• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.12A
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• pp.1136-1146
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• 2005

In this paper, the radiative electric field intensity due to the communication signal and conductive noise is calculated in overhead medium voltage power lines for power line communication. The input impedance is calculated by means of 2 port equivalent model of medium voltage power line network and basic transmission line theory. And then, currents is calculated by calculated input impedance and finally, the emissive electric field is calculated. The input impedance appears like a standing wave form with a fixed cycle because high reflection at the input terminal due to the characteristic impedance of medium voltage power line is very large. A calculated current and radiative electric field also appears like this form. From the measurement results, the measured results are very similar to the calculated results.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.1
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• pp.1-6
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• 2006

High performance $Si_{0.8}Ge_{0.2}$ heterostructure metal-oxide-semiconductor field effect transistors (MOSFETs) were fabricated using well-controlled delta-doping of boron and $Si_{0.8}Ge_{0.2}$/Si heterostructure epitaxal layers grown by reduced pressure chemical vapor deposition. In this paper, we report 1/f noise characteristics of the SiGe pMOSFETs measured under various bias conditions of the gate and drain voltages changing in linear operation regions. From the noise spectral density, we found that the gate and drain voltage dependence of the noise represented same features, as usually scaled with $f^{-1}$ However, 1/f noise was found to be much lower in the device with boron delta-doped layer, by a factor of $10^{-1}_10^{-2}$ in comparison with the device fabricated without delta-doped layer. 1/f noise property of delta-doped device looks important because the device may replace bipolar transistors most commonly embedded in high-frequency oscillator circuits.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.61-64
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• 1999

기존의 CELP 보코더에서, 무성음에 대한 별도의 처리 없이 유성음과 동일하게 처리하였다. 유성음과 무성음은 발성모델측면에서 임펄스열과 랜덤 잡음으로 각각 다름에 도 불구하고 동일하게 처리함으로써 합성음에서 음질의 저하 및 계산량과 전송률 측면에서 손실을 가져왔다. 또, U/V(Unvoiced /voiced) 분류기를 사용하는 경우에는 U/V 분류기의 성능에 따라 합성음의 음질저하의 정도의 차이가 심하다. 본 논문에서는 에러율과 전처리 계산량을 쳐소로 할 수 있는 U/V 분류기를 사용하여 CELP 보코더에서 전송률을 감소시키는 방법을 제안한다. CELP 보코더에서는 스펙트럼 정보를 LPC 파라미터로 추출한 후 다시 전송형 파라미터인 LSP(Line Spectrum Frequency)로 변환한다 새로운 린/V 분류기는 이 LSP 파라미터를 이용한다. LSP 파라미터의 주파수영역 분포도와 간격정보를 이용하여 U/V를 결정하게 된다 제안한 방법을 5.3kbps ACELP에 적용하여 성능 평가를 실시하였다 실험결과 음질의 저하 없이 $5.6\%$ (280bps)의 전송률을 감소할 수 있었다.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.610-614
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• 2005

Rock mass classification by using electrical resistivity tomography(ERT) method is widely performed for the determination of rock support type in tunnel design. In the region of high electrical noise level, however, the result of the ERT will have many erroneous features. In this study, the back ground electrical noise had been measured to find out the reason why the results of ERT in this area did not agree to the expected geology confirmed by boreholes. In order to overcome this limitation of ERT, a hybrid surface-borehole array seismic refraction tomography had been followed. Using this technique, we could get P-wave velocity section including the depth level of tunnel. The comparison of the P-wave velocity and RMR shows fairly good statistical relationship to make it possible to set up the rock mass classification for the entire tunnel line.

• Journal of Korea Multimedia Society
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• v.3 no.4
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• pp.365-371
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• 2000

To restore image degraded by out-of-focus blur and additive noise, an iterative restoration is used. Acceleration parameter is usually applied equally to all over the image without considering the local characteristics of degraded images. As a result, the conventional methods are not effective in restoring severely degraded edge region and shows slow convergence rate. To solve this problem we propose an adaptive iterative restoration according to local degradation, in which the acceleration parameter has low value in flat region that is less degraded and high value in edge region that is more degraded. Through experiments, we verified that the proposed method showed better results with fast convergence rate, showed Visually better image in edge region and lower MSE than the conventional methods.

• Journal of KIISE:Software and Applications
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• v.34 no.5
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• pp.447-454
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• 2007

TFT-LCD(Thin Film transistor liquid crystal display) has become actively used front panel display technology with increasing market. Intrinsically there is region of non uniformity with low contrast that to human eye is perceived as defect. As the gray level difference between the defect and the background is hardly distinguishable, conventional thresholding and edge detection techniques cannot be applied to detect the defect. Between the patterned and un-patterned LCD defects, this paper deals with un-patterned LCD defects by using independent component analysis, adaptive thresholding and skewness. Our method showed strong results even on noised LCD images and worked successfully on the manufacturing line.

• Journal of Veterinary Clinics
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• v.26 no.2
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• pp.155-159
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• 2009

A 2-year-old female mixed dog(weighing 4.3 kg) was referred to the Veterinary Teaching Hospital, Kangwon National University, with primary complaints of exercise intolerance, nocturnal coughing and heart murmur. Diagnostic studies revealed bi-lateral holosystolic murmurs on phonocardiogram, over-riding aorta, pulmonic stenosis, ventricular septal defect, atrial septal defect, biventricular hypertrophy, and subaortic stenosis in diagnostic imaging studies. Based on the diagnostic findings, pentalogy of Fallot(POF) with subaortic stenosis(SAS) was tentatively diagnosed. This is the first case report of POF complicated with SAS in a dog in Korea.

• Progress in Superconductivity
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• v.4 no.1
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• pp.53-58
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• 2002

Noise from electronic instrumentation is invariably present in biomedical signals, although the art of instrumentation design is such that this noise source may be negligible. And sometimes signals of interest are contaminated or degraded by signals of similar type from another source. Biomedical signals are omni-presently contaminated by these background noises that span nearly all frequency bandwidths. In the magneto-cardiogram (MCG), several digital filters have been designed for the elimination of the power-line interference, broadband white noise, surrounding magnetic noise, and baseline wondering. In addition to the introduced FIR filter, notch, adaptive filter using the least mean square (LMS) algorithm, and recurrent neural network (RNN) filter, a new filtering method for effective noise canceling in MCG signals is proposed in this paper, which is realized by the wavelet packets. The experimental results show that the proposed filter using wavelet packet performs efficiently with respect to noise rejection. To verify this, two characteristics were analyzed and compared with LMS adaptive filter, SNR of filtered signal and attractor pattern using the nonlinear dynamics.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 2002.06a
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• pp.76-79
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• 2002

Ghost cancelers need to accurately estimate the distortions suffered by transmitted signals on their way to receivers by capturing ghost canceling reference signals in the vertical blanking interval. As ghosts become much severer, sync separation tends to malfunction, making it impossible to acquire measurement data for channel estimation. This paper presents a robust method of acquiring ghost data using their correlation properties, and evaluates its performance through computer simulation. The reference signals are inserted in such a manner that the polarity alternates from one frame to another to remove color bursts and sync signals, and to increase the signal-to-noise ratio as well. As a result, however, they are prone to timing jitters. So a simple yet effective method is proposed that can correct for even fractional time delays. The timing errors are found to be less than about 4% of the sample spacing.

• Journal of the Korean Geophysical Society
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• v.6 no.4
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• pp.231-244
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• 2003

Lots of various utilities are buried under the surface of the earth. The effective handling of the underground utilities is becoming the big subject and project for the harmonious management and administration of the city. To detect the position and depth of buried underground utilities, GPR and Induced EM surveys are commonly used. However, they have limitations, such as shallow skin-depth and non-availability in the areas where subsurface materials are not homogeneous and are compose of clays and/or salts and gravels. The aim of this study is to find the efficient geophysical method which can overcome these limitations. For this purpose, various geophysical mehods were applied in the site of poor geotechnical environment.