• 천문학논총
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• 제32권1호
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• pp.29-31
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• 2017

We plan to produce a faint source catalogue from the AKARI mid-infrared (IR) all-sky diffuse maps. In the publicly-available AKARI mid-IR point source catalogue (PSC), sources were extracted from single-scan images, and confirmed by using the other scan images. By stacking multiple scan images, we can detect fainter sources which are not listed in the PSC. We optimized the source extraction process using a $6^{\circ}{\times}6^{\circ}C$ area around the star-forming region, Cepheus B. Then, we divided the all-sky data into three seasonal images, and checked the positions and the fluxes of the detected sources on the images. As a result, our new source extraction method works well; 90% of the sources are also identified in the WISE catalogue. In this method, we obtain the detection limit twice deeper than that of the PSC. The number of sources increases by a factor of 2, as compared with the PSC.

• 한국공작기계학회논문집
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• 제15권5호
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• pp.104-113
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• 2006

The main objective of this study is to investigate the effect of compounded welding by using acoustic emission (AE) signals and doing a source location for weld heat affected zone (HAZ) through tensile testing. This study was carried out an SWS 490A high strength steel for electric shield metal arc welding, SMAW; $CO_2$ gas metal arc welding, GMAW($CO_2$); and gas tungsten arc welding, GTAW/TIG. Data displays are based on the measured parameters of the AE signals, along with environmental variables such as time and load. For instance, Gutenberg-Richter magnitude-frequency relationship (G-R MFR) offers useful b-value in data analysis. Namely event identification, source location gives the X- and Y-coordinates of the AE source. And K-means clustering analysis by Euclidean distance confirmed that was powerful to source location. Generally, strength of welded metal zone was stronger than strength of base metal. As the result, confirmed certainly that fracture is produced in HAZ instead of welded metal zone from source location.

• 자원환경지질
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• 제30권5호
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• pp.451-458
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• 1997

The horizontal magnetic dipole as well as electrical dipole was adopted as a source to compute one-dimensional electromagnetic field behavior in controlled source magnetotellurics. he Cagniard impedances due to horizontal magnetic dipole source, especially phases, showed better frequency characteristics than those due to electric one. The magnetic dipole is inferior to the electric dipole in the point of relatively weak transmitting power at low frequency. But considering high resistivity charateristics of Korean geology, the magnetic dipole source is recommended for the survey up to depth of 500 m. A vector CSMT was introduced to get more reliable data in the area of two- or three-dimensional structures. A software and interpretation technique using polarization ellipses were developed. The technique was tested by synthetic data, which provided theoretical basis of the methodology. Although CSMT has inevitable limitation of investigation depth due to practically possible source-receiver separation, we proposed to use the technique developed in this paper where MT is not available, for example, in extremely noisy area or for shallow target.

• 한국지능시스템학회논문지
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• 제13권2호
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• pp.222-230
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• 2003

의료 시스템이 개발되면 시스템이 사용하는 knowledge source의 신뢰도가 시스템의 수행능력에 큰 영향을 미치게 되므로, knowledge source의 신뢰도를 검증해야한다. 본 논문은 의료 시스템 CLINAID의 knowledge source의 신뢰성 조사에 대한 연구의 방법과 결과를 발표하였다. 그 방법으로는 CLINAID에 사용된 Cardiovascular body system 데이터에 fuzzy relational method를 적용하여 구조적 분석을 통해 만들어진 인공의 syndrome을 knowledge base에 저장되어있는 의료 전문가의 syndrome과 비교하였다. 7 가지 fuzzy implication operator를 사용하여 거의 비슷한 결과들을 산출해 냈으며, 그 결과들이 전문가가 제공한 syndrome과 거의 일치하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.200-204
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• 2005

The use of beamforming method and de-Dopplerization technique was applied in studying the rotating sound sources. Acoustic analysis of a moving sound source required that the measured sound signals be do-Dopplerized and restored as of the original emission signals. Two main issues of the signal reconstruction in time domain are addressed herein: First, to remove Doppler effect from the measured data and to restore the original emission data of the moving source. The difference of the time domain beamforming from the frequency domain beamforming was mentioned. Also, the time domain beamforming method is deployed in the test and the comparisons were made to the frequency domain results. The time domain signal reconstruction was numerically simulated prior to the application. To validate the de-Dopplerization Performance, the rotating Point sources were examined and localized by the use of a phased array of microphone. The application of prop-rotor was conducted in a hovering condition. The results of reconstructing time signals of rotating sources and its locations were shown in the power distribution maps. In the prop-rotor measurements, the acoustic source locations were successfully verified in varying positions for different frequencies of interest.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2006년도 전기학술대회논문집
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• pp.209-210
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• 2006

Digital technology has been applied to marine seismic survey to develop data processing technology and multi-channel marine seismic survey. In result, high-resolution marine seismic survey ended in a success. Surveys are conducted for various purposes using various frequencies of acoustic sources. A low frequency source is used for deeper penetration and a high frequency source is used for higher resolution survey. In this study, a multi-source system was used for multi-channel marine seismic survey to acquire seismic sections of both low and high frequencies. Variations of depth of penetration and resolution would be used to achieve more accurate analysis of formations. In this study, the multi-source system consists of Bubble Pulser(400 Hz) for low frequency source and Sparker(1.5 kHz) for high frequency source.

• 천문학논총
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• 제20권1호
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• pp.109-116
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• 2005

When we measure a source signal in the presence of a background rate that has been independently measured, the usual approach is to obtain an estimate of the background rate by observing an empty part of the sky, and an estimate of the source signal plus background rate by observing the region where a source signal is expected. The source signal rate is then estimated by subtracting the background rate from the source signal plus background rate. However, when the rates or their observation times are small, this procedure can lead to negative estimates of the source signal rate, even when it should produce a positive value. By applying the Bayesian approach, we solve the problem and prove that the most probable value of source signal rate is zero when the observed total count is smaller than the expected background counts. It is also shown that the results from the conventional method is consistent with the most probable value obtained from the Bayesian approach when the source signal is large or the observation time is long enough.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 춘계학술대회 논문집
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• pp.414-417
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• 1999

According to development of power electric technology from industrial field to electronic home appliances, recent SMPS using semiconductor is spread widely. Electric converting instrument uses a sine wave voltage source, namely an usual power source, and it gets a non-sines power source from power source because current flows through one part in waveform of one cycle. This injects higher harmonic source in source part, absorb pollution source. And this cause quality deterioration, durability shortage of electric power instrument, spreading accident of electric solver system, and so on. It can't supply an electric source of good quality in industry, so become an impedimental element in improving productivity and reliance. This study can be used in prediction of hindrance and diagnosis material and intends to suggest a countermeasure about measurement data.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 II
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• pp.866-870
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• 2001

Measurement techniques for in-duct acoustic source parameters can be classified into the direct method and the load method, according to whether it utilizes an extra external source or not. It is reported that the load methods yield the negative source resistance and the purpose of this paper is to clarify that the time-varying nature of the source is the main cause of this physically implausible result. For this purpose, the direct and load methods for measuring the source characteristics of a simplified fluid machine are simulated using the time domain numerical analysis. In the numerical simulations, the method of characteristics is employed and the source characteristics are calculated from the resultant data. It is shown that the load method results in negative source resistance for some frequencies, whereas the direct method yields positive values for all frequencies considered. It is found that the result of load method is quite sensitive to the change of cylinder pressure or valve profile in contrast to the direct method.

• 지구물리와물리탐사
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• 제15권3호
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• pp.129-135
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• 2012

동시 송신원 전파형 역산 기법은 계산량을 획기적으로 줄여 전파형 역산의 적용성을 높여준다. 그러나 다수의 송신원 모음 자료를 동시에 모델링하여 사용하기 때문에 관측 자료의 수진기 위치가 송신원에 따라 다른 경우, 나머지(residual) 파동장에 불필요한 값을 생성하게 되고 이는 파형역산의 수렴성을 저해하게 된다. 특히, 제한된 벌림 거리(offset)를 갖는 스트리머 방식의 탐사자료는 동시 송신원 기법을 적용하기에 가장 어려운 자료 형태이다. 이러한 문제점을 극복하기 위해 최근에 global correlation에 기반한 목적함수가 제안되었고, 시간영역 전파형 역산에 성공적으로 적용되었다. 그러나 이 기법은 변형된 목적함수를 사용하기 때문에 나머지 파동장이 왜곡되고 경우에 따라 역산 결과에 부정적인 영향을 주기도 한다. 또한, 여러 가지 장점을 갖고 있는 주파수 영역 파형역산에 적용된 사례는 아직 보고된 적이 없다. 본 논문에서는 이러한 나머지 파동장의 왜곡을 최소화하기 위해 global correlation 계산 시 사용하는 자료에 진폭감쇠 기법을 적용한다. 진폭감쇠를 적용한 자료는 global correlation의 특성을 최적화하여 나머지 파동장의 왜곡을 줄이고 파형역산 결과를 향상시킨다. 시간 영역에서 구한 나머지 파동장을 주파수 영역에서 역전파시킴으로써 global correlation기법을 주파수 영역에서 구현한다. 스트리머 방식의 합성 탐사자료를 이용한 예제를 통해 본 논문에서 제안한 기법이 기존의 global correlation 목적함수에 기반한 동시 송신원 전파형 역산보다 향상된 결과를 얻을 수 있음을 보여준다.