• Journal of computational fluids engineering
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• v.21 no.1
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• pp.43-49
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• 2016

Thermal cracking is commonly modeled as plug flow reaction, neglecting the lateral gradients present. In this paper, 2-dimensional computational fluid dynamics including turbulence model and molecular reaction scheme are carried out. This simulation is solved by means of coupled implicit scheme for stable convergence of solution. The reactor is modeled as an isothermal tube, whose length is 1.2 m and radius is 0.01 m, respectively. At first, The radial profile of velocity and temperature at each point are predicted in its condition. Then the bulk temperature and conversion curve along the axial direction are compared with other published data to identify the reason why discussed variations of properties are important to product yield. Finally, defining a new non-dimensional number, Effect of interaction with turbulence, heat transfer and chemical reaction are discussed for design of thermal cracking furnace.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.4
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• pp.587-593
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• 2002

The present research proposes a pressure based approach along with Langmuir slip condition for predicting microscale fluid flows. Using this method, gaseous slip flows in 2 -dimensional microchannels are numerically investigated. Compared to the DSMC simulation, statistical errors could be avoided and computing time is much less than that of the aforementioned molecular approach. Maxwell slip boundary condition is also studied in this research. These two slip conditions give similar results except for the pressure nonlinearity at high Knudsen number regime. However, Langmuir slip condition seems to be more promising because this does not need to calculate the streamwise velocity gradient accurately and to calibrate the empirical accommodation coefficient. The simulation results show that the proposed method using Langmuir slip condition is an effective tool for predicting compressibility and rarefaction in microscale slip flows.

• Journal of Advanced Marine Engineering and Technology
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• v.11 no.4
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• pp.50-58
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• 1987

At present it has been cleared that even carefully polished surfaces have irregularities on them which are large compared with molecular dimensions by the progress of a scanning electron microscope. When two solids are placed together, the real area of contact is very small, so that the local pressure is high and, in general, exceeds the yield pressure of the metal. Plastic flow of the solid occurs at the summits of the irregularities so that the real area of contact is proportional to the applied load. There is adhesion at local resions of contact and the friction is, in a large measure, the force required to shear them. On this view point, the friction experiment with different specimens which are carbon steel, copper and constantan was attempted to know the characteristics of temperature change in contact with different metals. Various experiments are summerized as follows; 1) With metals of high melting point, momentary 1000 .deg. C may last below $10^{-4}$ of a second. It is thought that above phenomena back up previous adhesion theory in wear. 2) As a general rule, surface temperature in contact with different metals becomes high when the load increases while it is observed that surface temperature decreases when the load increases with shapes of specimens.

• Nuclear Medicine and Molecular Imaging
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• v.43 no.3
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• pp.174-178
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• 2009

Many radiopharmaceuticals have been developed and wildy used in the imaging cardiac function. Myocardial perfusion imaging (MPI) is a well established noninvasive method of assessing coronary blood flow and has been widely used in patients diagnosed or suspected with coronary artery diseases. The innovation of radiopharmaceuticals used in the cardiac imaging is one of the most important contributors to the development of nuclear cardiology. Thallium-201 and various technetium-99m agents have been globally used for myocardial perfusion SPEG, and N-13 ammonia (13NH3), rubidium-82 (82Rb), 0-15 water (H2150) for myocardial perfusion PET. As well as the cardiac perfusion studies, new radiopharmaceuticals that visualize fat metabolism or receptors of the sympathetic nervous system have successfully been applied to clinical practice. Useful information can be obtained for diagnosing coronary artery disease, evaluating patients' condition, or assessing therapeutic effects. In this review, we describe the characteristics and clinical usefulness of radiopharmaceuticals used for cardiac SPEG and PET.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.8
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• pp.3705-3708
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• 2012

Effects of Cantharidinate on apoptosis of human colorectal cancer UTC-116 cells were investigated by means of 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay, H and E staining, flow cytometry, and Raman Spectra analysis. The results showed Cantharidinate to exert inhibitory action on proliferation of human colorectal cancer UTC-116 cells, inducing apoptosis, arresting cells in G1 phase, with decline of S and G2 phases. In addition, the results of Raman spectrum showed significant changes in the UTC-116 cells chemical structure with stretching after the application of Cantharidinate. Taken together, these results suggest that the treatment of human colorectal cancer with Cantharidinate may be associated with multiple molecular mechanisms for apoptosis. Furthermore, similar to fluorouracil, Cantharidinate should be considered as novel assistant drug for controlling the growth of human colorectal cancer UTC-116 cells.

• Journal of the Korean Chemical Society
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• v.17 no.3
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• pp.207-212
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• 1973

The mechanical degradation of poly (-vinylacetate) in several mixed solvents (dioxane-n-butanol, dioxane-sec-butanol, dioxane-ethyleneglycol, dioxane-kerosene.) was studied using the capillary flow method. The velocity constant of scission reaction (k) and the limited degree of polymerization (g) were compared at the same value of [${\eta}$], which is considered as the parameter of molecular dimension of polymers in solution. As result, (k) did not change much, even if the species and the volume fraction of poor (non-) solvents changed, while the value of (g) changed according to the species of poor solvents and the value of [${\eta}$]. From the facts described above, It follows that the limited degree of polymerization (g) were affected by the composition and distribution of mixed solvent molecules around the polymer chain, and the value of $\alpha$ (at [${\eta}$] = $KM^a$) in the polymer solution.

• Journal of the Korean Society for Railway
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• v.9 no.3 s.34
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• pp.282-290
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• 2006

In the current train operation system, large scaled stations like Cheongnyangni and Yongsan are not remote controlled from the central operator but manually by local operator. It is because there are so many entering and exit of trains between depot and mainline which are operating through the large scaled stations and it is very effective to traffic flow on the mainline. Therefore, Kyong Bong Technology Co., Ltd. (KBTech) and Korea Railway Research Institute (KRRI) are continuing the research and development to import 'Autonomous Decentralized System (ADS)'as part of a new train operation control system which is a national policy project of MOCT (Ministry Of Construction & Transportation). The concept of the 'Autonomous Decentralized System (ADS)' has born in 1970's in Japan by the influences of molecular biology. The special features of ADS are being a system that able to do the online expansion, online maintenance and fault tolerance. This thesis introduces the concept of technology of ADS and also describes the system designing & development to apply with large scaled stations.

• Journal of Physiology & Pathology in Korean Medicine
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• v.21 no.6
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• pp.1513-1519
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• 2007

Yukwool-tang (YWT) is a traditional Chinese medicine, which has been used for patients suffering from a uterine disease in Oriental medicine. In the present study, it was examined the biochemical mechanisms of apoptosis by YWT in human cervical carcinoma HeLa cells. It was found that YWT could inhibit the cell growth of HeLa cells in a dose-dependent manner, which was associated with apoptotic cell death such as formation of apoptotic bodies and DNA fragmentation. Flow cytometry analysis confirmed that YWT treatment increased populations of apoptotic-sub-G1 phase of the cell cycle. We observed the p53-independent induction of p21 proteins, down-regulation of anti apoptotic Bcl-2 expression and proteolytic activation of caspase-3 in YWT-treated HeLa cells. YWT treatment also concomitant degradation and/or inhibition of poly (ADP-ribose) polymerase (PARP), phospholipase C-1 ($PLC{\gamma}1$), ${\beta}-catenin$ and DNA fragmentation factor 45/inhibitor of caspase-activated DNase (DFF45/ICAD). Taken together, these findings partially provide novel insights into the possible molecular mechanism of the anti-cancer activity of YWT.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.2299-2300
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• 2008

The Velocity Autocorrelation Function (VAF) of the sodium ions is calculated for a range of temperature from 250K to 1000K and converted into the linear ac-conductivity and ac-susceptibility response via Fourier transformation. A peak is found in the conductivity around $6{\times}10^{12}$ Hz that has some of the character of a Poley absorption. Here it is shown to be due to an harmonically coupled site vibrations of the sodium atoms, which extend only over a limited range. At frequencies below the peak the conductivity tends towards a constant i.e. dc value corresponding to a constant flow of ions through the simulation cell. At high temperatures the conductivity due to this ion transport process behaves like a metal with an insulator to metal transition occurring around a specific temperature.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.14
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• pp.5863-5868
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• 2015

Nicotine-derived nitrosamine ketone (NNK) is considered a key tobacco smoke carcinogen inducing lung tumors. Physalis peruviana L (harankash) is considered one plant with marked health benefits. This study aimed to evaluate Physalis peruviana L effect on the toxic effect of NNK induced lung cancer in the rats by using pulmonary histopathological, immunohistochemical and DNA flow cytometric analyses. Sixty adult male rats were divided into four groups, each consisting of fifteen animals. The first group received saline, the second received two successive toxic doses of NNK only while the third received two successive toxic doses of NNK with a single daily dose of Physalis peruviana L. The fourth group received a single daily dose of Physalis peruviana L only. Toxic doses of NNK induced hyperplasia and adenocarcinoma in the lung and positive immunoreactivity for Ki-67 and p53 staining with disturbance of the lung DNA content. Administration of Physalis peruviana L with NNK led to a mild pulmonary hyperplasia and weak expression of Ki-67 and p53 with an improvement in the lung DNA content. Physalis peruviana L may protect against NNK induced lung carcinogenesis due to its antioxidant and anti-proliferative effects.