• Proceedings of the KSR Conference
• /
• 2009.05a
• /
• pp.1489-1497
• /
• 2009

The rectifier for Electric railway is one of the most important facilities in DC urban railway which converts power from KEPCO(AC 22.9kV) to the electric mil car(DC 1.5kV), therefore it should be managed as the best condition for the drive. There are several things to cause performance degradation and deterioration of parts such as pollutants occurred by it established under the ground such as dust or foreign substances, rapid changes of driving current, and pyrogen which put the rectifier for Electric railway in malfunction. On the flow of time, the rectifier for Electric railway is causing a malfunction or failure which drive electric rail car in operations as well as loss of life. In this research we try to find the way of removing the various components of mal-functions in the performance of the rectifier for Electric railway by Over-Haul and reform itself, which gives us to get the chance investment of the reduction, the reliability of power supply to the electric rail car.

• Journal of Korean Society for Atmospheric Environment
• /
• v.24 no.1
• /
• pp.108-121
• /
• 2008

On January 1, 2005, the Korean Ministry of Environment put into operation a comprehensive program, so called 'Blue Sky 21' project, for the improvement of air quality in greater Seoul metropolitan area. This program was legally based on the 'Special Act on Metropolitan Air Quality Improvement' for Greater Seoul area, which was established in 2003, and should be updated every 10 years. The principal objective of this program is to improve the air quality in Seoul and surrounding area by 2014 to the levels of air quality in Tokyo and Paris, with particular emphases on reducing the concentrations of nitrogen dioxide and $PM_{10}$. Any regulation of the emission of toxic air pollutants in general, and $NO_2$ and $PM_{10}$ in particular, should be based on human exposure levels and consequential health effects. In this article, the contents and feasibility of the special program were critically evaluated with respect to the reduction of health risks. Important issues for improving not only air quality but public health are discussed, and future requirements for the success of the special program are suggested.

• International conference on construction engineering and project management
• /
• 2009.05a
• /
• pp.808-813
• /
• 2009

Top-down method is widely used for urban area construction for its advantages in reducing environmental problems such as dust and noise, and saving construction cost depending on given conditions of a construction site. Because the excavation and construction of super- and sub-structures of the building have to be proceeded simultaneously, a column has to be embedded prior to excavation. This column is called a pillar column or pre-founded column. Usually a wide flange section is used for these columns. To place the columns, usually the diameter of casing holes needs to be larger than the section of the wide flange itself in order to accommodate a couple of tremie pipes for pouring concrete. In this paper, a newly developed method of using circular pipe as an alternative to the existing wide flange section is discussed. The crucial part of the new method is to develop a connection between the circular column and concrete flat slabs. For shear force transfer from concrete slab to the concrete filled tube (CFT) column, shear jackets with studs and shear bands are proposed. The studs are welded on the jackets at shop and placed around the circular column on site. The shear bands are welded on the outer side of the CFT at shop and inserted into ground with the CFT. Test results and application of the method to a construction site are also provided in this paper.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2021.11a
• /
• pp.194-195
• /
• 2021

Due to urban regeneration projects or changes in the living environment, there is an increasing need to demolish old buildings that have lost their functions. Demolition of above ground and underground structures is an important construction project that greatly affects the construction period and safety of the entire process. However, it is difficult for the safety officer to manage the demolition work due to the lack of specific and diverse data applicable to the site of the demolition plan. Therefore, in this study, items that need to be improved in structural safety when the above-ground and underground structures are demolished are reviewed and organized. For the main contents of structural safety management in demolition work, 1) structural review reflecting the order of demolition work, 2) installation and dismantling of steel pipe scaffolding and dust nets, 3) installation and dismantling of system scaffolding, 4) installation and dismantling of fall prevention nets, 5) jack support Installation and dismantling, 6) movement of equipment, movement and planning between floors, 7) equipment for demolition of structures, height of remnants, 8) site cleanup, and 9) equipment operators were categorized and arranged.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.49 no.5
• /
• pp.1-11
• /
• 2021

The purpose of this study is to find out the main factors affecting air quality in urban physical space factors, and provide clues for environmental improvement. Nine monitoring stations in China's industrial city, Changchun, collected AQI concentration data from January 1, 2018 to December 31, 2019. This paper analyzes the types and distribution characteristics of urban physical facilities within a radius of 300m with the detection station as the center. The monitoring station is divided into three groups, and the difference in floating dust concentration among the three groups in different seasons is analyzed. The results show that AQI concentration is the highest in spring and winter, followed by summer, and the lowest in autumn. The place with the highest concentrations of AQI in spring are F (93.00), D (91.10), I (89.20), in summer are D (69.05), A (67.89), B (84.44), in autumn are I (62.80), G (60.84), D (53.27), D (53.27), in winter are I (95.82), H (95.60), f (94.04). Through SPSS analysis, it shows that the air index in a space with a diameter of 600 meters is related to forest land, grassland, bare land, water space, tree height, building area (average value), and building volume (average value). According to the statistical analysis results of spring and winter with the most serious pollution, forest land area (43,637m², 15.44%) and water surface area (18,736m², 6.63%) accounted for the majority, and group 1 (A, B, C) with the least average building area (448m², 0.17%) and average building volume (10,201m²) had the lowest pollution concentration. On the contrary, group 2 (D, E, F) had the highest AQI concentration, with less or no woodland (1,917m², 0.68%) and water surface area (0m², 0%), and the highest average building area (1,056m², 0.37%) and average building volume (17,470m³). It is confirmed that the characteristics of the area with the highest AQI concentration are that the more the site ratio of tree height above 12m, the smaller the site ratio of bare land, and the lower the pollution degree. On the contrary, the larger the area of bare land, the higher the pollution degree. By analyzing the characteristics of nine monitoring stations in Changchun, it can be seen that the air quality brought by the physical characteristics of urban space is closely related to the above factors.

• Journal of Environmental Health Sciences
• /
• v.8 no.1
• /
• pp.67-80
• /
• 1982

In order to evaluate the psychosomatic health status of metal manufacturing industries workers and their working environments, the present study was conducted from March 1, 1981 to the end of September 1981. The data was obtained from the samples of metal manufacturing industries in Kyung-In Area and their 1, 162 employees. In addition, the 803 urban residents including students, office clerks, and general publics were sampled as control groups to compare with factory employees in psychosomatic analysis. The basic tool employed in the present study was the Todai Health Index (THI) which modified CMI and was developed by Tokyo University Research Team of Japan. The results of the present study were summarized as follows: 1. Working environments of the factories 1) The data shows that fabrication shop produced the highest noise level ranging from 91 to 96 dB (A) and iron and steel shop had the lowest noise level ranging from 81 to 86 dB (A). 2) Dust concentration was the highest in iron foundry shop ($3.8 mg/m^3$) and the lowest in fabrication shop ($1.2 mg/m^3$). 3) WBGT above threshold limit values (T.L.V.) was noted in steel shop (38$\circ$C) and iron foundry shop (34$\circ$C) 4) The concentration of Sulfur dioxide ($SO_2$)was 30.5ppm at steel shop and 12.0ppm at iron foundry shop. 5) The concentration of carbon monoxide (CO) was 140.0ppm at steel shop and 110.5ppm at iron foundry shop. 6) The atmospheric lead concentration was $0.49 mg/m^3$ at soldering shop. 2. The responses of psychosomatic complaints were much higher in steel shops group than in other manu-facturing group, except the response of aggressiveness. 3. The responses of psychosomatic complaints were much higher in industrial workers than in urban residents, except the responses of depression and aggressiveness (p < 0.01 ). 4. The psychosomatic symptoms which industrial workers and urban residents complained frequently were nervousness. agressiveness and lie scale in order. 5. The responses of psychosomatic complaints by sex were much higher in female group than in male group, except the response of aggressiveness. 6. The responses of psychosomatic complaints by age were that both the female and male group showed an increasing tendency in the all items, except the response of depression as age was increasing. 7. The responses of psychosomatic complaints by the length of services were that both the female and male group showed a tendency of increasing in physical symptoms as work years increased. 8. The responses of psychosomatic complaints were higher in unmarried group in the score of nervousness, aggressiveness, mental irritability and irregular life.

• Ecology and Resilient Infrastructure
• /
• v.9 no.1
• /
• pp.36-58
• /
• 2022

In this study, the weather conditions corresponding to the increase in the environmental concentration of fine dust (PM₁₀) and ultrafine dust (PM_2.5) from 2001 to 2019 in Jeju and Seogwipo cities were analyzed. The increase in the levels of PM₁₀ and PM_2.5 was observed in the order: spring > winter > autumn > summer. In both cities, PM₁₀ and PM_2.5 levels increased more frequently during the day in spring and summer and at night in autumn and winter, with PM_2.5 showing a greater increase in concentration than PM₁₀. The air temperature and wind speed corresponding with increased levels of PM₁₀ were higher than their respective seasonal averages in spring and winter, but lower in summer and autumn. Relative humidity was lower than the seasonal average during all seasons. The air temperature variation corresponding with increased levels of PM_2.5 showed the same seasonal trend as that observed for PM₁₀. The relative humidity was higher than the respective seasonal averages in spring and summer, and lower in winter. The wind speed was lower than the seasonal average in both the cities. When the PM₁₀ and PM_2.5 levels increased, the wind direction was from the north and the west during the day and varied according to the season at night. The rate of the increase in the PM₁₀ concentration was the highest in both cities at the wind speed of 1.6 - 3.4 ms^-1 during the day and night except during night in the summer. The highest concentration of PM_2.5 was observed with the wind speed range of 1.6 - 3.4 ms^-1 in Jeju, and 0.3 - 1.6 ms^-1 in Seogwipo. The results of this study applied to urban and landscape planning will aid in the formulation of strategies to reduce the adverse effects of fine particular matter.

• Journal of Environmental Analysis, Health and Toxicology
• /
• v.21 no.4
• /
• pp.264-280
• /
• 2018

In this study, volatile organic compounds (VOCs) were measured using a proton transfer reaction-time of flight-mass spectrometer (PTR-ToF-MS) at the Seoul Metropolitan Area Intensive Monitoring Station (SIMS) in Korea during the summer season of 2018. The results revealed that oxygenated VOCs (OVOCs) contributed a large fraction (83.6%) of the total VOCs, with methanol being the most abundant constituent (38.6%). The VOCs measured at SIMS were strongly influenced by local conditions. Non-volatile organic compounds (NVOCs), such as pinene, increased due to northeasterly wind direction in the morning, and OVOCs and anthropogenic VOCS (AVOCs) increased with northwesterly wind direction during the daytime. This was the result of the eastward location of Bukhansan National Park and the westward location of urban area from the SIMS location. The VOCs included abundant oxidized forms of VOCs, which can affect the generation of fine dust through various response pathways in the atmosphere. The real-time measurement technique using PTR-ToF-MS suggested in this study is expected to contribute to an improved scientific understanding of high-concentration fine dust events because the high temporal resolution makes it possible to analyze the variations of VOCs reflected in dynamic events.

• Land and Housing Review
• /
• v.14 no.4
• /
• pp.111-120
• /
• 2023

Indoor air quality has become increasingly important with the increase in time spent in residential environments, impact of external fine dust, yellow dust, and the post-COVID 19 pandemic. Residential mechanical ventilation plays a key role in addressing indoor air quality. The legal standard for residential air changes per hour in Korea is 0.5 ACH. However, there are no standards for the location of supply and return vents. This study atempts to analyze the impact of ventilation performance based on the location of supply and return vents. An experiment was conducted using the CO₂ tracer gas concentration decay method in a mock-up house set inside a large chamber to minimize external influences. The experimental results indicated that the commonly used combination of 2 supply and 2 return vents in living room spaces had a lower mean age of air than the combination of 1 supply and 2 return vents. Using multiple supply and return vents had lower mean age of air than using just 1 supply and 1 return vent.

• Journal of Korean Society for Atmospheric Environment
• /
• v.23 no.3
• /
• pp.322-331
• /
• 2007

In this study, we have analyzed $PM_{10}$ concentration measured at Incheon Regional Air Monitoring Network (10 stations) and meteorological data at Incheon Weather Station to investigate factors (i.e. wind direction, wind speed, relative humidity, major meteorological phenomenon, and sea-land breezes existence) influencing $PM_{10}$ concentration in Incheon during 2005. Statistical differences among meteorological factors were assessed by Kruskal-Wallis test or Mann-Whitney U test. The main conditions causing high $PM_{10}$ concentration are summarized below; 1. When westerly wind prevailed (however, $PM_{10}$ decreased when winds were blowing from the east or north). 2. When the winds were calm, owing to accumulation of nearby emissions under stagnant conditions, or when the wind speed is in excess of 6 m/s, which shows the effect of fugitive dust produced by wind erosion. 3. Under the condition of high relative humidity and poor diffusion based on meteorological phenomenon such as fog, mist, and haze. 4. When the Sea-Land breezes existed, which occurred 70 days in Incheon during 2005 and contributed significantly to high $PM_{10}$ concentration in the coastal urban area. In conclusion, we have found that the meteorological factors have influence on $PM_{10}$ concentration in Incheon.