• Corrosion Science and Technology
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• v.7 no.3
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• pp.187-191
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• 2008

Transgranular stress corrosion cracking of nickel base alloys was reported by Copson and Dean in 1965. Study to establish this cracking mechanism needs to be carried out. Laboratory stress corrosion tests were performed for mill annealed(MA) or thermally treated(TT) steam generator tubing materials in a high temperature water containing lead. An electrochemical interaction of lead with the alloying elements of SG tubings was also investigated. Alloy 690 TT showed a transgranular stress corrosion cracking in a 40% NaOH solution with 5000 ppm of lead, while intergranular stress corrosion racking was observed in a 10% NaOH solution with 100 ppm lead. Lead seems to enhance the disruption of passive film and anodic dissolution of alloy 600 and alloy 690. Crack tip blunting at grain boundary carbides plays a role for the transgranular stress corrosion cracking.

• Proceedings of the Membrane Society of Korea Conference
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• 1994.06a
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• pp.33-43
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• 1994

It is the purpose of this paper to review the recent developments and future trends in various membrane processes, which will result in energy savings. Historically, there was a long period of academic curiosity in membrane research covering from gas separation to reverse osmosis. With advent of asymmetric membrane technology, many membrane processes proved to be energy efficient than the conventional separation methods. Thus, membrane technology has gained wide acceptance from many sectors of industry. The commercial sale of membranes is still modest compared to the major technologies, but it is one of the fastest growing industries. Recently the U.S.Department of Energy conducted a study (1) to evaluate and prioritize research needs in the membrane separation industry in order to foster and better support the deveolpment of energy-efficient new technologies. The National Science Foundation (U.S.A.) did also do a similar investigation. Both agencies have arrived neary at the same conclusion, that is, membrane separations can offer many new and alternative methods of separations that are more energy efficient than existing processes. This paper is largely based on these findings.

• Journal of the Korean Solar Energy Society
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• v.35 no.3
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• pp.81-91
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• 2015

LED has received intensive research attention due to its long life, high efficacy, fast response and wide colour availability, and has secured extensive application areas. However, LED chips within the modules convert only fraction of electric energy into light, and majority of supplied energy needs to be dissipated as heat, which challenges in the performance and life of the LED modules. IEC 62717 specifies the performance requirements for LED modules together with the test methods and conditions. The present study examined the influence of different design parameters on performance temperature through series of experiments and numerical simulations. The economic means to change the module performance temperature during the measurement of mandatory markings were suggested based on predicted cooling performances.

• International Journal of Internet, Broadcasting and Communication
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• v.11 no.1
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• pp.89-96
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• 2019

The purpose of this study is to investigate Nest Labs (Nest)'s business strategy. The activities based on strategic choices for monetizing connected product are investigated. Nest's capacity and functionality is to offer a seamless integration of devices, platforms, and services and the "Works with Nest" offers an ecosystem fulfilling the needs of different partners. For monetizing customer data, Nest provides a seamless customer experience supported by product incentives. Nest introduces open APIs to connect its connected products to the wider Internet of things (IoT) and open to "If This, Then That." The Nest app controls them from one single place. Nest partners with 32 energy providers as of 2017 and they provide energy from renewable and non-renewable energy sources. Nest also creates a sales channels in direct and indirect route and expands is business model to other industries such as home-rental service, 'AirBnB' to help consumers become more energy-efficient at home.

• Journal of Power Electronics
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• v.19 no.1
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• pp.316-331
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• 2019

A practical application of a supercapacitor energy storage system in a polarization instrument is proposed on the basis of the energy storage requirements of an induced polarization (IP) transmitter for geophysical exploration. We focused on the energy storage system of a supercapacitor, the topology of the power converter, and the system control strategy as key technologies, and we performed theoretical research and experimental tests on the system and developed an experimental platform. The experiments validated the theoretical research on the key technologies of the supercapacitor energy storage system and demonstrated the effectiveness of the innovation. Results showed that the storage system is efficient and satisfies the energy storage needs of the IP transmitter.

• Advances in Energy Research
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• v.8 no.3
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• pp.145-153
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• 2022

Recent concerns about rising fuel prices and greenhouse gas emissions have focused attention on alternative energy sources, particularly in the transport sector. Transportation consumes 40% of overall fuel usage. As a result, a growing majority of researches on Electric Vehicles (EVs) and their Energy Management Systems (EMS) have been done. In order to enhance the performance and to meet the needs of drivers, more information regarding the EMS is needed. A new Energy Management System is proposed using a FOPID controller. To put the concept into practice, state equations are utilised. The fifth-order state-space model under study is a linked model with several inputs and outputs and the transfer matrices are calculated for decoupling the system. Utilizing these transfer matrices to decouple the system and FOPID controller is used to tune the system. The tuned parameters are minimized using a Particle Swarm Optimization (PSO) approach with Integral Time Absolute Error (ITAE) as the goal. When the suggested FOPID system's results are compared to those of PID-controlled systems, a sizable improvement is observed, which is explained by the results.

• Journal of Hydrogen and New Energy
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• v.35 no.3
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• pp.269-279
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• 2024

Saudi Arabia is transitioning from its traditional oil-dependent economy to become a leader in the hydrogen industry. This paper explores the kingdom's strategic investments in hydrogen production and infrastructure as key components of its energy diversification and sustainability efforts. The focus is on enhancing green hydrogen production to meet domestic needs and strengthen its position in the global market. The urgency of diversifying energy sources is emphasized, with projects like the NEOM Green Hydrogen Project illustrating Saudi Arabia's commitment to renewable energy integration. These initiatives are positioned to centralize Saudi Arabia in the global shift toward sustainable energy, signaling a significant pivot in its economic and environmental policies.

• Journal of Navigation and Port Research
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• v.35 no.1
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• pp.57-62
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• 2011

On the view point of renewable energies as energy sources of district heating and cooling plant, the purpose of this study is to develop, classify and map the 500m${\times}$500m mesh, of which is treated as normal size in DHC regulations for evaluation process. Followings are the results. Various building and geographical informations including 13 districts and 108 counties are re-defined to create 500m${\times}$500m meshes, and it is find out that 3,289 meshes among 8,463 meshes have meaningful floor areas. Only 59 meshes(1.8%) are evaluated as mesh which has more than 50% of building volume ratio per mesh. 5 clusters classified by principal analysis and cluster analysis with building needs' characteristics are defined. Gwang-an Dong is representative of cluster 1 characterized as commercial area, and the cluster 4, 5 which has mainly residential needs are distributed in Yong-ho dong. Because there are a lot of cluster 3 meshes, which has complex needs area based on residential, cluster 3 could be defined as representative of Busan metropolitan city.

• Proceedings of the Korean Society of Crop Science Conference
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• 1999.11a
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• pp.102-144
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• 1999

The major problems of food crop cultivation in Korea are low yield of most crops except rice. inefficient cultivation techniques for aged farmers. and low international competibility. Therefore, development of cultivation techniques of food crops should aim the yield. quality improvement, labor reduction and production cost. The primary issue for increasing the yield of soybean, barely and wheat is to reduce the yield gap between the farmer's yield and recommended ones of experiment station. More advanced cultivation techniques needs to be developed. and/or the conventional breeding methods to be reconsidered. The newly developed labor-saving mechanized technique needs to reduce labor hours , and the cost of agricultural implements and machineries. In other words the labor-saving mechanized technique should be developed based on the improvement of total farming system as well as systemic fundamental innovation of cultural methods. The efficiency of solar energy use in food production of Korea in 1997 is as low as $0.52{\%}$ so there is much room to increase yield. It is recommendable that the concept of food Production should be changed to energy Producing efficiency Per unit area basis from volume and weight of food materials. Moreover, introduction of resonable cropping system is needed to increase yield of main crops, farmer's income, solar energy use efficiency, and decrease of land service expenditure. Current cropping system emphasized on economic crops. especially in vegetables , is not desirable for resonable use of arable land. stability of agricultural management and staple food crop self-sufficiency ratio. It is desirable to increase food crops . that are energy of carbohydrate and protein rich and land dependent crops. in cropping system. And the agronomist should develop the cultural methods to replace food crops for food self-sufficiency and stable farming management instead of economic crops in current cropping system. Low-input and environmentally-sound crop cultivation techniques, especially nitrogen-reducing culture technique which is directly related to food crop quality, also needs to be developed urgently. The extended cultivation of corn in upland and barely and wheat in lowland as a feed stuffs is recommended to prevent further decrease of food self-sufficiency ratio, which is mainly caused by the high reliance on imported feed grain. It is also considered that the calculation and presentation methods of standard agricultural income needs to be improved. The current calculation method uses unit land area of 10a regardless of crop kinds , characteristics of agricultural management and cultivation scale. So, it is apt to lead misunderstanding of farm income value. Therefore. it should show an income of average farmers for certain number of years. Research and developing system for food producing is not desirable because they are conducted currently individual crop and mono-culture basis. But actual agricultural income is usually earned by cropping system including upland and lowland. For example. the barley and wheat is usually cultivated in double cropping system. The cooperation among research institutes such as university agribusiness. government and farmers is indispensible. The public information and education on importance and consumption habit of food crops is necessary in Korean society to increase food self-sufficiency through nationwide cooperation.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2005.11a
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• pp.319-322
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• 2005

An energy problem has become one of the many Problems awaiting solution to human society. Energy needs to support not only industry, but also building in city. The types of residential building, office building and public building account for much proportion among the totally amount used energy. A public institution shows a fine example for an energy conservation in the present situation. But, the amount used energy of electricity, air-conditioning and heating is different from a building use and condition. Because the building data of the energy consumption by a load is insufficient, it is unable to select a proper energy source. According to this study, it analyzed an energy load by each building that had investigated the actual conditions of energy consumption about public buildings in Daegu City. In order to plan the efficient energy use both existing buildings and new buildings, this study will present the efficient energy use plan, which has operated to new buildings of a public institution, at present.