Kyungdoh Kim

The relation between usability and product success in cell phones

The cell phone is not a simple communication tool. People use embedded mobile phone features such as games, cameras and wireless internet for various purposes of entertainment and shopping. In some cases usability problems impact negatively on product success, whereas in other cases they do not. The objective of our study was to develop a questionnaire for cell phones and investigate the relation between usability and product success. We reviewed existing usability studies and factors for product success to develop the questionnaire for cell phones. Subjects then evaluated the usability and success factors of cell phones. Finally, re-purchase intention and success scores including usability scores were analysed to determine whether they are positively related and which usability factors impact cell phone product success. Design, customer needs and innovativeness of cell phones were especially important among success factors, whereas more attention should be paid to satisfaction, feedback and efficiency among the usability dimensions.

Menu Design for Computers and Cell Phones: Review and Reappraisal

Menu systems have been key components in modern graphical user interfaces, and there has been a lot of research about menu design. Menu design features play a significant role from the perspective of customer satisfaction. Therefore, researchers have investigated various features in menu design. 3D menus have been investigated because these can display more items and provide a natural and intuitive interface. Small screens of the type used on mobile phones are limited in the amount of available space, and thus it might be more beneficial to use 3D menus in cell phones. A review of previous menu design studies for human–computer interaction suggests that menu design guidelines for computers and mobile phones need to be reappraised, especially toward the use of 3D interfaces in cell phones. The main objective of this article is to propose an overall framework for 3D menu interfaces in cell phones. The second objective is to propose guidelines for 2D and 3D menu design in computers and cell phones based on a literature review. Three main factors that might influence the performance of menu retrieval task in cell phones are included in the proposed model: the presentation type, the number of items, and menu type.

Comparison of 3D and 2D menus for cell phones

Few prior studies have directly compared 3D and 2D menus for cell phones. Because the technology available for cell phone interfaces has changed in recent years, interface guidelines for cell phones need to be re-evaluated, especially with regard to the use of 3D interfaces. In the present study, we first compared performance of tasks for menus with different breadths using three 3D menus (revolving stage, 3D carousel, and collapsible cylindrical tree) shown on the small display screen of an iPhone(R) simulator. Performance was best with the revolving stage menu, and there was a nonsignificant tendency for it to be rated as preferred by the participants. Then, we compared the 3D revolving stage menu to a 2D overview menu, for tasks of different complexity and menus of different breadths, on an actual iPhone. The 3D menu was preferred by users at high breadth levels, and the 2D menu showed better performance than the 3D menu with low memory load. From the results, recommendations for the design of menus for small displays were developed.

Menu Design in Cell Phones: Use of 3D Menus

The number of mobile phone users has been steadily increasing due to the development of microtechnology and human needs for ubiquitous communication. Menu design features play a significant role in cell phone design from the perspective of customer satisfaction. Moreover, small screens of the type used on mobile phones are limited in the amount of available space. Therefore, it is important to obtain good menu design. Review of previous menu design studies for human-computer interaction suggests that design guidelines for mobile phones need to be reappraised, especially 3D display features. We propose a conceptual model for cell phone menu design with 3D displays. The three main factors included in the model are: the number of items, task complexity, and task type.

Intelligent contingent multi-sourcing model for resilient supply networks

We develop an intelligent contingent multi-sourcing model when disruptions occur.We evaluate the performance of our model in terms of lost sale and total cost.We analyze the performance of our model under various costs and disruption rates.Our model performs at least equal to or better than single sourcing.Our model also outperforms constant multi-sourcing under specific conditions. As the complexity and uncertainty of supply networks (SNs) increase, strategic management for resilient SNs becomes significant. An intelligent contingency plan, rather than a direct and constant back-up plan, is more suitable for flexible and effective management. In this research, we introduce a unique contingent multi-sourcing decision protocol for effective response when disruptions occur. It is called the Intelligent Contingent Sourcing (ICS) protocol. Unlike previous research, which has mostly considered the constant multi-sourcing11In this paper, constant multi-sourcing means that each manufacturer is supplied from only pre-determined suppliers and the amount of materials supplied from each of them is fixed. Only disrupted supplier cannot supply until recovery is finished. On the other hand, in case of contingent multi-sourcing, the suppliers and the amount of materials supplied can be changed according to the current condition. among internal suppliers, our model is developed for contingent multi-sourcing by collaboration with external suppliers. (When both the supplier and buyer are managed/controlled by the same company, that supplier is considered an internal supplier; in case each supplier is independent in terms of buyers and is self-interested, such supplier is considered an external supplier). Such contingent multi-sourcing requires the theoretical analysis of each participants economic aspect, because each external supplier is independent and thus self-interested. The ICS protocol forms a contingent collaborative coalition based on a distributed decision making process. To evaluate the performance of the ICS protocol, three sourcing models are compared: (1) Single sourcing, (2) Constant multi-sourcing, and (3) Contingent multi-sourcing by the ICS protocol. Statistical analysis reveals that, with statistical significance, the ICS protocol performs at least equal to or better than single sourcing, in terms of less lost sales and less total costs; ICS protocol also outperforms constant multi-sourcing under specific conditions (stated in the article).

Network structure-aware ant-based routing in large-scale wireless sensor networks

Routing algorithms for large-scale sensor networks should be capable of finding energy efficient paths to prolong the lifetime of the networks in a decentralized manner. With this respect, Ant System has several proper characteristics for routing algorithm in large-scale wireless sensor networks. First, its distributed mechanism enables routing algorithm to find a solution with only local information and be robust for uncertainties in wireless sensor networks. Second, the framework of the Ant System is proper to solve dynamic problems such as routing problem. Transition probability in Ant System can be used to estimate how good a given routing path is. Capturing these features, this work proposes two Ant Systems based routing algorithms, which are AS-RWSNs (Ant System for Routing in Wireless Sensor Networks) and SAAS-RWSN (Structure-Aware AS-RWSN). The AS-RWSN applies the original Ant System to routing algorithm for wireless sensor network and SAAS-RSN upgrades AS-RWSN with considering properties of network structure such as degree of node. In SAAS-RSN, sensors with high node degree have high data traffic since they have more routing paths. Consequently, SAAS-RSN achieves an energy balance over sensor network through this routing scheme. We demonstrate the effectiveness of the proposed algorithms by comparing three existing routing algorithms.

Comparison between Overview Menu and Text Menu in Smartphone

Objective: This study determines which of two types of 2D menu is better on iPhone. Background: Menu systems have been important components in modern graphical user interfaces. Review of menu design studies for human-computer interaction suggests that menu design guidelines for smartphones need to be reappraised. Method: A nested factorial design was used. Twenty-four participants were divided into two groups. The subjects were nested within the menu type. Two types of menus are an overview menu and a text menu. Two different breadth levels are 16 and 64. The participants performed five tasks in each breadth level. A task is defined as locating a product or product class on the deepest level of the hierarchy. An Apple iPhone 2G was used. Results: The results for ANOVA indicated a lack of a significant difference for time to respond between the two types of 2D menus. The overview menu showed the better satisfaction score between the two menu types. Conclusion: Even though the differences were not significant, an overview menu tended to show better performance and preference scores than a text menu that required scrolling. Application: This study can provide menu design guidelines when 2D menus are considered for small displays in a high breadth level.

Comparison of Mobile Web Browsers for Smartphones

ABSTRACT Previous studies on mobile Web browsers have focused on phone features and technical performance, but not on the user interface. In this study, we compared three mobile Web browsers in the iPhone and ultimately proposed recommendations for the design of mobile Web browsers for smartphones. To develop such recommendations, we redefined the user interface (UI) components of mobile Web browsers from previous studies to conform to smartphones and compared the Chrome, Safari, and Opera Mini-browsers. To do this, we conducted experiments on usability tests with several dependent variables, including usefulness, perceived time reduction, minimal action, usability, ease to memorize, learnability, fun, and satisfaction. Finally, we developed several recommendations, based on the experimental results and participant interviews, which will fulfill user needs for the interface design of mobile Web browsers for smartphones. Multi-windows need to be implemented in a 3D environment. Developers should consider UI components and features that ease learning how to use the browser for novice users.

Usability evaluation of menu interfaces for smartwatches

ABSTRACT Currently, there are various smartwatch products on the market, and the number of users is expected to continue to increase. The functions of smartwatches have also been diversified, and the amount of information displayed on their screens is also increasing. However, as there are many restrictions on the rather small screen size, it is difficult to apply the methods used to provide information on the existing smart devices. Therefore, this study investigated how menu should be provided on the touch screen of smartwatches and derived a more effective menu structure. For our purposes, we conducted two experiments. In the first experiment, we provided 40 items in grid view and list view layout styles and tried to search for a given item by scrolling or paging. Efficiency was higher for the list view layout, in which many items were displayed on the screen and task completion time was shortened. However, the overall satisfaction was higher for the grid view layout, in which fewer items were displayed on the screen. In the second experiment, we derived an efficient menu structure when displaying hierarchical items that could be grouped into upper and lower categories. Likewise, many items on a single screen were excellent in terms of task completion time and efficiency. Providing depth of menu by categorization showed satisfactory results in task completion time, efficiency, and overall satisfaction.

Design and Evaluation of an Assistive Window for Soft Keyboards of Tablet PCs that Reduces Visual Attention Shifts

In general, soft keyboards are used for tablet PCs much as they are for smartphones. However, since the screen size is larger than for smartphones, user gaze is dispersed. In this paper, we propose a new keyboard for tablet PCs, in which an assistive window is introduced to decrease visual shifts, and evaluate the usability and usefulness of the keyboard. Results of an experiment are reported confirming that the gaze dispersion showed a reduction of 90% compared to an existing keyboard, although the typing error rates and typing time did not greatly improve. These results indicate a way to reduce visual dispersions on larger screen devices.