• Journal of Convergence Society for SMB
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• v.5 no.2
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• pp.15-20
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• 2015

Recently, as smart phone technology is developing, wearable devices is also accelerating. But, the wearable device is necessary to operated for a long time with a small electric power because werable device is made compact. In this paper, we design and implement efficient lithium polymer battery model suitable to miniaturized wearable device in oder to maximize ease of use. The proposed model is characterized by a compact size of the battery by applying a thermal element and a light-weight battery. Also, proposed model gives greatly improve the life of wearable devices because it uses a method using the characteristics of the Peltier device using the temperature difference between the room temperature and body temperature of a person to generate power for charging. In particular, the proposed model can be used for the wearable device, as well as auxiliary charging of the smart phone.

• The Journal of the Convergence on Culture Technology
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• v.7 no.1
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• pp.668-673
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• 2021

As the fourth industrial revolution begins in earnest, related technologies are becoming a hot topic. Hardware development is accelerating to make the most of technologies such as high-speed wireless communication, and related companies are growing rapidly. Artificial intelligence often uses desktops in general for related research, but it is mainly used for the learning process of deep learning and often transplants the generated models into devices to be used by including them in programs, etc. However, it is difficult to produce results for devices that do not have sufficient power or performance due to excessive learning or lack of power due to the use of models built to the desktop's performance. In this paper, we analyze efficiency using boards with several Neural Process Units on sale before developing the performance of deep learning to match embedded boards, and deep learning accelerators that can increase deep learning performance with USB, and present a simple development direction possible using embedded boards.

• Clean Technology
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• v.28 no.2
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• pp.97-102
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• 2022

Lithium sulfur (Li-S) batteries have attracted considerable attention as a promising candidate for next-generation power sources due to their high theoretical energy density, low cost, and eco-friendliness. However, the poor electrical conductivity of sulfur and its insoluble discharging products (Li₂S₂/Li₂S), large volume changes, severe self-discharge, and dissolution of lithium polysulfide intermediates result in rapid capacity fading, low Coulombic efficiency, and safety risks, hindering Li-S battery commercial development. In this study, a three-dimensionally (3D) connected hierarchical porous carbon framework (HPCF) derived from waste sunflower seed shells was synthesized as a sulfur host for Li-S batteries via a chemical activation method. The natural 3D connected structure of the HPCF, originating from the raw material, can effectively enhance the conductivity and accessibility of the electrolyte, accelerating the Li⁺/electron transfer. Additionally, the generated micropores of the HPCF, originated from the chemical activation process, can prevent polysulfide dissolution due to the limited space, thereby improving the electrochemical performance and cycling stability. The HPCF/S cell shows a superior capacity retention of 540 mA h g^-1 after 70 cycles at 0.1 C, and an excellent cycling stability at 2 C for 700 cycles. This study provides a potential biomass-derived material for low-cost long-life Li-S batteries.

• Steel and Composite Structures
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• v.46 no.3
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• pp.385-401
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• 2023

Steel is becoming increasingly popular due to its high strength, excellent ductility, great assembly performance, and recyclability. In reality, steel structures serving for a long time in atmospheric, industrial, and marine environments inevitably suffer from corrosion, which significantly decreases the durability and the service life with the exposure time. For the mechanical properties of corroded steel, experimental studies are mainly conducted. The existing numerical analyses only evaluate the mechanical properties based on corroded morphology at the isolated time-in-point, ignoring that this morphology varies continuously with corrosion time. To solve this problem, the relationships between pit depth expectation, standard deviation, and corrosion time are initially constructed based on a large amount of wet-dry cyclic accelerated test data. Successively, based on that, an in-situ pitting evolution method for evaluating the residual tensile strength of corroded steel is proposed. To verify the method, 20 repeated simulations of mass loss rates and mechanical properties are adopted against the test results. Then, numerical analyses are conducted on 135 models of corrosion pits with different aspect ratios and uneven corrosion degree on two corroded surfaces. Results show that the power function with exponents of 1.483 and 1.091 can well describe the increase in pit depth expectation and standard deviation with corrosion time, respectively. The effect of the commonly used pit aspect ratios of 0.10-0.25 on yield strength and ultimate strength is negligible. Besides, pit number ratio α equating to 0.6 is the critical value for the strength degradation. When α is less than 0.6, the pit number increases with α, accelerating the degradation of strength. Otherwise, the strength degradation is weakened. In addition, a power function model is adopted to characterize the degradation of yield strength and ultimate strength with corrosion time, which is revised by initial steel plate thickness.

• Journal of Korea Port Economic Association
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• v.25 no.3
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• pp.67-92
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• 2009

A tugboat (tug) is a boat that maneuvers vessels by pushing or towing them. Tugs move vessels that should not move themselves alone, such as ships in a crowded harbor or a narrow canal, or those that cannot move themselves, such as barges, disabled ships, or oil platforms. Tugboats are powerful for their size and strongly built, some are ocean-going. Historically tugboats were the first seagoing vessels to receive steam propulsion, freedom from the restraint of the wind, and capability of going in any direction. As such, they were employed in harbors to assist ships in docking and departure. Towage is in essence a service by one vessel to another vessel for a fixed remuneration. The most common reason for requiring this service is the lack of its own motive power. Conventionally, towage is defined as "the employment of one vessel to expedite the voyage of another, when nothing more is required than the accelerating of her progress". Apart from accelerating vessels, acquiring towage service is a common practice for towing barges, platform of drilling oil, floating ship yards, etc.

• 한국태양에너지학회:학술대회논문집
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• 2009.11a
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• pp.56-61
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• 2009

Paradigm depending only on fossil fuel for building heat source is rapidly changing. Accelerating the change, as it has been known, is obligation for reducing green house gas coming from use of fossil fuel, i.e. reaction to United Nations Framework Convention on Climate Change. In addition, factors such as high oil price, unstable supply, weapon of petroleum and oil peak, by replacing fossil fuel, contributes to advance of environmental friendly renewable energy which can be continuously reusable. Therefore, current new energy policies, beyond enhancing effectiveness of heat using equipments, are to make best efforts for national competitiveness. Our country supports 11 areas for new renewable energy including sun light, solar heat and wind power. Among those areas, ocean thermal energy specifies tidal power generation using tide of sea, wave and temperature differences, wave power generation and thermal power generation. But heat use of heat source from sea water itself has been excluded as non-utilized energy. In the future, sea water heat source which has not been used so far will be required to be specified as new renewable energy. This research is to survey local heating system in Europe using sea water, central solar heating plants, seasonal thermal energy store and to analyze large scale central solar heating plants in German. Seasonal thermal energy store necessarily need to be equipped with large scale thermal energy store. Currently operating central solar heating system is a effective method which significantly enhances sharing rate of solar heat in a way that stores excessive heat generating in summer and then replenish insufficient heat for winter. Construction cost for this system is primarily dependent on large scale seasonal heat store and this high priced heat store merely plays its role once per year. Since our country is faced with 3 directional sea, active research and development for using sea water heat as cooling and heating heat source is required for seashore villages and building units. This research suggests how to utilize new energy in a way that stores cooling heat of sea water into seasonal thermal energy store when temperature of sea water is its lowest temperature in February based on West Sea and then uses it as cooling heat source when cooling is necessary. Since this method utilizes seasonal thermal energy store from existing central solar heating plant for heating and cooling purpose respectively twice per year maximizing energy efficiency by achieving 2 seasonal thermal energy store, active research and development is necessarily required for the future.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.4
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• pp.1039-1042
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• 2008

Dredged fills have been widely used to secure a land for the engineering activities. Before the useful application of the area, the soils should be consolidated to acquire the aquate shear strength. Several research projects have attempted to develop a method fur accelerating the consolidation of soft clay. Our study examined the effect of ultrasonic energy on the consolidation of soft clay, Tests were conducted using specially designed and fabricated equipment that was capable of directly applying ultrasonic energy to soil samples during consolidation tests. The specimens were prepared from slurry using a centrifuge facility, and tests were conducted at various levels of ultrasonic power and treatment time. The study showed that ultrasonic energy had a considerable effect on consolidation time, suggesting that ultrasound can be used to reduce the consolidation time of soft clay.

• Corrosion Science and Technology
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• v.12 no.6
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• pp.274-279
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• 2013

Flow accelerated corrosion (FAC) of the carbon steel piping in nuclear power plants (NPPs) has been major issue in nuclear industry. During the FAC, a protective oxide layer on carbon steel dissolves into flowing water leading to a thinning of the oxide layer and accelerating corrosion of base material. As a result, severe failures may occur in the piping and equipment of NPPs. Effect of alloying elements on FAC of pipe materials was studied with rotating cylinder FAC test facility at $150^{\circ}C$ and at flow velocity of 4m/s. The facility is equipped with on line monitoring of pH, conductivity, dissolved oxygen(DO) and temperature. Test solution was the demineralized water, and DO concentration was less than 1 ppb. Surface appearance of A 106 Gr. B which is used widely in secondary pipe in NPPs showed orange peel appearance, typical appearance of FAC. The materials with Cr content higher than 0.17wt.% showed pit. The pit is thought to early degradation mode of FAC. The corrosion product within the pit was enriched with Cr, Mo, Cu, Ni and S. But S was not detected in SA336 F22V with 2.25wt.% Cr. The enrichment of Cr and Mo seemed to be related with low, solubility of Cr and Mo compared to Fe. Measured FAC rate was compared with Ducreaux's relationship and showed slightly lower FAC rate than Ducreaux's relationship.

• Journal of Dairy Science and Biotechnology
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• v.25 no.2
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• pp.33-40
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• 2007

The Korean dairy industry has been developed continuously for the past seventy years both in quality and quantity; now the total amount of dairy products accounts for 13 percent of that of livestock production - a remarkable turnover. Korea now stands at the 13th economic power around the world and it is inevitable that we must pursue an open-door policy at a global level; the dairy industry should also strengthen its potentialities in the long term in order to compete with advanced dairy countries. It is predicted that the impact of DDA agreement and FTA negotiations on the domestic dairy industry will be great; so it is urgently needed that we should reconsider the current status of the dairy industry and comprehensive mesures for dairy industry development to improve its international competitiveness. Such measures comprise the three aspects: first, reforming the policy of dairy industry-related systems, second, improving the productivity and third, expanding the consumption of dairy products. In terms of the system reforming, the most important things are, above all, the planned production relevant to market needs, the milk supply and demand management, and the raw milk transaction method. Secondly, the appropriate scale of management is important for the enhancement of productivity together with the modernization of dairy facilities. Thirdly, step-up effort is needed to expand the milk consumption; especially, more milk should be provided to the students by improving the standing milk ration system in middle and senior high schools. The government should make more effort to support and develop new dairy products tuned to consumers' taste, accelerating the publicity of diverse and steady milk consumption together with related organizations.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.38 no.4
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• pp.265-270
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• 2002

Most of all the mechanical devices are becoming more high-speed and high-power as well as their used condition being more pollution with rapid development in industrial part. So, it is necessary for these devices to equip cooling system to overcome that kind of severe using condition. Industrial development and income increase causes rapid increase in using fossilenergy and it results in accelerating environmental pollution owing to the increasement in emission of air pollution substance. Specially, fresh water like stream and river water is acidified. Therefore, corrosion damage is accelerated in radiator for automobile that is using acidified water. So, in this study, corrosion test was carried out in distilled and tap water for the investigation on the corrosion behavior of Al-alloy that is using as material for radiator of automobile The main results obtained are as follows According to increase of temperature, open circuit potential is decreased in fresh water. And open circuit potential after deaeration is lower than that before deaeration. Corrosion current density in distilled water is less drained than that of tap water. And Corrosion current density after deaeration is less drained than that before deaeration.