• 조명전기설비학회논문지
• /
• 제24권9호
• /
• pp.16-19
• /
• 2010

In this paper, we fabricated angle-changable two-stage reflectors and measured the illuminance as a function of the angle of reflection plates. The illuminance of center areas could be controlled by changing the angle of upper reflection plates and the illuminated area expanded with reducing the angle of lower reflection plates. The bright spots could be moved using asymmetric structures of reflection plates. It was found that the distribution of illuminance matches well with the Gaussian distribution function. From the results of curve fitting, it was found that without reflectors, a half of the lights emitted from fluorescent lamp do not reach the working place. A simple model was suggested to explain the illuminance variation with the structure of reflector.

• 설비공학논문집
• /
• 제22권8호
• /
• pp.553-561
• /
• 2010

This study examines the influence of light variation on visual responses in a small office space where a daylight dimming control system is applied. Field measurements and survey were performed in a full-scale mocked-up small office space under clear sky day conditions. Maximum fluctuation range for desktop was 133.5 lx and it just happened once for entire monitoring period. For the majority of time, the fluctuation range did not exceed 50 lx, which did not cause visual discomfort to subjects. The daylight dimming control system successfully kept required illuminance levels for an office environment when desktop illuminance by daylight ranged up to 300 lx. The most serious contributor to the sensation of glare was direct daylight through window. The dimming of electric light was not a significant contributor to visual discomfort for the subjects under clear sky day conditions. Visual comfort was significantly influenced by the sensation of glare, feeling for visual stimulation and distraction, and required illuminance level.

• 설비공학논문집
• /
• 제23권3호
• /
• pp.231-242
• /
• 2011

This study examines influences of a daylight dimming control system on the variation of indoor illuminance and lighting energy savings in a small office space. Field measurements and a series of computation were performed for typical types of sky conditions in summer. Results indicate that the daylight illuminance under clear and partly-cloudy sky were close to the target illuminance during a majority of time due to a higher ratio of window to wall. However, the target illuminance was not kept successfully due to the variation of photosensor signals which were strongly influenced by desktop illuminance. The system with partially-shielded conditions succeeded to keep target illuminance under clear sky conditions. The system failed under overcast sky conditions since the electric light output from fixtures caused excessive signals to photosensors due to insufficient daylight on a desktop. Unshielded and fully-shielded conditions were not recommended for effective controls of the systems. The influence of lighting fixtures on photosensors should be minimized to achieve successful lighting controls by daylight dimming systems.

• 설비공학논문집
• /
• 제22권11호
• /
• pp.788-797
• /
• 2010

This study examines the influence of fluctuating daylight illuminance on daylight dimming control systems. Field measurements were performed for a full-scale mocked-up model under various daylight conditions in winter. Fluctuating ranges for a partially-shielded photosensor were great when the variation of sky ratio was great. When solar altitude was lower the illuminance and fluctuating range of illuminance were great due to the influence of direct components of daylight and the interrefelction between surfaces in rear area of space. It implies that daylight dimming system would not function effectively, unless the desktop illuminance by daylight is enough. Fluctuation ranges of photosensor illuminance were lower than 50 lx under clear sky conditions, but they were greater than 100 lx under partly-cloudy sky conditions. It means that the fluctuation range of electric light output of lighting fixture would greater under the partly-cloudy conditions and cause potential visual annoyance to occupants. Outdoor vertical illuminance reaching the windows would be an effective factor that can be used to predict the fluctuation of photosensor signals for effective controls of daylight dimming system.

• 한국태양에너지학회 논문집
• /
• 제26권3호
• /
• pp.33-43
• /
• 2006

Daylight dimming control system was analyzed for an indirect lighting system in a small office space with a double skin envelope system. Computer simulations were performed for photosensors with three shielding conditions. The photosensors were placed on the center of ceiling, and backwall. Three sky conditions defined by CIE were considered. Overall, control performance was not very excellent for all conditions. Fully-shielded photosensor achieved good control performance for some cases, but partially-shielded and unshielded photosensors failed to achieve target illuminance. The variation in desktop illuminance due to daylight was examined for a variety of daylight conditions. Linear correlation between desktop illuminance and photosensor illuminance was analyzed using ANOVA.

• 전기학회논문지P
• /
• 제61권1호
• /
• pp.55-58
• /
• 2012

By using EEG and HRV, subjects were estimated on their psychological and physiological reaction when reading psychrometric chart in 7 point century font, in an environmental test room in the condition of temperature 25[$^{\circ}C$], relative humidity 50[RH%], air current speed 0.02[m/sec], giving variation in illuminance to 0.1, 300, 600, 1000, 1300 and 1600[lux]. As a result, it was at 1300[lux] that absolute ${\alpha}$ wave, SMR, SDNN were most vitalized, and also both sides ${\alpha}$ wave asymmetry index, SEF50, HRT, stress and fatigue degree were at the lowest. It was found that a certain illuminance which minimizes psychological stress and fatigue degree while enhancing concentration and task achievement stably does exist.

• 한국안광학회지
• /
• 제5권1호
• /
• pp.13-18
• /
• 2000

본 논문에서는 다색 광원으로 대낮의 햇빛(daylight)을 표현하는 C광원을 사용하였으며, 입사광으로는 가우시안 형태의 진폭을 갖는 광을 고려하였다. 고려된 C광원에서 가우시안 진폭을 갖는 입사광의 단락된 정도에 따른 광학계의 상면과 축상의 조도(illuminance) 분포와 색도(chromaticity) 변화를 조사하였다. 이때 색감각 함수는 1931년 CIE 자료를 사용하였으며, 고려한 파장은 380nm에서 780nm까지이다. 본 연구에서 고려된 가우시안 진폭을 갖는 입사광의 단락된 정도가 증가할수록 상면에서 중심 spot의 크기가 작아졌으며, 축상에서의 초점 심도가 작아졌다. 색도 변화는 상면과 축상에서 단락된 정도가 증가할수록 심하게 변화하였으며, 조도의 세기가 중앙 극대점에서 점차 감소할수록 광학계의 색도 변화가 심해졌다. 또한 초점 심도가 증가할수록 광학계의 색도 변화가 작게 나타났다.

• 천문학회지
• /
• 제45권5호
• /
• pp.111-116
• /
• 2012

We present a mathematical model that predicts the variation of illuminance during a solar eclipse, considering continuous effects of limb darkening. We assume that (1) the Sun and the Moon constitute perfect spheres, (2) the Moon crosses the Sun with a constant apparent velocity, and (3) sunspots, prominences, and coronae can be neglected. We compare predictions of this model with actual measurements made by M$\ddot{o}$llmann & Vollmer (2006) during a total solar eclipse in Turkey, and with predictions of existing models. The new model is shown to describe the actual phenomenon more accurately than existing models.

• 한국조명전기설비학회:학술대회논문집
• /
• 한국조명전기설비학회 2005년도 학술대회 논문집
• /
• pp.213-216
• /
• 2005

Recently, energy depleting problem have risen seriously. Many studies of daylight responsive dimming system for saving of lighting energy in office buildings have been done actively. Most of studies are focused on the accuracy. However if the variation of dimming levels is changed too often, occupants would feel uncomfortable. First, illuminance changes which occupants couldn't detect are studied through analyzing foreign studies. Second, workplan illuminance from daylight in each sky condition is measured. Because the dimming level In daylight responsive dimming system is dependent on the workplan illuminance from daylight. In conclusion, the most appropriate polling periods to daylight responsive dimming system for occupant's visual comfort was determined.

• 설비공학논문집
• /
• 제23권1호
• /
• pp.61-72
• /
• 2011

The influences of luminous environment on visual responses and fatigue sensation in art galleries were examined in this study. Field measurements and survey were performed in three galleries under various illuminance and luminous conditions. Result implies that vertical illuminance on art paintings needed to be somewhere between 200 lx and 300 lx to avoid visual discomfort. The vertical illuminance difference between consecutive paintings should not exceed 100 lx to keep visually comfortable environment. Visual comfort sensations were related to glare, visual stimulus, reflection from paintings, illuminance variation, and the sensation that subjects can clearly see the paintings. The sensation of fatigue was significantly influenced by the changes of luminous element that caused visual stimulus and discomfort. The sensation of eye fatigue among physical fatigue was primarily influenced by the glare, visual stimulus and comfort. The psychological fatigue was also influenced by eye fatigue, visual comfort, brightness and satisfaction with color of light.