• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.2
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• pp.343-348
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• 2001

In this paper we propose a noise reduction algorithm which based on cellular automata with the local median rule. It is supposed that there is no information about the features of the image that must be improved. The proposed method behavior is to locally increase or decrease the gray level differences of the image without loss of the main characteristics of the image. The dynamical behavior of these automata is completely determined by Lyapunov operators for sequential and parallel update. We have found that the automata present very fast convergence to fixed points, stability in front of random noisy images. Based on the experimental results we discuss the advantage and efficiency.

• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.85-88
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• 2001

In this paper we consider a problem of blind co-channel signal separation, the goal of which is to estimate multiple co-channel digitally modulated signals using an antenna array. We employ the joint maximum likelihood estimation and present a sequential algorithm, which is referred to as sequential joint maximum likelihood (SJML) algorithm. It separates multiple co-channel signal on-line and converges fast in overdetermined noisy communication environment. And the computational complexity of SJML for M-QAM (M=8, 16, 64,...) signals is less expensive compared to the SLSP. Useful behavior of this algorithm are confirmed by simulations.

• ETRI Journal
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• v.32 no.5
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• pp.774-783
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• 2010

Many chaos-based encryption methods have been presented and discussed in the last two decades, but very few of them are suitable to secure transmission on noisy channels or respect the standard of the National Institute of Standards and Technology (NIST). This paper tackles the problem and presents a novel chaos-based cryptosystem for secure transmitted images. The proposed cryptosystem overcomes the drawbacks of existing chaotic algorithms such as the Socek, Xiang, Yang, and Wong methods. It takes advantage of the increasingly complex behavior of perturbed chaotic signals. The perturbing orbit technique improves the dynamic statistical properties of generated chaotic sequences, permits the proposed algorithm reaching higher performance, and avoids the problem of error propagation. Finally, many standard tools, such as NIST tests, are used to quantify the security level of the proposed cryptosystem, and experimental results prove that the suggested cryptosystem has a high security level, lower correlation coefficients, and improved entropy.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.259-263
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• 1996

In diagnosing of mechanical machinery, it is often improtant to get information about the movement inside the machine casing. If the values of internal tities may be derived from the measurement using sensors installed on the external casing, it would be much better in many senses. This paper discusses extracting internal gear movements byfrequencydemodulation from gear meshing force signatures which can be recovered from the vibrations though inverse filter. There are several way in demodulating signals. In this paper, especially, Hibert Transform, Wigner-Ville distribution, and Teager energy operator are examined and compared. Effects of noise on the frequency demodulation methods and the behavior of bandpass filtered noisy signal are discussed using simulated time-varying frequency signals.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.24 no.1
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• pp.7-14
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• 2015

The machine tools builders are trying to improve the efficiency and performance of the machine tools. The electro-mechanical driven broaching machine has many advantages such as lower noisy operating, higher energy efficiency, and smaller space of installation. This paper presents the structural and mechanical development of an electro-mechanical driven broaching machine that is replaced for traditional hydraulic one. The servo motor, ball screw and roller linear guide are used instead of hydraulic cylinder and translation frictional sliding guides. The simulation method based on FEM was applied to analyze the stress, deformation of the machine for static analysis. The dynamic analysis was carried out for verifying and assessing the mechanical behavior of the developed broaching machine. This work helps broaching machine developer make a better product at the early design stage with lower cost and development time.

• Proceedings of the Korean Information Science Society Conference
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• 2006.06b
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• pp.148-150
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• 2006

최근 모바일 디바이스의 기능이 다양해지면서 현대인에게 없어서는 안 될 필수품이 되었다. 모바일 디바이스의 사용영역이 널어지면서 늘어나는 개인 정보의 활용에 대한 관심이 집중되고 있다. 본 논문에서는 모바일 디바이스에서 사용자의 행동 패턴 분석 및 요약을 위한 지능형 에이전트를 제안한다 사용자의 다양한 행동 및 상태 패턴 분석을 위해 협력적 모듈 베이지안 네트워크를 사용한다. 협력적 모들 베이지안 네트워크는 비슷한 유형의 패턴끼리 모듈로 설계해 상호 협력적으로 작동하여 사용자의 특이성을 추론한다. 사용자에 기억에 남을 만한 특이성를 선택하기 위해 Noisy-OR gate를 적응하여 계산한 특이성간의 연결 강도와 특이성의 우선순위를 바탕으로 사용자의 하루 동안의 행동을 요약하여 구성한다. 추론을 위한 프로토타입을 작성하고 시나리오를 바탕으로 제안한 방법의 유용성을 보인다.

• Economic and Environmental Geology
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• v.30 no.5
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• pp.451-458
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• 1997

The horizontal magnetic dipole as well as electrical dipole was adopted as a source to compute one-dimensional electromagnetic field behavior in controlled source magnetotellurics. he Cagniard impedances due to horizontal magnetic dipole source, especially phases, showed better frequency characteristics than those due to electric one. The magnetic dipole is inferior to the electric dipole in the point of relatively weak transmitting power at low frequency. But considering high resistivity charateristics of Korean geology, the magnetic dipole source is recommended for the survey up to depth of 500 m. A vector CSMT was introduced to get more reliable data in the area of two- or three-dimensional structures. A software and interpretation technique using polarization ellipses were developed. The technique was tested by synthetic data, which provided theoretical basis of the methodology. Although CSMT has inevitable limitation of investigation depth due to practically possible source-receiver separation, we proposed to use the technique developed in this paper where MT is not available, for example, in extremely noisy area or for shallow target.

• Phonetics and Speech Sciences
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• v.5 no.4
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• pp.53-61
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• 2013

Voice disorders are most common in female teachers due to work-related vocal demands; however, only a few studies tried to evaluate individual risk factors with work-related risk factors to diagnose voice disorders. This study evaluated sixty-seven female elementary teachers (36 with voice disorders and 31 without voice disorders) to compare their vocal misuse, overuse, and vocal hygiene behaviors. Total Voice Handicap Index scores and VHI subscale (P, E, F) scores were not significantly different between two groups (p>0.05) and there was no relationship between VHI and acoustic measures (p>0.05). Loud talking, talking in noisy situations, and excessive speaking were significantly more frequent in female teachers with voice disorders (p<0.05) and thereby these overuse and misuse behavioral patterns were identified as risk factors to develop voice disorders in female teachers. Also, hydration was the most common behavior for vocal hygiene when experiencing vocal fatigue; however, hydration with hot green tea or coffee and throat clearing were often misused for vocal hygiene. This study found that female teachers from both groups presented higher voice handicap regardless of voice disorders. This study suggests a multidimensional voice assessment protocol is required to reflect voice problems in teachers and a vocal education program may be important to improve vocal hygiene knowledge and behavioral changes in female teachers.

• Journal of KIISE:Databases
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• v.41 no.4
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• pp.217-225
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• 2014

Analysis of social media such as Twitter can yield interesting perspectives to understanding human behavior, detecting hot issues, identifying influential people, or discovering a group and community. However, it is difficult to gather the data relevant to specific topics due to the main characteristics of social media data; data is large, noisy, and dynamic. This paper proposes a new algorithm that dynamically selects the seed nodes to efficiently collect tweets relevant to topics. The algorithm utilizes attributes of users to evaluate the user influence, and dynamically selects the seed nodes during the collection process. We evaluate the proposed algorithm with real tweet data, and get satisfactory performance results.

• Journal of the Korean Institute of Landscape Architecture
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• v.18 no.3 s.39
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• pp.71-84
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• 1990

This study was executed to investigate matters connected with planting of Gapho Citizen's Woods(Park), and to offer the data about countermeasure. The study was executed in 1988 and 1989. The contents of the study were the condition of plants, the environmental factors, the states of tree planting and the user's behavior. The result of this study can be summarized as follows. 1. Because of incongruity of soil and regardless of physiological properties of trees, the plants were damaged by their environment. In particular, the stress of soil moisture was serious. 2. The unsuitable planting forms for the park were found out through the park, which was the result of imprudent, additional planting. And so in planting trees additionally, the participation of landscape architect is needed. 3. There is a serious noisy problem from express way. Because when they planted trees, they did not consider about noise. It affected the quality and utilization of the park.