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[Author] Young KIM(118hit)

61-80hit(118hit)

  • Motion Evaluation for Rehabilitation Training of the Disabled

    Tae-young KIM  Jun PARK  Cheol-Su LIM  

     
    LETTER-Vision

      Vol:
    E91-A No:9
      Page(s):
    2688-2690

    In this paper, a motion evaluation technique for rehabilitation training is introduced. Motion recognition technologies have been developed for determining matching motions in the training set. However, we need to measure how well and how much of the motion has been followed for training motion evaluation. We employed a Finite State Machine as a framework of motion evaluation. For similarity analysis, we used weighted angular value differences although any template matching algorithm may be used. For robustness under illumination changes, IR LED's and cameras with IR-pass filter were used. Developed technique was successfully used for rehabilitation training of the disabled. Therapists appraised the system as practically useful.

  • On the Application of PN Acquisition Scheme to a DS/SSMA Packet Radio System

    Jin Young KIM  Jae Hong LEE  

     
    PAPER-Mobile Communication

      Vol:
    E80-B No:9
      Page(s):
    1327-1336

    The performance of a noncoherent parallel matched-filter (MF) acquisition scheme with a reference filter (RF) is evaluated for a direct-sequence/spread-spectrum multiple access (DS/SSMA) packet radio system in a mobile cellular environment. This acquisition scheme employs a RF to estimate the variance of interference at the output of detecting MF. Acquisition-based packet throughput of the parallel NM-RF scheme is derived for an AWGN and a Rayleigh fading channels. Packet throughput of a parallel MF-RF acquisition scheme is compared with those of a serial MF scheme, a serial MF-RF scheme, and a parallel MF. From the numerical results, it is shown that the packet throughput decreases with the number of users in the system, and increases with the preamble length. Imperfect power control causes packet throughput to decrease especially when the power control error is large. The considerations in this paper can be applied to the reverse link (mobile-to-base station) design of a DS/SSMA system for packet-type services.

  • Joint Erlang Capacity of DS/CDMA Forward Link Based on Resource Sharing Algorithm

    Wan CHOI  Jin Young KIM  

     
    PAPER

      Vol:
    E84-A No:6
      Page(s):
    1406-1412

    In future mobile communication systems, forward link may be a limiting one because emerging data services are likely to require higher data rates in the forward link than in the reverse link. In this paper, we derive joint Erlang capacity of a DS/CDMA forward link in terms of both outage probability and blocking probability for each type of traffic in a mixed traffic environment. Resource sharing algorithm and generalized Erlang model are employed to derive joint Erlang capacity of the DS/CDMA system with various types of traffics. The joint Erlang capacity reflecting both outage probability and blocking probability of each type of traffic is obtained by an approach based on virtual circuit switching perspective. We take into account effect of closed loop power control in the analysis. From numerical results, it is confirmed that blocking probability as a QoS (quality of service) parameter has a significant impact on the forward link capacity. The results of this paper can be applied to design of the DS/CDMA systems supporting wireless multimedia traffics.

  • A Buffer Management Technique for Guaranteed Desired Communication Reliability and Low-Power in Wireless Sensor Networks

    Dae-Young KIM  Jinsung CHO  Ben LEE  

     
    LETTER

      Vol:
    E93-B No:12
      Page(s):
    3522-3525

    Reliable data transmission is desirable in wireless sensor networks due to the high packet loss rate during multi-hop transmissions. To reliably transmit data for event-driven applications, packet loss recovery mechanism is needed. For loss recovery, sensor nodes need to keep packets in their buffers until transmissions successfully complete. However, since sensor nodes have limited memory, packets cannot be buffered for a long period of time. This letter proposes an efficient buffer management technique that caches data packets for appropriate amount of time to minimize the resource requirements and at the same time provide reliable data transmission among sensor nodes.

  • Construction of Global State Transition Graph for Verifying Specifications Written in Message Sequence Charts for Telecommunications Software

    Byeong Man KIM  Hyeon Soo KIM  Wooyoung KIM  

     
    PAPER-Software Engineering

      Vol:
    E84-D No:2
      Page(s):
    249-261

    Message Sequence Chart (MSC) standardized by International Telecommunication Union is a graphical and textual language for specification of concurrent systems. It has been used formally as well as informally to specify behavior of real-time systems, in particular telecommunication switching systems. Formal verification of a system specification is crucial to ensure that implementation of the system works correctly. In particular, verification methods based on finite states have been widely used in telecommunication systems design. The methods determine global system states and transitions between them (i. e. , build a global state transition graph (GSTG)), and verify the system's desired properties, such as safety and liveness, on the GSTG. In this paper, we focus on construction of GSTGs from MSC specifications. We propose action dependency graph as an intuitive description of semantics of MSC specifications and present an algorithm to translate MSC specifications to action dependency graphs as well as an algorithm to construct a global state transition graph from an action dependency graph.

  • Interference Cancellation and Multipath Mitigation Algorithm for GPS Using Subspace Projection Algorithms

    Jeong Hwan SHIN  Jun HEO  Seokho YOON  Sun Young KIM  

     
    LETTER-Communication Theory and Signals

      Vol:
    E91-A No:3
      Page(s):
    905-908

    This paper presents an interference cancellation and multipath mitigation algorithm for use in Global Positioning System (GPS) with an array antenna. It is shown that interference signals and multipath signals are effectively suppressed using a serial subspace projection method without any knowledge of the incoming directional information. After the subspace projections, a beamformer is used to maximize the SNR of the received signal. The enhancement in the performance is presented in terms of the cross correlation value and beam patterns.

  • Spectral Domain Noise Modeling in Compressive Sensing-Based Tonal Signal Detection

    Chenlin HU  Jin Young KIM  Seung Ho CHOI  Chang Joo KIM  

     
    LETTER-Digital Signal Processing

      Vol:
    E98-A No:5
      Page(s):
    1122-1125

    Tonal signals are shown as spectral peaks in the frequency domain. When the number of spectral peaks is small and the spectral signal is sparse, Compressive Sensing (CS) can be adopted to locate the peaks with a low-cost sensing system. In the CS scheme, a time domain signal is modelled as $oldsymbol{y}=Phi F^{-1}oldsymbol{s}$, where y and s are signal vectors in the time and frequency domains. In addition, F-1 and $Phi$ are an inverse DFT matrix and a random-sampling matrix, respectively. For a given y and $Phi$, the CS method attempts to estimate s with l0 or l1 optimization. To generate the peak candidates, we adopt the frequency-domain information of $ esmile{oldsymbol{s}}$ = $oldsymbol{F} esmile{oldsymbol{y}}$, where $ esmile{y}$ is the extended version of y and $ esmile{oldsymbol{y}}left(oldsymbol{n} ight)$ is zero when n is not elements of CS time instances. In this paper, we develop Gaussian statistics of $ esmile{oldsymbol{s}}$. That is, the variance and the mean values of $ esmile{oldsymbol{s}}left(oldsymbol{k} ight)$ are examined.

  • Development of a Lip-Sync Algorithm Based on an Audio-Visual Corpus

    Jinyoung KIM  Joohun LEE  Katsuhiko SHIRAI  

     
    LETTER-Databases

      Vol:
    E86-D No:2
      Page(s):
    334-339

    In this paper, we propose a corpus-based lip-sync algorithm for natural face animation. For this purpose, we constructed a Korean audio-visual (AV) corpus. Based on this AV corpus, we propose a concatenation method of AV units, which is similar to a corpus-based text-to-speech system. For our AV corpus, lip-related parameters were extracted from every video-recorded facial shot which of speaker reads the given texts selected from newspapers. The spoken utterances were labeled with HTK and such prosodic information as duration, pitch and intensity was extracted as lip-sync parameters. Based on the constructed AV corpus, basic synthetic units are set by CVC-syllable units. For the best concatenation performance, based on the phonetic environment distance and the prosodic distance, the best path is estimated by a general Viterbi search algorithm. From the computer simulation results, we found that the information concerned with not only duration but also pitch and intensity is useful to enhance the lip-sync performance. And the reconstructed lip parameters have almost equal values to those of the original parameters.

  • A New Approach for Personal Identification Based on dVCG

    Jong Shill LEE  Baek Hwan CHO  Young Joon CHEE  In Young KIM  Sun I. KIM  

     
    LETTER-Application Information Security

      Vol:
    E91-D No:4
      Page(s):
    1201-1205

    We propose a new approach to personal identification using derived vectorcardiogram (dVCG). The dVCG was calculated from recorded ECG using inverse Dower transform. Twenty-one features were extracted from the resulting dVCG. To analyze the effect of each feature and to improve efficiency while maintaining the performance, we performed feature selection using the Relief-F algorithm using these 21 features. Each set of the eight highest ranked features and all 21 features were used in SVM learning and in tests, respectively. The classification accuracy using the entire feature set was 99.53 %. However, using only the eight highest ranked features, the classification accuracy was 99.07 %, indicating only a 0.46 % decrease in accuracy compared with the accuracy achieved using the entire feature set. Using only the eight highest ranked features, the conventional ECG method resulted in a 93 % recognition rate, whereas our method achieved >99 % recognition rate, over 6 % higher than the conventional ECG method. Our experiments show that it is possible to perform a personal identification using only eight features extracted from the dVCG.

  • Capsule Network with Shortcut Routing Open Access

    Thanh Vu DANG  Hoang Trong VO  Gwang Hyun YU  Jin Young KIM  

     
    PAPER-Image

      Pubricized:
    2021/01/27
      Vol:
    E104-A No:8
      Page(s):
    1043-1050

    Capsules are fundamental informative units that are introduced into capsule networks to manipulate the hierarchical presentation of patterns. The part-hole relationship of an entity is learned through capsule layers, using a routing-by-agreement mechanism that is approximated by a voting procedure. Nevertheless, existing routing methods are computationally inefficient. We address this issue by proposing a novel routing mechanism, namely “shortcut routing”, that directly learns to activate global capsules from local capsules. In our method, the number of operations in the routing procedure is reduced by omitting the capsules in intermediate layers, resulting in lighter routing. To further address the computational problem, we investigate an attention-based approach, and propose fuzzy coefficients, which have been found to be efficient than mixture coefficients from EM routing. Our method achieves on-par classification results on the Mnist (99.52%), smallnorb (93.91%), and affNist (89.02%) datasets. Compared to EM routing, our fuzzy-based and attention-based routing methods attain reductions of 1.42 and 2.5 in terms of the number of calculations.

  • On-Chip Resonant Supply Noise Canceller Utilizing Parasitic Capacitance of Sleep Blocks for Power Mode Switch

    Jinmyoung KIM  Toru NAKURA  Hidehiro TAKATA  Koichiro ISHIBASHI  Makoto IKEDA  Kunihiro ASADA  

     
    PAPER

      Vol:
    E94-C No:4
      Page(s):
    511-519

    This paper presents an on-chip resonant supply noise canceller utilizing parasitic capacitance of sleep blocks. The test chip was fabricated in a 0.18 µm CMOS process and measurement results show 43.3% and 12.5% supply noise reduction on the abrupt supply voltage switching and the abrupt wake-up of a sleep block, respectively. The proposed method requires 1.5% area overhead for four 100 k-gate blocks, which is 7.1 X noise reduction efficient comparing with the conventional decap for the same power supply noise, while achieves 47% improvement of settling time. These results make fast switching of power mode possible for dynamic voltage scaling and power gating.

  • Relay Selection Scheme for Improved Performance in the Wireless Communication Systems Based on OFDM

    Sang-Young KIM  Won-Chang KIM  Hyoung-Kyu SONG  

     
    LETTER-Communication Theory and Signals

      Vol:
    E100-A No:10
      Page(s):
    2200-2203

    This letter proposes a relay selection scheme in order to improve a performance in the wireless cooperative communication system. The cooperative communication uses the relays in order to obtain a improved performance. The relay selection scheme has a great influence on the performance of the wireless cooperative communication. Because the diversity gain is affected by the superposition of the channels, a superposition of the channels is important in the wireless cooperative communication. The constructive superposition of the channels can improve the performance of the wireless cooperative communication. Because the conventional schemes do not consider the superposition of the channels, the conventional schemes are not suitable for the cooperative communication using the multiple relays. The new scheme considers the superposition of channels and selects the relays that can achieve the constructive superposition. Therefore, the new scheme can provide the improved performance by using the phase information between channels. The simulation results show that the bit error performance of the proposed scheme is better than the conventional schemes.

  • A Monte-Carlo FDTD Technique for Electromagnetic Wave Scattering from a Perfectly Conducting Fractal Surface

    Dong-Muk CHOI  Che-Young KIM  Kwang-Hee KWON  

     
    LETTER-Electromagnetic Theory

      Vol:
    E86-C No:4
      Page(s):
    668-671

    This letter presents a Monte-Carlo FDTD technique to determine the scattered field from a perfectly conducting fractal surface from which the useful information on the incoherent pattern tendency could be observed. A one-dimensional fractal surface was generated by the bandlimited Weierstrass function. In order to verify the numerical results by this technique, these results are compared with those of Kirchhoff approximations, which show a good match between them. To investigate the incoherent pattern tendency involved, the dependence of the fitting curve slope on the different D and is discussed for the bistatic and back scattering case, respectively.

  • Adaptive Cooperative Transmission with Spatial Phase Coding for Interference Mitigation in the Wireless Cellular Communication

    Sang-Young KIM  Yong-Jun KIM  Hyoung-Kyu SONG  

     
    LETTER-Communication Theory and Signals

      Vol:
    E100-A No:1
      Page(s):
    317-321

    This letter proposes a cooperative communication scheme with pre-coding in order to improve a performance in a wireless communication system. In a conventional scheme, a performance of the system is degraded due to the signal attenuation by the path loss and inter-cell interference (ICI). The proposed scheme uses two relays in order to obtain a diversity gain. Additionally, the proposed scheme uses a constructive spatial phase coding (SPC) using the phase relation of the channels in order to obtain an improved diversity gain. Therefore, the proposed scheme can prevent the performance degradation caused by the path loss. When a mobile is located in the cell edge, the signal suffers from the ICI by the other signals transmitted from a neighboring base station. In the proposed scheme, the other signals broadcast from neighboring base station are destructively superimposed by using the destructive SPC scheme. And then the power of the destructively superimposed signal is reduced. Therefore, the proposed scheme can reduce the ICI effect in the cell edge. Also, the destructively superimposed signal does not cause the performance degradation of other mobiles in the neighboring cell. The simulation results show that the bit error performance of the proposed scheme is better than the conventional scheme.

  • Downlink Multi-Point Transmission Effect Using Aggregate Base Station Architecture

    Soon-Gi PARK  Dae-Young KIM  

     
    LETTER

      Vol:
    E94-B No:12
      Page(s):
    3374-3377

    Downlink multi-point transmission as a capacity enhancement method for the users at cell edge and the operators is studied in this paper. It is based on the so-called aggregate base station architecture using distributed antennas and cloud computing. Its advantages are analyzed by both its architectural side and simulation. The simulation results show that the capacity may be affected by the number of cell belonging to an aggregate base station and by the parameters related to the operation of it.

  • One-Hop Neighbor Based Broadcast Scheduling in Wireless Sensor Networks

    Taehong KIM  Daeyoung KIM  Chong Poh KIT  

     
    LETTER-Network

      Vol:
    E94-B No:1
      Page(s):
    297-301

    For wireless sensor networks in which resources are limited and network topology dynamically changes, we propose the one-hop neighbor based broadcast scheduling (ONBS) algorithm to provide reliable delivery service of broadcast packets. The proposed algorithm reduces the scheduling overhead by allowing each joining node to decide its broadcast schedule based on only its one-hop neighbor information in an on-line and distributed manner. Also, once the broadcast schedule is decided, it is not changed to accommodate a newly joining node in order to prevent the consecutive changes of existing schedules. The network simulation results show that the proposed algorithm provides low latency and high reachability despite low overhead and on-line algorithm design.

  • Acquisition Performance of a DS/CDMA System in a Mobile Satellite Environment

    Jin Young KIM  Jae Hong LEE  

     
    PAPER-Modem and Coding

      Vol:
    E80-B No:1
      Page(s):
    40-48

    This paper evaluate the performance of a PN (pseudonoise) code acquisition for a direct-sequence/code-division-multiple-access (DS/CDMA) system in a mobile satellite environment. The acquisition scheme considered consists of a parallel matched-filter and a FFT processor. The uplink of mobile satellite channel is modeled as shadowed Rayleigh fading channel. The effects of power control error and shadowing are considered in the analysis of acquisition performance. It is shown that the power control error causes acquisition to be slower than the case of perfect power control, and for high SNR/chip, the effect of power control error becomes less significant. It is also shown that the case with heavy shadowing takes longer time to achieve acquisition than that with light shadowing. For the subinterval-based PN code search, the parallel MF scheme is thought to be more appropriate than the serial MF scheme at the cost of complexity. The analysis in the paper can be applied to the uplink of a DS/CDMA system for packet-type services in a mobile satellite channel.

  • Limiting the Length of BET for Tunnel-Based IP Fast Handover

    HeeYoung JUNG  SeokJoo KOH  JaeHong MIN  DaeYoung KIM  

     
    LETTER

      Vol:
    E87-A No:6
      Page(s):
    1527-1530

    Next generation wired/wireless networks will be based on IP technology. In the IP based networks, it is crucially required to support seamless mobility especially for proving real-time services in the mobile environment. The conventional Mobile IP protocols cannot satisfy such seamless mobility requirements for real-time services. Therefore various extensions of Mobile IP are being proposed. In this paper, we propose a new handover scheme to enhance the existing tunnel-based fast handover method, which is a typical Mobile IP extension to support seamless mobility. It is shown that the proposed method reduces the traffic overhead in the networks. It is expected that the proposed method will be particularly useful in the IP-based networks in which there are a number of users simultaneously using the long-lived real-time services, or in the condition that the traffic overhead is considered as a critical performance measure.

  • Rate Compatible Block Turbo Codes for Hybrid ARQ Schemes

    Sooyoung KIM  Jae Moung KIM  Sung Pal LEE  

     
    LETTER-Fundamental Theories

      Vol:
    E87-B No:4
      Page(s):
    999-1001

    Rate compatible (RC) codes are used for adaptive coding schemes or hybrid ARQ schemes in order to adapt varying channel conditions. This can improve overall service quality or the system throughput. Conventional RC codes have usually been designed on the basis of convolutional codes. This letter proposes an efficient RC code based on block codes. We use a high dimensional product code and divide it into the information block and a number of parity blocks. We form RC product codes using various combinations of these blocks. Because we can decode the RC product codes iteratively, these result in block turbo codes and they can be used efficiently for hybrid ARQ schemes.

  • Towards TMN-Based Integrated Network Management Using CORBA and Java Technologies

    Jae-Young KIM  Hong-Taek JU  James Won-Ki HONG  Seong-Beom KIM  Chan-Kyou HWANG  

     
    INVITED PAPER

      Vol:
    E82-B No:11
      Page(s):
    1729-1741

    Today's complicated and heterogeneous telecommunication network environments need fully-integrated, cost-effective, user-friendly management systems. When developing such management systems in distributed environments, many telecommunication companies are carefully adopting CORBA and Java technologies. CORBA technology enables developers to create and manipulate distributed management system components easily while Java technology liberates human users from complicated and proprietary management system interfaces. In this paper, we propose a TMN-based integration framework for distributed network management by combining both CORBA and Java technologies. The framework generalizes a logically-layered architecture from the management agents layer to the user interface layer. It also provides generalized TMN management interfaces using inter-domain gateway systems for coordinating heterogeneous management protocols. By using these interfaces, TMN management function components can be easily constructed as CORBA objects to provide powerful TMN management services to administrators via user-friendly Web browsers. On the basis of this framework, we have designed and implemented a TMN alarm surveillance system which realizes our framework.

61-80hit(118hit)