• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.1
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• pp.81-88
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• 2016

Recently, high-efficiency machining in the production of high-value products with complex shapes has constantly been required along with the need for hybrid machining. In this study, in addition to wire-cut Electric Discharge Machining (EDM) and vibration, we present the possibility of a hybrid process by carrying out an experiment with aluminum alloy, and the hybrid process determines the nature of the surface. The selected experimental parameters are waveform, amplitude, peak current, and two-dimensional (2D) vibration. The experimental results give the guideline for selecting reasonable machining parameters. The surface roughness was improved about 20% with increases in the amplitude of the vibration.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.4
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• pp.100-107
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• 2015

Recently, high-efficiency machining in the production of high-value products with a complex shape has constantly been required with the need for hybrid machining. In this study, in addition to the wire-cut E.D.M. and vibration used to present the possibility of a hybrid process by carrying out the aluminum alloy experiment, the hybrid process determines the nature of the surface. The selected experimental parameters are horizontality, waveform, amplitude, peak current, and frequency. The experimental results give guidelines for selecting reasonable machining parameters. The surface roughness was improved by about 20% with increases in the amplitude of the vibration.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.4
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• pp.104-112
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• 2017

In the sand casting process, the flow of liquid metal affects the quality of casting products and their die life. To determine the optimal bush part design process, this study performed various analyses using commercial finite element analysis S/W. The simulation focused on the molten metal behaviors during the mold filling and solidification stages of sand casting. This study aims to develop methods to reduce the cost and increase the tool life of the continuous hot zinc plating roll.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.10
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• pp.952-959
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• 2004

The hybrid liquid desiccant air conditioning system has been in use for many years, primarily in industrial process applications requiring dehumidification and humidity control. In this study, the hybrid dehumidifier has been designed to study the dehumidification characteristic of the aqueous triethylene glycol (TEG) solution. The experimental results show energy efficient characteristics of hybrid liquid desiccant air conditioning system compared with the refrigeration system in terms of energy use, the difference of pressure loss between hybrid liquid desiccant air conditioning system and refrigeration system. Data obtained are useful for design guidance and performance analysis of the hybrid air conditioning system.

• Journal of the Korean institute of surface engineering
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• v.51 no.6
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• pp.387-392
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• 2018

Nanopatterning is one of the essential nanotechnologies to fabricate electronic and energy nanodevices. Therefore, many research group members made a lot of efforts to develop simple and useful nanopatterning methods to obtain highly ordered nanostructures with functionality. In this study, in order to achieve pattern formation of three-dimensional (3D) hierarchical nanostructures, we introduce a simple and useful patterning method (nano-transfer printing (n-TP) process) consisting of various linewidths for diverse materials. Pt and $WO_3$ hybrid line structures were successfully stacked on a flexible polyimide substrate as a multi-layered hybrid 3D pattern of Pt/WO3/Pt with line-widths of $1{\mu}m$, $1{\mu}m$ and 250 nm, respectively. This simple approach suggests how to fabricate multiscale hybrid nanostructures composed of multiple materials. In addition, functional hybrid nanostructures can be expected to be applicable to various next-generation electronic devices, such as nonvolatile memories and energy harvesters.

• International Journal of Naval Architecture and Ocean Engineering
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• v.13 no.1
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• pp.674-690
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• 2021

This study proposes a hybrid marine power system combining dual-fuel generators, a fuel cell, and Vanadium Redox Flow Batteries (VRFB). Rigorous verification and validation of the dynamic modelling and integration of the system are conducted. A case study for the application of the hybrid propulsion system to a passenger ship is conducted to examine its time-variant behaviour. A comprehensive model of the reversible and irreversible capacity degradation of the VRFB stack unit is proposed and validated. The capacity retention of the VRFB stack is simulated by being integrated within the hybrid propulsion system. Reversible degradation of the VRFB stack is precisely predicted and rehabilitated based on the predefined operational schedule, while the irreversible portion is retained until the affected components are replaced. Consequently, the advantages of the VRFB system as an on-board ESS are demonstrated through the application of a hybrid propulsion system for liner shipping with fixed routes.

• Journal of Information Technology Services
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• v.13 no.4
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• pp.19-43
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• 2014

Categorization means the process labeling or identifying an object based on what people already know or its similarity for people to be easily perceptible in external environment. If it is categorized, it is schematically conjectured from typical characteristic of the category. In this sense, the categorization of new products has an important effect upon the market performance. Nevertheless, the categorization of innovative new products is not easy and occasionally very ambiguous. In this study, we discuss how to strengthen the categorization strategy of new hybrid IT products through complementary bundling. The model of this study is based on Technology Acceptance Model (TAM) with resistance variable and verifies the statistical significance by undertaking a survey on consumers' awareness. In addition, we review the moderating effects of prior knowledge in the adoption process of complementary bundling. Through this analysis, we find out the structural relationship among the factors affecting adoption of complementary bundling. Also, it show that the influence of prior knowledge in respect of the adoption process is greater than others in case that there exists significant heterogeneity among strategic categories and complements. In conclusion, these findings suggest the following managerial implication. The categorization strategy of new hybrid IT product can be enhanced by complementary bundling, but the suitability among strategic category and complements should be evaluated exhaustively.

• Journal of Korea Foundry Society
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• v.38 no.3
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• pp.60-65
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• 2018

In the present study, the characteristics of Mg inverter cases for hybrid cars are investigated. Concerns over the use of lightweight materials to reduce energy use and to mitigate emission problems are inevitable in the twenty-first century. Magnesium is a promising material for the manufacturing of lightweight parts. Several cases for thermal cooling channels have been designed and simulated, and the effects of materials and coatings on the thermal cooling efficiency have been discussed. The effects of the coating thickness on heat extraction in an Mg inverter housing case using the PEO (plasma electrolyte oxidation) coating method were also discussed. In order to produce an inverter case by the diecasting process, the filling sequence and cooling behavior during the diecasting process were simulated. The optimized process conditions from the simulation result were then used in a trial diecasting experiment.

• Journal of the Korean Applied Science and Technology
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• v.35 no.1
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• pp.80-88
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• 2018

In this study, we prepared hybrid composites by using low temperature sol-gel process for transparent and hard coating film. The hybrid composites consist of $ZrO_2/TiO_2/organosilane$, of which organosilane was introduced 3-(trimethoxysilyl)propyl methacrylate due to the role of a photocurable ceramic material for low temperature process. The ceramic composites with various composition ratios were coated on a polycarbonate substrate using a sol-gel process of low temperature process, and characterized optical and mechanical properties of coated thin film. The transparencies of coated thin films were 97.5 % or more, and the pencil hardness were 9H or more. In the case of the ZTS-2-1, the nano-indentation hardness was measured at the highest value of 1.14 GPa.

• Composites Research
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• v.30 no.6
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• pp.416-421
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• 2017

The structural adhesive have been manufactured for improvement of bonding process between CFRP and metal. The optimal condition for bonding process were investigated by evaluating the lap shear strength with amount of adhesive and curing time and the surface treatment of the CFRP. To confirm proper adhesion conditions, the fracture sections between CFRP and metal was observed using reflection microscope. Not only the improvement of the adhesion condition was important, but surface treatment on CFRP was also important. The optimal curing temperature was at $180^{\circ}C$ for 20 minutes. The improvement for adhesive property was confirmed After surface treatment on CFRP. The optimal amount of structural adhesive for bonding between CFRP and metal was $1.5{\times}10^{-3}g/mm^2$. Through the optimization of bonding process, the improvement of mechanical property over 10% is confirmed in comparison with existing adhesive.