• Journal of Korean Society for Atmospheric Environment
• /
• v.17 no.3
• /
• pp.277-288
• /
• 2001

Continuous atmospheric CO$_2$measurements measured during the 1 year(1998.8∼1999.8) at Korea Global Atmosphere Watch Observatory (KGAWO) in Anmyeon-do are analyzed by the selecting method which is recommended by WDCGG to get background CO$_2$. This method can reject data based on two criteria: the instability of CO$_2$ concentration within 1 hour from hourly standard deviation (hourly variability$\leq$ 0.6 ppm first selection) and the large changes in the CO$_2$ concentration from one hour to the nex(∼$\leq$0.3 ppm, second selection). We could obtain hourly background CO$_2$ of 37% in first selection and 20% in second selection during the l year. That are a little less than those of Ryori station in Japan. especially, the cases of background CO$_2$ which is selected were few during the summer. That is caused by affection of vegetation and anthropogenic source. After the selecting methods are applied, the cases which is selected for easterly wind decrease remarkably according to the analysis of wind direction about continuous CO$_2$ .That was affected by anthropogenic source from the east area.

• Journal of Korean Society for Atmospheric Environment
• /
• v.17 no.1
• /
• pp.105-115
• /
• 2001

This study was conducted to analyzed the pattern of $CO_2$ concentration changes in various time scale within and across the Korean Peninsula. We compared that data sets obtained from Moo-Ahn(NAN) station in Korea with those determined from major background observatory stations around the world from the periods of Aug. 1995 to Dec. 1997. The mean $CO_2$concentrations of the MAN area, if computed using the total of 884 daily mean values, were computed to by 374.5$\pm$6.6 ppm. When the background data for MAN were compared with those of other background site, the concentration of MAN was systematically higher than any other comparable sites. Results of correlation analysis between MAN and other background sites generally showed up the existence of strong correlations, indicating that the relative effect of $CO_2$ concentration change can proceed similarly over the globe. However, notable differences in annual growth rate of $CO_2$ between MAN and all the comparative sites suggested that its concentration in th MAN area be regulated in more complicated manners than those in the other areas. It is thus suspected that the data collected form MAN area be not effective enough to represent areal distribution characteristics of $CO_2$in the Korean Peninsula.

• Journal of the Korean Society of Combustion
• /
• v.15 no.4
• /
• pp.37-42
• /
• 2010

The measurement of heat release rate is of great importance in the study of thermo-acoustic instability occurring in lean premixed combustion and the chemiluminescence emission has been used as an indicator of heat release in combustion instability studies primarily for its relative simplicity. This paper presents results of experimental study of flame chemiluminescence from an atmospheric, swirl-stabilized, turbulent lean premixed flame with a main emphasis on the effect of $CO_2^*$ background level in the $CH^*$ and $OH^*$ band. The test results show that the effect of $CO_2^*$ level in the $CH^*$ band is greater than that in the $OH^*$ band. Also, the background to peak ratio for both $CH^*$ and $OH^*$ bands can be expressed as a function of equivalence ratio, almost regardless of a change in the inlet velocity.

• Atmosphere
• /
• v.27 no.4
• /
• pp.423-433
• /
• 2017

The spatial and temporal variations in radiative forcing (RF) and mean temperature changes of greenhouse gases (GHGs), such as $CO_2$, $CH_4$, and $N_2O$, were analyzed at urban center (Yeon-dong) and background sites (Gosan) on Jeju Island during 2010~2015, based on a modeling approach (i.e., radiative transfer model). Overall, the RFs and mean temperature changes of $CO_2$ at Yeon-dong during most years (except for 2014) were estimated to be higher than those at Gosan. This might be possibly because of its higher concentrations at Yeon-dong due to relatively large energy consumption and small photosynthesis and also the difference in radiation flux due to the different input condition (e.g., local time and geographic coordinates of solar zenith angle) in the model. The annual mean RFs and temperature changes of $CO_2$ were highest in 2015 ($2.41Wm^{-2}$ and 1.76 K) at Yeon-dong and in 2013 ($2.22Wm^{-2}$ and 1.62 K) at Gosan (except for 2010 and 2011). The maximum monthly/seasonal mean RFs and temperature changes of $CO_2$ occurred in spring (Mar. and/or Apr.) or winter (Jan. and/or Feb.) at the two sites during the study period, whereas the minimum RFs and temperature changes in summer (Jun.-Aug.). In the case of $CH_4$ and $N_2O$, their impacts on the RF and mean temperature changes were very small (an order of magnitude lower) compared to $CO_2$. The spatio-temporal differences in these RF values of GHGs might primarily depend on the atmospheric profile (e.g., ozone profile), surface albedo, local time (or solar zenith angle), as well as their mass concentrations.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.28 no.1
• /
• pp.80-86
• /
• 1995

To investigate the background concentration of air pollutants (SO_2,\;CO,\;NO_2,\;O_3,\;TSP)$ and the composition of atmospheric aerosols, air samplings using teflon bags and a high volume air sampler were accomplished from 7 to 8 lune 1991 (first time) and from 25 to 26 June 1992 (second time) at the top of Dokdo island, Korea. During observation periods, mean concentrations of $SO_2,\;CO'\;NO_2\;and\;O_3$ gases were 2.3 ppb, 5.57 ppm, 6 ppb and 7 ppb, respectively, and mean concentration of TSP using a high volume air sampler was $153{\mu}g/m^3$. The composition of atmospheric aerosols by SEM-EMAX analyses were mostly Na, Cl and Si, and their sizes were more than $1{\mu}m$ diameter. From the results, it is found that atmospheric background values at Dokdo island is influenced by oceanic water quality evaporated from sea surface water, and this island has to be used as a stationary observation site for meteorological and air quality data.

• Fire Science and Engineering
• /
• v.29 no.4
• /
• pp.57-60
• /
• 2015

The removal efficiencies by elastic fire gas mask of toxic gases CO, HCl, HCN, and $SO_2$ produced by a fire have a key role in saving lives. The elastic fire gas mask comprises a visible window, elastic hood, gas purification canister, and air vent. It does not have hair or neck thongs, which makes it easy to use and put on quickly. This research examined the removal efficiency of toxic gases by such a mask. The removal efficiencies for CO with a background concentration of 2505.0 ppm were 99.99 and 99.98% after 3.5 and 8.5 min, respectively. The residual CO concentration was drastically increased after 8.5 min. The removal efficiencies for HCl, HCN, and $SO_2$ with background concentrations of 1003.0, 399.0, and 100.3 ppm, respectively, were 100% after 20 min.

• Atmosphere
• /
• v.20 no.3
• /
• pp.307-318
• /
• 2010

This study investigates the generation and movement of low-concentration $CO_2$ observed in Gosan during summer from 2002 to 2006. For analysis, additional $CO_2$ data in Anmyeondo, Ryori, Barrow, and Minamitorishima as well as NOAA/ESRL daily global $CO_2$ fields, background trajectories data, and 850 hPa wind fields are also used. Based on analyses using various observed data, we classified three types of low-concentration $CO_2$ in Gosan according to its origin: i) the origin of the Siberian continental, in which the consumption of $CO_2$ is active due to photosynthesis from broad forests, ii) the origin of Okhotsh and Artic seas, in which the low-concentration $CO_2$ is dominant due to high primary productivity by a plankton bloom, and iii) the origin of the Northwestern Pacific which is related to the entry of air mass from high latitudes. These results show that the low-concentration $CO_2$ observed in Gosan during summer is not originated from the Pacific oceans as known in previous studies, but originated from high latitude regions such as the Siberian continental and the Okhotsh and Artic seas.

• Journal of Environmental Science International
• /
• v.25 no.7
• /
• pp.973-987
• /
• 2016

The spatial and temporal variations of $CO_2$ concentrations and radiative forcing (RF) due to $CO_2$ were examined at urban center (Yeon-dong) during 2010-2015 and background sites (Gosan) during 2010-2014 on Jeju Island. The RF at the two sites was estimated based on a simplified expression for calculating RF for the study period. Overall, annual mean $CO_2$ concentrations at the Yeon-dong and Gosan sites have gradually increased, and the concentrations were higher at Yeon-dong (401-422 ppm) than at Gosan (398-404 ppm). The maximum $CO_2$ concentrations at the two sites were observed in winter or spring, followed by fall and summer, with higher concentrations at Yeon-dong. The RF at Yeon-dong (annual mean of up to $0.70W/m^2$ in 2015) was higher than that at Gosan (up to $0.46W/m^2$ in 2014), possibly because of higher $CO_2$ concentrations at Yeon-dong resulting from population growth and human activities (e.g., fossil fuel combustion). The highest monthly mean RFs at Yeon-dong (approximately $0.92W/m^2$) and Gosan ($0.52W/m^2$) were observed in spring 2015 (Yeon-dong) and spring 2013 (Gosan), whereas the lowest RFs (0.17 and $0.31W/m^2$, respectively) in fall 2011 (Yeon-dong) and summer in 2012 (Gosan).

• 한국정보디스플레이학회:학술대회논문집
• /
• 2009.10a
• /
• pp.1077-1080
• /
• 2009

In this paper, we propose a new method for measuring image sticking of an OLED display using a human visual test. We determined that the perceptual image sticking threshold is 2% of luminance difference at 200 nits and 1% at 100 nits, respectively. Color shift must also be considered when evaluating image sticking, as a ${\Delta}$(u', v') shift of just over 0.002 can be recognized regardless of background brightness. Perception of image sticking is affected by the background level, test pattern, and ambient illumination conditions. The evaluation standard must consider both luminance variation and color shift simultaneously.

• Proceedings of the Korea Air Pollution Research Association Conference
• /
• 2007.10a
• /
• pp.265-267
• /
• 2007