• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.5
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• pp.51-58
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• 2014

This paper presents a fire exposure test result to evaluate fire resistance capacity of retrofit method using FRP (Fiber Reinforced Polymer) in reinforcement concrete structure. Especially, this paper focused on near-surface-mounted retrofit method; FRP is mounted into the groove after making a groove in concrete. In the test, main parameters are retrofit method and materials for fire proofing. Spray type of perlite and board type of calcium silicate were considered as external fire proof on surface while particle of calcium silicate and polymer mortar as internal one in groove. By increasing the temperature of inside heating furnace, the transfer of temperature from surface of fire proofing material to groove in specimen was measured. As a result, fire proofing using the board of calcium silicate was more effective to delay the heat transfer from outside than spraying with perlite. It was found that the fire proofing could resist outside temperature of $820^{\circ}C$ at maximum to keep the temperature of epoxy below glass transit temperature (GTT).

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.6
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• pp.112-121
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• 2013

FRP reinforced lightweight concrete structures can offer corrosion resistance and weight reduction effect simultaneously, so practical use of the structures may be expected afterwards. But to make concrete structures using lightweight concrete and FRP bar, that can resist external forces without internal slip of the FRP bar, it is very important to understand bond characteristic between lightweight concrete and FRP bar. During that time, a lot of studies for bond behaviors of FRP bar in normal concrete were conducted, but studies for bond behavior of FRP bar in lightweight concrete are very limited to date. So, bond characteristic between lightweight concrete and helically deformed GFRP bar was investigated in this study. Three main parameters were considered in experimental investigation: type of rebar, concrete type, and compressive strength of lightweight concrete. As an experimental result, it could be known that bond strength of helically deformed GFRP bar in lightweight concrete was 0.49 times bond strength of steel reinforcement in normal concrete.

• Korea Journal of Hospital Management
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• v.11 no.1
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• pp.54-90
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• 2006

Medical clinics are core institutes that cover the primary medical care in Korea. Financial viability of the clinics is essential for them to conduct their roles and functions, and can be improved by increasing their operating profitability. On this ground, this study aimed at finding important factors that affect the operating profitability, and thereby at suggesting strategic alternatives that can contribute to the improvement of the profitability. Operating margin was set as a dependent variable, and such factors as general management conditions, number of visits, medical revenue, marketing activities, input resources, medical cost as independent variables. Nineteen hypotheses related to the variables were established and tested using data collected from 138 sample clinics for the year 2003. The results of the study are as follows : Firstly, such variables as percent ratio of the depreciation plus rent costs to total administration costs, type of clinical department manifested whether medical, surgical, or quasi-surgical, percent ratio of the interior facility investment to total fixed assets, and total number of outpatient visit are important factors that affect, positively or negatively, the medical profitability of the clinics. Secondly, following measures are needed to be established and implemented to improve the medical profitability. (1) Administration costs share 53.2% of the total medical costs, and depreciation plus rent costs 16.3% of the total administration costs. This implies that such measures as reinforcement of marketing activities, establishment of the cooperative utilizing system of the facility and equipment, or group practice are needed to increase cost-effectiveness. (2) Occupancy rate of the clinics with inpatient bed is as low as 45.5%, causing high fixed costs and low medical profitability. For its improvement, the resource input structure should be reorganized. Thirdly, in the future, a study that can increase sample representativeness of the study and explanation power of the variables should be performed for each type of clinical department to find more specific determinant factors and to contribute to the improvement of the medical profitability of the clinics.

• Journal of the Korea Concrete Institute
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• v.17 no.6 s.90
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• pp.879-884
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• 2005

The setting time is a very important factor affecting the quality of tunnel lining and reinforcement of inclined slope etc. Currently, however, the quality criteria of accelerating admixture to improve it is not established well. In this study, evaluation on setting time measuring methods of cement mixed a accelerating admixture (AA) was performed using Gillmore and Vicat needle test methods. For both test methods, the setting time for addition at a time was better than post addition regardless of initial setting and final setting. For Gillmore needle test method, two types of measuring methods were selected and it is noted that setting time with cement type under the same accelerating admixture can be different. Accordingly, manufacturing company shall develop a less sensitive accelerating admixture to cement type. For Vicat needle test method, six types of measuring methods were used and a proper measuring method of the admixture were proposed as follows: (1) the temperature of materials used shall be controlled exactly and (2) to evaluate its properties, an admixture usage of $5\%$ (ratio of cement weight) is recommended.

• Structural Engineering and Mechanics
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• v.74 no.3
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• pp.395-406
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• 2020

Many prefabricated concrete frame joints have been proposed, and most of them showed good seismic performance. However, there are still some limitations in the proposed fabricated joints. For example, for prefabricated prestressed concrete joints, prefabricated beams and prefabricated columns are assembled as a whole by the pre-stressed steel bar and steel strand in the beams, which brings some troubles to the construction, and the reinforcement in the core area of the joints is complex, and the mechanical mechanism is not clear. Based on the current research results, a new type of fabricated joint of prestressed concrete beams and confined concrete columns is proposed. To study the seismic performance of the joint, the quasi-static test is carried out. The test results show that the nodes exhibit good ductility and energy dissipation. According to the experimental fitting method and the "fixed point pointing" law, the resilience model of this kind of nodes is established, and compared with the experimental results, the two agree well, which can provides a certain reference for elasto-plastic seismic response analysis of this type of structure. Besides, based on the analysis of the factors affecting the shear capacity of the node core area, the formula of shear capacity of the core area of the node is proposed, and the theoretical values of the formula are consistent with the experimental value.

• Journal of the Architectural Institute of Korea Planning & Design
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• v.34 no.3
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• pp.105-116
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• 2018

POPS(Privately Owned Public Spaces) is one of the major component that vitalize the city by private sectors providing open-spaces to the public. It holds great significances and possibilities within CBD(Central Business District) which lack open-space and green-space. Despite of its importance, a large number of problems such as deficient accessibility for the public and being unpractical from constructing only with formality occur in existing POPS. POPS should be for both owners and public because it is a public space located within a private estate. To vitalize POPS, functions like "diversity", "accessibility and connectivity", and "usability" are essential. Providing diverse types of spaces makes dynamic city, and the spaces must have easy access by public and variety of functions. Managements by diverse types of POPS are necessary to improve availability and to provides suitable spaces. To make diverse types of POPS, advanced classifications of type and clear criteria are required. From aspect of accessibility and connectivity, firstly detailed instructions for the arrangement are necessary for reinforcement. Specific research on means of connection such as how many faces of POPS should adjoin streets and in which direction it should be facing should be applied. Purposes of POPS must be specified depending on the type of POPS. By connecting adjacent buildings with POPS, one of the main principal of vitalizing POPS, inflow of people can be increased. Accordingly, improvements of design guidelines in "diversity", "accessibility and connectivity", and "usability" can be suggested to vitalize POPS. With these concerns in mind, this paper analyzes problems of current Seoul POPS guidelines with three aspects.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.5
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• pp.811-816
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• 2022

Even though continuous management and supervision of reinforcement of policies to safeguard accidents at workplace and work sites were implemented. Accident prevention activities such as inspection and diagnosis are urgently required to induce a preliminary investigation to identify the risk factors for each type of work, before the work task to eliminate risks at the worksites. Since safety inspections at work sites were generally conducted through visual inspections, the results of safety inspections may vary depending on the findings and proficiency of the safety officers. The results of those inspections may have loopholes to prevent potential accidents at work. Therefore, the purpose of this study was to develop a risk identification checklist that can effectively perform safety inspections to prevent accidents at work sites. This study initially analyzed the previously developed accident checklist to identify current complications and issues in safety checklists. Based on the findings of major industrial accidents over the past three years, the relationship between accident, workplace, and work type were analyzed refereeing the safety inspection standards. A risk recognition-checklist was developed to provide basic data on identifying risk factors, and inspection guidance at work sites. To prepare for potential accidents by identifying and taking countermeasures to mitigate the high risk and serious accidents at sites by the guidelines of the checklist. The developed inspection checklist has been practically used by experts at work sites to perform safety inspections, and it has been verified its suitability, and feasibility, to prevent or mitigate workplace accidents, including securing the safety and health of field workers. The role of the developed safety checklist has been considered effective at worksites.

• Journal of the Korea Society of Computer and Information
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• v.28 no.10
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• pp.171-178
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• 2023

In this paper, we propose a smart automated warehouse to maximize space utilization. Previous elevator-type automatic warehouses were designed with a maximum payload of 100kg on trays, which has the problem of extremely limiting the number of pallets that can be loaded within the space. In this paper, we design a smart warehouse that can maximize space utilization with a maximum vertical stiffness of 300kg. As a result of the performance evaluation of the implemented warehouse, the maximum payload was 500.6kg, which satisfied the original design and requirements, the lifting speed was 0.5m/s, the operating noise of the device was 67.1dB, the receiving and forwarding time of the pallet was 36.92sec, the deflection amount was 4mm, and excellent performance was confirmed in all evaluation items. In addition, the PLC control method, which designs the control UI and control panel separately, was integrated into the PC system to improve interoperability and maintainability with various process management systems. In the future, we plan to develop it into a fully automatic smart warehouse by linking IoT sensor-based logistics robots.

• Journal of The Korean Society of Agricultural Engineers
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• v.66 no.1
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• pp.39-48
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• 2024

Plastic greenhouses are simple structures consisting of lightweight materials such as steel pipes and polyvinyl chloride. However, serious damage occurs due to heavy winds and typhoon every year. To prevent a collapse of structural members, the Ministry of Agriculture and Rural Development has distributed plans and specifications for disaster-resistant standards. Despite these efforts, more than 50% of greenhouses still do not satisfy the disaster-resistant standards. Among the greenhouses that do not meet these standards, 85% are single-span greenhouses proposed 20 years ago. Consequently, there is a need to evaluate the safety of wind loads for the single-span greenhouse. Unfortunately, there are no design specifications for the greenhouses under wind loads. Therefore, a Korean design standard (KDS) has been utilized. KDS is defined with reference to wind speeds occurring once every 500 years, raising concerns about potential overdesign when considering the durability of plastic greenhouses. To address this, the modified wind load, considering the durability of the plastic greenhouse, was calculated, and a safety evaluation was conducted for sigle G-type plastic greenhouse. It was observed that the moment acting on the windward surface was substantial, and there was a risk of the foundation being pulled out if the basic wind speed exceeded 32 m/s. In terms of the combination strength ratio, it was less than 1.0 only on the leeward side when the basic wind speed was 24 m/s and 26 m/s. However, in all other cases, it exceeded 1.0, indicating an unsafe condition and highlighting the necessity for reinforcement.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.2
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• pp.139-148
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• 2008

The direct inspection of the outward aspects by field engineers is the important and critical part for structural safety assessment according to the related reports. This study presents an improved method of the state assessment for concrete floor slab by separating and evaluating the individual damage types. First, the various types of damage symptoms are separated, which have been included and dealt in a group. Secondly, they are weighted and scored independently based on the present guide and references. Overall procedures other than the above are retained as same as possible to avoid the confusion. The proposed method is applied and tested to a performed assessment project for a bridge for validation. The result shows that it is reasonable and applicable in respect that it is able to make up for the controversial points of the present guide revealed in practices. Careful check of excessively deteriorated parts in addition to the reasonable assessment of system by this method grants the structural repair and reinforcement propriety and economy, and assures of more safety. Twofold appraisal of this approach expands the applicable areas of value engineering to the structural maintenance.