• KIEAE Journal
• /
• v.13 no.2
• /
• pp.61-66
• /
• 2013

This study is to eliminate the need for conventional high density plant factory's artificial light source such as LED to reduce the initial investment of the light source installation as well as the operation cost. Use of solar light could enhance the quality of the vegetables similar to those grown in the natural environment. Provision of solar light into the multilayer vegetable cultivation facilities and collecting maximum and sustainable sunlight without too much loss by tracing solar path and properly distributing it through careful control during daytime are crucial for realizing the investigated rooftop light shelf system for multi-layered vegetable cultivation. In this study, we developed an innovative way of effectively allocating sunlight inside even to otherwise shaded zone of a multi-layer vegetable cultivation facility. To prove the effectiveness of the system's sunlight collection and distribution capability, both simulation and experiment in Daejeon are performed and the outcome is analyzed.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2018.10a
• /
• pp.626-628
• /
• 2018

In this paper, we compare the performances of SVM (Support Vector Machine) and ANN (Artificial Neural Network) machine learning models for predicting solar energy by using meteorological data. Two machine learning models were built by using fifteen kinds of weather data such as long and short wave radiation average, precipitation and temperature. Then the RBF (Radial Basis Function) parameters in the SVM model and the number of hidden layers/nodes and the regularization parameter in the ANN model were found by experimental studies. MAPE (Mean Absolute Percentage Error) and MAE (Mean Absolute Error) were considered as metrics for evaluating the performances of the SVM and ANN models. Sjoem Simulation results showed that the SVM model achieved the performances of MAPE=21.11 and MAE=2281417.65, and the ANN model did the performances of MAPE=19.54 and MAE=2155345.10776.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.1
• /
• pp.63-68
• /
• 2018

This paper presents an integrated photochemical reaction system (i.e., an artificial leaf) that uses earth-abundant catalysts for artificial photosynthesis with a carbon dioxide ($CO_2$) fixation process. The performance of the system was investigated in terms of the energy capture and conversion capabilities. A wireless configuration was achieved by directly doping cobalt oxide as an oxygen-evolving catalyst for water splitting reaction on the illuminated surface of photovoltaic (PV) cell, as well as molybdenum disulfide ($MoS_2$) as an efficient catalyst for $CO_2$ reduction on the back substrate surfaces of the PV cell. The system produces hydrogen and carbon monoxide (CO) as sustainable fuels (i.e., synthesis gas) at around 4.5% efficiency, which implies more than 75% catalytic efficiency at the cathode. The process of solar-driven $CO_2$ conversion and water-splitting reaction is contained in one system, which is one step closer to the successful realization of artificial photosynthesis.

• Journal of the Korean Solar Energy Society
• /
• v.29 no.5
• /
• pp.88-97
• /
• 2009

In these days, it attracts our attention to create a green outdoor environment around the building block in urban area. Green space and permeable ground covering are increased by laws and regulations. According to these trends, variety researches for improving outdoor environment are accomplished at this moment. However, the problems for outdoor environment such as heat island effect and air contaminant in urban area are still reported. The purpose of this study is to examine the variables to affect the formation of outdoor thermal environment by quantitative analysis. As a initial study, in this paper, the effect of ground composition on changes of surface temperature and heat flux in multi-residential building were analyzed by field measurement and numerical simulation. Through field measurement, the surface temperature and heat flux of artificial ground in multi-residential building in Suwon city were measured. The result showed that the surface temperature was decreased by about $20^{\circ}C$ with afforestation of artificial ground compared with those of concrete covering. Moreover, the inner temperature of artificial ground was changed as same behaviors of outdoor temperature changes to depths of 20cm. In simulation, the effect of soil types and depth of artificial ground on the changes of the surface temperature and heat flux were analyzed. As results, the natural soil ground was more effective against lowering the surface temperature than any other cases in the analyzed cases.

• Journal of Environmental Science International
• /
• v.28 no.5
• /
• pp.521-526
• /
• 2019

In this study, a solar light collector that collects and transmits solar light required for crop production in a closed plant production system was developed. The solar light collector consisted of a Fresnel lens for collecting solar light, and a tracking actuator for tracking solar light from sunrise to sunset to increase the light collection efficiency. The optical fiber that transmitted solar light was made of Glass Optical Fiber (GOF), and it had an excellent optical transmission rate. After collecting the solar light, the amount of light was measured at 5, 10, 15, 20, 25, and 30 cm distances from the GOF through the darkroom by using a light sensor logger connected to a quantum and pyranometer sensor. Compared with solar light, the light intensity of pyranometer sensor measured at 5 cm was 114% higher than solar light, and 61% at 10 cm. In addition, it was observed that it is possible to transmit the necessary amount of light for growing crops up to about 15 cm (as over 22%) through GOF. Therefore, adding diffusers to the solar light collector should be expected to replace artificial light in plant factories or plug seedlings nurseries for leafy vegetables. More studies on the solar light collection devices and the light transmission devices that have high light collection efficiency should be conducted.

• The Bulletin of The Korean Astronomical Society
• /
• v.42 no.2
• /
• pp.68-68
• /
• 2017

Measurements of solar wind speed near the Sun (< 0.1 AU) are important for understanding acceleration mechanism of solar wind as well as space weather predictions, but hard to directly measure them. For the first time, we provide 2D solar wind speed maps in the LASCO field of view using three consecutive days data. By applying the Fourier convolution and inverse Fourier transform, we decompose the 3D intensity data (r, PA, t) into the 4D one (r, PA, t, v). Then, we take the weighted mean along speed to determine the solar wind speeds that gives V(r, PA, t) in every 30 min. The estimated radial speeds are consistent with those given by an artificial flow and plasma blobs. We find that the estimated speeds are moderately correlated with those from slow CMEs and those from IPS observations. A comparison of yearly solar wind speed maps in 2000 and 2009 shows that they have very remarkable differences: azimuthally uniform distribution in 2000 and bi-modal distribution (high speed near the poles and low speed near the equator) in 2009.

• KIEAE Journal
• /
• v.14 no.3
• /
• pp.65-70
• /
• 2014

The thermal environment in a small city rapidly deteriorates due to the urbanization and overpopulation. It is important to understand and predict the thermal environment in a city area. The thermal environment is highly affected by the solar radiation and temperature distributions changing over time periodically. To predict the thermal environment precisely, the solar radiation calculation including radiation strength, incidence angle, and thermal radiation between building surface and ground should be considered. In this study, the computational domain includes various artificial structures such as building, ground, asphalt, brick and grass. To consider the solar radiation, the unsteady state numerical calculation is performed from sun rise to mid-day (2:00pm). The numerical methods consist of solar load and one dimensional heat conduction through the boundaries to reduce the computational load and improve the flexibility of the calculation.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2019.10a
• /
• pp.1023-1025
• /
• 2019

Coal and Natural gas are two biggest contributors to a generation of energy throughout the world. Most of these resources create environmental pollution while making energy affecting the natural habitat. Many approaches have been proposed as alternatives to these sources. One of the leading alternatives is Solar Energy which is usually harnessed using solar farms. In artificial intelligence, the most researched area in recent times is machine learning. With machine learning, many tasks which were previously thought to be only humanly doable are done by machine. Neural networks have two major subtypes i.e. Convolutional neural networks (CNN) which are used primarily for classification and Recurrent neural networks which are utilized for time-series predictions. In this paper, we predict energy generated by solar fields and optimal angles for solar panels in these farms for the upcoming seven days using environmental and historical data. We experiment with multiple configurations of RNN using Vanilla and LSTM (Long Short-Term Memory) RNN. We are able to achieve RSME of 0.20739 using LSTMs.

• The Bulletin of The Korean Astronomical Society
• /
• v.44 no.1
• /
• pp.54.1-54.1
• /
• 2019

Solar observations often show that interaction of more than one flux rope is involved in solar eruptions. In this regard, Lau and Finn (1996) intensively studied the interaction of two flux ropes, which reside in between two parallel planes each mimicking one polarity region of the solar photosphere. However, this geometry is quite far from the real solar situation, in which all feet of flux tubes are rooted in one surface only. In this paper, we study the interaction of two flux ropes in a semi-infinite region above a plane representing the solar photosphere. Four cases of the flux rope interaction are investigated in our MHD simulation study: (1) parallel axial fields and parallel axial currents (co-helicity), (2) antiparallel axial fields and parallel axial currents (counter-helicity), (3) parallel axial fields and antiparallel axial currents (counter-helicity), and (4) antiparallel axial fields and antiparallel axial currents (co-helicity). Each case consists of four or six subcases according to the background field direction relative to the flux ropes and the relative positions of the flux rope footpoints. In our simulations, all the cases eventually show eruptive behaviors, but their degree of explosiveness and field topological evolutions are quite different. We construct artificial emission measure maps based on the simulations and compare them with images of CME observations, which provides us with information on what field configurations may generate certain eruption features.

• Journal of Bio-Environment Control
• /
• v.29 no.2
• /
• pp.105-109
• /
• 2020

This study was conducted to the improvement of solar light-based artificial light supply system and effect of lettuce cultivation. The artificial light supply system was consisted of units such as light source, power, system measurement and controller. The light source supply was composed of a solar transmitter and an LED lamp. The power supply consisted of an leakage breaker, SMPS, LED controller and relay. The solar transmitter was made of a quartz optical fiber with optimal light transmission. Artificial light used white lamp among LEDs. System measurement and control consisted of touch screen, Zigbee communication module and light quantity sensor. The results of test confirmed that the LED light is automatically activated when the intensity measured by the light intensity sensor is 200 μmolm^-2s^-1 or less. Moreover, the leaf length, root length, chlorophyll content and root fresh weight of optical fiber treatment was hight than LED lamp treatment. Therefore, it can be inferred that the energy-saving solar light collector device can be effective in the indoor lettuce production. However, the use of LED lamp is also recommended to assure the availability of sufficient sunlight in cloudy and rainy days.