• Korean Journal of Agricultural Science
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• v.46 no.4
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• pp.723-735
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• 2019

The power-train is the most important component of an agricultural tractor. In this study, the strength of the driving gear transmission of an 82 kW-class tractor was analyzed using equivalent torque during plow tillage. The load measurement system consisted of an engine revolution speed sensor, torque-meters, revolution speed sensors for four axles, and pressure sensors for two hydraulic pumps. The load data were measured during plow tillage for four speed stages: F2 (2.78 km/h), F5 (5.35 km/h), F7 (7.98 km/h), and F8 (9.75 km/h). Aspects of the gear-strength such as bending stress, contact stress, and safety factors were analyzed under two torque conditions: the equivalent torque at the highest plow load for the F8 speed stage and the maximum engine torque. The simulation results using KISSsoft showed that the maximum engine torque conditions had a lower safety factor than did the highest equivalent torque condition. The bending safety factors were > 1 at all gear stages, indicating that gear breakage did not occur under actual measured operating conditions, nor under the maximum torque conditions. However, the equivalent torque condition in the contact stress safety factor was > 1, and the maximum torque condition was < 1 at the first gear pair. The method of analysis using the equivalent torque showed lower stress and higher safety factor than did the method using maximum torque. Therefore, when designing a tractor by applying actual working torque, equivalent torque method would support more reliable product development.

• Journal of the Korea institute for structural maintenance and inspection
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• v.6 no.2
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• pp.245-253
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• 2002

This study was focused on the effect of concrete strength and lateral ties of concrete columns using high-strength concrete. Thirty-six concrete columns with 20cm square cross-section were tested. Experimental parameters included the concrete strength, the distribution of longitudinal bars and the volumetric ratio, yield strength, spacing of lateral ties. From the experiments, we found that: 1) the increasing rate of the strength and ductility of concrete columns caused by confinement of lateral ties was decreasing, as the concrete strength increased. 2) The high volumetric ratio and the reduction of tie spacing had a tendency to enhance the strength and improve the ductility. 3) The high-strength concrete columns required high volumetric ratio of lateral ties to maintain the proper strength and ductility. It was observed that the current AIK design code to specify the maximum tie spacing of high-strength concrete columns led to the poor strength and ductility for seismic design.

• Journal of Music and Human Behavior
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• v.10 no.2
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• pp.79-97
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• 2013

The purpose of this study was to obtain the normative data of finger strength using the keyboard and the MIDI(Musical Instrument Digital Interface) software. A total of 92 college students (46 male and 46 female) were recruited from universities located in Seoul and Chungcheong province and an average age was 21.7(SD = 1.8). After the completion of demographic information, each participant asked to press the five keys both in ascending and descending manners with the maximum strength of individual finger. The velocity was obtained as an indicator for finger pressing force by using the MIDI software. Results showed that the individual finger velocity ranged between 77 to 97 (Maximum possible velocity = 127). Regarding male's velocity data, the maximum velocity was found in index finger of dominant hand(96.9), while the minimum strength was found in ring finger of nondominant hand(78.5). Female data appeared to be similar to male's one in terms of maximum strength in dominant index finger(92) and minimum strength in nondominant ring finger(77.5). It also found that the statistically significant differences(p < .05) on finger strength of all fingers between dominant and non-dominant hands except the thumbs(p < .05). The current findings serves as a "normative standard" that proves the validity and effectiveness of hand rehabilitation training program using the electronic keyboard connected with the MIDI software to enhance functional changes in hands.

• Journal of Korean Association for Spatial Structures
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• v.6 no.2 s.20
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• pp.53-60
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• 2006

The shear failure modes of reinforced concrete members using high-strength materials (high-strength concrete and high-strength steel) are different to those of reinforced concrete members using normal-strength materials. The reinforced concrete members using high-strength materials are inclined to fail due to concrete crushing before the shear reinforcing bar reaches its yield strength. This paper presents an evaluation equation to calculate the maximum shear reinforcement ratio based on the material stresses and strains when the reinforced concrete members fail in shear. The maximum shear reinforcement ratio calculated by the proposed equation increases as the compressive strength of concrete increases. Test results of 97 reinforced concrete members reported in the technical literatures are used to check the validity of the proposed equation. The comparison between the test results and the ratio calculated using the proposed equation indicated that the shear failure modes depended on the interaction between the amount of shear reinforcement and the compressive strength of concrete.

• Magazine of the Korea Concrete Institute
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• v.6 no.3
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• pp.131-141
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• 1994

This study was carried out to develop a procedural method to produce high strength polymer concrete using unsaturated polyt.ster resin and to examine its mechanical properties. Various mechanical properties were analyzed with respect to materials and additives. A method to produce high strength polymer concrete was successfully developed. Comperssive strength of $1,291~1,445 kg/cm^2$, splitting tensile strength of $106~145 kg/cm^2$ and flexural strength of $182~235 kg/cm^2$, at age of 7days wer-e achieved from the cylinderical ;md beam specimen prepared with the method. Modulus of elasticity. Poisson's rntio and the ultirnate corn pressive strain of cylinderical specimen were $2.8~3.8{\times}10^5\;kg/cm^2$. 0.21~0.32, and 0.005~0. 0065, respectively. Modulus of elasticity of the polymer concrete was smaller than that of hlgh strength cement concrete while the maximum compressive strain was very larger than that of high strength cement concrete.

• Journal of the Korea Convergence Society
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• v.10 no.6
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• pp.281-286
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• 2019

Appearance is a means of competitiveness for modern people, and one of the factors that harms the desires of modern people is white hair. For the modern man who needs to express beautiful appearance to others by covering white moth, we performed hair analysis after white moth hair dye treatment. The maximum modulus and tangential modulus according to the maximum load, maximum tensile strength, maximum elongation, breaking load, fracture strength, elongation at break, and evaluation interval between 1N-3N experimental group and control group of 1N-Respectively. Maximum load, maximum tensile strength, breaking load and breaking strength tended to be larger than those of the control group, while the maximum elongation and breaking elongation were the highest in the control group and the elongation decreased with the experimental group treatment. The maximum modulus and tangential modulus of the 1N-3N test group were higher than those of the control group at 0~0.15 and 0.15~2.5, respectively. Based on the study on the cosmetic changes of the hair before and after the treatment, it can be used as a basic data to select the correct oxidative hair dye product, the proper amount of application and the time to leave.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.6
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• pp.62-69
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• 2023

Re-damage is frequently occurring for various reasons, including material factors, external factors, and factors caused by poor construction in concrete cross-section restoration work, so it is necessary to identify the cause and improve it. Cement-based materials are the most commonly used maintenance materials for concrete structures, and in particular, additional cross-sectional restoration work may be carried out due to re-damage such as cracks and excitement due to dry contraction of the repair material. In this study, a basic study was conducted to identify the characteristics of concrete while diversifying the maximum dimensions and assembly rate of thick aggregates to examine the effects of using thick aggregates in repair materials. As a result, the slump of concrete increased as the maximum size of thick aggregates increased, and the amount of air content was measured 1.88 to 2.35 times higher in the mixing using aggregates with a maximum aggregate size of 5 mm or more compared to the mixing group with a maximum aggregate size of 10 mm or more. It was found that compressive strength was greatly affected by the performance rate of thick aggregates. The compressive strength was measured the highest in the mixture using thick aggregates with the highest performance rate of 20 mm, and the compressive strength of the mixture with the lowest performance rate was more than 45%. As a result of the dry shrinkage measurement, the dry shrinkage was the lowest as the performance rate of the thick aggregate increased according to the change in the maximum dimensions and assembly rate of the thick aggregate, and the lowest performance rate was the largest in the mix. Through this study, it was confirmed that adjusting the particle size by diversifying the maximum dimensions and assembly rate of thick aggregates used in concrete structure repair materials can improve strength and workability and reduce dry shrinkage.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.11
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• pp.4956-4962
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• 2012

Among the various parts of automobile, automotive seat is the most fundamental item that ride comfort can be evaluated as the direct contact part with human body. Automotive seat must have the sufficient rigidity and strength at the same time with ride comfort. In this study, cushion frame and back frame at car seat are modelled with 3D. There are structural simulation analyses about 3 kinds of tests on torsion strength, vertical load strength and back frame strength. In the analysis result, the initial total deformation and the permanent total deformation has the maximum values of 5.4821 mm and 0.02539mm respectively at the torsion strength test of cushion frame. Total deformations at front and rear end parts of cushion frame become the values of 2.1159mm and 0.0606mm respectively at the test of vertical load strength of cushion frame. In case of more than this load, the maximum value of total deformation also becomes 3.1739mm. The maximum value of total deformation becomes 0.18634mm at 3 kinds of the strength tests on back frame. By the study result of no excessive deformation and no fracture cushion frame and back frame at automotive seat, the sufficient rigidity and strength to guarantee the safety of passenger can be verified.

• Journal of Korean Biological Nursing Science
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• v.4 no.1
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• pp.5-23
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• 2002

Purpose: To determine the effect of the Fall Prevention Program(EPP) on gait, balance and muscle strength in elderly women at a nursing home. Method: The subjects of this consisted of 38 elderly women between the ages of 70 to 89 years living at a nursing home located in Seoul. Each of the experimental group and control group was composed of 19 subjects. The subjects in experimental group have participated in FPP for the 8 weeks which consisted of exercise, education and foot care. They started to exercise for 40 minutes per session, 3 sessions a week during the 1st week at 40% of age adjusted maximum heart rate. From the 2nd week to the 4th week, they increased the duration of exercise to 50 minutes per session and the intensity to 60% of age-adjusted maximum heart rate. They participated in 50 minutes at 60% of age-adjusted maximum heart rate from the 5th week to the 8th week. Each exercise session consisted of 10 minutes of warming-up exercise, 30 minutes of conditioning exercise and 10 minutes of cooling-down exercise. They participated in education for 20 minutes per week from the 1st week to the 4th week. Then they participated in a 30-minute foot care program per week from the 5th week to the 8th week. Gait, balance and muscle strength for each subject were measured before and after FPP. Gait was evaluated by step length, step width, gait speed and walking distance. Balance was measured by the duration of standing on one leg with their eyes closed and open each, and a get-up and go test. Grip strength was measured by hand dynamometer. Hip extensor and flexor strength, knee extensor and flexor strength and ankle plantarflexor and dorsiflexor strength were measured by manual muscle tester. Data was analyzed using SPSS form Windows. t-test and Chi square test were utilized as a homogeneity test. Repeated measure ANOVA was used to test the effect of FPP. Result: 1) Step width significantly decreased, and step length, gait speed and walking distance significantly increased in the experimental group compared with the control group after FPP(p<0.005). 2) There was no significant change in standing time on one leg with their eyes closed after FPP. The standing time on leg with their eyes open and the time of "get-up and go" significantly decreased in the experimental group compared with the control group after FPP(p<0.005). 3) Muscle strength-grip strength, hip extensor and flexor strength-significantly increased in the experimental group compared with the control group after FPP(p<0.005). 4) There was no significant difference of frequency of fall between the experimental group and control group during the period of FPP. Conclusion: These results suggest that FPP can increase gait, balance and muscle strength of elderly women at a nursing home.

• Journal of the Korea Concrete Institute
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• v.28 no.1
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• pp.33-40
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• 2016

The KCI-12 and ACI 318-14 design codes limit the maximum yield strength of shear reinforcement to prevent concrete compressive crushing before the yielding of shear reinforcement. The maximum yield strength of shear reinforcement is limited to 420 MPa in the ACI 318-14 design code, while limited to 500 MPa in the KCI-12 design code. A total of eight post-tensioning prestressed concrete beams with high strength shear reinforcement were tested to observe the shear behavior of PSC beams and the applicability of the high strength reinforcement was thus assessed. In the all PSC beam specimens that used stirrups greater than maximum yield strength of shear reinforcement required by the ACI 318-14 design code, the shear reinforcement reached their yield strains. The observed shear strength of tested eight PSC beams was greater than the calculated ones by the KCI-12 design codes. In addition, the diagonal crack width of all specimens at the service load was smaller than the crack width required by the ACI 224 committee. The experimental and analytical results indicate that the limitation on the yield strength of shear reinforcement in the ACI 318-14 design code is somewhat under-estimated and needs to be increased for high strength concrete. Also the application of high strength materials to PSC is available with respect to strength and serviceability.