• Journal of the Korean Society of Mechanical Technology
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• v.13 no.4
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• pp.93-99
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• 2011

This paper presents a new type of optical silicon accelerometer using deep reactive ion etching (DRIE) and micro-stereolithography technology. Optical silicon accelerometer is based on a mass suspended by four vertical beams. A vertical shutter at the end of the mass can only moves along the sensing axis in the optical path between two single-mode optical fibers. The shutter modulates intensity of light from a laser diode reaching a photo detector. With the DRIE technique for (100) silicon, it is possible to etch a vertical shutter and beam. This ensures low sensitivity to accelerations that are not along the sensing axis. The microstructure for sensor packaging and optical fiber fixing was fabricated using micro stereolithography technology. Designed sensors are two types and each resonant frequency is about 15 kHz and 5 kHz.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.4
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• pp.1474-1479
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• 2012

Rotational smart lighting control system provides artificial light to plants on planting board by rotational lighting system. As the lighting system of existing plant factory has high cost problem due to the installation for many lighting equipments, the lighting system was developed to rotate less number of lighting equipments to reduce cost. In this paper, the illuminance, luminous flux and photosynthetic photon flux density(PPFD) that plants need to grow were calculated. And the light intensity at each measured location considering the rotational speed of blade were analyzed by the simulation and the experiment.

• Journal of Korean Society of Forest Science
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• v.100 no.4
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• pp.609-615
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• 2011

Forsythia saxatilis is a Korean endemic plant designated as rare and endangered by the Korea Forest Service (KFS). Growth and physiological characteristics of F. saxatilis were investigated under two different light intensities in order to figure out an appropriate growth environment for conservation and restoration of the species in its natural habitat. Shoot length, leaf size and weight, photosynthetic pigment content and photosynthetic parameters were measured for F. saxatilis grown at two experimental plots under relative light intensities (RLI) of 20% and 60% of the full sun, respectively. Fresh leaf weight of plants grown under high relative light intensities (RLI-60) exceeded that of plants grown at 20% RLI. The ratio of fresh leaf weight to leaf size at RLI-60 was 1.47 times superior comparing to that recorded at RLI-20. The content of photosynthetic pigments such as chlorophyll a, b and carotenoid were higher in plants grown at RLI-60, whereas the ratio of total chlorophyll to carotenoid content was higher in the leaves at RLI-20. Photosynthetic rate, stomatal conductance and transpiration rate at RLI-60 were, respectively, 2.5, 2.65 and 1.79 times higher comparing to those recorded at RLI-20. Water use efficiency, however, was higher at RLI-20. The chlorophyll/nitrogen ratio was 1.83 times higher at RLI-20 than at RLI-60. In contrast, the ratio of net photosynthesis to chlorophyll content at RLI-60 was 2.58 times higher than that of RLI-20. In conclusion, light intensity might be the major factor affecting growth and physiological characteristics of F. saxatilis grown under canopy of tall tree species.

• Journal of Applied Biological Chemistry
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• v.64 no.4
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• pp.351-356
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• 2021

Changing environmental conditions can affect plant growth by influencing water and nutrient transport and photosynthesis. Plant physiological responses under changing environmental conditions can be non-destructively monitored using electrodes as plant induced electrical signal (PIES). Objective of the study was to monitor PIES in response to increased CO₂ and decreased photosynthetic photon flux density (PPFD). The PIES increased during day time when transpiration and photosynthesis occurs and monitored CO₂ concentration was negatively correlated to the PIES. Enhanced CO₂ concentration slightly reduced PIES, but the effect of increased CO₂ was limited by light intensity. The effect of reduced PPFD was not appeared immediately because water and nutrient transport was not promptly affected by the light. The study was conducted to evaluate short-term effect of increasing CO₂ and decreasing PPFD, hence proline content and chlorophyll fluorescence was not significantly affected by the conditions.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.54 no.4
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• pp.397-406
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• 2009

This study was carried out to investigate the microclimate (photosynthetically active radiation and temperature) response to different shading materials(shade plate, and polyethylene net) on Korean ginseng(Panax ginseng C.A. Meyer) bed. Photosynthetically active radiation(PAR) under polyethylene net was approximately 24 ~ 30% higher than that under shade plate on sunny day. Also, PAR was remarkably decreased from the front to the rear rows of ginseng beds. Temperature under polyethylene net was higher than that of shade plate. Internal temperature under polyethylene net was 1.9 ~ 3.1% higher than that under shade plate at the different rows of ginseng bed. Mean of total daily temperature under polyethylene net was higher at the rear rows than at the front rows, while that under shade plate was higher at the front rows than at the rear row of ginseng bed. Mean of total daily temperature on sunny days(April 15 and May 17) was 7.3% lower under shade plate than above outside but, polyethylene net was 0.7% high, while that on cloudy days(April 11 and May 15) was 1.6% higher under polyethylene net than above outside, but shade plate was 0.7% low. Also, overall mean of total daily temperature under polyethylene net was 7.0, 7.8, and 8.8 % on sunny day(April 15 and May 17), and 1.7, 1.6, and 3.5% on cloudy day(April 11 and May 15) higher than that under shade plate, respectively. The SPAD values of 6 years old ginseng at two point(front, center) in bed under shade plate showed the highest value, and the lowest under polyethylene net. The SPAD of 6 years old ginseng at rear in bed was not statistically significant under two shading materials.

• Korean Journal of Environmental Biology
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• v.19 no.1
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• pp.43-48
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• 2001

Chlorophyll fluorescence of needles of Korean fir (Abies koreana) plants and environmental factors of their natural habitat were investigated in order to obtain the information for environmental adaptation and conservation of Korean fir plants. The photochemical efficiency of photosystem II, Fv/Fm, of Korean fir needles was significantly low (0.19-0.36) in the winter, whereas it was high (0.8-0.86) in the summer. The Fv/Fm value of the winter was slightly higher at mid-day than at dawn, suggesting that mid-day environmental conditions of the winter were favorable on needles of Korean fir plants. In contrast, the mid-day Fv/Fm value of the summer maintained high (around 0.8). It indicates that mid-day environmental conditions of the summer did not induce photodamage, although it caused a slight decrease in the Fv/Fm values. The non-photochemical fluorescence quenching (NPQ) of Korean fir needles was very low (0-0.01) all through the day in the winter. However, it was high (0.76) at mid-day in the summer. These results suggest that Korean fir plants have a system for the protection of PS II from mid-day environmental stresses of the summer. In the winter, the Fv/Fm values were positively correlated with temperature, light intensity and relative humidity, although NPQ values showed no correlation with any of them. In the summer, the Fv/Fm values were positively correlated with relative humidity but negatively correlated with temperature and light intensity. These results indicate that increase of tempera-ture, light intensity and relative humidity lead to promotion of the photochemical efficiency in the winter and high temperature and light intensity may cause photoinhibition in the summer.

• Journal of Bio-Environment Control
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• v.29 no.4
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• pp.399-405
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• 2020

Recently, it is difficult to produce uniform scions and rootstocks with high quality in a greenhouse due to weather extremes. The closed transplant production system is useful for producing scions and rootstocks with desirable morphological characteristics by environment control regardless of weather outside. In this study, we investigated transpiration rates and growth of cucumber and tomato scions and rootstocks grown under different light intensity conditions for precise irrigation control in a closed transplant production system. Hanging system to measure continuously the weight of plug tray consisting of seedlings and substrate with load-cell was installed in each growing bed. Using this system, we confirmed initial wilting point of cucumber and tomato seedlings, and conducted subirrigation when moisture content of substrate was not below 50%. The irrigation time of cucumber scions and rootstocks were 7 and 6 days after sowing, respectively. In tomato scions and rootstocks grown under PPF (photosynthetic photon flux) 300 μmol·m^-2·s^-1, the irrigation time were 5, 8, 11, and 13 days after sowing. Increasing light intensity increased transpiration rates and differences of transpiration rates by light intensity was higher in tomato seedlings. The growth of cucumber and tomato seedlings was promoted by increasing light intensity, especially, hypocotyl elongation and stem thickening was affected by light intensity. Cumulative transpiration rate of plug tray in cucumber and tomato seedlings was increased by increasing light intensity, and daily transpiration rate per seedling was regressed by 1st-order linear equation with high correlation coefficient. Estimation of transpiration rates by weighing continuously plug tray of vegetable seedlings can be useful to control more accurately irrigation schedule in a closed transplant production system.

• Korean Journal of Ecology and Environment
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• v.46 no.4
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• pp.513-523
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• 2013

This ecological study was conducted to analyze seasonal variation characteristics of Zostera marina at HAENAM SAGUMI on the Southern Coast of Korea. Environmental characteristics, plant morphological characteristics, shoot density, biomass, and leaf production were monitored from August 2008 to March 2011. Zostera marina occurred in the subtidal zone from 0 to 2.5 m below the mean low water level. Water temperature showed a clear annual pattern, with increase in spring and summer, and decreases in fall and winter. Irradiance showed seasonal variation, even though daily weather condition has short-term variation in the incident irradiation. Plant morphological characteristics, shoot density, biomass, and leaf production showed clear seasonal variation. Seasonal variation in the above biomass of Zostera marina was mainly caused by changes in shoot length. We found that there are correlations between environmental characteristics (water temperature, irradiation) and the growth of Zostera marina. There is stronger correlation between water temperature and the growth of Zostera marina, compared to the correlation between irradiation and the growth of Zostera marina. In particular, the growth of Zostera marina is inhibited by both higher and lower water temperature.

• The Journal of the Convergence on Culture Technology
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• v.9 no.6
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• pp.1097-1101
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• 2023

As paprika plants grew in a glass greenhouse from November 2022 to March 2023, the amount of light at each plant height, leaf temperature, transpiration rate, and water vapor pressure were measured. Accumulated leaf temperature was higher at the top of the plant than at the bottom. Over time, the leaf temperature measured around 11-13 AM changed from 26.55→23.21→22.80→26.67℃ in the lower part (pL), and from 26.52→24.48→24.55→27.78℃ in the upper part (pAs). And VPD changed from 1.45→0.94→0.74→1.46kPa in pL and from 1.11→0.86→0.71→1.28kPa in pAs. Accordingly, the transpiration rate changed from 4.25→0.17→4.08→0.52mmol·m^-2·s^-1 in pL, 7.61→2.45→1.94→4.39→0.52mmol·m^-2·s^-1 in pAs, and from pAs to pL. It was significantly higher than The difference between the lower and upper parts (pL-pAs) was higher in pAs than pL in leaf temperature, light intensity, and transpiration rate, but the water vapor pressure difference was higher in pL. In this way, paprika shows differences in the environment and photosynthetic factors between the upper and lower parts during the cultivation period, so it is judged that this needs to be taken into consideration in future research.

• Journal of Korean Society of societal Security
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• v.1 no.3
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• pp.77-81
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• 2008

In this paper, we introduce a multi purpose environmental monitoring system developed as a commercially available standard using the technique of hetero-core spliced fiber optic sensor. The monitoring system has been tested and evaluated in a possible outdoor condition in view of the full scaled operation at actual sites to be monitored. Additionally, the developed system in this work conveniently provides us with various options of sensor modules intended for monitoring such physical quantities as displacement, distortion, pressure, binary states, and liquid adhesion. Two channels of optical fiber line were monitored, in each of which three displacement sensor modules were connected in series, in order to examine the performance to a pseudo-cracking experiment in the outdoor situation, and to clarify temperature influences to the system in terms of the coupling of optical connectors and the OTDR stability. The pseudo-cracking experiment successfully observed the actually given cracks by means of calculation based on the detected displacement values and their geometrical arrangement of the used sensor modules. And the robustness to the temperature is verified in the various temperature change.