• Korean Journal of Materials Research
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• v.17 no.1
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• pp.11-17
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• 2007

Turbulent in-situ mixing process is a new material process technology to get dispersed phase in nanometer size by controlling reaction of liquid/solid, liquid/gas, flow ana solidification speed simultaneously. In this study, mixing which is the key technology to this synthesis method was studied by computational fluid dynamics. For the simulation of mixing of liquid metal, static mixers investigated. Two inlets for different liquid metal meet ana merge like 'Y' shape tube having various shapes and radios of curve. The performance of mixer was evaluated with quantitative analysis with coefficient of variance of mass fraction. Also, detailed plots of intersection were presented to understand effect of mixer shape on mixing. The simulations show that the Reynolds number (Re) is the important factor to mixing and dispersion of $TiB_2$ particles. Mixer was designed according to the simulation, and $Cu-TiB_2$ nano composites were evaluated. $TiB_2$ nano particles were uniformly dispersed when Re was 1000, and cluster formation and reduction in volume fraction of $TiB_2$ were found at higher Re.

• Journal of Biomedical Engineering Research
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• v.30 no.5
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• pp.393-400
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• 2009

The present study developed a new technique with no physical object on the flow stream but enabling the air flow measurement and easily incorporated with the devices for cardiopulmonary resuscitation(CPR) procedure. A turbulence chamber was formed in the middle of the respiratory tube by locally enlarging the cross-sectional area where the flow related turbulence was generated inducing energy loss which was in turn converted into pressure difference. The turbulence chamber was simply an empty enlarged air space, thus no physical object existed on the flow stream, but still the flow rate could be evaluated. Computer simulation demonstrated stable turbulence formation big enough to measure. Experiment was followed on the proto-type transducer, the results of which were within ${\pm}5%$ error compared to the simulation data. Both inspiratory and expiratory flows were obtained with symmetric measurement characteristics. Quadratic curve fitting provided excellent calibration formula with a correlation coefficient>0.999(P<0.0001) and the mean relative error<1%. The present results can be usefully applied to accurately monitor the air flow rate during CPR.

• Journal of the Korean Ceramic Society
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• v.38 no.3
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• pp.287-292
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• 2001

본 실험은 목적은 CRT(Cathode Ray Tube)용 청색 형광체인 ZnS:Ag 분말 표면에 액상법으로 SnO$_2$를 균일하게 코팅하는 공정조건을 연구하는 것이다. 용매로서 물을 사용하고, Sn의 공급물질로서 SnCl$_4$.4$H_2O$, 침전 촉매로서 CO(NH$_2$)$_2$를 각각 사용하여, 균일 침전 방법으로 ZnS:Ag 분말표면에 SnO$_2$를 코팅할 수 있었다. 초기에 첨가되는 SnCl$_4$.4$H_2O$의 량이 Sn/Zn의 몰비기준으로 0.017인 경우에 ZnS:Ag 분말표면에 Sn(OH)$_4$가 균일하게 코팅되지만, 그 이상 첨가되면 과량의 Sn(OH)$_4$가 입자들 사이에 응집되었다. 코팅된 Sn(OH)$_4$는 비정질 구조로 규명되었으며, 이를 SnO$_2$결정상으로 전이시키기 위하여 300~$700^{\circ}C$ 범위 내에서 열처리를 행하였다. 비정질 Sn(OH)$_4$는 20$0^{\circ}C$이하에서 탈수되었고 45$0^{\circ}C$부터 SnO$_2$로 결정화되기 시작하였다. 순수한 ZnS의 경우, 50$0^{\circ}C$이하에서는 상변화가 없으나, $600^{\circ}C$에서 일부 산화되었으며 $700^{\circ}C$에서는 완전히 ZnO로 산화되므로, ZnS의 산화방지 및 SnO$_2$의 결정화를 동시에 만족하는 최고 열처리온도는 50$0^{\circ}C$로 규명되었다. 그러나 ZnS에 SnO$_2$가 코팅된 시편의 경우에는 $600^{\circ}C$가 되어도 ZnS 상이 거의 산화되지 않았고, $700^{\circ}C$에서도 ZnS와 ZnO 상이 공존한 것으로 보아 SnO$_2$코팅이 ZnS의 산화를 억제하는 것으로 나타났다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.8
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• pp.511-517
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• 2016

Three-dimensional models of stenosis blood vessels were prepared using a 3D printer. The models included a straight pipe with axisymmetric stenosis and a pipe that was bent $10^{\circ}$ from the center of stenosis. A refractive index matching method was utilized to measure accurate velocity fields inside the 3D tubes. Three different pulsatile flows were generated and controlled by changing the rotational speed frequency of the peristaltic pump. Unsteady velocity fields were measured by a time-resolved particle image velocimetry method. Periodic shedding of vortices occurred and moves depended on the maximum velocity region. The sizes and the positions of the vortices and symmetry are influenced by mean Reynolds number and tube geometry. In the case of the bent pipe, a recirculation zone observed at the post-stenosis could explain the possibility of blood clot formation and blood clot adhesion in view of hemodynamics.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.9
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• pp.790-798
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• 2007

An experimental study was performed to investigate the effects of mixing quality, inlet pressure, nozzle diameter on CO, NO emission and radiation characteristics in porous ceramic fiber radiant burners. Observations of combustion characteristics occurring inside the burner system which was insulated fiber mat, were investigated by measuring emission and radiation characteristics. Combustion was achieved at the firing rate of $88{\sim}99\;kcal/hr$, inlet pressure of $100{\sim}250mmH_2O$. The fiber burner exhibit significant both spectral intensity peaks in the bands at $2.5{\mu}m\;and\;4.0{\mu}m$ relatively. There is a small difference in the variable mixing tube. However spectral intensity increased with the firing rate. CO emissions were found to be strongly dependent on the operating conditions. There was a tendency that CO concentration increased as the firing rate increases. the reason for rise of CO concentration is that is becomes it the relatively rich condition. Relatively low NO emission was observed for the whole operating range. The NO concentration is maximal at the firing rate of approximately 2850 kcal/hr and an air ratio of about 1.

• The Journal of Internal Korean Medicine
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• v.22 no.4
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• pp.639-645
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• 2001

Angiogenesis is a fundamental process in reproduction and wound healing. Under these condition, neovascularization is tightly regulated. Unregulated angiogenesis may lead to several angiogenic diseases, and is thought to be indispensible for solid tumor growth and metastsis. The construction of new vascular network is a multistep cascade involving basement membrane degradation, endothelial cell proliferation, endothelial cell migration, and tube formation. Newly reported anti-angiogenic agents in oriental medical field have targeted both specific and multistep stages in the angiogenic process. From recent approach in oriental medical field with several herb medicines including activating blood flow and removing blood stasis medicine(活血化瘀藥), it may be possible in the future to develope specific anti-angiogenic agents that offer a less toxic potential therapy for cancer and angiogenic disease.

• Journal of Powder Materials
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• v.21 no.1
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• pp.28-33
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• 2014

This paper describes the surface modification effect of a Ti substrate for improved dispersibility of the catalytic metal. Etching of a pure titanium substrate was conducted in 50% $H_2SO_4$, $50^{\circ}C$ for 1 h-12 h to observe the surface roughness as a function of the etching time. At 1 h, the grain boundaries were obvious and the crystal grains were distinguishable. The grain surface showed micro-porosities owing to the formation of micro-pits less than $1{\mu}m$ in diameter. The depths of the grain boundary and micro-pits appear to increase with etching time. After synthesizing the catalytic metal and growing the carbon nano tube (CNT) on Ti substrate with varying surface roughness, the distribution trends of the catalytic metal and grown CNT on Ti substrate are discussed from a micro-structural perspective.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.1
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• pp.167-174
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• 2014

Tumor angiogenesis, growth and metastasis are three closely related processes. We therefore investigated the effects of barbigerone on all three in the B16F10 tumor model established in both zebrafish and mouse models, and explored underlying molecular mechanisms. In vitro, barbigerone inhibited B16F10 cell proliferation, survival, migration and invasion and suppressed human umbilical vascular endothelial cell migration, invasion and tube formation in concentration-dependent manners. In the transgenic zebrafish model, treatment with $10{\mu}M$ barbigerone remarkably inhibited angiogenesis and tumor-associated angiogenesis by reducing blood vessel development more than 90%. In vivo, barbigerone significantly suppressed angiogenesis as measured by H and E staining of matrigel plugs and CD31 staining of B16F10 melanoma tumors in C57BL/6 mice. Furthermore, it exhibited highly potent activity at inhibiting tumor growth and metastasis to the lung of B16F10 melanoma cells injected into C57BL/6 mice. Western blotting revealed that barbigerone inhibited phosphorylation of AKT, FAK and MAPK family members, including ERK, JNK, and p38 MAPKs, in B16F10 cells mainly through the MEK3/6/p38 MAPK signaling pathway. These findings suggested for the first time that barbigerone could inhibit tumor-angiogenesis, tumor growth and lung metastasis via downregulation of the MEK3/6/p38 MAPK signaling pathway. The findings support further investigation of barbigerone as a potential anti-cancer drug.

• Journal of Microbiology and Biotechnology
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• v.18 no.2
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• pp.242-247
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• 2008

In the fungal pathogen Candida albicans, the yeast-to-hyphal transition occurs in response to a broad range of environmental stimuli and is considered to be a major virulence factor. To address whether the zinc homeostasis affects the growth or pathogenicity of C. albicans, we functionally characterized the zinc-finger protein Csr1 during filamentation. The deduced amino acid sequence of Csr1 showed a 49% similarity to the zinc-specific transcription factor, Zap1 of Saccharomyces cerevisiae. Sequential disruptions of CSR1 were carried out in diploid C. albicans. The csr1/csr1 mutant strain showed severe growth defects under zinc-limited growth conditions and the filamentation defect under hypha-inducing media. The colony morphology and the germ-tube formation were significantly affected by the csr1 mutation. The expression of the hyphae-specific gene HWP1 was also impaired in csr1/csr1 cells. The C. albicans homologs of ZRTl and ZRT2, which are zinc-transporter genes in S. cerevisiae, were isolated. High-copy number plasmids of these genes suppressed the filamentation defect of the csr1/csr1 mutant strain. We propose that the filamentation phenotype of C. albicans is closely associated with the zinc homeostasis in the cells and that Csr1 plays a critical role in this regulation.

• Korean Security Journal
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• no.5
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• pp.19-40
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• 2002

For front, aspect of terror may have to prepare indeed even chemical terror or rocket and small size missile and radioactivity terror because is predicted to become various. Furthermore, when see motion of every countries about nuclear engineerses' bringing round and illicit sale of plutonium, our country may have to prepare in terrorism which is expected thus. So that can finish international event successfully because the United States of America supports great manpower and budget since New York's World Trade Center terror and when see that is considering terror prevention countermeasure, we operate temporarily bursting tube state complete charge team such as terror by each field specialist such as a concern interested including special CBR complete charge moving team among 2002 World Cups soccer game period ahead of international event, must consider safety countermeasure. Specially, biology weapon of chemical weapon and cholera etc. 13 kinds of 5000ton that North Korea plans CBR terror society confusion that North Korea that to terror support nation as well as nuclear weapons development suspicion is defending South Korea communization strategy as real condition that is amplified as well as is saving production brand gets imprinted uses CBR terror at normal times, when see that is planing powerlessness communization unity using CBR weapon at time of war, must operate until bias 2002 World Cups international event finishes cooperation safety countermeasure utensil safely under closer talk between the South Korea ${\cdot}$ Japan ${\cdot}$ North Korea. As for us which must serve 2002 World Cup successfully to accomplish perfectly preparedness of CBR terror firstly, all inhabitants knows well CBR protection trick, and secondly, CBR existing formation that solidify realignment CBR complete charge moving team which of course is consisted of CBR specialist compose and keeping immediate going out attitude operating, by third, that expand CBR individual protection equipment and CBR evacuation equipment and establish individual and group protection attitude naturally, supplement as there is main room that actualize CBR pollution patient's slogan countermeasure by fourth, and develop standard model for CBR terror provision by fifthBecause constructing infra of CBR safety establishing CBR preparedness that utilize it, must minimize damage and contribute inhabitants' life and property protection.