• Journal of Korea Water Resources Association
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• v.56 no.5
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• pp.337-345
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• 2023

Monitoring river microplastics is a challenging task since it is a time-consuming and high-cost process. The use of a physical model to have a better understanding of river microplastics' behaviors can complement the challenging monitoring process. However, there have been very limited studies on modeling river microplastics. In this study, therefore, we evaluated the applicability of one commonly used river water quality model, i.e., the Water Quality Analysis Simulation Program (WASP), in simulating the microplastic concentration in the river environment. We simulated the microplastic concentration in the Anyangcheon stream using the WASP's biochemical oxygen demand (BOD) and suspended solid (SS) variables as possible surrogate variables for the microplastics. Simulation analyses indicate that the SS state variable performs better than the BOD state variable to mimic the observed concentrations of microplastics. This is because of the characteristics of each water quality parameter; the BOD variable, a biochemical indicator, is inappropriate for modeling the behaviors of microplastics, which have generally constant biochemical features. In contrast, the SS variable, which has similar physical behaviors, followed the observed patterns of the microplastic concentrations well. To build a more advanced and accurate model for simulating the microplastic concentration, comprehensive and long-term monitoring studies of the river microplastics under different environmental conditions are needed, and the unit of microplastic concentration should be carefully addressed before its modeling application.

• Journal of Korea Water Resources Association
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• v.55 no.4
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• pp.257-266
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• 2022

Inundation damage is increasing every year due to localized heavy rain and an increase of rainfall exceeding the design frequency. Accordingly, the importance of hydraulic structures for flood control and defense is also increasing. The hydraulic structures are designed according to its purpose and performance, and the amount of flood is an important calculation factor. However, in Korea, design rainfall is used as input data for hydrological analysis for the design of hydraulic structures due to the lack of sufficient data and the lack of reliability of observation data. Accurate probability rainfall and its temporal distribution are important factors to estimate the design rainfall. In practice, the regression equation of temporal distribution for the design rainfall is calculated using the cumulative rainfall percentage of Huff's quartile method. In addition, the 6^th order polynomial regression equation which shows high overall accuracy, is uniformly used. In this study, the optimized regression equation of temporal distribution is derived using the variable selection method according to the principle of parsimony in statistical modeling. The derived regression equation of temporal distribution is verified through the significance test. As a result of this study, it is most appropriate to derive the regression equation of temporal distribution using the stepwise selection method, which has the advantages of both forward selection and backward elimination.

• Journal of Food Hygiene and Safety
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• v.38 no.3
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• pp.89-98
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• 2023

Currently, no guidelines exist regarding the maximum residues of pesticides in edible oil which is a processed food commonly consumed in Korea. This lack of guidelines hinders the evaluation of the safety of edible oil in terms of pesticide contamination. In this study, an analysis method based on heat distillation and GC-MS/MS was established by optimizing the extraction and purification procedure for 68 pesticides. Important variables in the thermal distillation procedure included heating temperature and time, and we found the nitrogen flow rate as a mobile phase and the type of dissolving solvent were not considerably affected. The determination coefficient (R²) of the residual pesticide was 0.99 or higher, and the quantitative limit (LOQ) was 0.01-0.02 mg/L. The average recovery rate (n=5) was 66.1-120.0% and the relative standard deviation was lower than ±10% when 68 pesticides were spiked at concentrations of 0.01-0.02, 0.1, and 0.5 mg/L. In addition, the within-laboratory precision was less than ±11%, meeting the Korea Food and Drug Safety Evaluation Institute's Guidelines on Standard Procedures for Preparing Food Testing Methods (2016). Therefore, the test method developed in this study can be used as a test method for managing the safety of the residual pesticide concentration in edible oil.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.3B
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• pp.269-276
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• 2010

Climatic disasters are globally soaring due to recent acceleration of global warming. Especially the occurrence frequency of heavy rainfalls is increasing since the rainfall intensity is increasing due to the change of rainfall pattern, This study proposed the non-stationary frequency analysis for estimating design rainfalls in a design target year, considering the change of rainfall pattern through the climatic change scenario. The annual rainfalls, which are regionally downscaled from the BCM2 (A2 scenario) and NCEP data using a K-NN method, were used to estimate the parameters of a probability distribution in a design target year, based on the relationship between annual mean rainfalls and distribution parameters. A Gumbel distribution with a probability weighted method was used in this study. Seoul rainfall data, which are the longest observations in Korea, were used to verified the proposed method. Then, rainfall data at 7 stations, which have statistical trends in observations in 2006, were used to estimate the design rainfalls in 2020. The results indicated that the regional annual rainfalls, which were estimated through the climate change scenario, significantly affect on the design rainfalls in future.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.4A
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• pp.281-290
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• 2009

In this study, an analysis technique of hybrid girder considering nonlinearity of steel-concrete contact surface is presented. Steel-concrete hybrid girder shows partial-interaction behavior due to the deformation of shear connectors, slip and detachment at the interface, and cracks under the applied loads. Therefore, the partial-interaction approach becomes more reasonable. Contact surface is modeled by interface element and analyzed nonlinearly because of cost of time and effort to detailed model and analysis. Steel and Concrete are modeled considering non-linearity of materials. Material property of contact surface is obtained from push-out test and input to interface element. For the constitutive models, Drucker-Prager and smeared cracking model are used for concrete in compression and tension, respectively, and a von-Mises model is used for steel. This analysis technique is verified by comparing it with test results. Using verified analysis technique, various analyses are performed with different parameters such as nonlinear material property of interface element and prestress. The results are compared with linear analysis result and analysis result with the assumption of full-interaction.

• 한국노년학
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• v.30 no.4
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• pp.1263-1280
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• 2010

The present study describes the acculturation meaning of 12 Chinese-Chosun residential care attendants(RCAs) who are currently working in long-term care settings for Korean older adults. Using a qualitative research method, the findings show that the acculturation process of Chinese-Chosun RCAs consists of three stages: entrance, conflict, and adaptation. In the initial stage, the assets of the social and cultural networks among their friends and relatives, who already settled down or employed as RCAs, provided more opportunities for being employed as a RCA. However, most Chinese-Chosun RCAs experienced a number of conflicts while they adapted to mainstream society and perform caregiving tasks. They perceived discrimination, heavy workload, prejudice, and homesick. Nevertheless, they appeared to adapt effectively to Korean society and working environments because they were aware of the various benefits of working as a RCA such as higher wage and more job openings compared to other jobs, a rapport with the patients and patients' families, flexible work hours, and pride as a caregiver. This type of qualitative groundwork will be an important precursor to the design, implementation, and evaluation of acculturation research for minority immigrant workers in the Korean social welfare system.

• 한국노년학
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• v.29 no.2
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• pp.459-475
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• 2009

This study focused on abused old people who lived together with their family in community. The purposes of the study were aimed to typology the abused old people according to abuse level, investigate the characteristics by categorization, and suggest policies to improve the abused old people's quality of life. Data were collected from 1,200 old people aged above 65 years old who lived in Kyungki province, Incheon-si, Chungnam province. Among 1,200 people, 212 abused old people were analysed for the study. First, as a result of categorizing old people according to abuse level, forcefully abused and damaged group, psychologically abused and damaged group, and lukewarmly abused and damaged group were categorized. The forcefully abused and damaged group was seriously suffered from verbal and emotional abuse and noninterference, including 14.6% of the subjects. The psychologically abused and damaged group appeared high in verbal and emotional abuse, and level of noninterference, and the highest in level of depression, including half of the subjects. Lastly, the lukewarmly abused and damaged group was lower in verbal and emotional abuse, economic abuse and level of noninterference than other two groups, but higher in physical abuse and abandonment than the psychologically abused and damaged group. Policies to improve the quality of life for the abused old people based on the each group were made.

• Korean Journal of Social Welfare Studies
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• v.42 no.2
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• pp.123-153
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• 2011

This study tries to categorize innovation types for social welfare organizations and investigate the level of innovation in each type in practical field. Firstly, this study scrutinizes the concept and classification's criterias of innovation. Secondly, this study reviews not only classification of innovation in profit organization but also several researches of innovation in service industry and public sectors, and finally, this study makes a suggestion of innovations' classification that is applicable for social welfare organizations. Based on this suggestion, fifteen questions are designed to ask the innovative activities in the organizations. And total 496 respondents from 116 organizations answered these questionnaire. The outcomes of this survey were substantiated by second data through converted procedures to mean value of organizations. Consquently, service innovation, administrative innovation and human resource innovation, proposed based on theoretical review, were subdivided into six categories such as service innovation, structural innovation, internal and efficiency innovation, marketing and communication innovation, external and employment innovation and evalution and mission innovation. The mean value of service(mean=14.7) and marketing innovation(mean=13.3) are higher than other type of innovations, which shows the aspect of innovative activities in social welfare organizations. Based on this result, we can get the directions of following study in investigating innovation of social welfare organization.

• Asia Marketing Journal
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• v.6 no.2
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• pp.23-54
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• 2004

This study investigates the relationship between the antecedents of Trust on Internet Shopping Mall and its effects on attitude, relationship involvement, or purchase intention on the basis of previous researches. 263 undergraduate students were used into data analysis. The date was analyzed by factor analysis, correlation analysis and Structural Equation Model(SEM) using SPSS and AMOS programs. As the results, the three antecedents of trust excepting company size had the positive effects on trust. Also, trust on Internet Shopping Mall had positive direct effects on attitude and relationship involvement. But, the direct effects of trust on buying intention were rejected. Trust on Internet Shopping Mall was intensified by the positive attitude and relationship involvement and leads to the buying intention. The results of this study provide the e-marketing strategy on Internet Shopping Mall focusing on trust, attitude, relationship involvement, and buying intention.

• Asia Marketing Journal
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• v.12 no.1
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• pp.51-79
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• 2010

This study is based on recent advances in celebrity traits and self-determination researches to address how consumers develop the strong attachment to a "star brand," and the effect of consumer's attachment to star brand on evaluation of product brand sponsored by the star. We use the consumers' need satisfaction and star traits as major causal factors that influence consumer's attachment to a star brand. Specifically this article uses autonomy need, relatedness need, competence need as the dimensions of need satisfaction and expertness, trustworthiness, likeability, and similarity as the key star traits. The purpose of this study is to investigate the influence of these factors on the consumer's attachment to star brand and how consumer's evaluation of product brand sponsored by star is moderated by the fitness level of between the image of star brand and the image of sponsored product brand. To collect the data, survey was taken in a University located in Incheon. Collected data are analysed using SPSS 15.0 and AMOS 7.0. The results show that when the star brand is perceived as more trustworthy and likeable, and satisfies autonomy need and relatedness need, the consumer is more likely to become strongly attached to him or her. The hypothesis that consumer's attachment to star brand will have the positive influence on the evaluation of product brand sponsored by star is supported. And hypothesis that consumer's attitude to a sponsored product brand is moderated by the fitness level of between the image of star brand and the image of sponsored product brand is also supported. The empirical results imply that star brand to which consumers are attached may have the significant positive impact on the consumers' evaluation process of endorsed product brand and purchase behavior, and that marketers should consider need dimensions which target consumers want to satisfy and the fitness level of between the image of star brand being considered as endorser and the image of product brand.