• Journal of the Korea Convergence Society
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• v.8 no.12
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• pp.15-22
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• 2017

This paper analyzes vulnerability of each service protocol used in ICT convergence industry, smart factory, smart grid, smart home, smart traffic, smart health care, and suggests technologies that can overcome security vulnerabilities. In addition, we design a service-oriented protocol security framework that allows us to quickly and easily develop security functions in an open environment by defining a security element common to protocols and designing a security module for each protocol layer including the corresponding elements. Service protocol independent security module and specialized security module, it will be possible to develop flexible and fast security system in ICT convergence industry where various protocols are used. The overall security level of the ICT service network can be improved by installing the necessary security modules in the operating system, and the productivity can be improved in the industrial security field by reusing each security module.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.3
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• pp.274-283
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• 2006

The Permanent Magnet Synchronous Motor(PMSM) drive systems with ball-screw, gear and timing-belt are widely used in industrial applications such as NC machine, machine tools, robots and factory automation. These systems have torsional vibration in torque transmission from servo motor to mechanical load due to the mechanical couplings. This vibration makes it difficult to achieve quick responses of speed and may result in damage to the mechanical plant. This paper presents adaptive notch filter with auto searching function of vibration frequency to reject the mechanical vibration of linear feeder system with PMSM. The proposed adaptive notch filter can suppress the torque command signal of PMSM in the resonant bandwidth for reject the mechanical torsional vibration. However, the resonant frequency can vary with conditions of mechanical load system and coupling devices, adaptive notch filter can auto search the vibration frequency and suppress the vibration signal bandwidth. Computer simulation and experimental results shows the verification of the proposed adaptive notch filter in linear feeder system with PMSM.

• The Journal of Bigdata
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• v.1 no.2
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• pp.9-19
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• 2016

Since ICT convergence became a major issue, German government has carried forward a policy 'Industry 4.0' that triggered ICT convergence with manufacturing. Now this trend gets into our stride. From this facts, we can expect great leap up to quality perfection in low cost. Recently Korean government also enforces policy with 'Manufacturing 3.0' for upgrading Korean manufacturing industry with being accelerated by many related technologies. We, in the paper, developed a custom-made operational big data analysis platform for the implementation of operational intelligence to improve industry capability. Our platform is designed based on spring framework and web. In addition, HDFS and spark architectures helps our system analyze massive data on the field with streamed data processed by process mining algorithm. Extracted knowledge from data will support enhancement of manufacturing performance.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.3
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• pp.343-348
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• 2013

In line with the advances in factory automation, various pieces of equipment are now operated in batch processes controlled by computers. However, many kinds of faults can occur in complicated and large systems, which can result in low productivity and economic loss. The reliability and safety of systems have been studied because of the difficulty of determining the severity and location of faults. Therefore, it is necessary to detect and diagnose such faults in order to guarantee the reliability and safety of the equipment. In this paper, a diagnosis method for the ball bearings of a hydraulic pump is applied using a vibration signal for the maintenance of injection molding equipment. The bearings' defects are selected as a main failure mode through a failure mode and effect analysis (FMEA). Usually, there are nonlinear and impulse components of vibration in a ball bearing with faults. For the effective fault diagnosis of a ball bearing, nonlinear diagnostic methods and time-frequency analysis are applied, in addition to the methods currently used, such as power spectrum, time series analysis, and statistical methods. As a result of this study, a failure diagnosis system is provided that is useful even for non-experts. This is a condition-based method that makes it possible to resolve problems in a timely and economical way, in contrast to the prior method, which required regular but wasteful maintenance based on the experience of expensive external experts.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.4
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• pp.62-70
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• 2005

This paper presents the actual conditions and reform measures of voltage and current harmonics being made in low-voltage power systems supplying various loads. The measurements were carried out at the secondary output terminals of 22.9[kV]/380[V]220[V] customer's transformers, and the results were discussed on the basis of the comparison with IEEE and IEC harmonics control standards. The voltage THDs of the power systems employed in this survey were less than $5[\%]$ that is considered to be acceptable. On the contrary, the current distortions were significantly greater than the voltage distortions, and the current THDs were distributed over the wide-range from 15.7 to $60.4[\%]$. In particular, the current distortion on the low voltage power lines of office buildings in which many PC and fluorescent lamps are used is remarkably more serious than that of factory facilities. As a result, the voltage distortion factors are observed within the range of its allowable level or less than the limits, but the current distortion factors are significantly greater than the limits of IEEE and IEC standards.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.4
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• pp.403-410
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• 2016

Materials made of metals have their own manifest resonant frequencies. Using this property, the quality test of products from the factory can be performed. An impact is applied to the product and the frequencies of the sound and/or vibration are measured using high-end equipments. They use a general purpose computer or a DSP(: Digital Signal Processor)-based stand-alone system which is usually too large in-size to carry and expensive to build. In this paper, we introduce a system that is developed based on a MSP430 MCU(:Micro-Controller Unit) from TI(: Texas Instruments). The ultra-low power MSP430 MCUs make it possible to make a frequency analyzer in a very small size without the need of using a large-size battery. The proposed system can be used in situations where the frequency analyzer should be carried easily with an investigator and should be built at low cost sacrificing some accuracy. We implemented the system using a launchpad supplied by TI and could confirm that the proposed system could identify with a high-accuracy the frequencies of various artificial and natural sounds.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.6
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• pp.1089-1096
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• 2019

Recently, small-scale IoT services using a small amount of information through low-performance computing have been spread. It requires low cost, low-power, and long-distance communication technologies with wide communication radius, relatively low power consumption. This paper proposes a MAC layer and routing protocol that supports multi-hop transmission in small-scale IoT environment distributed over a large area based on LoRa communication and delivering a small amount of sensing data. The terminal node is mobile and the communication type provides bidirectional transmission between the terminal node and the network application server. By applying the proposed protocol, a production line monitoring system for smart factory was implemented. It was confirmed that the basic monitoring functions are normally performed.

• Journal of the Korean Institute of Gas
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• v.10 no.4 s.33
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• pp.34-40
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• 2006

This paper provides a fusion technology between a district cooling energy system and an environment conservation policy based on the energy savings and reusable cold energy resources. The district heating and cooling systems are very effective ways for an energy saving, a cost reduction and a safety control. It is necessary to equalize the energy savings and an environmental preservation policy for an improved human lift. A gasification process of a liquefied natural gas, cooling water from deep seawater and an ice water thermal storage system may produce a cold energy. A district cooling system is used to cool an apartment, office buildings and factory facilities with a cooling energy supply pipeline. LNG cooling energy will switch a conventional air-conditioning system, which is operated by on electrical energy and a Freon refrigerant. Coincident with significant clean energy and operating cost savings, LNG cold energy system owen radical reductions in an air-borne pollutant, $CO_2$ and the release of environmentally harmful refrigerants compared with that of the conventional air-conditioning system. This study provides useful information on the fusion technology of a LNG cold energy usage and energy savings, and environmental conservation.

• Journal of the Korean Society of Clothing and Textiles
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• v.39 no.6
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• pp.877-884
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• 2015

Polytrimethylene Terephthalate (PTT) is an eco-fiber with good elastic properties; however, it requires more detailed studies related to spinnability according to blending of various kinds of fibers. The evolution of spinning technology was focused on improved productivity with good quality; in addition, air vortex spinning was recently invented and applied on the spinning factory as the facility with good productivity and quality. More detail spinning technology according to the blending of various kinds of fibers on the air vortex spinning system is required to obtain good quality yarns for high emotional fabrics. In this paper, the physical properties of air vortex, compact and ring staple yarns using PTT/wool/modal blend fibers were investigated with yarn structure to promote high functional PTT that includes fabrics for high emotional garments. Unevenness of air vortex yarns was higher than those of compact and ring yarns; in addition, imperfections were greater than those of compact and ring yarns, which was attributed to a fascinated vortex yarn structure. Tenacity and breaking strain of air vortex yarns were lower than those of compact and ring yarns, caused by higher unevenness and more imperfections of air vortex yarns compared to compact and ring yarns. Vortex yarns showed the highest initial modulus and ring yarns showed the lowest ones which results in a stiff tactile feeling of air vortex yarns in regards to the initial modulus of yarns. Dry and wet thermal shrinkages of air vortex yarns were lower than ring yarns. Good shape retention of vortex yarns was estimated due to low thermal shrinkage.

• Journal of the Korean Society for Advanced Composite Structures
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• v.6 no.2
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• pp.8-16
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• 2015

Prestressed concrete (PSC) is a method in which prestressed tendon is placed inside and/or outside the reinforced concrete member and the compressive force applied to the concrete in advance to enhance the engineering properties of concrete member which is weak under tension. In this paper we suggested the precast PSC girder assembled with segments of portable size and weight at the factory. The segments of precast PSC girder will be delivered and assembled as a unit of PSC girder at the site. Consequently, we suggested new-type of precast segmented PSC girder with different shapes of segment cross-section (i.e., I-shape, Box-shape). To mitigate the problems associated with the field splice between the segments of precast PSC girder anchor system is attached near the neutral axis of the girder and relatively uniform compression throughout the girder cross-section is applied. Prior to the experimental investigation, analytical investigation on the structural behavior of precast PSC girder was performed and the serviceability (deflection) and safety (strength) of the girder were confirmed. In addition, 4-point bending test on the girder was conducted to investigate the structural performance under bending. From the experimental investigation, it was found that the precast PSC girder spliced with 3 and 5 segments has sufficient in serviceability and safety conditions and it was also observed that the point where the segments spliced has no defects and the girder behaves as a unit.