• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.1
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• pp.159-168
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• 2011

In this study, we find out the feasibility of self-consolidating concrete with EP nylon fiber. Three kinds of method were used; when length of nylon fiber is differed for the experiment to investigate usability of nylon fiber with enhanced performance by dispersing-agent coating in self-consolidating concrete, when mixing in other organic fibers (polypropylene, cellulose) and in case of Binary Blended and Ternary Blended concrete mixed with different types of mineral admixtures (blast-furnace slag and fly ash). Based on the results of the experiment described above, comparison was made on the basic properties and dynamic characteristics of general fiber reinforced concrete mixed with enhanced performance nylon fiber and SCC mixed with enhanced performance nylon fiber as a Mock-up test prior to the experiment of application to the actual structure. Considering characteristics and durability of the fresh and hardened self-compacting concrete, dynamic characteristics and durability were found to be more outstanding when using nylon fiber for the mineral admixtures used, dynamic characteristics and durability were found to be more outstanding when using blast-furnace slag.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.2
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• pp.130-134
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• 2019

In this paper, a laser-based non-contact load cell is newly developed for measuring forces in prestressed concrete tendons. First, alumina particles have been sprayed onto an empty load cell which has no strain gauges on it, and the layer has been used as a passive stress sensor. Then, the spectral shifts in fluorescence spectroscopy have been measured using a laser-based spectroscopic system under various force levels, and it has been found that the relation of applied force and spectral shift is linear in a lab-scale test. To validate the field applicability of the customized load cell, a full-scale prestressed concrete specimen has been constructed in a yard. During the field test, it was, however, found that the coating surface has irregular stress distribution. Therefore, the location of a probe has to be fixed onto the customized load cell for using the coating layer as a passive stress sensor. So, a prototype customized load cell has been manufactured, which consists of a probe mount on its casing. Then, by performing lab-scale uniaxial compression tests with the prototype load cell, a linear relation between compression stress and spectrum shift at a specific point where laser light had been illuminated has been detected. Thus, it has a high possibility to use the prototype load cell as a force sensor of prestressed concrete tendons.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.3
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• pp.92-95
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• 2019

In this paper, a novel laser-based non-contact and non-destructive stress measurement technique is newly proposed for measuring stress in steel structural members. As the demand of stress monitoring in structural members is increased, various non-destructive techniques are being applied to the field of structural health monitoring. Spectroscopic techniques are non-contact technique and widely used for chemical identification of target materials. Especially, piezospectroscopic technique is a residual stress measurement technique in thermal barrier coatings. Although the piezospectroscopic technique has high possibility of measuring structural stress in steel members, the technique has been rarely applied to this field. In this paper, piezospectroscopy-based stress measurement technique is, therefore, proposed for measuring stress in steel structural member. To do that, alumina particles have been coated onto a specimen of a structural steel rod using a thermal spray coating technique. And then, an uniaxial compression test has been conducted to the specimen to collect each fluorescence spectrum under different loading conditions. Finally, the linear relation of spectral shift and applied compressive stress of the specimen has been experimentally established.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.5
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• pp.20-29
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• 2022

In this study, in order to improve the durability of the cement composite printed with the ME type 3D printer, PDMS, sodium silicate, and a surface hardener were employed. Post-treatment was performed on 3D-printed cement composite by coating after immersion, and the degree of improvement in durability was evaluated. As a result, in all evaluations, the durability performances of the post-processed specimens were improved compared to those of the plain specimens. Water absorption resistance, chloride penetration resistance, and carbonation resistance of the PDMS treated specimens were improved by 36.3 %, 77.1 %, and 50.4 % when compared to plain specimens. Freeze-thaw resistance of the specimens treated with sodium silicate was found to be the most excellent, with an average enhancement of 47.5% compared to plain specimens. It was found that PDMS was the most efficient post-treatment materials for 3D-printed cement composite. However, as suggested in this study, the post-treatment method by coating after immersion may not be applicable to cement composite structures printed with a 3D printer in field. Therefore, a follow-up study needs to be preformed on the durability enhancing materials suitable for 3D printing.

• The Journal of Pediatrics of Korean Medicine
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• v.16 no.2
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• pp.23-37
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• 2002

We have plenty of study of adults diseases, but not much has been said about children. 79 children who had visited in the weak children of Dongeui Oriental Medical Hospital from March, 2002 to October, 2002, were the respondents of the Weak Child Questionnaire. The results obtained were as follows: 1. Their symptoms have been observed with sequences of respiratory diseases, Digestive diseases, Psycho-neurological diseases. 2. Distribution of sex and ages : male 38 cases, female 41 cases. $0{\sim}6$ years 60 cases, $7{\sim}12$ years 17 cases, $13{\sim}18$ years 2 cases. 3. The texture of complexion was resulted in face color and the region of the face : whitish-2/ cases. yellowish-27 cases, darkish-22 cases, blue-2 cases, flushed face-l case. Sangeun(山根)-blue : 59 cases, a lower eyelid- dark or light brown : 54 cases. the rests of color on face region didn't mean. 4. The texture of tongue was ended in tongue state : tongue form-not plump not haggard patten(57 cases), a pricky patten(12), a map patten(7), a fissured patten(3). tongue color- pink (57 cases), red(16), light white(6). coating color- thin white(61 cases), thin yellow(l0), lack(6), deep and white(2). tongue coating substance-thin(72 cases), moisten(5), dry(1), deep(1).

• Journal of Korean Society of Industrial and Systems Engineering
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• v.42 no.3
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• pp.89-94
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• 2019

K1A1 tank commander's primary thermal sight is a device that enables tank commanders to detect, identify, aim and track the target by observing targets in all directions during day, night and in situations of smokescreen and fog through $360^{\circ}$ rotation independent from the gunner's primary thermal sight and stabilizing the line of sight even under the vibrations occurring when the tank is standstill and moving. The main function of this device is to detect and process visible and thermal images and deliver the final images to the tank commander. One of the core parts to that end is the observation window (daytime/thermal image window). This core part is mounted at the entrance of the optical path for observing the target and plays the role of making visible light during the daytime and infrared light during the night pass through the target and transmitting the resultant images to the internal optical system of the tank commander's primary thermal sight. Such core parts have been selected as depot maintenance items so that they are replaced by new parts instead of being recycled when they are subjected to maintenance in most cases. That is, the military budget is wasted because such parts are replaced by new parts despite that they can be recycled for maintenance. Therefore, this study proposed a mounting tool for polishing and coating observation windows (daytime and thermal image window) using planar polishing equipment and DLC (Diamond-Like Carbon) coating equipment. In addition, this study presented an amendment (proposal) of the Depot Maintenance Work Request (DMWR) already published to verify the performance of recycled products including the establishment of inspection standards for recycling processes.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.1
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• pp.68-74
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• 2014

Recently, concrete facility as advanced water treatment facilities is extending in the water treatment facilities according to raise awareness of pure drinking water and delicious water. For this reason, it is increased to the necessity need to make the standard and the development of waterproofing and anti-corrosion materials for concrete structures applied water treatment tank. So, related research has become active recently. However, as the limit of research focused on durability improvement of top coating material, it is insufficient to study on the adhesion strength between the concrete surface and primer. Therefore, there is to confirm the adhesion of between concrete surface and the three primers used as anti-corrosion waterproofing materials, and to investigate the properties of adhesion strength according to the condition such as dry condition, wet condition, and water pressure condition of the concrete surface in this study.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.4
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• pp.136-143
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• 2015

Galvanizing is one of the method used to solve the problem of corrosion of reinforcement in concrete structures. There few research reported in the literature regarding the effect of galvanized coating on the behavior of lap splices in concrete beams. The objective of this study was to determine whether galvanized rebar adversely affects lap splice behavior and bond strength. Concrete beams reinforced with black or galvanized rebar were tested in flexure. The test variables included the presence of galvanized rebar steel diameter, and lengths of lap splices. The study concentrated on comparing crack, failure pattern, and bond strength. The ultimate behavior of beams reinforced with galvanized rebar was not significantly different from that of black steel reinforced beams. Therefore, the test results indicated that the use of galvanizing-coated rebar had no adverse effect on behavior in lap splices of rebar compared to the use of black rebar.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.2
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• pp.117-123
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• 2013

As fiber reinforced polymer (FRP) material is appled for a curved structure such as tunnel, FRP material must has a curved shape. Until now, the curved FRP material has been producted by hand-lay-up or filament winding work. It is impossible for mass production of the curved FRP material by these methods. Also, the quality of product by these methods is lower than that by pultrusion method. New pultrusion method and equipment had been developed for production of FRP material with steady curvature. The objective of this study is to evaluate the effect of freezing and thawing on adhesion of cement concrete with coarse-sand coated FRP in repair and reinforcement of cement-concrete structure using curved FRP material.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.1
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• pp.193-202
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• 2008

This paper investigates experimentally the confining effect, strengthening capacity and rebound rate of sprayed Fiber-Reinforced-Polymer (SFRP). From the method, resin and chopped fibers are sprayed separately from the nozzle with high pressure, and then they are attached to the concrete surface, so structure could be repaired. To evaluate the strengthening effect of sprayed FRP, cylindrical specimens and beam specimens were strengthening with SFRP. As main material of FRP, glass fiber and polyester resin are used. To investigate the optimum condition of sprayed FRP, the effects of fiber length, coating thickness, fiber volume ratio and concrete strength were examined. Capacities of sprayed FRP method were also compared to the FRP sheet method. In case of the sprayed FRP, rebound rate is important parameter considering economical efficiency and constructibility, so rebound rate of was discussed. From the test results, optimum conditions of sprayed FRP were determined. SFRP method showed superior strengthening capacities than FRP sheet method.