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RISS 인기검색어
- 검색키워드
- 저자 : Seiji Yamaoka (검색결과 6 건)
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Study on Minimum Time Maneuver Problem for High Maneuvering Missile
Seiji Yamaoka,Seiya Ueno 한국항공우주학회 2008 한국항공우주학회 학술발표회 논문집 Vol.- No.-
the authors have been studying an application of Multidisciplinary Design Optimization (MDO) to the future missiles. For the purpose, a new design procedure on guidance and control system is proposed in this paper. For the future missiles, high maneuvering and high responsiveness are required. Then, the authors have been studying on guidance and control system design of the missile that uses the useful side thruster method for the high maneuvering and high responsiveness in the future missile. The side thruster method has an independent gas generator. The maximum thrust does not depend on dynamic pressure and is enabled even in the low-speed region immediately after launching or the high altitude area. It is expected that this method is useful in high maneuvering and high responsiveness in the future missiles. It is assumed that the side thruster device can change the amplitude of thrust continuously in this paper. In our previous studies, we solved the minimum time problem with the open loop and calculated optimal solution. The optimum thrust is no bang-bang control, but intermediate value is also used. The numerical results verified the usefulness. In this paper, we propose the closed-loop control system which is calculated inputs in real time due to aim toward the guidance and control system of more realistic missiles, verified by simulation.
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Minimum-Time Guidance and Control Law for High Maneuvering Missile
Seiji Yamaoka,Seiya Ueno 한국항공우주학회 2009 International Journal of Aeronautical and Space Sc Vol.10 No.1
This paper deals with design procedure of online guidance and control law for future missiles that requires agile maneuverability. For the purpose, the missile with high powered side thruster is proposed. The guidance and control law for such missiles is discussed from a point of view of optimal control theory in this paper. Minimum time problem is solved for the approximated system. It is derived that bang-bang control is optimal input from the necessary conditions of optimal solution. Feedback guidance without iterative calculation is useful for actual systems. In this paper, multiple design point method is applied to design feedback gains and feed forward inputs of the guidance and control law. The numerical results show that the proposed guidance and control law has a high-performance for wide-ranging boundary conditions.
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Minimum-Time Guidance and Control Law for High Maneuvering Missile
Yamaoka, Seiji The Korean Society for Aeronautical and Space Scie 2009 International Journal of Aeronautical and Space Sc Vol.10 No.1
This paper deals with design procedure of online guidance and control law for future missiles that requires agile maneuverability. For the purpose, the missile with high powered side thruster is proposed. The guidance and control law for such missiles is discussed from a point of view of optimal control theory in this paper. Minimum time problem is solved for the approximated system. It is derived that bang- bang control is optimal input from the necessary conditions of optimal solution. Feedback guidance without iterative calculation is useful for actual systems. In this paper. multiple design point method is applied to design feedback gains and feed forward inputs of the guidance and control law. The numerical results show that the proposed guidance and control law has a high -performance for wide-ranging boundary conditions.
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Real-Time Guidance Law for Quasi-Minimum Time Maneuver for a Missile
Seiya Ueno,Seiji Yamaoka 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8
Minimum time guidance is often required to real systems. However, optimal control problem is not solved inthe guidance system because of computational load. This paper proposed one design procedure for minimum time guidance law using multiple design points. The results show that the guidance law satisfies the design criteria, but the guidance law is solution at a local minimum point. The improvement on design criteria is necessary.
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Virulence Genes of Helicobacter pylori in Gastritis, Peptic Ulcer and Gastric Cancer in Laos
Vannarath, Sengdao,Vilaichone, Ratha-Korn,Rasachak, Bouachanh,Mairiang, Pisaln,Yamaoka, Yoshio,Shiota, Seiji,Binh, Tran Thanh,Mahachai, Varocha Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.20
Background: Helicobacter pylori (H. pylori) infection is an established cause of peptic ulcers and gastric cancer. The aim of this study was to identify H. pylori genotypes and to examine their associations with geographical regions and gastritis, peptic ulcers and gastric cancer in Laos. Materials and Methods: A total of 329 Lao dyspeptic patients who underwent gastroscopy at Mahosot Hospital, Vientiane, Laos during December 2010 - March 2012 were enrolled. Two biopsy specimens (one each from the antrum and corpus) were obtained for CLO testing and only CLO test-positive gastric tissue were used to extract DNA. PCR and sequencing were identified for variants of the cagA and vacA genotypes. Results: Some 119 Laos patients (36.2%) were found to be infected with H. pylori including 83 with gastritis, 13 with gastric ulcers (GU), 20 with duodenal ulcers (DU) and 3 with gastric cancer. cagA was detected in 99.2%. East-Asian-type cagA (62%) and vacA s1c (64.7%) were predominant genotypes in Laos. vacA s1c-m1b was significantly higher in GU than gastritis (53.8% vs. 24.1%; P-value=0.04) whereas vacA s1a-m2 was significantly higher in DU than gastritis (40.0% vs. 16.9%; P-value=0.03). East-Asian-type cagA and vacA s1c were significantly higher in highland than lowland Lao (100% vs. 55.8%; P-value=0.001 and 88.2% vs. 61.5%, P-value=0.03 respectively). Conclusions: H. pylori is a common infection in Laos, as in other countries in Southeast Asia. The cagA gene was demonstrated in nearly all Laos patients, cagA and vacA genotypes being possible important factors in explaining H. pylori infection and disease outcomes in Laos.
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Helicobacter pylori Infection and Gastric Mucosal Atrophy in Two Ethnic Groups in Nepal
Miftahussurur, Muhammad,Sharma, Rabi Prakash,Shrestha, Pradeep Krishna,Maharjan, Ramesh Kumar,Shiota, Seiji,Uchida, Tomohisa,Sato, Hiroki,Yamaoka, Yoshio Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.17
Serum anti-Helicobacter pylori antibodies and pepsinogens (PGs) have been used as gastric cancer screening and gastric mucosal status markers. Nepal is a low risk country for gastric cancer. However, the mountainous populace in the northern region culturally linked to Tibet as well as Bhutan, a neighboring country, have a high risk of GC. We collected gastric biopsy specimens and sera from 146 dyspeptic patients living in Kathmandu, Nepal. We also examined the sera of 80 volunteers living in the mountainous regions of the Himalayas. The optimal cut-off was calculated for serum biomarkers against the histology. Kathmandu patients (43.8%) were serologically positive for H. pylori infection, which was significantly lower than that for the mountainous (61.3%, P = 0.01). The same results also found in the prevalence of PG-positivity, PG I levels and PG I/II ratios (P = 0.001, P<0.0001 and P = 0.03, respectively). Moreover, the PG I/II ratios were significantly, and inversely correlated with the OLGA score (r = -0.33, P<0.009). The low incidence of gastric cancer in Nepal can be attributed to low gastric mucosal atrophy. However, the mountainous subjects have high-risk gastric mucosal status, which could be considered a high-risk population in Nepal.
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