HVOF와 LPPS로 제조된 단층 열차폐 코팅의 고온 물성에 관한 연구

남영민,송요승 한국 항공대학교 항공산업기술연구소 2000 航空宇宙産業技術硏究所 硏究誌 Vol.10 No.-

본 연구에서는 HVOF법과 LPPS법으로 제조된 CoNiCrAlY 단층 열차폐 코팅의 미세구조 분석, 고온산화시험, 그리고 열피로시험 등 종합적인 기계적, 열적 물성을 평가하였다. HVOF법과 LPPS법으로 제조된 피막의 두께는 각각 450∼500μm, 350∼450μm 정도였으며 경도는 각각 350Hv∼400Hv, 370Hv∼420Hv의 분포를 보였고 모재와 코팅층의 경계가 확실히 구분되지 않았다. 단면 관찰결과 두 피막 모두에서 열처리에 의한 확산의 영향으로 Al-rich 상이 나타났으며 코팅층 표면은 β상과 γ상으로 이루어져 있었다. 또한 기공도는 1∼2%정도를 나타내었으며 LPPS 시편에서 더 낮은 기공도를 유지하였다. 고온산화시험에서는 코팅층 표면에 10∼20μm 정도의 두께를 가진 oxide scale이 형성되었으며 산화하기 전에 보이는 Al-rich 상들이 점차적으로 사라지는 것이 발견되었다. 열피로시험 결과 표면과 계면부위에 커다란 기공이 형성되었으며 LPPS 시편이 HVOF 시편보다 더 나은 내열피로 특성을 나타내었다. In this study the evaluations of mechanical and thermal properties of FGM-TBC such as oxidation and fatigue at high temperatures have been conducted. The samples of bond coat produced by High Velocity Oxygen Fuel (HVOF) and Low Pressure Plasma Spray (LPPS) method were used. The thickness values of HVOF coating was about 450μm to 500μm and the hardness of coating was about 350Hv to 400Hv. The thickness values of LPPS coating was about 350μm to 450μm and the hardness number of coating was about 370Hv to 420Hv. The XRD analyzes showed that CoNiCrAlY coating layer of HVOF and LPPS was composed of β and γ phase after spraying. The cross sectional image showed Al-rich phase which was influenced by diffusion. After high temperature oxidation test of HVOF and LPPS, the oxide scale with about 10μm to 20μm thickness at coating surface was appeared and under the oxide scale layer the Al-depleted zone was observed. And, Al-rich phase which showed before oxidation test disappeared gradually. After thermal fatigue test of HVOF and LPPS, coarse pores were observed at the surface and interface area. The thermal fatigue resistance of LPPS coating is better than those of HVOF coating.

Thermoluminescent Response of Thin LiF:Mg,Cu,Na,Si Detectors to Beta Radiation

Cho,H.W.,Chang,S.Y.,Nam,Y.M.,Kim,J.L.,Kim,H.J. 대한방사선 방어학회 1999 방사선방어학회지 Vol.24 No.1

최근 개발된 감도가 좋은 LiF:Mg,Cu,Na,Si TL물질을 Teflon과 혼합한 후, 얇은 디스크 형태로 압축·성형한 얇은 LiF:Mg,Cu,Na,Si Teflon 검출기를 제작하고 베타선 검출기로서의 TL 반응특성을 연구하였다. 한국원자력연구소의 Pm, Tl 및 Sr/Y 베타선원을 이용하여 두께 2 ㎎/㎠인 kapton 박막을 덮은 상태로 베타선을 조사하였다. 제작한 얇은 LiF:Mg,Cu,Na,Si 검출기들의 Cs에 대한 batch 균질성은 4.7%, 베타선에 대한 선량의존성은 0.1 m㏉에서 100 ㏉까지 선형성을 나타내고, 에너지의존성은 Pm, Tl 및 Sr/Y 베타선에 대해 각각 0.46, 1.09 및 1.06 이었다. 그리고 베타선에 대한 방향의존성은 0.93±0.03 (Pm), 0.94±0.04 (Tl) 및 0.92±0.05 (Sr/Y)으로, 이들 얇은 LiF:Mg,Cu,Na,Si 검출기들에 대한 Tl 반응특성의 결과는 국제표준기구(ISO)의 베타선량계 기준을 잘 만족하였다. Thermoluminescent (TL) response characteristics of a thin LiF:Mg,Cu,Na,Si Teflon detectors have been studied for use in beta radiation detection. The detectors were fabricated from a mixture of LiF:Mg,Cu,Na,Siphosphor and Teflon powder which was molded into a thin disk form of 50 ㎎/㎠ These detectors were irradiated to beta fields of Pm, Tl and Sr/Y sources with a covering of Kapton foil (2 ㎎/㎠) and photon irradiation was carried out with a Cs source at the Korea Atomic Energy Research Institute (KAERI). Batch uniformity was estimated to be 4.7% and the beta dose response presented linear relationship from 0.1 m㏉ to 100 ㏉. The beta energy responses of thin detectors normalized to Cs were presented as 0.46, 1.09 and 1.06 for Pm, Tl and Sr/Y beta rays, respectively. The evaluated values for angular responses were 0.93±0.03 (Pm), 0.94±0.04 (Tl), and 0.92±0.05 (Sr/Y). The results satisfied well a proposed ISO Standard for beta ray dosimeters.

BELLE TOF 검출기의 특성 연구

남지우,김동욱,배미영,박강순,김정현,노상률,최영일,김희종,장동욱,최소명,권영준,Hikita, S.,Yu, C.,Yoshimura, Y.,Kichimi, H. 성균관대학교 기초과학연구소 1998 論文集 Vol.49 No.-

We investigated the properties of BELLE Time Of Flight(TOF) counter using the data taken in Jan 98 beam test at Pi2 beam line at KEK 12 GeV proton synchrotron. Charge distributions from readout PMT were analysed in comparison with dE/dx distributions predicted by GEANT full simulation. Experimental setup of the beam test is described, then procedures of data analysis, Monte Carlo simulation and analysis results are also described.

대학생의 스마트폰 중독, 불안 및 수면의 질에 대한 연구

김민지,염영은,전지은,조현정,최수민,계향미,김가현,남은재,박신영,박지영 이화여자대학교 간호과학대학 2014 이화간호학회지 Vol.- No.48

Purpose: The purpose of this study was to learn about smartphone addiction level, anxiety, and sleep quality among undergraduate students. Method: In this cross-sectional design study, a convenient sample of 231 undergraduate students were recruited between August and September, 2013. Questionnaires used for this study were the Smartphone addiction proneness scale for adults, the STAI (State-Trait Anxiety Inventory), and the PSQI (Pittsburgh Sleep Quality Index). Data were statistically analyzed using descriptive statistics, t-test, Pearson’s correlation, and ANOVA. Result: About 44 percent of the participants used smartphones in order to communicate with others; SNS (Social Network Service) was the most frequently used function among participants. 59 participants (25.5%) were smartphone addiction potentially risk group and 22 participants (9.5%) were high-risk group. Sex and amount of time used per day had significant influences on smarphone addiction score. There were statistically significant relationships among smartphone addiction level, anxiety, and quality of sleep. The smartphone addiction high-risk group had significantly higher trait anxiety scores compared to the normal group. Conclusion: Smartphone addiction was a risk factor for both anxiety and quality of sleep among undergraduate students. The proposals of this study are as follows: first, in-depth studies are required with regard to the intervention for high frequency of smartphone use and the influence of smartphone addiction as a risk factor of anxiety and mental health. Second, a smartphone addiction treatment program should be supplemented as one of the interventions for anxiety. Third, as an intervention for sleep quality, not only should sleep patterns be considered, but one’s behaviors or habits should be taken into account, particularly at the level of smartphone addiction and anxiety.

Mirror pattern of cerebral artery atherosclerosis in patients with ischaemic stroke

Kim, Y. D.,Choi, H. Y.,Jung, Y. H.,Nam, C. M.,Yang, J. H.,Cho, H. J.,Nam, H. S.,Lee, K-Y.,Heo, J. H. Blackwell Publishing Ltd 2009 European Journal of Neurology Vol.16 No.10

<P>Background and purpose: </P><P>Although it has been suggested that bilateral symmetry of atherosclerosis can be found in paired arteries, including external carotid arteries and femoral arteries, it has remained unknown in intracranial arteries. We determined whether bilateral symmetry (a mirror pattern) of atherosclerosis presents in the entire cerebral arterial system.</P><P>Methods: </P><P>Angiographic findings of 795 consecutive patients with ischaemic stroke, after excluding those with cardiac sources of embolism or other causes of stroke, were reviewed retrospectively. The presence (location) and severity (the degree of stenosis) of atherosclerosis were compared between left and right sides at 26 predetermined arteries/segments.</P><P>Results: </P><P>We found 2230 lesions in predetermined segments/arteries from 669 patients. Amongst 509 patients with atherosclerotic lesions at two or more arteries/segments, mirror patterns were observed in 312 patients (61.3%). The mirror pattern increased steeply as the number of atherosclerotic arteries increased and was most frequently found in the carotid bulb (C1, 26.7%), followed by the middle cerebral artery (M1, 14.1%). The severity of stenosis was also correlated between left and right sides, and the correlation was highest in the C1 (<I>r</I> = 0.40, <I>P </I>< 0.001). Multiple logistic regression analyses revealed that the mirror patterns of atherosclerosis were more obvious in C1 and associated with a past history of ischaemic stroke and the number of stenotic lesions.</P><P>Conclusion: </P><P>Atherosclerosis in cerebral arteries may develop and progress in a mirror pattern. In patients with cerebral artery atherosclerosis, the occurrence and progression of atherosclerosis in the contralateral cerebral artery should be considered during follow-up examination.</P>

Investigating the influence of organic matter composition on biofilm volumes in reverse osmosis using optical coherence tomography

Park, S.,Nam, T.,Park, J.,Kim, S.,Ahn, Y.,Lee, S.,Kim, Y.M.,Jung, W.,Cho, K.H. Elsevier Scientific Pub. Co 2017 Desalination Vol. No.

Biofouling, a critical issue in membrane filtration, is influenced by several factors such as membrane characteristics and feed water quality. The organic matter (OM) composition is known to significantly influence biofilm formation, but few studies on this subject have been reported. Optical coherence tomography (OCT) allows direct monitoring of biofilm development on the membrane surface without the need for membrane autopsy. The purposes of the present study are 1) to quantify biofouling formation on a membrane surface using OCT; 2) to monitor the temporal variation of OM composition during membrane formation; and 3) to investigate the variation of OM composition. Substantial variations in thickness was observed from OCT images. It demonstrates that biovolume quantified from a single 2D cross-sectional image could result in inaccurate quantification. Here, we quantified foulants on the membrane surface using 3D images and validated the results using confocal laser scanning microscopy (CLSM). As well, variations in the OM composition driven by bacterial activity were observed by fluorescence excitation-emission matrix analysis and size exclusion chromatography. The biovolume estimated by the OCT system was 103.7μm<SUP>3</SUP>/μm<SUP>2</SUP>. CLSM demonstrated that 10% of the foulants on the membrane surface was composed of live and dead bacteria.

방사선조사와 NSAID에 의한 유전자 발현의 차이에 관한 연구

설지연,김계영,남명진 국립보건연구원 2000 국립보건원보 Vol.37 No.-

20대 여성의 데이트폭력 피해 경험과 우울, 불안 및 신체화의 관계

김수민,김예진,김유정,남지현,박금빈,박이준,안혜민,오세연,유가현,유다현,전예지,김옥수,길민지 이화여자대학교간호학회 2020 이화간호학회지 Vol.- No.54

Purpose: The purpose of this study is to examine the degree of date violence damage, depression, anxiety, and somatization among women in their 20s who had experienced date violence, and to investigate the correlations b etween the subjects’ experience of date violence damage and depression, anxiety and somatization. Method: The subject of this study were collected from September 04 to October 13, 2019, by posting advertisements on the women’s university community site in Seoul and a representative women;s community site on the Internet. 149 subjects were collected in their 20s who had experienced date violence from their partners. SPSS statistics 22.0 statistical program was used for data analysis, and standard deviation, T-test, ANOVA, and Pearson’s correlation coefficients were performed. Result: The results showed that the degree of experience of date violence was significantly correlated with symptoms of depression, anxiety, and somatization. Conclusion: Since there was correlations b etween depression, anxiety, and somatization symptoms in date violence victims, it is necessary to apply nursing intervention related to depression and anxiety to prevent somatization symptoms caused by date violence.

한국 소재 대학교에 재학 중인 재외국민대학생의 문화지능과 학습참여도가 우울에 미치는 영향

강보미,강유빈,고미영,김찬송,남의정,박소은,박정연,백도윤,이혜린,한보혜,신주현,손지희 이화여자대학교 간호과학대학 2019 이화간호학회지 Vol.- No.53

Purpose: This study aims to identify the impact that cultural intelligence and learning engagement of Korean overseas students in Korea have in depression, also, to propose direction for further research, and to suggest a nursing intervention program that aims to the reduction of depression in overseas students. Methods:. The selected participants of the present study were Korean Overseas University Students enrolled in a special admission for overseas students. Data were obtained through the use of SPSS Window 25 and analyzed using descriptive statistics, t-test, ANOVA, Scheffe test, Pearsons correlation coefficient, and multiple linear regression analysis. Results: Depression in Korean overseas university students is influenced by the education system(ß=-.193, p=.046) and continent of residency(ß=0.197, p=.03). It is necessary to take into account the differences of education systems as well as the cultural differences from where they come from for the purpose of reducing depression rates in overseas Koreans. Conclusion: The results of this study show that depression in Korean overseas students is related to the differences in continents of residency and the education systems. Consequently, the development and implementation of a nursing intervention program considering both factors, the continent and education system, has become a necessity that relates to the reduction of depression in Korean overseas students.

유전자치료 효율향상을 위한 세포특이적 Vector의 개발

김계영,남명진,유천권,진동훈,백묘아,박만석,심수경,이혜경,이병철,박미연 국립보건연구원 2000 국립보건원보 Vol.37 No.-