• Journal of the Korea Society of Computer and Information
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• v.23 no.2
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• pp.9-16
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• 2018

Recently, as various IP set-top boxes based on Android OS have been widely used in general households and public facilities, complaints about services and set-top boxes have continued to increase as much as other smart devices. In order to reduce this problem, the manufacturer performs the testing work before the product is commercialized. However, the testing can reduce potential defects in the product, but it can not prove that the product is free of defects. Therefore, the quality of the product can vary depending on how effective testing techniques are introduced. In this paper, we propose a new exploratory testing method that minimizes test case creation time and makes it easier to plan and execute test while simultaneously learning how to run the product under test. Using the first proposed method, the test time is reduced by about 16.7 hours and the defect detection rate is 25.4% higher than the formal specification-based testing method. Informally, the test time was shortened by about 4.7 hours and the defect detection rate was 13% higher than the informal experience-based testing method.

• Korean journal of communication and information
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• v.38
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• pp.245-275
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• 2007

This study analyzes interactivity between formal policy and informal trade practices at outside production market of broadcasting production environment in Korea. For this, this study raises three topics. First, the trait of historical context of policy making at outside broadcasting production policy: Second, the trait and meaning of path dependency behavior in the process of trade practices between over-the-air TV Organization and independent production companies : Three, the meaning of interactivity between formal policy and informal trade practices at outside broadcasting production market. Major findings of this study are : the trait of policy making was concentrated on the quantitative rates of the outside production program. And, the trait of trade practices was unfair rivalry in accordance with the custom of insider dealing. The chief cause of the conflict structure of outside broadcasting production market is lacked in policy complement at the qualitative dimension.

• Communications of Mathematical Education
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• v.22 no.4
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• pp.471-487
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• 2008

Inventive mathematical thinking, original mathematical problem solving ability, mathematical invention and so on are core concepts, which must be emphasized in all branches of mathematical education. In particular, Polya(1981) insisted that inventive thinking must be emphasized in a suitable level of university mathematical courses. In this paper, the author considered two cases of inventive problem solving ability shown by his many students via real analysis courses. The first case is about the proof of the problem "what is the derived set of the integers Z?" Nearly all books on mathematical analysis sent the question without the proof but some books said that the answer is "empty". Only one book written by Noh, Y. S.(2006) showed the proof by using the definition of accumulation points. But the proof process has some mistakes. But our student Kang, D. S. showed the perfect proof by using The Completeness Axiom, which is very useful in mathematical analysis. The second case is to show the infinite countability of NxN, which is shown by informal proof in many mathematical analysis books with formal proofs. Some students who argued the informal proof as an unreasonable proof were asked to join with us in finding the one-to-one correspondences between NxN and N. Many students worked hard and find two singled-valued mappings and one set-valued mapping covering eight diagrams in the paper. The problems are not easy and the proofs are a little complicated. All the proofs shown in this paper are original and right, so the proofs are deserving of inventive mathematical thoughts, original mathematical problem solving abilities and mathematical inventions. From the inventive proofs of his students, the author confirmed that any students can develope their mathematical abilities by their professors' encouragements.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.3A
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• pp.196-204
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• 2002

The Sinusoidal Transform Coding(STC) is a vocoding scheme based on a sinusoidal model of a speech signal. The low bit-rate speech coding based on sinusoidal model is a method that models and synthesizes speech with fundamental frequency and its harmonic elements, spectral envelope and phase in the frequency region. In this paper, we propose the 2.4kbps low-rate speech coding algorithm using the sinusoidal model of a speech signal. In the proposed coder, the pitch frequency is estimated by choosing the frequency that makes least mean squared error between synthetic speech with all spectrum peaks and speech synthesized with chosen frequency and its harmonics. The spectral envelope is estimated using SEEVOC(Spectral Envelope Estimation VOCoder) algorithm and the discrete all-pole model. The phase information is obtained using the time of pitch pulse occurrence, i.e., the onset time, as well as the phase of the vocal tract system. Experimental results show that the synthetic speech preserves both the formant and phase information of the original speech very well. The performance of the coder has been evaluated in terms of the MOS test based on informal listening tests, and it achieved over the MOS score of 3.1.

• Korean Journal of Computational Design and Engineering
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• v.20 no.3
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• pp.254-262
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• 2015

This study proposes an approach to Product Data Management (PDM) education for collaborative product data management, which can support collaborative product development process. This approach introduces social media and a PDM system into a framework for PDM education supported by consistent product development process and product data model. It has been applied to two PDM classes and the result shows that the social media in PDM education can support not only experiences of the collaborative product data management but also interactive and informal communications among instructors and participants using integrated social media with product data during courses.

• Architectural research
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• v.16 no.4
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• pp.167-174
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• 2014

Smart Work is a way of working independent of time and space restrictions with the help of ICT. For past years, Korea has been promoting Smart Work to boost ICT industry, to overcome low birth rate and population ageing, and to implement Smart Korea. Three elements of Smart Work include people, technology and space. A lot of research has been performed on people and technology for Smart Work. But it is hard to find research on space. In this paper, some representative smart work centers(SWCs) in Korea were selected and analyzed from the perspective of spatial design including general characteristics, personal spaces, group spaces, and support spaces. From this research, it is observed that current SWCs in Korea are good in providing personal work spaces and simple group meeting rooms as well as ICT environments. However, they lack of openness to the public and group spaces to encourage informal communications. It is also observed that personal space plans need to be multi-functional, and that novel supporting spaces are required to improve quality of life and creativity of workers.

• The Journal of the Acoustical Society of Korea
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• v.27 no.1E
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• pp.11-16
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• 2008

In this paper, a pitch cycle waveform (PCW) is extracted, quantized, and interpolated in a time domain to synthesize high-quality speech at low bit rates. The pre-alignment technique is proposed for the accurate and efficient PCW extraction, which predicts the current PCW position from the previous PCW position assuming that pitch periods evolve slowly. Since the pitch periods are different frame by frame, the original PCW is converted into the fixed-dimension PCW using the dimension-conversion method, and subsequently quantized by code-excited linear predictive (CELP) coding. The excitation signal for the linear predictive coding (LPC) synthesis filter is generated using the time-domain interpolation and interlink of the quantized PCW's. The coder operates at 4.2 kbit/s and 3.2 kbit/s depending on the pitch period. Informal listening test demonstrates the effectiveness of the proposed coding scheme.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1999.11a
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• pp.312-321
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• 1999

Advanced system and softwares are required for informal ion communications ions protocol in Information sharing. electronlc commerce and intranet applications with the increase of Internet usage. Therefore. the development methodology of telecommunications protocol to meet user's requirement and increase reliability becomes more important. This study aims to develop the verification model and tool for ATM protpcol using SDL formal description technique and will becomes basic technique for the implementation of integrated protocol development tool.

• Journal of Korean Elementary Science Education
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• v.41 no.1
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• pp.118-133
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• 2022

In this study, we analyze the strengths and limitations of student convergence education and teacher-training programs offered by a science education institute in the capital region and provide suggestions for organizing and running similar programs in other science education institutes and schools. Reviews of relevant literature and interviews with internal and external expert groups were conducted, and an analytic framework was developed. Based on the framework, we collected data using focus group interviews and email communications with experts. The data were analyzed using both qualitative and quantitative methods within two areas, namely, convergence education programs for students and teacher-training programs. The data analysis results revealed the status of student convergence education and teacher-training programs in the institute. Furthermore, we also provided suggestions for improving programs in other informal science education institutes and schools through the interaction between the two areas in the framework and educational and social needs.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.8C
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• pp.1142-1148
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• 2004

A binaural filtering method using HRTF DB is generally used to make the headphone-based 3D sound. But it can make some confusion between front and back directions or between up and down directions due to the non-individual HRTF depending on each listener. To reduce the confusion of sound image localization, we propose a new method to boost the spectral cue by modifying HRTF spectra with spectrum difference between front and back directions. Informal listening tests show that the proposed method improves the front-back sound localization characteristics much better than the conventional methods