• Journal of the Microelectronics and Packaging Society
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• v.28 no.2
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• pp.13-28
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• 2021

Since transient electronic devices can operate under harsh conditions such as electrolytic solutions or inside the body, and be removed by hydrolysis after operation, they can replace conventional electronic devices in various research areas like biomedical implantable devices. Moreover, transient electronic devices that can dissolve in water and enzymes are the focus of the new concept of green technology, which can solve electrical waste issues. However, the surroundings of transient electronic devices can deteriorate internal device components. Thus, an encapsulation strategy is introduced for stable operation in solution by shielding the outside of a device with a passive barrier. This article summarizes recent research trends in transient electronic devices, including their background, dissolution behavior, and encapsulation strategies to enhance reliability by blocking water permeation.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.5
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• pp.334-339
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• 2012

A study on electrical and electronic equipment will occur in the atmosphere, which is essential to cut the power to prevent the waste of power by power measurement technology development and to develop the technology to do this operation is the main core of standby power to detect and block it and return the configured for software and hardware, while the actual construction to ensure stability through field testing and debugging of problems improved accordingly, as well as ease of installation and so it could be done while the test. In addition, in terms of basic hardware switching of standby power when blocking, reducing stress and ensure stable operation and circuit design, power off and back to ensure stable operation even when a protection circuit is applied.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.05a
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• pp.636-637
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• 2018

The electronic shelf label(ESL) system based on wireless communication can reduce waste of disposable paper, reduce labor force and update real time information. However, the environment in which a large number of ESL modules are installed is exposed to interference from radio frequency(RF) communications in the Industry-Science-Medical(ISM) band. In this paper, we propose an ESL system based on visible light communication to avoid congestion of ESL system using ISM band. In the proposed system, the goods information and ID transmitted from the administrator server are transmitted in the ESL Tag, and the ESL Tag identifies the ID and displays the product information. Experiments show that ESL system using visible light communication is possible.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.545-545
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• 2007

Recently, innovative process has been investigated in order to replace the conventional high-cost micro patterning processes on the electronic products. To produce desirable profit margins from this low cost products, printed circuit board(PCB), will require dramatic changes in the current manufacturing philosophies and processes. Innovative process using metal nano particles replaces the current industry standard of subtractive etched of copper as a highly efficient way to produce robust circuitry on low cost substrates. An advantage of using metal nano particles process in patterned conductive line manufacturing is that the process is additive. Material is only deposited in desired locations, thereby reducing the amount of chemical and material waste. Simply, it just draws on the substrate as glass epoxy or polyimide with metal nano particles. Particles, when their size becomes nano-meter scale, show some specific characteristics such as enhanced reactivity of surface atoms, decrease in melting point, high electric conductivity compared with the bulk. Melting temperature of metal gets low, the metal nano particles could be formated onto polymer substrates and sintered under $300^{\circ}C$, which would be applied in PCB. It can be getting the metal line of excellent electric conductivity.

• Journal of the Korean Physical Society
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• v.73 no.11
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• pp.1760-1763
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• 2018

To attain power generation with body heat, the thermal resistance matched design of the thermoelectric generator was the principal factor which was not critical in the case of thermoelectric generator for the waste heat generation. The dimension of thermoelectric legs and the number of thermoelectric leg-pairs dependent output power performances of the thermoelectric generator on the human wrist condition was simulated using 1-dimensional approximated heat flow equations with the temperature dependent material coefficients of the constituent materials and the dimension of the substrate. With the optimum thermoelectric generator design, thermoelectric generator modules were fabricated by using newly developed fabrication processes, which is mass production possible. The electrical properties and the output power characteristics of the fabricated thermoelectric modules were characterized by using a home-made test set-up. The output voltage of the designed thermoelectric generator were a few tens of millivolts and its output power was several hundreds of microwatts under the conditions at the human wrist. The measured output voltage and power of the fabricated thermoelectric generator were slightly lower than those of the designed thermoelectric generator due to several reasons.

• Resources Recycling
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• v.20 no.3
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• pp.12-27
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• 2011

DOWA group has been working on metal recycling applying the smelting and refining process of KOSAKA Smelter. DOWA has developed it's metal recycling technologies through the treatment of black ore(complex sulfide ores) that contain many kinds of non-ferrous metals. In addition to these special technologies, DOWA has strengthened its hydrometallurgical process of precious metals and ability to deal with low-grade materials such as used electrical appliances or vehicles. On the other hand, JX Nippon Mining & Metals Corporation(JX-NMMC) carries out its metal recycling and industrial waste treatment businesses employing advanced separation, extraction and refining technologies developed through its extensive experience in the smelting of non-ferrous metals. JX-NMMC collects approximately 100,000t/y of copper and precious metal scraps from waste sources such as electronic parts, mobile phones, catalytic converters, print circuit boards and gold plated parts. These items are recycled through the smelting and refining operations of Saganoseki smelter and Hitachi Metal-recycling complex(HMC). In this like, metal recycling industries combined with environmental business service in Japan have been developed through excellent technologies for mineral processing and non-ferrous smelting. Also, both group, Dowa and JX-NMMC, were contributed to establish Japan's recycling-oriented society as the typical leading company of non-ferrous smelting. Now. it is an important issue to set up the collection system for e-waste.

• Resources Recycling
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• v.18 no.4
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• pp.70-81
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• 2009

The patents were searched to investigate the trend and the direction of technologies about the recycling of WEEE (waste electric and electronic equipment). Database was collected from WIPS site, and then 223 patents were selected by investigating abstracts. The patents from 1986 to 2007 were analyzed according to countries, international patent classification (IPC), companies, technologies, and recycling-target materials. The most patents were applied in Japan and by Japan companies. Patents about physical pretreatment technology are the most among the patents of the WEEE recycling technologies. Patents about printed circuit boards among target materials are the most because of its high value-added.

• Journal of Hydrogen and New Energy
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• v.21 no.5
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• pp.435-441
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• 2010

To verify the possibility of a power generation system using biogas from the waste of pig farm for rural electric production, a SI gasoline engine is modified to use biogas fuel and was installed in a 20 KVA power generation system. An electronic speed regulation unit is developed to keep the system speed at 1500 rpm. Experimental investigations have been carried out to examine the performance characteristics of power generation system (such as: system frequency, phase output voltage,$\ldots$). In addition, the operating parameters and output emissions ($NO_x$, HC, and $CO_2$) of biogas-fueled engine are preliminary evaluated and analyzed for the change of system load. Results indicated that the researched power generation system shows a high stability of output voltage and frequency with help of speed regulator. Biogas fuel (mainly $CH_4$ and $CO_2$) has an environmental impact and potential as a green alternative fuel for SI engine and they would not require significant modification of existing engine hardware. Output emissions of biogas-fueled engine are found to be relative low. $NO_x$ emission increases with the increase of output electric power of the power generation system.

• The Journal of the Korea institute of electronic communication sciences
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• v.19 no.3
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• pp.589-602
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• 2024

Thermoelectric generator (TEG) generally do not have high heat conversion efficiencies. The performance of a thermoelectric generator module depends on the shape of the legs as well as the properties of the material and the number of legs. In this study, the leg shapes of thermoelectric elements are modeled into various geometric structures such as cylinder and cube shaped to efficiently harvest waste heat, and the electrical characteristics are compared numerically. The temperature gradient and power generation according to the bridge shape are found to be highest at the existing Cube shape. As a result of comparing the power generation using the cooling effect, the Cone shape was the highest in natural convection and the Hourglass shape was highest in forced convection. Research results confirm that geometry can affect the efficiency of thermoelectric generators.

• Applied Chemistry for Engineering
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• v.21 no.5
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• pp.509-513
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• 2010

Recently, an amount of waste electronic devices such as LED and trichromatic fluorescent lamp has increased with the development of electronic industry. Reportedly, rare earth metals such as yttrium and europium have been discovered in the waste electronic devices. In order to improve the selectivity of yttrium and europium, the effects of the following factors on recovery experiment have been considered : i) fatty acids with various alkyl chain lengths, ii) the concentration of extractant, and iii) pH. The results show that the extraction efficiencies decrease at the same pH with decreasing the concentration of extractant and so $pH_{0.5}$ (That value of pH in an aqueous phase at which the distribution ratio is unity at equilibrium: 50% of the solute is extracted (E = 0.5) only when the phase ratio is unity.) moves into higher pH. The highest selectivity of yttrium and europium was obtained with tetradecanoic acid as extractant. The extraction mechanism of yttrium and europium was varied with the change of concentration of the tetradecanoic acid. $MR_3$single-species was formed from the yttrium and europium ion in the extractant concentration less than 0.1 M. On the other hand, the yttrium or europium ion is solvated with three molecules of tetradecanoic acid monomer like $MR_3{\cdot}$ 3RH in the extractant concentration more than 0.1 M.