Ralph W. Plummer

Manual Dexterity Evaluation of Gloves Used in Handling Hazardous Materials

The problems associated with hazardous materials control are numerous and complex. One of these problems involves selecting hand protection which will resist permeation for the duration of the exposure while maintaining sufficient levels of dexterity and tactility so that the worker can safely and efficiently perform the required task. This study investigated the effect of nine glove combinations on manual dexterity. These included three single glove and six double glove combinations plus the bare hand condition. The subjects performed a nut-bolt-washer assembly-dissassembly task using the Bennett Hand Tool Dexterity Test apparatus. The task required the use of a screw driver, two sizes of open-end wrenches, and an adjustable wrench, along with handling the bolt, nut, and washer while performing the assembly-disassembly task for three different bolt, nut, and washer sizes (1/2″, 5/16″, 1/4″). The response variables measured in the experiment were the time to complete each task and number of errors committed during each task. An error was defined as a drop of any of the items handled. The data was analyzed using a fixed effects randomized ANOVA model and the Duncans Multiple Range Test. An alpha level of 5 per cent was used in the analysis. The results of the analyses showed that gloves increased the average completion time by 15 to 37%. Several double gloving combinations had significantly longer task completion times compared to single gloves.

EVALUATION OF DRIVER COMPREHENSION OF WORD VERSUS SYMBOL HIGHWAY SIGNS

This experiment investigated the effects of word and symbol signs on reaction time and accuracy of response. In addition, a proposed symbol sign, “SCHOOL BUS STOP AHEAD,” was evaluated using the same criteria. A tachistoscope was used to present the visual stimuli for a viewing time of 200 milliseconds. Two sets of conditions were used in the experiment. The first part consisted of a group of subjects that possessed no prior knowledge of/or special education in symbol highway signs. The second part involved a control group who received special training concerning the meaning of symbol highway signs. The stimuli were presented to 20 subjects (both male and female) aged 19 to 45, whose driving experience ranged from 3 to 29 years. The average miles driven per year varied from 1,000 to 20,000 miles. A three factor analysis of variance fixed effect model was used to analyze the data. The main factors of the model consisted of two levels of stimuli (word versus symbol signs), two levels of test conditions (prior knowledge versus no knowledge), and ten levels of different signs (traffic signs). Based upon the analysis of variance results, it was found that symbol signs do convey more accurate identification of road information than do word signs. However, it was not possible to conclude that symbol signs require less time to react to than word signs. The results of this investigation confirmed that neither the word or symbol “SCHOOL BUS STOP AHEAD” sign effectively convey the proper message.

A Test-Retest Criterion for Isometric Strength Testing:

Isometric strength testing has commonly been used to evaluate human strength capability. Recently it has been proposed by NIOSh as a form of administrative control for injury prevention. Historically, the number of trials used for each person-test combination has been arbitrarily selected and is often undocumented. This paper proposes a criterion for isometric testing and reports some results from using this criterion.

Performance Evaluation of Experienced Headlamp Inspectors

This investigation evaluated the performance of six experienced inspectors of automobile headlamps. The study was conducted in the normal manufacturing environment by supplying the regular final inspection position with a controlled sample of headlamps. Two inspectors were selected from each of the three shifts. The inspectors independently inspected each sample lot. The independent variables of the experiment were sample defect levels (three levels), percent of shift completed (four levels), shift (three levels) and inspectors (six levels). Three sample lots of 100 lamps were developed for defect levels of 0%, 10%, and 20%. The tests were conducted after 20% of the inspectors shift had expired, then after 40%, 60%, and 80%. This was done to monitor inspector performance which was measured in terms of incorrectly rejected or accepted lamps to determine if fatigue or boredom effects were critical. The most striking result of the study showed that 72 percent of the lamps the inspectors rejected were good. This resulted from a combination of insufficient training, vague standards and inspector overloading.

A Methodology for Determining the Mineral Content and Particle Size Distribution of Airborne Coal Mine Dust

Abstract Exposure to airborne dust in coal mines has caused respiratory disease in coal miners. The causal agent in these diseases remains unknown, although the minerals found in and around the coal seam have been implicated. Toxicological studies designed to establish the effect of different mineral combinations and concentrations are lacking because the mineral content of coal mine dust has not been defined. This paper reports the initial results of a study done to characterize the mineral content of the coal mine dust found in a mine in the Upper Freeport seam in Northern West Virginia. Coal mine dust samples were collected using 4-stage cassette impactors at nine locations in the mine. The samples were analyzed by an x-ray microdiffraction film technique supplemented by energy dispersive scanning electron microscopy. Primary size modes of about 17 to 20 micrometers from the samples collected at the haulageway and the returnside of the continuous miner were found. From the returnside of the roof bolter...

ENVIRONMENTAL STRESSORS AS CAUSAL FACTORS FOR DRIVER FATIGUE

The purpose of the investigation was to evaluate the relative effects of a moderate or suboptimal level of environmental heat and noise stress on individuals by utilizing performance and nonperformance parameters. Twenty-five male undergraduate and graduate students attending West Virginia University volunteered as subjects for this laboratory study. Each subject was isolated in a specially constructed chamber. Heat and noise were designated as the two independent variables used in the investigation. The effects of both variables on five dependent measures were evaluated for a nonstress condition and for a stress condition. Four physiological variables, which included heart rate, heart rate variability, galvanic skin response, and 17-hydroxycorticosteroid level were used to assess the level of psychophysiological arousal or activation attributed to the heat and noise stress. Task performance was measured in the form of reaction time to a visual stimulus. The data analyses revealed the influential effects of the two environmental test conditions. Relative to the nonstress condition, values for heart rate, heart rate variability, galvanic skin response, and 17-hydroxycorticosteroid level were significantly greater for the stress condition. Continuous exposure to the stress condition precipitated an increase in the level of psychophysiological arousal. Reaction times to the visual display were significantly greater for the stress condition than for the nonstress condition. The decrement in task performance occurred cumulatively over the duration of the experiment.

Case study: ergonomic and hazard evaluation of a new consumer product

The introduction of a new, powerful, mechanical home-use tool carries with it a high risk of product liability. This liability stems from both planned and unanticipated use of the product. In view of this, it is imperative that designers and manufacturers carefully analyze their proposed product to insure that possible failures and hazards have been evaluated and corrected, that current ergonomic principles have been used in the design, that instructions and warning signs clearly document the hazards associated with use of the product, and that the advertising describe only safe methods of handling and using the product. This paper describes the analyses that were performed on a tool prior to its production. The purpose of the analyses was to identify and solve as many of the hazardous operating problems of the tool as possible. To this end, a series of system safety analyses was performed to define the user, user-machine interface, and mechanical problems associated with the ditcher-saw.

The Effect of Environmental Stresses on Human Fatigue

This Investigation evaluated the relative effects of a moderate or suboptimal level of environmental heat and noise stress on human stress and fatigue by utilizing performance and nonperformance parameters. Twenty-five male undergraduate and graduate students served as subjects for this investigation. Each subject was isolated in a specially constructed environmental chamber located in a laboratory. Heat and noise were designated as the two independent variables used in the study. The effects of both variables on three dependent measures were evaluated during a nonstress condition and a stress condition. Two physiological variables, heart rate and heart rate variability, were used to assess arousal effects of heat and noise stress. In addition, performance data was collected in the form of reaction time to a visual display. Analyses of physiological and performance data revealed the influential effects of the two environmental conditions tested. Heart rate and heart rate variability responses were found to be significantly higher in the moderate stress condition than in the nonstress condition. Furthermore, a statistically significant deterioration in performance was observed in the reaction time task. An increase in reaction time occurred when subjects were exposed to the moderate stress condition.

Strategies and struggles of incorporating acoustics in undergraduate curriculum

This paper relates the philosophy of the authors concerning the introducing of integration of basic acoustical principles into junior and senior level courses. The curriculum presents basic instruction in sound measurement, the effects of noise on human performance, and acoustical control in a junior level course and reinforces these concepts plus additional instruction in acoustics in a senior level course. The paper explains the strategy and reasoning of this approach, relating both strengths and weaknesses.

Isometric Strength Test Consistency over Time

Workmens Compensation costs have become a major financial burden on industry. A significant part of these costs are the result of musculoskeletal injuries. One method of controlling these injuries is matching employees to jobs based on strength. Isometric strength testing has been shown to be an effective method of matching employee strength capability to job strength requirements. The use of screening test raises the question of test-retest consistency. This study was designed to determine the consistency of isometric strength test results over time. Thirteen student volunteer subjects (10m, 3F) participated in a testing protocol consisting of five strength tests performed a minimum of two times each at two week intervals. Four test sessions were held. An analysis of variance was used to identify week to week strength differences in the test population. Each of the five tests was analyzed separately and no significant week to week strength differences were found. This result further supports the validity of using isometric strength testing as a selection tool.