Yong Gu Ji

The Influence of Cultural Differences on the Use of Social Network Services and the Formation of Social Capital

With the advent of Web 2.0, social network services (SNSs), such as Facebook and MySpace, have grown explosively and globally as one of core Web 2.0 applications. However, as revealed in other cultural comparison studies in the field of human–computer interaction, it is believed that cultural differences profoundly impact on how people use SNSs. Unfortunately, the differences in using SNSs have not been systematically investigated, so this study presents a web-based survey study among three nations: Republic of Korea, Peoples Republic of China, and the United States of America. It was assumed that SNS users form bridging and bonding social capital (borrowed from social capital theory) through the five functions of SNS that were categorized: Identity, Expert Search, Connection, Communication, and Contents Sharing. A correlation between social capital-related activities and usage patterns of SNS was expected. A total of 489 responded to the web-based survey through the three counties. Although the theory of cultural differences turned out to be insufficient to explain diverse usage patterns of SNSs, the results showed that Korean and Chinese users form bridging and bonding social capital mainly through Expert Search and Connection functions, but American users mainly use the Communication function to form bonding Social Capital. Various implications of these results for researchers and practitioners who work on and for SNSs are described as well.

A Usability Checklist for the Usability Evaluation of Mobile Phone User Interface

In the last decade, the research of the usability of mobile phones has been a newly evolving area with few established methodologies and realistic practices that ensure capturing usability in evaluation. Thus, there exists growing demand to explore appropriate evaluation methodologies that evaluate the usability of mobile phones quickly as well as comprehensively. This study aims to develop a task-based usability checklist based on heuristic evaluations in views of mobile phone user interface (UI) practitioners. A hierarchical structure of UI design elements and usability principles related to mobile phones were developed and then utilized to develop the checklist. To demonstrate the practical effectiveness of the proposed checklist, comparative experiments were conducted on the usability checklist and usability testing. The majority of usability problems found by usability testing and additional problems were discovered by the proposed checklist. It is expected that the usability checklist proposed in this study could be used quickly and efficiently by usability practitioners to evaluate the mobile phone UI in the middle of the mobile phone development process.

A Study of Pointing Performance of Elderly Users on Smartphones

The number of global smartphone users is rapidly increasing. However, the proportion of elderly persons using smartphones is lower than that of other age groups because they feel it is difficult to use touch screens. There have only been a few studies about usability and elderly smartphone users or designs for them. Based on this background, we studied the pointing action of elderly users, which is a basic skill required to use touch screens on smartphones. We reviewed previous works to determine specific research methods and categorized them into three groups: (a) effect of target size and spacing on touch screen pointing performance, (b) effect of age on pointing performance, and (c) feedback of touch screens. To investigate the touch screen pointing performance of elderly, we conducted two experiments. In the first experiment, 3 target sizes (5 mm, 8 mm, and 12 mm) and 2 target spacings (1 mm, 3 mm) were evaluated. Adding to that, we analyzed whether touch screen pointing performance is dependent on the location of the target. In the second experiment, 3 types of feedback (auditory, tactile, and audiotactile) were evaluated. The results show that (a) pointing performance of elderly was significantly influenced by size, spacing, and location of target, and (b) the performance was higher in audiotactile feedback condition. We expected that these results can contribute to the design of smartphone applications for elderly users.

Investigating the Importance of Trust on Adopting an Autonomous Vehicle

The objective of this study is to examine the user’s adoption aspects of autonomous vehicle, as well as to investigate what factors drive people to trust an autonomous vehicle. A model explaining the impact of different factors on autonomous vehicles’ intention is developed based on the technology acceptance model and trust theory. A survey of 552 drivers was conducted and the results were analyzed using partial least squares. The results demonstrated that perceived usefulness and trust are major important determinants of intention to use autonomous vehicles. The results also show that three constructs—system transparency, technical competence, and situation management—have a positive effect on trust. The study identified that trust has a negative effect on perceived risk. Among the driving-related personality traits, locus of control has significant effects on behavioral intention, whereas sensation seeking did not. This study investigated that the developed model explains the factors that influence the acceptance of autonomous vehicle. The results of this study provide evidence on the importance of trust in the user’s acceptance of an autonomous vehicle.

Usability risk level evaluation for physical user interface of mobile phone

The mobile phone has become an indispensable device in everyday life. However, many usability problems were generated by the multi-functionality of mobile phones. There was an important increase on the user interface (UI) design and usability. With the introduction of a variety of forms and keypads in mobile phones, the users need of controllability, grip-stability, and usability were raised in the UI aspect. Therefore, in this study, we investigated the physical user interface (PUI) elements of mobile phones, and defined the degree of usability risk such as key level value, function level value, and grip level value. Also, this study proposed an evaluation framework to quantitatively measure the usability risk in the mobile phone PUI elements. For this, the mobile phone PUI elements were analyzed and classified by key type, function, and form-factor. Hence, in the case study was investigated and evaluated 133 mobile phones in the market by the proposed framework. As a result, the proposed evaluation framework enabled the measurement of the mobile phone usability risk level in the early stages of the concept design. This made possible the prediction of design problems related with the mobile phone PUI.

Perceived Visual Complexity and Visual Search Performance of Automotive Instrument Cluster: A Quantitative Measurement Study

Advancements in technology have spurred the development of new in-vehicle applications. Drivers are faced with different driving contexts due to an increase in the number of devices that provide a wealth of diverse information. However, such a scenario can cause drivers to become distracted. Therefore, research on how the presentation of visual information can affect drivers’ performance is important. In this study, an analysis of quantifiable measurements that affect drivers’ perception of visual complexity and visual search performance was conducted. A questionnaire was administered to assess subjective perception of visual complexity, and a user experiment using eye tracking was designed to explore participants’ visual search performance. The results of subjective visual complexity perception and visual search performance suggested that some objective measurement variables were significantly related only to perceived visual complexity, whereas others affected both subjective and behavioral measurements. Thus it is possible to predict which quantifiable measurement variables affect subjective perception of visual complexity and which affect visual search performance. Therefore, this study allows understanding and explaining of perception of visual complexity by quantifiable measurements and the different ways by which these measurements affect visual search performance.

Development of the Conceptual Prototype for Haptic Interface on the Telematics System

Driver safety and workload have become a crucial issue as the telematics system has evolved in a complex manner. To solve this problem, the aim of this study is to develop a conceptual prototype that supports haptic interface, an eye-free technology, with free navigation based on the users mental model. The conceptual prototype for haptic interface is established through identifying the problems with previous haptic interface devices and defining functional requirements for the next generation telematics system. In addition, 25 criteria for a haptic device design are identified and applied to evaluate the conceptual prototype. These criteria are classified in a hierarchical order, and an Analytic Hierarchy Process (AHP) evaluation model is constructed accordingly. The AHP evaluation framework reveals critical factors as well as the degree of importance in designing the haptic device. As a result, an evaluation method has been developed for the prototype of the early phase of the haptic device design.

Assessment model for perceived visual complexity of automotive instrument cluster

This research proposes an assessment model for quantifying the perceived visual complexity (PVC) of an in-vehicle instrument cluster. An initial study was conducted to investigate the possibility of evaluating the PVC of an in-vehicle instrument cluster by estimating and analyzing the complexity of its individual components. However, this approach was only partially successful, because it did not take into account the combination of the different components with random levels of complexity to form one visual display. Therefore, a second study was conducted focusing on the effect of combining the different components. The results from the overall research enabled us to suggest a basis for quantifying the PVC of an in-vehicle instrument cluster based both on the PVCs of its components and on the integration effect.

Effects of Superimposition of a Head-Up Display on Driving Performance and Glance Behavior in the Elderly

A vehicle head-up display (HUD) has a semitransparent property that utilizes a method of projecting light onto the windshield. The semitransparent characteristic of the HUD generates continuous superimposition between the “HUD graphic” and “road environment events.” This study aims to determine the effects of HUD use on elderly driving. Two age groups (elderly, younger) performed tasks (speed monitoring, navigation) utilizing two types of display (HUD, head-down display) in two different circumstances (high superimposition level, low superimposition level). Subject performance was evaluated by having the subjects execute a secondary display task while performing a primary driving task with an eye-tracking task. In addition, the degree of driver visual distraction was verified through the measurement of display glance duration. The results showed that an increase in superimposition negatively affected driver glance duration independent of age. However, the use of HUD in low superimposition situations showed relative advantages with regard to display use independent of age. This study confirmed that the negative effects of HUD use need to be considered during the selection of HUD information and display location. In particular, this study verifies that special attention should be given to the negative effects of superimposition of text information for use by an elderly population.

How we can measure the non-driving-task engagement in automated driving: Comparing flow experience and workload

In automated driving, a driver can completely concentrate on non-driving-related tasks (NDRTs). This study investigated the flow experience of a driver who concentrated on NDRTs and tasks that induce mental workload under conditional automation. Participants performed NDRTs under different demand levels: a balanced demand-skill level (fit condition) to induce flow, low-demand level to induce boredom, and high-demand level to induce anxiety. In addition, they performed the additional N-Back task, which artificially induces mental workload. The results showed participants had the longest reaction time when they indicated the highest flow score, and had the longest gaze-on time, road-fixation time, hands-on time, and take-over time under the fit condition. Significant differences were not observed in the driver reaction times in the fit condition and the additional N-Back task, indicating that performing NDRTs that induce a high flow experience could influence driver reaction time similar to performing tasks with a high mental workload.