• Biomolecules & Therapeutics
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• 제19권3호
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• pp.357-363
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• 2011

In relieving local pains, ropivacaine has been widely used. In case of their application such as ointments and creams, it is difficult to expect their effects for a significant period of time, because they are easily removed by wetting, movement and contacting. Therefore, the new formulations that have suitable bioadhesion were needed to enhance local anesthetic effects. The effect of drug concentration and temperature on drug release was studied from the prepared 1.5% Carboxymethyl cellulose (CMC) (150MC) gels using synthetic cellulose membrane at $37{\pm}0.5^{\circ}C$. As the drug concentration and temperature increased, the drug release increased. A linear relationship was observed between the logarithm of the permeability coefficient and the reciprocal temperature. The activation energy of drug permeation was 3.16 kcal/mol for a 1.5% loading dose. To increase the skin permeation of ropivacaine from CMC gel, enhancers such as saturated and unsaturated fatty acids, pyrrolidones, propylene glycol derivatives, glycerides, and non-ionic surfactants were incorporated into the ropivacaine-CMC gels. Among the enhancers used, polyoxyethylene 2-oleyl ether showed the highest enhancing effects. For the efficacy study, the anesthetic action of the formulated ropivacaine gel containing an enhancer and vasoconstrictor was evaluated with the tail-flick analgesimeter. According to the rat tail-flick test, 1.5% drug gels containing polyoxyethylene 2-oleyl ether and tetrahydrozoline showed the best prolonged local analgesic effects. In conclusion, the enhanced local anesthetic gels containing penetration enhancer and vasoconstrictor could be developed using the bioadhesive polymer.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
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• pp.90.2-90.2
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• 2011

세계 각 국에서는 선진국을 중심으로 기후변화와 치솟는 유가에 대응하기 위하여 다양한 에너지원의 확보를 위해 부단히 노력하고 있다. 특히, 신재생에너지원 중 에너지 지속성이 가장 우수한 연료전지의 경우 1kW급 건물용 연료전지시스템이 도시가스 인프라가 가장 우수한 한국 및 일본을 중심으로 상용화에 가장 근접해 있는 실정이다. 일본의 경우 가정용 연료전지시스템 '에너팜'의 일부 제품이 올해부터 200만엔대로 가격을 내려 보급되어질 예정이고, 아직은 경제성이 떨어지지만 연료전지 조기 상용화를 위해 시스템 가격저감을 통한 기술개발이 한창이다. 또한 700W급 고체산화물형 연료전지시스템을 세계에서 처음 시판 계획을 가지고 있다. 국내의 경우 2009년도부터 시작된 '그린홈 보급확대를 위한 건물용 연료전지 보조기기 가격저감 기술개발'연구를 통해 블로워, 밸브, 유량계 및 펌프 등의 보조기기의 단가를 낮추고자 기술개발에 박차를 가하고 있다. 이에 따른 연료전지 부품 가격저감 기술이 국내 건물용 연료전지 시장보급의 활력소가 되기를 기대한다. 본 연구에서는 건물용 연료전지의 보조기기인 블로워의 가격저감을 위한 연구의 일환으로 블로워의 안전성능 평가를 통한 보조기기의 가격저감 및 안전성을 확보하고자 한다. 1kW급 건물용 연료전지시스템의 여러 블로워 중 도시가스용 연료승압 블로워, 선택산화 공기 블로워, 버너 공기 블로워 및 캐소드 공기 블로워의 안전성능 평가를 수행하였고, 평가결과의 공유를 통하여 국내 블로워 제조사의 설계방향을 제시하고 연료전지시스템의 안전성을 확인하고자 한다. 특히, 내구성, 기밀, 가혹조건시험 및 소음, 진동, 습도, 온도와 같은 내주위환경시험 등의 평가결과 비교를 통하여, 연료전지 부품 인증기준을 재정립하여 연료전지 부품산업의 조기 활성화를 도모하고자 한다.

• 조명전기설비학회논문지
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• 제23권8호
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• pp.48-56
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• 2009

본 논문은 연료전지스택을 입력전원으로 하는 TIG-용접기용 전력변환장치를 제안하였다. 일반적으로 TIG-용접기의 전원공급장치는 상용전원을 이용한 다이오드 브리지 정류회로를 사용한다. 이런 회로의 경우 다이오드 정류기와 용량이 큰 캐패시터를 사용하게 되므로 부피가 커지고, 입력전류는 맥동성분과 고조파를 포함하게 된다. 또한, TIG-용접기는 상용전원의 사용이 여의치 않은 도서산간지역이나 특수한 환경에서는 소형 경량의 이동성이 수월한 전원장치 및 전력원을 필요로 하게 된다. 따라서 본 논문의 TIG-용접기용 전력변환장치는 고체고분자형연료전지(PEMFC)를 입력전원으로 사용하고, 부스트 컨버터의 기능과 인버터 용접전원의 기능을 하나의 풀-브리지 컨버터로 구성하였다. 제안한 연료전지를 이용한 TIG-용접기용 전력변환장치는 컴퓨터 시뮬레이션과 실험을 통하여 성능을 검증하였다.

• Membrane and Water Treatment
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• 제8권3호
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• pp.245-257
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• 2017

The separation of nicotine and tobacco-specific N-nitrosamines is a tough problem in tobacco industry. In this study, separation of nicotine from 4-(methylnitrosamino) -1-(3-pyridyl)-1-butanone (NNK) mixtures was investigated using electrodialysis by taking the principle of the protonation status difference between these two components. The results indicated that the solution pH has a dominant impact on the separation process. In a pH range of 5-7, nicotine molecules are existed as mono- and di-protonated ions and can be separated from the uncharged NNK molecules. The acidic electrolyte is conducive to the separation process from the point of flux and energy consumption; while the alkaline electrolyte has negative impact on the separation process. A current density of $10mA/cm^2$ is an appropriate value for the separation process. The lowest energy consumption of the separation process is 0.58 kWh/kg nicotine with the process cost to be estimated at only $0.208 /kg nicotine. Naturally, electrodialysis is a high-efficiency, cost-effective, and environmentally friendly process to separate and purify nicotine from tobacco juice.

• 한국정보통신학회논문지
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• 제20권12호
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• pp.2395-2400
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• 2016

암 환자들을 대상으로 하는 항암치료법은 나노입자, 폴리머 중합체, 지질, 리포솜 등을 치료 전달체로 이용하여 항암치료를 진행하는 방법들이 주로 활발하게 사용되고 있다. 이러한 전달체는 항암 치료제를 직접 암세포로 정확하게 표적 운반하는 정확성, 정확하게 운반한 후 선택적으로 항암치료제를 방출해야하는 유출제어, 다른 일반 세포들을 약물로부터 보호하는 기능 등을 동시에 가지고 있어야 하지만, 대부분 항암약물의 독성에 기인한 부작용이 발생하고 있다. 겸형적혈구는 암세포주변 혈관세포와 멤브레인 표면에 존재하는 리셉터 사이에의 점착성이 존재하며 추가적 생화학처리 없이 암세포 주변에 표적화가 가능함을 보인다. 또한, 암세포 주변의 혈관의 구조적 변화특성은 겸형적혈구의 중합화 반응을 증가시킨다. 따라서 본 논문에서는 겸형적혈구를 이용한 새로운 항암치료법의 효과를 정량적 혈관분석 방법을 통해 제시하고자 한다.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2011년도 임시총회 및 하계학술연구발표회
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• pp.129-129
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• 2011

The limited understanding of the surface properties of $Pt_3Ni$ for the oxygen reduction reaction (ORR) in polymer electrolyte membrane fuel cell (PEMFC) has motivated the study of properties and electronic structures of seven layered $Pt_3Ni$ (001), (110), and (111) surfaces. The first principle method based on density functional theory (DFT) is carried out. It is found that the bulk $Pt_3Ni$ has a ferromagnetic ground state with the ordered fcc type L12 structure, which is in good agreement with other results. Non magnetic Pt has the induced magnetic moment due to the strong hybridization between 3d Ni and 5d Pt. The magnetic moment of Pt and Ni enhanced on the surface of each due to surface effect however the magnetic moment of surface Pt in the Pt-segregated Pt3Ni (111) decreased and the magnetic moment of Ni in Ni rich subsurface increased significantly. The calculated d band centers of Pt explain the possibilities for oxygen absorption and play the important roles in altering the catalytic properties. The spin polarized densities of states are presented in order to understand physical properties of Pt in different surfaces in detail.

• 한국수소및신에너지학회논문집
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• 제15권1호
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• pp.23-31
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• 2004

For the fabrication of high efficient bifunctional electrocatalyst of oxygen electrode for PEM URFC (Polymer Electrolyte Membrane Unitized Regenerative Fuel Cell), which is a promising energy storage and conversion system using hydrogen as the energy medium, several bifunctional electrocatalysts were prepared and tested in a single cell URFC system. The catalysts for oxygen electrode revealed fuel cell performance in the order of Pt black > PtIr > PtRuOx > PtRu ~ PtRuIr > PtIrOx, whereas water electrolysis performance in the order of PtIr ~ PtIrOx > PtRu > PtRuIr > PtRuOx ~ Pt black. Considering both reaction modes PtIr was the most effective elctrocatalyst for oxygen electrode of present PEM URFC system. In addition, the water electrolysis performance was significantly improved when Ir or IrOx was added to Pt black just 1 wt.% without the decrease of fuel cell performance. Based on the catalyst screening and the optimization of catalyst composition and loading, the optimum catalyst electrodes for PEM URFC were $1.0mg/cm^2$ of Pt black as hydrogen electrode and $2.0mg/cm^2$ of PtIr (99:1) as oxygen electrode.

• 전력전자학회논문지
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• 제17권6호
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• pp.553-561
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• 2012

Existing energy sources convert chemical energy into mechanical energy, while fuel cell directly generates electricity through an electrochemical reaction between hydrogen and oxygen. Therefore, it has a lot of strong points such as high efficiency, zero emission, and etc. In addition, with the development of hydrogen preservation technique, some companies have been researching and releasing portable fuel cell power packs for specific applications like military equipment, automobile, and so on. However, there are some drawbacks to the fuel cell, high cost and slow dynamic response. In order to compensate these weak points, auxiliary energy storages could be applied to the fuel cell system. In this paper, the optimum structure for a 150W portable fuel cell power pack with a battery pack is selected considering the specification of the system, and the design process of main parts is described in detail. Here, main objectives are compact size, simple control, high efficiency, and low cost. Then, an automatic mode change algorithm, which converts the operating mode depending on the states of fuel cell stack, battery pack, and load, is introduced. Finally, performance of the designed prototype using the automatic mode change control is verified through experiments.

• 한국수소및신에너지학회논문집
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• 제23권6호
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• pp.640-646
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• 2012

The effect of Ce promotion over 1wt% $Pt/{\gamma}-Al_2O_3$ catalysts on the CO conversion and $CO_2$ selectivity was investigated in preferential CO oxidation (PrOx) to reduce the CO concentration less than 10 ppm in excess $H_2$ stream for polymer electrolyte membrane fuel cell (PEMFC). Ce-promoted 1wt% $Pt/{\gamma}-Al_2O_3$ catalysts were prepared by incipient wetness impregnation method and the loading amount of Pt was fixed at 1wt%. The content of Ce promoter which has excellent oxygen storage and transfer capability due to the redox property was adjusted from 0 to 1.5wt%. Ce-promoted 1wt% $Pt/{\gamma}-Al_2O_3$ catalysts exhibit high CO conversion and $CO_2$ selectivity at low temperatures below $150^{\circ}C$ due to the improvement of reducibility of surface PtOx species compared with the 1wt% $Pt/{\gamma}-Al_2O_3$ catalyst without Ce addition. When Ce content was more than 1wt%, the catalytic activity was decreased at over $160^{\circ}C$ in PrOx because of competitive $H_2$ oxidation. As a result, 0.5wt% Ce is optimal content not only to achieve high catalytic activity and good stability at low temperatures below $150^{\circ}C$ in the presence of $CO_2$ and $H_2O$ but also to minimize the $H_2$ oxidation at high temperatures.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제27권1호
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• pp.9-14
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• 2001

With the object of providing a temporary artificial periodonal ligament-like membrane around the dental implant, 10 Branemark type implants were coated with commercially available chitosan(Fluka Co., Buchs, Switzerland) which has a molecular weight of 70,000 and 80% deacetylation degree. Once this bioactive hydrophillic polymer(chitosan) contacts with blood or wound fluids, it becomes swollen and penetrates into the adjacent cancellous bone. Thus the interface between implant and surrounding bone is completely filled with chitosan. This tight junction in early healing phase enhances primary stability. The chitosan coated dental implants were implanted into the fresh patella bones from porcine knees, since the thickness of cortical bone is relatively even and their cancellous structure is homogenous. To test the shock absorbing effect, 1mm delta-rogette strain gage was installed behind the implant. The results showed 1. The principal strain peak value directed to the impact of coated implant was 0.064 0.018(p<0.05) and that of uncoated implant was 0.095(0.032 p<0.05). 2. The peak time delay of coated implant was 0.056sec(0.011 p<0.05) and that of uncoated implant was 0.024sec(0.009 p<0.05). It can be reasoned from this results that the chitosan coating has a shock absorbing effect comparable with a temporary artificial periodontal ligament.