• Journal of the Korean Society of Safety
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• v.18 no.3
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• pp.69-74
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• 2003

To investigate the partial discharge and electric field distribution in cable joint parts, we measured the partial discharge and electric field in specimen. The specimens which cross-linked polyethylene(XLPE) and ethylene propylene diene ethylene(EPDM) are used to insulating material for underground cable md cable jointing parts. The polymers are used to insulating material in switchgear which is a kind of transformer equipment and in ultra-high voltage cable. Its using is increasing gradually, the electrical insulation properties are not only excellent but also mechanical property is excellent. And because it is possible to be made void of several type in insulator while it is produced, which the electrical field distribution is changed by void, it has a critical influence to insulator performance. The underground cable is connecting by the jointing material, insulating breakdown and the electric ageing which are caused by several mixing impurity and the damage of cable insulator layer, which reduced the life of cable while intermediate joint kit is connected. Therefore, the computer simulation is used to estimating insulator performance, XLPE is used to the insulating material of ultra-high voltage cable and EPDM is used to insulator layer in joint material kit, and which are produced as specimen. And it is analyzed the electric field concentrating distribution and partial discharge by modeling of computer simulation in void and cable joint kit.

• Steel and Composite Structures
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• v.39 no.3
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• pp.337-352
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• 2021

The study presented experimental and numerical investigation on the seismic performance of steel reinforced concrete (SRC) L-shaped column- reinforced concrete (RC) beam joints. Various parameters described as steel configuration form, axial compressive ratio, loading angle, and the existence of slab were examined through 4 planar joints and 7 spatial joints. The characteristics of the load-displacement response included the bearing capacity, ductility, story drift ratio, energy-dissipating capacity, and stiffness degradation were analyzed. The results showed that shear failure and flexural failure in the beam tip were observed for planar joints and spatial joint, respectively. And RC joint with slab failed with the plastic hinge in the slab and bottom of the beam. The results indicated that hysteretic curves of spatial joints with solid-web steel were plumper than those with hollow-web specimens. The capacity of planar joints was higher than that of space joints, while the opposite was true for energy-dissipation capacity and ductility. The high compression ratio contributed to the increase in capacity and initial stiffness of the joint. The elastic and elastic-plastic story deformation capacity of L-shaped column frame joints satisfied the code requirement. A design formula of joint shear resistance based on the superposition theory and equilibrium plasticity truss model was proposed for engineering application.

• Journal of the Korean Society of Safety
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• v.34 no.3
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• pp.50-56
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• 2019

Precast members have relatively good quality because they are manufactured in an environment suitable for quality control. A typical precast method in which pre-fabricated segments are assembled in the field requires a joint. Although the joint is a small part of the member, it greatly affects the behavior and quality of the structural member. In the previous study of this paper, the flexural strength of a joint, which is generally applied to half-depth precast deck systems, was verified to have higher strength than the design requirement. In addition, the proposed joint has been verified to have higher strength by reinforcing the connecting rebar. However, even if the flexural strength of the joints is sufficient, excessive deflection or lack of fatigue performance is likely to cause cracks in the half-depth precast deck system. In this study, the serviceability of the half-deck precast panel specimens with joints was evaluated and the experimental verification was conducted to evaluate the fatigue performance of the joint without connection rebar. As a result, the serviceability such as deflection and crack width was found to be higher than the design requirement in all the specimens. In the fatigue test, the fatigue effect was insignificant even in the absence of connection rebar.

• Nuclear Engineering and Technology
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• v.54 no.1
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• pp.357-373
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• 2022

The high-temperature gas-cooled reactor pebble-bed module project is the first commercial Generation-IV NPP(Nuclear Power Plant) in China. A new joint is used for the vertical support of RPV(Reactor Pressure Vessel). The steel corbel is integrally embedded into the reactor-cabin wall through eight asymmetrically arranged pre-stressed high-strength bolts, achieving the different path transmission of shear force and moment. The vertical monotonic loading test of two specimens is conducted. The results show that the failure mode of the joint is bolt fracture. There is no prominent yield stage in the whole loading process. The stress of bolts is linearly distributed along the height of corbel at initial loading. As the load increases, the height of neutral axis of bolts gradually decreases. The upper and lower edges of the wall opening contact the corbel plate to restrict the rotation of the corbel. During the loading, the pre-stress of some bolts decreases. The increase of the pre-stress strength ratio of bolts has no noticeable effect on the structure stiffness, but it reduces the ultimate bearing capacity of the joint. A simplified calculation model for the elastic stage of the joint is established, and the estimation results are in good agreement with the experimental results.

• The Journal of Asian Finance, Economics and Business
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• v.9 no.7
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• pp.53-62
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• 2022

Commercial banks have a significant impact on the economy of Vietnam because they provide the majority of transactional capital. Therefore, the operational efficiency of commercial banks is a viral topic for the study of the Vietnamese banking system. The research aims to examine the efficiency and inefficiency of joint-stock commercial banks in Vietnam from 2016 to 2020 and then classify them into the efficient group and inefficient group. The study employs the time series data of 29 joint-stock commercial banks during the period 2016-2020. Based on the data collected from the annual audited financial statements of 29 Vietnamese joint-stock commercial banks, the authors select input and output variables for the standard DEA models and anti-efficient DEA models. This research uses two stages, first, by applying the standard DEA model, we investigate the efficient banks; second, by employing the anti-efficient DEA model, we find out the inefficient banks. The results reveal that the average efficiency score of 29 joint-stock commercial banks tends to increase in the period 2016-2018 and decrease gradually in the period 2019-2020. The findings of this study suggest that several small and medium-sized banks in the Vietnamese banking sector have both promising and risky performances and the efficiency of state-owned commercial banks has also improved significantly during the study period.

• International Journal of Highway Engineering
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• v.12 no.3
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• pp.27-35
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• 2010

Asphalt Plug Joint(APJ) is an buried expansion joint that enabling the smooth connection of expansion gap and road pavement by filling the gap with bituminous mixture of 20% bitumen and 80% aggregate by weight, so it secures evenness and expansion or contraction using the material's properties. Although APJ is designed to have a 6-7 year lifecycle, there are some cases where it is damaged within the first six months. This early damage cause traffic congestion due to frequent repair works, and social cost exceeding the installation cost of the joint. So, in this research, we have developed a new system of Buried Folding Lattice Joint(BFLJ) which can overcome the disadvantages of APJ, and have analyzed and compared it's performance with the conventional APJ through experiment with specimens. As a result of the experiment, APJ had crack formation on both ends of the gap plate, spreading to the surface of the expansion joint. With this result, we can conclude that the reason for early damage is the tension failure due to the concentration of strain in the asphalt mixture along the end of gap plate and the debonding along the joint section. In contrast, the newly developed BFLJ induced even transformation in the joint by applying moving stud and high performance material, and resolved APJ's disadvantage of strain concentration. Therefore, it could be seen that the newly developed BFLJ could overcome the disadvantages of APJ and prevent early damage.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.177-184
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• 2008

Vehicle body frame stiffness affects the dynamic and static characteristics. Vehicle frame structure performance is greatly affected by crossmember and joint design. While the structural characteristic of these joint vary widely, there is no known tool currently in use that quickly predicts joint stiffness early in design cycle. This paper present the joint design factors affecting on low frequency vibration. The joint factors are joint panel thickness, flange width and weld point space. To study the effect on vehicle low frequency vibration, case studies for these factors are performed. The result can present design guide for high-stiffness vehicle.

• International Journal of Knowledge Content Development & Technology
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• v.9 no.3
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• pp.75-101
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• 2019

In this study, we wanted to investigate and analyze the current status of international joint research conducted on researchers who have actually conducted or are doing international joint research and to identify difficulties in promoting international joint research based on this study and propose ways to promote future international joint research. As a result, autonomy of research subjects needs to be guaranteed for the revitalization of international joint research, establishment of international joint research guidelines and contract legal infrastructure, simplification and unification of administrative work system and supplementation of performance-related regulations will be necessary.

• Earthquakes and Structures
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• v.20 no.1
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• pp.29-38
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• 2021

According to ACI 224.3R-95 (ACI, 2013), construction joints (cold joint) in the column are to be provided at the top of floor slab for column continuing to the next floor and underside of floor slab and beam. A recent study reveals that providing cold joint of the mentioned location significantly reduced the seismic performance of the frame structures. Since, the construction joints in multi-story frame structures normally provided at the top of the floor slabs and at soffit of the beam in the column. This study investigated the effect of construction joint at various location in the column of beam-column joint such as at the top of floor slab, soffit level of the beam, half the depth of beam below the soffit of the beam and at a full depth of the beam below the soffit of the beam. The study revealed that there is an improvement in seismic capacity of the specimens as the location of cold joint is placed away from the soffit of the beam for lower story column.

• Structural Engineering and Mechanics
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• v.78 no.5
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• pp.623-635
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• 2021

Previous studies have suggested the maximum experimental story shear force of beam-column joint frame does not reach its theoretical value due to beam-column joint failure when the column-to-beam moment capacity ratio was close to 1.0. It was also pointed out that under a certain amount of axial force, an axial collapse and a sudden decrease of lateral load-carrying capacity may occur at the joint. Although increasing joint transverse reinforcement could improve the lateral load-carrying capacity and axial load-carrying capacity of beam-column joint frame, the conditions considering varying axial force were still not well investigated. For this purpose, 7 full-scale specimens with no-axial force and 14 half-scale specimens with varying axial force are designed and subjected to static loading tests. Comparing the experimental results of the two types of specimens, it has indicated that introducing the varying axial force leads to a reduction of the required joint transverse reinforcement ratio which can avoid the beam-column joint failure. For specimens with varying axial force, to prevent beam-column joint failure and axial collapse, the lower limit of joint transverse reinforcement ratio is acquired when given a column-to-beam moment capacity ratio.