Jaeho Choe

Coach design for the Korean high-speed train: a systematic approach to passenger seat design and layout.

Proper ergonomic design of a passenger seat and coach layout for a high-speed train is an essential component that is directly related to passenger comfort. In this research, a systematic approach to the design of passenger seats was described and the coach layout which reflected the tradeoff between transportation capacity and passenger comfort was investigated for the Korean high-speed train. As a result, design recommendations and specifications of the passenger seat and its layout were suggested. The whole design process is composed of four stages. A survey and analysis of design requirement was first conducted, which formed the base for designing the first and second class passenger seats. Prototypes were made and evaluated iteratively, and seat arrangement and coach layout were finally obtained. The systematic approach and recommendations suggested in this study are expected to be applicable to the seat design for public transportations and to help modify and redesign existing vehicular seats.

Development of Finger Gestures for Touchscreen-based Web Browser Operation

Compared to the existing PC which uses a mouse and a keyboard, the touchscreen-based portable PC allows the user to use fingers, requiring new operation methods. However, current touchscreen-based web browser operations in many cases involve merely having fingers move simply like a mouse and click, or not corresponding well to the user`s sensitivity and the structure of one`s index finger, making itself difficult to be used during walking. Therefore, the goal of this study is to develop finger gestures which facilitate the interaction between the interface and the user, and make the operation easier. First, based on the frequency of usage in the web browser and preference, top eight functions were extracted. Then, the users` structural knowledge was visualized through sketch maps, and the finger gestures which were applicable in touchscreens were derived through the Meaning in Mediated Action method. For the front/back page, and up/down scroll functions, directional gestures were derived, and for the window closure, refresh, home and print functions, letter-type and icon-type gestures were drawn. A validation experiment was performed to compare the performance between existing operation methods and the proposed one in terms of execution time, error rate, and preference, and as a result, directional gestures and letter-type gestures showed better performance than the existing methods. These results suggest that not only during the operation of touchscreen-based web browser in portable PC but also during the operation of telematics-related functions in automobile, PDA and so on, the new gestures can be used to make operation easier and faster.

A psychophysical evaluation of interior design alternatives for a high speed train

Abstract The magnitude estimation technique was used to evaluate several interior design alternatives for a high speed train. Design factors considered in this study include direction of passenger seats; passenger activity; and passenger age. The results showed that the passenger seat should be able to be arranged toward the traveling direction of the train. Also, a variety of convenience facilities could enhance the passenger comfort. These results were validated by using two different dependent measures. This paper demonstrates the use of psychophysical measurement techniques when it is difficult to express subjective preference in the form of quantitative data for making engineering decisions.

The Effect of Text Information Frame Ratio and Font Size on the Text Readability of Circle Smartwatch

Objective: The objective of this study was to examine frame ratio of text information and font size in the circle smartwatch. Background: Recently, electronic manufacturers try to develop the original metaphor of traditional wrist watch (circle) in terms of smartwatch. They endeavor to break the square display in order to improve emotional customer satisfaction. Method: The experiments examined twenty level of text information design, combinations of four frame ratios (1:1, 4:3, 16:9, 21:9) and five font sizes (6pt, 7pt, 8pt, 9pt, 10pt). Nineteen participants volunteered for the experiment. Dependent variables were WPM (Words per Minute), reading preference, design preference and total preference. Furthermore, small circle display was made by using circle display data (1.3inch), which was exhibited in IFA (International Funkausstellung) 2014. Results: As a result, ANOVA (Analysis of Variance) revealed that WPM, and task time preference affect the specific frame ratio and font size. Results of ANOVA for reading preference, design preference, total preference were grouped by post-analysis LSD (Least Significant Difference). Among users, display ratio (16:9, 21:9), and font size (9pt) were preferred. In conclusion, 16:9 display ratio and 9pt are adaptable for text information in 1.3inch circle display. Conclusion: From the study, it is shown that 16:9 display ratio and 9pt size are more adaptable for text information in 1.3inch circle display than others. It is mainly due to the fact that the order of frame ratio and font size may affect the usability of reading long text information in a small circle display. Therefore, when developers design a circle display, the square frame ratio and font size are required to be considered according to circle size. Application: The 16:9 display ratio and 9pt font size may be utilized as a text information frame in the circle display design guideline for smartwatch.

Analysis of Tendency and the Method Improving Ingress and Egress for Wheelchair Users

This study attempts to develop improved ingress and egress in vehicle for disabled wheelchair people who driving is available, after investigating the ingress and egress relation demand and the inconvenient factor in the vehicle. An experiment was performed for that disabled wheelchair people to analyze the characteristics of ingress and egress relation operation through the questionnaire survey and the camera photographing. The results suggest various improvements possibilities in inside handlebar as a main factor. Through analysis of disabled wheelchair persons ingress and egress tendency, the alternative shape and position of inside handlebar are suggested. Also, this paper aimed to draw ingress and egress improvement proposal by executing a verification experiment and collecting the preferences from disabled people.

Modeling of Wrist Discomfort with External Loads

The objectives of this study are to analyze representative wrist postures while using hand tools and parts at general assembly processes, to evaluate perceived discomfort on the wrist when external loads are present, and to suggest an evaluation and prediction model of perceived discomfort. Sixteen subjects participated in an experiment to appraise perceived discomfort. Three types of the wrist postures with five levels of non-neutralities were analyzed when five levels of external load were applied to each posture. The ANOVA results showed that the perceived discomfort of wrist postures was significantly affected by both the wrist posture and external load (p<0.001). It was also shown that some of the interactions between external loads and the wrist postures(Flexion/Extension*Load, Flexion/Extension*supination/pronation, ulnar/radial deviation*supination/pronation) were significant(p<0.001). The result implies that a new posture classification scheme for workload assessment methods may be needed to reflect such effects of external load and wrist posture. A regression model of perceived discomfort was developed with respect to wrist posture and external load from the experimental data. A subsequent experiment revealed that the correlation coefficient between the predicted values of perceived discomfort from the model and the actual values obtained from the experiment was about 0.98. It is expected that the results help to properly estimate the body stress resulting from workers postures and external loads and can be used as a valuable design guideline to analyze potential hazard of musculoskeletal diseases in industry.

A Cross-cultural Study on the Affection of Color with Variation of Tone and Chroma for Automotive Visual Display

Objective:The objective of this study is to evaluate affection on how users perceive colors viewed from an automotive visual display according to cultural and radical differences including North America, Europe, and Southeast Asia. This study especially aims to identify effects of the variation of tone and chroma of representative color groups by analyzing affection differences depending on cultural and racial differences targeting the colors constituted through variation of tone and chroma, centered on representative colors. Background: The colors of the menu, information display or background viewed through an automotive visual display are an important factor stimulating consumers affection, and therefore an effort to express the vehicles brand and product image through colors is made. The studies on colors focus only on the research on unique characteristics of colors, but an affective approach lacks according to cultural and racial differences on colors considering tone and chroma variation within a color from the currently used automotive visual displays. Method: To grasp the visual affection felt by users, this study extracted affective adjectives related with colors through existing literature and a dictionary for adjectives, and presented human affection dimensions on colors through evaluation of various colors. Prior to carrying out affection evaluation, the basic light sources, red (R), green (G), and blue (B) constituting the colors used for automotive visual displays were defined as a representative color group, respectively. When colors in a color group are constituted, the evaluation target of each color group consisted of the colors considering the variation of tone and chroma by changing color sense through RGB values of the remaining two light sources. And then, this study carried out affection evaluation on the constituted colors targeting the subjects with cultural and racial differences. Results: As a result of evaluating the constituted colors with representative affections, there were statistically significant differences between the groups having cultural and racial differences. As a result of S-N-K post-hoc analysis on the colors showing significant differences, North America and Europe were classified as heterogeneous groups. In some cases, Korea was classified as the homogeneous group with North America, but Korea was mainly classified as the homogenous group with Europe. Conclusion: The representative affections on colors from an automotive visual display was drawn as three affective dimensions: passionate, neat, and masculine. Based on these, the affection of Korea and Europe on the constituted colors showed significant differences from that of North America, as a result of affection evaluation on the constituted colors viewed through the visual display by reflecting cultural and racial factors. Regarding representative color groups, bigger cultural and racial differences were revealed in terms of affection on red and green colors than on blue color, and variation of affection was the biggest in the red color. Application: This study analyzed correlations of affection considering the colors constituted through variation of tone and chroma, and the culture and race in the representative color groups constituting a visual display. The results of this study are predicted to be utilized in coordination and selection of colors viewed from an automotive visual display taking into account culture and race.

Affective quality improving method for service fields by analysing customers' affective sensory responses

Purpose: The purpose of this study was to propose the useful method to improve service affective quality by analyzing customer’s service experiences and evaluating the satisfaction of the affective sensual responses to physical stimulus. Methods: While customers were experiencing the service, the customers evaluated the subjective satisfaction for the visual, auditory, tactile, olfactory and gustatory senses on a scale of -3 to 3 at each stage of the service process. The customers described the positive and negative feelings about each sensory stimulus, and explained the reason for the subjective evaluation scores. After experiencing the whole service, customers evaluated the affective quality of the whole service. Results: The proposed method was applied to coffee shops. 35 male and female college students were evaluated for 15 coffee shops in Korea. Multiple regression analysis revealed that auditory and olfactory senses had a greater impact on service affective satisfaction than other senses. Conclusion: This method is useful to identify the factors that affect customer’s affective quality and to find the target to improve physical environment more easily than existing methods.

Ergonomic Design of the Gauge Cluster Display for Commercial Trucks

Objective: The purpose of this study is to determine the priority of information presentation and the effective menu type to be placed in the center of a gauge cluster display for commercial trucks and to present a set of ergonomic designs for the gauge cluster display. Background: An effective ergonomic design is specifically needed for the development of the gauge cluster display for the commercial trucks, because more diverse and heavier information is delivered to truck drivers, compared to the information to passenger car drivers. Method: First, all the information that must be shown on the commercial truck display was collected. Then, the severity, frequency of use, and display design parameters were evaluated for those information by commercial truck drivers. Next, an analysis on the information attributes and the heuristic evaluation utilizing the display design principles were carried out. According to the results, a design alternative of the main screen to be displayed was constructed by priority. A comparative analysis between the alternative and existing main screens was also conducted to see the efficacy of the designs. Lastly, we conducted an experiment for the selection of menu type. The experiment was conducted using the driving simulator with an eye-tracking device. The independent variables were four types of the menu reflecting the commercial truck characteristics such as grid type, icon type, list type, and flow type. We measured preference, total execution time, the total duration of fixation on the gauge cluster area, and the total number of fixation on the gauge cluster area as dependent variables. Results: Four types of driver convenience information and six types of driver assistance information were selected as the information to be placed primarily on the main screen of the gauge cluster. The Grid type was the most effective among the menu types. Conclusion: In this study, the information that appears on the main screen of the display, the division of the display and the design of the menu type for commercial truck drivers were suggested. Application: This study is expected to be utilized as guidelines on the ergonomic design of a gauge cluster display for commercial trucks.

Usability Evaluation of the Touch Keys for the Smart Watch

The smart watch is the most popular wearable computing device because it takes a form of wristwatch. Many smart watches have adopted the touch screen interface due to the limited size of display. This paper focuses on touch key size and spacing that affect the usability about the touch key of smart watch. The experiments were made for four touch key sizes (width×height; 5×5, 5×7, 7×5, 7×7mm) and nine touch key spacing (vertical× horizontal; 0×0, 0×1, 0×3, 1×0, 1×1, 1×3, 3×0, 3×1, 3×3mm). The completion time, error rate, control discomfort and identification discomfort were measured. The touch key size 7×7, 7×5 and the touch key spacing 3×3, 1×3 provided the best results in terms of the completion time and the control discomfort, while the square touch key (7×7, 5×5) provided the best performance for the error rate measure. The result of this study can help ergonomically design the touch interface of the smart watch. †