taking part in the absorption was evaluated from quantitative analysis. The inverse of N_LA is linear to temperature and the N_LA at each temperature is dependent on square of the effective Bohr magnetron of each rare-earth ion. Therefore, this absorption seems to be due to the scattering between the spin of carriers and the localized magnetic moments at each site of rare-earth ion.
정명화,정성주 한국어병학회 2019 한국어병학회지 Vol.32 No.1
Rock bream iridovirus (RBIV) is a member of the Megalocytivirus genus that causes severe mortality to rock bream (Oplegnathus fasciatus) with characteristic clinical signs of spleen enlargement. In this study, we assessed spleen size and RBIV copy number patterns in RBIV-infected rock bream to determine lethal and safe levels of virus copy number/spleen index that may define disease progress. We found that rock bream infected with RBIV (1.1×107 virus copy number/100 μl) and held at 29, 26, 23 or 20°C exhibited significantly higher levels of spleen size compared to 17°C. In dead condition (100% mortality at 20~29°C), the spleen index (spleen weight / fish weight×100) and virus copy number were 3.00~5.38 and 106~108/μl, respectively. Conversely, in survived condition (0% mortality at 17°C), spleen index and virus copy number was as low as not-infected control (0.34~1.22/100~101/μl, respectively). These findings suggest that spleen index can be an indicator of disease severity of RBIV disease.
CERTAIN SUBGROUPS OF SELF-HOMOTOPY EQUIVALENCES OF THE WEDGE OF TWO MOORE SPACES II.
정명화 한국수학교육학회 2009 純粹 및 應用數學 Vol.16 No.2
In the previous work [5] we have determined the group [수식] for [수식] for all integers q > 1. In this paper, we investigate the group [수식] for all odd numbers q > 1 .
정명화,정엽,정대식,권종원,양중익,민신홍,Chung, Myung-Hwa,Jheong, Yeoub,Jheong, Dae-Sik,Kwon, Jong-Won,Yang, Joong-Ik,Min, Shin-Hong 한국약제학회 1988 Journal of Pharmaceutical Investigation Vol.18 No.1
Physicochemical properties of oil in water microemulsions containing soybean oil and egg phosphatide were observed for 3 weeks under the storage condition of $4^{\circ}C$ refrigerator. Changes in major fatty acid content, particle size distribution, rheogram, acid value and pH value were measured by gas chromatograph, laser particle sizer, Coulter counter and rheometer. From above experiments following conclusions were obtained; 1) Mean particle diameter was shifted from 240 to 266mm. 2) No significant changes were observed in the content of major fatty acids of soybean oil, rheogram, acid value and pH value.
Preparation and Luminescence of Europium-doped Yttrium Oxide Thin Films
정명화,김주한 한국진공학회 2017 Applied Science and Convergence Technology Vol.26 No.2
Thin films of europium-doped yttrium oxide (Y2O3:Eu) were prepared on Si (100) substrates by using a radio frequency (RF) magnetron sputtering. After the deposition, the films were annealed at 1000oC in an air ambient for 1 hour. X-ray diffraction analysis revealed that the Y2O3:Eu films had a polycrystalline cubic α-Y2O3 structure. The as-deposited films showed no photoluminescence (PL), which was due to poor crystalline quality of the films. The crystallinity of the Y2O3:Eu films was significantly improved by annealing. The strong red PL emission was observed from the annealed Y2O3:Eu films and the highest intensity peak was centered at around 613 nm. This emission peak originated from the 5D0→ 7F2 transition of the trivalent Eu ions occupying the C2 sites in the cubic α-Y2O3 lattice. The broad PL excitation band was observed at wavelengths below 280 nm, which was attributed to the charge transfer transition of the trivalent Eu ion.