• The KIPS Transactions:PartC
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• v.14C no.6
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• pp.475-480
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• 2007

Recently, wireless networking devices that depend on the limited Battery and power-saving of wireless hosts became important issue. Batteries can provide a finite amount of energy, therefore, to increase battery lifetime, it is important to design techniques to reduce energy consumption by wireless hosts. This paper improved power saying mechanism in Distributed Coordination Function(DCF) of IEEE 802.11. In the IEEE 802.11 power saving mechanism specified for DCF, time is divided into so-called beacon intervals. At the start of each beacon interval, each node in the power saving mode periodically wakes up during duration called the ATIM Window. The nodes are required to be synchronized to ensure that all nodes wake up at the same time. During the ATIM window, the nodes exchange control packets to determine whether they need to stay awake for the rest of the beacon interval. The size of the ATIM window has considerably affected power-saving. This paper can provide more power-saving than IEEE 802.11 power saving mode because ATIM window size is efficiently increased or decreased.

• Tunnel and Underground Space
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• v.29 no.2
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• pp.89-107
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• 2019

Rock joints have an extremely important role in analyzing the mechanical stability and hydraulic characteristics of rock mass structures. Most rock joint parameters are generally indicated as a distribution by statistical techniques. In this research, calculation technique of Joint Center Volume (JCV) is analyzed, which is required for estimating the size distribution having the largest uncertainty among the joint parameters, then a new technique is proposed which is applicable regardless of the shape of survey window. The existing theoretical JCV calculation technique can be applied only to the plane window, and the complete enumeration techniques show the limitations in joint trace type and analysis time. This research aims to overcome the limitations in survey window shape and joint trace type through calculating JCV by using Monte Carlo simulation. The applicability of proposed technique is validated through the estimation results at non-planar survey windows such as curved surface and tunnel surface.

• Korean Institute of Interior Design Journal
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• v.18 no.5
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• pp.101-110
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• 2009

In case of general residential house, photovoltaic can be installed at roof, wall, and any other places. But, in case of apartment building, there has not enough roof space to install photovoltaic panels to supply enough electricity. Actually, apartment building roof and facade wall (exclude the balcony window space) is not enough space to produce and supply the electricity to residents by installing PV panel. Generally, the space of facade balcony with windows in facade wall at apartment building occupied about $70{\sim}80%$, in all facade space. So, if we could use the balcony and windows space in facade as PV to generating electricity, there could contribute the energy saying. But, PV cell is opacify. So if it installed at front window area in apartment building, residents may have displeasure for that opacity character. But the other hand, residents are not always in house especially in day time that is exactly good time for generating electricity by PV. If we can use PV at the facade balcony with window without collusion of resident's displeasure, there have good attraction to using sustainable energy. Hence, this study suggests the design of facade balcony window style PV by considering resident's living pattern in apartment building. The methods of this study are as follows. At first, this study surveyed to the residents about residential time in their home and asked user demand by Delphi survey. At second, this study designed balcony open style PV system which oriented to the user demand. At third, this study tests designed result performance by computer simulation that compared design result with old design. As a result, For the purpose of satisfying the resident demand, there designed sliding window style which slide the several door systems to the one side. That would be make balcony absolute open scenery to the residents. Hence, the designed system performance results were as follows. When we compare the small apartment and large apartment, smaller one has good performance than larger one. Because resident's residential time characteristic. And that has more good electronic performance than vertical style that is similar to roof style.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.608-613
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• 2009

According to the building regulation U-value limitation of window is $3.3W/m^2{\cdot}K$ in southern regions, while U-value limitation of wall is $0.35{\sim}0.58W/m^2{\cdot}K$. It means that the energy loss through windows is five times more than it through wall. Therefore, this study analyze how much it has affected building energy rating when the insulation performance of windows and walls is changed by building regulation. In conclusion, in order to obtain 2 rating thermal performance of windows is improved more than 10 percent of U-value limitation and it of wall is improved more than 20 percent. The thermal performance of windows is improved more than 20 percent of U-value limitation and it of wall is improved more than 30 percent to receive 1 rating.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.11
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• pp.972-980
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• 2002

This work is aimed at estimating the effects of various factors on the energy consumption of Korean-style apartment houses using TRNSYS. The factors considered here include the nominal size of floor area, type of remodeling, azimuth, sidewall insulation, and window type. Based on some assumptions, an actual apartment house is simplified into a model that is used for thermal load calculations. The simplified model is validated by showing a good agreement with the actual one in the predicted result. Remodeling balconies into unconditioned buffer spaces yields a favorable thermal performance in comparison with the original type regardless of the nominal size. Incorporating balconies into a conditioned indoor space leads to sharp increases in thermal loads, which must be avoided in view of energy conservation as well as structural problem. A quantitative assessment on the azimuthal effect indicates that the heating energy can be saved up to 16％ by taking the south or southeast direction. Reduction in the heating load with enhancing the sidewall insulation is gradual, so that a cost-effectiveness analysis may be needed when amending the regulations concerned. Glazing appears to significantly affect the heat transfer through window. A typical case illustrates that the heating load is decreased about 25％ by simply adopting triple glazing instead of double glazing.

• 한국태양에너지학회:학술대회논문집
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• 2012.03a
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• pp.165-170
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• 2012

This study aims to analyze the characteristics of temperature variation of Spandrels. According to the change of SHGC of Window system, air space, insulation performance and absorption factor of inner surface at the Spandrels, It was firstly estimated by using simulation. Secondly, measured to minimize the temperature-rise of inner surface temperature and the intermediate air temperature by using Full-scale Mock-up based on the result of simulation analysis. As a result, it turns out that low SHGC window system such as BIPV system had an advantage of reducing the window surface temperature, and the surface temperature of clear window system was all higher than BIPV system on simulation results. In the experiment results, it had some advantages of increasing the Spandrels volume, decreasing insulation performance and lower absorption factor.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.4
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• pp.351-357
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• 2012

To reduce the summertime cooling load of a plant factory, a concept design was performed for the double skin window which utilizes the low temperature air from a ground coupled heat exchanger. The design parameters were selected as the number of cavity air inlet, the cavity thickness, the location of cavity air inlet, and the configuration of cavity air outlet. A parametric study was conducted in a systematic way to evaluate the heat transfer characteristics of the double skin window. As the number of cavity air inlet and the cavity thickness increase, the heat flux from outside air to indoor air was decreased. The effect of the location of cavity air inlet was not significant and the larger cavity air outlet area gave us relatively better heat blocking performance from outside hot air. This study demonstrated that it is possible to develop an improved double skin window by utilizing a ground coupled heat exchanger.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.3
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• pp.273-281
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• 2019

The energy consumed by buildings among the total national energy consumption is more than 10% of the total. For this reason, Korea has adopted the zero energy building policy since 2025, and research on the energy saving technology of buildings has been demanded. Analysis of buildings' energy consumption patterns shows that lighting, heating and cooling energy account for more than 60% of total energy consumption, which is directly related to solar power acquisition and window opening and closing operation. In this paper, we have developed a low - power IoT sensor module for window system to transfer acquired information to building energy management system. This module transmits the external environment and window opening / closing status information to the building energy management system in real time, and constructs the network to actively take energy saving measures. The power used in the module is designed as an independent power source using solar power among the harvest energy. The topology of the power supply is a Buck converter, which is charged at 4V to the lithium ion battery through MPPT control, and the efficiency is about 85.87%. Communication is configured to be able to transmit in real time by applying WiFi. In order to reduce the power consumption of the module, we analyzed the hardware and software aspects and implemented a low power IoT sensor module.

• KIEAE Journal
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• v.17 no.1
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• pp.63-68
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• 2017

Purpose: Various studies to solve the problem of increased energy consumption in the buildings are being carried out recently. Especially, the economic feasibility and insulation performance of the air-cap have been verified so that various studies regarding the reduction of building energy consumption have been carried out. However, previous studies regarding the air-cap were only carried out based on the verification of its insulation performance according to the size and attachment position of the air-cap. Therefore, the purpose of this study is to suggest a detachable air-cap module for improving the performance of the windows, evaluate the performance based on cooling, heating and light environments and verify its effectiveness through a real-scale testbed. Method: In this study, the energy saving performance in the circumstance where there is no attachment of an air-cap (Case 1), the circumstance where there is the attachment of air-cap on the glass surface of window (Case 2) and the circumstance where there is the attachment of an air-cap on the window frame (Case 3) were compared in order to verify the performance of the detachable air-cap module (Case 4), and the electricity consumption of cooling, heating and lighting equipment to maintain the appropriate indoor temperature and Illuminance for each case was calculated and utilized as indicators for the performance evaluation. Result: The result of this study is as follows. 1) In this study, the detachable air-cap module which was easily detachable through the principle of the magnet was suggested. 2) When Case 4 is applied, the electricity consumption of cooling and heating equipment can be reduced by 27.5%, 13.2% and 3.4% in comparison with Case 1, Case 2 and Case 3 respectively. 3) When the air-cap is applied to the window, the lighting energy consumption increases by 4 % in comparison to the non application of the air-cap, and this factor or aspect should be considered when applying the air-cap. 4) According to the performance evaluation result in consideration of cooling, heating and light environments, Case 4 demonstrates an energy saving ratio of 22.6%, 10.6% and 2.7% in comparison to Case 1, Case 2 and Case 3 respectively, indicating that it is effective for improving the performance of windows.

• Geophysics and Geophysical Exploration
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• v.16 no.4
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• pp.293-299
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• 2013

The recent Multiple Lapse Time Window (MLTW) analysis of Korean Peninsula event showed that the focal depth was far greater influence factor than the velocity structure of the model, applying the analysis of the direct simulation Monte Carlo (DSMC) method. Thus, using the events with focal depth of about 10 km, this study considered 330 paths connecting 41 events and 71 stations, and re-examined uniform and depth-dependent velocity models previously studied. As a result, the residual of misfit function greatly decrease from analytic model to DSMC model, reflecting variation of the focal depth from 0 to 10 km. On the other hand, the difference of residuals for each velocity model were relatively small.