• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.5
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• pp.346-353
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• 2016

In the design conditions of some research reactors, the siphon phenomenon can cause continuous efflux of water during pipe rupture. A siphon breaker is a safety device that can prevent water efflux effectively. However, the analysis of the siphon breaking is complicated because many variables must be included in the calculation process. For this reason, a simulation program was developed with a user-friendly GUI to analyze the siphon breaking easily. The program was developed by MFC programming using Visual Studio 2012 in Windows 8. After saving the input parameters from a user, the program proceeds with three steps of calculation using fluid mechanics formulas. Bernoulli's equation is used to calculate the velocity, quantity, water level, undershooting, pressure, loss coefficient, and factors related to the two-phase flow. The Chisholm model is used to predict the results from a real-scale experiment. The simulation results are shown in a graph, through which a user can examine the total breaking situation. It is also possible to save all of the resulting data. The program allows a user to easily confirm the status of the siphon breaking and would be helpful in the design of siphon breakers.

• Journal of Korean Society of Steel Construction
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• v.10 no.1 s.34
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• pp.47-61
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• 1998

The behavior of horizontally curved I-girder bridges is complex because the flexural and torsional behavior of curved girders are coupled due to their initial curvature. Also, the behavior is affected by cross beams. To investigate the behavior of horizontally curved I-girder bridges, it is necessary to consider curved girders with cross beams. In order to perform free vibration analyses of horizontally curved I-girder bridges, a finite element formulation is presented here and a finite element analysis program is developed. The formulation that is presented here consists of curved and straight beam elements, including the warping degree of freedom. Based on the theory of thin-walled curved beams, the shape functions of the curved beam elements are derived from homogeneous solutions of the static equilibrium equations. Third-order hermits polynomials are used to form the shape functions of the straight beam elements. In the finite element analysis program, global stiffness and mass matrix are composed, based on the Cartesian coordinate system. The Gupta method is used to efficiently solve the eigenvalue problem. Comparing the results of several examples here with those of previous studies, the formulation presented is verified. The validity of the program developed is shown by comparing results with those analyzed by the shell element.

• Journal of Korean Society of Steel Construction
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• v.19 no.5
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• pp.515-526
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• 2007

In this study, the models and methods for the safety assessment of Steel-Concrete Hybrid Cable-Stayed Bridge, which consists of steel composite girder and concrete girder erected by the FCM(Free Cantilever Method) and FSM(Full Staging Method) are proposed for the assurance of structural safety and the prevention against bridge collapse during construction. By the structural reliability approach that reasonably considers the uncertainties associated with the resistance and the load effect, the resistance and the load distribution characteristics of Steel-Concrete Hybrid Cable-Stayed Bridgeare defined and the strength limit state equations of permanent structures and temporary structures during construction are suggested. An AFOSM algorithm and MCS technique are used for the reliability analysis of cables, pylons, girders, steel-concrete conjunction part and temporary bents. Also, component reliability analyses are performed at the construction stages based on the structural system model. To demonstrate their rationality and practicality, the proposed models and approaches are applied to a real bridge. The sensitivity analyses of main parameters are performed in order to identify the critical factors that control the safety of similar bridges. As a result, it may be stated that the proposed models could be implemented as a rational and practical approach for the safety assessment of Steel-Concrete Hybrid Cable-stayed bridges erected by FCM and FSM during construction.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.135-142
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• 2017

This study employs an analytical mathematical model to estimate the optimal debt ratio of Korean agricultural corporations, more sensitive to the government debt ratio policy compared to other industries, and the estimation of the optimal debt ratio based on objective data. The analytical model utilizes the equation for ROE, with the debt ratio as an independent variable, and related parameters include ROS, TAT, and NFCL. Regarding the NFCL, the optimal debt ratio standard is defined as the debt ratio that maximizes the ROE by analytical procedures such as adding an equation concerning the debt ratio and a linearity relationship to the analytical model, and from these equations, a quadratic equation with the debt ratio as an independent variable describes the ROE. This methodemploys fourteen years of corporate data. Results show that 138% of debt ratio is the optimal debt ratio to increase the ROE of the corporations, which implies that the existing debt ratio of Korean agricultural corporations is higher than optimal. Consequently, it is required for authorities to change future debt ratio policies in view that the purpose of debt ratio management is to maintain safety and increase profitability.Management should emphasize characteristics of the specific industry rather than standardized judgements based on numerical indexes.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.408-417
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• 2017

This study was conducted to examine the influence of the nurse staffing level on the level of in-hospital death and infection in cancer patients who received surgery. Secondary data were used and the subjects of this study were 24,510 patients who received surgery for six types of cancer with a high postoperative mortality rate in the first half of 2012 at 260 hospitals. Simple logistic and GEE multiple logistic regression analyses were used. After adjusting for the patient and hospital characteristics, a greater likelihood of dying was found in the nurse staffing level 2-3 group (odds ratio [OR], 1.46; 95% confidence interval [CI], 1.00-2.11) and in the level 6-7 group (OR, 3.28; 95% CI, 1.87-5.74) compared to the level 0-1 group. The likelihood of in-hospital infection increased with each additional bed per nurse, being 6.63 times higher (95% CI, 3.00-14.62) in the level 2-3 group, 5.79 times higher (95% CI, 1.88-17.78) in the level 4-5 group, and 8.4 times higher (95% CI, 1.82-38.84) in the level 6-7 group, as compared to the level 0-1 group. A lower nurse staffing level was associated with higher in-hospital death and infection levels. This shows that an appropriate nurse staffing level is associated with superior postoperative cancer patient outcomes. Policies for providing adequate nurse staffing should be maintained for the sake of ensuring improved care quality and patient safety.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.2
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• pp.265-272
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• 2007

This proposed gamma (${\gamma}$) correction system is developed to reduce the difference between non-linear gamma curve produced by a typical formula and result produced by the proposed algorithm. In order to reduce the difference, the proposed system is using the Least Squares Polynomial which is calculating the best fitting polynomial through a set of points which is sampled. Each system is consisting of continuous several kinds of equations and having their own overlap sections to get more precise. Based on the algorithm verified by MATLAB, the proposed systems are implemented by using Verilog-HDL. This paper will compare the previous algorithm of gamma system such as Existing system with Seed Table with the latest that such as Proposed system. The former and the latter system have 1, 2 clock latency; each 1 result per clock. Because each of the error range (LSB) is $1{\sim}+1,\;0{\sim}+36$, we can how that Proposed system is improved. Under the condition of SAMSUNG STD90 0.35 worst case, each gate count is 2,063, 2,564 gates and each maximum data arrival time is 29.05[ns], 17.52[ns], respectively.

• Korean Journal of Family Social Work
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• no.54
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• pp.41-75
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• 2016

This study explored the impact of daily hassles and the mediated effect of spiritual well-being and the moderated effect of coping styles on health and depression of middle-aged women. Subjects for this study were 230 Christian midlife women attending in the 10 churches on the metropolitan area. The data was analyzed using path analysis and moderator effect model with the structural equation modeling. Daily hassles are found to act as causes that damage physical or mental health and also elevate the level of depression. Daily hassles have a direct impact on health and depression, and at the same time, they also produce a partial mediation effect on spiritual well-being as a mediation factor. In other words, daily hassles impede spiritual well-being, and the deteriorated spiritual well-being, although its connection to physical health is not clear, is shown to damage mental health and elevate the level of depression. Analysis of coping styles related to the relationship between daily hassles and health and depression showed that, of the 12 coping styles, three, namely, self-criticism, positive interpretation and self-control, produced significant buffering effects. This study hopes to reveal the mediation factors that can minimize negative impact in the relationship between middle-aged women's daily hassles and healthiness and provide the basic material for figuring out practical implications and policy measures regarding the issue.

• Journal of the Korean Society of Child Welfare
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• no.56
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• pp.221-251
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• 2016

The purpose of this study was to examine whether single-parent family status affects children's school adjustment through children's self-care and media exposure. In addition, the study investigated the mediating effects of self-protection and media exposure of children by analyzing whether single-parent family status has effects on school adjustment through self-care and media exposure of children. For this purpose, we used data of 1,916 students in the 4th grade who participated in the 4th year of the Korean Children and Youth Panel Survey (KCYPS). The results of the structural equation modeling showed that single-parent family environment not only had direct effects on the school adjustment, but also had effects on school adjustment through self-care of children. In addition, it was revealed that self-care of children influenced school adjustment through media exposure. One of the covariates, monthly income of households, did not affect the level of children's self-care. This result draws attention to the problems of the structural deficit of single-parent families. Therefore, political measures that correspond to the structural characteristics and special needs of single-parent families, along with their current financial support, are needed to improve the level of school adjustment of children from single-parent families.

• Journal of Korea Water Resources Association
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• v.52 no.10
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• pp.697-706
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• 2019

A multiphase flow modeling approach equipped with a hybrid turbulence modeling method is applied to compute the gravity currents in a rectangular channel. The present multiphase solver considers the dense fluid, the less-dense ambient fluid and the air above free surface as three phases with separate flow equations for each phase. The turbulent effect is simulated by the IDDES (improved delayed detach eddy simulation), a hybrid RANS/LES, approach which resolves the turbulent flow away from the wall in the LES mode and models the near wall flow in RANS mode on moderately fine computational meshes. The numerical results show that the present model can successfully reproduce the gravity currents in terms of the propagation speed of the current heads and the emergence of large-scale Kelvin-Helmholtz type interfacial billows and their three dimensional break down into smaller turbulent structures, even on the relatively coarse mesh for wall-modeled RANS computation with low-Reynolds number turbulence model. The present solutions reveal that the modeling approach can capture the large-scale three dimensional behaviors of gravity current head accompanied by the lobe-and-cleft instability at affordable computational resources, which is comparable to the LES results obtained on much fine meshes. It demonstrates that the multiphase modeling method using the hybrid turbulence model can be a promising engineering solver for predicting the physical behaviors of gravity currents in natural environmental configurations.

• Journal of Digital Convergence
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• v.17 no.10
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• pp.209-221
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• 2019

Cooperating with a supplier with professional skills is necessary to achieve performance in the development of the innovative products. It is also important to improve development competence and share knowledge. This study empirically analyzed the effect of participant's Job Competence and Leadership Competence on Knowledge Sharing, and the effect of Purchaser Interdependence on Supplier Absorption Capacity. The purpose of the study is to confirm that Knowledge Sharing between Development Participant and Supplier contributes to Performance and to demonstrate the need for a cooperative relationship with the Supplier. A survey was conducted on the product development participants to confirm the relationship between the factors using a Structural Equation Model. As a result of the hypothesis test, the better the Individual Competence of the development participants, the better the Knowledge Sharing Activity, and then Knowledge Sharing and Interdependence are the main factor in the Absorption Capacity of the Supplier. The results of this study can contribute to improving the Supplier Absorption Capacity in the product development projects in which high technology is converged. In the future, we will study the effects of the project support activities of related departments for Performance.