• Journal of Korean Society of Water and Wastewater
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• v.21 no.1
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• pp.75-82
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• 2007

When one forecasts urban water demand in a long-term, multivariate model can give more benefits than per capita requirement model. However, the former has shortcomings in that statistically high explanatory power cannot be obtained well, and change in customer behavior cannot be considered. If the past water consumption effects the future water demand, dynamic model may describe real water consumption data better than static model, i.e. the existing multivariate model. On these grounds, this study built dynamic model using system dynamics. From a case study in Seoul and Busan city, dynamic model was expected to forecast water demand more descriptively and reliably.

• Journal of Korean Society of Forest Science
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• v.95 no.5
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• pp.601-604
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• 2006

This study compared the accuracy of partial multivariate and vector autoregressive models for lumber demand prediction in Korea. The partial multivariate model has three explanatory variables; own price, construction permit area and dummy. The dummy variable reflected the boom of lumber demand in 1988, and the abrupt decrease in 1998. The VAR model consists of two endogenous variables, lumber demand and construction permit area with one lag. On the other hand, the prediction accuracy was estimated by Root Mean Squared Error. The results showed that the estimation by partial multivariate and vector autoregressive model showed similar explanatory power, and the prediction accuracy was similar in the case of using partial multivariate and vector autoregressive model.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.248-251
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• 1999

Recently, according to developing industry and life style, power consumption have been increased year after year. Currently these much power demand from power consumer is weakening the allowable power reverse margin in summer. As on of the remedies about this problem, the small scale grid-connected photovoltaic system is considered for auxiliary power source. Generally, grid-connected inverter have a isolation transformer for electrical isolation from utility. This paper propose transformerless system topology an inquiry the validity using simulation.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1801-1803
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• 2001

At present the under ground power transmission systems have installed until 154KV XLPE power cable in Korea But, the large capacity underground power transmission systems have been required gradually with the increasing demand of electric power. Therefore, our company has developed 345KV XLPE cable. This paper describes the estimate details of the insulation thickness according to weibull plotting for 345KV XLPE power cable.

• Journal of the Korean Professional Engineers Association
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• v.42 no.6
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• pp.36-41
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• 2009

Smart Grid is grafting IT(information technology) techniques on existing electric power network, supplier and the consumer to do real-time exchange of information lead to both direction and energy efficiency optimization, it is a next potential electric power network method. Because of applying various distributed electric power sources, the electric power network system will follow in size and it is dispersive and it will operate independently, and it become the intelligent electric power network, which in consumer demand reacts at real-time, because of using various sensors. In this article explain concept, features, and contemporary background of Smart Grid, and describe improve reliability of the electric power quality.

• Proceedings of the KIPE Conference
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• 2002.11a
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• pp.65-68
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• 2002

Most of the present demand in the world is met by fossil and nuclear power plants. A small part is met by renewable energy technologies. Among the renewable power sources, wind and solar energy have experienced a remarkably rapid growth in the past 10 years. Recently the utilization of wind power has been receiving close attention in this country, especially for the electrification of off-shore islands. The objective of this study is to demonstrate a small wind energy system as a stand-alone power source.

• Journal of KIISE:Information Networking
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• v.33 no.4
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• pp.299-309
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• 2006

In Mobile ad hoc networks, AODV is one of the famous on-demand routing protocol, which use the routing tables in the nodes if possible, or Route Discovery Process (RDP) is triggered to find a new route. However increasing the traffic of RDP causes dropping of the network performance in the large size of ad hoc networks. In this paper, we propose a novel routing protocol, named as AOZDV (Ad hoc On-demand Zone and Distance-Vector Routing), which enhances the AODV protocol with zone routing. AOZDV creates a Zone with neighbor nodes of the source/destination using traffic and power information, and utilizes Destination-Vector Table for internal routing in the Zone. We show by simulations that AOZDV can reduce the occurrence rate of route fail and RDP caused by route fail compared to existing routing protocols such as DSR and AODV.

• ETRI Journal
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• v.30 no.3
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• pp.469-479
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• 2008

This study analyzes factors affecting the competitiveness of broadband over power line communication (BPLC) and predicts demand for the service, based on quantitative information about consumer preferences drawn from a survey of Korean consumers. Findings from the estimation suggest that, although consumers value some beneficial features of BPLC, to be competitive the speed and stability of its data transmission needs to be improved. Moreover, on the basis of a market simulation, we expect BPLC to occupy only a small portion of Korea's Internet access market in the future, a finding we expect would hold true for other developed countries whose Internet access markets are already mature.

• Journal of Power Electronics
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• v.9 no.6
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• pp.919-928
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• 2009

Microgrids (MGs) are typically comprised of distributed generators (DGs) including renewable energy sources (RESs), storage devices and controllable loads, which can operate in either interconnected or isolated mode from the main distribution grid. This paper introduces a novel dynamic programming (DP) approach to MG optimization which takes into consideration the coordination of energy supply in terms of heat and electricity. The DP method has been applied successfully to several cases in power system operations. In this paper, a special emphasis is placed on the uncontrollability of RESs, the constraints of DGs, and the application of demand response (DR) programs such as directed load control (DLC), interruptible/curtaillable (I/C) service, and/or demand-side bidding (DSB) in the deregulated market. Finally, in order to illustrate the optimization results, this approach is applied to a couple of examples of MGs in a certain configuration. The results also show the maximum profit that can be achieved.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.113-116
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• 2007

The fuel cell which converts directly chemical energy of fuel into electric energy has higher efficiency than the conventional power generation which involves several additional processes. Especially, polymer electrolyte membrane fuel cell (PEMFC) of which the electrolyte is a thin proton conductive polymer membrane is affordable for portable power applications and small-scale distributed power generation including household and small building. It is very important to not only increase the efficiency of FC itself but determine the optimal operation mode. The optimal operational planning of lkW household PEMFC system based on the daily electricity and heat demand patterns was performed. The estimated economic gain was up to 20% by adoption of PEMFC system.