• 한국전산유체공학회:학술대회논문집
• /
• 2005.04a
• /
• pp.70-73
• /
• 2005

The HANARO, multi-purpose research reactor, 30 MWth open-tank-in-pool type, is planning to produce a fission moly-99 of radio isotopes, a mother nuclide of Tc-99m, a medical isotope and is under developing a target handling tool for loading and unloading it in a circular flow tube (OR-5). A guide tube is extended from the reactor core to the top of the reactor chimney for easily loading the target under the reactor normal operation. But active coolant through the core can be quickly raised up to the top of the chimney through the guide tube. The jet flow was suppressed in the guide tube after reducing the inner diameter of a flow restriction orifice installed in the OR-5 flow tube for adding the pressure difference in the flow tube after unloading the target. This paper describes an analytical analysis to calculate the flow distribution in the core of the HANARO after suppressing the jet flow of the guide tube. As results, it was confirmed through the analysis results that the flow distribution in the core of the HANARO were not adversely affected.

• Microbiology and Biotechnology Letters
• /
• v.24 no.5
• /
• pp.624-629
• /
• 1996

The ethanol extracts from Angelica gigas Nakai and Angelica acutiloba Kitagawa were fractionated to diethyl ether and aqueous partitions. Both partitions had strong antimutagenic effect on the MNNG (N-methyl-N-nitro-N-nitrosoguanidine) by Ames mutagenicity test. Diethyl ether fractions exhibited the greatest antimutagenic effect suppressing the mutagenicity of MNNG with inhibition of 78-80%. The ethanol extracts from both species showed the inhibitory effect on the growth of several human cancer cell lines. Especially, the diethyl ether fraction from ethanol extracts was most effective on human hepatocellular carcinoma cells, inhibiting 90-95% of cell growth. However, the aqueous fractions had least inhibition activity on many cancer cells. There was little cytotoxicity on human normal liver cell by ethanol extracts. Diethyl ether fraction from Angelica gigas Nakai ethanol extract had cytotoxicity less than 20% on human normal liver cells, compared with that from Angelica acutiloba Kitagawa ethanol exract. The adding of 0.5 (g/l) of diethyl ether fractions of Angelica gigas Nakai or Angelica acutiloba Kitagawa increased immune activity by enhacing human B and T cells up to three to four times. It was proven that diethyl ether fraction (0.7 g/1) from Angelica gigas Nakai could control blood pressure by suppressing angiotensin converting enzyme activity up to 98%. From TLC, it was appeared that both of diethyl ether partitions had umbelliferon, known to one of active substances from Angelica gigas Nakai and Angelica acutiloba Kitagawa.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.18 no.2
• /
• pp.479-491
• /
• 1994

Discrete vortex method was applied for simulating an active control of turbulent leading- edge separation bubble. The leading-edge separation zone was perturbed by a time-dependent sinusoidal perturbation of different frequencies and levels. In order to describe the local sinusoidal perturbation at the separation point, a source pulsation vortex technique was proposed. The present two-dimensional vortex simulations were qualitatively compared with the experimental results for a blunt circular cylinder, where perturbation was introduced along the square-cut leading edge of the cylinder $(Kiya et al.^{(6,7)}).$ It was found that the reattachment length attained a minimum point at low levels of perturbation and two minima at a moderate higher perturbation frequency. The effects of local perturbation on the evolution of leading-edge separation bubble were scrutinized by comparing the perturbed flow with the natural flow. These comparisons were made for the distributions of mean velocity and its velocity fluctuations, intermittency and wall velocity. The motions of instantaneous reattachment in the space-time domain were demonstrated, which were also compared with the experimental findings. In order to investigate the reduction mehanism of reattachment length in the separation bubble, various cross-correlations for velocity and pressure and the relevant convection velocities were evaluated. It was observed that the convection velocity was closely associated with its corresponding pulsationg frequency.

• Korean Journal of Medicinal Crop Science
• /
• v.21 no.3
• /
• pp.204-212
• /
• 2013

In general, stepwise hot steaming process is known to be effective in improving its biological activities; however, not much employed in processing Codonopsis lanceolata due to its hardness. The complex processed C. lanceolata showed highest free radical scavenging acitivity as 45.21%. Total phenol and flavonoid content were of complex processed C. lanceolata higher than conventional extract and alone steaming process. It was showed the lower melanogenesis rate on melanin production test by B16F10 cells as 27.46%. High inhibitory of tyrosinase was also measured as 28.61% by adding steamed Codonopsis lanceolata extracts by high pressure extraction of 1.0 $mg/m{\ell}$. And anti-wrinkle activity were 39.08%. In comparing phenolic acids profiles in the extract, in general higher amounts of polyphenol were obtained possibly by easy release of active components during thermal processing, which results in better antioxidant activities than that of general extract. This findings can also be supported by result that the extract by steaming process showed better activities than the general extraction extract.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.18 no.2
• /
• pp.159-163
• /
• 2005

This paper gives characterization of ZnO thin film deposited by RF magnetron sputtering method, which is concerned in deposition process and device fabrication process, to fabricate solidly mounted resonator(SMR)-type film bulk acoustic resonator(FBAR). A piezoelectric layer of 1.1${\mu}{\textrm}{m}$ thick ZnO thin films were grown on thermally oxidized SiO$_2$(3000 $\AA$)/Si substrate layers by RF magnetron sputtering at the room temperature. The highly c-axis oriented ZnO thin film was obtained at the conditions of 265 W of RF power, 10 mtorr of working pressure, and 50/50 of Ar/O$_2$ gas ratio. The piezoelectric-active area was 50 ${\mu}{\textrm}{m}$${\times}$50${\mu}{\textrm}{m}$, and the thickness of ZnO film and Al-3 % Cu electrode were 1.4 ${\mu}{\textrm}{m}$ and 180${\mu}{\textrm}{m}$, respectively. Its series and parallel frequencies appeared at 2.128 and 2.151 GHz, respectively, and the qualify factor of the resonator was as high as 401.8$\pm$8.5.

• Journal of Pharmaceutical Investigation
• /
• v.13 no.4
• /
• pp.153-172
• /
• 1983

The use of carrier systems for the delivery of drugs to areas in the body in need of pharmacological intervention is now the subject of intense research in many laboratories. Because of its obvious advantages (e.g. protection of drugs from hostile environments, facilitated target penetration and avoidance of side effects), drug delivery is expected to ease the pressure and expense of new drug development by making better use of drugs in existence. Generally, carrier-mediated delivery has been envisaged either as direct transport of drugs to a biological target by a carrier that will associate with it selectively, or as release of drugs from a carrier circulating in the blood or immobilized in tissues, at rates compatible with optimal action. One system that has attracted considerable attention is the use of liposomes as carriers of pharmacologically active agents. 154 references were reviewed with special emphasis on the targeting of drugs by use of liposomes in this respect. Recent advances in the other carrier systems and in methods for the preparation of liposomes were also reviewed briefly.

• Journal of Biosystems Engineering
• /
• v.25 no.1
• /
• pp.1-10
• /
• 2000

This study was conducted to develop the mathmatical model for predicting the side thrust which is generated by the shearing action on the vertical surfaces of the sides of the track. Experiments were conducted with the three different shear plates with grouser length of 1, 3 and 5 cm for two different soil condition using soil bin system. The measured side thrust were compared with the values predicted by the new model developed in this study and by Bekker's model respectively. The values of side thrust predicted by the new model were more close to the measured values than those of the side thrust predicted by Bekker's model . The total thrust measured were also compared with the values predicted by the conventional model which considers only bottom thrust effect and by the new model which contains not only bottom thurst but side thrust effect. The values of the thrust predicted by conventional modelwere lower than measured values for both of the soil conditions and the three levels of grouser length. The maximum errors of conventional model were increased with the increase of grouser length. but the values of the total thrust predicted by the model developed in this study were well matched to the measured ones for both of the soil conditions and the three levels of grouser lengths.

• 제어로봇시스템학회:학술대회논문집
• /
• 2000.10a
• /
• pp.20-20
• /
• 2000

Back-propagation neural network (BPNN) is the most prevalently used paradigm in modeling semiconductor manufacturing processes, which as a neuron activation function typically employs a bipolar or unipolar sigmoid function in either hidden and output layers. In this study, applicability of another linear function as a neuron activation function is investigated. The linear function was operated in combination with other sigmoid functions. Comparison revealed that a particular combination, the bipolar sigmoid function in hidden layer and the linear function in output layer, is found to be the best combination that yields the highest prediction accuracy. For BPNN with this combination, predictive performance once again optimized by incrementally adjusting the gradients respective to each function. A total of 121 combinations of gradients were examined and out of them one optimal set was determined. Predictive performance of the corresponding model were compared to non-optimized, revealing that optimized models are more accurate over non-optimized counterparts by an improvement of more than 30%. This demonstrates that the proposed gradient-optimized teaming for BPNN with a linear function in output layer is an effective means to construct plasma models. The plasma modeled is a hemispherical inductively coupled plasma, which was characterized by a 24 full factorial design. To validate models, another eight experiments were conducted. process variables that were varied in the design include source polver, pressure, position of chuck holder and chroline flow rate. Plasma attributes measured using Langmuir probe are electron density, electron temperature, and plasma potential.

• Journal of the Korean Vacuum Society
• /
• v.13 no.3
• /
• pp.99-102
• /
• 2004

In this work the electrical characteristics of organic thin film transistors with the surface-treated organic gate insulator have been studied. For the surface treatment of gate dielectric, Ar plasma was used. Pentacene and PVP were used as active and dielectric layers respectively. Pentacene was thermally evaporated in vacuum at a pressure of about $10^{-6}$ Torr and at a deposition rate of 0.5 $\AA$/sec. PVP was spin coated and cured at $100^{\circ}C$. before pentacene deposition. organic thin film transistors with surface-treated gate insulators have provided improved operation characteristics.

• Laser Solutions
• /
• v.15 no.3
• /
• pp.7-10
• /
• 2012

Dimensions (line/space) of circuits in IC substrates for high-end chips (e.g. CPU, etc.) are anticipated to decrease as small as $10{\mu}m/10{\mu}m$ in 2014. Since current etch-based circuit-patterning processes are not able to address the urgent requirement from industry, laser-based circuit patterning processes are under active research in which UV laser is used to engrave embedded circuits patterns into IC substrates. In this paper, we used a nanosecond UV laser to directly fabricate embedded circuit patterns into IC substrates with/without ceramic powders. In experiments, we engraved embedded circuit patterns with dimensions (width/depth) of abut $10{\mu}m/10{\mu}m$ and $6{\mu}m/6{\mu}m$ into the IC substrates. Due to the recoil pressure occurring during ablation, the circuit patterning of the IC substrates with ceramic powders showed the higher ablation rate.