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플라스틱 광섬유용 클래드 재료 개발 - PMMA/THV 블렌드의 상용성과 계면 접착력 -
박은주,박인철,이무성,박민,Park, Eun-Ju,Park, In-Cheol,Lee, Moo-Sung,Park, Min 한국섬유공학회 2008 한국섬유공학회지 Vol.45 No.6
We investigated the miscibility of poly(methyl methacrylate) (PMMA) and random copolymers of tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride (THV) blends and their interfacial adhesion as part of the development of cladding materials for PMMA based plastic optical fiber. Three different types of THV with different copolymer composition were used as candidates for them. PMMA/THV blends being melt-mixed at $240^{\circ}C$ showed typical immiscible morphology and the glass transition temperatures of the component polymers did not change after mixing. However, tie chains connecting matrix and dispersed phase were identified when THV with high content of vinylidene fluoride, i.e., THV220 was used. In spite of the intrinsic immiscibility of PMMA/THV blends the interfacial adhesion obtained from peel test was above $10^4N/m^2$ at the adhesion temperature of $240^{\circ}C$ and increased with increasing the temperature for THV220. From the melt viscosity data of the polymers it was recommended that the extrusion temperature of THV should be higher than that of PMMA in order to obtain smooth interface between core and cladding layer.
경기 일부지역 초등학교에서 담임교사의 영양교육 실시와 3~6학년생의 식생활지침 준수 정도
박은주,강현주,송경희,박경애,이홍미,Park, Eunjoo,Kang, Hyunjoo,Song, Kyung Hee,Park, Kyung Ae,Lee, Hongmie 대한영양사협회 2020 대한영양사협회 학술지 Vol.26 No.2
Homeroom teachers are not usually nutrition professionals, but they spend a lot of time with students in elementary school classrooms. This study was conducted to determine the association of homeroom teachers' nutrition education with the dietary habits of their classroom children. The subjects were 131 homeroom teachers and their 1,102 children from 17 elementary schools in Gyeonggi, Korea. Self-administered questionnaires to collect information on dietary habits were conducted in December 2016. The dietary habits were determined with the adherences to the Dietary Guidelines for Adults and Children, respectively, by coding the better diet life with a higher score. The significances between groups according to teachers' implementation of nutrition education (106 implemented, 25 not implemented) were analyzed by using SPSS at P<0.05. Implementing nutrition education was not associated with the dietary habits of teachers themselves, but their students. Therefore, the students of teachers who implemented nutrition education had significantly higher adherence to 8 items out of 19 items (P<0.05, P<0.01). More of the students considered themselves as non-picky eaters (P<0.05), tried to eat all the foods served at school lunch even when it contained unwanted ingredients (P<0.01), and agreed on the need of nutrition education (P<0.01), as compared to their counterparts. Conclusively, this study suggests that nutrition education delivered by homeroom teachers may be associated with more desirable dietary habits of students, even though homeroom teachers are not nutrition professionals. Therefore, efforts should be undertaken to develop and provide proper contents for homeroom teachers to use in nutrition education for elementary students.
고내열 POF용 클래딩 재료 제조 (II) -Methacrylic Acid 공단량체 첨가 효과-
박은주,정민진,김진봉,이무성,박민,Park, Eun-Ju,Jung, Min-Jin,Kim, Jin-Bong,Lee, Moo-Sung,Park, Min 한국섬유공학회 2004 한국섬유공학회지 Vol.41 No.2
We introduced methacrylic acid (MAA) into 80/20 trifluoroethyl methacrylate (TFEMA)-methyl methacrylate (MMA) copolymer in order to prepare heat-resistant cladding materials for plastic optical fiber based on poly(methyl methacrylate) (PMMA). As the content of MAA in the terpolymers increases, their T$_{g}$s increase to be higher values than those predicted by the Fox equation. Moreover, the interfacial adhesion between PMMA and the terpolymers, evaluated from the cross cut tape test, also increases from 1B to 4B classification. The results show that the MAA units, introduced in order to induce a specific intermolecular interaction, effectively contribute to increase the interfacial adhesion with PMMA as well as the thermal stability of the resultant copolymers.s.
박은주,Park, Eun-Ju 에너지절약전문기업협회 2007 esco Vol.48 No.-
김해시가 장유면 '장유쓰레기소각장'의 열병합발전시설을 ESCO사업으로 진행, 연간 6억원의 예산절감을 할 것으로 보여 주목된다. 특히 이 시설은 전력과 온수를 동시에 생산하게 되어 고유가시대에 에너지 이용 효율을 높이고, 에너지비용을 절감할 수 있는 이점 때문에 앞으로 각 지방자치단체에 그 파급효과가 클 것으로 기대되고 있다.
유체 내 전기선폭발법에 의한 은 나노입자 유체의 제조 및 특성
박은주,김지순,권영순,김진천,최혜선,정용훈,Park, E.J.,Bac, L.H.,Kim, J.S.,Kwon, Y.S.,Kim, J.C.,Choi, H.S.,Chung, Y.H. 한국분말야금학회 2009 한국분말재료학회지 (KPMI) Vol.16 No.3
This paper presents a novel single-step method to prepare the Ag nanometallic particle dispersed fluid (nanofluid) by electrical explosion of wire in liquid, deionized water (DI water). X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM) and transmission electron microscope (TEM) were used to investigate the characteristics of the Ag nanofluids. Zeta potential was also used to measure the dispersion properties of the as-prepared Ag nanofluid. Pure Ag phase was detected in the nanofluids using water. FE-SEM analysis shows that the size of the particles formed in DI water was about 88 nm and Zeta potential value was about -43.68 without any physical and chemical treatments. Thermal conductivity of the as-prepared Ag particle dispersed nanofluid shows much higher value than that of pure DI water.
박은주,탁혜진,박은하,백정미,이상휘,Park, Eun-Ju,Tak, Hye-Jin,Park, Eun-Ha,Baik, Jeong-Mi,Zhengguo, Piao,Lee, Sang-Hwy Korean Association of Maxillofacial Plastic and Re 2009 Maxillofacial Plastic Reconstructive Surgery Vol.31 No.2
In vertebrates, the face is mainly formed with neural crest derived neural crest cells by the inherent programs and the interactive environmental factors. Extracellular signaling-regulated kinase (Erk) is one of such programs to regulate the various cellular functions. And retinoic acid (RA) also plays an important role as a regulator in differentiation process at various stages of vertebrate embryogenesis. We wanted to know that the segregation as well as the patterning of maxillary and mandibular structure is greatly influenced by the maxillomandibular cleft (MMC) and the failure of this development may result in the maxillomandibular fusion (syngnathia) or other patterning related disorder. It has been well documented that the epithelium at this cleft region has significant expression of Fibroblast growth factor (Fgf) 8, and it is essential for the patterning of the first arch derived structures. By the morphological, skeletal, cell proliferation and apoptotic, and hybridization analysis, we checked the effects of Erk inhibition and/or RA activation onto MMC and could observe that Erk and RA signaling is individually and synergically involved in the facial patterning in terms of FGF signaling pathway via Barx-l. So RA and Erk signaling work together for the MMC patterning and the segregation of maxilla-mandible by controlling the Fgf-related signaling pathways. And the abnormality in MMC brought by aberrant Fgf signaling may result in the disturbances of maxillary-mandibular segregation.
박은주,진태호,Park Eun-Ju,Jin Tai-Ho 대한치과보철학회 2004 대한치과보철학회지 Vol.42 No.2
Statement of problem: Removable partial denture and complete denture often require denture base relines to improve the fit against the tissue-bearing mucosa because of gradual changes in edentulous ridge contours and resorption of underlying bone structure. Purpose: This study was performed to investigate the effect of surface design on bond strength of relining denture base resins to denture base acrylic resin. Materials and method: Heat curing resin(Lucitone 199, Dentsply U.S.A. and Vertex, Dentimex, Holland), self curing resin(Tokuso rebase, Tokuyama, Japan), and visible light curing resin(Triad, Dentsply, U.S.A.) were used in this study. The surface designs were classified as butt, bevel and rabbet joint and the bond strengths were measured by Universial Testing Machine (Zwick 2020, Zwick Co., Germany). Results and Conclusion: The obtained results from this study were as follows ; 1. The bond strength of Vertex resin was higher than those of Tokuso rebase and Triad. 2. The bond strength of rabbet and bevel joint was higher than that of butt joint. 3. The failure mode of Triad and Tokuso rebase was mainly adhesive, but cohesive failure was shown mainly in vertex.
박은주,권대일,사윤기,Park, Eunju,Kwon, Daeil,Sa, Yoonki 한국마이크로전자및패키징학회 2017 마이크로전자 및 패키징학회지 Vol.24 No.2
본 논문에서는 고온히터의 주 고장 원인이 되는 단자대 솔더 접합부의 손상 원인을 파악하여 사용 수명을 예측하는 방법을 제시하였다. 고온 히터 사용에 따르는 온도 스트레스로 인한 단자대 솔더 접합부의 영향을 알아보기 위해 동일한 부하 조건을 재현할 수 있는 고온히터 시편을 제작하였다. 고온히터 단자대의 단락은 주로 솔더접합부 내의 금속간 화합물이나 void로 인한 crack발생에서 기인한다. 가속시험을 통한 고장 재현을 위해 고온히터 시편을 $170^{\circ}C$의 오븐에서 장시간 동안 노출시키며 솔더 내부의 금속간 화합물 조성과 void의 변화를 측정하였다. 솔더 내의 금속간 화합물 층의 변화를 확인하기 위해서 주사전자현미경을 이용한 단면 분석을 시행하였고, 시편의 온도 스트레스로 인한 void 변화를 측정하기 위해 저항분광법을 이용한 특정 기준 주파수와 위상에 대한 신호를 실시간으로 측정하는 동시에 microCT를 이용하여 void 분율을 간헐적으로 관찰하였다. 시험결과 고온 노출 시간이 증가함에 따라 솔더 내부의 void의 분율이 증가하는 것을 확인하였으며 위상차 변화와 높은 상관관계가 있음을 확인하였다. 이 상관관계를 통해 온도 스트레스에 노출된 고온히터의 수명을 비파괴적으로 예측할 수 있음을 제시하였다. This paper proposes an approach to predict the reliability of high temperature heaters by identifying their primary failure modes and mechanisms in the field. Test specimens were designed to have the equivalent stress conditions with the high temperature heaters in the field in order to examine the effect of stress conditions on the solder joint failures. There failures often result from cracking due to intermetallic compound (IMC) or void formation within a solder joint. Aging tests have been performed by exposing the test specimens to a temperature of $170^{\circ}C$ in order to reproduce solder joint failures in the field. During the test, changes in IMC formation were investigated by scanning electron microscopy (SEM) on the cross-sections of the test specimens, while changes in void formation were monitored both by resistance spectroscopy and by micro-computed tomography (microCT), alternately. The test results demonstrated the void volume within the solder increased as the time at the high temperature increased. Also, the phase shift of high frequency resistance was found to have high correlation with the void volume. These results implied the failure of high temperature heaters can be non-destructively predicted based on the correlation.