• Journal of the Korean earth science society
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• v.25 no.6
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• pp.474-483
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• 2004

This paper analyzed the characteristics of daily ozone variations over Kangreung and Wonju. It was found that the diurnal cycle of ozone over Wonju has a primary ozone peak in the afternoon and a minimum around sunrise, which is a typical diurnal ozone cycle observable in the urban area. However, the cycle over Kangreung shows a primary peak in the afternoon and secondary peak around 3 a.m. The amounts of ozone in the secondary peak is occasionally higher than that in the primary peak. This nocturnal ozone peak is frequently observed year-round, and the highest frequency and extent are observed in spring. The possible cause of this nocturnal ozone increase was investigated using meteorological parameters and the HYSPLIT trajectory model. It was found that the nocturnal ozone peak is highly correlated with strong wind speed, which has led to positive temperature anomaly. The trajectory model revealed that when the secondary peak occurred, the air was originated from the west and a sinking motion subsequently followed. These findings suggested that when the westerly wind is strongest in spring, the polluted airs from urban areas are transported to the upper boundary layer over Kangreung area. In the case of strong wind during the night, nocturnal ozone peaks were produced by active vertical mixing between lower boundary and upper boundary layers.

• Journal of Korean Society for Atmospheric Environment
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• v.21 no.2
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• pp.243-257
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• 2005

The effects of Traffic Control Program (TCP) on the ambient urban air quality of SO$_{2}$, NO$_{2}$, O$_{3}$, and PM$_{10}$ were evaluated in Seoul metropolitan area by using the lower atmospheric vertical stability index and daily mean wind speeds. The vertical stability index; temperature lapse rate between 1000 hPa and 850 hPa geopotential height fields, were used to identify daily vertical stability index during the 2002 World Cup period where traffic amount was reportedly reduced to half the number of vehicles. The indicated air quality levels of TCP days were then compared with those of the cases observed with analogous vertical stability during the recent 3 years from 2000 to 2002. The result indicates that the effect of TCP on the primary air pollutants are found to be approximately 39$\%$, 23$\%$ and 20$\%$ lower for SO$_{2}$, NO$_{2}$ and PM$_{10}$, respectively. The secondary air pollutant; ozone, showed relatively smaller decreasing rate (13$\%$) of daily mean concentrations (even increased during the night time). The comparison of daily maximum or peak concentrations reveals that the pronounced decreasing effects of TCP on the ambient air quality for both primary and secondary air pollutants, suggesting that TCP is one of the effective strategies to control peak or higher concentrations for most urban scale air pollutants in and around the Seoul metropolitan area.

• Journal of Environmental Analysis, Health and Toxicology
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• v.21 no.4
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• pp.220-228
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• 2018

$PM_{2.5}$-bound mercury (PBM) was monitored at weekly intervals for three years (from 2014 to 2016) at an urban (Seoul) and rural site (Baengnyeong) in South Korea. The average PBM concentrations in $PM_{2.5}$ samples over the entire sampling period were $12{\pm}11pg/m^3$ and $36{\pm}34pg/m^3$ for Baengnyeong and Seoul, respectively. Seasonal differences were pronounced, with concentrations being highest in winter due to local meteorological conditions (high gas-particle coefficient due to low temperature and low mixing layer height in winter) as well as seasonal factors, such as coal combustion for heating purposes in China. In Baengnyeong, the significant positive correlation of PBM with $PM_{2.5}$, air pollutants, and heavy metals suggested that coal combustion in China might be the most important source of ambient mercury in Korea. In winter, no correlation of PBM with $PM_{2.5}$, air pollutants, and heavy metals was seen in Seoul. Furthermore, Seoul showed higher $PBM/PM_{2.5}$ and $Pb/PM_{2.5}$ ratios in winter due to the strong atmospheric oxidation-reduction reaction conditions as well as local and regional PBM sources. We conclude that immediate attention must be given to addressing PBM levels in Korea, including considering it as a key component of future air quality monitoring activities and mitigation measures.

• Journal of Korean Society for Atmospheric Environment
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• v.27 no.1
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• pp.63-72
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• 2011

This study describes the impact of positive sampling artifact caused by a filter-based sampling in the determination of ambient organic carbon (OC). Three different sampling media combinations were employed for this investigation: (1) Quartz filter-alone (Q-alone), (2) quartz filter behind quartz-fiber filter (QBQ), and (3) quartz filter and quartz filter behind Teflon filter (Q-QBT). The measurement of ambient OC was carried out at a semi-urban site near oceanside at the end of November of 2008. It was found that Q-alone sampling configuration resulted in a higher OC than QBQ and Q-QBT by 14% and 28%, respectively due to no correction for positive artifact caused by adsorption of gas-phase OC onto the filter. A lower quantity of OC was collected from the backup quartz filter on QBQ than that from Q-QBT. A possible explanation is that the front quartz filter of QBQ was not fully saturated with gas-phase OC during the sampling period, allowing smaller amount of gas-phase OC to reach the backup quartz filter. The contribution of positive artifact to $PM_{2.5}$ mass was approximately 2.15 ${\mu}g/m^3$ which is equivalent to 6% in terms of Q-QBT sampling configuration. The positive artifact was found to be more dominated during summer than during winter, showing temperature dependence. It was concluded that Q-QBT sampling configuration offers less impact of positive artifact on ambient OC sampling than QBQ in quantification of OC.

• Corrosion Science and Technology
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• v.10 no.2
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• pp.52-59
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• 2011

Corrosion of metallic materials occurs by the reaction with corrosive environment such as atmosphere, marine, soil, urban, high temperature etc. In general, reduction of thickness and cracking and degradation are resulted from corrosion. Corrosion in all industrial facilities and infrastructure causes large economic losses as well as a large number of accidents. Economic loss by corrosion has been reported to be nearly 1-6% of GNP or GDP. In order to reduce corrosion damage of industrial facilities, corrosion map as well as a systematic investigation of the loss of corrosion in each industrial sector is needed. The Corrosion Science Society of Korea in collaboration with 15 universities and institutes has started to survey on the cost of corrosion and corrosion map of Korea since 2005. This work presents the results of the survey on cost of corrosion by Uhlig, Hoar, and input-output methods, and the evaluation of atmospheric corrosion rate of carbon steel, weathering steel, galvanized steel, copper, and aluminum in Korea. The total corrosion cost was estimated in terms of the percentage of the GDP of industry sectors and the total GDP of Korea. According to the result of Input/output method, corrosion cost of Korea was calculated as 2.9% to GDP (2005). Time of wetness was shown to be categories 3 to 4 in all exposure areas. A definite seasonal difference was observed in Korea. In summer and fall, time of wetness was higher than in other seasons. Because of short exposure period (12 months), significant corrosion trends depending upon materials and exposure corrosion environments were not revealed even though increased mass loss and decreased corrosion rate by exposure time.

• Korean Journal of Environmental Biology
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• v.40 no.2
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• pp.172-186
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• 2022

Benthic macroinvertebrates are important ecological and environmental indicators as primary or secondary consumers, and therefore are widely used in the evaluation of aquatic environments. However, there are no comprehensive river ecosystem monitoring surveys that link the major physicochemical water quality items with benthic macroinvertebrates in urban streams. Therefore, this study investigated the distribution characteristics of benthic macroinvertebrates and physicochemical water quality items (17 items) in Yangjaecheon and Yeouicheon from 2019 to 2020. At the same time, by applying Spearman's rank correlation analysis and nonmetric multidimensional scaling (nMDS) analysis in the water quality data and biotic index, we tried to provide basic data for diagnosing the current status of river ecosystems in major urban rivers in Seoul. Based on the study results, a total of 39 species and 3,787 individuals were identified in Yangjaecheon, the water quality(based on BOD, TOC, and TP) of Yangjaecheon was higher than Grade Ib(good), and the BMI using benthic macroinvertebrates appeared as Grade C(normal) at all the sites. In Yeouicheon, a total of 51 species and 4,199 individuals were identified, the water quality(based on BOD, TOC, TP) was higher than Grade Ib(good) similar to Yangjaecheon, and the BMI of both Upstream and Saewon bridge was Grade B(good), while Yeoui bridge was Grade C(normal). Overall, analysis results for the distribution of benthic macroinvertebrates by a nonmetric multidimensional scaling method showed no significant difference between the two streams (p=0.1491). Also, significant environmental variables related to benthic macroinvertebrates distribution were determined as water temperature and DO. On the other hand, the results of the correlation analysis between biotic index and major water quality items confirmed that R1 and BMI could be used for on-site urban river water quality evaluation.

• Journal of the Korean earth science society
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• v.26 no.1
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• pp.93-105
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• 2005

Climatological characteristics in the variation of soil temperatures in Korea were investigated using Korea Meterological Administration's observation data. And the impacts of soil moisture on the variation of soil temperature were examined using observed precipitation data. The climatological averages of soil temperatures are ranged from 14.4 to $15.0^{\circ}C$ regardless of depths. And they showed an latitudinal gradient with a warm temperature at the southern region and 'U' shape as in the air temperature with a high value along the coastal region. The relatively higher heat capacity and low conductivity of soil compared to those of the air resulted in the significant delay of the maximum and minimum date with depth. As a results, soil acts as a heat source during winter while a heat sink during summer. Global warming and urban heat island have increased the soil temperatures with an average rate $0.3\~0.5^{\circ}C/10-year$ as in the air temperature during last 30 years $(1973\~2002)$. However, the warming rate is maximized during spring contrary to the winter in the air temperature. The temporal variation of soil temperatures is strongly affected by that of soil moisture through an modification of the heat capacity and heat convection. In general, the increased soil moisture clearly decreased the temporal variations and increased the deep layer soil temperatures during cold season.

• Journal of the Korean earth science society
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• v.28 no.1
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• pp.45-53
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• 2007

This study investigated the effect of parked cars in the sunshine on the increase of air temperature on a sunny day. Air temperatures were determined both from inside of the parked cars and the top surface of the vehicle at which one car was parked under the sunshine and the other in the shade for the duration of 27 hours. The surface temperatures of asphalt and bare soil were simultaneously measured in both locations, sunshine and shade areas, along with a couple of meteorological factors. The sensible heat fluxes from the surfaces of asphalt, bare soil and two vehicles were estimated by utilizing those observed data. The results are as follows; 1) The surface temperatures of bare soil, asphalt and two vehicles increased with $30{\sim}37^{\circ}C,\;37{\sim}46^{\circ}C\;and\;42{\sim}49^{\circ}C$ respectively during the day. 2) The sensible heat fluxes were noticeably higher from the top surface of the parked vehicle in the sunshine than from the asphalt or bare soil. The differences of sensible heat fluxes between the vehicle's roof and the other two surfaces of asphalt and bare soil were 60 (asphalt) and 85 (bare soil) $W/m^2$ during the daytime.

• Journal of Environmental Health Sciences
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• v.39 no.3
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• pp.211-222
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• 2013

Objectives: A great number of people visit forests for their bountiful healing factors. We investigated the quantity of terpene and analyzed the correlations with meteorological and environmental factors at Mt. Mudeung in order to support public health. Methods: The terpene amounts were investigated along 11 main trails using stainless steel tube packed by Tenax TA (150 mg) and Carbopack B (130 mg) during March to November 2012. Terpene amounts of 20 species (${\alpha}$-pinene, camphene, etc.), and meteorological and environmental factors were investigated in the field. Results: Terpene of 16 species was released from the forest and total terpene amounts were 2,080 pptv at the site of Chamaecyparis obtusa, the highest among 11 sites, nearby the first reservoir on Mt. Mudeung. Terpene concentrations in the forest were nine to 23 times higher than found in urban areas. Total terpene amounts had positive correlations with temperature, humidity, carbon dioxide and oxygen (p<0.01) with $R^2$ of 0.345, 0.369, 0.591, 0.145, respectively, from April to July. Wind speed and solar radiation in the forest had a negative correlation with terpene amounts and showed statistical insignificance with p-values of 0.118 and 0.233, respectively. Conclusions: This study suggests that the amounts of terpene around Mt. Mudeung are indeed higher, so visitors may enjoy a therapeutic walk in the forest with a healing effect. These results showed the forest was very effective for improving human health.

• Journal of Korean Society for Atmospheric Environment
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• v.25 no.4
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• pp.347-359
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• 2009

The concentrations of PAHs in $PM_{10}$ fine particles were determined at two sites, which were Jongno, one of the urban core sites of Seoul, and Yongin, a downwind site of Seoul. The average concentration of PAHs in $PM_{10}$ was $19.92{\pm}18.49\;ng\;m^{-3}$ with the range of $1.28{\sim}81.22\;ng\;m^{-3}$ at Jongno site of Seoul from August 2006 to August 2007, and $14.06{\pm}9.96\;ng\;m^{-3}$ with the range of $1.66{\sim}31.84\;ng\;m^{-3}$ at Yongin site from September to November of 2006. In the results of monthly comparison, the concentration of PAHs in August was the lowest level of $3.23\;ng\;m^{-3}$, but the highest level of $46.24\;ng\;m^{-3}$ in January. The seasonal comparison showed the concentration in winter was higher by the factor of 11.9 than in summer. The concentrations of PAHs during a warm period (November${\sim}$March) increased as 5.1 times higher than those during a cold period (April${\sim}$October). The concentrations of PAHs were assumed to be largely attributed to the consumption of fossil fuels, temperature, mixing height, and photochemical reactions in Seoul metropolitan area.