• Journal of Information Technology Services
• /
• v.19 no.2
• /
• pp.69-82
• /
• 2020

In the growth of IT industry, interest in wearable device has been globally rising along with the evolution of technology. A Smartwatch is expected to be at the center of wearable device industry in the future. However, there are some concerns that most of its actual sales are caused by gifts or bundling. Motivated by these issues, this study propounds the ideas that to enter the mainstream market, the empirical research is required for actual consumers who continue to use a smartwatch. The purpose of this study is to identify key factors affecting user satisfaction and antecedents affecting continuance intention to use from consumer perspectives. Further, assuming consumers' perceptions will be different according to how they acquired smartwatch, this study classified the group as direct buyers and acquired users. To achieve the purpose of the research, this study analyzes the usage of smartwatch by integrating the IS Success Model and IS Continuance and Habit Theory. We implemented the survey of 338 smartwatch users, and the research findings indicate that information quality and system quality have significant effects on satisfaction, and consequently satisfaction and habit positively affect the continuance intention to use. Additionally, it is found that there was a significant difference in the relationship between satisfaction and habit in the group divided by acquisition type. Based on these findings, this study provides theoretical and practical implications.

• Journal of Educational Research in Mathematics
• /
• v.9 no.1
• /
• pp.245-261
• /
• 1999

Proof is an essential characteristic of mathematics and as such should be a key component in mathematics education. But, teaching proof in school mathematics have been unsuccessful for many students. The traditional approach to proofs stresses formal logic and rigorous proof. Thus, most students have difficulties of the concept of proof and students' experiences with proof do not seem meaningful to them. However, different views of proof were asserted in the reassessment of the foundations of mathematics and the nature of mathematical truth. These different views of justification need to be reflected in demonstrative geometry classes. The purpose of this study is to characterize the types of students' justification in demonstrative geometry classes taught using dynamic software. The types of justification can be organized into three categories : empirical justification, deductive justification, and authoritarian justification. Empirical justification are based on evidence from examples, whereas deductive justification are based logical reasoning. If we assume that a strong understanding of demonstrative geometry is shown when empirical justification and deductive justification coexist and benefit from each other, then students' justification should not only some empirical basis but also use chains of deductive reasoning. Thus, interaction between empirical and deductive justification is important. Dynamic geometry software can be used to design the approach to justification that can be successful in moving students toward meaningful justification of ideas. Interactive geometry software can connect visual and empirical justification to higher levels of geometric justification with logical arguments in formal proof.

• Journal of Educational Research in Mathematics
• /
• v.23 no.4
• /
• pp.449-466
• /
• 2013

Mathematical discussion has been highlighted so that what students do actually guides their learning of mathematics and mathematical practice. However, the work of leading mathematical discussions has not yet been specified in such a way that it can be adequately studied and taught to teachers. This study analyzes a teacher's lessons that show full engagement in leading discussions, and examines the work of leading mathematical discussions in elementary classrooms. It identifies and illustrates the central tasks of leading mathematical discussions with single case questions with five steps. This article argues several key issues in leading mathematical discussions: helping students engage in struggling with important mathematical ideas, treating mathematical connections in an explicit and public way to have coherent and structured discussions, and parsing the work of teaching at a grain size that is usable in educating teachers.

• Ceramist
• /
• v.22 no.1
• /
• pp.36-55
• /
• 2019

Atomically thin two-dimensional (2D) nanomaterials, including transition metal dichalcogenides (TMDs), graphene, boron nitride, and black phosphorus, have opened up new opportunities for the next generation optoelectronics owing to their unique properties such as high absorbance coefficient, high carrier mobility, tunable band gap, strong light-matter interaction, and flexibility. In this review, photodetectors based on 2D nanomaterials are classified with respect to critical element technology (e.g., active channel, contact, interface, and passivation). We discuss key ideas for improving the performance of the 2D photodetectors. In addition, figure-of-merits (responsivity, detectivity, response speed, and wavelength spectrum range) are compared to evaluate the performance of diverse 2D photodetectors. In order to achieve highly reliable 2D photodetectors, in-depth studies on material synthesis, device structure, and integration process are still essential. We hope that this review article is able to render the inspiration for the breakthrough of the 2D photodetector research field.

• Journal of the Ergonomics Society of Korea
• /
• v.35 no.2
• /
• pp.75-84
• /
• 2016

Objective: The aim of this study is to suggest some improvement ideas based on the validity and the reliability analyses of the current safety culture measurement method applied to the Korean nuclear power industry. Background: Wrong safety culture is known as one of the major causes of the disasters such as the space shuttle Columbia disaster or the Fukushima Nuclear Power Plant accident. Assessment of safety culture of an organization is important to build a safer organizational environment as well as to identify the risks hidden in the organization. Method: A face validity of the current safety culture measurement method was analyzed by comparison of the key factors of safety culture in the Korean nuclear power industry with those factors reviewed in the previous studies. The current interview method was analyzed to identify the problems which degrade the consistency of evaluation. Results: Most safety culture factors reviewed in the literatures are covered in the list of the Korean nuclear power industry safety culture factors. However the unstructured questions used in the interview may result in inconsistency of safety culture evaluation among interviewers. Conclusion: This study suggests some examples which might improve the consistency of interviewers' evaluation on safety culture such as a post interview evaluation form. Application: An extended post interview evaluation form might help to increase the accuracy of the interviewing method for Korean nuclear industry safety culture evaluation.

• Electronics and Telecommunications Trends
• /
• v.33 no.5
• /
• pp.64-75
• /
• 2018

People usually check their social media, e-mail, and online news on their smartphones using their carrier network. During this process, much of the data traffic is offloaded to ubiquitous Wi-Fi networks. Such offloading will continue to increase rapidly because of flourishing public Wi-Fi networks located around the world. In this technical report, we first investigate domestic public Wi-Fi projects, and followed by foreign projects. In addition, we investigate the Wi-Fi technology evolution that has been standardized in IEEE 802. More and more people are tending to use Wi-Fi, not only at home or work, but also on public transport such as buses and trains. Hence, it is important to come up with ideas that can realize Wi-Fi onboard. The key technologies needed here are related to a mobile wireless backhaul between trains and trackside radio equipment, or between buses and roadside units. Thus, we also investigate the mobile wireless backhaul technologies and their trends.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.64 no.3
• /
• pp.451-457
• /
• 2015

In this paper, we consider the observer design problem that truly reflects the nonlinear stiffness of the manipulators. The two key ideas of our design are that (a) estimation error dynamics of the manipulator equipped with accelerometer dose not dependent on nonlinearities at the link part, when the measured signals are the motor position and the output of the accelerometer and (b) the nonlinear stiffness is indeed a Lipschitz function. In order to effectively compensate the nonlinear stiffness, the gain of the proposed observer is carefully chosen from the ARE(algebraic Riccati equations) which depend on Lipschitz constant. Comparative simulation result verifies the effectiveness of the proposed solution.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.65 no.2
• /
• pp.342-348
• /
• 2016

We propose an obstacle detection algorithm for unmanned ground vehicle on uneven terrain. The key ideas of the proposed algorithm are the use of two-layer laser range data to calculate the gradient of a target, which is characterized as either ground or obstacles. The proposed obstacle detection algorithm includes 4-steps: 1) Obtain the distance data for each angle from multiple lidars or a multi-layer scan lidar. 2) Calcualate the gradient for each angle of the uneven terrain. 3) Determine ground or obstacle for each angle on the basis of reference gradient. 4) Generate a new distance data for each angle for a virtual laser scanner. The proposed algorithm is verified by various experiments.

• Journal of English Language & Literature
• /
• v.64 no.2
• /
• pp.151-170
• /
• 2018

This paper examines the relationship and ideas of Hannah Arendt and Philip Roth including how they met, their correspondence and intellectual parallels, particularly in their shared criticism of Jewish ideals and culture in Europe and North America. It analyzes similarities in their careers and texts, especially between Eichmann in Jerusalem and Operation Shylock, as well as The Ghost Writer, while measuring their reception as social commentators and writers. Kafka was an important figure for both writers, Arendt's earliest writing engaged with the significance of Kafka in understanding and criticizing twentieth century political and cultural values in Europe. For Roth, Kafka offered a similar critique of moral principles he found corroded in North American Jewish life. Arendt connected with other writers, notably Isak Dinesen, W. H. Auden, Randall Jarrell and William Styron who further linked the two: he knew both Arendt and Roth and cited, incorrectly, a work by Arendt as the source for the key incident in his 1979 novel Sophie's Choice. He claimed it was Eichmann in Jerusalem; it was Arendt's The Origins of Totalitarianism. Arendt's reaction to Roth's fiction, however, remains a mystery: she died in 1975, before Roth began to seriously and consistently engage with Holocaust issues in works like The Ghost Writer (1979) and Operation Shylock (1993). Yet even in death they are joined. Their graves are only steps apart at the Bard College Cemetery in Annandale-on-Hudson, New York.

• The Journal of Korea Robotics Society
• /
• v.14 no.4
• /
• pp.285-292
• /
• 2019

Path planning is an important problem to solve in robotics and there has been many related studies so far. In the previous research, we proposed the Heterogeneous-Ants-Based Path Planner (HAB-PP) for the global path planning of mobile robots. The conventional path planners using grid map had discrete state transitions that constrain the only movement of an agent to multiples of 45 degrees. The HAB-PP provided the smoother path using the heterogeneous ants unlike the conventional path planners based on Ant Colony Optimization (ACO) algorithm. The planner, however, has the problem that the optimization of the path once found is fast but it takes a lot of time to find the first path to the goal point. Also, the HAB-PP often falls into a local optimum solution. To solve these problems, this paper proposes an improved ant-inspired path planner using the Rapidly-exploring Random Tree-star ($RRT^*$). The key ideas are to use $RRT^*$ as the characteristic of another heterogeneous ant and to share the information for the found path through the pheromone field. The comparative simulations with several scenarios verify the performance of the improved HAB-PP.