• Korean Chemical Engineering Research
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• 제51권5호
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• pp.634-639
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• 2013

유기발광다이오드(Organic Light-Emitting Diodes, OLEDs)의 효율을 향상시키기 위하여 다양한 아세트산금속(Macetate, M: Li, Na, K, Cs)을 cathode underlayer 소재로 사용하고 이들이 소자의 전자주입 및 발광 특성에 미치는 영향에 대하여 연구하였다. 1 nm 두께의 M-acetate 층을 cathode underlayer로 사용한 경우 Cs-acetate를 사용한 소자를 제외한 모든 소자에서 기존의 LiF 전자주입층을 사용한 소자보다 효율적인 전자주입 및 향상된 발광특성을 보였으며, M-acetate에 포함된 금속의 일함수가 작을수록 높은 전류밀도와 우수한 발광특성을 보였다. 또한, cathode underlayer의 두께가 소자의 특성에 미치는 영향을 분석한 결과, 사용된 M-acetate의 분자크기에 따라 각기 다른 두께(Li-acetate 0.7 nm, Cs-acetate 2.0 nm)에서 최적의 발광특성을 보였으며 기존의 LiF 층을 사용한 소자에 비하여 동일 인가전압에서 전류효율이 약 60% 향상된 결과를 얻을 수 있었다.

• 전자공학회논문지A
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• 제32A권2호
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• pp.73-80
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• 1995

We fabricated the 1.55.mu.m RWG-DFB-LD and measured its electrical and optical characteristics. Interference fringe of optical beams was used for grating formation and epi layers were grown by lower-temperature LPE. The fabricated RWG-DFB-LD operated in a single longitudinal mode with more than 30dB SMSR at 1543nm emitting wavelength and its threshold current was 40mA. The wavelength shift with operating temperature and characteristic temperature T$_{o}$ were 0.9${\AA}/^{\circ}C$ and 59K, respectively. Linewidth enhancement factor .alpha. and linewidty.optical power product were estimated as 6.15 and 60MHz$\cdot$mW respectively.

• 의료ㆍ복지 건축 : 한국의료복지건축학회 논문집
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• 제5권9호
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• pp.61-68
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• 1999

The purpose of this study was to get the design guidelines of the operating department in army hospital. New A.F.M.H. is now under construction but army hospital's characteristics are not reflected. This research is accomplished through an understanding of the characteristics of operating department in army hospitals by analyzing the plans and behavior survey of some A.F.M.H. This study attempts to examine the current status of domestic army medical center and to establish the design guideline of the operating department of the army hospitals.

• 한국태양에너지학회 논문집
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• 제22권2호
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• pp.19-26
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• 2002

This study aims at numerically analyzing on heat transfer the characteristics and pressure drop of plate heat exchanger(PHE) using the Phoenics 3.1 VR Editor for the standard k-$\varepsilon$ model. Computations have been carried out for a range of chevron angle from $30^{\circ}$ to $60^{\circ}$, inlet velocity from 0.03m/s to 0.63m/s and the height of corrugation from 0.0045m to 0.0060m. The results show that both of heat transfer performance and pressure drop increase as chevron angle increases. This is because higher troughs produce higher turbulence and a higher heat transfer coefficient in the liquids flowing between the plates. As inlet velocity from 0.03m/s to 0.63m/s increases, heat transfer performance and pressure drop increase parabolically. As the height of corrugation increases, both of heat transfer performance and pressure drop decrease with the decrease of velocity. And the pressure drop decreases and the friction factor increases as the height of corrugation increases.

• 대한화학회지
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• 제61권2호
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• pp.57-64
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• 2017

Monoclinic $VO_2(M)$ nanoparticles codoped with 1.5 at. % W and 2.9 at. % Mg were synthesized by the hydrothermal treatment and post-thermal transformation method of $V_2O_5-H_2C_2O_4-H_2O$ with $Na_2WO_4$ and $Mg(NO_3)_2$. The composite thin film of the W/Mg-codoped $VO_2(M)$ with a commercial acrylic block copolymer was also prepared on PET substrate by wet-coating method. The reversible phase transition characteristics of the codoped $VO_2(M)$ nanoparticles and the composite film were investigated from DSC, resistivity and Vis-NIR transmittance measurements compared with the undoped and Wdoped $VO_2(M)$ samples. Mg-codoping into W-doped $VO_2(M)$ nanoparticles synergistically enhanced the transition characteristics by increasing the sharpness of transition while the transition temperature ($T_c$) lowered by W-doping was maintained. The codoped composite film showed the prominently enhanced NIR switching efficiency compared to only W-doped $VO_2(M)$ film with a lowered $T_c$.

• 전기전자학회논문지
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• 제26권1호
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• pp.124-128
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• 2022

기존 LDO 레귤레이터 외부 커패시터는 오버슈트 및 언더슈트와 같은 과도 응답 특성을 줄일 수 있다. 그러나 본 연구에서 제안한 Capless LDO 레귤레이터는 과도 응답을 개선하고 우수한 전류 구동 능력을 제공하기 위해 패스 트랜지스터에 바디 기술을 적용하였다. 제안하는 LDO 레귤레이터의 동작 조건은 3.3V ~ 4.5V 범위의 입력 전압, 최대 부하 전류 200mA, 출력 전압 3V로 설정하였다. 측정 결과, 부하 전류가 100mA일 때 전압은 언더슈트 상태에서 95 mV, 오버슈트 상태에서 105 mV임을 확인 할 수 있었다.

• 한국광학회:학술대회논문집
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• 한국광학회 1999년도 제16회 광학 및 양자전자 학술발표회Proceedings of 16th Optics and Quantum Electronics Conference, 1999
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• pp.222-223
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• 1999

The structural dependence of harmonic and intermodulation distortion characteristics in 1.55${\mu}{\textrm}{m}$ DFB-LCD were investigated. The linearity of 1.55${\mu}{\textrm}{m}$ DFB-LD was greatly improved by employing a partially corrugated structure.

• 전자공학회논문지A
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• 제32A권12호
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• pp.136-141
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• 1995

GaAs power MESFETs with 1 .mu.m gate length and an undoped GaAs surface layer on the doped GaAs channel are fabricated using IR(image reversal) and air-birdge processes. And then We have measured and calculated DC and RF characteristics. We have obtained saturation current 107-500 mA (197-255 mA/mm), maximum linear RF output power 111-518.8 mW (204-270 mW/mm), current gain cut-off frequency 7-10 GHz, maximum unilateral transducer power gain 5.7-12.7, and power added efficiencies 37.9-41.2 % from the devices with gate width 0.45-2.2 mm, at 6 GHz.

• 한국연소학회지
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• 제7권4호
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• pp.10-20
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• 2002

This paper discusses effect of solid mass inventory on the hydrodynamic characteristics of circulating fluidized bed(CFB). Operating parameters of solid mass inventory and air flow rates were varied to understand their effects on fludization pattern. Experimental measurements were made in a CFB of which height and diameter are 3m and 0.05m respectively. Black SiC particles ranging from $100{\mu}m\;to\;500{\mu}m$ were employed as the bed material. Superficial gas velocity of riser and J-valve fluidizing velocity were in the ranges of $1.39{\sim}3.24m/s\;and\;0.139{\sim}0.232m/s$, respectively. The axial solid fraction and solid circulation rate of CFB were calculated based on the experimental data and compared with modellings through IEA-CFBC Model and commercial CFD code.

• Tribology and Lubricants
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• 제12권1호
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• pp.22-28
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• 1996

This study was undertaken to investigate the dry wear characteristics and mechanism of KP-4M steel for plastic molding against SKD 61 hardened by heat treatment. The wear test was carried out under different conditions such as sliding speed, contact pressure, sliding distance, with frictional tester of pin on disc type. The wear loss on variation of sliding speed was little in lower speed range below 0.5 m/sec and in higher speed range above 1.5 m/sec,'but wear loss was high in intermediate speed range. The critical sliding speed, which showed the maximum value of specific wear rate, became lower with increased contact pressure. Increasing the contact pressure, the critical sliding distance Lcr which the wear mechanism changes from severe wear to mild wear was increased due to the decrease of oxidation reaction velocity. Through this study we suggested a model of generation and elimination process of wear debris of KP-4M steel for plastic molding.