• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.6
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• pp.166-174
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• 2011

The object of this study is to evaluate the structural shear capacity of the PC girder-PC beam joint. The dapped end of PC beam and the ledger of PC girder are usually designed to design load. If the end of PC beam can be designed with continuous end, the dapped end of PC beam and the ledger of PC girder do not need to resist to all loads except dead load and construction load. The experimental program was carried out with 7 specimens containing the variable factors as the anchored method of the hanger bar, design load, be or not exist of ledger bars. As a result, the continuity of the dapped end and the ledger were ensured their safety although the design load was only the dead load and the construction load. The shear critical section was expanded toward the effective depth d, the distance from the supported position of the beam. If the ledger is designed according to PCI Design Handbook, the structural system of the ledger is as to the cantilever slab system. But the ledger of this study is as to the 3 side fixed slab system. Therefore the design of the ledger by PCI Design Handbook will lead to highly conservative results.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.3
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• pp.130-137
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• 2017

The purpose of this study is to provide a reasonable analytical method for the reinforced concrete beams which shows failure mode of shear and flexure-shear by proposing a modified formulation to consider the effect of shear deformation on the beam-column fiber element based on the flexibility method and a new constitutive law of inelastic shear response history for the section. A total of 6 specimens of reinforced concrete beams which is designed to cause shear failure before yielding longitudinal reinforcement to investigate the influence of the main experimental variables on the shear behavior characteristics and the analysis was performed by using a non-linear finite element analysis program (RCAHEST) applying the newly modified constitutive equation by the authors. The failure mode and the overall behavior characteristics until fracture are predicted appropriately for all specimens and the results are expected to be useful enough for the 3 - D analysis to carry out reliable results of large-scale and complicated structures in the future.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.22 no.6
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• pp.374-386
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• 2010

Recently, the theoretical and experimental research is being made actively in control character of waves of perforated-wall caisson breakwater like the slit caisson. This study showed that the character of reflection coefficient and the wave pressure acting on the front and inner of slit caisson were estimated in two and three dimensional numerical wave flume and compared each other. The numerical experiment was set and conducted by various cases as to a variety of wave steepness under 7 sec, 9 sec, 11sec and 13 sec period condition. In this study using a 2 and 3 dimensional numerical wave flume, it applied the Model for the immiscible two-phase flow based on the Naveir-Stokes Equations. This technique can easily reproduce a complicated physical phenomenon more than others and organize the program simply. According to the results of the experiment, the reflection coefficient was estimated high in short-period waves. However, 2-dimensional numerical experiment and 3-dimensional numerical experiment were the same in case of the long-period waves and high wave steepness. And to conclude in case of short-period waves the pressures were a relatively small difference between the two, but there was a big gap in longperiod waves and high wave steepness.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.30 no.1
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• pp.10-18
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• 2018

Recently, a port city has been gradually expanding near coastal area, and many facilities for tourism and waterfront have been constructed near the shore. When storm surge developed by typhoon have occurred, coastal facilities have a lot of damage and failure with loss of life caused directly by the waves. Various barriers have been suggested to protect property and human life from disasters, they have not been widely applied though. Because they do not satisfy the recent trends that emphasize the surrounding scenery. In this study, a moveable barrier on revetment is proposed against wave overtopping. This moveable barrier has two function, sightseeing and protecting. In case of usual day, it is installed on the revetment and used observatory deck for sightseeing. When wave overtopping has occurred by storm surge, it protect coastal area through changing of flat deck to triangular barrier. The hydraulic and the structural performance of the newly proposed movable barrier was investigated through numerical analysis using commercial program. As a results, this structure has numerically good performance, and follow-up research is required through experimental tests though.

• Journal of Korean society of Dental Hygiene
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• v.6 no.4
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• pp.455-467
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• 2006

Demand for appropriate health care has gradually increased in Korea. In addition, developments of community- and school-based oral health programs have also focused oral health care for the oral health promotion. Especially, school-based oral health programs are the underpinnings of promoting oral health and preventing oral diseases among schoolchildren. School-based oral health programs have had three major components: oral health education, oral health services, and a healthful environments. These included oral health education(one-to-one communication, group communication, and use of mass communication), oral examination, fluoride mouthrinsing, pit-and-fissure sealants, fluoride gel application, mechanical plaque control, and chewing xylitol candy. In this study, we evaluate the effects of oral health programs among primary schoolchildren by comparing the oral health knowledge, oral health behaviors, and perception of caries prevention procedures. Data for this study were obtained from 699 primary schoolchildren at the two primary school in Daegu, Korea. One is experimental group, N primary school, that was established school-based oral health center under supervision of Nam-gu Public Health Center, the other is control group, N' primary school, that was yet to establish school-based oral health center. We surveyed children's oral health knowledge and behaviors, and perception of caries prevention procedures using self-administrated questionnaire and then analyzed differences of each item among two groups. The brief findings of this study were summarized as follows. There are several advantage to a comprehensive school-based oral health program. (1) School-based oral health programs facilitate and increase the effectiveness of teaching oral health subjects. (2) Schoolchildren are available for prevention or treatment procedure. (3) School-based oral health center may be less threating than private dental clinic. (4) With comprehensive school-based oral health programs the decayed, missing, and filled teeth(DMFT) of schoolchildren should demonstrate a substantial and steady decrease over time(Choi et al, 2004). In conclusion, treatment is not the answer to solving children's oral health programs; rather primary prevention is the key. Many countries and communities are focusing on hoe millions of underprivileged children can be provided with health care. Schoolchildren gain the knowledge and behaviors to attain and maintain good oral health in schools. For these reasons, the role of school-based oral health center is not only important but also a necessity.

• Journal of Biosystems Engineering
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• v.26 no.5
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• pp.461-468
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• 2001

Impact between fruits and other materials is a major cause of product damage in harvesting and handling systems. The oriental pears are more susceptible to bruising than other fruits such as European pears and apples, and are required more careful handling. The interest in the handling of the pears for the processing systems has raised the question of the allowable drop height to which pears can be dropped without causing objectionable damage. Drop tests on pears were conducted using an impact device developed by authors to estimate the allowable drop height without bruising. The impact device was constructed to hold in a selected orientation and to release a fruit by vacuum for dropping on to a force transducer. The drop height was adjustable for zero to 60 cm to achieve the desired distance between the bottom of the fruits and the top of the impact force transducer. The transducer was secured to 150 kg$\sub$f/ concrete block. The transducer signal was sampled every 0.17 ms with a strain gage measurement board in the micro computer where it was digitaly stored for later analysis. The selected sample fruit was Niitaka cultivar of pears which is one of the most promising fruit for export in Korea. The pears were harvested during the 1998 harvest season from an orchard in Daejeon. The sample fruit was selected from two groups which were stored for 3 months and 5 months respectively by the method of current commercial practice. The pears were allowed to stabilize at environmental condition(18$^{\circ}C$, 65% rh) of the experimental room. One hundred fifty six pears were tested from the heights of 5, 7.5. 10 and 12.5 cm while measurement were made of impact peak force, contact time, time to peak force, dwell time, pear diameter and mass. The bioyield strength and modulus of elasticity were measured using UTM immediately after each drop test. The allowable drop height was estimated on the base of bioyield strength of the pears in two ways. One was assumed the peak force during impact test increasing linearly with time, and the other was based on the actual drop test results. The computer program was developed for measuring the impact characteristics of the pears and analyzing the data obtained in the study. The peak force increased while contact times decreased with increasing drop height and contact times of the sample from the hard tissue group. The allowable drop height increased with increasing bioyield strength and contact times, and also varied with Poisson\`s ratio, mass and equilibrium radius of the pears. The allowable drop height calculated by a theoretical method was in the range from 1 to 4 cm, meanwhile, the estimated drop height considering the result of the impact test was in the range from 1 to 6 cm. Since the physical properties of fruits affected significantly the allowable drop height, the physical properties of the fruits should be considered when estimating the allowable drop height.

• Applied Biological Chemistry
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• v.51 no.1
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• pp.11-16
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• 2008

The extraction conditions for resveratrol production from grape fruit stem, which is a by-product of grape processing, were optimized to develop high-functional grape-based products. Additionally, the bioefficacy of grape fruit stem extract (GFSE) as an antioxidant agent was evaluated. Resveratrol was extracted using various experimental conditions such as extractant type, extractant concentration, raw material-extractant ratio, extraction time and temperature, and the results were analyzed using a statistical program (SPSS). The resveratrol yield was the highest when 80% ethanol with a raw-material-extractant ratio of 1:10 (w/v) was used. In addition, the optimal temperature and time were selected as $60^{\circ}C$ and 90 min, respectively. When the antioxidant activity was analyzed and expressed as DPPH radical scavenging activity and SOD-like activity, the antioxidant activity of GFSE was higher than that of BHT, BHA and L-ascorbic acid. Finally, it was found that GFSE could be used as a raw material for the production of high antioxidant agents.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.6
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• pp.4098-4107
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• 2015

The purpose of this study was to investigate the effects of 8-week schroth 3-dimensional exercise and ball-sling complex exercise treatment on cobb's angle, abdominal muscle endurance, flexibility and balance in adolescents with idiopathic scoliosis. Thirty subjects with scoliosis were random assignment into one of two experimental groups, either schroth treatment(n=15) or ball-sling complex exercise treatment(n=15). Exercise program was to perform for 8-week and 90min and 3 times per week. The results of this study were as follows; First, cobb's angle was significantly decreased after 8-weeks in schroth treatment(p<.001). And also abdominal muscle endurance(p<.05), flexibility(p<.001) and balance(p<.001) were significantly improve in pre vs. post treatment. Second, the ratio of cobb's angle change was significantly higher in schroth treatment compared to ball-sling complex exercise treatment following 8-weeks(p<.05). These results suggest that although both the schroth treatment and bal-sling complex exercise treatment in adolescents with idiopathic scoliosis can improve on cobb's angle, abdominal muscle endurance, flexibility and balance, but schroth treatment was better than ball-sling complex exercise treatment improving effect of cobb's angle. Therefore, we consider that schroth treatment has more effect of prevention and therapy in idiopathic scoliosis in adolescents.

• Journal of KIISE
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• v.43 no.1
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• pp.87-95
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• 2016

Recently, due to the development of the Internet and electronic devices, there has been an enormous increase in the amount of available knowledge and information. As this growth has proceeded, studies on large-scale ontological reasoning have been actively carried out. In general, a machine learning program or knowledge engineer measures and provides a degree of confidence for each triple in a large ontology. Yet, the collected ontology data contains specific uncertainty and reasoning such data can cause vagueness in reasoning results. In order to solve the uncertainty issue, we propose an RDFS reasoning approach that utilizes confidence values indicating degrees of uncertainty in the collected data. Unlike conventional reasoning approaches that have not taken into account data uncertainty, by using the in-memory based cluster computing framework Spark, our approach computes confidence values in the data inferred through RDFS-based reasoning by applying methods for uncertainty estimating. As a result, the computed confidence values represent the uncertainty in the inferred data. To evaluate our approach, ontology reasoning was carried out over the LUBM standard benchmark data set with addition arbitrary confidence values to ontology triples. Experimental results indicated that the proposed system is capable of running over the largest data set LUBM3000 in 1179 seconds inferring 350K triples.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.4
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• pp.9-17
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• 2013

This paper describes an experimental program to investigate the shear behavior of insulated concrete sandwich panels (CSPs) with different types of GFRP shear connector. The study included testing of 13 insulated CSP specimens with two types of surface conditions for extruded polystyrene (XPS) insulation and various shapes of shear connectors. All specimens were loaded in direct shear by means of push-out and were consist of three concrete panels, two insulation layer and four rows of GFRP shear connectors. Load-relative slip between concrete panel and insulation response of CSP specimens has been established through push-out shear test. Test results indicate that the surface condition of insulation has a significant effect on the bond strength between concrete panel and insulation. The specimen used XPS foam with 10mm deep slot shows higher bond strength than those used XPS foam with meshed surface. Corrugated GFRP shear connectors show equivalent strength to grid GFRP shear connectors. Cross-sectional area and embedded length of shear connector have a notable effect on overall response and inplane shear strength of the CSP specimens.