• Journal of the Korean Institute of Telematics and Electronics T
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• v.35T no.2
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• pp.48-55
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• 1998

The main drawback of filtered-X LMS(FXLMS) algorithm for the ANC of broadband noises is its low convergence speed when the filtered reference signals are strongly correlated, producing a large eigenvalue ratio in correlation matrix. This correlation can be caused either by autocorrelation of the signals of the reference sensors, or by coupling between the error path which introduces intercorrelation in the filtered reference signals. In this paper, we introduce a transform domain FXLMS(TD-FXLMS) algorithm that has a high convergence speed by orthogonal transform's decorrelation properties.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.8
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• pp.678-687
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• 2012

The Fly-By-Wire(FBW) flight control system is essential to improve the stability and flying quality of the helicopter. Advanced aerospace companies, such as Bell-Sikorsky (USA) and NHI (European Consortium), have already applied the FBW flight control system to manufacture V-22 and NH-90 helicopters, respectively. This paper addresses the development of control law design using model inversion method improve the hover and low speed handling qualities of helicopter based on BO-105 model in 'Day' and 'Degraded visual environments(DVEs)' in accordance with ADS-33E-PRF. Design parameters are optimized to satisfy the handling qualities specification using Control Designer's Unified Interface (CONDUIT) commercial control law software. The result of the analysis based on CONDUIT and non-real time simulation in-house software, HETLAS (HElicopter Trim Linearization And Simulation) reveals that the provides an efficient mean to achieve Level 1 handling qualities.

• Convergence Security Journal
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• v.6 no.4
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• pp.1-9
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• 2006

With role-based access control, access decisions are based on the roles that individual users have as part of an organization. In this paper, we propose a new RBAC model that a user delegate a permission to another user with function-unit for practical organization. A function-unit delegation is more safe than existing delegations on RBAC model. And FuRBAC model has a authentication to supervise security problems.

• Journal of the Korea Computer Industry Society
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• v.10 no.1
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• pp.21-28
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• 2009

Role-Based Access Control Policy has a role hierarchies in which a higher case role can perform permissions of a lower case role. However, it is necessary for a lower case role to perform a higher case role's permission, which is not allowed to a lower case role, basically. In this paper propose a temporary permission delegation method. As the result of a temporary permission delegation, junior roles can perform senior roles' permissions in a dedicated interval.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.486-491
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• 1999

본 논문에서는 웨이브렛 신경회로망을 사용하여 알려지지 않은 비선형 시스템을 안정하게 적응 제어하는 문제를 다룬다. 비선형 시스템의 정확한 제어는 함수를 근사화하는 데 사용된 함수 근사화기의 정확성과 효율성에 의존한다. 이에 비선형 시스템 제어에 기준 함수의 선택이 자유롭고 함수 근사화 능력이 뛰어난 웨이브렛 신경회로망을 사용한다. 초기 웨이브렛 신경회로망 제어기 설정은 웨이브렛 신경회로망 변수인 신축과 이동 값을 제어기 입력의 시-주파수 특성을 분석해서 구하고, 연결강도는 Lyapunov 안정성 이론에 기초한 적응 법칙을 사용하여 조절한다. 이를 비선형 시스템인 역 진자 시스템에 적용한다.

• Journal of the Korean Society for Library and Information Science
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• v.46 no.2
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• pp.157-174
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• 2012

This study tries to describe personal name access point control ontology for the American novelist Mark Twain using RDF/OWL axiom to control access point based on the ontology. The Axiom used in this study are disjoint with class, domain and range, property cardinality, inverse functional property, individual and literal data property. As a result, in the ontology environment we can accept various access points as equal access points exclusive of authority heading and heading concept. It can successfully describe Mark Twain's personal name access point control ontology and display using the OntoGraf.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.4
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• pp.335-341
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• 2010

To improve the performance of inner loop based on PD controller for a unmanned helicopter, neural networks are applied. The performance of PD controller designed on the response characteristics of error dynamics decreases because of uncertain nonlinearities of the system. The nonlinearities are decoupled to modified dynamic inversion model(MDIM) and are compensated by the neural networks. For the training of the neural networks, online weight adaptation laws which are derived from Lyapunov's direct method are used to guarantee the stability of the controller. The results of the improved performance of PD controller by neural networks are illustrated in the simulation of unmanned helicopter with nonlinearities,

• The KIPS Transactions:PartC
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• v.11C no.6 s.95
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• pp.725-730
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• 2004

Separation of Duty(SOD), with delegation, is one of important security principles in access control area. The role-based access control model adopts SOD principle, but it has some problems; SOD concept is inconsistent with role hierarchy, permissions that have no relation with SOD may be restricted, and delegation may violate SOD. We propose permission-based SOD model on role-based access control. We establishes SOD as a set of permissions instead of role level SOD. Furthermore we propose a principle of role activation. It solves SOD problems of RBAC and supports easy implementation of SOD policy.

• The KIPS Transactions:PartC
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• v.9C no.4
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• pp.523-530
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• 2002

Earlier efforts on optical access concentrated on the design of PONs for the collection and distribution portion of the access network. PON architecture is very simple but it requires MAC protocol for control of upstream traffic. This paper proposes a MAC protocol for a broadband access network using an ATM Passive Optical Network supporting CBR/rtYBR, nrtYBR, UBR and ABR traffic. For the proposed MAC scheme, we present grant field format, minislot format, and bandwidth allocation algorithm. From the simulation result, we have confirmed that our proposed scheme can reduce the average cell delay in comparison to that of conventional MAC schemes.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.2
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• pp.221-226
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• 2012

In this paper, wideband two-stage amplification stage was designed, fabricated and evaluated. The proposed amplification stage with a novel gain control method have a high gain, low noise and high linearity performance. It is consisted of common emitter amplifier as the first stage, cascode gain control amplifier as second stage and power detector which sense the received signal strength. The proposed amplification stage shows a total gain of 29 dB~37 dB, noise fiugre of 1.5 dB at operating band and high linearity performance as the IMD (third intermodulation distortion) level is below the noise level of the measurement equipment at the control voltage 2.0 V generated from power detector under the strong electric field condition.