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.

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.

Effects of Cordyceps militaris Cultivated on Rice on Lipid Metabolism in Rats Fed High Fat-cholesterol Diets

박은주,Sang Mong Lee,Nam Sook Park 한국식품영양과학회 2006 Preventive Nutrition and Food Science Vol.11 No.2

Dongchunghacho rice, produced by cultivating Dongchunghacho fungus on rice, could be an effective functional food because it offers added value to rice and thus increases rice consumption. However, the physiological effect of Dongchunghacho rice has not been reported yet although there is increasing consumers demand. Therefore, we investigated the effect of Dongchunghacho rice (unpolished rice cultivated with Cordyceps militaris) on lipid metabolism in hyperlipidemic rats. Forty of 8 wk-old male Sprague-Dawley rats were divided into four groups after a 1 week of adaptation period and fed either a normal diet (66% polished rice diet, NC), high fat (12 g/100 g)-high cholesterol (1 g/100 g) diet with 53% polished rice (HC), or high fat-high cholesterol diets supplemented with 30% of the total rice as either unpolished rice (UR) or Dongchunghacho rice (DR). After 4 weeks, rats fed the Dongchunghacho rice diet with high fat and cholesterol had dramatically lower plasma LDL cholesterol concentrations and atherogenic indexes and higher plasma HDL cholesterol levels compared with the rats consuming polished rice or unpolished rice with high fat and cholesterol diet. Dongchunghacho rice led to less total lipid and total cholesterol accumulation in liver. However, these significant reductions in plasma or hepatic lipid profiles were not closely correlated with fecal total lipid or total cholesterol excretion. The plasma concentration of total cholesterol and triglycerides were not affected by Dongchunghacho rice. This hypolipidemic effect of Dongchunghacho rice seemed to be unrelated to unpolished rice itself, because the plasma and hepatic lipid profiles of UR group were not different from that of the HC group. These results suggest that unpolished rice containing cultivated Cordyceps militaris can improve plasma and hepatic lipid profiles in rats fed with high fat-high cholesterol diet.

Corrigendum: Correction of Acknowledgments

박은주,이상엽,임선주,윤소정,감비성,백선용,김윤진,우재석,이정규,정동욱,조영혜,이유현,탁영진,Park, Eun Ju,Lee, Sang Yeoup,Im, Sun Ju,Yune, So Jung,Kam, Beesung,Baek, Sun Yong,Kim, Yun-Jin,Woo, Jae Seok,Lee, Jeong-Gyu,Jeong, Dong-Wook,Cho, Yo 연세대학교 의과대학 2017 의학교육논단 Vol.19 No.2

과학 관련성 태도 변화 검사도구(CARS-Changes in Attitude about the Relevance of Science) 번역본의 타당도와 관련 변인 탐색 및 동형 검사 도구 구성

박은주,이상의,아리프 라흐마툴라흐,하민수,Park, Eunju,Lee, Sangeui,Rachmatullah, Arif,Ha, Minsu 경북대학교 과학교육연구소 2017 科學敎育硏究誌 Vol.41 No.2

이 연구의 목적은 CARS(Changes in Attitude of Relevance to Science)문항에 대한 신뢰도 및 타당도를 확인하여 우리나라 학생들에게의 적용여부를 판단하고, 성별 및 학교급별 차이를 비교한 후 라쉬 모델을 활용하여 두 개의 동형의 과학적 관련성 인식 검사도구를 구성하는 것이다. 이 연구를 위하여 59문항의 CARS 과학적 관련성 인식 검사문항을 번역하여 787명의 중 고등 (중학생 300명, 고등학생 431명의 답변이 분석됨) 학생들에게 투입하였다. CARS 문항의 우리나라 학생들에게의 적합도를 판단하고 많은 문항수의 제한점을 극복하기 위하여 라쉬 모델의 문항연결 방법을 활용하였다. 연구 결과를 분석하여 25문항으로 구성된 CARS-A와 CARS-B형의 두 과학적 관련성 인식 검사도구를 구성하였다. 두 동형검사도구의 라쉬 점수 상관관계는 0.78이며, 라쉬 모델 분석수치는 거의 일치하였다. 이 연구를 통해 생성된 두 형의 과학 관련성 인식 검사도구는 학생들의 과학의 일상관련 태도를 확인하거나, 특정 수업과정 후 또는 학년별 변화를 확인하는데 유용하게 활용될 수 있을 것이다. 이 연구를 통해 과학교육에서 학생들이 과학의 연관성 인식이 가지는 의미를 확인하고 도구개발 및 활용에 대하여 논의하고자 한다. The purpose of this study is to construct two equivalent science relevance recognition test tool after confirming the reliability and validity of the CARS(Changes in Attitude of Relevance to Science) questionnaire to determine the applicability of the items to Korean students and to compare gender and school differences. For this study, 59 items of the CARS scientific relevance test were translated and assigned to 787 middle and high school students (analyed the answer of 300 middle school students and 431 high school students). In order to determine the fit of the CARS question to Korean students and to overcome the limitation of the number of questions, we used the item-linking method of the Rasch model. By analyzing the results of the research, we constructed two equivalent scientific relevance recognition questionnaires of CARS-A and CARS-B with 25 items. The Pearson correlation coefficient of the Rasch scores of the two equivalent test was 0.78. The two types of scientific relevance recognition test tools generated through this study can be used to confirm students' attitude of scientific relevance to daily life, or to confirm the change after a certain class or grade. Through this study, we will discuss the implications of students' perceptions of science associations in science education, and the development and application of tools.

화제의 ESCO 현장을 가다-서울대학교병원

박은주,Park, Eun-Ju 에너지절약전문기업협회 2008 esco Vol.50 No.-

고온히터 솔더접합부의 신뢰성 평가 및 예측

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.

결합면 형태가 이장용 레진의 결합강도에 미치는 영향

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.

Erk AND RETINOIC ACID SIGNALING PARTICIPATE IN THE SEGREGATION AND PATTERNING OF FIRST ARCH DERIVED MAXILLA AND MANDIBLE

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.

《난경(難經)》 오사론(五邪論)을 적용한 침법(鍼法)이 2K1C 고혈압(高血壓) 백서(白鼠)의 혈압(血壓)에 미치는 영향(影響)

박은주,나창수,윤여충,조명래,Park, Eun-ju,Na, Chang-su,Yun, Yeu-chung,Cho, Myung-rae 대한침구의학회 2003 대한침구의학회지 Vol.20 No.1

Objectives : The purpose of this study is to compare Xingjian(LR2) Shaofu(HT8) with Dadun(LR1) Shaofu(HT8) on Blood Pressure in Hypertensive RAT induced by Two Kidney One Clip(2KIC). Methods : This experiments was to investigate the effects of LR2 HT8(originated from ${\ll}$Classic on Difficulty${\gg}$ Shi Ze Xie Qi Zi), LR1 HT8(originated from ${\ll}$Ling Shu${\gg}$ Sheng Ze Xie Zhi) acupuncture on the blood pressure, cardiomegalic index, and plasma levels of atrial natriuretic peptide in hypertensive rat induced by 2K1C. Results: 1. Blood pressure was decreased significantly after third acupuncture of LR2 HT8. 2. Blood pressure was decreased significantly after acupuncture of LR2 HT8, but was increased after LR2 HT8. 3. Cardiomegalic index was not changed after acupuncture of LR2-HT8 and LR1-HT8 4. Plasma levels of atrial natriuretic peptide was increased significantly after acupuncture of LR2 HT8 but LR1 HT8 was not changed.