• KIEAE Journal
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• v.4 no.4
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• pp.61-68
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• 2004

Daylight is a critical factor in architecture, as it helps enhance the working efficiency and pleasantness of the people working inside, in addition to reduce the power consumption in heating and cooling and make the interior space brighter. There are many kinds of glazing and daylighting systems. At present, research and efforts for their development are carried out, alongside quantitative evaluation. This study aims to present basic materials to be used to design proper glazing and daylighting systems in architecture based on a quantitative evaluation by scale models of existing office buildings. The result of the study can be summarized as follows. 1)As a result of the experiment, it appeared that the ratio of the interior illumination (i.e. at the working table, ceiling and wall) against the outdoor illumination increases at a constant rate, as the transmittance of the glazing goes up. 2) It was found that the SIR(Sunlight Illuminance Ratio) of a separated window system goes up by 20-50% at the rear part than in the case of an ordinary window system.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.69-72
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• 2006

The objective of this study is to find out the shear capacity of URM wall and the variables that affect the shear capacity of URM wall such as the opening and the aspect ratio, considering four kinds of failure modes, sliding shear failure, toe crushing failure, and diagonal shear failure. The main varialble is the shape of opening of URM walls. First URM has one door, second has one window, third hase one door and one window, the last has two windows. The test results of URM with openings show that the specimens are governed by rocking failure mode.

• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.69-72
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• 2000

In CDMA systems, the performance of the typical multipath searcher degrades much according as the signal to noise ratio becomes low. In this paper, multipath searcher algorithm is proposed based on sliding window to overcome this drawback. In searcher systems, correlation values between incoming and local PN sequences are used to acquire multipath components. Therefore more accurate distributions of correlation values obtained through this proposed algorithm enables to get higher detection probability. In computer simulations, it is verified that proposed algorithm has better performances in Rayleigh fading channel and Gaussian channel.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.8
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• pp.1384-1390
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• 2008

The TCP protocol is originally designed for wired network, however it performs very poor in wireless network due to different nature of wireless network from wired networks. In terms of TCP performance improvement in wireless Ad-hoc network, many researches show that small congestion window size of TCP connection can improve TCP performance. We propose a new TCP algorithm to improve TCP performance in wireless Ad-hoc network. The basic idea of our approach is that TCP receiver estimates the optimum window size and then sets congestion window limit of TCP sender to an optimum value by using the advertised window field in TCP ACK packet. From extensive computer simulation, the proposed algorithm shows superior performance than traditional TCP protocols in terms of packet delivery ratio and packet loss.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.5
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• pp.38-43
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• 1996

Windowing routines have as their purpose the reduction of the sidelobes of a spectral output of the FFT or DFT routines. Windowing routines accomplish this by forcing the beginning and end of any sequence to approach each other in value. Since they must work with any sequence they force the beginning and ending samples near zero. To make up for this reduction in power, windowing routines give extra weight to the values near the middle of the sequence. The difference between windows is the way in which they transition from the low weights near the edges to the higher weights neqr the middle of the sequence. Signal-to-noise ratio(SNR) can be determined by the ratio of the output noisy signal variance to the input noisy signal variance of a window. Standard deviation of noise is reduced by windowing. Thus, the windowing operation improved the SNR of the noisy signal. This paper shows a performance estimation of windowing on a single tone with added Gaussian noise and uniform noise.

• Journal of the Korean Solar Energy Society
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• v.40 no.1
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• pp.35-47
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• 2020

Due to the large window area, the lighting environment of the educational space between the window and deep part of the room is not uniformly illuminated, and the phenomenon of glare is severe. For this reason, the daylight performance of DSC-BIPV windows was analyzed in order to improve the natural lighting in the educational sector. The method derives the correlation with natural lighting by measurement and simulation. Dynamic simulation confirmed that the average illuminance of the target space was higher at later than the early afternoon. The performance of natural lighting at 40% and 30% transmission of DSC has the effect of significantly reducing the amount of excess light in existing windows. Nevertheless, the actual average illuminance in all seasons corresponds to the standard illuminance of the educational facility, 300 Lux. In addition, the uniformity is also seen through the skylight illuminance ratio.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.2
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• pp.13-22
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• 2005

This research aimed to generate two points of daylighting application as follows: 1) providing daylight performance data with a variety of glazing materials for a large window and 2) designing and evaluating an experimental type of differentiated window. For this purpose, we compared the daylight and distribution performance of new defined type of window configuration to the conventional window counterpart with a variety of glazing materials. The comparison was made for a deep, south-facing perimeter zone with large window, without any interior obstruction. The conventional window is the base single homogeneous glass pane, where as the differentiated window uses of two different glazings; an upper daylight glazing with high visible transmission and lower view window with lower transmittal glass. The daylight performance data was translated into a ratio between outdoor illuminance and the interiors. The simulated analysis of the conventional window indicates that the interior light levels have been changed proportionally dependent on the transmittance of the applied glass. The comparison of daylight distribution analysis showed that the differentiated window has lots of photometric advantage by the optical function of upper daylight window. In particular, the contribution of higher daylight window into deep rear space must be stressed for daylighting application.

• Architectural research
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• v.19 no.4
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• pp.89-94
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• 2017

In Korea, it is necessary to improve the performance of buildings with respect to the energy efficiency while improving the quality of occupants' lives through a sustainable built environment. During the design and development process, building projects must have a comprehensive, integrated perspective that seeks to reduce heating, cooling and lighting loads through climate-responsive designs. The aim of this study is to assess the optimal window-to-wall ratio of multi-rise residential units in the early design phase in Korea. The study analyzed the variation of annual heating and cooling energy load in two apartment prototype units located in Seoul city using different WWRs. The analysis was conducted using Autodesk Ecotect Analysis 2011 tool. The study found for total annual building load reductions WWR on the south and north face should be studied independently based on the room function. It also found reducing the WWR for bedrooms and windows on the northern façade resulted in reduced total annual building load.

• The Transactions of the Korea Information Processing Society
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• v.6 no.10
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• pp.2790-2796
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• 1999

In video-on-demand systems, the I.O bandwidth of video servers is the critical resource which contributes to increase in latency. Several approaches: bridging, piggybacking are used to reduce the I/O demand on the video server through sharing. Batching delays the requests for the different videos for a batching window so that more requests for the same video arriving during the current batching window may be served using the same stream. In this paper, we propose an adaptive reservation-based batching policy which dynamically reserves video server capacity for popoular videos according to video server loads. The performance of the proposed policy is evaluated through a simulation, and is compared with simple batching and static reservation-based batching policies. As the result, we know that the adaptive reservation-based batching policy more improves service ratio and average waiting time than simple batching and simple reservation-based batching policy more improves service ratio and average waiting time than simple batching and simple reservation-based batching polices.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.8 no.4
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• pp.110-121
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• 2009

It is essential to embed product quality in the design process to win the global competition. Many components found in many products including automobiles and electronic devices are fabricated using sheet metal forming processes. Wrinkle and fracture are two types of defects frequently found in the sheet metal forming process. Reducing such defects is a hard problem as they are affected by many uncontrollable factors. Attempts to solve the problem based on traditional deterministic optimization theories are often led to failures. Furthermore, the wrinkle and fracture are conflicting defects in such a way that reducing one defect leads to increasing the other. Hence, it is a difficult task to reduce both of them at the same time. In this research, a new design method for reducing the rates of conflicting defects under uncontrollable factors is presented by using operating window and a sequential search procedure. A new SN ratio is proposed to overcome the problems of a traditional SN ratio used in the operating window technique. The method is applied to optimizing the robust design of a sheet metal forming process. To show the effectiveness of the proposed method, a comparison is made between the traditional and the proposed methods using simulation software, applied to a design of particular sheet metal forming process problem. The results show that the proposed method always gives a more robust design that is less sensitive to noises than the traditional method.