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Masahiro Yamamoto,Etsuko Kusukawa 대한산업공학회 2018 Industrial Engineeering & Management Systems Vol.17 No.4
For product sales under a dual channel (DC) comprising a retail channel (RC) and a direct online channel(DOC), it is necessary to consider customers’ purchasing behaviors and preferences. This paper proposes the optimalsales strategy for DC under the situation where customer purchasing preference is unknown. This paper discussesthree types of customers: (i) customers who prefer purchasing a single type of products in RC, (ii) customers who preferpurchasing them in DOC, (iii) indecisive customers who purchase in either RC or DOC. A retailer runs RC anddetermines the optimal retail price. A manufacturer runs DOC and determines the optimal direct online price. Thispaper assumes that each channel faces price-dependent demand. Two sales strategies are compared: the cooperatedsales strategy (COSS) and the competed sales strategy (CMSS). Under COSS, a retailer and a manufacturer determinetheir prices cooperatively. Under CMSS, they determine their prices competitively. Using numerical examples, how(i) the uncertainty in customer purchasing preference, (ii) the existence ratio of indecisive customers, (iii) the sensitivityof demand by the difference between the retail price and the direct online price and (iv) the decrease ratio of theproduct demand for the increase in price, affect the optimal decisions under COSS and CMSS.
Program for Calculating the Extreme Value Statistics on the Spreadsheets Software(EVAN-II)
Yamamoto, Masahiro,Shibata, Toshio 한국부식방식학회 2002 Corrosion Science and Technology Vol.31 No.3
The extreme value statistics is widely used for predicting the lives of the various structures and the industrial plants in JAPAN. The program named EVAN, calculating the extreme value statistics, had been developed and sold by JSCE from 1989. However, a long time has passed through the development and it did not match a recent computer generation. And it was restricted only in Japanese language. So, a new program (EVAN-Ⅱ) was developed. Since the program was arranged for a corrosion engineer to calculate extreme value statistics easily, generally used spreadsheet software Excel™ was chosen for the developing platform. Gumbel distribution and GEV (Generalized Extreme Value) distribution are prepared for the extreme value analysis. Both MVLUE (Minimum Variance Linear Unbiased Estimator) method and MLH (Maximum Likelihood) method are applied to calculate the parameters for Gumbel distribution. The prediction of the extreme value of the total population can be carried out using return period. GEV distribution is so-called generalized these three extreme value distribution, such as Gumbel, Weibull and Frechet distribution. The shape parameter (k) of GEV distribution determines a type of distribution among them. If k is nearly equal to zero, GEV distribution is equivalent to Gumbel distribution. Thus, a test of this hypothesis indicates the fitness criterion for Gumbel distribution.
Design Exploration of High-Lift Airfoil Using Kriging Model and Data Mining Technique
Masahiro Kanazaki,Kazuomi Yamamoto,Kentaro Tanaka,Shinkyu Jeong 한국항공우주학회 2007 International Journal of Aeronautical and Space Sc Vol.8 No.2
A multi-objective design exploration for a three-element airfoil consisted of a slat, a main wing, and a flap was carried out. The lift curve improvement is important to design high-lift system, thus design has to be performed with considered multi-angle. The objective functions considered here are to maximize the lift coefficient at landing and near stall conditions simultaneously. Kriging surrogate model which was constructed based on several sample designs is introduced. The solution space was explored based on the maximization of Expected Improvement (EI) value corresponding to objective functions on the Krigingmodels. The improvement of the model and the exploration of the optimum can be advanced at the same time by maximizing EI value. In this study, a total of 90 sample points are evaluated using the Reynolds averaged Navier-Stokes simulation (RANS) for the construction of the Kriging model. In order to obtain the information of the design space, two data mining techniques are applied to design result. One is functional Analysis of Variance (ANOVA) which can show quantitative information and the other is Self-Organizing Map (SOM) which can show qualitative information.
AEGIS: AN ADVANCED LATTICE PHYSICS CODE FOR LIGHT WATER REACTOR ANALYSES
Yamamoto, Akio,Endo, Tomohiro,Tabuchi, Masato,Sugimura, Naoki,Ushio, Tadashi,Mori, Masaaki,Tatsumi, Masahiro,Ohoka, Yasunori Korean Nuclear Society 2010 Nuclear Engineering and Technology Vol.42 No.5
AEGIS is a lattice physics code incorporating the latest advances in lattice physics computation, innovative calculation models and efficient numerical algorithms and is mainly used for light water reactor analyses. Though the primary objective of the AEGIS code is the preparation of a cross section set for SCOPE2 that is a three-dimensional pin-by-pin core analysis code, the AEGIS code can handle not only a fuel assembly but also multi-assemblies and a whole core geometry in two-dimensional geometry. The present paper summarizes the major calculation models and part of the verification/validation efforts related to the AEGIS code.
Yamamoto Tomohiko,Kato Atsushi,Hayakawa Masato,Shimoyama Kazuhito,Ara Kuniaki,Hatakeyama Nozomu,Yamauchi Kanau,Eda Yuhei,Yui Masahiro 한국원자력학회 2024 Nuclear Engineering and Technology Vol.56 No.3
In a secondary cooling system of a sodium-cooled fast reactor (SFR), rapid detection of hydrogen due to sodiumwater reaction (SWR) caused by water leakage from a heat exchanger tube of a steam generator (SG) is important in terms of safety and property protection of the SFR. For hydrogen detection, the hydrogen detectors using atomic transmission phenomenon of hydrogen within Ni-membrane were used in Japanese proto-type SFR “Monju”. However, during the plant operation, detection signals of water leakage were observed even in the situation without SWR concerning temperature up and down in the cooling system. For this reason, the study of a new hydrogen detector has been carried out to improve stability, accuracy and reliability. In this research, the authors focus on the difference in composition of hydrogen and the difference between the background hydrogen under normal plant operation and the one generated by SWR and theoretically estimate the hydrogen behavior in liquid sodium by using ultra-accelerated quantum chemical molecular dynamics (UA-QCMD). Based on the estimation, dissolved H or NaH, rather than molecular hydrogen (H2), is the predominant form of the background hydrogen in liquid sodium in terms of energetical stability. On the other hand, it was found that hydrogen molecules produced by the sodium-water reaction can exist stably as a form of a fine bubble concerning some confinement mechanism such as a NaH layer on their surface. At the same time, we observed experimentally that the fine H2 bubbles exist stably in the liquid sodium, longer than previously expected. This paper describes the comparison between the theoretical estimation and experimental results based on hydrogen form in sodium in the development of the new hydrogen detector in Japan.
Effect of Back Pressure on Droplet Size Near Diesel Injector Nozzle
( Shohei Yamamoto ),( Daisaku Sakaguchi ),( Hironobu Ueki ),( Masahiro Ishida ) 한국액체미립화학회 2010 한국액체미립화학회 학술강연회 논문집 Vol.2010 No.-
A laser 2-focus velocimeter (L2F) with a micro-scale probe was used for measurements of the velocity and size of droplets in diesel sprays. The diameter of the nozzle orifice was 0.113 mm. The injection pressure was set at 40, 80, and 120 MPa by using a common rail system and the ambient pressure was set at 0.1 to 3.0 MPa. The focusing lens of the L2F was set inside a constant volume vessel, and a measurement position was located at 15 mm from the nozzle exit. It was confirmed that no droplet was observed by the L2F before the spray tip reached the measurement position in a high ambient pressure condition. The effect of the ambient pressure on the droplet velocity was found to be small in the near nozzle region. The droplet size decreased when the ambient pressure increased from 0.1 to 1.0 MPa. The droplet size increased when the ambient pressure equal to or increased higher than 2.0 MPa. These tendencies were verified by the KIVA-3V simulation.
Design Exploration of High-Lift Airfoil Using Kriging Model and Data Mining Technique
Kanazaki, Masahiro,Yamamoto, Kazuomi,Tanaka, Kentaro,Jeong, Shin-Kyu The Korean Society for Aeronautical and Space Scie 2007 International Journal of Aeronautical and Space Sc Vol.8 No.2
A multi-objective design exploration for a three-element airfoil consisted of a slat, a main wing, and a flap was carried out. The lift curve improvement is important to design high-lift system, thus design has to be performed with considered multi-angle. The objective functions considered here are to maximize the lift coefficient at landing and near stall conditions simultaneously. Kriging surrogate model which was constructed based on several sample designs is introduced. The solution space was explored based on the maximization of Expected Improvement (EI) value corresponding to objective functions on the Krigingmodels. The improvement of the model and the exploration of the optimum can be advanced at the same time by maximizing EI value. In this study, a total of 90 sample points are evaluated using the Reynolds averaged Navier-Stokes simulation(RANS) for the construction of the Kriging model. In order to obtain the information of the design space, two data mining techniques are applied to design result. One is functional Analysis of Variance(ANOVA) which can show quantitative information and the other is Self-Organizing Map(SOM) which can show qualitative information.
AEGIS: AN ADVANCED LATTICE PHYSICS CODE FOR LIGHTWATER REACTOR ANALYSES
AKIO YAMAMOTO,TOMOHIRO ENDO,MASATO TABUCHI,NAOKI SUGIMURA,TADASHI USHIO,MASAAKI MORI,MASAHIRO TATSUMI,YASUNORI OHOKA 한국원자력학회 2010 Nuclear Engineering and Technology Vol.42 No.5
AEGIS is a lattice physics code incorporating the latest advances in lattice physics computation, innovative calculationmodels and efficient numerical algorithms and is mainly used for light water reactor analyses. Though the primary objectiveof the AEGIS code is the preparation of a cross section set for SCOPE2 that is a three-dimensional pin-by-pin core analysiscode, the AEGIS code can handle not only a fuel assembly but also multi-assemblies and a whole core geometry in two-dimensional geometry. The present paper summarizes the major calculation models and part of the verification/validationefforts related to the AEGIS code.