• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.11
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• pp.1212-1217
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• 2004

Red organic electroluminescent (EL) devices based on tris(8-hydroxyquinorine aluminum) (Alq$_3$) doped with red emissive materials, 4-(dicyanomethylene)-2-t-butyl -6-(l,1,7,7-tetramethyljulolidyl-9-enyl)4H-pyran (DCJTB). poly(3-hexylthiophene) (P3HT). rubrene and 4-dicyanomethylene-2-methyl-6[2-(2,3.6.7-tetrahydro-lH,5H-benzo-[i,j]quinolizin-8yl)vinyl]-4H-pyran (DCM2) were fabricated for applying to the red light source, The photoluminescence (pL) intensities of red emissive materials doped in Alq$_3$ are limited by the concentration quenching with increasing the doping ratio and the doping concentration of DCJTB, DCM2, P3HT and rubrene measured at the maximum intensity showed 5, 1, 0.5 and 2 wt%, respectively. Time-resolved PL dynamic results showed that the PL lifetime of red emissive materials doped in Alq$_3$ were increased more than the value of material itself. It means that the efficient energy transfer occurred in the mixed state and Alq$_3$ is a suitable host materials for red emissive materials, The device which was used DCJTB as a dopant achieved the best result of the maximum luminance of 594 cd/$m^2$ at 15 V and showed the chromaticity coordinates of x=0,624, y=0,371.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.12a
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• pp.48-52
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• 2006

Phospho-olivine $LiFePO_4$ cathode materials were prepared by hydrothermal reaction. Carbon black was added to enhance the electrical conductivity' of $LiFePO_4$. The structural and morphological performance of $LiFePO_4$ and $LiFePO_4$-C powders were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). $LiFePO_4$/Li and $LiFePO_4-C$/Li cells were characterized electrochemically by cyclic voltammogram (CV), charge/discharge experiments and ac impedance spectroscopy. The results showed that the discharge capacity of $LiFePO_4$/Li cell was 147 mAh/g at the first cycle and 118 mAh/g after 30 cycles, respectively. The discharge capacity of $LiFePO_4-C$/Li cell with 5wt% carbon black was the largest among $LiFePO_4-C$/Li cells, 133 mAh/g at the first cycle and 128 mAh/g after 30 cycles, respectively. It was demonstrated that cycling performance of $LiFePO_4-C$/Li cell with 5wt% carbon black was better than that of $LiFePO_4$/Li cell.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.307-310
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• 1999

Using Se as a photoconductive element and ZnS as a luminescent element, a Se/ZnS thin film device for light amplifier applications was fabricated and its characteristics were investigated. The Se/ZnS thin film light amplifier was fabricated by evaporating the ZnS thin film on an ITO(Indium Tin Oxide) glass and the Se thin film on the ZnS thin film in sequence. The results of the characteristics investigation are summarized as follows: (1) When the frequency of an excitation voltage was increased, both the brightness response and the brightness saturation of the Se/ZnS thin film light amplifier began to start at a higher light input. (2) The gain of the Se/ZnS thin film light amplifier was dependent upon the amplitude and the frequency of the excitation voltage as well as an external light input. (3) When the Se/ZnS thin film light amplifier was excited by a direct current of a constant voltage, the frequency of the output brightness was\\`equal to the frequency of the input light applied. When the light amplifier was excited by a sinusoidal voltage of 60 Hz, the frequency of the output brightness was 120 Hz.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.10
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• pp.817-821
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• 2011

We have proposed an optical thin film and micro lens to improve the luminance of organic light emitting device. The first method, optical thin film was calculated refractive index of dielectric layer material that was modulated refractive index of organic material, ITO (indium tin oxide)and glass. The second method, microlens was applied with lenses on the organic device. Optical thin films were designed with Macleod Simulator and Micro Lenses were calculated by FDTD (finite-difference time-domain) solution. The structure of thin film was designed in organic material/ITO/dielectric layer/glass. The lenses size, height and distance were 5 ${\mu}m$, 1 ${\mu}m$, 1 ${\mu}m$, respectively. The material of micro lenses used silicon dioxide. Result, The highest luminance of OLED which applied with microlens was 11,185 $cd/m^2$, when approval voltage was 14.5 V, applied thin film was 5,857 $cd/m^2$. The device efficiency applying microlens increased 3 times than the device which does not apply microlens.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.115-115
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• 2000

Wide band gap을 갖는 III-V족 반도체인 GaN는 파란색에서 자외선영역에 이르는 발광소자용으로, 그리고 최근에는 전자소자로도 가장 유망한 반도체 중의 하나이다. 하지만 격자상수가 일치하는 적당한 기판이 존재하지 않아 성장된 GaN 박막 내에는 많은 결함들이 존재하게 된다. 일반적으로 가장 널리 쓰이는 기판은 사파이어 기판이 주로 이용되고 있는데 사파이어는 GaN와 격자상수 불일치가 16%에 이르므로 고품질의 GaN 박막을 성장시키기 위해서는 격자상수 불일치를 어느 정도 완화시키면서 초기성장과정의 컨트롤이 매우 중요하다. 이러한 방법들로는 GaN박막 성장 전에 사파이어 기판 질화처리를 하거나 buffer 층을 도입하는 것인데, 이에 관한 많은 연구들이 보고되고 있다. 하지만 각각 두 공정에 관한 연구는 많이 되어 있지만 두 공정사이를 연결해 주는 공정처리법에 관한 연구는 보고되고 있지 않다. 따라서 본 연구에서는 사파이어기판 질화처리를 한 후 buffer 층을 성장시키기 전까지 chamer 내부의 분위기 가스가 GaN 박막성장 거동에 어떤 영향을 주는지에 관해 연구하였다. 질화처리 후 chamber 내부의 분위기 가스가 GaN 박막 성장 거동에 미치는 영향을 연구하기 위하여 두 개의 시편 A,B를 준비하였다. 시편 A는 먼저 사파이어 기판을 유기용매를 이용하여 cleaning 한 후 장비에 장입되었다. 수소분위기하에서 10nsrks 104$0^{\circ}C$에서 가열한 후 30초간 암모니아 유속을 900sccm으로 유지하며 사파이어 기판 질화처리를 수행하였다. GaN buffer 층을 성장하기 위하여 104$0^{\circ}C$에서 56$0^{\circ}C$로 온도를 내리는 과정중 질화처리를 위하여 흘려주었던 암모니아 유속을 차단한 채 수소분위기에서만 온도를 내렸다. 56$0^{\circ}C$에서 GaN buffer 층을 300 성장시킨 후 102$0^{\circ}C$의 고온에서 2$\mu\textrm{m}$ 두께로 GaN 박막을 성장하였다. 시편 B는 질화처리 후 단계부터 GaN 박막성장 단계에 이르기까지 AFM을 이용하여 두 시편의 성장거동을 비교 분석하였다. 두 시편의 표면을 관찰한 결과 시편 A는 2차원적 성장을 하며 매우 매끄러운 표면을 갖는데 반해, 시편 B는 3차원적 성장을 하며 매우 거친 표면을 보였다. 또한 두 시편 A, B를 XRD, PL, Hal 측정으로 분석한 결과 시편 A가 시편 B보다 우수한 구조적, 광학적, 전기적 특성을 보였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.441-441
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• 2009

Dye-sensitized solar cells (DSSCs) have been widely investigated as a next-generation solar cell because of their simple fabrication process and low coats. The cells use a porous nanocrystalline TiO2 matrix coated with a sensitizer dye that acts as the light-harvesting element. The photo-exited dye injects electrons into the $TiO_2$ particles, and the oxide dye reacts with I- in the electrolyte in regenerative cycle that is completed by the reduction of $I_3^-$ at a platinum-coated counter electrode. Since $TiO_2$ porous film plays a key role in the enhancement of photoelectric conversion efficiency of DSSC, many scientists focus their researches on it. Especially, a high light-to-electricity conversion efficiency results from particle size and crystallographic phase, film porosity, surface structure, charge and surface area to volume ratio of porous $TiO_2$ electrodes, on which the dye can be sufficiently adsorbed. Effective treatment of the photoanode is important to improve DSSC performance. In this paper, to obtain properties of surface and dispersion as nitric acid treated $TiO_2$ photoelectrode was investigate. The photovoltaic characteristics of DSSCs based the electrode fabricated by nitric acid pre-treatment $TiO_2$ materials gave better performances on both of short circuit current density and open circuit voltage. We compare dispersion of $TiO_2$ nanoparticles before and after nitric acid treatment and measured Ti oxidized state from XPS. Low charge transfer resistance was obtained in nitric acid treated sample than that of untreated sample. The dye-sensitized solar cell based on the nitric acid treatment had open-circuit voltage of 0.71 V, a short-circuit current of 15.2 mAcm-2 and an energy conversion efficiency of 6.6 % under light intensity of $100\;mWcm^{-2}$. About 14 % increases in efficiency obtained when the $TiO_2$ electrode was treated by nitric acid.

• Journal of Animal Science and Technology
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• v.46 no.3
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• pp.295-300
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• 2004

The identification of the leptin gene in 1994 and it's adipocytes specific protein leptin hal provided the first physiological links to the regulatory system controlling body weight and fat deposits. The meat tastes is mainly determined by quantifY and quality of triglyceride stored in adipose tissue. This study was conducted to analyze genetic cbaracteristics of Hanwoo leptin gene and also to investigate the association of DNA marlcer with some economic meat traits for Hanwoo. The leptin hormone gene polymorphisms were identified by digestion with Kpn2 I and Msp I. Slaughter weight(SWI), slaughter peroentage(SP), longissimus muscle area(LMA), beef marbling score(MS) and back fat thickness(BF) were compared among three genotypes by P(R..RFlJ> and showed significant differences among genotypes. PCR-RFLP(Kpn2 I) were detected significant for SP, MS and BF. The allele was essociated with fatter carcasses and C allele with leaner carcasses.

• Journal of Animal Reproduction and Biotechnology
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• v.35 no.2
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• pp.190-197
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• 2020

The effects of the number of frozen-thawed ram sperm per single and double intra-cervical artificial insemination (AI) on fertility in ewes were studied. A total of 89 non-pregnant ewes were synchronized for oestrus with two doses of 100 ㎍ PGF_2α (Cloprostenol) 9 days apart. The ewes were randomly assigned to one of four groups; D200 (n = 23; double AI with 200 × 10⁶ sperm), S200 (n = 24; single AI with 200 × 10⁶ sperm), D100 (n = 24; double AI with 100 × 10⁶ sperm) and S100 (n = 18; single AI with 100 × 10⁶ sperm). Ewes were inseminated within 12 to 18 h for single AI and, within 10 to 12 h and 16 to 18 h for double AI after the onset of oestrus. The onset of oestrus ranged from 28 to 76 h (54.33 ± 1.28 h). The high percentage (29.2%) of ewes showed oestrus between 51 to 60 h. The non-return rates were highest in group D200 (56.5%) and differed significantly (p < 0.05) from group S100 (11.1%). No ewes were pregnant in group S100, and the pregnancy rates among the remaining groups did not differ. The mean gestation period was 152.8 ± 0.5 days and no difference was observed among the groups. The lambing and multiple birth rates were 100% in group D200. The single and twin lambing was highest in group D100 (33.3%) and group D200 (83.3%), respectively. Only one triplet lambing and the highest lambing size (2.2 ± 0.2) was recorded in group D200. In conclusion, double AI with 200 × 10⁶ sperm showed comparatively most practical for achieving high pregnancy rates and lambing performances in Bangladeshi ewes under field conditions.

• Journal of Korean Library and Information Science Society
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• v.4
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• pp.61-90
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• 1977

The historical development of books examination with utilizing science become inevitable to the machanization of library catalogues. With the advance of times, like this, a new- development of $Indention('||'&'||'$ : Kisun) must be sought for which is a kind of descriptive catalogues being used now. This paper is scheduled to grasp problems in the course of using and logical grounds of Indention which hal-e been used disordering. It must be considered that four kinds of Icdention settlement is suitable to the features of Korean letters. 1) TI-e must consider the features of Korean Language and Oriental Language writing(Japan, China). There must be a establishment of floating $Indention('||'&'||'E$ : Kisun), which are suitable for the writting style or hand writting man on the point of most of Koreans are depend upon hand witting, then books catalogues like western language, not left edge of the cards of the $Indention(B$ : Kisun) establishing, from edge to Call Number, from the last of the Call Number to First Indention(%-Bl63). First Indention(%-%%) to a space of Second $indention($\ulcorner^%)$ must be established and then, every catalogue and Indentions are distinguished surely. 2) \Then we consider the developing catalogue making in the future. It is important to establish a fixed $Indention('||'&'||'$ : Kisun) for machinization of typewriter(Korean, Mimeographing) and computer, etc ... not "Cm" unit but "Space" unit, and consider oriental letter, ne make more surplus space as a Indention, we can give anadaptablity of using machines. 3) Considering typography printing and type-setting printing by printing type, we must fit the $Indention(\ulcorner'||'&'||'$ : Kisun) as a "Cm" unit, and there must be a re-adjustment of $Indention(g$$ : Kisun) which considered the complexity of Call Number by a mass of collecting books like this, the establishment of Indention(E'||'&'||'j!: Kisun). We must not use a uilified one as a concrete conception by "Space" or "Cm" unit which has been used now but re-adjusted adaptably which can be fited as a method of making of catalogues. 4) The name of $Indcntion(J, S$ : Kisun) has becll called 7;arious methods until now, but English Indention which has been used without any concrete mexirig must be used as a ours fitable as a our mind. The above mentioned is presented as a Indention and examinational l~letilods by myself style, I wants these r i l l be helpful to the future developments of the machanization of Indention $(sf:$ Ki sun). Concrete studies must be continued in the future for development of $Indention(zj:$ : Kisun). : Kisun).

• Korean Journal of Crystallography
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• v.2 no.2
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• pp.13-21
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• 1991

X-ray methods have been used to determine the chain conformation and packing of the thermotropic liquid crystalline copolyester prepared from 50% tarephthaloyl chloride(TPA) and 50% (1-phenylethyl) hydroquinone(PEHQ). The x-ray patterns of annealed melt-spun fibers contain a series of annealed melt-Pointing to a well ordered crystalline structure, despite the random sense(2 or 3-) of the 1-phenylethyl substiuttion on the TPA-hydroquinone backbone. The crystalline fiber is monoclinic with space group P2l and the unit cell has dimensions 11=12.77 A, b=10.17 A (upique axis), c=12.58 h (fiber axis). and β=90.1° and contains TPA-PEHO units of to or chains. The random substitution of 1-phenylethyl groups was modelled by placing these groups at both the 2and 3 positions and giving each a weight of one-hal(. T he structure has been refined by linked a rom least square methods(LALS) against 16 observed and 21 unobserved reflections. and had a final R value of 0.20. Packing of the side chains is effected by staggering adjacent chains along the b axis by approximately c/2, so that the side chains are interleaved. The phenyl-COO and COO-phenyl torsion angles are -6.1 and 65.6, respectively, such that the main chain phenyls are mutually inclined at 59.5 (the ester groups are assumed to be planar). These torsion angles compare very well with those for the model compounds, notably phenylbenzoate, and can be used in future analyses of the structures of more complex random sequence copolyesters.