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정순용(Soon-Yong Jeong),김철웅(Chul-Ung Kim),정광은(Kwang-Eun Jeong),고재천(Jae-Cheon Koh),채호정(Ho-Jeong Chae),김태완(Tae-wan Kim),박현주(Hyunjoo Park),이상봉(Sang-Bong Lee),한정식(Jeongsik Han),정병훈(Byunghun Jeong) 한국추진공학회 2010 한국추진공학회 학술대회논문집 Vol.2010 No.11
석유대체자원을 이용하여 항공유의 제조기술 연구를 수행하고 있는데, 핵심 연구분야인 크게 3분야로 바이오매스, 석탄, 천연가스등으로부터 얻어진 합성가스를 제조하기 위한 전처리 제조분야, 이러한 정제된 합성가스를 사용하여 피셔트롭스(Fischer-Tropsh) 반응단계를 거쳐 탄화수소를 제조하는 단계, 마지막으로 탄화수로부터 항공유에 적합한 upgrading기술인 크래킹(cracking) 및 이성화(isomerization) 반응단계로 구분된다. 본 발표에서는 국내외 연구동향 및 주요단계에 중점기술에 관해 언급하고자 한다. The research for production of jet fuel from petroleum displacement resources such as bio-mass, coal, natural gas mainly consists of three sub-research areas; the fisrt step is the pretreatment for producing a synthetic gas, and the next step is the Fischer-Trophsh reaction process for making hydrocarbons. The last is the upgrading technology for the hydrocarbons to fit a jet fuel specification via cracking and isomerization reactions. This talk presents reaserch trends and main technologies for production of jet fuel derived from petroleum displacement resources.
Three-Dimensional Reduced-Symmetry of Colloidal Plasmonic Nanoparticles
Jeong, Eunhye,Kim, Kihoon,Choi, Inhee,Jeong, Sunil,Park, Younggeun,Lee, Hyunjoo,Kim, Soo Hong,Lee, Luke P.,Choi, Yeonho,Kang, Taewook American Chemical Society 2012 NANO LETTERS Vol.12 No.5
<P>Owing to their novel optical properties, three-dimensional plasmonic nanostructures with reduced symmetry such as a nanocrescent and a nanocup have attracted considerable current interest in biophotonic imaging and sensing. However, their practical applications have been still limited since the colloidal synthesis of such structures that allows, in principle, for in vivo application and large-scale production has not been explored yet. To date, these structures have been fabricated only on two-dimensional substrates using micro/nanofabrication techniques. Here we demonstrate an innovative way of breaking symmetry of colloidal plasmonic nanoparticles. Our strategy exploits the direct overgrowth of Au on a hybrid colloidal dimer consisting of Au and polystyrene (PS) nanoparticles without the self-nucleation of Au in an aqueous solution. Upon the overgrowth reaction, the steric crowding of PS leads to morphological evolution of the Au part in the dimer ranging from half-shell, nanocrescent to nanoshell associated with the appearance of the second plasmon absorption band in near IR. Surface-enhanced Raman scattering signal is obtained directly from the symmetry-broken nanoparticles solution as an example showing the viability of the present approach. We believe our concept represents an important step toward a wide range of biophotonic applications for optical nanoplasmonics such as targeting, sensing/imaging, gene delivery, and optical gene regulations.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/nalefd/2012/nalefd.2012.12.issue-5/nl300435j/production/images/medium/nl-2012-00435j_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nl300435j'>ACS Electronic Supporting Info</A></P>
Fully Dispersed Rh Ensemble Catalyst To Enhance Low-Temperature Activity
Jeong, Hojin,Lee, Geonhee,Kim, Beom-Sik,Bae, Junemin,Han, Jeong Woo,Lee, Hyunjoo American Chemical Society 2018 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.140 No.30
<P>Minimizing the use of precious metal catalysts is important in many applications. Single-atom catalysts (SACs) have received much attention because all of the metal atoms can be used for surface reactions. However, SACs cannot catalyze some important reactions that require ensemble sites. Here, Rh catalysts were prepared by treating 2 wt % Rh/CeO<SUB>2</SUB> hydrothermally at 750 °C for 25 h. Nearly 100% dispersion was obtained, but the surface Rh atoms were not isolated (denoted as ENS). They catalyzed the oxidation of C<SUB>3</SUB>H<SUB>6</SUB> or C<SUB>3</SUB>H<SUB>8</SUB> at low temperatures, but these oxidations did not occur on the Rh SAC. When the simultaneous oxidation of CO, C<SUB>3</SUB>H<SUB>6</SUB>, and C<SUB>3</SUB>H<SUB>8</SUB> was performed, the <I>T</I><SUB>20</SUB> (temperature at conversion 20%) for CO oxidation increased significantly from 40 °C for sole CO oxidation to 180 °C on SAC due to the competitive adsorption of hydrocarbons. However, <I>T</I><SUB>20</SUB> increased much less on ENS, from 60 to 100 °C. ENS exhibited superior activity for low-temperature oxidation. During hydrothermal treatment for 25 h, the Rh size initially increased from 2.3 to 6.7 nm then decreased to 0.9 nm. The surface hydroxyl groups formed on the catalyst surface help detach Rh atoms from Rh clusters, while preventing the reaggregation of dispersed Rh atoms into Rh clusters. This fully dispersed catalyst would have maximum atom-efficiency while catalyzing various surface reactions.</P> [FIG OMISSION]</BR>
Erythema infectiosum: a retrospective clinical study of 83 cases
( Hongpil Jeong ),( Hanhim Jeong ),( Sunyoung Jo ),( Seunggi Hong ),( Jaewan Go ),( Hyunjoo Lee ),( Eunphil Heo ) 대한피부과학회 2019 대한피부과학회 학술발표대회집 Vol.71 No.2
Background: Erythema infectiosum (EI) is a childhood illness commonly observed among school-aged children and is caused by the infection of Human parvovirus B19 (B19). In atypical forms, it is often difficult to distinguish from other viral diseases, drug eruption, and erythema multiforme. Objectives: The purpose of this study was to analyze clinical characteristic of EI. Methods: We retrospectively reviewed the medical records of the patients who suspected for EI from last 10 years (January 2009 - August 2019) in our hospital found eighty three patients. Results: A total of 83 patients (male to female ratio, 1.08) with a mean age of 8.45 years (range, 0.7 ~ 43 years) were evaluated. Rash started from face in 32 cases (38.6%), trunk in 16 cases (19.3%) and simultaneously in the whole body in 35 cases. Most patients has similar lapse of illness, resolved skin lesion in 1-2 weeks without other complications. Four cases had arthralgia, and thirty eight patients had upper respiratory tract infection symptoms with mild fever. We identified B19 DNA by PCR from serum in 27 cases (33%), results of test were positive in 18 and negative in 9. In these patients needed for differential diagnosis with drug eruption (3 cases), viral exanthem (8 cases) and acute urticaria (4 cases). Conclusion: EI is usually diagnosed on clinical characteristics. But significant number of atypical EI can be observed, which should be differentiated from other diseases. In these cases, serum B19 PCR aid confirmation of EI.
합성가스로부터 탄화수소제조를 위한 피서트롭스 반응에 관한 촉매 종류 및 반응매체의 영향
김철웅(Chul-Ung Kim),정순용(Soon-Yong Jeong),정광은(Kwang-Eun Jeong),고재천(Jae-Cheon Koh),채호정(Ho-Jeong Chae),김태완(Tae-wan Kim),박현주(Hyunjoo Park),이상봉(Sang-Bong Lee),한정식(Jeongsik Han),정병훈(Byunghun Jeong) 한국추진공학회 2010 한국추진공학회 학술대회논문집 Vol.2010 No.11
석유자원의 고갈에 따라 전 세계적으로 석유대체자원인 석탄, 천연가스 및 바이오매스로부터 합성연료 및 화학물질을 제조하기 위한 피셔트롭스 반응에 관한 많은 연구가 이루어지고 있다. 일반적으로 이러한 피셔트롭스 반응은 주로 스케일 업이 비교적 용이한 고정층 반응기를 사용한 기상반응이 적용되고 있으나, 촉매 기공에서의 확산제어 및 왁스의 생성에 따른 촉매의 비활성화 등의 문제점에 기인하여 최근 들어 초임계 유체를 이용한 반응이 많이 연구되고 있다. 본 연구에서는 피셔트롭스 반응에 관한 담지 촉매 및 반응매체에 관한 좀 더 심도 있는 영향을 고찰하기 위해 다양한 담지촉매를 제조하여 피셔트롭스 반응에 관한 기상반응과 초임계 반응을 비교, 고찰하였다. With petroleum reserves dwindling, interest has been increasing worldwide in Fischer-Tropsch synthesis (FT) as a method of producing synthetic liquid fuels and chemicals from coal, natural gas or biomass. In general, FT synthesis is operated through the gas phase fixed-bed reaction system. Recently, there are lots of study in supercritical fluid due to unique characteristics such as the quick diffusion of reactant gas, effective removal of reaction heat, and the in-situ extraction of high molecular weight hydrocarbon, such as wax. In this study, our major aim is to obtain a deeper insight into the effect of the type of support on the reaction performance over a supported cobalt catalyst in a fixed bed reactor.
Jeong, Hojin,Kim, Chanyeon,Yang, Sungeun,Lee, Hyunjoo Elsevier 2016 Journal of catalysis Vol.344 No.-
<P><B>Abstract</B></P> <P>Ni nanoparticles were synthesized by a colloidal method in the presence of organic surface-capping agents and used to catalyze the selective hydrogenation of unsaturated furanic aldehydes to furanic alcohols. The effects of the Ni nanoparticle size and surface organic layer were evaluated. Of the 3.7, 5.1, 6.8, and 10.4nm Ni nanoparticles tested in selective furfural (FFR) hydrogenation to furfuryl alcohol (FFA), the 6.8nm Ni nanoparticles exhibited the highest yield because access to the surface sites on the smaller and larger nanoparticles was blocked by the densely packed organic layer and by their agglomeration due to magnetic attraction, respectively. The capped Ni nanoparticles exhibited a high FFA yield of 96%, whereas significant over-hydrogenation was observed when uncapped calcined Ni/SiO<SUB>2</SUB> catalysts with similarly sized Ni nanoparticles were employed. Steric hindrance of the Ni surface induced by the organic surface layer led to selective FFR hydrogenation to FFA. The capped Ni nanoparticles could be reused repeatedly without a significant loss in the FFA yield. They also exhibited high selectivity (>90%) in the hydrogenation of other unsaturated furanic aldehydes to their corresponding alcohols.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Ni NPs capped with organic molecules showed high activity for selective hydrogenation. </LI> <LI> The surface organic molecules suppressed over-hydrogenation unlike uncapped Ni NPs. </LI> <LI> The size effect of capped and uncapped Ni NPs was estimated. </LI> <LI> The capped Ni NP catalysts can be reused up to 5 times without loss in activity. </LI> <LI> The absence of Ni ensemble sites on the capped Ni NPs was confirmed by in-situ IR. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Sitting Posture-Based Lighting System to Enhance the Desired Mood
Hyunjoo Bae,Haechan Kim,Hyeon-Jeong Suk 대한인간공학회 2015 大韓人間工學會誌 Vol.34 No.2
Objective: As a cue for desired mood, we attempted to identify types of sitting postures when people are involved in various tasks during their working hours. Background: Physical behaviors in reaction to user contexts were studied, such as automated posture analysis for detecting a subject"s emotion. Sitting postures have high feasibility and can be detected robustly with a sensing chair, especially when it comes to an office. Method: First, we attached seven sensors, including six pressure sensors and one distance sensor, to an office chair. In Part 1, we recorded participants" postures while they took part in four different tasks. From the seven sensors, we gathered five sets of data related to the head, the lumbar, the hip, thigh pressure and the distance between the backrest and the body. We classified them into four postures: leaning forward, upright, upright with the lumbar supporting, and leaning backward. In part 2, we requested the subjects to take suitable poses for the each of the four task types. In this way, we compared the matches between postures and tasks in a natural setting to those in a controlled situation. Results: We derived four types of sitting postures that were mapped onto the different tasks. The comparison yielded no statistical significance between Parts 1 and 2. In addition, there was a significant association between the task types and the posture types. Conclusion: The users" sitting postures were related to different types of tasks. This study demonstrates how human emotion can interact with lighting, as mediated through physical behavior. Application: We developed a posture-based lighting system that manipulates the quality of office lighting and is operated by changes in one"s posture. Facilitated by this system, color temperatures ranging between 3,000K and 7,000K and illuminations ranging between 300lx and 700lx were modulated.