• Journal of KSNVE
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• v.6 no.6
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• pp.851-856
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• 1996

The active noise cancellation system showing the effective convergence and stability has been studied by simplifying the controller structures using the weighting factors of control error path to the multi-channel filtered-x LMS algorithm which needs a lot of calculations and the performance has been verified experimentally. Besides, to implement the system performance in a vehicle cabin, experimental work for selecting the suitable numbers and positions of the microphones and speakers was accomplished. Effectively combining a TMS 320C 31 main processor conducting real number calculations and having various functions with other components, the purpose-built system board for active noise cancellation has been designed and with this board, car active noise cancellation system showing maximum stable 10dB noise reduction has been obtained at the car idling conditions above 3000rpm range.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.3
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• pp.1016-1030
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• 2018

In this paper, an error-detection-coding-aided iterative hard decision interference cancellation (EDC-IHIC) scheme for multiple-input multiple-output systems employing hybrid automatic repeat request (HARQ) for multi-packet transmission is developed and investigated. In the EDC-IHIC scheme, only packets identified as error-free by the EDC are submitted to the interference cancellation (IC) stage for cancellation from the received signals. Therefore, the possibility of error propagation, including inter-transmission error propagation, can be eliminated using EDC-IHIC. Because EDC must be implemented in systems that employ HARQ to determine packet retransmission, error propagation can be prevented without the need for additional redundancy. The results of simulations conducted herein verify that the EDC-IHIC scheme outperforms conventional hard decision IC schemes in terms of the packet error rate in various environments.

• Journal of the Korean Mathematical Society
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• v.33 no.1
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• pp.15-23
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• 1996

Let C be a category of (pointed) spaces. For $X, Y \in C$ we denote the wedge (or one point union) by $X \vee Y$ and the cartesian product by $X \times Y$. Let $Z \in C$; we say that Z cancels with respect to wedge (resp. cartesian product) and C, if for all $X, Y \in C$ the existence of a homotopy equivalence $X \vee Z \to Y \vee Z$ implies the existence of a homotopy equivalence $X \to Y$ (resp. for cartesian product). If this does not hold, we say that there is a non-cancellation phenomenon involving Z (and C).

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.3
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• pp.253-262
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• 2003

In this paper, the interference cancellation system, which is used to cancel the feedback signal in the wireless communication system with the same frequency, is studied. The time varying feedback signal generated from transmitter antenna to receiver antenna reduces the performance of the receiver system. the interference cancellation system using adaptive feedback method(AF-ICS) is suggested to prevent the oscillation of the receiver system and maintain the maximum output power of the power amplifier by the reduction of time-varying feedback signal and also this paper conforms that the oscillation disappears from the output signal by cancellation of the feedback signal and the total output power is satisfied the system specification.

• The Journal of the Acoustical Society of Korea
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• v.22 no.5
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• pp.351-359
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• 2003

In this paper, we proposed a method for acoustic echo cancellation based on independent component analysis. When the large acoustic noise is picked up by the microphone, the performance of echo cancellation decreased. We used two microphones that received echo signal which is linearly mixed with the noise, then separated the echo signals from the received signals with independent component analysis algorithm. The separated echo signal is used for the reference signal of adaptive algorithm which leads to better performance of the echo cancellation. Computer simulation results show the validity of the proposed method.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.2
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• pp.261-266
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• 2006

A number of different techniques are available to mitigate the problem of cross correlations caused by the limited dynamic range of the 10-bit Gold codes in the GPS C/A code. These techniques include successive-interference cancellation (SIC) and parallel-interference cancellation (PIC), where the strong signals are subtracted at IF prior to attempting to detect the weak signals. In this paper, a variation of these techniques is proposed whereby the subtraction process is delayed until after the correlation process, although still employing a pure reconstructed C/A code signal to permit prediction of the cross correlation process. The paper provides details on the method as well as showing the results obtained when the method was implemented using a software GPS receiver. The benefits of this approach are also described, as is the application of the method to the cancellation of CW interference.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.437-442
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• 2000

An alternative inverse feedback structure for adaptive active control of periodic noise is introduced for systems with nonminimum phase cancellation path. To obtain the inverse model of the nonminimum phase cancellation path, the cancellation path model can be factorized into a minimum phase term and a maximum phase term. The maximum phase term containing unstable zeros makes the inverse model unstable. To avoid the instability, we alter the inverse model of the maximum phase system into an anti-causal FIR one. An LMS predictor estimates the future samples of the noise, which are necessary for causality of both anti-causal FIR approximation for the stable inverse of the maximum phase system and time-delay existing in the cancellation path. The proposed method has a faster convergence behavior and a better transient response than the conventional FX-LMS algorithms with the same internal model control structure since a filtered reference signal is not required. We compare the proposed methods with the conventional methods through simulation studies.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.7
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• pp.1156-1160
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• 2000

The cancellation loop configuration for power amplifier module is proposed to reject the RX signals using feed-forward technique. In this paper, we implement the 1W-ampilfier module of WLL band to show validity of the proposed cancellation loop. The power amplifier module with the proposed cancellation loop can provide low TX insertion path loss due to duplexer and choice of loose RX attenuation characteristic for various wireless communication systems. It shows at least 90 % improved RX rejection characteristic compared to power amplifier module without RX band cancellation loop.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.50
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• pp.89-108
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• 2011

This work intends to study some issues in relation to the cancellation and amendment of letter of credit. Those issues in relation to the cancellation are the significance and formation time of cancellation of letter of credit and some points for practical attention of UCP 600 in the case of cancellation of letter of credit. Those issues in relation to the amendment are the significance and formation requirements of amendment of letter of credit and some points for practical attention of UCP 600 in the case of amendment of letter of credit. If exporters receive letters of credit from foreign countries, they must confirm the indication of irrevocable letter of credit. When they find revocable letters of credit, they should amend the credits to be irrevocable credits. If issuing banks amend letters of credit against beneficiaries, the banks should receive the beneficiaries' consent. If amendments devalue applicants' expectations in the underlying transaction, the applicants for whom the credit issues are not liable to reimburse. Beneficiaries and issuing banks may amend a credit, but the issuing bank acts at its own peril if it does not obtain the applicant's consent.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.11
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• pp.2388-2400
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• 1997

In this paper, we analyzed the serial interference cancellation scheme and proposed the new serial interference cancellation scheme suppressing multiple access interference. Compensating for the near-far effect and the multiple access interference is critical for the stable performance of DS/CDMA system, and the serial multiple access interference cancellation has been proposed as one of the compensation methods. But this serial interference cancellation scheme has a linear variation in the number of cancellation operation each users. Becaure of this variation, it is difficult to show a stable performance. Hence, we suggested a new serial interference applying window technique to overcome this fault and made a performance estiamation.