• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.11a
• /
• pp.391-394
• /
• 2002

There has recently been much interest and research in developing digital x-ray systems based on using amorphous selenium(a-Se) photoconductors as the image receptor. The amorphous selenium layer that is currently being studied for use as an x-ray photoconductor is not pure a-Se but rather amorphous selenium alloyed with arsenic. We fabricated samples using the selenium and arsenic alloy with various concentrations of the arsenic. In this work, x-ray photoconductor using amorphous selenium alloyed with arsenic were fabricated with different concentrations of the arsenic (0.1 wt.%, 0.3wt.%, 0.5wt.%, 1wt.%, 1.5wt.%, 3wt.%, 5wt.%). The seven kind of samples was fabricated with a-Se alloyed with arsenic through vacuum thermal evaporation. We also investigate the arsenic concentration dependence on the device performance in radiation detector. The electric characteristics of radiation detector devices with changing additive ratio of the arsenic is performed by measuring the x-ray induced photocurrent and integrating it over time to find the total charge. The thickness of a-Se is $100{\mu}m$. Bias voltages $3V/{\mu}m$, $6V/{\mu}m$， $9V/{\mu}m$ are applied at the samples. As results, the net charge of a-Se 0.3% As sample is $526.0pC/mR/cm^2$ at $9V/{\mu}m$ bias. The net charge is decreased as with the increasing additive ratio of arsenic.

• The Journal of Korean Academy of Prosthodontics
• /
• v.58 no.3
• /
• pp.251-256
• /
• 2020

In recent years, digital technology has been developed in dentistry, which denture frameworks can be manufactured using DMLS (Direct Metal Laser Sintering) technique. A traditional impression method can be replaced by oral scanning and wax pattern production process can be achieved by the use of CAD/CAM techniques. The designed STL files can be sent to DMLS devices to fabricate final components of removable partial dentures (RPD). The advantages of digital dentistry are concision and precision. In this case study, a fracture of occlusal rests providing support and indirect retention was repaired by DMLS and laser welding techniques. It shows satisfactory results in adaptation accuracy and functional properties of the repaired denture.

• Journal of Multimedia Information System
• /
• v.1 no.1
• /
• pp.11-22
• /
• 2014

This work discusses and evaluates the use of wireless and multi-sensor based technologies to develop UbiqBIOPARC, a new generation zoological park that has been created based on the zoo-immersion concept. It offers appropriate contextual information to zoo visitors, depending on their preferences and the environment in which they are positioned. It combines the flexibility of the iPhone SDK, the connectivity provided by 3G technologies, the location capabilities of GPS, and the orientation offered by a digital compass integrated in the device. In this document the overall architecture and the implementation steps followed to create this context-aware application are presented. We compare our system with respect to previous ones and demonstrate that UbiqBIOPARC is an example of how innovative context-aware applications can be built with the aid of GPS and compass features. Several real experiments have been carried out in order to evaluate performance and system behavior, and numerical results demonstrate the practicality offered by our application, while providing a quite reasonable performance in terms of delay, usability, and energy efficiency.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• v.9 no.2
• /
• pp.833-836
• /
• 2005

Compared to corporation and government networks, home devices and services connected in a home networks has security threats because of the use of various wired and wireless network, middleware and protocol in digital home environment, a restricted system resource of home information appliances and the users who do not care about security. So security is critical element to provide secure services in a home network environments. In this paper we design the access control system based on RBAC to offer secure home network services.

• Journal of Digital Convergence
• /
• v.12 no.8
• /
• pp.113-127
• /
• 2014

The use of mobile devices offers a variety of services to the individuals and companies. On the other hand, security threats and new mobile security threats that exist in IT infrastructure to build the environment for mobile services are present at the same time. Services such as mobile and vaccine management services, such as MDM (Mobile Device Management) has attracted a great deal of interest in order to minimize the threat of security in mobile environment. These solutions can not protect an application that was developed for the mobile service from the threat of vulnerability of mobile application itself. Under these circumstances, in this paper, we proposed mobile application security checklists based on application security review items in order to prevent security accidents that can occur in a mobile service environment. We collected and analyzed Android applications, we performed a total inspection of the applications for verification of the effectiveness of the check items. And we checked that the check items through a survey of experts suitability was verified.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.14 no.3
• /
• pp.587-594
• /
• 2010

In this paper, we propose an asynchronous IR-UWB ranging system based on the two-way ranging protocol. The periodic pulse sequence is used to measure a distance between two devices. At the receiver, a received signal is first transformed into a frequency-domain signal using an analog correlator bank and digital signal processing is followed in the frequency-domain. This make it possible for the system to use an ADC with a conversion speed of pulse rate. The proposed algorithm at the receiver side includes a peak detection procedure using mutipath channel compensation and matched filtering, and retransmits a pulse sequence synchronized with the detected peak. The validity of the proposed algorithm is verified from simulation results where the CM1 channel is assumed.

• Journal of Digital Convergence
• /
• v.14 no.6
• /
• pp.253-261
• /
• 2016

As many people use internet through the various programs of PC and mobile devices, the possibility of private data leak is increasing. A program should be used after checking security of information flow. Security analysis of information flow is a method that analyzes security of information flow in program. If the information flow is secure, there is no leakage of personal information. If the information flow not secure, there may be a leakage of personal information. This paper proposes a method of analyzing information flow that facilitates SAT solver. The method translates a program that includes variables where security level is set into propositional formula representing control and information flow. The satisfiability of the formula translated is determined by using SAT solver. The security of program is represented through the result. Counter-example is generated if the program is not secure.

• Journal of Digital Contents Society
• /
• v.18 no.6
• /
• pp.1079-1089
• /
• 2017

As a result of the development of information and communication technology and the negative phenomenon of using smart devices including smart phones, many people are stressed. In this paper, we examine the effect of independent variables(mobile use ability, technical limit, speed of change, popularity) and control variables(manual service) on technostresses, which is derived from previous studies conducted from the negative viewpoint of existing information technology. For empirical analysis, empirical data were collected from a total of 206 individuals, and hypothesis tests were conducted using AMOS 22.0. In addition, by the qualitative research, we have examined smartphone usage and the technostress of smartphone usage. Focus group interviews were conducted with 24 ordinary people who purchased and used smartphones in order to verify the user's response to the smartphone user manual service.

• Journal of Digital Convergence
• /
• v.16 no.7
• /
• pp.267-275
• /
• 2018

This study was conducted to analyze the impact factors of serious dental disease of elderly and to propose the need to treatments of negative factors on oral health-related quality of life. This study used the data of the 6th 3nd-year(2015) National Health and Nutrition Examination Survey. The dependent variables of this study were reviewed for serious dental diseases, and the independent variables were divided into demographic characteristics, health status and behavior, oral health status, and behavior. The results of study were as follow. Factors influencing dental caries was household income(p<.01), health checkups(p<.05), experience of toothache for the recent 1 year(p<.05), and whether to use oral hygiene devices(p<.05). Factors influencing periodontal disease was age(p<.05), occupation(p<.05), and whether to Comorbidity(p<.05). Based on these results, a political alternative plan will need to be arranged for promoting oral health in the aged as a relevant research is vitalized.

• Journal of Biomedical Engineering Research
• /
• v.19 no.3
• /
• pp.225-232
• /
• 1998

Results of Monte Carlo simulations on amorphous silicon based x-ray imaging arrays are described. In order to investigate the characteristics of amorphous silicon x-ray imaging devices and to provide the optimum design parameter, Monte Carlo simulations were performed. Monte Carlo simulation codes for our purpose were developed and various combinations of x-ray peak voltages, aluminum filter thicknesses, CsI(TI) thicknesses, and amorphous silicon photodiode pixel sizes were tested in connection with detection efficiency and spatial resolution of the amorphous silicon based x-ray imager. With usual Csl(TI) thickness of 300${\mu}{\textrm}{m}$-500${\mu}{\textrm}{m}$, detection efficiency was in the range of 70%-95% and energy absorption efficiency was in the range of 40%-70% for 60kVp-120kVp x-ray. From the simulations it was found that amorphous silicon pixel size and Csl(TI) thickness were the most important parameters which determine the resolution of the imager. By use of our simulation results we could provide proper combinations of Csl(TI) thicknesses and pixels sizes for optimum sensitivity and resolution.