• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.6
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• pp.989-999
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• 2017

In this study, hydraulic experimental studies were conducted to estimate the empirical formulas of loss coefficient, which is necessary to calculate the energy loss occurred in the dividing channel junction of sewer system. The experimental apparatus was consisted of two outflow conduit with a $90^{\circ}$ angle to the inlet conduit, and the pressure and velocity heads are measured to analyze the energy losses in the branch. The measurements of the hydraulic grade line show that the hydraulic grade line was steeply descended at the dividing point due to the head loss, and the decreasing amount of velocity head increased with the increase of flowrate ratio. The head loss exponentially increased in the outlet with larger runoff as the increase of flowrate ratio and Froude number, and the head loss coefficient also increased. On the other hands, the head loss coefficients decreased in the outlet with smaller runoff as the increase of the flowrate ratio and Froude number. Using the experimental results, the empirical formulas of loss coefficient was suggested for each outlet, and the error of empirical formula was 3.91 and 5.19%, respectively. Furthermore, the total head loss coefficient calculated by the two empirical formulas was compared with the experimental results, and the error was 3.62%.

• Informatization Policy
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• v.21 no.3
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• pp.33-55
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• 2014

Public Shared Service Centers (PSSC) consolidate functions such as human resources, information technology, financial management or accounting into one office to serve an organization. A prominent example from the United States is the Federal Information Technology Shared Services Strategy. It supports mission, administrative, and infrastructure-related IT functions through providing organizations in the Executive Branch of the Federal Government (Federal Agencies) with policy guidance on the full range and lifecycle of intra- and inter-agency information technology (IT) shared services. This study looks at the Federal Information Technology Shared Services Strategy in order to draw lessons for fostering collaborative government through the use of PSSC. It finds the following factors are critical for success when implementing IT shared services: (1) agency leadership must be solidly behind their IT shared service plan, or the needed changes will not happen at the business unit, program, or system levels; (2) there must be a move away from internally-centered, program-specific thinking, and a move toward a paradigm of consuming and providing IT shared services with multiple groups whenever possible; and (3) successfully managing "loss of control" issues is central, and optimizing business processes is essential to move from stove-piped workflows to processes that work across the agency enterprise and beyond. Therefore, the study suggests that a Korean model of PSSC implementation be introduced, and that good IT Governance is a crucial component of PSSC strategies.

• Journal of Distribution Science
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• v.14 no.2
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• pp.83-92
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• 2016

Purpose - The purpose of this study is to identify the relations among perceived organizational support, career planning, and subjective career success (career satisfaction and job satisfaction). In particular, this study focuses on the mediating effect on the career planning between perceived organization and subjective career success. The target cases are employees of a Korean branch of a global company (A), which operates formal career program to support a career development for employees. Research design, data, and methodology - The data were collected from December, 2014 to March, 2015. 211 out of 300 questionnaires were returned (response rate 70.3%). After the data cleaning, 209 questionnaires were used for the data analysis. These data were analyzed through descriptive statistics, correlation analysis, exploratory factor analysis (EFA), confirmatory factor analysis (CFA), and structural equation modeling (SEM). The whole process of the data analysis was accomplished using the SPSS 21.0 for windows and the AMOS 21 program. Results - The findings of the study are as follows: First, the better the organizational support is perceived, the higher career satisfaction and job satisfaction is. That is, the employees' career and job satisfaction is higher, when they feel themselves received more supporting. Second, perceived organizational support has a positive impact on employees' career planning. This result means that it is important to support employees in their career development. Third, career planning has a positive impact on career satisfaction, but not on job satisfaction. Lastly, it is verified that career planning has a mediating effect between the perceived organizational support and career satisfaction. Not only has the perception of an organizational support a direct impact on career satisfaction, but also an indirect impact through career planning. However, there is not an indirect relationship through career planning, just an direct relationship between the perception of an organizational support and job satisfaction Conclusions - Based on the findings of this study, the major conclusion of the study was as follows: The study provides theoretical values and practical implications for the fact that the differences of the subjective perception about organizational support exist among employees, and the differences have an impact on their career planning as well as subjective career success. Furthermore, some recommendations for workplace were suggested: The companies should support the career development for employees in organization level. Even though employment instability makes individual workers themselves to be responsible for their own career development, it is an important issue in organizational level that employees' career success could have positive effects on organizational development and success, as well. However, there is a limit in the study that analyzing results cannot be generalized due to the data from a single company. Some recommendations for future research are suggested: First, a comparative study should be conducted with other various companies. Second, a hierarchical analyzing model needs to be applied to substantiate how organizational context influences on subjective career success of employees.

• Journal of Korea Water Resources Association
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• v.42 no.8
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• pp.643-657
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• 2009

The major reason to construct large dams is to store surplus water during rainy seasons and utilize it for water supply in dry seasons. Reservoir storage has to meet a pre-defined target to satisfy water demands and cope with a dry season when the availability of water resources are limited temporally as well as spatially. In this study, a Hedging rule that reduces total reservoir outflow as drought starts is applied to alleviate severe water shortages. Five stages for reducing outflow based on the current reservoir storage are proposed as the Hedging rule. The objective function is to minimize the total discrepancies between the target and actual reservoir storage, water supply and demand, and required minimum river discharge and actual river flow. Mixed Integer Linear Programming (MILP) is used to develop a multi-reservoir operation system with the Hedging rule. The developed system is applied for the Han River basin that includes four multi-purpose dams and one water supplying reservoir. One of the fours dams is primarily for power generation. Ten-day-based runoff from subbasins and water demand in 2003 and water supply plan to water users from the reservoirs are used from "Long Term Comprehensive Plan for Water Resources in Korea" and "Practical Handbook of Dam Operation in Korea", respectively. The model was optimized by GAMS/CPLEX which is LP/MIP solver using a branch-and-cut algorithm. As results, 99.99% of municipal demand, 99.91% of agricultural demand and 100.00% of minimum river discharge were satisfied and, at the same time, dam storage compared to the storage efficiency increased 10.04% which is a real operation data in 2003.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.7 no.1
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• pp.7-18
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• 2012

So many researchers have been interested in key success factors of technological start-ups. However, even previous studies have focussed on key success factors, as their findings have not been consistent. The purpose of this study is to investigate the determinants of technological start-ups' performance. The first aim of this study is intended to explores impact of entrepreneurs' characteristics, technological capabilities and network on firm performance. The second aim is to examine the causal relationships among latent variables with firm performance and with the use of path analysis. For this study, information has been gathered through surveys from entrepreneurs of 701 Korean technological start-up companies. As for analysis of the data, SPSS 18.0 OK for Windows and AMOS 4.0 were used for testing of hypothesis. Results of the hypothesis testing are summarized as follows: First, it was found that entrepreneurs' characteristics, technological capabilities and network had statistically significant influence on firm performance. Second, entrepreneurs' characteristics had significant influence on technological capabilities and network. Third, network did not have significant influence on technological capabilities. The major contributions of this study are (1) identifying the determinants on firm performance of technology-based start-ups by means of structural equation model, (2) verifying effects on firm performance of technology-based start-ups by the variables.

• Journal of Soil and Groundwater Environment
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• v.17 no.2
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• pp.54-61
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• 2012

In this study, the adsorption of $Cu^{2+}$ from aqueous solution by the biochar derived from woody biomass at different pyrolysis temperatures has been investigated. The woody biomass wastes used in this study were branch of willow ($Salix$ $koreensis$ $Andersson$) and bark of chestnut ($Castanea$ $crenata$ $var.$ $dulcis$). Three biochar samples prepared by heating each biomass at temperature of $300^{\circ}C$, $500^{\circ}C$, and $700^{\circ}C$were tested for the adsorption capacity of Cu. Also the physicochemical properties of the developed biochars were studied using different characterization techniques such as FT-IR, SEM, BET surface area, and cation exchange capacity (CEC). The adsorption of Cu could be well described by Langmuir model for both willow and chestnut biochars with $R^2{\geq}0.98$. The maximum adsorption capacities of the biochar produced at $700^{\circ}C$ from the Langmuir equation were found to be 12.5 mg $g^{-1}$ and 16.9 mg $g^{-1}$ for willow and chestnut, respectively. Chestnut biochar was found to interact more effectively with the active sites available for Cu, resulting higher removal of Cu(II) than wiloow biochar. Ion exchange and surface complexation found to be the main mechanisms involved in the adsorption process. This study demonstrated the feasibility of the biochars derived from woody biomass to be as a low-cost potential adsorbent for heavy metals as Cu(II) removal in aquatic system.

• Korean Journal of Weed Science
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• v.4 no.1
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• pp.88-95
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• 1984

The study was intended to analyze the interaction effects of paraquat and oxytluorfen as an orchard herbicide-mixture. Data were prepared from the former report of authors. The algebraic expression for the actions of paraquat and oxyfluorfen on the control percentages of peach orchard weeds, and their interactions were determined from the multiple regression polynomial and plotted in three-dimensional graphs. As a result of treatments by combination of paraquat and oxyfluorfen on the field which was dominated by perennial weeds, the most effective interactions were detected at combination rates of $245\;gHa^{-1}$ paraquat and $470-705\;gHa^{-1}$ oxyfluorfen. However, to develope the long-term weeding-efficacies, the combination rates of paraquat are expected to raise up to $500-700\;gHa^{-1}$, and oxyfluorfen to fit at lower limits of rates, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.1
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• pp.113-120
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• 2018

Angiography and CT angiography are used widely for the examination of vascular diseases, but the diagnosis of such diseases is made mostly by the subjective judgment of the inspector. This paper proposes a method for detecting the suspicious regions of stenosis and aneurysm in the inner surfaces of 3D blood vessel models reconstructed from medical images. Initially, the 3D curve-skeletons of the blood vessel models and the contours at the nodes of the curve-skeletons were generated. Next, the 3D curve-skeletons were divided into a set of branches and the areas of normal contours of nodes located in each branch were calculated. The nodes whose contours contain suspicious regions were detected by taking into account the average area, maximum and minimum areas, and the area difference between the adjacent normal contours. The diagnosis of stenosis and aneurysm can be supported by properly visualizing the suspicious regions detected. The suspicious regions of the disease were identified by implementing and testing it using several data sets of human blood vessels, highlighting the usefulness of the proposed method.

• Journal of Nutrition and Health
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• v.44 no.3
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• pp.196-202
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• 2011

Epigallocatechin gallate (EGCG), or epigallocatechin 3-gallate, is the ester of epigallocatechin and gallic acid, and is a type of catechin. EGCG may be therapeutic for many disorders including diabetics and some types of cancer. However it is unknown whether EGCG can induce transdifferentiation of pancreatic cells in pancreatitis. The aim of this study was to investigate the effects of EGCG on the expression of pancreatic regenerating related markers in pancreatic AR42J cells, a model of pancreatic progenitor cells. AR42J cells, differentiated with betacellulin and activin A, were cultured with/without EGCG in a time-dependent manner. Cell growth rate, levels of mRNA, and protein expression were examined with the MTT assay, quantitative PCR, and Western blots, respectively. The results showed that AR42J cell growth rates were inhibited by EGCG in a dose-dependent manner. mRNA and protein expression of amylase, insulin and neurogenin 3 (ngn 3) increased in AR42J cells treated with EGCG. Additionally, we demonstrated that the signal transduction pathway of mitogen-activated protein (MAP) kinase is active in EGCG-treated AR42J cells. ERK and JNK phosphorylation decreased in cells treated with EGCG but not p38 phosphorylation. Activation of the p38 MAP kinase pathway was confirmed by specific MAP kinase pathways inhibitors: U0126 for ERK, SP600126 for JNK, and SB203580 for p38. Activated p38 phosphorylation was inhibited by the specific p38 inhibitor SB203580 but p38 phosphorylation was inhibited with increased EGCG treatment. The ERK and JNK MAP kinase pathways were not affected by EGCG treatment. Although further studies are needed, these results suggest that EGCG affects the induction of pancreatic cell regeneration by increasing the ngn 3 protein and mRNA expression and activating the p38 MAP kinase pathway.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.4
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• pp.400-406
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• 2017

The model used in this study was reversed to analyze the cause of excessive damage that occurred inside the rotating system and pipe system of a centrifugal-type seawater pump on a ship. For this purpose, internal flow analysis on a cooling seawater pump was performed using CFD. As a result, the shape and boundary conditions of the target pump were set by reverse engineering, and pump efficiency at a design operating point of $125m^3/h$ was calculated as 85.3 % with a head of 32.0 m. The maximum efficiency point of the target pump was estimated to be 86.2 % at $150m^3/h$, but this differed from the actual operating point. At $112.5m^3/h$, which was the lowest flow point, flow was unstable due to the characteristics of the low flow point and analysis convergence was not good. The purpose of this study was to clarify the cause of ongoing cavitation in seawater pumps and piping systems in operation. Future research will be needed to clarify causes for pipe systems in the future by performing calculations for the total piping system of an inlet and outlet, in addition to measuring the flow rate of each branch pipe.