• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.3
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• pp.200-209
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• 2013

In this paper, the types of B-dot controller and the review results of B-dot controller stability are summarized. Also, it is confirmed that B-dot controller is very useful and essential tool when a dawn-dusk low earth orbit(LEO) large satellite has especially to capture the Sun for a required power supply in a reliable way after anomaly and that its algorithm is very simple for on-board implementation. New physical interpretation of B-dot controller is presented as a result of extensive theoretical investigation introducing the concept of transient control torque and steady state control torque. Also, the failure effect analysis results of magnetic torquers as well as a simulation verification are included. And the design recommendation for optimal design is provided to cope with the failure of magnetic torquer. Nonlinear simulation results are included to justify its capability as well as its performance for an application to a dawn-dusk LEO large satellite.

• The Journal of Korean Institute for Practical Engineering Education
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• v.3 no.2
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• pp.18-26
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• 2011

Computational chemistry is one of the chemistry fields that deals with the theoretical chemistry problem using computer calculations and can be described as the chemistry lab moved on computer space. In line with recent enhancement of processing capability of computers, utilization of high performance computer cannot be overemphasized in the field of computational chemistry in performing complex calculation of huge molecular structure and simulation. While they have to use commands and consoles for high performance computer to execute complex calculation of huge molecular structure and simulation, most of students in natural science and engineering, who are not experts in computer technically, are likely to be unaware of UNIX. Under the circumstances, web-based educational support system for computational chemistry is needed to enable them to practice computational chemistry, even not knowing UNIX command. In this study, e-Chem, one of such educational support systems, is developed by using Liferay portal platform, which is a Java open source more oriented to standard and outstanding in its content management and collaboration function than other web portals. By using this system, even students who are not familiar with computer, are expected to take part in lab classes and save time learning Unix command and also enhance the learning efficiency by using familiar interface.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.8
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• pp.462-469
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• 2017

Eutrophication and shortage of phosphate ore raise the necessity of phosphate removal and recovery from wastewater treatment plants. Especially, a sludge treatment system containing highly concentrated phosphate should be targeted for phosphate removal and recovery. This study thus aimed to evaluate the capability of the struvite crystallization process for phosphate removal and recovery from a sludge treatment system of a wastewater treatment plant. Analysis on phosphate concentrations and masses in the sludge treatment system revealed that digested sludge and centrate have phosphate concentrations and masses, high enough to adopt the struvite crystallization process. Chemical equilibrium modeling indicated that the struvite crystallization reaction substantially occurred with pH higher than 8 and $Mg^{2+}$ concentration 1.2 times higher than its theoretical requirement. A series of batch tests with digested sludge and centrate indicated that the phosphate removal reaction by struvite crystallization followed a first-order kinetics and reached over 80% removal efficiency at equilibrium. Aeration in the batch tests was found to purge $CO_2$ in sludge or centrate and increase pH up to 8.7, without adding NaOH. Thus, we concluded that the struvite crystallization process could be an efficient and economical process for phosphate removal and recovery from a wastewater treatment plant.

• Journal of Technology Innovation
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• v.18 no.2
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• pp.175-219
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• 2010

Since diversification can be a necessary means for company's survival and the conservation of its success, hundreds of studies have been done by three schools of industrial economics, strategic management, and Neo-Schumpeterian economics for over 30 years. However, any school has not presented a model comprehensively explaining diversification' success or failure. The study tried to suggest a theoretical framework integrating findings came from three schools. The framework considers both firm's technological capabilities and sector-specific characteristics as well as reflects a Neo-Schumpeterian view emphasizing technological aspects. The goal of the study is finding major reasons of success and failure during company's diversification through studying three diversification cases of Samsung. Our findings show that the diversification toward TFT-LCD was easier and more successful than the diversification toward microprocessor because DRAM is more similar to TFT-LCD than microprocessor. Samsung also tended to build only the types of capabilities which were originated from capabilities accumulated in DRAM business. Our findings give firm's strategists a lesson that they can increase the probability of success in diversification, if only they should simultaneously consider a new sector's characteristics, a firm's technological capabilities accumulated in old sectors, and the availability of old capabilities for being applied to a new sector.

• The Journal of the Acoustical Society of Korea
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• v.22 no.3
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• pp.217-223
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• 2003

A novel cooling method induced by acoustic streaming generated by ultrasonic vibration at 30㎑ is presented. Ultrasonic vibration is obtained by piezoelectric devices and the maximum vibration amplitude of 50 m is achieved by including a horn, mechanical vibration amplifier in the system and making the complete system resonate. To investigate the enhancement of heat transfer capability of acoustic streaming, the temperature variations of heat source and air in the vicinity of heat source are measured in real-time. It is observed that acoustic streaming is instantly induced by ultrasonic vibration, resulting in the significant temperature drop due to the bulk air flow caused by acoustic streaming. In addition, it is observed that the cooling effect on the heat source is maximized when the gap between the ultrasonic vibrator and heat source coincides with the multiples of half-wavelength of the ultrasonic wave. This fact results from the resonance of the sound wave. The theoretical analysis of the dependence on the gap is also accomplished and verified by experiment. The advantage of the proposed cooling method by acoustic streaming is noise-free due to the ultrasonic vibration and maintenance-free because of the absence of moving parts. Moreover. This cooling method can be utilized to the nano and micro-electro mechanical systems, where the fan-based conventional cooling method can not be employed.

• Korean Journal of Social Welfare
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• v.65 no.2
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• pp.103-130
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• 2013

Although both ecosystem theory and empowerment have become the most prevalent candidate for integrated paradigm for social welfare practices, they could not overcome completely the long-standing and sharp divides between micro and macro practices, that is, between subject and structure as a main explanatory element in social welfare realm. Along with such traditional dualism and tension, a new emerging divide between modernism and postmodernism regarding intrinsic mission and roles of social welfare has urged strongly to develop the overarching theoretical framework for social welfare practice. In this regard, this study aims to recast the ecosystem theory and empowerment through the reflexive modernization theory of critical sociologist Anthony Giddens. With relatively strong emphasis on human capability coined as the reflexivity, Giddens's own creative theory of modernization can be thoroughly expected to provide a solid foundation of integrated paradigm enough to bridge the existing dualisms in social welfare theory and practice. Especially, his unique account of integrated way of how human agency is involved in the construction of social structure and how to transform each other recursively has profound implication for empowerment to be adequate and proper comprehensive framework for social welfare practice.

• 한국벤처창업학회:학술대회논문집
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• 2009.10a
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• pp.111-138
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• 2009

This research focuses on what factors determine firm's decisions on R&D outsourcing and how R&D outsourcing affect R&D performance. In recent years many firms outsource R&D activities instead of internalizing it. Thus, further investigation is necessary to find out this recent trend. Based on several theoretical background the study developed three determining factors of R&D outsourcing which are transactional level, firm level, and risk level. Transactional level composes of independent variables such as R&D cost saving, asset specificity and uncertainty which mainly comes from Transaction Cost Economics theory. Firm level composes of openness to technology from outer source, R&D capability, and outsourcing experience. Risk level composes of technological risk, cost-related risk and managerial risk. The result shows that R&D outsourcing is significantly related to cost saving aspect, low asset specific firms, firms without solid technological background, firms which are open to external technology, firms with other types of outsourcing experience, and firms which take technological risks. However, proposed relationship between degree of R&D outsourcing and R&D performance found out to be insignificant. This research is contribute to the field of outsourcing study since it will give guidance to managers who need to make strategic decisions on R&D outsourcing activities.

• Journal of Global Scholars of Marketing Science
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• v.18 no.4
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• pp.277-306
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• 2008

Knowledge1 is considered to be a key element of understanding how organizations gain and sustain competitive advantages. But very few firms are capable of creating the requisite knowledge and thus, firms should acquire and exploit new knowledge through knowledge transfer processes. The empirical part of this study involves examining relationships among adaptability of knowledge and knowledge transfer and marketing performance and testing the moderating roles of absorptive capacity, socialization and local marketing knowledge. This study is organized as follows: (1) Previous literature on knowledge, knowledge transfer and absorptive capacity is summarized, followed by the development of hypotheses derived from the knowledge-based view and absorptive capacity. (2) The hypotheses are tested with data collected from MNCs' subsidiaries performing marketing activities in Korea.Thestudyisclosedwithfindings,implications,andconclusions. Following six research hypotheses are drawn from literature review in related areas: H1: Adaptability of knowledge transferred from the MNCs' headquarters and other subsidiaries is positively associated with knowledge inflows into the receiving subsidiary. H2: The level of marketing knowledge transferred from the MNCs' headquarters and other subsidiaries is positively associated with marketing performance of the receiving subsidiary. H3: Increases in potential absorptive capacity will enhance the relationship between adaptability of knowledge and the level of marketing knowledge transfer. H4: Increases in realized absorptive capacity will enhance the relationship between the level of knowledge transfer and marketing performance of the receiving subsidiary. H5: Increases in socialization activity among the headquarters and subsidiaries will enhance the relationship between adaptability of knowledge and the level of marketing knowledge transfer. H6: Increases in the level of locally developed marketing knowledge will enhance the relationship between the level of knowledge transfer and marketing performance of the receiving subsidiary. The research framework that illustrates the proposed hypotheses is presented in figure 1. The unit of analysis for this study is knowledge transfer from the MNCs' headquarters and other subsidiaries to their subsidiaries operating in South Korea. The population for this study consists of subsidiaries established either as joint ventures or as wholly-owned subsidiaries. A group of 603 foreign firms were drawn from diverse industry organizations and business societies. After personal contact, telephone, fax, and e-mail to request that the respondents complete the questionnaire, 282 valid questionnaires from 133 initial sample companies were collected. The results of the empirical analyses significantly support all of the proposed hypotheses except hypothesis 3. Adaptability of external knowledge promotes knowledge transfer and the relationship is moderated by a firm's potential knowledge absorptive capacity. On the other hand, knowledge transfer improves a firm's marketing performance and a firm's realized knowledge absorptive capacity and local marketing knowledge moderate the relationship. The theoretical and practical implications of the findings in this study are as follows: (1) firms must take seeking, transferring, sharing and exploiting of external knowledge into serious consideration, while simultaneously creating knowledge to support the necessary business operations, remain competitive, and achieve superior performance. (2) Firms should continuously seek to develop their knowledge absorptive capacity (both potential and realized capacity) to absorb, learn and utilize valuable external knowledge. (3) Firms should emphasize not only absorptive capacity, but also development of local knowledge. Firms with strong absorptive capability and local knowledge can learn and transfer more external knowledge, which can be translated into greater levels of competence and performance.

• Journal of the Economic Geographical Society of Korea
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• v.15 no.2
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• pp.206-227
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• 2012

This study investigates the interaction mechanisms and processes between cyber space and real space. In particular, we analyze the relationships between changes on the economic landscape of the Bookchon region and the information supply and demand for this area on the Internet Blogs. In order to obtain the behavioral data about how people get information for Bookchon area and the reaction afterward, we perform questionnaire survey. The results of analysis reveal that there are significant connection between real space and cyber space, Internet Blog in particular. Internet Blog is the major media obtaining information about Bookchon area for major portion of people. Most people visit Bookchon after searching informations about it via Internet Blog. In particular, young generations who possess better capability to treat social media. At the same time, female, student, and office workers show these attitudes very strongly. We introduce a conceptual model for the interaction processes between cyber space and real space based on the survey data analysis, and propose a simple theoretical model for the dynamics of the total number of visitors about specific place with the experience of cyber space visit.

• Korean Journal of Medicinal Crop Science
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• v.5 no.4
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• pp.284-288
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• 1997

In order to study on suitable harvest time of adlay utilizing self-feeding combine harvester with four rows, which is originally designed for rice harvest, harvesting were carried out at four different times (40, 50, 60 and 70 days after anthesis) . For efficient operation, appropriate working rows were 2 rows at 50 days after anthesis and working speed was 0.26m/sec at 60 days after anthesis. Theoretical working capability was 11.23a/hr at 60 days after anthesis. As the harvesting was delayed, water content of adlay decreased. Water content of culm+leaf was $69.7{\sim}55.3%$ and water content of grain was 34.2% at 60 days after anthesis. The later adlay was harvested. the higher the percent of ripened grain was. But the immature grain was decreased. Remnants was less than 1.8% at 60 days after anthesis. The later adlay was harvested, the heavier volume weight was. Yield was the highest at 60 days after anthesis. When utilizing self-feeding combine harvester with four rows, which was originally designed for rice harvest, suitable harvesting time was 60 days after anthesis. Therefore, theoretically suitable harvest time was 68 days after anthesis.