Hoo-Gon Choi

Braille display device using soft actuator

Tactile sensation is one of the most important sensory functions along with the auditory sensation for the visually impaired because it replaces the visual sensation of the persons with sight. In this paper, we present a tactile display device as a dynamic Braille display that is the unique tool for exchanging information among them. The proposed tactile cell of the Braille display is based on the dielectric elastomer and it has advantageous features over the existing ones with respect to intrinsic softness, ease of fabrication, cost effectiveness and miniaturization. We introduce a new idea for actuation and describe the actuating mechanism of the Braille pin in details capable of realizing the enhanced spatial density of the tactile cells. Finally, results of psychophysical experiments are given and its effectiveness is confirmed.

Step-based feature recognition for manufacturing cost optimization

This paper proposes to integrate feature recognition and process planning in the machining domain. The input part is analyzed to produce a set of setups which might be needed to manufacture the part. Then, a two-layered search strategy is adopted, where a node of the upper layer corresponds to a specific setup, and a node of the lower layer corresponds to a specific process for a feature. For each visited setup node, tool database is consulted in order to generate manufacturable features, feature dependencies are established, and the lower layer search is invoked. The lower layer computes an optimal machining sequence and its manufacturing cost. Then, the control gets returned to the upper layer. Together with the manufacturing cost computed at the lower layer, setup cost analysis guides the upper layers setup space search. Eventually, a setup sequence is generated where an optimal machining sequence is determined per each setup. The system presented in this paper uses STEP as input and output formats, and therefore can be ported to arbitrary CAD and planning systems.

Detection of ethanol gas concentration by fuel cell sensors fabricated using a solid polymer electrolyte

Abstract Fuel cells using a polymer electrolyte membrane were successfully fabricated and tested for the detection of ethanol gas concentration. Nafion 115 membrane was used for the polymer electrolyte and 10% Pt/C sheets with 0.5 mg/cm2 Pt loading were used as catalyst electrodes. The peak height of electrical signal obtained from the fuel cells was found to be quite linear with the ethanol gas concentration. The electrical signal from the fuel cells was found to show second-order characteristic with respect to the induced voltage from the transient behavior of the response decay. It could be attributed to the diffusion and reaction of ions in the polymer electrolyte, which would be the rate-controlling step among all the steps involved in the fuel cell operation.

A pair of Braille-based chord gloves

Keyboards have been used on typewriters and as input devices to computers and many keyboards have been proposed in order to improve their performance. Some glove-based input devices to computers have been also proposed for compactness and flexibility. In this paper, an input device to computers consisting of a pair of gloves is proposed. The keys of the proposed gloves are mounted on the fingers of gloves and their chording methods resemble those of a Braille keyboard. Since the Braille representation for numbers and characters is efficient and has been well established for every language, the proposed input device may be one of good input devices to computers. Furthermore, since the Braille has been used for visually impaired people, the proposed one can be easily used as an input device to computers for them.

Dry Type Conducting Polymer Actuator Based on Polypyrrole–NBR/Ionic Liquid System

The fabrication of dry type conducting polymer actuator was presented. In the preparation of actuator system, nitrile rubber (NBR) was used as a base material of the solid polymer electrolyte. Thin films of NBR (150 ∼ 200 µm) were prepared by compression molding process. The conducting polymer, polypyrrole(PPy) was synthesized on the surface of NBR by chemical oxidation polymerization technique, and the room temperature ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethyl sulfonyl)imide (BMITFSI) was introduced into the composite film. The cyclic voltammetry responses and the redox switching dynamics of PPy in NBR/ionic liquid solid polymer electrolyte were studied. The displacement of actuator was measured by laser beam.

A Pair of Wireless Braille-Based Chording Gloves

Since input devices for desktop computers are inconvenient to use in a mobile working environment, other small input devices have been proposed. Few of them, however, are for visually impaired people. This paper proposes a pair of wireless Braille-based chording gloves as an input device to use in a mobile working environment for visually impaired people. Its keys are mounted on the fingers and its chording method is similar to that of a Braille keyboard. Since Braille has been efficiently devised to represent many language characters, numbers, and symbols including mathematical and musical notations, the proposed chording gloves will be also used for visually non-impaired people. IrDA (Infrared Data Association) and RF (Radio Frequency) wireless modules are designed and implemented to make the proposed chording gloves wireless.

3D Virtual Knowledge Space for Collaboration in New Product Development Processes

The purpose of this article is to create a virtual knowledge space, K-SPACE (Knowledge Space), that enables communication and knowledge sharing between a business level and a plant level for mutual decision-making. Another purpose of a virtual knowledge space is to enable successful collaboration that ensures better quality while reducing costs and time by checking the task progress of departments participating in new product development (NPD) under the concurrent engineering (CE) paradigm. The Croquet software development kit is utilized to develop the knowledge space, which is a small-talk based, object-oriented language. The use of K-SPACE at enterprises that adapt the CE philosophy for NPD processes is expected to reduce both time and cost through fast, accurate, efficient, and collaborative decision making for various conflicting issues.

A discrete event simulation study for incoming call centers of a telecommunication service company

Call center becomes an important contact point, and an integral part of the majority of corporations. Managing a call center is a diverse challenge due to many complex factors. Improving performance of call centers is critical and valuable for providing better service. In this study we applied forecasting techniques to estimate incoming calls for a couple of call centers of a mobile telecommunication company. We also developed a simulation model to enhance performance of the call centers. The simulation study shows reduction in managing costs, and better customers satisfaction with the call centers.

Design of Chording Gloves as a Text Input Device

A chording input device for text input was developed in a Glove-typed interface using all the joints of the four fingers and thumbs of both hands. The glove-based device works for input of Korean characters as well as Roman- alphabet, Braille characters, and numbers using mode conversion among the respective keymaps. To minimize finger force and fatigue from repeated finger motions, input switch was made of conductible silicon ink, which is easy to apply to any type of surface, light, and enduring. The chording gloves showed comparable performances in Korean text input tasks with input keypads of mobile phones, but proved to be inferior to conventional keyboards. Subjects’ performance showed that the chording gloves can input approximately 108 characters per minute in Korean, but needs further ergonomic consideration to reduce keying errors. The chording gloves developed in the study can be used with common computing devices such as PCs and PDAs in mobile environments.

Principal parameters affecting R&D exploitation of nanotechnology research: a case for Korea

The purpose of this study is to determine principal parameters which affect the R&D exploitation and to explore R&D activities in closed science that positively affect those in open science. Based on 486 nanotechnology projects from five national R&D programs in South Korea, canonical correlation analysis is used to analyze the relationships among R&D parameters of inputs, outputs and outcomes and to determine principle parameters. As a result, this study concludes that the principal parameters are publications with high impact, patents, and academic degrees. This study also shows a positive correlation between activities in open science and closed science. The conclusions suggest that research results with high impact value should be endorsed by the Korean government and should try to keep a balance between R&D exploitation in open science and closed science. This study would be used for establishing South Korea’s R&D policy effective for faster commercialization of nanotechnology related research.