Hydrophobic Coating of Y2O3:Eu Phosphors by Using HMDSO/Toluene Plasma at Low Pressure and Their Wettability

Han S. Uhm,Kyung H. Lee,Soon C. Cho,Sung Y. Jo,Chan U. Bang,Dong K. Lee 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.2

Surface treatments of Y2O3:Eu phosphors for improving the hydrophobic property were carried out using plasmas generated from a O-(Si(CH3)3)2 (HMDSO) in a low-pressure environment. The super-hydrophobic properties of the treated Y2O3:Eu phosphors were investigated. The samples treated by using the HMDSO/toluene glow plasma were analyzed by FTIR and OES and analyzed in terms of their contact angles (CAs). The effects of the HMDSO/toluene plasma treatments on the Y2O3:Eu phosphors were investigated in terms of the total surface free energy by using probe liquids to measure their contact angles (CAs). The total surface free energy of the Y2O3:Eu phosphors before and after a surface treatment with the HMDSO/toluene plasma, as estimated via the Owens-Wendt equation, was found to decrease from 82.2 mJ/m2 to 0.021 mJ/m2. This represents a significant improvement of the hydrophobicity of the Y2O3:Eu phosphors after the plasma treatment.

Mossbauer Study of Ti₁-x-yCoxFeyO₂

Eng Chan Kim,S. R. Lee,T. H. Kim,Y. S. Ryu,J. H. Cho,Y. G. Joh,D. H. Kim 한국자기학회 2006 韓國磁氣學會誌 Vol.16 No.1

Mossbauer spectra of Ti₁-x-yCoxFeyO₂ (0.01≤x, y≤0.05) prepared with (57)^Fe enriched iron have been taken at various temperatures ranging from 80 to 300 K. The Mossbauer spectrum of Ti0.94Co_(0.03)Fe_(0.03)O₂ consists of a ferromagnetic (six-Lorentzian), a paramagnetic phase (doublet) and armorphous phase over all temperature ranges. Isomer shifts indicate Fe³+ for the ferromagnetic phase and the paramagneic phase of Ti₁-x-yCoxFeyO₂ samples. It is noted that the magnetic hyperfine field of ferromagnetic phase had the value about 1.5 times as large as that of α-Fe. The XRD data for Ti₁-x-yCoxFeyO₂ showed mainly rutile phase with tetragonal structures without any segregation of Co and Fe into particulates within the instrumental resolution limit. The magnetic moment per (Co+Fe) atom in Ti_(0.94)Co_(0.03)Fe_(0.03)O₂ under the applied field of 1 T was estimated to be about 0.332μB which is ten times as large as that of Ti_(0.97)Co_(0.03)O₂, 0.024μB per Co atom, suggesting a high spin configuration of Co and Fe ions.

Effect of the Sintering Additives on the Microstructure and the Properties of Textured Silicon Nitride

Park, Dong Soo,Kim, Y.M.,Hahn, Byung Dong,Park, Chan Trans Tech Publications, Ltd. 2005 Key Engineering Materials Vol.287 No.-

<P>Silicon nitride samples without and with 3 wt% of the aligned b-silicon nitride whisker seeds were prepared with 8.2 wt% Er2O3 and 1.9 wt% AlN. After sintering at 2148 K for 4h, the samples exhibited densities higher than 99.5% TD. The microstructures and properties of the samples were compared with those of the samples sintered with 4.8 wt% Y2O3 and 2.2 wt% Al2O3 at 2273 K for 4h. For samples without the whiskers, the sample with 4.8 wt% Y2O3 + 2.2 wt% Al2O3 had coarser microstructures than those with with 8.2 wt% Er2O3 + 1.9 wt% AlN. However, the samples with the whisker seeds, the former sample appeared to have only slightly larger grains than the latter sample in spite of the significant difference in the sintering temperatures. For the samples without the whisker seeds, the room temperature flexural strength was higher for the sample with Er2O3 + AlN. However, for the samples with the aligned whisker seeds, the sample with Y2O3 + Al2O3 exhibited higher room temperature flexural strength than that with Er2O3 + AlN although the average grain width of the former sample was larger than that of the latter sample. In case of the high temperature flexural strength at 1673 K, the flexural strengths of the samples with the whisker seeds were higher than double the strengths of the samples without the whisker seeds. For samples without the whisker seeds, the sample with Er2O3 + AlN exhibited better mechanical properties than that with Y2O3 + Al2O3. However, for the samples with the aligned whisker seeds, the sample with Y2O3 + Al2O3 exhibited better mechanical properties than those with Er2O3 + AlN. The results were explained in terms of the microstructures of the samples.</P>

다양한 거리측도의 VQ를 이용한 우리말 단음절어의 전이구간 인식

백인찬,김민수,권영헌,이건상 漢陽大學校 工學技術硏究所 1996 工學技術論文集 Vol.5 No.1

We study word recognition by using the vector quantization. Using asymmetrical rate, transition intervals are detected from 686 monosyllables having the form of "14 initial consonants +7 single vowels + 7 final consonants". To recognize the transition intervals, the following steps are used. First of all, the LPC coefficients in the transition intervals are evaluated. And the vector quantization method is applied with various distance measure. According to the experimetal result, it is shown that recognition rate of speech by using the distance measure of lower order is better than that of higher order.

LTCC를 이용한 MCM VCO 제작에 관한 연구

이영신,곽승범,유찬세,이우성,강남기,박종철 한국마이크로전자및패키징학회 2000 추계 기술심포지움 논문집 Vol.2 No.1

B2B 거래에서 서술모델과 예측모델을 이용한 고객가치 산정

박찬주,박윤선,주상호,유우연 한국경영과학회 2003 經營 科學 Vol.20 No.2

Developing a proper program for customer evaluation is one of the most imminent CRM(Customer Relationship Management). Design of the Customer Value model is an important key to the customer evaluation program. This paper proposes two models for estimating Customer Value. The first one is a Description Model for Customer Value based on customer CSI(Customer Satisfaction Index) data. This model represents as quantitative numbers what customers feel from the company or the service. The second one is a Prediction Model which employs factor analysis and regression to predict customer value. This paper exploits the two models to evaluate Customer Value as well as for customer behavior prediction.

유전자 알고리즘을 이용한 음성의 특징 벡터 코드북의 성능 분석

이건상,백인찬,서정파,전병우,권영헌 漢陽大學校 自然科學硏究所 1999 自然科學論文集 Vol.18 No.-

음성의 특징벡터 코드북을 형성하는 벡터 양자화 과정에서 진화 및 유전원리에 기초한 유전자 알고리즘으로 얻어진 코드북과 기존의 LBG알고리즘으로 얻은 코드북사이의 인식 성능을 비교하였다. 이를 위해 유전자 알고리즘에서 초기 개체집단을 형성할 때 훈련벡터들의 초기분포를 반영하도록 하였고, 유전 연산자로 교배와 돌연변이 연산자를 사용하였다. 인식 성능을 비교하기 위해 특징 벡터로는 주파수 대역별 에너지와 LSF계수를 사용하여 화자종속으로 인식실험을 수행하였다. 실험결과 LBG 알고리즘을 사용한 코드북보다 유전자 알고리즘을 사용한 코드북의 인식 성능이 우수함을 살펴 볼수 있었다. In the development of speech codebook by vector quantization method, we compared the performance of the codebook by LBG algorithms with that by genetic algorithms based on the biological process of evolution and genetic principle. We reflected a initial distribution of training vectors to set up a initial population in genetic algorithm. The crossover and mutation are used as genetic operators. We performed the recognition experiments in speaker-dependent method using the feature vectors as the nomalized energies in frequency domain and LSF coefficients. So we investigated the recognition performance of the codebook by the above two algorithms. We have known that the recognition performance of the codebook by the algorithm is better than that by the LBG algorithm.

수상관의 밝기 및 해상도를 고려한 기준 백색 설정

최덕규,한찬호,정영헌 경운대학교 산업기술연구소 2001 産業技術硏究論文誌 Vol.3 No.2(C)

Reference white in color television receiver can be achieved by adjusting the RGB gun current ratio and it is necessary to provide additional gain ratio adjustment for the RGB video signal. Generally, the gun current density profile has a Gaussian distribution and the gain-bandwith product of RGB channel amplifier is constant. Therefore brightness and spatial resolution are changed with variations in reference white of receiver. In this paper, the effect of RGB gun current and channel gain ratios on brightness and resolution of CPT is analyzed. Brightness is increased with the color temperature of reference white because of Holmholtz-Kohlrausch effect. The change in light output is more abrupt and spatial resolution is improved with unity current ratio. For more bright and improved resolution we also present the range of color temperature of reference white for P22 phosphors.

Vibrio cholerae Serogroup Non-01에 의한 간경변 환자의 패혈증 3예

시마다 도시오,전재윤,정재복,이상인,이삼열,정윤섭 대한감염학회 1991 감염 Vol.23 No.2

In Korea, highly fatal Vibrio vulnificus septicemia is not a rare disease. V. cholerae serogroup non-O1 causes intestinal and extraintestinal infections. In 1987 and 1989, the authors isolated V. cholerae O5, O10 and O24 from blood cultures of three patients with liver cirrhosis. Two patients ate raw sea food before the infection. The growths of the isolates from blood cultures were detected relatively rapidly. Some of the biochemical characteristics of the isolates were similar to those of other species, but API 20E and Vitek systems correctly identified them. The isolates were susceptible to various antimicrobial agents and the patients recovered after antimicrobial therapy. It is concluded that as the infection is not rare in Korea, both clinicians and microbiologists should consider the possibility of V. cholerae non-O1 infection, besides V. vulnificus infection, when they have septicemic patients during the summer months.

QMF를 이용한 우리말 숫자음 인식에 관한 연구

남호정,양성일,백인찬,권영헌,이건상 漢陽大學校 工學技術硏究所 1996 工學技術論文集 Vol.5 No.1

In this study, QMF is used for recognition of Korean digits from /Young/(zero) to /Geo/(nine). The frequency band is divided into 8 bands and 16 bands. Each digit was pronounced repeatly 15 times by one man speaker so that 150 sample digits were used to be divided into 8 bands and 16 bands. The recognition of Korean digits was proposed and carried out to use the energy in each band. The recognition was done and compared according to the number of candidate patterns to be recognized. Experiments resulted in remarkably good recognition rate when the number of candidate patterns are above a threshold value.