• Journal of the Korean Institute of Telematics and Electronics
• /
• v.18 no.6
• /
• pp.1-8
• /
• 1981

A new desio method of decentraliaed stabilizing controller is proposed for large scale discretetime systems with delays in interconnections. Gain parameters of the local stabilizing controller are determined by utilizing the well-knowon Nyquist array technique in the complex q-plane, where .

• Proceedings of the KIEE Conference
• /
• 2009.07a
• /
• pp.619_620
• /
• 2009

본 논문은 자기장을 이용하여 전류를 안정화시켜 정밀전류를 발생 시킬 수 있는 장치에 관한 연구이다. 일반적으로 전류를 안정화 시키는 방법은 전류회로에 직렬로 저항을 연결하여 저항 양단에 유도되는 전압을 측정하여 전류를 제어하는 방법을 많이 사용한다. 그러나 이 방법은 정밀한 전류를 제어하기 위하여 직렬로 연결되는 저항값이 커야하며, 또한 전류에 의해 발생되는 열로 인해 저항값이 증가하기 때문에 정밀한 제어가 어렵다. 이러한 단점을 보완 할 수 있는 방법으로 전류회로에 직렬로 코일을 연결하여 전류가 변화면 코일속에 자기장이 변화는 원리를 이용하여 전류를 안정화시켜 정밀전류를 발생 할 수 있다. 본 연구에서는 저자기장 국가표준 확립 및 물리고유상수인 양성자 자기회전비율 측정을 위해 원자자기공명 방법을 이용하여 직류전류를 1 A 범위에서 $0.1{\mu}A$ 수준으로 안정화 시켰다.

• Computational Structural Engineering
• /
• v.8 no.4
• /
• pp.189-198
• /
• 1995

The conventional finite element formulations for incompressible materials show pressure oscillations or pressure modes in four-node quadrilateral elements of commonly used displacement and pressure interpolations. The criterion for the stability in the pressure solution is the so-called Babugka-Brezzi stability condition, and the above elements do not satisfy this condition. In this study, a pressure continuity residual based on the pressure discontinuity at element interfaces is used to study the stabilization of pressure solutions in bilinear displacement-constant pressure four-node quadrilateral elements. This pressure residual is implemented in Q1P0 element derived from the conventional incompressible elasticity. The pressure solutions can be stable with the pressure residual though they exhibit sensitivity to the stabilization parameters. Parametric study for the solution stabilization is also discussed.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.12 no.1
• /
• pp.545-551
• /
• 2011

Recently, demands for generating high quality tap waters are increasing with high concern of water pollution and corrosion of water pipelines. For the reasons, developing water quality stabilization technique in water purification system is sought rather than replacing to a new pipelines. In this study, high-purity liquid lime($Ca(OH)_2$) was introduced for a water quality stabilization technique in water purification process and simulated water distribution system of pilot-scale size was applied to evaluate anti-corrosion control effect. The effect of anti-corrosion control was calculated in terms of LSI(Langelier Saturation Index) In conclusion, the result of pilot plant showed improvement of corrosiveness by liquid lime($Ca(OH)_2$) with reduction of released iron(Fe). Application of anti-corrosion control technique to the mild steel coupon and the copper coupon were effective by indicating 35.4, 44.5% of improvements. Besides, sample pipes which were treated with liquid lime had formated more thicker layer of corrosion product inside of pipes. As a result, the process of injecting water stabilizer can greatly contribute to the high quality of tap water.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.06a
• /
• pp.41-42
• /
• 2008

p-type(100) Si 위에 BTMSM과 산소를 혼합한 전구체를 가지고 PECVD 방법을 사용 하여 저유전상수를 갖는 SiOCH막을 형성하였다. 알루미늄 전극을 구현한 MIS (Al/SiOCH/p-si(100)) 구조의 커패시터를 가지고 C-V 특성을 측정하여 유전상수를 계산하였다. 상온에서 증착된 SiOCH 박막의 유전상수는 $450^{\circ}C$에서 30분 동안 열처리 후 뚜렷하게 감소하는 경향을 나타냈으며, 상온 및 대기압에서 공기 중에 노출시켜 자연 산화과정을 겪은 후에 각각의 유전상수는 전체적으로 증가하였지만, 열처리한 박막이 상대적으로 경시효과(aging effects)에 대하여 안정화된 것을 확인하였다.

• Journal of the Korean Chemical Society
• /
• v.27 no.1
• /
• pp.1-8
• /
• 1983

Solvent effects on nucleophilic substitution reaction of naphthalene sulfonyl chlorides with pyridine in protic and aprotic solvent have been studied by means of conductometry. Results showed that the rate constants increased with dielectric constants for protic solvents, while they decreased with dielectric constants for aprotic solvents, except for acetonitrile which has a higher dielectric constant but had also greater rate constant. The rate constants were shown to be more susceptible to polarity-polarizability parameter, , than to hydrogen bond donor acidity parameter, ${\alpha}$, indicating that the pulling effect of hydrogen bonding solvent.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.06a
• /
• pp.43-44
• /
• 2008

PECVD 방식에 의거 low-k 유전상수를 갖는 층간 절연막 (ILD)를 제작하였다. 전구체 BTMSM 액체를 기화하여 16sccm 에서부터 1 sccm씩 증가하면서 25sccm 까지 p-Si[100] 기판위에 유량비를 조절하였으며 60 sccm으로 일정산소 $O_2$ 가스를 반응 챔버에 도달하도록 하였다. 제작된 시편의 구성성분은 FTIR의 흡수선으로 확인하였고, 알루미늄 전극을 구현한 MIS (Al/SiOCH/p-si(100)) 구조의 커패시터를 가지고 정전용량-전압 (C-V) 특성을 측정하여 유전상수를 계산하였다. BTMSM/$O_2$에 의한 층간절연막의 k ~ 2 근방의 저유전상수는 유량비에 민감하게 의존되고 열처리에 의하여 $CH_3$의 소멸 및 Si-O-Si(C) 성장하는 효과에 의하여 더 낮아짐을 확인할 수 있었다. 또한 상온 및 대기압에서 공기 중에 노출시켜 자연 산화과정을 겪은 시편들의 유전상수는 전체적으로 증가하였지만, 열처리한 박막이 상대적으로 안정화된 것을 확인하였다.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.15 no.1
• /
• pp.183-187
• /
• 2011

The polymer-stabilized blue phase liquid crystal (BPLC) cell has advantages such as sub-millisecond response time, wide viewing angle and no rubbing process for the alignment of liquid crystals. However, high operating voltage and low kerr constant of the polymer-stabilized blue phase liquid crystal deteriorate the electro-optical characteristic of the polymer-stabilized BPLC cell. In this paper, we proposed novel zig-zag electrode in cell layout and confirmed that proposed electrode shape could reduce an over 25 percent of operating voltage for BPLC cell without degradation of tranmittance by using Kerr constant simulation.

• Electrical & Electronic Materials
• /
• v.6 no.5
• /
• pp.407-416
• /
• 1993

무산소동을 안정화 모재로한 Cu/Nb-Ti 빌렛트를 제작한 다음 간접 열간방식의 압출에 의해 얻어진 봉재를 인발한 후 신선과 열처리를 반복하여 단심 및 다심 Nb-Ti 초전도 선재를 제조하였다. 가공 조직을 조사한 결과, 단심 선재의 경우 Nb-Ti 심의 단면이 균일하게 가공된 것을 확인하였으며 다심선재의 경우는 신선가공에 의하여 다소 불균질한 필라멘트부분이 관찰되었다. 4.2K, 자장하에서 4단자법으로 직선형 단척시료의 임계전류를 측정하여 가공 열처리 조건에 따른 임계전류밀도의 자장특성을 조사하였는데 열처리시간을 길게하고 가공도를 높인 시료일수록 자장하의 임계전류밀도가 높게 나타나는 것을 확인하였다. 4.2K, 5T 자장하에서 각각 4 x $10^{5}$A/$cm^{2}$ 및 2 x $10^{5}$A/$cm^{2}$의 임계전류밀도를 나타내는 Nb-Ti 단심 및 다심 초전도선재를 제작 할 수 있었다.있었다.

• Korean Journal of Soil Science and Fertilizer
• /
• v.44 no.6
• /
• pp.1063-1070
• /
• 2011

In this study, total of 5 different chemical amendments were evaluated for determining kinetic parameters and stabilization efficiency of heavy metals in aqueous phase. Standard solution of Cd and Pb ($100mg\;L^{-1}$) was mixed with various ratio of amendments (1, 3, 5, 10%) and heavy metal stabilization efficiency was monitored for 24hrs. All examined amendments showed over 90% of removal efficiency for both Cd and Pb except zerovalent iron (ZVI) for Cd (43-63%). Based on result of heavy metal stabilization efficiency, it was ordered as $CaCO_3$ > Dolomite > Zeolite > Steel slag > ZVI for both Cd and Pb in aqueous phase. For kinetic study, first order kinetic model was adapted to calculate kinetic parameters. In terms of reaction rate constants (k), zeolite showed the fastest reaction rate (k value from 0.4882 for 1% to 2.0105 for 10%) for Cd and ZVI (k value from 0.2304 for 1% to 0.5575 for 10%) for Pb. Considering reaction rate constant and half life for heavy metal stabilization, it was ordered as Zeolite > $CaCO_3$ > Dolomite > Steel slag > ZVI for Cd and $CaCO_3$ > Dolomite > Steel slag > Zeolite > ZVI for Pb. Overall result in this study can be interpreted that lime containing materials are more beneficial to remove heavy metals with high efficiency and less time consuming than absorbent materials.