• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.10
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• pp.739-744
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• 2017

Elastic deformation and fatigue damage can cause the permanent deformation of a kart's frame during turning, affecting the kart's driving performance. A kart's frame does not contain any suspension or differential devices and, therefore, the dynamic behavior caused by torsional deformation when driving along a curve can strongly affect these two kinds of deformations. To analyze the dynamic behavior of a kart along a curved section, the GPS trajectory of the kart is obtained and the torsional stress acting on the kart-frame is measured in real time. The mechanical properties of leisure and racing karts are investigated by analyzing their material properties and conducting a tensile test. The torsional stress concentration and frame distortion are investigated through a stress analysis of the frame on the basis of the obtained results. Leisure and racing karts are tested in each driving condition using driving analysis equipment. The behavior of a kart when being driven along a curved section is investigated through this test. Because load movement occurs owing to centrifugal force when driving along a curve, torsional stress acts on the kart's steel frame. In the case of a leisure kart, the maximum torsional stress derived from the torsional fatigue limit was found to be 230 MPa, and the torsional fatigue limit coefficient was 0.65 when driving at a speed of 40 km/h. Furthermore, the driving elements during the cornering of a kart were measured based on an actual auto-test after installing a driving measurement system, and the driving behavior of the kart was analyzed by measuring its vertical displacement.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.10
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• pp.696-706
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• 2017

The purpose of this study was to verify experimentally debris reduction facilities for culverts installed in small rivers. A culvert is defined as a structure laid under a road or a railroad that passes through an inner urban area or downtown area to make an artificial canal. Culverts are generally categorized into road culverts or waterway culverts, among which the latter are artificial structures designed to discharge running water into a river. At the time of floods, the structural safety of waterway culverts can be undermined by the accumulation of debris, such as soil, boughs and weeds, and they may be at risk of overflowing due to blockages. Debris reduction facilities are necessary to prevent such damage. In this study, the effects of the three existing types of debris reduction facilities were examined through hydraulic experiments. The results of the experiments showed that vertical separation to divert debris reduced the accumulation rate by 27.65 to 31.39 percent. The two types of screen designed to block and divert debris, respectively, were found to have excellent debris blocking abilities. However, when the effects of the rising water level are considered simultaneously, the screen to divert debris was found to show superior effects. The screen to block debris can be considered to have excellent debris blocking ability, but requires the continuous collection of the debris, due to the high risk of rising water levels caused by its accumulation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.8
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• pp.624-629
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• 2016

A brake lever in a basic railway brake system is an important safety device that delivers braking force from the brake cylinder to the brake pad. The safety guidelines for designing rolling stock only qualitatively describe that the brake lever should have sufficient strength. Each train has a different type of brake lever. One brake lever that was designed with a factor of safety of 1.27 has failed, so the material was changed to increase the strength. Therefore, the stress distribution and weak points of the lever were identified by theoretical analysis. and structural analysis. Different brake lever designs were examined for KTX high-speed trains, which have a split-type structure, as well as for electric locomotives, which use an electric multiple unit (EMU) with a unity-type structure. A fracture test was also done to look at the relationship between the vertical stress and the bending stress during braking. The results were used to find a safety factor to apply to each train and suggest quantitative minimum guidelines. We also looked at changing the unity-type EMU brake lever to the split type under the same conditions and analyzed how much the design change affected the factor of safety.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.12
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• pp.106-111
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• 2017

In this study, the stiffness of an LMU (Leg Mating Unit), which is a device required for installing the top side part of an offshore structure, was examined through structural analysis. This unit is mounted on the supporting point of the structure and is used to absorb the shock at installation. It is a cylindrical structure with an empty center. To support the vertical load, elastomeric bearings (EBs) and iron plates are laminated in layers. The stiffness of the EBs is basically influenced by the size of the bearings, but it varies with the number of laminated sheets inside the same sized structure. The relationship between the stiffener and the compressive stiffness is investigated, and its design is suggested. The stiffness of the EBs is analyzed by calculating the reaction force, while controlling the displacement. First, the relationship between the size of the reinforcing plate and the compressive stiffness is considered. Next, the relationship between the number of stacked reinforcing plates and the compression stiffness is considered. Different loads are required for each installed point. The goal is to design the compression stiffness in such a way that the same deformation occurs at each point in the analysis. In this study, ANSYS is used to perform the FE analysis.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.3
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• pp.230-236
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• 2020

A trash screen is installed in front of the inflow channel of a drainage pumping station, sewage treatment plant, and a power plant to block floating contaminants. The bottleneck phenomenon, which decreases the water inflow, causes damage to the damper as a result of clogging in between the screen if string type obstacles are not removed. In this paper, the apron was removed, and the screen was expanded, to prevent breakage of the bottleneck phenomenon and string type obstacles. This was designed using an extended rake by adding an inner rake in between the screen interspace to remove the bottleneck phenomenon and string type obstacles. To design the inner rake that satisfies the allowable stresses of the existing damper rake, the experiment points were determined according to the experimental design method using the inner rake vertical length and the thickness of the reinforced section as parameters. The use of the ANSYS static structural module and statistical analysis tool R software gives the optimized shape according to the response surface method. The relative error between the response surface analysis results and the simulation results was 1.63% of the determined optimal design-point rake length of 210.2 mm and the reinforcement section thickness of 2 mm. Through empirical experiments, a test rake was constructed to the actual size, and approximately 97% of the bottleneck phenomenon and string type obstacles could be removed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.3
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• pp.481-487
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• 2020

This study examined the behavior change of river levees during an earthquake by numerical analysis. Unlike conventional research using artificial earthquake waves, earthquake analysis was performed using real earthquake waves. The behavior of a river levee before and after an earthquake was compared and analyzed quantitatively. Studies show that the river levee has a safety factor of approximately 28.5% due to an earthquake. On the other hand, the minimum standard safety factor is satisfied. Vertical effective stress has decreased by 81.8% due to excess pore-water pressure generated by the earthquake. In addition, liquefaction occurs in most of the foundation soil. An examination of the stress-displacement behavior due to the earthquake revealed a large amount of settlement in the backfill layer. Most of the foundation soil yielded. Therefore, the target river levee is quite vulnerable to earthquakes. Through the results of this study, the necessity of refreshing the seismic design standards for river levees is required. This study can be used as basic data for estimating the approximate damage level and vulnerable areas.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.4
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• pp.1-8
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• 2020

This paper proposes architectural and evacuation recommendations through evacuation experiments of two child care centers with disabilities. To achieve these purposes, a survey on the architectural characteristics and evacuation experiments was carried out. The results were as follows: (1) the child care center with disabilities were located within one kilometer or five minutes from a fire station and 119 safety center, but the architectural characteristics and the ratio of self-moving children in a care center were very different conditions. (2) The evacuation behavior patterns of children with a disability were as follows: hugging a child by a teacher with the arms, walking with hugging and holding the child by a teacher, moving a wheelchair with a helper, and drag-out a cerebral palsied child with a mat wrapping. (3) The speed of the evacuation was fast in the following order: drag-out with a mat wrapping a child with a disability, hugging the child with the arms, walking with hugging and holding child, and moving with a wheelchair. In the case of difficulties in the vertical evacuation, a temporal evacuation area was essential for children with disability.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.9
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• pp.49-56
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• 2020

High temperature heat generated during rifle firing not only degrades the performance of the weapon, but also limits the user's operation. In this study, temperature change of handguard according to firing was measured with reference to Human Engineering criteria and the operability according to material was examined. Accordingly, for the firing test, three types of Korean rifle and one overseas model were selected for each material of handguard, and firing test was conducted using a contact type temperature meter. The test result shows that using a plastic handguard with low thermal conductivity and aluminum handguard with high thermal conductivity enabled the rifles to be operated with bare hands even when firing at more than 100 rounds at low atmospheric temperature. However, when firing more than 60 rounds at over 20℃ atmospheric temperature, aluminum handguard use is limited. When firing quickly over 100 rounds, handguard use is restricted regardless of its fabrication material. To eliminate operational limitations by overheating, it is necessary to eliminate direct contact with skin using gloves, vertical grips, etc. This study examined the operability of rifles in terms of thermal risk, and the resulting study results are expected to be used as basic data for Human Engineering of other rifles and munitions.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.9
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• pp.397-404
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• 2020

The military tactical vehicle currently being operated is manufactured by improving the parts of commercial vehicles. In addition, the power supply system is applied by installing a separate converter inside the communication room to secure the operating environment of communication equipment. On the other hand, due to electromagnetic radiation noise, there are problems in frequent noise and deterioration in communication sensitivity during wireless communication in vehicles. To improve these, an advanced power supply system is applied, which is also equipped with an alternator to receive power required for communication equipment reducing broadband electromagnetic radiation noise. An additionally installed alternator, which is located in the engine room, is separated from the communication room where communication equipment is operated and is expected to reduce the effect of electromagnetic radiation noise generated from the power supply system. To verify these, a broadband radiation test was performed on a previous and advanced one. As a result, the broadband radiation noise of vehicles with an applied advanced power supply system satisfied all of the domestic vehicle safety standards and reduced in most of the sections except for some frequencies compared to previous typed vehicles. In particular, broadband radiation noise was decreased by up to 10.751 dB𝜇V/m in the vertical sections in 170 to 200 MHz on the right side of the vehicle.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.1
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• pp.28-35
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• 2016

The in-situ thermal response test for the design of a ground heat exchanger of geothermal heat pumps have difficulty in predicting the outlet temperature according to the variation of conditions due to the expense and time. This paper suggests a 3-D CFD analysis method to predict the heat transfer performance of vertical type ground heat exchanger, which is mostly used in national, and the outlet temperature and the slope of two in-situ thermal response tests were compared to test the proposed CFD reliability. The results of CFD analysis showed that the outlet temperature was predicted to within $0.5^{\circ}C$ of the actual value and the slope was predicted to within 1.6%. The reliability of the CFD analysis method was confirmed using this process, and the outlet temperature prediction of the two in-situ thermal response tests was obtained by changing ${\pm}20%$ of the flow rate and the effective thermal conductivity conditions, respectively. The results of CFD analysis showed that the outlet temperature of Case 1 was 28.0 (-20%) and $29.6^{\circ}C$ (+20%) for the flow rate variation and $29.6^{\circ}C$ (-20%) and $28.0^{\circ}C$ (+20%) for the effective thermal conductivity variation, and the outlet temperature of Case 2 was 28.4 (-20%) and $29.8^{\circ}C$ (+20%) for the flow rate variation and $29.7^{\circ}C$(-20%) and $28.4^{\circ}C$(+20%) for the effective thermal conductivity variation.