• Journal of the Ergonomics Society of Korea
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• v.31 no.6
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• pp.725-731
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• 2012

Objective: The aim of this study is to investigate visual feedback effects and human performance in the foot mouse control. Background: Generally, computer mouse tasks are controlled by visual feedback. In order to understand the characteristics of a foot mouse control, it is important to investigate the patterns of visual feedback involved in foot-mouse control tasks. Human performance of foot mouse control is also an important factor to understand the foot mouse control. Method: Three types of mouse control were determined to investigate visual feedback effects and human performance in the foot mouse control. Visual feedback effects in the foot mouse control were compared with those of a typical hand mouse. The cursor movement speed and mental workload were measured in the three types of tasks and two types of mouses. Results: Mouse control tasks with an element of homing-in to the target were more quickly performed by the hand mouse than the foot mouse. Mental workload was also higher in the foot mouse than the hand mouse. However, in the steering movement, human performance of the foot mouse control was not lower than that of the hand mouse control. Visual feedback in the foot mouse control was less required than in the hand mouse control. Conclusion: The foot mouse was not efficient in the most mouse control tasks, compared to the hand mouse. However, the foot mouse was efficient in the steering movement, moving a cursor within a path with lateral constraints. Application: The results of this study might help to develop the foot mouse.

• Journal of Navigation and Port Research
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• v.38 no.6
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• pp.615-621
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• 2014

VTS operators may suffer from acute, chronic, or traumatic stress caused by their workload and working environments associated with task or combination of task. This study intended to measure the level of VTS operator' stress and find out factors influencing it by understanding their characteristics during carrying out their task. For this purpose, analyzed the data collected through conducting survey on VTS operators as the Korea Occupational Stress(KOSS) and Psychological Well-being Index(PWI). As a result, VTS operators are experiencing higher level of psychological stress than the national average. And the factors to cause VTS operators' occupational stress can be summarized as follows; working environment factors, shift work especially night duty, workload, etc. This study provides the fundamental information for understanding human factors of VTS operator' occupational stress.

• Physical Therapy Korea
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• v.19 no.2
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• pp.69-79
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• 2012

Importance of the work-related musculoskeletal disorders (WMSDs) has been increasing in the hospital industry such as health care industry and financial industry. This study investigated in order to identify the factors like general, occupational and ergonomically characteristics of the subjects related to musculoskeletal disorders (MSDs) of physical therapists (PTs). Ergonomic tools of rapid upper limb assessment (RULA) were used for evaluation workload of the tasks. Prevalence of MSDs were 13 PTs (26.0%) for neck, 31 PTs (62.0%) for shoulder, 9 PTs (18.0%) for arm/elbow, 27 PTs (54.0%) for hand/wrist, 28 PTs (56.0%) for back, 14 PTs (28.0%) for leg/foot. The analysis of the rate of the pain intensity showed that 53.5% subjects experience moderate pain and 14.0% subjects experience severe pain. Factors which were general characteristics, for example, height, ergonomically characteristics such as 'Posture Score A' were related musculoskeletal subjective symptoms in logistic analysis (p<.05). Among physical therapists, action level of RULA were action level 2 (6.0%), action level 3 (52.0%), action level 4 (42.0%). Physical therapists were estimated one of the highest risk factor in this study. This study suggested that the need of preventive education and program for PTs (physical therapists). Comprehensive and systematic management plans should be established to include both ergonomic and sociopsychological aspects.

• Safety and Health at Work
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• v.10 no.1
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• pp.30-38
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• 2019

Background: Police officers' stress perception, frequency of stressful events (stressors), and police work characteristics may contribute to poor sleep quality through different mechanisms. Methods: We investigated associations of stress severity (measured by stress rating score) and frequency of stressors with sleep quality and examined the influence of police work characteristics including workload, police rank, prior military experience, and shift work on the associations. Participants were 356 police officers (256 men and 100 women) enrolled in the Buffalo Cardio-Metabolic Occupational Police Stress Study from 2004 to 2009. A mean stress rating score and mean frequency of stressors occurring in the past month were computed for each participant from the Spielberger Police Stress Survey data. Sleep quality was assessed using the global score derived from the Pittsburgh Sleep Quality Index survey. Linear associations of the stress rating score and frequency of stressors with sleep quality (Pittsburgh Sleep Quality Index global score) were tested. Age, sex, race/ethnicity, and smoking status were selected as potential confounders. Results: The stress rating score was positively and independently associated with poor sleep quality (${\beta}=0.17$, p = 0.002). Only workload significantly modified this association (${\beta}=0.23$, p = 0.001 for high workload group; p-interaction = 0.109). The frequency of stressors was positively and independently associated with poor sleep quality (${\beta}=0.13$, p = 0.025). Only police rank significantly modified the association (${\beta}=0.007$, p = 0.004 for detectives/other executives; p-interaction = 0.076). Conclusion: Both police officers' perception of stress severity and the frequency of stressors are associated with poor sleep quality. Stress coping or sleep promotion regimens may be more beneficial among police officers reporting high workloads.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.2
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• pp.32-38
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• 2006

A vehicle adaptive cruise control strategy based on human drivers' driving characteristics has been investigated. Human drivers driving characteristics have been analyzed using vehicle test data obtained from 125 participants. The control algorithm has been designed to incorporate the driving characteristics of the human drivers and to achieve natural vehicle behavior of the controlled vehicle that would reduce the workload of the human driver. Vehicle following characteristics of the cruise controlled vehicle have been compared to real-world driving radar sensor data of human drivers using a validated vehicle simulator. and compare nominal cruise control and adaptive cruise control.

• The Korean Journal of Nuclear Medicine Technology
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• v.14 no.2
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• pp.190-196
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• 2010

Purpose: This study was undertaken to investigate the feasibility of using automated liquid-handling systems equipped with reusable fixed tips in Radioimmunoassays and to demonstrate that the use of an automated pipetting instrument can decrease in the typical daily workload. Materials and Methods: The precisions of the automated pipettor and the manual pipettor were determined gravimetrically (n=30). A total of 30 specimens for HBs Ag were repeatedly pipetted (three replicates) with the automated pipettor and then retested. PSA samples were simultaneously pipetted with either the automated pipettor or the manual pipettor and then analyzed (n=40). Sample carryover test assessed for CA19-9, AFP and HCG when the automated pipettor was used. Pipetting speed of the automated pipettor and the manual pipettor were compared by evaluation of each workload. Results: The precisions coefficients of variation (CV) were 2.1% for the automated pipettor and 1.6% for manual pipettor. The mean cpm and CV for each group of replicates were 41,203 cpm and 3.7% for HBs Ag positive specimens, and 99 cpm and 7.9% for HBs Ag negative specimens, respectively. PSA results showed no significant differences between automated pipettor and manual pipettor (p=0.15, r=0.999). Carryover for CA19-9, AFP and HCG analytes was <0.1 ppm or below the assay limit of detection. Pipetting speed was significantly improved by using the automated instrument. Conclusion: There was no evidence that the use of an automated pipettor adversely affected any of the performance characteristics of the assay. Indeed, routine use of the Tecan automated pipettor has resulted in a decrease in the typical daily workload.

• The Journal of Information Technology and Database
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• v.7 no.2
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• pp.47-59
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• 2000

In this paper, we analyze the applicability of a general optimization algorithm to a database optimization problem. The index selection problem Is the problem to choose a set of indexes for a database in a way that the cost to process queries in the given workload is minimized subject to a given storage space restriction for storing indexes. The problem is well known in database research fields, and many optimization and/or heuristic algorithms have been proposed. Our work differs from previous research in that we formalize the problem in the form of non-linear Integer Programming model, and investigate the feasibility and applicability of a general purpose optimization algorithm, called OPBDP, through experiments. We implemented algorithms to generate workload data sets and problem instances for the experiment. The OPBDP algorithm, which is a non-linear 0-1 Integer Programming problem solver based on Davis-Putnam method, worked generally well for our problem formulation. The experiment result showed various performance characteristics depending on the types of decision variables, variable navigation methods and ocher algorithm parameters, and indicates the need of further study on the exploitation of the general purpose optimization techniques for the optimization problems in database area.

• The KIPS Transactions:PartD
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• v.13D no.2 s.105
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• pp.183-190
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• 2006

Database workloads may show different resource usages for database applications. Database administrators can enhance the DBMS performances through resource management that reflects workload characteristics. We provide a method that can identify tunable resources from analyzing the relationship between performance indicators and resources. First, we select which performance indicators increase or decrease by expanding resources using a correlation coefficient and a significance level test. Next, we identify resources that can affect the DBMS Performances by using increasing or decreasing performance indicators. We evaluated our method in the TPC-C and TPC-W environments.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.35 no.4
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• pp.33-40
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• 2012

Dentists are known to be highly exposed to the musculoskeletal disorders (MSD). The present study investigated the prevalence of MSD among Korean dentists and association between their MSD and physical workload. In addition, detailed causes related to the physical workloads were identified in dental operation, and needs for improvement of dental instrument and environment were collected from Korean dentists. The standardized Nordic questionnaire was used to survey body troubles and three types of questionnaires were made to investigate the physical workloads, causes of the physical workloads and improvement priority of dental equipments, respectively. A total of 104 Korean dentists were participated in the survey. Neck trouble (82%) was the most prevalent in Korean dentists, and shoulder (68%) and low back trouble (56%) followed, while low back trouble was reported to be most frequent in previous studies. The body troubles were related to the physical workload of the corresponding body parts, although they were not associated with personal characteristics. Most Korean dentists selected 'to keep direct view inside patient's mouth' and 'no support of the hand with dental instruments' as the causes of awkward and strenuous work postures. They wanted design improvement for some equipment in their operating room such as operating light and arrangement of workplace.

• Korean journal of aerospace and environmental medicine
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• v.31 no.2
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• pp.38-44
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• 2021

Purpose: This study aimed to identify the prevalence of fatigue and its associated factors leading to the fatigue among Korean commercial airline pilots. Methods: An anonymous, web-based questionnaire collecting data on sleep related characteristics was completed by airline pilots. The final 1,029 samples of completed questionnaires were analyzed. The association of the risk factors with fatigue was determined using logistic regression analysis. Results: The prevalence of fatigue was 60% (Fatigue Severity Scale index≥3.2), disturbed sleep 28% (Pittsburgh Sleep Quality Index≥9), daytime sleepiness 17% (Epworth Sleepiness Scale≥10), and sleep apnea (Berlin Questionnaire≥2) 11%. The fully adjusted logistic regression showed that quality of life (odds ratio [OR]=0.16, confidence interval [CI]=0.11-0.24), daytime sleepiness (OR=1.26, CI=1.18-1.34), sleep quality (OR=1.44, CI=1.29-1.61), mental workload (OR=1.10, CI=1.05-1.14), vigorous physical activity (OR=0.82, CI=0.72-0.92), late starts (OR=1.25, CI=1.06-1.46) and average weekly flying hours (OR=1.02, CI=1.00-1.03) were associated with higher levels of fatigue. Conclusion: Lower quality of life, disturbed sleep, more subjective sleepiness, shorter sleep duration, higher mental workload, less vigorous physical activity, frequent late starts, and longer flying hour were shown to be risk factors for fatigue in airline pilots. These findings should be taken into account in the development of sleep and fatigue countermeasures for airline pilots.