• 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.499-504
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• 2017

A Mobile Radio Wave Measurement System (MRWMS)is a vehicle-mounted system designed to be operating in a single mission. The mission characteristic for mobile measurement requires mobility. For this, we must consider the arrangement and embedded method of MRWMS's antennas. In this paper, we described the measurement method design of direction detecting accuracy for MRWMS and designed the direction finding antenna mast capable of rotating itself by using a slip ring without turntable for Direction Finding (DF) accuracy test. As we removed the dependency of a limited local area by designing a measurement method of direction detecting accuracy, Equipment Under Test (EUT) zero-Adjustment and mounted process shortened. So, we the reduced production costs. We expect an improved cable loss value by shortening the RF cable length in accordance with our design. In addition, due to the same phenomenon, the entire system is lighter and the mobility is improved.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.10
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• pp.174-180
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• 2020

This paper presents the development of a tacho generator that is applicable to a DC motor for anti-aircraft weapon systems. In general, devices such as tacho generators and resolvers are used as feedback devices for controlling DC motors. A tacho generator with a wide operating temperature range was developed, which has robust characteristics against shock loads and vibrations according to the operational characteristics of anti-aircraft weapon systems. The target specifications were set based on the requirements of the tacho generator currently in operation. A rotor coupled to the shaft of the motor and a stator coupled to the housing of the motor were then designed and manufactured. The inductance was 31.0 mH, the terminal resistance was 147.7 ohms, and the rotational measurement factor was satisfactory under both normal operation and operating conditions after the maximum speed for the standard of 9.500 ± 0.475 V/krpm. In addition, the environmental suitability of the applied equipment was confirmed through the rate of change in unit temperature, and it was found that the temperature characteristics were all within 0.03 %/℃.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.10
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• pp.541-546
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• 2020

The surveillance radar for naval ships is an essential equipment of a battle system that executes the detection and tracking of targets, and the shooting support function; it calculates the three-dimensional track of the target range, azimuth, and altitude to carry out its duty. The surveillance radar consists of an antenna, a transceiver, a processing unit, and an air dryer section. The radar radiates the transmission signal on the antenna section, receives the reflected signal from the target, and amplifies the signals on the transceiver section. The signal received from the antenna is used to provide the operator with target information in various ways. This study identified the display problems when the information about the target is displayed through the radar. The causes of the problems were analyzed and improved. The tracking disappearance phenomenon caused by the altered-course of the ship was improved on the TWS tracking algorithm. The validity of the improved TWS tracking algorithm was confirmed by the normal condition of the target status on the B-scope.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.8
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• pp.172-182
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• 2016

This study is a descriptive survey research conducted to examine the influence of learning efficacy on nursing students' self-confidence. Research subjects included a total of 231 university students in D city, and the data were analyzed by t-test, ANOVA, Pearson's correlation coefficients, and multiple regression. The study results were as follows: Learning experience was high in the order of vital sign check, intramuscular injection, and subcutaneous injection. Recognition of importance was also high in the order of vein therapy, intramuscular injection, and vital sign check. Self-confidence was high in the order of vital sign check and wearing of protective equipment. As for the learning experience, there were significant differences depending on the students' school year. As for the correlation among all variants, 'learning experience of nursing skills', 'self-confidence', 'learning self-efficacy', and 'self-efficacy' had a positive correlation with each other. Based on these study results, it is necessary to develop an educational strategy that ensures students' education of self-efficacy and improvement of their learning experience to enhance their self-confidence.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.10
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• pp.4403-4410
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• 2011

The purpose of this study was to investigate on the safety knowledge level, and to identify the factors that affect the safety knowledge according to general characteristics of scuba divers. This research design was a descriptive study. Data of 179 scuba divers were collected from October 17, 2010 to June 17, 2011. Data were analyzed by SPSS PASW statistics 18.0 program. The mean score of safety knowledge related to diving was 2.07(${\pm}0.54$)(score range was 1~4). The highest score was safety knowledge to cope with the cold($2.42{\pm}0.64$점). The lowest score was safety knowledge for hyperexpansion of lungs. In the results of multivariate regression analysis after variable selection, Adjusted $R^2$ value was 0.567. The model fit was 56.7%. The factors that affect the safety knowledge were age(${\leqq}29$ years), equipment(all purchase, some lease), motivation(job), participation period(${\leqq}11$ months) and frequency(once a month)(p<.05, p<.001). It is necessary to develop and conduct the educational program for scuba divers safety at country level.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.69-75
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• 2019

The cooling performance of heat pump system for light-duty commercial electric vehicle was evaluated experimentally. The cooling performance characteristics of the heat pump for light-duty commercial electric vehicles were evaluated by varying the temperature, flow rate of chiller coolant, and electric compressor speed, under the exterior air temperature of 35 ℃ and interior air temperature of 25 ℃. Increasing the compressor speeds decreased the cooling system efficiency by 16.4 % on average with the cooling capacity increasing by 8.0 % on average and the compressor work increasing by 27% on average. To use waste heat from the coolant to chill power electronic components, such as the motor and inverter, a chiller was installed to transfer heat between the coolant and refrigerant. Increasing the temperature of the chiller coolant from 35 ℃ to 55 ℃ decreased the efficiency by 18.2 % on average due to higher condensing heat source. Increasing the coolant flow rate from 10 liter/min to 20 liter/min did not affect the cooling capacity of the system due to a similar total condensing heat transfer rate at the chiller and the exterior heat exchanger. In future works, heating performance will be investigated by varying the operating conditions to use the chiller's waste heat with an improvement of heating capacity.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.12
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• pp.321-328
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• 2017

The effects of the Sewol ferry disaster have infiltrated into various fields, such as politics, the economy, and social fields in Korea, and the population's consciousness of the importance of safety has been strengthened by the disaster. The purpose of, this study is to empirically verify whether there has been any change in the fire service environment following the Sewol ferry disaster. Such a change would be expected to have produced a change in the consciousness of the government about safety and increased the level of support. This study sets out five research hypotheses and verifies their adoption. The years studied are those before and after the accident occurred, viz. 2013 and 2015, respectively, and the main statistical technique is the t-test. The main results of this study are as follows. First, there was no significant difference in the fire-service demand between the two years. Second, the fire-service budget showed a significant difference between the two years. Third, the regional resources facilities tax showed a significant difference between the two years. Fourth, the fire-service budget considering the fire-service demand showed no statistically significant difference. Fifth, the fire service-demand considering (the number of) fire-fighters was significantly different in the rescue and emergency medical services between the two years. Sixth, the fire service-demand considering fire-equipment showed no significant difference between the two years.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.12
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• pp.638-643
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• 2017

The 3D laser scanner operates by measuring the distance from the sensor to the target and operates on the same principle as Electronic Distance Measuring (EDM). Recently, 3D laser scanning technology has been rapidly developed in line with the strongly increasing demand for 3D information acquisition. Therefore, it is now possible to more easily acquire geometric information of various objects existing in real space. In this study, we constructed geospatial information by using new equipment which integrated 3D laser scanner and total station, and we suggest the possibility of using new technology for geospatial information construction by comparing and analyzing with existing methods. In the study result, we demonstrated the efficiency of the geospatial information constructed by integration of 3D laser scanner and total station. The proposed method is expected to shorten the time required for data acquisition compared to the existing method using the existing total station. Furthermore, it is possible to use various methods such as cross section analysis and volume calculation using the acquired data. In the future, spatial information construction by integration of 3D laser scanner and total station will help improve work efficiency in related fields.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.12
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• pp.452-458
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• 2017

In this study, a device was developed for diagnosing depression using EEG signals from July 2016 to June 2017. For normal people, the left alpha rhythm is more activated than the right alpha rhythm, but for the depressed patients, the right alpha rhythm is more activated than the left one. An analog circuit and digital low pass filter were used for noise removal and amplification of EEG, and the Hamming window function was applied to eliminate the signal leakage generated by the fast Fourier transform. To verify the validity of the developed diagnosis system, the EEG of 20 university students in the 3rd and 4th grade with an average age of 24 years was measured. Calculations of the relative value of the left and right alpha rhythm for the depression diagnosis revealed a minimum, maximum, and mean value of 66.7, 113.3, and 92.2, respectively. In addition, 7 out of 20 subjects were between 90 and 95, and those with a higher mean deviation of approximately 20 tended to have mild depression. These results can provide meaningful data for the development of depression treatment equipment by solving the left and right brain asymmetry problem, and it may be applied usefully to diagnose depression after clinical trials on a large number of depressed patients.