• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.10a
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• pp.93-99
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• 2012

This paper presents an optimal design of magnetorheological (MR) fluid based mount (MR mount in short) which can be applicable to vibration control of diesel engine of ship. In this work, a mixed - mode including squeeze mode, flow mode and shear mode is proposed and designed. In order to determine actuating damping force of MR mount required for efficient vibration control, excitation force from diesel engine is analyzed. In this analysis, a model of V-type engine is considered and the relationship between velocity and pressure of gas in torque of the piston is derived. Subsequently, by integrating the field-dependent rheological properties of commercially available MR fluid with the excitation force an appropriate size of MR mount is designed. In addition, in order to achieve maximum actuating force with geometric constraints design optimization is undertaken using ANSYS software. Through the magnetic density analysis, optimal design parameters such as bottom gap and radius of coil are determined.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.77-77
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• 2011

These days, a growing demand for memory device is filled up with the flash memory and the dynamic random access memory (DRAM). Although DRAM is a reasonable solution for current demand, the universal novel memory with high density, high speed and nonvolatility, needs to be developed. Among various new memories, the magnetic random access memory (MRAM) device is considered as one of good candidate memories because of excellent features including high density, high speed, low operating power and nonvolatility. The etching of MTJ stack which is composed of magnetic materials and insulator such as MgO is one of the vital process for MRAM. Recently, MgO has attracted great interest in the MTJ stack as tunneling barrier layer for its high tunneling magnetoresistance values. For the successful realization of high density MRAM, the etching process of MgO thin films should be investigated. Until now, there were some works devoted to the investigations on etch characteristics of MgO thin films. Initially, ion milling was applied to the etching of MgO thin films. However, ion milling has many disadvantages such as sidewall redeposition and etching damage. High density plasma etching containing the magnetically enhanced reactive ion etching and high density reactive ion etching have been employed for the improvement of etching process. In this work, inductively coupled plasma reactive ion etching (ICPRIE) system was adopted for the improvement of etching process using MgO thin films and etching gas mixes of $CH_4$/Ar and $CH_4$/$O_2$/Ar have been employed. The etch rates are measured by a surface profilometer and etch profiles are observed using field emission scanning emission microscopy (FESEM). The effects of gas concentration and etch parameters such as coil rf power, dc-bias voltage to substrate, and gas pressure on etch characteristics will be systematically explored.

• Proceedings of the KIEE Conference
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• 1995.07b
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• pp.761-765
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• 1995

The old Timing Controller for Control Element Drive Mechanism (CEDM) is designed as an open loop control system because it is difficult to mount sensors within the Control Element Drive Mechanism(CEDM) which is operating under the pressure boundary of the reactor vessel. In this work new method which can be used to detect the CEDM operational conditions without mounting sensors within the CEDM housing is developed in order to resolve problems of the old Timing Controller. By using the developed new method, the new Timing Controller for the CEDM is designed as a closed loop controller which has features of the control rod drop prevention, fine position control and the coil life time extension. The algorithm developed under closed loop control concept resolves most problems occurred in the old Timing Controller and improves the performance and reliability of the system. During designing and testing of the Timing Controller algorithm, the real time CEDM simulator developed here was used. And all functions of the developed algorithm were verified using CEDM simulator with the real data collected from the site. The results show that the Timing Controller performs its intended functions properly.

• KSBB Journal
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• v.21 no.2
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• pp.129-132
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• 2006

The importance of natural preservative has increased in recent years. The natural preservatives have been used in the field of foods, cosmetics and pharmacology. In the present work Artemisia sp., well recognized for their effect of antimicrobial activity, were extracted by methanol and water sequentially for selecting only water-soluble compounds that can be used as additives in food and cosmetics. Antimicrobial activities of water extracts from stem and leaf of Artemisia princeps var. orientalis were investigated by the disc diffusion method. Two gram positive bacteria(Staphylococcus aureus and Bacillus subtilis) and three gram negative bacteria(Escherichia coil, Agrobacterium tumefaciens and Pseudomonas putida) were used for antimicrobial activity studies. The water-soluble compounds from methanol extract showed higher antimicrobial activity than only water extract to these bacteria. Comparative evaluation of water-soluble metabolite profiles with caffeic acid that is known as an antimicrobial compound from Artemisia sp. was performed by high performance liquid chromatography with photo-diode array detection.

• KIEAE Journal
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• v.16 no.4
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• pp.41-46
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• 2016

Purpose: This is a study on the planning of temporary housing for post application of Mega Sports facilities. The subject of the study is 2018 Pyeongchang Winter Olympics, which is to suggest building an alternative temporary housing using shipping containers(high cube), which solve the lack of accommodations and recycle temporary housing after Olympics, save money and be eco-friendly in Olympics. Method: This study includes this ; research on the a fact-finding survey about Mega sports facilities post application and demand survey on 2018 Pyeongchang Winter Olympics accomodations and an analysis about temporary housing plan. Furthermore we decided temporary housing building plan by analyzing residents' needs and traits of the housing etc. Through this, we made a schematic design for household units. Result: As a result, this study is a plan of making space, forms, and structure. The planned size is $38.4m^2$(L:12m, W:3.2m) except balcony, and indoor height is 2.5m. The space consists of entrance, bathroom, bedroom and living room with folding furniture system. Also there's a detailed floor plan of the ceiling, wall, and floor we drew up. The ceiling and wall consist of dampproof film, noncombustible board, fire proof urethane form, and color-designed sheet. The floor is composed of floor tile, cement mortar, light concrete(with heat coil), insulation, and dampproof film. Additionally, this study is a plan of interior dry wall with detail using modular construction method for work efficiency and quality improvement.

• Journal of Power Electronics
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• v.11 no.5
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• pp.759-766
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• 2011

This paper focuses on monitoring and predicting the short circuit faults of the rotor windings of large turbo-generator systems. For the purpose of increasing efficiency and decreasing maintenance cost, a method that combines the HHT (Hilbert Huang Transform) with a wavelet has been studied. This method is based on analyzing a classical Albright detecting coil. Due to the Empirical Mode Decomposition (EMD) and the Intrinsic Mode Functions (IMF) of the HHT the exact location of a short circuit of rotor windings may be given. However, a part of the useful information is eliminated by the unreasonable decomposing scale of the wavelet. Based on the thermodynamics modeling method, this study was illustrated with a 50MW turbo-generator system that is installed in Northern China. The analysis results, which have very good agreement with those of a previous study, show that the method of combining the HHT with a wavelet is an effective way to analyze and predict the short circuit faults of the rotor windings of large generators, such as supercritical turbo-generator systems and wind turbo-generator systems. This work can offer a useful reference for analyzing smart grids by improving the power quality of a distribution network that is supplied by a turbo-generator system.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.16 no.6
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• pp.51-59
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• 2002

This paper deals with the measurement and analysis of the induced voltages and magnetic fields caused by the operation of home appliances. The induced voltage and magnetic field measurement circuit used in this work consists of the induction coil, the operational preamplifier and the active integrator. Television set and monitors for personal computer cause strong magnetic fields rich in harmonics and high induced voltages by using the switching power suppliers. The strong magnetic field intensity and high induced voltage were created by 14" television set, and their values are 2.1 ［$\mu$Tp-p］and 140 ［mVp-p］at the distance of 0.4 ［m］, respectively. However, the induced voltage per unit magnetic field intensity was created by 17" monitor for personal computer and the measured data was approximately 560［mV/$\mu$T］at the same distance. distance.

• Journal of the Korean Society of Safety
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• v.36 no.2
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• pp.10-17
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• 2021

This paper presents the robust design of each component used in the development of an induction bolt heating system for dismantling the high-temperature high-pressure casing heating bolts of turbines in power plants. The induction bolt heating system comprises seven assemblies, namely AC breaker, AC filter, inverter, transformer, work coil, cable, and CT/PT. For each of these assemblies, the various failure modes are identified by the failure mode and effects analysis (FMEA) method, and the causes and effects of these failure modes are presented. In addition, the risk priority numbers are deduced for the individual parts. To ensure robust design, the insulated-gate bipolar transistor (IGBT), switched-mode power supply (SMPS), C/T (adjusting current), capacitor, and coupling are selected. The IGBT is changed to a field-effect transistor (FET) to enhance the voltage applied to the induction heating system, and a dual-safety device is added to the SMPS. For C/T (adjusting current), the turns ratio is adjusted to ensure an appropriate amount of induced current. The capacitor is replaced by a product with heat resistance and durability; further, coupling with a water-resistant structure is improved such that the connecting parts are not easily destroyed. The ground connection is chosen for management priority.

• Safety and Health at Work
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• v.11 no.4
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• pp.537-542
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• 2020

Background: Personal protective equipment (PPE) has been designed in such a way to reduce accident rates. Unfortunately, existing PPE is rather ineffective as it is not able to provide warning signals when hazard is around. The integration of intelligent systems is envisaged to increase the efficiency of existing PPE. Methods: This project designed a safety vest incorporated with metal detectors which can provide immediate warning to the field workers when there is metal hazard around. This product has greater freedom of design via smart manufacturing as it involves the assembly of few commercially available parts into a single entity. Briefly, the metal detector is a do it yourself (DIY) kit, and the safety vest is purchasable from any local market. The DIY kit was connected to a copper coil and being sewed into the safety vest. Results: The metal detector induces beeping sound when there is metal hazard around. A total of 121 engineering students were introduced to the prototype before being requested to answer a survey associated with the design. Respondents have rated >3.00/5.00 for the design simplicity, ease of usage, and light weight. Meanwhile, respondents suggested that the design should be further improved by increasing the metal detection range. Conclusion: It is envisaged that the introduction of this smart safety vest will allow the workers to carry out their duties securely by reducing the accident rates. Particularly, such design is expected to reduce workplace accident especially during night time at construction sites where the visibility is low.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.6
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• pp.34-42
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• 2000

Recently, there is a growing need to develope small-size RF chip inductors operating to GHz to realize high-performance, micro-fabricated wireless communication products. For the development of high-performance RF chip inductors, however, the ferrite-based chip inductors can not be used above 300MHz due to the limitation of the permeability of this material. In this work, small-size, high-performance RF chip inductors utilizing amorphous $Al_2O_3$ core material were investigated. Copper (Cu) with 40${\mu}m$ diameter was used as the coils and the chip inductor size fabricated in this work is $2.1mm{\times}1.5mm{\times}1.0mm$. The external current source was applied after bonding Cu coil leads to gold pads electro-plated on the bottom edges of a core material. The composition of core materials was measured using a EDX. High frequency characteristics of the inductance (L), quality factor (Q), and impedance (Z) of developed inductors were measured using an RF Impedance/Material Analyzer (HP4291B with HP16193A test fixture). The developed inductors have the self-resonant frequency (SRF) of 1 to 3.5 GHz and exhibit L of 22 to 150 nH. The L of the inductors decreases with increasing the SRF. The Z of the inductors has the maximum value at the SRF and the inductors have the quality factor of 70 to 97 in the frequency range of 500 MHz to 1.5 GHz.