• The Journal of Korean Institute of Information Technology
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• v.15 no.12
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• pp.181-188
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• 2017

As a population of leisure activities grows and diversifies, there is a great demand for portable and environment-friendly power generation systems. A small wind power generation system is emerging as a suitable power generation equipment to meet these needs. The most important thing when developing a small portable wind turbine is to reduce the weight of the generator and increase the efficiency. The existing 300W wind turbine generator weighs about 10kg, which is heavy to carry. Therefore, a new generator weighing less than 4kg to make it easy to carry with high efficiency has been developed. In addition, considering complicated characteristics of wind volume and topography of Korea, a small wind turbine that can be used in urban and rural areas individually was constructed. Through basic designing and optimization, the lightweight and efficient generator was manufactured. It is a 300W wind turbine designed and fabricated with reduced weight as a prototype. The average output voltage of the generator was 24.7V at 900rpm no-load test. On a load test with the average line voltage 36.8V and the average phase current 2.62A, when the mechanical input was 339.84W, an average voltage output of the generator was measured as 289.5W with efficiency of 85.18%. The generator weight was 3.84kg.

• Nuclear Engineering and Technology
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• v.53 no.9
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• pp.3068-3084
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• 2021

Investigations of large commercial aircraft impact effect on nuclear power plant (NPP) buildings have been drawing extensive attentions, particularly after the 9/11 event, and this paper aims to experimentally assess the damage and vibrations of NPP buildings subjected to aircraft crash. In present Part I, two shots of reduce-scaled model test of aircraft impacting on NPP building were carried out. Firstly, the 1:15 aircraft model (weighs 135 kg) and RC NPP model (weighs about 70 t) are designed and prepared. Then, based on the large rocket sled loading test platform, the aircraft models were accelerated to impact perpendicularly on the two sides of NPP model, i.e., containment and auxiliary buildings, with a velocity of about 170 m/s. The strain-time histories of rebars within the impact area and acceleration-time histories of each floor of NPP model are derived from the pre-arranged twenty-one strain gauges and twenty tri-axial accelerometers, and the whole impact processes were recorded by three high-speed cameras. The local penetration and perforation failure modes occurred respectively in the collision scenarios of containment and auxiliary buildings, and some suggestions for the NPP design are given. The maximum acceleration in the 1:15 scaled tests is 1785.73 g, and thus the corresponding maximum resultant acceleration in a prototype impact might be about 119 g, which poses a potential threat to the nuclear equipment. Furthermore, it was found that the nonlinear decrease of vibrations along the height was well reflected by the variations of both the maximum resultant vibrations and Cumulative Absolute Velocity (CAV). The present experimental work on the damage and dynamic responses of NPP structure under aircraft impact is firstly presented, which could provide a benchmark basis for further safety assessments of prototype NPP structure as well as inner systems and components against aircraft crash.

• Journal of the Korea Convergence Society
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• v.12 no.12
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• pp.145-151
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• 2021

This study aimed to investigate the efficient conduct of HA coating on Ti Gr4 for the practical use of medical device. Ti Gr4 alloy specimens measuring 𝜱 25mm × 1mm were sprayed with hydroxyapatite using thermal spray according to ASTM F1185-88. The surface was evaluated at #120, #400, #1,000 sandpaper and barrel finishing. Each coating properties was analyzed using SEM, UTS 20,000psi cap. and in vitro cytotoxicity. Surface morphology consists of well molten particles with very little resolidified or unmolten areas. The average Ca/P ratio is 1.74 which is in good agreement with theoretical value of 1.67. The average roughness Ra is very representative of roughness of specimen. The coatings are dense and well adhered to the substrate. The average bond strength was 61.74 MPa with a standard deviation of 4.06 which indicates fairly reliable results for ASTM 633 type tests. Variations in results from jig design, epoxy used, crosshead speeds etc. in vitro cytotoxicity result had a Grade 3. The results of the study are expected to be helpful in osseointegration and plasma-spray HA coated Ti Gr4 are more satisfactory in HA coating thickness elevation which is preferable to any other system.

• Journal of Wetlands Research
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• v.23 no.4
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• pp.307-316
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• 2021

Due to rapidly increased urbanization, impervious area has been extended and concerns about urban flooding has been increased as well. A lot of effort has been made to restore the urban water circulation. Low Impact Development (LID) technology that consist of retention, infiltration, and evapotranspiration has begun to attract attention to simulate the hydrologic phenomenon before and after development. Many researches on the technique is being actively conducted. In this study, the effect on reducing runoff in urban catchment was analyzed and evaluated by applying LID techniques using SWMM and six scenarios. A SWMM-LID model was built for the Gasan 1 rainwater pumping station basin, and Green Roof and Permeable Pavement were selected as LID techniques to be applied. As a result, the reduction effect of the permeable pavement was larger than green roof. In the future, the results could be used to design a LID facility using the characteristics of the watershed, and other urban water resource factors such as river and groundwater levels that affect each other should be considered, so that the entire system can be considered.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.5
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• pp.279-286
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• 2021

In this study, we investigated the behavior characteristics of the L-type flange bolt connection, which is used to connect upper and lower flanges having L-type ring sections, by bolts. This connection is mainly used in domestic wind turbine structures, wherein it is a vital component as any imperfection could cause the collapse of the entire structural system. Therefore, understanding the behavior characteristics of the L-type flange bolt connection is imperative. In this study, the connection's response to external force was simulated using finite element (FE) analysis and the FE model was idealized to behave as a single L-type bolt flange. The variation in the bolt tension and the L-type flange stress were analyzed to understand the behavior characteristics of the connection. Moreover, the bolt-load function models proposed by Petersen, Schmidt/Neuper and VDI 2230, theoretically expressing a relation between bolt tension and external force, were compared to evaluate the suitability of the FE analysis and analyze the significant behavior characteristics of the connection. Furthermore, the changes in the bolt-load curve due to the variations in the partial dimensions of the L-type flange bolt connection were analyzed.

• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.5
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• pp.325-337
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• 2021

On the road and rail tunnels, the evacuation pathway and facilities such as smoke-control and fire suppression system are essential in tunnel fire. In the long twin tunnels, the cross-connection tunnel is usually designed to evacuate from the tunnel where the fire broke out to the other tunnel. In twin shield tunnels, the segment lining has to be demolished to construct the cross-connection tunnel. Considering the modern shield TBM is mostly the closed chamber type, the exposure of underground soil induced by removal of steel segment lining is the most danger construction step in the shield tunnel construction. This case study introduces the excavation method using the thrust of large steel pipe and reviews the measured data after the construction. The large steel pipe thrust method for the cross-connection tunnel can stabilize the excavated face with the two mechanisms. Firstly, the soil in front of excavated face is cylindrically pre-supported by the large steel pipe. Secondly, the excavated face is supported by the plugging effect caused by the soil pressed into the steel pipe. It was reviewed that the large steel pipe thrust method in the cross-connection tunnel is enough to secure the construct ability and stability in soil from the measurement results about the deformation and stress of steel pipe.

• Journal of the Korean Institute of Gas
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• v.25 no.4
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• pp.10-18
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• 2021

CO₂ storage technology in an aquifer is one of the most effective way to decrease global warming due to a high storage capacity and economics. A demonstration-scale offshore CO₂ storage project was performed in a geological deep aquifer in the Pohang Basin, Korea for a technological development of large-scale CO₂ storage. A challenging issue in the early design stage of the project was to establish the proper injectivity during CO₂ injection. To solve this issue, injection conditions were calculated by calculating injection rate, pressure, temperature, CO₂ phase change, and thermodynamic properties. For this study, we simulated and numerically analyzed CO₂ phase change from gas to supercritical phase and flow behavior in transport piping and injection tubing using OLGA program. Our results provide the injectivity conditions of CO₂ injection system combined with a bottomhole pressure of an aquifer.

• Journal of Korea Trade
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• v.23 no.3
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• pp.68-83
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• 2019

Purpose - The UNCITRAL Model Law on Electronic Transferable Records (Model Law) is based on the principles of non-discrimination against the use of electronic means, functional equivalence, and technology neutrality underpinning all UNCITRAL texts on electronic commerce. Investigating the disagreements between the Model Law and the Koran Commercial Act (KC Act), including the B/L Regulation, and suggesting the revision of the KC Act including the B/L Regulation, could be a valuable study. The purpose of this paper is to contribute to the harmonization of Korean legislation regarding electronic bill of lading in compliance with the Model Law. Design/methodology - The Model Law is flexible to accommodate the use of all technologies and models, such as registries, tokens, and distributed ledgers: that is, blockchain. In 2007, the KC Act was revised to regulate electronic bills of lading to promote the widespread legal use of electronic bills of lading. In addition, The Regulation on Implementation of the Provisions of the Commercial Act Regarding Electronic Bills of Lading (the B/L Regulation) was enacted to regulate the detailed procedures in using electronic bills of lading in 2008. This paper employs a legal analysis by which this paper does find differences between two rules in light of technology neutrality and global standard of electronic bills of lading model. Findings - The main findings are as follows: i) the Korean registry agency has characteristics of a closed system. ii) The KC Act has no provision regarding control. iii) The KC Act discriminates other electronic bills of lading on the ground that it was issued or used abroad. Moreover, this study does comprehensive analysis of Korean Acts in comparison with the Model Law and, in particular, this study analyzes the differences between the KC Act and the Model Law by comparing article by article in view of the harmonization of the two rules. Originality/value - The subject of previous several studies was draft provisions on Electronic Transferable Records before completion of the Model Law; thus, these studies did not take into consideration the character of the Model Law as the Model Law was chosen at the final stage of legislation. This study is aimed at the final version of the Model Law. So, this study is meaningful by finding the suggestion and directions for the Korean government to revise the KC Act and the B/L Regulation in line with the Model Law.

• Journal of Korea Trade
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• v.25 no.7
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• pp.92-107
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• 2021

Purpose - This paper analyzes the relationship between trade facilitation and agricultural products exports and estimates the effects of trade facilitation in importing countries on Chinese agricultural products exports, which is of great significance for promoting agricultural trade between China,Japan and Korea and the governments of the three countries to formulate targeted trade facilitation policies. Design/methodology - Based on Wilson (2003) theoretical framework, this paper sets up its own trade facilitation level measurement system by involving four primary indicators and fifteen secondary indicators to evaluate the trade facilitation levels of Japan and Korea from 2011 to 2018 respectively. The paper selected the data on China's agricultural exports at the HS4 level from 2011-2018 and used a fixed-effects model to estimate the effect of changes in trade facilitation levels in trading partner countries on China's agricultural trade. Findings - Our main findings can be summarized as follows: the level of trade facilitation in importing countries has a significantly positive effect on China's agricultural exports. The higher the level of trade facilitation in trading partner countries, the more Chinese agricultural exports trade, i.e. for every 1 percentage point increase in the level of trade facilitation, the volume of exports will increase by 2.299%.The sub-sample test shows that China's main agricultural products exported to Japan and Korea, such as aquatic products, vegetables, fruits and other perishable fresh products, are particularly significantly affected by the level of trade facilitation. Originality/value - First, from the innovation of the research perspective, which is different from the analysis of the existing paper on the overall trade facilitation of all traded commodities. This article is based on the close trade relations between China, Japan and Korea, and the particularity of agricultural products, from the perspective of China's agricultural exports to Japan and Korea, discuss the impact of importing countries-Japan and Korea's trade facilitation levels on China's agricultural exports;Secondly, in this paper, the hierarchical data of the HS4 quartile is used to avoid the information loss of the industry, and to analyse the impact of the importing country's trade facilitation level on the export of different types of agricultural products more scientifically.

• Journal of Animal Science and Technology
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• v.63 no.6
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• pp.1314-1327
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• 2021

Bacillus is characterized by the formation of spores in harsh environments, which makes it suitable for use as a probiotic for feed because of thermostability and high survival rate, even under long-term storage. This study was conducted to investigate the effects of Bacillus-based probiotics on growth performance, nutrient digestibility, intestinal morphology, immune response, and intestinal microbiota of weaned pigs. A total of 40 weaned pigs (7.01 ± 0.86 kg body weight [BW]; 28 d old) were randomly assigned to two treatments (4 pigs/pen; 5 replicates/treatment) in a randomized complete block design (block = BW and sex). The dietary treatment was either a typical nursery diet based on corn and soybean meal (CON) or CON supplemented with 0.01% probiotics containing a mixture of Bacillus subtilis and Bacillus licheniformis (PRO). Fecal samples were collected daily by rectal palpation for the last 3 days after a 4-day adaptation. Blood, ileal digesta, and intestinal tissue samples were collected from one pig in each pen at the respective time points. The PRO group did not affect the feed efficiency, but the average daily gain was significantly improved (p < 0.05). The PRO group showed a trend of improved crude protein digestibility (p < 0.10). The serum transforming growth factor-β1 level tended to be higher (p < 0.10) in the PRO group on days 7 and 14. There was no difference in phylum level of the intestinal microbiota, but there were differences in genus composition and proportions. However, β-diversity analysis showed no statistical differences between the CON and the PRO groups. Taken together, Bacillus-based probiotics had beneficial effects on the growth performance, immune system, and intestinal microbiota of weaned pigs, suggesting that Bacillus can be utilized as a functional probiotic for weaned pigs.