• Journal of the Korean Ceramic Society
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• v.40 no.3
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• pp.286-292
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• 2003

In this study, new shock absorbing system was proposed using silica gel particles according to the nano-technology. For the design and real application of the proposed damper, an experimental investigations are carried out using colloidal damper, which is statically loaded. The porous matrix is composed from silica gel(labyrinth architecture), coated by organo-silicones substances, in order to achieve a hydrophobic surface. Water is considered as associated lyophobic liquid. Reversible colloidal damper static test rig and the measuring technique of the static hysteresis were described. Iufluence of the water volume and particle diameters upon the reversible colloidal damper hysteresis was investigated. Also, influence of the relaxation time on the hysteresis of the damper was investigated. As a result, the proposed new shock absorbing damper is proved as an effective one, which can be replaced for the conventional hydraulic damper.

• The KIPS Transactions:PartB
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• v.10B no.3
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• pp.311-320
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• 2003

The Optimal filter yielding optimal texture feature separation is a most effective technique for extracting the texture objects from multiple textures images. But, most optimal filter design approaches are restricted to the issue of supervised problems. No full-unsupervised method is based on the recognition of texture objects in image. We propose a novel approach that uses unsupervised learning schemes for efficient texture image analysis, and the band-pass feature of Gabor-filter is used for the optimal filter design. In our approach, the self-organizing neural network for multiple texture image identification is based on block-based clustering. The optimal frequency of Gabor-filter is turned to the optimal frequency of the distinct texture in frequency domain by analyzing the spatial frequency. In order to show the performance of the designed filters, after we have attempted to build a various texture images. The texture objects extraction is achieved by using the designed Gabor-filter. Our experimental results show that the performance of the system is very successful.

• Journal of Power Electronics
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• v.14 no.3
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• pp.444-457
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• 2014

This paper presents the design and realization of a digital PV simulator with a Push-Pull Forward (PPF) circuit based on the principle of modular hardware and configurable software. A PPF circuit is chosen as the main circuit to restrain the magnetic biasing of the core for a DC-DC converter and to reduce the spike of the turn-off voltage across every switch. Control and I/O interface based on a personal computer (PC) and multifunction data acquisition card, can conveniently achieve the data acquisition and configuration of the control algorithm and interface due to the abundant software resources of computers. In addition, the control program developed in Matlab/Simulink can conveniently construct and adjust both the models and parameters. It can also run in real-time under the external mode of Simulink by loading the modules of the Real-Time Windows Target. The mathematic models of the Push-Pull Forward circuit and the digital PV simulator are established in this paper by the state-space averaging method. The pole-zero cancellation technique is employed and then its controller parameters are systematically designed based on the performance analysis of the root loci of the closed current loop with $k_i$ and $R_L$ as variables. A fuzzy PI controller based on the Takagi-Sugeno fuzzy model is applied to regulate the controller parameters self-adaptively according to the change of $R_L$ and the operating point of the PV simulator to match the controller parameters with $R_L$. The stationary and dynamic performances of the PV simulator are tested by experiments, and the experimental results show that the PV simulator has the merits of a wide effective working range, high steady-state accuracy and good dynamic performances.

• Korean Institute of Interior Design Journal
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• v.25 no.3
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• pp.51-59
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• 2016

The technique for Eye-tracking is to trace the movements of pupils so that the eye's exploration response to be digitized. The procedure of Observation Experiment shows a mutual environmental characteristics between men and measuring devices. In order to improve the reliability and to secure the objectivity of the data acquired from eye-tracking, it is very important to analyze the procedures for the experiment to be prepared and the test data to be saved. Based on this viewpoint, the convergent exploration activities at the observation experiment with the objects of sport images were examined to find out what influences the context effect given by experimental environments have on this experiment. In addition, the starting time of attention affecting the reliability of observation data has been estimated. When the observation time is to be subdivided by the unit of second. The attention disperses for the individual characteristics to be appreciated. However, in case of analysis by the overall average, there was the problem that the section of attention dispersed to make it difficult to analyze the subjects' observation features. The study results made it possible to understand the physiological characteristics which were near unconsciousness, when there was an intensive attention for the first 3 seconds and the observation data were shown to be in ordinary range after 4 seconds. The analysis of observation with the focus of the intensive attention enabled the analysis with the first 3 seconds excepted so that it might approach the ordinary range of observation data. The distribution of attention for the first 3 seconds showed the intensive attention, which was on the center. The emergence of intensive attention and the overlapping of the centers can be considered as a context effect due to the correction for the preparing process of experiment. Accordingly, it is thought to be helpful to the security of objectivity and the construction of reliability of eye-tracking data to analyze the observation features shown after the deletion of the data for the first 3 seconds.

• Korean Institute of Interior Design Journal
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• v.18 no.6
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• pp.44-51
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• 2009

Various and complex cultural phenomena have led to many changes in the space. The concept of unconsciousness, among others, and experimental expression technique and the concepts from surrealism that rather attaches great importance to contingency than intentional attempt have been employed in the space. The abstract expression as expressional characteristics of surrealism makes the space ambiguous through the concept of automatism using the approach of indeterminism and double image expression, and represents the space providing diversity through the dualism. In contrast, objective expression, which was based on depaysement, generates the tension and expresses the dramatic situation in such a way and manner which are intentional, distorted transformed, together with heterogenous meanings aligned through the reversal appeared in the techniques of collage and paranoiac-critical method. However if such space accommodating the expressional characteristics of surrealism is approached as superficial concept in analyzing the human's inner consciousness and imaginary society, expression of the ultimate concept contained in the expressional characteristics of surrealism can hardly be achieved. Hence, the spatial analysis from the semiotic approach, instead of unilateral method aimed to convey the meaning only, which creates the signification, was adopted. The study, as effective approach to the space accommodating the expressional characteristics of surrealism, was intended systematically evaluate the concreteness of understanding and generation of meaning through the semiotic method. Greimas' semiotic square analysis to the space plays the important role in generating the spatial meaning, as well as is needed for objective analysis of the importance of various characteristics and methodology which the space contains through the expressional characteristics of surrealism.

• The Transactions of the Korean Institute of Power Electronics
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• v.19 no.4
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• pp.364-375
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• 2014

Parametric array transducers are used for long-range and highly directional communication in an underwater environments. The power amplifiers for parametric array transducers should have sufficient linear output characteristic and high efficiency to avoid communication errors, system heating, and fuel problems. But the conventional power amplifier with fixed source voltage is very low efficient due to large power loss by the big difference between the fixed source voltage and the amplifier output voltage. Thus to solve the problems this paper proposes the high efficiency power amplifier for parametric array transducers. The proposed power amplifier ensures high linearity of output characteristic by utilizing the push-pull class B type amplifier and furthermore gets high efficiency by applying the envelope tracking technique that variable source voltage tracks the envelope of the amplified signal. Also the paper suggests the detailed circuit topology and design guideline of class B push-pull type amplifier and variable output voltage AC/DC converter. Its characteristics are verified by the detailed simulation and experimental results.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.8 s.113
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• pp.848-856
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• 2006

This paper describes the aeroelastic stability test of the small-scaled 'Next-generation Blade(NRSB)' with NRSH (next-generation hub system) and HCTH hingeless hub system in hover and forward flight conditions. Excitation tests of rotor system installed in GSRTS (general small-scale rotor test system) at KARI (Korea Aerospace Research Institute) were carried out to get lead-lag damping ratio of blades with flexures as hub flexure. MBA(moving block analysis) technique was used for the estimation of lead-lag damping ratio. First, NRSB-1F blades with HCTH hub system, then NRSB- 1F with NRSH hub system were tested. Second, NRSB-2F blades with NRSH hub system were tested. Tests were done on the ground and in the wind tunnel according to the test conditions of hover and forward flight, respectively. Non-rotating natural frequencies, non-rotating damping ratios and rotating natural frequencies were showed similar level for each cases. Estimated damping ratios of NRSB-1F, NRSB-2F with HCTH and NRSH were above 0.5%, and damping ratio increased by collective pitch angle increasement. Furthermore damping ratios of NRSB-2F were higher than damping ratios of NRSB-1F in high Pitch angle. It was confirmed that the blade design for noise reduction would give observable improvement in aeroelastic stability compared to paddle blade and NRSB-1F design.

• International Journal of Advanced Culture Technology
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• v.9 no.3
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• pp.188-201
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• 2021

The purpose of this study is to analyze the effects of online home learning in connection with extracurricular activities for lifelong education for the disabled in university on the cooking aids skills of cafeterias for the job search persons with developmental disabilities. Three people with job search developmental disabilities who have been in a state of unemployment for three years after graduating from a special high school course participated in the experiment. In order to verify the meaningful functional relationship between independent variables and dependent variables, multiple probe design across subjects, one of the main techniques of a single object study, was used. The experimental conditions according to the research design consisted of the steps of baseline, intervention, maintenance, and generalization. The dependent variable of this study is the restaurant cooking aid skills in the cafeteria, and three subskills such as side dish arrangement, sink arrangement, and dish washing were combined by task analysis. And the independent variable of this study was composed of procedures and methods to teach the environment, tools and materials related to the performance of dependent variables to the developmental disabled people at home by using real-time image technique through zoom service, and the contents of the performance by stages of task analysis. In addition, independent variables were applied to the subjects in the course of the extracurricular activities with the theme and contents of lifelong education for the disabled at university. Students who completed the above extracurricular activities practiced the intervention scene of the researcher through the screen sharing of zoom service. As a result, the subjects with developmental disabilities effectively acquired and maintained the positive response performance of dependent variables through independent variables. The subjects also showed high positive responses to generalization tests conducted in kitchens in cafeterias located elsewhere in the same university.

• Journal of Navigation and Port Research
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• v.45 no.3
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• pp.165-172
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• 2021

Breaking wave is one of the important design factors in the design of coastal and port structures as they are directly related to various physical phenomena occurring on the coast, such as onshore currents, sediment transport, shock wave pressure, and energy dissipation. Due to the inherent complexity of the breaking wave, many empirical formulas have been proposed to predict breaker indices such as wave breaking height and breaking depth using hydraulic models. However, the existing empirical equations for breaker indices mainly were proposed via statistical analysis of experimental data under the assumption of a specific equation. In this study, a new Munk-type empirical equation was proposed to predict the height of breaking waves based on a representative linear supervised machine learning technique with high predictive performance in various research fields related to regression or classification challenges. Although the newly proposed breaker height formula was a simple polynomial equation, its predictive performance was comparable to that of the currently available empirical formula.

• Journal of the Korea Society for Simulation
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• v.19 no.2
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• pp.1-8
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• 2010

With recent development of computer hardware and 3D graphic technique, a lot of people have concern for something to express as the 3D graphic that look the real environment. Because the request of users have increased, the 3D simulation is developed and popularized in the many field. In this paper, we design and implement the simulation system that humans evacuate a building fires using the 3D graphic techniques. In this paper, we use the A* algorithm to humans have the artificial intelligence at evacuating a building fires, calculate the evacuation speed of each human considering temperature damage and smoke damage. In this paper, we applied the real building to demonstrate the effect of proposed evacuation simulation. Experimental results showed that the evacuation speed is affected by the temperature condition and the smoke density.