• Journal of IKEEE
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• v.24 no.4
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• pp.1028-1033
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• 2020

The existing in-band interference reduction method recommends the physical separation distance between wireless devices and interference signals, and the interference can be suppressed through the separation distance. If the in-band interference signals can be reduced in a wireless device, a margin can be given to the physical separation distance. Since there is an effect of extending the receiver dynamic range of receivers, it is highly useful for interference reduction and improvement method. In this paper, the structure of an in-band analog IRM(Interference Reduction Module) is proposed and the design and implementation of the proposed analog IRM are described. To design an analog IRM, the interference reduction performance according to the delay mismatch, phase error and the number of delay lines that affect the performance of the analog IRM was simulated. The proposed analog IRM composed of 16 delay lines was implemented and the implemented IRM has the interference reduction performance of about 10dB for a 5G(NR-FR1-TM-1.1) signal having a 40MHz bandwidth at a center frequency of 3.32GHz. The analog IRM proposed in this paper can be used as an in-band interference canceller.

• Journal of The Korean Society of Agricultural Engineers
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• v.63 no.2
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• pp.75-84
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• 2021

As the weather changes become frequent, weather disasters are increasing, causing more damage to plastic greenhouses. Among the damage caused by various disasters, damage by snow to the greenhouse takes a relatively long time, so if an alarm system is properly prepared, the damage can be reduced. Existing greenhouse design standards and snow warning systems are based on snow depth. However, even in the same depth, the load on the greenhouse varies depending on meteorological characteristics and snow density. Therefore, this study aims to secure the structural safety of greenhouses by developing sensors that can directly measure snow loads, and analysing the warning criteria for load using a stochastic model. Markov chain was applied to estimate the failure probability of various types of greenhouses in various regions, which let users actively cope with heavy snowfall by selecting an appropriate time to respond. Although it was hard to predict the precise snow depth or amounts, it could successfully assess the risk of structures by directly detecting the snow load using the developed sensor.

• Journal of The Korean Society of Agricultural Engineers
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• v.64 no.1
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• pp.15-26
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• 2022

3D open-field farm model developed from UAV (Unmanned Aerial Vehicle) data could make crop monitoring easier, also could be an important dataset for various fields like remote sensing or precision agriculture. It is essential to separate crops from the non-crop area because labeling in a manual way is extremely laborious and not appropriate for continuous monitoring. We, therefore, made a 3D open-field farm model based on UAV images and developed a crop segmentation model using a supervised machine learning algorithm. We compared performances from various models using different data features like color or geographic coordinates, and two supervised learning algorithms which are SVM (Support Vector Machine) and KNN (K-Nearest Neighbors). The best approach was trained with 2-dimensional data, ExGR (Excess of Green minus Excess of Red) and z coordinate value, using KNN algorithm, whose accuracy, precision, recall, F1 score was 97.85, 96.51, 88.54, 92.35% respectively. Also, we compared our model performance with similar previous work. Our approach showed slightly better accuracy, and it detected the actual crop better than the previous approach, while it also classified actual non-crop points (e.g. weeds) as crops.

• Explosives and Blasting
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• v.40 no.2
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• pp.1-14
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• 2022

Numerical simulation is the most widely used methods for evaluating blasting performance. This study, conducted the numerical analysis of shock chamber model to evaluate the pressure confine effect of the stemming material and plug device. The stemming effect was compared and evaluated with that of the STF-based stemming material currently under development and sand, which is a commonly used blast stemming material. Furthermore, to verify of enhancement the confine effect inside blast hole pressure, three types of stemming plugs were adopted for the numerical analysis. The numerical simulation results revealed that the STF-based stemming materials were superior to the general stemming material. Also, It is evaluated that the STF-based stemming and Plug system can not only prevent detonation gas from overflowing the borehole prematurely, but also prolong the action time and scope of detonation gas in the borehole effective.

• Journal of The Korean Society of Agricultural Engineers
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• v.64 no.5
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• pp.67-77
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• 2022

Recently, the trend in structural analysis and design is moving towards the development of reliable system. The reliability-based method defines various limit states related to usability and failure, thereby enabling multiple levels of design according to the importance of a structure. Meanwhile, an actual structure is composed of a set of several elements, and particularly, a frame type is composed of a system in which the members are connected each other. At this time, the actual connection between members is in a semi-rigid condition, not in complete rigid or hinged. This semi-rigid is found in several structures, especially in agricultural facilities designed with lightweight materials. In this study, a system reliability analysis technique for frame structure was established, and applied to an analysis of the semi-rigid connection. Various conditions of correlation were applied to reflect the connectivity between members, and through this, the limitations of existing structural analysis method and the behavioral characteristics of structure were analyzed. The failure probability of the frame member component and the overall structure system was significantly different in consideration of the semi-rigid connection. In addition, it was evaluated that the behavior of structure can be more accurately analyzed if the correlation according to the position of members in a system is further investigated.

• Electronics and Telecommunications Trends
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• v.36 no.2
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• pp.43-55
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• 2021

National and social issues are becoming increasingly common, but traditional policy-making methods are no longer effective. Therefore, evidence-based policy making is emerging as an alternative paradigm. Digital twin technology is one of the digital support tools for the new data-driven policy-making process. This study presents ongoing government experiments in the world where digital twin technology is applied to policy making and describes our experience in developing digital twin platforms in Sejong-the de facto administrative capital of South Korea.

• Journal of The Korean Society of Agricultural Engineers
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• v.64 no.6
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• pp.35-41
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• 2022

Heavy snow damage can be prevented in advance with an appropriate security system. To develop the security system, we developed a model that predicts snow depth after a few hours when the snow depth is observed, and utilized it to calculate a failure probability with various types of greenhouses and observed snow depth data. We compared the Markov chain model and Bayesian long short-term memory models with varying input data. Markov chain model showed the worst performance, and the models that used only past snow depth data outperformed the models that used other weather data with snow depth (temperature, humidity, wind speed). Also, the models that utilized 1-hour past data outperformed the models that utilized 3-hour data and 6-hour data. Finally, the Bayesian LSTM model that uses 1-hour snow depth data was selected to predict snow depth. We compared the selected model and the shifting method, which uses present data as future data without prediction, and the model outperformed the shifting method when predicting data after 11-24 hours.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.28 no.3
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• pp.69-77
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• 2022

Background: Ankle sprains, and the resulting ankle instability worsen to chronic due to recurrent ankle injuries or sprains, 78% of which are accompanied by posture instability and damage due to changes in the position of the talus of the ankle. The purpose of this study is to investigate the immediate effect of applying MWM taping on the patient's muscle strength and balance ability in patients with chronic ankle instability. Methods: 15 people with MWM taping and 15 people with Kinesio taping were applied, and after applying the taping of the ankle, 10 minutes of walking treadmill and 10 times of forward lunge operation, the change in ankle muscle strength and balance ability was confirmed. The strength test of the ankle was performed using a test device called Biodex system 4 (USA) for the movement of the dorsi-flexion and plantar flexion of the foot, and the balance of the two groups was measured using Biodex balance system (USA) to test balance ability. Results: The comparison of muscle strength changes in the ankle does not show a significant increase in the group applying MWM compared to the group applying kinesio taping (p<.05). In the comparison of equilibrium capabilities, the MWM taping group also showed a significant increase in the MWM taping group compared to the kinesio taping group (p<.05). Conclusion: When applying MWM taping and kinesio taping to patients with chronic ankle instability, there was no significant difference in comparison of muscle strength changes, but there was a significant difference in comparison of balance ability.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.28 no.3
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• pp.51-59
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• 2022

Background: This study aimed to investigate the effect of mobilization with movement (MWM) applied to the ankle joint, on the craniovertebral angle (CVA), pressure pain threshold, and neck disability index (NDI) in asymptomatic adults with a forward head posture (FHP). Methods: A total of 32 subjects with FHP were assigned to either the MWM group (N=16) or the cranio-cervical flexion exercise (CCFE) group (n=16). The CVA, pressure pain threshold and NDI were measured before and 4 weeks after the intervention. Results: A significant improvement in the CVA was observed in the MWM group (p<.05), whereas no significant changes (p>.05) were observed in the CCFE group. Both groups showed significant differences in the pressure pain threshold and NDI before and after the intervention (p<.05). Conclusion: The results of the study suggest that MWM applied to the ankle joint can effectively improve the CVA, pressure pain threshold, and NDI of adults with a forward head posture. Based on this study, the ankle MWM technique for dorsiflexion can be used as an objective research method for additional studies targeting FHP patients in the future.

• Journal of The Korean Society of Agricultural Engineers
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• v.64 no.4
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• pp.21-30
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• 2022

Renewable energy systems aim to achieve carbon neutrality and replace fossil fuels. Photovoltaic technologies are the most widely used renewable energy. However, they require a large operating area, thereby decreasing available farmland. Accordingly, agrivoltaic systems (AVSs)-innovative smart farm technologies that utilize solar energy for crop growth and electricity production-are attracting attention. Although several empirical studies on these systems have been conducted, comprehensive research on their design is lacking, and no standard model suitable for South Korea has been developed. Therefore, this study created an integral design of AVS reflecting domestic crop cultivation conditions and conducted a structural analysis for safety assessment. The shading ratio, planting distance, and agricultural machinery work of the system were determined. In addition, national construction standards were applied to evaluate their structural safety using a finite element analysis. Through this, the safety of this system was ensured, and structural considerations were put forward. It is expected that the AVS model will allow for a stable utilization of renewable energy and smart farm technologies in rural areas.