• Journal of Korean Society for Atmospheric Environment
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• v.9 no.1
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• pp.61-68
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• 1993

Since November 1990, the observations of carbon dioxide$(CO_2)$ levels have been carried out at Tae-ahn Peninsula(TAP) in Korea. Analysis on atmospheric data obtained in the period from November 1990 to August 1992 is carried out and the results are included in this study. It is observed that variations of monthly average level on $CO_2$ are in the range of 315.72 $\sim$ 365.37ppm(amplitude 17.65ppm). The seasonal variation is large with a maximum occurring in March-April and with a minimum in July-August. A comparison of TAP data is made with data obtained at Ryori in Japan for 1991. The annual average value of TAP is 1.79ppm higher than that of Ryori. It is also found that in summer the minimum level of $CO_2$ at TAP is almost same as the $CO_2$ level occurring at Quinghai Province in China and at Ulaan Uul in Mongolia. Albeit, a maximum concentration of $CO_2$ at TAP is slightly higher than that of the same gas observed at other sites in spring. We interpret that TAP is generally under the influence of airflows coming from China. According to analysis of trajectories and airflows, we find the high values of $CO_2$ when an air flow is originated mainly from China and when an airflow is both of local(Korea) and of China origins. In contrast, when an airflow of maritime origin arrives, a low value of the atmospheric constituent is observed at TAP.

• Journal of Ecology and Environment
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• v.41 no.6
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• pp.165-172
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• 2017

Background: This study investigated the temporal variation in soil $CO_2$ efflux and its relationship with soil temperature and precipitation in the Quercus glauca and Abies koreana forests in Jeju Island, South Korea, from August 2010 to December 2012. Q. glauca and A. koreana forests are typical vegetation of warm-temperate evergreen forest zone and sub-alpine coniferous forest zone, respectively, in Jeju island. Results: The mean soil $CO_2$ efflux of Q. glauca forest was $0.7g\;CO_2\;m^{-2}\;h^{-1}$ at $14.3^{\circ}C$ and that of A. koreana forest was $0.4g\;CO_2\;m^{-2}\;h^{-1}$ at $6.8^{\circ}C$. The cumulative annual soil $CO_2$ efflux of Q. glauca and A. koreana forests was 54.2 and $34.2t\;CO_2\;ha^{-1}$, respectively. Total accumulated soil carbon efflux in Q. glauca and A. koreana forests was 29.5 and $18.7t\;C\;ha^{-1}$ for 2 years, respectively. The relationship between soil $CO_2$ efflux and soil temperate at 10 cm depth was highly significant in the Q. glauca ($r^2=0.853$) and A. koreana forests ($r^2=0.842$). Soil temperature was the main controlling factor over $CO_2$ efflux during most of the study period. Also, precipitation may affect soil $CO_2$ efflux that appeared to be an important factor controlling the efflux rate. Conclusions: Soil $CO_2$ efflux was affected by soil temperature as the dominant control and moisture as the limiting factor. The difference of soil $CO_2$ efflux between of Q. glauca and A. koreana forests was induced by soil temperature to altitude and regional precipitation.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 1999.10a
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• pp.269-271
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• 1999

온실기체농도에 대한 감시는 전세계적으로 미국의 NOAA(National Oceanic and Atmospheric Administration)/CMDL(Climate Monitoring and Diagnostic Laboratories)의 관측망을 비롯하여 세계기상기구(WMO)의 지구대기감시(GAW)계획에 의하여 수행되고 있다(Keeling et al., 1976 ; Komhyr et al., 1989). 기상청에서는 온실기체의 관측을 위하여 1994년에 전남 무안의 무안기상대에 비분산적외선 이와 같이 측정된 $CO_2$농도자료가 배경대기관측자료로써의 신뢰를 받기 위해서는 적절한 질관리를 통하여 인간 및 생물의 활동에 의한 직접적인 영향 제거하여야 한다.(중략)

• Journal of Ecology and Environment
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• v.43 no.2
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• pp.212-218
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• 2019

Background: Allelopathy has been suggested as one potential mechanism facilitating the successful colonisation and expansion of invasive plants. The impacts of the ongoing elevation in atmospheric carbon dioxide (CO₂) on the production of allelochemicals by invasive species are of great importance because they play a potential role in promoting biological invasion at the global scale. Common ragweed (Ambrosia artemisiifolia var. elatior), one of the most notorious invasive exotic plant species, was used to assess changes in foliar mono- and sesquiterpene production in response to CO₂ elevation (389.12 ± 2.55 vs. 802.08 ± 2.69 ppm). Results: The plant growth of common ragweed significantly increased in elevated CO₂. The major monoterpenes in the essential oil extracted from common ragweed leaves were β-myrcene, DL-limonene and 1,3,6-octatriene, and the major sesquiterpenes were β-caryophyllene and germacrene-D. The concentrations of 1,3,6-octatriene (258%) and β-caryophyllene (421%) significantly increased with CO₂ elevation. Conclusions: These findings improve our understanding of how allelochemicals in common ragweed respond to CO₂ elevation.

• Korean Journal of Optics and Photonics
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• v.4 no.2
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• pp.212-219
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• 1993

To reduce the mode noise induced from a multimode dye laser, a modeless laser generating amplified spontaneous emission was used as Stokes beam of the broadband CARS. A new technique for measuring species concentration from the modulation dip of nonresonant background of broadband CARS spectrum was proposed. The modulation dip was numerically calculated and fitted as a function of the concentration of the minor species and temperature of gas sample. We applied this technique in measuring CO concentration in a static cell and also the profile of CO concentration in a CHdair premixed flame of a counterflow burner.

• 보존과학연구
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• s.15
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• pp.21-32
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• 1994

Optimum conditions for benzene synthesis and liquid scintillation counting have been studied for the determination of radiocarbon age. In benzene synthesis the carbon dioxide converted to benzene with high efficiency of 91%. Yields of each step with 10L of carbon dioxide were $CO_2$ $\rightarrow$$C_2H_2$(94%), $C_2H_2$$\rightarrow$$C_6H_6$(96%) and$CO_2$$\rightarrow$$C_6H_6$(91%), respectively. Benzene synthesized from oxalate was measured with purity of 95% by GC /MS. $\delta^13$(C$^13$C/$^12$C) of oxalate was measured to $-24.7\{textperthousand}$ by massspectrometer. For liquid scintillation counting of benzene sample low background and highest FOM were measured in 0.5 ml cocktail and 3 ml standard solution with the range of 15.4∼74.9 KeV window setting. Oxalate and background samples weremeasured to $28.7\pm0.12$cpm and $3.92\pm0.04$ cpm in 15.4∼74.9 KeV

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.90-95
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• 2003

Chemical management of annulus gas system is carried out for the purpose of ensuring the safety and reliability of the system via securing the integrity of the system, detecting the D$_2$O in-leakage of coolant and/or moderator, and reducing the radiation dose. Since the quality of CO_2$ gas, which is used as a filling gas for annulus gas system at CANDU plants, has a propound effect on the integrity of the system material and the radiation dose, CO_2$ gas of high quality is needed. If the quality of CO_2$ gas does not meet the specification, it may give rise to undesirable effect not only on the annulus gas system, but also on the environment due to the production of radioactive nuclei. Therefore, it is very important to check the impurities of CO_2$ gas. Based on this background, the inventories of C-14 and Ar-41 in CO_2$ gas that is supplied as annulus gas were estimated using the data on concentrations of the impurities of $CO_2$ such as C, N_2$ and Ar. The results of this study is expect to give useful information on optimization of CO_2$ impurities maintenance and management of gaseous radioactive wastes produced at CANDU plants.

• Journal of the Korean Society of Radiology
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• v.12 no.2
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• pp.123-131
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• 2018

This study compared PENELOPE with measured values from low energy peak to high energy peak to reduce peak to compton ratio and continuum background spectrum using $^{60}Co$, $^{137}Cs$ and mixed volume source. In addition, the change in backscattering and compton edge efficiency was compared with that of PENELOPE through changes in the vicinity of low energy. The results from the mixed volume source are applied to the soil samples to determine how much the minimum detection limits of the soil samples are reduced in the suppression and unsuppressed mode. The compton suppression of the low energy region of $^{60}CO$ (1,173 keV) was considerable, and the Compton edge RF for the $^{137}Cs$ (661 keV) peak was 2.8. In particular, the $^{60}Co$ source emits coincidence gamma rays of 1,173.2 keV and 1,332.5 keV, so compton inhibition was reduced by approximately 21%. RF of compton edges of 1,173 keV and 1,332 keV emitted from a $^{60}Co$ source was 3.2 and 3.4, and the peak to compton edge ratio was improved to 8: 1. And Compared with Penelope, the uncertainty was well within 2%. In compton unsuppressed mode, MDA values of 661 keV, 1,173 keV and 1,332 keV were 0.535, 0.173 and 0.136 Bq/kg, respectively, but decreased in compton suppressed mode to 0.121, 0.00826 and 0.00728 Bq/kg. Thus, Compton suppressed could reduce the background radioactivity and the radioactivity contained in the detector itself.

• Perspectives in Nursing Science
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• v.16 no.1
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• pp.12-24
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• 2019

Purpose: This study examined the suitability of using text network analysis (TNA) methodology for topic analysis of academic papers related to nursing. Methods: TNA background theories, software programs, and research processes have been described in this paper. Additionally, the research methodology that applied TNA to the topic analysis of the academic nursing papers was analyzed. Results: As background theories for the study, we explained information theory, word co-occurrence analysis, graph theory, network theory, and social network analysis. The TNA procedure was described as follows: 1) collection of academic articles, 2) text extraction, 3) preprocessing, 4) generation of word co-occurrence matrices, 5) social network analysis, and 6) interpretation and discussion. Conclusion: TNA using author-keywords has several advantages. It can utilize recognized terms such as MeSH headings or terms chosen by professionals, and it saves time and effort. Additionally, the study emphasizes the necessity of developing a sophisticated research design that explores nursing research trends in a multidimensional method by applying TNA methodology.

• Journal of the Korean earth science society
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• v.33 no.1
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• pp.32-38
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• 2012

Mean background concentrations of greenhouse gases such as $CO_2$ and $CH_4$ were estimated on Ulleungdo using PICARRO Cavity Ring-Down Spectroscopy (CRDS) analyzer. To improve the accuracy of $CO_2$ and $CH_4$ concentrations, a standardized QA${\cdot}$QC (Quality Assurance Quality Control) procedure was employed with three steps: 1) the inspection procedure of physical limitation (e.g. the exclusion of data corresponding to the number of data of ${\leq}$50%) for hourly mean values, 2) a stage inspection (e.g. the use of data corresponding to ${\geq}15$ observations per day) for daily mean values, and 3) a fast fourier transform (FFT) analysis using curve-fitting methods for the investigation of climatic characteristics. The monthly mean concentrations of $CO_2$ and $CH_4$ derived from three-step QA${\cdot}$QC procedure were then compared with those observed at Anmyundo (Korea) and Ryori (Japan). Overall, the error of mean $CO_2$ and $CH_4$ concentrations estimated in this study distinctly decreased. However, in comparison with their concentrations monitored at Ryori, the $CO_2$ concentration at estimated at Ulleungdo is soemwhat lower than that of Anmyundo due to the missing data, which is statistically significant. On the other hand, the former has a statistically significant higher value of $CH_4$ that of the latter.