• Composites Research
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• v.31 no.6
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• pp.365-370
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• 2018

One of the critical parameters to improve the output power for triboelectric nanogenerators (TENGs) is the surface charge density. In this work, we modify the tribo-material of TENG by introducing the $TiO_x$ embedded Polydimethylsiloxane (PDMS) in anatase and rutile phase. The effect of dielectric constant and electronic structure of the $TiO_x$ on the capacitance of TENG and the output power as well are discussed. The surface charge density is increased as the control of the dielectric constant in difference weight percent of $TiO_x$ and PDMS. As the results of that, the 5% $TiO_x$ rutile phase and 7% $TiO_x$ anatase phase embedded PDMS exhibit the highest TENG output. The peak value of voltage/current obtained from $TiO_x$ rutile and anatase phase are ${\sim}180V/8.2{\mu}A$ and $211.6V/8.7{\mu}A$, respectively, at the external force of 5 N and working frequency of 5 Hz, which gives over 12-fold and 15-fold power enhancement compared with the TENG based on the pristine PDMS film. This study provides a better understanding for TENG performance enhancement from the materials view.

• Journal of the Korean Physical Society
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• v.73 no.12
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• pp.1834-1839
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• 2018

A tabletop ultrafast soft x-ray has been generated from the laser-produce plasma with a femtosecond pulsed Ti:Sapphire laser. The estimated total flux of Al $K{\alpha}$ is of $2.2{\times}10^9photons/sec$ in $4{\pi}$ radian and the parameters related to the optical performance were obtained. The tungsten/silicon multilayer, flat quartz and bent thallium acid phthalate (TLAP) crystal were used for monochromatization of soft x-ray to refine the aluminum $K{\alpha}$ radiation and compared the respective value of $E/{\Delta}E$. To estimate the size of the x-ray source beam generated by a fs laser, the approximation using the FWHM obtained from the x-ray beam scan near the focal point was discussed, and the size of the diameter was about $9.76{\mu}m$.

• Journal of the Korean Magnetics Society
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• v.10 no.5
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• pp.220-224
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• 2000

Ultra-fine $Co_{1+x}$F $e_{2-}$2x/ $Ti_{x}$ $O_4$ferrite powders have been prepared by the sol-gel method. The crystallographic and magnetic properties of the sample have been investigated by means of x-ray diffraction, Mossbauer spetroscopy and vibrating sample magnetometry. The formation of nano crystallized particles is confirmed. The x-ray diffractions of all samples with various compositions clearly indicate the presence of spinel structure. The Mossbauer spectra could be fitted as the superposition of two sextets due to F $e^{3+}$ A-site and B-site. The IS and QS values nearly constant with substituted Co-Ti contents, whereas $H_{hf}$ of B-site decreases with increasing Co-Ti substitution in $Co_{1+x}$F $e_{2-}$2x/ $Ti_{x}$ $O_4$. The magnetic behaviour of powders shows that the saturation magnetization and the coercivity decrease with increasing x in $Co_{1+x}$F $e_{2-}$2x/ $Ti_{x}$ $O_4$.$.X>.

• Korean journal of food and cookery science
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• v.3 no.1
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• pp.71-77
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• 1987

This study was to investigate the synergistic taste effect between monosodium glutamate(MSG) and 5'-ribonucleotides consisted of disodium 5'-inosinate (IMP) and 5'-guanylate (GMP) as 1:1 ratio. Solvent was distilled water. Sensory evaluation with 10 panelists was performed by using ratio scaling method (magnitude estimation). The results were as follows: 1) Taste intensities were increased, as nucleotides content to MSG increased. 2) Multiple regression analyses were carried out with the taste intensity data as a function of nucleotides content at three concentrations of seasonings, 0.025%, 0.05% and 0.1%. 3) Predicted taste intensities ($Y_P$) were calculated from the regression equation. Also taste intensity ratios ($Y_{TR}$)-$Y_{TR}$=$Y_P$/taste intensity of MSG only-were calculated. 4) The taste intensity ratios ($Y_{TR}$) at three concentrations of seasonings in the same nucleotides contents showed about the same. Therefore, instead of above regression equations, only one multiple regression equation expressing $Y_P$ of nucleotides seasonings could be determined, as functions of nucleotides content and seasoning concentration.

• Korean Journal of Materials Research
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• v.10 no.9
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• pp.607-611
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• 2000

Zr modified $(Ba_{1-x},Sr_x)TiO_3$ thin films as capacitor for high density DRAM were deposited by r.f. magnetron sputtering. The films deposited at various chamber pressure exhibited a polycrystalline structure. The Zr/Ti ratio of the films increased significantly with decreasing the chamber pressure and this variation affected the microstructure and surface roughness of films When chamber pressure increased dielectric constant of the films effected due to decrease of Zr. The thin films prepared in this study show dielectric constant of 380 to 525 at 100KHz. The variation of capacitance and polarization measured as a function of bias voltage suggested that all films were paraelectric phases. Leakage current exhibited smaller value as chamber pressure decrease and the leakage current density of the films deposited above 10mTorr was $10^{-7}~10^{-8}A/cm^2$ order at 200kV/cm. $(Ba_{1-x},Sr_x)(Ti_{1-y},Zr_y)O_3$ thin films in this study appeared to be potential thin film capacitor for high density DRAM.

• Journal of radiological science and technology
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• v.1 no.1
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• pp.44-54
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• 1978

This study was carried out with statistical materials during the last two years of period from Jan. 1975 to Dec. 1976 which presented at radiologic department of 5 hospitals in Seoul City. The primary purpose of this study was to obtained more detailed informations related to the activities of radiologic technologists in diagnostic X-Ray examinations part and to provide some basic materials for managements in activities of then and manpower managements of their organization and practice. From the results of this study, the following conclusions were obtained [1] During two year from the January of 1975 to the December of 1976, total number of case in X-ray examinations were 464,830 case and 22,029 case in 1975 and 24,461 in 1976. And ratio of icreased in X-Ray examinations by year was 11.09 per cent. [2] Regarding the examined portion of X-Ray examination, a great propotion was chest examination as 56.88 per cent. [3] An average, the required time per case in X-Ray exam. was 9.28 minutes and make used of 1.94 sheets of X-Ray film per case in radiography. [4] An average, ratio of increased in X-Ray film by year was 12.71 per cent and ratio of failed film in it was 2.23 per cent. [5] The frequency rate of film size showed the highest distribution of $8"{\times}10"$(28.17%) and the highest distribution of X-Ray film by month was July(8.93%). [6] An average, the amount of activities per a diagnostic X-Ray equipment was 34.92 case and make used of 67.81 sheets of X-Ray film in a day. [7] The mean number of case in X-Ray examinations by radiologic technologists was 29.29 cases and make used of 56.87 sheets of X-Ray film in a day. Also, the average number of case was reading by radiologists was 32.42 case and 62.97 sheets of X-Ray film in a day.

• Korean Journal of Applied Biomechanics
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• v.26 no.3
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• pp.265-272
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• 2016

Objective: The aim of this study was to analyze X-factor, triple X-factor, and the center of pressure (COP) according to the feel of golf driver swing. Method: For this research, 9 golfers from the Korea Professional Golfers' Association (age: $30.11{\pm}2.98yrs$, height: $178.00{\pm}8.42cm$, weight: $76.22{\pm}8.42kg$, experience: $10.06{\pm}3.11yrs$) were recruited to participate in the experiment. Twelve Motion Analysis Eagle-4 cameras were installed and an image analysis was conducted by using the NLT (non-linear transformation) method, and 2 units of Kistler type 5233A dynamometer were used to measure ground reaction force. The sampling ratio was set at 1000 Hz. The golfers each took 10 swings by using their own driver, and chose the best and worse feel from among 10 shots. A paired-sample t-test was used to analyze the results. Results: In regard to feel, no change in head speed, X-factor, and the triple X-factor's X-factor stretch, hip rise, and head swivel, was observed (p>.05). Regarding ground reaction force, a difference was observed between the top of the backswing (p<.05) and impact (p<.05) in the vertical force of the left foot. For COP, a difference was also observed between the mid backswing (p<.001), late backswing (p<.001), and top of the backswing (p<.05) for the right foot X-axis and Y-axis mid follow through (p<.01). Conclusion: It can be reasoned that, irrespective of feel, the head speed, X-factor and triple X-factor's X-factor stretch, hip rise and head swivel did not have an effect on drive distance for domestic golfers, and the vertical reaction force of the left foot and left-right movement span's pressure dispersal of the right foot had an increasing effect on drive distance.

• Electronics and Telecommunications Trends
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• v.10 no.1 s.35
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• pp.113-122
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• 1995

현재 발표된 공간 광스위치 구조들은 전자 스위치 및 전자 통신 분야에서 많이 이용된 Clos, Benes, Banyan, omega, shuffle network 등을 directional coupler switch, TIR(total internal reflection) switch, cross X switch 등 여러가지 단위 광스위치를 이용하여 고안한 것으로 서로 다른 장단점을 갖고 있다. 따라서 4 X 4나 8 X 8, 또는 그 이상의 확장된 광스위치를 제작하기 위해서는 이러한 기존 구조에 대한 조사 및 분석이 선행되어야 한다. 본 논문은 현재 개발되어 발표된 광스위치의 구조들을 조사하여 특성을 비교하였다.

• Communications of the Korean Mathematical Society
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• v.12 no.3
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• pp.701-707
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• 1997

In [8], we introduce the relative root Nielsen number N(f;X, A, c) for maps of pairs of spaces $f : (X, A) \to (Y, B)$. From it, we obtain some immediate consequences of the definition and illustrate it by some examples. We consider the question whether there exists a map $g : (X, A) \to (Y, B)$ homotopic to a given map $f : (X, A) \to (Y, B)$ which has precisely N(f;X, A, c) roots, that is, the minimum theorem for N(f;X, A, c).

• Honam Mathematical Journal
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• v.32 no.1
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• pp.61-71
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• 2010

The aim of this paper is to extend a number of transformation formulas for the four $X_4$, $X_5$, $X_7$, and $X_8$ among twenty triple hypergeometric series $X_1$ to $X_{20}$ introduced earlier by Exton. The results are derived from the generalized Kummer's theorem and Dixon's theorem obtained earlier by Lavoie et al..