• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.43 no.1 s.343
• /
• pp.33-40
• /
• 2006

This paper presents a novel surface acoustic wave (SAW)-based pressure sensor, which is composed of single phase unidirectional transducer (SPUDT), three reflectors, and a deep etched substrate for bonding underneath the diaphragm. Using the coupling of modes (COM) theory, the SAW device was simulated, and the optimized design parameters were extracted. Finite Element Methods (FEM) was utilized to calculate the bending and stress/strain distribution on the diaphragm under a given pressure. Using extracted optimal design parameters, a 440 MHz reflective delay line on 41o YX LiNbO3 was developed. High S/N ratio, shan reflection peaks, and small spurious peaks were observed. The measured S11 results showed a good agreement with simulated results obtained from coupling-of-modes (COM) modeling and Finite Element Method (FEM) analysis.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.12 no.5
• /
• pp.787-794
• /
• 2001

In this paper, the development of large-signal model extractor for GaAs FET device through the Monolithic Microwave integrated Circuit(MMIC) is presented. The measurement program controlled by personal computer is developed for the processing of an amount of measured data, and the de-embedding algorithm is added to the program for voltage dropping as attached series resistance on measurement system. The small-signal model parameters are typically consisted of 7 elements that are considered as complexity of large-signal model and its the accuracy of the small-signal model is verified through comparing with measured data as varied bias point. The fitting function model, one of the empirical model, is used for quick simulation. In the process of large-signal model parameter extraction, one-dimensional optimization method is proposed and optimized parameters are extracted. This study can reduce the modeling and measuring time and can secure a suitable model for circuit.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.29 no.4
• /
• pp.250-254
• /
• 2016

Currently, power conversion system which converts AC to DC Power is applied in domestic urban railway. The diode rectifier is used in most of them. However the diode rectifier can not control the output voltage and can not regenerate power as well. On the other hand, PWM (pulse width modulation) converter using IGBT (isolated gate bipolar transistor) can control output voltage, allowing it to reduce the output voltage drop. Moreover the Bi-directional conduction regenerates power which does not require additional device for power regeneration control. This paper compared the simulation results for the DC power supply system on both the diode rectifier and the PWM converter. Under the same load condition, simulation circuit for each power supply system was constructed with the PSIM (performance simulation and modeling tool) software. The load condition was set according to the resistance value of the currently operating impedance of light rail line, and the line impedance was set according to the distance of each substations. The train was set using a passive resistor. PI (proportional integral) controller was applied to regulate the output voltage. PSIM simulation was conducted to verify that the PWM Converter was more efficient than the diode rectifier in DC Traction power supply system.

• Journal of the Korean Institute of Gas
• /
• v.13 no.3
• /
• pp.1-6
• /
• 2009

High pressure devices are used widely. Interest in rupture disc to people is the increases in protect of facilities and people. A rupture disc consists of mainly three parts: holder, plate and vacuum support. Rupture discs are rusted or destroyed by diverse environments. Rupture discs are made from STS 316L stainless steel because of its high corrosion resistance and yield strength. In this study, modeling of a rupture disc by CATIA V5 and finite element analysis by ANSYS were carried out. The finite element analysis results executed to predict properties of the rupture disc with thickness and height.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.23 no.5
• /
• pp.436-443
• /
• 2013

This paper presents design methods of a fuzzy controller and an operator model for a wire-driven heavy material lifting system helping human workers. The wire-driven heavy material lifting system is a kind of human-assistive systems in which a human is involved in the control loop. Thus, human's control characteristics and requirement of reducing worker's force to lift a heavy material are considered in the design process of the proposed fuzzy controller. An automatic weight measurement algorithm during the early stage of lifting is also introduced. Finally, the effectiveness and performance of the proposed system are proved by experiments.

• KIPS Transactions on Computer and Communication Systems
• /
• v.2 no.1
• /
• pp.1-6
• /
• 2013

Variety of smart devices including smart phone have become and essential item in user's daily life. This means that smart devices are good mediators to get collecting user's behavior by sensors mounted on the devices. The information from smart devices is important clues to identify by analyzing the user's preferences and needs. Through this, the intelligent service which is fitted to the user is possible. This paper propose a smart service recommendation model based on user scenario using fusion context-awareness. The information for recommendation services is collected to make the scenario depending on time, location, action based on the Fusion process. The scenarios can help predict a user's situation and provide the services in advance. Also, content categories as well as the content types are determined depending on the scenario. The scenario is a method for providing the best service as well as a basis for the user's situation. Using this method, proposing a smart service model with the fusion context-awareness based on the hybrid sensing is the goal of this paper.

• Journal of Internet Computing and Services
• /
• v.10 no.4
• /
• pp.127-138
• /
• 2009

Mobile web applications are being used and changed rapidly due to the growth of mobile device performance. But, cost of development environment and standards make the high development cost and low productivity. It is main reason that the design and implementation of the applications are more time consuming than general computing environments. In this paper, we propose MWeb(MobileWeb)-Framework based on the agile methodology and Ruby on Rails that is a kind of framework for supporting mobile web application development using mobile web standards. This work consists of the mobile web development architecture and agile process model. MWeb-Framework will support the same user experience to the different devices. We validates the framework by implementing the case studies through suggested mobile web development framework. As a result, we can develop the mobile web applications with productivity and quality. In the future, we will suggest how to make the MWeb-Framework standardization and practically apply the frameworks the various case studies to improve framework potentially problems.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.25 no.5
• /
• pp.805-815
• /
• 2001

Glaucoma is an eye disease which is caused by abnormal high IOP (Intra Ocular Pressure). High IOP is caused by the aqueous humor which is produced consistently but not drained due to malfunction of the trabecular system which has a role of draining the aqueous humor into the venous system. Currently, there are three methods to treat glaucoma-using medicines, surgical operation, and using implant device. The first and second methods are not long acting, so the use of implants is increasing in these days in order to drain out the aqueous humor compulsory. However, though conventional implants have a capability of pressure regulation, they cannot maintain IOPs desired for different patients, and too much aqueous humor are usually drained, to cause hypotony. To solve these problems, it is needed to develop a new implant which is capable of controling the IOP actively and copes with personal difference of patients. An active glaucoma implant consists of the valve actuator, pressure sensor, controller, and power supply. In this paper, firstly, we make an analysis of the operation of a conventional implant using a bond graph and show defects and limitations of the conventional valve analytically. Secondly, we design and analyze a valve actuator considering actuation principles, resistance elements, control methods, and energy sources focused on power saving problem. Finally, using simulations the possibility of the proposed valve actuator is investigated.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.25 no.2
• /
• pp.207-218
• /
• 2017

Improving fuel consumption, particularly that of commercial vehicles, has become a global concern. The reduction in logistics cost has been a key issue in efforts to improve fuel economy and efficiency of transportation equipment. Typical technologies for reducing reduce fuel usage include air resistance reduction technologies, tire rolling resistance technologies, and idle technologies among others. Air resistance technology is a highly effective method that can be easily applied in a short period. As with air resistance technology, several devices involving side skirt, boat tail and gap fairing have been developed based on an analytical 3-D modeling technique for reducing air resistance attributed to the vehicle configuration. The devices were on a 45 feet tractor-trailer and the emission test was done using PEMS equipment. Fuel economy was evaluated by introducing several devices to reduce outer air resistance. The test was conducted by changing the experimental method of SAE J1321 Joint TMC/SAE Fuel Consumption Test Procedure - Type II test. As a result, air resistance decreased by at least 15 % and fuel economy improved by at least 13 %. This study sought to reduce greenhouse gas and improve fuel economy by applying several devices to a test vehicle to lower air resistance.

• Journal of Digital Convergence
• /
• v.10 no.4
• /
• pp.107-118
• /
• 2012

Smart TV is expected to take the center stage of the recent "smartization" trend in IT and consumer electronics as it performs a hub for various smart IT devices, such as smart phone, smart pad, PC, etc. It is distinct from traditional TVs or even IPTVs in the sense that it provides immersive and interactive experiences via apps downloaded through TV app store. Smart TV could serve as a new intermediary device between other smart devices and the Internet. While it started experiencing a rapid growth, little research has been conducted to understand this emerging technology in terms of its user acceptance and adoption by users. The current research attempts to fill the gap in the field by examining factors and processes for this new technology to be adopted by users. This paper draws on theories of IT acceptance and use, such as the "Unified Theory of Acceptance and Use of Technology", to investigate factors affecting "intention to use" of smart TV. The proposed research model is analyzed using the structural equation modeling approach. Findings show that such factors as innovativeness, switching cost, switching benefit, service interface, and user interface affect users' intention to use smart TV, through effort expectation, performance expectation, and social influence. Theoretical and managerial implications are discussed.