• Journal of IKEEE
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• v.24 no.3
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• pp.713-718
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• 2020

The method of measuring skin active points is a technique for obtaining a lot of biometric information because it is measured with convenience, low cost and non-invasive methods. In this paper, we used in a three electrode measure method that has the advantage of measuring the impedance of the APs under the skin. The impedance measuring method is well illustrated by a simple model of an equivalent electrical circuit that correlates well with experimental results. The characteristic frequencies of APs are about 15-30HZ higher than that of surrounding skin and the values of measured reactance are about 35-77KΩ smaller. This technology analyzed accurately and objectively the reactance and characteristic frequency of APs and the surrounding skin using a non-invasive measuring system.

• Journal of Oral Medicine and Pain
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• v.17 no.1
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• pp.73-87
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• 1992

저자는 28명의 측두하악장애 환자와 31명의 정상인을 대상으로 최적기능교합의 개념에 입각하여 교합시의 치아접촉점을 동적이며 정량적인 방법으로 평가하여 교합안정장치의 사용으로 인한 교합안정성의 개선여부를 알아보고자 하였다. 이와 동시에 교근과 전측두근의 활성도를 측정하여 치료의 경과에 따른 근활성의 변화를 알아보기 위해 본 연구를 시행하였다. 측정항목은 개구범위, 두개하악장애지수, 치아접촉점 좌우균형치, 치아접촉점 전후균형치, 치아접촉점 평균시간간격, 치아접촉점의 개수, 접촉시간, 좌우측 교근과 좌우측 전측두근의 근활성, 근활성 비대칭 지수 등이었다. 이의 측정을 위해 T-Scan System, K-6 Diagnostic System 그리고 EM 2등을 사용하였으며 얻어진 자료에 대해 검정한 후 다음과 같은 결론을 얻었다. 1. 교합안정장치를 이용하여 측두하악장애 환자들을 4주간 치료한 결과 전반적인 임상증상이 호전되어 개구범위와 두개하악장애지수에 있어서 뚜렷한 개선이 있었다. 2. 측두하악장애 환자에서 최대 악물기시의 치아접촉점 좌우균형치및 평균시간 간격이 큰 것으로 나타나 치아접촉이 일어나는 순간의 교합안정성이 좋지 않은 것으로 평가되었다. 3. 치료 4주후 교하안정장치를 장착한 상태에서 측정한 치아접촉점 좌우균형치및 치아접촉점 평균시간간격은 치료전에 비해 개선된 것으로 나타났다. 4. 치료 4주후 치아접촉점의 전후방 분포가 구치부위로 이동되는 양상을 보였다. 5. 측두하악장애 환자에서 최대 악물기시의 좌우측 교근 및 전측두슨의 근활성은 정상인에 비해 낮에 나타났으며, 이는 치료기간 동안 감소되는 경향을 나타내었다. 6. 측두하악장애 환자에서 전측두근의 근활성 비대칭지수는 정상인에 비해 상당히 높게 나타났으며 이는 치료기간 동안 감소되는 경향을 나타내었다.

• Korean Chemical Engineering Research
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• v.47 no.1
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• pp.31-37
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• 2009

A zwitterionic surfactant shows not only detergency but also mildness effect since it shows characteristics of a nonionic or an anionic surfactant above an isoelectric point, while showing characteristics of a cationic surfactant below an isoelectric point. Therefore, a zwitterionic surfactant can serve as a dual function surfactant by a single molecule through the interconversion of cleaning and softening effects depending on pH variations of the aqueous solution. In this study, physical properties of betaine surfactant such as CMC, surface tension, interfacial tension, contact angle and viscosity were measured and phase behavior study was performed. Also dual function characteristics of betaine zwitterionic surfactant were investigated by measuring an isoelectric point using QCM(quartz crystal microbalance) and zeta potential measurement. The CMC of betaine surfactant was near $10^{-4}mol/L$ and the surface tension at CMC was about 32 mN/m. The interfacial tension between 1 wt% aqueous solution and n-decane measured by spinning drop tensiometer at pH 2~10 resulted in an increase in interfacial tension until pH 5 and a decrease with pH after 5 and equilibration time showed the similar trend with an increase in pH. The isoelectric point of betaine surfactant measured by QCM experiment was found to exist between 3.0 and 3.3, which is the same as the result determined by zeta potential measurement.

• Applied Chemistry for Engineering
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• v.20 no.1
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• pp.9-14
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• 2009

A zwitterionic surfactant shows not only detergency but also softening effect since it shows characteristics of a nonionic or an anionic surfactant above an isoelectric point, while showing characteristics of a cationic surfactant below an isoelectric point. Therefore, a zwitterionic surfactant can serve as a dual function surfactant by a single molecule through the interconversion of cleaning and softening effects depending on pH of the aqueous solution. In this study, the dual function characteristics of an amine oxide zwitterionic surfactant were investigated by measuring the zeta potential and the isoelectric point using quartz crystal microbalance (QCM). In addition, the physical properties of an amine oxide surfactant such as critical micelle concentration, surface tension, interfacial tension, contact angle and viscosity were measured and phase behavior study was also performed. The isoelectric point of an amine oxide surfactant determined by zeta potential measurement was near 7.35 and that obtained by QCM experiment was about 7.4, where both results were found to be close to the value reported in the literature.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2004.05a
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• pp.40-45
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• 2004

액상 TCE 제거반응을 위한 Hetero-CWO 촉매들 중에서 $CoO_{x}$/$TiO_2$와 $CuO_{x}$/$TiO_2$가 상대적으로 유망한 것으로 보여졌으며, 특히 5% $CoO_{x}$/$TiO_2$ 촉매의 경우에 반응시간에 따른 활성추이는 TCE 제거반응에서 주요 역할을 할 수 있는 반응 활성점의 변화를 암시하고 있다. $FeO_{x}$ /$TiO_2$와 Fe-MFI 촉매상에서 TCE 제거반응에 대한 시간에 따른 활성거동으로부터 활성점의 redox cycle를 어떻게 제어하는가 하는 점이 매우 중요함을 알 수 있었으며, 촉매표면에서 이를 유지.증진시킬 수 있는 촉매 디자인 기법이 요구되었다.

• Applied Chemistry for Engineering
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• v.23 no.1
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• pp.112-118
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• 2012

In this study, physical properties of synthesized DE7-OSA82-AO and DEP52-OSA82-AOQ82 zwitterionic surfactants were measured such as critical micelle concentration, surface tension, interfacial tension, contact angle and viscosity. Phase behavior study was also performed. The dual function characteristics of a zwitterionic surfactant were investigated by determining an isoelectric point, which was attained using zeta potential measurements and QCM (quartz crystal microbalance) experiments. The isoelectric point of DE7-OSA82-AO surfactant determined by the zeta potential measurement and QCM experiment was about 7.2 and 7.4, respectively. On the other hand, the isoelectric point of DEP52-OSA82-AOQ82 surfactant determined by the zeta potential measurement and QCM experiment was about 10.9 and 11.0, respectively. The frictional property measured using an automated mildness tester showed that DE7-OSA82-AO surfactant can provide a good softening effect at an acidic or neutral condition. On the other hand, DEP52-OSA82-AOQ82 was found to provide a good softening effect to a fabric surface at a pH below its isoelectric point of 11.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.164-164
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• 2011

본 연구에서는 InAs 양자점 태양전지의 활성영역에 크기가 다른 양자점을 삽입하여 그 광학적 특성변화를 photoreflectance (PR)와 photoluminescence (PL)를 이용하여 연구하였다. 본 연구에 사용된 InAs 양자점 태양전지 구조는 n+-GaAs (100) 기판 위에 n+-GaAs buffer를 300 nm 성장 후 활성영역에 InAs 양자점과 40 nm 의 n-GaAs spacer를 이용하여 8층의 양자점을 삽입하였다. 그 위에 n-GaAs $1.14{\mu}m$와 p+-GaAs $0.6{\mu}m$, p+-AlGaAs window를 50 nm 성장하고 ohmic contact을 위하여 p+-GaAs 10 nm 성장하였다. 활성영역에 사용된 InAs 양자점의 크기는 InAs 조사량을 1.7 ML~3.0 ML까지 변화시키며 조절하였다. 양자점 태양전지의 활성영역에 삽입한 양자점의 크기에 따른 photoreflectance 측정에서 InAs 조사량이 0~2 ML 사이에서는 Franz-Keldysh oscillation (FKO)의 주기가 짧아지고 2.5 ML 이상에서는 일정한 값 가짐을 보였다. 이는 양자점의 크기가 커질수록 내부 응력에 의한 전기장의 변화에 의한 것으로 사료된다. 아울러 InAs 양자점 태양전지의 photoluminescence 측정 결과 상온에서 1.35 eV 근처에 발광이 관측되었으며 InAs 조사량이 증가할수록 발광중심 낮은 에너지쪽으로 이동함을 보였으며 태양전지 효율은 2.0 ML 인 경우 최고치를 나타내었다. InAs 조사량을 2.0 ML 이상 증가 시킨 경우는 효율이 점진적으로 감소하였다.

• Korean Chemical Engineering Research
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• v.50 no.3
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• pp.455-463
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• 2012

In this study, the measurement of physical properties of ethylene oxide-propylene oxide adducted zwitterionic surfactants were measured such as critical micelle concentration, surface tension, interfacial tension, contact angle, viscosity and foam stability. Also, the dual function characteristics of a zwitterionic surfactant were investigated by determining an isoelectric point, which were obtained using zeta potential measurement and QCM (quartz crystal microbalance) experiments. The isoelectric point of DEP-OSA82-AO zwitterionic surfactant determined by zeta potential measurement was close to that obtained by QCM experiment and both results have shown almost the same trend as that determined by the frictional property measured using an automated mildness tester. In particular, it has been observed that DEP32-OSA82-AO and DEP34-OSA82-AO surfactants provide better softening effect at a pH of acidic or neutral condition than at an alkaline condition. This result indicates that both surfactants act as a cationic surfactant at a pH of acidic or neutral condition and thus provide good softening effect during a rinsing cycle in the detergency process.

• Korean Journal of Plant Resources
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• v.22 no.1
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• pp.71-77
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• 2009

Antioxidative activity and ${\alpha}$-amylase inhibitory activity were investigated in the methanol extracts of 289 species of angiosperm plants native to Jeju Island in order to select the plant species containing bioactive materials for functional foods or medicines. The antioxidative activity, estimated by the DPPH radical scavenging capacity, was high in the galla of Rhus chinensis, the fruit of Platycarya strobilacea, and the stem of Cedrela sinensis. Particularly, the antioxidative activity of Rhus chinensis galla (94.2${\pm}$0.8%) was very high even though compared to those of BHA (61.7${\pm}$0.6%) and ascorbic acid (53.6${\pm}$0.7%). The ${\alpha}$-amylase inhibitory activity was 80% or above in 9 species including Cornus macrophylla (stem, leaf), Distylium racemosum (leaf) and Vaccinium oldhami (leaf). These results suggest that these plants could be potentially utilizable to develop bioactive materials for functional foods or medicines.

• Journal of the Korean Chemical Society
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• v.23 no.2
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• pp.80-87
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• 1979

The active site for the formation of acrolein in propylene oxidation reaction over copper(Ⅱ)-exchanged zeolite Y has been studied. At the early stage of the reaction, the formation of hydrocarbons was observed. The formation of hydrocarbons decreased gradually during the course of reaction, apparently due to the poisoning the Bronsted acid sites. The formation of acrolein was quite low when the formation of hydrocarbons was proceeding. The formation of acrolein was depend on the copper ion content and this can be related to the availability of the copper ions inside the supercage. It seems that it is the copper ion not the Bronsted acid site which is primarily responsible for the formation of acrolein.