• Journal of Information Display
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• 제4권2호
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• pp.13-18
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• 2003

We synthesized bis (2-methyl-8-quinolinolato)(triphenylsiloxy) aluminum (III) (SAlq), a blue-emitting material having a high luminous efficiency, through a homogeneous-phase reaction. The photoluminescence (PL) and electroluminescence (EL) spectra of SAlq show two peaks at 454 nm and 477 nm. Efficient white light-emitting devices are fabricated by doping SAlq with a red fluorescent dye of 4-dicyanomethylene-2-methyl-6-{2-(2,3,6,7-tetrahydro-1H,5H-benzo[i,j]quinolizin-8yl) vinyl}-4H-pyran (DCM2). The incomplete energy transfer from blue-emitting SAlq to red-emitting DCM2 results in light-emission of both blue and orange colors. Devices with the structure of ITO/TPD (50 nm)/SAlq:DCM2 (30 nm, 0.5 %)/$Alq_3$ (20 nm)/LiF (0.5 nmj/Al show EL peaks at 456 nm and 482 nm originating from SAlq and at 570 nm from DCM2, resulting in the Commission Internationale d'Eclairage (CIE) chromaticity coordinates of (0.32, 0.37). The device exhibits an external quantum efficiency of about 2.3 % and a luminous efficiency of about 2.41m/W at 100 $cd/m^2$. A maximum luminance of about 23,800 $cd/m^2$ is obtained at the bias voltage of 15 V.

• 마이크로전자및패키징학회지
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• 제15권4호
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• pp.59-64
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• 2008

본 연구에서는 백색 고분자유기 발광다이오드를 제작하여 전기 광학적 특성을 평가하였다. ITO(indium tin oxide)를 양극으로 사용하고 정공수송층으로 PEDOT:PSS [poly(3,4-ethylenedioxythiophene):poly(styrene sulfolnate)]를 발광물질로는 PFO [poly(9,9-dioctylfluorene)]와 MEH-PPV [poly(2-methoxy-5(2-ethylhexoxy)-1,4-phenyl-enevinyle)]를 각각 host와 dopant로 사용하였다. 전자주입층으로 LiF(lithium flouride)와 음극으로 Al(aluminum)을 증착하여 최종적으로 ITO/PEDOT:PSS/PFO:MEH-PPV/LiF/Al 구조를 갖는 백색 고분자 유기발광다이오드를 제작하고 PFO와 MEH-PPV의 농도에 따른 전기 광학적 특성 변화를 조사하였다. 제작된 소자는 9V에서(x=0.36, y=0.35)의 CIE 색좌표를 갖는 백색 발광이 관찰되었으며, 최대 전류밀도와 휘도는 약 13V의 인가전압에서 $740mA/cm^2,\;900cd/m^2$의 값을 나타내었으며, $200cd/m^2$ 휘도에서 0.37 cd/A의 최대 전류효율이 관찰되었다.

• 한국전기전자재료학회논문지
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• 제33권6호
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• pp.475-482
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• 2020

For electronic paper displays using electrophoresis, the response time and reflectivity of the image panel fabricated by filtering are analyzed. For the filtering process, a square wave and ramp wave are applied to white charged particles with a unique q/m value. We divide the sample panels into #1 to #4 according to the applied waveform in the filtering process. Step waves comprising two steps are used to drive the panel; therefore, we divide the driving conditions into D1~D4. The applied voltage at the first stage of the half cycle of the driving waveform moves the charged particles attached via the image force from the electrode, and the applied voltage at the second stage moves the floating charged particles by detaching. As mentioned, four types of driving conditions (D1 to D4) classified according to the half cycle of the driving waveform are applied to the samples #1 to #4), which are classified according to four types of filtering process. When driving condition D1 is applied to the four types of sample panels, the rise time of #1 is 1.59s, #2 is 1.706s, #3 is 1.853s, and #4 is 1.235s, resulting in #4 being relatively faster compared with other sample panels, and showing the same trend in other driving conditions. As a result, we confirm that applying the driving condition D1 causes abrupt movement of the white charged particles injected into the cell. When the same driving waveform (D1) is applied to each sample, reflectivities of 32.1% for #1, 31.4% for #2, 27.9% for #3, and 63.4% for #4 are measured. From the experiment, we confirm that the driving condition D1 (1s of 3.5 V, 9s of 3.0 V) and ramp wave #4 in filtering are desirable for good reflectivity and response time. Our research is expected to contribute to the improvement of the filtering process and optimization of the driving waveform.

• 대한화학회지
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• 제45권2호
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• pp.156-161
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• 2001

여러 가지 산화상태의 폴리아닐린을 화학적으로 합성하여 FT-IR, UV-Vis, GPC, TG-DTA로 측성 분석하였다. ITO 기관위에 다양한 산화상태의 LEB-PAN/NMP 용액으로 스핀코팅하고, AI 전극을 진공증착하여 단일층 발광다이오드를 제작하고 I-V 특성과 EL 스팩트럼에서 완전환원형인 LEB 함량이 증가할수록 ${\pi}$-${\pi}$* 전이의 장파장이동과 분자 엑시톤 전이 세기가 감소하고 PL과 EL 세기가 증가하는 것을 확인하였다. ITO/LEB/AI 구조의 LED에서 작동 전압은 5V 이었다. 백색광은 단지 폴리아닐린의 환원형 구조에서만 발광하는 것을 확인하였다.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제37권
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• pp.10.1-10.5
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• 2015

Background: The aim of this study was to investigate the effect of a botulinum toxin type A (BTX-A) injection in the masseter muscle using electromyography (EMG) in an animal model. Methods: Ten male adult (>3 months of age) New Zealand white rabbits were used. Muscle activity was continuously recorded from 8 hours before to 8 hours after BTX-A injection. The rabbits received unilateral BTX-A injections of either 5 units (group 1, n = 5) or 20 units (group 2, n = 5). Results: The masseter muscle activity of the rabbits was significantly reduced immediately after BTX-A injection (P < 0.05 for both groups). When the results from group 1 were compared with those from group 2, only the peak voltage was significantly decreased in group 2 (P = 0.013). Conclusion: Masseter muscle activity measured by EMG was immediately decreased after a BTX-A injection.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.156-156
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• 2011

Nanocrystalline $Ca_2Gd_8Si_6O_{26}$ (CGS) : $Sm^{3+}$ and CGS : $Tb^{3+}/Sm^{3+}$ phosphors were prepared by solvothermal reaction method for light emitting diode (LED) and field emission display (FED) applications. The XRD patterns of these phosphors confirmed their oxyapatite structure in the hexagonal lattice. The visible luminescence properties of these phosphors were investigated by exciting with ultraviolet (UV) or near-UV light and low voltage electron beam. The photoluminescence (PL) properties of $Ca_2Gd_8Si_6O_{26}$ (CGS) : $Sm^{3+}$ and CGS : $Tb^{3+}/Sm^{3+}$ phosphors were investigated as a function of $Sm^{3+}$ concentration. Cathodoluminescence (CL) properties were examined by changing the acceleration voltage. The CGS : $Sm^{3+}$ showed the dominant orange emission due to the $^4G_{5/2}{\rightarrow}^6H_{7/2}$ transition. The CGS : $Tb^{3+}/Sm^{3+}$ phosphor showed the green, white and orange emissions when excited with 275, 378, and 405 nm wavelengths, respectively. The chromaticity coordinates of these phosphors were comparable to or better than those of standard phosphors for LED or FED devices.

• 전기학회논문지P
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• 제59권4호
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• pp.462-466
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• 2010

The purpose of this study is to evaluate the safety of a wire connector fabricated for the effective installation of a lighting fixture including its contact resistance, insulation resistance, withstanding voltage characteristics, etc., and to provide the basis for the analysis and judgment of PL(Product Liability) dispute by presenting a damage pattern due to a general flame and overcurrent. This study applied the Korean Standard (KS) for the incombustibility test of the connector using a general flame and performed an overcurrent characteristics test of the connector using PCITS (Primary Current Injection Test System). The contact resistance of the housing connector was measured using a high resistance meter and the insulation resistance was measured using a multimeter. In addition, a supply voltage of AC 1,500V for testing the withstanding voltage characteristics was applied to both ends of the connector. Measurement was performed on 5 specimens and the measured values were used as a basis for judgment. Since the connector is fabricated in the form of a housing, it can be connected and separated easily and has a structure that allows no foreign material to enter. In addition, since it has a structure that allows wires to be connected only when their polarity is identical, any misconnection that may occur during installation can be prevented. When the incombustibility test was performed by applying a general flame to the connector, it showed outstanding incombustibility characteristics and the blade and blade holder connected to the housing remained firmly secured even after the insulation sheath (PVC) was completely destroyed by fire. In addition, the mechanism of the damaged connecting wire showed a comparatively uniform carbonization pattern and it was found that some residual melted insulation material was attached to both ends. In the accelerated life test (ALT) to which approximately 500% of the rated current was applied, the connector damage proceeded in the order of white smoke generation, wire separation, spark occurrence and carbonization. That is, it could be seen that the connector damaged by overcurrent lost its own metallic color with traces of discoloration and carbonization. The contact resistance of the connector at a normal state was 2.164mV/A on average. The contact resistance measured after the high temperature test was 3.258mV/A. In addition, the insulation resistance after the temperature test was completed was greater than $10G\Omega$ and the withstanding voltage test result showed that no insulation breakdown occurred to all specimens showing stable withstanding voltage and insulation resistance characteristics.

• 전기전자학회논문지
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• 제10권2호통권19호
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• pp.156-160
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• 2006

Al2O3 층의 유무에 따른 Ge 나노입자가 형성된 MOS 구조의 캐패시터의 전압에 대한 캐패시턴스 (C-V)의 특성을 측정하였다. Al20O층이 형성된 MOS 캐패시터의 C-V 곡선은 전압의 변화에 대해 나타나는 반시계 방항의 히스테리시스 특성은 Si 기판과 Ge 나노입자 사이를 전자가 터널링하여 Ge 나노입자에 저장되었기 때문이다. Al2O3 층이 없는 MOS 캐패시터의 경우, 시계 방향의 히스테리시스 특성과 좌측으로 이동한 플랫-밴드 전압 값을 볼 수 있다. 이것은 SiO2 층에 존재하는 산소 결원 (oxygen vacancy) 으로 인한 전하 트랩이 이러한 특성을 나타냈다 할 수 있다. 또, 백색광이 C-V 특성에 미치는 영향에 대하여 논하였다.

• 한국산학기술학회논문지
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• 제13권1호
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• pp.329-332
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• 2012

LED는 저 전력, 긴 수명, 고 휘도, 빠른 응답, 친환경적인 특성의 여러 장점을 갖고 있기 때문에 청색과 녹색 LED는 교통신호, 옥외 디스플레이, 백색 LED는 LCD 후면광 등의 응용 제품에 사용되고 있다. 여기서 LED의 성능을 향상하기 위하여 출력전력과 소자의 신뢰성을 높이고, 동작전압을 낮추어야 LED 칩의 고효율화가 이루어져야 하는데, 이는 에피택셜층, 표면요철, 패턴이 있는 사파이어 기판, 칩 설계의 최적화, 특수 공정의 개선 등의 기술이 우수해야 한다. 본 연구에서는 측면 에칭 기술과 절연층 삽입기술을 이용하여 사파이어 에피 웨이퍼 위에 GaN-기반 백색 LED 칩을 제작하여 그 성능을 조사하였다. LED 칩의 성능을 개선하기 위한 최적화 설계와 CBL(current blocking layer) 삽입 기술의 개선된 공정을 통하여 LED 칩 성능의 향상을 확인할 수 있었으며, 출력 전력은 광 출력 7cd, 순방향 인가전압 3.2V의 값을 얻었다. 현재의 LCD 후면광원으로 사용되고 있는 LED 칩의 출력에 비하여 성능이 개선되었으며, 의료기기 및 LCD LED TV의 후면광원으로 사용할 수 있을 것으로 기대된다.

• 한국표면공학회지
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• 제52권3호
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• pp.138-144
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• 2019

In this work, PEO (Plasma Electrolytic Oxidation) film formation behavior of Al6061 alloy was investigated as a function of applied current density of AC at 310 Hz in the range from $120mA/cm^2$ to $300mA/cm^2$ in 0.5 M $Na_2SiO_3$ solution. When applied current density is lower than a critical voltage of about $132mA/cm^2$, voltage reaches a steady-state values less than 120 V without generation of arcs and metallic color of the alloy surface remains. On the other hand, when applied current density exceeds about $132mA/cm^2$, voltage increases continuously with time and arcs are generated at more than 175 V, resulting in the formation of PEO films with grey colors. Two different types of arcs, large size and small number of arcs with orange color, and small size and large number of arcs with white color, were generated at the same time when the PEO film thickness exceeds about $50{\mu}m$, irrespective of applied current density. Formation efficiency of the PEO films was found to increase with increasing applied current density and the growth rate was obtained to be about $5{\mu}m/min$ at $300mA/cm^2$. It was also found that surface roughness of the PEO films with $70{\mu}m$ thickness is not dependent on the applied current density.