Objective: The purpose of this study is to investigate the effects of the roughness, friction coefficient, and hardness, which are typical properties related to tactile affection affecting the interior affective satisfaction for Thermoplastic Olefin (TPO) materials. This study also aims to derive optimal design values to maximize tactile affective satisfaction. Background: There are a variety of design variables related to tactile affection of vehicle interior materials. Previous studies about sensibility engineering for vehicle interior material mainly interested to visual sense, and some studies for tactile sense had limitations performed in actual vehicle conditions where human sensibility could be affected by several noise factors. Therefore, it is necessary to make material's samples considering various levels of design variables related to the material properties, and to determine the optimal design combinations to improve tactile affection. Method: A total of 72 subjects, 59 males and 13 females, participated in this experiment. A total of 18 TPO materials were fabricated to evaluate the affective satisfaction, according to the physical property levels of the interior materials. Affective satisfaction with a sense of touch was used as a dependent variable, and roughness, hardness and coefficient of friction were considered as three independent variables. For 18 samples provided by combinations of three independent variables, the affective satisfaction was measured repeatedly according to the within-subject design. ANOVA and regression analysis were carried out to derive optimal design values for vehicle interior materials. Results: The optimal regression model was derived from the best subset regression analysis, which included hardness and roughness variables. In addition, the optimal design values were predicted through the iso-response contour plots obtained by the response surface model. The optimum tactile affection condition can be provided from the middle level of hardness and the low level of roughness. Conclusion: By suggesting the optimal material property level of TPO material, it is possible to provide improved affective satisfaction that can be felt in high quality interior materials. Application: This study can be used to improve tactile affection for vehicle interior design, and be helpful to cost reduction through replacing artificial leathers by improved TPO materials.

Objective: The objective of this study is to investigate the intrusive feeling caused by a Lane Keeping Assistance System (LKAS) and measure it objectively through the sensor log data of a vehicle. Background: LKAS, one of the Advanced Driver Assistance System (ADAS), directly intervenes in the steering wheel control to assist the driver to keep the lane. Due to the torque generated by the LKAS, the driver has a different and undesirable feeling from a usual situation, which can affect the driving experience. Nevertheless, the performance of the LKAS in most studies focused only on how well the system keeps the lane. Method: Through an actual driving test using a test vehicle equipped with an LKAS, two ADAS experts and two human factor experts observed the intrusive feeling while collecting sensor log data at the same time. After the types of the intrusive feeling were classified, variables that could account for the feeling were derived. Then, this study compared the data collected from the vehicle with and without the intrusive feeling. Results: Three types of the intrusive feeling were observed: abrupt lateral change, steering wheel vibration, and heavy steering. The lateral speed (LS), the high-pass filtered steering angle (FSA), and the interrupt torque (IT) were then derived as the variables that could explain each feeling, respectively. It is found that the patterns of the derived variables are different in driving with and without the intrusive feeling. Conclusion and Application: The intrusive feeling found in this study can be used as a performance index in the development stage of the LKAS. It will be helpful to systematically reduce the intrusive feeling.

Objective: The purpose of this study was to evaluate the biomechanical effects of insole material and hardness in different plantar regions on the comfort and impact absorption during walking and to analyze the correlations between comfort and impact variables. Background: It is necessary to apply materials tailored to the functionalities of different plantar regions during different phases of the gait cycle: the rearfoot portion should absorb the impact force during the heel-contact phase, the midfoot portion should support the entire arch, and the forefoot portion should enhance the swing efficiency during the toe-off phase. Method: Twenty men in their twenties were recruited for the study (age: $23.4{\pm}2.7yrs$; height: $175.9{\pm}4.1cm$; weight: $72.9{\pm}9.4kg$). They wore insoles in random order. Pedar-X system (Novel GmbH, USA) and Treadmill (Instrumented treadmill, Bertec, USA) were used to measure the plantar pressure and ground reaction force. The walking speed was set at 1.3m/s and 1.7m/s. The sampling rate was set at 50Hz and 1,000Hz, respectively. For comfort testing, the subjects administered a questionnaire survey using the visual analogue scale (VAS) after walking 1km. Three insole models were tested: Insole A using a mixed material with shock-absorbing and anti-rebound components uniformly spread throughout the insole; Insole B and Insole C using sponge and ethylene vinyl acetate (EVA), respectively, as underlying material and strengthened with shock absorber in the rearfoot portion, high-hardness material in the midfoot portion, and anti-rebound function in the forefoot portion. The impulse, mean impact force, initial peak of ground reaction force, and loading rate were calculated. Results: First, Insole B significantly outscored Insole A in terms of the forefoot cushioning comfort (p<.05), with Insole B and C showing higher overall comfort scores compared with Insole A (p<.05). Second, Insole A showed higher mean impact force, initial and peak vertical ground reaction forces, and loading rate compared with Insoles B and C, but without reaching statistical significance. Third, Insole B and C showed statistically higher mean pressure in the midfoot portion compared with Insole A (p<.05). Conclusion: Positive effects in terms of comfort and impact absorption were demonstrated by the insoles fabricated with different materials and hardness tailored to the functionalities of different plantar regions in comparison with the conventional insoles using the uniform material throughout the insole. In particular, positive effects on overall comfort were found to be ascribable to the enhanced hardness in the midfoot portion, which supported the arch more efficiently and contributed to an even distribution of the overall pressure on the plantar. Application: The study results can be applied to insole development as follows: Insole material and hardness should be varied for different plantar regions, and shock absorber and high-hardness material should be used for the rearfoot and midfoot portions, respectively.

Objective: This study proposed a system for safe management of agricultural facilities whereby safety accidents of farmers are prevented from harmful factors of agricultural facilities and relevant hazardous situations, and efficient reaction is made possible when an accident occurs. Background: Recent development of information and communication technology (ICT) brought groundbreaking development of cutting-edge technologies such as the internet of things (IoT) and ubiquitous sensor network, and application of such technologies is expanding to the area of industrial safety. In particular, accidents from the hazardous environment surrounding agricultural facilities, say, from harmful gases, are frequently taking place and therefore development of services for safe farming work is required. Method: This study examined the types of safety accidents related to agricultural facilities occurring during farming work and designed a ICT-based system for safe management of accidents. Results: This study presents a model of such system and the model has the following functions: detection of harmful environment and conditions dangerous to farmers with sensor technologies; communication network technology for prevention of and fast coping with accidents; and user interface aimed at monitoring harmful environment and dangerous situations. Conclusion: The ICT-based system for safe management of agricultural facilities proposed in this study is expected to be applied as an application technology for safe agricultural activities. Application: The outcome of this study will be useful to develop a convergent ICT-based system for the prevention of safety accidents related to agricultural facilities.

Objective: The aim of this study is to investigate the legibility of Hangul characters in two situations; moving characters and moving observers. Background: The legibility study of Hangul has been primarily focused on the case in which a static observer reads static characters. With the advent of kinetic typography, characters have begun to move, and drivers have to read road signs while moving. Research on legibility of Hangul in a moving situation is needed. Method: In order to compare the legibility of Hangul in the context of observer movement and Hangul movement, the character size (visual angle of character = $2.5^{\circ}$, $5.5^{\circ}$, $8.5^{\circ}$), the reading time (1 Sec. 2 Sec. 3 Sec.), and the difficulty of the letter (the number of stroke in a character = 1~5, 6~10, 11~15) were set to be the same and the legibility was compared. Results: Under the same experimental conditions, the reading rate of moving observers was higher than that of moving letters. In both situations, the reading rate increased as the letter size and reading time increased and the difficulty of letters decreased. In the case of moving characters, the reading rate sharply changed with the change of the character size and the difficulty of the character. On the other hand, moving observers did not change sensitively to these changes. Conclusion: In contrast to the situation where moving observers read Hangul characters, the reading rate of the kinetic typography is sensitive to the difficulty of the character and the size of the character. Therefore, when designing the kinetic typography, it is necessary carefully to adjust the size and difficulty of the characters in consideration of legibility. Application: The results of this research will be helpful in designing kinetic typography and designing Hangul typography which should be read by moving observers.

Objective: The purposes of this study are to survey the accidents occurred in the kitchens of the catering services and restaurants, and to identify their risk factors focused on the kitchen facilities and utensils. Background: Accidents rates in the food industry showed increasing trend in many countries including Korea. The workload in catering and commercial kitchens is high, and workers in kitchens are experiencing several kinds of accidents and hazards like burn, slip, cut, and musculoskeletal disorders. To reduce the accidents and hazards in kitchens, the information about the accidents and hazards occurred in kitchens and risk factors related to kitchen facilities and utensils are necessary. Method: Questionnaire survey was conducted for accidents occurred during last one year, their risk factors, and preventive measures. Participants were 321 workers currently working in kitchens of catering services and commercial restaurants, and 276 respondents were used for analysis. Frequency analysis was conducted for the characteristics of the participants and kitchens, also for the kitchen facilities and accident cases occurred within a year till today. Chi-square test was conducted to see whether the accidents cases were different according to the kitchen type, number of workers (size of kitchen), etc. Based on these results, preventive measures were derived for each accident type. Results: Frying kettle, rotary kettle, vegetable cutter and kitchen knife were more dangerous cooking utensils. More than 30% of the respondents (31.5%) reported more than one accident case during last one year (1 case, 14.9%; 2 cases, 8.3%; and 3~5 cases, 8.0%). The most frequently reported accident was burn injury (34.0%), followed by cut (27.1%), slip (26.4%), and musculoskeletal disorders (7.6%). It was found from chi-square test that the number of accidents during last one year was dependent on the level of safety device installation (more safety device, less accident cases). Several preventive measures were suggested for each accident and hazard based on the results. Conclusion: Burn, cut, slip, and musculoskeletal disorders were the frequently occurred accident and hazards, and frying kettle, rotary kettle, vegetable cutter, and kitchen knife were identified as most dangerous cooking utensils. Thus, preventive efforts should be focused on these accidents and cooking facilities. Application: The results of this study would be helpful as basic data for kitchen safety and the suggested preventive measures would be useful for establishing policies to reduce accidents and risk factors.

Objective: The aim of this study is to investigate discrimination power of a black letter on the 3 types of color background; red, green and blue colors. Background: In previous studies on visual search, the similarity between distractors and target was main factor to visual search performance. However, there were a few studies on how the background color of visual search field affects visual search performance. Method: In the search fields with black distractors, black target and 3 types of background colors, all of ten subjects were participated in two kinds of experiments. Each subject performed visual search experiments of 50 times for a kind of background color to measure an average time of visual search. Each subject repeated visual lobe experiments of 720 times for one background color and the size of visual lobe was measured using these measurements. Results: The size of visual lobe was not affected by the background color. Visual search time was significantly different when the background color was green and blue. However, when the background color was green and red, and red and blue, the visual search time was not significantly different. Conclusion: The background color effect appeared in visual search time, but not in the size of visual lobe. These results may indicate that there is more background color effect when searching target with sufficient time than when searching target in a short time. Application: The results of this research will be helpful in selecting color background for black letter or black object.

Objective: The purpose of this study is to provide a guide for the seat back design by studying the effects of seat back angle on muscle activity and subjective physical comfort in rehabilitation equipment for the aged. Background: While there is a lot of research on rehabilitation equipment for the elderly, there is a lack of research on chair design suitable for rehabilitation equipment. However, rehabilitation requires a chair to support the user's body, while the chair of the rehabilitation device determines his or her posture and has a significant impact on the effectiveness of the exercise and user satisfaction. The backrest angle of chair is an important factor in determining the posture, efficiency, and physical comfort while exercising rehabilitation. Method: In order to study the effect of the seat back angle on muscle activity and physical comfort in the adduction and abduction rehabilitation exercise of the aged, this study conducted some adduction and abduction movements experiment with 12 people aged 65 or older. EMG signals and subjective comforts were measured under five backrest angle ($90^{\circ}$, $100^{\circ}$, $110^{\circ}$, $120^{\circ}$, and $130^{\circ}$). Results: For the hip adduction movement, the backrest angle of the rehabilitation device did significantly affect the muscle activity of the adductor longus and showed an increased muscle activity as the angle increased. For the abduction movement, the back rest angle had a significant effect on the muscle activity of the tensor fascia latae, and the muscle activity tended to increase as the angle increased. There was no significant impact on the muscle activity of gluteus medius, but muscle activity tended to decrease with increasing angles. The subjective comfort during the adduction and abduction movements was shown to be significantly different with the backrest angle. Subjects felt comfortable with a backrest of $100^{\circ}$ to $120^{\circ}$. Conclusion: This study identified how the backrest angle of chair in hip rehabilitation equipment for the elderly affected muscle activity and subjective comfort. The subjective evaluation of physical comfort was significantly affected by the angle of the backrest. The muscle activity showed significant differences in both adduction and abduction movements (except gluteus medius) and that overall the muscle activity varied with the back rest angle. Application: This study could serve as a basis for designing the seat of hip rehabilitation equipment for adduction and abduction exercise.

Objective: The purpose of this study is to identify the types of farming accidents that occur differently depending on the crops. Background: Agriculture is difficult to standardize workplaces, and work is done in a wide variety of ways depending on the terrain and crops. Safety measures also need to be established by the line of sight to suit their characteristics, for this purpose. It is necessary to examine the nature of farm work accidents appears to crops. Method: In the study, 251 replying questionnaires were used. Through this, we identified the major types of accidents by seven kinds of crops. Results: Slip and trip accidents occur at the highest rate in all crops, and other accidents occur differently depending on the crop. Conclusion: This study is significant in that it describes the characteristics of the accidents that occur according to the crop. Application: The results of this study provide accident characteristics that occur differently according to the crops, which can be used as basic data for establishing agricultural safety measures.