• KIEAE Journal
• /
• v.17 no.4
• /
• pp.75-81
• /
• 2017

Purpose: Most contemporary office buildings supply external views, a sense of openness and a sense of time to their occupants by adopting the curtain walls, which are equipped with an outer cover having large window area. As a result, the amount of radiation increases, adversely affecting cooling load during the summer in office buildings. Although solar radiation decreases heating load and reduces energy costs during the winter period, due to the characteristics of offices where occupants work largely during daytime, the cooling load is important compared to the heating. Therefore, diverse measures to resolve those trade-offs and annual energy cost have been investigated. Method: In this study, the annual thermal load was comparatively analyzed according to the slat angle of the venetian blind along with lighting control technique. Result: After selecting effective conditions, in order to resolve such issues, this study established automated control strategies of slat angle depending on the window-to-wall ratio and zone orientation, so that the findings of this study can be effectively generalized to other circumstances.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.9 no.4
• /
• pp.484-496
• /
• 1997

The fluid flow and heat transfer characteristics of conjugate forced and natural convection in the triple-glazed airflow window, where the outer air passes through a space contrived between the interior and exterior window panes, were studied numerically by a finite volume method for the elliptic form of the Navier-Stokes equations. The investigation focused on the influence of window geometry, ventilastion rate and solar energy on the temperature, velocity distribution and thermal performance of the airflow window. The comparison between the triple-glazed airflow window and the enclosed triple-glazed window was also made to evaluate the effect of buoyancy upon which the thermal performance of the window depended.

• KIEAE Journal
• /
• v.17 no.3
• /
• pp.15-21
• /
• 2017

Purpose: "Building energy design standard" is used to limit the thermal transmittance of building in Korea. However, it only covers the insulation standard for each appropriate elements of a building, not the thermal performance of Junction thermal bridge of windows and doors installed in wall. Therefore in this study, we have evaluated the thermal performance of Junction thermal bridge depending on installation method and position of windows and provide it as design data. Method: We analyzed heat transfer of 4-Track sliding window and tilt & turn triple glazed window that are placed in the first class category on window energy efficiency rating using Window 7.4 and Therm 7.4. Result : First, linear thermal transmittance of 4-Track sliding window differs by 2.2 times or more depending of installation method and location. It is higher than the linear thermal transmittance, 0.01W/mK, proposed by Passivhaus. Second, linear thermal transmittance of Tilt & turn triple glazed window differs by 7.7 times or more depending of installation method and location. The average linear thermal transmittance was less than 0.01W /mK when windows were installed on the internal wall insulation by the fixed hardware attachment method. Third, the thermal losses of a window caused by a junction thermal bridge are inversely proportional to the window area and converge gradually as the area increased.

• KIEAE Journal
• /
• v.12 no.5
• /
• pp.77-84
• /
• 2012

Daylighting is the controlled admission of natural light into a space, reducing electric lighting and saving energy. By providing a direct link to the dynamic and perpetually evolving patterns of outdoor illumination, daylighting helps create a visually stimulating and comfort environment for building occupants, while reducing energy costs. Especially, however, glare is the most important factor in daylighting, which is issued by incoming direct sunlight into windows. This study analyzed the discomfort glare on a daylighting window by using Image processing methodology and found a solution to problems with glare source of occupants. There are several ways to evaluate discomfort glare such as UGR (Unified Glare Rating) of CIE, DGI (Daylight Glare Index, Hopkinson, 1972) and VCP (Visual Comfort Probability) of IES. These are used to apply to the relatively little artificial light source and they cannot cover discomfort glare from a real daylighting window. In this regarding, this paper aimed to calculate DGI index of the real daylighting window in a experimental space by using image processing methodology. The variables and outcomes are luminance distribution of non-shading window, effect of venetian blind installed on the window and locations related to position index of DGI.

• Journal of Internet Computing and Services
• /
• v.9 no.4
• /
• pp.11-20
• /
• 2008

IEEE 802.16e has adopted sleep mode to minimize energy consumption of mobile nodes with high speed mobility. If the Base Station (BS) has no data to be sent to a Mobile Subscriber Station (MSS) at the instant of ending sleep window of the MSS, the MSS increases its sleep window interval by double until the window interval reaches to the maximum sleep window interval. Thus, during the operation of sleep mode, MSS repeatedly performs switch on/off action until there exist frames to be received from BS. The switch on/off operation significantly consumes energy of MSS. To effectively deal with the energy of the MSS, this paper proposes an algorithm which decides the minimum sleep window interval that will be used in next sleep mode based on the current sleep window interval. We evaluate the performance of IEEE 802.16e sleep mode algorithm and our proposed algorithm in terms of energy consumption and blocking probability. Compared with the current sleep mode algorithm used in IEEE 802.16e, the proposed algorithm decreases the energy consumption by about 30% without increasing blocking probability.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2004.08a
• /
• pp.401-404
• /
• 2004

Transfer characteristics of poly-Si TFTs within process window of laser energy are investigated. In terms of surface morphology and transfer characteristics, process window of laser crystallization is evaluated. While maximum mobility exists in lower edge of process window in n-channel TFTs, maximum mobility exists in higher edge of process window in p-channel TFTs.

• Journal of Energy Engineering
• /
• v.10 no.3
• /
• pp.294-298
• /
• 2001

A research for transmutation reactor is in progress to transmute high radioactive isotopes into low radioactive ones. In this study, thermal-hydraulic and structural analysis was performed to design liquid metal target system that would be used in subcritical transmutation reactor. Diffuse plate installation was considered to enhance cooling of window. And thermal-structural analysis of window was performed varying window thickness, beam power, and coolant flow rate to determine target system design valuers. It is ensured that maximum window temperature and stress would be acceptable in the design condition.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.33 no.11A
• /
• pp.1105-1116
• /
• 2008

Cognitive radio is one of the most effective techniques to improve the spectrum utilization efficiency. To implement the cognitive radio, spectrum sensing is considered as the key functionality because only counting on it, can the secondary users identify the spectrum holes and utilize them efficiently without causing interference to primary users. Generally, there are several spectrum sensing methods; the most common and simplest method is energy detection. However, the conventional energy detection has some disadvantages, which are caused by noise, especially, uncertain noise power leads to degradation of energy detector. In this paper, to solve this problem, we proposed sliding window-based energy detection method which can devide the frequency band of primary signal and noise using sliding window to estimate the power of primary user without the noise effect and achieve the better performance. It can calculate the energy of primary user only and can detect the primary signal. The simulation result shows that our proposed method outperforms conventional one.

• Journal of the Korean Institute of Rural Architecture
• /
• v.19 no.2
• /
• pp.9-16
• /
• 2017

The study analyzed the heat losses and the building energy efficiency grade by the energy simulation using the ENERGY# and ECO2 programs for the three types of Standard design of rural houses. It was calculated the energy efficiency rating by the ECO2 program for the rural housing standard design, and the energy demand and the energy consumption by each factor were compared and analyzed. And it analyzed energy consumption by element of each house by ENERGY # program. As a result, first in the evaluation of the energy efficiency grade of buildings by the ECO2 program, the rating for primary energy requirement for the housing newly built by the standard design of rural house is expected to range from 2 to 4 with 189.3 to $238.7kWh/m^2.a$. Second, the energy loss of each part of standard design of rural housing occurs in the order of ventilation 39%, window 33%, outer wall 14%, roof 9%, bottom 5%, and energy loss through ventilation and window occurs more than 70%. Third, the most beneficial effects on the energy efficiency grade is obtained the lowest grade of all three types by 2 when the lowering of the window and door heat transmission rate and the lowering of the light density, and the heat exchange ventilation device is not installed. Fourth, in the standard design of rural housing, the energy demand is occupied by heating > hot water > lighting order, and the order of the weight is changed in order of heating > lighting > ventilation > hot water. Fifth, building energy efficiency assessment system needs to establish policy for fixing rural housing energy as a practical device to ensure energy performance and quality.

• ETRI Journal
• /
• v.35 no.1
• /
• pp.80-88
• /
• 2013

A passive infrared or pyroelectric infrared (PIR) sensor is mainly used to sense the existence of moving objects in an indoor environment. However, in an outdoor environment, there are often outbreaks of false alarms from environmental changes and other sources. Therefore, it is difficult to provide reliable detection outdoors. In this paper, two algorithms are proposed to reduce false alarms and provide trustworthy quality to surveillance systems. We gather PIR signals outdoors, analyze the collected data, and extract the target features defined as window energy and alarm duration. Using these features, we model target and false alarms, from which we propose two target decision algorithms: window energy detection and alarm duration detection. Simulation results using real PIR signals show the performance of the proposed algorithms.