• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.839-845
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• 2003

This paper introduces multichannel blind source separation (BSS) and multichannel blind deconvolution (MBD) based on higher order statistics of signals from convolutive mixtures. In particular, we are concerned with the case that the number of inputs is the same as the number of outputs. Simulations for two input two output cases are carried out and their performances are assessed. One of the major applications of those sequential algorithms (BSS and MBD) is demonstrated through the fault signal detection from only a single measurement of rotating machine, which offers a certain degree of practicability in the engineering field such as machine health monitoring or condition monitoring.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2017년도 추계학술대회
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• pp.716-717
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• 2017

본 논문은 오픈소스 소프트웨어를 활용하여 IoT와 Cloud 기반의 연계를 지원하는 해양환경 모니터링을 지원할 수 있도록 오픈소스 기반의 모델링 제안한다. 제안 모델은 Apache Hadoop 기반의 시계열 데이터베이스를 이용한 스케일 아웃(Scale out)이 가능하도록 설계하여 수집되는 데이터가 늘어나더라도 컴퓨터 자원을 늘려서 쉽게 처리할 수 있다. 또한 수집되는 데이터를 시각화함으로써 해양 자료를 분석하는데 이용할 수 있다.

• Journal of Positioning, Navigation, and Timing
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• 제8권2호
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• pp.69-77
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• 2019

This study introduces MATLAB Graphical User Interface (GUI)-based software to monitor ionospheric disturbances. This software detects ionospheric disturbances using Global Positioning System (GPS) and Global Navigation Satellite System (GLONASS) measurements, and estimates a location of the disturbance source through the detected disturbance. In addition, this software includes a sky plot making function and frequency analysis function through wavelet transform. To evaluate the performance of the developed software, data of 2011 Tohoku earthquake in Japan were analyzed by using the software. The analysis results verified that the ionospheric disturbances were detected through GPS and GLONASS measurements, and the location of the disturbance source was estimated through the detected disturbance.

• 한국항행학회논문지
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• 제14권3호
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• pp.358-366
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• 2010

무선 네트워크상에서 혼잡과 지연은 네트워크 내에 존재하는 패킷의 수가 과도하게 증가하거나 송신측과 수신측의 전송 균형이 일치되지 않을 때 주로 발생한다. 이러한 혼잡과 지연은 패킷 손실 (pack loss)의 원인이 되며, 패킷손실은 멀티미디어 스트리밍의 성능을 떨어뜨릴 뿐만 아니라 오버헤드를 증가시킨다. 본 논문에서는 무선네트워크의 패킷 손실을 최적화하고 멀티미디어 스트리밍의 QoS 향상을 위한 전송율 기반의 멀티미디어 스트리밍의 최적화 메카니즘을 제안한다. 제안된 기법은 전송율 모니터링과 오버헤드 모니터링에 기반하여 최적화를 수행한다. 이러한 목적을 위하여 본 논문에서는 소스율 제어에 의한 최적화를 수행하도록 하며, 이것은 혼잡, 지연 등의 이슈들을 최적화하기 위한 것이다. 성능 평가는 RED (Random Early Detection), TFRC (TCP-friendly Rate Control) 그리고 제안된 기법으로 수행하였으며, 시뮬레이션 결과 제안된 기법이 RED, TFRC기법에 비해서 패킷손실율, 처리율, 평균 응답율이 보다 효율적임을 알게 되었다.

• 천문학논총
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• 제30권2호
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• pp.129-131
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• 2015

We have initiated single-dish monitoring observations of ~400 methanol maser sources at 6.7 GHz using the Hitachi 32-m radio telescope from December 2012 to systematically research periodic flux variations, which are observed in some methanol maser sources associated with high-mass (proto-)stars. In our monitoring, we have made daily monitoring, so that each source has been observed every nine days with an integration time of 5 min (typical $3{\sigma}$ detection sensitivities of 0.9 Jy). The monitoring observations help us statistically understand periodic flux variations with a period longer than 50 days. As an initial result, we present a new detection of periodic flux variations in the 6.7 GHz methanol maser source G 036.70+00.09. The period of the flux variations is ~53 days (~0.019 cycles $day^{-1}$), and seems to be stable over 9 cycles, at least until the middle of August 2014.

• 한국농공학회논문집
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• 제63권3호
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• pp.87-95
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• 2021

The Doam Lake Watershed is one of Gangwon-do's non-point source management areas. This area has a lot of snowfall in winter, and it is expected that there will be a lot of soil erosion in early spring due to snow melting. In this study, snow melting was monitored in the Doam Lake watershed from February to 3, 2020. It was conducted to analyze the water quality changes by calculating the concentration of non-point source pollution caused by snowmelt, and to compare the concentration of water quality during snowmelt event with rainfall and non-rainfall event. As a result of water quality analysis, Event Mean Concentration (EMC) at the first monitoring was SS 33.9 mg/L, TP 0.13 mg/L, TN 4.33 mg/L, BOD 1.35 mg/L, TOC 1.84 mg/L. At the second monitoring, EMC were SS 81.3 mg/L, TP 0.15 mg/L, TN 3.12 mg/L, BOD 1.32 mg/L, TOC 3.46 mg/L. In parameter except SS, it showed good water quality. It is necessary to establish management measures through continuous monitoring.

• 응용통계연구
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• 제31권1호
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• pp.1-11
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• 2018

최근 다변량 공정관리는 다양한 응용 분야에서 중요해지고 있는 추세이다. 예를 들어, 제조 산업 분야에서는 다변량 품질특성치를 동시에 모니터링할 필요가 있다. 그러나, 다변량 관리도는 이상신호가 발생한 경우 그 원인이 되는 개별적인 변수를 식별하기가 어렵기 때문에, 실제로는 기대만큼 유용하게 쓰이고 있지 않은 형편이다. 이에 본 논문에서는 새로운 관측치에 대한 개별적인 신뢰구간을 사용하여 이상신호의 원인을 탐지하는 세 가지 방법을 소개하고, 시뮬레이션 연구를 통해 이상신호의 원인이 되는 개별적인 변수를 식별하고 해석하는 데 있어 주의할 점이 무엇인지 살펴보기로 한다.

• 한국물환경학회지
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• 제24권2호
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• pp.169-173
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• 2008

A field monitoring was conducted in order to find out the discharge characteristics of non-point source pollutants in the agricultural area. Event Mean Concentration (EMC) of TSS, $BOD_5$, $COD_{Mn}$, TP, TN was calculated based on the monitoring data of 10 rainfall events at agricultural watersheds. A significant relationship was observed from the correlation between EMCs and rainfall characteristics. The result shows that EMC ranges of 95% confidence intervals were 50.5~203 mg/L for TSS, 0.8~14.2 mg/L for $BOD_5$, 4.2~20.7 mg/L for $COD_{Mn}$, 2.4~4.5 mg/L for TN and 0.2~0.5 mg/L for TP, respectively. The correlation coefficients between TSS and TP and between $BOD_5$ and $COD_{Mn}$ were found to be 0.912 and 0.961. But TN was lower correlated with other EMC factors. It was also found that rainfall characteristics was not correlated with EMCs.

• 콘크리트학회지
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• 제10권6호
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• pp.203-211
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• 1998

고체내부의 미소파괴시 발생하는 탄성파 방출을 이용하는 음향방출기법은 구조물 또는 재료 내부의 미시적 변형기구를 이해하는데 매우 유익한 수단으로 최근 각 분야에서 다양하게 응용되고 있다. 따라서 본 연구에서는 모르타르 부재의 휨재하 시험시 부재 내부에 발생하는 미시적 손상거동 및 파괴특성을 시험시 연속적으로 모니터링한 AE 신호특성으로부터 평가하였다. 나아가 삼각법을 이용한 2차원 AE 발생원 위치추정으로부터 시험체 노치선단 주변에 대한 AE 발생원 위치를 명확히 하였으며 이들 결과로부터 미소균열의 성장 거동을 연속적으로 모니터링 하였다.

• Smart Structures and Systems
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• 제9권5호
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• pp.461-472
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• 2012

This study proposes an optics-based active sensing system for continuous monitoring of underground pipelines in nuclear power plants (NPPs). The proposed system generates and measures guided waves using a single laser source and optical cables. First, a tunable laser is used as a common power source for guided wave generation and sensing. This source laser beam is transmitted through an optical fiber, and the fiber is split into two. One of them is used to actuate macro fiber composite (MFC) transducers for guided wave generation, and the other optical fiber is used with fiber Bragg grating (FBG) sensors to measure guided wave responses. The MFC transducers placed along a circumferential direction of a pipe at one end generate longitudinal and flexural modes, and the corresponding responses are measured using FBG sensors instrumented in the same configuration at the other end. The generated guided waves interact with a defect, and this interaction causes changes in response signals. Then, a damage-sensitive feature is extracted from the response signals using the axi-symmetry nature of the measured pitch-catch signals. The feasibility of the proposed system has been examined through a laboratory experiment.