SKFM Observation of Corrosion on SUS304 Stainless Steel

Masuda, Hiroyuki 한국부식방식학회 2002 Corrosion Science and Technology Vol.31 No.2

Super Kelvin force method (SKFM) which is one of AFM measurement method is very useful for corrosion study, because the surface morphology and potential distribution can be obtained at high accuracy. The most cases the atmospheric corrosion is accelerated by sea salt. The initial corrosion mechanism of steels by sea salt particles is not well known. In-situ observation of corrosion initiated fkom a small water droplet of MgCl₂ was done by SKFM and the mechanism of atmospheric corrosion is discussed. The test specimen used was a SUS304 stainless steel. SKFM measurement was done under the constant temperature (297± 0.5 K) and the relative humidity range of 40 to 50 %. The test specimen was dry-polished up to 0.32m roughness and droplets of MgCl₂ with diameter of 0.3 - 0.8 mm were attached on the specimen, then they were kept the condition mentioned above. The corrosion morphology can be divided into 2 types: 1. Corrosion progressed inside of specimen with corrosion product when the liquid layer of MgCl₂ was thin. 2. Corrosion progressed inside of specimen without corrosion product when the liquid layer of MgCl₂ was thick. The corrosion product is invisible when the liquid layer of MgCl₂ was thin. Potential of the part where the droplet is attached becomes more negative as the thickness of liquid layer increased after corrosion stasted. Enrichment of chloride ion occurred at corroding part and water is supplied by the deliquescence of metal chloride.

Study on Environmental Changes of River in the Suburban Area and Transition of Relations between Residents and River

Hiroyuki Kaga,Kumi Kawano,Yasuhiko Shimomura,Noboru Masuda Korean Institute of Landscape Architecture 2004 Journal of the Korean institute of landscape archi Vol.2 No.-

This study dealt with the Kogi River, located in Kaizuka City, Osaka, which has experienced different improvements from the upper through the lower regions, aimed at revealing temporal relations between residents and the river, as well as probing future problems and directions regarding the river in the suburban area, by conducting a survey of local residents. The result showed that, in the upper region where nature remains in its natural state and the good water quality has been maintained, the relations between the residents and the river continued until around 1965; meanwhile in the middle region the relations have been disappearing since about 1955, and in the lower region where the stream has been repeatedly rehabilitated since 1955, there are fewer involvements of the people with the river. It also revealed that the weaker the relations between people and the river became, the larger the number of residents, even in the upper region, who became concerned over the deteriorating river environment after about 1975, and that in the middle and lower areas, about a decade earlier than in the upper area, the number of those who were aware of the environmental deterioration began to increase. Consequently, with an eye to resuming the relations between people and the river in an suburban area, their future challenges would be the space improvements depending on the environmental characteristics of the area; for example, the recovery of grassy banks for the purpose of protection in the lower region; the preservation and maintenance of many waterside woods as well as the creation of open spaces utilizing the river banks in the middle area; and throughout the whole region, the establishment of a system in which the relations between man and the river can be passed down to future generations, by utilizing the local human resources including those who know the former river landscapes or about the playing in and around the river.

Monitoring and Scheduling Methods for MIMOFIFO Systems Utilizing Max-Plus Linear Representation

Hiroyuki Goto,Shiro Masuda 대한산업공학회 2008 Industrial Engineeering & Management Systems Vol.7 No.1

This paper proposes an approach to monitoring and scheduling methods for repetitive MIMO-FIFO DESs. We use max-plus algebra for modeling and formulation, known as an effective approach for controller design for this type of system. Because a certain type of linear equations in max-plus algebra can represent the system’s behavior, the principal concerns in past researches were how to solve the equations. However, the researches focused mainly on analyses of the relation between inputs and outputs of the system, which implies that the changes or the slacks of internal states were not clarified well. We first examine several properties of the corresponding state variables, which contribute to finding and tracing the float times in each process. Moreover, we provide a rescheduling method that can take into account delays or changes of the internal states. These methods would be useful in schedule control or progress management.

Model Predictive Control for Productions Systems Based on Max-plus Algebra

Hiroyuki Goto,Shiro Masuda,Kazuhiro Takeyasu,Takashi Amemiya 대한산업공학회 2002 Industrial Engineeering & Management Systems Vol.1 No.1

Derivation Algorithm of State-Space Equation for Production Systems Based on Max-Plus Algebra

Hiroyuki Goto,Shiro Masuda 대한산업공학회 2004 Industrial Engineeering & Management Systems Vol.3 No.1

Derivation Algorithm of State-Space Equation for Production Systems Based on Max-Plus Algebra

Goto, Hiroyuki,Masuda, Shiro Korean Institute of Industrial Engineers 2004 Industrial Engineeering & Management Systems Vol.3 No.1

This paper proposes a new algorithm for determining an optimal control input for production systems. In many production systems, completion time should be planned within the due dates by taking into account precedence constraints and processing times. To solve this problem, the max-plus algebra is an effective approach. The max-plus algebra is an algebraic system in which the max operation is addition and the plus operation is multiplication, and similar operation rules to conventional algebra are followed. Utilizing the max-plus algebra, constraints of the system are expressed in an analogous way to the state-space description in modern control theory. Nevertheless, the formulation of a system is currently performed manually, which is very inefficient when applied to practical systems. Hence, in this paper, we propose a new algorithm for deriving a state-space description and determining an optimal control input with several constraint matrices and parameter vectors. Furthermore, the effectiveness of this proposed algorithm is verified through execution examples.

Monitoring and Scheduling Methods for MIMO-FIFO Systems Utilizing Max-Plus Linear Representation

Goto, Hiroyuki,Masuda, Shiro Korean Institute of Industrial Engineers 2008 Industrial Engineeering & Management Systems Vol.7 No.1

This paper proposes an approach to monitoring and scheduling methods for repetitive MIMO-FIFO DESs. We use max-plus algebra for modeling and formulation, known as an effective approach for controller design for this type of system. Because a certain type of linear equations in max-plus algebra can represent the system's behavior, the principal concerns in past researches were how to solve the equations. However, the researches focused mainly on analyses of the relation between inputs and outputs of the system, which implies that the changes or the slacks of internal states were not clarified well. We first examine several properties of the corresponding state variables, which contribute to finding and tracing the float times in each process. Moreover, we provide a rescheduling method that can take into account delays or changes of the internal states. These methods would be useful in schedule control or progress management.

Mist CVD Growth of ZnO-Based Thin Films and Nanostructures

Toshiyuki Kawaharamura,Hiroyuki Nishinaka,Yudai Kamaka,Yoshio Masuda,Jian-Guo Lu,Shizuo Fujita 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.5

As a safe, simple, environmental-friendly, and cost-effective growth technique of oxide materials, we have developed the mist chemical vapor deposition method. To grow ZnO, a water and/or alcohol solution of zinc-compounds (for example, zinc acetate) is used as the source, and micronsized aerosol or mist particles formed by ultrasonic atomization are supplied to the reaction area with a carrier gas. The ZnO thin films grown on glass substrates exhibited c-axis orientation under the selected growth conditions. The transparency in the visible region was higher than 90 %, the room temperature photoluminescence showed near band edge emission without noticeable deep level emissions, and the surface root-mean-square roughness was 7.5 nm despite the polycrystalline structure. These results are satisfactory for optical applications. The minimum resistivity, however, by gallium doping was 1.1 × 10-3 Ωcm, which needs further progress by enlarging the grain size. The growth of other oxide thin films, for example, MgO and CdO, as well as ZnO nanorods was reported, suggesting potential of wide applications of this growth technique to various oxide thin films and nanostructures with the friendliness to environment.

Ion Selective Permeability of Rust Layers on Low Alloy Steels under the Chloride Ion Existence

Noda, Kazuhiko,Nishimura, Toshiyasu,Masuda, Hiroyuki,Kodama, Toshiaki 한국부식방식학회 2002 Corrosion Science and Technology Vol.31 No.1

The ion selective permeability of the rust on carbon steel and Fe-Co and Fe-Ni low alloy steel was investigated by measurement of membrane potential to evaluate the characteristics of the rust layer on low alloy steels. These steels were selected as testing materials because they were thought to be basic alloys of weathering steels for the use in coastal environments, A rust film was formed on two kinds of low alloy steels (Fe-Co and Fe-Ni steel) by corrosion cycle tests that imitated the atmospheric corrosion environment in the seashore. In the case of the carbon steel, the rust layer on it had anion selective permeability. On the other hand, in spite of the rust layer on the carbon steel was anion selective, it was found out that the permeability changed to the cation selective by the result of determining the membrane potential of the rust on Fe -Co low alloy steel. The addition of a few Co was effective for decreasing the corrosion rate, because the rust layer of the cation selective was obstructed the invasion of chloride. The addition of Ni was known to be effective in decreasing corrosion rate of steel, despite their anion selective nature in rust layer. Alternative mechanism other than ion selectivity is required for the explanation of inhibition by Ni. The tendency of the membrane potential measurement of rust layers on all samples formed by corrosion cycle test was same as the case of rust films formed by exposure tests.

Numerical Simulation of a Premixed Flame in Three-Dimensional Turbulence

Manabu Hishida,Kazumichi Tanaka,Hiroyuki Oshie,Wataru Masuda 대한기계학회 1998 KSME/JSME THERMAL and FLUID Engineering Conference Vol.1 No.1