• Applied Chemistry for Engineering
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• v.10 no.4
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• pp.557-562
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• 1999

The reaction properties of Pd. Pd-Ce and Pd-La catalysts supported on ${\gamma}-Al_2O_3$ were investigated in the oxidation reaction of methane($CH_4$) exhausted from the compressed natural gas vehicle in a U-tube flow reactor with gas hourly space velocity of $72,000h^{-1}$. The catalysts were characterized by X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS), BET surface area and hydrogen chemisorption. Pd catalyst prepared by $Pd(NO_3)_2$ as a palladium precursor and calcined at $600^{\circ}C$ showed the highest activity for a methane oxidation. Catalytic activity of calcined $Pd/{\gamma}-Al_2O_3$ in which most of palladium was converted into palladium oxide species was higher than that of reduced $Pd/{\gamma}-Al_2O_3$ in which most of palladium existed in palladium metal by XRD. As increasing the number of reaction cycles in the wide range of redox, the catalytic activity of $Pd/{\gamma}-Al_2O_3$ was decreased and the highly active window became narrower. Lanthanum oxide promoted Pd catalyst, $Pd/La/{\gamma}-Al_2O_3$ showed enhanced thermal stability compared with $Pd/{\gamma}-Al_2O_3$ even after aging at $1000^{\circ}C$, which was ascribed to the role of La as a promoter to suppress the sintering of palladium metal and ${\gamma}-Al_2O_3$ support. Almost all of methane was removed by the reaction with NO at the redox ratio of 1.2 in case of oxygen excluded steam, but that activity was significantly decreased in the steam containing oxygen.

• Applied Chemistry for Engineering
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• v.29 no.4
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• pp.461-467
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• 2018

In this study, $(n-BuCp)_2ZrCl_2$, was supported on $SiO_2/MgCl_2$ binary support. Before supporting the catalyst, the $SiO_2/MgCl_2$ binary support was surface treated with three different alkyl aluminum compound, namely trimethylaluminum, triethylaluminum, and ethylaluminum sesquichloride. The synthesized surface-treated $SiO_2/MgCl_2$ supported metallocene catalysts were used for the copolymerization of ethylene and 1-hexene. Their catalytic properties and performances were analyzed through BET, XPS analysis, ICP-AES analysis, and FE-SEM. While the resulting copolymers were analyzed through DSC analysis, GPC analysis, 13C-NMR analysis, and FE-SEM. The analysis of synthesized surface-treated $SiO_2/MgCl_2$ supported metallocene catalysts showed that the Zr content of these catalysts is relatively lower compared to that of the catalyst supported on $SiO_2$. This could be attributed to the reduction in the surface area of $SiO_2$ due to the presence of recrystallized $MgCl_2$ and alkyl aluminum. Furthermore, they exhibited a better copolymerization activity compared to that of $SiO_2$ supported catalyst, particularly the EASC-surface treated binary support, which has the highest activity of 1.9 kg PE/($mmol-Zr^*hr$) because EASC acts as a strong Lewis acid. It could also be observed that the larger the ligand of alkyl aluminum used, the rougher the particle surface of the resulting polymer.

• 한국해양학회지
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• v.30 no.5
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• pp.390-402
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• 1995

Bimonthly sampling was carried out over the period February 1983 to April 1985 at two stations in Kwang-yang Bay, Korea, in order to study the temporal changes of benthic ploychaete communities. In addition, an important focus of the study was the large-scale reclamation and dredging operations that were taking place for industrial purposes during the study period. The muddy station, located on the main channel, showed high mud content (94%), whereas the sandy station, situated on the north channel of Myodo, demonstrated mud content of 42%. At the muddy station, the number of species and individuals were highest in the early sampling stage, but markedly declined in October 1983, and then gradually increased as in the early state. At the sandy station, the number of species highly oscillated during the entire period. The density was affected by the pectinated Lagis bocki showing particulary high density in February 1983 and 1984. However, the high density in the winter time did not occur in February 1985. The analysis of similarities and clusterings between communities were carried out to evaluate temporal changes in community structure. Significant changes occurred during the study period in the community structures at both stations, but each maintained different patterns of species dominance over time. At the muddy station, this transitionary phase was found in October 1983 but in December 1984 at the sandy station. Comparisons with earlier communities suggest that faunal changes in the dominant species composition occurred from Lumbrineris longifolia to Heteromastus filiformis over this time period. The colonization of this opportunistic pioneer, H, filiformis, seems to manifest environmental disturbances in this bay area.

• Journal of the Korean earth science society
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• v.26 no.6
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• pp.573-583
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• 2005

[ $PM_{10}\;and\;PM_{2.5}$ ] aerosols were collected at Busan from March, 2004 to December, 2004, and the concentrations of some metal elements were chemically analyzed to study their characteristics. The mean concentration of $PM_{10}$ was $58.2{\mu}g/m^3$ with a range of 8.3 to $161.1{\mu}g/m^3$. The mean concentration of $PM_{2.5}$ was $29.3{\mu}g/m^3$ with a range of 2.8 to $65.3\mu}g/m^3$. The mean mass concentrations of Asian dust and non Asian dust in $PM_{10}$ were $121.5\mu}g/m^3$ and $56.0{\mu}g/,^3$ respectively. The mean values of crustal enrichment factors for six elements (Cd, Cr, Cu, Ni, Pb and Zn) were all higher than 10, possibly suggesting the influence of anthropogenic sources. The crustal enrichment factors of some heavy metal elements in non-Asian dust (NAD) were higher than those in Asian dust (AD), possibly due to anthropogenic emissions transported from industries around this area by westerly wind. The soil contribution ratios for $PM_{10}$ and $PM_{2.5}$ were $15.2\%$ and $17.5\%$ on the whole. and those of AD/NAD for $PM_{10}$ and $PM_{2.5}$ were 1.9 and 2.1, respectively.

• 대한공업교육학회지
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• v.36 no.1
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• pp.149-166
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• 2011

The purpose of this study was to develop a creative problem-solving competition program in order to provide an opportunity for junior high schoolers to solve problems on the basis of technological hands-on activities by deploying their creative problem-solving skills and to foster their cooperative and challenging spirits by tackling the given problems in group. Relevant literature and competition programs were analyzed to develop a junior high school competition program for creative problem solving on the basis of technological hands-on activities. This study was implemented in three stages: preparing, developing and applying. In the preparation stage, the content structure of technology and the fields of corresponding hands-on activities were investigated, and creativity theories were analyzed. Besides, domestic and foreign creativity-related competition programs were checked. In the development stage, an overview of the nature, object, question making and evaluation of a competition program for creative problem solving on the basis of technological hands-on activities was presented, and a program was developed, which consisted of three stages: planning, operating and evaluating. In the application stage, every student in a selected junior high school participated in the competition program. The findings of the study were as follows: First, the competition program developed in this study intended to offer a chance for every junior high schooler to solve problems on the basis of technological hands-on activities to display their creative problem-solving skills. Second, the program was designed to include planning, operating and evaluation stages, after the nature and object of the competition program and in which way question making and evaluation should be fulfilled were determined. Third, the competition program dealt with five areas according to the content structure of technology: manufacturing technology, construction technology, transportation technology, communication technology and biotechnology. And questions for each area and student worksheets were developed. Fourth, the program was utilized in a junior high school to give an example.

• Journal of Korean Society of Forest Science
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• v.86 no.3
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• pp.342-351
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• 1997

The objective of this study was to compare acid-neutralizing and buffering capacity of four tree species against soil acidification by acid rain. About 30-year-old forests composed of Pinus rigida, Alnus hirsuta, Quercus mongolica, and Liriodendron tulipifera in a provincial experimental forest located 15km east from Banwol Industrial Complex in Kyonggido were used in this study. Incident precipitation, throughfall and stemflow, and soil samples were collected from May to September, 1996 to analyze their pH and canon concentrations. Internal leaf pH, external acid neutralizing capacity(ENC), and buffering capacity index(BCI) of leaves were also determined. The incident precipitation showed an average pH of 4.56, with the percentage of acid rain incidents being 74%. The average soil pH of the study area was 4.15. The pH of throughfall and stemflow in all four species was higher than that of precipitation except that of the stemflow of Pinus rigida which showed a pH of 3.73. The throughfall of Liriodendron tulipifera showed the highest pH of 5.38. The pH of throughfall and stemflow showed a positive correlation and no correlation, respectively, with precipitations. The most abundant cation in precipitation was Ca. The canon concentraions in throughfall and stemflow decreased in the following order of K, Na, Ca, and Mg. Cation concentrations in stemflow were highest in Lirioendron tulipifera and lowest in Pines rigida. Nutrient leaching from above ground increased with decreasing pH of precipitation. The pH of stemflow showed a positive correlation with ENC and BCI. The highest values in ENC, BCI, soil pH, and soil cation concentrations were observed in Liriodendron tulipifera, while the lowest values were obtained in Pinus rigida, It was concluded that Liriodendron tulipifera had highest neutralizing capacity against acid rain, while Pinus rigida had the lowest capacity and even promoted acidification of soil.

• Knowledge Management Research
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• v.21 no.3
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• pp.249-269
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• 2020

Recently, as the online market has matured, it is facing many problems to prevent the growth. The most common problem is the homogenization of online products, which fails to increase the number of customers any more. Moreover, although the portion of the online market has increased significantly, it now becomes essential to expand offline for further development. In response, many online firms have recently sought to expand their businesses and marketing channels by securing offline spaces that can complement the limitations of online platforms, on top of their existing advantages of online channels. Based on their competitive advantage in terms of analyzing large volumes of customer data utilizing information technologies (e.g., big data and artificial intelligence), they are reinforcing their offline influence as well through this online for offline (O4O) business model. On the other hand, most of the existing research has primarily focused on online to offline (O2O) business model, and there is still a lack of research on O4O business models, which have been actively attempted in various industrial fields in recent years. Since a few of O4O-related studies have been conducted only in an experience marketing setting following a case study method, it is critical to conduct an empirical study on O4O selection attributes and their impact on customer satisfaction and loyalty. Therefore, focusing on China's representative O4O business model, 'Fresh Hema,' this study attempts to identify some key selection attributes specialized for O4O services from the customers' viewpoint and examine the impact of these attributes on customer satisfaction and loyalty. The results of the structural equation modeling (SEM) with 300 O4O (Fresh Hema) experienced customers, reveal that, out of seven O4O selection attributes, four (mobile app quality, mobile payment, product quality, and store facilities) have an impact on customer satisfaction, which also leads to customer loyalty (reuse intention, recommendation intention, and brand attachment). This study would help managers in an O4O area well adapt to rapidly changing customer needs and provide them with some guidelines for enhancing both customer satisfaction and loyalty by allocating more resources to more significant selection attributes, rather than less significant ones.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.10 no.6
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• pp.15-26
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• 2015

The purpose of this study was to examine the area, theme and method of domestic articles on the successful establishment of venture companies, which were presented between 1998 and 2014, according to related basic classification criteria in an effort to shed light on the characteristics of these studies. It's basically meant to make a contribution to the development of research on the success of venture business and to be of practical use for the success of venture companies in our country. After related earlier studies were analyzed, 164 articles were collected, and 64 articles were selected from among them. The articles that were overlapped, not presented or not registered were excluded. The related studies had been conducted by different learned societies that were interested in the same research themes, and the studies were primarily led by the Korean Society of Business Venturing as of 2014, especially by Asia-Pacific Journal of Business Venturing and Entrepreneurship that was a journal published by this society. This society seemed to have taken the initiative in this field. There was a tendency that the related studies increased in number due to the shifts of modern industrial society and the changing policies of the government, as the number of the studies has been on the steady rise since 2012. In terms of method, quantitative research methods, especially descriptive studies, were prevailing. To step up the development of research into this field, a wide variety of research methods should be utilized in the future. As for the sphere of research, the characteristics of founders, strategic characteristics and environmental characteristics were mainly covered as the success factors of venture business. More diverse variables should be explored as well to make more advanced, extended research in the years to come. The findings of the study are expected to provide both theoretical and practical information on the establishment and success of venture business to make a contribution to the development of research.

• Journal of Distribution Research
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• v.17 no.3
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• pp.115-132
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• 2012

This study empirically examines the impact of SSM market entry on changes in market shares among retailing types. The data is monthly time-series data spanning over the period from January 2000 to December 2010, and the effect of SSM market entry on market shares of retailing types is analyzed by utilizing several key factors such as the number of new SSM monthly entrants, total number of SSMs, the proportion of new SSM entrant that is smaller than $165m^2$ to total new SSM entrants. According to the Korean Standard Industrial Classification codes, the retailing type is classified into 5 groups: department stores, retail sale in other non-specialized large stores(big marts), supermarkets, convenience stores, and retail sale in other non-specialized stores with food or beverages predominating (others). The market shares of retailing types are calculated by the ratio of each retailing type monthly sales to total monthly retailing sales in which total retailing sales is the sum of each retailing type sales. The empirical model controls for the size effects with the number of monthly employees for each retailing type and the macroeconomic effects with M2. The empirical model employed in this study is as follows; $$MS_i=f(NewSSM,\;CumSSM,\;employ_i,\;under165,\;M2)$$ where $MS_i$ is the market share of each retailing type (department stores, big marts), supermarkets, convenience stores, and others), NewSSM is the number of new SSM monthly entrants, CumSSM is total number of SSMs, $employ_i$ is the number of monthly employees for each retailing type, and under165 is the proportion of new SSM entrant that is smaller than $165m^2$ to total new SSM entrants. The correlation among these variables are reported in