International Conference

2024

  1. Minkyu Oh, Young-Seok Lee, Jeong-Bong Lim, Chang-Ok Kang, and Bang Chul Jung, “Hierarchical MUSIC Technique for Direction Finding of Multiple Signal Sources,” IEEE CCNC, Jan. 2024.
  2. Ju Yeong Baek, Young-Seok Lee, and Bang Chul Jung, “Downlink RIS-NOMA with Constellation Adjustment for 6G Wireless Communication Systems,” IEEE CCNC, Jan. 2024.

 

2023

  1. Ki-Hun Lee, Howon Lee, Jungwook Choi, Soobum Park, and Bang Chul Jung, “Distributed Space-Time Block Coding for Barrage Relay Networks,” IEEE MILCOM, Oct. 2023.
  2. Jeong Seon Yeom and Bang Chul Jung, “Cell-Free Massive MIMO Uplink Systems with Joint Maximum-Likelihood Detector for 6G Networks,” ICTC, Oct. 2023.
  3. Jeong Seon Yeom, Yujin Lee, and Bang Chul Jung, “MMSE-Based MIMO Receiver for Cooperative Downlink NOMA in LEO Satellite Networks,” ICTC, Oct. 2023.
  4. Young-Seok Lee, Minkyu Oh, InKi Lee, and Bang Chul Jung, “A Novel Correlative Interferometer Technique with Multi-Sample Diversity for Finding Direction of Satellites,” ICTC, Oct. 2023.
  5. Ju Yeong Baek, Young-Seok Lee, and Bang Chul Jung, “STAR-RIS-Enabled NOMA with Signal Constellation Adjustment for 6G LEO Satellite Networks,” ICTC, Oct. 2023.
  6. Yerin Lee, Jimin Jeon, Jungwook Choi, Soobum Park, Donggeun Lee, Bang Chul Jung, and Howon Lee, “UNPR Uncovered Neighbor-aware Probabilistic Relay-Selection Method in Tactical FANETs,” ICTC, Oct. 2023.
  7. Minkyu Oh, Young-Seok Lee, and Bang Chul Jung, “A Low-Complexity Subarray-Based UCCA for Robust LoS MIMO Communications,” IEEE CCNC, Jan. 2023.
  8. Young-Seok Lee, Jeong Seon Yeom, and Bang Chul Jung, “A Novel Antenna-Based GNSS Spoofing Detection and Mitigation Technique,” IEEE CCNC, Jan. 2023.
  9. Ki-Hun Lee, Hyang-Won Lee, Howon Lee, and Bang Chul Jung, “PRADA: Practical Access Point Deployment Algorithm for Cell-Free Industrial IoT Networks,” IEEE CCNC, Jan. 2023.
  10. Hyeonggeun Kim, Jeong Seon Yeom, Jong Min Kim, and Bang Chul Jung, “Coverage Analysis of Spectrum-Shared Directional Networks: Exclusion Zone and Antenna Radiation,” IEEE CCNC, Jan. 2023.

 

2022

  1. Woong Son, Ki-Hun Lee, EunMi Choi, and Bang Chul Jung, “Optimal Design of Full-Duplex Orbital Angular Momentum Mode-Division Multiplexing Systems,” IEEE ICC Workshops, May 2022.

 

2021

  1. Sangku Lee, Janghyuk Youn, Yongjae Kim, and Bang Chul Jung*, “Buffer-Aided Cooperative Phase Steering Technique for Delay-Tolerant Networks,” ICTC, Oct. 2021.
  2. Dong-Su Choi, Yoon-Seon Choi, Min-Seok Baik, Bang Chul Jung* and Jong-Myung Woo, “RFID Tag Antenna Attached to Drug Nozzle and Electronic Fishing Float,” ICUFN, Aug. 2021.
  3. Janghyuk Youn, and Bang Chul Jung*, “A Novel Wireless Channel Confusion Technique with Intelligent Reflecting Surface,” ICEIC, Feb. 2021.
  4. Jae Hee Noh, Byung-Hyi Gong, Young-Seok Lee, Bang Chul Jung*, Sang Jeong Lee, and Heonho Choi, “Performance Analysis of GNSS Spoofing Mitigation Techniques based on Array Antennas in Various Spoofing Scenarios,” ION ITM 2021, Jan. 2021.

 

2020

  1. Ki-Baek Kim, Bang Chul Jung, and Jong-Myung Woo, “Dual-Polarized Microstrip Patch Antenna Array with Dual-Feed for Target Detection,” MIKON, May. 2020.
  2. Youngjun Choi, Jingon Joung, Jihoon Choi, and Bang Chul Jung, “Double Space-Time Line Codes with Transmit Antenna Selection for Two Users,” ICEIC, Jan. 2020.

 

2019

  1. Woong Son, Howon Lee, and Bang Chul Jung, “Capacity Analysis of Multi-Pair Orbital Angular Momentum Interference Networks,” IEEE GLOBECOM Workshops, Dec. 2019.
  2. Woong Son, Howon Lee, and Bang Chul Jung, “Achievable Rate of Multi-User Mode-Division Multiplexing Using Orbital Angular Momentum,”IEEE VTC-Fall, Sep. 2019.
  3. Ki-Hun Lee, Jeong Seon Yeom, Bang Chul Jung, and Jingon Joung, “A Novel Non-Orthogonal Multiple Access with Space-Time Line Codes for Massive IoT Networks,” IEEE VTC-Fall, Sep. 2019.
  4. Jae Won Bae, Ki-Hun Lee, Jong Min Kim, Bang Chul Jung, and Jingon Joung, “Performance Analysis of Uplink NOMA-IoT Networks with Space-Time Line Code,” IEEE VTC-Fall, Sep. 2019.
  5. Janghyuk Yoon, Yongjae Kim, Han Seung Jang, and Bang Chul Jung, “Downlink Interference Alignment with Multi-User and Multi-Beam Diversity for Fog RANs,” IEEE VTC-Fall, Sep. 2019
  6. Eunmi Chu, Jong Min Kim, and Bang Chul Jung, “Interference Analysis of Directional UAV Networks A Stochastic Geometry Approach,” ICUFN, Jul. 2019.
  7. Jeong Seon Yeom, Young-bin Kim, and Bang Chul Jung, “UAV-Assisted Cooperative Downlink NOMA with Virtual Full-Duplex Operation,” ICUFN, Jul. 2019.
  8. Han Seung Jang, Hu Jin, Bang Chul Jung, and Tony Q. S. Quek, “Recursive Access Class Barring for Machine Type Communications with PUSCH Resource Constraints,” IEEE ICC, May. 2019.
  9. Yongjae Kim, Inkyu Bang, Bang Chul Jung, and Youngnam Han, “Adaptive Proportional Fairness Scheduling for SWIPT-Enabled Multicell Downlink Networks,” IEEE WCNC, Apr. 2019.

 

2018

  1. Eunmi Chu, Hyuk Ju Jang, and Bang Chul Jung, “Machine Learning Based Link-to-System Mapping for System-Level Simulation of Cellular Networks,” ICUFN, Jul. 2018.
  2. Woong Son, Bang Chul Jung, Choul-Young Kim, and Jong Min Kim, “Pseudo-Random Beamforming with Beam Selection for Improving Physical-Layer Security,” ICUFN, Jul. 2018.
  3. Jeong Seon Yeom, Han Seung Jang, and Bang Chul Jung, “Diversity-Controlled Multi-User Superposition Transmission for Uplink Cellular Networks,” ICUFN, Jul. 2018.
  4. Young-bin Kim, Kosuke Yamazaki, and Bang Chul Jung, “Adaptive Successive Transmission in Virtual Full-Duplex Cooperative NOMA,” IEEE WCNC, Apr. 2018.

 

2017

  1. Woong Son, Bang Chul Jung, Won-Yong Shin, and Yoan Shin, “Multi-Cell Pseudo-Random Beamforming: Opportunistic Feedback and Beam Selection,” ICTC, Oct. 2017 (Invited).
  2. Jun-Bae Seo, Hu Jin, and Bang Chul Jung, “Non-Orthogonal Random Access with Channel Inversion for 5G Networks,” ICTC, Oct. 2017.
  3. Xuelian Wu, Waqas Tariq Toor, Hu Jin, and Bang Chul Jung, “On CDF-Based Scheduling with Non-Uniform User Distribution in Multi-Cell Networks,” ICTC, Oct. 2017.
  4. Huifa Lin, Won-Yong Shin, and Bang Chul Jung, “Achieving Optimal Degrees of Freedom in Multi-Source Interfering Relay Networks With Multiple Antennas,” IEEE Vehicular Technology Society Asia Pacific Wireless Communications Symposium, Aug. 2017.
  5. Bang Chul Jung, Jeonghong Park, Tae-Won Ban, Woongsup Lee, and Jong Min Kim, “Full-Duplex Generalized Spatial Modulation: A Compressed Sensing-Based Signal Detection,” ICUFN, Jul. 2017.
  6. Eunmi Chu, Jae Sook Yoo, and Bang Chul Jung, “Spatial-Modulated Physical-Layer Network Coding in Two-Way Relay Networks with Convolutional Codes,” ICUFN, Jul. 2017.
  7. Huifa Lin, Won-Yong Shin, and Bang Chul Jung, “Multi-Stream Opportunistic Network Decoupling with Virtual Full-Duplex Operation,” IEEE ISIT, Jun. 2017.
  8. Hyunwoo Nam and Bang Chul Jung, “Trade-off between Spectral Efficiency and Energy Efficiency in Multi-Cell Uplink Networks,” ICACT, Feb. 2017.

 

2016

  1. Jeonghong Park, Bang Chul Jung, Tae-Won Ban, and Jong Min Kim, “Signal Detection with Parallel Orthogonal Matching Pursuit in Multi-User Spatial Modulation Systems,” ICUFN, Jul. 2016 (Invited Paper).
  2. Hu Jin, Bang Chul Jung, and Won-Yong Shin, “On the Secrecy Capacity of Multi-Cell Uplink Networks with Opportunistic Scheduling,” IEEE ICC, May 2016.

 

2015

  1. Hu Jin, Bang Chul Jung, Jinhyung Oh, and Myung Sun Song, “A Distributed Interference Management for Crowded WLANs: Opportunistic Interference Alignment,” IEEE VTC2015-Fall, Sep. 2015.
  2. Sang-Woon Jeon, and Bang Chul Jung, “Opportunistic In-Network Computation for Wirelesss Sensor Networks,” IEEE ISIT, Jun. 2015.
  3. Moon-Je Cho, Tae-Won Ban, Bang Chul Jung, and Hyun Jong Yang, “A Distributed Scheduling with Interference-Aware Power Control for Ultra-Dense Networks,” IEEE ICC, Jun. 2015.
  4. Seong Ho Chae, Bang Chul Jung, and Wan Choi, “Achievable Degrees-of-Freedom of (n,K)-user Interference Channel with Distributed Beamforming,”IEEE ICASSP, Apr. 2015.

 

2014

  1. Hyun Jong Yang, Byeong Su Lee, and Bang Chul Jung, “Buffer-Aided Two-Way Relaying with Lattice Codes,” ICTC, Oct. 2014 (Invited Paper).
  2. Bang Chul Jung, Su Min Kim, Hyun Jong Yang, and Won-Yong Shin, “On the Joint Design of Beamforming and User Scheduling in Multi-Cell MIMO Uplink Networks,” IEEE PIMRC 2014, Sep. 2014.
  3. Hyun Jong Yang, Won-Yong Shin, Bang Chul Jung, Changho Suh, and Arogyaswami Paulraj, “Opportunistic Downlink Interference Alignment,” IEEE ISIT 2014, Jul. 2014.
  4. Bang Chul Jung, Yong-Up Jang, Min Suk Kang, and Tae-Won Ban, “A Practical Multi-Packet Reception Technique with Joint Detection for Wireless Ad Hoc Networks,” ICFICE 2014, Jun. 2014.
  5. Hu Jin, Bang Chul Jung, and Victor C. M. Leung, “On the CDF-Based Scheduling for Multi-Cell Uplink Networks,” IEEE ICC 2014, Jun. 2014.
  6. Won-Yong Shin, Hyung Jong Yang, and Bang Chul Jung, “Opportunistic Network Decoupling in Multi-Source Interfering Relay Networks,” IEEE ICC 2014, Jun. 2014.
  7. Hyung Jong Yang, Won-Yong Shin, Bang Chul Jung, and Changho Suh, “Opportunistic Interference Alignment for Interfering Broadcast Channels,” IEEE ICASSP 2014, May 2014.
  8. Hyung Jong Yang, Bang Chul Jung, Won-Yong Shin, and Arogyaswami Paulraj, “The Design of Optimal Receiver for Opportunistic Interference Alignment,” IEEE ICASSP 2014, May 2014.

 

2013

  1. Sung Hwan Kim and Bang Chul Jung, “On the Joint Power and Rate Optimization in Multihop Relay Networks with HARQ,” IEEE PIMRC 2013, Sep. 2013.
  2. Kap Seok Ko, Bang Chul Jung, and Dan Keun Sung, “On the Energy Efficiency of Wireless Random Access Networks with Multi-Packet Reception,” IEEE PIMRC 2013, Sep. 2013.
  3. Bang Chul Jung and Woohyuk Chang, “A Message Passing Algorithm for Compressed Sensing in Wireless Random Access Networks,” Asia Pacific Conference on Communications (APCC) 2013, Aug. 2013.
  4. Won-Yong Shin, Hyun Jong Yang, and Bang Chul Jung, “Opportunistic Relay Selection Based on Interference Nulling in the K×N×K Channel with Interfering Relays,” IEEE ISIT 2013, Jul. 2013.
  5. Bang Chul Jung, Tae Won Ban, and Kil-Young Sung, “Practical Signal Models for Orthogonal Code Hopping Multiplexing Systems,” ICFICE 2013, Jun. 2013.
  6. Su Min Kim, Bang Chul Jung, and Dan Keun Sung, “On the Link Adaptation and User Scheduling with HARQ in the Presence of Inter-Cell Interference,” IEEE ICC 2013, Jun. 2013.
  7. Hu Jin, Bang Chul Jung, Victor C. M. Leung, “A Novel Feedback Reduction Technique for Cellular Downlink with CDF-Based Scheduling,” IEEE ICC 2013, Jun. 2013.
  8. Seong Ho Chae, Bang Chul Jung, and Wan Choi, “Achievable Degrees-of-Freedom by Distributed Scheduling in an (n,K)-user Interference Channel,” IEEE ICC 2013, Jun. 2013.

 

2012

  1. Hyun Jong Yang, Won-Yong Shin, Bang Chul Jung, and Arogyaswami Paulraj, “A Feasibility Study on Opportunistic Interference Alignment: Limited Feedback and Sum-Rate Enhancement,” Asiloma Conference on Signals, Systems, and Computers, Nov. 2012.
  2. Su Min Kim, Bang Chul Jung, Wan Choi, and Dan Keun Sung, “Joint Rate Adaptation and User Scheduling in HARQ-Based Multi-User Systems with Heterogeneous Mobility,” IEEE ISCIT 2012, Oct. 2012.
  3. Won-Yong Shin, Koji Ishibashi, and Bang Chul Jung, “Large-Scale Ultra Wide-Band Ad Hoc Networks,” Triangle Symposium on Advanced ICT 2012, Sep. 2012.
  4. Hyun Jong Yang, Won-Yong Shin, Bang Chul Jung, and Arogyaswami Paulraj, “Opportunistic Interference Alignment for MIMO IMAC: Effect of User Scaling Over Degree-of-Freedom,” IEEE ISIT 2012, pp. 2646-2450, Jul. 2012.
  5. Jiyoung Cha, Hu Jin, Bang Chul Jung, and Dan Keun Sung, “Performance Comparison of Downlink User Multiplexing in IEEE 802.11ac: Multi-User MIMO vs. Frame Aggregation,” IEEE WCNC 2012, Apr. 2012.

 

2011

  1. Sang-Woon Jeon, Sung Hoon Lim, Bang Chul Jung, and Dae-Won Seo, “Opportunistic Noisy Network Coding for Fading Parallel Relay Networks,” IEEE GLOBECOM 2011, Dec. 2011.
  2. Seong-Ho Hur, Bang Chul Jung, and Bhaskar D. Rao, “Sum Rate Enhancement by Maximizing SGINR in an Opportunistic Interference Alignment,” Asiloma Conference on Signals, Systems, and Computers, pp. 354-358, Nov. 2011.
  3. Min Suk Kang and Bang Chul Jung, “Performance Analysis of Opportunistic CSMA Schemes in Cognitive Radio Networks,” IEEE MTT-S IMWS 2011 – Invited Paper, Aug. 2011.
  4. Donghan Chee, Min Suk Kang, Howon Lee, and Bang Chul Jung, “A Study on the Green Cellular Network with Femtocells,” ICUFN 2011, pp. 235-240, Jun. 2011.
  5. Sungro Yoon, Injong Rhee, Bang Chul Jung, Babak Daneshrad, and Jae H. Kim, “Contrabass: Concurrent Transmissions without Coordination for Ad Hoc Networks,” IEEE INFOCOM 2011, pp. 1134-1142, Apr. 2011.

 

2010

  1. Bang Chul Jung, Dohyung Park, and Won-Yong Shin, “A Study on the Optimal Degrees-of-Freedom of Uplink Cellular Network: Opportunistic Interference Management,” Asiloma Conference on Signals, Systems, and Computers, pp. 2067-2071, Nov. 2010.
  2. Jae Jeung Kim, Jinhyun Ahn, Dongwon Lee and Bang Chul Jung, “Ontology Based Information Distribution in the Pervasive Display Environment,” IEEE PERCOM Workshops, Apr. 2010.
  3. Kyuho Son, Bang Chul Jung, Song Chong and Dan Keun Sung, “Power Allocation for OFDM-Based Cognitive Radio Systems Under Outage Constraints,” IEEE ICC 2010, May 2010.
  4. Min Suk Kang and Bang Chul Jung, “A Cognitive p-Persistent CSMA Scheme for Spectrum Sharing Based Cognitive Radio Networks,” IEEE WCNC 2010, Mar. 2010.

 

2009

  1. Kyuho Son, Bang Chul Jung, Song Chong and Dan Keun Sung, “Opportunistic Underay Transmission in Multi-carrier Cognitive Radio Systems,” IEEE WCNC ’09, Mar. 2009.
  2. Hu Jin, Bang Chul Jung, Ho Young Hwang and Dan Keun Sung, “A Throughput Balance Problem between Uplink and Downlink in Multi-user MIMO-based WLAN Systems,” IEEE WCNC ’09, Mar. 2009.
  3. Min Suk Kang and Bang Chul Jung, “Decentralized Inter-cell Interference Coordination in Uplink Cellular Networks Using Adaptive Sub-band Exclusion,” IEEE WCNC ’09, Mar. 2009.

 

2008

  1. Tae Won Ban, Wan Choi, Bang Chul Jung, and Dan Keun Sung, “Capacity Analysis of Opportunistic Scheduling System in a Spectrum Sharing Environment,” IEEE GLOBECOM 2008, Nov. 2008.
  2. Hyun Jong Yang, Bang Chul Jung, and Joohwan Chun, “Zero-Forcing Based Two-Phase Relaying with Multiple Mobile Stations,” Asiloma Conference on Signals, Systems, and Computers, Oct. 2008.
  3. Hu Jin, Bang Chul Jung, Ho Young Hwang, and Dan Keun Sung, “Performance Comparion of Uplink WLANs with Single-User MIMO and Multi-User MIMO Schemes,” IEEE WCNC ’08, pp. 1854-1859, Mar. 2008.

 

2007

  1. Bang Chul Jung, Tae Won Ban, Wan Choi, and Dan Keun Sung, “Capacity Analysis of Simple and Opportunistic Feedback Schemes in OFDMA Systems,” IEEE ISCIT ’07, pp. 203-205, Oct. 2007.
  2. Seonghwan Kim, Bang Chul Jung, and Dan Keun Sung, “Effect of Other Cell Interference on Multiuser Diversity in Cellular Networks,” IEEE ISCIT ’07, pp. 521-525, Oct. 2007.
  3. Min Suk Kang, Bang Chul Jung, and Dan Keun Sung, “Performance Analysis of Four Different Downlink Relaying Schemes in Cellular Systems,” IEEE ISCIT ’07, pp. 511-516, Oct. 2007.
  4. Sung Soo Cho, Jong Woon Lyu, Bang Chul Jung, Dan Keun Sung, and Soonuk Seol, “Effecitve Exchange of Real-Time Location Information Packet in an Integrated Voice/Data Ad-hoc Network based on MIL-STD-188-220C Standard,” IEEE MILCOM ’07, Oct. 2007.
  5. Tae Won Ban, Bang Chul Jung, Wan Choi, and Dan Keun Sung, “Performance Analysis of Two Relay Selection Schemes for Cooperative Diversity,” IEEE PIMRC ’07, Sep. 2007.
  6. Su Min Kim, Bang Chul Jung, Jo Woon Chong, Chang Yong Jung, and Dan Keun Sung, “Capacity Analysis of a TH-PPM UWB System Using a Near-Interfernce Erasure Scheme in Multi-User Environments,” IEEE PIMRC ’07, Sep. 2007.
  7. Bang Chul Jung, Young Jun Hong, Dan Keun Sung, and Sae-Young Chung, “Adaptive Sub-bands Nulling for OFDM-Based Wireless Communication Systems,” IEEE WCNC ’07, pp.1491-1495, Mar. 2007.
  8. Chong Woon Lyu, Bang Chul Jung, Sung Ho Moon, and Dan Keun Sung, “Distance-Based Code-Collision Control Scheme Using Erasure Decoding in Orthogonal Code Hopping Multiplexing,” International Conference on Advanced Communication Technology (ICACT 2007), pp. 1053-1057, Feb. 2007.

 

2006

  1. Sung Soo Cho, Bang Chul Jung, and Dan Keun Sung, “Capacity Analysis of Downlink CDMA Systems with Quasi-Orthogonal Sequences,” IEEE GLOBECOM 2006, Nov. 2006.
  2. Bang Chul Jung, Sung Soo Cho, and Dan Keun Sung, “Downlink Capacity Improvement Through Orthogonal Code Hopping Multiplexing and Multiple Scrambling Codes,” IEEE GLOBECOM 2006, Nov. 2006.
  3. Min Jeong Kim, Bang Chul Jung, Jo Woon Chong, and Dan Keun Sung, “Performance Enhancement of a TH-PPM UWB System Using a Near-Interference Erasure Scheme in Multi-User Environments,” IEEE International Conference on Ultra-Wideband (ICUWB), pp. 399 – 404, Sep. 2006.
  4. Bang Chul Jung, Hu Jin, Dan Keun Sung, and Sae-Young Chung, “Performance Analysis of Orthogonal Code Hopping Multiplexing Systems,” IEEE ICC 2006, pp. 2078 – 2082, Jun. 2006.

 

2005

  1. Jo Woon Chong, Bang Chul Jung, Jae Hoon Chung, and Dan Keun Sung, “Statistical Multiplexing Based Hybrid FH-OFDMA System for OFDM-Based UWB Indoor Radio Access Networks,” IEEE International Conference on Ultra-Wideband 2005(ICUWB 2005), pp. 695-699, Sep. 2005.
  2. Chang Yong Jung, Jo Woon Chong, Young Jun Hong, Bang Chul Jung, and Dan Keun Sung, “Orthogonal Time Hopping Multiple Access for UWB Impulse Radio Communications,” Asia Pacific Conference on Communications 2005 (APCC 2005), pp. 353-357, Oct. 2005.
  3. Bang Chul Jung and Dan Keun Sung, “Random FH-OFDMA System Based on Statistical Multiplexing,” IEEE VTC2005-Spring, Vol. 3, pp. 1793-1797, May 2005.

 

2004

  1. Bang Chul Jung, Jae Hoon Chung, and Dan Keun Sung, “Symbol Repetition and Power Re-allocation Scheme for Orthogonal Code Hopping Multiplexing Systems,” APCC/IEEE MDMC 2004, pp. 80-84, Sep. 2004.
  2. Seon Yeob Baek, Bang Chul Jung, Sung Ho Moon, Jae Hoon Chung, Chang Yong Jung, Dan Keun Sung, Hyung Uk Cho, and Jong Min Cheong, “1xEV-DO System-Level Simulator Based on Measured Link-Level Data,” IEEE VTC 2004-Fall, pp.4486-4490, Sep. 2004.

 

2003

  1. Bang Chul Jung, Jae Kyun Kwon, and Dan Keun Sung, “Determining the Optimum Threshold Values of MCS Levels for Retransmission Packets in HARQ Schemes,”IEEE VTC 2003-Spring, pp. 1935-1939, Apr. 2003.

 

2002

  1. Bang Chul Jung, Myung Hoon Sunwoo, and Sung Keun Oh, “A New Turbo-Coded OFDM System Using Orthogonal Code Multiplexing,”IEEE VTC 2002-Spring, pp. 1448-1452, May 2002.