• Environmental and Resource Economics Review
• /
• v.30 no.2
• /
• pp.237-268
• /
• 2021

As variable renewable sources rapidly increase due to the Energy Transition plan, integration cost of renewable sources to the power system is rising sharply. The increase in variable renewable energy reduces the capacity factor of existing traditional power capacity, and this undermines the efficiency of the overall power supply, and demand resources are drawing attention as a solution. In this study, we analyzed how much electric vehicle demand resouces, which has great potential among other demand resources, can reduce power supply costs if it is used as a flexible resource for renewable generation. As a methodology, a stochastic form of power system optimization model that can effectively reflect the volatile characteristics of renewable generation is used to analyze the cost induced by renewable energy and the benefits offered by electric vehicle demand resources. The result shows that virtual power plant-based direct control method has higher benefits than the time-of-use tariff, and the higher the proportion of renewable energy is in the power system, the higher the benefits of electric vehicle demand resources are. The net benefit after considering commission fee for aggregators and battery wear-and-tear costs was estimated as 67% to 85% of monthly average fuel cost under virtual power plant with V2G capability, and this shows that a sufficient incentive for market participation can be offered when a rate system is applied in which these net benefits of demand resources are effectively distributed to consumers.

• Journal of Sensor Science and Technology
• /
• v.30 no.3
• /
• pp.154-164
• /
• 2021

In this study, the IoT sensor technology required for improving the survival rate and high-density productivity of individual shrimp in smart shrimp farming (which involves the usage of recirculating aquaculture systems and biofloc technology) was analyzed. The principles and performances of domestic and overseas water quality monitoring IoT sensors were compared. Furthermore, the drawbacks of existing aquaculture monitoring technologies and the countermeasures for future aquaculture monitoring technologies were examined. In particular, for farming white-legged shrimp, an IoT sensor was employed to collect measurement indicators for managing the water quality environment in real-time, and the IoT sensor-based real-time monitoring technology was then analyzed for implementing the optimal farming environment. The results obtained from this study can potentially contribute to the realization of an autonomous farming platform that can improve the survival rate and productivity of shrimp, achieve feed reduction, improve the water quality environment, and save energy.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.25 no.3
• /
• pp.77-84
• /
• 2021

In this study, flexural tests of prestressed high strength spun concrete (PHC) piles reinforced with infilled concrete and longitudinal rebars were conducted, where the longitudinal rebar ratio and the presence of sludge formed on the inner surface of PHC pile were set as key test variables. A total of six PHC pile specimens were manufactured, and their flexural behaviors including failure mode, crack pattern, longitudinal strain distribution in a section and end slip between external PHC pile and infilled concrete were measured and discussed in detail. The test results revealed that the flexural stiffness and strength increased as the longitudinal rebar ratio became larger, and that the sludge formed on the inner surface of PHC pile did not show any detrimental effect on the flexural performance. In addition to the experimental approach, this study presents a nonlinear flexural analysis model considering compatibility conditions and strain and stress distributions of the PHC piles and infilled concrete. The rationality of the nonlinear flexural analysis model was verified by comparing it with test results, and it appeared that the proposed model well evaluated the flexural behavior of PHC piles reinforced with infilled concrete and longitudinal rebars with a good accuracy.

• The Journal of Bigdata
• /
• v.5 no.2
• /
• pp.187-199
• /
• 2020

The World Health Organization declared COVID-19 a pandemic on March 11. South Korea recorded 27,000 cases of the coronavirus illness, and more than 50 million coronavirus cases were confirmed all over the world. An epidemiological investigation becomes important once again due to the spread of COVID-19 infections. However, there were a number of confirmed coronavirus cases from Deagu and Gyeongbuk. Limitations of the epidemiological investigation methods were recognized. The Korea Disease Control and Prevention Agency developed the Epidemiological Investigation Support System(EISS) to utilize the smart city data hub technology and utilized the system in the epidemiological investigation. As a part of EISS, The proposed system is big-data bsed epidemiological investigation support system processing mobile network data. The established system is the epidemiological investigation support system based on big data to process mobile carriers' big data. Processing abnormal values of mobile carriers' data which was impossible with existing staff or creating hotspot regions where more than two people were in contact with an infected person were realized. As a result, our system processes outlier of mobile network data in 30 seconds, while processes hotspot around in 10 minutes. as a first time to adapt and support bigdata system into epidemiological investigation, our system proposes the practical utilizability of big-data system into epidemiological investigation.

• Journal of the Korean Applied Science and Technology
• /
• v.38 no.3
• /
• pp.870-882
• /
• 2021

Coptis chinensis has been used in the treatment of various diseases such as soothing, anti-inflammation, antimicrobial and antipyretic in oriental traditional medicine. In this study, we investigated the effect of hot water extract of Coptis chinensis(CCW) on skin barrier and inflammation-related factors in UVB and TNF-α/IFN-γ-induced HaCaT cells and evaluated its potential as a moisturizing and anti-inflammatory material. Based on result, the amount of HA (Hyaluronic acid) production and protein and mRNA expression of filaggrin were measured. In TNF-α/IFN-γ-induced HaCaT cells, CCW increased the amount of HA production in a concentration-dependent manner. In the measurement of protein and mRNA expression of filaggrin, the expression rate increased as the concentration of CCW increased. In UVB-induced HaCaT cells, CCW decreased the production of ROS and showed significant results with EGCG ((-)-epigallocatechin-3-gallate), a positive control. In addition, CCW inhibited the expression of inflammatory cytokines TNF-α, IL-1β, IL-6, and IL-8 in TNF-α/IFN-γ-induced HaCaT cells. It was confirmed that the protein and mRNA expression of COX-2, a major factor in skin inflammation, was decreased in a concentration-dependent manner. These results suggest that hot water extract from Coptis chinensis can be used as a cosmetic material having a moisturizing and anti-inflammatory effect.

• Journal of Drive and Control
• /
• v.17 no.4
• /
• pp.133-140
• /
• 2020

Traction performance of a tractor varies depending on soil conditions. Sinkage and slip of the driving wheel for tractor frequently occur in a reclaimed land. The objective of this study was to develop a tractor suitable for a reclaimed land. Traction performance was evaluated according to soil conditions of reclaimed land and paddy field. Field experiments were conducted at two test sites (Fields A: paddy field; and Field B: reclaimed land). The tractor load measurement system was composed of an axle rotation speed sensor, a torque meter, a six-component load cell, GPS, and a DAQ (Data Acquisition System). Soil properties including soil texture, water content, cone index, and electrical conductivity (EC) were measured. Referring to previous researches, the tractor traveling speed was set to B3 (7.05 km/h), which was frequently used in ridge plow tillage. Soil moisture contents were 33.2% and 48.6% in fields A and B, respectively. Cone index was 2.1 times higher in field A than in field B. When working in the reclaimed land, slip ratios were about 10.5% and 33.1% for fields A and B, respectively. The engine load was used almost 100% of all tractors under the two field conditions. Traction powers were 31.9 kW and 24.2 kW for fields A and B, respectively. Tractive efficiencies were 83.3% and 54.4% for fields A and B, respectively. As soil moisture increased by 16.4%, the tractive efficiency was lowered by about 28.9%. Traction performance of tractor was significantly different according to soil conditions of fields A and B. Therefore, it is necessary to improve the traction performance of tractor for smooth operations in all soil conditions including a reclaimed land by reflecting data of this study.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.22 no.1
• /
• pp.131-137
• /
• 2021

This study estimated acreage response functions for greenhouse paprika, greenhouse strawberry, open-land garlic, and open-land spinach by using Gyeongsangnamdo agricultural income data. The results show that the cultivation area for greenhouse paprika increased because the agricultural management costs decreased, and the risk of price volatility was relatively low. On the other hand, the cultivation area for greenhouse strawberries decreased due to increasing agricultural management costs and the greater risk of price volatility. In the case of open-land garlic and spinach, the cultivation area remained stagnant due to the greater risk of price volatility, despite increasing agricultural revenue. We derived several policy implications from our results. The risk of price volatility in agricultural products is greater for crops grown on land rather than crops grown in greenhouses. Therefore, the local government needs to adopt the "agricultural revenue guarantee insurance" in preference to crops grown on land rather than crops grown in greenhouses. On the other hand, in the case of greenhouse crops, agricultural management costs are very high. Thus, local government should focus on replacing old facilities and supplying smart-farm facilities that reduce agricultural management costs such as heating costs.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.22 no.2
• /
• pp.127-133
• /
• 2021

A recent study of people physically falling focused on analyzing the motions of the falls using a recurrent neural network (RNN) and a deep learning approach to get good results from detecting 2D human poses from a single color image. In this paper, we investigate a detection method for estimating the position of the head and shoulder keypoints and the acceleration of positional change using the skeletal keypoints information extracted using PoseNet from an image obtained with a low-cost 2D RGB camera, increasing the accuracy of judgments about the falls. In particular, we propose a fall detection method based on the characteristics of post-fall posture in the fall motion-analysis method. A public data set was used to extract human skeletal features, and as a result of an experiment to find a feature extraction method that can achieve high classification accuracy, the proposed method showed a 99.8% success rate in detecting falls more effectively than a conventional, primitive skeletal data-use method.

• Environmental and Resource Economics Review
• /
• v.30 no.1
• /
• pp.79-105
• /
• 2021

In the circumstance of standing out the climate change issue, the purpose of this study is to compare the efficiency of offshore and coastal fisheries according to whether or not greenhouse gas (GHG) emissions are considered, and then to present policy alternatives based on the analysis results. For analysis, the traditional data envelopment analysis (DEA), the slacks-based measure (SBM) and the SBM-undesirable models were used, and robust analysis of variance (ANOVA) and Wilcoxon Signed-rank tests were performed. As a result, the study showed that the average efficiency of fisheries decreased as the traditional DEA extended to the SBM model considering the slack and the SBM-undesirable model including the GHG emissions. Specifically, the average efficiency of the traditional DEA model, SBM model, and SBM-undesirable model was analyzed as 0.7350, 0.5820 and 0.4976 respectively. In addition, the results of the robust ANOVA and Wilcoxon Signed-rank tests all showed that there are statistically significant differences in efficiency between offshore and coastal fisheries as well as among traditional DEA, SBM and SBM-undesirable models. As a policy alternative to the analysis, it was suggested that to improve the efficiency of coastal and offshore fisheries, it is necessary to actively implement the new fishing vessel project and develop smart and electric hybrid fishing vessels.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.12
• /
• pp.772-781
• /
• 2020

A direct shear member resists external forces through the shear transfer of reinforcing bars placed at the concrete interface. The current concrete structural design code uses empirical formulas based on the shear friction analogy, which is applied to the horizontal shear of concrete composite beams. However, in the case of a member with a large amount of reinforcing bars, the shear strength obtained through the empirical formula is lower than the measured value. In this paper, the limit state of newly constructed composite beams on an existing concrete girder is defined using stress field theory, and material constitutive laws are applied to gain horizontal shear strength while considering the tension-stiffening and softening effects of concrete struts. A simplified method of calculating the shear strength is proposed, which was validated by comparing it with the related design code provisions. As a result, it was confirmed that the method generally shows a similar tendency to the experimental results when the shear reinforcing bar yields, unlike the regulations of the design code, where differences in the predicted value of shear strength occur according to the shear reinforcement ratio.