• Journal of the Society of Disaster Information
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• v.8 no.3
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• pp.223-233
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• 2012

Steel fiber is high stiffness and large weight. So, Pumping hose to rupture of the safety management is difficult. Steel fiber caused by corrosion of the deterioration of durability and high-rebound losses are needed for the improvements. Thus, the revised regulations in 2009 by a steel fiber to reinforce other materials is possible. Variety of fiber reinforcement material for concrete review of applicability is needed. Steel fiber strength than the other fibers is large and by the geometry of the fibers are attached to improve performance. However, compared to steel fiber organic fibers and low modulus of elasticity and tensile strength of fiber and agglomeration occurs in the concrete to be used as reinforcement material is difficult. In this regard, the present study as a single object in the micro-fiber bouquet sharp entanglement through make muck attach surface area, distributed fibers from surfactant of the surface enhanced polyamide fibers, steel fiber and PP fiber reinforced concrete by comparing the scene to provide a basis for the use.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.3
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• pp.88-98
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• 2011

Masonry structure is a style of building which has been widely applied as residential facilities of low and middle stories, commercial and public facilities etc. But it is possible to destroy by loss of adhesive strength or sliding when lateral forces, such as earthquake, occurs. This study proposes a seismic retrofit method for masonry structure and its seismic performance is demonstrated by shaking table test. Two specimens per each shaking direction were made, having out-of-plane(weak axis) and in-plane(strong axis) direction. External load of 1 ton was also applied for each specimen during the test, to model the behavior of reinforced masonry wall. As a result of shaking table tests, it is shown that the specimen applying the proposed seismic retrofit method showed acceptable behaviors in both of Korea building design criteria(0.14g) and USA seismic criteria suggested by IBC(0.4g). However, it was observed that stiffness of the specimen toward out-of-plane was rapidly decreasing when seismic excitations over 0.14g were loaded. In comparison of relative displacements, maximum relative displacement of specimens which were accelerated toward out-of-plane with 0.4g at once was 29~31% of maximum relative displacement when specimens were gradually accelerated from 0.08g to 0.4g, while the maximum relative displacement of specimens accelerated toward in-plane has similar value in both cases. Therefore, it is concluded that the wall accelerated toward out-of-plane is more affected by hair crack or possible fatigues caused by seismic excitation.

• The Journal of Engineering Geology
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• v.26 no.2
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• pp.207-221
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• 2016

As greater numbers of fill dams and reservoirs become old, the risks of damage or embankment collapse increases. However, few studies have considered the deterioration and hazard classification of the internal core layers of fill dams. This study reports the results of geotechnical investigations of 13 earth-cored fill dams in Korea, based on no-water borehole drilling, Standard Penetration Test, and 2D and 3D electrical resistivity surveys along with in situ and laboratory testing. High-capacity no-water boring minimized core layer disturbance while providing continuous core sample recovery. The results allow the classification of potential hazards related to the existing core layers based on both visual inspection of the recovered samples and the results of engineering surveys and tests. Four types of potential hazard are classified: locally fluidized core with a high water content, rapid water inflow to a borehole, cores with granular materials, and relatively low stiffness of core. Among these, the locally fluidized core is the most critical hazard that requires remedial action because it is related to the potential internal flow path and internal erosion. The other three hazard types are of medium importance and require careful monitoring and regular inspection. Of note, there was no correlation between age and core deterioration. The results are expected to aid the safe management and potential upgrading of aging cored fill dams.

• Korean Journal of Optics and Photonics
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• v.22 no.4
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• pp.184-190
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• 2011

A compact imaging spectrometer (COMIS) was developed for a microsatellite STSAT-3. The satellite is now rescheduled to be launched into a low sun-synchronous Earth orbit (~700 km) by the end of 2012. Its main operational goal is the imaging of the Earth's surface and atmosphere with ground sampling distance of 27 m and 2 - 15 nm spectral resolution over visible and near infrared spectrum (0.4 - 1.05 ${\mu}m$). A flight model of COMIS was developed following an engineering model that had successfully demonstrated hyperspectral imaging capability and structural rigidity. In this paper we report the environmental test results of the flight model. The mechanical stiffness of the model was confirmed by a small shift of the natural frequency i.e., < 1% over 10 gRMS random vibration test. Electrical functions of the model were also tested without showing any anomalies during and after vacuum thermal cycling test with < $10^{-5}$ torr and $-30^{\circ}C\;-\;35^{\circ}C$. The imaging capability of the model, represented by a modulation transfer function (MTF) value at the Nyquist frequency, was also kept unvaried after all those environmental tests.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.1
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• pp.64-71
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• 2016

In this paper, when the composite beam is made with UHPC deck and steel girder, the steel girder takes the form of the inverted-T shape without top flange because of high strength and stiffness of UHPC deck. There is no evaluation by experiment and analysis about the shear connector behavior on the web of steel girder and flexural behavior of inverted-T shape composite beam. By this reason, this study compares between experiment and analysis by using tension softening model of UHPC on the basis of flexural test results of 16 members considering compressive strength of UHPC, spacing of stud and thickness of deck as variables. The results of tensile strength of UHPC by inverse analysis were 6.57 MPa(in case of 120 MPa) and 9.57 MPa(in case of 150 MPa). In case of the test members with small stud spacing, the results of analysis and test were close clearly, and the test members with thick deck and low UHPC compressive strength also similar, but effects were small. As it compared between analysis and experiment totally, the results of analysis and experiment agree well. So the tension softening model of UHPC is reasonably reflected on the real behavior of composite beam of UHPC.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.44 no.1
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• pp.81-87
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• 2018

The objective of this article is to provide analytical tools for the scattering of stratum corneum (SC) and to check whether the optical clearing agents (OCAs) could be applied in optics affecting the scattering reduction. Dark field images of tape striped corneocyte separates scattered light of the SC from others in vitro. Several optical clearing agents were tested to reduce the scattering. Physical properties of SC such as water contents, keratin configuration and volume after OCAs treatment were investigated by FT-IR and 3D laser microscope. Several reducing sugars, monomeric sugars, sugar alcohol, and hyaluronic acid, which were used as humectants in cosmetic field, also reduced scattering. However, unlike dehydration in optics, water penetrated into the keratin in SC and scattering was decreased at low concentration of OCAs. In that condition, the volume of corneocyte was increased and stiffness seemed to decrease. The analyzing of tape-stripped SC, showed the change of optical and physical properties of corneocyte by optical clearing agents. The hydration of SC layer by optical clearing agents decreased the scattering of corneocyte and thus improved the skin appearance and moisturizing effect, which are important benefits in the cosmetic field and could provide new possibility to develop skin care study targeting at SC.

• Journal of Sensor Science and Technology
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• v.10 no.1
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• pp.1-8
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• 2001

Conventional microgyroscopes of vibrating type require resonant frequency tuning of the driving and sensing modes to achieve high sensitivity. These tuning conditions depend on each fabricated microgyroscopes, even though the microgyroscopes are identically designed. A new micromachined resonator, which is applicable to microgyroscopes with self-toning characteristics, is presented. Since the laterally driven two degrees of freedom (2DOF) resonator was designed as a symmetric structure with identical stiffness in two orthogonal axes, the resonator is applicable to vibrating microgyroscopes, which do not need mode tuning. A dynamic model of the resonator was derived considering gyroscopic application. The dynamic model was evaluated by experimental comparison with fabricated resonators. The microgyroscopes were fabricated using a simple 2-mask-process of a single polysilicon layer deposited on an insulator layer. The feasibility of the resonator as a vibrating microgyroscopes with self-tuning capability is discussed. The fabricated resonators of a particular design have process-induced non-uniformities that cause different resonant frequencies. For several resonators, the standard deviations of the driving and sensing frequencies were as high as 1232Hz and 1214Hz, whereas the experimental average detuning frequency was 91.75Hz. The minimum detuned frequency was 68Hz with $0.034mVsec/^{\circ}$ sensitivity. The sensitivity of the microgyroscopes was low due to process-induced non-uniformity; the angular rate bandwidth, however, was wide. This resonator could be successfully applicable to a vibrating microgyroscopes with high sensitivity, if improvements in uniformity of the fabrication process are achieved. Further developments in improved integrated circuits are expected to lower the noise level even more.

• Journal of Genetic Medicine
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• v.14 no.1
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• pp.8-17
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• 2017

Purpose: Pulse wave velocity (PWV) is an indicator of arterial stiffness, and is considered a marker of vascular damage. However, a genome-wide association study analyzing single nucleotide polymorphisms (SNPs) associated with brachial-ankle PWV (baPWV) has not been conducted in healthy populations. We performed this study to identify SNPs associated with baPWV in healthy populations in Korea. Materials and Methods: Genomic SNPs data for 2,407 individuals from three sites were analyzed as part of the Korean Genomic Epidemiologic Study. Without replication samples, we performed multivariable analysis as a post hoc analysis to verify the findings in site adjusted analysis. Healthy subjects aged between 40 and 70 years without self-reported history or diagnosis of hypertension, diabetes, hyperlipidemia, heart disease, cerebrovascular disease and cancer were included. We excluded subjects with a creatinine level >1.4 mg/dL (men) and 1.2 mg/dL (women). Results: In the site-adjusted association analysis, significant associations (P<$5{\times}10^{-8}$) with baPWV were detected for only 5 SNPs with low minor allele frequency. In multivariable analysis adjusted by age, sex, height, body mass index, mean arterial pressure, site, smoking, alcohol, and exercise, 11 SNPs were found to be associated (P<$5{\times}10^{-8}$) with baPWV. The 5 SNPs (P<$5{\times}10^{-8}$) linked to three genes (OPCML, PRR35 and RAB40C) were common between site-adjusted analysis and multivariable analysis. However, meta-analysis of the result from three sites for the 11 SNPs showed no significant associations. Conclusion: Using the recent standard for genome-wide association study, we did not find any evidence of significant association signals with baPWV.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.5
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• pp.149-156
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• 2021

FRP has been proposed to replace the steel as a reinforcement in the concrete structures for addressing the corrosion issue. However, FRP-Rebar does not behave in the same manner as steel because the properties of FRP are different. For example, FRP-Rebar has a high tensile strength, low stiffness, and linear elastic behavior which results in a difference bonding mechanism to transfer the load between the reinforcement and the surrounding concrete. Therefore, bonding behavior between FRP-Rebar and concrete has to be investigated using the bonding test. So, Pull-out test has been used to estimate bond behavior because it is simple. However, the results of pull-out test have a difference with flexural-boding behavior of FRP-Rebar concrete member. So, it is needed to evaluate the real fleuxral-bonding behavior. In this study, the evaluation method to flexural-bonding behavior of FRP-Rebar concrete member was reviewed and compared. It was found that the most accurate evaluation method for the fleuxral-bonding behavior of FRP-Rebar concrete member was splice beam test, however, the size and length of specimen have to increase than other test method and the design and analysis of splice beam is complex. Meanwhile, characteristics of concrete could be reflected by using arched beam test, unlike hinged beam test which is based on the ignored change of moment arm length in equilibrium equation. However, the possibility of shear failure exists before the flexural-bonding failure occur.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.1
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• pp.362-370
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• 2019

This study was conducted to investigate effects of 12 weeks of combined exercise training with blood flow restriction (BFR) on body composition (weight, %body fat, lean body mass, body mass index (BMI)) and cardiovascular responses (brachial-ankle pulse wave velocity (ba PWV) and ankle-brachial index (ABI)) in elderly women. Participants (N = 43, Females) were randomly assigned into a combined exercise with BFR (n = 14, BFR), only combined exercise (n =14, EX) or non-exercise control group (n = 15, CON). Two-way repeated measures ANOVA with contrast testing was utilized for data analysis. Alpha was set at p < 0.05. Body composition (weight, %body fat, BMI) in BFR was significantly changed, and %body fat in EX was significantly decreased, but there was no change in the CON. In addition, the right and left ba PWV values in the BFR were significantly decreased, while only the left side ba PWV in EX was significantly decreased and there was no change in the CON. Moreover, the % change and effect size of most variables in the BFR were higher than the EX. Taken together, the results indicate that even though BFR and EX groups performed the same combined exercise training, BFR had additional stimulations of the sympathetic nerve system due to blood flow restriction. Thus, BFR training is more beneficial and has greater effects on body composition and cardiovascular responses in elderly females.