• Journal of the Korean Institute of Landscape Architecture
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• v.33 no.4 s.111
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• pp.119-128
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• 2005

This study was carried out to obtain fundamental information of growth response of interior landscape plants under a fluorescent lighting, a sunlight at indoor. Ficus elastica Roxb. vu. decora Hort, Spathiphyllum 'Clevelandii', Codiaeum variegatum Blume var. pictum Mvell. Arg. 'Exalant' and Cordyline terminalis Kunth var. red edge Hort were examined under 100lux, 500lux, 1,000lux and 2,000lux light intensity consisted of fluorescent lighting and sunlight at indoor condition. Result of experiments are as follows; 1. A Ficus elastica Roxb. var. decora Hort plant growth status was better showed under fluorescent lighting than sunlight. A plant growth status showed the best result under 2,000lux light intensity of fluorescent lighting in cases of all conditions. 2. A Spathiphyllum 'Clevelandii' showed the best effective adaptations under law intensity among experimental plants. A Spathiphyllum 'Clevelandii', plant growth status was better showed under fluorescent lighting than sunlight. A plant growth status showed the best result under 1,000lux light intensity of fluorescent lighting in cases of all conditions. 3. It need the best high establishment of fluorescent lighting among experimental plants for good plant growth. A Codiaeum variegatum Blume var. pictum Mvell. Arg. 'Exalant' plant growth status was better showed under fluorescent lighting than sunlight. A plant growth status was better showed under high light intensity in case of same light source. A plant growth status showed the best result under 2,000lux light intensity of fluorescent lighting. 4. A Cordyline terminalis Kunth var. red edge Hort plant growth status was better showed under fluorescent lighting than sunlight. but, A plant growth status was better showed under $500lux\sim1,000lux$ than 2,000lux in cases of all intensity of fluorescent lighting. while, A plant growth status was better showed under $1,000lux\sim2,000lux$ in cases of all intensity of sunlight.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2020.08a
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• pp.63-63
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• 2020

This study investigated the growth of native ferns under indoor light intensities to identify the introduction possibility as in-door ornamental plants. Three evergreen perennial fern species used in this experiment were Coniogramme japonica (Thunb.) Diels, Woodwardia japonica (L. f.) Sm., and Cyclosorus acuminatus (Houtt.) Nakai ex H. Itô. The light intensities were adjusted to 10, 50, 100 and 200 PPFD (µmol·m^-2·s^-1) based on the measurement of the various indoor light quantities. The experiment was conducted for a total of 8 weeks, and the light period (12/12h), temperature (25±1℃), and humidity (55±3%) were maintained during the experiment. The control plant group was grown in glass greenhouse for the same period. As the result of the study, in door C. japonica showed better growth under light intensities of 100, 200 PPFD. However, withering of the plants were observed under all light intensities except the control, which causes an ornamental value decrease. This seems to be related to the increase of DIo/RC value in chlorophyll fluorescence parameters. In the W. japonica growth data, the plant height was not significantly different from the control but, the leaf number decreased more than a two-fold. Also, the formed leaves turned brown and showed a poor growth and SPAD value at 200 PPFD had decreased significantly. Growth data of C. acuminatus was not significantly different with the control at all light intensities however, withering was observed at 100 and 200 PPFD. In chlorophyll fluorescence parameters, significant decrease in Pi_Abs and increase in DIo/RC value at 200 PPFD impose that stress caused by the intense light might be the reason of the withering of the plants.

• Journal of Satellite, Information and Communications
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• v.5 no.2
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• pp.69-74
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• 2010

In this paper, we present an indoor positioning system based on light emitting diode (LED). Because LED is a semiconductor light emitting device, we can easily switch and modulate electrical signals into lightwave signals at high speed using LEDs. We assigned unique 8-bit ID address to each LED lights. Photo diode receives data from 16-LED lights and takes correlation coefficient beteween received data and each LED-ID. Using correlation coefficient, proposed positioning system shows resolution of 50 cm in dimensions of $4\;m\;{\times}\;4\;m\;{\times}\;2\;m$.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.7
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• pp.647-654
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• 2016

Indoor localization based on visible-light communication using the received signal strength intensity (RSSI) has been widely studied because of its high accuracy compared with other wireless localization methods. However, because the RSSI can vary according to the inclination and azimuth of the receiver, a large error can occur, even at the same position. In this paper, we propose a visible-light communication-based 3-D indoor positioning algorithm using the Gauss-Newton technique in order to reduce the errors caused by the change in the inclination of the receiver. The proposed system reduces the amount of computations by selecting the initial position of the receiver through the linear least-squares method (LSM), which is applied to the RSSIs, and improves the position accuracy by applying the Gauss-Newton technique to the 3-D nonlinear model that contains the RSSIs acquired by the changes in the azimuth and inclination of the receiver. In order to verify the validity of the proposed algorithm in an indoor space with dimensions of $6{\times}6{\times}3m$ where 16 LED lights are installed, we compare and analyze the errors of the conventional linear LSM-based trilateration technique and the proposed algorithm according to the changes in the inclination and azimuth of the receiver. The experimental results show that the location accuracy of the proposed algorithm is improved by 82.5% compared to the conventional LSM-based trilateration technique.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2020.08a
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• pp.55-55
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• 2020

This study investigated the growth and chlorophyll fluorescence reactions of three Ardisia genus grown under various indoor light intensity conditions with the aim of evaluating their suitability as indoor plants. Young seedlings of A. crispa (Thunb.) A.DC., A. pusilla DC., and A. japonica (Thunb.) Blume were used in the experiment. The plants were cultivated indoors for 10 weeks under different light intensities: 10, 50, 100, and 200 PPFD (μmol·m^-2·s^-1), and their growth was compared with that of plants cultivated in a greenhouse during the same period (mean value 236.8±20.4 PPFD at noon). Also, chlorophyll fluorescence analysis was investigated with a portable PAM fluorometer. The indoor plants were maintained at 12/12 h photoperiod, temperature at 25±1℃, and humidity at 55±3%. Irrigation frequency (once every three days) was the same for the indoors and the greenhouse. The results of growth in three Ardisia plants showed that almost all parameters except leaf number and chlorophyll content had similar levels regardless of light intensity. A. crispa and A. pusilla plants grown in 200 PPFD were investigated to have low chlorophyll contents. Meanwhile, chlorophyll fluorescence parameters differed based on light levels. In A. crispa, the Fv/Fm (0.77), DIo/RC (0.47) and Fm/Fo (4.77) parameters tended to be poor at 200 PPFD compared to those at other light intensities. Similarly, the DIo/RC, Fm/Fo, and Pi_Abs parameters of A. pusilla plant (200 PPFD) are 0.45, 4.48 and 2.42, respectively, which can be considered stress. The analysis of fluorescence in A. japonica showed that all parameters except ETo/RC had similar levels regardless of light intensity. The ETo/RC parameter was 0.49 and 0.72 in the control plants and plants 200 PPFD, respectively, which was lower than those in plants at other light intensities. Therefore, it seems that the relatively high light intensity acted as a stressor for Ardisia plants.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.6
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• pp.207-213
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• 2014

In this paper, we propose Bluetooth based on efficient indoor-emotion-lighting control system. The proposed Bluetooth based on indoor-emotion-lighting control system was designed to be automatically controlled by the motion sensor light and using a Bluetooth module may be controlled to light up or mobile PC, wall pad. In addition, It was designed the LED lighting On/Off control the environment according to Humidity, the temperature, illumination, motion sensors. System based on the bluetooth is automatic control possible using the illumination sensor, and by selecting the desired lighting partial control can be designed. The experimental efficiency results of the proposed indoor-emotion-lighting control system were designed to provide an internal environment adapted to a resident, were able to maximize the energy savings, have reduced power consumption than the traditional simple On/Off control system.

• Environmental Engineering Research
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• v.13 no.4
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• pp.171-176
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• 2008

Studies on visible-light-driven photocatalysis of air pollutants at indoor air quality (IAQ) levels have been limited. Current study investigated visible-light derived photocatalysis with N-doped and S-doped titanium dioxide ($TiO_2$) for the control of benzene at indoor levels. Two preparation processes were employed for each of the two types of photocatalyst: urea-Degussa P-25 $TiO_2$ and titania-colloid methods for the N-doped $TiO_2$; and titanium isopropoxid- and tetraisopropoxide-thiourea methods for the S-doped $TiO_2$. Furthermore, two coating methods (EDTA- and acetylacetone-dissolving methods) were tested for both the N-doped and S-doped $TiO_2$. The two coating methods exhibited different photocatalytic degradation efficiency for the N-doped photocatalysts, whereas they did not exhibit any difference for the S-doped photocatalysts. In addition, the two doping processes showed different photocatalytic degradation efficiency for both the S-doped and N-doped photocatalysts. For both the N-doped and S-doped $TiO_2$, the photocatalytic oxidation (PCO) efficiency increased as the hydraulic diameter (HD) decreased. The degradation efficiency determined via a PCO system with visible-light induced $TiO_2$ was lower than that with UV-light induced unmodified $TiO_2$, which was obtained from previous studies. Nevertheless, it is noteworthy that for the photocatalytic annular reactor with the HD of 0.5 cm, PCO efficiency increased up to 52% for the N-doped $TiO_2$ and 60% for the S-doped $TiO_2$. Consequently, when combined with the advantage of visible light use over UV light use, it is suggested that with appropriate HD conditions, the visible-light-assisted photocatalytic systems can also become an important tool for improving IAQ.

• IEMEK Journal of Embedded Systems and Applications
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• v.17 no.1
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• pp.9-17
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• 2022

As the COVID-19 pandemic situation worsens, the time spent indoors increases, and the exposure to indoor environmental pollution such as indoor air pollution and noise also increases, causing problems such as deterioration of human health, stress, and discord between neighbors. This paper designs and implements a system that measures and monitors indoor air quality and noise, which are representative evaluation criteria of the indoor environment. The system proposed in this paper consists of a particulate matter measurement subsystem that measures and corrects the concentration of particulate matters to monitor indoor air quality, and a noise measurement subsystem that detects changes in sound and converts it to a sound pressure level. The concentration of indoor particulate matters is measured using a laser-based light scattering method, and an error caused by temperature and humidity is compensated in this paper. For indoor noise measurement, the voltage measured through a microphone is basically measured, Fourier transform is performed to classify it by frequency, and then A-weighting is performed to correct loudness equality. Then, the RMS value is obtained, high-frequency noise is removed by performing time-weighting, and then SPL is obtained. Finally, the equivalent noise level for 1 minute and 5 minutes are calculated to show the indoor noise level. In order to classify noise into direct impact sound and air transmission noise, a piezo vibration sensors is mounted to determine the presence or absence of direct impact transmitted through the wall. For performance evaluation, the error of particulate matter measurement is analyzed through TSI's AM510 instrument. and compare the noise error with CEM's noise measurement system.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.4
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• pp.221-229
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• 2008

This study analyze indoor thermal comfort properties such as PMV, PPD and fluid variables when the cooling loads are light, occupant and ventilation. There are 6 cases to study for the indoor unit installation conditions and ventilation rates. Numerical method is used to study the indoor environmental properties and experimental study is adapted to analyze reaching time by variable cooling load conditions.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.10
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• pp.2062-2064
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• 2015

In this paper, we propose indoor positioning algorithm performed at the image sensor equipped in mobile station, which receives the light signal from LED panels. To evaluate the performance of positioning algorithm, we consider the ambient noise existing indoor environment, and it is found that the proposed algorithm estimates the position of mobile station with high accuracy regardless of existence of ambient noise.