• Journal of the Korean Recycled Construction Resources Institute
• /
• v.5 no.3
• /
• pp.261-266
• /
• 2017

In this study, to determine the shear properties, experiments on the shear behavior of plain concrete with the high volume fly ash cement by double shear test were performed. Test parameters are fly ash content and concrete compressive strength. Experimental results show the tendency that the shear strength similarly increases with an increase in the compressive strength as is generally known. The concrete shear strength formula proposed in the concrete structural design code of KCI shows a similar tendency to the experimental results, and It is expected that the shear strength of the high volume fly ash cement concrete can be applied with the formula given in the concrete structural design code of KCI. When considering the fly ash content ratio, the shear strength of high volume fly ash cement concrete according to fly ash conctent ratio shows as having a far greater correlation than if it is not considered to fly ash content ratio. So, even though existing code can be appliable for non consideration of the fly ash content ratio, we proposed a formula that is much more relevant than that of concrete structural design code of KCI.

• Journal of Korean Society of Water and Wastewater
• /
• v.24 no.2
• /
• pp.195-202
• /
• 2010

The evaluation of organic matters and nutrients removal was investigated for the synthetic wastewater and the high strength of dairy wastewater. Two different systems were performed for this research. System A composing of a single RBC with tapered aeration was fed with the synthetic wastewater for 74 days with 173L/day of influent, 200% of internal return and 100% of sludge return for the period 1 and 2. The feed conditions were maintained 346L/day of influent, 50% of internal return and sludge return for the period 3. The dairy wastewater was introduced to evaluate treatment efficiency for system B composing of dual RBCs and tapered aeration tanks for 50 days of experimental run time, in which hydraulic rates were maintained at the constant ratios of 346L/day, 50% of internal return and 50% of sludge return. The spiral string media made of nylon fibre was attached by Bacillus sp. in RBC for both systems. The specific area of string media was $1.4m^2$/m and biomass was maintained at the concentrations of 23g/m. The synthetic wastewater was supplied by 1,800mg/L of glucose, 500mg/L of $NH_4Cl$, and 500mg/L of $KH_2PO_4$ to system A. The dairy wastewater was supplied to system B from dairy production plant. The average influent concentrations were 1,334mg/L of BOD, 2,014mg/L of CODcr, 160mg/L of T-N, and 12mg/L of T-P in system A. The average influent concentrations of parameters were 1,006 mg/L for BOD, 1,875mg/L for $COD_{cr}$, 51.6mg/L for T-N and 8.9mg/L for T-P in system B. Results indicated that removal efficiencies of BOD and $COD_{cr}$ were more than 90% however, the removal efficiency of T-N was 87%, and that of T-P was 82% for system A. Removal efficiencies were 98.5% of BOD, 91.3% of nitrogen and 89% of phosphorus for system B. The removal efficiencies of organic matters, T-N and T-P were higher in system B than in system A. The effluent quality issued by the stringent national legislations for the discharge of the high strength of dairy products wastewater can be improved using sequential RBCsand tapered aeration reactors rather than a single RBC and tapered aeration reactors with Bacillus sp.

• Magazine of the Korea Concrete Institute
• /
• v.7 no.1
• /
• pp.109-116
• /
• 1995

In tnis study, the impact factors of a simply supported highway bridge due to a vehicle moving across the span are presented. This variable has received cons~derable attention in recent years, both analytically and experimentally. The KBDC specification equation has a maximum 30 percent value which decreases with span length. The results of field tests showed that the dynamic load effects are mostly lower t.hari present KBDC value and that the impact factor does not vary significantly with spar1 as implied in KHUC. The rnain parameters affecting lmpact are the br dge approach. bumps, and other pavement roughness. In thls study, based on test results, three values of impact factors are provided by correlating the roughness of the surface to the deck condition survey values. The present study proposes reasonable impact factors for the strength evaluation of highway bridges. This study may be extended to the evaluation of existing brdges.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.21 no.3
• /
• pp.433-452
• /
• 2019

This study deals with shotcrete reinforcing performance according to the amount of synthetic fiber (PP fiber) and proper evaluation method. The shotcrete compressive strength, flexural strength and flexural toughness were tested by setting the mixing amounts of steel fiber ($37.0kg/m^3$) and synthetic fiber (PP fiber) as parameters ($5.0kg/m^3$, $7.0kg/m^3$ and $9.0kg/m^3$). Particularly, circular panel flexural toughness test (Road and Traffic Authority, RTA) was performed to evaluate the shotcrete energy absorption capacity. As a result, the compressive strength and the bending strength of the steel fiber reinforced shotcrete were large, but the flexural toughness of the synthetic fibe (PP fiber) reinforced shotcrete was large. Therefore, synthetic fiber (PP fiber) reinforced shotcrete is considered to have a reinforcing effect comparable to that of steel fiber reinforced shotcrete. Analysis of the relationship between the flexural toughness and the energy absorption capacity of synthetic fiber (PP fiber) reinforced shotcrete revealed that the energy absorbing ability is exhibited at a flexural toughness lower than the allowable standard (3.0 MPa). (Class A: 2.55 MPa = 202J, Class B: 2.72 MPa = 282J, Class C: 3.07 MPa = 403J). As a result of this study, it can be concluded that the actual shotcrete support performance can be evaluated by evaluating the support performance of the shotcrete measured at less than the allowable standard (3.0 MPa) at the actual tunnel site.

• Clinics in Shoulder and Elbow
• /
• v.18 no.3
• /
• pp.138-143
• /
• 2015

Background: To evaluate the effect of preoperative fatty degeneration of deltoid and teres minor muscles on the clinical outcome in patient with reverse total shoulder arthroplasty (RTSA). Methods: Nineteen patients with RTSA were enrolled. The mean follow-up period was 16.1 months. The fatty degeneration of three distinct parts in each deltoid and the teres minor muscle was measured using a preoperative magnetic resonance imaging. Postoperatively, the muscle strengths for forward elevation (FE), abduction (Abd), and external rotation (ER) were measured using a myometer at the last follow-up. The parameters for clinical outcome were Constant Score (CS) and Korean Shoulder Score (KSS). Results: The number of cases was 10 in group 1 and 9 in group 2. The strength of FE and Abd were significantly higher in group 1 (p<0.001 and p<0.001, respectively), and the strength of ER was not different significantly between two groups (p=0.065). For the clinical outcome, both CS and KSS were higher in group 1 (p=0.002 and p=0.002, respectively). The number of patients in group A was 11, and group B was 8. Although there was not a significant difference in terms of FE and Abd between group A and B (p=0.091, p=0.238), ER was significantly higher in group A (p=0.012). We did not find a significant difference in the clinical scores (CS, p=0.177 and KSS, p=0.238). Conclusions: These findings suggest the importance of a preoperative evaluation of the fatty degeneration of deltoid and teres minor muscles for predicting postoperative strength and clinical outcome.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.28 no.3
• /
• pp.259-266
• /
• 2015

In this paper, transverse shear spacing and effective depth of wide beams were considered as parameters to evaluate the shear capacity of wide beam according to transverse spacing of steel plates with openings in experimental way. The eight specimens were composed of: five specimens of shear reinforced by steel plates with openings and three non-reinforced specimens. Crack, failure mode, strain and load-displacement curve of specimens were analysed. Shear contribution of shear reinforcement is evaluated and maximum transverse spacing of shear reinforcement was proposed. Shear strength of the specimen that reinforced with three stirrup legs was higher than shear strength of the specimen that reinforced with two stirrup legs. And as the effective depth increased, shear strength was increased.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.27 no.2
• /
• pp.121-128
• /
• 2014

In this study, The purpose of this study is to experimentally investigate the shear behavior of reinforced flat plate embedded with GFRP(glass fiber reinforced polymer) plate with openings. The GFRP shear reinforcement is manufactured into a plate shape with several openings to ensure perfect integration with concrete. The test was performed on 7 specimens. the parameters include the type of reinforcement and amount of the shear reinforcement., From the test, we analysed the crack, failure mode, Strain, load-displacement graph. a calculation of the shear strength of reinforced flat plate with GFRP plate based on the ACI 318-11 was compared with the test results. The results of the experiment indicate that GFRP plate is successfully applied as a shear reinforcement in the flat plate under punching shear.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.19 no.1
• /
• pp.53-61
• /
• 2015

This paper reports the test results of the floating floor system used to reduce the floor noise of apartment buildings. Recently, many soft resilient materials placing between the reinforced concrete slab and finishing mortar are used. The resilient material should not only reduce the floor impact sound vibration from the floor but also support the load on the floor. Thus, even if soft resilient materials satisfy the maximum limitation of light-weight impact sound and heavy-weight impact sound, these materials may not support the load on the floor. The experimental program involved conducting sixteen sound insulation floating floor specimens. Three main parameters were considered in the experimental investigation: resilient materials, loading location, and layers of floor. Experimental results indicated that the stiffness of resilient material significantly influenced on the structural behavior of floating floor system. In addition, the deflection of the floating concrete floor loaded at the side or coner of the specimen was greater than that of the floor loaded at the center of the specimen. However, the aerated concrete did not effect on the cracking strength of floating floor system.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.28 no.2
• /
• pp.354-360
• /
• 2022

The aluminum handrails used for promoting structural strength and weight reduction of the topside in an offshore platform are designed according to international standards (ISO, NORSOK, and Austria Standard), and consider the most conservative load combinations. Existing aluminum handrails are bolted to a socket when installed on the topside of a platform, and the amount of deflection of the handrail is largely influenced by the socket design. However, the importance of socket design has been overlooked, and furthermore, separate evaluation procedures or guidance for socket design are ambiguous. Therefore, a series analysis was performed for estimating the structural strength of aluminum handrails to obtain the governing parameters that minimize their deflection against loads. Experimental verification was performed to validate the structural safety of the new model, and we confirmed that all were satisfied within allowable deflection according to international standards. The developed model could be used in several areas in the future as it is lighter and more productive compared to existing models from overseas makers.

• Journal of the Korean Society of Physical Medicine
• /
• v.15 no.4
• /
• pp.131-143
• /
• 2020

PURPOSE: The purpose of this study was to determine if an exercise program with vertical vibration can improve balance, walking speed, muscle strength and falls efficacy in the healthy elderly. METHODS: A total of 28 elderly were randomly divided into two groups: vertical vibration exercise group (exercise with vertical vibration) (N = 14) and control group (exercise without vibration) (N = 14). The exercise program, comprising calf raise, deep-squat, semi-squat, front lunge, and leg abduction was conducted with or without vibration, respectively. Subjects in each group participated in the 30 minutes training program, 2 times per week for 6 weeks. In both groups, the balance evaluation system (BT4) was used to evaluate standing balance, and walking speed was measured using the 10MWT. The manual muscle test system was applied to evaluate the knee extensor and ankle planter flexor muscle strength of the subjects, whereas the Korean falls efficacy scale (K-FES) evaluated the falls efficacy. RESULTS: After intervention, the vertical vibration group showed significantly higher changes compared to the control group, in the parameters of standing balance (P < .05), 10MWT (P < .05), left knee extensor (P < .05), right knee extensor (P < .01), both ankle plantar flexors (P < .05), and K-FES (P < .05). CONCLUSION: The exercise program with vertical vibration has the potential to improve balance, walking speed, muscle power and falls efficacy in the elderly.