• Clean Technology
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• v.24 no.4
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• pp.339-347
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• 2018

In order to cope with environmental problems and climate change caused by fossil fuels, renewable energy supply is increasing year by year. Currently, waste energy accounts for 60% of renewable energy production. However, waste has a lower calorific value than fossil fuels and contains various harmful substances, which causes serious problems when applied to power generation boilers. In particular, the chlorine in the waste fuel increases slagging and fouling of boiler heat exchangers, leading to a reduction in thermal efficiency and the main cause of high temperature corrosion, lowering facility operation rate and increasing operating cost. In this study, the high temperature corrosion experiments of superheater materials (ASME SA213/ASTM A213 T2, T12 and T22 alloy steel) by alkali chlorides were conducted, and their corrosion characteristics were analyzed by the weight loss method and SEM-EDS. Experiments show that the higher the temperature and chloride content, the more corrosion occurs, and KCl further corrodes the materials compared to NaCl under the same condition. In addition, the higher the chromium content of the material, the better the corrosion resistance to the alkali chlorides.

• International Area Studies Review
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• v.13 no.3
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• pp.501-525
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• 2009

Recent increase of academic interest in Born Globals has brought abundant researches, which accounts their causes and states, both in and out of the country. However, postulating that types of companies see the different perception of environment of global markets, and this difference will also bring different effects on enterprise capabilities and performance, this study implemented theoretical inquiry and evidential analysis. Technologically innovative SMEs, main subjects of this study, were categorized into Rapid Globals and Gradual Globals according to their internationalization speed, then followed by a CSA. This analysis has shown, regardless of corporate types, early perception of changes in global market environments, affects, in great amount, on marketing and R&D capabilities as well as performance. However, corporate types also showed difference in early perception of changes, marketing and R&D capabilities as well as performance. This evidential analysis provides enterprises pursuing internationalization in early stage with enforcement in their early perception of changes in global market environments.

• Journal of Korea Port Economic Association
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• v.35 no.2
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• pp.93-108
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• 2019

Recently, air pollution from the marine ports has become a serious issue all over the world. Because marine trade accounts for 99.7% of Korea's trade, efforts are required to recognize the level of port pollution and establish environmental policies. This study estimates air pollution emitted during the berthing process in the Gwangyang and Ulsan ports. Data on ship activity and characteristics are collected and reasonable methodologies and factors from EEA and EPA are adopted. The results show that 253.09 tons of CO, 1986.61 tons of NOx, 684.01 tons of SOx, 47.88 tons of $PM_{10}$, and 44.69 tons of $PM_{2.5}$ are emitted at the Gwangyang port. Further, the Ulsan port emitted 212.28 tons of CO, 1712.54 tons of NOx, 573.72 tons of SOx, 40.16 tons of $PM_{10}$, and 37.48 tons of $PM_{2.5}$. A stage-by-stage plan for installing AMP infrastructure is suggested as part of a green port policy. This research provides the current pollution status and contributes guidelines for the direction of future policy.

• Journal of Ecology and Environment
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• v.46 no.4
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• pp.316-323
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• 2022

Background: We developed a habitat suitability index (HSI) model for Pedicularis hallaisanensis, a Grade II Endangered Species in South Korea. To determine the habitat variables, we conducted a literature review on P. hallaisanensis with a specific focus on the associated spatial factors, climate, topography, threats, and soil factors to derive five environmental factors that influence P. hallaisanensis habitats. The specific variables were defined based on the collected data and consultations with experts in the field, with the validity of each variable tested through field studies. Results: Mt. Seorak had a suitable habitat area of 2.48 km² for sites with a score of 1 (0.62% of total area) and 0.01 km² for sites with a score of 0.9. Mt. Bangtae had a suitable habitat area of 0.03 km² for sites with a score of 1 (0.02% of total area) and 0 km² for sites with a score of 0.9. Mt. Gaya showed 0.13 km² of suitable habitat for sites with a score of 1 (0.17% of total area) and 0 km² for sites with a score of 0.9. Lastly, Mt. Halla showed 3.12 km² of suitable habitat related to sites with a score of 1 (2.04% of total area) and 4.08 km² of sites with a score of 0.9 (2.66% of total area). Mt. Halla accounts for 73.1% of the total core habitat area. Considering the climatic, soil, and forest conditions together with standardized collection sites, our results indicate that Mt. Halla should be viewed as a core habitat of P. hallaisanensis. Conclusions: The findings in this study provide useful data for the identification of core habitat areas and potential alternative habitats to prevent the extinction of the endangered species, P. hallaisanensis. Furthermore, the developed HSI model allows for the prediction of suitable habitats based on the ecological niche of a given species to identify its unique distribution and causal factors.

• Journal of the Korean Geotechnical Society
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• v.38 no.5
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• pp.5-17
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• 2022

A pile is a type of medium for constructing superstructures in weak geotechnical conditions. A pretensioned spun high-strength concrete (PHC) pile is composed of high-strength concrete with a specified strength greater than 80 MPa. Therefore, it has advantages in resistance to axial and bending moments and quality control and management since it is manufactured in a factory. However, the skin friction of a pile, which accounts for a large portion of the pile bearing capacity, is only approximated using empirical equations or standard penetration test (SPT) N-values. Particularly, there are some poor research results on the pile-soil interface under the seismic loads in Korea. Additionally, some studies do not consider geoenvironmental elements, such as groundwater pH values. This study performs sets of cyclic simple shear tests using submerged concrete specimens for 1 month to consider pH values of groundwater and clay specimens composed of kaolinite to generate a pile-soil interface. 0.2 and 0.4 MPa of normal stress conditions are considered in the case of pH values. The disturbed state concept is employed to express the dynamic behavior of the interface, and the disturbed function parameters are newly suggested. Consequently, the largest disturbance increase under basic conditions is observed, and an early approach to the failure under low normal stress conditions is presented. The disturbance function parameters are also suggested to express this disposition quantitatively.

• Journal of Wetlands Research
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• v.24 no.2
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• pp.93-101
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• 2022

This study was conducted to analyze the distribution characteristics of abandoned paddy wetlands according to topography and land cover. In Seosan-si, Dangjin-si, Boryeong-si, and Taean-gun, Chungcheongnam-do, abandoned rice wetlands were found through GIS and field surveys, and the distribution status according to slope, elevation and land cover type was analyzed. As a result of the study, a total of 106 abandoned paddy wetlands were identified, and the average elevation of each abandoned paddy wetlands was 38.85m (S.D.32.76), the average slope was 6.27˚ (S.D.5.39), and the total area was 24,200km². 90 sites (84.9%) of abandoned paddy wetlands were distributed on flat land with less than 5˚ slope, 63 sites (12,121.07km²), and 27 sites(9,524.15km²) at 5-10˚ (9,524.15km²) on flat land with less than 10˚. The area is 21,645.22km²(89.5%) of the total area of abandoned paddy wetlands. 48 sites(12,326km²) in the lowlands with an altitude of less than 25 m, 29 sites(4,909.4km²) below 50m. It accounts for 71.2% of the total area of abandoned paddy wetlands. Among environmental factors of abandoned paddy wetlands, there was no statistically significant correlation between slope and altitude. According to the land cover classification, it was widely distributed in artificial grasslands (38), paddy fields (33), and fields (22).

• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.5
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• pp.667-674
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• 2023

In the event of a disaster occurring within a building, the prompt and efficient evacuation and rescue of occupants within the building becomes the foremost priority to minimize casualties. For the purpose of such rescue operations, it is essential to ascertain the distribution of individuals within the building. Nevertheless, there is a primary dependence on accounts provided by pertinent individuals like building proprietors or security staff, alongside fundamental data encompassing floor dimensions and maximum capacity. Consequently, accurate determination of the number of occupants within the building holds paramount significance in reducing uncertainties at the site and facilitating effective rescue activities during the golden hour. This research introduces a methodology employing computer vision algorithms to count the number of occupants within distinct building locations based on images captured by installed multiple CCTV cameras. The counting methodology consists of three stages: (1) establishing virtual Lines of Interest (LOI) for each camera to construct a multi-camera network environment, (2) detecting and tracking people within the monitoring area using deep learning, and (3) aggregating counts across the multi-camera network. The proposed methodology was validated through experiments conducted in a five-story building with the average accurary of 89.9% and the average MAE of 0.178 and RMSE of 0.339, and the advantages of using multiple cameras for occupant counting were explained. This paper showed the potential of the proposed methodology for more effective and timely disaster management through common surveillance systems by providing prompt occupancy information.

• Clean Technology
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• v.16 no.2
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• pp.103-116
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• 2010

It has been reported that the LCD panel market in the FPD industry is become growing and its panel size and production capacity are increasing, and its manufacturing technique is improved every year. FPD manufacturing process requires high cleanliness in its overall process. Especially, FPD cleaning process which accounts for 30~40% of total manufacturing process is very important in its technological and productivity aspects. It is difficult to remove residual liquid-crystal in the fine gap after liquid-crystal injection process in the cell. In this study, aqueous cleaning agents with excellent cleaning, rinsing, and penetrating abilities, but minimum ion content for LCD panel were formulated through mixing glycol ether-type and glycol dimethyl ether-type solvents and nonionic surfactants which are widely used as raw materials for alternative cleaning agents because of environmental regulation at home and abroad. And the formulated cleaning agents were applied to clean FPD liquid crystal after its injection in the cell. Physical properties, cleaning efficiencies, and rinsabilities of the formulated cleaning agents with different combination ratios of solvents, surfactants and additives were measured. As experimental results, the formulated cleaning agents showed higher wetting indices and cloud point than the traditional commercial cleaning agent. And it was found that cleaning efficiencies of the formulated cleaning agents were influenced by the structure of main solvents in them and the types of liquid crystal as soil for cleaning. The best cleaning agents among the formulated cleaning agents showed similar cleaning efficiencies and better rinsabilities compared to the conventional cleaning agent.

• Journal of the Korean Geotechnical Society
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• v.22 no.4
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• pp.11-19
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• 2006

For the last decade, the hi-directional testing method has been advantageous over the conventional pile load testing method in many aspects. However, because the hi-directional test uses a loading mechanism entirely different from that of the conventional pile load testing method, many investigators and practicing engineers have been concerned that the hi-directional test would give inaccurate results, especially about the pile head settlement behavior. Therefore, a hi-directional load test and the conventional top-down load test were executed on 1.5 m diameter cast-in-situ concrete piles at the same time and site. Strain gauges were placed on the piles. The two tests gave similar load transfer curves at various depth of piles. However, the top-down equivalent curve constructed from the hi-directional load test results predicted the pile head settlement under the pile design load to be about one half of that predicted by the conventional top-down load test. To improve the prediction accuracy of the top-down equivalent curve, a simple method that accounts for the pile compression is proposed. It was also shown that the strain gauge measurement data from the hi-directional load test could reproduce almost the same top-down curve.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.1
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• pp.55-62
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• 2023

Internal erosion is one of the main causes of levee damage and collapse, and representative of this is backward erosion piping. This type of internal erosion accounts for one-third of the damage to levees, meaning it is important to predict and prevent it. In this work, experiments were conducted with the aim of detecting piping in advance by using a tracer. Experiments were undertaken by changing the head difference, soil diameter, and the installation of the cutoff wall. A tracer was injected twice, once at the beginning of the experiment and once after the piping occurred. A key finding was that the piping process significantly affectedthe concentration variation of the tracer in a soil layer. Hence, a tracer concentration curve monitored at downstream could provide information about piping occurrence. It is expected that the results of this study can be used to prevent levee damage and collapse caused by piping.