• Journal of Power Electronics
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• v.16 no.3
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• pp.1025-1035
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• 2016

Luenberger observer (LO)-based sensorless multi-loop control of a converter requires an iterative trial-and-error design process, considering that many parameters should be determined, and loop gains are indirectly related to the closed-loop characteristics. Robust H∞ control adopts a compact sensorless controller. The algebraic Riccati equation (ARE)-based and linear matrix inequality (LMI)-based H∞ approaches need an exhaustive procedure, particularly for a low-order controller. Therefore, in this study, a novel robust H∞ synthesis approach is proposed to design a low-order sensorless controller for boost converters, which need not solve any ARE or LMI, and to parameterize the controller by an adjustable parameter behaving like a "knob" on the closed-loop characteristics. Simulation results show the straightforward closed-loop characteristics evaluation and better dynamic performance by the proposed H∞ approach, compared with the LO-based sensorless multi-loop control. Practical experiments on a digital processor confirmed the simulation results.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.410-411
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• 2007

To investigate the ZnO LED which are interested in the next generation of short wavelength LEDs and Lasers, the ZnO thin films were deposited by RF magnetron sputtering system. The p-type ZnO thin film, fabricated by means of the ampoule-tube method, was used to make the ZnO p-n junction, and its characteristics was analyzed. The ampoule-tube method was used to make the p-type ZnO based on the As diffusion, and the hall measurement was used to confirm that the p-type is formed. the current-voltage characteristics of the ZnO p-n junction were measured to confirm the rectification characteristics of a typical p-n junction and the low leakage voltage characteristics. Analysis of ZnO LED V-I curve will provide a very useful technology for producing the UV ZnO LED and ZnO-based devices.

• KIEAE Journal
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• v.17 no.5
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• pp.15-23
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• 2017

Purpose: The purpose of this study is to suggest a proper plan about the exterior space of elementary school in Korea through analyzing the various factors of the exterior spaces in foreign elementary school case. because the foreign cases have diversified eco-friendly certification standards on the elementary school unlike Korean cases. Method: First, we review the recent eco-friendly research trends of elementary schools and the external space characteristics of elementary schools that are currently being studied through related literary surveys, And we review the korean criteria factor for eco-friendly certification, we draw the types of exterior space thorough analysis framework, using the korean criteria factor. Second, the foreign cases of the elementary school were chosen, and then some planning data such as architecture scheme, design concepts and drawings will be collected. So the data were analysed and then the characteristics of physical setting and eco-friendly certification standards will be drawn. Third, We analyzed the characteristics and factor of physical and eco-friendly of exterior space through the drawn types. Result: The various physical settings are appeared physical environment. when we analyzed certification factors at korean eco-friendly standards, the suggestion and guide about the eco-friendly elements than the numerical goals were treated importantly in Korea.

• Korean Journal of Materials Research
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• v.18 no.2
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• pp.61-64
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• 2008

Electrical optical switching and structural transformation of $Ge_{15}Sb_{85}$, $Sb_{65}Se_{35}$ and N2.0 sccm doped $Sb_{83}Si_{17}$ were studied to investigate the phase change characteristics for PRAM application. Sb-based materials were deposited by a RF magnetron co-sputtering system and the phase change characteristics were analyzed using an X-ray diffractometer (XRD), a static tester and a four-point probe. Doping Ge, Se or Si atoms reinforced the amorphous stability of the Sb-based materials, which affected the switching characteristics. The crystallization temperature of the Sb-based materials increased as the concentration of the Ge, Se or Si increased. The minimum time of $Ge_{15}Sb_{85}$, $Sb_{65}Se_{35}$ and N2.0 sccm doped $Sb_{83}Si_{17}$ for crystallization was 120, 50 and 90 ns at 12 mW, respectively. $Sb_{65}Se_{35}$ was crystallized at $170^{\circ}C$. In addition, the difference in the sheet resistances between amorphous and crystalline states was higher than $10^4{\Omega}/{\gamma}$.

• The Journal of Fisheries Business Administration
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• v.50 no.1
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• pp.39-54
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• 2019

The purpose of this paper is to analyze the difference of seafood dining consumer behavior by demographic characteristics (age, gender). This research surveyed 251 people in Busan, Korea. t-test, one-way ANOVA, and MDS were used to identify the difference of consumer behavior by demographics. The result of the research revealed the difference between demographic characteristics and seafood dining consumption. 20's showed to accept the trendy dining culture represented by salmon, sushi and shrimp, and 30's also have similar tendency. 40's have higher spending tendency to seafood dining like tuna restaurants. 50's and 60's showed conservative consumption propensity represented by grilled fish, braised fish and raw fish restaurants. In gender analysis, male have higher frequency than female about grilled eel. In the future, the seafood dining market would be reorganized with the expansion of sushi, salmon and shrimp dishes, which can be classified as a new dining market. In this research, we suggested fisheries supply and production strategies according to age and gender.

• Journal of Multimedia Information System
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• v.8 no.2
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• pp.93-100
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• 2021

Under the time-varying temperature, the high-temperature radiation of forgings and the change of reflection characteristics of oxide skin on the surface of forgings lead to the difficulty of obtaining images to truly reflect the geometric characteristics of forgings. It is urgent to study the clear and reliable acquisition method of hot forging feature image under time-varying temperature to meet the requirements of visual measurement of hot geometric parameters of forgings. Based on this, this chapter first puts forward the quality evaluation method of forging feature image, which provides guarantee for the accurate evaluation of feature image quality. Furthermore, the factors that affect the image quality, such as the radiation characteristics of forgings and the photographic characteristics of cameras, are analyzed, and the imaging spectrum which can effectively suppress the radiation intensity of forgings is determined. Finally, aiming at the problem that the quality of image acquisition is difficult to guarantee due to the drastic change of radiation intensity of forgings under time-varying temperature, an image acquisition method based on minimum signal-to-noise ratio (SNR) based laser light intensity adaptation is proposed, which significantly improves the definition of feature light strips in forging images at high temperature, and finally realizes the clear acquisition of feature images of large-scale hot forging under time-varying temperature.

• International Journal of Advanced Culture Technology
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• v.12 no.1
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• pp.34-42
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• 2024

This study investigated the academic achievement of science and high school students according to the characteristics of R&E activities in mathematics and science. In addition, based on the survey results, the correlation between R&E activity characteristics and mathematics and science academic achievement was studied through correlation analysis and factor analysis between subjects. There was a difference in academic achievement in mathematics and science according to the characteristics of the R&E activity area, and the experience of R&E activity was found to be closely related to the academic achievement of related subjects. Depending on the area of R&E activity, mathematical and scientific academic achievement was found to be two factors: mathematical logic and natural understanding. Natural understanding factors significantly influenced students' academic achievement in mathematics, physics, and life sciences, and mathematical logic factors significantly influenced the academic achievement of students in chemistry and earth science subjects. In particular, mathematical logic ability was concentrated in excellent physics class students, and natural understanding ability was concentrated in excellent life science class students. Since the characteristics of the R & E activity area greatly influence the academic achievement of mathematics and science, it will significantly contribute to the selection and operation of the R & E activity area of science high school students.

• ETRI Journal
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• v.27 no.5
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• pp.563-568
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• 2005

A motion-control chip contains major functions that are necessary to control the position of each motor, such as generating velocity command profiles, reading motor positions, producing control signals, driving several types of servo amplifiers, and interfacing host processors. Existing motion-control chips can only generate velocity profiles of fixed characteristics, typically linear and s-shape smooth symmetric curves. But velocity profiles of these two characteristics are not optimal for all tasks in industrial robots and automation systems. Velocity profiles of other characteristics are preferred for some tasks. This paper proposes a motion-control chip to generate velocity profiles of desired acceleration and deceleration characteristics. The proposed motion-control chip is implemented with a field-programmable gate array by using the Very High-Speed Integrated Circuit Hardware Description Language and Handel-C. Experiments using velocity profiles of four different characteristics will be performed.

• Journal of Preventive Medicine and Public Health
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• v.42 no.4
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• pp.215-222
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• 2009

Objectives : Vigorous physical activity is a well-known method to promote people s health. This research aims to investigate whether perceived neighborhood characteristics affect vigorous physical activity among adult Seoul residents (aged 19 to 64). Methods : Utilizing the 2005 Seoul Citizens Health Indicators Survey data, this study estimates the probability of vigorous physical activity. Particular attention is given to the effects of three perceived neighborhood characteristics satisfaction with relationship to the neighborhood, satisfaction with park and recreational facilities, and satisfaction with public security). Logistic regression models are analyzed separately by gender for the parameter estimation. Results : Vigorous physical activity is positively associated with three perceived neighborhood characteristics for women, while neither significant nor substantive association is found for men. Conclusions : As vigorous physical activity among Seoul citizens is differentially affected by perceived neighborhood characteristics and by gender, a different approach will be needed to increase vigorous physical activity of men and women in Seoul.

• Tribology and Lubricants
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• v.18 no.5
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• pp.339-344
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• 2002

Whenever moving surfaces of machine driving elements interact in air and lubricating oil, oxidization film on the surfaces are generated. It is effect to prevent friction and wear on contact area. Since the electronic current progress the oxidization of metal, if the electronic flow be regulated, the thickness of oxidization film can be regulated and friction characteristics can be improved. But the electronic current can deteriorate friction characteristics, so various characteristics must be investigated on transforming of electronic current. Therefor, using the Norton equation in this study, short current were transformed between frictional materials using ball on disk type tester. It was studied on effect of electronic current for friction characteristics.