• Resources Recycling
• /
• v.22 no.5
• /
• pp.3-12
• /
• 2013

It is necessary to manage risk of metals which are has rigid supply structures and expected demand expansion, considering to industry structure and resource securing capacity of each country. Countries conducted various criticality analyses and selected mainly rare metals as critical materials(or Critical metals or Critical raw materials). This study examined cases of metals risk evaluation and management which are based on technology changes and imbalance supply-demand. EU and U.S.A evaluated risk on metals needed as supply expansion of renewable energy. Japan forecasted demand of rare metals needed in Japan's growth engine industry. U.K analyzed criticality of metals, considering environmental burden occurred from mining to refining. Critical materials has features such as weak price signal, inelastic supply structure, demand volatility in technology change.

• Journal of Hydrogen and New Energy
• /
• v.33 no.3
• /
• pp.183-201
• /
• 2022

In this study, economic feasibility analysis was performed when various hydrogen production and transport technologies were applied to derive hydrogen supply plans by period. The cost of hydrogen may vary depending on several reasons; configuration of the entire cycle supply path from production, storage/transportation, and utilization to the cost that can be supplied to consumers. In this analysis, the hydrogen supply price according to the hydrogen supply route configuration for each period was analyzed for the transportation hydrogen demand in metropolitan area, where the demand for hydrogen is expected to be the highest due to the expansion of hydrogen supply.

• Water Engineering Research
• /
• v.1 no.1
• /
• pp.63-74
• /
• 2000

This paper presents a two- phase search scheme for optimal pipe expansion of expansion of existing water distribution systems. In pipe network problems, link flows affect the total cost of the system because the link flows are not uniquely determined for various pipe diameters. The two-phase search scheme based on stochastic optimization scheme is suggested to determine the optimal link flows which make the optimal design of existing pipe network. A sample pipe network is employed to test the proposed method. Once the best tree network is obtained, the link flows are perturbed to find a near global optimum over the whole feasible region. It should be noted that in the perturbation stage the loop flows obtained form the sample existing network are employed as the initial loop flows of the proposed method. It has been also found that the relationship of cost-hydraulic gradient for pipe expansion of existing network affects the total cost of the sample network. The results show that the proposed method can yield a lower cost design than the conventional design method and that the proposed method can be efficiently used to design the pipe expansion of existing water distribution systems.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.32 no.2
• /
• pp.1-12
• /
• 2009

Distribution centers in a distribution system that consists of the distribution centers and retailers supplies products to retailers. At the present, although total capacity of the distribution centers are enough to supply total demand of retailers, capacity of the distribution centers need to be expanded to satisfy the demand of retailers in case that future demand of the retailers will be increased. Capacity expansion model in a distribution system is to determine the location and size of expansion distribution centers that minimize costs among given distribution centers. Transportation amount from distribution center to retailers also is determined. The costs factors are the capacity expansion costs of the distribution centers and the transportation costs from the distribution centers to the retailers. A model is formulated, and a genetic algorithm based solution procedure is developed. A numerical example is shown and the algorithm is analyzed through examples.

• The Journal of Asian Finance, Economics and Business
• /
• v.8 no.2
• /
• pp.1263-1268
• /
• 2021

This study investigates how dramatic increase of university and college graduates affects labor market outcomes. Using a series of seven repeated cross sections of the Vietnam Household Living Standards Surveys, this paper analyzed the changes in the rate of returns to higher education attainment along with the increased supply of university and college graduates due to the higher education expansion throughout the 2002-2014 period. The study utilized a ratio of number of university and college students to the number of upper-secondary pupils within each province as an instrumental variable to calculate the effects of higher education expansion on the labor wage. The study found that, with the basic equations, the coefficients for higher education attainment are statistically significant and have positive values for the whole period. Our instrumental variables were found to be valid. For instrumental variable estimation, the return to higher education in IV earning equations was quite high. The findings of this study suggested that the expansion of the higher education system in Vietnam during 2002-2014 had positive effects on wages for those who increased their education attainment due to the reforms and there was a declining trend of the returns to higher education toward the end of the period.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.12 no.20
• /
• pp.55-61
• /
• 1989

The main contribution this research is the development of methodology which is capable of solving problems associated with the capacity expansion and operating schedule of energy industries. The principal concern of such industries is the proper allocation of primary energy which are required for the production of sufficient supply of electricity and petroleum products for the Korea`s energy needs. Nonlinear programming models are developed for power generation expansion planning and for the oil refinery industry. In order to deal with uncertainties about future demands for final energy, chance-constrained programming is used to formulate appropriate constraints. The methodology of the model can be used to evaluate Korean energy and expansion planning in the energy industry, especially the electric power generation industry and the refinery industry.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.34 no.8
• /
• pp.308-316
• /
• 1985

This paper proposes an analytic tool for long-term generation expansion planning based on the maximum principle. Many research works have been performed in the field of generation expansion planning. But few works can be found with the maxinmum principle. A recently published one worked by professor Young Moon Park et al. shows remarkable improvements in modeling and computation. But this modeling allows only thermal units. This paper has extended Professor Park's model so that the optimal pumped-storage operation is taken into account. So the ability for practical application is enhanced. In addition, the analytic supply-shortage cost function is included. The maximum principle is solved by gradient search due to its simplicity. Every iteration is treated as if mathematical programming such that all controls from the initial to the terminal time are manipulated within the same plane. Proposed methodology is tested in a real scale power system and the simulation results are compared with other available package. Capability of proposed method is fully demonstrated. It is expected that the proposed method can be served as a powerful analytic tool for long-term generation expansion planning.

• Proceedings of the KIEE Conference
• /
• 1997.07c
• /
• pp.1083-1087
• /
• 1997

Every effort is now being exerted in industrialized and developing countries to reduce emission of greenhouse gases from electric power sector. In this paper, we provide supply-side resource mix strategies in the long-term generation expansion planning under the expected greenhouse gas regulations. Under the environmental regulations, we explore the least-cost generation expansion plan of Korea and determine the composition of future resource mixes. Our analysis is performed on the basis of the revised WASP package which can evaluate emission of carbon dioxide from each power plant. The evaluation process of carbon dioxide emissions, which can consider the efficiency and operating conditions of each generator simultaneously, has been incorporated into the probabilistic production cost simulation module of WASP.

• Environmental Engineering Research
• /
• v.18 no.2
• /
• pp.109-114
• /
• 2013

In Cukhe, a village located in the outskirts of Hanoi, Vietnam, people suffer from a shortage of high-quality water due to an arsenic contaminated supply water resource. We installed catchments, filters and settled tanks in the existing rainwater harvesting facility to improve water quality, and ten portable rainwater tanks to provide good-quality drinking water to the poor households and kindergartens in the dry season. The triple bottom line considerations, as well as the environmental, economic, and social impacts of the rainwater harvesting (RWH) systems are examined. RWH is a sustainable method to obtain good-quality drinking water at low cost and with little energy expenditure. Education of the system also encourages that continuation of the system and expansion can lead into economic prosperity, as the safe drinking water can be sold to the community. Hence, RWH is a unique proposal as sustainable drinking supply water for improving the lives and health of residents in Cukhe and other sites where water supply sources are contaminated.

• Journal of Aerospace System Engineering
• /
• v.15 no.6
• /
• pp.26-32
• /
• 2021

The global aircraft-manufacturing industry ecosystem is characterized by the international division of labor through the worldwide supply chain and by the concentration of value added at the top of the supply chain. As a result, the competition for entry into the top supply chain and for order expansion is becoming increasingly intensive. To increase their orders, domestic aircraft manufacturing enterprises need to enhance their competitiveness by evaluating and analyzing it. However, most domestic aircraft manufacturing companies are unaware of the need to quantitatively evaluate their competitiveness. It is challenging to perform such an evaluation, and there are few research cases. In this study, we quantitatively evaluated and analyzed the competitiveness of domestic aircraft manufacturers by using data mining techniques. Thereby, implications for enhancing their competitiveness could be identified.