• Tribology and Lubricants
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• v.17 no.4
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• pp.267-275
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• 2001

Friction and wear properties of brake friction materials containing different metal fibers (Al, Cu or Steel fibers) were investigated. Based on a simple experimental formulation, friction materials with the same amount of metal fibers were tested using a pad-on-disk type friction tester. Two different materials (gray cast iron and aluminum metal matrix composite (MMC)) were used for disks rubbing against the friction materials. Results front ambient temperature tests revealed that the friction material containing Cu fibers sliding against gray cast iron disk showed a distinct negative $\mu$-v (friction coefficient vs. sliding velocity) relation implying possible stick-slip generation at low speeds. The negative $\mu$- v relation was not observed when the Cu-containing friction materials were rubbed against the Al-MMC counter surface. Elevated temperature tests showed that the friction level and the intensity of friction force oscillation were strongly affected by the thermal conductivity and melting temperature of metallic ingredients of the friction couple. Friction materials slid against cast iron disks exhibited higher friction coefficients than Al-MMC (metal matrix composite) disks during high temperature tests. On the other hand, high temperature test results suggested that copper fibers in the friction material improved fade resistance and that steel fibers were not compatible with Al-MMC disks showing severe material transfer and erratic friction behavior during sliding at elevated temperatures.

• Journal of the Earthquake Engineering Society of Korea
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• v.7 no.4
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• pp.1-13
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• 2003

For spatial free vibration of non-symmetric thin-walled curved beams with shear deformation, an improved formulation is proposed in the present study. The elastic strain and the kinetic energies are first derived by considering constant curvature and shear deformation effects due to shear forces and restrained warping torsion. Next equilibrium equations and force-deformation relations are obtained using a stationary condition of total potential energy. And the finite element procedures are developed by using isoparametric curved beam element with arbitray thin-walled sections. Particularly not only shear deformation and thickness-curvature effects on vibration behaviors of curved beams but also mode transition and crossover phenomena with change in curvatures of beams are parametrically investigated. In order to illustrate the accuracy and the reliability of this study, various numerical solutions for spatial free vibration are compared with results by available references and ABAQUS's shell element.

• Journal of the Korean Geotechnical Society
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• v.38 no.9
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• pp.45-52
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• 2022

Because discontinuity in the rock mass and contact of soil-structure interaction exhibits coupled thermal-hydromechanical (THM) behavior, it is necessary to develop an interface element based on the full governing equations. In this study, we derive force equilibrium, fluid continuity, and energy equilibrium equations for the interface element. Additionally, we present a stiffness matrix of the elastoplastic mechanical model for the interface element. The developed interface element uses six nodes for displacement and four nodes for water pressure and temperature in a two-dimensional analysis. The fully coupled THM analysis for fluid injection into a fault can model the complicated evolution of injection pressure due to decreasing effective stress in the fault and thermal contraction of the surrounding rock mass. However, the result of hydromechanical analysis ignoring thermal phenomena overestimates hydromechanical variables.

• Journal of Korea Trade
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• v.26 no.5
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• pp.1-22
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• 2022

Purpose - This study aims to analyze the influence of South Korea's outward foreign direct investment (OFDI) under the effect of both multinational enterprises' (MNEs) investment motivation and host country institutions. Some suggestions are put forward with regard to South Korean MNEs participating in and integrating into the fierce and changeable world of international market competition. Design/methodology - The basic hypotheses are that MNEs' investment motivations and the host country's superior institutions both boost South Korea's OFDI in those host countries. South Korea's OFDI is divided into investment choice stage and investment scale stage. A Heckman two-stage selection model is established for empirical analysis, using the panel data of South Korea's OFDI and related variables, from 2002 to 2019. Findings - (1) The influence on the investment scale of South Korea's OFDI is more regular and noteworthy than the influence on investment choice. (2) In the investment scale stage, there are obvious motivations to seek markets, labor force and superior technology, but not natural resources. (3) In the investment scale stage, the South Korea's OFDI is more obviously attracted by the host country's superior political institutions, economic institutions and legal institutions, but not cultural institutions. Originality/value - The choices of variables and uses of model expand the theoretical basis and empirical method of OFDI research. The results of the empirical study also provide some reference for the transnational investment of South Korean MNEs and the investment policy formulation of the South Korean government.

• Journal of the Korean Society of Food Science and Nutrition
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• v.44 no.9
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• pp.1364-1373
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• 2015

The purpose of this study was to determine the optimum sodium concentration (0~8%), soaking time (4~20 min) and storage time (0~60 day) for preparation of persimmon jangachi with kochujang sauce using response surface methodology. Physicochemical properties (salinity, pH, Hunter's color value, cutting force, and sensory evaluation) of persimmon kochujang jangachi were analyzed during storage at $20^{\circ}C$ for 60 days. When the proximate composition of persimmon was analyzed, moisture content, crude protein content, crude lipid content, and crude ash content were 85.41%, 0.51%, 0.22%, and 0.20%, respectively. For persimmon kochujang jangachi manufactured with different sodium concentrations, soaking times, and storage times, salinity, pH, Hunter's color value of L, a, and b, color, flavor, taste, texture, and overall preference were represented by a quadratic model. Cutting force was represented by a linear model pattern. In conclusion, the optimal formulation for persimmon kochujang jangachi, as assessed by numerical and graphical optimization methods, was a sodium concentration of 6.91%, soaking time of 11.36 minutes, and storage time of 25.18 days.

• Food Science of Animal Resources
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• v.23 no.2
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• pp.122-127
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• 2003

A surimi like material was made from fresh pig hearts and used to manufacture emulsion-type sausages for the improvement of quality characteristics. The heart muscles were diced and frozen at -60$^{\circ}C$ until processed. Then, the frozen diced heart muscles were thawed, chopped, filtered, and washed to extract myofibrillar proteins. The residue was centrifuged to take a surimi-like material. Emulsion-type sausages were made different levels of surimi-like material(5∼15%) and compared to the control. Cooking loss(CL, %) and water-holding capacity (WHC, %) were measured on raw meat batter, whereas shear force, hardness, color and panel test were measured after cooking. The addition of the surimi-like material up to 15% level in the sausage formulation reduced CL and increased WHC, as compared to the control. Shear force and hardness values of the control had the highest value, however sausages containing 15% surimi-like material had the lowest value(p<0.05). Increased surimi-like material became darker in color. Although no differences in panel scores of flavor and off-flavor were observed, panellists prefer to select sausages having 15% surimi-like material(p<0.05). These results indicated that a surimi-like material, which was a myofibrillar protein extracted from pig hearts, could be used to manufacture emulsion-type sausage up to 15% to improve cooking yield and textural characteristics without color and flavor defects.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.1
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• pp.67-74
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• 2003

Quality characteristics of dough and noodles prepared from Korean wheat flours (Gru and Tapdong) were evaluated by substituting foreign wheat flours and starch in the formula. Korean wheat flours showed greater water absorption and weakness as well as protein and ash contents, but lower stability than the foreign wheat (control) By increasing substituted foreign wheat flours, water absorption of domestic Gru and Tapdong decreased. Dough development time decreased for Tapdong by substituting up to 30％ with foreign wheat flours. When imported wheat flours added in Gru and Tapdong, weakness of dough was decreased. Adhesiveness of dough was increased in all samples according to water adding, and Gru particulary showed the most high adhesiveness at 65% water and 10~20% replacement. From the mechanical texture test, Tapdong noodles were increased in cutting force by increasing amounts of imported wheat but decreased in extension distance. However, Cru noodles showed the opposite tendency. Hardness, adhesiveness, and chewiness of noodles were increased in all samples by increasing amounts of substitution with imported starch. As a result of cooked noodles test, Korean wheat noodles showed relatively lower values in cutting force and extension distance than in those of the control Studies of noodle-related characteristics of Korean wheat flours indicated that domestic soft wheat such as Gru might have high quality above the foreign wheat in noodle preparation by adding flours containing high amylose or low gluten.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.993-999
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• 2008

A girder height limitation is the critical parameter for rapid construction of bridge deck and construction space limitation especially in urban area such as high population area and high density habitats. A standard post-tensioned I-shaped concrete girder usually demands relatively higher girder height in order to retain sufficient moment arm between compression force and tensile force. To elaborate this issue, a small U-shaped section with wide flanges can be used as a possible replacement of I-shaped standard girder. This prestressed concrete box girder allows more flexible girder height adjustment rather than standard I-shaped post-tensioned girder plus additional torsion resistance benefits of closed section. A 30m-long, 1.7m-high and 3.63m-wide actual small prestressed concrete box girder is designed and a laboratory test for its static behaviors by applying 6,200kN amount of load in the form of 4-point bending test was performed. The load-deflection curve and crack patterns at different loading stage are recorded. In addition, to extracting the dynamic characteristics such as natural frequency and damping ratio of this girder, several excitation tests with artificial mechanical exciter with un-symmetric mass are carried out using operational frequency sweep-up. Nonlinear finite element analysis of this 4 point bending test under monotonic static load is investigated and discussed with aids of concrete damaged plasticity formulation using ABAQUS program.

• The Journal of the Convergence on Culture Technology
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• v.10 no.3
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• pp.19-24
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• 2024

The future military combat environment is rapidly expanding the role and importance of artificial intelligence (AI) in defense, aligning with the current trends of declining military populations and evolving dynamics. Particularly, in the civilian sector, AI development has surged into new domains based on foundation models, such as OpenAI's Chat-GPT, categorized as Super-Giant AI or Hyperscale AI. The U.S. Department of Defense has organized Task Force Lima under the Chief Digital and AI Office (CDAO) to conduct research on the application of Large Language Models (LLM) and generative AI. Advanced military nations like China and Israel are also actively researching the integration of Super-Giant AI into their military capabilities. Consequently, there is a growing need for research within our military regarding the potential applications and fields of application for Super-Giant AI in weapon systems. In this paper, we compare the characteristics and pros and cons of specialized AI and Super-Giant AI (Foundation Models) and explore new application areas for Super-Giant AI in weapon systems. Anticipating future application areas and potential challenges, this research aims to provide insights into effectively integrating Super-Giant Artificial Intelligence into defense operations. It is expected to contribute to the development of military capabilities, policy formulation, and international security strategies in the era of advanced artificial intelligence.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.49 no.3
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• pp.247-258
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• 2023

This study aims to investigate the enhancement of water resistance and improvement in adhesion to the skin by combining dextrin palmitate and isopropyl titanium triisostearate coating materials with titanium dioxide. Due to the recent increase in consumers who enjoy outdoor activities, the demand for sunscreen with excellent water resistance is increasing. Prior research was conducted with O/W, Pickering, and W/O/W multiple formulations, but there was a limit to water resistance. The purpose of this study is to develop a complex inorganic powder that can improve water resistance and increase adhesion to the skin to solve this problem. First, we combined dextrin palmitate and isopropyl titanium triisostearate coating materials to form a composite with titanium dioxide. The coating of the inorganic powder was confirmed using FE-SEM and FT-IR analysis. The composite exhibited significantly higher in vitro water resistance compared to other formulations. The hydrophobicity of the coated inorganic powder was compared by measuring the contact angles. When the coated inorganic powder was applied to the W/O sunscreen formulation and the non-coated inorganic powder was applied to the W/O sunscreen formulation as a control, the SPF of the sunscreen containing the coated inorganic powder was higher. These results were the same when observed with a UV camera. Finally the adhesion of the coated inorganic powder to the skin was assessed by applying it to a foundation product. In vivo study, it was observed that the product formulated with the coated powder exhibited less smudging compared to the foundation product formulated with the non-coated powder. The developed inorganic powder in this study demonstrated excellent adhesion to the skin, providing a superior sensory experience, as well as enhanced hydrophobicity and remarkable water resistance effects. In the future, the result of this study is expected to help develop various sunscreen products to improve water resistance.