• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.7
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• pp.499-507
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• 2003

This paper presents a method for active noise control (ANC) in a duct by using a ring-tyPe smart foam. The ring-type smart foam consists of an elastic porous material of lining shape and a PVDF film embedded In the material. The PVDF element acts as a secondary sound source to reduce the noise. Active noise control using a ring-type smart foam is only effective locally because of the way to excite radially. To enlarge the quiet zone, the duct Is lined with additional acoustic foam between the smart foam and the error microphone. When cancellation path ks optimized by the LMS/RLS algorithm, the computation power is reduced while control performance Is maintained. The filtered-x LMS algorithm is used to minimize the error signal.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1967-1968
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• 2008

본 논문에서는 안정성이 강화된 다중채널 적응 필터를 사용한 능동소음 제어 시스템을 제안한다. 초기에는 IIR필터의 극점을 원점방향으로 강제로 이동시켜 안정성을 확보하고, 망각인수를 도입하여 정상상태에 도달하면 최적 수렴치로 유지하게 함으로서 제어 정상상태 성능에는 영향을 미치지 않고 안정도가 강화 된 적응 IIR 필터 알고리즘을 제안한다. LMS 알고리즘의 수렴 성능을 개선하기 위한 방법으로 정규화기법을 사용하면 수렴 속도가 향상되지만 이에 비례하여 안정성이 떨어지게 된다. 소음원 입력의 파워가 시변 할 경우 적응 알고리즘의 안정성이 약화되는 문제점이 발생하는데, 본 논문에서는 Leaky LMS알고리즘과 비슷한 구조이지만 안정성이 강화된 IIR정규화 LMS 알고리즘을 제안한다. 제안한 알고리즘의 유용성을 비교 분석하기 위하여 실험을 수행하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2016.10a
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• pp.439-442
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• 2016

제한된 환경에서 로봇이 동적 장애물들에 대해 능동적으로 대처하며 목표한 지점까지 도달하기 위한 알고리즘을 제안한다. 로봇은 행동기반 시스템으로 만들어져 주변 장애물들을 자율적으로 회피한다. ex-agent는 공중에서 주변 환경들을 modeling 한 뒤 cell-map을 만들어 $A^*$알고리즘을 통해 이동 경로를 설정한다. 이동 경로와 로봇의 진행방향을 비교하여 회전 방향을 조언해준다. 로봇은 ex-agent 로부터 받은 조언과 센서값들을 조율하여 장애물들을 능동적으로 회피하며 목표 위치를 찾아갈 수 있다. 실험은 시뮬레이터를 통해 이루어졌으며 장애물들에 대해 원반한 회피율을 보였다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.10a
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• pp.775-780
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• 2011

This paper represents the study on the development of semi-active bicycle suspension system. The road vibration and transmissibility of front suspension are obtained by driving test on proving ground. The numerical simulation is evaluated by dynamic system modeling and equation of motion. The numerical simulation are performed to estimate the optimal damping force for minimal vibration transmission. And oscillating displacement is calculated and analyzed. Therefore the stoke which convert the damping characteristics is suggested from the driving test and numerical simulation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.916-921
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• 2014

In this paper, an improved small-scaled blade prototype was designed with the flap-driving mechanism classified as an active vibration reduction method, in order to reduce vibratory load in the helicopter. In detail, the previous Active Trailing-Edge Flap based on piezoelectric actuator, called SNUF(Seoul National University Flap), failed to achieve the target value (${\pm}4^{\circ}$) of the flap deflection angle. Therefore, the flap-driving mechanism design was improved, and a new piezoactuator was selected to accomplish the target value of the flap deflection angle in both static and rotating situations.

• Proceedings of the KSME Conference
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• 2001.06b
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• pp.641-645
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• 2001

In this paper, it is discussed that active noise control in a circular duct using smart foam. Firstly, it is demonstrated that the potential of the conventional smart foam, proposed by Fuller, for active noise control in a duct. Conventional smart foam is not applicable to active noise control in a duct having flow. Thus, this paper presents a ring-type smart foam as an alternative. The ring-type smart foam consists of polyurethane acoustic foam of lining shape and PVDF film embedded in the foam. The embedded PVDF element acts as an actuator to reduce noise at lower frequencies and the foam absorbs noise at higher frequencies. A filtered-x LMS controller is used to minimize the signal from the error microphone. Experiments are executed to reduce broadband and tonal noise.

• Journal of KSNVE
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• v.9 no.2
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• pp.265-272
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• 1999

A LMS algorithms has been widely used for an adaptive filter algorithm in active noise control systems. But this algorithm has poor convergence and it is very difficult to select optimal convergence parameters in this algorithm. In this paper, a fuzzy LMS algorithm where the convergence parameters are computed using a fuzzy logic controller was proposed. A proposed algorithm was applied to active noise control system in HVAC(central Heating Ventilation and Air Conditioning) ducts. The experimental ducts and experimental apparatus were designed and manufactured for experiments, and the modelling of the experimental ducts was also performed for computer simulations. Computer simulations and experiments were performed to show the effectiveness of a proposed algorithm.

• The Journal of the Acoustical Society of Korea
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• v.32 no.6
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• pp.455-471
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• 2013

Active sonar has been commonly used to detect targets existing in the shallow water. When a signal is transmitted and returned back from a target, it has been distorted by various properties of acoustic channel such as multipath arrivals, scattering from rough sea surface and ocean bottom, and refraction by sound speed structure, which makes target detection difficult. It is therefore necessary to consider these channel properties in the target signal simulation in operational performance system of active sonar. In this paper, a monostatic active sonar system is considered, and the target echo, reverberation, and ambient noise are individually simulated as a function of time, and finally summed to simulate a total received signal. A 3-dimensional highlight model, which can reflect the target features including the shape, position, and azimuthal and elevation angles, has been applied to each multipath pair between source and target to simulate the target echo signal. The results are finally compared to those obtained by the algorithm in which only direct path is considered in target signal simulation.

• Journal of KIISE:Computing Practices and Letters
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• v.11 no.2
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• pp.165-179
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• 2005

Close collaboration among businesses is required in B2B EC environment. Furthermore, emergency requests or critical information among businesses should be processed in an immediate mode. Most current systems, however, due to firewalls for the systems' security and autonomy, can not handle these requirements appropriately, but handle them in an ad hoc manner In this paper a method of timely collaboration among businesses and an active functionality component to support it in B2B EC environment are proposed. Since the active functionality component supports high level ECA rule patterns and event-based immediate processing, system administrators and programmers can easily program and maintain the timely collaboration independently to the application logic. The proposed active functionality component uses HTTP protocol to be applied through firewalls and is designed using a commercial DBMS for practical purpose.

• KLA journal
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• v.46 no.6 s.361
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• pp.26-28
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• 2005

《도서관문화》6월호 특집란에서는 각 급 도서관 현장 사서 및 다양한 분야의 오피니언리더들의 '도서관 마케팅 및 도서관 PR'에 대한 생각을 들어보는 지면을 마련하였다. 아직도 일부에서는 도서관은 열심히 일하는 데 알아주지 않는다는 불만의 소리가 높은데 이는 우리 스스로 도서관을 알리는 적극적인 노력이 부족한 것이 아닐까도 싶다. 도서관의 외부환경 변화에 능동적으로 대처하기 위한 생존전략의 하나로서 '도서관 마케팅 및 도서관 PR'을 생각해보는 시간이 될 수 있기를 바라며, 편집실의 자문에 도움을 준 '한국도서관마케팅연구소'에 감사드린다.