• Journal of the Korean Society of Safety
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• v.38 no.3
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• pp.77-84
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• 2023

Welding and cutting, which are representative tasks in handling firearms at industrial sites, are the basis for production and maintenance processes across all industries. They are also essential in the root industry. Specifically, they are widely used in the manufacturing industry, including equipment industries such as shipbuilding, automobiles, and chemicals, and subsequent maintenance work and general facility repair. However, such hot work carries a high fire risk owing to sparks scattering and inadequate management, resulting in a high occurrence of accidents. In response, the government and relevant organizations have recently revised the Occupational Safety and Health Act to prevent accidents during hot work. These revisions impose more stringent regulations than before, which are expected to help prevent actual fire accidents. However, whether the fire observer system, which is the core element of the revision, would be practically applied and maintained is unclear. Therefore, this study compared the fire observer system in the revised Occupational Safety and Health Act with those in the laws and systems of developed countries, conducted interviews with safety and health experts to assess the suitability of the new system for fire observer operations, and improvement plans were derived accordingly. Therefore, the laws and systems of developed countries grant more authority to fire observers compared with those of Korea. Moreover, professional training in handling emergency is required. Interviews with safety and health experts revealed that regardless of company size, the same operating standards were applied, and standards for deploying fire observers in various locations were unclear. Furthermore, there was a lack of professional education and training, and the role and authority of fire observers were limited. These findings revealed a problem in this sector. The results of this study are expected to serve as basic data for establishing a practical system for placing fire observers and supplementing laws, guidelines, and systems for preventing fire accidents.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.22 no.3
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• pp.55-71
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• 2019

The purpose of this study is to propose an evaluation method to assess green environments of streetscapes to improve urban street green spaces in Jeonju City. Through a rapid assessment of urban street green spaces, we suggest an objective basis for expanding street green space as well as for adopting sustainable maintenance and improvement measures. We choose 12 sections of streetscapes (roads and sidewalks) to investigate existing street conditions which have more than four lanes and function as major road axes. Six large roads and six medium roads of Jeonju City center area are investigated as pilot assessment study sites. Site inventory checklists consist of environmental characteristics of streetscape, street tree status, and planting condition evaluation. Environmental characteristics of streetscapes are composed of physical and neighborhood factors. For instance, items for physical factors are types and width of road/sidewalks, paving materials, tree protection materials, and green strip. And surrounding landuse is a neighborhood factor. Assessment items for street tree status are street plant names (tree/shrubs/ground cover), size, and planting intervals. Planting condition evaluation items are tree shape, damage, canopy density, and planting types with existence of adjacent green space. Evaluation results are classified into three levels such as A(maintain or repair), B(greening enhancement), and C(structural improvement). In case of grade A, streetscapes have enough sidewalk width for maintaining green strip and a multi-layered planting(in large road only) with fairly good growing conditions of street trees. For grade B and C, streetscapes have a moderate level of sidewalk width with a single street tree planting. In addition, street tree growing conditions are appeared poor so that green enhancement or maintenance measures are needed. For median, only grade B and C are found as its planting growing foundations are very limited in space. As a result, acquiring enough sidewalk space is essential to enhance ecological quality of urban street green. Especially, it is necessary to have green strip with reasonable widths for plant growing conditions in sidewalks. In addition, we need to consider native species with multi-layer plant compositions while designing street green.

• International Journal of Highway Engineering
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• v.16 no.6
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• pp.159-167
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• 2014

PURPOSES : The purpose of this study is to analyze the requirements of the road traffic safety moderator robot when road repairing. The road traffic safety moderator robot is road traffic safety equipment and to conversions mechanical engineering and IT when road repairing. METHODS : The study used AHP based on the survey from road repair related expert that field engineers, design engineers, public officials and professors. The survey used paired comparison. The survey items were safety, convenience and economics. The safety is classified as visibility or efficiency, the convenience is classified as utility or mobility and the economics is classified as initial investment cost or maintenance $ management cost. The survey alternatives were the road traffic safety moderator robot, traffic regulation by human, traffic regulation by mannequin and traffic signs. The software for AHP is Expert Choice 2000. RESULTS : The results of AHP analyze, the weighted value of safety was analyzed with the highest at 0.488 of survey items. The weighted value of convenience was analyzed at 0.295, the weighted value of economics was analyzed at 0.218. The results of the road traffic safety moderator robot, the weight value of efficiency and utility were analyzed with the highest at 0.284 and 0.259 of alternatives. The weighted value of initial investment cost and maintenance & management cost were analyzed with the lowest at 0.203 and 0.211 of alternatives. The consistency test results of each items, null hypothesis is rejected because the CR values were 0.000 respectively. Therefore, the study results are consistency. CONCLUSIONS : The result of this study, overall value of the road traffic safety moderator robot came off second-best of other alternatives. The road traffic safety moderator robot has been received highest praise by the result of the study as good road traffic safety equipment when road repairing because the weighted values of efficiency and utility were analyzed with the highest of survey items. The efficiency mean securing safety and the utility mean practical assistance when road repairing. The results of this study showed that the road traffic safety moderator robot will effective for traffic safety when road repairing. economics and visibility are that supplementation of the road traffic safety moderator robot because the weighted values of economics and visibility were analyzed with the lowest of survey items. The consistency test results are consistency because the CR values were 0.000 respectively.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.2
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• pp.161-169
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• 2011

Two-way slabs reinforced with high-performance steels, which have several practical advantages of a reduction of congestion in heavily reinforced members, savings in the cost of labor and repair, the higher corrosion resistance, and a reduction of construction time, were constructed and tested. The influences of the flexural reinforcement ratio, concentrating the reinforcement in the immediate column region, and using steel fiber-reinforced concrete (SFRC) in the slab on the punching shear resistance and post-cracking stiffness were investigated, and compared with the punching shear test results of the slabs reinforced with conventional steels and GFRP bars. In addition, the strain distribution of flexural reinforcements and crack control were investigated, and the effective width calculating method for the average flexural reinforcement ratio was estimated. The use of high-performance steel reinforcement increased the punching shear strength of slabs, and decreased the amount of flexural reinforcements. The concentrating the top mat of flexural reinforcement increased the post-cracking stiffness, and showed better strain distribution and crack control. In addition, the use of SFRC showed beneficial effects on the punching shear strength and crack control. It was suggest that the effective width should be changed to larger than 2 times the slab thickness from the column faces.

• International Journal of Highway Engineering
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• v.17 no.2
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• pp.55-62
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• 2015

Cracking is an inevitable fact of asphalt concrete pavements and plays a major role in pavement deterioration. Pavement cracking is one of the main factors determining the frequency and method of repair. Cracks can be treated with a number of preventative maintenance actions, including overlay surface treatments such as slurry sealing, crack sealing, or crack filling. Pavement cracks can show up as one or all of the following types: transverse, longitudinal, fatigue, block, reflective, edge, and slippage. Crack sealing is a frequently used pavement maintenance treatment because it significantly extends the pavement service life. However, crack sealant often fails prematurely due to a loss of adhesion. Because current test methods are mostly empirical and only provide a qualitative measure of the bond strength, they cannot accurately predict the adhesive failure of the sealant. This study introduces a laboratory test aimed at assessing the bonding of hot-poured crack sealant to the walls of pavement cracks. A pneumatic adhesion tensile testing instrument (PATTI) was adopted to measure the bonding strength of the hot-poured crack sealant as a function of the curing time and temperature. Based on a limited number of test results, the hot-poured crack sealants have very different bonding performances. Therefore, this test method can be proposed as part of a newly developed performance-based standard specification for hot-poured crack sealants for use in the future. PURPOSES : The purpose of this study was to evaluate both the adhesion and failure performance of a crack sealant as a function of its curing time and curing temperature. METHODS: A pneumatic adhesion tensile testing instrument (PATTI) was adopted to measure the adhesion performance of a crack sealant as a function of the curing time and curing temperature. RESULTS: With changes in the curing time, curing temperature, and sealant type, the bond strengths were found to be significantly different. Also, higher bond strengths were measured at lower temperatures. Different sealant types produced completely different bond strengths and failure behaviors. CONCLUSIONS: The bonding strength of an evaluated crack sealant was shown to differ depending on various factors. Two sealant types, which were composed of different raw materials, were shown to perform differently. The newly proposed test offers the possibility of evaluating and differentiating between different crack sealants. Based on alimited number of test results, this test method can be proposed as part of a newly developed performance-based standard specification for crack sealants or as part of a guideline for the selection of hot-poured crack sealant in the future.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.6
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• pp.102-110
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• 2023

PSC-I girder bridges constitute the largest proportion among highway bridges in Korea. According to the precision safety diagnosis data for the past 10 years, approximately 41.3% of the PSC-I bridges have been graded as C. Furthermore, with the increase in the aging of bridges, preemptive management is becoming more important. Damage and deterioration to the deck and girder with a long replacement cylce can have considerable impacts on the service and deterioration of a bridge. In addition, the high rate of device damages, including expansion joints and bearings, necessitates an investigation into the influence of the device damage in the structural members of the bridge. Therefore, this study defined representative PSC-I girder bridges with single and multiple spans to evaluate heterogeneous damages that incorporate the damage of the bridge member and device with the deterioration of the deck. The heterogeneous damages increased a crack area ratio compared to the individual single damage. For the single-span bridge, the occurrence of bearing damage leads to the spread of crack distribution in the girder, and in the case of multi-span bridges, expansion joint damage leads to the spread of crack distribution in the deck. The research underscores that bridge devices, when damaged, can cause subsequent secondary damage due to improper repair and replacement, which emphasizes the need for continuous observation and responsive action to the damages of the main devices.

• Journal of Service Research and Studies
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• v.2 no.1
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• pp.47-59
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• 2012

With the rapid development of the Internet, public agencies and private companies introduced 'IT outsourcing in order to maintain and repair the information systems. Also they have utilized the SLA in order to manage it. Although IT outsourcing as a way to promote effective SLA are being introduced, the introduction of service level agreements or those introduced universal effectiveness did not demonstrate in the public agencies. The importance of outsourcing in the information systems is growing, but the increase in size of the business information, IT technology diversification, expansion of information between systems interconnection, information system operating and maintenance costs with the increase of information systems to streamline operations, increase the need for versatility is growing gradually. In this paper we investigates IT outsourcing in public agencies as a way to promote effective service level agreement(SLA) with the introduction and consideration, and through the application of SLA mutual customers and IT service organizations make a clear point of management and IT service levels and IT services for improved mind and strengthen the effectiveness of preventive activities can be seen.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.5
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• pp.94-104
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• 2013

Experiments were divided into two parts; one part is to understand the basic properties of high flowable VA/VeoVa-modified cement mortar with different polymer cement ratio (P/C) and the weight ratio of fine aggregate to cement (C:F) and the other part is to investigate the effect of surface water spread on the concrete substrate on adhesion in tension. To understand the basic performance, the specimens were prepared with proportionally mixing VA/VeoVa redispersible powder, ordinary portland cement, silica sand, superplasticizer and viscosity enhancing agent. Here, P/C were 10, 20, 30, 50 and 75% and C:F were 1:1 and 1:3. As the change of P/C and C:F unit weight, flow test, crack resistance and adhesion in tension were measured. Three specimens with good adhesion properties were selected among specimens with different P/C and C:F. The effect of surface water evenly sprayed on concrete substrate on adhesive strength is investigated. The results show that surface water on concrete substrate increases the adhesion in tension of high flowable VA/VeoVa-modified cement mortar and additionally improves the flowability compared to the non-sprayed case.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.5
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• pp.113-119
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• 2023

Most infrastructure structures were completed during periods of economic growth. The number of infrastructure structures reaching their lifespan is increasing, and the proportion of old structures is gradually increasing. The functions and performance of these structures at the time of design may deteriorate and may even lead to safety accidents. To prevent this repercussion, accurate inspection and appropriate repair are requisite. To this end, demand is increasing for computer vision and deep learning technology to accurately detect even minute cracks. However, deep learning algorithms require a large number of training data. In particular, label images indicating the location of cracks in the image are required. To secure a large number of those label images, a lot of labor and time are consumed. To reduce these costs as well as increase detection accuracy, this study proposed a learning structure based on mean teacher method. This learning structure was trained on a dataset of 900 labeled image dataset and 3000 unlabeled image dataset. The crack detection network model was evaluated on over 300 labeled image dataset, and the detection accuracy recorded a mean intersection over union of 89.23% and an F1 score of 89.12%. Through this experiment, it was confirmed that detection performance was improved compared to supervised learning. It is expected that this proposed method will be used in the future to reduce the cost required to secure label images.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.2
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• pp.124-134
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• 2013

This study investigated the effect of surface water on concrete substrate on adhesive strength in tension of very high flowable SBR-modified cement mortar. The specimens were prepared with proportionally mixing SBR latex, ordinary portland cement, silica sand, superplasticizer and viscosity enhancing agent. Polymer cement ratio (P/C) were 10, 20, 30, 50 and 75% and the weight ratio of fine aggregate to cement were 1:1 and 1:3. The specimens obtained with different P/C and C:F were characterized by unit weight, flow test, crack resistance and adhesion test. After basic tests, two mixtures of P/C=20% and 30% in case of C:F=1:1, and one mixture of P/C=50% in case of C:F=1:3 were selected, respectively. These three selected specimens were studied about the effect of surface water evenly sprayed on concrete substrate by a amount of 0, 0.006, 0.012, 0.017, 0.024g per unit area ($cm^2$) of concrete substrate surface The results show that surface water on concrete substrate increases the adhesive strength in tension of high flowable SBR-modified cement mortar and improve the flowability compared to the non-sprayed case.