• New & Renewable Energy
• /
• v.20 no.1
• /
• pp.52-60
• /
• 2024

This study conducted an economic analysis of renewable heat energy by estimating the levelized cost of heat production (LCOH) of ST and GSHP and comparing it with the cost of alternative fuels. The LCOH of ST ranged from 396.8 KRW/kWh to 578.7 KRW/kWh (small-scale), 270.3 KRW/kWh to 393.3 KRW/kWh (large-scale), and 156.3 KRW/kWh to 220.7 KRW/kWh for GSHP. The economic feasibility of ST and GSHP was analyzed by comparing the calculated LCOH and the fuel costs such as gas and kerosene prices. Moreover, scenario analyses were conducted for installation subsidies under the current system to examine the changes in the economics of renewable thermal energy.

• The KIPS Transactions:PartA
• /
• v.16A no.3
• /
• pp.169-180
• /
• 2009

With fixed sinks, the network stability could be improved while the network life time could be decreased by the rapid energy dissipation around the fixed sink because of the concentrated network traffic from sensor nodes to the fixed sink in wireless sensor network. To address this problem, mobile sinks, which decentralize the network traffic, has received a lot of attention from many researchers recently. Since a mobile sink has a limited period to communicate with each sensor nodes, it is necessary for a scheduling algorithm to provide the fairness of data collection from each sensor nodes. In the paper, we propose the new scheduling algorithm, ASF(Availability based Scheduling scheme for Fair data collection), for the fair data collection by a mobile in the sensor networks. The ASF takes account of the distance between each sensor nodes and the mobile sink as scheduling metric, as well as the amount of collected data from each sensor nodes. Experiment results shows that the ASF improves the fairness of data collection among the sensor nodes, comparing to existing algorithm.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.18 no.5
• /
• pp.1215-1223
• /
• 2014

In multi-hop wireless networks, a message transmission path is set up on demand by a route discovery step, where a shortest path is used in general. The shortest path, however, normally uses the nodes near the center area, which causes a high traffic load in that area and reduces the message transmission reliability. We propose a stable routing protocol considering the remaining energy of nodes. Our protocol uses ETX as a link performance estimator and tries to avoid the nodes with smaller energy. By doing this, we can reduce the route failure probability and packet loss. We have evaluated the performance of the proposed protocol using QualNet and compared with AODV and MRFR protocols. The simulation result shows that our protocol has a similar performance as MRFR in terms of end-to-end message reception ratio, average message delay and delay jitter, but outperforms MRFR in terms of traffic load distribution.

• Journal of Digital Convergence
• /
• v.11 no.10
• /
• pp.419-429
• /
• 2013

The Wireless sensor network(WSN) consisting of a large number of sensors aims to gather data in a variety of environments. The sensor nodes operate on battery of limited power. so, To extend network life time is major goals of research in the WSN. In this paper, we state the key point of a energy consumption with minimum&load balancing. The proposed protocol guarantee balance of number of cluster member nodes using the node memory threshold and optimization of distribution of cluster head using the optimized clustering method. The results show that the proposed protocol could support the load balancing and high energy efficiency by distributing the clusters with a reasonable number of member nodes. The simulation results show that our schme ensure longer life time in WSN as compare with existing schemes such as LEACH and CBLM.

• Korean Journal of Construction Engineering and Management
• /
• v.7 no.3 s.31
• /
• pp.112-121
• /
• 2006

The purpose of this study is to execute economical analysis for two types of office building HVAC system using LCC technique : single vs, separated HVAC(equal partition installation, unequal partition installation) system. The research method of this study includes the case analysis and questionnaire surveys. The results of this study are as follows: (1) LCCs of 3 types of HVAC system are estimated and the most economical one is investigated as single HVAC system, (2) In this case study, the single HVAC system was investigated as 34% lower in LCC during 15 years per $100m^2$ compared to equal partition installation, as 41% compared to unequal partition installation.

• Journal of Korea Spatial Information System Society
• /
• v.9 no.3
• /
• pp.35-50
• /
• 2007

In a data centric sensor network, a sensor node to store data is determined by the measured data value of each sensor node. Therefore, if the same data occur frequently, the energy of the sensor node to store the data is exhausted quickly due to the concentration of loads. And if the sensor network is extended, the communication cost for storing data and processing queries is increased, since the length of the routing path for them is usually in the distance. However, the existing researches that generally focus on the efficient management of data storing can not solve these problems efficiently. In this paper, we propose a NUNS(Non-Uniform Network Split) method that can distribute loads of sensor nodes and decrease the communication cost caused by the sensor network extension. By dividing the sensor network into non-uniform partitions that have the minimum difference in the number of sensor nodes and the splitted area size and storing the data which is occurred in a partition at the sensor nodes within the partition, the NUNS can distribute loads of sensor nodes and decrease the communication cost efficiently. In addition, by dividing each partition into non-uniform zones that have the minimum difference in the splitted area size as many as the number of the sensor nodes in the partition and allocating each of them as the processing area of each sensor node, the NUNS can protect a specific sensor node from the load concentration and decrease the unnecessary routing cost.

• Journal of Energy Engineering
• /
• v.25 no.1
• /
• pp.29-42
• /
• 2016

This study analyzes the economic efficiency of utilizing hot waste water at a thermoelectric power plant, which is part of recent projects supported by the Korean government to foster new energy industry. The author proposes an institution that provides economic incentives to promote the project. Based on a method of calculating Levelized cost of energy (LCOE), this study finds that the LCOE of using hot waste water at power plants is higher than that of oil boiler, biomass and a power plant's auxiliary steam but similar to that of the geothermal system. Also, according to sensitivity analysis on the LCOE of each element in the system of using hot waste water, a distance of heat supply is most sensitive. Therefore, this study shows that when the government devises an incentive-based institution to expand the project of utilizing hot waste water, it is necessary to establish Renewable Energy Certificate (REC) weights that are differentiated by a distance of heat supply.

• Clean Technology
• /
• v.26 no.1
• /
• pp.55-64
• /
• 2020

According to the Korean Renewable Energy 3020 Implementation Plan, the installation capacity of renewable energy is expected to increase whereas technology for storing excess electricity and stabilizing the power supply of renewable energy sources is extremely required. Power-to-Gas is one of energy storage technologies where electricity is converted into gas fuel such as hydrogen and methane. Basically, Power-to-Gas system could be effectively utilized to store excess electricity generated by an imbalance between supply and demand. In this study, the economic feasibility analysis of Power-to-Gas reflecting the domestic situation was carried out. Total revenue requirement method was utilized to estimate the levelized cost of hydrogen. Validation on the economic analysis method in this study was conducted by comparison of the result, which is published by the International Energy Agency. The levelized cost of hydrogen of a 100-MW Power-to-Gas system reflecting the current economic status in Korea is 8,344 won kg^-1. The sensitivity analysis was carried out, applying the main analysis economic factors such as electricity cost, electrolyser cost, and operating year. Based on the sensitivity analysis, the conditions for economic feasibility were suggested by comparing the cost of producing hydrogen using renewable energy with the cost of producing natural gas reformed hydrogen with carbon capture and storage.

• Journal of radiological science and technology
• /
• v.14 no.2
• /
• pp.45-53
• /
• 1991

SPECT 영상에서 콤프톤 산란 광자는 공간분해능의 감소와 그 양을 측정하는데 있어 정확성과 정밀성을 감소시킨다. 이와같은 콤프톤 산란의 영향을 감소시키기 위하여 사용하는 대부분의 보정방법은 선원의 위치로부터 거리의 단일지수함수로 대칭인 산란분포함수를 고려하게 된다. 본 연구는 균등 및 불균등 산란에 대한 산란분포함수를 얻기 위하여 보다 현실적인 접근방법을 시도하였다. 산란 및 비산란광자의 공간분포와 에너지분포를 얻기 위하여 뼈, 폐, 물의 균등 및 불균등 분포로 된 원통형의 팬톰 속에 $^{99m}Tc$의 선선원 및 점선원을 놓고 Monte Carlo Simulation을 하였으며, 깊이의 함수, media의 접촉영역으로부터 선원거리 및 산란체의 밀도의 변화로 표현한 산란분포함수(SDF)를 얻었다. 산란분포함수는 균등한 뼈, 폐, 물에서는 선원위치로부터 거리의 단일지수함수(single exponential functions)로 대칭으로 나타났으며, 두 물체의 조합에서는 2중지수함수(dual exponential functions)로 비대칭으로 나타났다. 산란분율은 20% window photopeak에서 총 계수의 8%에서 53%까지 다양한 변화가 있었으며, 지수함수의 기울기는 $0.1{\sim}0.9\;cm^{-1}$의 범위로 나타났다. 불균등 산란체에서 얻은 산란분포함수는 SPECT 영상에 있어 콤프톤 산란의 감소에 대한 보다 정확한 보정방법의 개발에 필요한 정보를 제공할 것이다.

• Proceedings of the Korean Information Science Society Conference
• /
• 2006.10d
• /
• pp.600-605
• /
• 2006

센서 네트워크는 데이터를 수집하는 싱크 주변에 있는 센서 노드가 극심한 에너지 소비를 보이는 문제가 있다. 이러한 싱크 주변 센서 노드의 에너지 소비 분산을 위해 모바일 싱크를 사용한 데이터 수집방법에 대한 연구가 최근 활발히 진행되고 있다. 모바일 싱크를 사용하여 데이터를 수집하기 위해서는 각 센서 노드별 데이터 수신 순서를 스케줄링하여 각 센서 노드에게 균등한 데이터 전송 기회를 부여하는 것이 중요하다. 본 논문에서는 싱글 홉 센서 네트워크에서 모바일 싱크를 이용한 균등한 데이터 수집을 위한 데이터 가중치 기반 스케줄링기법인 DWEDF를 제안한다. 또한 시뮬레이션을 통해 여러 다른 스케줄링 기법들에 비해 약 1.5배에서 3배가량 높은 성능을 보임으로써 그 효율성을 검증하였다.