• The Journal of the Acoustical Society of Korea
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• v.32 no.4
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• pp.329-334
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• 2013

Order spectrum analysis is widely used to grasp the features of noises due to powertrain system including engine and intake/exhaust system. It is known from many previous researches that order components related to the first and second firing frequencies of engine considerably affect the noise of car interior. The purpose of this paper is to find out the difference in sound quality: Pleasantness of car interior noise according to the change of its order spectrum. For this, car interior noises of 6-cylinder and 4-cylinder engines are recorded and their order spectrum levels are modified by applying adaptive digital filters. After subjective listening test employing paired comparison method is conducted, it is investigated that the level change of half-order components is a noticeable factor to improve Pleasantness of the car interior noises whereas level decrease of firing order does not always give the positive effect on its sound quality.

• The Journal of the Korea Contents Association
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• v.9 no.2
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• pp.432-438
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• 2009

In this paper, we evaluated the performance of the automatic classifier applied for the discrimination of acute alcoholic liver injury and chronic liver fibrosis. The classifier uses the discriminant peaks of the preprocessed Raman spectrum as a feature set. In preprocessing step, we subtract baseline and apply Savitzky-Golay smoothing filter which is known to be useful at preserving peaks. After identifying discriminant peaks from the spectra, we carried out the classification experiments using MAP and neural networks. According to the experimental results, the classifier shows the promising results to diagnosis alcoholic liver injury and chronic liver fibrosis. Classification results over 80% means that the peaks used as a feature set is useful for diagnosing liver disease.

• Tunnel and Underground Space
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• v.16 no.6 s.65
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• pp.486-494
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• 2006

The horizontal to vertical (H/V) ratio technique in spectral domain is a common useful technique to estimate empirical site transfer function. The technique, originally proposed by Nakamura, is proposed to analyse the surface waves in the micrortremor records. The purpose of this paper is to estimate spectral ratio using observed data at the seismic stations distributed within Southern Korean Peninsula from the Fukuoka earthquake including 11 aftershocks. The results show that most of the stations have fairly good amplification characteristics in low frequency band. However, some of the seismic stations show one (resonant frequency specific to the site) or several local peaks of amplification factors with narrow high frequency band. Even though the site amplification characteristics are important information, we should be careful to analyse the observed ground motions from the seismic stations which have several very high amplification peaks for the deconvolution of seismic source and attenuation parameters.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.2
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• pp.81-88
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• 2018

Spectrum sensing, the key technology of the cognitive radio networks, is used by a secondary user to determine the frequency state of a primary user. The energy detection in the spectrum sensing determines the presence or absence of a primary user according to the intensity of the allocated channel signal. Since this technique simply uses the strength of the signal for spectrum sensing, it is difficult to detect the signal of a primary user in the low SNR band. In this paper, we propose a way to combine spectrum sensing and support vector machine using wavelet packet decomposition to overcome performance degradation in low SNR band. In our proposed scheme, the sensing signals were extracted by wavelet packet decomposition and then used as training data and test data for support vector machine. The simulation results of the proposed scheme are compared with the energy detection using the AUC of the ROC curve and the accuracy according to the SNR band. With simulation results, we demonstrate that the proposed scheme show better determining performance than one of energy detection in the low SNR band.

• Journal of the Korean Association of Geographic Information Studies
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• v.3 no.1
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• pp.1-11
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• 2000

The hybrid coding algorithm for multi-spectral image obtained from satellite is discussed. As the spatial and spectral resolution of satellite image are rapidly increasing, there are enormous amounts of data to be processed for computer processing and data transmission. Therefore an efficient coding algorithm is essential for multi-spectral image processing. In this paper, VQ(vector quantization), quadtree decomposition, and DCT(discrete cosine transform) are combined to compress the multi-spectral image. VQ is employed for predictive coding by using the fact that each band of multi-spectral image has the same spatial feature, and DCT is for the compression of residual image. Moreover, the image is decomposed into quadtree structure in order to allocate the data bit according to the information content within the image block to improve the coding efficiency. Computer simulation on Landsat TM image shows the validity of the proposed coding algorithm.

• Proceedings of the Acoustical Society of Korea Conference
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• 1998.06e
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• pp.428-431
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• 1998

화자 인식의 방법에서 사용되고 있는 특징 파라미터들은 음성 인식에서 사용되고 있는 특징 파라미터를 그대로 사용하고 있다. 따라서, 이를 화자 인식에 적용할 때 화자의 특성을 효과적으로 반영할 수 있어야 한다. 일반적인 화자의 특징이 고주파수 위주로 분포되어 있기 때문에 전체 스펙트럼의 고주파 영역을 강조시킬 수 있고, 또한 인간의 청각특성이 공진 주파수에 기반하여 이루어진다는 사실에 기반을 두어서 공진 주파수 위주로 강조시키는 인지 가중 필터를 인식단의 전처리로 사용하는 방법에 관한 것이다. 본 논문을 실험한 결과 전체 인식율에서는 기존의 방법보다 3.89%까지 인식율의 향상을 얻을 수 있었다. 또한 사칭자 수리율은 2.5%의 저하를 얻을 수 있었다.

• 한국HCI학회:학술대회논문집
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• 2007.02a
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• pp.530-536
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• 2007

본 논문에서는 MFL(Magnetic flux leckage) 피그(PIG : Pipeline Inspection Gauge)에서 획득된 센서데이터의 분석을 위한 가시화 기법의 구현을 소개한다. MFL피그는 배관 내부에 삽입되어 배관의 결함이나 특징정보를 파악하기 위해 사용되는 장비로, 다양한 종류의 센서를 지니고 있으며, 각 센서에서 나온 값들은 피그에 탑재된 저장장치에 빠른 샘플링 속도로 저장된다. 분석가는 피그에 저장된 데이터를 가시화 도구를 사용하여, 피그에 샘플링 된 데이터를 통해 배관의 용접부위나 결함과 같은 특징정보를 찾아야 하고, 특징정보인 부분과 그렇지 않은 부분을 쉽게 구별 할 수 있어야 한다. 하지만 센서의 값에 따라 색상에 맵핑하여 보여주는 2차원 가시화 기법만으로는 효율적인 분석이 어렵다. 본 논문은 이를 극복하기 위하여, 센서 값에 맵핑되는 색상 스펙트럼 편집 및 기본 값 조정 기능을 제안한다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.6
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• pp.113-118
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• 2010

The split spectrum processing algorithm of an ultrasonic wave on the tire was studied for the damage detection of a driving vehicle's tire. The processing results of normal and damaged tire was compared using the split spectrum algorithm to estimate the maximum value. The result that used Auto-correlation in case of damaged tire, the damage feature point is detected during 81ms intervals at a speed of 100km/h and during 162ms periodicity at a speed of 50km/h. This results was meaned the possibility for the tire's damage decision by damaging material with using periodicity feature point of tire damage according to vehicle speed.

• Journal of the Korean Academy of Esthetic Dentistry
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• v.24 no.2
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• pp.86-100
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• 2015

To harmonize with the remaining natural teeth a dentist and technician make an effort to do. Dental ceramic perfectly reproduce the functionality and esthetic is so moved that will deliver to the patient. However It is not easy to overcome the problem. Actually, it can't have the same spectrum curve between different object. The spectrum curve and reflectance is a unique feature of an object like fingerprints. So it is not that the identification of spectral curves that we usually focuses color. We need to understand the process of matamerism makes something like a combination of color perception. In other word that will tell in our field with ceramic teeth of the patient wish to match the color matching process to simulate the cone in our retinas with the same combination.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.4
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• pp.459-466
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• 2014

This paper deals with the method to classify the aircraft target by analyzing its JEM signal. We propose the method to classify the engine model by analyzing JEM spectrum using the harmonic frequency mask generated from the blade information of jet engine. The proposed method does not need the complicated logic algorithm to find the chopping frequency in each rotor stage and the pre-simulated engine spectrum DB used in the previous methods. In addition, we propose the method to estimate the precise spool rate and it reduces the error in estimating the number of blades or in calculating the harmonic frequency of frequency mask.