• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.7 no.2
• /
• pp.126-130
• /
• 2006

Programmable Logic Controller(PLC) is the most widely utilized and plays an important role in industrial control system. Sequential Function Chart(SFC) is a graphic language which is suitable for describing a sequential control logic in discrete control system. We can design a distribute control construction and a hierarchical control construction in process control system described by SFC. In hierarchical control structure, we construct each subsystems to synchronize a synchronous signal between subsystems, and the command system gives and takes a synchronous signal with subsystems. Therefore, the system has a low memory efficiency and a low system performance. In this paper, we propose the method that improved the efficiency of memory in hierarchical control construction, and confirm its feasibility through an actual example.

• The KIPS Transactions:PartC
• /
• v.13C no.6 s.109
• /
• pp.725-732
• /
• 2006

RBAC(Role-Based Access Control) has advantages in managing access controls, because it offers the role inheritance and separation of duty in role hierarchy structures. However, RBAC does not process delegation of permission effectively that occurs frequently in the real world. This paper proposes an Advanced Permission-Based Delegation Model(APBDM) that guarantees permanency of delegated permissions and does not violate security principle of least privilege and separation of duty. APBDM, based on the well-known RBAC96, supports both user-to-user and role-to-role delegation. A delegator can give permission to a specific person, that is delegatee, and the permission can be withdrawn whenever the delegator wants. Our model is analyzed and shown to be effective in the present paper.

• Digital Contents
• /
• no.9 s.52
• /
• pp.34-38
• /
• 1997

본 보고서는 유럽의 전자정보서비스시장에 대한 분석과 경제사회에서의 정보 역할에 대한 전략적 이해를 돕고 정부와 EC의 관련정책수립의 근거자료로서, 또한 다양한 계층의 분야종사자들이 활용할 수 있도록 EU집행위원회 산하의 24개 총국중의 하나인 DG X III/E가 info2000 프로그램 수행의 한분야로 작성하였다. 이번호에서는 공급측면에서 EEA의 EIS 관련부분들만 다투기로 하여 다음호에서 수요측면을 다루기로 하겠다.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2009.04a
• /
• pp.1285-1287
• /
• 2009

VoIP 통신에서 단말간의 세션을 수립하고 종료하는 역할을 하는 SIP는 기본적으로 서버-클라이언트 방식으로 이루어져있다. 하지만 이는 확장성과 설치비용, 단일실패 지점 측면에서 큰 단점을 갖는다. 최근에 DHT를 이용한 구조적인 P2P를 SIP와 결합하여 위의 단점들을 극복하기 위한 연구들이 활발히 진행되고 있다. 하지만 DHT를 이용한 방식은 기존 서버-클라이언트 방식에 비해 검색지연이 늘어난다는 큰 단점을 가지고 있다. 검색지연은 SIP에서 QoS의 중요한 지표중 하나인 호 설정 지연에 60~80% 정도의 큰 영향을 미치게 되므로 해결해야할 중요한 문제이다. P2PSIP에서는 종단 노드가 검색한 사용자의 주소를 캐싱하여 같은 사용자를 재 검색시에 사용하고 있다. 이는 네트워크 전체 오버헤드 감소에 큰 영향을 주지 못할뿐만 아니라 발생된 검색비용을 자신만이 사용할 수 있으므로 비효율적이다. 이에 본 논문에서는 도메인으로 구분된 계층적 P2PSIP네트워크에서 프록시 서버의 역할을 하는 슈퍼노드를 이용한 효과적인 캐싱 방법을 이용하여 호 설정 지연을 단축할 수 있는 방안을 제안하다.

• Journal of Digital Convergence
• /
• v.13 no.10
• /
• pp.263-269
• /
• 2015

This paper suggest remote control technic using TCP/IP protocol network after UART serial communication implemented through RS-232 cable to ethernet module. This is multidisplinary signal technique which is PC signal is converted to internet communication signal. Ethernet module is WIZ1000SR. This is gate module which convert RS-232 protocol to TCP/IP protocol. This module convert serial data transmitted serial device to TCP/IP type data, in contrast TCP/IP data received through network converted to serial data transmitted to serial device. This paper propose that the lower subnet internet layer UDP module make the higher speed in control board than TCP/IP signal.

• Archives of design research
• /
• v.15 no.4
• /
• pp.243-252
• /
• 2002

The enlarge the range of internet users require user centered design method what understanding of cognitive faculties about users by different age groups. This study aims at analyzing cognitive faculties about visual information on web interface by different age groups, presenting visual perception cognitive process model as an evaluation model and proposing an effective web interface design guideline, On the basis of analyzing cognitive faculties verified what each detail property of visual perception cognitive process model as form, color, space, movement and physiological, physical cognitive faculties had have individual cognitive faculties. As the result visual perception cognitive process model suggested in this study can be used as an evaluation model of web interface and users' cognitive faculties analyzed in visual perception measurement by different age groups can be applied as a web interface design guideline. In addition, this study has a meaning in that it makes a chance to extend a web designer's roles and establish a direction of future research by usability of different age groups.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.45 no.2
• /
• pp.150-156
• /
• 2008

Many papers have shown that the hierarchical clustering method takes good-performance, but is limited because of its quadratic time complexity. In contrast, with a large number of variables, K-means reduces a time complexity. Think of the factor of simplify, high-quality and high-efficiency, we combine the two approaches providing a new system named CONDOR system with hierarchical structure based on document clustering using K-means algorithm. Evaluated the performance on different hierarchy depth and initial uncertain centroid number based on variational relative document amount correspond to given queries. Comparing with regular method that the initial centroids have been established in advance, our method performance has been improved a lot.

• Journal of KIISE:Information Networking
• /
• v.32 no.6
• /
• pp.723-731
• /
• 2005

Wide spread deployment of infrastructure WLANs has made Wi Fi an integral part of today's Internet access technology. Despite its crucial role in affecting end to end performance, past research has focused on MAC protocol enhancement, analysis and simulation based performance evaluation without sufficient consideration for modeling inaccuracies stemming from inter layer dependencies, including physical layer diversity, that significantly impact performance. We take a fresh look at IEEE 802.11 WLANs, and using experiment, simulation, and analysis demonstrate its surprisingly agile performance traits. Contention based MAC throughput degrades gracefully under congested conditions, enabled by physical layer channel diversity that reduces the effective level of MAC contention. In contrast, fairness and jitter significantly degrade at a critical offered load. This duality obviates the need for link layer flow control for throughput improvement but necessitates traffic control for fairness and QoS. We use experimentation and simulation in a complementary fashion, pointing out performance characteristics where they agree and differ.

• The Journal of the Convergence on Culture Technology
• /
• v.10 no.1
• /
• pp.477-482
• /
• 2024

Since the Act on Punishment of Serious Accident has been implemented, the role of construction companies in safety and health and the responsibility of CEO are strengthened. However, serious accidents still occur. Due to population decline and young people's reluctance into the construction industry, the ratio of elderly workers and foreign workers is increasing at construction sites. In this study, a survey was conducted to identify differences in the perception of importance of smart safety technology among vulnerable groups such as foreign workers, elderly workers, and workers with health conditions. Vulnerable workers recognize the importance of smart technology in the fields of foreign language support, risk warning, and body wear monitoring, and the conclusion was drawn that smart technology should be expanded for vulnerable groups in the future.

• The KIPS Transactions:PartC
• /
• v.14C no.1 s.111
• /
• pp.65-72
• /
• 2007

The existing RBAC models are not sufficient for managing delegations or separation of roles. Researches have been done on RBDM(Role Based Delegation Model) that deal with delegating role or permission to other users. In this paper, we divide the delegated roles into two groups: periodic and temporary delegation roles. When a role is delegated, a time period is assigned together, which is used to revoke the permission of delegated role automatically. In our model, the role of monotonic delegation by an original user can be revoked at any time in case of malicious use by the delegated user. The contribution of our model is that the malicious use of delegated role can be prohibited and security vulnerability in the role hierarchy due to role delegations can be alleviated. The proposed model, T RBDM(Time out Based RBDM) is analyzed and compared with the conventional models, such as RBDM0, RBDM1 and PBDM. Our model shows an advantage over other models in terms of security robustness.