• Journal of the Korea Concrete Institute
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• v.15 no.2
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• pp.234-245
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• 2003

Most of the concrete bridge structures are exposed to damage due to the excessive traffic loading and the aging of the structure. The damage of concrete causes the further deterioration of the function in the concrete structure due to corrosion of the reinforced bars and decohesion between the concrete and the reinforced bar. The quick rehabilitation of the damaged concrete structures has become of great importance in the concrete structural system in order to avoid the further deterioration of the structures. Recently fiber sheets are used for strengthening the damaged concrete structures due to its many advantages such as its durability, non-corrosive nature, low weight, ease of application, cost saving, control of crack propagation, strength to thickness ratio, high tensile strength, serviceability and aesthetic. However, the lack of analytical procedures for assessing the nominal moment capacity by the fiber sheet reinforcement leads to difficulties in the effective process of decisions of the factors in the strengthening procedure. In this work, flexural strengthening effects by fiber sheets bonded on bottom face of the member are studied for the reinforced concrete T beam. In addition, auxiliary flexural strengthening effects by U-type fiber sheets bonded on bottom and side faces of the member to prevent delamination of the bottom fiber sheet are theoretically investigated. The analytical solutions are compared with experimental results of several references to verify the proposed approach. It is shown that the good agreements between the predicted results and experimental data are obtained.

• The Journal of the Korea Contents Association
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• v.10 no.3
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• pp.454-462
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• 2010

The current curriculum in the 7th informatics, which simply highlights the use of applied programs rather than enhancing creativity through learning several principles in information science and thus making it hard to have optimism on the future as a powerhouse in IT. By diagnosing these problems, Education Ministry revised the existing curriculum to have a more scientific access to the informatics. However, the curricular revision fails to meet the needs of learners sufficiently because it tends to put the considerations of theoretical specialists before the learners them selves. This paper compares and analyzes the overall understanding of learners on informatics, current-curriculum and 7th revised curriculum and that of college-level, thus offering the student-centered one. Also, the research tries to bridge the opinion gap between developer and learner by looking into the understanding level of university majors about the current curriculum. In doing so, thesis may provide the basis on exploring new approaches and contribute to establishing 7th revised curriculum in school.

• The Journal of Art Theory & Practice
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• no.7
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• pp.165-188
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• 2009

In the development of linear perspective, Brook Taylor's theory has achieved a special position. With his method described in Linear Perspective(1715) and New Principles of Linear Perspective(1719), the subject of linear perspective became a generalized and abstract theory rather than a practical method for painters. He is known to be the first who used the term 'vanishing point'. Although a similar concept has been used form the early stage of Renaissance linear perspective, he developed a new method of British perspective technique of measure points based on the concept of 'vanishing points'. In the 15th and 16th century linear perspective, pictorial space is considered as independent space detached from the outer world. Albertian method of linear perspective is to construct a pavement on the picture in accordance with the centric point where the centric ray of the visual pyramid strikes the picture plane. Comparison to this traditional method, Taylor established the concent of a vanishing point (and a vanishing line), namely, the point (and the line) where a line (and a plane) through the eye point parallel to the considered line (and the plane) meets the picture plane. In the traditional situation like in Albertian method, the picture plane was assumed to be vertical and the center of the picture usually corresponded with the vanishing point. On the other hand, Taylor emphasized the role of vanishing points, and as a result, his method entered the domain of projective geometry rather than Euclidean geometry. For Taylor's theory was highly abstract and difficult to apply for the practitioners, there appeared many perspective treatises based on his theory in England since 1740s. Joshua Kirby's Dr. Brook Taylor's Method of Perspective Made Easy, Both in Theory and Practice(1754) was one of the most popular treatises among these posterior writings. As a well-known painter of the 18th century English society and perspective professor of the St. Martin's Lane Academy, Kirby tried to bridge the gap between the practice of the artists and the mathematical theory of Taylor. Trying to ease the common readers into Taylor's method, Kirby somehow abbreviated and even omitted several crucial parts of Taylor's ideas, especially concerning to the inverse problems of perspective projection. Taylor's theory and Kirby's handbook reveal us that the development of linear perspective in European society entered a transitional phase in the 18th century. In the European tradition, linear perspective means a representational system to indicated the three-dimensional nature of space and the image of objects on the two-dimensional surface, using the central projection method. However, Taylor and following scholars converted linear perspective as a complete mathematical and abstract theory. Such a development was also due to concern and interest of contemporary artists toward new visions of infinite space and kaleidoscopic phenomena of visual perception.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.6
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• pp.730-736
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• 2014

Test standards for electrical and electronic equipment required for ship operations is applying the IEC-60533 standard. However, although a test procedure and a specified regulation are clearly defined in the deck and bridge zone and general power distribution zone, they are not regulated in the special power distribution zone with ship propulsion system. For these reasons, the costs for additional research and development have been invested. In this paper, we was measured power noise in a special power distribution zone in ship and we were compared and analyzed values measured. The actual experiments are performed on the ship of Korea Maritime and Ocean University. As a result, the acquired data on Hanbada shows that loop antenna with low frequency band(160kHz) and ultra log antenna with high frequency band(1.97GHz)occur about 6-8dB differences and about 8.7 difference respectively. Also, the acquired data on Hannara shows that each loop antenna of 1MHz, 11MHz, and 25MHz occurs about 7dB difference about 4-5dB differences respectively. so standard of Special distribution zone must be specified by comparative analysis of data obtained by the experiment more.

• Journal of Wetlands Research
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• v.6 no.1
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• pp.167-178
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• 2004

The southern tidal flat of Kanghwa Island is one of the biggest flats on the west coast of Korea. Tide is typically a semidiurnal with maximum range of about 10m. The tidal flat receives large amount of sediments from Han River system. Surface sediments for sedimentary analyses were sampled at 83 stations in the study area in August 2003. The surface sediments consisted of five sedimentary facies. Generally, sandy mud sediments dominated in the southern tidal flat of Kanghwa Island, whereas sand sediments dominated in channel and subtidal zones of the western part of Kanghwa Island. The area of sandy mud sediment extended to eastward tidal flat compared to sedimentary facies in August 1997. Sedimentary facies analysis of three core sediments from the tidal flat to the south of the Kangwha Island revealed three sedimentary facies: trough-cross-bedded sand, laminated silt, and bioturbated silt. Distribution of the facies in the cores suggested that sedimentation rates has been generally high in the margin of main tidal channel, especially in the east of the Donggeum Island. Twelve-and-half-hour anchoring survey was carried out for measurements of hydrodynamic parameters at Yeomha channel near Choji Bridge(K1) and channel near Donggeum Island(K2) in June 2003. Residual flows indicated strong ebb-dominated tidal currents. Depth-integrated net suspended sediment loads for one tidal cycle were seaward movement with 309,217.9kg/m and 128,123.1kg/m at station K1 and K2, respectively. The higher value of net suspended sediment loads at station K1 suggested that lots of suspended sediments from Han River deposited in the eastern part of tidal flat.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.3
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• pp.10-17
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• 2016

This paper presents a laboratory validation of a new approach for Finite Element Model Updating(FEMU) on short-span bridges by combining ambient vibration measurements with static load input-deflection output measurements. The conventional FEMU approach based on modal parameters requires the assumption on the system mass matrix for the eigen-value analysis. The proposed approach doesn't require the assumption and even provides a way to update the mass matrix. The proposed approach consists of two steps: 1) updating the stiffness matrix using the static input-deflection output measurements, and 2) updating the mass matrix using a few lower natural frequencies. For a validation of the proposed approach, Young's modulus of the laboratory model was updated by the proposed approach and compared with the value obtained from strain-stress tests in a Universal Testing Machine. Result of the conventional FEMU was also compared with the result of the proposed approach. It was found that proposed approach successfully estimated the Young's modulus and the mass density reasonably while the conventional FEMU showed a large error when used with higher-modes. In addition, the FE modeling error was discussed.

• Journal of Korean Society of Steel Construction
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• v.9 no.4 s.33
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• pp.489-500
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• 1997

The number of railway bridges in Korea reaches to about 3,000. Among them, the ratio of steel bridges is about 47%. Most of the long span railway bridges take the truss type, its number is 15 in Korea. These bridges have more than 30 years service life, it is expected that the damages of cracks and corrosion is going. Therefore, the estimation of fatigue life with random stress is considered as significant subject in maintenance. In this paper, the random stress was measured in bridges and counted the stress cycles using the rainflow counting method So, the stress range frequencies and their equivalent stress are obtained and the amplification factor for the span length, bridge types and traveling speed is assessed by the dynamic testing. From the results, the stress range of the stringer and the lower chord is higher than the other members and the characteristics of the stress histogram is varied to the loading system and the amount of the passing through trains. And the impact effects are depended on the traveling speed as well as the span length.

• Journal of Korean Society of Steel Construction
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• v.23 no.6
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• pp.747-761
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• 2011

This paper presents an investigation on the change in the statical behavior and the ultimate capacity of steel cable-stayed bridges after cable failure. Cable failure can occur due to fire, direct vehicle clash accidents, cable or anchorage fatigue, and so on. Moreover, the cable may be temporarily disconnected during cable replacement work. When cable failure occurs, the load, that was supported by the broken cable is first transferred to another cable. Then the structural state changes due to the interaction between the girder, mast, and cables. Moreover, it can be predicted that the ultimate capacity will decrease after cable failure, because of the loss of the support system. In this study, the analysis method is suggested to find the new equilibrium state after cable failure based on the theory of nonlinear finite element analysis. Moreover, the ultimate analysis method is also suggested to analyze the ultimate behavior of live loads after cable failure. For a more rational analysis, a three-step analysis procedure is suggested and used, which consisted of initial shape analysis, cable failure analysis, and live load analysis. Using this analysis method, an analytical study was performed to investigate the changes in the structural state and ultimate behavior of steel cable-stayed bridges.

• Journal of Korean society of Dental Hygiene
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• v.8 no.4
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• pp.153-163
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• 2008

The purpose of this study was to investigate the quality of life of clients who treated and equipped prosthesis in Eulji University Hospital in Dae-Jun City. The results of this study were as follows. The oral status of Female had more carious tooth than male had. Carious tooth(p<0.05) and losed tooth(p<0.001) was more popular in older female. The frequency of treated tooth was higher under 59 years old female than over 60 years old(p<0.01). In education category, carious tooth(p<0.05) and losed tooth(p<0.000) was more popular in low education than high education In the score of relation of OHIP-14 category and general characteristic, female was significantly higher than male in dysfunction( p<0.05), physical disorder(p<0.001) and activity disorder(p<0.05). The score was significantly higher in older than younger in dysfunction(p<0.05), physical disorder(p<0.001) and activity disorder(p<0.001). The score of education was significantly higher in low education group than high education group in physical pain (p<0.001), mental discomfort (p<0.001). The score of marriage status was significantly higher in marriaged group than other group in dysfunction (p<0.05) and mental discomfort (p<0.05). In the score of relation of OHIP-14 category and oral status, the score of carious tooth group was significantly higher in dysfunction(p<0.05), physical disorder(p<0.05) and activity disorder(p<0.05). The score of losed tooth group was significantly higher in dysfunction(p<0.05), physical pain (p<0.05), mental discomfort(p<0.05), physical disorder(p<0.05) and activity disorder(p<0.01). The score of non treated tooth group was significantly higher in dysfunction(p<0.05), mental discomfort(p<0.05), social disorder(p<0.05) and activity disorder(p<0.05). In the score of relation of OHIP-14 category and the sort of prosthesis, the score of being bridge group was significantly higher than being crown group in activity disorder(p<0.05). The OHIP-14 category and the number of prosthesis was not significant relationship. These results suggest that the information and services of the process of dental prosthesis based on subjective evaluation should be provided to clients rather than based on clinical evaluation. The continued system of oral management should be developed and provided.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.3
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• pp.92-103
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• 2015

Development of new concrete bridge deck system with FRP plank using as a permanent formwork and the main tensile reinforcement recently has been actively conducted. Concurrent use as a reinforcing material and a permanent formwork, it is possible to reduce the construction time and construction costs than the usual concrete slab. In this study, an experiment was carried out for the bond stress between cast-in-place concrete and the type of FRP plank using as a permanent formwork. The interfacial fracture energy that can be one of the most important parameters were evaluated for adhesion performance and bond stress to know the characteristics of the failure mechanism of the adhesion surface. Interfacial fracture energy of normal concrete is 0.24kN/m of GF11 case, in the case of GF21, 0.43kN/m appears, in the case of CF11 and GF31, 0.44kN/m and 0.46kN/m respectively it appeared. In case of RFCON, 0.52kN/m appears from GF12, the CF12 and GF22, 0.51kN/m and 0.36kN/m appeared each case.