• 순환기질환의공학회:학술대회논문집
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• 2006.04a
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• pp.28-36
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• 2006

The x-ray PIV method was improved for measuring quantitative velocity fields of real blood flows using a coherent synchrotron x-ray source. Without using any contrast media or seeding particles, this method can visualize flow pattern of blood by enhancing the phase-contrast and interference characteristics of blood cells based on a synchrotron x-ray imaging mechanism. The enhanced x-ray images were achieved by optimizing the sample-to-scintillator distance, the sample thickness, and hematocrit. The quantitative velocity fields of blood flows inside opaque tubes were obtained by applying a 2-frame PIV algorithm to the x-ray images of the blood flows. The measured velocity field data show typical features of blood flows such as the yield stress effect. The non-Newtonian flow characteristics of blood flows were analyzed using the x-ray PIV method and the experimental results were compared with hemodynamic models.

• Journal of the Korea Furniture Society
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• v.19 no.2
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• pp.151-155
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• 2008

An experiment was conducted to observe the 5% CCFZ solution penetration depth through ray parenchyma and ray tracheid of Larix kapempferi. Moisture content was adjusted 28% for both sapwood and heartwood. Even though the moisture content was same, heartwood was 1.3 times less permeable than sapwood and the difference was found statistically significant. Due to anatomical differences between ray parenchyma and ray tracheid, ray parenchyma was about 1.3 times more permeable than ray tracheid. Penetration speed was high initially and it decreased rapidly in course of time.

• 한국정보통신설비학회:학술대회논문집
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• 2007.08a
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• pp.251-255
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• 2007

In this paper, propagation analysis method in using 3D Ray Tracing propagation model in wireless cell planning is proposed. Through 3D Ray Tracing model, we can predict the distribution of propagation loss of the received signal. For correct and a low complex analysis, Quad Tree and Pre-Ordering and Hash Function algorithms are included in 3D Ray Tracing algorithm. And 3D Ray Tracing model is embodied in CellTREK that is developed by KT and used to plan Wibro system analysis. In CellTREK, propagation analysis is performed and that result is represented in 3D viewer. In numerical results, it is showed that the proposed scheme outperforms Modified HATA model when comparing with measurement data.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.580-582
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• 2008

The object of this paper is develope the PC based controlled high voltage power supply and studies 1.2kW(120kV, 10mA) pulse power X-ray generator possible to adapt fluoroscopy of Dental CT X-ray generator and industrial X-ray pulse power equipment. The developed pulse power X-ray generator consisted of mono-block tank include X-ray tube and high voltage X-ray power supply circuit and high voltage control unit with RS232C/422 communication port. The PC control program of pulse power X-ray generator uses LabVIEW, and the size of high voltage transformer and high voltage generator is minimized by high voltage high frequency inverter has 100kHz switching frequency. Also this paper shows result of X-ray tube voltage and tube current correspond to variable load.

• International Journal of Vascular Biomedical Engineering
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• v.4 no.1
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• pp.1-8
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• 2006

The x-ray PIV method was improved for measuring quantitative velocity fields of real blood flows using a coherent synchrotron x-ray source. Without using any contrast media or seeding particles, this method can visualize flow pattern of blood by enhancing the phase-contrast and interference characteristics of blood cells based on a synchrotron x-ray imaging mechanism. The enhanced x-ray images were achieved by optimizing the sample-to-scintillator distance, the sample thickness, and hematocrit. The quantitative velocity fields of blood flows inside opaque tubes were obtained by applying a 2-frame PIV algorithm to the x-ray images of the blood flows. The measured velocity field data show typical features of blood flows such as the yield stress effect. The non-Newtonian flow characteristics of blood flows were analyzed using the x-ray PIV method and the experimental results were compared with hemodynamic models.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.41.1-41.1
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• 2014

Clusters of galaxies provide unique laboratories to study astrophysical processes on large scales, and are also important probes for cosmology. X-ray observations are still the best way to find and characterise clusters. The extended ROSAT-ESO flux-limited X-ray (REFLEX II) galaxy clusters form currently the largest well-defined and tested X-ray galaxy cluster sample, providing a census of the large-scale structure of the Universe out to redshifts of z-0.4. I will describe the properties of the survey and the X-ray luminosity function, which led to our recent cosmological constraints on omegaM-sigma8. They tighten the previous constraints from other X-ray experiments, showing good agreements with those from the Planck clusters, but some tension exists with the Planck CMB constraints. The second part of my talk will concern the structure of the local Universe, and the study of the first X-ray superclusters. The density of the clusters reveals an under-dense region in the nearby Universe, which has an interesting implication for the cosmological parameters. Using the X-ray superclusters, that are constructed with a physically motivated procedure, I will show environmental aspects that X-ray superclusters provide, and compare to cosmological N-body simulations.

• 한국가시화정보학회:학술대회논문집
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• 2003.11a
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• pp.83-86
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• 2003

Synchrotron X-ray micro imaging technique was employed to non-invasively monitor the water flow inside xylem vessels in a bamboo leaf. The phase contrast X-ray images clearly visualized plant anatomy and the rise of a water front inside the vessels. Consecutive X-ray images taken for 60 seconds revealed water rise kinetics against gravity in the xylem of a cut dry leaf taken from a bamboo tree. For the first time, traces of water rise, variation of contact angle between water and xylem wall as well as the internal structure of xylem were obtained. In xylem vessels, a repeating flow pattern has a typical flow velocity of $30.7{\mu}m/s$ and faster flow is established intermittently. It is concluded that the transmission type of X-ray micro imaging can be used as a powerful tool to investigate the ascent of sap in the xylem vessels at a resolution higher than that of MRI.

• IEMEK Journal of Embedded Systems and Applications
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• v.7 no.1
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• pp.41-52
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• 2012

Recently, FlexRay was developed to replace controller area network (CAN) protocol in chassis networking systems, to remedy the shortage of transmission capacity and unsatisfactory real-time transmission delay of conventional CAN. FlexRay network systems require correct synchronization and complex scheduling parameters. However, because platform configuration register (PCR) setting and message scheduling is complex and bothersome task, FlexRay is more difficult to implement in applications than CAN protocol. To assist a network designer for implementing FlexRay cluster, this paper presents an analysis of FlexRay platform configuration register and automatic generation program of PCR. To demonstrate the feasibility of the automatic generation program, we evaluated its performance using experimental testbed.

• Korean Journal of Rural Living Science
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• v.7 no.2
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• pp.121-128
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• 1996

This study was performed to define the effects of Far Infrared Ray Radiation Fabrics as summer garments during outdoor work by human trial. One healthy male subject was volunteered for this study. Experimental garments consisted of three kinds of trousers (Cotton, Cotton/linen blended, Far Infrared Ray Radiation Fabric/wool blended) and basic garments (panty, socks, shirts, and dress shirts). The measurements were rectal temp., skin temp., microclimate inside clothing, heart rate, subjective sensation etc. The results were as follows : 1. Rectal temperature showed the lowest in Far Infrared Ray Radiation Fabrics among 3 garments. 2. Skin temperature (forehead, chest abdomen temp.) and mean skin temperature were lower in Far Infrared Ray Radiation Fabrics than in others, especially during early stage of work. 3. Heart rate showed lower value in Far Infrared Ray Radiation Fabrics than in others but there was no significance among the garments. 4. Humidity inside clothing and total weight loss showed the highest value in Far Infrared Ray Radiation Fabrics.

• Journal of Astronomy and Space Sciences
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• v.5 no.2
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• pp.143-158
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• 1988

Since the successful observation by Uhuru, the first astronomical satellite, X-ray astronomy has become one of the rapidly developing fields in astronomy. The scientific results provide us the unique opportunity to understand the high energy nature of X-ray sources. We now know that our galaxy contains many different types of X-ray sources such as the compact X-ray sources, galactic bulge sources in addition to the Sun, the brightest X-ray sources in the sky. In this study we review the general properties of galactic X-ray sources, the characteristics of periodic compact X-ray sources, and bursters as well as the models.