• International journal of advanced smart convergence
• /
• v.10 no.4
• /
• pp.52-58
• /
• 2021

Data access bias can be observed in various types of computing systems. In this paper, we characterize the data access bias in modern mobile computing platforms. In particular, we focus on the access bias of data observed at three different subsystems based on our experiences. First, we show the access bias of file data in mobile platforms. Second, we show the access bias of memory data in mobile platforms. Third, we show the access bias of web data and web servers. We expect that the characterization study in this paper will be helpful in the efficient management of mobile computing systems.

• Journal of Medicine and Life Science
• /
• v.20 no.3
• /
• pp.115-125
• /
• 2023

Arteriovenous fistula flow dysfunction is the leading cause of vascular access thrombosis and loss in patients undergoing hemodialysis. However, data regarding the influence of access flow rate measurements on the long-term outcomes of access are limited. This study aims to identify accesses at a high risk of thrombosis and loss among patients undergoing hemodialysis by measuring the access flow rate and exploring an optimal threshold value for predicting future access thrombosis. We enrolled 220 patients with arteriovenous fistula undergoing hemodialysis. The primary outcome was the occurrence of access thrombosis. Access flow rates were measured monthly using the ultrasound dilution method and were averaged using all measurements from patients with patent access. In patients experienced access thrombosis, those immediately before the thrombosis were selected. Using these data, we calculated the access flow rate threshold for thrombosis occurrence by analyzing the receiver operating characteristic curve, and the patients were divided into two groups according to whether access flow rates were higher or lower than 400 mL/min. During a median follow-up period of 3.1 years, 4,510 access flows were measured (median measurements per patient, 33 times; interquartile range, 11-54). A total of 65 access thromboses and 19 abandonments were observed. Access thrombosis and loss were higher in the lowflow group than in the high-flow group. This study revealed that low access flow rates are strongly associated with access thrombosis occurrence and subsequent loss of arteriovenous fistulas in patients undergoing hemodialysis.

• 한국정보통신설비학회:학술대회논문집
• /
• 2007.08a
• /
• pp.117-120
• /
• 2007

This article describes a definition of next generation access network, and introduces the researches about a candidate optical links for the next generation access network, and a trend of standardization of Next Generation Access (NGA). Expansion in reaches of access network enables to the evolutions to the metro-access union system. Also, this paper reviews the access network in Korea, and suggests the requirements for the system in NGA.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2003.05a
• /
• pp.439-442
• /
• 2003

In this paper, a system that implementation of Access Control System Using Biometric System. Biometrics is science which deals with verifying or recognizing using physiological or behavioral characteristic Access Control System uses Biometric system to make an access control system. Biometrics goes under the study of bio-recognition or bio-measurement. It is a technology or study that identifies individuals using one's Biometric character. Access control system is a system used to identify one's entrance and exit, personal management, and security. Access control system can be joined with Biometric system to produce easier use and more sufficient effects. Access control system using Wiegand (Data Format) signal output, can replace earlier RF Card systems and make an access control (security) system. It uses RS-232, Rs-422 or TCP/IP type communication with the computer so an embedded system can be controlled using the software.

• ETRI Journal
• /
• v.32 no.1
• /
• pp.112-119
• /
• 2010

We present a useful design for a free access mat which supports two frequency bands of 2.4 GHz and 5 GHz. The free access mat is a sheet-shaped waveguide which consists of a tightly coupled double-layered microstrip resonator array. It provides easy access for devices in short-range wireless communications. Interference is a common problem with conventional applications which use free space transmission. Our proposed wireless access system uses a subsidiary waveguide, the free access mat. Wireless devices are proximately coupled to the free access mat through which the coupled electromagnetic (EM) wave transmits. The arrival domain of the EM wave of an application is therefore limited to an area close to the free access mat. Wireless devices can be coupled to the free access mat at an arbitrary position without contact. We previously presented a free access mat for a single frequency band. This paper presents a free access mat for the two frequency bands of 2.4 GHz and 5 GHz. The free access mat uses a ring patch resonator array which is easily excited by typical antennas and is resistant to interference. These characteristics are demonstrated by numerical simulation and confirmed by experiment.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.8 no.2
• /
• pp.494-498
• /
• 2004

In this paper, a system that implementation of Access Control System Using Biometric System. Biometries is science which deals with verifying or recognizing using physiological or behavioral characteristic Access Control System uses Bionietric system to make an access control system. Biometrics goes under the study of bio-recognition or bio-measurement. It is a technology or study that identifies individuals using one's Biometric character. Access control system is a system used to identify one's entrance and exit, personal management, and security. Access control system can be joined with Biometric system to produce easier use and more sufficient effects. Access control system using Weigand (Data format) signal output, can replace earlier RF Card systems and make an access control (security) system. It uses RS-232, Rs-422 or TCP/IP type communication with the computer so an embedded system can be controlled using the software.

• Journal of Satellite, Information and Communications
• /
• v.6 no.2
• /
• pp.26-34
• /
• 2011

In Femtocell that provides high quality of indoor communications with low transmitted power, there are two typical Access modes; Closed Access mode and Open Access mode. In this paper, we propose resource allocation scheme, which mitigates difference of performance between Access modes and improves overall cell performance, according to Access mode. We give more wireless resources to Open Access mode Femtocell, which improves performance of other users, than Closed Access mode Femtocell. If Open Access mode Femtocell uses more resource, there is trade-off between improvement of user using Open Access mode Femtocell and increase of interference that other users receive. So, we solve the optimal value for resource allocation and analyze performance of conventional scheme and proposed scheme applying the optimal value. Eventually, proposed scheme can improve overall cell performance relative to conventional scheme.

• 한국정보통신설비학회:학술대회논문집
• /
• 2007.08a
• /
• pp.121-124
• /
• 2007

This article describes a function and structure of access network equipment under BcN environment. Access network until now have constructed separately to offer voice, data service. However, simplifies network structure, function that can do traffic concentration, subscriber certification, individual charging, QoS according to service and routing is required in BcN. In this paper, compare method offering by separate system with existing access network and method that offer integrating function inside system for structure of suitable access network to BcN and search structure of access network equipment for desirable access network of hereafter. Composition of this paper is as following. In Chapter 2, establishment history and structure of access network until present. In Chaprte 3, define suitable requirement and functions to BcN. And compare structure for access net work that is new with present. Last Chapter 4, suggests direction of structure of BcN access network and concludes conclusion.

• Journal of the Korean Society for Industrial and Applied Mathematics
• /
• v.8 no.1
• /
• pp.11-30
• /
• 2004

Access Control is one of essential branches to provide system's security. Depending on what standards we apply, in general, there are Role-based access control, History-based access control. The first is based on subject's role, The later is based on subject's history. In fact, RBAC has been implemented, we are using it by purchasing some orders through the internet. But, HBAC is so complex that there will occur some errors on the system. This is more and more when HBAC is used with other access controls. So HBAC's formalization and model which are general enough to encompass a range of policies in using more than one access control model within a given system are important. To simplify these, we design the mathematical model called non-access structure. This Non-access structure contains to historical access list. If it is given subjects and objects, we look into subject grouping and object relation, and then we design Non-access structure. Then we can determine the permission based on history without conflict.

• Journal of Korea Multimedia Society
• /
• v.25 no.10
• /
• pp.1416-1432
• /
• 2022

The access control system is a system that allows users to selectively enter the building by granting an access key to the user for security. Access keys with weak security are easily exposed to attackers and cannot properly perform the role that authenticates users. Access code keys should be protected from forgery or spoofing. For this reason, access key verification service models is important in security. However, most models manage all access keys on one central server. This method not only interrupts all services due to server errors, but also risks forgery and spoofing in the process of transmitting access keys. Therefore, blockchain algorithms are used to reduce this risk. This paper proposes a blockchain-based access key verification service model that used distributed stored blockchain gateways on storing access keys and authenticates the user's identity based on them. To evaluate the performance of this model, an experiment was conducted to confirm the performance of the access key forgery recovery rate and the blockchain network performance. As a result, the proposed method is 100% forgery recovery rate, and the registration and verification process is evaluated at 387.58 TPS and 136.66 TPS.