• Journal of the Korean Institute of Gas
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• v.22 no.6
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• pp.44-51
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• 2018

As the LNG storage tank is aged, if there is a crack in the outer wall concrete or corrosion of the reinforcing steel, there is a risk of a major accident such as collapse of the structure depending on the type and degree of damage. Since 2014, LNG storage tanks have undergone precise safety diagnosis and safety inspection has been carried out. The condition evaluation criteria for each component have been revised and applied in January 2016. The condition evaluation standard is to evaluate the status of storage tanks based on the appearance survey and material test results of LNG storage tanks and it is important for maintenance. In addition, the representative condition evaluation standard that shows the comprehensive state of each LNG storage tank is important in maintenance, but the related standard for LNG storage tank outer concrete is not available in Korea and abroad, and development of the condition evaluation standard is necessary. In this paper, we examined the structural characteristics of LNG storage tanks, analyzed the status of the condition evaluation criteria for each member, and developed a comprehensive status rating system by weighting the members. We used the AHP(Analytic Hierarchy Process) technique and developed a representative conditon evaluation criteria through surveys of professional organizations.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.12
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• pp.265-271
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• 2018

This paper presents a method for detecting damage to a structure at low cost using its impedance. The impedance technique is a typical method to detect local damage for structural health monitoring. This is a common technique for estimating damage by monitoring the electro-mechanical admittance signal of the structure. To apply this technique, an expensive impedance analyzer is generally used. On the other hand, it is necessary to develop a low-cost variant to effectively disseminate the technique. In this study, a method based on the transfer impedance using a function generator and digital multimeter, which are generally used in the laboratory instead of an impedance analyzer, was developed. That is, this technique estimates the damage by comparing the damage index using the amplitude ratio of the output voltage measured in the healthy and damaged state. A transfer impedance test was carried out on a steel specimen. By comparing the damage index, the presence of damage could be assessed reasonably. This study is a basic investigation of an impedance-based low-cost damage detection method that can be used effectively for structural health monitoring if supplemented with future research to estimate the damage location and severity.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.3
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• pp.55-63
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• 2022

A modular underground arch structure using steel and concrete has been proposed as a structure that has a simple construction process and can effectively resist cross-sectional forces generated during construction and use. Structural behavior of modular underground arch was evaluated about span length less than 15m through 3D structural analysis and test. In general, 2D and 3D structural analysis methods may be applied for structural analysis such as underground arch and tunnels. However, if a 2D or 3D structural analysis method is applied to evaluate the structural safety of a modular underground arch structure, it is difficult to model for structural analysis and it may take an excessively long time to interpret. Therefore, it may not be reasonable as a structural analysis method for considering the structural safety and earth pressure in the design process of a modular underground arch structure. In addition, when a modular underground arch structure is configured for span lengths to which the predetermined cross-section is applicable, it may be reasonable to evaluate only the safety of the structure and cross-section according to the cross-section and load conditions. Therefore, in this study, a structural analysis model using frame elements was proposed for efficient structural safety evaluation. In addition, structural analysis results of the 2D structural analysis model and the simplified analysis model using frame elements were compared, and the structural safety of the modular underground arch structure for a span length of 20m was evaluated with a simplified analysis method.

• Journal of Korea Port Economic Association
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• v.38 no.4
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• pp.199-214
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• 2022

A relative important analysis was conducted to determine what factors are required for port selection in Mokpo New Port and what needs to be addressed first in order to expand automobile and steel cargo handling. The port selection factors of Mokpo New Port were classified into 4 major and 13 intermediate categories, and AHP analysis was used. As a result, items such as 'port facilities', 'accessibility to international ports', 'port facility usage fees', and 'connectivity with neighboring cities/ports' were evaluated as important. The respondent groups were divided into shipowner and shipper, port operator and stevedore, and public official, and an analysis of variance (ANOVA) was conducted to verify if there was a difference in perception between the groups. As a result, shipowner and shipper, port operator and stevedore were similar, but there was a difference from public official group. Shipowner and shipper, port operator and stevedore with similar response characteristics were classified into the 'port practitioner' group, and public official were classified into the 'port policy maker' group, and the difference in perception between the group was tested. Therefore, there were differences in some major category items, and even in the intermediate category items such as 'possession of adjacent hinterland industrial complex', 'cargo equipment', '24-hour port operation', 'inland transportation cost', 'accessibility to international ports', 'marketing and incentives' with statistical. In other words, the 'port practitioner' group evaluated items that can increase cargo creation and handling productivity as important whereas the 'port policy maker' group considers port development and policies such as port infrastructure, connectivity with other ports, and incentive support items are more important.

• Journal of Korean Tunnelling and Underground Space Association
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• v.25 no.2
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• pp.43-63
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• 2023

With the concentration of the population in the city center and the saturation of the structures on the ground, the development of the underground structures becomes important and the construction of an adjoining tunnel that can reduce the overall problems is respected. In addition, it is necessary to apply the reinforcement construction method for the pillar part of the adjacent tunnel that can secure stability, economy and workability of the site. In this study, the tunnel pillar reinforcement method using prestress and grouting was reviewed. There are various reinforcement methods that can compensate for the problems of the side tunnel, but as the tunnel pillar construction method using prestress and grouting is judged to be excellent in field applicability, stability and economic feasibility, theoretical and numerical analysis of the actual behavior mechanism are conducted. Numerical analysis is divided into PC stranded wire + steel pipe reinforcement grouting + prestress (Case 1), pillar part tie bolt reinforcement (Case 2), pillar part non-reinforcement (Case 3) under the same ground conditions, and the maximum value of the celling displacement, internal displacement, and member force, the stability was confirmed. Through numerical analysis, it was confirmed that Case 1 which reinforced the PC stranded wire, was the best construction method and if it is verified and supplemented through field experiments later, it will be possible to derive superior results in terms of displacement control and member force than the currently applied reinforcement method was judged.

• Korean Journal of Construction Engineering and Management
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• v.25 no.1
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• pp.62-72
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• 2024

Due to the distribution structure of domestic temporary equipment, quality control of temporary equipment is essential because more than 80% of temporary equipment is repeated and reused. Due to this importance, the Ministry of Land, Infrastructure and Transport has proposed quality management standards for temporary equipment for 10types of temporary equipments, including steel pipe support, but the overall quality of temporary eqipment cannot be confirmed because the quality is managed through sampling quality tests. In addition, although quality control standards exist for temporary material rental company, practical utilization was investigated and analyzed to be very low as they are mainly presented based on qualitative inspection standards by visual inspection. Therefore, the purpose of this study is to develop individual temporary material/quality/delivery management standards (Guides) for temporary equipment rental company to preemptively secure the quality of temporary equipment before bringing them into the construction site. If the standards developed through this study are applied to domestic temporary equipment rental companies, it is expected that high-quality temporary equipment with secured quality will be brought into the construction site as the quality of temporary equipment quality of domestic medium and small temporary equipment rental companies is improved safety accidents related to temporary structures.

• Computers and Concrete
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• v.33 no.5
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• pp.497-507
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• 2024

In squat reinforced concrete walls, the displacement capacity for lateral deformation is low and the ability to resist the axial load can quickly be lost, generating collapse. This work consists of testing two squat reinforced concrete walls. One of the specimens is built with conventional detailing of reinforced concrete walls, while the second specimen is built applying an alternative design, including stirrups along the diagonal of the wall to improve its ductility. This solution differs from the detailing of beams or coupling elements that suggest building elements equivalent to columns located diagonally in the element. The dimensions of both specimens correspond to a wall with a low aspect ratio (1:1), where the height and length of the specimen are 1.4 m, with a thickness of 120 mm. The alternative wall included stirrups placed diagonally covering approximately 25% of the diagonal strut of the wall with alternative detailing. The walls were tested under a constant axial load of 0.1f'cAg and a cyclic lateral displacement was applied in the upper part of the wall. The results indicate that the lateral strength is almost identical between both specimens. On the other hand, the lateral displacement capacity increased by 25% with the alternative detailing, but it was also able to maintain the 3 complete hysteretic cycles up to a drift of 2.5%, reaching longitudinal reinforcement fracture, while the base specimen only reached the first cycle of 2% with rapid degradation due to failure of the diagonal compression strut. The alternative design also allows 46% more energy dissipation than the conventional design. A model was used to capture the global response, correctly representing the observed behavior. A parametric study with the model, varying the reinforcement amount and aspect ratio, was performed, indicating that the effectiveness of the alternative detailing can double de drift capacity for the case with a low aspect ratio (1.1) and a large longitudinal steel amount (1% in the web, 5% in the boundary), which decreases with lower amounts of longitudinal reinforcement and with the increment of aspect ratio, indicating that the alternative detailing approach is reasonable for walls with an aspect ratio up to 2, especially if the amount of longitudinal reinforcement is high.

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.11
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• pp.1548-1555
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• 2011

Persimmons are shown to contain high levels of phenolics. The present study was designed to investigate if a sweet persimmon wine (SPW) would affect the development of alcoholic fatty liver in rats. Initially, male Sprague-Dawley rats were housed singly in stainless steel wire-bottomed cages in a room of controlled temperature and lighting. The rats had free access to a nutritionally adequate AIN-93G diet and deionized water. After the acclimatization period, rats were weight-matched and assigned to the following three groups: two groups were fed 6.7% ethanol or the caloric equivalent of maltose-dextrin in a Lieber-DeCarli diet and the other group was fed the isocaloric Lieber-DeCarli diet containing SPW at the same ethanol level. All three groups were fed their respective diets for 6 weeks. Serum transaminase, cholesterol, and triglyceride levels were measured. Liver lipids and histology were assessed at 6 weeks. The total phenolic content and the antioxidant and free radical scavenging activities of SPW were determined. SPW significantly increased antioxidant and free radical scavenging activities. As markers of liver injury, serum alanine and aspartate transminases were markedly lowered by SPW at 6 weeks. SPW significantly reduced the serum levels of serum cholesterol and triglyceride compared to ethanol treatment. SPW delayed the development of an alcoholic fatty liver by reversing fat accumulation in the liver, as evidenced in histological observations. Taken together, SPW seems to protect the liver from becoming fatty by alleviating fatty liver symptoms and lowering hepatic and serum lipid levels. Such a protective effect of SPW appears to be in part due to its phenolics.

• Journal of The Korean Society of Grassland and Forage Science
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• v.27 no.1
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• pp.21-28
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• 2007

This study was conducted to investigate the effects of the degree of slope according to cattle slurry (CS) application on productivity of herbage yield and nutrients runoff in mixed grassland. silage corn and environmental pollution in silage corn cultivation soil. Field study was conducted on the steel-made erosion apparatuses which consisted of various degree of slope, such as 0%, 8.75% and 17.50%, Dry matter yield and N yield of forages decreased as the degree of the slope increased, whereas N contents increased as the degree of slope increased. $NO_3-N$ and $PO_4-P$ concentrations from the surface run-off significantly elevated by increasing the slope during the experimental period (P<0.05). However, $NO_3-N$ and $PO_4-P$ concentrations $PO_4-P$ content from the surface run-off by application of CS maintained a low levels during the experimental period. In conclusion, com productivity and nutrient losses from run-off are significantly affected by heavy rainfall on the sloping land. The results of this study suggest that CS application in the sloping land can be an important source of pollution for surface water if intensity rainfall takes place within a short period.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.11 no.4
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• pp.233-238
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• 1978

Rainbow trout were reared in a stainless steel aquarium from Nov. 11, 1977 to June 12, 1978, and the following results were obtained : 1. The volume of water was about $400\iota$ in a aquarium measuring $1m\;(Length)\times1m\;(Width)\times67cm(Height)$ and water depth 40 cm. Water was supplied for about 16 hours daily at a rate $3\iota/min$ and was drained through the conical settling part in the middle of the aquarium bottom. Filter tank was about $23cm(W)\times23cm(L)\times40cm(D)$ and contained pebbles 30 cm in depth. Water recirculation rate was at)out $1,030\iota/hr$, or 2.6 turn-over per hour. 2. During the first period (77 days), the trout grew from 88.3g to 229g in average, the total weight attaining 30.7kg. The food coefficient was 1.249, average daily increment 243.3g, average daily growth rate 1.245%, and the mortality was 2 smallest fish weighing 53 g, owing to unknown reason. During the second period (135 days), the trout grew from 239g to 555g in average, the total weight attaining 57.2 kg. The food coefficient was 1.447, average daily increment 279.8g, average daily growth rate $0.65\%$ and the mortality was 31 fish weighing 11,255 g, owing partly to miss-handling and partly to disease. 3. The feed consisting of fully domestic materials was prepared in this laboratory, and the feed conversion was not inferior to high protein commercial feed available in foreign countries. 4. The result of whole period for 212 days was 56.5 kg in gross increment, and based on this result, when $1\iota/min$ full day inflowing water available, the net production will become 28.25 kg. So, if a 5000kg production is planned, $180\iota/min$ or about $10.8m^3/hr$ be reauired, and the production in value frill become 15million won at local price at the expense of about 5.3 million won. From the result of this experiment, rainbow trout is feasible for commercial production in Korea with relatively small amount of well water and simplified water recirculation system.