• Title/Summary/Keyword: 임의시간

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Separation of the Occluding Object from the Stack of 3D Objects Using a 2D Image (겹쳐진 3차원 물체의 2차원 영상에서 가리는 물체의 구분기법)

  • 송필재;홍민철;한헌수
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.41 no.2
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    • pp.11-22
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    • 2004
  • Conventional algorithms of separating overlapped objects are mostly based on template matching methods and thus their application domain is restricted to 2D objects and the processing time increases when the number of templates (object models) does. To solve these problems, this paper proposes a new approach of separating the occluding object from the stack of 3D objects using the relationship between surfaces without any information on the objects. The proposed algorithm considers an object as a combination of surfaces which are consisted with a set of boundary edges. Overlap of 3D objects appears as overlap of surfaces and thus as crossings of edges in 2D image. Based on this observation, the types of edge crossings are classified from which the types of overlap of 3D objects can be identified. The relationships between surfaces are represented by an attributed graph where the types of overlaps are represented by relation values. Using the relation values, the surfaces pertained to the same object are discerned and the overlapping object on the top of the stack can be separated. The performance of the proposed algorithm has been proved by the experiments using the overlapped images of 3D objects selected among the standard industrial parts.

High Performance QoS Multicast Routing Scheme for Real-Time Mobile Multimedia Applications in Wireless Mesh Networks (무선메쉬네트워크에서 실시간 이동 멀티미디어 응용을 위한 고성능 QoS 멀티캐스트 라우팅 기법)

  • Kang, Moonsik
    • Journal of the Institute of Electronics and Information Engineers
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    • v.52 no.6
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    • pp.85-94
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    • 2015
  • In this paper, an enhanced QoS multicast routing scheduling scheme is proposed to adapt to a dynamic mobile traffic condition for wireless mesh networks (WMNs). It handles the network QoS by controlling the delay constraints for multimedia applications. The group size will be controlled according to both the current network state and QoS requirements. The dynamic reconstruction of QoS multicast tree can be obtained from preprocessing with both the partial multicast routing scheme and the traffic estimation. Performance evaluation of the proposed scheme is carried out on randomly generated graph derived from the wireless mesh network, by choosing the optimal value related to the appropriate delay bounds. Simulation results show that the proposed scheme can improve the performance of QoS multicast routing for WMNs.

Improving Clustering-Based Background Modeling Techniques Using Markov Random Fields (클러스터링과 마르코프 랜덤 필드를 이용한 배경 모델링 기법 제안)

  • Hahn, Hee-Il;Park, Soo-Bin
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.48 no.1
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    • pp.157-165
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    • 2011
  • It is challenging to detect foreground objects when background includes an illumination variation, shadow or structural variation due to its motion. Basically pixel-based background models including codebook-based modeling suffer from statistical randomness of each pixel. This paper proposes an algorithm that incorporates Markov random field model into pixel-based background modeling to achieve more accurate foreground detection. Under the assumptions the distance between the pixel on the input imaging and the corresponding background model and the difference between the scene estimates of the spatio-temporally neighboring pixels are exponentially distributed, a recursive approach for estimating the MRF regularizing parameters is proposed. The proposed method alternates between estimating the parameters with the intermediate foreground detection and estimating the foreground detection with the estimated parameters, after computing it with random initial parameters. Extensive experiment is conducted with several videos recorded both indoors and outdoors to compare the proposed method with the standard codebook-based algorithm.

Large Slow-Drift Motions of a Floating Body in Slightly Modulated Waves (해상(海上)에 계류(繫留)된 부유체(浮遊體)의 표류운동(漂流運動) 해석(解析))

  • Dong-J.,Kim;Hang-S.,Choi
    • Bulletin of the Society of Naval Architects of Korea
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    • v.27 no.4
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    • pp.3-14
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    • 1990
  • For a moored body on the sea surface, incident waves with narrow-banded spectra excite the body oscillations of short and long periods. Since the period of slow oscillations can be as long as the natural period of the moored body in horizontal modes, resonance can occur and resulting large motions may cause significant strains in mooring cables. By using the perturbation method of multiple scales, the large slow motion can be analyzed without solving any second-order potentials explicitly. To the leading order, the flows associated with the fast and slow motions interact only parametrically and thus they can be studied separately. It is found that the slow motion strongly depends on the mooring stiffness. In particular, if the moring stiffness is considerably weak compared to the body inertia, the slow motion is highly amplified near resonance. It is also shown that the slow motion is associated with the generation of long waves.

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Thermal Characteristics Analysis of Upper Arm Hybrid Structure of Lightweight Pantograph Considering Heat Source by Collecting Current (집전전류에 의한 열원을 고려한 경량 판토그래프 상부암 혼성구조체의 열 특성 분석 연구)

  • Park, Chan-Bae;Jeong, Geochul
    • Journal of the Korean Society for Railway
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    • v.20 no.4
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    • pp.466-473
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    • 2017
  • Recently, domestic railway related institutes are developing pantographs for high speed trains; to lighten the upper arm, this device has a composite structure of CFRP (Carbon Fiber Reinforced Plastic) and aluminum instead of conventional steel. In the case of KTX-Sancheon, the pantograph must have a large current capacity because this system is of power-car type, supplying all necessary power for the train through a single pantograph. If the thickness of the pipe is arbitrarily increased in order to increase the current carrying capacity, without analyzing the thermal characteristics of the aluminum pipe, the increase in the weight of the upper arm may cause degradation of the current collecting performance. Therefore, in this paper, using the thermal analysis technique, we analyze the temperature change characteristics of the aluminum pipe of the upper arm over time, while receiving power at the stationary state of the KTX-Sancheon; we also examine the adequacy of the minimum thickness of the aluminum pipe in accordance with the proposed pantograph flow capacity.

User Authentication Key Establishment Scheme based on Color Model for Healthcare Environment (헬스케어 환경을 위한 칼라 모델 기반의 사용자 인증 키 설립 기법)

  • Jeong, Yoon-Su
    • Journal of the Korea Convergence Society
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    • v.8 no.3
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    • pp.115-121
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    • 2017
  • Hospital medical services are making great efforts to provide prompt medical services to patients or improve the quality of medical services by convergence patient's healthcare information. However, recent research suggests problems about safety and efficiency when trying to transmit patient's healthcare information to hospital server via radio and wireless. In this paper, we propose a color model - based patient authentication key establishment protocol method to securely transmit patient healthcare information. The proposed method extracts randomly three color information used in the color model and vectorizes the extracted arbitrary information to obtain the key information required for user authentication as the sum of orthogonal vectors to improve the efficiency. In addition, the proposed method can securely generate key information used for user authentication without using an additional encryption algorithm. In performance evaluation result, proposed method shows that the server processing time of the sensed information is 8.1% higher than the existing method and 7.7% lower than the existing method.

Infiltration Analysis for Surficial Stability Evaluation of Two-layered Slopes (2층 지반의 표면파괴에 대한 안정성 평가를 위한 침투거동 해석)

  • Cho Sung-Eun
    • Journal of the Korean Geotechnical Society
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    • v.21 no.8
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    • pp.45-53
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    • 2005
  • Shallow slope failures in residual soil during periods of prolonged infiltration are common over the world. Therefore, this study examines an approximate method to estimate the influence of infiltration on surficial stability of slopes by one-dimensional infiltration model. Modified GAML model based on the Green-Ampt model was extended to predict the infiltration behavior of two-layered slope. Then, the model has been considered to evaluate the likelihood of shallow slope failure which is induced by a particular rainfall event that accounts for the rainfall intensity and duration for various return periods in two-layered soil profile. The results obtained from the approximate method were compared with those obtained from numerical analyses. According to the results, with the use of properly estimated input parameters, the proposed method was found to give good results that agree reasonably well to those of the more rigorous finite element analyses.

Proposal of A Transaction Structure to Improve Compatibility of Blockchain regarding Post-Quantum Digital Signatures (블록체인의 양자 내성 전자서명 호환성을 증대하기 위한 트랜잭션 구조 제안)

  • Kim, Mee Yeon;Lee, Jun Yeong;Yoon, Kisoon;Youm, Heung Youl
    • Journal of the Korea Institute of Information Security & Cryptology
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    • v.30 no.1
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    • pp.87-100
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    • 2020
  • Researches on Post-quantum blockchain, which is a synthesis of blockchain and post-quantum cryptography[1], are relatively unrevealed areas but have needs to be studied with the regard to the quantum computers. However there could be several fundamental problems, e.g. unsustainably large size of public key and signature, or too lengthy time for sign and verification, if any post-quantum cryptography is adopted to the existing blockchain to implement post-quantum blockchain. Thus, a new method was proposed in this paper that produces fixed length of references for massive signatures and corresponding public keys to enable relatively lightweight transactions. This paper proposed the mechanism that included a new transaction structure and protocols, and demonstrated a post-quantum blockchain that the proposed mechanism was adopted. Through this research, it could enhance compatibility of blockchain regarding post-quantum digital signature, possibly reducing weights of the whole blockchain.

Investigation of the Lateral Acoustic Signal Detection Using by Two Fabry-Perot Fiber Optic Sensor Array (두 개의 Fabry-Perot 광섬유 센서 배열을 이용한 횡방향 음압 감지 특성 연구)

  • Lee, Jong kil
    • 대한공업교육학회지
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    • v.31 no.1
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    • pp.185-199
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    • 2006
  • In this paper, to detect lateral direction sound pressure fiber optic sensor using Fabry-Perot interferometeric sensor array was fabricated and experimented. This parallel sensor array composed of one light source and the light split into each sensor using directional coupler and to see the output signal the array system do not need any digital signal processor. As a lateral direction sound source arbitrary sound frequency of 100Hz, 200Hz, and 655Hz using by nondirectional speaker were applied to the array sensor which installed on 60cm×60cm×60cm latticed structure. The detected signals from the two sensors were analyzed in the time and frequency domains. It was confirmed that the suggested sensor array detected applied sound source well but there were a little amplitude differences in between the sensors. Because the sensor supported simply at both ends theoretical analysis was performed and its solution was suggested. To compare the theoretical and experimental results arbitrary sound frequency of 2kHz was applied to the sensor array. It shows that experimental results was good agreement with theoretical results.

Performance Comparison of Trellis Coded Multi-Carrier CDMA SYstem with Transmite/Rceive Antenna Diversity in Indoor Radio Channel (실내 무선 채널에서 송신/수신 안테나 다이버시티를 적용한 Trellis 부호화된 Multi-Carrier CDMA 시스템의 성능 비교)

  • 노재성;이찬주;김언곤;조성준
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.25 no.8B
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    • pp.1348-1356
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    • 2000
  • In this paper, we proposed a trellis coded Multi-Carrier CDMA 16 QAM system with multiple transmit/receive antenna diversity technique, which is simple and suitable for indoor wireless communications. The proposed multiple transmit/receive antenna diversity technique is that the transmitter sends a trellis coded Multi-Carrier CDMA 16 QAM signal from multiple transmitting antennas with intentional time delays, which makes a receiver possible to distinguish and combine the signals from different antennas. In wireless indoor communication system, if we allow the increase of the complexity of the system, it is also possible to achieve additional diversity gain in the performance with the combination of the proposed technique and the conventional receiving antenna diversity. Furthermore, we have found that the proposed trellis coded Multi-Carrier CDMA 16 QAM system, which employs multiple transmit/receive antenna, is less sensitive to the multiple user interference and fading than conventional receiving antenna diversity systems.

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