• Journal of the Institute of Convergence Signal Processing
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• v.4 no.4
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• pp.23-29
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• 2003

In this paper, we propose an idea for the improved 3-D sound system using conventional stereo headphones to obtain a better sound diffusion from the mono-sound recorded at an anechoic chamber. We use the HRTF(Head Related Transfer Function) for the sound localization and the wavelet filter bank with time delay for the sound diffusion. And we test the modified HRTF with the various sampling rate. We investigate the effects of the 3-D sound depending on the length of time delay at lowest frequency band. Also the correlation coefficient of the signals between the left channel and the right channel is measured to identify the sound diffusion. At last we obtain the diffusion sound using Cool Edit for reverberation.

• Fire Science and Engineering
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• v.18 no.2
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• pp.27-33
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• 2004

An accurate knowledge of the AIT(Autoignition temperatures) of chemicals is important in developing appropriate prevention and control measures in industrial fire protection. The AITs describe the minimum temperature to which a substance must be heated, without the application of a flame or spark, which will cause that substance to ignite. The measurement AITs are dependent upon many factors. namely initial temperature. pressure, volume, fuel/air stoichiometry. catalyst material, concentration of vapor, ignition delay time. This study measured the AITs of acids from ignition delay time by using ASTM E659-78 apparatus which was produced in the year 1994. The experiment AITs were a good agreement with the calculated AITs by the proposed equations with a few A.A.P.E.(average absolute percent error) and A.A.D.(average absolute deviation).

• Computational Structural Engineering
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• v.7 no.1
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• pp.25-30
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• 1994

본 고에서는 강한 바람이나 지진에 의한 고층 구조물의 진동을 감소시키기 위하여, 능동제어장치가 효과적으로 사용될 수 있음을 보이었다. 그러나 능동제어장치를 실제 구조물에 널리 적용하기에는 아직 많은 문제점들이 남아있다. 첫째, 효과에 비해 고가의 진동제어장치가 필요하며 유지관리에도 많은 비용이 필요하다. 또한 진동제어장치가 원활히 작동하기 위해서는 계속된 에너지의 공급이 있어야 하는데, 지진과 같은 과도한 구조물의 진동시 이를 보장할 수는 없다. 그러므로 극한상황에서는 진동을 오히려 증폭시킬 수도 있다. 둘째, Control Force의 산정시 사용되는 목적함수의 가중행렬을 결정하는 정형화된 방법이 아직 존재하지 않으며 효율적인 산정을 위해서는 많은 시행착오가 필요하다. 그밖에도 복잡한 실제 구조물의 단순한 모형화에 따라서 여러 문제점들이 발생하기 쉬우며, 실제 제어시에는 시간지연효과나 측정되지 못한 거동에 의한 문제 등이 있다. 구조물의 진동 저감방안에 대한 지금까지의 연구결과로는, 일반적인 경우에 있어서는 Base Isolator와 같이 재료의 감쇠특성을 이용하는 방법이 추천되고 있으나, 현재 내진설계된 고층건물과 같은 대형 구조물의 진동제어 등의 몇몇 경우에 있어서 능동제어의 필요성이 인정되고 있다. 좀더 안정적이고 효율적인 제어기법의 개발에 의해 많은 실제 구조물에 적용 범위를 넓힐 수 있을 것으로 기대된다.

• The KIPS Transactions:PartC
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• v.11C no.3
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• pp.353-360
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• 2004

In this Paper, We propose an efficient iteration decoding control method with variable iteration decoding of iteration codes decoding using Cyclic Redundancy Check. As the number of iterations increases, the bit error rate and frame error rate of the decoder decrease and the incremental improvement gradually diminishes. However, when the iteration decoding number is increased, it require much delay and amount of processing time for decoding. Also, It can be observed the error nor that the performance cannot be improved even though increasing of the number of iterations and SNR. So, Suitable number of iterations for stopping criterion is required. we propose variable iteration control method to adapt variation of channel using Frame Error-Check indicator. Therefore, the amount of computation and the number of iterations required for iteration decoding with CRC method can be reduced without sacrificing performance.

• Proceedings of the KIEE Conference
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• 2004.07d
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• pp.2224-2226
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• 2004

현재 ATM 망의 ABR 소스에서 불확실한 시간지연에 대한 이산시 모델에 대해, 많은 연구가 진행되고 있다. 이 모델들은 각각의 소스에서의 대역폭(Bandwidth)을 일정하게 보고 있지만, 현실적으로 소스의 네트워크 상황에 따라 각기 할당되는 대역폭은 큰 차이가 있다. 각기 다른 대역폭을 고려할 때 ABR 스위치 모델은 특이 섭동 구조를 갖는다. 본 연구에서는 대역폭 차에 따른 ABR 스위치에서의 특이 섭동 모델을 제안하고 ABR 스위치에서의 체증을 해결하기 위해 합성제어 기법을 이용한 이산시 최적 제어기를 설계한다.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.11
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• pp.1124-1129
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• 2008

Recently, two-port time-domain passivity approach was modified for time-varying communication delay. The newly proposed approach could achieve stable teleoperation even under the serious time-varying delay and packet loss communication condition. However, after some operation hour, the accumulated energy difference between the input energy from one port and the output energy at the other port caused unstable behavior until the passivity controller is activated. Resetting scheme is introduced for solving this problem, and stable bilateral teleoperation can be guaranteed without worrying about the accumulated energy difference.

• Proceedings of the KIEE Conference
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• 2001.07d
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• pp.2616-2618
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• 2001

본 논문에서는 홈 오토메이션용 제어 통신망에 널리 사용되는 Ethernet, CEBus, Lonworks 통신규약에 대해서 성능을 분석하고 이를 평가한다. 각 통신시스템의 MAC 규약을 살펴보고 시간 해석에 관한 분석을 제시한다. 본 논문에서는 평균 지연 시간, 네트워크 이용률, 전송 성공 확률 등을 성능분석의 지표로 사용한다. 이를 이용하여 각 통신 규약에 대해 시뮬레이션 결과를 비교, 분석한다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.306-309
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• 2005

This parer describes the tracking control simulation of 6-DOF shaking table with a bell crank structure, which converts the direction of reciprocating movements. For the Joint coordinate-based control which uses lengths of each actuator, the trajectory conversion process inverse kinematics is performed. Applying the Newton-Euler approach, the dynamic equation of the shaking table is derived. To cope with nonlinear problems, time-delay control(TDC) is considered, which has been noted for its exceptional robustness to parameter uncertainties and disturbance, in addition to steady-state accuracy and computational efficiency. If the nominal model is equal to the real system, joint coordinate-based control can be very efficient. However, manufacturing tolerances installation errors and link offsets contaminate the nominal values of the kinematic parameters used in the kinematic model of the shaking table. To compensate differences between the nominal model and the real system. the joint coordinate-based control using acceleration feedback in the Cartesian coordinate space is proposed.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.10
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• pp.94-117
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• 1998

This paper investigates the performance characteristics of the data link layer of the 1996 version of IEC/ISA fieldbus which is developed as internatioal standard of fieldbus. A discrete-event simulation model of the data link layer of IEC/ISA fieldbus is developed. Using the simulation model, this paper identifies the network parameters that influence the performance of prioritys scheme and real-time data transmission, and analyzes the delay performance of IEC/ISA fieldbus with respect to the change of network parameters. The simulation model also integrates continuous-time simulation model of a control system as application process. Using the integrated simulation model, this study investigates the effect of network-induced delay on the performance of control system. Since the simulation model developed in this study can predict the network performance, it will be effectively utilized in the design phase of control and automation systems that adopt the IEC/ISA fieldbus.

• Journal of the Korea Society for Simulation
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• v.18 no.3
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• pp.47-59
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• 2009

Due to the application-specific nature of wireless sensor networks, the sensitivity to such a requirement as data reporting latency may vary depending on the type of applications, thus requiring application-specific algorithm and protocol design paradigms which help us to maximize energy conservation and thus the network lifetime. In this paper, we propose a novel delay-adaptive sensor scheduling scheme for energy-saving data gathering which is based on a two phase clustering (TPC). The ultimate goal is to extend the network lifetime by providing sensors with high adaptability to the application-dependent and time-varying delay requirements. The TPC requests sensors to construct two types of links: direct and relay links. The direct links are used for control and forwarding time critical sensed data. On the other hand, the relay links are used only for data forwarding based on the user delay constraints, thus allowing the sensors to opportunistically use the most energy-saving links and forming a multi-hop path. Simulation results demonstrate that cluster-based delay-adaptive data gathering strategy (CD-DGS) saves a significant amount of energy for dense sensor networks by adapting to the user delay constraints.