• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.9
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• pp.988-993
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• 2004

Luminescence characteristics of Ag-doped ZnO as the quantum dot materials to increasing the efficiency on dye-sensitized solar cells (DSC) have been studied. Ag doped ZnO powder was produced by the self-sustaining combustion process using ultrasonic spraying heating method. Luminescence wavelength region of the ZnO by Ag doping was shifted to longer wavelength. Tn the case of the Ag doped ZnO powder, broad luminescence spectrum centered on 600nm was observed. On the other hand, we compared PL data of RTA treated ZnO:Ag film at various temperatures because the front electrode of solar cell was in need of the sintering process. In XRD and PL data for RTA treated film at the 500$^{\circ}C$ showed good property. And, it was found that the grain size wasn't growing but only optical property was changed. According to the result of XRD, PL, absorption, emission spectrum and DV-X${\alpha}$ used in theoretical calculation, it is considered to be possible to use Ag doped ZnO as quantum dot material for improving DSC efficiency.

• The Journal of Korea Robotics Society
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• v.11 no.3
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• pp.156-162
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• 2016

For the underwater localization, acoustic sensor systems are widely used due to greater penetration properties of acoustic signals in underwater environments. On the other hand, the good penetration property causes multipath and interference effects in structured environment too. To overcome this demerit, a localization method using the attenuation of electro-magnetic(EM) waves was proposed in several literatures, in which distance estimation and 2D-localization experiments show remarkable results. However, in 3D-localization application, the estimation difficulties increase due to the nonuniform (doughnut like) radiation pattern of an omni-directional antenna related to the depth direction. For solving this problem, we added a depth sensor for improving underwater 3D-localization with the EM wave method. A micro scale pressure sensor is located in the mobile node antenna, and the depth data from the pressure sensor is calibrated by the curve fitting algorithm. We adapted the depth(z) data to 3D EM wave pattern model for the error reduction of the localization. Finally, some experiments were executed for 3D localization with the fast calculation and less errors.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.2D
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• pp.95-101
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• 2012

Layout Criteria are developed for an access mode's on and off facility at multiple transfer centers in this paper. Layout Criteria are location issues between a main mode and access modes in terms of the on and off facility one another. The total distance between them has been suggested to be minimized. In the distance calculation stairs are considered to be more difficult and than open space. On the other hand an escalator and an elevator are treated as easier than open space. Considering the number of people between on and off facility, the weighted average distance is suggested to be a MOE(Measure of effectiveness) for layout criteria at multiple transfer centers. Finally, the layout criteria are applied to the existing Kimpo airport terminal and some improvement ideas are suggested.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2006.11a
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• pp.89-96
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• 2006

To estimate the manufacturing district and generation of ancient paper as a cultural property, fiber orientation is one of the criteria. Image analysis using fast Fourier transform with suitable modifications was demonstrated to be an effective means to determine angle and intensity of fiber orientation as a nondestructive method. Binarization process of microscopic images of paper surface and precise calculation for average Fourier coefficients as an angular distribution by linear interpolation were newly introduced in the procedures to improve the accuracy. This analysis method was applied to digital optical micrographs of paper surfaces. Korea and Japanese traditional hand making papers were well distinguished. Korea and Japanese papers made in the traditional ways showed its own characteristic orientation behavior in accordance with the motion of a bamboo wire.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.21 no.3
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• pp.167-180
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• 2017

According to the fact that the low convergence level of the complete elliptic integral of the first kind for the modulus which having values approach to one. In this paper we propose novelty of the complete elliptic integral which having new infinite series that consists of new modulus introduced as own modulus function. We apply scheme of iteration by substituting the common modulus with own modulus function into the new infinite series. We obtained so many new exact formulas of the complete elliptic integral derived from this method correspond to the number of iterations. On the other hand, it has been also obtained a lot of new transformation functions with the corresponding own modulus functions. The calculation results show that the enhancement of the number of significant figures of the new infinite series of the complete elliptic integral of the first kind corresponds to the level of quadratic convergence.

• Journal of Internet Computing and Services
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• v.6 no.2
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• pp.37-47
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• 2005

Most of the methods of estimating the size of software are based on the functions provided to costumers and in the process of granting the score to each function we consider the complexity during the process. The FFP technique has advantages applied to vast areas like data management. real-time system, algorithmic software, etc, but on the other hand, has disadvantage on estimating sizes for weights for necessary function elements. This paper proposes the estimating method for software size by considering the complexity of each function elements in full function point calculation method applied to a new developed project and maintenance projects. For this, based on function point by using surveyed data proved the validity of proposed method. The valid result. was that the function elements, the attributes used in size estimation of software, est mated better estimated sizes than in the case of other weights being applied.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.12A
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• pp.1828-1835
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• 2000

In this paper, we analyzed the other-cell interference characteristics for various non-uniform traffic distributions and their effects on the capacity of multi-cell CDMA system. We consider three different traffic distributions, i.e., linear, exponential and Gaussian traffic distribution with distribution parameters. Changing the distribution parameter, we can obtain the center-focused distributions or uniform distributions for each model. From the results of other-cell interference calculation we can see that the other-cell interference decreases, as the user concentrates on the base station. Also using frequency reuse efficiency indicating the capacity reduction of a multi-cell system when compared to a single cell system, we evaluate the effect of traffic distribution on the reverse link CDMA capacity. For linear case, the capacity of multi-cell system is reduced to 0.637∼0.867 times that of single cell system. On the other hand, for both exponential and Gaussian cases, the capacity under a multi-cell environment is equal to 70∼100% of that under a single cell. Therefore, we conclude that the average capacity of multi-cell CDMA system are increased when users are likely to be at near the cell base station due to reduced total other-cell interference and decreased when users exist at near the cell edge regardless of traffic distribution models.

• Geomechanics and Engineering
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• v.14 no.4
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• pp.355-366
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• 2018

One of the significant problems in the design of onshore pipelines in seismic areas is their stability in case of liquefaction. Several model tests and numerical analyses allow investigating the behavior of pipelines when the phenomenon of liquefaction occurs. While experimental tests contribute significantly toward understanding the liquefaction mechanism, they are costly to perform compared to numerical analyses; on the other hand, numerical analyses are difficult to execute, because of the complexity of the soil behavior in case of liquefaction. This paper reports an overview of the existing computational methods to evaluate the stability of onshore pipelines in liquefied soils, with particular attention to the development of excess pore water pressures and the floatation of buried structures. The review includes the illustration of the mechanism of floating and the description of the available calculation methods that are classified in static and dynamic approaches. We also highlighted recent trends in numerical analyses. Moreover, for the static condition, referring to the American Petroleum Institute (API) Specification, we computed and compared the uplift safety factors in different cases that might have a relevant practical use.

• Journal of the Korean Magnetics Society
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• v.27 no.4
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• pp.140-144
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• 2017

We have studied electronic and magnetic structure of cubane-type Co magnetic molecule using density functional method. The calculated density of states show $Co^{+2}$ ionic state and high-spin state because of large exchange interaction between inside Co 3d electrons. The exchange interaction J between Co atoms depends Co-O-Co angle. The calculated J is ferromagnetic with right angles. On the other hand J is antiferromagnetic with large angles since super-exchange interactions between $Co^{+2}$ atoms. It induces that Co cubane has a antiferromagnetic spin structure of AFM1 = [${\uparrow}{\uparrow}{\downarrow}{\downarrow}$]

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.2120-2124
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• 2008

In order to rise up the accuracy of evaluation of egress safety for train car and facilities, analysis of egress route, scenario and the prediction by variation of flow rate were conducted. According to analysis of egress scenario for train, the extra time should be added to the time from train to safety area when the distance between the train car floor level and the track level exists. In the result of hand calculation, the egress time was 123.1 s at flow rate 0.5, was 61.5 s at flow rate 1.0, and was 41 s at flow rate 0.5.