• Journal of Information Display
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• 제8권3호
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• pp.5-10
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• 2007

Twin target sputtering (TTS) system with a configuration of vertically parallel facing Al targets and a substrate holder perpendicular to the Al target plane has been designed to realize a direct Al cathode sputtering on organic light emitting diodes (OLEDs). The TTS system has a linear twin target gun with ladder type magnet array for effective and uniform confinement of high density plasma. It is shown that OLEDs with Al cathode deposited by the TTS show a relatvely lower leakage current density $({\sim}1{\times}10^{-5}mA/cm^2)$ at reverse bias of -6V, compared to that ($1{\times}10^{-2}{\sim}10^{-3}$ $mA/cm^2$ at -6V) of OLEDs with Al cathodes grown by conventional DC magnetron sputtering. In addition, it was found that Al cathode films prepared by TTS were amorphous structure with nanocrystallines due to low substrate temperature. This demonstrates that there is no plasma damage caused by the bombardment of energetic particles. This indicates that the TTS system with ladder type magnet array could be useful plasma damage free deposition technique for direct Al cathode sputtering on OLEDs or flexible OLEDs.

• E2M - 전기 전자와 첨단 소재
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• 제7권4호
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• pp.289-293
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• 1994

Thin films of YB $a_{2}$C $u_{3}$$O_{7-x}$ supercondYB $a_{2}$C $u_{3}$$O_{7-x}$uctor were prepared on (100) SrTi $O_{3}$ substrates by pulsed laser deposition using visible light laser. Q-switched Nd:YAG(532 nm, 30 ns) pulsed laser was used for deposition. The effects of substrate temperature and oxygen pressure during deposition on films were studied. Critical current density of 2.93*10$^{6}$ A/c $m^{2}$ at 77K and Tc(zero)=91.7K were obtained from the film prepared with Tsub=745.deg. C and $P_{02}$=200 mTorr. XRD analysis showed that the grown film has c-axis normal orientation to the substrate surface and has single phase. Surface morphology of the film has been improved by interfering the plume ejected from YB $a_{2}$C $u_{3}$$O_{7-x}$ target.arget.t.

• Nuclear Engineering and Technology
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• 제48권1호
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• pp.1-15
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• 2016

For a long time, a top priority in the nuclear industry was the safe, reliable, and economic operation of light water reactors. However, the development of accident-tolerant fuel (ATF) became a hot topic in the nuclear research field after the March 2011 events at Fukushima, Japan. In Korea, innovative concepts of ATF have been developing to increase fuel safety and reliability during normal operations, operational transients, and also accident events. The microcell $UO_2$ and high-density composite pellet concepts are being developed as ATF pellets. A microcell $UO_2$ pellet is envisaged to have the enhanced retention capabilities of highly radioactive and corrosive fission products. High-density pellets are expected to be used in combination with the particular ATF cladding concepts. Two concepts-surface-modified Zr-based alloy and SiC composite material-are being developed as ATF cladding, as these innovative concepts can effectively suppress hydrogen explosions and the release of radionuclides into the environment.

• Journal of Ginseng Research
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• 제8권2호
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• pp.178-183
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• 1984

This study was conducted to know the influence of plant age and cultural conditions such as plant population density and light intensity under the shading on the leaf shape of panax ginseng. The result obtained were as follows; 1) Leaf length(L)/maximum width(W) was no difference with different age of over 3-over 3year old plant, but that of 1 or 2-yearold was smaller than those of over 3-year old. The values of L/W showed in the order of 2 or 4,3, 1 or 5 leaflet. 2) Ratios of leaflet area to leaf area were 32.0% in leaflet 3, from 209.% to 27.9% in leaflet 2 or 4, and from 6.5% to 7.1% in leaflet 1 or 5. 3) The coefficients of variability for L/W and ratio of leaflet area to leaf area of leaflet 3 were smallest among leaflets. 4) There were significant differences between largest and smallest leaflet 3, leaf areas and ratio of leaflet 3 area to leaf area in same plant. 5) LW and ratio of leaflet 3 area to leaf area were not affected by plant population density. 6) It showed a tendency that the L/W was increased with increasing the light transmittance rate (LTR). The ratio of leaflet 3 area to leaf area of ginseng grown under 20% LTR was not different comparing to that of plant grown under 5% LTR, but it was significantly increased in plant grown at 100% LTR.

• 한국세라믹학회지
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• 제48권5호
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• pp.404-411
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• 2011

The humidity controlling ceramic materials was developed by applying the phenomena of dew condensation in the capillary. It is said that the humidity range which human feels comfortable is from 40 to 70% in relative humidity. In this study, the ceramic tile using natural soils such as diatomite for interior wall was investigated. In particular, we had introduced novel processing routes for fabricating microcellular ceramics tile using hollow microsphere as a pore former. The microcellular pores in the humidity controlling ceramic materials showed the superior properties such as light-weight, heat insulation. The cell density was ${\sim}1.0{\times}10^9$ cells/$cm^3$ and density of sample was 0.65 g/$cm^3$ in the case of 1.71 wt% hollow microsphere content. Also, it is observed that the BET surface area and the pore volume of the sintered diatomite tile have the values of 40.92 $m^2$/g and 0.173 $cm^3$/g.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 추계학술대회 논문집
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• pp.170-173
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• 2000

In this study, we have investigated the light-emitting property of the EL device with the thickness ratio of the HTL/ETL, which was 500$\AA$:500$\AA$, 400$\AA$:600$\AA$, 600$\AA$:400$\AA$. The ALq$_3$ was used for the ETL. We have studied the relation of voltage, contrase, efficiency for current density. Emission was observed above 10mA/$\textrm{cm}^2$ and luminance was measured to be 1030cd/$m^2$ at a current density of 100mA/$\textrm{cm}^2$ in 500$\AA$/500$\AA$ sample. A luminance of over 2500cd/$m^2$ was also observed after the final fabrication process in 500$\AA$/500$\AA$ sample

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.379-379
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• 2010

Recent technical advances in OLEDs (organic light emitting devices) requires more and more the improvement in low operation voltage, long lifetime, and high luminance efficiency. Inverted top emission OLEDs (ITOLED) appeared to overcome these problems. This evolved to operate better luminance efficiency from conventional OLEDs. First, it has large open area so to be brighter than conventional OLEDs. Also easy integration is possible with Si-based driving circuits for active matrix OLED. But, a proper buffer layer for carrier injection is needed in order to get a good performance. The buffer layer protects underlying organic materials against destructive particles during the electrode deposition and improves their charge transport efficiency by reducing the charge injection barrier. Hexaazatriphenylene-hexacarbonitrile (HAT-CN), a discoid organic molecule, has been used successfully in tandem OLEDs due to its high workfunction more than 6.1 eV. And it has the lowest unoccupied molecular orbital (LUMO) level near to Fermi level. So it plays like a strong electron acceptor. In this experiment, we measured energy level alignment and hole current density on inverted OLED structures for hole injection. The normal film structure of Al/NPB/ITO showed bad characteristics while the HAT-CN insertion between Al and NPB greatly improved hole current density. The behavior can be explained by charge generation at the HAT-CN/NPB interface and gap state formation at Al/HAT-CN interface, respectively. This result indicates that a proper organic buffer layer can be successfully utilized to enhance hole injection efficiency even with low work function Al anode.

• 한국융합학회논문지
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• 제12권7호
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• pp.125-131
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• 2021

치과에서 사용횟수가 증가하고 있는 광중합형 레진 치료에는 강한 에너지를 가진 청색광이 필요하나, 그 빛은 산란 또한 커서 눈과 관련된 여러 부작용이 나타난다. 산란되는 빛에 노출되는 위험을 줄이고자 색깔 렌즈를 활용해보고자 하였다. 광중합기용 팁들과 청색광 빛의 차단에 효과가 있을 것으로 기대하는 시판용 노란색 계열의 청광 차단 렌즈와 노란색 염료로 착색한 노란색 렌즈를 UV-Vis 스펙트로미터 기기에 놓고 각각 청색광의 투과와 차단을 실험하였다. 결과로 광중합기용 팁들의 청광차단율 평균은 99.49%, 시판용 렌즈들 중 색 농도가 가장 높은 C 렌즈는 99.54%의 높은 청광차단율을 보였다. 노란색으로 착색한 렌즈의 경우에는 착색 농도가 가장 짙은 노란색 착색 C 렌즈가 87.57%의 청광차단율을 보였다. 레진 치료 시 광중합기용 팁과 함께 노란계열의 시판용 렌즈나 착색 렌즈를 착용한다면 청색광에 의한 눈과 관련된 부작용들을 줄일 수 있을 것으로 판단된다.

• 원예과학기술지
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• 제32권1호
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• pp.77-83
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• 2014

동양배의 교배육종 효율을 증진시키기 위하여 13품종의 교배친을 이용한 15 조합으로부터 얻어진 교배실생 4,035주를 공시하여 과실의 품질과 밀접한 상관이 있는 육질관련 주요 형질에 대한 유전력, 양친평균과 실생평균과의 상관과 후대실생의 분포특성을 분석하였다. 배 과실 육질관련 형질의 유전력은 조합에 따라 차이는 있으나 경도, 육질경도, 육질밀도, 석세포 모두 대부분의 조합이 0.6 내외로 비교적 높았다. 그러나, 경도에 있어서는 조합별로 유전력의 차이가 다른 형질에 비해 큰 편이었고 '신고' ${\times}$ '장수' 조합에서는 유전력이 0.11로서 특이하게 낮았다. 배 육질관련 형질의 양친평균과 교배실생 평균 사이에 경도는 정의 상관이 있었으나 육질경도, 육질밀도, 석세포 함량에서는 상관이 인정되지 않았으며 회귀계수는 경도 0.778, 육질경도 0.343, 석세포는 0.313으로 산출되어 경도가 가장 높은 값을 나타낸 반면 육질밀도에서는 -0.273으로 부의 회귀값을 나타냈다. 배 과실 육질 관련 형질인 양친의 경도, 육질경도, 육질밀도, 석세포 함량에 대한 조합별 교배실생의 분포양상이 달랐으며 특히 경도는 양친이 모두 낮은 경우 낮은 쪽 낮음 ${\times}$ 높음의 경우 중간에, 높음 ${\times}$ 높음의 경우 높은 실생이 많이 분포되는 양상이었으며 석세포 함량이 적음 ${\times}$ 적음 조합에서는 실생의 분포가 적은 쪽으로, 적음-중간 ${\times}$ 중간-많음 조합에서는 중간에 많은 실생이 분포되는 양상을 보였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.287.1-287.1
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• 2016

Three-dimensional (3-D) semiconductor nanoarchitectures, including nano- and micro- rods, pyramids, and disks, are emerging as one of the most promising elements for future optoelectronic devices. Since these 3-D semiconductor nanoarchitectures have many interesting unconventional properties, including the use of large light-emitting surface area and semipolar/nonpolar nano- or micro-facets, numerous studies reported on novel device applications of these 3-D nanoarchitectures. In particular, 3-D nanoarchitecture devices can have noticeably different current spreading characteristics compared with conventional thin film devices, due to their elaborate 3-D geometry. Utilizing this feature in a highly controlled manner, color-tunable light-emitting diodes (LEDs) were demonstrated by controlling the spatial distribution of current density over the multifaceted GaN LEDs. Meanwhile, for the fabrication of high brightness, single color emitting LEDs or laser diodes, uniform and high density of electrical current must be injected into the entire active layers of the nanoarchitecture devices. Here, we report on a new device structure to inject uniform and high density of electrical current through the 3-D semiconductor nanoarchitecture LEDs using metal core inside microtube LEDs. In this work, we report the fabrications and characteristics of metal-cored coaxial $GaN/In_xGa_{1-x}N$ microtube LEDs. For the fabrication of metal-cored microtube LEDs, $GaN/In_xGa_{1-x}N/ZnO$ coaxial microtube LED arrays grown on an n-GaN/c-Al2O3 substrate were lifted-off from the substrate by wet chemical etching of sacrificial ZnO microtubes and $SiO_2$ layer. The chemically lifted-off layer of LEDs were then stamped upside down on another supporting substrates. Subsequently, Ti/Au and indium tin oxide were deposited on the inner shells of microtubes, forming n-type electrodes of the metal-cored LEDs. The device characteristics were investigated measuring electroluminescence and current-voltage characteristic curves and analyzed by computational modeling of current spreading characteristics.