• Advances in materials Research
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• v.8 no.3
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• pp.197-217
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• 2019

In this study, the interfacial stresses in RC beams strengthened by externally bonded prestressed GFRP laminate are evaluated using an analytical approach, based on the equilibrium equations and boundary conditions. A comparison of the interfacial stresses obtained from the present analytical model and other existing models is undertaken. Otherwise, a parametric study is conducted to investigate the effects of geometrical and material properties on the variation of interfacial stresses in damaged RC beams strengthened by externally bonded prestressed GFRP laminate. The results obtained indicate that the damage degree has little effect on the maximum shear stress, with a variation less than 5% between the damaged and undamaged RC beams. However, the results also reveal that the prestressing level has a significant effect on the interfacial stresses; hence the damaged RC beam strengthened with an initial prestressing force of 100 kN gives 110% higher maximum shear stress than the damaged RC beam strengthened with an initial prestressing force of 50 kN. The values of shear stress obtained by the analytical approach are approximately equal to 44% of those obtained from the numerical solution, while the interfacial normal stresses predicted by the numerical study are approximately 26% higher than those calculated by the analytical solution.

• Korean Journal of Acupuncture
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• v.27 no.3
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• pp.79-95
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• 2010

Objective : In this study, we try to identify the herbal formulated by Heo Im from Kyeongheombang(經驗方), and investigate its medical property. Method : Those articles referenced from Heo Im's herbal formulas in "Sauikyeongheombang(四醫經驗方)" were extracted and results were quantitatively analyzed. From extracted empirical formulas, those categorized as externally applicable formulas were grouped by several standards and their medical significance was analyzed. Results and Conclusions : 85 and 66 articles were designated to be referred from Heo(許) in "Sauikyeongheombang" and "Uibanghapbu(醫方合部)" in each category, and 263 and 155 were identified to be Heo Im formulas, respectively. Externally applicable formulas in Heo Im's empirical recipes have following characteristics. First, various methods were used by Heo Im. Second, Heo Im's empirical formulas suggest useful clinical information maximizing therapeutic effect, which is of much value, originated from his practical experiences as a clinician. Third, Heo Im's therapy favorably succeeds the tradition of Hyangyak-medicine and Empirical -medicine. From this information, Heo Im is thought to have had rich insight and experience, not only in acupuncture but also in the prescription of herbal formulas at those days.

• Journal of Industrial Convergence
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• v.20 no.6
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• pp.1-6
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• 2022

This study started with the design methodology for externally installed metal sculptures. As the scope and meaning of design grows, the concept of design is also used for externally installed sculptures, and there is a demand for a sculpture design that contains the story of the installation environment while being suitable for the surrounding environment. This concept is defined as an environmental sculpture only among formative artists. The concept of environmental sculptures is not fully known and academic research is also insufficiently performed. Therefore, in order to define externally installed sculptures as environmental sculptures, this study elaborated the concept and conditions of good design and the concept and role of environmental sculptures as a theoretical background, and classified the concepts and conditions of good design and the concepts and roles of environmental sculptures. Based on the previous theoretical studies, by utilizing the conditions of good design and the role of environmental sculptures, this study suggested that design development elements were completed as metal environmental sculptures and research works were presented. In conclusion, the design methodology for metal environmental sculptures has been presented, and various environmental sculpture design studies will continue and various paradigms of convergence environmental sculptures will be studied.

• Analytical Science and Technology
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• v.37 no.3
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• pp.189-199
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• 2024

In forensic genetics, when it is not possible to confirm an individual's identity through STR profile analysis, additional information about the individual can be obtained using DNA-based phenotypic traits estimation. Recently, various researches have been conducted on methods to determine externally visible characteristics (EVC) such as eyes, hair, and skin color. However, relying solely on such phenotypic traits information has limitations for application in East Asian regions, including Korea. In this study, in order to utilize EVC related to an individual's appearance as investigative information, SNPs related to eye shape, hair thickness, skin color, as well as baldness, body type, high myopia, facial shape, acne, and behavioral habits were explored. A total of 50 SNPs were selected, and a targeted amplicon NGS panel capable of amplifying them all at once was developed. Experimental results confirmed the allelic types and frequencies of the 50 SNPs in 14 samples. We plan to use this panel to investigate the correlation between genotype and phenotype using various samples, and to develop methods for interpreting the results.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.6
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• pp.155-163
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• 2008

Experimental study has been performed in order to investigate the behavior of RC beams strengthened with externally bonded post-tensioned CFRP (Carbon Fiber Reinforced Polymer) strips. Specimens consist of 9 small-scaled specimens with the different post-tensioning level as a main test parameter. A control specimen and specimens with simply bonded CFRP strips have been manufactured to compare the structural performances of prestressed system. From the test results, it was observed that the specimens strengthened with simply bonded CFRP strips showed debonding failure below 50% of CFRP tensile strength due to premature debonding. On the other hand, all the specimens strengthened with post- tensioned CFRP strips reached the rupture strength of the CFRP strip. The cracking and yielding loads were also increased proportionally to the post-tensioning level, but the ultimate loads were nearly equal regardless of the post-tensioning level.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.6
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• pp.147-154
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• 2008

Experimental study has been performed in order to investigate the behavior of RC beams strengthened with externally unbonded post-tensioned CFRP (Carbon Fiber Reinforced Polymer) strips using embedded or stud-type plate anchorages. Total 10 small-scaled specimens were manufactured with the different post-tensioning level and types of mechanical anchorage as a main test parameter. A control specimen and specimens with simply bonded CFRP strips were included to compare the structural performances of each system. From the test results, it was observed that the specimens strengthened with simply bonded CFRP strips showed debonding failure below 50% of CFRP tensile strength due to premature debonding. On the other hand, all the specimens strengthened with post- tensioned unbonded CFRP strips reached the rupture strength of the CFRP strip. Also, it was observed that the specimens with stud-type anchorage have equivalent strengthening performance compared with embedded-type anchorage.

• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.5 s.57
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• pp.109-120
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• 2009

This paper introduces a new method to estimate the loss of prestressing force for the externally prestressing tendon. The proposed method that combines of HGA and FEM is able to identify the lost tensile force of a externally prestressed tendon. The identification variables of the proposed method is a exteranlly prestressed tendon of tension, effective nominal diameter, mass per unit length and Rayleigh damping coefficients. First of all, a finite element model system is constructed to consider the effect of damping, and these variables are identified using inverse analysis technique - updating algorithm. Finally, throughout total 3 cases of numerical tests, the numerical propriety of the proposed method is verified. Here, it is seen that the errors in the estimated variables by the proposed method are about 1% except in the case of Rayleigh damping coefficients.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.86-93
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• 2020

The demand for maintenance in Korea infrastructure facilities constructed since the 1970s has increased significantly compared to the demand for new construction. Moreover, after the Gyeongju and Pohang earthquakes, seismic performance evaluation, repair, and retrofitting projects have been carried out. Therefore, in this study, a specimen was designed following the L-type GFRP Plate Externally Bonded Retrofit method, one among other retrofit methods. The L-type GFRP Plate was bonded to the specimen by epoxy and a washered steel nail. A four-point bending test was performed to confirm the strengthening effect of the Externally Bonded Retrofit method using an L-type GFRP Plate. The strengthening effect of the L-type GFRP plate was proven experimentally, and the behavior of the beam designed following the L-type GFRP Plate Externally Bonded Retrofit method was evaluated according to Korea's "Design Manual & Specification for Strengthening of RC Structures by Advanced Composites System". Furthermore, the effectiveness of the bonding method, a combination of epoxy and washered steel nail, was also checked. The results showed that the design, according to the guidelines mentioned above, predicted the strength of the member well, but the failure mode did not satisfy the design assumption because of unexpected damage to the GFRP plate due to the fixing method, washered steel nail.

• Journal of the Korea Concrete Institute
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• v.20 no.6
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• pp.765-772
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• 2008

For RC structures, long-term deformation occurs due to the inherent characteristics, which are creep and shrinkage. In terms of serviceability, it is important to limit deflection caused by the deformation to the allowable deflection. In the recent years, various repair and strengthening methods have been used to improve performance of the existing RC structures. One of the typical methods is FRP externally bonded method (EBR). Fiber reinforced polymer (FRP) has been used worldwide as repair and strengthening materials due to its superior properties. Besides, it has to offer improved strengthening performance not only under instantaneous load but sustained load. Therefore, accurate prediction method of deflection for the RC members externally bonded with FRP under sustained load is required. In this paper, three beams were fabricated. Two beams were externally strengthened with one of CFRP plate and GFRP plate respectively. Total three beams were superimposed under sustained load of 25 kN. During 470 days, deflections at midspan were obtained. Moreover, creep coefficients and shrinkage strains were calculated by using ACI-209 code and CEB-FIP code. In order to predict the deflection of the beams, EMM, AEMM, Branson's method and Mayer's method were used. Through the experiment, it was found that the specimen with CFRP plate has the most flexural capacity and Mayer's method is the most precise method to predict total long-term deflections.

• Journal of Animal Science and Technology
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• v.54 no.1
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• pp.43-49
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• 2012

This study was carried out to investigate the effects of age of laying hens and grade of shell abnormality on internal egg quality. At each week, 1,000 eggs were randomly selected from 21,000 eggs laid by Hy-Line hens (100,000 birds) aged from 56 to 62 wk. The samples were divided into normal and externally abnormal eggs by an official egg grader. Then, egg quality including egg weight, egg white height, Haugh unit and yolk color was evaluated from each normal and abnormal eggs. The production rate of externally normal and abnormal eggs was 81.22 and 18.78%, respectively. No difference found in the production rate by the increase of hen's age, but Haugh unit of eggs from hens of 60-wk-old was higher (p<0.05) than that of 56-wk-old. When the same age groups were compared, egg white height and Haugh unit were lower in eggs which were externally abnormal. When the grade of abnormality increased, egg white height and Haugh unit were decreased further (p<0.05). Among the externally abnormal eggs, malformation showed the lowest Haugh unit. In conclusion, the shell abnormality of eggs laid by hens aged 56 to 62 wk was closely related with internal egg quality. Therefore, the grading external egg quality in the present egg grading system is directly related with the internal egg freshness.