• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.5A
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• pp.503-510
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• 2009

Latex modified concrete (LMC) is a successful polymer-portland cement concretes, which have been developed and used for many years, in overlaying bridge decks and resurfacing industrial floors. The excellent bond strength to substrate, easy application and high resistance to impact, abrasion, wear, aggressive chemicals and freeze-thaw deterioration have made this material used widely. The objective of this study was to determine experimentally the load-deflection response and ultimate strength of reinforced RC beams. The cracking patterns and the mode of failure were observed. Because of excellent bond strength and repairing effects, the RC beams repaired by LMC at compression or tension zone showed over 100% recovery from damaged structures. The RC beams overlaid by LMC showed significant improvement at load carrying capacity as overlay thickness increases. However, the beams repaired of tension zone without shear stirrups almost showed no strengthen effect, and indicated an interfacial failures. The interfacial behavior was estimated by numerical method adopting the concept of shear flow.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.2
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• pp.231-239
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• 1999

The microstructure of ceramic composite has been found to be governed by the type and amount of the secondary phase, the sintering aid, and the sintering conditions such as sintering temperature, pressure and holing time. Moreover, tribological properties are strongly dependent on microsturcture of composite and operating conditions. In this study, silicon nitride with various amount of magnesia as a sintering aid were prepared and sintered by a hot pressing (HP) technique. Microstructure, mechanical properties (hardness, strength, and fracture toughness), and tribological properties in different environments of $Si_{3}N_{4}$ (in air, water, and paraffine oil) were investigated as a function of MgO content in $Si_{3}N_{4}$. As increasing the amount of MgO in $Si_{3}N_{4}$, the glassy phase in the grain boundaries enlarged the $\beta$-phase elongated grains, and also degraded the Hertzian contact damage resistance. Tribological behaviors in air was seemed to be determined by fracture toughness of $Si_{3}N_{4}$, and those in water and paraffin oil was seemed to be determined by hardness as well as strength. Since glassy grain-boundary phase (MgO) in $Si_{3}N_{4}$ expected to be reacted with water during sliding, such tribochemical reaction reduced wear. In paraffin oil under a higher applied load, the initial sliding dominated wear rate because of Hertzian contact damage.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.29 no.6
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• pp.329-337
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• 2019

We synthesized potassium titanates having splinter and plate shape and evaluated frictional and wear properties of brake pad using them as reinforcements in friction materials. For splinter-shaped potassium titanates, potassium tetratitanate (K₂O·4TiO₂, PT4) with plate shape was prepared, then K ion of the titanate was leached by acid to make potassium hexatitanate (K₂O·6TiO₂, PT6), which was transformed to splinter-shaped PT6 by thermal treatment at 800℃. Plate-shaped potassium magnesium titanate (K_0.8Mg_0.4Ti_1.6O₄, PMT) was prepared by adding Mg in the potassium titanate using KCl as a flux. Using PT6 and PMT as reinforcements in friction materials of brake pad, we evaluated frictional and wear properties using 1/5-scale dynamometer. According to dynamometer test results, both reinforcements shows similar friction coefficient and fade & recovery behavior to conventional material and plate-shaped PMT exhibits higher wear resistance than splinter-shaped PT6.

• Elastomers and Composites
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• v.46 no.1
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• pp.45-53
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• 2011

The effect of the silane coupling agent, bis(triethoxysilypropyl)tetrasulfide (TESPT), on mechanical properties of a silica-filled NBR compound for oilseal was investigated. Curing behavior and crosslinking density of the compounds were measured using ODR (oscillating disk rheometer) and swelling ratio in toluene. UTM (universal testing machine) and shore A hardness tester were used in order to study the characteristics of mechanical properties of original vulcanizates and aged ones with heated air and ASTM No. 3. oil. Recovery of elasticity which influences the performance and service life of oilseal was investigated by giving bending deformation to vulcanizates in aging condition. After bending aging test, recovery distance was measured and calculated angle of recovery from it. TR (temperature retraction) test was performed on these vulcanizates to determine the low temperature recovery behavior. Wear resistance was measured by Taber type abrasion tester. In addition, SEM was used to characterize the morphology of the worn surface of vulcanizates. The result showed that addition of TESPT into silica-filled compound improves not only compound flow-ability, interaction between NBR and silica and crosslinking density, but also hardness, 100% modulus, recovery of elasticity, wear resistance, heat resistance and ASTM No.3 oil resistance of vulcanizates.

• Korean Journal of Materials Research
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• v.10 no.10
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• pp.703-708
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• 2000

As the engine design changes to get high efficiency and performance of commercial diesel engine, surface w wear of the earn follower becomes an important issue as applied load increasing at the contact face between cam follower and cam. We developed the ceramic cam follower made of sili$\infty$n nitride ceramic which was more wear resistant than the cast iron or sintered metal cam follower. Ceramic cam follower was made by direct brazing of thin ceramic disk to steel body using an active brazing alloy without the interlayer. In-situ crowning(R), resulted from the difference of thermal expansion coefficient between ceramic and carbon steel after direct brazing without any stress-relieving inter]ayer, could be controlled. When a earbon steel was heated above $A_{c1}$ point and then c$\infty$led, the expansion curve represented a hysteresis. Appropriate crowning was achieved below the $A_{c1}$ point(about $723^{\circ}C$) and crowning increased with brazing temperature exponentially above the $A_{c1}$ point. Optimum brazing temperature range was from 700 to $720^{\circ}C$. We developed successfully the ceramic cam follower having appropriate crowning and being inexpensive. Also we could successfully control the crowning of ceramic earn follower by hysteresis behavior of thermal expansion of earbon steel during direct brazing process.

• 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 %.

• Journal of the Korean Home Economics Association
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• v.25 no.2
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• pp.39-54
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• 1987

One's Clothing Satisfaction, has a great influence on his role behavior in a society. Especially, as for the teacher's and the professors whose role is teaching, it can not be too emphaszed. Above all, high school girls and college women are the most likely to be influenced by their teachers' clothing behavior, to whom they pay their respect in every way. From this point of view, this study was aimed at explaining, the correlation between the teachers/professors' clothing behaviors and the learning efficiency. On clothing behaviors assessed 30 items related with the learning efficiency, selected from the instruments of preceding studies, and modified by the factors dealing with modesty, color, and design. The questionnaires were composed of two major categories: those for students and for teachers/progessors. The subjects of this study were included students and teachers/professors of high school and universities in Seoul. The data were analyzed statically by mean, standard Deviation, and F-test. The results of this study were summerized as follows; 1. The clothing behaviors of the teachers/professors influenced on the learning efficiency. Namely teachers' clothing satisfaction is in direct proportion to them teaching efficiency and students' learning efficiency. 2. Among the clothing behavior variables, modesty had a great influence on the learning efficiency, especially as for that of teachers more than professors. 3. The influence of the teachers'/professors' clothing behaviors on the learning efficiency showed no significance between high school girls and college women, but some significance between the grades of collegians. 4. As for the teachers'/professors' clothing behavior, male teachers/professors gave priority to design and female teachers/professors to modesty, color showed no significance between them irrespective of age. 5. As for the clothing behavior variabels, both the teachers/professors and the students showed some significance. In class the teachers/professors highly responded to their own clothing behaviors than the students. 6. According to priority the most favorable clothing colors for male teachers/professors are navy blue, gray, indigo blue, and black, and the most disgusting ones red, mud yellow, violet, pink, and green. The most favorable clothing colors for female teachers/professors are beign, white, pale yellow, and black, and the most disgusting ones red, mud yellow, and yellow and yellow according to priority. It is that teachers/professors should wear modestly and in color harmony to invite the desirable students' will to study. Teachers'/professors' colorful appearance and heavy toilet bring about a drop in the students' will to study.

• Journal of Global Scholars of Marketing Science
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• v.16 no.3
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• pp.39-60
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• 2006

The purpose of this study is to investigate the effect of two different characteristics of music(tempo) and advertising photograph(type) in a fashion store on consumers' emotional responses and approach behavior and to suggest competitive in-store atmospheric strategies. To test the conceptual model, this study used a video simulation method. Researchers selected a fashion casual wear retail store for young people and videotaped to provide realistic store settings. Two different levels of background music(fast, slow) and advertising photograph(sexy, cheerful) were inserted into the video clip generating four stimuli. Including a stimulus for the control group, 5 video clips were created. A total of 289 subjects answered the questionnaire after viewing a two-minute video clips. The results are as follows: First, advertising photograph in a store had a significant effect on consumers' in-store emotional state, whereas musical tempo did not. Second, the effect of in-store consumers' emotional state on behavioral reponses were investigated. Results showed that consumers' positive emotional state lead to consumers' approach behavior. The results of this study indicated that background music and advertising photograph in a fashion store affected consumers' in-store emotional state, and ultimately these affected consumers' positive approach behavior. Thus retailer should try to create a pleasant store environment using effective store atmospheric factors like background music and advertising photograph.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.05a
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• pp.337-341
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• 2004

Engineering ceramics have superior heat resistance, corrosion resistance, and wear resistance. Consequently, these art significant candidates for hot-section structural components of heat engine and the inner containment of nuclear fusion reactor. Besides, some of them have the ability to heal cracks and great benefit can be anticipated with great benefit the structural engineering field. Especially, law fracture toughness of ceramics supplement with self-healing ability. In the present study, we have been noticed some practically important points for the healing behavior of silicon nitride, alumina, mullite with SiC particle and whisker. The presence of silicon carbide (SiC) in ceramic compound is very important for crack-healing behavior. However, self-healing of SiC has not been investigated well in detail yet. In this study, commercial SiC was selected as sample, which can be anticipated in the excellent crack healing ability. The specimens were produced three-point bending specimen with a critical semi-circular crack of which size that is about $50-700{\mu}m$. Three-point bending test and static fatigue test were performed cracked and healed SiC specimens. A monotonic bending load was applied to cracked specimens by three-point loading at different temperature. The purpose of this paper is to report Strength Properties and Elastic Waves Characteristics of Silicon Carbide with Crack Healing Ability.

• Journal of the Korean Society of Costume
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• v.48
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• pp.183-196
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• 1999

The purpose of the Present research is to investigate the effect of fashion lifestyle on babies' clothing shopping attitude of housewives. In this study shopping attitude includes criteria for shop selection prefered types of shop and prefered shop atmosphere. Subjects are 447 housewives residing in Seoul Bundang Illsan and Pungchon and having child under 4 years old Data was analyzed by factor analysis cluster analysis analysis of variance and chi-square. The results of the study are as follows: 1. Housewives can be classified into four groups according to their fashion lifestyle the group of planned buying conservative/practical group the group of self-actualization/individuality and the high involved and care for shopping group. 2. Fashion lifestyle is different according to their age. The high involved and care for shopping group have the lager proportion in twenties than thirties. The conservative/practical group have a larger proportion in thirties. 3. The factors of shop selection which serve as criteria for shop the quality of service encironment anround shop quality of goods convenience to care about babies fashionable goods location of the shop and price of goods. The group of self actualization/personality prefers shops carrying fashionable and unique style of babies clothing and showing prestige. The conservative/practical group prefers shops carrying good quality clothing and having variety in size and design. The high involved and careful shopping group prefers shops having wide space as well as carrying fashionable goods. 4. Among the types of babies clothing shops. department stroe is the most preferred Low-price brand shop is followed by traditional open market. The conservative/practical group and the group of planned shopping use department strores national bran shops street shops and import shops more often than other groups. 5. The result of the study indicates there are considerable differences in housewives attitudes of babies clothing shopping acording to their own fashion lifestyle. Therefore the retailer of babies clothing should decide their marketing policy on the basis of the understanding and analysis of costomer's fashion lifestyle. And they have to reflect their costomer's shopping attitudes on their marketing policy to improve the satisfaction of both consumer and retailer as well.