• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.9
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• pp.6247-6253
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• 2015

This paper presents the transient-response improved LDO regulator based on parallel error amplifiers. The proposed LDO regulator consists of an error amplifier (E/A1) which has a high gain and narrow bandwidth and a second amplifier (E/A2) which has low gain and wide bandwidth. These amplifiers are in parallel structure. Also, to improve the transient-response properties and slew-rate, some circuit block is added. Using pole-splitting technique, an external capacitor is reduced in a small on-chip size which is suitable for mobile devices. The proposed LDO has been designed and simulated using a Megna/Hynix $0.18{\mu}m$ CMOS parameters. Chip layout size is $500{\mu}m{\times}150{\mu}m$. Simulation results show 2.5 V output voltage and 100 mA load current in an input condition of 2.7 V ~ 3.3 V. Regulation Characteristic presents voltage variation of 26.1 mV and settling time of 510 ns from 100mA to 0 mA. Also, the proposed circuit has been shown voltage variation of 42.8 mV and settling time of 408 ns from 0 mA to 100 mA.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.5
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• pp.723-730
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• 2016

Solar cells in a PV module are connected in series and parallel to produce a higher voltage and current. The PV module has performance characteristics depending on solar radiation and temperature. In addition, the PV system causes power loss by special situations, including the shadows of the surrounding environment, such as nearby buildings and trees. In other words, an increase in power loss and a decrease in life cycle can occur because of the partial shadow and hot-spot effect. Therefore, this paper proposes the optimal configuration algorithm of a bypass diode to improve the output of a PV module and one of a PV array to minimize the loss of the PV array. In addition, this paper presents a model of a PV module and PV array based on the PSIM S/W. The simulation results confirmed that the proposed optimal configuration algorithms are useful tools for improving the performance of PV system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.11
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• pp.2689-2696
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• 2015

Radioactive isotopes which are manufactured using a cyclotron in a radioisotope used for radiation diagnosis is affected by the production yield according to size and shape of the beam and beam uniform degree from irradiated location when the proton beam investigated the target by cyclotron. Therefore, in this paper developed the BPM(Beam Profile Monitor) device capable of measuring the beam cross-section at the cyclotron beam line. It was configured so as to be able to remote control the BPM device in LabView and used the BPM program it was to be able to easily monitor and display to analyze the graph of two-dimensional graph and a three-dimensional beam distribution numerical information of the beam obtained while scanning the tungsten wire to the X and Y axis. The time it takes to measure the beam can be confirmed 37seconds when step motor driving speed was 2000pps. Through a beam readjusted based on the measured beam distribution information by optimizing the beam distribution it can be made to maximize the RI production yield and contribute supply stabilization.

• The Transactions of the Korean Institute of Power Electronics
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• v.15 no.2
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• pp.150-158
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• 2010

The operational characteristics of a resonant DC/DC converter, which can harvest thermoelectric energy, is analyzed, depending on the relative magnitudes of the input voltage and the load voltage. The resonant converter consists of LC resonant circuit connected to DC input source and a resonant pulse converter in which the input energy is transferred to the load as the resonant capacitor voltage is peak. The resonant capacitor doubles the input voltage by the resonance phenomenon. By the relative magnitude between the input voltage and the output voltage, the resonant DC/DC converter operates in three different modes. For boost mode, the peak voltage of the resonant capacitor is smaller than the load voltage. For hybrid mode, the peak voltage of the resonant capacitor is bigger than the load voltage and every switching period has both the boost mode and the direct mode. For the direct mode, the input voltage is bigger than the load voltage and the converter transfers directly the input energy to the load without the switching operation. Operation principles and the feasibility of the converter for the thermoelectric energy harvesting are verified with PSPICE simulation and experiment.

• Journal of Gifted/Talented Education
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• v.12 no.2
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• pp.31-56
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• 2002

Providing gifted education should be based on the principle of differentiation, that is, paying close attention to the individual characteristics of the gifted. The gifted are known to be the fast learners with autonomous studying ability and high levels of thinking and creativity, which certainly differentiate them from the ordinary others. Thus, the program for the gifted should fundamentally differ from other general programs. The need for gifted education is growing as our society has turned into the knowledge-based society. Fortunately, on December 28th, 1999, a law in favor of gifted education was passed. According to the law, gifted education will be actively provided under the government's support from the year 2002. In this context, this study is intended to search for the model of developing instructional materials for the gifted. The output materials of this study are to be used in gifted schools which will be built in the near future. The curriculum for the gifted consists of three parts: basic curriculum, in-depth curriculum, and optional curriculum. The learning and instructional materials developed in this study are to be used for the in-depth curriculum. In order to develop the materials, various theoretical models related to gifted education were reviewed. Finally, a theoretical model was developed. On the basis of the model, several instructional materials are developed and the possibility of application are considered.

• Korean Journal of Construction Engineering and Management
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• v.22 no.6
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• pp.3-14
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• 2021

In the Chinese construction industry, the utilization of Building Information Modeling (BIM) aims to increase the total output of the construction industry by solving the problem of inefficient interoperability in the construction industry. In 2011, the Chinese Ministry of Housing and Urban-Rural Development despite the technical advantages of BIM and the government policy, the BIM adoption rate in China is lower than 45%. Meanwhile, as the South Korean construction industry is a step ahead of its Chinese counterpart in introducing and utilizing BIM, it is expected that BIM is more actively utilized and accepted in South Korea than in China. According to a comparative study based on the hype-cycle theory, South Korea is at a more advanced stage of introducing BIM, than in China. This study aimed to suggest how to increase BIM utilization rates in China. To this end, this study comparatively analyzed factors affecting BIM acceptance between China and South Korea. For the comparative analysis of the BIM acceptance factors between China and South Korea, literature reviews on the technology acceptance model (TAM) and BIM acceptance model were carried out, and based on that, the BIM acceptance factors were classified. Other BIM acceptance factors were also added and considered, as they reflected Chinese national characteristics and construction industry. As for the derived BIM acceptance factors, construction project participants, especially actual BIM users in China and South Korea, were targeted for the survey. A t-test using SPSS 22.00 was carried out to identify significant differences in data. Finally, based on the t-test results, this study suggested ways of improving the BIM utilization rate in China. Based on the findings, this study is expected to contribute to activating BIM adoption in the Chinese construction industry and also to set a theoretical foundation for future studies on BIM utilization in the industry.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.44 no.3
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• pp.10-21
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• 2021

Recently, the demand for atypical structures with functions and sculptural beauty is increasing in the construction industry. Existing mold-based structure production methods have many advantages, but building complex atypical structures represents limitations due to the cost and technical characteristics. Production methods using molding are suitable for mass production systems, but production cost, construction period, construction cost, and environmental pollution can occur in small quantity batch production. The recent trend in the construction industry calls for new construction methods of customized small quantity batch production methods that can produce various types of sophisticated structures. In addition to the economic effects of developing related technologies of 3D Concrete Printers (3DCP), it can enhance national image through the image of future technology, the international status of the construction civil engineering industry, self-reliance, and technology export. Until now, 3DCP technology has been carried out in producing and utilizing residential houses, structures, etc., on land or manufacturing on land and installing them underwater. The final purpose of this research project is to produce marine structures by directly printing various marine structures underwater with 3DCP equipment. Compared to current underwater structure construction techniques, constructing structures directly underwater using 3DCP equipment has the following advantages: 1) cost reduction effects: 2) reduction of construct time, 3) ease of manufacturing amorphous underwater structures, 4) disaster prevention effects. The core element technology of the 3DCP equipment is to extrude the transferred composite materials at a constant quantitative speed and control the printing flow of the materials smoothly while printing the output. In this study, the extruding module of the 3DCP equipment operates underwater while developing an extruding module that can control the printing flow of the material while extruding it at a constant quantitative speed and minimizing the external force that can occur during underwater printing. The research on the development of 3DCP equipment for printing concrete structures underwater and the preliminary experiment of printing concrete structures using high viscosity low-flow concrete composite materials is explained.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.5
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• pp.263-270
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• 2021

In this study, a reliability-based design optimization of a 130-m class fixed-type offshore platform, to be installed in the North Sea, was carried out, while considering environmental, material, and manufacturing uncertainties to enhance its structural safety and economic aspects. For the reliability analysis, and reliability-based design optimization of the structural integrity, unity check values (defined as the ratio between working and allowable stress, for axial, bending, and shear stresses), of the members of the offshore platform were considered as constraints. Weight of the supporting jacket structure was minimized to reduce the manufacturing cost of the offshore platform. Statistical characteristics of uncertainties were defined based on observed and measured data references. Reliability analysis and reliability-based design optimization of a jacket-type offshore structure were computationally burdensome due to the large number of members; therefore, we suggested a method for variable screening, based on the importance of their output responses, to reduce the dimension of the problem. Furthermore, a deterministic design optimization was carried out prior to the reliability-based design optimization, to improve overall computational efficiency. Finally, the optimal design obtained was compared with the conventional rule-based offshore platform design in terms of safety and cost.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.4
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• pp.35-42
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• 2019

Nut fasteners that require ultra-precise control are required in the overall manufacturing industry including electronic products that are currently developing with the automobile industry. Important performance factors when tightening nuts include loosening due to insufficient fastening force, breakage due to excessive fastening, Tightening torque and angle are required to maintain and improve the assembling quality and ensure the life of the product. Nut fasteners, which are now marketed under the name Nut Runner, require high torque and precision torque control, precision angle control, and high speed operation for increased production, and are required for sophisticated torque control dedicated to high output BLDC motors and nut fasteners. It is demanded to develop a high-precision torque control driver and a high-speed, low-speed, high-response precision speed control system, but it does not satisfy the high precision, high torque and high speed operation characteristics required by customers. Therefore, in this paper, we propose a control technique of BLDC motor variable speed control and nut runner based on vector control and torque control based on coordinate transformation of d axis and q axis that can realize low vibration and low noise even at accurate tightening torque and high speed rotation. The performance results were analyzed to confirm that the proposed control satisfies the nut runner performance. In addition, it is confirmed that the pattern is programmed by One-Stage operation clamping method and it is tightened to the target torque exactly after 10,000 [rpm] high speed operation. The problem of tightening torque detection by torque ripple is also solved by using disturbance observer Respectively.

• Journal of Korea Technology Innovation Society
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• v.22 no.1
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• pp.119-157
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• 2019

It is important for the people in the 3D printing industry to determine which factors influence the decision-making that determine the adoption of 3D printers and the role of the factors. Through this, we intend to find ways to contribute to the development of 3D printing industry in Korea by increasing utilization of 3D printer used in domestic companies and increasing investment in related industries. 3D printers are making rapid progress according to the development of technology, the public interest, and the activation of investment. Foreign countries have made remarkable progress in equipment, materials, software, and industrial applications, but they are lower than expected in Korea. It is necessary to introduce a smooth 3D printer in order to revitalize the 3D printer industry and enlarge the base, but it is insufficient for actual introduction and field application. The independent variables that represent economic, technological, and environmental characteristics were selected through a literature survey, and a model for accepting integrated technology for convergence of societies in the 3D printing industry was proposed. This study confirms that economic factors such as output unit price, government support, and environmental factors such as 3D contents should be developed organically for the introduction of 3D printing technology and equipment. This require systematic and effective support from the government, and it is necessary to improve the economic support, related laws, and systems that can be directly experienced by the user as a user. As the domestic 3D printing industry develops with economic, technological and time investment, 3D printing industry should be the key engine of the 4th industrial revolution.