• International journal of advanced smart convergence
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• 제10권4호
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• pp.52-58
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• 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
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• 제20권3호
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• pp.115-125
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• 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
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• 한국정보통신설비학회 2007년도 학술대회
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• pp.117-120
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• 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.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2003년도 춘계종합학술대회
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• pp.439-442
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• 2003

본 연구에서는 생체인식(Biometric)을 이용하여 Access Control System을 구현하였다. Biometric 는 생체 인식 또는 생체 측정학으로 사람의 생체적, 행동적 특성을 이용하여 개인을 식별하는 학문 또는 기술이다. Access Control System은 개인을 식별 출입과 근태, 개인 관리, 보안 둥에 사용하는 System으로 Biometric System과 접목으로 편리성과 보안성에서 탁월한 효과를 발휘할 수 있다. 본 연구에서 제안한 시스템은 기존의 RF Card System에 Wiegand(Data format) Signal 출력으로 기존 RF Card Reader대신 Access Control (Security) System을 구성할 수 있도록 설계되었고 컴퓨터와 RS-232, RS-422 또는 Tcp/Ip로 구성되어 Software상에서 임베이디드 System을 Control 할 수 있게 되어 있다.

• ETRI Journal
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• 제32권1호
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• pp.112-119
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• 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.

• 한국정보통신학회논문지
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• 제8권2호
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• pp.494-498
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• 2004

본 연구에서는 생체인식(Biometric)을 이용하여 Access Control System을 구현하였다. Biometrics는 생체인식 또는 생체 측정학으로 사람의 생체적, 행동적 특성을 이용하여 개인을 식별하는 학문 또는 기술이다. Access Control System은 개인을 식별 출입과 근태, 개인 관리, 보안 등에 사용하는 System으로 Biometric System과 접목으로 편리성과 보안성에서 탁월한 효과을 발휘할 수 있다. 본 연구에서 제안한 시스템은 기존의 RF Card System에 Wiegand(Data format) Signal 출력으로 기존 RF Card Reader대신 Access Control (Security) System을 구성할 수 있도록 설계되었고 컴퓨터와 RS-232, RS-422 또는 TCP/IP 로 구성되어 Software상에서 임베이디드 System을 Control 할 수 있게 되어 있다.

• 한국위성정보통신학회논문지
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• 제6권2호
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• pp.26-34
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• 2011

저전력으로 옥내 고품질의 통신환경을 제공하는 펨토셀에는 등록된 유저만 접근이 가능한 Closed Access mode와 모두에게 접근을 허락한 Open Access mode, 이렇게 대표적으로 두 가지의 접근 모드가 있다. 본 논문에서는 두 접근 방식의 펨토셀이 혼재된 LTE 기반의 OFDMA 셀룰라 환경에서 유저 간의 성능 차이를 완화하고, 시스템 전체의 성능을 향상시키는 접근 모드에 따른 자원 분배를 제안한다. 상대적으로 Closed Access mode보다 다른 유저들에게 고품질의 통신 환경을 제공하는 Open Access mode 펨토셀에게 더 많은 무선 자원을 허용한다. 무선 자원을 더 많이 허용하면 Open Acees mode 펨토셀을 사용하는 유저의 성능은 향상하지만 동시에 다른 유저에게 미치는 간섭 또한 증가하기 때문에 이러한 trade-off 관계를 고려한 최적의 자원 할당이 필요하다. 따라서 시스템 레벨 시뮬레이션을 통해서 최적의 자원 할당 값을 구하고 기존 방식과 최적 값을 적용한 제안한 방식을 시뮬레이션 한 결과, 제안한 방식이 기존 방식보다 전체적인 셀 성능을 향상 되는 것을 볼 수 있었다.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2007년도 학술대회
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• pp.121-124
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• 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
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• 제8권1호
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• pp.11-30
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• 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.

• 한국멀티미디어학회논문지
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• 제25권10호
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• pp.1416-1432
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• 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.