• Journal of the Korea Concrete Institute
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• v.24 no.5
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• pp.605-612
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• 2012

Spalling of concrete occurs due to vapor pressure ignited explosion, temperature difference across a section, and combination of these factors. Factors affecting spalling can be classified into internal and external factors such as material property and environmental condition, respectively, have to be considered to precisely understand spalling behavior. An external environmental factor such as differences in heating rate cause internal humidity cohesion and different vapor pressure behavior. Therefore, spalling property, vapor pressure and thermal strain property were measured from concrete with compressive strengths of 30 MPa, 50 MPa, 70 MPa, 90 MPa, and 110 MPa, applied with ISO-834 standard heating curve of $1^{\circ}C/min$ heating rate. The experimental results showed that spalling occurred when rapid heating condition was applied. Also, when concrete strength was higher, the more cross section loss from spalling occurred. Also, spalling property is influenced by first pressure cancellation effect of thermal expansion caused by vapor pressure and heating rates.

• Culinary science and hospitality research
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• v.20 no.4
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• pp.115-126
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• 2014

The purpose of this study was to offer primary information for development of Makgeolli adapted to the tastes of Chinese and marketing strategies for promoting consumption of Makgeolli in the Chinese market. This study was intended to investigate the Makgeolli drinking behavior through a survey and the sensory properties and preference of fresh and sterilized Makgeolli through sensory evaluation focusing on the Chinese students in Korea, becoming potential consumers of Makgeolli. The survey was conducted from October 9th to October 30th, 2013, and then 117 copies were adopted for the analyses. The results are as follows. 71.8% of the subjects liked Makgeolli, 56.4% drank 5-6 times a week, and 25.7% drank more than 2 bottles at a time. 61.5% of the subjects had purchasing experience. The routes of collecting information about Makgeolli were acquaintances(66.7%) and media sources(28.2%). In the sensory evaluation, sterilized Makgeolli(BS) that has a fresh odor, sweet and sour taste, cooling sensation, and good aftertaste got the best score in the overall acceptability, and fresh Makgeolli(KD) that has a strong nuruk odor, turbidity, bitter taste, and heavy mouthfeel got the lowest score in the overall acceptability. These results show that sweet, fresh, and refreshing Makgeolli suits Chinese's taste and word of mouth marketing through the expansion of tasting events would promote Makgeolli consumption in the Chinese market.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.10
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• pp.817-822
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• 2017

The braking system is one of the most important components in vehicles and machines. It must exert a reliable braking force when they are brought to a halt. Generally, frictional heat is generated by converting kinetic energy into heat energy through friction. As the kinetic energy is converted into heat energy, high temperature heat is generated which affects the mechanical behavior of the braking system. Frictional heat affects the thermal expansion and friction coefficient of the brake system. If the temperature is not controlled, the brake performance will be decreased. Therefore, it is important to predict and control the heat generation of the brake. Various numerical analysis studies have been carried out to predict the frictional heat, but they assumed the existence of boundary conditions in the numerical analysis to simulate the frictional heat, because the simulation of frictional heat is difficult and time consuming. The results were based on the assumption that the frictional heat is different from the actual temperature distribution in a rotating brake system. Therefore, the reliability of the cooling effect or thermal stress using the results of these studies is insufficient. In order to overcome these limitations and establish a simulation procedure to predict the frictional heat, this study directly simulates the frictional heat generation by using a thermal-structure coupling element. In this study, we analyzed the thermo-mechanical behavior of a brake model, in order to investigate the thermal characteristics of brake systems by using the Finite Element method (FEM). This study suggests the necessity to directly simulate the frictional heating and it is hoped that it can provide the necessary information for simulations.

• Journal of the Korean Geosynthetics Society
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• v.11 no.2
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• pp.1-9
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• 2012

In order to review the utility of Lade's single hardening constitutive model, a series of isotropic compression-expansion tests and consolidated drained triaxial tests including as CTC, TC, RTC, and OSP were performed by Baekma river sand with various of stress path. Parameters required in model were determined using these tests. The accuracy of analysis was reviewed by back analysis of test results used to determine the 11 parameters of soil property through the test of each stress path. Also. for verifying the accuracy of prediction for the stress-strain behavior using failure criterion related 9 parameters with correlational equation and constant and yield criterion related parameters h, ${\alpha}$ and ${\eta}_1$, when stress path is different with each other, it has been obtained in the review result of stress path dependent characteristics of the constitutional model through the analyzing results of CTC, TC, RTC, OSP, and fine silica sand tests.

• Korean Journal of Materials Research
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• v.8 no.6
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• pp.538-544
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• 1998

The spallation of a thermal barrier coating layer depends on the formation of brittle spinels. thermal expansion mismatch between ceramic and metal. the phase transformation of a ceramic layer and residual stress of coating layer. In this work. the formation mechanism of oxide scale formed by oxidation treatment at 90$0^{\circ}C$ was investigated in order to verify oxidation behavior at the interface between E-beam coated $Zr0_2$-7wt.% $Y_20_3$ and plasma sprayed CoNiCrAIY. Some elements distributed in the bond coating layer were selectively oxidized after oxidation. At the initial time of oxidation. AI-depletion zone and $\alpha$-$Al_O_3$,O, were formed at the bond coating layer by the AI-outward diffusion. After layer grew until critical thickness. spinels. $Cr_20$, and $C0_2CrO_4$ by outward diffusion of Co. Cr, Ni were formed. It was found that the formation of spinels may be related to the spallation of $Zr0_2$-7wt.% $Y_20_3$ during isothermal oxidation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.6
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• pp.1775-1781
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• 2008

The effects of the type of curing agent on the swelling of the natural rubber(NR) sponge applicable to the self-sealing layer of a helicopter fuel tank were investigated. The curing systems employed were peroxide and mixed ones of sulfur and peroxide. The NR compounds were prepared in a kneader and a roll-mill. The compounds were partially cured in a press at high pressure and subsequently cured fully with expansion in another press at atmospheric pressure. The apparent density of the NR sponge was measured and the cell structure was observed with scanning electron microscopy. The swelling experiments were performed at room temperature using toluene, iso-octane, and an aircraft fuel as a solvent. More rapid volume swelling of the NR sponge cured by peroxide was achieved than cured by sulfur and peroxide with similar amount of curing agent added in rubber compounds. The apparent density and cell structure of the sponge were extremely sensitive to the amount of peroxide, which influences again the swelling behavior of the NR sponge. It is important to control properly two reactions of decomposition of foaming agent and crosslinking of NR in the mold to obtain rapid swelling of the NR sponge on contact of the fuel.

• Information Systems Review
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• v.17 no.3
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• pp.39-64
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• 2015

As information and information technology become more important in competitive corporate environments, the risk of information security breaches has increased accordingly. Although organizations establish security measures to manage information security risks, members of organizations do not comply with them well, and their information security behavior intention is unclear. Therefore, to understand the information security risk management intention of the members of organizations, the present study developed a research model using Protection Motivation Theory, Supervisory Authority Pressure, and Background factors. This study presents empirical research findings based on the analysis of survey data from 201 members of financial institutions. Perceived Severity, Self-efficacy, and Supervisory Authority Pressure had a positive effect on intention; however, Perceived Vulnerability and Response Efficacy did not affect intention. Security Avoidance Habit, which was considered a background factor, had a negative effect on all parameters, and did not have an effect on intention. Security Awareness Training, another background factor, had a positive effect on information security risk management intention and perceived vulnerability, self-efficacy, response efficacy, and supervisory authority pressure, and had no effect on perceived severity. This study used supervisory authority pressure and background factors in the field of information security, and provided a basis to use supervisory authority pressure in future studies on behavior of organizations and members of an organization. In addition, the use of various background factors presented the groundwork for the expansion of protection motivation theory. Furthermore, practitioners can use the study findings as a foundation for organization's security activities, and to improve regulations.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.1
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• pp.35-42
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• 2020

Torsional behavior due to the plane irregularities of the piloti building can cause excessive story drift in the torsionally outermost column, which can lead to shear failure of the column. As a seismic retrofit method that can control the torsional behavior of the piloti building, the expansion of RC wall, steel frame or steel brace may be used, but such methods may hinder the openness of the piloti floor. Therefore, in this study, linear dynamic analysis and nonlinear static analysis for piloti buildings retrofitted by knee brace were performed, and seismic performance evaluation and torsion control effect of knee brace were analyzed. The results showed that the shear force of the column increased when the piloti building retrofitted by knee brace, but it was effective in controlling the torsional deformation. In case of retrofit between knee brace and column by 30°, the shear force of the column increased less than that of 60°, and the lateral displacement of column was decreased in the order of □, ◯ and Ｈ in cross-section.

• Journal of the Korean Institute of Landscape Architecture
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• v.49 no.2
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• pp.41-50
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• 2021

This study was conducted to see the differences of park users by classifying them with their park use frequency in terms of park use, management policy and perception, using the same survey results conducted in 2014 and 2020. Research was conducted on urban parks in Yangju, South Korea, and 740 in 2014 and 431 in 2000 survey results were used. After classifying the high-use and low-use groups according to park use frequency, this study compared the demographic differences and park use method differences according to the group, the recognition differences for the future park management direction between the two groups were analyzed and compared using statistical analysis by year. The results showed that the park's quantitative expansion and accessibility improvements were the most important issues in 2014, while the importance of park management, such as checking and improving aging facilities, providing various programs, and creating a themed neighborhood park that could reveal the identity of the area, was increased in 2020. Despite recognizing the importance of persistent management in the case of high-use groups, the results showed that they were less willing to participate in park management programs compared to less-use groups, which showed the need for a discussion of how to involve high-use groups for long term park management. This study contribute the body of literature that it seeks to understand differences of park user in terms of their park use frequency. However, in future studies, analyzing the differences of park users through a short-term study is required.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.31 no.1
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• pp.32-36
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• 2021

This study was investigated in carbon diffusion behavior of laser-carburized TiZrN coating layer and the changes of mechanical properties. The carbon paste was deposited on TiZrN coatings, and the laser was irradiated to carburize into the coatings. The XRD peak corresponding to the (111) plane shifted to a lower angle after the carburization, showing the lattice expansion by doped carbon. The decreased grain size implied the compression by the grain boundary diffusion of carbon. The XPS spectra for the bonding states of carbon was analyzed that carbon was substitute to nitrogen atoms in TiZrN, as carbide, through the thermal energy of laser. In addition, the combination of sp2 and sp3 hybridized bonds represented the formation of an amorphous carbon. The cross-sectional TEM image and the inverse FFT of the TiZrN coating after carburizing were observed as the wavy shape, confirming the amorphous phase located in grain boundaries. After the carburization, the hardness increased from 34.57 GPa to 38.24 GPa, and the friction coefficient decreased by 83 %. In particular, the ratio of hardness and elastic modulus (H/E) which is used as an index of the elastic recovery, increased from 0.11 to 0.15 and the wear rate improved by 65 %.