• Journal of Photoscience
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• v.4 no.3
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• pp.97-103
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• 1997

The effect of temperature on the fluorescence quenching of 2-(4-Methoxyphenyl)-5-(1-naphthyl)-1,3,4-oxadiazole (MPNO1), 2-(4-Methoxyphenyl)-5-(2-naphthyl)-1,3,4-oxadiazote(MPNO2), by aniline, and 2-Phenylindole (2-PI) by CCk, in toluene by steady state method and in benzene by time-resolved method have been carried out in the temperature range 30 - 70$\circ$C. The Stem-Volmer (S-V) plots, I$_0$/I against quencher concentration [Q] at different temperanares show positive deviations. The fluorescence lifetimes determined at different temperatures show no systematic variations and the variations being within the experimental error, the average values of lifetimes $ $\tau$ (t) are taken for further calculations. Rate constants such as Stem-Volmer quenching constants K$_sv}$, quenching rate parameters k$_q$ and k'$_q$, static quenching constant V and kinetic distance r are determined using the modified Stem-Volmer equation and sphere of action static quenching model. In order to see whether the reactions are diffusion limited, equations k$_q$ = e$^{-Eq/RT}$ and k'$_q$ = e$^{-Eq/RT}$ are used to determine the values of E$_q$ and E'$_q$, the activation energies for collisional quenching and the values of E$_q$ are 14.53. 17.28 and 16.20 kJ mole$^{-1}$ for MPNO1, MPNO2 and 2-PI respectively and the values of E'$_q$ are 14.62 and 17.73 for MPNO1 and MPNO2 respectively. From the magnitudes of various quantities it has been concluded that the reactions are diffusion limited and the observed positive deviations in the S-V plot are due to static and dynamic quenching.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.10C
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• pp.921-926
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• 2006

The Presence of a line-of-sight(LoS) blockage can degrade the UWB positioning accuracy for two reasons. Firstly, it makes estimation of the time of arrival(ToA) of the direct path signal difficult by complicating the multipath structure of the propagation channel. Secondly, the higher dielectric constant of the LoS blocking material than that of free space introduces excess propagation delay which will bias the range estimation. In this paper, methods based on ray tracing to reduce the ranging error resulting from the second reason are Posed. We take two different approaches; a statistical approach and a map-aided method. In the statistical approach, we establish a conditional distribution of the excess propagation delay caused by LoS blockages using a ray tracing technique. The lo6wer bound of the ranging performance based on this model is estimated. Ine ray tracing method is also used for the map-aided ToA positioning approach. UWB propagation measurement data taken in an office environment is used to examine the performance of this method.

• Journal of the Korean Society of Radiology
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• v.8 no.1
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• pp.19-26
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• 2014

This paper suggests techniques to enhance coding time which is a problem in traditional fractal compression and to improve fidelity of reconstructed images by determining fractal coefficient through adaptive selection of block approximation formula. First, to reduce coding time, we construct a linear list of domain blocks of which characteristics is given by their luminance and variance and then we control block searching time according to the first permissible threshold value. Next, when employing three-level block partition, if a range block of minimum partition level cannot find a domain block which has a satisfying approximation error, we choose new approximation coefficients using a non-linear approximation of luminance term. This boosts the fidelity. Our experiment employing the above methods shows enhancement in the coding time more than two times over traditional coding methods and shows improvement in PSNR value by about 1-3dB at the same compression rate.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.3_1spc
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• pp.537-543
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• 2013

A water-$Al_2O_3$ nanofluid was manufactured, and its thermal conductivity was measured in this study. The measurement was performed at volumetric concentrations of 0.5%, 1%, 2%, and 3%, and the nanoparticle sizes were 20 nm and 70 nm. Experimental test equipment, using the transient hot wire method, was installed to measure the thermal conductivity of the nanofluid, and the measured results were confirmed by measuring pure water with a measurement error of 0.92% at $20^{\circ}C$. The thermal conductivity enhancement ranged from 4.8% to 13.6% for the 20 nm particle size, and from 3.1% to 8.8% for the 70 nm particle size at a concentration range of 0.5% to 3%. The enhancement increased with a decrease in particle size and an increase in concentration. With the elapse of time after manufacturing the nanofluid, the thermal conductivity enhancement decreased significantly from 5 to 9 h, and this trend was measured under all of the measurement conditions. After 24 h, the enhancement ranged from 1.2% to 3.5% for the 20 nm particles, and from 0.6% to 2.3% for the 70 nm particles. The enhancement trends with the elapse of time were almost identical with and without stirring the nanofluid. SDBS (Sodium Dodecyl Benzene Sulfonate) was added as a dispersing agent, and the decrease in the thermal conductivity enhancement was delayed.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.2 s.107
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• pp.163-168
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• 2006

The PWR Nuclear Fuel assembly consists of more than 250 fuel rods that are supported by leaf springs in the cells of more than 10 Spacer Grids (SG) along the rod length. Since it is not easy to conduct mechanical tests on a full-scale model basis, the small-scaled rod bundle $(5\times5)$ which is called partial fuel assembly is generally used for various performance tests during the development stage. As one of the small-scaled tests, a flow test should be carried out in order to verify the performance of the spacer grid to obtain the Flow-Induced Vibration (FIV) characteristics of the scaled fuel assembly over the specified flow range. A vibration test should be also performed to obtain the modal parameters of the assembly prior to the flow test. In this study, we want to develop the estimation procedure of the damping ratio for the scaled test assembly. For the damping factor of the partial fuel assembly and the grid cage at the first vibration mode, as one of the vibration tests, a so-called pluck testing has been performed in air as a preliminary test prior to in-flow damping measurement test. Logarithmic decrement method is used for calculation of the damping ratio. Estimated damping ratio of the partial fuel assembly is about $0.7\%$ with reasonable error of $2\%$ for the previous results. Nonlinear behavior of the partial fuel assembly might be stem mainly from the rod-grid support configuration.

• Journal of the Korean Society for Nondestructive Testing
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• v.29 no.3
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• pp.248-255
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• 2009

After several damages by PWSCC were found in the world, USNRC and PNNL(Pacific Northwest National Laboratory) started the research on PWSCC under the project name of PINC. The aim of the project was 1) to fabricate representative NDE mock-ups with flaws to simulate PWSCCs, 2) to identify and quantitatively assess NDE methods for accurately detecting, sizing and characterizing PWSCCs, 3) to document the range of locations and morphologies of PWSCCs and 4) to incorporate results with other results of ongoing PWSCC research programs, as appropriate. Korea nuclear industries have also been participating in the project. Thermally and mechanically cracked-four mockups were prepared and phased array and manual ultrasonic testing(UT) techniques were applied. The results and lessons learned from the preliminary RRT are summarized as follows: 1) Korea RRT teams performed the RRT successfully. 2) Crack detection probability of the participating organizations was an average 87%, 80% and 80% respectively. 3) RMS error of the crack sizing showed comparatively good results. 4) The lessons learned may be helpful to perform the PINC RRT and PSI /ISI in Korea in the future.

• Journal of The Korean Society of Grassland and Forage Science
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• v.34 no.3
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• pp.209-213
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• 2014

This study was carried out to explore the accuracy of near infrared spectroscopy (NIRS) for the prediction of chemical and fermentation parameters of whole crop winter rye silages. A representative population of 216 fresh winter rye silages was used as database for studying the possibilities of NIRS to predict chemical composition and fermentation parameters. Samples of silage were scanned at 1 nm intervals over the wavelength range 680~2,500 nm and the optical data recorded as log 1/Reflectance (log 1/R) and scanned in fresh condition. NIRS calibrations were developed by means of partial least-squares (PLS) regression. NIRS analysis of fresh winter rye silages provided accurate predictions of moisture, acid detergent fiber (ADF), neutral detergent fiber (NDF), crude protein (CP) and pH as well as lactic acid content with correlation coefficients of cross-validation ($R^2cv$) of 0.96, 0.86, 0.79, 0.85, 0.82 and 0.78 respectively and standard error of cross-validation (SECV) of 1.89, 2.02, 2.79, 1.14, 1.47 and 0.46 % DM respectively. Results of this experiment showed the possibility of NIRS method to predict the chemical parameters of winter rye silages as routine analysis method in feeding value evaluation and for farmer advice.

• Journal of radiological science and technology
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• v.18 no.2
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• pp.61-73
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• 1995

For the managements of the diagnostic X-ray equipments, the authors examined the output of single phase rectification assembly, Three phase rectification assembly and serial radiographic appartus, and got the following conclusions. 1. When the tube voltages in X-ray control panels ware compared to the measured values on the kVp pulse meter, only little differences were detected in all the X-ray equipments. And most of the equipments were all well managed within the internationally permitted limits, excepting the 12.02 % error at 120 kVp in three phase rectifying assembly. 2. As for the X-ray qualities affecting the X-ray images, the serial radiographic apparatus showed excellence, while the single phase rectification assembly were somewhat inferior to the others only maining the internationally recommended limits. 3. The tube voltage ranges where the X-ray output showed excellence were $100{\sim}200\;mA$ in serial radiographic apparatus, $200{\sim}350\;mA$ in three phase rectification assembly and $350{\sim}400\;mA$ in single phase rectification assembly respectively. 4. In the repeatability test of the X-ray equipments, CVs were in the range of $0.0029{\sim}0.049$, which is within the HEW or KS standards. Consequently all the equipments are thought to be well-manage. 5. This study on characteristics and output of the X-ray equipments was accomplished within a limited short time. Long-time researches on the function managements for the X-ray equipments should be followed along with the periodical checking the output for reduction of X-ray exposures to the patients or radio-technologists, and for maintanance and prediction of trouble of the equipments.

• Communications for Statistical Applications and Methods
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• v.25 no.4
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• pp.341-354
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• 2018

The one of the principles described in ICH E9 is that only results obtained from pre-specified statistical methods in a protocol are regarded as confirmatory evidence. However, in multi-regional clinical trials, even when results obtained from pre-specified statistical methods in protocol are significant, it does not guarantee that the test treatment is approved by regional regulatory agencies. In other words, there is no so-called global approval, and each regional regulatory agency makes its own decision in the face of the same set of data from a multi-regional clinical trial. Under this situation, there are two natural methods a regional regulatory agency can use to estimate the treatment effect in a particular region. The first method is to use the overall treatment estimate, which is to extrapolate the overall result to the region of interest. The second method is to use regional treatment estimate. If the treatment effect is completely identical across all regions, it is obvious that the overall treatment estimator is more efficient than the regional treatment estimator. However, it is not possible to confirm statistically that the treatment effect is completely identical in all regions. Furthermore, some magnitude of regional differences within the range of clinical relevance may naturally exist for various reasons due to, for instance, intrinsic and extrinsic factors. Nevertheless, if the magnitude of regional differences is relatively small, a conventional method to estimate the treatment effect in the region of interest is to extrapolate the overall result to that region. The purpose of this paper is to investigate the effects produced by this type of extrapolation via estimations, followed by hypothesis testing of the treatment effect in the region of interest. This paper is written from the viewpoint of regional regulatory agencies.

• Korean Journal of Applied Biomechanics
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• v.19 no.1
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• pp.59-66
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• 2009

The purpose of this study was to evaluate flatness of swing plane and determine swing plane type using 3-D swing plane analysis from young elite male golf players. This study also investigate the possibility of determination of swing plane using other kinematic parameters except flatness. As results, no correlations was found between flatness and handicap. Comparison of flatness between single plane and multiple plane swing group were performed and found a significant difference. The error range of flatness, 10cm, which was used for distinguish swing plane type was effective since significant differences were found at MB, EB, and EF. These differences were typical characteristics to classify two swing styles. Other kinematic parameters such as unit vector components of shaft and displacement of shaft end point also compared per event but found no significant differences. However, the moving patterns of these parameters during a golf swing showed such characteristics of each swing plane type well that these parameters could be used to determine swing style as an indirect barometers.