프로필렌글리콜에 분산된 나피온 이오노머로 제조된 공기극 촉매층의 연료전지 성능 특성 연구

우승희,양태현,박석희,임성대 한국화학공학회 2019 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.57 No.4

고분자연료전지용 막전극접합체(Membrane Electrode Assembly, MEA)의 저가화 및 고성능화를 위하여 촉매층을 구성하는 촉매와 이오노머의 계면 특성에 대한 이해가 중요한 연구주제가 되고 있다. 본 연구에서는 이오노머의 구조 제어를 위하여 상용 이오노머의 용매로 사용되는 물 대신에 프로필렌글리콜(Propylene Glycol, PG)을 용매로 사용하여단측쇄(Short Side Chain, SSC) 나피온 이오노머가 분산된 현탁액을 제조하고 이를 이용하여 공기극 촉매층을 제조하여 연료전지 성능 특성을 평가하였다. PG 기반 이오노머의 함량을 20~35 wt%로 증가시키면서 제조된 촉매층의 연료전지 성능은 상용 물 기반 이오노머와는 달리 이오노머 함량이 35 wt%까지 증가함에 따라 성능도 지속적으로 증가하였다. PG 기반 이오노머의 작은 입도와 느린 건조 속도는 균일 구조의 촉매층 형성을 유도하여 수소이온전달에는 효과적이었지만 PG 기반 이오노머 필름의 낮은 산소투과도는 MEA 성능을 저하시키는 주요 문제로서 개선이 필요하였다. To develop a membrane electrode assembly (MEA) with lower Pt loading and higher performance in proton exchange membrane fuel cells (PEMFCs), it is an important research issue to understand interfacial structure of Pt/C catalyst and ionomer and design the catalyst layer structure. In this study, we prepared short-side-chain Nafion-based ionomer dispersion using propylene glycol (PG) as a solvent instead of water which is commonly used as a solvent for commercially available ionomers. Cathode catalyst layers with different ionomer content from 20 to 35 wt% were prepared using the ionomer dispersion for the fabrication of four different MEAs, and their fuel cell performance was evaluated. As the ionomer content increased to 35 wt%, the performance of the prepared MEAs increased proportionally, unlike the commercially available water-based ionomer, which exhibited an optimum at about 25 wt%. Small size micelles and slow evaporation of PG in the ionomer dispersion were effective in proton transfer by inducing the formation of a uniformly structured catalyst layer, but the low oxygen permeability problem of the PG-based ionomer film should be resolved to improve the MEA performance.

저온균일침전법으로 제조된 TiO₂ 분말의 아크릴레진에서의 분산특성 및 광분해 효과

우승희,김흥회,이창규,Woo S. H.,Kim W. W.,Rhee C. K. 한국분말야금학회 2004 한국분말재료학회지 (KPMI) Vol.11 No.6

Dispersion stabilities and photocatalytic activities of rutile $TiO_{2}$ powders with unique nano-structure synthesized by homogeneous precipitation process at low temperature(HPPLT) have been investigated in the acrylic resin containing fluorostyrene in the range of 0~0.16 mole. Isoelectric point of $TiO_{2}$ in the acrylic resin placed in the neutral region whereas that of $TiO_{2}$ in the water placed in the acidic region, indicating that zeta potential and agglomeration of $TiO_{2}$ powder is strongly dependent on the pH and the type of solvent. To prepare an adhesion, an acrylic resin containing fluorostyrene was synthesized by a radical polymerization. The adhesion of coating layer was increased with increasing fluorostyrene's contents without changing the dispersion stabilities and degrading photocatalytic properties.

물증을 남지기 않는 키스

우승희 샘터사 1997 월간 샘터 Vol.28 No.8

전기분해법에 의한 수산화알루미늄 나노화이버 제조

우승희,이민구,이창규,Woo S.H.,Lee M.K.,Rhee C.K. 한국분말야금학회 2006 한국분말재료학회지 (KPMI) Vol.13 No.2

Aluminum hydroxides were synthesized by a simple electrolytic reaction of aluminum plates. The aluminum hydroxide, boehmite (AlO(OH)), was predominantly formed in the application of electrical potential at and above 30V, while the mixture of bayerite ($Al(OH)_3$) and boehmite (AlO(OH)) phases were formed below 20V. The boehmite has a clear fibrous structure controlled on nanometer scale. On the contrary, the bayerite consists of the typical hourglass or semi-hourglass shaped coarse crystals as a result of aggregation of various crystals stacked together. The specific surface area of the boehmite nanofiber was markedly high, approaching at about $302\;m^2/g$.

TiO₂ 나노 분말의 분산 안정성 및 침강 특성

우승희,이민구,이창규,Woo S.H.,Lee M.K.,Rhee C.K. 한국분말야금학회 2006 한국분말재료학회지 (KPMI) Vol.13 No.4

In this study, the colloidal stability and sedimentation behavior of crystalline $TiO_2$ particles (300nm) in various organic solvents have been investigated by means of a backscattered light flux profile (Turbiscan). The backscattered light flux profiles revealed that the $TiO_2$ nanoparticles were readily sedimented in water, methyl alcohol, and ethyl alcohol due to a flocculation-induced particle growth, while a particle coalescence and a sedimentation of the $TiO_2$ nanoparticles were hardly observed in isopropyl alcohol. The migration velocities of the $TiO_2$ particle were measured as around 6.15/min, 12.53 m/min, 6.51m/min, and 0.18m/min for water, methyl alcohol, ethyl alcohol, and isopropyl alcohol, respectively, showing a remarkably slow migration of the $TiO_2$ particles in isopropyl alcohol.

소매믹스, 소비감정, 고객만족, 재방문의도의 관계: 대전지역 전통시장을 중심으로

우승희,김원겸 한국상품학회 2022 商品學硏究 Vol.40 No.6

Due to the opening of the retail markets and the rapid increase of large retail stores, traditional markets have been experiencing many difficulties with regards to management. Furthermore, traditional markets have recently been adversely affected by COVID-19. This traditional market stagnation can be caused by a combination of internal and external problems. The purpose of this study is to present a marketing strategy to increase the intention to revisit by understanding how retail mix factors, consumption emotions and customer satisfaction related to shopping in traditional markets affect consumers' revisit intention. To achieve the purpose of the study, a theoretical approach through literature review and an empirical analysis based on a consumer survey were performed simultaneously. The empirical results indicate that retail mix affected positive emotions. In particular, price factors among retail mix factors had the greatest influence on positive emotions. On the contrary, product, location, and display had no impact on negative emotions. The factor that had a great influence on negative emotion was the price. It was confirmed that consumption emotion affects customer satisfaction and revisit intention. Also, customer satisfaction had a significant effect on revisit intention.

Effect of Aluminum Chloride Hemostatic Agent on Bonding Strength of RMGIC in Primary Tooth

우승희,신지선,이준행,한미란,김종수,Woo, Seung-Hee,Shin, Jisun,Lee, Joonhaeng,Han, Miran,Kim, Jong Soo Korean Academy of Pediatric Dentistry 2021 大韓小兒齒科學會誌 Vol.48 No.4

이 연구의 목적은 유치의 상아질면에서 염화알루미늄 지혈제의 적용이 레진강화형 글라스아이오노머(RMGIC)의 결합에 미치는 영향을 전단결합강도, 주사전자현미경(SEM), 에너지분산형 분광분석기(EDS)를 통하여 평가하는 것이다. 36개의 유구치가 이용되었으며, 상아질이 노출되도록 시편을 제작하여 상아질 전처리과정에 따라 4개의 군으로 분류하였다. I, II, III, IV군은 각각 전처리를 하지 않은 군, 25% polyacrylic acid(PAA)를 10초간 적용한 군, 21.3% 염화알루미늄 지혈제를 1분간 적용한 군, IV군은 염화알루미늄 지혈제를 1분간 사용한 뒤 PAA를 10초간 적용한 군으로 설정하였다. 각 군당 15개의 시편에 RMGIC를 중합하여 전단결합강도를 측정하였다. 각 군당 3개의 시편을 SEM/EDS 분석하였다. II군, IV군, I군, III군 순서로 결합강도가 유의하게 높았다. SEM 촬영으로 염화알루미늄 지혈제를 적용한 군들은 도말층이 일부 제거 되었음을 확인하였다. EDS 분석결과, 염화알루미늄 지혈제 적용 후 칼슘의 감소 및 염소와 알루미늄의 증가가 확인되었고, PAA 사용후에도 증가한 염소는 감소하지 않음을 관찰하였다. 연구를 통해 염화알루미늄 지혈제는 PAA의 사용에 관계없이 상아질에서 RMGIC의 전단결합강도를 감소시키는 것을 알 수 있다. The purpose of this study was to evaluate the effect of a hemostatic agent containing aluminum chloride on the shear bond strength of resin-modified glass ionomer cement (RMGIC) to the dentin of primary teeth. Thirty-six extracted non-carious human primary teeth were collected in this study. Dentin surfaces were cut and polished. The specimens were randomly divided into 4 groups; group I: RMGIC without conditioning; group II: polyacrylic acid (PAA), RMGIC; group III: aluminum chloride, RMGIC; group IV: aluminum chloride, PAA, RMGIC. All teeth were thermocycled between 5.0℃ and 55.0℃ for 5000 cycles. Fifteen specimens from each group were subjected to shear bond strength test and 3 specimens from each group were inspected using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy. The mean shear bond strength of each group was as follows: 4.04 ± 0.88 MPa in group I, 8.29 ± 1.40 MPa in group II, 1.39 ± 0.47 MPa in group III, 6.24 ± 2.76 MPa in group IV. There were significant differences among all groups (p < 0.001). SEM image of the dentinal tubules were partially exposed in group III and group IV. Fully exposed dentinal tubules were found in group II. In conclusion, aluminum chloride decreased the shear bond strength of RMGIC to dentin, regardless of PAA conditioning.

영암군 고향사랑기부제 현황 및 활성화 제언

우승희 한국지방자치학회 2023 학술발표대회 논문집 Vol.2023 No.2

노인 환자의 만족도가 치과의료기관 재이용에 미치는 영향

우승희,김은주,이재라 대한치과위생학회 2017 대한치과위생학회지 Vol.19 No.2

The purpose of this study was to closely examine how the satisfaction plays a role as a mediating variable of reuse and positive promotion through analyzing the satisfaction with dental institutions of being used by the rapidly-growing elderly population and through investigating the influence of users' satisfaction upon intention of reuse. The following conclusions were elicited. First, the satisfaction at dental institutions in Mokpo area as the subject of this study appeared to be relatively high level. Especially, the satisfaction with dentists and dental hygienists stood at 4.30 points and 4.39 points, respectively, thereby having shown a very high outcome. And as a result of having surveyed the intention of public relations, the intention of recommending to people around, and the intention of a preferential choice in terms of the reuse, a slightly high level was indicated with 4.26 points, 4.29 points, and 4.20 points. Second, in consequence of having surveyed a difference in dental service satisfaction depending on general characteristics, the satisfaction at the facilities & environment, and at dental hygienists showed a difference according to gender. Men were surveyed to have a higher satisfaction than women. A statistical significance was indicated. Compared to National Health Insurance participants, the Medical Aid Beneficiaries were surveyed to have a higher satisfaction with the facilities & environment, with reception & administration, and with dental hygienists. Third, as a result of having surveyed a correlation between the dental institution satisfaction and the reuse-related question, a positive correlation was shown in all of the satisfaction with the intention of public relations, with the intention of recommending to people around, and with the intention of preferential choice. Thus, it could be known that the higher satisfaction leads to getting higher even in possibility of reuse. In this way, the satisfaction at dental institutions has positive influence upon selecting and re-using dental clinics. Hence, the dental institutions need to constantly strive to improve quality of medical service. To do this, a positive effort and investment should be made. A systematic program is considered to be likely necessary for reinforcing service quality and intensifying competitive edge. And to promote the dental institution's service quality based on the results of this study, it is considered to be likely needed introduction and activation of the dental institution accreditation system. Many dental institutions were changed now in comparison with the past. But the dental institution accreditation system is being autonomously enforced, thereby causing polarization in an institution with the execution of dental institution accreditation system and in an institution with its opposite case. Accordingly, an institutional device is needed that can supplement this. There is a need to establish the specialized and organized quality control system in order to step up quality of medical service.

Multiplexed Representation of Itch and Pain and Their Interaction in the Primary Somatosensory Cortex

우승희,Kim Yoo Rim,Bak Myeong Seong,Chung Geehoon,Kim Sang Jeong,Kim Sun Kwang 한국뇌신경과학회 2022 Experimental Neurobiology Vol.31 No.5

Itch and pain are distinct sensations that share anatomically similar pathways: from the periphery to the brain. Over the last decades, several itchspecific neural pathways and molecular markers have been identified at the peripheral and spinal cord levels. Although the perception of sensation is ultimately generated at the brain level, how the brain separately processes the signals is unclear. The primary somatosensory cortex (S1) plays a crucial role in the perception of somatosensory information, including touch, itch, and pain. In this study, we investigated how S1 neurons represent itch and pain differently. First, we established a spontaneous itch and pain mouse model. Spontaneous itch or pain was induced by intradermal treatment with 5-HT or capsaicin on the lateral neck and confirmed by a selective increase in scratching or wiping-like behavior, respectively. Next, in vivo two-photon calcium imaging was performed in awake mice after four different treatments, including 5-HT, capsaicin, and each vehicle. By comparing the calcium activity acquired during different sessions, we distinguished the cells responsive to itch or pain sensations. Of the total responsive cells, 11% were both responsive, and their activity in the pain session was slightly higher than that in the itch session. Itch- and painpreferred cells accounted for 28.4% and 60.6%, respectively, and the preferred cells showed the lowest activity in their counter sessions. Therefore, our results suggest that S1 uses a multiplexed coding strategy to encode itch and pain, and S1 neurons represent the interaction between itch and pain.