• Geomechanics and Engineering
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• v.29 no.4
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• pp.471-486
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• 2022

The effect of segmental joints is one of main importance for the segmental lining design when tunnels are excavated by a mechanized process. In this paper, segmental tunnel linings are analyzed by two numerical methods, namely the Beam-Spring Method (BSM) and the Solid-Interface Method (SIM). For this purpose, the Tehran Subway Line 6 Tunnel is considered to be the reference case. Comprehensive 2D numerical simulations are performed considering the soil's calibrated plastic hardening model (PH). Also, an advanced 3D numerical model was used to obtain the stress relaxation value. The SIM numerical model is conducted to calculate the average rotational stiffness of the longitudinal joints considering the joints bending moment distribution and joints openings. Then, based on the BSM, a sensitivity analysis was performed to investigate the influence of the ground rigidity, depth to diameter ratios, slippage between the segment and ground, segment thickness, number of segments and pattern of joints. The findings indicate that when the longitudinal joints are flexible, the soil-segment interaction effect is significant. The joint rotational stiffness effect becomes remarkable with increasing the segment thickness, segment number, and tunnel depth. The pattern of longitudinal joints, in addition to the joint stiffness ratio and number of segments, also depends on the placement of longitudinal joints of the key segment in the tunnel crown (similar to patterns B and B').

• Journal of the Korean Wood Science and Technology
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• v.45 no.1
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• pp.53-61
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• 2017

In this study, specimens were produced with a column member and a wooden gusset only by inserting an wooden gusset which is a substitute for steel plate into the center of a slit-processed column member. The moment resistance performance of the specimens was compared with that of control specimens that used a steel plate. The measured maximum moments of the specimens produced with GFRP-reinforced wooden laminated gussets and pins were lower by 24% on average compared to the steel plate-inserted specimens, but they showed good toughness. The fracture shape suggests that it was fractured along the annual rings between the pin and the end of the column member. The rigid specimen that integrated a laminated wood and a wooden laminated gusset with adhesive showed 2.8 times greater initial rigidity and 40% greater maximum moment on average compared to the control specimen. The rigid specimens mainly fractured on a glulam around glue line.

• Journal of Korean Tunnelling and Underground Space Association
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• v.21 no.5
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• pp.675-687
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• 2019

In recent years, the needs for double deck-tunnels have increased in large cities due to the increase in traffic volume and high land compensation costs. In Korea, a network type tunnel which is smaller than general road tunnels and crosses another tunnel underground is planned. In the shield tunnel joints between the existing shield tunnel and the box-type enlargement section, a partial steel-concrete joint is proposed where the bending moment is large instead of the existing full-section steel joint. In order to analysis the enlargement section of the shield tunnel diverged section to reflect the three-dimensional effect, the two-dimensional analysis model is considered to consider the column effect and the stiffness effect of the longitudinal member. A two-dimensional analysis method is proposed to reflect the stiffness of the longitudinal member and the column effect of the longitudinal point by considering the rigidity of the longitudinal member as the elastic spring point of the connecting part in the lateral model. As a result of the analysis of the model using the longitudinal member, it was considered that the structural safety of the partial steel-concrete joint can be secured by reducing the bending moment of the joint and the box member by introducing the longitudinal member having the stiffness equal to or greater than a certain value.

• Journal of muscle and joint health
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• v.3 no.1
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• pp.37-49
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• 1996

The joint diseases threaten modern people's healthy life. They bring about a long pain, an anasarca, loss of joint function or even deformation and rigidity of joint, limiting people's ordinary activities much. The chronic joint patients may be subject to some hypochondria caused by anxiety for their life, social isolation, financial problem and physical disability. Therefore, this population should continue to be duely taken care of by medical personnels. In particular, nurses should adequately help these people to recover and improve their health through suitable adaptations. With such basic conceptions in mind, this study was aimed at reviewing these patients' conditions in their ordinary life before and after a plastic operation for artificial joint replacement as well as their satisfaction with their life. For this purpose, those patients who underwent some plastic operations for artificial joint replacement at university hospitals in Seoul from January 2, 1993 to June 30, 1995 were selected as the population of this study. Among them, 87 people were randomly sampled to answer a questionnaire designed specially. For the surveying tools, Jette's (1980) scale was applied to address the sample people's inconveniences experienced and supports received in their ordinary life, while the scale of Wood, Wylie & Sheafer was used to measure their satisfaction with their life. The collected data were analyzed for percentiles, means, SD, t-test and Pearson's correlations. The results of survey can be summarized as follows ; As a result of t-test the frequencies of other people's support before and after the plastic operation, it was disclosed that those who underwent the operation were supported less frequently. In addition, as a result of t-testing their satisfaction with life before and after the operation, it was found that the operation increased their satisfaction with life significantly. Meanwhile, as a result of t-test inconveniences, frequencies of supports and life satisfaction before and after the plastic operation for artificial knee replacement, it was disclosed that only the inconveniences were significantly reduced after the operation. In contrast, the t-test the variables before and after the plastic operation for artificial hip replacement, it was found that only the frequencies of other people's supports were significant reduced after the operation. Furthermore, the differences 6 months, one year and two years after the plastic operation for artificial joint replacement were t-tested on the variables. As a result, it was disclosed that people's inconvenience, frequencies of supports and life satisfaction were not improved 6 months after the operation but their frequencies of supports decreased significantly one year after, while their inconveniences and life satisfaction were significantly improved two years after. As a result of analyzing the variables with Pearson's correlations, inconveniences and frequency of supports were negatively correlated significantly with the life satisfaction. In conclusion, the plastic operation for artificial joint replacement significantly improved people's living inconveniences, reduced their frequency of other people's support and enhanced their satisfaction with life. To break don the plastic operation for artificial knee replacement improved patients' inconveniences, while the plastic operation for artificial hip replacement not only improved patients' inconveniences but reduced the frequencies of other people's support also. Finally, the finding that the plastic operation for artificial joint replacement brought about the improvement two years after suggests that this period is needed for the patients to adapt themselves to the post-operation conditions.

• Journal of the Korean Wood Science and Technology
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• v.39 no.1
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• pp.8-14
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• 2011

Japanese larch glulam was used as structural members to develop a modern engineered wood jointing system using traditional post and beam structure. For the connections comprised of traditional joining and drift-pins, structural members are processed at a pre-cut factory. As a basic study to examine and increase the whole shear performance of portal frame, pin withdrawal test and moment resistance tests were conducted on each connection. The post and beam members with specified connectors showed good bearing performance in the wood members' joining system, column-base and beam-end. Moment rigidity was a bit better in a joint with higher slenderness ratio of drift-pin, but moment resistance performances, yield moment and maximum moment, were excellent in smaller one.

• Journal of Korean Association for Spatial Structures
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• v.18 no.1
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• pp.45-53
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• 2018

Following the earthquake that shook the city of Gyeongju, Korea, in 2016, it became apparent that research on the safety of cultural heritages against the seismic hazards is necessary in Korea. Predictions of how historically significant stone pagodas would behave the earthquakes anticipated in near future, which are the subject of this study, is also required. In this study, the dynamic characteristics of 15 cultural heritage designated stone pagodas of Korea were investigated, including natural frequency and damping ratio, and the stiffness of the stone material and its contact area were determined using eigenvalue analysis by assuming the stone pagodas to be multi-degree-of-freedom structures. The results of this study enable the structural modeling of stone pagodas using a finite element analysis program and the method is expected to be useful in assessing the structural safety of stone pagodas against vertical loads as well as lateral forces, including earthquakes. Also, by identifying the dynamic characteristics of the structures, the results of this study can be utilized as a nondestructive testing method to determine the rigidity of cultural heritage structures and to identify inherent problems. The natural frequencies of the Korean stone pagodas were measured to be within 3.5~8.3Hz, excluding cases with distinct natural frequency results, and it was determined that the natural frequencies of the stone pagodas are influenced by various parameters including the height and joint stiffness of the structures.

• International journal of advanced smart convergence
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• v.9 no.4
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• pp.26-33
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• 2020

This study measured the downward stepping movement relative to weight change (no load, and 10%, 20%, 30% of body weight respectively of adult male (n=10) from standardized stair (rise of 0.3 m, tread of 0.29 m, width of 1 m). The 3-dimensional cinematography and ground reaction force were also utilized for analysis of leg stiffness: Peak vertical force, change in stance phase leg length, Torque of whole body, kinematic variables. The strategy heightened the leg stiffness and standardized vertical ground reaction force relative to the added weights (p<.01). Torque showed rather larger rotational force in case of no load, but less in 10% of body weight (p<.05). Similarly angle of hip joint showed most extended in no-load, but most flexed in 10% of body weight (p<.05). Inclined angle of body trunk showed largest range in posterior direction in no-load, but in vertical line nearly relative to added weights (p<.001). Thus the result of the study proved that downward stepping strategy altered from height of 30 cm, regardless of added weight, did not affect velocity and length of lower leg. But added weight contributed to more vertical impulse force and increase of rigidity of whole body than forward rotational torque under condition of altered stepping strategy. In future study, the experimental on effect of weight change and alteration of downward stepping strategy using ankle joint may provide helpful information for development of enhanced program of prevention and rehabilitation on motor performance and injury.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.36 no.3
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• pp.165-171
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• 2023

The rotary joint connecting the upper and lower structures of construction machinery and special vehicles transmits hydraulic pressure as the shaft and housing rotate, and multiple seals are assembled to prevent oil leakage into the oil flow channel. Because the seal material is rigid and difficult to assemble, we sought a method to assemble it after cutting. The shapes of the cutting surface are L-shaped and / shaped, and the leakage standard when hydraulic pressure is applied is the contact pressure generated on the cutting surface. The structure and material of the seal are composed of a double elastomer, and nonlinear contact structural analysis is performed when only the high-rigidity PE material is cut. Studies have shown that the shorter the cutting length, the better the leakage prevention and the higher the possibility of leakage to the bottom surface where NBR and PE come into contact rather than the top surface where the PE and the housing come into contact.

• Journal of the Korean Wood Science and Technology
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• v.17 no.2
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• pp.34-64
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• 1989

Corner block with anchor bolt(CBA) joint method used in knock-down type table furniture manufacturing can reduce the packing and transporting cost. Unfortunately. it also has the disastrous defect to be loosend and unstable during the service life mainly due to fatigue and creep(repeated and prolonged loading). So 22 joint groups constructed were tested to evaluate the effect of some design factors related to the size of side rail(apron). block attachment to side rail. and the number of anchor bolt as well as the effect of the type of corner block(mitered type vs. rectangular type) Usable strength from the stiffness coefficients of each joint group were analysed with SPSS /PC+ and described as the criteria of CBA joint construction. The conclusions were as follows: The height of side rail(50, 75 and 100 mm) and the addition of polyvinyl acetate(PVAc) emulsion in the corner block attactment to side rail had the effect on raising the usable strength of CBA joint with remarkable high significance. And the effect of 2 - anchor bolts was also superior to that of 1 - bolt significantly. However. the thickness of side rail(22 mm vs. 25 mm) had no effect on the strengthening the table joint rigidity. Mitered type corner block joint appeared to he recommendable for CBA jointed table construction rather than the rectangular type one regardless of the method of block attachment to side rail. The best result identified from Duncan's multiple comparison was in the construction with 25 mm thick and 100 mm height of side rail fastened using 2 - anchor bolts in mitered type corner block. But it would be reasonable to use 22 mm thick & 75 mm high side rail and mitered corner block with PVAc emulsion & 2 bolts considering the productivity and production cost down in the MDF furniture manufacturing industries.

• Composites Research
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• v.30 no.4
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• pp.254-260
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• 2017

In this paper, we investigated the application method and properties of 0.1 mm, 0.2 mm and 0.3 mm beads, which can secure a certain thickness due to the molding stability of joint surfaces of different materials (aluminum and composite). In order to verify this, the influence was evaluated according to the thickness of the adhesive in the Double lap test and the FEM simulation. As a result, it was confirmed that as the content of the bead of the adhesive increased more than 1%, the strength of the adhesion increased and the elongation decreased. We confirmed as the size of the bead became larger, the rigidity became lower and the elongation increased.