• Journal of the Semiconductor & Display Technology
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• v.22 no.1
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• pp.28-32
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• 2023

Recently, the use of stable lithium nanostructures as substrates and electrodes for secondary batteries can be a fundamental alternative to the development of next-generation system semiconductor devices. However, lithium structures pose safety concerns by severely limiting battery life due to the growth of Li dendrites during rapid charge/discharge cycles. Also, enabling long cyclability of high-voltage oxide cathodes is a persistent challenge for all-solid-state batteries, largely because of their poor interfacial stabilities against oxide solid electrolytes. For the development of next-generation system semiconductor devices, solid electrolyte nanostructures, which are used in high-density micro-energy storage devices and avoid the instability of liquid electrolytes, can be promising alternatives for next-generation batteries. Nevertheless, poor lithium ion conductivity and structural defects at room temperature have been pointed out as limitations. In this study, a low-dimensional Graphene Oxide (GO) structure was applied to demonstrate stable operation characteristics based on Li+ ion conductivity and excellent electrochemical performance. The low-dimensional structure of GO-based solid electrolytes can provide an important strategy for stable scalable solid-state power system semiconductor applications at room temperature. The device using uncoated bare NCA delivers a low capacity of 89 mA h g-1, while the cell using GO-coated NCA delivers a high capacity of 158 mA h g−1 and a low polarization. A full Li GO-based device was fabricated to demonstrate the practicality of the modified Li structure using the Li-GO heterointerface. This study promises that the lowdimensional structure of Li-GO can be an effective approach for the stabilization of solid-state power system semiconductor architectures.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.6
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• pp.1706-1727
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• 2023

Under Water Sensor Networks (UWSN) has gained attraction among various communities for its potential applications like acoustic monitoring, 3D mapping, tsunami detection, oil spill monitoring, and target tracking. Unlike terrestrial sensor networks, it performs an acoustic mode of communication to carry out collaborative tasks. Typically, surface sink nodes are deployed for aggregating acoustic phenomena collected from the underwater sensors through the multi-hop path. In this context, UWSN is constrained by factors such as lower bandwidth, high propagation delay, and limited battery power. Also, the vulnerabilities to compromise the aquatic environment are in growing numbers. The paper proposes an Energy-Efficient standalone Intrusion Detection System (EEIDS) to entail the acoustic environment against malicious attacks and improve the network lifetime. In EEIDS, attributes such as node ID, residual energy, and depth value are verified for forwarding the data packets in a secured path and stabilizing the nodes' energy levels. Initially, for each node, three agents are modeled to perform the assigned responsibilities. For instance, ID agent verifies the node's authentication of the node, EN agent checks for the residual energy of the node, and D agent substantiates the depth value of each node. Next, the classification of normal and malevolent nodes is performed by determining the score for each node. Furthermore, the proposed system utilizes the sheep-flock heredity algorithm to validate the input attributes using the optimized probability values stored in the training dataset. This assists in finding out the best-fit motes in the UWSN. Significantly, the proposed system detects and isolates the malicious nodes with tampered credentials and nodes with lower residual energy in minimal time. The parameters such as the time taken for malicious node detection, network lifetime, energy consumption, and delivery ratio are investigated using simulation tools. Comparison results show that the proposed EEIDS outperforms the existing acoustic security systems.

• Journal of Electrochemical Science and Technology
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• v.14 no.1
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• pp.85-95
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• 2023

In recent years, solid-state Li metal batteries (SSLBs) have attracted significant attention as the next-generation batteries with high energy and power densities. However, uncontrolled dendrite growth and the resulting pulverization of Li during repeated plating/stripping processes must be addressed for practical applications. Herein, we report a plastic-crystal-based polymer/ceramic composite solid electrolyte (PCCE) to resolve these issues. To fabricate the one-side ceramic-incorporated PCCE (CI-PCCE) film, a mixed precursor solution comprising plastic-crystal-based polymer (succinonitrile, SN) with garnet-structured ceramic (Li₇La₃Zr₂O₁₂, LLZO) particles was infused into a thin cellulose membrane, which was used as a mechanical framework, and subsequently solidified by using UV-irradiation. The CI-PCCE exhibited good flexibility and a high room-temperature ionic conductivity of over 10^-3 S cm^-1. The Li symmetric cell assembled with CI-PCCE provided enhanced durability against Li dendrite penetration through the solid electrolyte (SE) layer than those with LLZO-free PCCEs and exhibited long-term cycling stability (over 200 h) for Li plating/stripping. The enhanced Li⁺ transference number and lower interfacial resistance of CI-PCCE indicate that the ceramic-polymer composite layer in contact with the Li anode enabled the uniform distribution of Li⁺ flux at the interface between the Li metal and CI-PCCE, thereby promoting uniform Li plating/stripping. Consequently, the Li//LiFePO₄ (LFP) full cell constructed with CI-PCCE demonstrated superior rate capability (~120 mAh g^-1 at 2 C) and stable cycle performance (80% after 100 cycles) than those with ceramic-free PCCE.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.37 no.3
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• pp.292-296
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• 2024

In this study, Iron (III) oxide-hydroxide (δ-FeOOH) was successfully synthesized using hydrogen peroxide (H₂O₂) as an oxidizing agent. The synthesis of δ-FeOOH was carried out by controlling the amount of H₂O₂, and pure δ-FeOOH was successfully synthesized in ranges from 0.2 mL to 0.6 mL of H₂O₂. The size of the synthesized δ-FeOOH particles was compared by controlling the amount of oxidant H₂O₂. The average particle size of the synthesized pure δ-FeOOH particles increased from 875.1 nm to 897.2 nm as the amount of H₂O₂ was increased. The optical properties of δ-FeOOH synthesized under these specific conditions were investigated. All δ-FeOOH showed a similar trend of increasing and decreasing light absorption from 800 nm to 400 nm, although there was a slight difference in the amount of light absorption, with the largest amount of light absorption at 410 nm. The band gap energy of δ-FeOOH through the Tauc plot method was about 2.1~2.2 eV when H₂O₂ was 0.2~1.4mL. With a sufficient small particle size, simple control of that particle size, and a small band gap energy enough to absorb light in the visible spectrum, δ-FeOOH could be useful in a variety of applications, including photoelectrochemistry and battery electrodes.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.18 no.5
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• pp.1390-1411
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• 2024

Underwater Wireless Sensors Networks (UWSNs) are deployed in remotely monitored environment such as water level monitoring, ocean current identification, oil detection, habitat monitoring and numerous military applications. Providing scalable and efficient routing is very challenging in UWSNs due to the harsh underwater environment. The biggest difficulties are the nodes inherent movement due to water current, long delay in data transmission, low bandwidth of the acoustic signal, high error rate and energy scarcity in battery powered nodes. Many routing protocols have been proposed to solve the aforementioned problems. There are three broad categories of routing protocols namely depth based, energy based and vector-based routing. Vector Based Forwarding protocols perform routing through virtual pipeline by defining their radius which give proper direction to packets communication. We proposed a routing protocol termed as Path-Oriented Energy Scaled Expanded Vector Based Forwarding (PESEVBF). PESEVBF takes into account all parameters; holding time, the source nodes packets routing path and void holes creation on the second hop; PESEVBF not only considers the packet upward advancement but also focus on density of the forwarded nodes in terms of number of potential forwarding and suppressed nodes for path selection. Node selection in resultant holding time is based on minimum Path Factor (PF) value. Moreover, the suppressed node will be selected for packet forwarding to avoid the void holes occurrences on the second hop. Performance of PESEVBF is compared with other routing protocols using matrices such as energy consumption, packet delivery ratio, packets dropping ratio and duplicate packets creation indicating considerable performance improvement.

• Design & Manufacturing
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• v.18 no.3
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• pp.15-21
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• 2024

This study investigates the causes of wrinkle defects in PA12-insulated busbars used in electric vehicles and proposes an improvement method to address these issues. Busbars, essential components for efficient current transmission in electric vehicle battery modules, require complex three-dimensional bending to optimize internal layouts. For this study, oxygen-free copper busbars with a 0.8 mm PA12 insulation coating were subjected to three types of bending tests: flat bending, edge bending, and torsional bending. Experimental results showed that wrinkle defects only occurred during edge bending, while flat and torsional bending modes exhibited no significant issues. Cross-sectional analysis revealed that the PA12 insulation layer's thickness was uneven, with thinner sections on flat areas and thicker accumulation at the comers. This uneven distribution led to poor adhesion between the insulation and copper layers, resulting in the formation of wrinkles, particularly in areas with air gaps ranging from 75 to 250 ㎛. To further analyze the issue, finite element analysis (FEA) of the bending process was performed under adhesive and non-adhesive conditions. The results confirmed that wrinkles formed when the adhesion between the copper and PA12 coating was insufficient. Improved adhesion conditions, achieved through a heat treatment process at 120℃ for 2 hours, significantly reduced the occurrence of wrinkles during edge bending. This study demonstrates that optimizing the adhesion between the insulation coating and the copper busbar, through controlled heat treatment, can prevent wrinkle defects. The findings provide a pathway for enhancing the durability and performance of insulated busbars in electric vehicle applications.

• Economic and Environmental Geology
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• v.56 no.6
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• pp.781-797
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• 2023

Recently, there has been a rapid response from mineral-demanding countries for securing critical minerals in a high tech industries. Graphite, while overwhelmingly dominated by China in production, is changing in global supply due to the exponential growth in EV battery sector, with active exploration in East Africa. Rare earth elements are essential raw materials widely used in advanced industries. Globally, there are ongoing developments in the production of REEs from three main deposit types: carbonatite, laterite, and ion-adsorption clay types. While China's production has decreased somewhat, it still maintains overwhelming dominance in this sector. Recent changes over the past few years include the rapid emergence of Myanmar and increased production in Vietnam. Nickel has been used in various chemical and metal industries for a long time, but recently, its significance in the market has been increasing, particularly in the battery sector. Worldwide, nickel deposits can be broadly classified into two types: laterite-type, which are derived from ultramafic rocks, and ultramafic hosted sulfide-type. It is predicted that the development of sulfide-type, primarily in Australia, will continue to grow, while the development of laterite-type is expected to be promoted in Indonesia. This is largely driven by the growing demand for nickel in response to the demand for lithium-ion batteries. The global lithium ores are produced in three main types: brine lake (78%), rock/mineral (19%), and clay types (3%). Rock/mineral type has a slightly higher grade compared to brine lake type, but they are less abundant. Chile, Argentina, and the United States primarily produce lithium from brine lake deposits, while Australia and China extract lithium from both brine lake and rock/mineral sources. Canada, on the other hand, exclusively produces lithium from rock/mineral type. Vanadium has traditionally been used in steel alloys, accounting for approximately 90% of its usage. However, there is a growing trend in the use for vanadium redox flow batteries, particularly for large-scale energy storage applications. The global sources of vanadium can be broadly categorized into two main types: vanadium contained in iron ore (81%) produced from mines and vanadium recovered from by-products (secondary sources, 18%). The primary source, accounting for 81%, is vanadium-iron ores, with 70% derived from vanadium slag in the steel making process and 30% from ore mined in primary sources. Intermediate vanadium oxides are manufactured from these sources. Vanadium deposits are classified into four types: vanadiferous titanomagnetite (VTM), sandstone-hosted, shale-hosted, and vanadate types. Currently, only the VTM-type ore is being produced.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.6
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• pp.239-245
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• 2016

In this study, a 12 V PWM boost converter was designed with the optimal values of the external components of the power stage was well as the compensation stage for smart electronic applications powered by a battery device. The 12 V boost PWM converter consisted of several passive elements, such as a resistor, inductor and capacitor with a diode, power MOS switch and control IC chip for the control PWM signal. The devices of the power stage and compensation stage were designed to maintain stable operation under a range of load conditions as well as achieving the highest power efficiency. The results of this study were first verified by a simulation in SPICE from calculations of the values of major external elements comprising the converter. The design was also implemented on the prototype PCBboard using commercial IC LM3481 from Texas Instruments, which has a nominal output voltage of 12 V. The output voltage, ripple voltage, and load regulation with the line regulation were measured using a digital oscilloscope, DMM tester, and DC power supply. By configuring the converter under the same conditions as in the circuit simulation, the experimental results matched the simulation results.

• Journal of KIISE:Software and Applications
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• v.37 no.5
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• pp.341-353
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• 2010

Mobile Internet Device (MID) allows users to flexibly use various forms of wireless internet such as Wi-Fi, GSM, CDMA, and 3G. Using such Internet, MID users can utilize application services. MID usage is expected to grow due to the benefits of portability, Internet accessibility, and other convenience. However, it has resource constraints such as limited CPU power, small memory size, limited battery life, and small screen size. Consequently, MIDs are not capable to hold large-sized complex applications and to process a large amount of data in memory. An effective solution to remedy these limitations is to develop cloud services for the required application functionality, to deploy them on the server side, and to let MID users access the services through internet. A major concern on running cloud services for MIDs is the potential problems with low Quality of Service (QoS) due to the characteristics of MIDs. Even measuring the QoS of such services is more technically challenging than conventional quality measurements. In this paper, we first identify the characteristics of MIDs and cloud services for MIDs. Based on these observations, we derive a number of quality attributes and their metrics for measuring QoS of mobile services. A case study of applying the proposed quality model is presented to show its effectiveness and applicability.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.1261-1262
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• 2008

Laser-based crystallization techniques are ideally-suited for forming high-quality crystalline Si films on active-matrix display backplanes, because the highly-localized energy deposition allows for transformation of the as-deposited a-Si without damaging high-temperature-intolerant glass and plastic substrates. However, certain significant and non-trivial attributes must be satisfied for a particular method and implementation to be considered manufacturing-worthy. The crystallization process step must yield a Si microstructure that permits fabrication of thin-film transistors with sufficient uniformity and performance for the intended application and, the realization and implementation of the method must meet specific requirements of viability, robustness and economy in order to be accepted in mass production environments. In recent years, Low Temperature Polycrystalline Silicon (LTPS) has demonstrated its advantages through successful implementation in the application spaces that include highly-integrated active-matrix liquid-crystal displays (AMLCDs), cost competitive AMLCDs, and most recently, active-matrix organic light-emitting diode displays (AMOLEDs). In the mobile display market segment, LTPS continues to gain market share, as consumers demand mobile devices with higher display performance, longer battery life and reduced form factor. LTPS-based mobile displays have clearly demonstrated significant advantages in this regard. While the benefits of LTPS for mobile phones are well recognized, other mobile electronic applications such as portable multimedia players, tablet computers, ultra-mobile personal computers and notebook computers also stand to benefit from the performance and potential cost advantages offered by LTPS. Recently, significant efforts have been made to enable robust and cost-effective LTPS backplane manufacturing for AMOLED displays. The majority of the technical focus has been placed on ensuring the formation of extremely uniform poly-Si films. Although current commercially available AMOLED displays are aimed primarily at mobile applications, it is expected that continued development of the technology will soon lead to larger display sizes. Since LTPS backplanes are essentially required for AMOLED displays, LTPS manufacturing technology must be ready to scale the high degree of uniformity beyond the small and medium displays sizes. It is imperative for the manufacturers of LTPS crystallization equipment to ensure that the widespread adoption of the technology is not hindered by limitations of performance, uniformity or display size. In our presentation, we plan to present the state of the art in light sources and beam delivery systems used in high-volume manufacturing laser crystallization equipment. We will show that excimer-laser-based crystallization technologies are currently meeting the stringent requirements of AMOLED display fabrication, and are well positioned to meet the future demands for manufacturing these displays as well.