• Journal of Digital Convergence
• /
• v.17 no.7
• /
• pp.131-138
• /
• 2019

The world's electricity production ratio is 40% for coal, 20% for natural gas, 16% for hydroelectric power, 15% for nuclear power and 6% for petroleum. Fossil fuels also cause serious problems in terms of price and supply because of the high concentration of resources on the earth. Solar energy is attracting attention as a next-generation eco-friendly energy that will replace fossil fuels with these problems. In this study, we test the charge-operation plan and the discharge operation plan for peak-cut operation by applying the maximum power demand reduction simulation. To do this, we selected the electricity usage from November to February, which has the largest amount of power usage, and applied charge / discharge logic. Simulation results show that the contract power decreases as the peak demand power after the ESS Peak-cut service is reduced to 50% of the peak-target power. As a result, the contract power reduction can reduce the basic power value of the customer and not only the economic superiority can be expected, but also contribute to the improvement of the electric quality and stabilization of the power supply system.

• Korean Journal of Heritage: History & Science
• /
• v.42 no.3
• /
• pp.176-191
• /
• 2009

This report is a result of investigating the materials and techniques of the lacquer ware excavated from Hwangnamdaechong Tomb known as an old tomb in the Gyeongju maximum district. First, the fragment of lacquer ware was classified by the shape of it. Next, the thin section of lacquer film (all sides about 2mm) was made based on the result. Then they were observed under the microscope, and classified the kind of the foundation mixture and the applied structure. It is a result as follows. 1 The bone dust was mixed by the foundation of the made of cloth-body lacquer ware such as eared lacquer cup, lacquer bowl, and the lacquer rectangular containers excavated from the south tomb. 2 Eared lacquer cup and lacquer bowl, and rectangular box excavated from south and north tomb had the possibility they were the set of articles partially of tableware and the cosmetic box. 3 There is a difference in the quality of burial lacquer ware between in south tomb and north tomb. A lot of highlevel lacquer ware such as eared lacquer cup, lacquer bowl and the rectangular lacquer containers were discovered from the south tomb. 4 Many of containers where animal and bird had been drawn on the black lacquered ground excavated from north tomb were wooden bath.

• Korean Journal of Food Science and Technology
• /
• v.52 no.6
• /
• pp.641-648
• /
• 2020

The objective of this study was to optimize the mixing ratio of mixed bean protein concentrate (MBPC) and to improve the quality of sausage analogues. Soybean (Glycine max MERR), mung bean (Phaseolus radiatus L.), red bean [Vigna angularis (Wild.)], and pea (Pisum sativum L.) were mixed and processed to produce a MBPC, which was used to make a sausage analogue. The protein, moisture, and carbohydrate content were significantly (p<0.05) different among the samples. A significant (p<0.05) improvement was observed in textural properties (hardness, gumminess, and chewiness), cooking loss, frying loss, and emulsion stability of the sausage analogue. This study suggested the possibility of attaining high-quality sausage analogues and partial sausage analogues using MBPC, which could serve as a potential ingredient in meat analogues.

• The Journal of Engineering Geology
• /
• v.30 no.4
• /
• pp.649-661
• /
• 2020

Cut-slope management system (CSMS) has been investigated all slopes on the road of the whole country to evaluate risk rating of each slope. Based on this evaluation, the decision-making for maintenance can be conducted, and this procedure will be helpful to establish a consistent and efficient policy of safe road. CSMS has updated the database of all slopes annually, and this database is constructed based on a basic and detailed investigation. In the database, there are two type of data: first one is an objective data such as slopes' location, height, width, length, and information about underground and bedrock, etc; second one is subjective data, which is decided by experts based on those objective data, e.g., degree of emergency and risk, maintenance solution, etc. The purpose of this study is identifying an data application plan to utilize those CSMS data. For this purpose, logistic regression, which is a basic machine-learning method to construct a prediction model, is performed to predict a judging-type variable (i.e., subjective data) based on objective data. The constructed logistic model shows the accurate prediction, and this model can be used to judge a priority of slopes for detailed investigation. Also, it is anticipated that the prediction model can filter unusual data by comparing with a prediction value.

• Journal of Digital Convergence
• /
• v.19 no.1
• /
• pp.29-43
• /
• 2021

Coinciding with the advent of COVID-19, online education is on the rise both domestically and globally, and has become an absolutely necessary and irreplaceable form of education. It is a very curious question what the perception of people about the suddenly growing form of education is, and how it has changed. This study investigated changes in consumers' perception of online education using big data. To this end, we divided the time into four stages: before COVID-19 (November to December 2019), after the triggering of COVID-19 (January to February 2020), right after the online classes started (March to April 2020), after experiencing some online education (May to June 2020). Then we conducted text mining, namely, keyword frequency analysis, network analysis, word cloud analysis, and sentiment analysis were performed. The implications derived as a result of the analysis can help education policy makers and educators working in the field to improve online education quality and establish its future directions.

• Korean Journal of Remote Sensing
• /
• v.36 no.6_1
• /
• pp.1323-1337
• /
• 2020

GEO-KOMPSAT-2A AMI (Advanced Meteorological Imager) radiometric calibration evaluation is an essential element not only for functional and performance verification of the payload but for the quality of the sensor data. AMI instrument consists of six reflective channels and ten thermal infrared ones. One of the key parameters representing radiometric properties of the sensor is a SNR (Signal-to-Noise Ratio) for the reflective channels and a NEdT (Noise Equivalent delta Temperature) for the IR ones respectively. Other important radiometric calibration parameters are a dynamic range and a gain value related with the responsivity of detectors. To verify major radiometric calibration performance of AMI, an offline radiometric evaluation tool was developed separately with a real-time AMI data processing system. Using the evaluation tool, validation activities were carried out during the GEO-KOMPSAT-2A In-Orbit Test period. The results from the evaluation tool were cross checked with those of the HARRIS, which is the AMI payload vendor. AMI radiometric evaluation activities were conducted through three phases for both sides (Side 1 and Side 2) of AMI payload. Results showed that performances of the key radiometric properties were outstanding with respect to the radiometric requirements of the payload. The effectiveness of the evaluation tool was verified as well.

• The Journal of Society for e-Business Studies
• /
• v.26 no.4
• /
• pp.81-93
• /
• 2021

Through processors, wholesale markets, intermediate sellers, and retailers, agricultural products have been distributed in a multi-level customary manner for a long time as they are easy to deteriorate and no not have a standardized system of size and quality. However, with the advancement of Internet networks and logistic services during the 2000s that facilitated the development of offline markets, and the rise of the non-contact purchase preference in direct response to COVID-19, previous offline consumers flowed into the online market to purchase agricultural goods. In other words, the volume of online agricultural transactions exploded since the pandemic. Against this social backdrop, this study focused on the difference in distribution costs as a result of converting from conventional offline distribution channels to online channels, and analyzed the reduced distribution costs through a case study of garlic sales on the online platform "H" shopping mall. The analysis found that considerable economic effects occurred, some of the effects being an approximate 39% decrease in distribution cost when comparing direct online transactions of the online shopping mall with other more traditional means, a reduced distribution cost rate of approximately 28%p, and increased profit for farmers.

• The Journal of the Korea Contents Association
• /
• v.22 no.1
• /
• pp.646-655
• /
• 2022

This study was conducted to investigate the quality characteristics of Kimchi during fermentation and storage according to containers with native plant extract. The containers used in the experiment were antimicrobial polypropylene containers(KAPP) developed with the addition of native plant extracts, and it was tested by comparing the microbial changes and sensory characteristics of the existing commercial containers, such as polypropylene containers(KPP), stainless steel containers(KST), and porcelain containers(KPC). Change in total microbial cell were similar for each container. Coliform maintained the lowest level from 15 days after storage to 50 days. Leuconostoc spp. and Lactobacillus spp. showed a rapid increase in all four storage containers until the 15th day of storage and then decreased. The KAPP container maintained its highest level. The sensory evaluation was carried out on Kimchi optimal condition(storage 40 days). The sensory scores of KAPP were generally higher than those of other experimental samples in characteristics of appearance, odor, taste and overall preference. As a result, KAPP container has an excellent antibacterial effect as compared with the three commercially available storage containers, is effective for fermentation of lactic acid.

• Journal of Korea Water Resources Association
• /
• v.55 no.9
• /
• pp.679-686
• /
• 2022

As the occurrences of flash floods have increased due to climate change, faster and more accurate precipitation observation using X-band radar has become important. Therefore, the Ministry of Environment installed two dual-pol X-band radars at Samcheok and Uljin. The radar data used in this study were obtained from two different elevation angles and composed to reduce the shielding effect. To obtain quantitative rainfall, quality control (QC), K_DP retrieval, and Hybrid Surface Rainfall (HSR) methods were sequentially applied. To improve the accuracy of the quantitative precipitation estimation (QPE) of the X-band radar, we retrieved parameters for the relationship between rainfall rate and specific differential phase, which is commonly called the R-K_DP relationship; hence, an empirical approach was developed using multiple rain gauges for those two radars. The newly suggested relationship, R = 27.4K^0.81_DP, slightly increased the correlation coefficient by 1% more than the relationship suggested by the previous study. The root mean square error significantly decreased from 3.88 mm/hr to 3.68 mm/hr, and the bias of the estimated precipitation also decreased from -1.72 mm/hr to -0.92 mm/hr for overall cases, showing the improvement of the new method.

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