• KEPCO Journal on Electric Power and Energy
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• v.6 no.4
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• pp.461-466
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• 2020

There are many application fields of electrical energy storage such as load shifting, integration with renewables, frequency or voltage supports, and so on. Especially, the frequency regulation is needed to stabilize the electric power system, and there have to be more than 1 GW as power reserve in Korea. Ni-rich layered oxide cathode materials have been investigated as a cathode material for Li-ion batteries because of their higher discharge capacity and lower cost than lithium cobalt oxide. Nonetheless, most of them have been investigated using small coin cells, and therefore, there is a limit to understand the deterioration mode of Ni-rich layered oxides in commercial high energy Li-ion batteries. In this paper, the pouch-type 20 Ah-scale Li-ion full cells are fabricated using Ni-rich layered oxides as a cathode and graphite as an anode. Above all, two test conditions for the application of frequency regulation were established in order to examine the performances of cells. Then, the electrochemical performances of two types of Ni-rich layered oxides are compared, and the long-term performance and degradation mode of the cell using cathode material with high nickel contents among them were investigated in the frequency regulation conditions.

• Wind and Structures
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• v.34 no.2
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• pp.199-213
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• 2022

The current study investigates the dynamic effects in the tornado-structure response of an aeroelastic self-supported lattice transmission tower model tested under laboratory simulated tornado-like vortices. The aeroelastic model is designed for a geometric scale of 1:65 and tested under scaled down tornadoes in the Wind Engineering, Energy and Environment (WindEEE) Research Institute. The simulated tornadoes have a similar length scale of 1:65 compared to the full-scale. An extensive experimental parametric study is conducted by offsetting the stationary tornado center with respect to the aeroelastic model. Such aeroelastic testing of a transmission tower under laboratory tornadoes is not reported in the literature. A multiaxial load cell is mounted underneath the base plate to measure the base shear forces and overturning moments applied to the model in three perpendicular directions. A three-axis accelerometer is mounted at the level of the second cross-arm to measure response accelerations to evaluate the natural frequencies through a free-vibration test. Radial, tangential, and axial velocity components of the tornado wind field are measured using cobra probes. Sensitivity analyses are conducted to assess the variation of the structural dynamic response associated with the location of the tornado relative to the lattice transmission tower. Three different layouts representing the change in the orientation of the tower model relative to the components of the tornado-induced loads are considered. The structural responses of the aeroelastic model in terms of base shear forces, overturning moments, and lateral accelerations are measured. The results are utilized to understand the dynamic response of self-supported transmission towers to the tornado-induced loads.

• The Journal of the Convergence on Culture Technology
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• v.9 no.4
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• pp.393-399
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• 2023

Upper limb amputees wear an upper limb prosthesis for both aesthetic purposes and functional necessity, and in particular, in the case of amputee with both hands, it is essential to wear a myoelectric prosthetic hand capable of gripping action. The prosthetic hand operated by the EMG signal of the remaining muscles is a public insurance benefit item of the Industrial Accident Compensation Insurance, and test method standards are needed to be developed for the safety of the user and the effectiveness of the product performance. In this study, we developed systems for measuring the gripping force of myoelectric hand prosthesis by a load cell and for durability test of the prosthesis over repeated use with a proximity sensor, and propose a test method standard. Since the international test method standard has not yet been established, it is expected that Korea will be able to play a leading role in this standardization field in the future.

• Journal of Information Technology Services
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• v.22 no.6
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• pp.87-102
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• 2023

Existing child car seats do not have a monitoring means for the driver or guardian to effectively recognize the status of whether the seat belt of car seat is fastened and whether the ISOFIX of the car seat is fastened to the inside device of the vehicle. In this paper, we propose a smart car seat system which can monitor in real time, whether the seat belt of a child seated in the car seat is fastened and whether the ISOFIX of the car seat is fastened. The proposed system has been developed with a prototype, in which a Hall sensor, magnet, Bluetooth, and display device are used to detect whether these are fastened and to display the detection results. The prototype system provides the detection results as texts and alarm signal to the display for driver or guardian' smartphone in the car in motion. With functional tests of the prototype system, it was confirmed that the detection functions are properly operated, and the detection results were transmitted to the display device and smartphone via Bluetooth within 0.5 seconds. It is expected that the development system can effectively prevent safety accidents of child car seats.

• Korean Journal of Agricultural Science
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• v.50 no.4
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• pp.773-784
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• 2023

In this study, we developed a dynamic model and steering controller model for an autonomous tractor and evaluated their performance. The traction force was measured using a 6-component load cell, and the rotational speed of the wheels was monitored using proximity sensors installed on the axles. Torque sensors were employed to measure the axle torque. The PI (proportional integral) controller's coefficients were determined using the trial-error method. The coefficient of the P varied in the range of 0.1 - 0.5 and the I coefficient was determined in 3 increments of 0.01, 0.05, and 0.1. To validate the simulation model, we conducted RMS (root mean square) comparisons between the measured data of axle torque and the simulation results. The performance of the steering controller model was evaluated by analyzing the damping ratio calculated with the first and second overshoots. The average front and rear axle torque ranged from 3.29 - 3.44 and 6.98 - 7.41 kNm, respectively. The average rotational speed of the wheel ranged from 29.21 - 30.55 rpm at the front, and from 21.46 - 21.63 rpm at the rear. The steering controller model exhibited the most stable control performance when the coefficients of P and I were set at 0.5 and 0.01, respectively. The RMS analysis of the axle torque results indicated that the left and right wheel errors were approximately 1.52% and 2.61% (at front) and 7.45% and 7.28% (at rear), respectively.

• Korean Journal of Agricultural Science
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• v.51 no.1
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• pp.63-77
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• 2024

Yield monitoring systems have become integral to precision agriculture, providing insights into the spatial variability of crop yield and playing an important role in modern harvesting technology. This paper aims to review current research trends in yield monitoring systems, specifically designed for non-grain crops, including cabbages, radishes, potatoes, and tomatoes. A systematic literature survey was conducted to evaluate the performance of various monitoring methods for non-grain crop yields. This study also assesses both mass- and volume-based yield monitoring systems to provide precise evaluations of agricultural productivity. Integrating load cell technology enables precise mass flow rate measurements and cumulative weighing, offering an accurate representation of crop yields, and the incorporation of image-based analysis enhances the overall system accuracy by facilitating volumetric flow rate calculations and refined volume estimations. Mass flow methods, including weighing, force impact, and radiometric approaches, have demonstrated impressive results, with some measurement error levels below 5%. Volume flow methods, including paddle wheel and optical methodologies, yielded error levels below 3%. Signal processing and correction measures also play a crucial role in achieving accurate yield estimations. Moreover, the selection of sensing approach, sensor layout, and mounting significantly influence the performance of monitoring systems for specific crops.

• Pediatric Infection and Vaccine
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• v.30 no.3
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• pp.173-179
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• 2023

Complete DiGeorge syndrome (cDGS) refers to DGS with profound T cell deficiency. Herein, we present the case of an infant with cDGS suffering from refractory cytomegalovirus (CMV) infection and who was treated with CD45RA+ depleted lymphocyte infusion. The patient was diagnosed with cDGS by fluorescence in situ hybridization which verified 22q11.2 deletion and as well as by the observed profound T cell deficiency (CD3+ T cells 69/μL, CD4+ T cells 7/μL). On the 45th day of age, CMV viremia was first detected with a plasma viral load (VL) of 120,000 IU/mL. Ganciclovir treatment effectively reduced VL post 56 days of treatment; however, VL subsequently rebounded. A CMV UL97 phosphotransferase M460V mutation conferring ganciclovir resistance emerged and foscarnet was incorporated. Despite this, high titers of CMV viremia (VL 2,820,000 IU/mL) and CMV retinitis were complicated. To restore T cell immunity and treat refractory CMV infection, CD45RA+ depleted CMV-specific lymphocytes from the patient's father were infused twice on the 196th and 207th days after birth. After receiving the second infusion, a decline in CMV VL was observed, with a decrease to 87,100 IU/mL by the tenth day following infusion, despite the failure in maintaining T cell increase. The patient died of Pneumocystis jirovecii pneumonia and Elizabethkingia meningoseptica sepsis on the 222nd day after birth. CD45RA+ depleted lymphocyte infusion may be a therapeutic option for refractory CMV disease in cDGS patients.

• Journal of Bio-Environment Control
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• v.6 no.4
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• pp.250-257
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• 1997

Stem diameter and shoot fresh weight of tomato grown in greenhouse were measured non-destructively at 10 minutes interval from 1 to 16 July, 1996 with displacement detector using strain gauges and with suspension-type load cell, respectively, and simultaneously were measured soil water potential, transpiration and solar radiation. Ample water was irrigated before experiment, and thereafter, irrigations were made on the next morning when visual symptoms of wilting appeared. Shoot fresh weight and stem diameter showed very similar patterns in diurnal changes which are characterized by predawn maximum and afternoon minimum and in long- term evolutions, suggesting that stem diameter shrinkage and expansion are closely related to plant water content and growth, respectively, Shoot weight and stem diameter reached minimum values a little later than the time on which transpiration showed maximum. The daily net gains of fresh weight(DG) and stem diameter(DI) showed significantly Positive correlations with solar radiation in those days on which plants were not water-stressed. However, Dl and DG on those days of water stress showed much lower values than expected from the relationships between solar radiation and them. Transpiration was much lower than the expected potential transpiration on 10 July, implying that plants were water-stressed. In this case water stress was not detected from visual symptom of wilting and/or soil water potential, but was able to be identified by the lower DI and DG than the expected. The maximum contraction of stem diameter(MC) and the maximum loss of fresh weight(ML) during daytime showed significantly positive correlations with solar radiation in those days on which plants were not water-stressed and were observed greater than expected from the relationships on severely water-stressed days. But mild water stress could not be discernable by ML and MC. It would be concluded that the daily net gains of fresh weight and/or stem diameter could be used as criteria for diagnosing the water status of tomato and for triggoring the onset of irrigation in automatic system.

• Journal of Dental Rehabilitation and Applied Science
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• v.26 no.4
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• pp.405-417
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• 2010

Previous studies have already shown that mouthguard is effective in protecting jaw bone, teeth and oral tissue against sports trauma. However, other than severe trauma, repetitive force, such as disorders like clenching, cause teeth or oral tissue damage. These kinds of disorders usually present pathologic attrition in the posterior teeth, resorption in alveolar bone, loss of teeth and destruction of occlusion. Wearing a mouthguard is believed to be effective in preventing these disorders. But its effect is not examined thoroughly enough. The purpose of this study is to identify whether mouthguard is effective in reducing strain caused by clenching. Mandibular first molars in the normal occlusal relationship without any history of dental treatment were chosen. Biaxial type strain gauge was placed on the buccal surface of the tooth. Having maximum occlusal force, measured by load cell, as a standard, clenching intensity were divided into three stages; moment of slightly tooth contact, medium bite force (50% of maximum bite force), maximum bite force. Strain occurring in dentition in each stage with and without mouthguard was measured. Changes in strain (on dentition) between each stage and difference in strain, between with or without mouthguard were recorded by PCD-300 analyzer and PCD-30 soft ware. The data was statistically analyzed by Wilcoxon signed rank test. The following results were drawn; Without mouthguard, strain given on dentition increased as the clenching force increased. With mouthguard, strain given on dentition also increased as the clenching force increased. With mouthguard, strain decreased, in all cases of clenching force stages. Data on the moment of slightly tooth contact stage, had no statistical significance. However, with mouthguard, 50-90% of decrease in strain could be obtained in maximum occlusal force, compared to the group without mouthguard. Mouthguard decreased the strain on the dentition, caused by clenching. Therefore, mouthguard seems to be effective in preventing damage on dentition, by acting against clenching, which occurs both consciously and unconsciously during sports activities.

• 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.