• School Mathematics
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• v.1 no.1
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• pp.123-133
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• 1999

For an appropriate assessment in mathematics, students should play an active role in their learning by becoming aware of what they have learned in mathematics and by being able to assess their attainment of mathematical knowledge. The process of actively examining and monitoring students' own progress in learning and understanding of their mathematical knowledge, process, and attitude is called self-assessment, Researchers in mathematics education have found some important facts about the meta-cognitive process which is related to self-assessment : i. e. meta-cognition progress is composed of being aware of ones' own personal thinking of content knowledge and cognitive process(self-awareness) and engagement in self-evaluation. Tipical method for self-assessment in mathematics developed upon above finding about meta-cognitive progress is describing about students' knowledge and their problem solving strategies. In the beginning of the description in mathematics about themselves, students are required to answer which part they know and which part they don't know. Self-assessment of students' attitudes and dispositions can be just as important as assessment of their specific mathematical abilities. To make the self-assessment method a success, teachers should let students' have confidence and earn their cooperation by let them overcoming fear to be known the their ability to other students. In conclusion, self-assessment encourages students to assume an active role in development of mathematical power. For teachers, student self-assessment activities can provide a prism through which the development of students' mathematical power can be viewed.

• Journal of Distribution Science
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• v.14 no.8
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• pp.51-57
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• 2016

Purpose - If control-ownership disparity is large, managers will not actively reduce costs; rather, they will maintain unutilized resources or possess surplus resources even when sales decrease with the purpose of increasing personal utility from status, power, compensation, and prestige. These managers' utility maximizing tendencies cause cost stickiness. We examine whether asymmetric behavior related to costs becomes stronger when there is a large disparity between ownership and control rights. Research design, data, and methodology - We construct a regression model to examine the relationship between control-ownership disparity and cost stickiness. STICKY, a dependent variable representing cost stickiness is a value found using the method of Weiss (2010), and Disparity is an interest variable that shows control-ownership disparity. Results - This study is based from the unique situations in Korea, in which high control-ownership disparity is common in firms. Large control-ownership disparity was found to increase cost stickiness of corporations. Conclusions - The results of this study imply that controlling shareholders may be regarded as a threat to the interests of minority shareholders and corporate values especially when controlling shareholders have significant influence over managers or the power to make managerial decisions as owners of a corporation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.10 s.181
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• pp.2654-2663
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• 2000

Steam turbine rotors are the most critical and highly stressed components of a steam power plant; therefore, the life expectancy of the turbine rotor is an important consideration for the safety of a steam power plant. The objective of this paper is to develop a life estimation program for turbine rotors for all possible operating conditions. For this purpose, finite element analysis was carried out for four normal operating modes (cold, warm, hot and very hot starts) using ABAQUS codes. The results are made into databases to evaluate the life expenditure for an actual operating condition. For any other possible abnormal operating condition, the operating data are transmitted to the server (workstation) through a network to carry out finite element analysis. Damage estimation is carried out by transmitting the finite element analysis results to the personal computer, and then the life expectancy is calculated.

• Journal of Power System Engineering
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• v.5 no.4
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• pp.82-89
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• 2001

To design a structural or a mechanical system with the best performance, the main procedure of a typical design usually consists of repeated modifications of design parameters and the investigation of the system response for each set of these parameters. But this procedure requires much time, effort and experience. Sensitivity analysis can provide systematic information for improving performance of a system. The author has studied on the development of the structural analysis algorithm and suggested recently the transfer stiffness coefficient method(TSCM). This method is very suitable algorithm to a personal computer because the concept of the TSCM is based on the transfer of the nodal stiffness coefficients which are related to force and displacement vectors at each node. In this paper, a new sensitivity analysis algorithm using the concept of the TSCM is formulated for the computation of state variable sensitivity in static problems. The trust of the proposed algorithm is confirmed through the comparison with the computation results using existent sensitivity analysis algorithm and reanalysis for computation models.

• Proceedings of the Technology Innovation Conference
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• 1999.12a
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• pp.63-81
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• 1999

The environment of Information and Telecommunication industry has rapidly changed. This is leading the growth of the world economy. Because of the characteristic of the information and communication, the standardization plays a important role in this market. The company that owns the standardization in its industry has dominant power like Microsoft in personal computer software, and Qualcomm in digital cellular phone system. Therefore, to take advantage of this standardization power, it is important to find which technology will be set up as a new standard. This paper presents how to capitalize the standardization as a market strategy. To perform this strategy, we take two steps. The first step is to strategically choose the most important technology or service which would lead the information and telecommunication market. We used modified AHP(Analytic Hierarchy Process) to set the priorities among the various standard related technologies and services, We interviewed with the information and telecommunication experts to find out some criteria and the weights of them. The second step is to select the standard to realize the technology. Actually, this is very hard to decide which technology we should select, because there are lots of alternative standards to develop the technology. In this step, we use a strategic framework for choosing the standard. This framework provides how the research institution and company do to get a maximum benefit from the standardization strategy, Finally, we applied these to Korea's situation simply in order to show how to take advantage of the framework.

• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.206-209
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• 2006

At present, the cold cathode fluorescent lamp (CCFL) using mercury lamp has been generally used far liquid crystal backlight source of personal computer and car navigation and so on. This kind of lamp is more excellent on luminance performance and cost. However, the requirements of liquid crystal backlight due to a light source without mercury have been strongly increased from a viewpoint of the actual influence on environmental preservation and environmental recycling. As fluorescent lamp without mercury, Dielectric Barrier Discharge based rare gas fluorescent lamp (DBD-FL) using xenon (Xe) gas has been studied so far. This DBD lamp has no influence on the human body and environmental recycle. Its operating life is long because electrode is out. In this paper, the simulation and experimental results of soft switching high frequency inverter with reverse blocking single switch as a high frequency power supply circuit for DBD-FL using Xe gas are comparatively evaluated and discussed from a practical point of view.

• The Journal of Asian Finance, Economics and Business
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• v.4 no.1
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• pp.79-86
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• 2017

With the increasing trend of popularity of websites and social networking sites, it is quite evident that companies need to take cautionary measures in protecting the reputations with respect to company and brands. In this process, every company should indulge in enhancing their company and brand image through websites and social networking sites that fortify the bonding nature among them. The always-on nature of websites and social networking sites has contributed to their phenomenal marketing power and altered the balance of power between consumers and firms. Websites and social networks are used by hundreds of millions of people to communicate about a huge range of topics, including personal interests, activities, social events and even public issues. The paper explores a case study of the Ritz-Carlton hotel for their marketing strategy and organizational use of their website and social media in communicating with their customers. Even for the normal luxury traveler who would not have previously used the Internet to research a hotel or make a reservation, ritzcarlton.com is making it possible for them to do so in a sense of the luxury and typical Ritz-Carlton style. It seems to be a staple of the company for years to come.

• ETRI Journal
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• v.27 no.6
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• pp.697-707
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• 2005

This paper proposes a new design of directional couplers with high directivity for personal communication services (PCS) and International Mobile Telecommunications-2000 (IMT-2000). The directional coupler is used to check and verify the power, frequency, and antenna reflection of a signal at transmission stations for mobile communications. The performance requirements of directional couplers are a strong coupling to reduce the effect on the transmitted power and high directivity to suppress the interference of the reflected signals and reduce the errors in communication. So far, various architectures have been proposed to gain high directivity, and there have been many studies used to obtain a strong coupling. However, conventional architectures for high directivity and strong coupling have a directivity of only about 20 dB, and there have been difficulties to achieve the higher directivity of 30 dB suitable for PCS and IMT-2000. This paper proposes a new architecture of directional couplers based on a grounding composed of strip lines, and compares the test results of this directional coupler with conventional ones. The results show that the proposed directional coupler has a directivity of more than 30 dB and is adequate for PCS and IMT-2000.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.12 no.2
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• pp.38-44
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• 1998

This paper presents an integrated fault diagnosis expert system to assist SCADA operators in local control centers which controls unmanned distribution substations in a power system. The proposed system diagnoses various faults occurred in both substation devices and transmission devices. The system can be easily installed without disturbing main SCADA system. The system simply shares the dynamic information including alarms with main SCADA using dual data link interface. And the proposed expert system utilizes the fuzzy reasoning process in order to consider the uncertainty factor. The system is developed using a low cost personal computer owing to the special modular programming and the meta-inf!'lrence structure. Case studies showed a promising possibility.bility.

• Journal of Power Electronics
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• v.9 no.4
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• pp.654-666
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• 2009

Direct torque control (DTC) of induction machines (IM) is a well-known strategy of these drives control which has a fast dynamic and a good tracking response. In this paper a nonlinear DTC of speed sensorless IM drives is presented which is based on input-output feedback linearization control theory. The IM model includes iron losses using a speed dependent shunt resistance which is determined through some effective experiments. A stator flux vector is estimated through a simple integrator based on stator voltage equations in the stationary frame. A novel method is introduced for DC offset compensation which is a major problem of AC machines, especially at low speeds. Rotor speed is also determined using a rotor flux sliding-mode (SM) observer which is capable of rotor flux space vector and rotor speed simultaneous estimation. In addition, stator and rotor resistances are estimated using a simple but effective recursive least squares (RLS) method combined with the so-called SM observer. The proposed control idea is experimentally implemented in real time using a FPGA board synchronized with a personal computer (PC). Simulation and experimental results are presented to show the capability and validity of the proposed control method.