• Bulletin of the Society of Naval Architects of Korea
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• v.26 no.3
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• pp.1-8
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• 1989

The flow characteristics of a circulating water channel which is appropriate for a flow measurement and visualization in the laboratory has been investigated by using a Laser Doppler Anemometer. In order to get a stable and uniform distribution of mean velocity at the test section, the surface flow accelerator is designed and used. The experimental results that the turbulent structure should be considered with the mean velocity for obtaining the reasonable uniformity at the test section.

• Bulletin of the Korean Chemical Society
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• v.27 no.12
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• pp.1997-2001
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• 2006

The photodissociation dynamics of formic acid (HCOOH) at 206 nm have been investigated from rotationally resolved laser induced fluorescence spectra of OH ($^2\Pi$) fragments produced exclusively in the ground state. From the spectra, the rotational energy of the fragments was measured to be $820\;{\pm}\;50\;cm^{-1}$. The translational energy released in the products, which is 87% of the total available energy of the system, was also measured from analyses of the Doppler profiles. Joining these data with quantum chemical molecular orbital calculations, we have concluded that the dissociation should take place along the S1 surface with an exit channel barrier and also that the energy partitioning is determined at the exit channel.

• Journal of Mechanical Science and Technology
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• v.18 no.7
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• pp.1177-1186
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• 2004

In this paper, the spray atomization characteristics of a gasoline direct-injection injector were investigated experimentally and numerically. To visualize the developing spray process, a laser sheet method with a Nd :YAG laser was utilized. The microscopic atomization characteristics such as the droplet size and velocity distribution were also obtained by using a phase Doppler particle analyzer system at the 5 ㎫ of injection pressure. With the experiments, the calculations of spray atomization were conducted by using the KIVA code with the LISA-DDB breakup model. Based on the agreement with the experimental results, the prediction accuracy of LISA-DDB breakup model was investigated in terms of the spray shapes, spray tip penetration, SMD distribution, and axial mean velocity. The results of this study provides the macroscopic and microscopic characteristics of the spray atomization, and prediction accuracy of the LISA-DDB model.

• Journal of Environmental Science International
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• v.17 no.6
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• pp.699-709
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• 2008

To understand the development mechanism of the aerosols in the surface boundary layer, the variation in the aerosol number concentration due to the divergence and convergence of the wind fields was investigated. The aerosol number concentration was measured in the size ranges of $0.3{\sim}10.0{\mu}m$ using a laser particle counter(LPC) from 0000 LST on 03 Feb. to 0600 LST on 07 Feb. 2004 at Mokpo in Korea during snowfall. The Velocity Azimuth Display(VAD) technique was used to retrieve the radar wind fields such as the horizontal wind field, divergence, and deformations including the vertical air velocity from a single Doppler radar. As a result, the distribution of the aerosol number concentration is apparently different for particles larger than $1{\mu}m$ during snowfall, and it has a tendency to increase at the beginning of the snowfall. The increase and decrease in the aerosol concentration due to the convergence and divergence of the wind fields corresponded to the particles with diameters greater than $1{\mu}m$. It is found that the fluctuations in the aerosol number concentration are well correlated with the development and dissipation of snowfall radar echoes due to the convergence and divergence of horizontal wind fields near the surface boundary layer in the inland during the snowfall.

• Physical Therapy Rehabilitation Science
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• v.2 no.2
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• pp.63-69
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• 2013

Objective: To assess the effect of vitamin D administration on the skin blood flow response to occlusion and heat. Design: Cross-sectional study. Methods: Twenty age matched subjects; 10 who had diabetes and 10 who were controls were administered 4,000 IU of vitamin D3 for 3 weeks at breakfast. The function of the endothelial cells was evaluated in 2 ways; first, the response to 4 minutes of vascular occlusion of the skin was measured with a laser Doppler flow meter. Second, the skin blood flow response to local heat at 42 degrees C for 6 minutes was examined. Results: The results of the experiments showed that the blood flow response to heat was reduced after 3 weeks administration of vitamin D in the subjects with diabetes and in the control subjects (p<0.05). The response to occlusion was not significantly different within each group before and after vitamin D administration, but the group with diabetes had a significantly lower blood flow response to occlusion than did the controls (p<0.05). Conclusions: Acute doses of vitamin D may impair nitric oxide production and reduce blood flow to tissue during stressors in people with diabetes.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.607-611
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• 2006

There are several methods to obtain structural vibration for analysis of vibro-acoustic noise. First of all, vibration data can be obtained through the structural analysis using finite element method. Although this method has no need to experiment, the analysis result is unreliable when the structure and the vibration source is complex to model exactly. The second method is to measure vibration using a number of sensors. The analyzed vibro-acoustic noise with directly measured data is setting morereliable when the number of data acquisition points is getting larger. However, it requires large amount of time and effort to measure all vibration data on every node especially when the size of vibrating structure is large. The Modal Expansion Method(MEM), which uses mode information and measurement data, has been introduced to compensate their limits. With a relatively small number of measurement data, the reliable structural vibration for vibro-acoustic noise can be obtained using this semi-analysis method. Although MEM gives reliable result, it is restricted by the number of modes and measurement points. In this paper, structural analysis, direct vibration measurement method and MEM are compared using the simple aluminum box model. Furthermore, the washing machine case is also provided as a comparative example. The Laser Doppler Vibrometer(LDV) was used instead of contact type accelerometer to get vibration data.

• Archives of Plastic Surgery
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• v.36 no.3
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• pp.254-261
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• 2009

Purpose: The objective of this study was to evaluate the heparin effect for a viability of random - pattern dorsal flap in hairless mouse. Methods: A caudally - based random dorsal flap, measuring $1.5{\times}5cm$, was designed and heparin was applied topically after microneeding. Twenty five male hairless mice were randomly divided into control (Group1, n=5); received only microneedling (Group 2, n=5), only heparin(Group3, n=5), microneedling with saline(Group 4, n=5), and microneedling with heparin group(group5,n=5) to the flap during 7 days. The number of the capillaries were compared between the experimental groups and control group with respect to neovascularization after heparin application using imaging analysis program under hematoxylin - eosin stain. The capillary blood flow was measured by laser Doppler flowmetry. After seven days each animal was evaluated for the percentage area of the flap survival. Mann - Whitnety U test and Kruskal - Wallis statistical analysis of survival relationships was performed. Results: It can be observed increased number of the blood vessels in the experimental groups however it was not statistically significant. Blood flow of the haparin with microneedling group maintained higher than other experimental groups. Treated microneeding and heparin mice were significantly better flap viability than in controls (flap survival 67% and $54.4mm^2$ respectively; p<.01). Positive correlation was shown between flap survival rate and laser Doppler flux value only at first day after surgery. Conclusion: Heparin has a beneficial effect on capillary flow and improve peripheral circulatory disturbances in random pattern flaps.

• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.5
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• pp.522-528
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• 2011

Artificial basilar membranes made of PVDF(polyvinylidene fluoride) are manufactured using microfabrication processes. The mechanical behavior of PVDF artificial basilar membrane was measured to evaluate its performance as a mechanical frequency analyzer using scanning LDV(laser Doppler vibrometer). The experimental setup consists of the microfabricated artificial basilar membrane, a loud speaker connected to an amplifier for generating acoustic pressure of specific spectral pattern, and a scanning LDV with controlling unit for measuring the displacement of the membrane on the incoming acoustic stimulation. The microfabricated artificial basilar membrane was attached tightly upon a package containing a chamber which can be filled with silicone oil before placed on the experimental setup stage. The experiment results showed that the microfabricated artificial basilar membrane has a property as a mechanical frequency analyzer.

• Journal of Physiology & Pathology in Korean Medicine
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• v.27 no.4
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• pp.481-486
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• 2013

To investigate the effects of facial temperature and blood flow rates generated by Miso Facial Rejuvenation Acupuncture treatment. Ten women in their twenties to fifties with no skin diseases were recruited. Miso Facial Rejuvenation Acupuncture(MFRA) was performed on the both sides of their face. We measured their facial temperature using Digital Infrared Thermal Imaging(DITI) and blood flow rates using Laser Doppler Perfusion Imaging(LDPI) at pre-treatment, immediately, twenty and sixty minutes after treatment. We analyzed data using student's t-test(p<0.05). After MFRA treatment, facial temperature on the measurement area increased immediately from $30.5{\pm}1.0^{\circ}C$ to $31.5{\pm}1.0^{\circ}C$, a statistically significant increase. Sixty minutes after treatment, facial temperature on the measurement area decreased a little bit($30.2{\pm}0.6^{\circ}C$), but there was no statistical significance. After MFRA treatment, facial blood flow rates on the measurement area increased immediately from $165.1{\pm}52.3$ PU to $342.7{\pm}51.3$ PU, a statistically significant increase. Sixty minutes after treatment, facial blood flow rates measurement area were recovered almost at the same level as before treatment. MFRA treatment could increase facial temperature and blood flow rates.

• The Korean Journal of Physiology and Pharmacology
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• v.10 no.4
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• pp.167-172
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• 2006

In the present study, we developed a simple method to predict the neuronal cell death in the mouse hippocampus and striatum following transient global forebrain ischemia by evaluating both cerebral blood flow and the plasticity of the posterior communicating artery (PcomA). Male C57BL/6 mice were anesthetized with halothane and subjected to bilateral occlusion of the common carotid artery (BCCAO) for 30 min. The regional cerebral blood flow (rCBF) was measured by laser Doppler flowmetry. The plasticity of PcomA was visualized by intravascular perfusion of India ink solution. When animals had the residual cortical microperfusion less than 15% as well as the smaller PcomA whose diameter was less than one third compared with that of basilar artery, neuronal damage in the hippocampal subfields including CA1, CA2, and CA4, and in the striatum was consistently observed. Especially, when mice met these two criteria, marked neuronal damage was observed in CA2 subfield of the hippocampus. In contrast, after transient BCCAO, neuronal damage was consistently produced in the striatum, dependent more on the degree of rCBF reduction than on the plasticity of PcomA. The present study provided simple and highly reproducible criteria to induce the neuronal cell death in the vulnerable mice brain areas including the hippocampus and striatum after transient global forebrain ischemia.