• KIEAE Journal
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• 제14권2호
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• pp.11-19
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• 2014

Building energy consumption takes up almost 25% of the total energy consumption. Therefore, diversified ways, such as improving wall and window insulation, have been considered to reduce building energy consumption. Recently, green roof system has been explored as an effective alternative for dealing with reducing heating and cooling energy, thermal island effect and improving water quality. However, recent studies regarding a green roof system have only focused on building energy reduction without considering the applied usage, location, and story of the green roof system. Therefore, this study pays attention to the heating and cooling energy in relation to the applied usage, location, and story of a green roof system for investigating its impact on energy reduction. The result of simulations show that the reduction in heating energy consumption is higher when applied to Cherwon-gun province which has a continental climate condition, compared to the city of Busan that is distinguished by its warm climate. Cooling energy saving turns out to be higher when the green roof system is applied to Busan in comparison with Cherwon. As for the applied usage or function of the building, residential space acquires the highest heating and cooling energy saving effect rather than commerce, educational or office space because of HVAC's running time based on usage. When it comes to the story of the green roof, both heating and cooling energy saving become the highest when the green roof is applied to single-storied buildings. The reason is that single story building is affected by the ground largely. Generally, the variations of heating energy consumption are larger than the cooling energy consumption. The outcome of the simulations, when a green roof system is applied, indicates that the energy consumption reduction rate is dynamically responding to the applied usage, location, and story. Therefore, these factors should be counted closely for maximizing the reduction of energy consumption through green roof systems.

• 정보통신설비학회논문지
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• 제10권1호
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• pp.33-39
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• 2011

This paper considers a performance analysis of set-top box (STB) power saving schemes. STB converts the signal into content which is then displayed on the television (TV) screen, and there are typically two operation modes: on mode and stand-by mode. The total energy consumption (TEC), a typical measure of power consumption of STB, is defined by the sum of power consumption in each mode. Recently there are some works of STB power saving schemes that transit STB operation modes efficiently, and the mode transition time point of those schemes can be different. Thus it is required to develop a performance evaluation method that reflects mode transition time points of each scheme to get TEC correctly. This paper proposes a performance evaluation method for STB power consumption using Poisson process to consider the mode transition time point. By modeling STB mode transitions as events of Poisson process, the average time duration of STB mode is computed and accordingly the effect of power saving is evaluated. The performance evaluation result shows that the proposed method achieves 1 to 19% improvement in power consumption compared with a conventional performance evaluation method.

• Journal of Power Electronics
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• 제12권1호
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• pp.215-222
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• 2012

Lighting represents a significant component of commercial buildings, particularly office buildings. Fluorescent lighting is invariably used in all commercial, industrial and residential areas. A significant amount of lighting energy is wasted every day by leaving the lights on and not utilizing daylight energy. However, if daylight illuminance can be harnessed, this will reduce the electricity consumption of fluorescent lamps and save energy. This paper explains possible significant savings in lighting energy consumption and hence in costs, without reducing the performance and visual satisfaction in office or industrial buildings. It is proposed to obtain energy saving by reducing the supply voltage without degradation in lighting performance. Experimental results confirm that as much as 20% of electrical energy can be saved by reducing about 9% of the supply voltage, without noticeably affecting light output while complying with lighting standard limits.

• Journal of Communications and Networks
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• 제7권2호
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• pp.126-134
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• 2005

Reducing energy consumption in mobile hosts (MHs) is one of the most critical issues in wireles/mobile networks. IP paging protocol at network layer and power saving mechanism (PSM) at link layer are two core technologies to reduce the energy consumption of MHs. First, we investigate the energy efficiency of the current IEEE 802.11 power saving mechanism (PSM) when IP paging protocol is deployed over IEEE 802.11 networks. The result reveal that the current IEEE 802.11 PSM with a fixed wakeup interval (i.e., the static PSM) exhibits a degraded performance when it is integrated with IP paging protocol. Therefore, we propose an adaptive power saving mechanism in IEEE 802.11-based wireless IP networks. Unlike the static PSM, the adaptive PSM adjusts the wake-up interval adaptively depending on the session activity at IP layer. Specifically, the MH estimates the idle periods for incoming sessions based on the exponentially weighted moving average (EWMA) scheme and sets its wake-up interval dynamically by considering the estimated idle period and paging delay bound. For performance evaluation, we have conducted comprehensive simulations and compared the total cost and energy consumption, which are incurred in IP paging protocol in conjunction with various power saving mechanisms: The static PSM, the adaptive PSM, and the optimum PSM. Simulation results show that the adaptive PSM provides a closer performance to the optimum PSM than the static PSM.

• 한국정밀공학회지
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• 제30권5호
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• pp.486-492
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• 2013

Energy cost has been increasing rapidly to comply with environmental regulations worldwide and the manufacturing industry who consumes more than half of the total energy needs to improve their cost competitiveness considering environmental costs. Machine tools are essential elements in manufacturing industry and efforts have been made recently to increase their energy efficiency mainly by German and Japanese machine tool builders. In this paper, trends in energy saving technology are described on the hardware and software sides of peripheral equipment of machine tools. In addition, the power consumption of a machining center is measured and analyzed to develop a software-based standby strategy for energy saving with peripheral equipment of machine tools.

• 설비공학논문집
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• 제14권12호
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• pp.1092-1101
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• 2002

The objective of this study is to develop energy saving strategies for indoor swimming pools and to estimate the effect of each energy saving strategy. For this purpose, field measurements regarding pool water heating energy, domestic hot water heating energy are conducted and a base energy consumption model is implemented using the DOE-2.1E program. The results of the study reveal that 25% of the total pool water heating energy may be saved by using night time pool covers, 27% of the total domestic hot water heating energy may be saved by using a waste water heat recovery system (effic. 60%), and of the total ventilation energy may be saved using an exhaust air heat recovery system (effic. 60%).

• 설비공학논문집
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• 제26권10호
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• pp.486-490
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• 2014

In our country, which imports 97% of the energy consumed, an energy saving policy is required. The price inflation of utility bills is caused by a steep rise in the prices of imported oil. This study aims to solve the difficulties that cause poor environmental conditions for workers in the energy services sector, and especially, to systematize energy consumption reports to manage energy goals by suggesting an example of written energy-saving reports. To this end, this research focuses on energy consumption of target facilities including office spaces in a main building and multi-use facilities of an office building. A system where all employees can participate is structured through the analysis of energy usage in the target buildings.

• 한국태양에너지학회 논문집
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• 제31권1호
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• pp.115-120
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• 2011

The energy used in Korea is strongly dependent on that produced by foreign countries. Accordingly, saving energy is more important than ever, because of the rise of international oil prices and depletion of oil resources. The development of energy efficient buildings is required especially for public buildings in Korea. In this study, the energy use of public buildings is identified. Then, the analysis of energy usage through regional offices in Busan City offers energy saving measures for public buildings.

• 한국기후변화학회지
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• 제9권3호
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• pp.253-261
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• 2018

As user-involved energy saving activities have become important in recent years, many forms of energy feedback experiments have been conducted. We conducted a study to determine if energy feedback activities affect energy saving for students living in dormitories at a university in Seoul. In particular, smart plugs were used for efficient research and quantitative performance measurements, and the extent of the impact of competition and rewards on participant energy saving behavior was further analyzed. The main findings of this study are as follows. First, the power usage of groups using smart plugs was lower than that of those without them. Second, energy feedback delivered to smart plug users did not have a significant impact on reduction of electric power consumption. Third, competition and compensation strategies had additional effects in reducing power usage for smart plug users. As a result, methods to deliver energy feedback more effectively as ICT technologies develop and efficient energy activities using IoT technologies can be expected to spread widely in the future.

• 전자공학회논문지
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• 제49권9호
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• pp.27-34
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• 2012

오늘날 ICT 네트워크에서 에너지 소모는 전체 에너지 소모의 10% 내외로 가까운 미래에 에너지가 현저하게 증가 할 것이다. 그러한 이유로 ICT 네트워크에서 에너지를 절약하려는 연구가 상당히 활발하게 이루어지고 있다. 본 논문에서 네트워크 레벨에서 네트워크 품질을 보장하면서 에너지 절약이 가능한 방법을 검토한다. 네트워크를 구성하는 노드와 링크는 에너지 프로파일에 따라 에너지가 소모된다고 가정하였다. 특히 IP 네트워크에서, 다양한 에너지 프로파일 모델을 기본으로 하여 네트워크가 소모하는 에너지 모델을 정식화하고, IP 네트워크 품질을 만족하면서 에너지 절약이 가능한 energy-aware QoS 라우팅 방안을 제시하고 검토한다. 본 논문에서 시뮬레이션을 이용하여, 에너지 프로파일에 따라 IP 네트워크가 소모하는 에너지의 차이가 크며, 적절한 에너지 프로파일 모델을 개발한다면 에너지 절약이 가능함을 보여 준다. 또 IP 네트워크의 품질을 유지하면서 에너지 절약이 가능한 energy-aware QoS 라우팅 중 min_used_path(MP) heuristic을 이용한 방법이 네트워크의 노드 및 링크의 감소율이 다른 방법에 비해 우수하고, 에너지 절약 효과가 다른 방법에 비해 우수함을 분명히 한다. 따라서 결론적으로 본 논문에서는 energy-aware QoS 라우팅의 한 방법인 min_used_path(MP) heuristic을 적용하여 네트워크 품질 유지하면서 에너지를 절약 할 수 있음을 확인 하였다.