Recently, importance of the rehabilitation of hand pathologies as well as the development of high-technology hand robot has been increased. The biomechanical model of hand is indispensable due to the difficulty of direct measurement of muscle forces and joint forces in hands. In this study, a three-dimensional biomechanical model of four fingers including three joints and ten muscles in each finger was developed and a mathematical relationship between neural commands and finger forces which represents the enslaving effect and the force deficit effect was proposed. When pressing a plate under the flexed posture, the muscle forces and the joint forces were predicted by the optimization technique. The results showed that the major activated muscles were flexion muscles (flexor digitorum profundus, radial interosseous, and ulnar interosseous). In addition, it was found that the antagonistic muscles were also activated rather than the previous models, which is more realistic phenomenon. The present model has considered the interaction among fingers, thus can be more powerful while developing a robot hand that can totally control the multiple fingers like human.

The objective of this study is to survey the working environmental conditions and musculoskeletal workload(DMQ) in red pepper farmers. 155 full-time farmers(males=91, females=64) lived in Chungnam and Jeonbuk participated in the study. To offer the fundamental data for agricultural improvement of red pepper farms, information about working farm conditions, health condition, musculoskeletal disorders(MSDs), labor intensity and musculoskeletal workload was obtained by questionnaire and interviews. The results are as follows: 1. The farmers reported sunlights, high temperature and cold/ draught as uncomfortable work environment. 2. Physical and mental fatigue in females is higher than that of males. 3. The prevalence rates of medical diagnosed diseases are higher in order of osteoarthritis, herniated nucleus pulposus(HNP), and chronic gastritis/gastric ulcer. 4. Prevalence rates of musculoskeletal symptoms more than standard 1 among the various pain areas are higher in order of low back, shoulders and knees. These results can be used practically for agricultural improvement of red pepper farms to prevent MSDs.

This study was aimed to analyze of characteristics of Musculoskeletal disorders (MSDs) based on the industrial accident statistics which were extracted from the Ministry of Labor. In this study all MSDs cases in 2007, 7,723 cases, were investigated. First of all, for the analysis of a wide view point concerning the characteristics of MSDs, We have inspected characteristics of the user population (i.e. age, gender, employed periods, etc.). Secondly, work-related risk factors such as repetitive motions, awkward postures, manual material handling were analyzed in terms of disease code, injured part of body, types of business, etc. Next, characteristics of handling of heavy materials were analyzed according to weight, types of handling, agency of cause, etc. Finally, we have compared and analyzed the features between the period of hospitalization and other variables. In addition to that we also conducted statistics analysis. The study results showed that there were significant characteristics of MSDs that could be used as basis data for the MSDs prevention policy.

To evaluate the usability of a Kimchi refrigerator, we performed an evaluation test that consisted of an experiment and a post-hoc questionnaire survey. In this study, we focused on the older women who have less physical and cognitive ability than younger women. In physical usability, there was no significant difference between the older and the younger subject group. However, there was some significant statistical difference in the results of cognitive usability test. When the subjects debriefed their operations after finishing the experiment, the all subjects in the older group reported the difficulties in identifying the labels and icons in the control panel and in understanding operation sequences. Also, they couldn't learn and remember the operation procedures well. Based on the analysis of the video protocols, some causes of the problems were found and then several improvement ideas were suggested.

Impact force to a body during walking depends on walking speed, walking steps, the condition of the floors and shoes, and weight. The ground reaction force and the foot pressure can be measured instantaneous force easily, but it's difficult to find out the amount of transferring forces to the body. On the other hand, the acceleration has an advantage for analyzing the amount of transferring forces. However, most of studies about impact forces to the ground reaction during exercise have been limited to analyze instantaneous forces. The important thing is to evaluate characters and the amount of the impact force rather than the magnitude. Therefore, this study analyze the impact force using 3 axis acceleration in three dimensions (x; anterior-posterior, y; left-right and z; longitudinal axis) using three axis acceleration. As working speed increased, impact forces increased significantly. Impact forces on x axis and z axis are higher at lower limb than that of upper limb. However, impact force at the knee is higher than that of other parts on y axis regardless of walking speed significantly. In addition, relations of the impact forces as interaction of experiment factors as well as effect of each factor are analyzed.

The purpose of this study, during the lifting task was researching the difference and a relationship between the ground reaction force and the grip strength by change of position. After grip strength has measured in symmetry position and asymmetry position at 45cm and 75cm of height of hand, ground reaction force was measured by same attitude lifting wooden box. We analyzed the difference of grip strength and ground reaction force in each position change. The results of grip strength, the grip strength of both hand were significant difference that in study subject symmetry and asymmetry position (p<0.01). The results of symmetry lifting task, the study subjects was significant difference of the ground reaction force difference by height (p<0.05). Asymmetry lifting task was significant difference of ground reaction force difference by direction of rotation was changed (p<0.01). The result of it will rotate with non-dominant hand side of lifting tasks from height 75cm where it easily maintains a balance possibility and decreasing the load of the hand. Therefore, from the workshop in the work people, it will be between the height 75cm and non-dominant hand side of trunk rotatory direction in the lifting tasks. Future study is necessary researched about the change of grip strength when the height of the hand is higher, and the difference of the ground reaction force when the change of weight.

Visual occlusion method is a visual demand measuring technique which uses periodic vision/occlusion cycle to simulate driving environment. It became one of the most popular techniques for the evaluation of in-vehicle interfaces due to its robustness and cost-effectiveness. However, it has a limitation in that the vision/occlusion cycle forces the user to use the IVIS at a predetermined pace, while a driver decides when to use the device on his/her own in actual driving. This paper proposes a user-driven visual occlusion method for measuring the visual demand of in-vehicle interfaces. An experiment was conducted to examine the visual demand of an in-vehicle interface prototype using both the existing (system-driven) occlusion method and the proposed (user-driven) one. Two in-vehicle tasks were evaluated: address input and radio tuning. The results showed that, for the radio tuning task, there were significant differences in total shutter open time and resumability ratio between the methods. The user-driven visual occlusion method not only allows a better representation of drivers' behavior, but it also seems to provide more information on the chunkability of a task.

This study is concerned with predicting human search performance using a visual lobe. The most previous studies on human performance in visual search have been limited to a single-target search. This study extended the visual search research to multiple-target search including targets of different types as well as targets of same types. A model for predicting visual search performance was proposed and the model was validated by human search data. Additionally, this study found that human subjects always did not use a constant ratio of the whole visual lobe size for each type of targets in visual search process. The more conspicuous the target is, the more ratio of the whole visual lobe size human subjects use. The model that can predict human performance in multiple-target search may facilitate visual inspection plan in manufacturing.

A car navigation system as an in-vehicle route guidance information (RGI) offers a state-of-the-art technological solution to driver navigation in an unfamiliar area. However, the RGI is provided by some pre-determined options in terms of the interface between a driver and a car navigation system. Drivers occasionally pass the target intersection owing to non- or late- recognizing it. This paper is examined the position of driver's turn signal operation and intersection recognition approaching at the target intersection which is difficult to identify, as a fundamental research on developing the additional RGI connecting with the turn signal control. The field experiment was conducted to measure distances of the turn signal operation and the intersection recognition from the target intersection according to left turns, right turns, and landmarks at adjacent intersection. And glance behavior to the car navigation display was evaluated by using an eye camera. The results of the field study indicate that, most case of driving, drivers operate the turn signal until 40m to 50m before coming to the target intersection. The driving simulator experiment was performed to examine the effectiveness of providing the additional RGI when drivers did not operate the turn signal approaching at the target intersection based on the results of the field study. To provide the additional RGI is effective for the intersection identification and recognition, and expected to improve the traffic safety and the comfort for drivers.

Driving is a complex psychomotor task often interrupted by secondary activities that increase cognitive workload and divert attention away from the roadway. The risk of inattentive driving is known to vary with age. To assess the characteristics of advancing age on driver's cognitive workload under dual task condition, we evaluate the performance of 96 drivers divided into three age groups: 20's, 40's, and 60's. This study considers driver's cognitive workload in the context of urban and highway driving. Error rate & Dual task cost are used to measure driver's cognitive workload. Results indicate that age impacts cognitive workload during dual task driving conditions.

Work related musculoskeletal disorders(WMSDs) was a leading cause of sick leave and injuries in the industries of our country. Posture was an important consideration in the design of work method and workplaces, because it affected the ability of workers to use various equipments and influenced how long they could perform their job without feeling discomfort, fatigue, and musculoskeletal disorders. Imbalanced lower limb postures such as a squatting posture were awkward working postures common to the shipbuilding shops, farms, automobiles assembly lines in our country. Different awkward working postures were known to be associated with specific musculoskeletal disorders. Eight postures in lower limb postures divided into balanced and imbalanced postures were evaluated by electromyographic(EMG) activity for lower limb muscles. Twelve male subjects participated in this study. This paper was to analyze the effects of lower limb muscles workload according to lower limb postures(knee angle) and working time. The ANOVA results showed that most EMG root mean square(RMS) values were statistically significant effect according to lower limb postures(knee angle) and working time. Therefore, the results of this study will provide the basis to evaluate workload of lower limb postures correctly adopted by workers in various jobs and the ergonomic reference to prevent WMSDs.

The aim of the study is to investigate the usability of wheel navigation key(WNK) recently adopted for the new models of mobile phone and MP3 product. In this study, an experiment was designed to evaluate the functional benefit of WNK by using a performance test. A questionnaire was also used to examine the personal preference. In results, a significant difference was found in performance time between wheel-type and button-type product. In general, the difference was more significant as subject's skill level was higher. In particular, the performance time was significantly shortened with the WNK when a searching task was required, but push button was an effective interface for simple search task among beginners. Therefore, the wheel navigation key can be used to improve the usability of product by reducing the searching time in mobile phone and mp3. For practical application, the user's level of skill needs to be considered to maximize the effect of interface when choosing WNK or push button.

Ten young females were participated in this study to investigate the effects of types of shoes (sneakers, high heels, kill heels), types of tasks (standing, walking floor, step up and down), and areas of foot (fore foot, middle foot, rear foot) on foot pressures as well as subjective discomfort ratings. Results showed that kill heels had the most discomfort shoes, followed by high heels and sneakers. Generally, as the heel was higher, the discomfort of foot increased. For the analyses of task types, generally discomfort ratings were highest for the step down and up, followed by walking floor and standing. Especially discomfort ratings of high heels and kill heels were more evident in case of step up and step down than standing and walking floor. Standing task was rated as the lowest levels of discomfort on users' foot. Peak and mean foot pressures were also evaluated in this study. The findings represented that there was no significant differences between types of shoes in both peak and mean foot pressures. The peak pressure (82.14kPa) and mean pressure (40.32kPa) for standing task were significantly lower than those of other tasks [walking floor (190.55kPa, 55.46kPa), step up (191.43kPa, 53.80kPa), and step down (200.66kPa, 52.62kPa)]. Generally discomfort ratings and peak/mean pressures associated with foot showed that fore foot had higher discomfort ratings as well as peak and mean pressures than middle and rear foots. In particularly, this trend was more obvious in case of high heels and kill heels. For the high heels and kill heels, the peak pressures of fore foot were 4.5~4.8 times and 2.3~2.5 times greater than that of middle foot and rear foot, respectively, whereas the peak pressures of fore foot were 2.9 times and 1.7 times greater than that of middle and rear foots, respectively, in case of sneakers.

This study investigated perceived discomfort and reasons related to use three information technology products (personal computer, mobile phone and digital television remote controller), and extracted the universal design factors. 240 people (30 females and 30 males for four age groups) participated in the one-to-one interview type of questionnaire, and replied to degree of discomfort at level of items and the reasons of discomfort at level of detailed elements for each product. As a result, almost all age groups answered that using input buttons of mobile phone and remote controller and watching display of mobile phone caused discomfort. Binary logistic regression of the detailed elements showed that response rate of discomfort mostly increased with age, except for specific elements such as shape of mouse and remote controller, and location of function button of mobile phone. Some of the detailed elements had high response rate of discomfort from all age groups. The age groups also showed similar tendency for the elements to select one alternative for the reason of discomfort, but not for sound volume and size of mobile phone and button sensitivity of remote controller. Finally, the universal design factors were extracted for each product based on the results, and divided into common factors and factors classified by the age group. Through this study, we identified using practices of various age groups and their demands for the products. It is expected that extracted detailed elements can be considered as important design factors to design the products universally.

The purpose of this research is to develop a protocol which can quantitatively evaluate cognitive ability that is needed when elderly people use mobile phone. Since previous methods for measuring the cognitive ability of elderly people was mainly for clinical evaluation, they would not be adequate to measure cognitive ability for mobile phone development. Therefore, this study suggests cognitive areas which are necessary to use the mobile phone based on the existing evaluation tools. The cognitive areas consist of language, visuospatial ability, memory, executive function and perception. New questionnaire was developed to evaluate the individual cognitive ability for the elderly. They include 9 questions for button comprehension test, 8 for icon button comprehension test, 10 for vocabulary comprehension test, 8 for menu comprehension test, 3 for icon size test, and 2 for font size test. The protocol can be used in the field although further modification may be necessary for betterment.

The muscle strengths in various postures are used in our daily life with or without our recognition. Also, many works are still performed with strengths, although mechanization and automation have been fairly accomplished at the industry site. Since the late seventies, various body measurements have been conducted periodically in Korea, however, muscle strengths have not been measured actively. For this reason, the muscle strength data have been hardly accumulated. The aims of this study are to learn more about the physical strength of young-aged Koreans and to provide basic information for designing equipments, tools and facilities in the work site and daily life. The muscle strengths that are related to shoulder and upper limbs joints, which are used frequently, are measured in this study. Eighteen muscle strengths, from seven different movements such as elbow flexion, elbow extension, shoulder abduction(seated), shoulder adduction(seated), shoulder rotation(internal and external), lifting a tray, and turning a key(inward and outward) were measured. For every movement, the muscle strengths for both hands were measured. In each measurement, five seconds averaged value and peak value were collected. Comparing the average value, the strength of shoulder adduction was the strongest for male and female, while strength of turning a key inward with left hand was the weakest for male and female. Strengths of preferred hand in elbow extension, shoulder abduction, shoulder external rotation, lifting a tray, and turning a key were stronger than those of non-preferred hand for both male and female. Rohrer's index considerably had an effect on muscle strength. The results of this study can provide some basic information not only in designing the equipment and facilities in work site or daily life, but also in selection, training and management of workers.

This study surveyed standardization activities of the International Standard Organization (ISO) Technical Committee 159 (TC 159) (ergonomics) in the year 2008. The subcommittee 1 (SC 1) dealing with general ergonomics principles produced one committee draft (CD). The subcommittee 3 (SC 3) dealing with anthropometry and biomechanics systematically reviewed two ISO standards issued in 2003 and 2004 respectively. The subcommittee 4 (SC 4) dealing with ergonomics of human system interaction issued 11 final draft international standards (FDIS), 3 draft international standards (DIS), 4 CDs, and 4 new work item proposals (NWIP). The SC 4 also systematically reviewed 10 international standards due on the year 2008. The subcommittee 5 (SC 5) dealing with ergonomics of the physical environment issued one FDIS, 3 CDs, and one NWIP. This paper summarized the major features of the FDIS approved by each subcommittee of TC 159 for publication in the year 2008.