• Journal of Korean Tunnelling and Underground Space Association
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• v.21 no.6
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• pp.811-823
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• 2019

Slip form method is applied to many cases of a shaft these days because it is safer, more economical and faster than cast-in-place method. Slip-up height of the method is approximately 2.5 to 4.0 m/day. If the temperature of concrete is outside the range of 10 to 30℃, the effects of changes in strength or elastic characteristics are significant. Therefore, it is difficult for slip-up speed to be higher than 3 m/day during winter construction. In addition, concrete has heat caused by hydration, which causes temperature cracking of hardened concrete. Therefore, temperature control of concrete curing is necessary for the continuous slip-up of slip form. In this study, the rebound hardness, time of ultrasonic waves propagation, heat of hydration, and external temperature are measured by developing heating panels and test devices for the continuous slip-up. Based on this, heating slip form is manufactured; this was applied to "Kimpo sites" and "Sinwol sites". The compared slip-up speed samples were 1.9 m/day or 0.200 m/hr on average at Gimpo sites (08:00~17:30) and 2.0 m/day or 0.210 m/hr at Sinwol sites.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.6
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• pp.637-641
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• 2008

The aims of this research were to manufacture tailored powder activated carbon having a higher prechlorate removal efficiency and to compare perchlorate removal efficiency with different carbon materials for applying to the drinking water treatment plant. Activated carbon pre-loaded with cetyltrimethylammonium chloride(CTAC) has been researched to be an effective adsorbent for removing perchlorate in the water. 10,000 mg/L tailored powder activated carbon were manufactured by mixing 5.0 g of powder activated carbon(PAC) into 500 mL of 5,000 mg/L CTAC solution. The tailored powder activated carbon had 10 times higher perchlorate removal efficiency than virgin powder activated carbon. The residual perchlorate gradually decreased with the first 15 minute contact time with the tailored powder activated carbon, however, the longer contact time did not affect perchlorate removal. Tailored powder activated carbon by manufactured with 1,083 mg/g iodine value carbon had almost 4 times higher perchlarate removal efficiency than the 944 mg/g iodine value carbon. Dosage of 5 mg/L tailored powder activated carbon, which can adaptable dosage at the treatment plant, could decrease the perchlorate concentration from 50 $\mu$g/L to 15 $\mu$g/L.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.5
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• pp.98-105
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• 2018

Cracks in RC members occurred as a result of material and structural factors. The crack width and a crack location are very difficult to examine. A direct crack control method and indirect crack control method to control a crack are presented in the KHBDC (LSD) and KSCDC (2012). In the KSCDC text, cracks are controlled by steel spacing indirectly under a service load. On the other hand, in the KSCDC appendix, cracks are controlled by a crack width directly under a sustained load. In particular, the loading state considered is different. On the other hand, cracks are controlled under a combination of service load and an effective elastic modulus is used in KHBDC. Therefore, in this study, an effective elastic modulus that can reflect the ratio of the sustained load and live load was applied, and a maximum steel spacing was calculated through a design crack width. A variable interpretation was carried out, and a rational crack control method was assessed. As a result, a steel spacing through the design crack width in the KSCDC was smaller than that from the design crack width in the KHBDC, which leads to a conservative design. In addition, the maximum steel spacing suggested in this study has a consistency eliminating the difference between direct crack control and indirect crack control.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.1
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• pp.633-638
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• 2018

We are constantly hearing about the seriousness of food shortages in North Korea through various media reports. Recently, the severity of the problem has increased, and international organizations and relief organizations have become increasingly concerned. Due to the shortage of food and firewood, residents illegally cut trees in the mountains and, as a result, North Korea has become the third fastest-growing area of forest degradation in Asia. However, since North Korea cannot directly measure the extent of forest degradation, remote sensing techniques using satellite imagery have to be applied. The purpose of this study was to analyze the characteristics of forest change in North Korea, in order to understand the severity of the forest degradation problem. For this purpose, Landsat 5 TM and Landsat 8 OLI TIRS satellite images were acquired and classified. As a result, it was found that the forests have turned into wilderness in the Nampo City and Pyongyang municipalities, while the wasteland has changed into forests in the north of Yanggangdo. In addition, the total forested area of the whole region decreased by $4,166.22km^2$, the residential area decreased by $2,017.03km^2$, and the amount of agricultural land increased by $6,625.74km^2$, which is similar to the amount of forested area lost, although the difference in the overall area of the forests between 2017 and 2006 was small.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.6
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• pp.3923-3930
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• 2014

In this study, the physical and dynamic characteristics of soil were analyzed by selecting 3 sections as research subjects among road and structure construction sections in the construction site of the Gwangyang ${\bigcirc}{\bigcirc}$ industry area, and conducted consolidation analysis and bearing capacity assessments through Midas-GTS according to the construction conditions of the structures and section conditions of reinforcement using stabilized soil. The effects of improving the settlement and bearing capacity according to the improved effects of the stability and sections of reinforcement using stabilized soil in applying the reinforcement method using stabilized soil were analyzed as a solution for improving the settlement and bearing capacity of soft clay for constructing roads and structures. The improvement effects of the settlement and bearing capacity were outstanding when the reinforcement method using stabilized soil to the soft clay was applied. After applying the reinforcement method using stabilized soil, the holdback effect of the consolidation settlement was excellent by decreasing the volume of the consolidation settlement from a minimum of 53% to a maximum of 82%. When the width of the reinforcement using stabilized soil was twice the width of the constructed structure, it was found that the holdback effect of the consolidation settlement ranged from 1% to 7% through the width of reinforcement using stabilized soil. In addition, when applying reinforcement more than 6m in width and 1m in depth using stabilized soil, it was found that the increase in the allowable bearing capacity was 2.3 to 3.3 times more than that before applying the reinforcement, which suggests that the increase in bearing capacity by applying the reinforcement method using stabilized soil was significant.

• Journal of the Korean Institute of Landscape Architecture
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• v.41 no.5
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• pp.68-77
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• 2013

Change in the Global Climate causes flood, drought, heavy snow, and rainfall patterns in the Korean Peninsula. A variety of alternatives related to climate change are considered. The foreign researchers are interested in Low Impact Development(LID); the utilization of water resources and eco friendly development, over 10 years ago. The research and development of related technology has been advanced to apply LID techniques in order to develop several projects in the country. However, sharing of technology or system that can be used easily in the private sector is insufficient. The performance of the elements of LID Technology has not been fully agreed. LID elements of this technology are easy to apply to Apartment complex. The elements are classified technology. The infiltration of elements performs the functions of apartment complex landscaping space technology applied to the target. The water cycle simulation(SWMM 5.0) and technology the implementation of the effectiveness is also verified. For this purpose, three different places in apartment complex to target by SWMM5.0 U.S. EPA conducted utilizing simulated rainfall and applying LID techniques before and after the simulated water cycle (infiltration, surface evaporation, and surface runoff) were conducted. The importance of green space in the LID techniques of quantitative and qualitative storm water control as well as the role of Apartment Housing is to promote Amenity. Remember that the physical limitations of apartment complex and smooth water circulation system for the application of LID integrated management techniques should be applied. To this end, landscapes, architecture, civil engineering, environmental experts for technical consilience between the Low Impact Development efforts are required.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.7
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• pp.1319-1330
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• 2000

Activated carbons prepared by chemical activation of organic waste sludges with $ZnCl_2$ and $K_2S$ have been studied in terms of their pore development and adsorptivity. Pore development of the carbons prepared from organic waste sludges was characterized by the nitrogen adsorption at 77K. The $ZnCl_2$-activated carbon produced by chemical activation with zinc chloride exhibited type I isotherm characteristics according to the BDDT classification, suggesting the presence of micropores formed by activation process. The isotherms of the commercial powdered activated carbon and $K_2S$-activated carbon reveal a hysteresis similar to that of type IV in BDDT classification, indicating the formation of mesopores. This result implies that the major pores of $K_2S$-activated carbon are composed of meso and micropores, and a macropores are minor. The adsorptive capacities of metal on the $K_2S$-activated carbon prepared from organic waste sludges were found to be superior to those on a commercial granular activated carbon. The Langmuir and Freundlich isotherms yield a fairly good fit to the adsorption data, indicating a monolayer adsorption of metals onto $K_2S$-activated carbon. The adsorptive capacity of the $K_2S$-activated carbon was superior to $ZnCl_2$-activated carbon for $PO_4$-P, and vice versa for $NO_3$-N. From the results of the studies reported here, it can be concluded that activated carbons with adsorptivity superior to commercial granular activated carbons can be produced from organic waste sludge using a two-step carbonization/activation procedure with zinc chloride or potassium sulfide as the activating agents.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.10
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• pp.701-708
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• 2011

In this study, the emissions of GHG from general ships were calculated by Tier1 method based on the fuel consumption, and by Tier3 method based on the activities data such as power and SFOC of each engine, sailing characteristics (e.g. time and load factor, etc.) considering the ship type. In 2009, the emissions of GHG by Tier1 and Tier3 method were appeared 28.27 mega-ton $CO_{2eq}$ and 30.81 mega-ton $CO_{2eq}$. The emissions by Tier3 were slightly more than those by Tier1. We found that the values of the sailing characteristics for surveyed data are overestimated slightly. In the near future, more detailed researches for sailing characteristics considering ship types would be needed for sailing, anchoring, and berthing condition, etc.

• Korean Journal of Construction Engineering and Management
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• v.19 no.6
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• pp.14-23
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• 2018

In the domestic construction industry, large-scale housing construction projects are being carried out by construction companies with competitiveness in the domestic top 10, it is said that the competence of the construction engineer is a factor for the success of the project. In Korea, there is National Competency Standards (NCS) that systematize contents of knowledge, technology, and attitude required in order to perform job in industrial field as the importance of individual ability is systemized in the country. Therefore, in this study, defined the detail competence in construction administration works, and examined the level of competence and degree of impotance detailed competency of construction engineers using AHP analysis & ANOVA. As a result, it was found that the current capacity of the Engineers in the apartment construction work is insufficient compared to the level of the competence they think they have, and that they have different competencies depending on their work experience and job position. This means that if the career is accumulated, the capacity that is possessed naturally will be changed. Therefore, it will be necessary to improve the capacity of the construction engineers who have a short work experience and a low job level.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.4
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• pp.362-373
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• 2018

This study was conducted to investigate the relationship between interest in smoking cessation and factors that define this interest. The study subjects were 593 male civil servants who work at D metropolitan city and were smokers at the time of the survey. The research method was a survey using a self-administered questionnaire in October 2015. Interest in smoking cessation of study subjects showed that 28.3% had no interest in smoking cessation, 45.7% were interested in smoking cessation, but had no intention to quit within six months, and 26.0% were interested in smoking cessation and intended to quit within six months. Multiple regression analysis revealed that the factors influencing interest in smoking cessation with explanatory powers of 23.6% were employment type, age when first starting smoking, number of cigarettes smoked per day, time from when you wake up until you smoke your first cigarette, recognition of susceptibility to lung cancer, and benefits to smoking cessation. Logistic regression analysis revealed that the odds ratio of recognition of susceptibility for lung cancer, benefits to smoking cessation, and barriers to smoking cessation were significantly increased in the group with interest in smoking cessation and intention to quit within six months vs. the group with no interest in smoking cessation. Taken together, these results suggest that cancer prevention due to smoking and awareness of the seriousness of health problems caused by smoking were factors increasing interest in smoking cessation.