• Journal of Electrical Engineering and Technology
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• v.10 no.4
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• pp.1400-1407
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• 2015

This paper deals with methodology to control an automatic substation system. The control system can predict the power system condition by a voltage stability index (VSI). The strategies in this paper is called as Voltage-Reactive Power Control (VRPC), which regulates an abnormal voltage of a target substation by using coordination between tap changers and shunt capacitor/reactor. This method is efficient for better voltage profile. The monitoring substation includes whole of substations around the contingency event. The control quantities of the monitoring substations are decided by the calculation of the VSI, called as a Z-index. Case studies with BC Hydro-Quebec system are presented to illustrate this approach using real-time simulator.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.12
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• pp.1051-1057
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• 2000

A traveling-wave CPW(coplanar waveguide) electrode with abruptly broken input/output-taper for LiNbO$_3$optical modulator was designed and fabricated. The electrical characteristics of traveling-wave electrode on z-cut LiNbO$_3$crystal with SiO$_2$buffer layers were measured by network analyzer. To confirm the possibility of the electro-optic modulator electrode, detailed calculations of the impedance, microwave effective index and attenuation constants are presented as a function of the microwave electrode thickness, but the buffer layer thickness is fixed as 1${\mu}{\textrm}{m}$. These characteristics are discussed from the viewpoint of the device optimization and are expected to be design guides for the LiNbO$_3$modulator’s electrodes.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.34 no.2
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• pp.61-66
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• 2002

This study was carried out to investigate sheet properties of Indian mallow hanji, made by different pulping methods such as alkali and sulfomethylated pulpings, and different stock compositions, various mixing ratios of bast fiber and woody core fibers. Effect of morphological properties of pulp stocks on the sheet formation and their optical properties were also evaluated using an image analyzer and confocal laser scanning microscope(CLSM). In addition, the effect of fiber distribution index(FDI), which was calculated based on the image in a z-direction of a sheet from CLSM, on the sheet properties of Indian mallow hanji was discussed. The proposed FDI had a good correlation with various properties of paper, such as apparent density, opacity, tear index, breaking length and zero-span tensile strength. Especially, sulfomethylated pulp sheets＇FDI was higher than alkali pulp sheets.

• Journal of Acupuncture Research
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• v.37 no.1
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• pp.64-67
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• 2020

The aim of this study was to investigate the efficacy of thread-embedding therapy for the treatment of knee osteoarthritis. There were 20 patients treated with thread-embedding therapy at various acupoints on the muscles around the knee. Gender, age, location, morbidity period, numeric rating scale (NRS), Western Ontario and McMaster Universities (WOMAC) index, improvement result, side effects, and patient's satisfaction were investigated. After the treatment, the NRS score (z = -4.07, p < 0.001) and WOMAC (p < 0.001) indices decreased in most patients. The NRS score decreased by more than 2 points in 95% of the patients. The WOMAC index decreased by 6-12 points. There were no serious side effects, although bruising, pain, and edema were observed. Overall, 85% of the patients felt satisfied with the thread-embedding therapy. These findings suggested that thread-embedding therapy was effective and may be used widely for knee osteoarthritis.

• Journal of the Korean Society of Safety
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• v.33 no.1
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• pp.142-147
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• 2018

This study aims to analyze and discuss the accidents based on the level of traffic culture (LOT). In pursuing the above, LOT are divided into three categories based on the standardized index of traffic culture. Also, this study focuses on developing the accident models using GLM (generalized linear model). The main results are as follows. First, the null hypotheses that the ratios of fatal and serious injured persons (FSI) are the same over categories are rejected. Second, as the common variables, the ratio of turn signal usage and elderly population are analysed to be impacted to the ratio of FSI. Third, the traffic culture indicators among 5 accident factors which give impact to 'high level' are judged to affect the reduction of FSI. Fourth, compared to other levels, the traffic law violations among 7 accident factors of 'medium level' are estimated to influence the increase of FSI. Finally, in 'low level', the increasing ratio of traffic culture index compared to that of previous year and the number of hospital beds per person are evaluated to be significant to reducing the ratio of FSI. This study can be expected to give some policy implications to regional traffic safety policy-making.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.68.3-68.3
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• 2016

We analyze the dependence of environment of warped galaxies by using the local background density, Tidal Index and projected distance as measures of the environment. we use galaxies with redshift less than z=0.025 from the Sloan Digital Sky Survey (SDSS) DR7. We selected 345 edge-on galaxies using color images provided by the SDSS DR7 and checked it using isophotal maps. This sample contains 136 warped galaxies, 209 non-warped galaxies. Among warped galaxies, there are 18 strongly warped galaxies which have warp angles larger than 7.5o. We calculated the fractional distributions of galaxies as a function of environmental parameters. All of these parameters show little difference between warped galaxies and non-warped galaxies if we include weakly warped galaxies. However, there is a clear difference in the fractional distributions between the strongly warped galaxies and non-warped galaxies. The fraction of warped galaxies increases with decreasing distance to the nearest neighbor galaxy but It increases with increasing background density and Tidal Index. However, the relationships between warp angles and the three environmental parameters are not strong. The effect of Tidal Index is well distinguished in small, bright galaxies whereas the effects of the background density and the distance to the nearest neighbor galaxy are more pronounced in large, bright galaxies.

• Korean Journal of Materials Research
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• v.31 no.7
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• pp.382-385
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• 2021

Well-crystallized vanadium pentoxide V₂O₅ thin films are fabricated on MgO single crystal substrates by using pulsed-laser deposition technique. The linear optical transmission spectra are measured and found to be in a wavelength range from 300 to 800 nm; the data are used to determine the linear refractive index of the V₂O₅ films. The value of linear refractive index decreases with increasing wavelength, and the relationship can be well explained by Wemple's theory. The third-order nonlinear optical properties of the films are determined by a single beam z-scan method at a wavelength of 532 nm. The results show that the prepared V₂O₅ films exhibit a fast third-order nonlinear optical response with nonlinear absorption coefficient and nonlinear refractive index of 2.13 × 10^-10 m/W and 2.07 × 10^-15 cm²/kW, respectively. The real and imaginary parts of the nonlinear susceptibility are determined to be 3.03 × 10^-11 esu and 1.12 × 10^-11 esu, respectively. The enhancement of the nonlinear optical properties is discussed.

• Physical Therapy Rehabilitation Science
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• v.11 no.1
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• pp.105-112
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• 2022

Objective: Nonspecific low back pain (NS-LBP) causes pain and disability, affecting the neuromuscular system and altering gait patterns. The purpose of this study is to investigate the effect of improvement of low back pain symptoms through physical therapy on foot pressure and spatiotemporal gait parameters. Design: A pilot study. Methods: Participants received manual therapy and supervised therapeutic exercise, which consisted of 12 sessions for 6 weeks. Participants were assessed for pain intensity (a numeric pain rating scale), disability index (oswestry disability index), and spatiotemporal gait parameters before and after intervention. Wilcoxon signed rank test was used to analyze the before-and-after differences in a single group. Results: All seven NS-LBP patients completed the study without dropout. After six weeks of physical therapy, the numeric pain rating scale and oswestry disability index showed significant improvement (Z= -2.388, P=0.017). There was no significant improvement in both static and dynamic conditions in foot pressure (P>0.05). However, in the spatiotemporal gait parameters, there were significant differences in all variables except the right stance phase and left mid stance (P<0.05). Conclusions: In our pilot study, 12 sessions of physical therapy in NS-LBP patients improved gait quilty in spatiotemporal gait parameters. Similarly, it has resulted in clinically positive improvements in pain and disability.

• Journal of Preventive Medicine and Public Health
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• v.43 no.2
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• pp.174-184
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• 2010

Objectives: This study shows the issues that should be considered when applying standardized rates using Community Health Survey(CHS) data. Methods: We analyzed 2008 CHS data. In order to obtain the reliability of standardized rates, we calculated z-score and rank correlation coefficients between direct standardized rate and indirect standardized rate for 31 major indices. Especially, we assessed the change of correlations according to population composition (age and sex), and characteristics of the index. We used Mantel-Haenszel chi-square to quantify the difference of population composition. Results: Among 31 major indices, 29 indices' z-score and rank correlation coefficients were over 0.9. However, regions with larger differences in population composition showed lower reliability. Low reliability was also observed for the indices specific to subgroups with small denominator such as 'permanent lesion from stroke', and the index with large regional variations in age-related differences such as 'obtaining health examinations'. Conclusions: Standardized rates may have low reliability, if comparison is made between areas with extremely large differences in population composition, or for indicies with large regional variations in age-related differences. Therefore, the special features of standardized rates should be considered when health state are compared among areas.

• Korean Journal of Acupuncture
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• v.28 no.3
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• pp.63-71
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• 2011

Objectives : The aim of this study is to develop the system and evaluate the optical analytical technique that reflects acupoint pigmentation and extravasated blood by cupping. Methods : We designed the system able to express XYZ coordinate on local skin color. To evaluate measurement-accuracy, we compared with 24 Color Checker Chart by standardized Commission Internationale de l'Eclairage. After confirming the performance of system, we experimented with cupping which was 80 kPa negative pressure for 1 minute on left/right BL13. The X, Y and Z values were converted to R, G and B, $L^*$, $a^*$ and $b^*$, Erythema Index (E.I.), and Melanin Index (M.I). We compared and analyzed two cases on before/after cupping. Results : The R, G and B values which were converted by X, Y and Z values had high linearity as a high level of R-square (R: 0.969, G: 0.996, and B: 0.992). Moreover, we confirmed that it was possible to quantitatively analyzed the change in skin color by cupping using R, G, B, $L^*$, $a^*$, $b^*$, E.I., and M.I. Conclusions : Therefore, we proposed the new analytical technique for objectifying the oriental medical diagnostic method using cupping and optical sensing technique.