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가스가 주입된 용기에서 기공율, 기포빈도와 온도측정에 관한 연구
박설현,오율권,서동표 朝鮮大學校 機械技術硏究所 1999 機械技術硏究 Vol.2 No.2
The local phase volume fraction, bubble frequency and the phase temperature distributions were measured in vertical air injected water baths. An electroresistivity probe was employed for the determination of the local void fraction and bubble arrival frequency. The phase resolved temperatures were measured using a microthermocouple. The thermocouple signals were digitally filtered, and were carried out to characterize the overall structure of the gas-liquid plume and the heat transfer mechanism between the phases.
박설현,정대훈,오율권 조선대학교 에너지.자원신기술연구소 2001 에너지·자원신기술연구소 논문지 Vol.23 No.1
Solid-liquid phase change (i.e. melting or solidification) occurs in a number of situations of practical interest. Some common examples include the melting of edible oil. metallurgical process such as casting and welding, and materials science applications such as crystal growth. Therefore, due to the practical importance of the subject, there have been a large number of experimental and numerical studies of problems involving phase change during the past few decades. This study presents experimental work on phase change heat transfer. Especially, in order to increase heat transfer rate. ultrasonic vibrations were introduced. The melting cavity contained one vertical heating surface which dissipates heat at constant power and was insulated on the sides. Experimental observations show that the effect of ultrasonic vibrations on heat transfer is very important throughout melting process. The results of this study reveal that ultrasonic vibrations accompany the effects like agitation, acoustic streaming, cavitation, and oscillating fluid motion. Such effects are a prime mechanism in the overall melting process when ultrasonic vibrations are applied. They speed up the melting process as much as 2.5 times, compared with the result of natural melting. Also, energy can be saved by applying ultrasonic vibrations to the natural melting.
박설현,윤정환,서동표,정대훈,오율권 朝鮮大學校 機械技術硏究所 2000 機械技術硏究 Vol.3 No.1
Polymer drag reduction can offer a attractive way to utilize ready-made facilities in crude-oil transport system without additional large expenditure. Also, drag reduction in two phase flow can be applied to phase change system such as chemical reactor, pool and pump impeller which occurs cavitation. But the research on drag reduction in two phase flow has not been investigated. Therefore, experimental investigations have been carried out to analyze the drag reduction in the single phase and two phase flow. The objectives of the proposed investigation are primarily to identify and develop high performance polymer additives for fluid transportation. And drag reduction will be evaluated in horizontal flow by measuring void fraction, pressure drop, mean liquid velocity and turbulent intensity
Distribution of the Fairy Pitta (Pitta nympha) in the South Korea: A focus on protected areas
Gil-Pyo Hong(홍길표),Jae-Hoon Kim(김재훈),Seul-Gi Seo(서슬기),So-Yeon Cho(조소연),Bo-Yeon Hwang(황보연),Jong-Hyun Park(박종현),Seung-Yeon Lee(이승연),Ga-Young Kim(김가영),Wan-Hee Nam(남완희),Ha-Cheol Sung(성하철) 한국조류학회 2021 한국조류학회지 Vol.28 No.2
국내 팔색조(Pitta nympha) 분포 현황을 알아보고자 전국 국립공원 등 보호지역 중심으로 총 19개 지역을 조사하였고, 전문가 네트워크를 통해 자료를 보강하였다. 전국 19개 지역을 조사한 결과 북한산, 지리산 등 내륙지역 7개 국립공원에서는 팔색조가 확인되지 않았고, 경남 거제, 남해, 해남, 장흥 고흥 등 남해안과 인접한 12개 지역에서 팔색조 서식이 확인되었다. 또한 전문가 네트워크를 통해 수집한 팔색조 출현 위치 정보 82건을 분석한 결과, 전국 8개 광역지자체 모두 팔색조 서식이 확인되었고, 내륙지역(26.8%)보다 해안지역(73.2%)에서 더 많이 출현하였다. 연구 결과를 종합해보면, 우리나라의 팔색조는 주로 제주도와 남해안 지역을 중심으로 많이 분포하며, 그 보다 적은 개체수가 내륙 지역에 넓게 분포하고 있는 것으로 나타났다. The present study investigated the current distribution of Fairy Pitta (Pitta nympha) in South Korea. A total of 19 study areas, including protected areas such as national and provincial parks in South Korea were surveyed, and additional data obtained from an expert network. According to the results, Fairy Pitta was absent in seven inland national parks, including Mt. Bukhan and Chiri parks. Fairy Pitta inhabited 12 areas near the southern coast of South Korea, including Geoje, Namhae, Haenam, Jangheung, Goheung, and Gyeongnam Province. The analysis results of 82 datasets obtained from experts with regard to the locations where Fairy Pitta have been spotted showed that the bird inhabits all the eight metropolitan regions in South Korea, and is more frequently spotted in coastal areas (73.2%) than in inland areas (26.8%). The findings demonstrate that Fairy Pitta is mainly distributed in Jeju Island and the southern coast of South Korea, and is distributed in inland areas at relatively lower numbers.
Annealed Au-Assisted Epitaxial Growth of Si Nanowires: Control of Alignment and Density
Park, Yi-Seul,Jung, Da Hee,Kim, Hyun Ji,Lee, Jin Seok American Chemical Society 2015 Langmuir Vol.31 No.14
<P>The epitaxial growth of 1D nanostructures is of particular interest for future nanoelectronic devices such as vertical field-effect transistors because it directly influences transistor densities and 3D logic or memory architectures. Silicon nanowires (SiNWs) are a particularly important 1D nanomaterial because they possess excellent electronic and optical properties. What is more, the scalable fabrication of vertically aligned SiNW arrays presents an opportunity for improved device applications if suitable properties can be achieved through controlling the alignment and density of SiNWs, yet this is something that has not been reported in the case of SiNWs synthesized from Au films. This work therefore explores the controllable synthesis of vertically aligned SiNWs through the introduction of an annealing process prior to growth via a Au-catalyzed vapor–liquid–solid mechanism. The epitaxial growth of SiNWs was demonstrated to be achievable using SiCl<SUB>4</SUB> as the Si precursor in chemical vapor deposition, whereas the alignment and density of the SiNWs could be controlled by manipulating the annealing time during the formation of Au nanoparticles (AuNPs) from Au films. During the annealing process, gold silicide was observed to form on the interface of the liquid-phase AuNPs, depending on the size of the AuNPs and the annealing time. This work therefore makes a valuable contribution to improving nanowire-based engineering by controlling its alignment and density as well as providing greater insight into the epitaxial growth of 1D nanostructures.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/langd5/2015/langd5.2015.31.issue-14/la503453b/production/images/medium/la-2014-03453b_0008.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/la503453b'>ACS Electronic Supporting Info</A></P>
Park, Hyeoun-Ae,Lee, Joo Yun,On, Jeongah,Lee, Ji Hyun,Jung, Hyesil,Park, Seul Ki Korean Society of Medical Informatics 2017 Healthcare Informatics Research Vol.23 No.2
<P><B>Objectives</B></P><P>The objective of this study was to review and visualize the medical informatics field over the previous 12 months according to the frequencies of keywords and topics in papers published in the top four journals in the field and in <I>Healthcare Informatics Research (HIR)</I>, an official journal of the Korean Society of Medical Informatics.</P><P><B>Methods</B></P><P>A six-person team conducted an extensive review of the literature on clinical and consumer informatics. The literature was searched using keywords employed in the American Medical Informatics Association year-in-review process and organized into 14 topics used in that process. Data were analyzed using word clouds, social network analysis, and association rules.</P><P><B>Results</B></P><P>The literature search yielded 370 references and 1,123 unique keywords. ‘Electronic Health Record’ (EHR) (78.6%) was the most frequently appearing keyword in the articles published in the five studied journals, followed by ‘telemedicine’ (2.1%). EHR (37.6%) was also the most frequently studied topic area, followed by clinical informatics (12.0%). However, ‘telemedicine’ (17.0%) was the most frequently appearing keyword in articles published in <I>HIR</I>, followed by ‘telecommunications’ (4.5%). Telemedicine (47.1%) was the most frequently studied topic area, followed by EHR (14.7%).</P><P><B>Conclusions</B></P><P>The study findings reflect the Korean government's efforts to introduce telemedicine into the Korean healthcare system and reactions to this from the stakeholders associated with telemedicine.</P>
Park, Gyeong Jin,Na, Yu Jeong,Jo, Hyun Yong,Lee, Seul Ah,Kim, Ah Ram,Noh, Insup,Kim, Cheal The Royal Society of Chemistry 2014 NEW JOURNAL OF CHEMISTRY Vol.38 No.6
<P>A new highly selective and sensitive chemosensor <B>1</B> for both Zn<SUP>2+</SUP> and OAc<SUP>−</SUP> with off–on fluorescence behavior in aqueous solution was developed. The selectivity mechanism of <B>1</B> for zinc is based on a combinational effect of the inhibition of excited-state intramolecular proton transfer and C&z.dbd;N isomerization, and chelation-enhanced fluorescence. As a practical application, <I>in vitro</I> studies with fibroblasts showed fluorescence in the presence of both the receptor <B>1</B> and Zn<SUP>2+</SUP>. Moreover, the deprotonated <B>1</B> can behave as a chemosensing system for turn-on detection of OAc<SUP>−</SUP> in preference over various other anions tested. Therefore, <B>1</B> can serve as ‘one sensor for multiple analytes’.</P> <P>Graphic Abstract</P><P>A single fluorescent chemosensor <B>1</B> for multiple analytes (Zn<SUP>2+</SUP> and OAc<SUP>−</SUP>) has been developed and it can monitor Zn<SUP>2+</SUP> ions in living cells. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c4nj00191e'> </P>
Effect of strain relaxation in InGaN/GaN multi-quantum wells with self-assembled Pt nanoclusters.
Park, Ah Hyun,Oh, Tae Su,Seo, Tae Hoon,Lee, Seul Be,Lee, Gun Hee,Suh, Eun-Kyung American Scientific Publishers 2014 Journal of nanoscience and nanotechnology Vol.14 No.11
<P>We report effect of the strain relaxation in InGaN/GaN multi-quantum well (MQW) structures grown on platinum nanocluster-coated sapphire substrate (PNSS) by metal organic chemical vapor deposition. The photoluminescence (PL) intensity of InGaN/GaN MQWs on PNSS was significantly enhanced compared to that of the InGaN/GaN MQWs on flat sapphire substrate due to the reduction of defect density and residual strain by self-assembled Pt nanoclusters. We confirmed the reduction of strain-induced piezoelectric field by the power dependence of the PL in InGaN/GaN MQWs on PNSS. Cathodoluminescence shows that a large bright area with overall strong peak intensity is attributed to the suppression of In inhomogeneity and strain relaxation in InGaN/GaN MQWs on PNSS. Based on these results, we suggest that the self-assembled Pt nanocluster can be applied to increase the quantum efficiency through improved crystal quality and internal strain relaxation in MQWs.</P>