• Journal of the Korea Convergence Society
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• v.8 no.6
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• pp.219-226
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• 2017

As the UAV industry is getting matured, various types of UAVs have appeared in many application fields, including filming, reconnaissance, rescue, and etc. and it requires the quick hardware designs, particularly a battery pack, of the UAV. We developed the automatic battery pack design tool for the convenient battery pack configuration design of the hoverable type delivery UAV. With inputs, including current profile, voltage profile, various kinds of cell specifications, desired battery pack voltage, and etc. the automatic battery pack design tool calculates a pack having the minimum weight and the maximum capacity by combining either homogeneous cells or heterogeneous cells. Also, the tool could predict the capacity fading trend of the designed battery pack configuration.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.6
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• pp.134-138
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• 2014

Power packs can change energy to hydraulic energy generated by an engine as a tool for use with civil engineering construction equipment. This paper determines which type of power pack meets the standards of construction machinery. A power pack was formulated as a three-dimensional model by using the software CATIA. A modal analysis was conducted using ANSYS Workbench, and the resonance was checked. Next, a harmonic analysis was conducted. The analytical results show that the dynamic stability of the power pack is assured.

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

• International Journal of Naval Architecture and Ocean Engineering
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• v.10 no.4
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• pp.491-498
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• 2018

The cost evaluation for voyage route planning in an ice-covered sea is one of the major topics among ship owners. Information of the ice properties, such as ice type, concentration of ice, ice thickness, strength of ice, and speed-power relation under ice conditions are important for determining the optimal route in ice and low operational cost perspective. To determine achievable speed at any designated pack ice condition, a model test of resistance, self-propulsion, and overload test in ice and ice-free water were carried out in a KRISO ice tank and towing tank. The available net thrust for ice and an estimation of the ice resistance under any pack ice condition were also performed by I-RES. The in-house code called 'I-RES', which is an ice resistance estimation tool that applies an empirical formula, was modified for the pack ice module in this study. Careful observations of underwater videos of the ice model test made it possible to understand the physical phenomena of underneath of the hull bottom surface and determine the coverage of buoyancy. The clearing resistance of ice can be calculated by subtracting the buoyance and open water resistance form the pre-sawn ice resistance. The model test results in pack ice were compared with the calculation results to obtain a correlation factor among the pack ice resistance, ice concentration, and ship speed. The resulting correlation factors were applied to the calculation results to determine the pack ice resistance under any pack ice condition. The pack ice resistance under the arbitrary pack ice condition could be estimated because software I-RES could control all the ice properties. The available net thrust in ice, which is the over thrust that overcomes the pack ice resistance, will change the speed of a ship according to the bollard pull test results and thruster characteristics (engine & propulsion combination). The attainable speed at a certain ice concentration of pack ice was determined using the interpolation method. This paper reports a procedure to determine the attainable speed in pack ice and the sample calculation using the Araon vessel was performed to confirm the entire process. A more detailed description of the determination of the attainable speed is described. The attainable speed in 1.0 m, 90% pack ice and 540 kPa strength was 13.3 knots.

• Journal of Hydrogen and New Energy
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• v.31 no.5
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• pp.489-497
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• 2020

The Li-ion battery is considered to be one of the potential power sources for electric vehicles. In fact, the efficiency, reliability, and cycle life of Li-ion batteries are highly influenced by their thermal conditions. Therefore, a novel thermal management system is highly required to simultaneously achieve high performance and long life of the battery pack. Basically, thermal modeling is a key issue for the novel thermal management of Li-ion battery systems. In this paper, as a basic study for battery thermal modeling, temperature distributions inside the simple Li-ion battery pack (comprises of nine 18650 Li-ion batteries) under a 1C discharging condition were investigated using measurement and computational fluid dynamics (CFD) simulation approaches. The heat flux boundary conditions of battery cells for the CFD thermal analysis of battery pack were provided by the measurement of single battery cell temperature. The temperature distribution inside the battery pack were compared at six monitoring locations. Results show that the accurate estimation of heat flux at the surface of single cylindrical battery is paramount to the prediction of temperature distributions inside the Li-ion battery under various discharging conditions (C-rates). It is considered that the research approach for the estimation of temperature distribution used in this study can be used as a basic tool to understand the thermal behavior of Li-ion battery pack for the construction of effective battery thermal management systems.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.289-289
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• 2009

The series hybrid propulsion system in bimodal tram consists of CNG engine, generator, inverter, motor and battery as main components. Among them, battery is very important thing to make a hybrid bimodal tram more efficient in driving. Battery pack is composed of 168 LPB(lithium polymer battery) cells, 650Vdc-300A. LPB should be treated with a good consideration in both temperature and overvoltage. This paper had analyzed and investigated the thermal flow and distribution of LPB module(l4 LPB cells) and Pack in simulated environments by commercial thermal analysis tool.

• Journal of Korea Technology Innovation Society
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• v.7 no.2
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• pp.413-439
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• 2004

There are many new technologies developed these days and the companies try to assess their technologies in order to either get financial supports or verify how valuable they are. However, since not only so many innovative technologies have been developed, but also the areas are very diverse, it becomes really difficult to value the technologies by the conservative technology valuation systems. Especially, in the energy technology area, it is much harder because energy technology is mainly used for public purposes and there have not been many experiences of valuing technologies. In this paper, the objective and systematic technology valuation system tool for energy technology will be suggested and investigated.

• Journal of Korea Entertainment Industry Association
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• v.15 no.7
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• pp.271-280
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• 2021

The purpose of this study was to conduct a subjective and objective evaluation to verify the improvements in acne skin conditions followed by the use of foam cleanser, skin toner, and a facial pack that contains bamboo vinegar. The research targets are 20 male and female high school students in Gwangju and Jeolla regions with acne skin of grade II and above based on the Korean Acne Grading System (KAGS). For the experiment, the subjects were classified between an experimental group with 10 subjects who used bamboo vinegar foam cleanser, skin toner, and facial pack and a control group with 10 subjects who used foam cleanser, skin toner, and facial pack without bamboo vinegar, and the subjects had to use the foam cleanser, skin toner, and facial pack for 12 weeks. In the case of skin improvement effects founded upon the objective measurement values, the experimental group showed a greater improvement for reducing the pores in the forehead, nose ridge, and left cheek (p<.001) compared to the control group, and the experiment group had higher satisfaction overall even for the skin improvement effects based on the subjective evaluation tool (p<.05, p<.001). The overall values of the satisfaction of the cosmetics showed that the experiment group had higher values (p<.01, p<.001) compared to the control group for the foam cleanser, skin toner, and facial pack, and there were statistically significant differences for usability in details (p<.01, p<.001). In conclusion, it was proven that bamboo vinegar is an effective natural cosmetic product material to improve acne skin conditions.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.3
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• pp.179-185
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• 2014

Average temperature and temperature uniformity in a battery cell are the important criteria of the thermal management of the battery pack for hybrid electric vehicles and electric vehicles (HEVs and EVs) because high power with large size cell is used for the battery pack. Thus, liquid cooling system is generally applied for the HEV/EV battery pack. The liquid cooling system is made of multiple cooling plates with coolant flow paths. The cooling plates are inserted between the battery cells to reject the heat from batteries to coolant. In this study, the cooling plate with U-shaped coolant flow paths is considered to evaluate the effects of coolant flow condition on the cooling performance of the system. The counter flow and parallel flow set up is compared and the effect of flow rate is evaluated using CFD tool (FLUENT). The number of counter-flows and flow rate are changed and the effect on the cooling performance including average temperature, differential temperature, and standard deviation of temperature are investigated. The results show that the parallel flow has better cooling performance compared with counter flow and it is also found that the coolant flow rate should be chosen with the consideration of trade-off between the cooling performance and pressure drop.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.06a
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• pp.626-629
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• 2007

The digital content was supplied quickly with advancement of video compressive technique and the network. Simultaneously illegal copy and diffuse via Internet, it was caused to necessitate the intellectual property right protection of the digital content. With this background, Various standardization groups and content provision enterprises developed the solution for a digital content protection. But the problem which lack interoperability is appeared, cause of independent development among other equipment. To find solution about this, MPEG(Moving Picture Experts Group) has progressed standardization against IPMP (Intellectual Property Management and Protection) techniques which are possible interoperability. In spite of it, with reason why insufficient function, DMP(Digital Media Project) standard was presented with the alternative against this. In this paper, we analyze MPEG IPMP standards and DMP ToolPack concepts to compare between them, and through these, designed and implemented digital content protection system which possible interoperability.