• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.2
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• pp.187-194
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• 2012

The strength of particle-reinforced metal matrix composites is, in general, known to be increased by the geometrically necessary dislocations punched around a particle that form during cooling after consolidation because of coefficient of thermal expansion (CTE) mismatch between the particle and the matrix. An additional strength increase may also be observed, since another type of geometrically necessary dislocation can be formed during extensive deformation as a result of the strain gradient plasticity due to the elastic-plastic mismatch between the particle and the matrix. In this paper, the magnitudes of these two types of dislocations are calculated based on the dislocation plasticity. The dislocations are then converted to the respective strengths and allocated hierarchically to the matrix around the particle in the axisymmetric finite-element unit cell model. The proposed method is shown to be very effective by performing finite-element strength analysis of $SiC_p$/Al2124-T4 composites that included ductile failure in the matrix and particlematrix decohesion. The predicted results for different particle sizes and volume fractions show that the length scale effect of the particle size obviously affects the strength and failure behavior of the particle-reinforced metal matrix composites.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.10
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• pp.480-489
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• 2020

Controversy and legal disputes over counterfeit fashion designs have recently arisen in the fashion industry. The purpose of this study is to examine cases of counterfeiting disputes over fashion designs, and how the perception of counterfeit fashion designs is fostered from the learner's point of view, suggesting implications for the counterfeiting problem. As a result of this study, first, counterfeiting disputes over fashion design started from a lack of utilization of the Design Protection Act and the ambiguity in counterfeit design criteria. Second, the negative perceptions of counterfeit designs were mainly about unethical behavior, inhibiting the growth of the fashion industry, and reducing consumers' willingness to buy the genuine article. Positive perceptions were mainly about the process of creation, the promotion of a developmental environment for the fashion industry, and the expansion of opportunities to promote new designs. The most common perception was the absence of clear criteria for judgments about counterfeiting. Third, the implications of the counterfeiting problem in fashion design require effective institutional improvement in the fashion industry, the establishment of standards to deal with counterfeiting, the development and practical introduction of education proposals regarding intellectual property rights, and changing the perception of counterfeiting in the fashion industry.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.327.1-327.1
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• 2014

Nitrides-on-silicon structures are considered to be an excellent candidate for unique design architectures and creating devices for high-power applications. Therefore, a lot of effort has been concentrating on growing high-quality III-nitrides on Si substrates, mostly Si(111) and Si(001) substrates. However, there are several fundamental problems in the growth of nitride compound semiconductors on silicon. First, the large difference in lattice constants and thermal expansion coefficients will lead to misfit dislocation and stress in the epitaxial films. Second, the growth of polar compounds on a non-polar substrate can lead to antiphase domains or other defective structures. Even though the lattice mismatches are reached to 16.9 % to GaN and 19 % to AlN and a number of dislocations are originated, Si(111) has been selected as the substrate for the epitaxial growth of nitrides because it is always favored due to its three-fold symmetry at the surface, which gives a good rotational matching for the six-fold symmetry of the wurtzite structure of nitrides. Also, Si(001) has been used for the growth of nitrides due to a possible integration of nitride devices with silicon technology despite a four-fold symmetry and a surface reconstruction. Moreover, Si(110), one of surface orientations used in the silicon technology, begins to attract attention as a substrate for the epitaxial growth of nitrides due to an interesting interface structure. In this system, the close lattice match along the [-1100]AlN/[001]Si direction promotes the faster growth along a particular crystal orientation. However, there are insufficient until now on the studies for the growth of nitride compound semiconductors on Si(110) substrate from a microstructural point of view. In this work, the microstructural properties of nitride thin layers grown on Si(110) have been characterized using various TEM techniques. The main purpose of this study was to understand the atomic structure and the strain behavior of III-nitrides grown on Si(110) substrate by molecular beam epitaxy (MBE). Insight gained at the microscopic level regarding how thin layer grows at the interface is essential for the growth of high quality thin films for various applications.

• Journal of East Asia Management
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• v.1 no.1
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• pp.65-87
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• 2020

In recent years, with the rapid development of network live streaming, with the popularization of mobile Internet and mobile terminal equipment, the live streaming industry has ushered in great development. A sudden outbreak of the COVID-19 makes the PC end live streaming which has been developed for many years enter a new era, giving birth to the rapid development of mobile end live streaming. Not only because of the expansion of the live streaming industry market, the rise of the trend of the national live streaming, but also because the mobile live streaming is more and more valued by the brand, becoming an important tool for brand communication and product promotion. It is because of its unique communication characteristics that some scholars believe that the era of precision marketing has been opened by live network. Mobile live from the initial fans to reward and promote the brand, to now in the form of live marketing, consumers can "buy while watching". The time period from the understanding of the goods to the final completion of the purchase behavior has been greatly shortened. It is conducive to improving sales volume and brand awareness. Marketing communication through mobile live platform has become a popular way of brand marketing. This paper mainly studies the current situation, methods, problems and development strategies of brand marketing activities with the help of live streaming platform under the background of mobile internet. Taking Tmall live streaming platform as an example, this paper analyzes several ways of brand marketing with the help of live streaming and some universal characteristics of live streaming marketing by using the relevant theories of marketing. In view of the problems existing in live streaming brand marketing, it puts forward relevant Improvement measures. First of all, the paper puts forward the innovation in content and form. Second, the paper suggests that we should make full use of new technologies such as AR and VR to effectively combine with mobile live broadcasting. Third, the paper explores the integration of multiple channels to create intelligent marketing, and further optimize the live interface of mobile terminals. Finally, the paper emphasizes that the government departments and the platform itself should jointly supervise the mobile network live streaming platform and establish a good live broadcasting environment for mobile terminals. With the help of mobile live streaming, the marketing mode has an important impact on the promotion of brand marketing. How to make better use of this business mode and accurately use mobile live broadcast to promote brand marketing, so that enterprises can create greater profits, is also of profound research significance.

• Journal of the Society of Disaster Information
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• v.9 no.4
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• pp.503-510
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• 2013

Recently, localized heavy rain is increased by climatic changes and landslide is increased. Also, because of landslide occurred in urban area, life and property damages are increased. Therefore, standard operation procedure of disasters should be established by steps and institutions so as to respond landslide. This thesis investigated application of current disaster manual so as to write SOP of landslide for disaster prevention related experts and accepted opinion for responding necessaries by using landslide SOP and important matters by step of disaster management. As the result of investigation, application of manual was low during the current response to disasters and application was the highest in responding step among the steps of disaster management. In case of landslide, they responded that response with SOP is necessary. During the organization of landslide SOP, they responded that training and education for landslide disaster are important at the step of prevention, conduction of landslide disaster broadcasting and provision of information are important at the step of preparation, guidance for evasion and behavior methods is important at the step of response and investigation of landslide disaster damages and reflection of record and evaluation are important at the step of recovery. In addition, for the requests for landslide SOP application, there was an importance of secondary factors such as expansion of professional manpower, strengthening of law and institution, education and training for SOP acquisition, etc.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.40 no.2
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• pp.145-156
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• 2020

The climate change occurring all over the world increases the risk, specially in urban area, Accordingly, rainwater pumping station expansion is required than before. In order to increase the efficiency of the rainwater pumping station, the analysis of flow characteristics in the pump sump is needed for vortex control. Many efforts have been made to illuminate the vortex behavior using PIV, but any reliable results have not been obtained yet, because of the limitations in image capturing and dependency of measured velocity values on the interrogation area and time interval used for velocity calculation. In this study, therefore, experiments were carried out to find out the limitation of PIV and estimate the validation of the velocity values associated with the analysis parameters such as interrogation area, time interval, grid size. For the experimental condition used in this study, the limitation of PIV and the effects of parameters on the velocity estimation are presented.

• Korean Journal of Materials Research
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• v.10 no.6
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• pp.415-421
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• 2000

The effect of silica binder content on the mechanical properties of zircon shell mold was investigated. Content of binder silica sol to refractory powder in weight[$R_W$] was adjusted from 0.18 to 0.43. Sintering of the shell mold was carried out in the temperature range of $871^{\circ}C$ to $1400^{\circ}C$. Green strength of the shell mold at room temperature increased with increasing $R_W$ and sintering temperature up to $1300^{\circ}C$. However, the mold with $R_W$ of 0.43 that sintered at $1400^{\circ}C$ for 3 hours showed relatively low strength and large level of porosity. The mechanical behavior of the shells is supposed to attributed to the difference in thermal expansion coefficient between refractory powder and binder silica. The optimum value of $R_W$ for zircon-based shell molds was found to be 0.33.

• Journal of the Korean institute of surface engineering
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• v.46 no.2
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• pp.68-74
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• 2013

For the coating of diamond films on WC-Co tools, a buffer interlayer is needed because Co catalyzes diamond into graphite. W and Ti were chosen as candidate interlayer materials to prevent the diffusion of Co during diamond deposition. W or Ti interlayer of $1{\mu}m$ thickness was deposited on WC-Co substrate under Ar in a DC magnetron sputter. After seeding treatment of the interlayer-deposited specimens in an ultrasonic bath containing nanometer diamond powders, $2{\mu}m$ thick nanocrystalline diamond (NCD) films were deposited at $600^{\circ}C$ over the metal layers in a 2.45 GHz microwave plasma CVD system. The cross-sectional morphology of films was observed by FESEM. X-ray diffraction and visual Raman spectroscopy were used to confirm the NCD crystal structure. Micro hardness was measured by nano-indenter. The coefficient of friction (COF) was measured by tribology test using ball on disk method. After tribology test, wear tracks were examined by optical microscope and alpha step profiler. Rockwell C indentation test was performed to characterize the adhesion between films and substrate. Ti and W were found good interlayer materials to act as Co diffusion barriers and diamond nucleation layers. The COFs on NCD films with W or Ti interlayer were measured as less than 0.1 whereas that on bare WC-Co was 0.6~1.0. However, W interlayer exhibited better results than Ti in terms of the adhesion to WC-Co substrate and to NCD film. This result is believed to be due to smaller difference in the coefficients of thermal expansion of the related films in the case of W interlayer than Ti one. By varying the thickness of W interlayer as 1, 2, and $4{\mu}m$ with a fixed $2{\mu}m$ thick NCD film, no difference in COF and wear behavior but a significant change in adhesion was observed. It was shown that the thicker the interlayer, the stronger the adhesion. It is suggested that thicker W interlayer is more effective in relieving the residual stress of NCD film during cooling after deposition and results in stronger adhesion.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.140-140
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• 2018

The 3D interconnect technologies have been appeared, as the density of Integrated Circuit (IC) devices increases. Through Silicon Via (TSV) process is an important technology in the 3D interconnect technologies. And the process is used to form a vertically electrical connection through silicon dies. This TSV process has some advantages that short length of interconnection, high interconnection density, low electrical resistance, and low power consumption. Because of these advantages, TSVs could improve the device performance higher. The fabrication process of TSV has several steps such as TSV etching, insulator deposition, seed layer deposition, metallization, planarization, and assembly. Among them, TSV metallization (i.e. TSV filling) was core process in the fabrication process of TSV because TSV metallization determines the performance and reliability of the TSV interconnect. TSVs were commonly filled with metals by using the simple electrochemical deposition method. However, since the aspect ratio of TSVs was become a higher, it was easy to occur voids and copper filling of TSVs became more difficult. Using some additives like an accelerator, suppressor and leveler for the void-free filling of TSVs, deposition rate of bottom could be fast whereas deposition of side walls could be inhibited. The suppressor was adsorbed surface of via easily because of its higher molecular weight than the accelerator. However, for high aspect ratio TSV fillers, the growth of the top of via can be accelerated because the suppressor is replaced by an accelerator. The substitution of the accelerator and the suppressor caused the side wall growth and defect generation. The suppressor was used as Single additive electrodeposition of TSV to overcome the constraints. At the electrochemical deposition of high aspect ratio of TSVs, the suppressor as single additive could effectively suppress the growth of the top surface and the void-free bottom-up filling became possible. Generally, copper was used to fill TSVs since its low resistivity could reduce the RC delay of the interconnection. However, because of the large Coefficients of Thermal Expansion (CTE) mismatch between silicon and copper, stress was induced to the silicon around the TSVs at the annealing process. The Keep Out Zone (KOZ), the stressed area in the silicon, could affect carrier mobility and could cause degradation of the device performance. Cobalt can be used as an alternative material because the CTE of cobalt was lower than that of copper. Therefore, using cobalt could reduce KOZ and improve device performance. In this study, high-aspect ratio TSVs were filled with cobalt using the electrochemical deposition. And the filling performance was enhanced by using the suppressor as single additive. Electrochemical analysis explains the effect of suppressor in the cobalt filling bath and the effect of filling behavior at condition such as current type was investigated.

• Journal of the Korean Geotechnical Society
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• v.31 no.6
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• pp.71-82
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• 2015

Recently, due to the expansion of urban infrastructure for the citizen convenience, the shield tunnel construction has increased considering the civil complaints minimization and construction stability. Most shield tunnels are designed based on the assumption of the undrained condition that underground water does not inflow, but they are operated in the field as drained tunnels with drainage facility to drain underground water. Therefore, the drained condition needs to be considered in the shield tunnel design. It is also necessary to consider the weathered granite soil that is widely distributed throughout the country and consequently is encountered in most of construction sites. In this paper, the model test which can control total stress and pore water pressure and simulate the underground tunnel located in the weathered granite soil below ground water level is conducted. Total stress, pore water pressure and an inflow water into an inner pipe were measured using the testing device. Test results showed that the total stress in a drained condition was lower than in an undrained condition because pore water pressure decreased in a drained condition and an inflow water into an inner pipe was proportional to the loading stress in a drained condition. As a result, if a drained condition is considered in the shield tunnel design, the more economical design can be expected because of the stress reduction of the lining.