• Journal of the Computational Structural Engineering Institute of Korea
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• v.32 no.5
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• pp.313-322
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• 2019

Recently, there have been frequent occurrences of bridge fires. Fires in cable-supported bridges can damage and brake cables due to high temperatures. In this study, fire scenarios that can occur on cable-supported bridges were set up. In addition, based on the results of vehicle fire tests, a fire intensity model was proposed and cable heat transfer analyses were performed on a target bridge. The analyses results demonstrated that temperature rises were identified on cables with a smaller cross-sectional area. Furthermore, vehicles other than tankers did not exceed the fire resistance criteria. When the tanker fire occurred on a bridge shoulder, the minimum diameter cable exceeded the fire resistance criteria; the height of the cable exceeding the fire resistance criteria was approximately 14 m from the surface. Therefore, the necessity of countermeasures and reinforcements of fire resistance was established. The results of this study confirmed that indirect evaluation of the temperature changes of bridge cables under fire is possible, and it was deemed necessary to further study the heat transfer analysis considering wind effects and the serviceability of the bridge when the cable temperature rises due to fire.

• The Journal of Korean Obstetrics and Gynecology
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• v.27 no.1
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• pp.41-64
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• 2014

Objectives: This study was to evaluate the effect of Jaeumkanghwa-tang (JEKHT) on the propylthiouracil (PTU)-induced rat hypothyroidism. Methods: Six groups, each of 8 rats per group were used in the present study - intact vehicle control, PTU control, Levothyroxine ($LT_4$), JEKHT 500, 250 and 125 mg/kg treated groups. JEKHT were administered once a day for 42 days as an oral dose of 500, 250 and 125 mg/kg, and hypothyroidism was induced by daily subcutaneous treatment of PTU 10 mg/kg for 28 days. The changes on the body and organ weight, serum hormone and lipid profiles, liver and testis antioxidant defense factors were observed with histopathology of organs. Results were compared with $LT_4$ 0.5 mg/kg intraperitoneally treated rats in this experiment. Results: PTU treatment, marked decrease of body weight, increases of thyroid weight, decreases of liver, testis, epididymis and prostate weights, decreases of serum Tri-iodothyronine ($T_3$), and Thyroxine ($T_4$) level with increase of serum Thyroid-stimulating hormone (TSH) level, decreases of serum testosterone and dihydrotestosterone (DHT) level with increases of serum Follicular stimulating hormone (FSH) level, increases of serum High density lipoprotein (HDL), decrease of triglyceride content, increase of serum Aspartate aminotransferase (AST) level, decreases of liver and testis antioxidant defense factors were observed. In addition, marked hyperplasia of follicular cells with decreases of follicular colloid contents and diameters was additionally demonstrated with the decrease of hepatocyte numbers per unit area due to hypertrophy of hepatocytes related to lipid droplet depositions, increase of a/oligospermatic epididymal tubules with epididymal atrophic changes, seminiferous tubular atrophy with decrease of stage I~II seminiferous tubules in testis, prostate tubular atrophic changes at histopathological inspections. However, these PTU induced hypothyroidism and related hepatic and male reproductive organ damages were favorably and dose-dependently inhibited by treatment of JEKHT 500, 250 and 125 mg/kg, and JEKHT also effectively regulated the PTU-induced abnormal antioxidant defense factor changes in the both liver and testis. Conclusions: JEKHT 500, 250 and 125 mg/kg dose-dependently inhibited PTU-induced hypothyroidism and related liver and male reproductive organ damages in rats.

• Korean Journal of Remote Sensing
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• v.37 no.6_1
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• pp.1731-1738
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• 2021

The objective of this study was to extract individual trees and tree heights using UAV drone images. The study site was Gongju national university experiment forest, located in Yesan-gun, Chungcheongnam-do. The thinning intensity study sites consisted of 40% thinning, 20% thinning, 10% thinning and control. The image was filmed by using the "Mavic Pro 2" model of DJI company, and the altitude of the photo shoot was set at 80% of the overlay between 180m pictures. In order to prevent image distortion, a ground reference point was installed and the end lap and side lap were set to 80%. Tree heights were extracted using Digital Surface Model (DSM) and Digital Terrain Model (DTM), and individual trees were split and extracted using object-based analysis. As a result of individual tree extraction, thinning 40% stands showed the highest extraction rate of 109.1%, while thinning 20% showed 87.1%, thinning 10% showed 63.5%, and control sites showed 56.0% of accuracy. As a result of tree height extraction, thinning 40% showed 1.43m error compared with field survey data, while thinning 20% showed 1.73 m, thinning 10% showed 1.88 m, and control sites showed the largest error of 2.22 m.

• Journal of Aerospace System Engineering
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• v.15 no.5
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• pp.24-32
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• 2021

Personal Air Vehicle (PAV), Cargo UAS (Cargo UAS), and existing manned and unmanned aircraft are key vehicles for urban air mobility (UAM), and should demonstrate compatibility for the design of aircraft systems. The safety assessment required by for certification to ensure safety and reliability should be systematically performed throughout the entire cycle from the beginning of the aircraft development process. However, with the increasing complexity of safety critical aviation systems and the application of state-of-the-art systems, conventional experience-based and procedural-based safety evaluation methods make ir difficult to objectively assess safety requirements and system safety. Therefore, Model-Based Safety Assessment (MBSA) using modeling and simulation techniques is actively being studied at domestic and foreign countries to address these problems. In this paper, we propose a Model-Based Safety Evaluation framework utilizing modeling and simulation-based integrated flight simulators. Our case studies on the Traffic Collision Availability System (TCAS) and Wheel Brake System (WBS) confirmed that they are practical for future safety assessments.

• Laboraroty Animal Research
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• v.34 no.4
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• pp.239-247
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• 2018

Bacopa monnieri is a medicinal plant with a long history of use in Ayurveda, especially in the treatment of poor memory and cognitive deficits. In the present study, we hypothesized that Bacopa monnieri extract (BME) can improve memory via increased cell proliferation and neuroblast differentiation in the dentate gyrus. BME was administered to 7-week-old mice once a day for 4 weeks and a novel object recognition memory test was performed. Thereafter, the mice were euthanized followed by immunohistochemistry analysis for Ki67, doublecortin (DCX), and phosphorylated cAMP response element-binding protein (CREB), and western blot analysis of brain-derived neurotrophic factor (BDNF). BME-treated mice showed moderate increases in the exploration of new objects when compared with that of familiar objects, leading to a significant higher discrimination index compared with vehicle-treated mice. Ki67 and DCX immunohistochemistry showed a facilitation of cell proliferation and neuroblast differentiation following the administration of BME in the dentate gyrus. In addition, administration of BME significantly elevated the BDNF protein expression in the hippocampal dentate gyrus, and increased CREB phosphorylation in the dentate gyrus. These data suggest that BME improves novel object recognition by increasing the cell proliferation and neuroblast differentiation in the dentate gyrus, and this may be closely related to elevated levels of BDNF and CREB phosphorylation in the dentate gyrus.

• Journal of Hydrogen and New Energy
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• v.30 no.1
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• pp.76-82
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• 2019

This study was investigate the characteristics of GHGs ($CO_2$, $CH_4$, and $N_2O$) emissions of diesel medium duty trucks according to their various driving modes. GHGs emissions decreased as vehicle speed increased, and emissions increased after 64.7 km/h. The 4.5 ton trucks show higher values of $CO_2$, $CH_4$, $N_2O$, 35%, 25%, and 57%, respectively, comparing of the 2.5 ton trucks. Also, $CO_2$ emissions under WHVC mode were 20% lower than those under the NEDC mode. In the case of cold start condition, $CO_2$ emissions were 12-13% higher than those for hot start condition. In the future, the result of present study will provide basic data to set up GHGs emission standards for medium and heavy duty vehicles.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.32 no.1
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• pp.1-5
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• 2019

In this paper, the experimental study and finite elements analysis were conducted on homogeneous and dissimilar metals single lap-shear bonded joints to investigate the factor that affect the joint failure load. It was found that factors which have the significant effects on the failure load of the joint was stiffness of the adherends. And from experimental results, it can be confirmed that the failure load increases linearly with overlap length increases. And the failure load of dissimilar metal joints is approximately 1KN(10~17%) larger than homogeneous metal joints. In order to confirm this phenomenon, the stress distribution and strain distribution of the specimens were analyzed through the finite element analysis. The difference between homogeneous metals joints and dissimilar metals joints is that stress and strain in adhesive are concentrated at the end of the overlap zone close to aluminium which has lower rigidity than aluminium in case of dissimilar metals joints. From high rigidity of steel, the stress concentration in bonds are decreased and it cause increase of the failure strength at dissimilar metal joints.

• Journal of Convergence for Information Technology
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• v.9 no.9
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• pp.13-19
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• 2019

This paper analyzed the SCMS and pilot policy, which is pursued by the U.S. government in connected vehicles. SCMS ensures authentication, integrity, privacy and interoperability. The SCMS Support Committee of U.S. government has established the National Unit SCMS and is responsible for system-wide control. Of course, it introduces security policy, procedures and training programs making. In this paper, the need for SCMS to be applied to C-ITS was discussed. The structure of the SCMS was analyzed and the U.S. government's filot policy for connected vehicles was discussed. The discussion of the need for SCMS highlighted the importance of the role and responsibilities of SCMS between vehicles and vehicles. The security certificate management system looked at the structure and analyzed the type of certificate used in the vehicle or road side unit (RSU). The functions and characteristics of the certificates were reviewed. In addition, the functions of basic safety messages were analyzed with consideration of the detection and warning functions of abnormal behavior in SCMS. Finally, the status of the pilot project for connected vehicles currently being pursued by the U.S. government was analyzed. In addition to the environment used for the test, the relevant messages were also discussed. We also looked at some of the issues that arise in the course of the pilot project.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.7
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• pp.20-25
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• 2019

In this paper, the structural weakness analysis and quality improvement of small fixed wing UAV of the hard landing type were studied. Unlike conventional aircraft, small UAV does not use runways because of its small size. Instead, small UAV use hand launch takeoff and hard landings. This type has many operational advantages because it can take off and land in a narrow space. But, the hard landing has a strong impact on the structure of the UAV and can cause serious damage. In order to analyze the exact cause of this phenomenon, the structural analysis was carried out using the 3D structural analysis program (ABAQUS) to identify the location of the fracture. And to improve the accuracy of the structural analysis, properties of the material were obtained through specimen test. As a result of the analysis, structural weaknesses were identified and improved. Thus, the validity of the study was verified by demonstrating the quality of enhanced structure through a real impact test at a higher level of 1.5 times the maximum impact during operation.

• Journal of Internet Computing and Services
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• v.20 no.2
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• pp.109-118
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• 2019

The purpose of this study is to deliver both market-practical and civil-centric political implication for sharing economy by investigating the nature of consumer-adoption for car-sharing service. With the global interest and market proliferation of the sharing economy, various service models for sharing idle resources have also been released in Korea. Particularly, in case of car sharing service, public - private partnership projects are spreading rapidly in various local governments including Seoul, along with the growing demand for alternative transportation system centering on the urban area. This study conducted an empirical study on the process of accepting the car sharing service by analyzing the data collected from users of the car sharing service "Sharing Car(Nanum Car)" of Seoul Metropolitan Government. A survey was conducted on 281 users in their twenties who are in the age of main use among the experienced users of the "Sharing Car(NaNum)" residing in Seoul. The result of analysis on the relationship between these users' perceived value and intention to use the vehicle sharing service would provide implications for establishing consumer(citizen)-centeric policies as well as market implications.