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Error Concealment Based on Multiple Representation for Wireless Transmission of JPEG2000 Image

  • Ou, Yang;Lee, Won-Young;Yang, Tae-Uk;Chee, Sung-Taek;Rhee, Kyung-Hyune
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.33 no.1C
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    • pp.68-78
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    • 2008
  • The transmission of multimedia information over error-prone channels such as wireless networks has become an important area of research. In this paper, we propose two Error Concealment(EC) schemes for wireless transmission of JPEG2000 image. The Multiple Representation(MR) is employed as the preprocessing in our schemes, whereas the main error concealing operation is applied in wavelet domain at receiver side. The compressed code-stream of several subsampled versions of original image is transmitted over a single channel with random bit errors. In the decoder side, the correctly reconstructed wavelet coefficients are utilized to recover the corrupted coefficients in other sub-images. The recovery is carried out by proposed basic(MREC-BS) or enhanced(MREC-ES) methods, both of which can be simply implemented. Moreover, there is no iterative processing during error concealing, which results a big time saving. Also, the simulation results confirm the effectiveness and efficiency of our proposed schemes.

A Study on the Efficiency of Join Operation On Stream Data Using Sliding Windows (스트림 데이터에서 슬라이딩 윈도우를 사용한 조인 연산의 효율에 관한 연구)

  • Yang, Young-Hyoo
    • Journal of the Korea Society of Computer and Information
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    • v.17 no.2
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    • pp.149-157
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    • 2012
  • In this thesis, the problem of computing approximate answers to continuous sliding-window joins over data streams when the available memory may be insufficient to keep the entire join state. One approximation scenario is to provide a maximum subset of the result, with the objective of losing as few result tuples as possible. An alternative scenario is to provide a random sample of the join result, e.g., if the output of the join is being aggregated. It is shown formally that neither approximation can be addressed effectively for a sliding-window join of arbitrary input streams. Previous work has addressed only the maximum-subset problem, and has implicitly used a frequency based model of stream arrival. There exists a sampling problem for this model. More importantly, it is shown that a broad class of applications for which an age-based model of stream arrival is more appropriate, and both approximation scenarios under this new model are addressed. Finally, for the case of multiple joins being executed with an overall memory constraint, an algorithm for memory allocation across the join that optimizes a combined measure of approximation in all scenarios considered is provided.

A New Rekeying Scheme for 802.11 Wireless Packets Transmission (802.11 무선패킷 전송을 위한 새로운 Rekeying 스킴)

  • Phang, Seong-Yee;They, Yu-Shu;Yang, Chi-Shian;Lee, Hoon-Jae;Lim, Hyo-Taek
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2008.10a
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    • pp.274-277
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    • 2008
  • Rekeying is the process of changing the encryption key of an ongoing communication. The main objective is to limit the amount of data encrypted with the same key. The IEEE 802.11 standard defines the Wired Equivalent Privacy, or WEP, encapsulation of 802.11 data frames. MAC at sender encrypts the payload (frame body and CRC) of each 802.11 frame before transmission using RC4 stream cipher. MAC at receiver decrypts and passes data to higher level protocol. WEP uses symmetric key stream cipher (RC4) where same key will be used for data encryption and decryption at the sender and the receiver. WEP is not promising with the advancement of the wireless technology existing today. We propose to use the existing information to define the security attributes. This will eliminate the steps that regenerated keys have to be sent to each other over certain period. The rekeying scheme is according to the number of bytes transmitted. Therefore, even the attacker has recorded the packets, it will be insufficient information and time for the attacker to launch the attacks as the key is not deterministic. We develop a packet simulation software for packet transmission and simulate our propose scheme. From the simulation, our propose scheme will overcome the weak WEP key attack and provide an alternative solution to wireless packet transmission. Besides that, our solution appears to be a software approach where only driver updates are needed for the wireless client and server.

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A Study on the Behavior of Liquid Film Flow in Intake Manifold - On the improvement of intake manifold system - (흡기관내(吸氣管內) 액막류(液膜流) 거동(擧動)에 관(開)한 연구(硏究) (I) - 흡기계통(吸氣系統)의 품질개선(品質改善)을 위(爲)하여 -)

  • Jeon, Heung-Sin;Lee, Gyu-Yeong;Park, Gyeong-Seok;Yang, Ok-Yong;Seong, Hwan-Tae
    • Journal of Korean Society for Quality Management
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    • v.9 no.2
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    • pp.15-25
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    • 1981
  • This paper deals with the experimental study on the behavior of fuel flow in intake manifold of gasoline engine. The main purpose of this study is an analysis of air stream velocity, behavior of liquid film flow, generation of atomization and atomization rate by using the basic apparatus which is manufactured the visible, straight tube type model of intake manifold. As the result, we have found factors which influenced on the behavior of liquid film flow in intake manifold.

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A Study of the Trend on Structuralism Appeared in the Contemporary Hospital Architecture (현대 병원건축에서 나타나는 구조주의적 경향에 관한 연구)

  • Cho, Jun-Young;Yang, Nae-Won
    • Journal of The Korea Institute of Healthcare Architecture
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    • v.14 no.2
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    • pp.65-72
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    • 2008
  • Structuralism on the architecture have been appeared in the middle of 20th Century against Functionalism. The hospital architecture which is a representation of functionalism architecture couldn't be an exception in the stream of this change. This study doesn't regard the hospital architecture as a specific area limited by Functionalism but as a general area of the architecture. This study analyze the features of the form and system on the hospital which is affected by Structuralism. Then by the analysis of the features on the change of a native hospital, it will be interpreted that a native hospital would be adapted with the formation of Structuralism.

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Development of Probability Theory based Dynamic Travel Time Models (확률론적 이론에 기초한 동적 통행시간 모형 정립)

  • Yang, Chul-Su
    • Journal of Korean Society of Transportation
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    • v.29 no.3
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    • pp.83-91
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    • 2011
  • This paper discusses models for estimating dynamic travel times based on probability theory. The dynamic travel time models proposed in the paper are formulated assuming that the travel time of a vehicle depends on the distribution of the traffic stream condition with respect to the location along a road when the subject vehicle enters the starting point of a travel distance or with respect to the time at the starting point of a travel distance. The models also assume that the dynamic traffic flow can be represented as an exponential distribution function among other types of probability density functions.

A Numerical Study on the Planar Contraction Flow of Oldroyd B Fluids (Oldroyd B 유체의 평면 수축 유동에 관한 수치 해석적 연구)

  • Yoo, Jung-Yul;Na, Yang
    • The Korean Journal of Rheology
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    • v.2 no.1
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    • pp.33-45
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    • 1990
  • This study analyzes the planar 4:1 contraction flow of viscoelastic fluids with retardation time using finite volume method. To consider separately the elasticity effect of the viscoelastic fluid without shear thinn-ing effect, Oldroyd B liquid model is adopted for the numerical simulation. Instead of the stream function-vorticity formulation, SIMPLER algorithm with staggered grid system which incorporates primitive variable has been introduced in discretizing the momentum equations. An upwind corrected scheme has been used in discetizing the constitutive equations for the non-Newtonian part of the stress. The size of the corner vortex is shown to be slightly influenced by the Weissenberg number. However as the Weissenberg number is increased the chang-ing of the vortex shape agrees qualitatively well with some experimental studies.

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기름 유출로 인한 토양 및 지하수의 오염

  • Kim Dong-Jin;Yang Jae-Eui;Yu Jin-Yeol;Kim Hui-Gap;Kim Gi-Dong
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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    • 2006.04a
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    • pp.424-427
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    • 2006
  • Soil contamination with petroleum oil around a military army was investigated. It showed that soils of a riverside highland, an entrance of the military army, and nearby roads were contaminated with total petroleum hydrocarbons (TPH) released from the military army to the depth of approximately 2 m. The measured concentrations were as high as 15,277 mg/kg. A wide range of soil in the riverside highland was contaminated by the movement of oil to the surface soil, which occurred with the vertical movement of groundwater table caused by the change of river water level and groundwater level. Spilled petroleum oil components were released into Wonju Stream by the increase of hydraulic conductivity and the groundwater flow.

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An Experimental Study on the Local Effective Thermal Conductivity in Packed Bed (충전층에서의 국부유효열전도율에 관한 실험적 연구)

  • Lee J.S;Yang H.J;Choi K.K;Seo J.Y
    • The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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    • v.16 no.1
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    • pp.81-88
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    • 1987
  • In this paper, the local effective thermal conductivities and calculated by using the actual temperature distribution in packed bed. The variations of these are investigated for radius and air stream direction, flow rate and particle diameter. The resulting local effective thermal conductivi-ties are classified in the inner zone of bed and vicinity zone of the wall surface. Also these are related to dimensionless axial direction position, radius direction position, and particle diameter and Reynolds number which uses particle diameter as the characteristic length. If these correla-tions are represented by function, the equation is showed in Eq. (3-4). This equation is well satisfied with experimental results within $\pm25\%.$

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Efficient Management of Moving Object Trajectories in the Stream Environment (스트림 환경에서 이동객체 궤적의 효율적 관리)

  • Lee, Won-Cheol;Moon, Yang-Sae;Rhee, Sang-Min
    • Journal of KIISE:Databases
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    • v.34 no.4
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    • pp.343-356
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    • 2007
  • Due to advances in position monitoring technologies such as global positioning systems and sensor networks, recent position information of moving objects has the form of streaming data which are updated continuously and rapidly. In this paper we propose an efficient trajectory maintenance method that stores the streaming position data of moving objects in the limited size of storage space and estimates past positions based on the stored data. For this, we first propose a new concept of incremental extraction of position information. The incremental extraction means that, whenever a new position is added into the system, we incrementally re-compute the new version of past position data maintained in the system using the current version of past position data and the newly added position. Next, based on the incremental extraction, we present an overall framework that stores position information and estimates past positions in the stream environment. We then propose two polynomial-based methods, line-based and curve-based methods, as the method of estimating the past positions on the framework. We also propose three incremental extraction methods: equi-width, slope-based, and recent-emphasis extraction methods. Experimental results show that the proposed incremental extraction provides the relatively high accuracy (error rate is less than 3%) even though we maintain only a little portion (only 0.1%) of past position information. In particular, the curve-based incremental extraction provides very low error rate of 1.5% even storing 0.1% of total position data. These results indicate that our incremental extraction methods provide an efficient framework for storing the position information of moving objects and estimating the past positions in the stream environment.