• 한국연소학회:학술대회논문집
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• 2006.10a
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• pp.276-281
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• 2006

Although fireside corrosion of heat transfer surfaces in coal fired steam generators has been a problem to some extent for a number of tears, with the advent of low NOx firing systems these surfaces can be exposed to conditions that will exacerbate wastage rates. Numerous reports of waterwall wastage in coal fired boilers have appeared in the literature. It is believed that wastage results both from gaseous phase attack of metal surfaces and from deposition of ash and unburned fuel. Gaseous phase attack is known to occur in the presence of reducing sulfur species such as $H_2S$ and in the presence of fuel chlorine. The highest wastage rates are thought to be due to deposition of unoxidized material and the presence of fuel chlorine. Localized wall and near wall conditions that may exacerbate wastage include reducing conditions, high temperatures, high heat fluxes, and a high fraction of unoxidized material deposited. So, this study is directed at developing an advanced corrosion model in coal-fired utility boilers.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.816-821
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• 2001

The generation of isolated grids by pulsed converters with characteristics close to the mains of the utility companies is a pretentious task. For generation of three-phase four-wire isolated grids are presented possible topologies and the demands on the system control are processed. For control of all conceivable load and error conditions, an extensive control technology is necessary. This must permit unsymmetrical operating conditions for an unlimited period but recognize errors simultaneously and therefore an overloading the consumer and the power semiconductors reliable may prevent. Measurement results on an experimental plant show the problems to be solved.

• The Korean Journal of Nuclear Medicine
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• v.35 no.1
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• pp.1-11
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• 2001

Current scintigraphic tests of gastrointestinal motor function provides relevant pathophysiologic information, but their clinical utility is controversial. Many scintigraphic methods are developed to investigate gastrointestinal motility from oral cavity to colon. These are esophageal transit scintigraphy, oropharyngeal transit study, gastric emptying test, small bowel transit time measurement, colon transit study and gastroesopahgeal reflux scintigraphy. Scintigraphy of gastrointestinal tract is the most physiologic and noninvasive method to evaluate gastrointestinal motility disorders. Stomach emptying test is regarded as a gold standard in motility study. Gastrointestinal transit scintigraphy also has a certain role in assessment of drug effect to GI motility and changes alter therapy of motility disorders. Scintigraphy provides noninvasive and quantitative assessment of physiological transit throughout the gastrointestinal tract, and it is extremely useful for diagnosing gastrointestinal motor dysfunction. This article reviews the current procedures, indications, significance and guidelines for gastrointestinal motility measurements by scintigraphy.

• Proceedings of the KIEE Conference
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• 2007.10c
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• pp.238-240
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• 2007

This paper present adaptation method of rail potential test to verify DC railway system's performance and safety. For protection of person and utility caused by rail potential rise, international standard to limit rail potential rise is made and rail potential is tested at the time of plan and construction of DC railway system in foreign country. So, we need rail potential test at the opening time and prepare a continuous monitoring technique of rail potential and a limitation method of rail potential rise. For these, we describe cause of rail potential rise, international standard about rail potential, protection principle, an example of calculation and measurement, and adaptation method for performance test.

• Korean Journal of Human Ecology
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• v.6 no.2
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• pp.37-45
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• 1997

The purpose of this study is to identify parental stress of working mothers with young children and to fine its rented variables. subjects were consisted of 108 working mothers who had children from 3 to 6 ages. The measurement instruments are the questionnaire which consisting the following parts; Parenting Daily Hassles, Employment Subjective Expected Utility, Beck Depression Inventory, Emotionality, Activity, Sociablity Temperament Scale. The data were analyzed by the statistical method based on frequency, percentile, t-test, F-test, Pearson's correlation, and multiple regression. The main results were as follows: 1. Parental stress of working mother had a significant correlation with working mothers' negative attitudes for their occupations. 2. The higher working mothers' depression resulted in the higher working parental stress. 3. There was a significant positive correlation between children's difficult temperament and parental stress of working mothers. 4. The influential variables on parental stress of working mothers were mothers' attitude to her occupations and children's temperament.

• Transactions on Control, Automation and Systems Engineering
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• v.2 no.3
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• pp.157-162
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• 2000

The inverted pendulum is a typical example of unstable systems and has been used for verification of designed control systems. It is also very popular in control education in laboratories, serving as a good example to show the utility of the state space approach to the controller design. This paper shows two kinds of experiment using inverted pendulum: one is the stabilization of a single spherical inverted pendulum by a plane manipulator using visual feedback, and the other is the state transfer control of a double pendulum. In the former experiment, the feedback stabilization using a CCD camera has major importance as an example of controller implementation with non-contact measurement. The latter involves the standard stabilizing regulation method and nonlinear control techniques. The details of the experimental systems, the control algorithms and the experimental results will be given.

• Fibers and Polymers
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• v.2 no.2
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• pp.71-74
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• 2001

Surface characterization of materials has been considered critical in the development of biomaterials, as many unfavorable responses from the body occur at the interface between a material and the body component. The contact angle measurement is one means to characterize the surface properties and to correlate them to the biocompatibility of materials. In this paper, surface characteristics of silk fibroin/S-carboxymethyl kerateine, representative fibrous proteins, were investigated by contact angle measurements of ESCA. The biocompatibility of the blends was evaluated based on minimal interfacial free energy concept, and compared with other potential biomaterials. It was also hypothesized that the enhanced surface polarity of the blends was generated from the conformational transition of proteins. This approach to evaluate the biocompatibility of materials based on surface characteristics may find wide utility in many biomedical applications.

• Journal of the Korean Home Economics Association
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• v.44 no.12
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• pp.105-115
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• 2006

The purpose of this study is to apply conjoint analysis to fashion product development. Conjoint measurement was undertaken on the traditional casual market, composed of Polo, Beanpole, Maru and Giordano brands. Product's attributes, such as brand name, price, country of origin and style, were selected as choice factors. Twelve profiles were used for full-profile stimulus cards method. Based on the importance and utility rates of the product attributes, preferences for the products currently in the market and simulated products were calculated. The results increased our understanding of the trends in traditional casual market and assisted in the preparation of marketing strategies for each brand.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.49-54
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• 2001

Measurement of welding residual stresses is one of important tasks to assess the structural integrity of welded structures. For operating components, especially, nondestructive techniques are required. By now, authors have proposed a new residual stress evaluation method, the bead flush method, where residual stresses are calculated from eigenstrain distribution determined by surface removal of reinforcement. In this paper, a brief description of the bead flush method is given and its utility and problem to be overcome are discussed. And also stabilization method of solution set of eigenstrain in inverse analysis is proposed.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.3
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• pp.423-433
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• 2004

A large eddy simulation (LES) is performed for turbulent flow in a combustion device. The combustion device is simplified as a cylindrical chamber with sudden expansion. A flame holder is attached inside a cylindrical chamber in order to promote turbulent mixing and to accommodate flame stability. The turbulent sub-grid scale models are applied and validated. Emphasis is placed on the evaluation of turbulent model for the LES of complex geometry. The simulation code is constructed by using a general coordinate system based on the physical contravariant velocity components. The calculated Reynolds number is 5000 based on the bulk velocity and the diameter of inlet pipe. The predicted turbulent statistics are evaluated by comparing with the LDV measurement data. The Smagorinsky model coefficients are estimated and the utility of dynamic SGS models are confirmed in the LES of complex geometry.