• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.5
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• pp.525-531
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• 2011

Exhaust gas recirculation (EGR) is more effective than selective catalytic reduction (SCR) or lean $NO_x$ trap (LNT) for the reduction of $NO_x$ emissions in diesel engines. A large amount of EGR gas is necessary to satisfy the stringent regulations on $NO_x$ emissions. Low pressure loop (LPL) EGR is almost independent of the variable geometry turbocharger (VGT) at a specific boost pressure, so LPL EGR is better than conventional high pressure loop (HPL) EGR in terms of EGR supply. We compare the influence of HPL EGR and LPL EGR on the combustion characteristics at a constant boost pressure in a diesel engine. The dilution ratio was employed as an independent parameter to analyze the effect of the dilution of the intake charge for each EGR loop. At the same level of $NO_x$ emissions, the fuel consumption and smoke opacity were slightly lower for LPL EGR than for HPL EGR.

• The Korean Journal of Nuclear Medicine
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• v.27 no.2
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• pp.261-269
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• 1993

When monoclonal antibodies are used in radioimmunoassay or immunoscintigraphic studies, post-labelling immunoreativity is a critical parameter. $^{125}I$ was incorporated to CEA-79 (anti CEA monoclonal antibody developed in Korea) by chloramine T and iodogen method with variable specific activities from $0.1{\mu}Ci/{\mu}g$ to $100{\mu}Ci/{\mu}g$. We used a new method to evaluate the immunoreactivites of modified antibody relative to the unlabelled native antibody from competitive binding assay. The effect of immunoreactivity and specific activity to the sensitivity of radioimmunometric assay was also evaluated. As a result, chloramine T method was better than iodogen method in radioiodination of CEA-79, because the immunoreactivity of antibody was relatively well reserved and more stable. New competitive binding assay was simple and effective to evaluate the change of immunoreactivity in radiolabelling. Antibody with high immunoreactivity and high specific activity improved the sensitivity of radioimmunometric assay, whereas antibody with high specific activity but low immunoreactivity didn't. The immunoreactivity and specific activity should be optimized according to the clinical un, and competitive binding method is useful in selection of optimal radiolabelling assay.

• Journal of Korean Society of Transportation
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• v.34 no.3
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• pp.278-290
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• 2016

Maximum traffic flow rate is an important performance measure of operational status in transport networks, and has been considered as a key parameter for transportation operation since a bottleneck in congestion decreases maximum traffic flow rate. Although previous studies for traffic flow analysis have been widely conducted, a detection method for changes in dynamic traffic flow has been still veiled. This paper explores the dynamic traffic flow detection that can be utilized for various traffic operational strategies. Turning point analysis (TPA), as a statistical method, is applied to detect the changes in traffic flow rate. In TPA, Bayesian approach is employed and vehicle arrival is assumed to follow Poisson distribution. To examine the performance of the TPA method, traffic flow data from Jayuro urban expressway were obtained and applied. We propose a novel methodology to detect turning points of dynamic traffic flow in real time using TPA. The results showed that the turning points identified in real-time detected the changes in traffic flow rate. We expect that the proposed methodology has wide application in traffic operation systems such as ramp-metering and variable lane control.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.2
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• pp.8-18
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• 2020

An Exponential Bandwidth Harmony Search with Centralized Global Search (EBHS-CGS) was developed to enhance the performance of a Harmony Search (HS). EBHS-CGS added two methods to improve the performance of HS. The first method is an improvement of bandwidth (bw) that enhances the local search. This method replaces the existing bw with an exponential bw and reduces the bw value as the iteration proceeds. This form of bw allows for an accurate local search, which enables the algorithm to obtain more accurate values. The second method is to reduce the search range for an efficient global search. This method reduces the search space by considering the best decision variable in Harmony Memory (HM). This process is carried out separately from the global search of the HS by the new parameter, Centralized Global Search Rate (CGSR). The reduced search space enables an effective global search, which improves the performance of the algorithm. The proposed algorithm was applied to a representative optimization problem (math and engineering), and the results of the application were compared with the HS and better Improved Harmony Search (IHS).

• Journal of the Korean Society for Marine Environment & Energy
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• v.11 no.3
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• pp.160-163
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• 2008

$CO_2$ ocean sequestration is being considered as a way to earn a frame of time to change other industrial life pattern to overcome the global warming crisis. The method is to dilute the captured $CO_2$ into ocean by ejecting the liquefied $CO_2$ through nozzles. The main issue of such method is the effectiveness and safety, and in both problems the rising speed of those LCO2 droplet is the key parameter. In this paper, the rising speed of LCO2 droplets is numerically studied including the effect of the surfactant which can be residing along the density interface of the droplets. A front tracking method with a simple surface tension model is developed and the rising speed of the droplets is carefully investigated with varying the various parameters. It is demonstrated that the variable surface tension can change the deformation of the droplet, the flow near the interface, and the rising speed.

• Journal of Distribution Science
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• v.13 no.2
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• pp.63-73
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• 2015

Purpose - Satisfaction with service is evaluated according to customers' subjective judgment. The expected value of customer service and its evaluations depend on the customers' position. The customer recognizes two different forms of service levels. One is satisfaction and the other is dissatisfaction. Customers who are satisfied want to receive the service in future. However, those dissatisfied try to change the service. The service provider tries to improve the service. There are two different service cycles. One is the successful cycle and the other is the failure cycle. This study aimed to empirically determine the effects of the justice and authenticity of service recovery on customer behavioral intention through an integrated approach to cognitive justice and psychological authenticity. Research design, data, and methodology - Based on a literature review, justice of service recovery was categorized into three types: distributive, procedural, and interactive. Then, authenticity was added to obtain four independent variables, along with recovery satisfaction as a parameter. Behavioral intention, as an outcome variable, was divided into the repurchase intention and positive word-of-mouth. The model and hypotheses were created and measurement items were developed. A questionnaire survey of items concerning the service recovery experience at family restaurants was conducted on college students and residents in Gwangju from September 30 to October 31, 2013. A total of 400 copies of the questionnaire were sent out and 385 were returned. Respondents answered questions about the importance of, and satisfaction with service recovery on a 5-point Likert scale. Excluding 174 copies without service failure experiences and 7 inappropriate copies, 204 copies were analyzed using SPSS 21.0 for Windows and AMOS 20.0 to determine the reliability and validity of measurements. The hypotheses were tested through a goodness-of-fit analysis. Results - First, distributive justice positively affected recovery satisfaction. Second, procedural and interactive justice had no impact. Third, authenticity positively affected recovery satisfaction. Fourth, distributive justice had relatively stronger effects on recovery satisfaction than authenticity. Fifth, recovery satisfaction significantly affected repurchase intention and positive word-of-mouth and it proved effective in mediation. Finally, additional analysis was performed for descriptive statistics of the principal variables by various demographic characteristics and significant differences were found in gender, occupation, and so on. Conclusions - This study has academic significance as the fairness and authenticity of service recovery were investigated to reveal the effects on behavior. The findings could be applied to a wide range of service recovery strategies. However, there are some limitations. First, data was collected only from the residents of Gwangju and most respondents were aged 20-30. Future studies should target a wide range of areas and age groups. Second, because the questionnaire used in this study targets only convenience family restaurants, the results of this study cannot be generalized to all services companies. Future research should be done on a wide range of industries such as hotels, airlines, and hospitals, and perform a comparison between sectors.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.7
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• pp.125-132
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• 2018

The purpose of this study is to examined the relationship between child care teachers' science teaching efficacy and children's scientific attitude. Then, using the instructional creativity as a parameter to increase the quality of teacher-children interaction, we examined how the teacher-children relationship changed. In this study, 303 child care center teachers in Suwon, Gyeeonggi were surveyed. To analyze the data, structural equation modeling and Sobel-test were performed using SPSS 23.0 and AMOS 23.0. The analysis results showed that child care center teachers' science teaching efficacy had positive effects on the teachers' creativity and the children's scientific attitude. Furthermore, the creativity of child care center teachers had a positive effect on children's scientific attitude. The result of the Sobel-test revealed that child care center teachers's creativity played a mediating role between teachers' science teaching efficacy and children's scientific attitude and acted as a key variable in promoting children's scientific attitude. In conclusion, it has been identified that the creativity of the infant teacher's teaching is an important change that has a positive effect on the child's scientific attitude. Therefore, if education is provided to enhance the creativity of the professor when the infant teacher is working as a science professor at the same time, it can contribute to the quality of the child's scientific attitude.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.6
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• pp.2575-2587
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• 2011

Whereas the early financial information technology invested a large amount of investment on developing and adopting its own new systems. it is now focusing on reducing expenses and improving internal efficiency but applied for securing a company's competitive advantage considering the long term strategic level. As relevant researches, studies on information system quality and performance are actively going on. In previous research, the relations of the influence on the financial performance by information system quality or absorption capacity have been reviewed. In other words, the information system quality and absorptive capacity, respectively, in the position of the independent variables have been studied as a factor to have a significant effect on financial performance while the research on the relationship between these two variables is lacking. Thus, in this researches, quality of financial information systems and the absorptive capacity, respectively, as independent variables and parameters on the mediating effect on the financial performance were researches. As a result, quality of financial information systems showed a positive effect on the performance of company, the absorption capacity was perfect to play the role of mediating one. However, absorptive capacity as an independent variable has a positive impact on financial performance, but the quality of financial information systems as a parameter was not affected in any manner.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.2
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• pp.799-805
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• 2016

Background: There is no standard treatment for patients with platinum-resistant or refractory epithelial ovarian cancer. Single agent chemotherapies have evidence of more efficacy and less toxicity than combination therapy. Most are very expensive, with appreciable toxicity and minimal survival. Since it is difficult to make comparison between outcomes, economic analysis of single-agent chemotherapy regimens and best supportive care may help to make decisions about an appropriate management for the affected patients. Objective: To evaluate the cost effectiveness of second-line chemotherapy compared with best supportive care for patients with platinum-resistant or refractory epithelial ovarian cancer. Materials and Methods: A Markov model was used to estimate the effectiveness and total costs associated with treatments. The hypothetical patient population comprised women aged 55 with platinum-resistant or refractory epithelial ovarian cancer. Four types of alternative treatment options were evaluated: 1) gemcitabine followed by BSC; 2) pegylated liposomal doxorubicin (PLD) followed by BSC; 3) gemcitabine followed by topotecan; and 4) PLD followed by topotecan. Baseline comparator of alternative treatments was BSC. Time horizon of the analysis was 2 years. Health care provider perspective and 3% discount rate were used to determine the costs of medical treatment in this study. Quality-adjusted life-years (QALY) were used to measure the treatment effectiveness. Treatment effectiveness data were derived from the literature. Costs were calculated from unit cost treatment of epithelial ovarian cancer patients at various stages of disease in King Chulalongkorn Memorial Hospital (KCMH) in the year 2011. Parameter uncertainty was tested in probabilistic sensitivity analysis by using Monte Carlo simulation. One-way sensitivity analysis was used to explore each variable's impact on the uncertainty of the results. Results: Approximated life expectancy of best supportive care was 0.182 years and its total cost was 26,862 Baht. All four alternative treatments increased life expectancy. Life expectancy of gemcitabine followed by BSC, PLD followed by BSC, gemcitabine followed by topotecan and PLD followed by topotecan was 0.510, 0.513, 0.566, and 0.570 years, respectively. The total cost of gemcitabine followed by BSC, PLD followed by BSC, gemcitabine followed by topotecan and PLD followed by topotecan was 113,000, 124,302, 139,788 and 151,135 Baht, respectively. PLD followed by topotecan had the highest expected quality-adjusted life-years but was the most expensive of all the above strategies. The incremental cost-effectiveness ratios (ICER) of gemcitabine followed by BSC, PLD followed by BSC, gemcitabine followed by topotecan and PLD followed by topotecan was 344,643, 385,322, 385,856, and 420,299 Baht, respectively. Conclusions: All of the second-line chemotherapy strategies showed certain benefits due to an increased life-year gained compared with best supportive care. Moreover, gemcitabine as second-line chemotherapy followed by best supportive care in progressive disease case was likely to be more effective strategy with less cost from health care provider perspective. Gemcitabine was the most cost-effective treatment among all four alternative treatments. ICER is only an economic factor. Treatment decisions should be based on the patient benefit.

• Journal of Digital Convergence
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• v.15 no.10
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• pp.1-7
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• 2017

The purpose of this paper is to examine how multi-cultural acceptability affects the perception of necessity of unification through structural equation model. The multi-cultural acceptability, familiarity with North Korean defectors, and awareness of unification were selected as the latent variables and the full / partial mediator models were built for structural equations. The observed variables for each latent variable were data that were collected through the National Survey on the Integration of North and South Korea conducted by the Korea Institute for National Unification in 2015. As a result, the acceptance of multiculturalism had a significant effect on the intimacy of the defectors, which had a positive effect on the recognition of the need for unification. The intimacy of the defectors was more influential as a parameter for full mediation than for partial mediation. Although the consciousness of unification gets weakened by postwar generations, that the phenomenon that changes into a multicultural society plays a part in recognizing the necessity of unification. In addition, the increase of North Korean defectors may ultimately become a factor in recognizing the need for unification. This study demonstrated that increasing the acceptance of multiculturalism can increase the need for unification, which means that more research fields can be derived.