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채종철,윤형선,서성규 國立麗水大學校 環境問題硏究所 2004 環境硏究論文集 Vol.6 No.-
The objective method, combined sensory and instrumental analysis, was desired to evaluation of intensity as well as odor active compounds because malodor is sensory pollution. The Seonso area was classified into seaside, residential and reference area. Target compounds were sulfur compounds such as hydrogen sulfide(H₂S). methyl mercaptan(CH₃SH), dimethyl sulfide((CH₃)₂S)and dimethyl disulfide((CH₃)₂S₂). The odor intensity at Seonso area in Yeosu city was set in order as follows : reference area < residential area < seaside area. There was a difference of the odor intensity between the summer and the winter at seaside area. Most of the odor intensity identified at seaside area(S-3) was exceeded the Korean odor regulations(the level 3.0). The concentrations of dimethyl sulfide, dimethyl disulfide were not significantly changed with sampling time and site. However, the concentration of hydrogen sulfide and methyl mercaptan at S-3 site were higher than other sites and these concentrations of the summer were higher than that of the winter. The concentrations of hydrogen sulfide at the sediments of R-1, S-1, S-2, S-3 sites by the Gastec detection tube were 0.16, 1.26, 0.43 and 2.20㎎/g-dry respectively. The order of major odor active compounds related to Seonso area were dimethyl disulfide < dimethyl sulfide < methyl mercaptan < hydrogen sulfide.
PERFORMANCE OF THE AUTOREGRESSIVE METHOD IN LONG-TERM PREDICTION OF SUNSPOT NUMBER
채종철,김연한 한국천문학회 2017 Journal of The Korean Astronomical Society Vol.50 No.2
The autoregressive method provides a univariate procedure to predict the future sunspot number (SSN) based on past record. The strength of this method lies in the possibility that from past data it yields the SSN in the future as a function of time. On the other hand, its major limitation comes from the intrinsic complexity of solar magnetic activity that may deviate from the linear stationary process assumption that is the basis of the autoregressive model. By analyzing the residual errors produced by the method, we have obtained the following conclusions: (1) the optimal duration of the past time for the forecast is found to be 8.5 years; (2) the standard error increases with prediction horizon and the errors are mostly systematic ones resulting from the incompleteness of the autoregressive model; (3) there is a tendency that the predicted value is underestimated in the activity rising phase, while it is overestimated in the declining phase; (5) the model prediction of a new Solar Cycle is fairly good when it is similar to the previous one, but is bad when the new cycle is much different from the previous one; (6) a reasonably good prediction of a new cycle can be made using the AR model 1.5 years after the start of the cycle. In addition, we predict the next cycle (Solar Cycle 25) will reach the peak in 2024 at the activity level similar to the current cycle.
채종철,박형민,양희수,박영득,조경석,안광수,Chae, Jongchul,Park, Hyungmin,Yang, Heesu,Park, Young-Deuk,Cho, Kyung-Suk,Ahn, Kwangsu,Cao, Wenda 한국천문학회 2012 天文學會報 Vol.37 No.2
The characteristics of Doppler shifts in a quiet region of the Sun are investigated by comparing between the $H{\alpha}$ line and the Caii infrared line at 854.2 nm. A small area of $16^{\prime\prime}{\times}40^{\prime\prime}$ was observed for about half an hour with the Fast Imaging Solar Spectrograph (FISS) of the 1.6 meter New Solar Telescope (NST) at Big Bear Solar Observatory. The observed area contains a network region and an internetwork region, and identified in the network region are $H{\alpha}$ fibrils, Caii fibrils and bright points. We infer the Doppler velocity from each line profile at a point with the lambdameter method as a function of half wavelength separation ${\Delta}{\lambda}$. It is confirmed that the bisector of the spatially-averaged Caii line profile has an inverse C-shape of with a significant peak redshift of +1.8 km/s. In contrast, the bisector of the spatially-averaged $H{\alpha}$ line profile has a different shape; it is almost vertically straight or, if not, has a C-shape with a small peak blueshift of -0.5 km/s. In both the lines, the bisectors of bright network points are much different from those of other features in that they are significantly redshifted not only at the line centers, but also at the wings. We also find that the spatio-temporal fluctuation of Doppler shift inferred from the Caii line is correlated with those of the $H{\alpha}$ line. The strongest correlation occurs in the internework region, and when the inner wings rather than the line centers are used to determine Doppler shift. In this region, the RMS value of Doppler shift fluctuation is the largest at the line center, and monotonically decreases with ${\Delta}{\lambda}$. We discuss the physical implications of our results on the formation of the $H{\alpha}$ line and Caii 854.2 nm line in the quiet region chromosphere.