• Korean Journal of Poultry Science
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• v.48 no.4
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• pp.185-191
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• 2021

Chicken spermatozoa have the ability to survive in low-temperature environments; however, the effects of low temperature on sperm motility and acrosome damage have not been studied in detail. The present study investigated semen longevity following dilution of rooster semen with Beltsville Poultry Semen Extender (BPSE) and Lake extender in preservation vessels (1.5 mL e-tube and 0.5 mL straw). Spermatozoa motility in the closed-type vessel (0.5 mL straw) was higher than that in the 1.5 mL e-tube on day 3 of preservation (68.6±3.1% vs. 22.1±5.7%). The motility of rooster semen diluted with BPSE in 0.5 mL straw was also higher than that of the Lake extender on day 3 of preservation (57.7±5.6% vs. 37.7±5.4%). Furthermore, acrosome intactness was higher in 0.5 mL straw than in the 1.5 mL e-tube, and the rate of acrosome cap damage increased with preservation days. The present study demonstrates that a closed 0.5-mL straw vessel could be used for low-temperature semen preservation, with an increased motility rate and acrosome integrity in fresh rooster semen.

• Tunnel and Underground Space
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• v.32 no.6
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• pp.373-385
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• 2022

The drum cutter, which is used in the form of an attachment of a excavator, is very useful in that it can be used in connection with a excavator that can perform various tasks in the field. This study estimated the load and torque acting on the drum cutter attachment by measuring the hydraulic pressure and strain that appear during excavation on the exposed rock slope using the drum cutter installed in the excavator. Working conditions such as the operation angle between the boom and arm of the excavator were divided into eight working modes. And as a result of analyzing the variations in hydraulic pressure and action force according to the working mode, it was confirmed that the hydraulic pressure and flow rate can be driven without any problems within the range considered in the manufacturing specifications of the drum cutter. The average load and torque acting on the drum cutter were within the range of the manufacturing specifications, but the maximum load was up to four times the specification. Because sumping was not properly performed due to the high ground strength and the ground included discontinuous surfaces in some locations, no trend of load and torque was found depending on the angle between the boom and arm of the excavator. However, it is believed that this result can be used to determine the range of loads and torques that appear on the drum cutter when excavating a high-intensity rock.

• Tunnel and Underground Space
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• v.32 no.6
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• pp.502-517
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• 2022

As the use of TBM increases, research has recently increased to to analyze TBM data with machine learning techniques to predict the exchange cycle of disc cutters, and predict the advance rate of TBM. In this study, a regression prediction of disc cutte wear of slurry shield TBM site was made by combining machine learning based on the machine data and the geotechnical data obtained during the excavation. The data were divided into 7:3 for training and testing the prediction of disc cutter wear, and the hyper-parameters are optimized by cross-validated grid-search over a parameter grid. As a result, gradient boosting based on the ensemble model showed good performance with a determination coefficient of 0.852 and a root-mean-square-error of 3.111 and especially excellent results in fit times along with learning performance. Based on the results, it is judged that the suitability of the prediction model using data including mechanical data and geotechnical information is high. In addition, research is needed to increase the diversity of ground conditions and the amount of disc cutter data.

• Tunnel and Underground Space
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• v.32 no.6
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• pp.353-362
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• 2022

The wet shotcrete refers to a method in which all materials are mixed and then supplied to the spraying device, compressed air is added to the nozzle, and the spraying speed is improved to spray on the target surface. In order to reproduce the amount of shotcrete used in the wet method in the field and the situation at the laboratory scale, it is essential to control the discharge amount of the equipment. In this study, in order to increase the reproducibility of field conditions at the laboratory scale, a flow control system for shotcrete mortar spraying equipment was developed and applied to the equipment. To verify the developed equipment, a discharge control test using water and mortar was performed. In the developed control system, the discharge was smoothly controlled according to the user input value for the mono pump, but the discharge was not properly controlled according to the input value for the screw pump because of a reducer. When a speed reducer is attached, it is necessary to adjust the operation rate of the screw pump close to the target flow rate by increasing the operation rate of the screw pump while lowering the operation rate of the mono pump.

• Journal of the Korean Geosynthetics Society
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• v.21 no.4
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• pp.21-29
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• 2022

The room-and-pillar method or grid-type underground space is a method of forming a space by excavating the excavation part at regular intervals so that it is orthogonal and using natural rock mass as a structure. Such excavation may appear different in size from the excavation stage where the maximum displacement occurs depending on the excavation direction and sequence. In this study, considering the installation of support materials such as shotcrete and rock bolts for the optimal design of the excavation process, the safety and constructability of the design and construction of the grid-type underground space under specific ground conditions were analytically reviewed. The ground conditions were set using an numerical method, and the stress at pillar and displacement at center of room were considered for each excavation stage and construction type under a constant surcharge. The height of the space was 8m, which was set higher than the size of a general office, and was reviewed in consideration of equipment and plant facilities. In addition, the degree of displacement control according to the installation of support materials was reviewed in consideration of shotcrete and rock bolts.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.1
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• pp.171-176
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• 2023

The purpose of this study is to analyze the introduction and use cases of Metaverse in the financial sector to learn lessons and implications. Let's take a look. The era of the metaverse is coming. The financial sector is pioneering the blue ocean market in a new era and working with the MZ generation. In order to expand contact points, we are very interested in the new business model, Metaverse, and are actively engaged in research and development. appear to be participating. In the case of finance, information is efficiently transmitted through metaverse, and customers It is predicted that the convenience of customers will be greatly improved by making it possible to use convenient services without visiting a branch. Additionally, by utilizing technologies such as AR and VR, we are trying to provide services linked to the metaverse in earnest. In addition, new financial services such as non-face-to-face asset management consulting services and brokerage services for funds through Metaverse Business models are also expected to be created. It is still in its infancy, and it is currently in its infancy, Metaverse is being used for educational purposes.

• Tunnel and Underground Space
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• v.32 no.6
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• pp.363-372
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• 2022

Precast concrete is an effective method to increase the construction quality and construction speed by optimizing and making the manufacturing conditions similar. In order to more effectively produce a fireproof material-integrated precast duct slab, the purpose of this study was to determine whether the fire resistance performance of the fireproof layer is maintained when a method of increasing the curing rate using a hardening accelerator is used. As a result of performing a fire resistance performance test on specimens classified according to whether or not the hardening accelerator was included, increase of temperature inside the specimen was high in the specimens using the hardening accelerator, and the section loss of the fireproof layer occurred locally on the surface exposed to fire heating. In conclusion, it is judged that the fireproof layer in the case where the strength at 3th day of age is gained within 1 day curing age using a hardening accelerator does not guarantee sufficient fire resistance performance in the conditions used in this study.

• Korean Journal of Materials Research
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• v.32 no.11
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• pp.481-488
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• 2022

The Cu₂ZnSn(S_xSe_1-x)₄ (CZTSSe) absorbers are promising thin film solar cells (TFSCs) materials, to replace existing Cu(In,Ga)Se₂ (CIGS) and CdTe photovoltaic technology. However, the best reported efficiency for a CZTSSe device, of 13.6 %, is still too low for commercial use. Recently, partially replacing the Zn²⁺ element with a Cd²⁺element has attracting attention as one of the promising strategies for improving the photovoltaic characteristics of the CZTSSe TFSCs. Cd²⁺ elements are known to improve the grain size of the CZTSSe absorber thin films and improve optoelectronic properties by suppressing potential defects, causing short-circuit current (J_sc) loss. In this study, the structural, compositional, and morphological characteristics of CZTSSe and CZCTSSe thin films were investigated using X-ray diffraction (XRD), X-ray fluorescence spectrometer (XRF), and Field-emission scanning electron microscopy (FE-SEM), respectively. The FE-SEM images revealed that the grain size improved with increasing Cd²⁺ alloying in the CZTSSe thin films. Moreover, there was a slight decrease in small grain distribution as well as voids near the CZTSSe/Mo interface after Cd²⁺ alloying. The solar cells prepared using the most promising CZTSSe absorber thin films with Cd²⁺ alloying (8 min. 30 sec.) exhibited a power conversion efficiency (PCE) of 9.33 %, J_sc of 34.0 mA/cm², and fill factor (FF) of 62.7 %, respectively.

• 지역과문화
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• v.7 no.3
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• pp.49-79
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• 2020

This study focuses on the analyzing historical and cultural resources formed during the Goryeo, Chosun, and Anti-Japanese Movement periods after the Silla period with the aim of finding ways to utilize its cultural contents. The viewpoint of analysis was made from the perspective of exchange, naturalization, and faith, and the following conclusions were obtained from the analysis. First of all, from the exchange perspective, the activities of Choi Chi-won, Seogyu, and Song Young-gu contributed to the formation of regional historical and cultural contents, such as leaving a lot of ruins or geographic stories in the area and a heritage of good human exchange. From the point of view of naturalization, Du Kyung-ryeong, Cheon Man-ri, and Jeong Yul-seong contributed to the history and culture of the story and the formation of heritage by doing such as contributing activities to the war, anti-Japanese movement for the nation, and the formation of the nation. The most representative from a religious point of view is the Guan Yu faith, which has become a faith believed by the authorities and civilian as a brave longevity and a symbol of the victory of war. The related symbols, paintings, etc. also are objects of worship and have become valuable local Chinese cultural resources as artistic values. Therefore, from a cultural point of view, there is a need to further develop and utilize these China-related historical and cultural resources as good cultural contents by elaborating their stories and local festivals, book culture branding, international music festivals, and exploring various cultures such as Chinese tour courses.

• Clinical Pain
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• v.19 no.2
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• pp.70-79
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• 2020

Objective: We evaluated the efficacy of a newly-developed spinal orthoses (V-LSO) by comparing the stabilizing effect, abdominal pressure, and comfort of 3 different semirigid LSOs (classic LSO, V-LSO, and Cybertech^®) during various body movements. Method: Thirty healthy volunteers (23~47 years, 24 males, 6 females) were selected. A dual inclinometer measured the range of motion (ROM) while the participants performed flexion/extension and lateral flexion of the lumbar spine with 3 LSOs. The LSO's pressure on the abdominal surface was measured using 9 pressure sensors while lying, sitting, standing, flexion/extension, lateral flexion, axial rotation, and lifting a box. Comfort and subjective immobilization were analyzed by a questionnaire. Results: V-LSO had a statistically significant effect on flexion over Cybertech^®. No significant differences were noted during extension and lateral flexion between the 3 LSOs. The abdominal pressure showed no significant differences while supine. While sitting, standing, and lifting a box, the mean abdominal pressure for V-LSO were significantly higher than those for Cybertech^®. During lumbar flexion, the mean abdominal pressures for classic LSO and V-LSO were significantly higher than that of Cybertech^®. For extension, lateral flexion and axial rotation, the abdominal pressure for V-LSO was significantly higher than those of classic LSO and Cybertech^®. In the subjective analysis, V-LSO and Cybertech^® scored best for comfort. Conclusion: The V-LSO and Cybertech^® were more comfortable than the classic LSO, and hence, may have improved compliance with decreased discomfort. V-LSO may be superior to the other LSOs in restricting lumbar movement and increasing intraabdominal pressure.