• Fire Science and Engineering
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• v.31 no.4
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• pp.103-110
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• 2017

With the common tendency in the accordance with the trend, low-stories built edifices that are Pilotis-oriented structured exponentially and constantly increasing its number of buildings. It inevitably contains its risks of facing conflagrations as most of its part is used as parking lots. In the parking lots, the length of the flame has a heavy-weighted possibility that it would get increased because the heat release rate gets relatively high due to the vehicle insulation. Following on top of that, due to the nature of the Pilotisconsisting of pillars, there is a risk of flame spread to the adjacent building if the same Pilotis-structured buildings are adjacent to each other, if the flame spreads to the surroundings due to the influence of the wind. Because the most of the pilotis-structured-buildings have this entrance that makes the residents be able to enter, if the entrance were plugged the resident get a serious risk of a poisonous gas and a flame. Therefore, if the parking-lots of the pilotis-structured-buildings are adjacent to each other it requires a space to prevent the place from the spread of flame. This research studied how far is appropriate to prevent flame spreading with FDS. As a result, the study found that the distance at least 3.0 m is required.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.520-520
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• 2016

석유 화학공장에서 발생하는 spent sulfidic caustic (SSC) 폐수는 액화석유가스(LPG)나 천연가스(NG)의 정제과정에서 발생되는 것으로 고농도의 sulfide와 cresylic, phenolic 그리고 mercaptan 등이 포함된 독성과 냄새를 유발하는 물질이다. 이러한 물질들은 LPG나 NG의 정제과정에서 높은 산도를 가진 휘발성 황화합 물질들을 제거하기 위해 사용된 NaOH가 $H_2S$와 반응하여 발생하는 것이다. 진한 갈색 또는 검은색을 띄는 SSC 폐수는 12 이상의 높은 pH를 가지고 있으며 5~12 wt%의 높은 염분도를 가지고 있다. 또한 강한 부식성과 독성을 가진 황화합물의 농도가 1~4 wt%이며, 방향족 탄화수소 물질 (i.e. methanethiol, benzene, tolune and phenol)들도 다량 함유되어 있다. 따라서 이러한 유해 물질들은 기존의 하수처리 공정으로 방류하기 전에 완벽하게 처리해야만 하수처리 공정의 오염 부하량을 줄일 수 있다. 습식산화공정은 SSC 폐수를 처리하기 위해 흔히 사용되고 있는 물리-화학적 처리 공정이지만 고비용, 고에너지가 필요하며, 고온 및 고압에서만 작동되어 안전상의 문제점을 갖고 있다. 또한 습식산화공정을 거친 폐수는 배출허용기준을 만족하기 위해 생물학적 2차 처리가 반드시 필요하다. 철-과산화수소를 이용하는 펜톤산화 공정, 그리고 sulfide를 sulfate로 전환시키는 생물학적 처리 공정은 황화합물의 완전한 무기물화가 힘들며, 현장 적용 시 기술적 경제적 부담이 크다. 이러한 단점을 극복하고, SSC 폐수를 효과적으로 처리하기 위해 본 연구는, 높은 흡착력과 광산화력을 가진 흡착광산화 반응 시스템(Adsorption Photocatalysis System, APS)을 개발하였다. APS는 SSC 폐수를 시스템 내부로 유입하여 수중의 오염물질을 흡착광산화제로 구성된 반응구조체가 흡착하고, 흡착된 오염물질을 UV에너지와 이산화티타늄 광촉매의 광화학반응에 의해 최종적으로 무해한 물질로 환원시키는 폐수처리시스템이다. APS의 반응구조체는 태양에너지 및 인공에너지원에 의해 활용 가능하며, 난분해성 유기화합물질을 물과 이산화탄소로 분해할 수 있는 친환경적이고 경제적인 소재로서 널리 쓰이고 있는 이산화티타늄 광촉매와 화력발전소의 높은 소성온도에 의해 연소된 후 발생되는 bottom ash를 이산화티타늄의 지지체로 사용하여 높은 흡착력과 광촉매 산화력을 가진 복합물이다. 개발된 APS에 의해 SSC 폐수를 처리한 결과, COD 86.1%, 탁도 98.4%, sulfide 99.9%의 높은 처리효율을 보여주고 있다. 따라서 본 연구를 통해 개발된 APS는 강한 부식성과 독성 그리고 높은 농도를 가지고 있는 SSC 폐수를 효과적으로 처리할 수 있다.

• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.3
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• pp.271-278
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• 2019

The corrosion of reinforcements embedded in concrete causes severe deterioration in reinforced concrete structures. As a countermeasure, epoxy coated reinforcements are used to prevent corrosion of reinforcements. When epoxy coated bars are used, the resistance of corrosion is excellent, but epoxy coating on the bars have a disadvantage of reduction in bond capacity comparing to that of normal bars. Therefore, it is necessary to confirm the bond performance of epoxy coated reinforcements through experimental and analytical methods. Bond behaviors of epoxy coated bars for various diameters of 13 and 19mm and thicknesses of cover concrete of 3 types(ratio of cover to bar diameter) are examined. As the diameters of the epoxy coated bars increase, the difference of bond strength between epoxy coated and uncoated bars also increases and damage patterns showed pull out failure. In addition, finite element analysis was performed based on the bond-slip relationship obtained by direct pullout test and compared with the flexural test results. It is considered that flexural member test is more useful than pullout test for simulating the behavior of actual structure.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.6
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• pp.76-83
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• 2021

This study examines the bending behavior of lap-spliced ultra-high-strength fiber-reinforced concrete members and evaluates the safety of the design codes for ultra-high-strength fiber-reinforced concrete structures. An experiment on a total of six beams was performed. The main variables were the fiber-inclusion and the lap-spliced length at the center of the beams. The steel fibers in a volume fraction of 2% were used, and the lap-splice lengths were determined to be 8db and 16db. As a result of the test, the specimens not reinforced with fiber lost abrupt load-bearing capacity at the lap region and did not experience yielding of the reinforcing bar. In the case of fiber-reinforced concrete, if a lap-splice length of 16db is secured, the yielding of the main reinforcing bar can be experienced, and appropriate flexural strength can be expressed. Based on the experimental results of this study, as a result of reviewing the lap-splice length calculation formulas of the current design standards and the ultra-high-strength concrete structural design recommendations, it was found that all of them were evaluated conservatively.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.17 no.6
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• pp.54-66
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• 2018

In this study, vehicle speeds at acceleration and deceleration lanes of rest areas for drowsy drivers were investigated to analyze effects of acceleration and deceleration lane lengths, grades and curve radius. In addition, we used VISSM to analyze proper lengths of rest area's acceleration and deceleration lanes. Several VISSIM scenarios with different lengths of acceleration and deceleration lane were constructed. Through VISSIM simulation, we collected individual vehicle speed data to analyze speed changes by different lengths of acceleration and deceleration lanes. As a result of the vehicle speed change investigation, grades and curve radii of the rest area affected the speed, most of all lengths of acceleration and deceleration lane showed a great effect on the vehicle speed. In the case of short lengths of acceleration and deceleration lane, speed variation among vehicles was significant. If the deceleration lane length is short, the vehicle enters a state in which the speed is not sufficiently reduced, and if the acceleration lane length is short, the vehicle enters a state in which the speed is not sufficiently accelerated showing high risks of conflicts and accidents. It is recommended that 245m length of deceleration lane and 370m length of acceleration lane should be installed at least to secure safety and manage conflicts relevantly.

• Journal of Korea Water Resources Association
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• v.53 no.12
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• pp.1183-1192
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• 2020

Economic analysis is a basic step in establishing disaster mitigation measures, but it is difficult to verify the results due to uncertainty. Therefore, the scope of investigation and analysis is wide. However, it is difficult to predict the amount of damage caused by flooding because the collection of relevant data is limited in the ungauged basin. In this study, distributed runoff analysis and flooding analysis were performed, and a method of estimating the amount of flood damage in the ungauged basin was proposed using collectible social and economic indicators and flood analysis results. For distributed runoff analysis and flooding analysis, GRM (Grid based Rainfall-runoff Model) and G2D (Grid based 2-Dimensional land surface flood model) developed by Korea Institute of Civil engineering and Building Technology were used. The method of substituting collectible social and economic indicators into the simple method and improvement method was used to estimate the amount of flood damage. As a result of the study, it was possible to estimate the amount of flood damage using satellite data and social and economic indicators in the ungauged basin.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.5
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• pp.135-142
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• 2022

In this study, lap spliced ultra-high strength reinforced concrete beams were tested and the code criteria for calculating the lap splice length which was affected by the transverse reinforcement and concrete covering performance were reviewed. The main variables for test were set as fiber volume fraction and transverse reinforcing bar arrangement to improve the confining performance of the concrete cover. The change of the confining performance of concrete cover according to the increase in the fiber mixing amount at 1% and 2% volume ratio was examined, and D10 stirrups with a spacing of 100 mm were placed in the lap spliced region. As a result of the test, the specimens confined by the stirrups showed a sudden drop of load bearing capacity with horizontal cracking at the position of tensile longitudinal reinforcement. However, horizontal cracks were not appeared at the location of longitudinal reinforcement for the specimens with steel fiber. And these specimens showed gradual decrease of load bearing capacity after experiencing peak load. In particular, it was found that the strain at the position of the tensile longitudinal reinforcements of the specimens to which the mixing ratio of 2% was applied exceeds the yield strain. As a result of measuring the strain on the concrete surface, it was found that the fiber was more effective in preventing damage to the concrete surface than the stirrups for short lap spliced region.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.3
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• pp.103-110
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• 2022

The purpose of this study is to experimentally evaluate the stiffness and strength reduction according to the reinforcing bar details of the vertically divided reinforced concrete shear walls. To confirm the effect of reducing strength and stiffness according to vertical division, four real-scale specimens were fabricated and repeated lateral loading tests were performed. As a result of the experiment, it was confirmed that the strength and stiffness were decreased according to the vertical division. In particular, as the stiffness reduction rate is greater than the strength reduction rate, it is expected that safety against extreme strength can be secured when the load is redistributed according to vertical division. As a result of checking the crack pattern, a diagonal crack occurred in the wall subjected to compression control among the divided walls. It was confirmed that two neutral axes occurred after division, and the reversed strain distribution appeared in the upper part, showing the double curvature pattern. In future studies, it is necessary to evaluate the stiffness reduction rate considering the effective height of the wall, to evaluate additional variables such as wall aspect ratio, and to conduct analytical studies on various walls using finite element analysis.

• Journal of Service Research and Studies
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• v.13 no.3
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• pp.1-19
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• 2023

Despite the growing importance of video-based social media content, such as vlogs, as a marketing tool in the travel industry, there is limited research on the characteristics that enhance engagement among potential travelers. This study explores the influence of emotional valence in YouTube travel content on viewer engagement, specifically likes and comments. We analyzed 4,619 travel-related YouTube videos from eight popular tourist cities. Using negative binomial regression analysis, we found that both positive and negative emotions significantly influence the number of likes received. Videos with higher positive emotions as well as negative emotions receive more likes. However, when it comes to the number of comments, only negative emotions showed a significant positive influence, while positive emotions had no significant impact. These findings offer valuable insights for marketers seeking to optimize engagement strategies on YouTube, considering the unique nature of travel products. Further research into the effects of specific emotions on engagement is warranted to improve marketing strategies. This study highlights the powerful impact of emotions on viewer engagement in the context of social media, particularly on YouTube.

• Journal of the Korean Recycled Construction Resources Institute
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• v.12 no.1
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• pp.63-71
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• 2024

Through the development of construction technology, various construction projects such as redevelopment projects, undergrounding of roads, expansion of subways, and metro railways are being carried out. However, this has led to an increase in the number of construction projects in existing urban centers and neighborhoods, resulting in an increase in the number of damages and disputes between neighboring buildings and residents, as well as an increase in safety accidents due to the aging of existing buildings. In this study, digital data was applied to a graphics program to objectify the progress of cracks by comparing the creation of cracks and the increase in length and width through photographic images and presenting the degree of cracks numerically. Through the application of the program, the error caused by the subjective judgment of crack change, which was mentioned as a shortcoming of the existing field survey, was solved. It is expected that the program can be used universally in the building diagnosis process by improving its reliability if supplemented and improved in the process of use. As a follow-up study, it is necessary to apply the extraction algorithm of the digital graphic data program to calculate the length and width of the crack by itself without human intervention in the preprocessing work and to check the overall change of the building.