• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.183-186
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• 2006

Reduction of optical losses in crystalline silicon solar cells by surface modification is one of the most important issues of silicon photovoltaics. Porous Si layers on the front surface of textured Si substrates have been investigated with the aim of improving the optical losses of the solar cells, because an anti-reflection coating and a surface passivation can be obtained simultaneously in one process. We have demonstrated the feasibility of a very efficient porous Si AR layer, prepared by a simple, cost effective, electrochemical etching method. Silicon p-type CZ (100) oriented wafers were textured by anisotropic etching in sodium carbonate solution. Then, the porous Si layer were formed by electrochemical etching in HF solutions. After that, the properties of porous Si in terms of morphology, structure and reflectance are summarized. The surface morphology of porous Si layers were investigated using SEM. The formation of a porous Si layer about $0.1{\mu}m$ thick on the textured silicon wafer result in an effective reflectance coefficient $R_{eff}$ lower than 5% in the wavelength region from 400 to 1000nm. Such a surface modification allows improving the Si solar cell characteristics.

• Journal of Information Technology Services
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• v.14 no.2
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• pp.129-142
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• 2015

The purpose of this study is to suggest an effective regression testing method in order to minimize the scope of test resulting from the modification of software and to prevent mismatch of test case and test objects. As a way to improve the efficiency of regression testing which uses a change-centric testing technique, the method flow is analyzed and grasped through a static analysis based on source code in order to identify modified parts. After the order of priority is set according to the results of user action log-based dynamic analysis on identified regression testing objects, test effect can be raised by adjusting the order of priority using code complexity. Quality assurance coverage can be checked using the user action log suggested in this study, and the progress of test and whether or not each function has been verified can be checked, too. In addition, by minimizing test parts and adjusting the order of test, costs and time can be saved, making it possible to conduct regression testing effectively.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.10a
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• pp.43-46
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• 2004

Multi-walled carbon nanotubes (MWNTs) produced by chemical vapor deposition were treated with acidic solution for purification and oxidization of CNTs. The surface modification of the oxidized CNTs was achieved by amine treatment and oxygen plasma treatment. The functionalized CNTs were embedded in the epoxy resin by sonication method and the resulting composite was investigated by FESEM. Rheological and mechanical properties of nanocomposites were measured by AR2000 and Instron. The rheological properties and dispersion of modified CNTs/epoxy composites were improved as CNTs were modified, because the modification of CNTs led to a improvement interaction between the CNTs and the epoxy resin. In addition to this, mechanical properties are also improved because of the effective stress transfer between the CNTs and the polymer.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.5
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• pp.939-951
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• 1994

In adaptive equalizers based on least mean squares (LMS) algorithms, the convergence rate is determined by the convariance matrix of an input signal. When the eigenvalue spread of the convariance matrix is close to unity, the convergence rate is quite fast. In this paper, for fast convergence of LMS-based adaptive equalizers we propose a modified reference signal pertinent to the statistical channel. From the theoretical analysis and computer simulation, it is shown that the proposed modification method is quite effective for fast convergence of LMS-based adaptive equalizers.

• MALSORI
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• no.60
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• pp.181-190
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• 2006

This paper describes a speech enhancement scheme that leads to significant improvements in recognition performance when used in the ASR front-end. The proposed approach is based on adaptive comb filtering and an MMSE-related parameter estimator. While adaptive comb filtering reduces noise components remarkably, it is rarely effective in reducing non-stationary noises. Furthermore, due to the uniformly distributed frequency response of the comb-filter, it can cause serious distortion to clean speech signals. This paper proposes an improved comb-filter that adjusts its spectral magnitude to the original speech, based on the speech absence probability and the gain modification function. In addition, we introduce the modified comb filtering-based speech enhancement scheme for ASR in mobile environments. Evaluation experiments carried out using the Aurora 2 database demonstrate that the proposed method outperforms conventional adaptive comb filtering techniques in both clean and noisy environments.

• Journal of Korean Academy of Nursing
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• v.42 no.7
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• pp.1062-1069
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• 2012

Purpose: Meager research has been carried out to determine the effectiveness of the token economy among patients behaving violently in mental hospitals. The purpose of this study was to examine the effectiveness of the Short-Term Token Economy (STTE) on violent behavior among chronic psychiatric in-patients. Methods: A nonequivalent control group design method was utilized. Participants in an experimental group (n=22) and control group (n=22) took part in this study from January to April, 2008. Observation on aggressive behavior among male in-patients in one hospital as a baseline was made during the week before the behavior modification program and measurement of aggressive behavior was done using the Overt Aggression Scale (OAS), which includes verbal attacks, property damage and physical attacks. Results: The aggressive behavior scores of the experimental group decreased, those of the control group, scores showed an increase after the eight-week behavior modification program utilizing STTE. Conclusion: The results of the study indicate that STTE is effective in reducing the incidence of aggressive behavior among male in-patients in psychiatric hospitals. The outcome of this study should be helpful in reducing the use of coercive measures or psychoactive medication in controlling the violent behavior among in-patients in hospitals.

• Applied Science and Convergence Technology
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• v.26 no.6
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• pp.164-173
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• 2017

Across the most industry, the demand for nanoparticles is increasing. Therefore, many studies have been carried out to synthesize nanoparticles using various methods. The aim of this paper is to introduce an industry-applicable as well as financially and environmentally effective solution plasma process. The solution plasma process involves fewer chemicals than the traditional kit, and can be used to replace many of the chemical agents employed in previous synthesis of nanoparticles into plasma. In this study, this process is compared to the wet-reaction process that has thus far been widely used in the most industry. Furthermore, the solution plasma process has been classified into four different types (in-solution, out of solution, direct type, and remote type), according to its plasma occurrence position and plasma types. Thus, the source of radicals, nanoparticle synthesis, and modification methods are explained for each design. Lastly, unlike nanoparticles with hydrophilic functional groups that are made inside the solution, a nanoparticle synthesis and modification method to create a hydrophobic functional group is also proposed.

• International Journal of Computer Science & Network Security
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• v.22 no.3
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• pp.129-134
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• 2022

The primary goal of any classroom is effective teaching and student learning, with an emphasis on changing negative students' behaviors into positive ones. This change can occur when students' behavior is always at the forefront of teachers' educational goals. The current study aimed to reveal the experiences of special education teachers in dealing with the behavioral problems that students with disabilities show by identifying behavioral problems among students with disabilities and investigating the efficacy of the application of behavior modification plans and strategies designed to address the behavioral problems presented by students with disabilities. The researcher used a qualitative phenomenological approach, and the study tool consisted of semi-structured interviews that consisted of (13) questions directed to (10) special education male and female teachers who work in special education centres and institutes. The data were analyzed using the thematic analysis method. The findings of the study showed that the most undesirable behaviors prevalent among students with disabilities in the classroom were aggression, bullying and ADHD. The actions taken by teachers in confronting these behaviors were not systematic and were carried out randomly, as no behavior modification plans were applied. The most important strategies used by teachers in facing behavioral problems were applied behavioral analysis (ABA) strategies such as reinforcement, punishment and ignoring. The results have many important implications for future practice, including the need to conduct practical training courses for special education teachers to implement behavior modification plans and develop methods of measuring inappropriate behavior.

• Computational Structural Engineering
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• v.8 no.4
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• pp.87-97
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• 1995

For the same configuration of two-dimensional finite element models, 6-node element exhibits stiffer bending stiffness than 8-node element. This is true in the relation between 16-node element and 20-node element for three-dimensional model. This stiffening phenomenon comes from the elimination of several mid nodes from full-node elements. Therefore, this may be called 'relative stiffness stiffening phenomenon'. It seems that there are a couple of ways to correct the stiffening effect, however, we could find only one effective method-the method of modification of Gauss sampling points-which passes the patch test and does not alter other kinds of stiffness, such as extensional stiffness. The quantity of modification is a function of Poisson's ratios of the constituent materials. We could obtain two modification equations, one for plane stress case and the other for plane strain case. This method can be extended to 3-dimensional solid elements. Except the exact plane strain cases, most 3-dimensional plates could be modeled successfully with 16-node element modified by the equation for the plane stress case. The effectiveness of the modification method is checked by applying it to several examples with excellent improvements. In numerical examples, beams with various boundary conditions are subjected to static and time-dependent loads. Free and forced motion analyses of beams and plates are also tested. The beam and plate may be composed of isotropic multilayers as well as a single layer.

• Journal of the Korean Society of Safety
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• v.12 no.3
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• pp.120-131
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• 1997

This paper presents an approximate reanalysis methods of structures based on substructuring for an effective optimization of large-scale structural systems. In most optimal design procedures the analysis of the structure must be repeated many times. In particular, one of the main obstacles in the optimization of structural systems are involved high computational cost and expended long time in the optimization of large-scale structures. The purpose of this paper is to evaluate efficiently the structural behavior of new designs using information from previous ones, without solving basic equations for successive modification in the optimal design. The proposed reanalysis procedure is combined Taylor series expansions which is a local approximation and reduced basis method which is a global approximation based on substructuring. This technique is to choose each of the terms of Taylor series expansions as the basis vector of reduced basis method in substructuring system which is one of the most effective analysis of large -scale structures. Several numerical examples illustrate the effectiveness of the solution process.