• Journal of the Korea institute for structural maintenance and inspection
• /
• v.25 no.6
• /
• pp.262-269
• /
• 2021

This paper conducts an evaluation of the structural performance of the lap splice detail of SD700 headed bar experiment for developing an RC beam with different depths joint details. The experiment variable is lap splice length, yield strength, and end anchorage of main reinforcements. For all specimens, a headed bar was applied to the main reinforcement of the beam with low depth (B2), and the beam with high depth (B1) was applied to the main reinforcement with two splice methods: straight headed bar and 90° hooked-headed bar. The experimental results were that specimens of applying SD500 and SD600 had the results of flexural fracture at the lap splice location, which maximum load was similar. For specimens of appling SD500, the 90° hooked-headed bar of B1, suppressed horizontal cracks in the lap splice section compared to the straight headed bar. Specimens of applying an SD 700 headed bar had the results of brittle anchorage failure. In addition, maximum load was increased with the lap splice length increasing. For specimens of applying SD700 headed bar, test for test maximum load/theoretical load for test development length/design development length were estimated to be 1.30~1.48 for the ACI 318-19 equation, and 1.14~1.30 for the KDS-2021 equation. Thus, ACI 318-19 equation had conservatively greater safety factors as estimated development lengththened.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.25 no.5
• /
• pp.173-181
• /
• 2021

Reinforced concrete structures are exposed to various environments, resulting in reinforcement corrosion due to moisture and ions penetration. Reinforced concrete corrosion causes a decrease in the durability performance of reinforced concrete structures. One solution to mitigate such issues is using FRP rebars, which offer several advantages such as high tensile strength, corrosion resistance, and light-weight than conventional rebars, in reinforced concrete instead of conventional steel rebars. The FRP rebar used should be examined at the limit state because FRP reinforced concrete has linear behavior until its fracture and can generate excessive deflection due to the low elastic modulus. It should be considered while designing FRP reinforced concrete for flexure. In the ultimate limit state, the flexural strength of FRP reinforced concrete as per ACI 440.1R is significantly lower than the flexural strength by applying both the environmental reduction and strength reduction factors accounting for the material uncertainty of FRP rebar. Therefore, in this study, the experimental results were compared with the deflection of the proposed effective moment of inertia referring to the local and international standards. The experimental results of GFRP and BFRP reinforced concrete were compared with the flexural strength as determined by ACI 440.1R and Fib bulletin 40. The flexural strength obtained by the experimental results was more similar to that obtained by Fib bulletin 40 than ACI 440.1R. The flexural strength of ACI 440.1R was conservatively evaluated in the tension-controlled section.

• Journal of Veterinary Science
• /
• v.21 no.5
• /
• pp.77.1-77.14
• /
• 2020

Background: Staphylococcus aureus is one of the main microorganisms that causes bovine mastitis, and its well-known virulence characteristics and interactions with the environment are used to aid the design of more efficient therapies. Objectives: To determine whether the virulence traits, such as antibiotic resistance and biofilm-forming and internalization abilities, of S. aureus isolated from bovine mastitis are related to dairy production system types. Methods: The study was performed in the Mexican states of Guanajuato and Michoacan. Semi-intensive dairy farms (SIDFs) and family dairy farms (FDFs) (454 and 363 cows, respectively) were included. The 194 milk samples from mastitis affected quarters were collected and 92 strains of S. aureus were isolated and identified by biochemical and molecular tests. Antibiotic resistance, biofilm and internalization assays were performed on 30 randomly selected isolated strains to determine virulence traits, and these strains were equally allocated to the 2 dairy production systems. Results: All 30 selected strains displayed a high degree of resistance (50%-91.7%) to the antibiotics tested, but no significant difference was found between SIDF and FDF isolates. S. aureus strains from SIDFs had an average biofilm forming capacity of up to 36% (18.9%-53.1%), while S. aureus strains from FDFs registered an average of up to 53% (31.5%-77.8%) (p > 0.05). Internalization assays revealed a higher frequency of internalization capacity for strains isolated from FDFs (33.3%) than for those isolated from SIDFs (6.7%) (p > 0.05). fnbpA gen was detected in 46.6% of FDF strains and 33.3% of SIDF strains, and this difference was significant (p < 0.05). Conclusions: Our findings show that the virulence traits of S. aureus isolates analyzed in this study, depend significantly on several factors, such as phenotype, genotype, and environmental conditions, which are significantly related to dairy production system type and daily management practices.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.10 no.1
• /
• pp.101-110
• /
• 2022

In this study, water content tests were performed on various fresh concretes subjected to different binder compostions to review the estimation errors and reliability of water content test methods. Micro-oven drying method, air-meter method, capacitance method and microwave penetration method were used to estimate water content of fresh concrete. Errors in water content estimation were analyzed by each test method. Regardless of the test method of water content, the estimation error was less than 5 %, and in the case of the test using mortar, the error in the estimation value was relatively large. In addition, based on the test results of water content of various concrete, the probability density function in which the estimation error for each test method becomes the population was analyzed. Water content test methods of fresh concrete which using concrete samples showed high estimate reliability of 97 % within the estimation error range of ± 10 kg/m³. On the other hand, the reliability of water content test method using mortar samples was lower.

• Journal of the Korean Institute of Gas
• /
• v.26 no.6
• /
• pp.30-36
• /
• 2022

In commercial transactions of energy sources using hydrogen charging stations, high-accuracy flow meters are needed to prevent accidents such as overcharging due to inaccurate measurements and to ensure transparency in hydrogen commercial transactions through accurate measurements. This research developed a Corioli-type flowmeter prototype and conducted a risk assessment to prevent accidents during a process change comparison experiment for existing charging stations to verify the measurement performance. A process change section was defined for the installation of measurement facilities for empirical experiments and HAZOP was conducted. In addition, JSA was also conducted to secure the safety of experimenters, such as preventing valve mis-opening during empirical experiments. Measures were established to improve the risk factors derived through HAZOP, and work procedures were established to minimize human errors and ensure the safety of workers through JSA. The design change and system manufacturing for the installation of the metering system were completed by reflecting the risk assessment results, and safety could be confirmed through the performance comparison test of the developed meter prototype. The developed prototype flow meter showed a total of 30 flow measurements under the operating conditions of 70 MPa, and the average error was -1.58% to 3.96%. Such a metering error was analyzed to have the same performance as a flow meter installed and operated for commercial use.

• Journal of the Korean Geotechnical Society
• /
• v.38 no.11
• /
• pp.69-86
• /
• 2022

The railway is widely used to transport passengers and freight due to its punctuality and large transport capacity. The recent remarkable development in construction technology enables various subsea railway tunnels for continent-continent or continent-island connectivity. In Korea, design and construction experience is primarily based on the successful completion of the Boryeong subsea tunnel (2021) and the Gadeok subsea tunnel (2010). However, frequent earthquakes with diverse magnitudes, globally induced and continuously increased the awareness of seismic risks and the frequency of domestic earthquakes. The effect of an earthquake on the subsea tunnel is very complicated. However, ground conditions and seismic waves are considered the main factors. This study simulated four ground types of 3-dimensional numerical models, such as soil, rock, composite, and fractured zone, to analyze the effect of ground type and seismic wave. A virtual subsea railway shield tunnel considering external water pressure was modeled. Further, three different seismic waves with long-term, short-term, and both periods were studied. The dynamic analyses by finite difference method were performed to investigate the displacement and stress characteristics. Consequently, the long-term period wave exhibited a predominant lateral displacement response in soil and the short-term period wave in rock. The artificial wave, which had both periodic characteristics, demonstrated predominant in the fractured zone. The effect of an earthquake is more noticeable in the stress of the tunnel segment than in displacement because of confining effect of ground and structural elements in the shield tunnel. 

• The Korea Journal of Herbology
• /
• v.34 no.1
• /
• pp.117-124
• /
• 2019

Objective : Chronic acid reflux esophagitis (CARE), one of gastroesophageal reflux disease (GERD) is increasing worldwide. Coptidis rhizoma extract (CRE) is a traditional herb that cures a variety of diseases. This study was conducted to evaluate the protective effect of CR on rats with chronic acid reflux esophagitis. Methods : The antioxidant activities were evaluated through radical scavenging assays using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis (3-ethylbenzothiazolin-6-sulfonic acid) (ABTS) radical scavenging assays. CARE was surgically induced in 5-week-old male SD rats by ligating the border between forestomach and glandular portion with a 2-0 silk tie and covering the duodenum using 18-Fr $N{\acute{e}}laton$ catheter. To evaluate the esophageal protective effect of CRE, rats were divided into 3 groups: Nor (normal rats), Veh (chronic acid reflux esophagitis induced rats), CR (chronic acid reflux esophagitis induced rats treated with CRE 200 mg/kg body weight). Results : The administration of CRE significantly prevented the mucosal injury of the esophagus tissue and histological findings improved the esophageal lesion. It has been shown that inflammation is prevented by the increase of antioxidant-related factors (Nrf-2, HO-1, SOD, catalase, and GPx-1/2) through the antioxidant pathway of esophageal tissue. The administration of CRE reduced the increase of serum peroxynitrite ($ONOO^-$) and markedly reduced the protein expression of inflammatory mediator such as $NF-{\kappa}Bp65$, $p-I{\kappa}B{\alpha}$, iNOS, and IL-6. Conclusions : Overall, these results suggest that CRE administration confirmed the protective effect of esophageal mucosa, suggesting that it is a potential treatment for chronic acid reflux esophagitis.

• The Korean Journal of Franchise Management
• /
• v.13 no.2
• /
• pp.17-31
• /
• 2022

Purpose: With the development of the Internet, consumers can quickly access the electronic word-of-mouth. Consumers seek to reduce uncertainty by referring to the opinions of other consumers about products and services when making purchase decisions. In the food service industry, evaluating a restaurant before an actual visitation is difficult. Therefore, electronic word-of-mouth is important to interact with the customer in restaurants. as it can be used as an exchange of information in which consumers participate and interact with other customers. This study was conducted to verify how online word-of-mouth characteristics (Consensus, Vividness, Neutrality) on attitudes and visit intention from the perspective of social exchange theory. And it was performed to verify the structural relationship between short-term visit intention, mid-term visit and long-term visit intention. Research design, data, and methodology: A survey was conducted on customers who have visited restaurants. Of a total of 312 responses, 306 responses were used, excluding insincere responses and missing values for factors analysis. SPSS 25.0 and AMOS 25.0 were used for statistical analysis, and hypothesis testing was conducted after verifying the validity and reliability of the questionnaire items. Result: The result of the analysis showed that, consensus and neutrality have a positive effect on attitude but not much on vividness. In addition, consensus, vividness, and neutrality have no effect on the short-term visit intention. Finally, the short-term visit intention has a positive effect on mid-term visit intention, and mid-term visit intention has a positive effect on long-term visit intention. Conclusions: Based on the results, this study suggested that it is necessary to have practical implications for marketing and monitoring restaurant reviews in consideration of the characteristics of electronic word-of-mouth. When managing electronic-word-of-mouth, it is necessary to manage the consensus and neutrality is essential to provide sufficient information about the restaurant. The focus should not only be on vividness, such as photos and videos. In addition, restaurants should also provide a good experience for first-time visitors as the short-term visit intention positively affects mid-term and long-term visit intention.

• Journal of Digital Convergence
• /
• v.20 no.2
• /
• pp.289-297
• /
• 2022

The purpose of this study was to investigate the perception of dental students based on their experiences of online classes after taking non-face-to-face education courses for all the school semesters in 2020. For the research method, an online survey was conducted on A survey was conducted on 161 dental students enrolled in A University. The analytical method was conducted through frequency analysis, correlation analysis, and multiple regression analysis. The survey analysis findings showed that the satisfaction of dental students' about the non-face-to-face education course was above 4.2, and the detailed items were in the order of the appropriateness of the attendance processing method, satisfaction with recorded video lectures, and the assessment method of the course grade. In the case of the factors that affect the satisfaction of non-face-to-face education courses, the learning system and assessment method were statistically significant. The online class type that is most preferred by the students is recorded video lectures, and the highest number of participants chose 21~30 minutes as the appropriate time for the class content. It is considered that the application of the online system will continue to be used together with face-to-face education courses in the education site and various university-level efforts like systematic support are required to achieve effective learning achievements. This study only investigated the non-face-to-face education operation conditions of A University, so it cannot be generalized to all universities, but it can be used as basic data to provide education curriculum design and supportive measures for the compatibility of face-to-face and non-face-to-face courses.

• 지역과문화
• /
• v.8 no.3
• /
• pp.27-48
• /
• 2021

In recent years, China's tourism performing art in a series of new completion of the project, increase the box office of tourism performing arts industry, higher economic income, at the same time led to the formation of brand of tourism performing arts and has a good reputation, with the regional culture, has a certain role in promoting economic development, including Large scenario experience drama is one of the key projects. Large scenario experience drama is a new form of drama that simulates the space design of real environment and enables the audience to have active experience in visual, auditory, smell, taste, touch and other senses with strong interactivity.Large scenario experience drama are adapted from traditional Chinese culture, regional culture and long-passed stories, and combine high technology such as lighting, sound effects, special effects and 3D effects to make the audience's experience more real.As the first Large scenario experience drama in China, 'You Jian Ping-yao' reflects the profound culture of Shanxi with new forms of expression and creative means, in the form of scene experience and make the audience more intuitive feel the 'Shanxi emotion', 'Shanxi sentiment' and 'Shanxi Morality', carry forward the traditional culture at the same time, also passed the Shanxi ancient and great values, strengthened the drama of China's movie village, impetus the development of the tourism industry in Shanxi, drive the Shanxi region of jingjing, gradually formed a complete industrial chain. However, there are also limitations such as improper plot connection and improper tourist management, which can improve the performance effect through more audience interaction and guidance. Therefore, it can be seen that large-scale situational experience dramas play a great role in promoting the dissemination of traditional culture and values, the development of tourism industry, the formation of regional brand characteristics and economic development. Through these, it can be seen that large-scale situational experience plays have enlightenments such as innovative thinking content, gradually forming an industrial chain closed-loop, and broadening publicity channels for the development of live-action performances.