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Measuring Multipath Error of a Pseudo Quasi-Zenith Satellite
Toshiaki Tsujii,Hiroshi Tomita,Yoshinori Okuno,Ivan Petrovski,Masahiro Asako,Kazuki Okano 한국항해항만학회 2006 한국항해항만학회 학술대회논문집 Vol.2 No.-
Japan has been investigating a new satellite based positioning system called Quasi-Zenith Satellite System (QZSS). Since the improvement of positioning availability in urban area is one of the most important advantages of the QZSS, multipath mitigation is a key factor for the QZSS positioning system. Therefore, Japan Aerospace Exploration Agency (JAXA) and GNSS Inc. have commenced the R&D of a pseudolite, which transmits the next-generation signal such as BOC(1,1), in order to evaluate the effect of multipath on the new signal. A prototype BOC pseudolite was developed in 2005, and ground tests showed a capability of generating proper pseudorange. Also, preliminary flight experiments using a pseudo quasi-zenith satellite, a helicopter on which the pseudolite is installed, were conducted in early 2006, and the BOC-type correlation function was monitored in real time.
Real-time Trajectory Optimization for Reducing Helicopter Noise Impact on the Ground
Hiroshi Ikaida,Takeshi Tsuchiya,Hirokazu Ishii,Yoshinori Okuno 한국항공우주학회 2008 한국항공우주학회 학술발표회 논문집 Vol.- No.-
The purpose of this study is to obtain optimal landing approaches of helicopters that reduce the ground noise impact. In a previous study, we verified that the flights following the pre-calculated optimal trajectories with using our own noise source model resulted in lower noise impact on the ground than nominal approach paths. Detailed examination of these flights experiments. however, revealed that there were some results that did not show the predicted noise reduction effects because of unexpected external disturbances. We therefore refined the algorithms to realize more practical real-time optimization. To confirm the validity and effectiveness of the proposed optimization techniques, flight experiments were conducted again. The results showed that the noise levels predicted by proposed noise models show reasonable agreement with the measured noise levels. Furthermore. the experiments demonstrated that following the real-time optimized trajectories could decrease the ground noise impact.
Otsuki Shuhei,Ikeda Kuniaki,Wakama Hitoshi,Okuno Nobuhiro,Okamoto Yoshinori,Okayoshi Tomohiro,Miyamoto Yuki,Neo Masashi 대한슬관절학회 2020 대한슬관절학회지 Vol.32 No.-
The purpose of the study was to determine the effect of cartilage degeneration at the patellofemoral joint on clinical outcomes after open wedge high tibial osteotomy and to investigate the predisposing factors for progressive patellofemoral cartilage degeneration.Seventy-two knees were evaluated on second-look arthroscopy in patients who opted for plate and screw removal at an average of 20.1 months after osteotomy. Cartilage degeneration at the patellofemoral joint was evaluated using the International Cartilage Repair Society grading system, with cases divided into progression and nonprogression groups. Radiographic parameters of the patellofemoral anatomy, knee range of motion, and clinical outcomes were evaluated from the preoperative baseline to the final follow up, on average 50 months after osteotomy. A contracture > 5° was considered a flexion contracture. Cartilage degeneration progressed in 31 knees, and preoperative knee flexion contracture was significantly associated with progressive degeneration ( P < 0.01). The Lysholm and Kujala scores were significantly lower in the progression group (87.9 and 85.3, respectively) than in the nonprogression group (91.6 and 93.6, respectively) ( P < 0.05). The odds ratio of the flexion contracture resulting in progression of patellofemoral cartilage degeneration was 4.63 (95% confidence interval, 1.77–12.1). No association was detected between progressive degeneration and age, sex, body mass index, Kellgren-Lawrence grade, or radiographic parameters. Flexion contracture may be associated with progression of cartilage degeneration at the patellofemoral joint and may negatively affect the clinical outcomes after open wedge, high tibial osteotomy.