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CFD Analysis to Suppress Condensate Water Generated in Gas Sampling System of HANARO
SungHwan Cho,JongHyeon Lee,DaeYoung Kim 한국방사성폐기물학회 2020 방사성폐기물학회지 Vol.18 No.2(E)
HANARO (High-flux Advanced Neutron Application Reactor)는 우라늄의 핵분열 연쇄반응에서 생성된 중성자를 이용하여 다양한 연구개발을 수행하는 열출력 30 MW 규모의 연구용 원자로이다. 탈기탱크는 HANARO의 부속시설에 설치되어 있다. 탈기탱크는 내부환경요인으로 인해 기체오염물질을 발생시킨다. 탈기탱크는 기체오염물질을 허용 가능한 수준 이하로 유지하기위해 필요하며 기체시료채취판넬의 분석기에 의해 모니터링 된다. 응축수가 발생하여 기체시료채취판넬의 분석기 내부로 유입된다면, 분석기의 측정 챔버 내부에 부식이 발생하여 고장을 야기한다. 응축수의 생성 원인은 탈기탱크에 존재 하는 기체가 분석기로 유입되는 과정에서 탈기탱크와 분석기사이 온도 차이다. 응축수 생성을 억제하고 계통 내부에 생성 된 응축수를 효율적으로 제거하기 위해 탈기탱크와 기체시료채취판넬 사이에 히팅시스템이 설치되었다. 이 연구에서 우리는 히팅시스템의 효율성을 알고자 한다. 또한 Wall Condensation Model을 이용하여 유체 입구온도, 외부온도 및 히팅 케이블 설정온도 변화에 따른 파이프 온도와 평균응축량의 변화를 모델링하였다. The high-flux advanced neutron application reactor (HANARO) is a research reactor with thermal power of 30 MW applied in various research and development using neutrons generated from uranium fission chain reaction. A degasifier tank is installed in the ancillary facility of HANARO. This facility generates gas pollutants produced owing to internal environmental factors. The degasifier tank is designed to maintain the gas contaminants below acceptable levels and is monitored using an analyzer in the gas sampling panel. If condensate water is generated and flows into the analyzer of the gas sampling panel, corrosion occurs inside the analyzer's measurement chamber, which causes failure. Condensate water is generated because of the temperature difference between the degasifier tank and analyzer when the gas flows into the analyzer. A heating system is installed between the degasifier tank and gas sampling panel to suppress condensate water generation and effectively remove the condensate water inside the system. In this study, we investigated the efficiency of the heating system. In addition, the variations in the pipe temperature and the amount of average condensate water were modeled using a wall condensation model based on the changes in the fluid inlet temperature, outside air temperature, and heating cable-setting temperature.
Fully Elastic Conductive Films from Viscoelastic Composites
Cho, Sunghwan,Song, Jun Hyuk,Kong, Minsik,Shin, Sangbaie,Kim, Young-Tae,Park, Gyeongbae,Park, Chan-Gyung,Shin, Tae Joo,Myoung, Jaemin,Jeong, Unyong American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.50
<P>We investigated, for the first time, the conditions where a thermoplastic conductive composite can exhibit completely reversible stretchability at high elongational strains (epsilon = 1.8). We studied a composite of Au nanosheets and a polystyrene-block-polybutadiene-block-polystyrene block copolymer as an example. The composite had an outstandingly low sheet resistance (0.45 Omega/sq). We found that when a thin thermoplastic composite film is placed on a relatively thicker chemically cross-linked elastomer film, it can follow the reversible elastic behavior of the bottom elastomer. Such elasticity comes from the restoration of the block copolymer microstructure. The strong adhesion of the thermoplastic polymer to the metallic fillers is advantageous in the fabrication of mechanically robust, highly conductive, stretchable electrodes. The chemical stability of the Au composite was used to fabricate high luminescence, stretchable electrochemiluminescence displays with a conventional top-bottom electrode setup and with a horizontal electrode setup.</P>
High molecular weight thermoplastic polyether ester elastomer by reactive extrusion
Cho, Sunghwan,Jang, Yunjoo,Kim, Dongmin,Lee, Taeyoung,Lee, Dongho,Lee, Youngkwan Wiley Subscription Services, Inc., A Wiley Company 2009 Polymer engineering and science Vol.49 No.7
<P>A reactive branched thermoplastic polyether-ester elastomer (TPEE) precursor was synthesized by the esterification reaction of dimethyl terephthalate (DMT) with poly(tetramethylene etherglycol) (PTMEG), 1,4-butadiene, and glycerol as a soft segment, hard segment, and a branching agent, respectively. The high molecular weight TPEE was further synthesized with the prepared branched TPEE precursor, poly(butylene terephthalate) (PBT) and modified methylene diisocyanate (m-MDI, 0.5–2.0 wt%) by the reactive extrusion method. Their chemical structures were determined by Fourier Transform Infra Red (FTIR) and Proton-Nuclear Magnetic Resonance (<SUP>1</SUP>H NMR). Thermal characteristics and rheological properties of TPEE were measured by Differential Scanning Calorimetry (DSC) and rheometer as a function of m-MDI content. The intrinsic viscosity (IV) and melt index ratio (MIR) of TPEE increased as the content of m-MDI increased up to 1.5 wt% and remained constant thereafter. The variation of the MIR was consistent with that of the IV. The storage modulus and viscosity did not vary with the measurement time up to 1.0 wt% of m-MDI at the first extrusion, which indicates that the m-MDI reacted fully. However, the viscosity and storage modulus increased with increasing measurement time at m-MDI contents over 1.5 wt%. POLYM. ENG. SCI., 2009. © 2009 Societyof Plastics Engineers</P>
Sunghwan Cho,Yonggyun Kim 한국응용곤충학회 2006 Journal of Asia-Pacific Entomology Vol.9 No.1
A2 (PLA2) catalyzes phos-pholipids atsn(20:4n-6). The arachidonic acid is further oxidizedto form different eicosanoids, which play biologicalmediators to express cellular or humoral immune re-actions in response to pathogen infection.Xeno-rahbdus and Photorhabdus, the symbiotic bacteriaof entomopathogenic nematodes, have been knownto inhibit PLA2 to express their pathogenicity. Thisresearch aimed to test a hypothesis that other en-tomopathogenic bacteria also inhibit PLA2 to ex-press their pathogenicity inSpodopera exigua. T w obacterial species ofEnterococcus faecalisand Pseu-domonas fluorescenspresumably different in ento-bitory activities. A pathogenicE. faecalisinducedsignificantly imunodepression ofS. exiguabyinhibiting PLA2 activity because the bacteria-infectedS. exiguarecovered immune reactions afterthe addition of arachidonic acid. However, thenonpathogenicP. fluorescensdid not induce immu-nodepression because the addition of arachidonicacid to P. fluorescens-infectedS. exiguadid notfurther increase immune capacities while dexame-thasone, a PLA2 inhibitor, could ecrease the im-mune activities. Injection ofE. faecalisalong withμ -thogenicity in comparison with the bacteria alone.Moreover, the addition of dexamethasone transfor-med nonpathogenicP. fluorescensinto pathogenicbacterium. This study suggests an evidence thatPLA2 is an inhibitory target even for entomopatho-genic bacteria not related with entomopathogenicnematodes, and that he inhibition of PLA2 deter-mines the bacterial virulence inS. exigua.Key words arachidonic acid, dexamethasone,Ente-rococcus faecalis, phospholipase A2,Pseudomonasfluorescens, Spodoptera exigua
Sunghwan Cho,Kim, Yonggyun Korean Society of Applied Entomology 2004 Journal of Asia-Pacific Entomology Vol.7 No.2
Entomopathogenic bacteria of Xenorbabdus nematophila, Xenorhabdus sp., and Photorhabdus temperata subsp. temperata are symbionts of entomopathogenic nematodes including Steinernema and Heterorhabditis. These bacteria have potent insecticidal pathogenicity causing hemolymph septicemia. To explain a mechanism of the septicemia, this research raises a hypothesis that the hemolymph septicemia is due to the induction of the programmed cell death (=apoptosis) of the hemocytes by the entomopathogenic bacteria. Injection of the bacteria into the hemocoel of the fifth instar larvae of Bombyx mori led to septicemia (few viable hemocytes) at 12h in all three bacterial treatments. During the pathogenicity, the infected hemocytes exhibited the membrane b1ebbing, nuclear chromatin condensation and DNA fragmentation, which reflected typical morphological changes of cells undergoing apoptosis. The apoptosis began as early as 4h after bacterial injection and increased with post-injection time. Three pathogenic bacteria, however, differed in the degree of apoptosis-inducing effect on B. mori by the effective bacterial dose and time. These results support the hypothesis that hemolymph septicemia caused by the bacteria is due to their apoptosis-inducing effect.
소형 무인기들의 군집비행을 위한 운영 네트워크 시스템과 PILS 개발
김성환(Sunghwan Kim),조상욱(Sangook Cho),조성범(Seong-Beom Cho),박춘배(Choon-Bae Park) 제어로봇시스템학회 2012 제어·로봇·시스템학회 논문지 Vol.18 No.5
In this paper, a operation network system equipped with onboard wireless communication systems and ground-based mission control systems is proposed for swarm flight of small UAVs. This operating system can be divided into two networks, UaV communication network and ground control system. The UAV communication network is intend to exchange the informations of navigation, mission and flight status with minimum time delay. The ground control system consisted of mission control systems and UDP network. Proposed operation network system can make a swarm flight of various UAVs, execute complex missions decentralizing mission to several UAVs and cooperte several missions. Finally, PILS environments are developed based on the total operating system.