Joonhwan Lee

Variable Speed Engine Generator with Super-Capacitor; Isolated Power Generation System and Fuel Efficiency

A variable-speed engine generator set for an isolated power system is investigated due to reduced fuel consumption and less emission. However, because of the sluggish dynamic behavior of the internal combustion engine, the power quality would be degraded during the sudden load power surge, where the power required by the load is not available by the engine because of the reduced engine speed. An isolated power system based on a variable-speed engine with a supercapacitor bank can improve the dynamic characteristics under such a sudden load change, and power quality, fuel consumption, and emission of pollutants can be improved remarkably. Furthermore, it is verified by the computer simulation and experimental results that the three-phase four-leg inverter is compatible to the isolated power system with an unbalanced load. In this paper, the feasibility of the system has been verified based on a 26-kW commercial diesel engine system.

Iterative design of MOVE: A situationally appropriate vehicle navigation system

Drivers need assistance when navigating an unfamiliar route. In-vehicle navigation systems have improved in recent years due to the technology advances, but are sometimes problematic because of information overload while driving. To address the attentional demands of reading a map while driving, we have developed the maps optimized for vehicular environments (MOVE) in-car navigation display, which provides situationally appropriate navigation information to the driver through optimization of map information. In this paper, we describe the iterative design and evaluation process that shaped the MOVE system. We describe early map reading and navigation studies that led to early designs for our system. We present a study on visual search tasks that refined the renditions used for the system. Finally, we present a study on the effectiveness of several variations of a contextually optimized route map visualization with a desktop steering system. The result of this study shows that MOVEs contextually optimized navigation information can reduce the drivers perceptual load significantly. Our laboratory experiment shows that the total map display fixation time was decreased six-fold, and the number of glances to interpret the map display were decreased about threefold, when comparing the contextually optimized display to a static display.

Studying the effectiveness of MOVE: a contextually optimized in-vehicle navigation system

In-vehicle navigation has changed substantially in recent years, due to the advent of computer generated maps and directions. However, these maps are still problematic, due to a mismatch between the complexity of the maps and the attentional demands of driving. In response to this problem, we are developing the MOVE (Maps Optimized for Vehicular Environments) system. This system will provide situationally appropriate map information by presenting information that uses appropriate amounts of the drivers attention. In this paper, we describe our findings of studies to help shape the design of the MOVE system, including studies on map reading and in-vehicle navigation, and studies on the effectiveness of a variety of contextually optimized route map visualizations in a simulated driving context.Results show that contextually optimized displays designed for the MOVE system should significantly reduce perceptual load in the context of driving. In our laboratory experiment there was a six-fold decrease in the total map display fixation time and nearly threefold decrease in the number of glances needed to interpret the contextually optimized display compared to a static display.

Usability of car dashboard displays for elder drivers

The elder population is rising worldwide; in the US, no longer being able to drive is a significant marker of loss of independence. One of the approaches to helping elders drive more safely is to investigate the use of automotive user interface technology, and specifically, to explore the instrument panel (IP) display design to help attract and manage attention and make information easier to interpret. In this paper, we explore the premise that dashboard displays can be better designed to support elder drivers, their information needs, and their cognitive capabilities. We conducted a study to understand which display design features are critically linked to issues of divided attention and driving performance. We found that contrast of size and reduced clutter are instrumental in enhancing driving performance, particularly for the elder population. Surprisingly, our results showed that color elements have a negative effect on driving performance for elders, while color elements and fills slightly improve performance. We conclude with design implications generated from this work.

Design of Speed Control Loop of A Variable Speed Diesel Engine Generator by Electric Governor

Electric governors are widely used in diesel engine applications. And a proportional, integral and derivative(PED) controllers runs the electric governor in order to control the engine speed. However, it is difficult to analyze the system stability due to the non-linear characteristics of the diesel engine, and as a result, the PID controller should be tuned by trial-and-error approach. In this paper, a locally linearized diesel engine model is proposed based on the experimentally obtained engine torque map, and the proposed model is verified by simulations and experiments. Through the simulations and experiments it is concluded that the proposed model can be used in the system analysis and so to determine the PID controller gains.

A Framework for Assessment of Student Project Groups On-Line and Off-Line

Assessment of difficulties within group processes, especially through automatic means, is a problem of great interest to the broader CSCL community. Group difficulties can be revealed through interaction processes that occur during group work. Whether these patterns are encoded in speech recorded from face-to-face interactions or in text from on-line interactions, the language communication that flows between group members is an important key to understanding how better to support group functions and therefore be in a better position to design effective group learning environments. With the capability of monitoring and then influencing group processes when problems are detected, it is possible to intervene in order to facilitate the accomplishment of a higher quality product. In this chapter we address this research problem of monitoring group work processes in a context where project course instructors are making assessments of student group work. Thus, our purpose is to support those instructors in their task. We describe the mixed methods approach that we took, which combines both an interview study and a classroom study. Three research questions are answered: (1) What do instructors want to know about their student groups? (2) Is the desired information observable, and can it be reliably tracked by human annotators? (3) Can the desired information be automatically tracked using machine learning techniques to produce a summary report that instructors can use? Based on interviews with nine instructors, we identified five process assessment categories with subcategories at the group and individual level: namely, goal setting, group and individual progress, knowledge contribution, participation, and teamwork. We verified that these assessment categories can be reliably coded during group meetings with a reliability of r = 0.80 at the group level and r = 0.64 at the individual level using carefully constructed human assessment instruments. We present work in progress towards automation of this assessment framework.

The System Diagrams: Shifting Perspectives

As society becomes increasingly saturated with information, the design of that information becomes ever more important. However, rather than reinforcing the agency of the user, many information design products limit one’s possibilities for action. Take bus route maps (Figure 1), for instance. No problems emerge when looking at each bus route separately, but when users try to compare them to one another, it is difficult to understand their relationship. Only scattered information is made available, so that users are unable to form a clear, holistic understanding of how the bus service operates. Consequently, if an unexpected delay in a bus service were to occur, passengers might not be able to find and take an alternate route. Although a variety of approaches are available to resolve this problem, using system diagrams is a method that allows information designers to consider the holistic context. It is necessary not only to understand the system itself but also to study diagrams as a means of effectively describing the system, which is abstract in nature. The use of diagrams is a key component in communicating the holistic structure of an information system; however, a lack of rigorous discussion in the field means that designers often have difficulty examining systems as an integral part of their work. The purpose of this article is to provide a theoretical framework that broadens designers’ conception of system diagrams and enables them to design diagrams that can be effectively applied to various situations, needs, and design problems. In the first half of the article, we introduce four kinds of system diagrams and analyze different examples; the second half of the article focuses on how different modes of thinking are used to address varied needs and goals in the design process.

Ubi-jector: an information-sharing workspace in casual places using mobile devices

The widespread use of mobile devices has transformed casual places into meeting places. However, in these places, it is uncommon to have shared information workspace such as a beam projector, making it inconvenient and inefficient to exchange information and to get a direct feedback. To address this challenge, we present Ubi-jector, a mobile system that provides a shared information space that is equally distributed to each participants mobile device and allows group members to share documents and collaborate real-time. We first characterized the information sharing patterns and identified the limitations of the current practice in meeting places without a shared workspace, by conducting qualitative user studies. Next, we implemented Ubi-jector with the design guidelines drawn in the prior stage. Also, we performed an evaluation study that showed the possibilities of Ubi-jector to facilitate an effective information sharing and foster an active participation even in poorly-equipped environments.

Use of the Backseat Driving Technique in Evaluation of a Perceptually Optimized In-Car Navigation Display

Recently drivers have greatly benefited from new vehicular technologies such as in-car navigation systems, but at the same time they can be easily distracted from those technologies. Consequently, creating displays that balance the communication of information with the attentional demand imposed on the driver is of increasing importance. A set of research has been conducted to minimize the driver’s attentional cost toward the navigational displays while driving. However, accurate evaluation methods to assess the effects of these displays in realistic environments are not yet available. This article introduces the backseat driving technique for high-fidelity, safe, and inexpensive evaluation of interaction with in-car displays. This technique makes use of a real vehicle driving on a real road. As a result it allows for the exploration of some types of research questions using audio, visual, and kinesthetic stimulus at least equal in fidelity to very high-end driving simulators, without requiring such a specialized and expensive facility. Further, it allows for the employment of detailed and fine-grained measures of attentional demand, which cannot be safely used with subjects who are actually driving. Although the backseat driving technique can address only some types of questions and so is not a full replacement for high-realism driving simulators, it may offer a new approach, which augments laboratory, simulator, and real driving for many studies. As a part of the work presented here, the backseat driving technique is used to evaluate a previously developed in-car navigation display—the MOVE system. The technique allowed for new questions to be asked, which were not able to be considered in previous laboratory studies, and for the use of study measures that were only previously able to be used in the laboratory due to driving safety concerns. Specifically, the display was shown to work well when real-world stimulus are used to navigate along a real route, reducing the navigation error rate nearly threefold, and up to sixfold when compared to displays providing more or less contextual information. In addition the display was shown to cut total display fixation time (which is time spent looking away from the road) almost in half in both cases.

Eat What You Want and Be Healthy!: Comfort Food Effects: Human-Food Interaction in View of Celebratory Technology

Food craving is one of the fundamental desires of human nature. Many HCI researchers used to define this desire as a problem and has developed its corrective technology. However, positive aspects of food craving and food reward has rarely been in the scope of research. Few studies made its efforts to evaluate how food positively interacts with mental aspects of humans but have shown inconsistent results because of user subjectivity and environmental variations. Therefore, we have evaluated the human-food interactions with an EEG as objective indicator to track the mental activity. We found that when participants have a high craving for the certain food, which makes them feel comfort (hereafter comfort food), their working memory performance and related theta signal increase and stress related high beta signal decrease. The methodology adopted in this study will contribute to the progress in food-related celebratory technologies in HCI research field.