• Membrane Journal
• /
• v.33 no.6
• /
• pp.325-343
• /
• 2023

Direct methanol fuel cells (DMFCs) have been attracting attention as energy conversion devices that can directly supply methanol liquid fuel without a fuel reforming process. The commercial polymer electrolyte membranes (PEMs) currently applied to DMFC are perfluorosulfonic acid ionomer-based PEMs, which exhibit high proton conductivity and physicochemical stability during the operation. However, problems such as high methanol permeability and environmental pollutants generated during decomposition require the development of PEMs for DMFCs using novel ionomers. Recently, studies have been reported to develop PEMs using hydrocarbon-based ionomers that exhibit low fuel permeability and high physicochemical stability. This review introduces the following studies on hydrocarbon-based PEMs for DMFC applications: 1) synthesis of grafting copolymers that exhibit distinct hydrophilic/hydrophobic phase-separated structure to improve both proton conductivity and methanol selectivity, 2) introduction of cross-linked structure during PEM fabrication to reduce the methanol permeability and improve dimensional stability, and 3) incorporation of organic/inorganic composites or reinforcing substrates to develop reinforced composite membranes showing improved PEM performances and durability.

• The korean journal of orthodontics
• /
• v.25 no.4
• /
• pp.433-445
• /
• 1995

Tooth movement, the phenomena and mechanisms of which are still controversial, can be considered as part of the result of the inflammatory processes. The purpose of this study was to examine the activity of macrophage and T-cell, playing important roles in the immune reaction, in the periodontal ligament of dog, in which experimental tooth movement was performed. Six one and half year-old dogs, a control and 5 experimentals, were studied. Light force (50-75g) was applied by placing open-coil spring between left mandibular premolars ; heavy force (250-300g), between right mandibular premolars. Experimental dogs were sacrificed at 12 hours, 1, 3, 7 and 14 days since force application, respectively. And the histologic and the immunohistochemical evaluation on the obtained tissue were performed, using $\alpha$-1-antichymotrypsin and CD3 antibodies. The results were as follows : 1. There were more inflammatory cell infiltrations in heavy force group than in light force group until 3 days. But from 7 dsays on, no difference was not observed between groups ; Such an infiltration was more evident at pressure side than at tension side. 2. Osteoclastic activity at pressure side began to be seen in 12 hours, increasing until 7 days. After then it decreased ; Such an activity was more evident in heavy force group than in light force group. 3. Tearing of periodontal ligament and vascular dilatation at tension side began to be seen in 12 hours, increasing until 3 days. After then it decreased ; Such an observation was more evident in heavy force group than in light force group, but there was no difference between groups in 14 days. 4. $\alpha$-1-antichymotrypsin expression in control group was positive, mainly in sulcular epithelium, but negative in periodontal membrane, pulp, bone cells. 5. $\alpha$-1-antichymotrypsin expression in experimental group was more positive in pressure side than in tension side ; The expression was a little more positive in cervical area of tooth until 3 days, but after 7days, it was more positive in apical area. 6. $\alpha$-1-antichymotrypsin expression in light force group began to be observed in 12 hours and reached to the greatest level in 7 days, after which it decreased ; In heavy force group, it was the greatest in 3 days, after which it decreased. 3 Expression in the periodontium was almost negative.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.32 no.4
• /
• pp.595-603
• /
• 2005

Incomplete removal of bacteria contaminated dentin or enamel associated with caries is a potential problem in restorative dentistry Secondary or residual caries, pulpal inflammation and hypersensitivity may result from bacteria left after the initial preparation, especially if an adequate seal against microleakage is not obtained. A possible solution to eliminate residual bacteria left in a cavity preparation would be to treat the cavity with cavity disinfectant wash. But a potential problem with using a cavity disinfectant with dentin bonding agents could be their interference with the ability of the resin to bond to the tooth micromechanically. The purpose of this study was to evaluate the effect of 2% chlorhexidine containing cavity disinfectant ($Consepsis^{(R)}$) on shear bond strength and microleakage of dentin bonding agents, $Adper ^{TM}$ $Scotchbond^{TM}$ Multi-Purpose, $Adper^{TM}$ Single Bond and $Adper^{TM}\;Prompt^{TM}\; L-Pop^{TM}$ Sixty and sixty sound human third molar teeth, respectively, were used for shear bond strength and microleakage test. For experimental group, cavity disinfectant was applied before dentin bonding agents, and was not applied for the control group. The result from the this study can be summarized as follows ; 1. Use of 2% chlorhexidine containing cavity disinfectant($Consepsis^{(R)}$) does not significantly affect the shear bond strength of dentin bonding agents. 2. Use of 2% chlorhexidine containing cavity disinfectant($Consepsis^{(R)}$) does not significantly affect the microleakage of dentin bonding agents.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.46 no.6
• /
• pp.75-84
• /
• 2018

The inclusive playground is a playground where disabled children and non-disabled children can play together, not a playground for the disabled. It started with the change of social awareness of the citizenship rights of disabled people in the 1960s and the resulting playgrounds. Since then, inclusive playgrounds have been developed in many countries, and these are organized in the form by guidelines. In Korea, social interest in inclusive playgrounds is increasing, but there are no systematic guidelines in Korea, and the application of overseas cases or guidelines is limited. The purpose of this study is to classify the concept of inclusive playgrounds and design guidelines, that were previously presented in inclusive playground design guideline of various countries and analyze the characteristics of, design scope, and design principles, and provide a basic framework for creating guidelines. The purpose of the design guideline was to present specific numerical values to the inclusive playground design guidelines, to link with academic research and industrial products, to present pursuit values, and to expand the value of pursuing design methods. The contents were covered by scope, conceptualization, principles of design and design process, design guidelines, and checklists. Most of the guideline covers specific autonomous governments or countries that can apply the related systems or laws, but the composition of the detailed contents is different. The guiding value of inclusive playgrounds presented in each guideline is not a playground for the disabled but a playground for all, and some guidelines refer to the difficulty in playgrounds considering non-disabled children. Based on these concepts, design guidelines are presented in each guideline. Improving the accessibility in design principles is a common theme and adds to the principles of safety, independence, convenience, and playability. None of the guidelines do not provide design guidelines. Although there is a difference in the degree and method of specificity provided by each of the guidelines, the design guidelines can be generally summarized as space, copper line, and unit facilities. As mentioned in many guidelines, an inclusive playground is not only a playground for children with disabilities. Therefore, in the design guidelines, it is also important to the support play of children with disabilities and to induce inclusive play. The design guidelines presented in the guideline can be rearranged into three stages of 'supporting the play of children with disabilities', 'securing the dimensions and materials of spaces and facilities', 'adding auxiliary devices' and 'designing new facilities'. There are three design guidelines for inducing inclusive play. First, by creating various difficulty levels and intersecting spaces, children with various abilities can play with each other, and at the same time, they can interact witheach other. Second, all children can cooperate and play without distinction between children with disabilities and non-disabled children. Finally, the guardian provides the conditions for efficient support so that the disabled child can fully enjoy the inclusive playground.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.30 no.3 s.151
• /
• pp.378-385
• /
• 2006

To release fashion trends in an efficient way, many of the apparel business and fashion educational institutes in land adopt fashion shows employing fashion models. Modeling rather than flat pattern making realizes the majority of the complicated design works for the fashion shows. However, for the different measurements between the dress form and the real human model, problems often occur during the modeling and fitting processes. Researches on the standard dress form development representing professional fashion models' features are therefore in urgent need to enable the related apparel business and fashion institutes to make appropriate use of the dress form in their jobs. The study has been conducted as a preliminary study using a questionnaire method ultimately to develop the female dress form. A questionnaire in the research aimed at an investigation into the actual conditions of and satisfaction with the usage and the body measurements of existed dress forms. Approximately 30 fashion-related educational institutes and 10 apparel companies responded to the survey. Data derived from the survey was analyzed using SPSS version 10.1, the statistics tool. The results throughout the research were discussed in terms of largely three categories that are; (1) the general conditions of the usage of the dress form to prepare fashion shows: e.g. the frequency of holding the fashion show in an annual term, the proportion of professional and amateur models employed for the fashion show, the methods to construct garments, types and number of dress forms utilized and etc.; (2) factors considered to purchase the dress form e.g. its functionality, shapes, sizes, duration, price, A/S condition and etc.; and(3) satisfaction with the similarity between the dress form and the human body in the relation to the body measurements. Measurements in length wise, front and back waist lengths, neck to bust point on the dress forms were apparently differed from the ones of the actual body. In particular, differed torso length measurements cause the problem to have to alter the whole silhouette, consequently, the resultant patterns as well. In girth measurements, in order of bust and waist girths, the satisfaction was low.

• Spatial Information Research
• /
• v.4 no.1
• /
• pp.21-42
• /
• 1996

The Anyang-cheon is one of the Han River tributaries in Seoul Metropolitan area. It is 35.1km long, has a basin area of 287km2 and touches seven cities of Kyounggi Province and part of Seoul. The purpose of this study were 1) to reconstruct the ancient stream network and to investigate the change of landuse in Anyang-cheon watershed between 1957 and 1991,2) to measure the change of the hydrologic ¬acteristics with urbanization, 3) to suggest the institutional solutions to reduce natural hazard as the area has urbanizedThe main results are as follows: 1.Anyang-cheon river basin has experienced the rapid urbanization and industrialization since 1957. Anyang-cheon stream network was oversimplified in the watershed. The total stream length decreased atributaries in the upper part of river basin have eliminated or buried undergrolmd in pipes. 2.Urbanization impacted to all of the area of Anyang-cht'On watershed. Urbanization in Anyang-cheon watershed corresponds to the large portion of flat area, especially flood - prone zone of river side, and the small portion of Greenbelt to constrain urban expantion in cities. 3.The urbanization of Anyang-cheon watershed produces fundamental changes in watershed hydrology. As infiltration is reduced by the creation of extensive pavement, concrete surface, and sewer pipe, runoff moves more quickly from upland to stream. As a result, runoff from the watershed is flashier, increasing flood hazardAs urban area continue to grow we will need to better utilize stream by protecting and enhancing stream systems.otecting and enhancing stream systems.tems.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.30 no.2
• /
• pp.196-203
• /
• 2003

The application of sealants is a highly technique-sensitive procedure, requiring an extremely dry field prior to placement. Moisture contamination of the etched enamel surface before sealant placement is cited as the main reason for sealant failure. The purpose of this study was to evaluate the effects of different methods of sealant application on the shear bond strength of sealants to enamel. In groups 1, 2, 3, 4 Teethmate(unfilled sealant) was used, while Ultraseal XTplus(filled sealant) was used in groups 5, 6, 7, 8. Groups 1 and 5(control) were acid etched for 15 seconds using 35% phosphoric acid, washed and then dried. In groups 2, 6 drying agents were applied, and in groups 3, 7 bonding agents were applied and light cured. In groups 4 and 8 both drying agent and bonding agent were applied. Then sealant was cured to the specimen using molds 3mm in diameter and 2mm in height. Thermocycling was performed and shear bond strength was finally measured. The following results were obtained : 1. Groups using filled sealant(groups 5, 6, 7, 8) showed higher shear bond strengths compared to groups using unfilled sealant(groups 1, 2, 3, 4). 2. Among groups using unfilled sealant(groups 1, 2, 3, 4), groups 2, 3, 4 showed significantly higher shear bond strength compared to group 1(p<0.05). There were no significant differences among groups 2, 3 and 4. 3. There were no significant differences(p>0.05) among groups using filled sealant(groups 5, 6, 7, 8). 4. When modes of fracture were examined, cohesive failure was observed in groups 2, 3 and 4.

• Journal of Korea Water Resources Association
• /
• v.48 no.12
• /
• pp.1065-1075
• /
• 2015

In the estuary where the structure such as river-mouth weir has been installed, the flow is developed very complicatedly due to river water from upstream, tide of the sea and floodgate operation. Especially, if basin outlets more than one exists in one estuary, the boundary conditions will be significantly more complex form. Saemangeum(SMG) project area in Korea is the most typical example. There are Mankyung river and Dongjin river in upstream. The water of them inflows into SMG project area. In the downstream, river flow was drained from inland to sea over the SMG sea dike through the sluice. The connecting channel was located between Mankyung and Dongjin basins. It functions not only as transportation by ship in ordinary period but also as flood sharing by sending flood flow to each other in flood period. Therefore, in order to secure the safety against flood, it is very important to understand the flood sharing capacity for connecting channel. In this study, the flood control effect was analyzed using numerical simulation. Delft3D was used to numerical simulation and simulated period was set up with neap tide, in which the maximum flood stage occurred due to poor drainage. Actually, three connecting channels were designed in land use plan of the SMG Master Plan, but they were simplified to a single channel for conciseness of analysis in this study. According to the results of numerical analysis, the water level difference between two basins was increased and the maximum flood stage at dike sluice was also upraised depending on decrease of conveyance. And the velocity induced by same water level difference was decreased when the conveyance became smaller. In certain conveyance above, there was almost no flood control effect. Therefore, if the results of this study are considered for design of connecting channel, it will be expected to draw the optimal conveyance for minimizing dredging construction cost while maximizing the flood control effect.

• Restorative Dentistry and Endodontics
• /
• v.27 no.2
• /
• pp.183-195
• /
• 2002

흑색 색소를 형성하는 그람음성 혐기성 세균은 급성 임상 증상을 가진 환자의 근관에서 자주 발견되는 세균으로서 세균 및 세균의 성분과 산물이 치근단 병소의 생성과 밀접하게 연관된 것으로 알려져 있다. 본 연구는 흑색 색소를 형성하는 그람음성 혐기성 세균 중 가장 발현율이 높은 Prevotella nigrescens가 배양된 세포에 미치는 세포 독성을 연구하고자 하였다. 두 가지 세포주 및 사람의 치은섬유모세포를 일차배양하여 사용하였으며, 세포주에 따른 독성 발현에 차이가 있는지를 비교하였다. P. nigrescens ATCC 33563 표준 균주 및 임상 균주로는 환자의 감염된 근관으로부터 165 rRNA primer를 사용한 중합효소 연쇄반응으로 P. nigrescens 6 균주를 동정하여 사용하였다. 세균배양액, 세균의 초음파 추출단백질 및 lipopolysaccharide (LPS)를 MC3T3-El 조골세포, NIH3T3 섬유모세포 및 치은섬유모세포에 첨가한 후 MTT분석법으로 세포의 활성을 측정하였으며, 세포의 형태학적 변화를 도립현미경으로 관찰하였다. 세균배양액을 100$\mu\textrm{l}$ 첨가한 경우는 세가지 세포주 모두에서 통계적으로 유의하게 세포의 활성을 억제하였다. 세균의 초음파 추출단백질 12.5$\mu\textrm{g}$/ml 와 25$\mu\textrm{g}$/ml 는 NIH3T3세포에 통계적으로 유의한 세포독성을 보였다. 세 가지 세포주에 대한 LPS의 세포 독성 효과는 첨가된 LPS의 농도 및 균주에 따라 다양하게 나타났다. 심하게 손상된 세포는 세포의 단일층이 수축되고 세포가 응집되었으며 세포가 배양용기의 바닥에서 떨어지는 양상이 도립 현미경하에서 관찰되었다. 본 연구의 결과 P. nigrescens가 숙주 반응을 조절하여 치수 및 치근단 병소의 유발 및 악화에 기여하는 세균으로 작용할 수 있음을 시사한다. 조직과 함께 제거하고 포르말린에서 48시간 고정시킨 후 파라핀에 포매한 다음에 micro-tome을 사용하여 6$\mu\textrm{m}$로 serial section을 시행하였다. 정중선 부위의 시편에 Hematoxylin-Eosin staining을 시행한 후 Olsson, Orstavik 그리고 Mjor 등의 방법에 따라 조직학적 변화를 관찰한 후 slight(1), moderate(2), severe inflammation(3)의 단계로 분류하였다. 얻어진 결과를 통계처리 프로그램인 Jandel사의 Sigmastat을 이용하여 Kruskal Wallis Test로 통계처리를 하였다. 결과 : (Table omitted) 결론 : 1) Pulp Canal Sealer를 제외한 모든 군에서 시간이 지남에 따라 유의성 있게 염증이 감소되는 양상을 보였다(p<0.05). 2) Pulp Canal Sealer는 1주, 2주, 12주에서 강한 염증반응을 보였다. 3) AH 26과 AH Plus에서는 1주, 2주에서 강한 염증반응을 보였으나 12주에서는 염증반응이 감소하였다. 4) 새로 개발된 봉함제 Adseal-1,2는 1주, 2주에서는 가장 약한 염증반응을 보이나 4주, 12주 후에는 AH Plus와 비슷한 수준의 염증 반응을 보였다. 5) Pulp Canal Sealer를 제외한 모든 군에서 인정할 만한 생체친화성을 보였다. 6) Adseal-2가 Adseal-1에 비하여 전반적으로 낮은 염증반응을 보였다. 7) 각 군간 결과의 차이에 통계적 유의성은 없었다(p>0.05).mmunity. Then, a hierarchical language is to defeat its own purpose.중 행정부가 북한에 대해 실시한 포용정책이 어떠한 성과를 거두고 어떠한 문제점을 간과하고 있는가에 대해 논의하고, 대북 정책의 새로운 지평을 논의하는 것을 목적으로 하고 있다. 1) 포용 정책은 세계의

• Korean Journal of Microbiology
• /
• v.42 no.3
• /
• pp.185-194
• /
• 2006

The aim of this study was to identify the bacteria isolated from endodontic lesions by cell culture and to determine the antimicrobial susceptibility of them against 8 antibiotics. The necrotic pulpal tissues were collected from 27 infected root canals, which were diagnosed as endodontic infection. Samples were collected aseptically from the infected pulpal tissue of the infected root canals using a barbed broach and a paper point. The cut barbed broaches and paper points were transferred to an eppendorf tube containing $500{\mu}l\;of\;1{\times}PBS$. The sample solution was briefly mixed and plated onto a BHI-agar plate containing 5% sheep blood. The agar plates were incubated in a $37^{\circ}C$ anaerobic chamber for 2 to 5 days. The bacteria grown on the agar plates were identified by comparison of 16S rRNA gene (rDNA) sequencing method at the species level. To test the sensitivity of the bacteria isolated from the infected root canals against 8 antibiotics, minimum inhibitory concentrations (MIC) were determined using broth dilution assay. The data showed that 101 bacterial strains were isolated and were identified. Streptococcus spp. (29.7%) and Actinomyces spp. (21.8%) were predominantly isolated. The 9 strains were excluded in antimicrobial susceptibility test because they were lost during the experiment or were not grown in broth culture. The percentage of bacteria susceptible for each antibiotic in this study was clindamycin, 87.0% (80 of 92); tetracycline, 75.0% (69 of 92); cefuroxime axetil, 75.0% (69 of 92); amoxicillin + clavulanic acid (5:1), 71.7% (66 of 92); penicillin G, 66.3% (61 of 92); erythromycin, 66.3% (61 of 92); amoxicillin, 44.6% (41 of 92); and ciprofloxacin, 31.5% (29 of 92). The susceptibility pattern of 8 antibiotics was dependent on the host of the bacteria strains rather than the kinds of bacterial species. These results indicate that antibiotic susceptibility test should be performed when antibiotics are needed for the treatment of infected root canals.