• Journal of the Korea Concrete Institute
• /
• v.13 no.4
• /
• pp.354-361
• /
• 2001

In this paper, three kinds of poly(acrylate-co-methylacrylate) with different number average molecular weight(Mn) were synthesized and studied for the effects on the mechanical properties and the fluidities of the cement mortar admixtured with them. The physical properties of the cement mortar are more favorably enhanced by the poly(acrylate-co-methylacrylate) of Mn,, 5,000 than that of Mn, 2,000∼3,000. And the optimum dosage was decided to ca. 0.6 % of cement weight in cement mortar. However, the dispersion abilities of the polymers in cement mortar was not kept long time. This last result could not be explained by the theory that the fluidity of the cement mortar added with the slow releasing polycarboxylates is kept by the releasing of the carboxylic group of the copolymer in alkaline solution of cement paste.

• Applied Chemistry for Engineering
• /
• v.29 no.6
• /
• pp.657-662
• /
• 2018

In this study, the effect of $Pt/TiO_2$ catalysts on the CO oxidation reaction at room temperature was investigated using various $TiO_2$ supports with different physical properties to compare and evaluate $Pt/TiO_2$ catalysts. Physicochemical properties of the catalyst were alanyzed using XPS, CO-chemisorption, BET, and CO-TPD. As a result, when the active particle diameter was smaller, while the metal dispersion and surface area were larger, the CO room temperature oxidation reaction was better. These physical properties increased the number of active sites, causing the target material to increase the adsorption amount of CO. In addition, when the $O_2$-consumption increased, the CO-room temperature oxidation reaction activity increased due to the excellent oxygen-transferring ability.

• Nuclear Engineering and Technology
• /
• v.53 no.8
• /
• pp.2582-2590
• /
• 2021

The high-energy milling is one of the most extended techniques to produce Oxide dispersion strengthened (ODS) powder steels for nuclear applications. The consequences of the high energy mill process on the final powders can be measured by means of deformation level, size, morphology and alloying degree. In this work, an ODS ferritic steel, Fe-14Cr-5Al-3W-0.4Ti-0.25Y₂O₃-0.6Zr, was fabricated using two different mechanical alloying (MA) conditions (M_std and M_act) and subsequently consolidated by Spark Plasma Sintering (SPS). Milling conditions were set to evidence the effectivity of milling by changing the revolutions per minute (rpm) and dwell milling time. Differences on the particle size distribution as well as on the stored plastic deformation were observed, determining the consolidation ability of the material and the achieved microstructure. Since recrystallization depends on the plastic deformation degree, the composition of each particle and the promoted oxide dispersion, a dual grain size distribution was attained after SPS consolidation. M_act showed the highest areas of ultrafine regions when the material is consolidated at 1100 ℃. Microhardness and small punch tests were used to evaluate the material under room temperature and up to 500 ℃. The produced materials have attained remarkable mechanical properties under high temperature conditions.

• Analytical Science and Technology
• /
• v.19 no.5
• /
• pp.394-399
• /
• 2006

The polishing performance and the relationships of electrochemistry depending upon oxidizers and additives in the tungsten CMP slurry used in semiconductor industry were investigated. Hydrogen peroxide, ferric nitrate and potassium iodate were used as oxidizers and they showed different oxidation reactions on tungsten film depending on the kind of oxidizers and pH of slurry. The differences influenced the polishing performance. Etching reaction was predominated in the hydrogen peroxide. However, passivation reaction was prevailed in ferric nitrate and potassium iodate. TMAH and KOH raised the potential energy and removal rate of tungsten, and improved a dispersion characteristic of slurry by increasing absolute value of zeta potential. Addition of 100 ppm of poly(acrylic acid) of M.W. 250,000 improved dispersion ability.

• Journal of Global Scholars of Marketing Science
• /
• v.19 no.2
• /
• pp.40-52
• /
• 2009

Franchising is one of the fastest growing types of business. It is already popular and well-known in the U.S., and has been growing in many other countries including Korea. Furthermore, many Korean franchising companies have expanded their business overseas actively. According to the data by the Ministry of Industry and Resource, 82 companies out of a sample of 500 franchising companies are already operating in many foreign countries and 48% of them have started their foreign business since 2006. This clearly indicates the fast growing current trend of foreign operation by Korean franchising companies. In spite of the fast growing trend of foreign expansion in the industry, academic research on internationalization of franchising companies is extremely difficult to find. Accordingly, academic research on the issue is necessary and urgent in Korea. Among the various research questions on internationalization of franchising business, this study intends to investigate the difference in organizational factors between the franchising companies doing foreign operation and those doing business only domestically. More specifically, this research has the following purposes. First, considering the lack of theoretical basis of previous studies, resource-based theory and agency theory are employed as the theoretical bases. Second, this study explains the difference in internationalization based on organizational factors such as company size, history and growth rate. Third, the five hypotheses regarding the difference in organizational factors are presented and tested empirically, which is the first attempt in the area of this topic. Finally, the study attempts to clarify the conflicting implications among theories regarding some organizational factos such as growth rate. As the theoretical background, resource-based theory and agency theory are discussed. According to resource-based theory, a firm can grow continuously when it has competence and resource, and also the ability to develop them. The competence and resource can include capital, human resource, management skill, market information, ability to manage risk, etc. Meanwhile, agency theory views the relationship between franchisor and franchisee as an agency relationship. In agency theory, bonding capability and monitoring capability are the two key factors which promote internationalization of franchising companies. Based on the two theories, a conceptual model is designed. The model consists of two groups of variables. One is organizational factors including size, history, growth rate, price bonding and geographic dispersion. The other is whether a franchising company is operating overseas or not. We developed the following five research hypotheses basically describing the relationship between organizational factors and internationalization of franchising companies. H1: The size of franchising companies operating overseas is larger than that of franchising companies operating domestically. H2: The history of franchising companies operating overseas is longer than that of franchising companies operating domestically. H3: The growth rate of franchising companies operating overseas is higher than that of franchising companies operating domestically. H4: The price bonding of franchising companies operating overseas is higher than that of franchising companies operating domestically. H5: The geographic dispersion of franchising companies operating overseas is wider than that of franchising companies operating domestically. Data for the analyses are obtained from 2005 Korea Franchise Survey data co-generated by Ministry of Industry and Resource, GS1 Korea, and Korea Franchise Association. Out of 2,804 population companies, 2,489 companies are excluded for various reasons and 315 companies are selected as the final sample. Prior to hypotheses tests, validity and reliability of the measures of size, history, growth rate and price bonding are examined for further analyses. Geographic dispersion is not validated since it is measured using nominal data. A series of independent sample T-tests is used to find out whether there exists any significant difference between the companies internationalized and those operating only domestically for each organizational factor. Among the five factors, size and geographic dispersion show significant difference, growth rate and price bonding do not reveal any difference and, finally, history factor shows conflicting results in the difference depending on how to measure it.