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Makoto Kawai,Kenji Tateda,Yuma Ikeda,Ima Kosukegawa,Satoshi Nagoya,Masaki Katayose 대한고관절학회 2022 Hip and Pelvis Vol.34 No.1
Purpose: The aim of this study was to evaluate the short-term outcome of physiotherapy in patients with acetabular labral tears and to assess the effectiveness of physiotherapy according to the severity of the labral tear. Materials and Methods: Thirty-five patients who underwent physiotherapy for treatment of symptomatic acetabular labral tears were enrolled. We evaluated the severity of the acetabular labral tears, which were classified based on the Czerny classification system using 3-T MRI. Clinical findings of microinstability and extraarticular pathologies of the hip joint were also examined. The International Hip Outcome Tool 12 (iHOT12) was use for evaluation of outcome scores pre- and post-intervention. Results: The mean iHOT12 score showed significant improvement from 44.0 to 73.6 in 4.7 months. Compared with pre-intervention scores, significantly higher post-intervention iHOT12 scores were observed for Czerny stages I and II tears (all P<0.01). However, no significant difference was observed between pre-intervention and post-intervention iHOT12 scores for stage III tears (P=0.061). In addition, seven patients (20.0%) had positive microinstability findings and 22 patients (62.9%) had findings of extra-articular pathologies. Of the 35 patients, eight patients (22.9%) underwent surgical treatment after failure of conservative management; four of these patients had Czerny stage III tears. Conclusion: The iHOT12 score of patients with acetabular labral tears was significantly improved by physiotherapy in the short-term period. Improvement of the clinical score by physiotherapy may be poor in patients with severe acetabular labral tears. Determining the severity of acetabular labral tears can be useful in determining treatment strategies.
A Synchronization Method for Synchronous CDMA Systems with GEO Satellites
Sakamoto, Takuya,Umehara, Daisuke,Kawai, Makoto 통신위성우주산업연구회 2001 Joint Conference on Satellite Communications Vol.2001 No.-
High-speed core networks with optical fibers are globally being installed. However, it is very difficult to access these core networks from rural districts such as remote places among mountains and solitary islands. Synchronous CDMA systems with GEO satellite links are very attractive to solve this problem, since such systems have wide service areas and are suitable for packet-based networks due to their statistically multiplexing effect. Furthermore, their statistically multiplexing effect leads to effective frequency and power efficiency. In synchronous CDMA systems, each transmitted signal from a fixed earth station must be controlled to be synchronized with each other. However, the broadband systems require extremely precise timing control. In this paper, we discuss synchronization methods and evaluate their timing accuracy for the broadband systems quantitatively. First, we point out defects of two fixed filter methods and a Kalman filter method. Then, we propose a new synchronization method, which is robust to random noise and trend components. As a result, we conclude that the proposed synchronization method can make it possible to synchronize lGchip/sec CDMA systems with GEO satellites.
Nakamura, Junichi,Makishima, Akihito,Umehara, Daisuke,Kawai, Makoto 통신위성우주산업연구회 2002 Joint Conference on Satellite Communications Vol.2002 No.-
TCP is generally used for data transmission on a geo-synchronous satellite link. It is known that the throughput increase corresponding to the increase of transmission speed can not be expected on a geo-synchronous satellite link since TCP was originally designed as a protocol for terrestrial cable networks. We established a computer simulation system and an experimental system using a Ka-band satellite to investigate the TCP performance on a high speed satellite communication link. This paper describes the throughput performances obtained by both systems using Window Scaling Option which is expected to improve the conventional TCP performances and shows the relationship between bit error rate and throughput.
Quasi-Synchronous CDMA Performances Using Orthogonal Cyclic Shift M-Sequences
Sugano, Kiminobu,Umehara, Daisuke,Morihiro, Yoshiteru,Kawai, Makoto 통신위성우주산업연구회 2003 Joint Conference on Satellite Communications Vol.2003 No.-
CDMA (Code Division Multiple Access) is one of the attractive multiple access schemes for satellite data communications. In terms of chip synchronization, CDMA can be classified into asynchronous, synchronous, and quasi-synchronous (QS) CDMA. In this paper, we propose the QS-CDMA using the orthogonal cyclic shift M-sequences for satellite data communications. We investigate the number of sequences which have zero cross-correlation property each other within the prescribed chip timing errors by computer simulation and show the results. Furthermore, we show the throughput performances of the QS-CDMA with the orthogonal cyclic shift M-sequences and then compare it with that of the synchronous CDMA.
An ATM-Based Multicast Intersatellite Routing for LEO Satellite Networks
Umehara, Daisuke,Ebiko, Keisuke,Kobayashi, Toshihito,Kawai, Makoto,Morihiro, Yoshiteru 통신위성우주산업연구회 2000 Joint Conference on Satellite Communications Vol.2000 No.-
Low Earth Orbit (LEO) satellite communication systems with InterSatellite Links (ISLs) are promising as a world-wide multimedia core network infrastructure. As satellites come to higher latitudes in polar orbit constellation, the degradation of ISL transmission quality becomes large because of ISL interference and relative angular velocity between satellites in adjacent orbits. This paper deals with the transmission quality of ISLs based on the general transmission model. We propose an ATM-based multicast routing approach with link weight which overcomes the degradation of transmission quality and show that this approach enhances transmission quality significantly by computer simulation.