• The Journal of Engineering Geology
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• v.29 no.1
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• pp.23-35
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• 2019

Landslides occur due to heavy rainfall in the summer season. Some of water may infiltrate into the ground; it causes a high saturation condition capable of causing a landslide. Soil properties are crucial in estimating slope stability and debris flow occurrence. The main study areas are Gwanaksan, Suraksan and Bukhansan (Mountain) in Seoul. A total of 44 soil samples were taken from the study area; and a series of geotechnical tests were performed. Physical and mechanical properties were obtained and compared based on region. As a result, among well-graded soils, they are classified as a clayey sand. Coarse-grained and fine-grained contents are approximately 95% and 5%, respectively, with very low amount of clay content. Density, liquid limit and dry unit weight are ranged in $2.62{\sim}2.67g/cm^3$, 27.93~38.15% and $1.092{\sim}1.814g/cm^3$. Cohesion and internal friction angle are 4 kPa and $35^{\circ}$ regardless of mountain area. Coefficient of permeability is varied between $3.07{\times}10^{-3}{\sim}4.61{\times}10^{-2}cm/sec$; it means that it results in great seepage. Permeability is inversely proportional to the uniformity coefficient and is proportional to the effective particle size. In the formal case, there was a difference by mountain area, while in the latter, the tendency was almost similar.

• Korean Journal of Occupational Therapy
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• v.26 no.4
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• pp.1-11
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• 2018

Objective : This study was conducted to determine the emotional labor of occupational therapists and the level of their feelings of depression and to examine the impact of their emotional labor on their depressive mood. Methods : Subjects of this study were clinical occupational therapists working at hospitals and clinics in Seoul and Gyeonggi regions. The factors of emotional labor were set as independent variables, the general characteristic variable and job characteristic variable which showed significant results in the chi-square test was set as the adjusted variable and whether the depression happens or not was set as the dependent variable, after which a multivariate logistic regression analysis was conducted. Results : Components of emotional labor, including frequency of emotional display(OR 1.699, 95% CI 1.202-2.401), attentiveness to required display rules(OR 1.436, 95% CI 1.070-1.982), and emotional dissonance(OR 1.866, 95% CI 1.336-2.607) all had a significant effect on depression. The possibility of depression was significantly higher in women than men(OR 5.736, 95% CI 1.746-18.846), those working for more than 8 hours per day than less than 8 hours per day(OR 8.609, 95% CI 2.306-32.137), and those working with children than those working with adults(OR 4.249, 95% CI 1.668-10.824). Conclusion : This study revealed that the emotional labor that occupational therapists are exposed to while interacting with patients and their caregivers exerts an influence on their feelings of depression. This suggests the need for developing various preventive intervention programs designed to alleviate the depressive symptoms of occupational therapists and formulating appropriate policies.

• Korean Journal of Remote Sensing
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• v.36 no.6_3
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• pp.1711-1720
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• 2020

Particulate matter (PM) that has been artificially generated during the recent of rapid industrialization and urbanization moves and disperses according to weather conditions, and adversely affects the human skin and respiratory systems. The purpose of this study is to predict the PM10 concentration in Seoul using meteorological factors as input dataset for multiple linear regression (MLR), support vector machine (SVM), and random forest (RF) models, and compared and evaluated the performance of the models. First, the PM10 concentration data obtained at 39 air quality monitoring sites (AQMS) in Seoul were divided into training and validation dataset (8:2 ratio). The nine meteorological factors (mean, maximum, and minimum temperature, precipitation, average and maximum wind speed, wind direction, yellow dust, and relative humidity), obtained by the automatic weather system (AWS), were composed to input dataset of models. The coefficients of determination (R2) between the observed PM10 concentration and that predicted by the MLR, SVM, and RF models was 0.260, 0.772, and 0.793, respectively, and the RF model best predicted the PM10 concentration. Among the AQMS used for model validation, Gwanak-gu and Gangnam-daero AQMS are relatively close to AWS, and the SVM and RF models were highly accurate according to the model validations. The Jongno-gu AQMS is relatively far from the AWS, but since PM10 concentration for the two adjacent AQMS were used for model training, both models presented high accuracy. By contrast, Yongsan-gu AQMS was relatively far from AQMS and AWS, both models performed poorly.

• Journal of Industrial Convergence
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• v.21 no.7
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• pp.29-39
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• 2023

In the recent period, there have been numerous earthquakes both domestically and internationally, and buildings in South Korea are particularly vulnerable to seismic design and earthquake damage. Therefore, the objective of this study is to discover an effective method for assessing the seismic vulnerability of buildings and conducting a density analysis of high-risk structures. The aim is to model this approach and validate it using data from pilot area(Seoul). To achieve this, two modeling techniques were employed, of which the predictive accuracy of the statistical analysis technique was 87%. Among the machine learning techniques, Random Forest Model exhibited the highest predictive accuracy, and the accuracy of the model on the Test Set was determined to be 97.1%. As a result of the analysis, the district rating revealed that Gwangjin-gu and Songpa-gu were relatively at higher risk, and the density analysis of at-risk buildings predicted that Seocho-gu, Gwanak-gu, and Gangseo-gu were relatively at higher risk. Finally, the result of the statistical analysis technique was predicted as more dangerous than those of the machine learning technique. However, considering that about 18.9% of the buildings in Seoul are designed to withstand the Seismic intensity of 6.5 (MMI), which is the standard for seismic-resistant design in South Korea, the result of the machine learning technique was predicted to be more accurate. The current research is limited in that it only considers buildings without taking into account factors such as population density, police stations, and fire stations. Considering these limitations in future studies would lead to more comprehensive and valuable research.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.6
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• pp.721-733
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• 2023

As the frequency of extreme rainfall events increase due to climate change, climate change adaptation measures have been proposed by the central and local governments. In order to reduce flood damage in urban areas, various flood response policies, such as low impact development techniques and enhancement of the capacity of rainwater drainage networks, have been proposed. When these policies are established, regional characteristics and policy-effectiveness from the cost-benefit perspective must be considered for the flood mitigation measures. In this study, capacity enhancement of rainwater pipe networks and low impact development techniques including green roof and permeable pavement techniques are selected. And the flood reduction effect of the target watershed, Gwanak campus of Seoul National University, was analyzed using SWMM model which is an urban runoff simulation model. In addition, along with the quantified urban flooding reduction outputs, construction and operation costs for various policy scenarios were calculated so that cost-benefit analyses were conducted to analyze the effectiveness of the applied policy scenarios. As a result of cost-benefit analysis, a policy that adopts both permeable pavement and rainwater pipe expansion was selected as the best cost-effective scenario for flood mitigation. The research methodology, proposed in this study, is expected to be utilized for decision-making in the planning stage for flood mitigation measures for each region.

• Journal of Environmental Health Sciences
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• v.50 no.2
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• pp.83-92
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• 2024

Background: In this study, we investigate the rapid increase in environmental odors and notable rise in civil complaints near Dorim Stream in the Gwanak-gu area of Seoul. Objectives: This study aims to identify the causal compounds responsible for environmental odors in the Dorim Stream and investigate the structural characteristics of the stream that influence odor generation. Methods: The research methodology involved setting up 41 sampling points, selecting panels for direct sensory evaluation to assess odor intensity, measuring dissolved oxygen and hydrogen sulfide concentrations, and using all-in-one low-temperature desorption gas chromatography (ATD-GC) and thermal desorption-gas chromatography-mass spectrometry (TD-GC/MS) analysis to identify odor-causing compounds. Results: The evaluation of Dorim Stream revealed that in areas with complete meandering, there were lower dissolved oxygen levels (4.5±2.67 mg/L) and higher odor intensity (4.0±0.92), while in partially meandering sections, higher dissolved oxygen levels (7.8±1.15 mg/L) and lower odor intensity (2.8±1.06) were observed. Hydrogen sulfide levels measured with sensors increased with higher temperatures, especially in the afternoon hours (12:00~14:00). Acetaldehyde was the dominant odor compound detected in both the Bonglim Bridge (0.4 ppm) area and Guro Bridge area (0.867 ppm), with concentrations more than twice as high near Guro Bridge. Odor-causing compounds identified by TD-GC/MS indicated a pungent, sulfurous odor in the Guro Bridge area and a musty odor in the Bonglim Bridge area. Conclusions: This study categorizes and analyzes the sources of odor in Dorim Stream in Seoul based on meandering patterns and the distribution of sewage facilities, highlighting the potential odor issues associated with combined sewage systems and sewer junctions and suggesting policy improvements.

• Journal of Korean Society of Forest Science
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• v.87 no.1
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• pp.62-73
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• 1998

This research was conducted to analyze the influence of the environmental factors on water quality such as contents of cation($K^+$, $Na^+$, $Ca^{2+}$, $Mg^{2+}$) and anion($Cl^-$, $NO{_3}^-$, $SO{_4}^{2-}$) in rainfall, throughfall, soil water(A and B layer), and stream water at a small forested watershed. Rainfall, throughfall, soil water(A and B layer), and stream water were sampled at the study sites in Kwanak Arboretum, Seoul National University, in Mt. Kwanak for 14 months(Jul. 1, 1996~Aug. 31, 1997). $Cl^-$ content of stream water correlated with that of soil water tire than that of rainfall and throughfall. Also $NO{_3}^-$ content in soil water was correlated with that of rainfall. Cation($K^+$, $Na^+$, $Ca^{2+}$, $Mg^{2+}$) contents in soil water at layer A and B were significantly correlated with anion($Cl^-$, $NO{_3}^-$, $SO{_4}^{2-}$) of that. The ratio of the average content of $NO{_3}^-$ to $SO{_4}^{2-}$ in rainfall was 0.66. Accordingly the content of $SO{_4}^{2-}$ was higher than $NO{_3}^-$ in rainfall. The amount of anion in stream water was significantly correlated with that in rainfall, throughfall, and soil water. Average content of cation and anion in hydrological processes were decreasing in the following order, soil water(B layer> A layer) > throughfall(Pinus rigida > Prunus serrulata var. spontanea > Carpinus laxiflora) > stream water > rainfall.

• Korean Journal of Remote Sensing
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• v.32 no.2
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• pp.119-131
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• 2016

Descriptions are provided of the automated aerosol-type classification and mass concentration calculation algorithm for real-time data processing and aerosol products in Korea Aerosol Lidar Observation Network (KALION, http://www.kalion.kr). The KALION algorithm provides aerosol-cloud classification and three aerosol types (clean continental, dust, and polluted continental/urban pollution aerosols). It also generates vertically resolved distributions of aerosol extinction coefficient and mass concentration. An extinction-to-backscatter ratio (lidar ratio) of 63.31 sr and aerosol mass extinction efficiency of $3.36m^2g^{-1}$ ($1.39m^2g^{-1}$ for dust), determined from co-located sky radiometer and $PM_{10}$ mass concentration measurements in Seoul from June 2006 to December 2015, are deployed in the algorithm. To assess the robustness of the algorithm, we investigate the pollution and dust events in Seoul on 28-30 March, 2015. The aerosol-type identification, especially for dust particles, is agreed with the official Asian dust report by Korean Meteorological Administration. The lidar-derived mass concentrations also well match with $PM_{10}$ mass concentrations. Mean bias difference between $PM_{10}$ and lidar-derived mass concentrations estimated from June 2006 to December 2015 in Seoul is about $3{\mu}g\;m^{-3}$. Lidar ratio and aerosol mass extinction efficiency for each aerosol types will be developed and implemented into the KALION algorithm. More products, such as ice and water-droplet cloud discrimination, cloud base height, and boundary layer height will be produced by the KALION algorithm.

• Journal of Soil and Groundwater Environment
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• v.8 no.4
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• pp.68-73
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• 2003

This study performed from 2002 October to 2003 April. The samples were taken at 66 sites, divided into the 6 sections functionally in the southern part of Seoul such as Yangchon-gu, Kangseo-gu, Kuro-gu, Yeongdengpo-gu, Kwanak-gu, Dongjak-gu, Seocho-gu, Kangnam-gu, Songpa-gu, and Kangdong-gu. The result of research showed that each property soil was pH 4.7∼9.5, Cd; 0.391 mg/kg (0.011∼l.081 mg/kg). Cu; 12.35 mg/kg (0.061∼73.62 mg/kg), Pb; 13.04 mg/kg (N.D.∼61.85 mg/kg), Hg; 0.0866 mg/kg (N.D.∼1.353 mg/kg), F; 206.8 mg/kg(47.1∼561.1mg/kg). The minimum and maximum of the concentration with functional soils were Cd; 0.632 mg/kg for multi-purposed soil,0.079 mg/kg for schools, Cu; 21.35 mg/kg for roadside, 2.159 mg/kg for schools, Pb; 24.70 mg/kg for roadside, 1.030 mg/kg for schools, Hg; 0.1780 mg/kg for multi purposed, 0.0087 mg/kg for schools. Especially F was the high concentration at the hills. Also the concentration of Cd, Cu, Pb, Hg and F at school Zone was detected such as low. area of schools area was detected the low concentrations as the items of Cd, Cu, Pb, Hg, and F. The average concentrations of metals and fluorine in the survey area were below the Preliminary Standard of the Soil Preservation Acts in Korea. To evaluate the soil quality of these area showed as a good qualified results. The results of SQPI (Soil Quality Pollution Index the qualified results as much as 86.4%.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.10 no.4
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• pp.227-235
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• 1977

The noise pressure scattered underwater on account of the engine revolution of a pole and liner, Kwan-Ak-San(G. T. 234.96), was measured at the locations of Lat. $34^{\circ}47'N$, Long. $128^{\circ}53'E$ on the 16th of August 1976 and Lat. $34^{\circ}27'N$, Long. $128^{\circ}23'E$ on the 28th of July, 1977. The noise pressure passed through each observation point (Nos. 1 to 5), which was established at every 10m distance at circumference of outside hull was recorded when the vessel was cruising and drifted. In case of drifting, the revolution of engine was fixed at 600 r. p. m. and the noise was recorded at every 10 m distance apart from observation point No. 3 in both horizontal and vertical directions with $90^{\circ}$ toward the stern-bow line. In case of cruising, the engine was kept in a full speed at 700 r.p.m. and the sounds passed through underwater in 1 m depth were also recorded while the vessel moved back and forth. The noise pressure was analyzed with sound level meter (Bruel & Kjar 2205, measuring range 37-140 dB) at the anechoic chamber in the Institute of Marine Science, National Fisheries University of Busan. The frequency and sound waves of the noise were analyzed in the Laboratory of Navigation Instrument. From the results, the noise pressure was closely related to the engine revolution shelving that the noise pressure marked 100 dB when .400 r. p. m. and increase of 100 r. p. m. resulted in 1 dB increase in noise pressure and the maximum appeared at 600 r. p. m. (Fig.5). When the engine revolution was fixed at 700 r. p. m., the noise pressures passed through each observation point (Nos. 1 to 5) placed at circumference of out side hull were 75,78,76,74 and 68 dB, the highest at No.2, in case of keeping under way while 75,76,77,70 and 67 dB, the highest at No.3 in case of drifting respectively (Fig.5). When the vessel plyed 1,400 m distance at 700 r.p.m., the noise pressure were 67 dB at the point 0 m, 64 dB at 600m and 56 dB at 1,400m on forward while 72 at 0 m, 66 at 600 m and 57 dB at 1,400 m on backward respectively indicating the Doppler effects 5 dB at 0 m and 3 dB at 200 m(Fig.6). The noise pressures passed through the points apart 1,10,20,30,40 and 50 m depth underwater from the observation point No.7 (horizontal distance 20 m from the point No.3) were 68,75,62,59,55 and 51 dB respectively as the vessel was being drifted maintaining the engine revolution at 600 r. p. m. (Fig. 8-B) whereas the noise pressures at the observation points Nos.6,7,8,9 and 10 of 10 m depth underwater were 64,75,55,58,58 and 52 dB respectively(Fig.8-A).