• Journal of Korean Tunnelling and Underground Space Association
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• v.15 no.5
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• pp.497-504
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• 2013

This research uses numerical analysis to examine the tunnel portal landscape affecting the brightness level of interior lighting when designing lights for road tunnels through the L20 method. In order to extract the brightness recognition per form of a tunnel entrance and to evaluate the effects of the characteristics of the materials of facilities near a tunnel portal, brightness analysis was conducted by filming brightness on a video photometer called Hi-land Elf System, and a surface brightness photometer called LMK Mobile Advanced. Tunnels in Korea are mostly distributed in mountain areas; thus, the ratio occupied by the sky, which has the highest brightness within the angle of L20, is close to zero, while most of the ratio was occupied by brightness by the area near the tunnel entrance or road surface. However, for a tunnel portal retaing wall, which allows the width of a tunnel entrance to seem wider within the L20 angle, appeared to be have higher brightness compared to nearby areas or the surface, which is an element increasing the tunnel portal brightness within the tunnel, and the road facilities near the tunnel portal appeared to have an effect on the brightness as well. Thus, when designing tunnel lights based on brightness, the form of the tunnel entrance and the area width, material, and color of areas near the tunnel portal appeared to affect outside brightness and become an element affecting the establishment of the brightness level of the interior lights of tunnels. Consequently, reviewing such matters is a prerequisite when designing tunnel portal landscape.

• Journal of the Korea Computer Graphics Society
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• v.27 no.3
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• pp.31-42
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• 2021

We propose a deep learning-based method that can estimate an appropriate lighting of both indoor and outdoor images. The method consists of two networks: Crop-to-PanoLDR network and LDR-to-HDR network. The Crop-to-PanoLDR network predicts a low dynamic range (LDR) environment map from a single partially observed normal field of view image, and the LDR-to-HDR network transforms the predicted LDR image into a high dynamic range (HDR) environment map which includes the high intensity light information. The HDR environment map generated through this process is applied when rendering virtual objects in the given image. The direction of the estimated light along with ambient light illuminating the virtual object is examined to verify the effectiveness of the proposed method. For this, the results from our method are compared with those from the methods that consider either indoor images or outdoor images only. In addition, the effect of the loss function, which plays the role of classifying images into indoor or outdoor was tested and verified. Finally, a user test was conducted to compare the quality of the environment map created in this study with those created by existing research.

• Journal of Convergence for Information Technology
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• v.8 no.6
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• pp.243-249
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• 2018

In this paper, we analyzed the effect of modulation scheme and modulation scheme on the dimming level of visible light communication system and studied the effect of distortion due to delayed signal. Currently, the modulation schemes most commonly used in visible light communication result in increasing the communication performance but reducing the brightness of the entire illumination. Continuous Burst Zero Duration will severely degrade lighting. This degrades not only the illumination but also the performance of the whole system and causes Flicker phenomenon. In this paper, we analyze the relationship between modulation technique and illumination - communication performance and investigate the effect of signal delay on visible light communication system. Through simulation, we analyze the performance of IPI-OOK which has the best communication-lighting performance and propose future research directions accordingly.

• Korean Institute of Interior Design Journal
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• v.15 no.3 s.56
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• pp.65-74
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• 2006

This study is intended to analyze the way of incorporating the effect of natural light into the architectural space design by Le Cobusier. The composition of modem architectural space is significantly different from that of classical architecture. Such transition is attributable to the change of tectonic method which was supported by the development of new materials and structural systems. In addition, the effect of natural light systems which is one of the main elements in architectural space has undergone significant changes in modern ages. Moreover, Le Corbusier introduces the new concept of natural light in his works. By bringing the above two trends together, this study analyzed the way how Le Cobusier applied light effect in his works. Specifically, findings regarding the 'traffic flow in the space' with the light, 'elevation effect' with the 'Brise soleil' in Le Cobusier's works were presented. And also the way of lighting the object in the space was presented.

• Journal of the Korean Ceramic Society
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• v.50 no.1
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• pp.75-81
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• 2013

We fabricated translucent opal glass to replace the polycarbonate diffuser in LED lighting systems in order to solve the durability problem. Batch materials of opal glass with a composition of calcium phosphate were created and melted at $1550^{\circ}C$, and the effect of opaqueness was identified by an addition of 1~7% calcium phosphate as an opacifier raw material. As a result, translucent opal glass was obtained by the melting of the mixed batch materials with a composition of more than 5% calcium phosphate glass at $1550^{\circ}C$ for 2 hrs, which had excellent optical properties for the diffuser of a LED lighting system with no dazzling from direct light by a high haze value exceeding 90% and a low parallel transmittance value of about 5%. For the thermal properties, the thermal expansion coefficient was found to be $5.6{\sim}5.9{\times}10^{-6}/^{\circ}C$ and the softening point was $874{\sim}884^{\circ}C$. In addition, good thermal properties such as good thermal shock resistance and feasibility for use with a general manufacturing process during the forming of glass tubes and bulbs were noted. Therefore, it is concluded that this translucent opal glass can be used as a glass diffuser material for LED lighting due to its high heat resistance and high durability as a replacement for a polycarbonate diffuser.

• Journal of Power Electronics
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• v.15 no.3
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• pp.621-633
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• 2015

This paper proposes the analysis and design of a DC-side symmetrical zero-current-switching (ZCS) Class-D current-source driven resonant rectifier to improve the low power-factor and high line current harmonic distortion of lighting applications. An analysis of the junction capacitance effect of Class-D ZCS rectifier diodes, which has a significant impact on line current harmonic distortion, is discussed in this paper. The design procedure is based on the principle of the symmetrical Class-D ZCS rectifier, which ensures more accurate results and provides a more systematic and feasible analysis methodology. Improvement in the power quality is achieved by using the output characteristics of the DC-side Class-D ZCS rectifier, which is inserted between the front-end bridge-rectifier and the bulk-filter capacitor. By using this symmetrical topology, the conduction angle of the bridge-rectifier diode current is increased and the low line harmonic distortion and power-factor near unity were naturally achieved. The peak and ripple values of the line current are also reduced, which allows for a reduced filter-inductor volume of the electromagnetic interference (EMI) filter. In addition, low-cost standard-recovery diodes can be employed as a bridge-rectifier. The validity of the theoretical analysis is confirmed by simulation and experimental results.

• Journal of the Korean Institute of Landscape Architecture
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• v.32 no.1
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• pp.23-32
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• 2004

This study aims to examine constraints on visits to urban community parks and to find ways to elevate the efficient use of parks. To achieve this, the study relied on empirical study method and the descriptive method; additionally, present condition survey was performed with a user interview, on the assumption that a park visit is a form of leisure. As a result, the item of 'insufficient lighting facilities' shows the highest mean and the item of 'low quality of park' follows Previous research also revealed that the item of 'the lack of lighting facilities' is a major factor on user dissatisfaction, so a design and management program for night time users are fully researched and elaborately accomplished. Also, the high response of 'low quality of park' shows that the park supply policy in Korea focusses mainly on quantity so far, and it shows that user's dissatisfaction for park facilities becomes one of the major constraints of park visit. The factor analysis, on the object of 35 items except 2 items, appeared 5 factors: accessibility, inner discord, companion, family matters, park-itself-matters. Oneway Anova test showed that 4 factors except 'park-itself-matters' have reliable difference in constraint cognition by age and education. The visit constraint of 'park-itself-matters' did not appear different by any personal characteristics. Without regard to personal characteristics, it is regarded that this factor has the greatest effect upon park visits. In general, people who are disadvantaged strongly cognize constraints even in leisure such as a park visit, which is a simple and inexpensive leisure activity. Therefore, a park like a pocket park, which is small but located in a neighborhood, is more needed than a central park like a symbolic and huge park in every new city. Careful concern for night activity should be accomplished in the planning process.

• Journal of Broadcast Engineering
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• v.21 no.5
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• pp.749-759
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• 2016

As image contents in broadcasting have been created in HDTVs and monitors have been commercialized, facial expression of objects in broadcasting lighting has become a very significant task. Figure modeling of objects in HDTVs requires smoother and cleaner video images owing to the expansion of precision of image expression by light. Lighting methods that enlighten characters in the digital generation have come to require a new change. Character modeling methods used on expression features of underlight are receiving attention for aesthetic expression of figures in HD images. Accordingly, the influence of underlight light source intensity, distance, and size on character modeling characteristics was experimentally measured and comparatively analyzed. The experiment results show that good results can be obtained only when the intensity is 17%∼25.5% in contrast to total brightness, distance is beyond 40cm, and the size is at least 20cm, to exhibit the optimum effect of underlight. This data will become material with high usage to gain smoother and cleaner images of characters in future high-quality images.

• Journal of Biosystems Engineering
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• v.38 no.4
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• pp.279-286
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• 2013

Purpose: This study was conducted to analyze the utilization efficiencies of electric energy and photosynthetically active radiation of lettuce grown under red LED, blue LED and fluorescent lamps with different photoperiods. Methods: Red LED with peak wavelength of 660 nm and blue LED with peak wavelength of 450 nm were used to analyze the effect of three levels of photoperiod (12/12 h, 16/8 h, 20/4 h) of LED illumination on light utilization efficiency of lettuce grown hydroponically in a closed plant production system (CPPS). Cool-white fluorescent lamps (FL) were used as the control. Photosynthetic photon flux, air temperature and relative humidity in CPPS were maintained at 230 ${\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, $22/18^{\circ}C$ (light/darkness), and 70%, respectively. Electric conductivity and pH were controlled at 1.5-1.8 $dS{\cdot}m^{-1}$ and 5.5-6.0, respectively. The light utilization efficiency based on the chemical energy converted by photosynthesis, the accumulated electric energy consumed by artificial lighting sources, and the accumulated photosynthetically active radiation illuminated from artificial lighting sources were calculated. Results: As compared to the control, we found that the accumulated electric energy consumption decreased by 75.6% for red LED and by 70.7% for blue LED. The accumulated photosynthetically active radiation illuminated from red LED and blue LED decreased by 43.8% and 33.5%, respectively, compared with the control. The electric energy utilization efficiency (EEUE) of lettuce at growth stage 2 was 1.29-2.06% for red LED, 0.76-1.53% for blue LED, and 0.25-0.41% for FL. The photosynthetically active radiation utilization efficiency (PARUE) of lettuce was 6.25-9.95% for red LED, 3.75-7.49% for blue LED, and 2.77-4.62% for FL. EEUE and PARUE significantly increased with the increasing light period. Conclusions: From these results, illumination time of 16-20 h in a day was proposed to improve the light utilization efficiency of lettuce grown in a plant factory.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.12
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• pp.1-5
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• 2014

Since the "Light Pollution Prevention Act" was executed, the installation of the light cutoff panel to the security lightings which caused light trespass has been increased in the local government. The light cutoff panel is effective in reducing the light trespass in term of the cost-benefit. Because the installation of the light cutoff panel is inexpensive than the change of the security lighting. But the reflected light from the surface of the light cutoff panel has been regarded as another light pollution problem to solve. Therefore, we try to improve light cutoff panel by changing the light reflectivity characteristic of the surface of the light cutoff panel. First, we laminated the surface of light cutoff panel by black powder to reduce the light reflectivity of the light cutoff panel. After the black powder lamination, the light reflectivity on the light cutoff panel improved from 85% to 5%. And we compared reflected light caused by black powder laminated light cutoff panel with the one of no surface treatment cutoff panel. The vertical illuminance was measured at 3, 6, 9m in front of the security lighting and 3, 6, 9, 12, 15, 18m in back of the security lighting to evaluate the reflected light. And the measurement height was determined of 1.5m considering the height of the 1th floor of an apartment house. In this study, we found that the reflected light from the light cutoff panel can be reduced about 90% by the black powder lamination method. The results derived from this study will be helpful to develope the various kind of light cutoff panel which minimize the adverse effect like reflected light of light cutoff panel.