• The Mathematical Education
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• v.45 no.2 s.113
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• pp.217-230
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• 2006

The purpose of this study is to inquire the building process of Pedagogical Content Knowledge of prospective mathematics teachers about the function concepts. For this purpose, We performed the following steps; First, we performed the survey relaying to the prospective mathematics teachers' teaching experiences, capabilities of their error evaluation of the students, and viewpoints about the function concepts. Second, we performed the survey on the subject-matter knowledge about the function concepts and the key items of designing teaching plans about the function concepts. And then, we interviewed the participants to check the results of the surveys and to supplement the necessary contents. The collected data was relatively correlative and analyzed in the process. As a result, we found the followings; First, subject-matter knowledge of prospective mathematics teachers about the function concepts is different depending on the grades. Second, prospective mathematics teachers are building more extended function concepts through the major subjects. Third, the major subjects are important to build the Pedagogical Content Knowledge of function concepts. Fourth, teaching experience plays an important role in transforming subject-matter knowledge of function concepts to Pedagogical Content Knowledge of it. Fifth, building the Pedagogical Content Knowledge means transferring the teacher's viewpoint from himself/herself to the learner.

• Coupled systems mechanics
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• v.4 no.1
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• pp.67-98
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• 2015

Numerical prediction of dynamic behavior of fully coupled saturated porous media is of great importance in many engineering problems. Specifically, static and dynamic response of soils - porous media with pores filled with fluid, such as air, water, etc. - can only be modeled properly using fully coupled approaches. Modeling and simulation of static and dynamic behavior of soils require significant Verification and Validation (V&V) procedures in order to build credibility and increase confidence in numerical results. By definition, Verification is essentially a mathematics issue and it provides evidence that the model is solved correctly, while Validation, being a physics issue, provides evidence that the right model is solved. This paper focuses on Verification procedure for fully coupled modeling and simulation of porous media. Therefore, a complete Solution Verification suite has been developed consisting of analytical solutions for both static and dynamic problems of porous media, in time domain. Verification for fully coupled modeling and simulation of porous media has been performed through comparison of the numerical solutions with the analytical ones. Modeling and simulation is based on the so called, u-p-U formulation. Of particular interest are numerical dispersion effects which determine the level of numerical accuracy. These effects are investigated in detail, in an effort to suggest a compromise between numerical error and computational cost.

• Journal of Korea Society of Digital Industry and Information Management
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• v.15 no.4
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• pp.9-17
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• 2019

Sun power generation systems which use large capacity centralized inverters have loss of power generation due to cloud and building shadows, pollution, cell deterioration, etc. To minimize loss of power generation, decentralized solar power systems using multiple micro-inverters are being proposed as an alternative. A distributed solar power system consisting of a system-connected system uses power line communication to collect data from the micro-inverters. Power line communication has the advantage of using power lines without separate lines for data transmission, but in distributed solar power generation systems that use a large number of micro-inverters, the bit error rate is less reliable due to the phenomenon caused by limited transmission power, high load interference and noise, variable signal attenuation, and impedance characteristics. So we proposed wireless intelligent controller for micro-inverter that is used to build distributed solar power systems. and we design and implement that. Further, the proposed wireless intelligent controller for micro-inverter was used to establish a small-volume solar power plant to check its function and operation.

• Journal of Korean Society for Geospatial Information Science
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• v.8 no.2 s.16
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• pp.79-88
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• 2000

It is essential to build a high quality database in developing a UIS to enhance the administrative effectiveness of municipal governments. To secure such a high quality DB, a proper methodology of quality control should be established. It is imperative to have such a method fit UIS DB considering that the conventional method has mainly been focusing on the quality control of the digital layers itself. Therefore, this study have analyzed the city of Inchon's UIS DB to devise a proper method to categorize the types of errors and to identify major relevant items. Also, the magnitude and frequency of each error along with its major cause have been analyzed to propose a quality control procedure to minimize the errors

• Journal of the Korea Institute of Military Science and Technology
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• v.3 no.2
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• pp.166-178
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• 2000

As the 21st century signifies an information-oriented society, the computer integration takes place in all walks of human presence. Needs for computer and network-integrated automation present new challenges in military as well as commercial facility systems engineering. Since the first intelligent building appeared in USA in 1984, it gradually became an essential capability for the building industry requirement these days. Intelligent Building System(IBS) is evolving to be very complex because there are many subsystems such as telecommunication(TC), office automation(OA), building automation(BA), security, construction environments, etc. During the planing phase of IBS development, therefore, a disciplined systems engineering must be performed to analyze stake- holder's requirements to build an optimized system while minimizing trial-and-error expenses and risks. This paper presents a conceptual design of BAS applying systems engineering methods. The contribution of this study includes the development of IBS subsystem specification for building automation subsystem, which is a part of IBS, using the methodology of requirement analysis, functional analysis, synthesis, and verification. A computer-aided systems engineering s/w, RDD-100, was used to improve the system design efficiency and to promote the product design knowledge management for reuse in later design programs.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.11
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• pp.2040-2050
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• 2007

In this study, we present a novel method for estimating the information of MU(motor unit) which is the basic element of human muscle by using surface EMG. Some of the method developed in this field could only estimate the numbers of MU that is activated. However, in our study the MU-simulator based on the line source model was designed to estimate the MU information including the numbers of MU and muscle fiber, conduction velocity, MU diameter, fiber diameter, and end plate position. The SMUAP(single motor unit action potential) detector was designed and CMAP(compound muscle action potential) by electrical stimulus was recorded. With these data, the MU-simulator can estimate the MU information by varying muscle paramater settings through MSE(mean square error) method. Our results shows that the proposed method can be comparable with the method of anatomical studies. Moreover, our system can be utilized to build a tool for diagnosis and treatment assessment of neuromuscular patients.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.8
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• pp.378-383
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• 2005

We report the development of miniature fluorescence detection systems that employ miniature prism, mirrors and low coat CCD camera to detect the fluorescence emitted from 40 fluorescently-labeled protein patterns without scanner. This kind of miniature fluorescence detection system can be used in point of care. We introduce two systems, one uses prism+mirror block and the other uses prism and two mirrors. A large NA microscope eyepiece and low cost CCD camera are used. We fabricated protein chip containing multi-pattern BSA labeled with Cy5, using MEMS technology and modified the surface chemically to clean and to immobilize proteins. The measurements show that the combination of prism and mirrors can homogenize elliptical excitation light over the sample with higher optical efficiency, and increase the separation between excitation and fluorescence light at the CCD to give higher signal intensity and higher signal to noise ratio. The measurements also show that protein concentrations ranging from 10 ng/ml to 1000 ng/ml can be assayed with very small error. We believe that the proposed fluorescence detection system can be refined to build a commercially valuable hand-held or miniature detection device.

• Advances in Energy Research
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• v.6 no.2
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• pp.91-101
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• 2019

This paper proposes an efficient data-driven approach to build models for predicting energy consumption in buildings. Data used in this research is collected by installing humidity and temperature sensors at different locations in a building. In addition to this, weather data from nearby weather station is also included in the dataset to study the impact of weather conditions on energy consumption. One of the main emphasize of this research is to make feature selection independent of domain knowledge. Therefore, to extract useful features from data, two different approaches are tested: one is feature selection through principal component analysis and second is relative importance-based feature selection in original domain. The regression model used in this research is gradient boosting regression and its optimal parameters are chosen through a two staged coarse-fine search approach. In order to evaluate the performance of model, different performance evaluation metrics like r2-score and root mean squared error are used. Results have shown that best performance is achieved, when relative importance-based feature selection is used with gradient boosting regressor. Results of proposed technique has also outperformed the results of support vector machines and neural network-based approaches tested on the same dataset.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2375-2380
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• 2008

Controlling of thermal environment and flow in nanoimprint process chamber is important to ensure high precision levels of products. The purpose of this paper is to build optimal nanoimprint process environment. Because of this, Optimum PI control parameter for precise temperature control has been examined. Also porous medium of ventilation system is simulated for uniform flow in the equipment chamber. The porous medium consists of mesh structure, and is installed to place which flow the influx of the air flows. PID control parameter is based on the data obtained by experiment. And then heating and cooling method which simultaneously operated was used for decreasing an error. In conclude temperature in the equipment chamber was able to control precisely in the range of ${\pm}0.1^{\circ}C$ by the PID control parameter and Deadband.

• International Journal of Naval Architecture and Ocean Engineering
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• v.7 no.2
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• pp.426-434
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• 2015

In this paper we proposed a dada-aided Doppler estimation method for underwater acoustic communication. The training sequence is non-dedicate, hence it can be designed for Doppler estimation as well as channel equalization. We assume the channel has been equalized and consider only flat-fading channel. First, based on the training symbols the theoretical received sequence is composed. Next the least square principle is applied to build the objective function, which minimizes the error between the composed and the actual received signal. Then an iterative approach is applied to solve the least square problem. The proposed approach involves an outer loop and inner loop, which resolve the channel gain and Doppler coefficient, respectively. The theoretical performance bound, i.e. the Cramer-Rao Lower Bound (CRLB) of estimation is also derived. Computer simulations results show that the proposed algorithm achieves the CRLB in medium to high SNR cases.