• 한국전자파학회논문지
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• 제18권9호
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• pp.1083-1089
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• 2007

본 논문에서는 무선 통신 기기의 주요 부품인 VCO(Voltage Controled Oscillator)의 고조파 특성을 개선시키기 위하여 CMRC(Compact Microstrip Resonant Cell) 구조를 이용한 여파기를 공진기 후단에 적용하였다. CMRC 여파기는 PBG, DGS 등 다른 여파기에 비하여 그 크기가 소형일 뿐 아니라 제작이 용이한 장점을 가지고 있다. 본 논문에서 제안한 CMRC를 이용한 VCO의 2차 고조파 특성은 -42.83 dBc, 위상 잡음 특성은 100 kHz offset에서 -95.83 dBc/Hz이었다. CMRC를 공진기 후단에 연결하는 것이 CMRC를 공진기로 이용하는 것보다 2차 고조파 특성은 약 15.73 dB, 위상 잡음은 약 31.13 dB 개선되었다.

• Bulletin of the Korean Chemical Society
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• 제31권2호
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• pp.429-434
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• 2010

A novel T-type polyester 7 containing 1-(2,5-dioxyphenyl)-2-{5-(1,2,2-tricyanovinyl)-2-thienyl}ethenes as nonlinear optical (NLO) chromophores, which are part of the polymer backbone, was prepared and characterized. Polyester 7 is soluble in common organic solvents such as dimethylsulfoxide and N,N-dimethylformamide. It showed a thermal stability up to $300^{\circ}C$ in thermogravimetric analysis thermogram and the glass-transition temperature ($T_g$) obtained from differential scanning calorimetry thermogram was around $113^{\circ}C$. The second harmonic generation (SHG) coefficient ($d_{33}$) of poled polymer films at 1,560 nm fundamental wavelength was around 1.85 pm/V. The dipole alignment exhibits a greater thermal stability even at $10^{\circ}C$ higher than $T_g$, and there is no SHG decay below $125^{\circ}C$ due to the partial mainchain character of the polymer structure, which is acceptable for nonlinear optical device applications.

• Macromolecular Research
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• 제15권6호
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• pp.506-512
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• 2007

2,3-Di-(2'-hydroxyethoxy)-4'-nitrostilbene (3) was prepared and condensed with terephthaloyl chloride, adipoyl chloride, and sebacoyl chloride to yield novel Y-type polyesters (4-6) containing the NLO-chromophores 2,3-dioxynitrostilbenyl groups, which constituted parts of the polymer backbones. Polymers 4-6 were soluble in common organic solvents such as acetone and N,N-dimethylformamide. Polymers 4-5 showed thermal stability up to $300^{\circ}C$ in thermogravimetric analysis with glass transition temperatures $(T_g)$, obtained from differential scanning calorimetry, in the range $81-95^{\circ}C$. The second harmonic generation (SHG) coefficients $(d_{33})$ of the poled polymer films at the 1064 nm fundamental wavelength were around $3.68{\times}10^{-9}$ esu. The dipole alignment exhibited high thermal stability up to $T_g$, and there was no SHG decay below $T_g$ due to the partial main-chain character of the polymer structure.

• Bulletin of the Korean Chemical Society
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• 제32권9호
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• pp.3361-3366
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• 2011

New Y-type polyester (3) containing nitrophenylazoresorcinoxy groups as NLO chromophores, which are components of the polymer backbone, was prepared and characterized. Polyester 3 is soluble in common organic solvents such as N,N-dimethylformamide and acetone. It shows a thermal stability up to $240^{\circ}C$ in thermogravimetric analysis with glass-transition temperature ($T_g$) obtained from differential scanning calorimetry near $116^{\circ}C$. The second harmonic generation (SHG) coefficient ($d_{33}$) of poled polymer film at the 1064 nm fundamental wavelength is around $4.63{\times}10^{-9}$ esu. The dipole alignment exhibits a thermal stability even at $4^{\circ}C$ higher than $T_g$, and there is no SHG decay below $120^{\circ}C$ due to the partial main-chain character of polymer structure, which is acceptable for NLO device applications.

• Bulletin of the Korean Chemical Society
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• 제29권5호
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• pp.933-938
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• 2008

2,4-Di-(2'-hydroxyethoxy)benzylidenemalononitrile (3) was prepared and polymerized with terephthaloyl chloride and adipoyl chloride to yield novel Y-type polyesters 4 and 5 containing dioxybenzylidenemalononitrile groups as NLO-chromophores, which constituted parts of the polymer backbone. The resulting polymers 4 and 5 are soluble in common organic solvents such as acetone and N,N-dimethylformamide. Polymers 4 and 5 showed thermal stability up to 300 ${^{\circ}C}$ in thermogravimetric analysis with glass-transition temperatures obtained from differential scanning calorimetry in the range 83-94 ${^{\circ}C}$. The second harmonic generation (SHG) coefficients ($d_{33}$) of poled polymer films at the 1064 nm fundamental wavelength were around $6.48\;{\times}\;10^{-9}$ esu. The dipole alignment exhibited high thermal stability even at 10 ${^{\circ}C}$ higher than $T_g$ and no significant SHG decay was observed below 105 ${^{\circ}C}$ partially due to the main-chain character of polymer structure, which is acceptable for NLO device applications.

• Bulletin of the Korean Chemical Society
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• 제30권5호
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• pp.1080-1084
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• 2009

Methyl 2,4-di-(2'-hydroxyethoxy)benzylidenecyanoacetate (3) was prepared and polymerized with terephthaloyl chloride to yield a novel Y-type polyester 4 containing 2,4-dioxybenzylidenecyanoacetate groups as NLOchromophores, which constituted parts of the polymer backbone. The resulting polymer 4 is soluble in common organic solvents such as acetone and N,N-dimethylformamide. Polymer 4 showed thermal stability up to 280 ${^{\circ}C}$ in thermogravimetric analysis with glass-transition temperature obtained from differential scanning calorimetry near 108 ${^{\circ}C}$. The second harmonic generation (SHG) coefficient ($d_{33}$) of poled polymer films at the 1064 nm fundamental wavelength was around $3.54\;{\time}\;10^{-9}$ esu. The dipole alignment exhibited a thermal stability up to near $T_g$ and no significant SHG decay was observed below 100 ${^{\circ}C}$ due to the partial main-chain character of polymer structure, which is acceptable for NLO device applications.

• Macromolecular Research
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• 제15권3호
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• pp.234-237
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• 2007

3,4-Bis-(3,4-dicarboxyphenylcarboxyethoxy)-4'-nitrostilbene dianhydride was prepared and reacted with 4,4'-(hexafluoroisopropylidene)dianiline to yield a novel Y-type polyimide containing the 3,4-dioxynitrostilbenyl group as an NLO-chromophore, which constituted part of the polymer backbone. The resulting polyimide was soluble in polar solvents such as acetone and N,N-dimethylformamide. The polymer exhibited good thermal stability up to $370^{\circ}C$ in the thermogravimetric analysis. The glass-transition temperature ($T_g$) obtained from the differential scanning calorimetry thermogram was near to $153^{\circ}C$. The second harmonic generation (SHG) coefficient ($d_{33}$) of the poled polymer film at the fundamental wavelength of $1064\;cm^{-1}$ was around $2.15\;{\times}\;10^{-8}\;esu$ (9.01 pm/V). The dipole alignment exhibited exceptionally high thermal stability even at a temperature $30^{\circ}C$ above the $T_g$, and there was no SHG decay below $180^{\circ}C$ because of the partial main chain character of the polymer structure.

• Bulletin of the Korean Chemical Society
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• 제30권3호
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• pp.661-666
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• 2009

1-{2,4-Di-(2-hydroxyethoxy)phenyl}-2-(2-thienyl)ethene (5) was prepared and condensed with terephthaloyl chloride to yield polyester (6). Polymer 6 was reacted with tetracyanoethylene to give novel Y-type polyester (7) containing 1-(2,4-dioxyethoxy)phenyl-2-{5-(2,2,3-tricyanovinyl)-2-thienyl)}ethenyl groups as NLO-chromophores, which are parts the polymer backbones. Polymer 7 is soluble in common organic solvents such as acetone and N,N-dimethylformamide. It showed thermal stability up to 300 ${^{\circ}C}$ in thermogravimetric analysis with glasstransition temperature obtained from differential scanning calorimetry near 134 ${^{\circ}C}$. The second harmonic generation (SHG) coefficient ($d_33$) of poled polymer film at the 1560 nm fundamental wavelength was around 6.74 x $10^{-9}$ esu. The dipole alignment exhibited high thermal stability up to the glass-transition temperature ($Tg$), and there was no SHG decay below 135 ${^{\circ}C}$ because of the partial main-chain character of polymer structure, which is acceptable for NLO device applications.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 학술대회 논문집 전문대학교육위원
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• pp.125-127
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• 2007

Presented increase and so on of switch stress and switching dissipation and EMI that is happened in general PWM converter and in this study to solve problem the resonance energy return to life rate and new active snubber PWM converter because do maximization. Active snubber PWM converter that try adds auxiliary switch and resonance capacitor, diode to existing converter under all switching conditions turn on/off Minimised switching dissipation that occur. Reduced harmonic components absorbing station recovery electric current that happen to snubber diode inserting diode and resistance. And decreased peak current that is happened in auxiliary switch arranging resonance capacitor and inductor properly, Certified effect that efficiency rises about 2.5[%] more than existent PWM converter in rated load through an experiment.

• 한국자기공명학회논문지
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• 제13권1호
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• pp.35-55
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• 2009

The two correlation times previously obtained in our coupled $^{13}C$ relaxation measurement for the methyl group in 2,6-dichlorotoluene may be used as a criterion for evaluating the reorientation dynamics of an internal rotor. We numerically tested an extended diffusion model and the Smoluchowski diffusion equation to see how the rotational inertial effect and jump character contribute to the internal correlation time ratio of the internal rotor. We also analytically solved the general jump model with three different rate constants in a sixfold symmetric potential barrier. By assuming that the internal rotation of the methyl group in 2,6-dichlorotoluene can be described in terms of jumps among sixfold harmonic potential wells, we can conclude that the jump model satisfactorily reproduce the experimental data and the rate for sixfold jump is at least 1.53 times as great as that of a threefold jump.