• Journal of the Computational Structural Engineering Institute of Korea
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• v.33 no.2
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• pp.95-101
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• 2020

The wind turbine blades should be designed to possess a high stiffness and should be fabricated with a light and high strength material because they serve under extreme combination of lift and drag forces, converting kinetic energy of wind into shaft work. The goal of this study is to understand the basic knowledge required to curtail the process time consumed during the construction of small wind turbine blades using carbon fiber reinforced polymer (CFRP) prepeg composites. The configuration of turbine rotor was determined using the QBlade freeware program. The fluid dynamics module simulated the loads exerted by the wind of a specific speed, and the stress analysis module predicted the distributions of equivalent von Mises stress for representing the blade structures. It was suggested to modify the shape of test specimen from ASTM D638 to decrease the variance in measured tensile strengths. Then, a series of experiments were performed to confirm that the bladder compression molded CFRP prepreg can provide sufficient strength to small wind turbine blades and decrease the cure time simultaneously.

• Archives of design research
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• v.17 no.4
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• pp.211-222
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• 2004

During the 1980s, Textile design achieved a remarkable growth in creating aesthetic effect and in establishing its standing by responding to demands of the time effectively and seeking changes proactively. This was a period when Textile design constructed its modern concept as it was attempting a qualitative improvement through advanced technology, high class, and differentiation. The advent of advanced materials through the development of textile engineering, employment of craft techniques to further cultural and artistic orientation, and restoration of decorativeness in pursuit of sensitivity, all these developments of the 1980s contributed to the rise of above characteristics. In this study, attempts are made to grasp the new trend of Textile design during the 1980s and to review diverse methods of aesthetic creation and plastic possibility which this trend presented for the Textile, and thus to recognize the role of Textile design and its importance in a new light. The new trend of Textile design during the 1980s can be summarized as follows: 1) An appreciation of the creative aspect of the Textile. As attempts are made to emphasize visual and sensitive aspects of the medium, Textile tended to become an object of art itself. 2) A new awareness of the representative and plastic capacity of the fiber material. As attempts are made to develope the creative potential of the Textile, representation of the material tended to become more diversified. 3) A recognition of the Textile as a proper means to deliver the spirit of the time. As the medium accommodates and fuses diverse cultures including traditional culture, more emphasis was place on cultural contents of the Textile. In the process of pursuing these changes, Textile design of the 1980s has also contributed to the creation of new values, laying the groundwork for its emergence as an advanced high value-added industry.

• Analytical Science and Technology
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• v.15 no.6
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• pp.514-520
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• 2002

The electrothermal vaporization (ETV) hollow cathode glow discharge atomic emission spectrometer for analysis of liquid sample has been developed and characterized. This system has improved the sample introduction method of electrothermal vaporization and the hollow cathode glow discharge. The sample introduction method was possible to provide high analyte transport efficiency to the plasma by helix coil made of tungsten material. In addition, small volume samples (<$30{\mu}{\ell}$) could be used. The system has glow discharge cell with special design for improvement of precision. The effect of discharge parameters such as discharge power, gas flow rate has been studied to find optimum condition. The emitted light was effectively carried into detector by fiber optic cable in UV region. The calibration curve of Pb, Cd were obtained with 3 samples.

• Asian-Australasian Journal of Animal Sciences
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• v.32 no.5
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• pp.701-710
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• 2019

Objective: This study investigated the effect of different acute heat stress (HS) levels on chicken meat quality and ultra-structure. Methods: Chickens were randomly divided into 7 groups to receive different HS treatments: i) $36^{\circ}C$ for 1 h, ii) $36^{\circ}C$ for 2 h, iii) $38^{\circ}C$ for 1 h, iv) $38^{\circ}C$ for 2 h, v) $40^{\circ}C$ for 1 h, vi) $40^{\circ}C$ for 2 h, and vii) un-stressed control group ($25^{\circ}C$). Blood cortisol level, breasts initial temperature, color, pH, water holding capacity (WHC), protein solubility and ultra-structure were analyzed. Results: HS temperatures had significant effects on breast meat temperature, lightness ($L^*$), redness ($a^*$), cooking loss and protein solubility (p<0.05). The HS at $36^{\circ}C$ increased $L^*{_{24h}}$ value (p<0.01) and increased the cooking loss (p<0.05), but decreased $a^*{_{24h}}$ value (p<0.05). However, as the temperature increased to $38^{\circ}C$ and $40^{\circ}C$, all the values of $L^*{_{24h}}$, cooking loss and protein denaturation level decreased, and the differences disappeared compared to control group (p>0.05). Only the ultimate $pH_{24h}$ at $40^{\circ}C$ decreased compared to the control group (p<0.01). The pH in $36^{\circ}C$ group declined greater than other heat-stressed group in the first hour postmortem, which contributed breast muscle protein degeneration combining with high body temperature, and these variations reflected on poor meat quality parameters. The muscle fiber integrity level in group $40^{\circ}C$ was much better than those in $36^{\circ}C$ with the denatured position mainly focused on the interval of muscle fibers which probably contributes WHC and light reflection. Conclusion: HS at higher temperature (above $38^{\circ}C$) before slaughter did not always lead to more pale and lower WHC breast meat. Breast meat quality parameters had a regression trend as HS temperature raised from $36^{\circ}C$. The interval of muscle fibers at 24 h postmortem and greater pH decline rate with high body temperature in early postmortem period could be a reasonable explanation for the variation of meat quality parameters.

• Journal of Ocean Engineering and Technology
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• v.33 no.2
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• pp.168-177
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• 2019

KRISO (Korea Research Institute of Ship & Ocean Engineering) started a project to develop the core algorithms for autonomous intervention using an underwater robot in 2017. This paper introduces the development of the robot platform for the core algorithms, which is an ROV (Remotely Operated Vehicle) type with one 7-function manipulator. Before the detailed design of the robot platform, the 7E-MINI arm of the ECA Group was selected as the manipulator. It is an electrical type, with a weight of 51 kg in air (30 kg in water) and a full reach of 1.4 m. To design a platform with a small size and light weight to fit in a water tank, the medium-size manipulator was placed on the center of platform, and the structural analysis of the body frame was conducted by ABAQUS. The robot had an IMU (Inertial Measurement Unit), a DVL (Doppler Velocity Log), and a depth sensor for measuring the underwater position and attitude. To control the robot motion, eight thrusters were installed, four for vertical and the rest for horizontal motion. The operation system was composed of an on-board control station and operation S/W. The former included devices such as a 300 VDC power supplier, Fiber-Optic (F/O) to Ethernet communication converter, and main control PC. The latter was developed using an ROS (Robot Operation System) based on Linux. The basic performance of the manufactured robot platform was verified through a water tank test, where the robot was manually operated using a joystick, and the robot motion and attitude variation that resulted from the manipulator movement were closely observed.

• Composites Research
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• v.32 no.5
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• pp.284-289
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• 2019

In the present paper, the dynamic force-moment equilibrium equations, driving power and energy equations are analyzed to formulate the equation for fuel economy(km/liter) equivalent to the driving distance (km) divided by the fuel volume (liter) of the vehicle, a selected model of gasoline powered KIA K3 (1.6v). In addition, the effects of the dynamic parameters such as speed of vehicle (V), vehicle total weight(M), rolling resistance ($C_r$) between tires and road surface, inclined angle of road (${\theta}$), as well as the aerodynamic parameters such as drag coefficient ($C_d$) of vehicle, air density(${\rho}$), cross-sectional area (A) of vehicle, wind speed ($V_w$) have been analyzed. And the possibility of alternative materials such as lightweight metal alloys, fiber reinforced plastic composite materials to replace the conventional steel and casting iron materials and to reduce the weight of the vehicle has been investigated by Ashby's material index method. Through studies, the following results were obtained. The most influencing parameters on the fuel economy at high speed zone (100 km/h) were V, the aerodynamic parameters such as $C_d$, A, ${\rho}$, and $C_r$ and M. While at low speed zone (60 km/h), they are, in magnitude order, dynamic parameters such as V, M, $C_r$ and aerodynamic ones such as $C_d$, A, and ${\rho}$, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.5
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• pp.468-476
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• 2019

This paper presents the means of improving the strength of LTV's FRP structure for resolve and prevent quality problems. LTV secures enough kerb weight by applying FRP materials at hood and rear van assembly. However, because of FRP's inherent limitations, many initial quality problems such as crack at connections have occurred. Moreover, hood assy' is concerned about fall of endurance, because hood assy' have operated in abnormal condition. Therefore, this study executes lamination structure optimizations of FRP structure for improving bending strength. As a results, hood and rear van's bending strength at connections is improved 8.1 times and 1.5 times, respectively. Also hood assy's plate secures endurance life and improve 1.7 times of critical load about abnormal operating conditions through 1.4 times improvement of bending strength.

• Composites Research
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• v.34 no.1
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• pp.8-15
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• 2021

In the shipbuilding and marine industry, as a technology for reducing the weight of parts to reduce energy and improve operational efficiency of ships is required, a method of applying fibers-reinforced composites which is high-strength lightweight materials, as part materials can be considered. In this study, the possibility of applying fibers-reinforced composites to the pipe support clamps was evaluated to reduce the weight of LNGC. The fibers-reinforced composites were manufactured using carbon fibers and glass fibers as reinforcing fibers. Through the computer simulation program, the properties of the reinforcing materials and the matrix materials of the composites were inversely calculated, and the performance prediction was performed according to the change in the properties of each fiber lamination pattern. In addition, the structural analysis of the clamps according to the thickness of the composites was performed through the finite element analysis program. As a result of the study, it was confirmed that attention is needed in selecting the thickness when applying the fibers-reinforced composites of the clamp for weight reduction. It is considered that it will be easy to change the shape of the structure and change the structure for weight reduction in future supplementary design.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.7
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• pp.471-478
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• 2022

This paper is about research and development of Korea Aerospace University's Solar-Powered UAV System that named of KAU-SPUAV, and describes the design process of the 4.2 m solar UAV that succeeded in a long flight of 32 hours and 19 minutes at June 2020. In order to improve the long-term flight performance of the KAU-SPUAV, For reduce drag, a circular cross-section of the fuselage was designed, and manufactured light and sturdy fuselage by applying a monocoque structure using a glass fiber composite material. In addition, a solar module optimized for the wing shape of a 4.2 m solar drone was constructed and arranged, and a propulsion system applied with the 23[in] × 23[in] propeller was constructed to improve charging and flight efficiency. The developed KAU-SPUAV consumes an average of 55W when cruising and can receive up to 165W of energy during the day, and its Long-term Endurance was verified through flight tests.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.6
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• pp.73-81
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• 2022

Recently, as the service life of structures increased, the load-carrying capacity of deteriorated reinforced concrete, where corrosion of reinforcing bars occurs due to various causes, is frequently decreased. In order to address this problem, many studies on the bond characteristic of FRP (Fiber Reinforced Polymer) bars with corrosion resistance, light weight and high tensile strength have been conducted, however there are not many studies on the bond characteristic of grid-typed CFRP embedded in concrete. Therefore, in order to evaluate the bond characteristics of grid-typed CFRP and its usability as a substitute for steel rebar, a pull-out test is performed using the longitudinal bond length and transverse grid length of the grid-typed CFRP as variables. Through the pull-out test, the bond load-slip curve of the grid-typed CFRP is derived, and the bond behavior is analyzed. The total bond load equation is proposed as the sum of the bond force of the longitudinal bond length and the shear force of the grid in the transverse direction. Also, expressing the area of the bond load-slip curve as total work, the change in dissipated energy with respect to the slip is analyzed to examine the effect of the tranverse grid on the bond force.