• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.5
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• pp.274-278
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• 2016

A road energy harvester was designed and fabricated to convert mechanical energy from the vehicle load to electrical energy. The road energy harvester is composed of 20 piezoelectric materials. This study attempted to evaluate output depending on pavement materials when paving road piezoelectric energy harvester in the road. Harvester is the bender type and is the method of supporting the both ends of piezoelectric material and applying the load in the middle part. Harvester was paved in the type paved with asphalt, type paved with cement and in the exposed type not covering the top of harvester. The output characteristics were compared and evaluated depending on changes in vehicle load and vehicle speed changes. As vehicles, truck (11.9 ton), SUV(1.6 ton) and sedan (1.5 ton) were used and the output characteristics when driving at the interval of 10 km/h from 10 km/h to 100 km/h were evaluated.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.6
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• pp.420-425
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• 2012

Lead-free piezoelectric ceramic/epoxy composites with '0-3' connectivity were prepared by cold-pressing with a temperature controlled curing method. A ceramic powder with a composition of $(Na_{0.51}K_{0.47}Li_{0.02})(Nb_{0.8}Ta_{0.2})O_3$ was synthesized by a conventional solid state reaction route. The dielectric and piezoelectric properties of ceramic/epoxy composites were characterized as a function of the volume fraction (${\phi}$) of piezoelectric ceramics, which was varied from 70 to 95 vol%. The results indicated that the piezoelectric properties of composites were significantly affected by the volume fraction of ceramics. In terms of the piezoelectric properties, specimens showed the best performance at ${\phi}$= 85 vol%, resulting in the piezoelectric constant $d_{33}$ of 39 pC/N and the figure of merit as a piezoelectric energy harvester ($d_{33}{\cdot}g_{33}$) of 1.24 $pm^2/N$.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.356.1-356.1
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• 2014

The Isolation of few-layered transition metal dichalcogenides has mainly been performed by mechanical and chemical exfoliation with very low yields. in particular, the two-dimensional layer of molybdenum disulfide (MoS2) has recently attracted much interest due to its direct-gap property and potential application in optoelectronics and energy harvesting. However, the synthetic approach to obtain high-quality and large-area MoS2 atomic thin layers is still rare. In this account, a controlled thermal reduction-sulfurization method is used to synthesize large-MoOx thin films are first deposited on Si/SiO2 substrates, which are then sulfurized (under vacuum) at high temperatures. Samples with different thicknesses have been analyzed by Raman spectroscopy and TEM, and their photoluminescence properties have been evaluated. We demonstrated the presence of mono-, bi-, and few-layered MoS2 on as-grown samples. It is well known that the electronic structure of these materials is very sensitive to the number of layer, ranging from indirect band gap semiconductor in the bulk phase to direct band gap semiconductor in monolayers. This synthetic approach is simple, scalable, and applicable to other transition metal dichalcogenides. Meanwhile, the obtained MoS2 films are transferable to arbitrary substrates, providing great opportunities to make layered composites by stacking various atomically thin layers.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1996.06c
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• pp.539-546
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• 1996

The physical condition of rapeseed delivered to fat industry plants plays a significant role in the formation of the qualitative features of the raw material for oil production and, consequently , of the oil itself. Rapeseed is stored in silos , frequently for months, before it is subjected to processing. During the long storage, the conditions of the seed cover is very important, as the seed cover provides natural protection of the seed against the effect of the environment. Seeds with damaged seed cover are more easily affected by mildew, and the rate of chemical processes. Deteriorating the quality of oil contained in the cotyledons is faster in such seeds. Cracked seed covers facilitates also the growth and development of microorgaism. So as rapeseed damage occurring inthe course of harvest and the post-harvest processing have a negative effect of the quality and quantity of oil the sees contain. The study presented here was aimed at examining the typical process of purcha ing and handling of rapeseed in fat industry plants, in the aspect of the occurrence of mechanical damage to the seeds. Special attention was paid to the condition of rapeseed immediately after combine harvesting : next , the successive stages of technological handling of the seed were examined. observing the operation parameters of the particular machinery and equipment in order to identify those operations which caused deterioration in the quality of the material (sees). Seed samples were taken successively from the following the hopper, prior to cleaning , after cleaning , prior to drying , after drying, from dry rape silo. The total level of damage increased through the handling. The content of unusable contaminants had the tendency to decrease in the successive operations. though the actual values still exceeded levels permitted by standards. The study allow to indicate the operation fo postharvest technological process, which cause the most seed damage as well as gave quantita ive description of the losses occurred.

• Journal of Biosystems Engineering
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• v.42 no.4
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• pp.283-292
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• 2017

Purpose: Japanese Apricot, a type of plum, has various medicinal and economical applications. Plums are quite popular worldwide, but their deseeding remains a serious impediment to their processing. Therefore, a plum (Japanese Apricot) seed remover (PSR) was developed that can use various types of cutters according to the purpose of the plum processing, and its performance was evaluated. Methods: The proposed PSR, which allows multipurpose cutters, namely, zero-, two-, and four-blade cutters, to be installed, was first designed and manufactured. To identify appropriate parameters related to the cutting pressure, plums were harvested from three regions during three harvesting periods, and their geometrical and mechanical properties were measured. After application of the parameters related to the cutting pressure, a performance test was carried out on both fresh and frozen plums by identifying the ratios of the flesh recovery, seed recovery, seed breakage, deseeding efficiency, and machine efficiency. Results: The results show that, using the proper calculation of the processing parameters, 100% deseeding efficiency was facilitated regardless of the type of cutter used. However, in the case of a four-blade cutter, there are significant differences in the flesh recovery ratio according to the plum setting angle. Between the fresh and frozen plums, all cutters showed a significantly better flesh recovery ratio for the case of fresh plums. Conclusions: This machine will advance the plum processing technology, and eventually help the plum industry flourish.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.10
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• pp.773-778
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• 2012

A road energy harvester was designed and fabricated to convert mechanical energy from the vehicle load to electrical energy. The road energy harvester is composed of 16 piezoelectric cantilevers. We fabricated prototypes using a vehicle load transfer mechanism. Applying a vehicle load transfer mechanism rather than directly installing energy harvesters under roads decreases the area of road construction and allows more energy harvesters to be installed on the side of the road. The power generation amount with respect to the vehicular velocity change was assessed by installing the vehicle load transfer mechanism form and underground form. The energy harvester installed in the underground form generated power of 4.52 mJ at the vehicular velocity of 50 km/h. Also, power generation of the energy harvester installed in the vehicle load transfer mechanism form was 48.65 mJ at the vehicular velocity of 50 km/h.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.287.1-287.1
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• 2013

The Isolation of few-layered transition metal dichalcogenides has mainly been performed by mechanical and chemical exfoliation with very low yields. in particular, the two-dimensional layer of molybdenum disulfide (MoS2) has recently attracted much interest due to its direct-gap property and potential application in optoelectronics and energy harvesting. However, the synthetic approach to obtain high-quality and large-area MoS2 atomic thin layers is still rare. In this account, a controlled thermal reductionsulfurization method is used to synthesize large-MoOx thin films are first deposited on Si/SiO2 substrates, which are then sulfurized (under vacuum) at high temperatures. Samples with different thicknesses have been analyzed by Raman spectroscopy and TEM, and their photoluminescence properties have been evaluated. We demonstrated the presence of single-, bi-, and few-layered MoS2 on as-grown samples. It is well known that the electronic structure of these materials is very sensitive to the number of layer, ranging from indirect band gap semiconductor in the bulk phase to direct band gap semiconductor in monolayers. This synthetic approach is simple, scalable, and applicable to other transition metal dichalcogenides. Meanwhile, the obtained MoS2 films are transferable to arbitrary substrates, providing great opportunities to make layered composites by stacking various atomically thin layers.

• Journal of Powder Materials
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• v.28 no.2
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• pp.127-133
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• 2021

One-dimensional (1D) piezoelectric nanostructures are attractive candidates for energy generation because of their excellent piezoelectric properties attributed to their high aspect ratios and large surface areas. Vertically grown BaTiO₃ nanotube (NT) arrays on conducting substrates are intensively studied because they can be easily synthesized with excellent uniformity and anisotropic orientation. In this study, we demonstrate the synthesis of 1D BaTiO₃ NT arrays on a conductive Ti substrate by electrochemical anodization and sequential hydrothermal reactions. Subsequently, we explore the effect of hydrothermal reaction conditions on the piezoelectric energy conversion efficiency of the BaTiO₃ NT arrays. Vertically aligned TiO₂ NT arrays, which act as the initial template, are converted into BaTiO₃ NT arrays using hydrothermal reaction with various concentrations of the Ba source and reaction times. To validate the electrical output performance of the BaTiO₃ NT arrays, we measure the electricity generated from each NT array packaged with a conductive metal foil and epoxy under mechanical pushings. The generated output voltage signals from the BaTiO₃ NT arrays increase with increasing concentration of the Ba source and reaction time. These results provide a new strategy for fabricating advanced 1D piezoelectric nanostructures by demonstrating the correlation between hydrothermal reaction conditions and piezoelectric output performance.

• Journal of the Microelectronics and Packaging Society
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• v.29 no.1
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• pp.17-33
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• 2022

Ti₃C₂T_X MXene, first reported by Naguib et al. in 2011, has attracted tremendous attention due to its excellent hydrophilicity, electrical conductivity, and mechanical/chemical stability. Since MXene is a two-dimensional material with a thickness of few nanometers, which ensure its flexibility. In last few years, due to these properties many researchers used Ti₃C₂T_X MXene into various fields such as flexible smart sensors, energy harvesting/storage devices, supercapacitors and electromagnetic interference shielding systems. In this review article, we have briefly discussed the various synthesis processes and characteristics of Ti₃C₂T_X MXene. Moreover, we reviewed the latest development of Ti₃C₂T_X MXene as flexible electrode material to be used into different applications.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.9
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• pp.1347-1356
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• 2022

In this paper, we investigate the properties of CoGe thin film-based galvanic cells as a function of their dimension (cell length, width, etc.) and show their application as sensors to Arduino-based IoT sensor networks to detect water contact. Because these CoGe thin film-based galvanic cells do not require mechanical strains or temperature gradients unlike piezoelectric and thermoelectric energy harvesters, we think that these thin film-based galvanic cells are more suitable for self-powered sensor networks demanding sustainable and robust energy harvesters. In the past, a sputter-deposited CoGe thin film has not been intensively investigated for energy harvesting appilcations. Thus, in this study, we perform a feasibility study of galvanic cells composed of a sputter-deposited CoGe thin film to see if they can be applied as potential self-powered sensors. We believe that this paper will be of great help in developing even more enhanced sensor networks.