• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2415-2418
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• 2008

Polydiacetylenes (PDAs) are very attractive chemical substances which have distinctive features of color change and fluorescence emission by thermal or chemical stress. Especially, when PDAs contact with solutions of a particular pH, such as a strong alkaline sodium hydroxide (NaOH) solution or a strong acidic hydrogen chloride (HCl) solution, PDAs change their color from non-fluorescent blue to fluorescent red. In this study, we propose a novel method to detect alkaline pH using PDAs and NaOH solutions by hydrodynamic focusing on a microfluidic chip. Preliminary results indicate that the fluorescent intensity of PDAs increases in respond to the NaOH solution concentrations. Also, the fluorescence is quenched back when the PDAs are in contact with a HCl solution. These results are useful in a microfluidic PDA sensor chip design for pH detection.

• 디자인학연구
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• 제16권2호
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• pp.301-310
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• 2003

The interface design of mobile products has become a hot issue recently as a variety of products are being developed for extended usages. There have been two different views on interface design of mobile products like PDAs(personal digital assistants) or cellular phone. One 치aims that the current interface design of PC cannot be directly applied because mobile products have their own specific functions and requirements. On the meantime, the other argues that an extended application of PC metaphors to mobile products can have advantages because users'PC experiences can reduce the learning efforts and thus contribute to intuitive understanding mobile products. In this research, two types of PDAs, developed according to the aforementioned conflicting philosophies were compared and evaluated, based on laboratory-based usability testing conducted by novice users. The experiment consists of asking subjects to perform identical tasks for the two different types of products. The interaction data collected during usability testing were analyzed in terms of time taken, rate of success of tasks and errors. The experiment shows that there were some meaningful effects of users'experience of PC on the usability of PDAs.

• 대한산업공학회지
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• 제30권4호
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• pp.338-345
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• 2004

Personal Digital Assistants (PDAs) have become ubiquitous and continued to gain popularity. Since PDAs have some special contexts such as mobility and limited screen size, icons are utilized frequently because icons allow us to do tasks more rapidly and effectively on PDAs like another information appliances. The study presents a cognitive approach to study human factors affecting icon design with multidimensional Scaling (MDS) analysis. In the experiment, a real PDA was used to investigate 29 attributes and2 preference ratings for 22 PDA icons by 20 Korean subjects. As a result, cognitive positioning about icons, attributes, and preference data were arranged on the two dimensional perceptual map. Attributes were grouped by simplicity, universality, activity, complexity, abstraction, static, and alphanumeric time. Subjects preferences were highly related with simplicity attributes group and positive to universality and activity attributes groups. It was also confirmed that there are some icons unfitted to the mental model of Korean. However, when icons are designed for PDAs or similar information appliances to Korean, it should be designed simply and actively with universal image fitted on target users mental model.

• Nutrition Research and Practice
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• 제1권1호
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• pp.42-45
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• 2007

Rapid integration of information technology into health care systems has included the use of highly portable systems-in particular, personal digital assistants (PDAs). With their large built-in memories, fast processors, wireless connectivity, multimedia capacity, and large library of applications, PDAs have been widely adopted by physicians and nurses for patient tracking, disease management, medical references and drug information, enhancing quality of health care. Many health-related PDA applications are available to both dietetics professionals and clients. Dietetics professionals can effectively use PDAs for client tracking and support, accessing to hospital database or information, and providing better self-monitoring tools to clients. Internship programs for dietetics professionals should include training in the use of PDAs and their dietetics applications, so that new practitioners can stay abreast of this rapidly evolving technology. Several considerations to keep in mind in selecting a PDA and its applications are discussed.

• 대한인간공학회지
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• 제24권3호
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• pp.1-10
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• 2005

The primary objective of this study is to design input methods for assisting button selection tasks on a PDA screen. Familiar methods in the existing computing environments were investigated to develop aiding methods. Factors manipulated in the experiment included aiding method, button size, and users' prior experience with PDAs. A total of sixteen participants examined the usability of button selection tasks. Two types of button selection tasks were used as experimental tasks; one was selecting a target button, and the other was selecting multiple target buttons consecutively. The results showed that the aiding method and the button size had significant effects on the subjective satisfaction as well as the performance. In addition, users' prior experience with PDAs affected the performance significantly. The interaction between the aiding method and the button size was found to have significant effects on the performance. However, the interaction effect between the button size and the PDA experience was significant on the task performance time only for the multiple button selection tasks. Design considerations were proposed based on the experimental results. These can be applied to the PDA interaction design to make the PDAs more usable.

• Wind and Structures
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• 제38권1호
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• pp.15-42
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• 2024

A flexible-base coupled-two-beam (CTB) discrete model with equivalent tuned mass dampers is used to assess the effect of soil-structure interaction (SSI) and different types of lateral resisting systems on the design of passive dynamic absorbers (PDAs) under the action of along-wind and across-wind loads due to vortex shedding. A total of five different PDAs are considered in this study: (1) tuned mass damper (TMD), (2) circular tuned sloshing damper (C-TSD), (3) rectangular tuned sloshing damper (R-TSD), (4) two-way liquid damper (TWLD) and (5) pendulum tuned mass damper (PTMD). By modifying the non-dimensional lateral stiffness ratio, the CTB model can consider lateral deformations varying from those of a flexural cantilever beam to those of a shear cantilever beam. The Monte Carlo simulation method was used to generate along-wind and across-wind loads correlated along the height of a real shear wall-frame building, which has similar fundamental periods of vibration and different modes of lateral deformation in the xz and yz planes, respectively. Ambient vibration tests were conducted on the building to identify its real lateral behavior and thus choose the most suitable parameters for the CTB model. Both alongwind and across-wind responses of the 144-meter-tall building were computed considering four soil types (hard rock, dense soil, stiff soil and soft soil) and a single PDA on its top, that is, 96 time-history analyses were carried out to assess the effect of SSI and lateral resisting system on the PDAs design. Based on the parametric analyses, the response significantly increases as the soil flexibility increases for both type of lateral wind loads, particularly for flexural-type deformations. The results show a great effectiveness of PDAs in controlling across-wind peak displacements and both along-wind and across-wind RMS accelerations, on the contrary, PDAs were ineffective in controlling along-wind peak displacements on all soil types and different kind of lateral deformation. Generally speaking, the maximum possible value of the PDA mass efficiency index increases as the soil flexibility increases, on the contrary, it decreases as the non-dimensional lateral stiffness ratio of the building increases; therefore, there is a significant increase of the vibration control effectiveness of PDAs for lateral flexural-type deformations on soft soils.

• 대한인간공학회지
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• 제22권4호
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• pp.27-45
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• 2003

PDAs(Personal Digital Assistants), one of the typical mobile devices, are examined in this study to identify the factors affecting their usability. This study focuses on the menu design of PDAs. Three factors including menu extension method, menu structure, and screen orientation were manipulated in a usability experiment. Task completion times, error rates, and degree of subjective satisfaction were measured. Guidelines for designing a PDA menu are proposed based on the experimental results.

• 대한음성학회:학술대회논문집
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• 대한음성학회 2006년도 춘계 학술대회 발표논문집
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• pp.33-36
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• 2006

This paper describes a speech recognizer implemented on PDAs. The recognizer consists of feature extraction module, search module and utterance verification module. It can recognize 37 words that can be used in the telematics application and fixed-point operation is performed for real-time processing. Simulation results show that recognition accuracy is 94.5% for the in-vocabulary words and 56.8% for the out-of-task words.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2007년도 하계종합학술대회 논문집
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• pp.407-408
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• 2007

Robust pitch estimation is an important study in many areas of speech processing. In voice pathology, diverse statistics extracted form pitch were commonly used to test voice quality. In this study, we compared several established pitch detection algorithms (PDAs) for verification of adequacy of the PDAs. In the database of total pathological voices of 99 and normal voices of 30, an analysis of errors related with pitch detection was evaluated between pathological and normal voices, or among the types of pathological voices such as benign vocal fold lesions; polyp, nodule, and cysts. Consequently, it is required to survey the severity of tested voice in order to obtain accurate pitch estimates.

• 재활복지공학회논문지
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• 제4권1호
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• pp.63-70
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• 2010

시각장애인을 위한 보조공학(Assistive Technology : AT)의 연구개발은 보행과 정보 접근을 위한 것이 대부분이고, 특히 정보커뮤니케이션을 위한 음성도서용 DAISY플레이어나, 컴퓨터 화면을 읽어 주는 스크린 리더, 저시력자용 독서확대기, 점자 및 점자정보단말기 등이 상품화되어 오늘날 많은 시각장애인들에게 필수적인 보조공학기기로 자리 잡고있다. 시각장애인들이 사용하는 보조공학은 촉각이나 청각을 이용하여 시각 기능을 대행하기 때문에 감각대행기라고도 한다. 촉각을 이용한 감각대행기인 점자디스플레이와 점자정보단말기는 점자 형성을 위한 액츄에이터로 압전 소자로 만든 바이몰프가 사용되며, 점자셀의 점자(핀)는 바이몰프의 상하 운동에 의해 형성된다. 점자 셀은 휴대용 점자정보단말기에 사용되고 있기 때문에, 소형화 및 저가격화가 관건이 되며 현재는 일본의 KGS사가 세계 점자 셀(Cell) 시장의 80% 이상을 점유하고 있다. 본 연구진은 2003년에 저가/소형 원반형 점자디스플레이를 개발하여, 세계 최초로 제품화에도 성공한 바있다. 본고에서는 일본의 점자정보단말기를 비롯한 촉각디스플레이의 연구개발에 대해 검토하고 촉각을 이용한 감각대행 제품의 하나로서, 본 연구진이 개발한 원반형 점자디스플레이에 대해 고찰한다.