• Journal of Welding and Joining
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• 제19권1호
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• pp.40-48
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• 2001

An ultrasonic test method, as a nondestructive test is applied to ensure the clad interface quality assessment. According to the reference codes and standards, not only korea Industrial Standard(KS) but also American Society for Testing and Materials (ASTM) Standard, ultrasonic examination procedures use the pulse-echo, A-scan, back reflection signal drop method and/or side drilled reference hole used to establish the acceptance criteria of clad material test. But the variety of bonding materials and sizes makes it difficult to produce the reference blocks, or thus the criteria. In order to overcome these practical difficulties, new ultrasonic testing criterion is suggested. In this new method, the theoretical interface reflection signal amplitude level is calculated and suggested as an acceptance criteria with the back reflection signal set to 100% FSH(Full Screen Height) which is based on acoustic impedance mismatch at the clad interface for the explosive clad ultrasonic inspection. Applicability of suggested criterion, for the explosive clad Fe-Naval Brass with different bonding quality is confirmed to the pre-existed KS and ASTM specifications and verified by using SEM (Seanning Electron Microscope) micrograph. The results obtained by the suggested method is more conservative than the results according to the KS B 0234 and ASTM A 578 specifications The suggested method could be applicable to any other combination of explosive clad ultrasonic inspection.

• 말소리와 음성과학
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• 제6권3호
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• pp.63-72
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• 2014

The current study assessed the utility of acoustic analyses the most commonly used in routine clinical voice assessment including perturbation, nonlinear dynamic analysis, and Spectral/Cepstrum analysis based on signal typing of dysphonic voices and investigated their applicability of clinical acoustic analysis methods. A total of 70 dysphonic voice samples were classified with signal typing using narrowband spectrogram. Traditional parameters of %jitter, %shimmer, and signal-to-noise ratio were calculated for the signals using TF32 and correlation dimension(D2) of nonlinear dynamic parameter and spectral/cepstral measures including mean CPP, CPP_sd, CPPf0, CPPf0_sd, L/H ratio, and L/H ratio_sd were also calculated with ADSV(Analysis of Dysphonia in Speech and VoiceTM). Auditory perceptual analysis was performed by two blinded speech-language pathologists with GRBAS. The results showed that nearly periodic Type 1 signals were all functional dysphonia and Type 4 signals were comprised of neurogenic and organic voice disorders. Only Type 1 voice signals were reliable for perturbation analysis in this study. Significant signal typing-related differences were found in all acoustic and auditory-perceptual measures. SNR, CPP, L/H ratio values for Type 4 were significantly lower than those of other voice signals and significant higher %jitter, %shimmer were observed in Type 4 voice signals(p<.001). Additionally, with increase of signal type, D2 values significantly increased and more complex and nonlinear patterns were represented. Nevertheless, voice signals with highly noise component associated with breathiness were not able to obtain D2. In particular, CPP, was highly sensitive with voice quality 'G', 'R', 'B' than any other acoustic measures. Thus, Spectral and cepstral analyses may be applied for more severe dysphonic voices such as Type 4 signals and CPP can be more accurate and predictive acoustic marker in measuring voice quality and severity in dysphonia.

• 한국항행학회논문지
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• 제23권2호
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• pp.142-150
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• 2019

포구속도는 총포탄약의 평가에 있어 가장 중요한 계측항목들 중 하나이다. 포구속도는 포탄이 포구를 떠나는 시점의 속도로 정의된다. 특히, 포구속도는 추진제의 성능과 밀접하게 관련이 있기 때문에 정확한 측정이 요구된다. 포구속도의 측정에는 도플러 레이더가 사용되나, 도플러 레이더 신호의 품질은 시험장 환경에 의존한다. 따라서 본 논문에서는 도플러 레이더의 신호 품질을 악화시키는 클러터를 시험장 구조 및 신호처리 방법의 개선을 통해 제거하는 방법을 제시하였다. 개선된 신호처리 방법의 적용을 위해 도플러 레이더의 원시 도플러 데이터를 획득하는 프로그램을 작성하였다. 시험장 구조 및 신호처리 방법의 개선을 통해 얻어진 속도 데이터에 대한 통계적인 검증으로 제안하는 방법이 기존에 사용하던 방법에 비해 클러터 제거에 효과가 있음을 증명하였다.

• 한국컴퓨터정보학회논문지
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• 제28권2호
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• pp.19-25
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• 2023

이 논문에서는 image signal processing 을 고려하여 저조도에서 촬영된 저품질의 raw 이미지를 딥러닝에 기반하여 개선하는 방법을 제안한다. 스마트폰 카메라의 경우 DSLR 카메라에 비해 렌즈나 센서의 확장에 제약이 있어 저조도 상황에서 이미지에 노이즈가 증가되고 품질이 저하되는 문제점을 보인다. 기존 딥러닝 기반 저조도 이미지 처리 방식은 image signal processing의 주요 요소인 렌즈 쉐이딩 효과와 화이트 밸런스를 고려하지 못하여 부자연스러운 이미지를 생성하기도 한다. 본 논문에서는 렌즈 쉐이딩 효과와 화이트 밸런스를 딥러닝 모델에 적용하기 위해 중심거리와 채널 평균을 활용한다. 스마트폰으로 촬영된 저조도 이미지를 통한 실험에서 제안하는 방법이 기존 방법에 비해 더 높은 peak signal to noise ratio 와 structural similarity index measure를 달성함과 동시에 높은 품질의 저조도 이미지를 생성함을 확인한다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.1322-1325
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• 2009

Adaptive black band insertion improve blur phenomenon that caused by hold type issue of LCD, the approach regulate charge time by OE signal to control black inserted ratio, and the charge time be modified according the motion quantity of displaying content.

• 디지털산업정보학회논문지
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• 제10권3호
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• pp.143-149
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• 2014

This paper is on the blind signal separation(BSS) method by the geometric method. To separate the signal sources, we use Hough transform and BSS. Hough transform is a geometric method which let us know the local informations of the signal. We find the orientations of signals by Hough transform and know the number of signal sources. When the number of sensors is more than the number of sources. the BSS algorithm can separate the mixtures well in the time domain. This algorithm has a good performance in converging fast. We had checked up the quality of the algorithm after separating the mixed signals. The results of simulations show that this BSS method has the abnormal waveforms due to unconverging coefficients in the beginning, and stably has the separated waveforms which almost equal to the sources in the most period.

• Journal of information and communication convergence engineering
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• 제7권3호
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• pp.304-308
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• 2009

This paper proposes a new concept of a signal constellation of the recently introduced half-symbol-rate-carrier phase-shift keying (HSRC-PSK) modulations for bandwidth-efficient high speed data communications. Since the HSRC-PSK modulations contain different symbol energies representing the same bit sequences due to the loss of orthogonality of their HSRC signals, it is very hard to represent the symbol using the conventional signal constellation. To resolve the problem, two different energies are assigned to represent one symbol for the HSRC offset quadrature phase shift keying (OQPSK) modulation. Similarly, the different energies exist to display the different symbol for HSRC minimum shift keying (MSK) modulation. With the proposed signal space representation, HSRC-PSK symbol can easily be shown with a two-dimensional scatter plot which provides helpful information of evaluating HSRC-PSK signal's quality.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2006년도 추계학술대회 논문집
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• pp.885-889
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• 2006

Metro Subway System is widely known as the leader of public transportation in a metropolitan area. The signal interlocking is one of the most important organs that plays a major role in the system. By improving the quality of signal lights on the traffic system and keeping its maintenance on a high level will not only repair the current state, but it will also let the LED type signal semi-permanent. The device, which underwent a process of fine manufacture establishment and a close examination, obtained a patented article (2004, as a new device). Utilizing the equipment with cautious preservation on the system will enhance the current state of the signal device. Especially, the test for improvement and development based upon the technique that decreases the frequency of defect produced will further precipitate its efficiency. With authorization of imposing the LED lights on production, installment, and investigation of the system, the newly made equipment will bring improvement to the signal technology and to the industry at largest extent.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 추계종합학술대회 논문집
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• pp.1247-1250
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• 1998

In speech synthesis, LF model is widely used for excitation signal for voice source coding system. But LF model does not represent the harmonic frequencies of excitation signal. We propose an effective method which use sinusoidal functions for representing the harmonics of voice source signal. The proposed method could achieve more exact voice source waveform and better synthesized speech quality than LF model.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.28-32
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• 1995

Bacause the chatter vibration is a main factor to damage on the quality and integrity, The cure is required peticurity in cykinderical plunge grinding. The chatter vibration relatied with wheel speed, workpiece and infeed rate. Therefore, we expressed more credible normal signal and chatter signal Pattern in accrdiance with wheel speed and acquired RMS signal of the accelerrometer. In thos study, after finding the chatter pattern, we applied two parameters, standard deviation and Kurtosis, to Neural Network.