• 천문학회보
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• 제46권2호
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• pp.66.2-66.2
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• 2021

We list up the Paα-emitting sources observed in the Carina Region (l = 276°-296°) using the MIRIS Paα Galactic Plane Survey data. A total of 201 sources are cataloged. Out of them, 118 sources are coincident with those in the WISE H II region catalog. 52 H II region candidates are newly confirmed as definite H II regions by detecting the Paα recombination lines. For the remaining 83 sources, we search the corresponding objects in the SIMBAD database. 26 point-like sources are associated with planetary nebulae or emission-line stars (such as Wolf-Rayet and Blue supergiant stars). Also, we carry out aperture photometry to measure Paα fluxes for the sources that show circular features without overlapping with other bright sources. For the whole Galactic Plane, the complete Paα-emitting source catalog is in progress.

• 한국대기환경학회지
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• 제25권3호
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• pp.219-236
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• 2009

Particle-phase organic tracers (molecular markers) have been shown to be an effective method to assess and quantify the impact of sources of carbonaceous aerosols. These molecular markers have been used in chemical mass balance (CMB) models to apportion primary sources of organic aerosols in regions where the major organic aerosol source categories have been identified. As in the case of all CMB models, all important sources of the tracer compounds must be included in a Molecular Marker CMB (MM-CMB) model or the MMCMB model can be subject to biases. To this end, the application of the MM-CMB models to locations where reasonably accurate emissions inventory of organic aerosols are not available, should be performed with extreme caution. Of great concern is the potential presence of industrial point sources that emit carbonaceous aerosols and have not been well characterized or inventoried. The current study demonstrates that emissions from industrial point sources in the St. Louis, Missouri area can greatly bias molecular marker CMB models if their emissions are not correctly addressed. At a sampling site in the greater St. Louis Area, carbonaceous aerosols from industrial point sources were found to be important source of carbonaceous aerosols during specific time periods in addition to common urban sources (i.e. mobile sources, wood burning, and road dust). Since source profiles for these industrial sources have not been properly characterized, method to identify time periods when point sources are impacting a sampling site, needs to avoid obtaining biases source apportionment results. The use of real time air pollution measurements, along with molecular marker measurements, as a screening tool to identify when point sources are impacting a receptor site is presented.

• 기술혁신학회지
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• 제9권3호
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• pp.412-434
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• 2006

본 연구는 기업형태를 자율성 측면과 기업 규모 측면으로 구분하여 그 주요 특성에 따른 신제품 개발역량과 아이디어의 원천을 규명하고자 하였다. 신제품 개발역량에 있어, 외국자회사가 국내기업에 비해 우수하고, 중소기업이 대기업에 비해 우수한 것으로 나타났다. 신제품 개발을 위한 아이디어의 원천에 있어서는 기업 내부자원의 활용도와 기업 외부자원의 활용도의 비교에 있어 독립기업이 광범위한 외부 자원 네트워크를 가진 그룹계열사에 비해 외부자원을 더 활발히 활용하고 있으며, 국내기업이 외국자회사에 비해 내부자원과 외부자원 모두를 더 활발히 활용하고 있는 것으로 나타났다. 또한, 다양한 외부자원의 흡수 통합 역량의 차이로 중소기업은 내부자원을 더 활발히 활용하고 있었고, 대기업은 기업 외부자원을 더 활발히 활용하는 것으로 분석되었다.

• 한국소음진동공학회논문집
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• 제13권10호
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• pp.743-750
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• 2003

The equivalent source method(ESM) is used for the calculation of the internal pressure field for an enclosure which can have arbitrary boundary conditions and nay include internal objects which scatter the sound field. The advantage of using ESM is that it requires relatively low computing cost and is easy to model the internal diffracting objects. Typical ESM modeling uses two groups of equivalent source positions. One group includes the first order images of the source inside the enclosure. The Positions of the other group are usually on a spherical surface some distance outside the enclosure. The normal velocity on the surfaces of the enclosure walls is evaluated at a larger number of positions than there are equivalent sources. The sum of the squared difference between this velocity and the expected is minimized by adjusting the strength of the equivalent sources. This study is on the optimal far field sources positions when using the equivalent source method. In general, the far field sources are evenly distributed on a surface of a virtual sphere which is centered at the enclosure with a sufficiently large radius. In this study. optimal far field source locations are searched using simulated annealing method for various radii of spheres where far field sources are located. Simulation results showed that optimally located sources with adequate distance away from the enclosure center gave better result than sources with even distribution even with a smaller number of far field sources.

• 천문학회보
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• 제36권2호
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• pp.145.2-145.2
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• 2011

We present the results of simultaneous observations of SiO v = 1, 2, J = 1-0, $^{29}SiO$ v = 0, J = 1-0, and $H_2O$ $6_{16}-5_{23}$ maser lines toward 152 known $H_2O$-only maser sources (the sources which are previously detected only in the 22 GHz $H_2O$ maser emission) using Yonsei and Tamna 21-m radio telescopes of the Korean VLBI Network from 2009 June to 2011 January. Both SiO and $H_2O$ maser emission were detected from 62 sources giving a detection rate of 40.8 %. SiO-only maser emission was detected from 27 sources, while $H_2O$-only maser was detected from 22 sources. We have identified 19 new detections of SiO maser emission for previous non-detection sources and 51 new detections of SiO maser for previously not observed sources. Characteristics of all observed sources in the IRAS two-color diagram is investigated including their evolutionary sequence and mutual relations between SiO and $H_2O$ maser emission. These observational results will be useful for statistical study of asymptotic giant branch (AGB) stars and future VLBI observation.

• Journal of Preventive Medicine and Public Health
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• 제54권4호
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• pp.245-250
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• 2021

Objectives: Jeju Province in Korea reported 627 coronavirus disease 2019 (COVID-19) cases between January 20, 2020, and March 31, 2021. This study analyzed the sources of infection among confirmed cases in Jeju Province, a self-governed island. Methods: The sources of infection were broadly categorized as follows: (1) infections from overseas (confirmed patients who reported travel overseas or contact with overseas travelers); (2) infections from outside Jeju Province (confirmed patients who had visited other provinces or had contact with individuals who had traveled to other provinces in Korea); and (3) unknown sources of infection (confirmed patients who were infected following contact with an infected person whose source of infection was unknown). The chi-square test was used to analyze the differences in the distributions of related variables for each source of infection. Results: Of the 627 confirmed cases, 38 (6.1%) were infections from overseas sources, 199 (31.7%) were from outside of Jeju Province, and 390 (62.2%) were from unknown sources. Jeju Province had no cases with an unknown source of infection during the first and second waves of the nationwide outbreak. Conclusions: Infections from overseas sources could be blocked from spreading to local communities in Jeju Province by conducting screening at the airport, along with the preemptive suspension of visa-free entry. In addition, considering the scale of the nationwide outbreak, measures must be established to delay outbreaks from unknown sources of infection caused by sources outside Jeju Province.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2022년도 학술발표회
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• pp.475-475
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• 2022

The aim of this study is to identify the significant pollutant sources from the tributaries that are affecting the water quality of the study site, the Geum River and provide a solution to enhance the water quality. Multivariate statistical analysis modles such as cluster analysis, Principal component analysis (PCA) and positive matrix factorization (PMF) were applied to identify and prioritize the major pollutant sources of the two major tributaries, Gab-cheon and Miho-cheon, of the Geum River. PCA identifies three major pollutant sources for Gab-cheon and Miho-cheon, respectively. For Gab-cheon, wastewater treatment plant (WWTP), urban, and agricultural pollutions are identified as major pollutant sources. For Miho-cheon, agricultural, urban, and forest land are identified as major pollutant sources. On the contrary, PMF identifies three pollutant sources in Gab-cheon, same as PCA result and two pollutant sources in Miho-cheon. Water quality control scenarios are formulated and improvement of water quality in the river locations are simulated and analyzed with the Environmental Fluid Dynamic Code (EFDC) model. Scenario results were evaluated using a water quality index developed by Canadian Council of Ministers of the Environment. PCA and PMF appears to be effective to identify water pollution sources for the Geum river and also its tributaries in detail and thus can be used for the development of water quality improvement alternative of the above water bodies.

• 천문학회지
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• 제21권2호
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• pp.133-153
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• 1988

Linear polarization has been measured for fifteen extragalactic radio sources in the field of supernova remnant S 147. These observations were made at 4885, 4835, 1665, 1515, 1465, and 1385 MHz using the Very Large Array, primarily to determine unambiguous Rotation Measures (RM) of the sources. This yields a total of 11 new RM sources. Comparisons of a sample of sources which are seen through S 147 were made with sources located farther away. The result tentatively indicates that the distribution of the rotation measure of the former population is broadened, with more than a 85% level of confidence. This constitutes evidence that there is a SNR contribution to rotation measure in sources seen through the SNR. Limits on this RM contribution are statistically at 30 < | RM | < 70 rad $m^{-2}$ with a 85% statistical level of confidence. These result imply the magnetic field in the rim of S 147 has strength 10 microguass if the electron density is $1\;cm^{-3}$.

• KIEE International Transactions on Electrophysics and Applications
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• 제3C권5호
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• pp.177-181
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• 2003

Partial discharge pulse shapes from variable PD (partial discharge) sources sustain many characteristics such as types of PD. Ultra high frequency antennas have wide bandwidth from 30KHz to 2㎓. Therefore, signals taken from a UHF antenna have important attributes (rising time, falling time, shape factor, etc.) for electromagnetic sources, such as PD sources. We investigated PD pulse shapes from several PD sources using a UHF antenna and the results were used for classification of PD sources. Features for discrimination are extracted from frequency distribution and LPC (Linear Prediction Coefficient) of time signal. RBFN are used for investigating the possibility of classification of multi-PD sources.

• 설비공학논문집
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• 제3권3호
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• pp.197-205
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• 1991

A numerical study has been performed to investigate two dimensional natural convection heat transfer in a rectangular enclosure with heat sources of constant temperature at the bottom. Calculations were made for various dimensionless heat source lengths, W/L=0.1-0.5, and positions of heat sources at $Gr=2.57{\times}10^6$, Pr=0.71 and Ks/Kf=28.98. For various positions of heat sources, the maximum local Nusselt numbers generally show X=0.81-0.85 at the bottom and X=0.23 at the top. For various dimensionless heat source lengths, the maximum local Nusselt numbers at the bottom show W/L=0.4 for one heat source, W/L=0.2 for two heat sources with fixed centers, W/L=0.5 for two heat sources with moved centers. Finally the maximum heat transfer at the bottom exhibits in condition of W/L=0.4 for two heat sources with moved centers.