• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.5
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• pp.368-373
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• 2010

In this study, we have investigated the effects of Cr dopant on the bulk trap levels and grain boundary characteristics of $Bi_2O_3$-based ZnO (ZB) varistor using admittance spectroscopy and dielectric functions (such as $Z^*,\;Y^*,\;M^*,\;{\varepsilon}^*$, and $tan{\delta}$). Admittance spectra show more than two bulk traps of $Zn_i$ and $V_o$ probably in different ionization states in ZnO-$Bi_2O_3-Cr_2O_3$ (ZBCr) system. Three kinds of temperature-dependant activation energies ($E_{bt}'s$) were calculated as 0.11~0.14 eV of attractive coulombic center, 0.16~0.17 eV of $Zn_{\ddot{i}}$, and 0.33 eV of $V_o^{\cdot}$ as dominant bulk defects. The grain boundaries of ZBCr could be electrochemically divided into two types as a sensitive to ambient oxygen i.e. electrically active one and an oxygen-insensitive i.e. electrically inactive one. The grain boundaries were electrically single type under 460 K (equivalent circuit as parallel $R_{gb1}C_{gb1}$) but separated as double one ($R_{gb1}C_{gb1}-R_{gb2}C_{gb2}$) over 480 K. It is revealed that the dielectric functions are very useful tool to separate the overlapped bulk defect levels and to characterize the electrical properties of grain boundaries.

• Journal of Korea Society of Industrial Information Systems
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• v.18 no.4
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• pp.9-18
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• 2013

Flash memory is mostly used on smart devices and embedded systems because of its nonvolatile memory, low power, quick I/O, resistant shock, and other benefits. Generally the typical file systems base on the NAND flash memory are YAFFS2, JFFS2, UBIFS, and etc. In this paper, we had variously made an experiment regarding I/O performance using our schemes and the UBIFS of the latest Linux Kernel. The proposed I/O performance analyses were classified as a sequential access and a random access. Our experiment consists of 6 cases using kmalloc(), vmalloc(), and kmem_cache(). As a result of our experiment analyses, the sequential reading and the sequential rewriting increased by 12%, 11% when the Case 2 has applied vmalloc() and kmalloc() to the UBI subsystem and the UBIFS. Also, the performance improved more by 7.82%, 6.90% than the Case 1 at the random read and the random write.

• Transactions on Electrical and Electronic Materials
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• v.16 no.5
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• pp.285-289
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• 2015

We prepared silver Schottky contacts to O-polar and nonpolar m-plane bulk ZnO wafers. Then, by considering various transport models, we performed a comparative analysis of the current transport properties of Ag/bulk ZnO Schottky diodes, which were measured at 300, 200, and 100 K. The fitting of the forward bias current-voltage (I-V) characteristics revealed that the tunneling current is dominant as the transport component in both the samples. Compared to thermionic emission (TE), a stronger contribution of tunneling current was observed at low temperature. The reverse bias I-V characteristics were well fitted with the thermionic field emission (TFE) in both the samples. The presence of acceptor-like adsorbates, such as O₂ and H₂O, modulated the surface conductive state of ZnO, thereby affecting the tunneling effect. The degree of activation/passivation of acceptor-like adsorbates might be different in both the samples owing to their different surface morphologies and surface defects (e.g., oxygen vacancies).

• Bulletin of the Korean Chemical Society
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• v.27 no.5
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• pp.687-693
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• 2006

Chromium(III) complexes, cis-[Cr([14]-decane)$(HOC _6H _4COO) _2$]$ClO _4$ I and cis-[Cr([14]-decane)(OH) $(OC _6H _4NO _2)$]$ClO _4{\cdot}H _2O$ II ([14]-decane = rac-5,5,7,12,12,14-hexamethyl-1,4,8,11-teraazacyclotetradecane) are synthesized and structurally characterized by a combination of elemental analysis, conductivity, IR and VIS spectroscopy, and X-ray crystallography. The complexes crystallizes in the monoclinic space groups, $C2 _1$/a in I and $P2 _1$/n in II. Analysis of the crystal structure of complex I reveals that central chromium(III) ion has a distorted octahedral coordination environment and two hydrogensalicylato ligands are unidentate to the chromium(III) ion via the carboxyl groups in the cis-position. For monomeric complex I the hydrogensalicylato coordination geometry is as follows: Cr-O(average) = 1.984(3) $\AA$;Cr-N range = 2.105(3)-2.141(4) $\AA$;C(24)-O(4) = 1.286(5) $\AA$;N(2)-Cr-N(4) (equatorial position) = 96.97(15)${^{\circ}}$; N(1)-Cr-N(3) (axial position) = 168.27(15)${^{\circ}}$; O(1)-Cr-O(4) = 85.70(13)${^{\circ}}$. The crystal structure of II has indicated that chromium(III) ion is six-coordinated by four secondary amines of the macrocycle, hydroxide anion and nitrophenolate anion.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.1
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• pp.89-94
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• 2007

High duality BiSrCaCuO thin films fabricated by using the i-beam sputtering method at various substrate temperatures, $T_{sub}$ and oxidation gas pressures, $pO_3$. The correlation diagrams of the BiSrCaCuO phases with Tsub and $pO_3$ are established in the 2212 and 2223 compositional films. In spite of 2212 compositional sputtering, Bi2201 and Bi2223 as well as Bi2212 phases come out as stable phases depending on $T_{sub}$ and $pO_3$. From these results, the thermodynamic evaluation of ${\Delta}H$ and${\Delta}S$, which are related with Gibbs' free energy change for single Bi2212 or Bi2223 phase, was performed.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10b
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• pp.1764-1769
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• 1991

Recently, dexterous mechanical hands have become of interest in the field of robotics. In this paper, a new symbolic C-Y notation is proposed for the kinematic modeling, and we solve the kinematics of a simplified model of POSTECH Hand 1, which is a 5 fingered, 20 degrees of freedom anthropomorphic hand. POSTECH Hand I is designed to have distinctive kinematic structure and the kinematic analysis of the hand is carried out using C-Y notation. To prove the feasibility of C-Y notation, D-H notation is also applied to the POSTECH Hand 1. In the inverse kinematic analysis, we neglect the fingertip geometry and assume the point contact with 3 degrees of freedom constraints. The configurations which optimize manipulability index[2] was obtained based on the simulation experiments on the SUN-4 graphic workstation using SUNPhigs graphic software.

• Journal of the Korean Ceramic Society
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• v.35 no.10
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• pp.1113-1119
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• 1998

Crystal structure of needle-shaped maghemite(${\gamma}$-{{{{ { {Fe }_{2 }O }_{3 } }}) has been studied by the Rieveld analysis of powder X-ray diffraction patterns. The tetragonal space group P41,.3212 and cubic space group P41,.32 have been have been used for the refinement of X-ray diffraction patterns. The crystal system of maghemite is closed to tetragonal more than cubic. The tetragonal lattice parameters are a=8.3460$\AA$ and c=25.034$\AA$ The standard X-ray diffraction pattern of the tetragonal maghemite analyzed with space group P41,.3212 is proposed.

• 제어로봇시스템학회:학술대회논문집
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• 1989.10a
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• pp.1028-1034
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• 1989

A method of analysis of the steady-state performance of induction motor with supply voltage controlled by cyclically-triggered inline thyristors is presented. Phase-variable model and asymmetrical components are not used in this analysis. Instead, Fast Fourier Transform technique and the method of multiple reference frames are employed to obtain the constant-speed performance of I.M. easily.

• Journal of Chest Surgery
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• v.28 no.1
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• pp.7-10
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• 1995

Mixed Venous oxygenation saturation[SvO2 is a variable determined in part by the externally controlled factors and in part by the patient during CPB. I monitored the SvO2 and tested it as a parameter for the regulation of pump output and as a criteria for the need of inotropics after CPB. With the help of SvO2, I increased the pump flow especially during rewarming for more optimal oxygenation of cells. After CPB, the calculated cardiac index was used as an indicator for the need of inotropic support with greater accuracy and without any clinical problems. I conclude that the SvO2 is an easily checkable variable and a good indicator for optimal oxygenation at cell level, and can be used as an objective criteria for the need of postoperative inotropic support.

• Journal of Distribution Science
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• v.13 no.12
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• pp.85-94
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• 2015

Purpose - The purpose of this paper is to provide a political registration point for analyzing the economic impacts on the national economy from the REITs distribution industry in our country. The REITs distribution industry was introduced in 2001 to accelerate the corporate restructuring process and advance the real estate market. During its establishment, the REITs distribution industry faced difficulties; however, the industry grew rapidly through interest from institutional investors, thus mitigating the establishment problems by 2006. In Korea, more than 108 REITs were operating as of the end of June 2015. REITs contribute significantly to the national economy. The economic impacts on the national economy of the REITs distribution industry was analyzed using input-output (I-O) analysis with respect to production, imports, value-added, and employment. Research design, data, and methodology - The research used an I-O analysis of the activities of the REITs distribution industry in the national economy. The I-O analysis methodology analyzes the economic effects that influence other industries with respect to one unit of external investment. The data for this analysis were the I-O table of 2013 as published by the Bank of Korea in 2014. Results - The findings of this study are as follows. First, if an external input to the REITs distribution industry is 1 won, the overall impact of the product is 1.3869 won, the import induction is 0.0002 won, and the value-added induction is 0.7656 won. A new investment of 659.9 billion won into the REITs industry was estimated to produce a gross effect of 915.2 billion won. Second, if an external input to the REITs distribution industry is 1 billion won, the employment-inducing effects are estimated at 19.6394 individuals. The employment-inducing coefficient of 19.6394 for the REITs distribution industry indicates that the industry created significant employment-more than other industries-because the coefficient was 2.2 times the 2013 industry average employment-inducing coefficient of 8.8. Third, the investment effects of the REITs distribution industry on production induction, value-added induction, and employment induction are assumed to be large in business support services, financing, communications and broadcasting, and professional, scientific, and technical services. Conclusions - The REITs distribution industry was analyzed as having a strong employment inducing, high value added effect. The REITs distribution industry is an excellent alternative for the government authority to create multilateral jobs. Because the REITs distribution industry has a significant positive impact on the national economy, it should be developed. However, the I-O methodology has restrictions with respect to the fixation and timing of the input coefficient. Follow-up research is expected to supplement the analysis method at a specific point in time.