• Proceedings of the Korean Information Science Society Conference
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• 2012.06d
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• pp.208-210
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• 2012

일반적으로 비동기식 센서 네트워크 MAC 프로토콜들은 별도의 충돌회피 알고리즘을 사용하지 않기 때문에 동기식 MAC 프로토콜에 비해 충돌에 의한 성능 저하가 크게 나타난다. 본 논문에서는 충돌에 따른 비동기식 MAC 프로토콜의 성능 저하 문제를 최소화하기 위해 수신 노드가 충돌을 야기한 송신 노드들의 전송 순서를 제어하여 추가적인 충돌을 제거할 수 있는 비동기식 MAC 프로토콜용 충돌해결 알고리즘을 소개한다. 충돌을 감지한 수신 노드는 충돌을 일으킨 송신 노드들에 대한 정보를 수집하고 이를 이용하여 충돌이 발생하지 않는 전송 순서를 각 송신 노드에게 지정한다. 송신 노드들은 지정된 순서에 따라 독점적인 채널 사용 권한을 얻으며 이를 통해 송신 노드간의 충돌을 회피할 수 있다. 실험에 대한 분석에 따르면 본 논문에서 제안하는 충돌해결 알고리즘은 반복적인 충돌을 방지하여 그로 인해 낭비되는 시간과 대역폭을 줄이고 이를 통해 각 노드당 평균 데이터 처리량을 약 18.6% 증가시킬 수 있다.

• Journal of KIISE:Databases
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• v.30 no.1
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• pp.1-13
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• 2003

In this paper, we present a content-dependent authorization mechanism for object-oriented database systems. So far, several models of authorization for object-oriented databases have been proposed, but most of these models do not support the authorization based on the database content. This paper shows how the traditional content-independent authorization model can be extended to provide the content-dependent authorization using predicates on the values of attributes of a class. The proposed model makes it possible to group objects that satisfy the specified conditions on the values of the objects and to grant a single authorization on those objects. This model supports the negative authorization and provides the concept of the strong and weak authorization to resolve conflicts between positive and negative authorizations. In addition, we address and resolve some of the problems that arise when the predicates are associated with the authorization. In particular, since the authorization operations of the traditional content- independent model become inadequate for our mode, we redefine the semantics of the authorization operations.

• Journal of KIISE:Computer Systems and Theory
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• v.30 no.12
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• pp.699-707
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• 2003

RBAC is accepted as a more advanced control method than existing DAC and MAC. Studies on the permission-role part of RBAC model are relatively insufficient compared with those on the user-role part, and researches on symmetric RBAC models to overcome this is also in an incipient stage. Therefore there is much difficulty in assigning permissions suitable for roles. This paper proposes an symmetric RBAC model that supplements the constraints on permission assignment set forth by previous studies. The proposed symmetric RBAC model reflects the conflicts of interests between roles and the sharing and integration of permissions on the assignment of permissions by presenting the constraints on permission assignment that take the separation of duties and role hierarchies into consideration. In addition, by expressing constraints prescribing prerequisite relations between dynamic permissions through AND/OR graphs, it is possible to effectively limit the complicated prerequisite relations of permissions. The constraints on permission assignment for the proposed symmetric RBAC model reduce errors in permission assignment by properly detailing rules to observe at the time of permission assignment.

• Proceedings of the Korea Information Processing Society Conference
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• 2001.10b
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• pp.1315-1318
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• 2001

이 논문은 TCP/IP 기반의 근거리 네트워크에서 사용되는 개인용 컴퓨터의 MAC 주소을 이용하여 인터넷 프로토콜 주소 충돌을 해결하는 방법에 대하여 연구한다. 네트워크에 접속된 컴퓨터의 증가에 따른 IP 주소의 부족 현상과 고의 또는 실수로 권한을 받지 않은 사용자의 IP 주소의 사용에 의하여, 정당한 IP 주소 사용자가 네트워크를 사용할 수 없게 되는 경우가 있다. 본 논문은 근거리 네트워크에 접속되어 있는 컴퓨터의 MAC 주소와 IP 주소를 데이터베이스화 하여 IP 주소 충돌을 방지한 수 있는 시스템을 구축함으로써. 비정상적인 IP 사용자가 네트워크를 사용할 수 없도록 설계되어 있다.

• Journal of Internet Computing and Services
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• v.7 no.5
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• pp.109-121
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• 2006

In this paper, we suggest lattice based role graph security management model which changes security level in mandatory access control model as well as constraint and role hierarchy systematically in role base access control model. In this model, we solved privilege abuse of senior role that is role graph model's problem, and when produce conflict between privileges, we can keep integrity of information by reseting grade of subject through constraint. Also, we offer strong security function by doing to be controlled by subject's security level as well as privilege inheritance by role hierarchy, Finally, we present the role graph algorithms with logic to disallow roles that contain conflicting privileges.

• The Transactions of the Korea Information Processing Society
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• v.7 no.1
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• pp.126-134
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• 2000

Version control is an application to maintain consistency between different instances of the same document allowing operations such as navigation, differencing, and merging. Most version control systems, however, lack the support of functionality for cooperative writing environment, such as to represent and store the history of the actions of different individuals, to effectively differentiate and merge the individual actions including the text object, and to manage different access privileges for different granularity and individuals. With the help of Activity IDentification (AID) tag and its unique addressing scheme proposed in this paper, differencing and merging become simple and effective. Access and role control is improved by associating the access right table and role assignment in AID scheme also eliminates the requirements for large storage capacity for version information maintenance.

• Journal of Advanced Navigation Technology
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• v.16 no.1
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• pp.122-130
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• 2012

Airborne separation assurance is a key requirement for Free Flight. This paper is to propose autonomous flight algorithm, such as extended authority of delegation, efficiency of airspace issue to deal with the empirical solution for free flight, and to measure flight efficiency and conflict detection and resolution (CD&R) by utilizing flight performance data under the two circumstances of scenario with the modeling of proposed algorithm and potential field algorithm. The results show that the autonomous flight algorithm is superior to the potential field algorithm under the circumstances of free flight airspace in terms of algorithm performance, CD&R, and flight efficiency.

• Proceedings of the Korea Information Processing Society Conference
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• 2015.10a
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• pp.383-386
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• 2015

Ad Hoc 네트워크는 단말간 채널 경쟁을 통해 데이터 패킷을 전송하는 DCF(Distributed Coordination Function)에 기반을 둔다. DCF는 단말의 수가 많아질수록 충돌 확률이 증가하여 성능이 급격하게 감소한다. 성능 향상을 위해 DPCF(Distributed Point Coordination Function) 방법이 제안되었다. 이 방법에서 단말은 기본적으로 DCF로 동작하고 채널 접근 권한을 얻었을 때 이웃 단말들에게 PCF(Point Coordination Function)를 이용하여 채널 경쟁 없이 데이터 패킷을 전송하도록 한다. 그러나 이 방법은 히든 노드 문제를 더 가중시키고 데이터 패킷이 없는 단말도 폴링을 하기 때문에 채널 낭비를 초래한다. 본 논문에서는 이 문제점을 해결하기 위한 새로운 방법을 제안한다. 제안된 방법은 PCF로 동작할 때 전송 범위 내 모든 단말이 아닌 제한된 영역에 있는 단말을 대상으로만 동작한다. 또한 데이터 패킷이 있는 단말에 대해서만 폴링을 수행한다. 이를 통해 제안된 방법은 Ad Hoc 네트워크에서 충돌 확률을 낮추고 성능을 향상시킨다.

• Journal of Korea Port Economic Association
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• v.29 no.3
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• pp.135-158
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• 2013

There have been many conflicts in Pyeongtaek-Dangjin Port among central government, metropolitan council, and cities over the jurisdiction of reclaimed port area, an international passenger terminal construction and a bridge between the port and Dangjin area. This study found out two causes for the conflicts in terms of governance. First, the current governance structure of Pyeongtaek-Dangjin port has high levels of conflict and disputes among stakeholder. Second, there is no leading agency which is responsible for the future development of the port. It is very important to decrease the possibility of conflict and to establish leading agency. Measures to decrease the likelihood of conflict include establishment of conflict resolution mechanism, the clarification of the facts and applicable law, mutual exchanges between stakeholder. Measures to establish a leading agency include the introduction of a single governance, establishment of Pyeongtaek-Dangjin Port Authority, central-local combined governance, and empowering PA to do all port management.

• Journal of Advanced Navigation Technology
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• v.12 no.5
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• pp.470-482
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• 2008

This paper propose role base access control model that use context information for ubiquitous environment. Concept of access control that use context information assigns permission that can approach in some information or object in part. And do so that can assigned user in part to it and acquire permission. So it can approach in information or object. Therefore, user approaches in information or object in assigned role, and the role that is allocated ro own is having. So, do so that can secure information or utilization of object safety. Proposa1 model investigated lacking restriction item in GEO-RBAC model. So, it considered that present new restriction condition and role conflict in various case. Also, to GEO-RBAC model proposed suitable model, analyzed old model's advantage, shortcoming. And it presented proposal model to GEO-RBAC because improving this.