• Journal of Electrical Engineering and Technology
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• v.10 no.3
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• pp.1304-1310
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• 2015

In remote islands, due to expense of existing generation systems, installation of photovoltaic cells (PVs) and wind turbines has a chance of reducing generation costs. However, in island power systems, even short-term power fluctuations change the frequency of grids because of their small inertia constant. In order to compensate power fluctuations, the authors proposed the power consumption control of pumps which send water to tanks. The power control doesn’t affect water users’ convenience as long as tanks hold water. Based on experimental characteristics of a pump system, this paper shows methods to determine reference power consumption of the system with compensation for short-term PV fluctuations while satisfying water demand. One method uses a PI controller and the other method calculates reference power consumption from water flow reference. Simulations with a PV and a pump system are carried out to find optimum parameters and to compare the methods. Results show that both PI control method and water flow calculation method are useful for satisfying the water demand constraint. The water demand constraint has a little impact to suppression of the short-term power fluctuation in this condition.

• Atmosphere
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• v.26 no.4
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• pp.599-615
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• 2016

This study investigates the accuracy of short-term ocean predictions during the development of ocean stratification for the Korea Meteorological Administration (KMA) Global Seasonal Forecast System version 5 (GloSea5) as well as the effect of atmosphere-ocean coupling on the predictions through a series of sensitive numerical experiments. Model performance is evaluated using the marine meteorological buoys at seas around the Korean peninsular (KP), Tropical Atmosphere Ocean project (TAO) buoys over the tropical Pacific ocean, and ARGO floats data over the western North Pacific for boreal winter (February) and spring (May). Sensitive experiments are conducted using an ocean-atmosphere coupled model (i.e., GloSea5) and an uncoupled ocean model (Nucleus for European Modelling of the Ocean, NEMO) and their results are compared. The verification results revealed an overall good performance for the SST predictions over the tropical Pacific ocean and near the Korean marginal seas, in which the Root Mean Square Errors (RMSE) were $0.31{\sim}0.45^{\circ}C$ and $0.74{\sim}1.11^{\circ}C$ respectively, except oceanic front regions with large spatial and temporal SST variations (the maximum error reached up to $3^{\circ}C$). The sensitive numerical experiments showed that GloSea5 outperformed NEMO over the tropical Pacific in terms of bias and RMSE analysis, while NEMO outperformed GloSea5 near the KP regions. These results suggest that the atmosphere-ocean coupling substantially influences the short-term ocean forecast over the tropical Pacific, while other factors such as atmospheric forcing and the accuracy of simulated local current are more important than the coupling effect for the KP regions being far from tropics during the development of ocean stratification.

• Journal of Ocean Engineering and Technology
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• v.14 no.3
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• pp.66-71
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• 2000

The main objectives of this study are to carried out in order to evaluate strength development of Fly Ash concrete containing various amounts of Fly Ash such as 0%, 10%, 20% and 30%. The experimental variables included in this test program consist of content of Fly Ash, concrete strength and chemical activation. As Fly Ash increases, air content, strength development of concrete and slump loss of normal strength concrete were gradually decreased. The inclusion of Na$_2$SO$_4$increased the short-term strength of concrete that contains Fly Ash. In addition, the strength development of concrete that contains Fly Ash and Na$_2$SO$_4$were improved.

• Korea Trade Review
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• v.47 no.5
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• pp.59-74
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• 2022

The exemption clause of recurring shipments refers to the insurer's exemption in Short-term Export Credit Insurance for the additional shipment which was shipped on board while any foregoing shipment was unpaid beyond its due date over 30 days. The recurring shipments are constituted with two factors: the due date of the foregoing shipment and the shipment date of the additional export. The exemption clause of recurring shipments has been eased by extending the grace period for payment up to 60 days from 30 days for the transactions between exporters and importers having the history of payments which were made customarily in delay. This research argues that the current grace period is for the buyers who customarily delay their payments, and that the insurer introduce a grace period for shipment in favor of exporters for the additional shipment which was delayed in on-boarding due to reasons beyond the control of exporters. In consideration of the waiting time and the on-boarding time at ports for container freight, shipments are frequently delayed, which entails those shipments to be indemnified by the exemption clause of recurring shipments. Roll-overs and Blank Sailings also cause the container freight to be delayed in on-boarding. This research is expected to contribute to further development of Short-term Export Credit Insurance in K-SURE.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.4
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• pp.451-454
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• 2014

Short-term load forecasting(STLF) for electric power demand is essential for stable power system operation and efficient power market operation. We improved STLF method by using hourly temperature as an input data. In order to using hourly temperature to STLF algorithm, we calculated temperature-electric power demand sensitivity through past actual data and combined this sensitivity to exponential smoothing method which is one of the STLF method. The proposed method is verified by case study for a week. The result of case study shows that the average percentage errors of the proposed load forecasting method are improved comparing with errors of the previous methods.

• Hwankyungkyoyuk
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• v.2 no.1
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• pp.107-116
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• 1991

In this study, the goals and the short and long term plan to attain the goals were set up through the analysis of non-government environmental protection organizations actual conditions which were grasped through interview and questionnaire. The goals and the plan were modified and elaborated through 3 times environment experts conferences and a public hearing. The goals were as follows: a) Laying down the guidelines on the organizations. b) Establishing a view of environment. c) Paying a public attention to importance of environment. d) Activations the practice in environmental protection movement. e) Harmonizing the relations between the organizations themselves. government and the organizations, industries and the organizations. f) Establishing the government support system to the organizations in leagal. administrative and financial aspects. g) Enhancing the potentialities on research and development in environmental protection technology. In the short and long term plan, the specific activities to be driven up to the year 2000 were presented by stages.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.11
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• pp.1956-1963
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• 2010

Studies on the development of various energy management programs and real-time bidirectional information infrastructures have been actively conducted to promote the reduction of power demands and CO2 emissions effectively. In the conventional energy management programs, the demand response program that can transition or transfer the power use spontaneously for power prices and other signals has been largely used throughout the inside and outside of the country. For measuring the effect of such demand response program, it is necessary to exactly estimate short-term loads. In this study, the power consumption patterns in both individual and group consumers were analyzed to estimate the exact short-term loads, and the relationship between the actual power consumption and seasonal factors was also analyzed.

• Journal of the Korean Institute of Intelligent Systems
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• v.16 no.6
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• pp.730-735
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• 2006

This paper proposes a time series prediction method for the short term electrical load will) the fuzzy system and the genetic algorithm. At first, we obtain the optimal fuzzy membership function using the genetic algorithm. With the optimal fuzzy rules and its input differences, a better time prediction system may be obtained. We obtain good results for the time prediction of the short term electric load by the proposed algorithm. In addition we implement the graphic user interface for the proposed algorithms. Finally, we implement the regional prediction system for the electric load.

• Land and Housing Review
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• v.10 no.2
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• pp.1-13
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• 2019

This study suggests that the system improvement priority of the Natural Conservation Zone of the Metropolitan Area Maintenance Planning Law, which was enacted for about 37 years. First of all, through the precedent research and the consultation meeting, the improvement plan was divided into the short term and the mid(or long) term. Important findings and implications are as follows. The short-term priority results were 'Improve water quality regulation', 'Strengthen individual location regulations of factories and induce multi-use plan position', and 'Improvement of waterfront area regulation', which were both critical and urgent. The mid-term(or Long-term) priority results were 'To integrate development and environmental duplication regulations', 'Abolition and unification of environmental laws', and 'Adjustment and resetting of natural conservation areas', which were both critical and urgent. On the other hand, 76.4% of the residents and 64.5% of the experts are concerned about the necessity of improvement of the Natural Conservation Zone system. Both residents and experts seem to be aware of the necessity. Opinions about Improvement and mitigation of regulations on Natural Conservation Zone that were constantly raised. In the past, there was a temporary and fragmented institutional mitigation of the government. However, with the rapid development of eco-friendly technologies since 2010, Our Country Conditions is in a transition period. This study has significant implications for the improvement and mitigation of metropolitan area regulations.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2003.10a
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• pp.507-510
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• 2003

The development of a basin-wide runoff analysis model is to analysis monthly and daily hydrologic runoff components including surface runoff, subsurface runoff, return flow, etc. at key operation station in the targeted basin. A short-term water demand forecasting technology will be developed taking into account the patterns of municipal, industrial and agricultural water uses. For the development and utilization of runoff analysis model, relevant basin information including historical precipitation and river water stage data, geophysical basin characteristics, and water intake and consumptions needs to be collected and stored into the hydrologic database of Integrated Real-time Water Information System. The well-known SSARR model was selected for the basis of continuous daily runoff model for forecasting short and long-term natural flows.