Rohae Myung

Conjoint analysis as a new methodology for Korean typography guideline in Web environment

Abstract Statistical significance approach such as the analysis of variance (ANOVA) has been commonly used to analyze the legibility elements of on-line and printed texts. However, few researches have been done with conjoint analysis. Therefore, a new methodology of Korean typography guidelines for Web pages using conjoint analysis is introduced because conjoint analysis has a great merit of its representation of relative importance. Twelve volunteer subjects participated to investigate the effects for font type (Goolim, Batang, and Dodum), font size (10 and 12 pt) and line spacing (100% and 150%) in reading preference tasks. The results showed that conjoint analysis provided quantified customer preference functions for multi-attribute typography alternatives, including the contributions of each attribute and attribute level to the overall typography utility and the relative importance of typography attributes. The analysis results also suggest the following preference structures in selecting Hangul typography at the aggregate level: Line spacing has a relative importance of 53%, the most preferred factor in typography, followed by fonts (35%). The least preferred attribute is size, with an importance value of 12%. Relevance to industry By using the most preferred typography (font type, font size, and line spacing) in the Web environment, e-commerce providers will benefit from the enhanced user satisfaction caused by better usability of the websites.

A Study on Ecological Interface Design for Navy Ship's Radar Display

Objective: The aim of this study is developing the navigation radar display of navy ship with ecological interface design (EID) framework. Background: Navy ship radar operator must perform navigation support tasks by monitoring the complex and diverse information presented on the radar display. Current radar display is limited in effective navigation aid and response to an unusual state immediately. It is necessary to develop an effective radar display. Method: Ten navy radar operators performed a series of trials in a low-fidelity radar simulation in which they attempted to solve the problems of current navigation situation. Results: The result demonstrated that the ecological interfaces performance was better than the existing radar display on performance time and subjective mental workload. Conclusion: This study expand EID study field to navy ship radar display and confirm ecological display is better than existing radar display in performance time, subjective mental work load. Application: The result of this study may help to improve navy ship navigation radar display currently in use.

The Application of Work Domain Analysis for the Development of Vehicle Control Display

The purpose of this study is to apply WDA (Work Domain Analysis) for the development of EID (Ecological Interface Design) of vehicle control display. At first, a work domain model on the automobile operation was developed using the AH (Abstraction Hierarchy) which is one of WDA tools. Secondly, information requirements that should be included in vehicle control displays were extracted on the basis of the completed model. The vehicle control information that typical automobiles interface displays currently provide occurred on the low level of the work domain model. This implies that current control displays impose too heavy cognitive workload on automobile drivers. Information requirements that can be included new vehicle control display are also discovered in the high level of the work domain model. The detailed information for EID was not proposed in this study. In the further study, the development of vehicle control display will be deeply conducted, using the results of this study.

The mobile phone's optimal vibration frequency in mobile environments

Mobile environments are very dynamic and unpredictable [1]. When a mobile phone user is moving, his attention resources are reserved partly for passively monitoring and reacting to contexts and events and partly for actively constructing them [2]. In this paper, we suggest guidelines related to the optimal vibration frequency for the perception of mobile phone vibration when the user is moving. To guarantee the validity of this study, subjects were asked to indicate their perception of the randomly given 7 vibrotactile stimuli while they performed routine activities on a sidewalk, subway, or bus. With Logistic Regression analysis, the results showed that the optimal vibration frequency in the dynamic state was higher than 180 Hz, considerably higher than 151 Hz - the optimal vibration frequency obtained in the static state in the previous study. From this study, mobile phone manufacturers should consider this factor when designing the vibration frequency for the vibration mode so that missed calls in mobile environments are minimized.

Use of backward slip to predict falls in friction test protocols

Abstract In standard friction test protocols, backward slip in the takeoff phase is not considered because it is not believed to offer additional information about the prediction of slips and falls. A possible reason for the exclusion was because conventional slips and falls studies have used walking surface and shoe combinations that have a relatively high coefficient of friction. However, a normal gait pattern cannot be maintained when the frictional characteristics of a floor are low, and therefore there may be other measures of gait performance that are better predictors of loss of balance in extremely low frictional conditions. Therefore, a new approach, namely “backward slip” in the takeoff phase, was used to predict loss of balance when the frictional characteristics of a floor are low. As a result, dangerous falls initiated by backward slip were observed in this study, in contrast to the absence of backward slips in conventional studies. In addition, the conditional probability and logistic regression results showed backward slip in the takeoff phase could be an alternative measure in predicting dangerous falls because no significant difference was found between backward slip and forward slip in the prediction of dangerous falls. Relevance to industry By incorporating backward slip in predicting floor slipperiness, floor slipperiness on lower frictional floors, characterized by abnormal gait patterns, can be measured, and tighter criteria regarding safe floor surfaces can be enacted to prevent workers from dangerous slips and falls.

Attitude Indicator Design and Reference Frame Effects on Unusual Attitude Recoveries

The objectives of this study were to examine the combination effects of the attitude directional indicator (ADI) formats and the 2 reference frames (moving horizon [MH] and moving aircraft [MA]) on unusual attitude recovery performance. Three ADI display formats were examined: (a) conventional MH; (b) perspective-view aircraft symbol (PAS), which replaced the conventional miniature aircraft symbol with a pictorial moving aircraft symbol; and (c) command, which presented the appropriate direction for recovery using the pitch or roll arrow. Twenty-two participants (10 unmanned aircraft operators, 12 nonoperators) performed a series of trials in a low-fidelity ADI simulator in which they attempted to recover from a series of unusual attitudes. The results revealed that the combination effect differed according to display format. The command display expedited initiation of the roll input regardless of reference frame. The conventional display showed better performance in the MA reference frame. The PAS display improved the total recovery time and pitch input time of nonoperator participants in the MA reference frame.

Revised Computational-GOMS Model for Drag Activity

The existing GOMS model overestimates the performance time of mouse activities because it describes them in a serial sequence. However, parallel movements of eye and hand(eye-hand coordination) have been dominant in mouse activities and this eye-hand coordination is the main factor for the overestimation of performance time. In this study, therefore, the revised CGOMSL model was developed to implement eye-hand coordination to the mouse activity to overcome one of the limitations of GOMS model, the lack of capability for parallel processing. The suggested revised CGOMSL model for drag activity, as an example for one of mouse activities in this study, begins visual search processing before a hand movement but ends the visual search processing with the hand movement in the same time. The results show that the revised CGOMSL model made the prediction of human performance more accurately than the existing GOMS model. In other words, one of the limitations of GOMS model, the incapability of parallel processing, could be overcome with the revised CGOMSL model so that the performance time should be more accurately predicted.

Prediction of Menu selection on Touch-screen Using A Cognitive Architecture: ACT-R

Cognitive model, that is cognitive architecture, is the model expressed with computer program to show the process how human solve a certain problem and it is continuously under investigation through various fields of study such as cognitive engineering, computer engineering, and cognitive psychology. In addition, the much extensive applicability of cognitive model usually helps it to be used for quantitative prediction of human Behavior or Natural programming of human performance in many HCI areas including User Interface Usability, artificial intelligence, natural programming language and also Robot engineering. Meanwhile, when a system designed, an usability test about conceptual design of interface is needed and in this case, analysis evaluation using cognitive model like GOMS or ACT-R is much more effective than empirical evaluation which naturally needs products and subjects. In particular, if we consider the recent trend of very short-end term between a previous technology development and the next new one, it would take time and much efforts to choose subjects and train them in order to conduct usability test which is repeatedly followed in the process of a system development and this finally would bring delays of development of a new system. In this study, we predicted quantitatively the human behavior processes which contains cognitive processes for menu selection in touch screen interface through ACT-R, one of the common method of usability test. Throughout the study, it was shown that the result using cognitive model was equal with the result using existing empirical evaluation. And it is expected that cognitive model has a possibility not only to be used as an effective methodology for evaluation of HCI products or system but also to contribute the activation of HCI cognitive modeling in Korea.

A study of relationships between situation awareness and presence that affect performance on a handheld game console

Modern handheld devices are equipped with a high-speed CPU and a 3D graphic accelerator that enrich experience to a similar level as for Desktop Virtual Reality (VR). This research explored relationships between situation awareness and presence that affect performance on a handheld game console. The task was to shoot down enemy aircraft in a flight simulator game. Situation awareness (SA) was measured by SAGAT (Situation Awareness Global Assessment Technique), while presence was measured by PQ (Presence Questionnaire) Version 3.0. Performance was measured by the number of enemy aircraft shot down per minute during aerial combat in the flight simulation game. Situation awareness was positively significantly correlated with performance. The correlation between presence and performance was also significantly positive. Presence and SA were positively related. Research on situation awareness, presence, and performance can be conducted even on a handheld game console. The study also proved that the domain of research on situation awareness and presence can be extended to small displays, such as handheld game consoles.

Predicting Task-related Properties of Mental Workload with ACT-R Cognitive Architecture

In this paper, a methodology with ACT-R cognitive architecture is proposed to quantitatively predict task-related properties that influence mental workload. A mathematical representation of task-related properties over time with respect to an activated time of each module from ACT-R is proposed in this paper. Experiments were performed on menu selection and visual-manual tasks, varied by task difficulty and time pressure. As a result, it was found that predicted values of each task-related property, consisting of physical demand, mental demand, and temporal demand of NASA-TLX achieved by the proposed method, were highly correlated with mean values of subjective rating from subjects.