Abstract of Special Research Report (RR-92)
National Institute of Occupational Safety and Health, Japan
Residual Stress Measurements in Butt-Welded Plates by X-Ray and Hole-Drilling Strain-Gage Methods
RR-92-1 |
Etsuji YOSHIHISA |
: Welding residual stresses are frequently of interest in fracture evaluations of structural components. Although some data are available on them in small-sized specimens, data for large sized plates, in particular with a comparison of different measurement methods, are scarce. |
Development of a General Purpose Structural Reliability Analysis Code Jointly Based on the AFOSM Method and the Monte Carlo Simulation with Importance Sampling
RR-92-2 |
Tetsuya SASAKI |
: With the increase of complex engineering systems, structural reliability has become a major consideration in the design of durable machines and structures. In general, structural reliability analysis requires the failure probability of the structural component. However, the exact solution of the failure probability requires the calculation of a multi-dimensional integral which often needs large memory and computing time. For this reason, the availability of a computer code for calculating the failure probability is important for practical use of reliability methods. |
Fundamental Research of Emergency Stop Mechanism for Power Press
RR-92-3 |
Shigeo UMEZAKI, Shoken SHIMIZU and Soichi KUMEKAWA |
: The half number of industrial accidents caused by power press operation occurs from the structural inappropriateness of positive clutch type presses in Japanese industries. The main fault of this type press is due to the fact that a slide cannot stop until it reaches to upper dead point. |
Structural Requisites of Actuator for Grouping Motion and Its Realization
RR-92-4 |
Hiroyasu IKEDA and Noboru SUGIMOTO |
: Normally, the kinetic control of robot actuators can be achieved by providing positional feedback control. In this positional feedback control of actuators, a positional deviation manages a large amount of energy output. Therefore, if a robot comes in contact with humans during groping motion, the positional deviation will be caused and, as a result, force corresponding to this positional deviation is imparted to targets including humans. As the robot touches targets during groping motion, the level of force imparted targets can not be assured of safety by only a touch sensor and a collision avoidance control. |
Safety Control Theory Based on the Logic of Safety --Energy Transmition of Safety Information--
RR-92-5 |
Noboru SUGIMOTO and Hiroyasu IKEDA |
: Safety control system, which is defined as the machine operation controlled according to safety confirmation information, is explained as an interlocking model that is so functioned that energy output from machine is permitted only while the information (safety information) reports safety. The information transmittion properties presented in this model are applied on all devices in the interlocking system, consistent from the sensor for producing safety information to devices for transmitting/outputting energy. Small energy level of signal signifying safety is normally produced in a pickup element in the sensor. Enormous power made by amplifying the energy of the safety signal is supplied to the machine to conduct its powerful operation. |
Evaluation of Noise Control for Impact-Machines for Construction Work
RR-92-6 |
Yoshiyuki EGAWA |
: It is well known that the noise emitted from various impact-machines for construction has a bad influence on machine operation by workers. It has been, therefore, generally carried out to decrease the noise for these impact-machines as the countermeasure of noise control. The noise of these machines consists of two components. One component is the noise which is caused by concrete crushing (hereinafter referred to as "crushing noise") and the other is the noise which is generated from machine's body by the vibration of hitting concrete (vibration noise). These noises emanate nearly at the same time, and the fluctuation of crushing noise for a variety of concrete hardness has a large effect on the vibration noise. |
Deformation Behavior at Failure of Saturated Cohesive Soil Model Grounds in Geotechnical Centrifuge Model Tests
RR-92-7 |
Noriyuki HORII, Satoshi TAMATE and Yasuo TOYOSAWA |
: In recent years, construction work has been increasing in number for the development of infrastructures such as water and sewage works. Excavation work is very common to construction work since most of the work have been performed on or under ground. For this reason, hazardous situations associated with slope failures during excavation work have been gradually increasing. In fact, many slope failure accidents have occurred in Japan every year. |
Safety Dimensions of Tread and Stairs in Considering Visual Perceptive Errors
RR-92-8 |
Hisao NAGATA |
: A man seldom looks intently at his feet during walking, except when he wants to avoid an obstacle or a muddy pool. Usually he walks rhythmically while looking at the road surface a few meters ahead. But, sometimes, man becomes absent-minded or distracted while walking, with the result that he stumbles over even small projections or falls down when he mistakenly presumes that there is another step. There are many cases of such kinds of accidents. When descending a stairway, he slows down the pace of his walk just before he takes his first step, in order to adjust his pace to the width of the steps of the staircase, and walk down at an even pace. If the staircase is sloped gently he can see the bottom of it while watching his downward target. However, if the staircase is steep, he can not see anything downward until he arrives at the top of it, so he finds it difficult to adjust his pace. In fact, there are many cases of accidents which occur around this spot. In this paper, relations of dimensions of tread and rise, and human peripheral vision in descending stairs, were theoretically analyzed. A theoretical method for obtaining the required dimensions of a tread was suggested. |
A study on the Time Intervals between Occupational Accidents (6)
RR-92-9 |
Shigeo HANAYASU |
: The accident frequency rate has been widely used as a measurement of safety performance in many undertakings over a long period of time. |
An Information Analysis by Statistical Method for the Descriptive Statements of the Occupational Accident Report Concerning Construction Work
RR-92-10 |
Yoshimi SUZUKI |
: In this study, driving a method for making practical and direct use of descriptive statements of the "Occupational Accident Report" concerning Construction Work, statistical analysis methods are applied to examine free-terms used in descriptive statements of theses reports. Especially, statistical quantification analytical method are applied to study free-terms selected from descriptive statements of the "Accident Situation and Circumstances". |
Relationship between Chemical Structure and Thermal Stability of Reactive Chemicals (3rd Report) --Thermal Decomposition of Nitrophenylhydrazine Isomers--
RR-92-11 |
Takayuki ANDO and Yasuhiro FUJIMOTO |
: In manufacturing, transporting, and storage of reactive chemicals in recent years, the hazard evaluations have been extremely important. In the chemical industry, the most concerns are focused on thermal hazards such as runaway reactions and thermal decompositions, which are mostly governed by thermodynamics and reaction kinetics of these reactive chemicals in the system. |
Prediction of Exothermic Onset-Temperature for Benzene Derivatives with Fuzzy Reasoning
RR-92-12 |
Yasuhiro FUJIMOTO |
: Evaluation of chemical hazard is important in the chemical industries because explosions or fires occasionally occur in chemical processes where fine-chemicals including Pharmaceuticals or functional resins are treated. If the evaluation of these chemical hazards is possible by easy calculation, this may save chemical industries money and time. Thermal hazards of chemical substances must be evaluated from the two aspects; sensitivity, which shows how easily chemicals may decompose or ignite, and severity, which shows how much or how fast energy is liberated when chemicals decompose. One of typical methods for the evaluation of thermal hazards is DSC, which gives information on the sensitivity (exothermic onset-temperature) and the severity (decomposition heat) at the same time with easy operation. This report consists of the results of prediction, which were obtained in our laboratory, of the exothermic onset-temperature of benzene derivatives with fuzzy reasoning, using the 141 DSC data. If this result could predict chemical hazards accurately enough, it might be used for the direct evaluation of thermal hazards from chemical structures which are easily known without any experiments. |
Laboratory Studies on Spontaneous Combustion of Coal Bed in Pulverizer
RR-92-13 |
Haruhiko ITAGAKI |
: Since the introduction of pulverized coal combustion systems for power plants in the mid-1930's, there has been a great concern about fire/explosion accidents due to coal dust in the pulverizer. Even for some years, the fire/explosion accident in the system has a tendency to increase. |
Ignition Hazards of Hydrogen-Air Mixture Caused by Spark Discharge with Switching in Radio Frequency Resistative Circuit
RR-92-14 |
Tatsuo MOTOYAMA |
: With a progress of electrical technologies, radio frequency circuits including high frequency components are applied to electrical installations. Some of them are used in hazardous locations where explosive or inflammable gases exist: as a result, ignitions of the gases may be induced by a spark discharge when the radio frequency circuits are switched on or off. However, experiments on their ignition hazards are scarcely carried out and problems of the ignition are often discussed to design the high frequency electrical installations used in hazardous area. |
Detoxification of Hazardous Gaseous Substances by Discharge Plasma --Decomposition of Aromatic Organic Solvents by Surface Discharge Plasma--
RR-92-15 |
Shigeo YAMAGUMA, Atsushi OHSAWA, Tsutomu KODAMA and Yasuyuki TABATA |
: There are a lot of industrial processes in which generation of hazardous gaseous substances such as solvent vapor, NOx and SOx, etc. are unavoidable. These substances are also known to cause environmental pollution and have been thought to be difficult to be sufficiently managed by conventional technologies based on heat burning, adsorption by active carbon, etc. |