• Journal of the Korean Society of Safety
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• v.20 no.3 s.71
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• pp.47-52
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• 2005

Recently, power conversion equipment increased rapidly makes a lot of harmonics. Thus, it is growing that wrong operation and break down of sensitive devices. There are two kinds of causes of harmonics. One of them is lots of power conversion equipment as modem controller, inverter, converter and SWS(Switching Mode Power Supply). Another is nonlinear operating machines as transformer and motor. The more nonlinear loads like them grow, the more serious problems as harmonic current to source and low power factor because of increasing reactive power grow. It is installed for reactor and L-C Filter to decrease harmonic in general. This paper analysis and compares two of characteristics and harmonic from reactor and L-C Filter with operation of induction motor and power conversion equipment. In the result, L-C Filter more improves unbalance rate and THD than reactor.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.12
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• pp.30-37
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• 1995

The mechanical seals, which are installed in rotating machines like pump and compressor, are gengrally used as sealing devices in the many fields of industries. The failure of mechanical seals such as leakage,fast and severe wear, excessive torque, and squeaking results in big problems. To monitor the failure of mechanical seals and to propose the proper monitoring techniques with artificial neural network, sliding wear experiments were conducted. Torque and temperature of the mechanical seals were measured during experiments. Optical microstructure was observed for the wear processing after every 10 minute sliding at rotation speed of 1750 rpm and scanning electron microscopy was also observed. During the experiment, the variation of torque and temperature that meant an abnormal phenomenon, was observed. That experimental data recorded were applied to the developed monitoring system with artificial neural network. This study concludes that torque and temperature of mechanical seals wil be used to identify and to monitor the condition of sliding motion of mechanical seals. An availability to monitor the mechanical seal failure with artificial neural network was confirmed.

• Journal of information and communication convergence engineering
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• v.20 no.1
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• pp.16-21
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• 2022

In this research, we create a network infrastructure based on a service-oriented infrastructure (SOI) for the virtualization technology and integrate it with a cloud technology that applies the cloud integration management platform (CIMP) concept. In CIMP, the server and storage will be separated. The server will be adopted for virtualization while the storage will be used by students and teachers to store data. As long they save their data in the storage module, every time, everywhere, and on every device, they can access their data. This research will implement the design of the network infrastructure and be applied to the remote practical learning system in the laboratory. Students and teachers will ultimately adopt this network infrastructure for remote practice using their respective devices without physically meeting in the laboratory. In the future, if the implementation phase is successful, then in addition to laboratory environments, it can be implemented in all learning activities at our campus.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.4
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• pp.343-351
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• 2014

Washing machines designed to clean laundry have been more widely used at home as they reduce household labor and boost the quality of life. Technological advances and better standards of life increase demand for laundry washing performance. Energy efficiency regulations and consumer demand for the larger trend, washing machine makers should be done in performance studies to reduce power, and water consumption and the load on power transmission devices. In this study, performance of a fully automatic washing machine with unconstrained transmission is analyzed through experiment and CFD simulation. It is found that the interaction between laundry and transmission change the washing behavior and affect washing performance with regard to the degree of freedom. The results obtained in this study can be used in developing new washing machine transmissions and make them more robust.

• Journal of Korea Multimedia Society
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• v.20 no.3
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• pp.511-519
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• 2017

This Paper introduces the design and communication method between PLC (Programmable Logic Controller) and Arduino based on MODBUS Protocol. MODBUS connection can be established in a new or existing system very easily, therefore we used this protocol in our proposed system. In the field of automatic devices, multi-function serial port such as RS232, RS422, RS485, and so on creates a great convenience to the developer. This proposed system used RS485 as a key mediator for data exchanging on a connected network. We also believe that it will reduce the development cost in various automated industry because this system can be reused or can be implemented any such PLC installed machines. RS485 is used as a communication interface between PLC (as a slave) and Arduino (as a master), through which a reliable network is created for safe and fast communication. Furthermore, RS485 allows multiple devices(up to 32) to communicate at half duplex on a single pair of wires and provides a long connectivity area (up to 1200 meters) as compare to other device, which makes it a user-friendly for various devices in the automated industry. Moreover, Arduino can play as a mediator by connecting third party device and setup a communication network with PLC.

• Progress in Superconductivity and Cryogenics
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• v.10 no.2
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• pp.1-11
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• 2008

The application of bulk superconducting materials to electrical power systems is very attractive because bulk high temperature superconductors offer excellent electromagnetic properties. In recent years there has been significant progresses in the research and fabrication of superconducting bulk materials. Numerous efforts have been made worldwide to make bulk YBCO as a replacement of the conventional magnets to produce larger magnetic field and hence to improve the device performance in electrical power applications. This paper gives a comprehensive review of different applications of bulk HTS materials, concentrating in three areas including superconducting bearing, superconducting motors and high field magnets. The advantages of applying superconducting material into each application are analysed. The status of current research in each section is summarized and examples are given to demonstrate how YBCO bulk materials can benefit the design of electrical devices. Several numerical models which calculate the electromagnetic properties of bulk superconductors are introduced and finally the article concludes with a review on the studies of the demagnetisation effect in superconducting bulk magnets which is extremely relevant to applying superconducting technology to rotating machines.

• Journal of Korean Critical Care Nursing
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• v.16 no.2
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• pp.28-41
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• 2023

Purpose : This study aimed to investigate the characteristics and risk factors associated with pressure injuries related to medical devices among patients admitted to the intensive care unit (ICU). Method : A retrospective study analyzed data from 462 ICU patients. Statistical analyses, including independent t-tests, Fisher's exact tests, and logistic regression were performed to analyze the data. Results : Among the 154 subjects, there were a total of 198 medical device-related pressure injuries (MDRPI). Stage 2 and deep tissue pressure injuries were the most frequent. MDRPI occurred most frequently on the face, with nasogastric tubes being its leading cause, followed by endotracheal tubes. The risk factors for MDRPI included male sex (odds ratio [OR]=1.78, 95% confidence interval [CI]=1.12-2.83), department at the time of ICU admission (OR=4.29, 95% CI=2.01-9.15), post-surgery ICU admission (OR=0.43, 95% CI=0.25-0.73), application of extracorporeal membrane oxygenation machines (OR=2.72, 95% CI=1.06-6.95), number of medical devices (OR=1.16, 95% CI=1.05-1.30), inotropic drug administration (OR=2.33, 95% CI=1.19-4.60), and sedative use (OR=2.53, 95% CI=1.17-5.45). Conclusion : These results enable the determination of the characteristics and risk factors associated with MDRPI. It is crucial to acknowledge the risk factors for MDRPI in ICU patients and establish a prevention strategy.

• International Journal of Contents
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• v.11 no.4
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• pp.70-76
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• 2015

The development of technology provides and increases security as well as convenience for humans. The development of new technology directly affects the standard of life thanks to smart home automatic control systems. This paper describes a door control, automatic curtain, home security (CCTV, fire, gas, safe, etc.), home control (energy, light, ventilation, etc.) and web-based smart home automatic controller. It also describes the use of ARM (Advanced RISC Machines) for automatic control of home equipment, a Multi-Axes Servo Controller using FPGA (Field Programmable Gate Array) and PLC (programmable logic controller). Additionally, it describes the development of a HTML editor using web auto control software. The tab loading time (7 seconds) is faster when using ARM-based web browser software instead of Chrome and Firefox is used because the browser has a small memory footprint (300M). This system is realized by web auto controller language which controls and uses PLCs that are easier than existing devices. This smart home automatic control technology can control smart home equipment anywhere and anytime and provides a remote interface through mobile equipment.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.10 no.5
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• pp.350-355
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• 2000

The fabrication of sapphire wafer in C plane has been developed by horizontal Bridgeman method and GaN based semiconductor epitaxial growth has been carried out in metal organic chemical vapour deposition. The single crystalline ingot of sapphire has been utilized for 2 inch sapphire wafers and wafer slicing and lapping machines were designed. These several steps of lapping processes provided the mirror-like surface of sapphire wafer. The measurements of the surface flatness and the roughness were carried out by the atomic force microscope. The GaN thin film growth on the developed wafer was confirmed the wafer quality and applicability to blue light emitting devices.

• Journal of Korea Society of Digital Industry and Information Management
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• v.10 no.4
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• pp.1-9
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• 2014

Recently, with the enlargement of cloud computing, virtual desktop infrastructure(VDI) can be an alternative of the existing personal computer based information environment. For the case of partially introduced VDI coexisting with personal computer environment, we suggest a virtual folder based approach to control the overall digital contents within an organization with a case of implementation. Although a centralizing device was used for storage and sharing of organization's digital contents, it was not easy to accomplish centralizing digital contents completely. It is tried to prevent users from utilizing their own storage in their personal computers or virtual machines and to use virtual folder which transfer and store digital contents to and in EDMS. The virtual folder system of this paper looks like a real folder in a personal computer, but it is another virtual device for outer storage devices including EDMS. It can be an alternative and reference of digital contents control for future applications of cloud computing.