• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.5
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• pp.646-654
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• 2020

This paper is to develop an electromagnetic wave-based sensor that can measure the spatial distribution of precipitation, and to a electromagnetic wave rain gauge (hereinafter, "EWRG") capable of simultaneously measuring rainfall, snowfall, and wind field, which are the core of heavy rain observation. Through this study, the LFM transmission and reception signals were theoretically analyzed. In addition, In order to develop a radar transceiver, LFM transceiver design and simulation were conducted. In this paper, we developed a K-BAND pulse-driven 6W SSPA(Solid State Power Amplifiers) transceiver using a small HMIC(Hybrid Microwave Integrated Circuit). It has more than 6W of output power and less than 5dB of receiving NF(Noise Figure) with short duty of 1% in high temperature environment of 65 degrees. The manufactured module emits LFM and Square Pulse waveform with the built-in waveform generator, and the receiver has more than 40dB of gain. The transceiver developed in this paper can be applied to the other small weather radar.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.6
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• pp.561-568
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• 2020

Wave measurements using X-band radar have many advantages compared to other wave gauges including wave-rider buoy, P-u-v gauge and Acoustic Doppler Current Profiler (ADCP), etc.. For example, radar system has no risk of loss/damage in bad weather conditions, low maintenance cost, and provides spatial distribution of waves from deep to shallow water. This paper presents new methods for estimating significant wave heights of X-band marine radar images using Artificial Neural Network (ANN). We compared the time series of estimated significant wave heights (Hs) using various estimation methods, such as signal-to-noise ratio (${\sqrt{SNR}}$), both and ${\sqrt{SNR}}$ the peak period (TP), and ANN with 3 parameters (${\sqrt{SNR}}$, TP, and Rval > k). The estimated significant wave heights of the X-band images were compared with wave measurement using ADCP(AWC: Acoustic Wave and Current Profiler) at Hujeong Beach, Uljin, Korea. Estimation of Hs using ANN with 3 parameters (${\sqrt{SNR}}$, TP, and Rval > k) yields best result.

• Journal of Bio-Environment Control
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• v.31 no.4
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• pp.438-443
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• 2022

In this study, the lateral loading test was performed to analyze structural performance of multi-span plastic greenhouse through full-scale experiment and numerical analysis. In order to analyze the lateral stiffness and stress, we installed 9 displacement sensors and 19 strain gauge sensors on the specimen, respectively, and load of l mm per minute was applied until the specimen failure. In the comparison between the full-scale experiment and the structural analysis results of a multi-span greenhouse with venlo-type roof according to bracing installation, there was a large difference in the lateral stiffness of the structure. By installing a brace system, the lateral stiffness measured near the side elevation of the specimen increased by up 44%. As the bracing joint used in the field did not secure sufficient rigidity, the external force could not be transmitted to the entire structure properly. Therefore, it is necessary to establish a bracing construction method and design standards in order for a greenhouse to which bracing applied to have sufficient performance.

• Korean Journal of Remote Sensing
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• v.37 no.2
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• pp.211-220
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• 2021

Land Surface Temperature (LST) is one of the useful parameters to diagnose the growth and development of crop and to detect crop stress. Unmanned Aerial Vehicle (UAV)-based LST (LSTUAV) can be estimated in the regional spatial scale due to miniaturization of thermal infrared camera and development of UAV. Given that meteorological variable, type of instrument, and surface condition can affect the LSTUAV, the evaluation for accuracy of LSTUAV is required. The purpose of this study is to evaluate the accuracy of LSTUAV using LST measured at ground (LSTGround) under various meteorological conditions and growth phases of garlic crop. To evaluate the accuracy of LSTUAV, Relative humidity (RH), absolute humidity (AH), gust, and vegetation index were considered. Root mean square error (RMSE) after minimizing the bias between LSTUAV and LSTGround was 2.565℃ under above 60% of RH, and it was higher than that of 1.82℃ under the below 60% of RH. Therefore, LSTUAV measurement should be conducted under the below 60% of RH. The error depending on the gust and surface conditions was not statistically significant (p-value < 0.05). LSTUAV had reliable accuracy under the wind speed conditions that allow flight and reflected the crop condition. These results help to comprehend the accuracy of LSTUAV and to utilize it in the agriculture field.

• Journal of People, Plants, and Environment
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• v.23 no.2
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• pp.211-220
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• 2020

The purpose of this study was to analyze the frequency and contents of horticultural activities in 696 individual activities listed in 11 teacher's guidebooks of Nuri Curriculum for 5-year-olds, and to find out the perceptions of horticultural activities in the formal curriculum. The target horticultural activities that were selected were those using natural objects like potted plants, water, wind, soil, stones, etc. as the topic or subject of activities, and those with different topics but are mentioning plants or natural objects as an example at least twice. The 150 selected horticultural activities were classified by life-based theme, activity type, activity domain, and medium. As a result of examining horticultural activities by life-based theme, there were 150 horticultural activities (21.55%): 40 in Spring, Summer, Autumn and Winter (5.75%), 34 in Animals, Plants, and Nature (4.89%), 22 in Environment and Life (3.16%), 19 in Our Country (2.73%), and nine in Our Neighborhood (1.29%), nine in Various Countries of the World (1.29%), four in Health and Safety (0.57%), four in Living tools (0.57%), four in Transportation (0.57%), three in Kindergarten and Friends (0.43%), two in Me and My Family (0.29%; χ²=130.427, p < .001). As a result of examining horticultural activities by activity type, there were 61 free choice activities (40.67%), 80 large and small group activities (53.33%), and nine outdoor play activities (6.00%), indicating that outdoor play was the fewest activity type (χ²=54.040, p < .001). The results of analyzing horticultural activities by activity domain showed that there were 25 in conversation (16.67%), 19 in science (12.50%), 14 in art (9.33%), 14 in cooking (9.33%), 10 in fairy tales (6.00%), nine in music (6.00%), eight in language (5.33%), eight in number operation (5.33%), eight in others (5.33%), six in children's plays (4.0%), six in games (4.0%), four in body and movement (2.67%), three in stacking (2.00%), three in roles (2.00%), three in rhythm (2.00%), two in children's poems (1.33%), two in field experience (1.33%) and one in outside play (0.67%; χ²=87.600, p < .001). As a result of examining the mediums used in the horticultural activities, 46 activities (30.67%) directly used plants as the mediums, 11 activities (7.33%) used soil such as stones, gravel, and earth as the mediums instead of plants, four activities (2.67%) used dry plants such as branches and dry leaves as the mediums, and 89 activities (59.33%) used videos, photos of plants, and pictures of plants as the mediums (χ²=121.307, p < .001).

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.34 no.4
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• pp.109-118
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• 2022

The data of the missing section among the vertex surface sea temperature observation data was imputed using the Bidirectional Recurrent Neural Network(BiRNN). Among artificial intelligence techniques, Recurrent Neural Networks (RNNs), which are commonly used for time series data, only estimate in the direction of time flow or in the reverse direction to the missing estimation position, so the estimation performance is poor in the long-term missing section. On the other hand, in this study, estimation performance can be improved even for long-term missing data by estimating in both directions before and after the missing section. Also, by using all available data around the observation point (sea surface temperature, temperature, wind field, atmospheric pressure, humidity), the imputation performance was further improved by estimating the imputation data from these correlations together. For performance verification, a statistical model, Multivariate Imputation by Chained Equations (MICE), a machine learning-based Random Forest model, and an RNN model using Long Short-Term Memory (LSTM) were compared. For imputation of long-term missing for 7 days, the average accuracy of the BiRNN/statistical models is 70.8%/61.2%, respectively, and the average error is 0.28 degrees/0.44 degrees, respectively, so the BiRNN model performs better than other models. By applying a temporal decay factor representing the missing pattern, it is judged that the BiRNN technique has better imputation performance than the existing method as the missing section becomes longer.

• Journal of Space Technology and Applications
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• v.2 no.2
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• pp.104-120
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• 2022

The Small Scale magNetospheric and Ionospheric Plasma Experiment (SNIPE)'s scientific goal is to observe spatial and temporal variations of the micro-scale plasma structures on the topside ionosphere. The four 6U CubeSats (~10 kg) will be launched into a polar orbit at ~500 km. The distances of each satellite will be controlled from 10 km to more than ~1,000 km by the formation flying algorithm. The SNIPE mission is equipped with identical scientific instruments, Solid-State Telescopes(SST), Magnetometers(Mag), and Langmuir Probes(LP). All the payloads have a high temporal resolution (sampling rates of about 10 Hz). Iridium communication modules provide an opportunity to upload emergency commands to change operational modes when geomagnetic storms occur. SNIPE's observations of the dimensions, occurrence rates, amplitudes, and spatiotemporal evolution of polar cap patches, field-aligned currents (FAC), radiation belt microbursts, and equatorial and mid-latitude plasma blobs and bubbles will determine their significance to the solar wind-magnetosphere-ionosphere interaction and quantify their impact on space weather. The formation flying CubeSat constellation, the SNIPE mission, will be launched by Soyuz-2 at Baikonur Cosmodrome in 2023.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.67 no.4
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• pp.274-284
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• 2022

To use kenaf (Hibiscus cannabinus L.) as a fiber and livestock feed, a high-yielding variety needs to be identified. For this, accurate phenotyping of plant height is required for this breeding purpose due to the strong relationship between plant height and yield. Plant height can be estimated using RGB images from unmanned aerial vehicles (UAV-RGB) and photogrammetry based on Structure from Motion (SfM) algorithms. In kenaf, accurate measurement of height is limited because kenaf stems have high flexibility and its height is easily affected by wind, growing up to 3 ~ 4 m. Therefore, we aimed to identify a method suitable for the accurate estimation of plant height of kenaf and investigate the feasibility of using the UAV-RGB-derived plant height map. Height estimation derived from UAV-RGB was improved using multi-point calibration against the five different wooden structures with known heights (30, 60, 90, 120, and 150 cm). Using the proposed method, we analyzed the variation in temporal height of 23 kenaf cultivars. Our results demontrated that the actual and estimated heights were reliably comparable with the coefficient of determination (R²) of 0.80 and a slope of 0.94. This method enabled the effective identification of cultivars with significantly different heights at each growth stages.

• Journal of Practical Agriculture & Fisheries Research
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• v.13 no.1
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• pp.19-26
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• 2011

The machine transplanted rice has highly extended in the Republic of Korea due to a wage rise since 1976 and thus rice seedling raising nursery method has shifted from field into polyethylene film house. The rice seedling grown under a polyethylene film house was weak and tall because of limited sunlight and wind and so there was so complained among rice growing farmers in terms of missing hill and broken seedling after machine transplanting. In recent iron-coated seedling has reported on healthier and stronger than that of polyethylene film house. These seedlings were more stiff and thus more easy to handle during transplanting and less missing hills. The Iron-coated seed was proven to more stiff like seedling height, root growth and weight of shoot and root growth. This was more convenient during transfer of seedling raising box im machine transplanting. Thus, this study was carried out to grow a stiff and healthy seedling growth and development for machine transplanting. There were a normal seed germination and sprouting after iron-coated seeds treatment and this seedling was smaller and stiffer than that of untreated control. The leaf number and root growth of seedling which was iron-coated seeds would be better and total seedling fresh weight was greater than that of untreated control.

• Journal of Ginseng Culture
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• v.6
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• pp.105-115
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• 2024

Wild ginseng, grown in undisturbed forest environments, has been maintained for centuriesthrough human intervention and knowledge, leading to the development of current ginseng agriculture. The practice of ginseng farming has long been established in various regions of Korea. However, the ginseng farming specifically in Geumsan was recognized as a Globally Important Agricultural Heritage System (GIAHS) by the Food and Agriculture Organization of the United Nations (FAO) in 2018. This designation was granted after a thorough evaluation, which confirmed that Geumsan's ginseng farming met the necessary criteria, including historical importance, traditional knowledge system, agrobiodiversity, and agricultural landscape. Traditional ginseng farming in Geumsan practices the 'rotating agriculture system', a sustainable land use approach that has been developed over several cycles of long duration (10-15 years). It contains the knowledge to choose locations for cultivation that prioritize the direction of sunlight and wind circulation. Furthermore, it received significant recognition for its agricultural heritage value based on its maintenance of several traditional knowledge systems, including ancestral wisdom and knowledge regarding pre-planting field management techniques. As of December 2023, there are currently 86 locations in 26 nations that have been designated as GIAHS. Among these sites, Geumsan stands out as the first and only site in the world specifically recognized for the cultivation of ginseng crops. This historical record serves as a significant reminder of Korea's prominent position as a major producer of ginseng on a global level. This article first provides an overview of the concept of agricultural heritage, the designation criteria, and the status of the designation. It then identifies, among the GIAHS designation criteria, the agricultural heritage value of traditional ginseng farming in the Geumsan region from the perspective of local traditional knowledge systems.