• Journal of the Korean Applied Science and Technology
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• v.32 no.2
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• pp.188-193
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• 2015

Blast Furnace Slag is good for enhancing the qualities of concrete such as reducing hydration heat increasing fluidity, long-term strength and durability, but it has some problems: construction time is increased or the rotation rate of form is decreased due to low development of early strength. In this study, an aqueous alkali solution for alkali activated reaction was obtained by the electrolysis using concentrated water discharged from seawater desalination process. Prepared aqueous alkali solution was applied to produce mortars using blast furnace slag. The results can be summarized as follows : For the mortar, compressive strength was decreased below 2% of NaOH and increased below 6% of NaOH. And compressive strength was increased gradually with increasing NaOCl contents. However, NaCl contents of mortars caused a decrease of 28days strength above early strength.

• Atmosphere
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• v.29 no.3
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• pp.283-294
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• 2019

For the upper air observations, a temperature measurement using radiosonde is a common method, and the compensation of solar radiation effects in the radiosonde temperature sensor is an important factor. In this paper, we present various experiments and compensation methods of the radiosonde temperature sensor to overcome the errors caused by the movement of the radiosonde rotation, etc. The methods and procedures of this study are as follows. First, we used the solar simulator to analyze the temperature variation and solar effect of the temperature sensor in the radiosonde according to the insolation. We also analyzed the temperature variation and solar effect of the temperature sensor according to the incident angle between the solar simulator and radiosonde. Second, we measured and analyzed solar radiation absorbed by solar cells attached to radiosonde. Third, we present combined compensate solution of the first and the second experiment results, to overcome errors caused by insolation effects in the radiosonde temperature sensors. Fourth, we compared that the reference temperature in similar environment with the upper air conditions, to verify the new radiated compensation performance of the radiosonde temperature sensor. Finally, the radiosonde fabricated in this study was raised to the atmosphere, and the laser correction algorithm proposed through experiments was reviewed. As a result of the radiosonde SRS-10 produced in this study, the temperature deviation from Vaisala RS92 was $0.057^{\circ}C$ in nighttime observation, $0.17^{\circ}C$ in daytime observation, It is expected that the GRUAN under WMO will be able to obtain a high test rating of 5.0.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.2
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• pp.60-67
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• 2018

Recently, environment-friendly cultivation technology is popular. A cultivator is useful for turning over the stall bedding in a poultry farm. In this study, a rotary-based cultivator with a rechargeable battery was developed for eco-friendly management of broiler chickens. From the results of the test run, the clustered stall bedding was approximately divided into up and down layers. Through experimental evaluation, the working width was more than 60 cm, and the noise was less than 80 dB. The output of the motor was 400 W, and the speed of rotation was 3000 rpm. Electric battery type cultivators are expected to be widely used in the livestock industry.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1253-1258
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• 2007

The media transport systems, such as printers, copy machines, facsimiles, ATMs, cameras, etc. have been widely used and being developed rapidly. In the development of those sheet-handling machineries, it is important to predict the static and dynamic behavior of the sheet with a high degree of reliability because the sheets are fed and stacked at such a high speed. Flexible media are very thin, light and flexible, so they behave in geometric nonlinearity with large displacement and large rotation but small strain. In the flexible media analysis, aerodynamic effect from the surrounding air must be included because any small force can make large deformation. In this paper, only the flexible media analysis is performed as early stage of analysis including aerodynamic effect. Through formulations and simulations for total Lagrangian(TL), updated Lagrangian (UL) and co-rotational(CR) method which are widely used for geometric nonlinear analysis, usefulness and reliability of each methods are investigated.

• Journal of Korean Society of Steel Construction
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• v.19 no.6
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• pp.599-610
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• 2007

In this paper, we described a co-rotational formulation for the geometrical nonlinear analysis of three-dimensional frames. We suggested a new concept called the Zero-Twist-Section Condition (ZTSC) to decide the element coordinate system consistently. According to the ZTSC procedure, it is possible to obtain an element coordinate system and natural deformations consistently when finite displacements and rotations are induced in an element. Based on the developed procedure, numerical examples are investigated to calculate natural rotations while finite displacements are imposed on an element. Also, the developed co-rotational procedure gives accurate results in the analysis of post-buckling problems with finite rotations.

• Korean Journal of Applied Biomechanics
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• v.21 no.2
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• pp.181-187
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• 2011

The purpose of this study was to identify major factors on pirouette in ballet, and especially angle, Center of Mass(CM) & muscle activity aspects. The data were collected by using Motion Analysis System with 12 cameras to analyze kinematic variables with 120 Hz and Electromyography(EMG; 4,000 Hz) & Force Platform(1,000 Hz) to analyze kinetic variables. The subjects of this study were 8 female ballet dancers. The results as follow. First of all, full extension of knee joint and full plantar flexion of ankle joint appeared at the similar point. Secondly, in the rotational phase, total movement of segments in Good motion is smaller than that of Bad motion(in Good motion, head movement 2.70 cm, right shoulder movement 0.72 cm, left shoulder 4.26 cm, left wrist 17.4 mm smaller than Bad motion). Third, CoP distance of Good motion is 11.76 mm, and CoP distance of Bad motion is 11.76 mm, so Good motion is 5.98 mm smaller). Lastly, Pirouette need more retus femur activity than gastrocnemius activity in extention phase and rotation phase of support leg.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.9
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• pp.64-75
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• 2007

Photovoltaic systems utilize the infinite clean energy of the sun, without creating any air pollution or noise and mechanical vibration. A PV system operates without the need of fuel, rotation surfaces, high temperatures or high pressures. It is therefore to do maintain and simple to install as well as having a long life cycle. The global market for PV systems continues to grow rapidly by 30[%] per year. This paper suggests a new design method for the PV system installation that will allow to the improvement of system efficiency. This method is in accordance with the loss parameter compensation method designed for the PV systems and investigated through simulation and practical experimentation. It was applied to an interconnected 10[kW] grid PV system and was demonstrated in the field. Features such as solar array, PCS, system efficiency, performance and stability were considered. Through the proposed optimal parameter design method, the features of the system were studied, and the 10[kW] PV system was demonstrated and analyzed.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.2
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• pp.152-158
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• 2015

Unlike photovoltaic systems installed on land, photovoltaic systems applied to the offshore plant have the characteristic that is installed in a limited space. For single point mooring plant, it is advantageous in terms of a reliable power supply to be installed in different directions of photovoltaic panels, because it is not possible to identify the position of the sun by rotation of the plant itself. Differences of installation angle between photovoltaic panels make a difference of the intensity of radiation irradiated on each photovoltaic panel, and it brings loss of generation quantity due to the partial shading. In order to provide a photovoltaic system suitable for offshore plant, the modeling which contains multiple photovoltaic panels controlled by single controller is performed. Then, it was examined how the output characteristics of the photovoltaic system change about the difference of the intensity of radiation that varies depending on the altitude of the sun. Finally, through the simulation, a development model of the photovoltaic system which is suitable for offshore plant is suggested.

• The Journal of Korea Robotics Society
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• v.15 no.4
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• pp.341-349
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• 2020

Recently, interest in ground subsidence in urban areas has increased after a large sinkhole occurred near the high-story building area in Jamsil, Seoul, Korea, in 2014. If a massive sinkhole occurs in an urban area, it is crucial to assess its risk rapidly. Access to humans for on-site safety diagnosis may be difficult because of the additional risk of collapse in the disaster area. Generally, inspection using drones equipped with high-speed lidar sensors can be utilized. However, if the sinkhole is created vertically to a depth of 100 m, similar to the sinkhole in Guatemala, the drone cannot be applied because of the wireless communication limit and turbulence inside the sinkhole. In this study, a three-dimensional (3D) scanning system was fabricated and operated using a towed cable in a massive vertical sinkhole to a depth of 200 m. A high-speed lidar sensor was used to obtain a continuous cross-sectional shape at a certain depth. An inertial-measuring unit was applied to compensate for the error owing to the rotation and pendulum movement of the measuring unit. A reconstruction algorithm, including the compensation scheme, was developed. In a vertical hole with a depth of 180 m in the mining area, the fabricated system was applied to scan 0-165 m depth. The reconstructed shape was depicted in a 3D graph.

• Journal of the Institute of Convergence Signal Processing
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• v.11 no.1
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• pp.41-46
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• 2010

In this paper, the DoA(Direction of Arrival) estimator using unitary MUSIC algorithm is studied. The complex-valued correlation matrix of MUSIC algorithm is transformed to the real-valued one using unitary transform for easy implementation. The eigenvalue and eigenvector are obtained by the combined Jacobi-CORDIC algorithm. CORDIC algorithm can be implemented by only ADD and SHIFT operations and MUSIC spectrum computed by 256 point DFT algorithm. Results of unitary MUSIC algorithm designed by System Generator for FPGA implementation is entirely consistent with Matlab results. Its performance is evaluated through hardware co-simulation and resource estimation.