• Journal of the Korean Applied Science and Technology
• /
• v.27 no.2
• /
• pp.196-201
• /
• 2010

The influence of red lead($Pb_3O_4$) to curing and formation reaction properties when it was added in positive material of lead acid battery for vehicle use has been investigated. At the results, it was confirmed that the addition of red lead led 4BS crystal size to be smaller and increased the rates of 4BS formation and Pb consumption. Consequently the curing time was shortened to half compared with that of red lead-free one. In addition to this, the lead acid battery prepared by adding red lead showed 14% higher efficiency at the life cycle test than that without red lead.

• Journal of the Semiconductor & Display Technology
• /
• v.15 no.2
• /
• pp.20-25
• /
• 2016

The parallel computer cluster system has been known as the powerful tool to solve a complex physical phenomenon numerically. The numerical analysis of large size of Li-ion battery pack, which has a complex physical phenomenon, requires a large amount of computing time. In this study, the numerical analyses were conducted for comparing the computing efficiency between the single workstation and the parallel cluster system both with multicore CPUs'. The result shows that the parallel cluster system took the time 80 times faster than the single work station for the same battery pack model. The performance of cluster system was increased linearly with more CPU cores being increased.

• Proceedings of the KIPE Conference
• /
• 2015.07a
• /
• pp.195-196
• /
• 2015

This paper investigates the design of coupled inductor for minimum inductor current ripple in rapid traction battery charger systems. Based on the general circuit model of coupled inductor together with the operating principles of dc-dc converter, the relationship between the ripple size of inductor current and the coupling factor is derived under the different duty ratio. The optimal coupling factor which corresponds to a minimum inductor ripple current becomes -0.5, i.e. a complete inverse coupling without leakage inductance, as the steady-state duty ratio operating point approaches 1/3 or 2/3. In an opposite manner, the optimal coupling factor value of zero, i.e. zero mutual inductance, is required when the steady-state duty ratio operating point approaches either zero or one. Coupled inductors having optimal coupling factor can minimize the ripple current of inductor and battery current resulting in a reliable and efficient operation of battery chargers.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.25 no.2
• /
• pp.103-110
• /
• 2020

In this study, the design and operating strategy of DC home grid with PV, battery, and ultracapacitor have been discussed, The proposed sizing method can find the optimum size of the battery and PV which can reduce yearly utility energy consumption, whereas the control scheme can maintain the DC-bus voltage level of the DC home grid under different operating conditions, where day or night time operation, load and PV power levels, and the maximum current and state-of-charge of batter are considered. In addition, a supervisory power management strategy has been suggested, and its validity has been verified by HILS (hardware in-the-loop simulation) results.

• Journal of Energy Engineering
• /
• v.26 no.4
• /
• pp.107-117
• /
• 2017

Since South Korea started to apply Renewable Portfolio Standard (RPS) in 2012, there have been huge investment for deploying renewable technologies. Recently, the government determined to incentivize battery energy storage system(BESS) with renewable generations in order to induce the improvement of dispatching capability. In this paper, the annual pattern of PV generation based on actual generation data in South Korea is analyzed and the duration curve of capacity factor is proposed in order to provide the simplified analyzing methodology of present support policy for additional BESS installation for decision maker who is responsible for supply and demand planning. With suggested methodology, the range of appropriate BESS size with respect to the variation of system marginal price(SMP) and renewable energy certificate(REC) price can be derived briefly, and decision makers easily evaluate the effect of support scheme. Current policy for BESS installation support present additional BESS-related installation policy may give incentives to developers partially, however, the dependence between BESS size and benefit components (SMP and REC) can limit the deployment of the various portfolios of the BESS. Therefore, when improving the current policy in future, addressing the dependence between the technical aspects of battery size and the benefit components separately by the technical and economical parts is needed to set the suitable compensation rules for the renewable generation and BESS.

• Journal of the Korean Electrochemical Society
• /
• v.4 no.3
• /
• pp.132-137
• /
• 2001

Recently, the demand for notebook PC with lithium ion batteries has steadily increased and consumers require them to adopt a SBP(smart battery pack) able to predict the remaining capacity and the run time of batteries precisely. The SBP is composed of a protection If, by which safety of lithium ion batteries is maintained against overcharge, overdischarge and overcurrent, and a smart IC, which calculates the remaining capacity and the remaining run time. The protection IC shut abmormal current down by using overcharge/overdischarge FET. A SBS(smart battery system) is composed of a system host, a smart battery and a smart battery charger. The smart ICs for SBP will be required to provide a low cost, low current consumption and small size. There will need to develop a microcomputer control type IC and an optimum algorism which is able to predict the residual capacity and the residual run time precisely. SBS will apply to many kinds of industry fields such as an electric bicycle, an electric vehicle, a load levelling and a military.

• Journal of Ocean Engineering and Technology
• /
• v.35 no.1
• /
• pp.1-12
• /
• 2021

As increasing the international community's awareness of greenhouse gas reduction, the demand for eco-friendly ship fuel has accelerated recently. The fundamental aim of this study is to develop a new type of fully electrified ferry for passengers and cars considering Korean domestic coastal environmental conditions. Several technical difficulties are encountered in applying a fully electric propulsion system based on removable battery systems into a ship due to limitations imposed by the batteries' size and capacity. This paper reviews and analyzes marine environment regulations strengthened recently, technology trends related to fully electric propulsion vessels in each country, and Korean domestic coastal environments. We propose a new fully electrified car ferry design with a displacement of 400 t applied in Korea. It is powered by removable battery systems pre-charged in a safe inland charging station. The mobile battery system is developed to enable roll-on and roll-off using wheels. The characteristics of the ship motion are analyzed based on the weight and location of the battery systems. We expect our battery systems to be applicable to larger ships in the future.

• Proceedings of the KIPE Conference
• /
• 2008.06a
• /
• pp.413-415
• /
• 2008

The charge equalizer design for a series connected battery string is very challenging because it needs to satisfy many requirements such as implementation possibility, equalization speed, equalization efficiency, controller complexity, size and cost issues, voltage and current stress, and so on. Numerous algorithms and circuits were developed to meet the above demands and some interesting results have been obtained through them. However, for a large number of cells, for example, eighty or more batteries, the previous approaches might cause problems. Such problems include long equalization time, high controller complexity, bulky size, high implementation cost, and high voltage and current stress. To overcome these circumstances, this paper proposes a charge equalizer design method based on a battery modularization technique. In this method, the number of cells that we consider in an equalizer design procedure can be effectively reduces; thus, designing a charge equalizer becomes much easier. Furthermore, by applying the previously verified charge equalizers to the intramodule and the outer-module, we can obtain easy design of a charge equalizer and good charge balancing performance. Several examples and experimental results are presented to demonstrate the usefulness of the charge equalizer design method.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.8 no.12
• /
• pp.4269-4292
• /
• 2014

Currently, increasing numbers of access points (AP) are being deployed in enterprise offices, campuses and municipal downtowns for flexible Internet connectivity, but most of these access points are idle or redundant most of the time, which causes significant energy waste. Therefore, with respect to power conservation, applying energy efficient strategies in WIFI networks is strongly advocated. One feasible method is dynamically managing network resources, particularly APs, by powering devices on or off. However, when an AP is powered on, the device is initialized through a long boot time, during which period clients cannot be associated with it; therefore, the network performance would be greatly impacted. In this paper, based on a global view of an entire WLAN, we propose an AP selection technology, known as Temporary Access Selection (TAS). The criterion of TAS is a fusion metric consisting of two evaluation indexes which are based on throughput and battery life, respectively. TAS is both service and clients' preference specific through balancing the data rate, battery life and packet size. TAS also works well independently in traditional WLANs in which no energy efficient strategy is deployed. Moreover, this paper demonstrates the feasibility and performance of TAS through experiments and simulations with Network Simulator version 3 (NS3).

• Journal of Electrical Engineering and Technology
• /
• v.13 no.2
• /
• pp.659-668
• /
• 2018

This paper proposes an optimization approach of a grid-connected photovoltaic and wind hybrid energy system including energy storage considering voltage fluctuation in the electricity grid. A techno-economic analysis is carried out in order to minimize the size of hybrid system by considering the benefit-cost. Lithium-ion battery type is used for both managing the electricity selling to the grid and reducing voltage fluctuation. A new technique is developed to limit the voltage perturbation caused by the solar irradiance and the wind speed through determining the state-of-charge of battery for every hour of a day. Improved particle swarm optimization (PSO) methods, referred to as FC-VACPSO which combines Fast Convergence Particle Swarm Optimization (FCPSO) method and Variable Acceleration Coefficient Based Particle Swarm Optimization (VACPSO) method are used to solve the optimization problem. A comparative study has been performed between standard PSO method and PSO based methods to extract the best size with the benefit cost. A sensitivity analysis has been studied for different kinds and costs of batteries, by considering variable and constant state-ofcharge of battery. The simulations, performed under Matlab environment, yield good results using the FC-VACPSO method regarding the convergence and the benefit cost of the hybrid system.