• Journal of Korea Water Resources Association
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• v.42 no.3
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• pp.235-246
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• 2009

This study theoretically reviews the basin storage coefficient and concentration time using the Nash model, a simple unit hydrograph theory. First, the storage coefficient and concentration time of Nash instantaneous unit hydrograph (IUH) are derived based on their definitions, whose characteristics as well as their relationship are also reviewed. Additionally, several empirical equations of storage coefficient and concentration time commonly used in Korea are evaluated by comparing them with those for the Nash IUH. Major results of this study are summarized as follows. (1) The concentration time of Nash IUH is approximately linearly proportional to the number of linear reservoirs, but the storage coefficient non-linearly to the square root. That is, if increasing the number of linear reservoirs by four times, the concentration time becomes also increased by about four times, but the storage coefficient only about two times. This result has a special meaning to understand the effect of basin subdivision on the concentration time and storage coefficient. (2) The storage coefficient and concentration time of Nash IUH are not independent each other, so their independent estimation does not make any physical sense. As the concentration time among the two is more sensitive to the number of linear reservoirs, which should be estimated first, then the storage coefficient considering the concentration time estimated. (3) Empirical equations of concentration time can be divided into two groups, one following the linear channel theory and the other not, whose equation forms are also found to be very similar. This result indicates that the characteristic factors dominating the concentration time are very similar, indicating the possibility of its regionalization over a basin with consistent equation forms. (4) Those for storage coefficient like the Russell formulae are found to consider the physical characteristics of a basin, so their unreasonable applications could sufficiently be excluded.

• Journal of Digital Contents Society
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• v.17 no.6
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• pp.593-601
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• 2016

This paper is related to the Region-based Spectral Correlation Estimation(RSCE) coding method that makes it possible to achieve the high-compression ratio by estimating color component images from luminance image. The proposed method is composed of three steps. First, Y/C bit-plane summation image is defined using normalized chrominance summation image and luminance image, and then the Y/C bit-plane summation image is segmented for extracting the shape information of the regions. Secondly, the scale factor and the offset factor minimizing the approximation square errors between luminance image and R, B images by the each region are calculated. Finally, the scale factor and the offset factor for the each region are encoded into bit stream. Referring to the results of computer simulation, the proposed method provides more than two or three times higher compression ratio than JPEG/Baseline or JPEG2000/EBCOT algorithm in terms of bpp needed for encoding two color component images with the same PSNR.

• Journal of the Korean Vacuum Society
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• v.15 no.2
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• pp.180-185
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• 2006

Microwatt power level at relatively high voltage(order of volt) was produced by $Bi_{0.5}Sb_{1.5}Te_{3}/Bi_{2}Te_{2.4}Se_{0.6}$ thin film thermoelectric generators, and maximum output power varied with temperature difference in the square-law relation. Output voltage and current were possible to control by changing the way of electrical connection as well as the number of stacking plate-modules. Variation of open circuit voltage and short circuit current with temperature difference showed a linear relationship. There were, however, some differences in variations; open circuit voltage were dependent on the number of plate-module when connected in series, but it was not for parallel connection. On the other hand, short circuit current showed the opposite behavior to the case of open circuit current.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.37 no.1
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• pp.49-58
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• 2000

This paper presents a new color Image coding method which estimates color component Images from luminance image using spectral correlation m wavelet transformed domain More specifically, the wavelet transform is performed to the luminance image(Y), and then, for an efficient quad-tree division to encompass the varying block size, a cost function IS defined using high frequency coefficients generated by wavelet decomposition Next, a scale factor and an offset factor for each the block to minimize the estimation error between luminance image(Y) and R, B Images, are iteratively calculated With respect to the varying block size With associated cost function.

• Journal of architectural history
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• v.17 no.4
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• pp.97-112
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• 2008

In this study, I attempted to the architectural design characteristics of Daeung-Jeon in Sudeok Temple. For this purpose, After I set up several assumptions in the basis of the general characteristics of Korean wood architecture, and then, analyzed floor plan, structural formation and section sizes of structure and bracket members in relation to module and unit. As the results, the characteristics of the design process of plan and structure are follows. (1) 1 ja(尺), the unit applied to this building is measured $307.6{\sim}318.3mm$) and the average is 312.9mm (2) It is estimated that the floor plan designed on the basis of the top of columns. By the applied unit, every bay of the front side and the side is each designed by 15 ja and 8.5 ja. (3) The section is composed of piled members which have same section size. As basic module of section size called 'jae(재;材)', it is estimated at width 0.45 ja by height 0.75 ja. And as the secondary module, height between jae and is called 'gyoe(계;)' and it wes designed by three height size of 0.25 ja, 0.27 ja and 0.30 ja, (4) It is estimated that the section plan was designed by the order as follows. Firstly, the horizontal position of purlins wes decided on the basis of the intersection point of long and short rafters, and then the position and the section size of purlins and jangheyo(長舌) wes decided on the basis of the slope of roof and rafters. Secondly, going down from purlins, the members of structure composed of 'jae' and 'gyoe' was repeated. Lastly, for the purpose of linking the structure members located on the center line of adjacent purlins organically, the height of whaban(화반) was controlled.

• Korea journal of population studies
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• v.29 no.3
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• pp.159-188
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• 2006

This study attempts to create a longitudinal dataset by linking tdata on the identical individuals across the monthly sample household management lists of the Economically Active Population Survey(EAPS) and the Household Income and Expenditure Survey(HIES). Using the data constructed through such process, the study also tryies to analyze the duration of longitudinal responses and the characteristics of nonrespondents. Between 1998 and 2002, longitudinal response rates had declined to 46% of total EAPS and 34% of total HIES. The fact that nonresponse was not a random phenomenon leads to concerns about the representativeness of the remaining sample. Using Cox's proportional hazard model the study revealed that the duration of longitudinal responses is affected by the ownership of house and the age of the respondent.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.16 no.5
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• pp.223-229
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• 2023

This Paper propose the method that measure main system parameters for PI(proportional-integral) current control of a.c. motor adopting the vector control technique. For current control, the PI control input is could be tuning by several selective methods. Among the several methods, the method that using the main system parameters, wire resistance and inductance, are frequently used. In this study, the technique to dissect and measure these two system parameters through the results of simple feedback control. This analytic measurement method is measuring parameters step by step dissecting the results of P control using simple proportional feedback gain about the unit step or multiple step reference command. This strategy is an real time analytic measurement method that calculate current control gains of torque component and flux component both for vector control of A.C. motor without introducing the further measurement circuits and complex measuring algorithms.

• Journal of the Korean Data and Information Science Society
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• v.27 no.2
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• pp.285-294
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• 2016

In general, employment duration is influenced by the individual characteristics (level-1) as well as type of the occupational characteristics (level-2). That is, the data has hierarchical structure in the sense that individual employment duration is influenced by the individual-level variables (level-1) and the job-level (level-2) variables. In this paper, we study the determinants of the employment duration of youth-intern in the SMEs (small and medium enterprises) using Cox's mixed effect model. Major results at level-1 variables are as followings. First, the hazard rate of treatment group is lower than that of control group. Second, the hazard rate of woman is lower than that of man. Also, the hazard rate is lower, for the older and the workers working in the bigger company. Investigation of level-2 variables has shown that random effect for job-level is statistically significant.

• Journal of the Korean Recycled Construction Resources Institute
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• v.11 no.3
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• pp.192-201
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• 2023

In this paper, the strength properties of porous concrete containing natural fine aggregates and bottom ash aggregates were investigated, The material properties of natural fine aggregates and bottom ash were identified then used as aggregates for porous concrete. The water-binder ratio was constant at 0.25, and the com paction level of 0.5, 1.5, and 2.5 MPa was applied to produce a porous concrete specimen. Test of unit weight, ultrasonic velocity, compressive strength, and flexural tensile strength were perform ed and analyzed. The unit weight, ultrasonic velocity, com pressive strength, and flexural tensile strength increased as the compaction level increased and also the replacement rate of bottom ash with sand(fine aggregate) increased. In addition, through regression analysis, the correlation between the unit weight, compressive strength, and flexural tensile strength of bottom ash porous concrete was presented. Unit weight and strength properties are proportional to each other and showed an increasing correlation. In addition, the correlation coefficient (R²) value of regression analysis was calculated based on the experimental results of this study and those of other research papers.

• Journal of the Korean Wood Science and Technology
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• v.44 no.1
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• pp.48-56
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• 2016

In this study, to develop the lattice materials with a low environmental load for restoring the destroyed forest, 7 types of wood-concrete hybrid laminated materials were manufactured with domestic four softwoods, three hardwoods and concrete, and the effects of density of wood species on static bending strength performances were investigated. Bending MOEs of wood-concrete hybrid laminated materials increased with increasing density of wood species on the whole, and the values were higher than that of concrete by hybrid-laminating woods on the concrete. It was found that the measure values of bending MOEs were slightly lower than the calculated values calculated using equivalent cross-section method from MOE of each laminae of hybrid laminated materials and the difference between them was less than 10%. Bending proportional limit stresses of hybrid laminated materials showed 1.2-1.6 times higher than that of concrete by hybrid-laminating. Bending strength (MOR) of hybrid laminated materials increased with the density of wood species. By hybrid-laminating, the MOR of concrete was considerably increased. Therefore, it is considered that wood-concrete hybrid laminated materials can be applied as a materials with a low environmental load and durability for ecological restoration.