• Journal of Information Display
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• 제8권2호
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• pp.20-24
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• 2007

Efficient white organic light-emitting diodes are fabricated with the blue and red electroluminescent (EL) units electrically connected in a stacked tandem structure by using a transparent doped organic p/n junction. The blue and red EL units consist of the light-emitting layer of 1,4-bis(2,2-diphenyl vinyl)benzene (DPVBi) and 4-dicyanomethylene-2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[i,j] quinolizin-8-yl)vinyl]-4H-pyran) (DCM2) doped tris(8-hydroxyquinoline) aluminum $(Alq_3)$, respectively. The organic p-n junction consists of ${\alpha}-NPD$ doped with $FeCl_3$ (15 % by weight ratio) and $Alq_3$ doped with Li (10 %). The EL spectra exhibit two peaks at 448 and 606 nm, resulting in white light-emission with the Commission Internationale d'Eclairage (CIE) chromaticity coordinates of (0.36, 0.24). The tandem device shows the quantum efficiency of about 2.2 % at a luminance of 100 $cd/m^2$, higher than individual blue and red EL devices.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2003년도 추계학술발표강연 및 논문개요집
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• pp.21-21
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• 2003

To increase the light-emission efficiency of LED, we increased the internal and external quantum efficiency by suppressing the defect formation in the quantum well and by increasing the light extraction efficiency in LED, respectively. First, the internal quantum efficiency was improved by investigating the effect of a low temperature (LT) grown p-GaN layer on the In$\sub$0.25/GaN/GaN MQW in green LED. The properties of p-GaN was optimized at a low growth temperature of 900oC. A green LED using the optimized LT p-type GaN clearly showed the elimination of blue-shift which is originated by the MQW damage due to the high temperature growth process. This result was attributed to the suppression of indium inter-diffusion in MQW layer as evidenced by XRD and HR-TEM analysis. Secondly, we improved the light-extraction efficiency of LED. In spite of high internal quantum efficiency of GaN-based LED, the external quantum efficiency is still low due to the total internal reflection of the light at the semiconductor-air interface. To improve the probability of escaping the photons outside from the LED structure, we fabricated nano-sized cavities on a p-GaN surface utilizing Pt self-assembled metal clusters as an etch mask. Electroluminescence measurement showed that the relative optical output power was increased up to 80% compared to that of LED without nano-sized cavities. I-V measurement also showed that the electrical performance was improved. The enhanced LED performance was attributed to the enhancement of light escaping probability and the decrease of resistance due to the increase in contact area.

• 대한화학회지
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• 제16권5호
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• pp.298-303
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• 1972

페닐글리옥산과 구아닌 사이의 부가생성물을 얻었다. 그 구조는 글리옥살-구아닌 부가생성물과 유사하다. 페닐글리옥살의 알데히드기는 구아닌의 1-N의 위치에, 케토기는 구아닌의 $N^2$위치에 부가된다. 부가생성물의 구조는 질량분광법, 핵자기 공명분광법 및 과요오드산염 산화법에 의하여 결정하였다. 부가생성물을 과요오드산염으로 산화하여 $N^2$-벤조일-구아닌을 얻었다. 이 결과에 근거하여 구조식 I과 같이 구조를 밝혔다. 부가생성물은 알카리용액에서 안정하다. pH 12, $60^{\circ}C$에서 2시간을 가열하여도 페닐글리옥살과 구아닌으로 해리되지 않는다. 부가생성물은 산성 에탄올에 녹지만 중성 또는 알카리성 물에는 녹지 않는다. 이 물질은 구아닌의 $A_{280}/A_{260}$의 값에 비하여 낮은 값을 가진다.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2017년도 춘계학술대회
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• pp.527-528
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• 2017

터널 전계 효과 트랜지스터(tunnel field effect transistor; TFET)의 게이트를 소스 영역으로 오버랩 시킨 구조에서 가우시안으로 P형 도핑한 경우의 전류특성을 조사했다. 제안된 구조는 채널을 P형 도핑하여 험프를 제거하고 가우시안 도핑하여 드레인 벌크영역에서 나타나는 역방향성(ambipolar) 전류를 최소화시켰다. 소스-채널-드레인을 P-P-N으로 구성된 TFET의 구동전류는 P-I-N TFET와 동일하나 문턱전압 이하 기울기(Subthreshold Swing; SS)에서 5배 높은 효율이 관찰되었으며 차단전류는 가우시안 도핑 결과가 일정한 도핑에 비해 약 10배 감소하였고, 역방향성 전류는 100배 감소하였다.

• 전자공학회논문지A
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• 제28A권12호
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• pp.53-58
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• 1991

Hot-carrier induced degradation has been studied for the BF$_2$ ion-implanted surface-channel LDD(P$^{+}$ polysilicon gate) PMOSFET in comparison to the buried-channel structure(N$^{+}$ polysilicon gate) PMOSFET. The conditions for maximum degradation better correlated to I$_{g}$ than I$_{sub}$ for both PMOSFET's. Due to the use of LDD structure on SC-PMOSFET, the substrate current for SC-PMOSFET was shown to be smaller than that of BC-PMOSFET. The gate current was smaller as well, due to the gate material work-function difference between p$^{+}$ and n$^{+}$ polysilicon gates. From the results, it was shown that the surface-channel LDD PMOSFET is more resistant to short channel effect than the buried-channel PMOSFET.

• 전자공학회논문지A
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• 제29A권10호
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• pp.29-34
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• 1992

JFET's with gate lengths ranging from 1$\mu$m to 8.3$\mu$m are successfully fabricated on InP substrate where the long haul (1.3$\mu$m~8.3$\mu$m) OEIC's(OptoElectronic Integrated Circuits) have been made. The pn junction of InP JFET's is made by co-implantation and RTA process. JFET's have etched-mesa-gate structure and the maximum gm larger than 90mS/mm was measured and this is the highest record in JFET's of such structure without S/D n$^{+}$ ion implantation. To maintain maximum g$_m$ should be well controlled the overetch of n-layer which inevitably occurs during etching off the unused p-layer. The I-V characteristic is checked during p-layer etch, for this purpose. A dc voltage gain of 11 is obtained from a preamplifier circuit thus fabricated.

• 약학회지
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• 제24권2호
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• pp.135-141
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• 1980

The crystal and molecular structure of 2-methyl-3-(N-trimethyl ammonium)phenol iodide, $C_{10}H_{16}NOI, was determined by X-ray diffraction method. The compound crystallizes in the orthorhombic space group $P_{na2}_{1}$ with a=13.327(3), b=12.496(3), C=7.227(2)A and Z=4. A total of 489 independent observed reflections were collected by the automated Four-circle diffractometer and was solved by heavy atom method and refined by anisotropic block-diagonal least-squares method to the R value of 0.04. The benzene ring is slightly distorted from regular hexagon. The I atom and 2-methyl-3-(N-trimethyl ammonium)phenol group is held together by van der Waals forces in the crystal. Intermolecular hydrogen bond is of the type O-H....I with the length 3.35.angs.. Apart from the hydrogen bonding system the molecules are held together by van der Waals forces in the crystal.

• Bulletin of the Korean Chemical Society
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• 제32권9호
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• pp.3411-3420
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• 2011

Kinetic and structural studies have been carried out on the effects of meso-tetrakis(4-sulfonatophenyl)-porphyrin ($H_2TPPS_4$) as an anionic and meso-tetrakis(3-N-methyl-pyridyl)porphyrin ($H_2TMPYP$) as a cationic porphyrin with adenosine deaminase (ADA) in 25 mM citrate/phosphate buffer, pH = 4-8, at $37^{\circ}C$ using UVvis spectrophotometry, circular dichroism (CD), fluorescence spectrophotometry as well as molecular dynamics (MD) and molecular docking. Kinetic results showed that the two porphyrins are non-competitive inhibitors. Increasing pH, increases $K_I$ and cationic porphyrin has a higher $K_I$ and lower binding constant ($K_b$) at all pH ranges. Analyzing the secondary structure revealed that both ligands decrease the secondary structure and that the anionic porphyrin is more effective.

• 호남수학학술지
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• 제4권1호
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• pp.75-84
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• 1982

Let M be a complete and orientable hypersurface of an odd-dimensional sphere $S^{2n+1}$ with quasi-integrable $(f,\;g,\;u,\;{\nu},\;{\lambda})$ -structure. The purpose of the present paper is to prove the following two theorems. (I) If the scalar curvature of M is constant and the function $\lambda$ is not locally constant, then M is a great sphere $S^{2n}$(1) or a product of two spheres with the same dimension $S^{n}(1/\sqrt{2}){\times}S^{n}(1/\sqrt{2})$. (II) Suppose that the sectional curvature of the section $\gamma(u,\;{\nu})$ spanned by u and $\nu$ is constant on M and M is compact. If the second fundamental tensor H of M is positive semi-definite and satisfies trace $$^{t}HH{\leq_-}{2n}$$, then M is a great sphere $S^{2n}$ (1) or a product of two spheres $S^{n}{\times}S^{n}$ or $S^{p}{\times}S^{2n-p}$, p being odd.

• Molecules and Cells
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• 제24권3호
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• pp.437-440
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• 2007

$OGL-20P^T$-358 is a novel 66 amino acid residue protein from the hyperthermophile Thermococcus thioreducens sp. nov., strain $OGL-20P^T$, which was collected from the wall of the hydrothermal black smoker in the Rainbow Vent along the mid-Atlantic ridge. This protein, which has no detectable sequence homology with proteins or domains of known function, has a calculated pI of 4.76 and a molecular mass of 8.2 kDa. We report here the backbone $^1H$, $^{15}N$, and $^{13}C$ resonance assignments of $OGL-20P^T$-358. Assignments are 97.5% (316/324) complete. Chemical shift index was used to determine the secondary structure of the protein, which appears to consist of primarily ${\alpha}$-helical regions. This work is the foundation for future studies to determine the three-dimensional solution structure of the protein.