• Journal of The Geomorphological Association of Korea
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• v.19 no.3
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• pp.1-22
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• 2012

The classification scheme of estuaries can be divided into two categories: qualitative classification based on geomorphic characteristics and quantitative classification based upon the physical properties of water body. While simple and intuitive scheme of the former is difficult to quantify, the latter is not easy to apply due to the lack of data. A classification scheme based on morphological convergence is very promising because it only requires easily accessible data such as width and depth of channels, as well as it can characterize estuaries in terms of tidal propagation. Thus, this paper examines the classification scheme based on estuarine morphological convergence using depth and width data obtained from 19 major Korean estuaries. Morphological convergence for each estuary was estimated with the estuarine length, width and depth data to get the convergence parameters, which includes the degree of funneling ${\nu}$ and the dimensionless estuarine length $y_0$. The transfer function ${\xi}({\nu},ky)$ is then deduced analytically from 1D depth-integrated hydrodynamic momentum equation and continuity equation for estuarine shapes. Tidal response of each estuary is finally calculated using ${\nu}$, $y_0$ and ${\xi}({\nu},ky)$ for comparison and classification. The 19 Korean estuaries were classified into three groups: tidal amplitude-dominated estuaries with standing wave-like tidal response (group 1), current-dominated estuaries with progressive wave-like tidal response (group 2), and the intermediate group (group 3) between groups 1 and 2. The sensitivity analysis revealed that uncertainties in determining the estuarine length can have a critical effect upon the results of classification, which indicates that the reasonable determination of the estuarine length is of critical importance. Once the estuarine length is feasibly determined, depth-convergence can be neglected without any negative effect on the classification scheme, which has an important ramification on the wide applicability of the classification scheme.

• Geophysics and Geophysical Exploration
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• v.9 no.1
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• pp.19-29
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• 2006

The first Japanese pilot-scale $CO_2$ sequestration project has been undertaken in an onshore saline aquifer, near Nagaoka in Niigata prefecture, and time-lapse well logs were carried out in observation wells to detect the arrival of injected $CO_2$ and to evaluate $CO_2$ saturation in the reservoir. $CO_2$ was injected into a thin permeable zone at the depth of 1110m at a rate of 20-40 tonnes per day. The total amount of injected $CO_2$ was 10400 tonnes, during the injection period from July 2003 to January 2005. The pilot-scale demonstration allowed an improved understanding of the $CO_2$ movement in a porous sandstone reservoir, by conducting time-lapse geophysical well logs at three observation wells. Comparison between neutron well logging before and after the insertion of fibreglass casing in observation well OB-2 showed good agreement within the target formation, and the higher concentration of shale volume in the reservoir results in a bigger difference between the two well logging results. $CO_2$ breakthrough was identified by induction, sonic, and neutron logs. By sonic logging, we confirmed P-wave velocity reduction that agreed fairly well with a laboratory measurement on drilled core samples from the Nagaoka site. We successfully matched the history changes of sonic P-wave velocity and estimated $CO_2$ saturation a(ter breakthrough in two observation wells out of three. The sonic-velocity history matching result suggested that the sweep efficiency was about 40%. Small effects of $CO_2$ saturation on resistivity resulted in small changes in induction logs when the reservoir was partially saturated. We also found that $CO_2$ saturation in the $CO_2$-bearing zone responded to suspension of $CO_2$ injection.

• Korean Journal of Family Social Work
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• no.54
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• pp.297-331
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• 2016

The purpose of this study was to examine the mediating roles of neglectful rearing attitudes and mental health in the relationship between economic status of single-parent famillies and school adjustment, and the differences between single-parent and two-parent families, using structural equation modeling. Data were obtained from the Middle School 1 Panel(third-wave) of the Korean Child and Youth Panel Survey 2010. This study selected 2,195 middle school 3th-grade students (249 from single-parent families and 1,946 from two-parent families). Data were examined with structural equation modeling and multi-group analysis using AMOS 21.0, and mediating effects were tested using the Sobel test. The results were as follows; First, the single-parent children reported lower levels of economic status and school adjustment, and higher levels of neglectful rearing attitudes than the two-parent children. Second, multi-group analysis showed a statistically significant difference between single-parent and two-parent in structural equation modeling. Economic status of two-parent famillies affected school adjustment of children, but economic status of single-parent famillies did not affect school adjustment of children. Third, as a result of examining for total effect, the variable that most influenced school adjustment of children was neglectful rearing attitudes. Fourth, neglectful rearing attitudes and mental health did play a mediating role in the relationship between economic status and school adjustment in case of two-parent famillies, but neglectful rearing attitudes and mental health did not play a mediating role in case of single-parent famillies. Based on the result, this study stressed the following; First, the study suggested that problem of the single-parent famillies supporting standard which is concentrated on the low income single-parent famillies. Second, the study proposed multifaceted support measures which reflects characteristics of single-parent famillies to increase school adjustment of the single-parent children.

• Korean Journal of Family Social Work
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• no.58
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• pp.5-36
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• 2017

This study aims to empirically analyze whether the women's cognitive attitude toward gender role, which is formed through social norms, enforces the gender division of housework. In this study, 4,435 married women aged 18-59 years from the 5th wave dataset of Korean Longutudinal Survey of Women and Family Data were selected for analysis. Using the Structural Equation Model(SEM), we examine the direct effect of "attitude toward behavior" and "subjective norm" on the domestic working hours and whether those two independent variables, such as "attitude toward behavior" and "subjective norm," influence the mediator variable "Behavior Intention" which in turn affect the dependent variable. The study reveals that "attitude toward the gender division of housework" has a statistically significant direct effect on the domestic working hours as well as an indirect effect operating through "behavior intention." And"subjective norm "has only a statistically significant indirect effect on the domestic working hours, operating through "behavior intention." Despite the fact that many women are now aware that various work-life balance policies are avaliable to mitigate the gender inequality of domestic works, it is proven that the gender division of housework becomes worse. The reason behind this is not only because there exist some problems in implementing the institutions themselves, but also because women's deeply internalized self-perception of gender role based on the traditional patriarchal culture somehow exacerbates the gender division of housework. Hence, in order to instill a progressive change in gender division of housework, it is important for women to try to change the way they perceive the stereotypical gender roles as well as for men to treat women equally.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.6
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• pp.520-526
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• 2020

This study aimed to address the effect of poverty on depression and self-rated health in older adults living alone in Korea. In addition, this study identified the mediating effect of social participation on the poverty-depression and poverty-self-rated health relationships. The researcher conducted a secondary data analysis using the 6th wave of the Korean Longitudinal Study on Aging. The final sample was 1,093 older adults living alone. Using structural equation modeling, standardized coefficients of each path were analyzed. Then, the statistical significance of the mediating effect of social participation was addressed via analyzing direct, indirect, and total effects. Results show that older adults under poverty were more depressed and had a lower level of self-rated health than their counterparts. Moreover, frequent participation in religious gatherings, social gatherings, and leisure activities decreased depression in older adults living alone. Moreover, religious gatherings, social gatherings, and alumni meetings were positively related to self-rated health om older adults living alone. Significant mediating effects appeared in poverty-social gathering-depression, poverty-social gathering-self-rated health, and poverty-alumni meeting-self-rated health relationships. Based on the results, the researcher also discussed implications for social work practice.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.15 no.3
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• pp.45-51
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• 2016

Existing real-time signal control system was brought up typical problems which are supersaturated condition, point detection system and loop detection system. For that reason, the next generation signal control system of advanced form is required. Following thesis aimed at calculating queue length for the next generation signal control system to utilize basic parameter of signal control in crossing queue instead of the volume of real-time through traffic. Overflow saturated condition which was appeared as limit of existing system was focused to set-up range. Real-time location information of individual vehicle which is collected by GPS data. It converted into the coordinate to apply shock wave model with an linear equation that is extracted by regression model applied by a least square. Through the calculated queue length and link length by contrast, If queue length exceed the link, queue of downstream intersection is included as queue length that upstream queue vehicle is judeged as affecting downstream intersection. In result of operating correlation analysis among link travel time to judge confidence of extracted queue length, Both of links were shown over 0.9 values. It is appeared that both of links are highly correlated. Following research is significant using real-time data to calculate queue length and contributing to signal control system.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2017.04a
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• pp.156-156
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• 2017

Most crop damages have been occurred by vermin(e.g., wild birds and herbivores) during the period between seeding and the cotyledon level. In this study, to minimize the damage by vermin and acquire the benefits such as protection against weeds and maintenance of water content in soil, immediately vinyl mulching after seeding was devised. Vinyl mulching has been generally covered with black color vinyl, that crop seeding locations cannot be detected by visible light range. Before punching vinyl, non-contact and non-destructive methods that can continuously determine the locations are necessary. In this study, a crop position detection method was studied that uses infrared thermal image sensor to determine the cotyledon position under vinyl mulch. The moving system for acquiring image arrays has been developed for continuously detecting crop locations under plastic mulching on the field. A sliding mechanical device was developed to move the sensor, which were arranged in the form of a linear array, perpendicular to the array using a micro-controller integrated with a stepping motor. The experiments were conducted while moving 4.00 cm/s speed of the IR sensor by the rotational speed of the stepping motor based on a digital pulse width modulation signal from the micro-controller. The acquired images were calibrated with the spatial image correlation. The collected data were processed using moving averaging on interpolation to determine the frame where the variance was the smallest in resolution units of 1.02 cm. For this study, the spline method was relatively faster than the other polynomial interpolation methods, because it has a lower maximum order of formulation when using a system such as the tridiagonal linear equation system which provided the capability of real-time processing. The temperature distribution corresponding to the distance between the crops was 10 cm, and the more clearly the leaf pattern of the crop was visually confirmed. The frequency difference was decreased, as the number of overlapped pixels was increased. Also the wave pattern of points where the crops were recognized were reduced.

• Journal of the Society of Naval Architects of Korea
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• v.32 no.1
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• pp.42-57
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• 1995

An efficient and accurate scheme has been constructed by taking advantages of the hi-quadratic spline scheme and the higher-order boundary element method selectively depending on computation domains. Boundary surfaces are represented by 8-node boundary elements to describe curved surfaces of a ship and its neighboring free surface more accurately. The variation of the velocity potential complies with the characteristics of the 8-node element on the body surface. But on the free surface, it is assumed to follow that of the hi-quadratic spline scheme. By which, the free surface solution is free from numerical damping and has better numerical dispersion property. As numerical examples, steady and unsteady Neumann-Kelvin problems are considered. Numerical results for a submerged spheroid, Series 60($C_B=0.6$) and a modified support the proposed method. Finally, a new upstream radiation condition is derived using a wave equation operator in order to deal with problems for subcritical reduced frequency. The relevance of this operator has been confirmed in the case of unsteady Kelvin source potential.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.39 no.3
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• pp.239-248
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• 2003

This paper was conducted as an attempt in order to construct the data bank of target strength for acoustic estimation of fish length in the coastal waters of Korea. The fish length dependence of acoustic target strength for 13 large yellow croakers (Pseudosciaena crocea) at 75 kHz was investigated and the prediction of the target strength by using the Kirchhoff-Ray Mode model (KRM model) was compared with target strength measurements. The results obtained are summarized as follows; 1. In the averaged target strength pattern for 13 large yellow croakers the maximum target strength was -35.13 dB at $-13.35^{\circ}$ on a tilted angle. 2. The relationship between fork length(L, cm) and averaged target strength(TS, dB) was expressed as follows; TS=23. 76log (L) -73.45 (r=0.47) TS=20log(L) -67.35 From this result, the conversion coefficient was -73.45 dB and 6.1 dB lower than the coefficient -67.35 dB where the value of the slope of the regression equation is forced to be 20. 3. Averaged target strength and a length conversion coefficient derived from a target strength histogram for 13 large yellow croakers of mean length 25.59 cm were -41.23 dB, -69.72 dB, respectively. 4. In the range of $$2;{\ll} L (fish length /{\lambda}(wave length);{\ll}40$$, the prediction of the averaged target strength by the KRM model increased gradually with the increasing of $L/{\lambda}$ and was lower than the measured target strength.

• Journal of Korea Water Resources Association
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• v.41 no.11
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• pp.1123-1133
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• 2008

It needs to conceptualize watershed with triangular or rectangular elements and to analyze the changes in hydrological components of each element for distributed modeling of rainfall-runoff process. This study is the network analysis of watershed grid for flow routing occurred in each element when analyzing rainfall-runoff process by one-dimensional kinematic wave equation. Single flow direction from D8-method(deterministic eight-neighbors method) is used, and the information of flow direction and flow accumulation are used to determine the computation order of each element. The application theory of finite volume method is suggested for each flow direction pattern between elements, and it is applied it to calculate the flow of each grid. Network analysis method from this study is applied to GRM(Grid based Rainfall-runoff Model) which is physically based distributed rainfall-runoff model, and the results from simplified hypothetical watersheds are compared with $Vflo^{TM}$ to examine the reasonability of the method. It is applied to Jungrangcheon watershed in Han river for verification, and examination of the applicability to real site. The results from Jungrangcheon watershed show good agreement with measured hydrographs, and the application of the network analysis method to real site is proper.