• 한국환경과학회지
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• 제16권2호
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• pp.187-195
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• 2007

Long-term passive diffusive samplers(PDS) have been used to measure $NO_2\;and\;SO_2$ concentrations at 21 sampling sites in Daejeon, Korea during the period of January 2000 - December 2002. The spatial distributions of annual $NO_2\;and\;SO_2$ concentrations were mapped. Average annual $NO_2$ concentration over the sampling period was $28.5{\pm}12.5\;ppb$, ranging from 1.2 to 81.7 ppb. Average annual $SO_2$ concentration over the sampling period was $7.7{\pm}4.8\;ppb$, ranging from 0.6 to 26.8 ppb. On average, $NO_2$ concentration was approximately 5.8%(1.6 ppb) larger in 2002. $SO_2$ concentration was decreased by 13%(1.1 ppb) during the sampling period. The seasonal variation of $NO_2\;and\;SO_2$ concentration was observed with a tendency to be higher in fall and winter. $NO_2\;and\;SO_2$, concentrations measured at different site types(patterns of land use) show significant difference. The observed difference in concentration was associated with difference in emissions of $NO_2$ from motor vehicles and $SO_2$ by non-traffic fuel consumption for heating.

• 한국지반환경공학회 논문집
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• 제16권5호
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• pp.43-53
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• 2015

본 연구에서는 빅데이터 범주에 포함되는 각종 계측 데이터를 대상으로 각종 이상치를 판단하기 위한 기법을 고안하고, 인공 데이터 및 실 계측 데이터를 이용한 이상치 분석을 수행하였다. 계측결과에 대한 1차 차분 값 및 오차율을 적용한 규칙기반 방법은 큰 규모의 Short fault 분석 및 일정 기간 계측값에 변화가 발생하지 않는 경우의 Constant fault 분석에 효과적으로 적용될 수 있었으나, 독립적인 단일 데이터셋만을 이용하는 관계로 큰 변화폭을 보이는 실 계측 데이터의 정상 데이터를 이상치로 오판하는 문제점이 있었다. 규칙기반 방법을 이용한 Noise fault 분석은 적정 데이터 윈도우 사이즈의 선택 및 이상치 판정용 한계값 선정상의 문제로 인해 실 계측 데이터 적용에 한계가 있었다. 이종 데이터 간 상관분석 방법은 학습 데이터의 적정범위 선정이 선행된다면 장단기 계측 데이터의 이상 거동 및 국부적 이상치 판정에 매우 효과적으로 이용될 수 있음을 알 수 있었다.

• 한국재난정보학회 논문집
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• 제15권1호
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• pp.28-38
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• 2019

연구목적: 본 연구는 건설 계측센서의 내구연한 저하원인 및 개선방안을 상세히 제시하여 건설구조물의 계측관리 수준향상과 계측센서의 기술발전에 기여하고자 한다. 연구방법: 건설 계측센서의 내구연한 저하원인 및 개선방안에 대하여 건설분야와 전기전자분야로 구분하여 상세한 현황을 조사하고 검토를 실시하였다. 연구결과: 건설분야는 승인 및 검수, 검사 및 시험, 검정 및 교정, 손망실율 최소화 방안 등을 조사 검토하였고, 전기전자분야는 센서패키지 및 실링, 응력집중부위 단선, 낙뢰 및 부식에 의한 손상 등을 조사 검토하였다. 결론: 건설분야와 전기전자분야에서 계측센서의 내구연한 저하원인 및 개선방안을 토대로 건설현장에 적용되는 계측센서의 내구연한이 현재보다 연장될 것으로 기대된다.

• 한국방재학회 논문집
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• 제9권5호
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• pp.115-123
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• 2009

수량과 수질에 관한 정보는 수자원 관리뿐만 아니라 수공구조물의 계획, 설계 및 운영에 필수적인 자료로 활용된다. 우리나라에서 수량과 수질에 대한 정보는 목적에 따라 여러 기관에 의해 관측되고 있어 많은 문제점이 발생하고 있다. 본 연구에서는 기술적 측면과 법, 제도 측면에서 수량과 수질 연계방안에 대하여 다음과 같은 다양한 대안을 제시하였다. 먼저 국가수문관측계획 및 국가물정보관리계획, 부처간 관측 표준과 정보인증 과정에 대한 협의, 관련 법령(하천법과 수질관련법)의 개정이 필요하다. 또한 현재 설치되어 있는 수량 수질관측소를 유지하고 신규관측소나 교체해야 할 관측소에 대해서는 통합관측을 수행하며, 자료의 관리 및 유통에 대한 단일 기구를 설립해야 한다. 그리고 관측기준을 명확히 확립해야 하며, 통합관리안을 만족시키기 위해 각 부처별로 산재된 정보를 중앙집중식으로 자료 관리를 수행해야 한다. 마지막으로 각 부처별 자료의 신뢰도 및 자료품질에 대한 검증이 우선적으로 수행되어야 한다. 다양한 이해관계 때문에 단기간 내에 수량과 수질 연계관측에 관한 문제들을 해결한다는 것은 어려운 일이나 본 연구에서 도출된 법, 제도, 기술적 제안사항들은 중, 장기적으로 수량과 수질 관측의 효율적인 연계방안에 도움이 될 수 있을 것으로 판단된다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.528-535
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• 2011

According to railway safety regulations for securing the railway vehicle's quality and performance, it can be partly exempted that the performance tests and production inspections on the railway vehicles which are produced and assembled for the purpose of test and research. The reasons of this exemption are for ensuring maximum autonomy and for saving time considered the development period of railway vehicle. However, it was continuously demanded the necessity of supplementation on the confirmation about railway vehicle's quality & performance. Therefore, we added "The monitoring step" which is for securing the quality and performance in high speed railway vehicle's subsystem & compartment to supplement those tests & inspections in development. In this paper, based on a standard ABS(Activity Breakdown Structure) of railway vehicle and a WBS(Work Breakdown Structure) of the railway vehicle system, we investigate the necessity of monitoring in the High speed railway vehicle development. And by comparing and analyzing the essential requirements of international standard, IRIS(International Railway Industry Standard) & TSI(Technical Specification for Interoperability), we try to examine a standard monitoring procedure.

• Smart Structures and Systems
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• 제15권2호
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• pp.395-408
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• 2015

This study aims to propose a Bayesian approach to consider changes in temperature and vehicle weight as environmental and operational factors for vibration-based long-term bridge health monitoring. The Bayesian approach consists of three steps: step 1 is to identify damage-sensitive features from coefficients of the auto-regressive model utilizing bridge accelerations; step 2 is to perform a regression analysis of the damage-sensitive features to consider environmental and operational changes by means of the Bayesian regression; and step 3 is to make a decision on the bridge health condition based on residuals, differences between the observed and predicted damage-sensitive features, utilizing 95% confidence interval and the Bayesian hypothesis testing. Feasibility of the proposed approach is examined utilizing monitoring data on an in-service bridge recorded over a one-year period. Observations through the study demonstrated that the Bayesian regression considering environmental and operational changes led to more accurate results than that without considering environmental and operational changes. The Bayesian hypothesis testing utilizing data from the healthy bridge, the damage probability of the bridge was judged as no damage.

• Journal of Chest Surgery
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• 제50권6호
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• pp.448-452
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• 2017

Background: Proper monitoring of cerebral perfusion during carotid artery surgery is crucial for determining if a shunt is needed. We compared the safety and reliability of near-infrared spectroscopy (NIRS) w ith transcranial Doppler (TCD) for cerebral monitoring. Methods: This single-center, retrospective review was conducted on patients who underwent carotid endarterectomy (CEA) using selective shunt-based TCD or NIRS at Daegu Catholic University Medical Center from November 2009 to June 2016. Postoperative complications were the primary outcome, and the distribution of risk factors between the 2 groups was compared. Results: The medical records of 74 patients (45 TCD, 29 NIRS) were reviewed. The demographic characteristics were similar between the 2 groups. One TCD patient died within the 30-day postoperative period. Postoperative stroke (n=4, p=0.15) and neurologic complications (n=10, p=0.005) were only reported in the TCD group. Shunt usage was 44.4% and 10.3% in the TCD and NIRS groups, respectively (p=0.002). Conclusion: NIRS-based selective shunting during CEA seems to be safe and reliable for monitoring cerebral perfusion in terms of postoperative stroke and neurologic symptoms. It also reduces unnecessary shunt usage.

• 천문학회보
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• 제38권2호
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• pp.54-54
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• 2013

We performed spectroscopic and photometric monitoring observations of a QSO, PG0934+013 for a reverberation-mapping analysis, using the 9-m Southern African Large Telescope (SALT) for spectroscopy and the 2-m Faulkes Telescope North and the South for photometry. The monitoring campaign was carried out for 5 month between December 2012 to April 2013, providing 20 spectroscopic epochs and ~40 photometric epochs. Based on the obtained spectra, which typically have a signal-to-noise ratio to 30-60, we performed multicomponent decomposition using various components, i.e., power-law continuum, FeII emission complex, and broad and narrow emission lines, to properly measure the Hbeta line flux. After a flux normalization using [O III] 5007 line luminosity, we obtained a rms spectrum from all epochs, which shows clear variability of Hbeta line. We find that Hbeta line flux decreases by ~20% during the monitoring period while the continuum flux obtained from the aperture photometry based on the imaging data, shows similar variability. The current Hbeta light curve shows monotonic decrease and a reliable cross correlation analysis between Hbeta and continuum light is difficult. Nevertheless, we obtained a preliminary lag measurements as ~24 light days.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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• pp.1400-1402
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• 2003

The objective of this paper is to determine the suitable spectral bands for monitoring growth status change during a long period. The long-term ground-level reflectance spectra as well as LAI and biomass were obtained in xiaotangshan area, Beijing, 2001. The narrow-band NDVI type spectral indices by all possible two bands were calculated their correlation coefficients R$^2$ with biomass and LAI. The best NDVIs must have higher R$^2$ with both biomass and LAI. The reasonable band centers and band widths were determined by a systematically increasing bandwidth centered over a wavelength. In addition, the first 19 bands of MODIS were simulated and investigated. Each developed spectral indices was then validated by the biomass and LAI time series using the generalized vector angle. It turned out that six new NDVI type indices within 750-1400nm were developed. NDVI(811_10,957_10) and NDVI(962_10,802_10) performed best. No satisfactory conventional NDVI formed by red and NIR bands were found effective. MODIS_NDVI(band19, band17) and MODIS_NDVI(band19, band2) were much better than MODIS_NDVI(band2,band1) for growth monitoring.

• 한국대기환경학회지
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• 제10권1호
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• pp.41-48
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• 1994

A monitoring system for atmospheric CFC-12 and CFC-11 has been established at Mt. Kwan-Ak, Seoul National University (SNU) since July, 1991. The concentrations showed quite a large variation ranging from 495 to 37600 pptv (pptv=part per trillion, 10$^{-12}$ , v/v) for CFC-12 and from 233 to 12100 pptv for CFC-11 due to many local sources. However, monthly medians show rather limited ranges ; 553~765 pptv for CFC-12 and 301~431 pptv for CFC-11. Furthermore minimum concentrations could be defined relatively well during the whole period of observation. The regional background concentrations in 1993 near SNU wer estimated as 533 pptv for CFC-12 and 293 pptv for CFC-11. These values are very comparable to global averages in Northern Hemisphere, 523 pptv for CFC-12 and 287 pptv for CFC-11, reflecting the fast atmospheric mixing processes within the hemisphere. Examinations with meteorological parameters such as wind speed and direction suggest the possible measurement-window at SNU, appropriate for regional monitoring. Studies for improving the monitoring capability of the SNU station such as automation of the analysis system along with correlation with other meteorological parameters, are in progress at the present time.