• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.3
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• pp.8-15
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• 2019

The PM synchronous motor drives with vector control have been applied to wide fields of industry applications due to its high efficiency. The rotor position information for vector control of a PM synchronous motor is detected from the rotor position sensors or rotor position estimators. The sensorless control based on the mathematical model of PM synchronous motor is generally used and it can be classified into back EMF -based sensorless control and magnet flux-based sensorless control. The rotor position estimating performance of the back EMF-based sensorless control is deteriorated at low speeds since the magnitude of back EMF is proportional to the motor speed. The magnitude of the magnet flux for estimating rotor position in the flux-based sensorless control is independent on the motor speed so that the estimating performance is excellent for wide speed ranges. However, the estimation performance of the model-based sensorless control may be influenced by the motor parameter variation since the rotor position estimator uses the mathematical model of the PM synchronous motor. In this paper, the rotor position estimation performance for the back EMF based- and flux-based sensorless controls is analyzed theoretically and is compared through the simulation and experiment when the motor parameters including stator resistance and inductance are varied.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.11
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• pp.105-115
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• 2018

The purpose of this study was to clarify whether or not alcohol drinking patterns are associated with sleep quality. A cross-sectional study was carried out by self-administered questionnaire in May, 2017 among 553 male workers who employed in manufacturing industries in D city. Logistic regression analysis was used to evaluate whether or not alcohol drinking patterns (as measured by frequency, amount of alcohol per day, and amount of alcohol per week) were associated with poor sleep quality (as measured by Pittsburgh Sleep Quality Index). As a result, in comparison with male workers who did not drink, the adjusted odds ratio for poor sleep quality was 0.44 (95% CI=0.232-0.845) for those who drank alcohol once a week or more, 0.31 (95% CI=0.192-0.829) for those who drank less than 1 glass daily, and 0.28 (95% CI=0.167-0.762) for those who drank 1-3 glasses daily. The results of this study suggest that some alcohol drinking patterns may affect sleep quality among male workers.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.11
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• pp.182-190
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• 2018

Many pharmaceutical companies operate the SFA system to support salespeople. The SFA system is used for various behaviors of salespeople. However, there is a lack of empirical analysis on the performance of SFA in Korea. The purpose of this study is to investigate the utilization of SFA system and the non - financial performance of SFA system. The subjects of the survey were 347 pharmaceutical community members who consisted of pharmaceutical salespeople and surveyed online for 18 days from March 13, 2018 to April 30, 2018. and the effective response rate was 23.1% (80/347). The analysis shows that the higher the level of SFA system utilization, the higher the non - financial performance. By type of company, the utilization level of multinational companies was higher than that of domestic companies. Among the SFA utilization level items, 1.47 points (3.65, 2.18) were higher than the domestic companies in terms of the support service items. Among the SFA performance items, foreign companies were 1.47 points (3.16, 1.69) Respectively. This suggests that the SFA development and operation method of the domestic company focuses on the management service rather than the support service for the salesperson and the customer satisfaction. Through this study, it is considered that domestic companies should strengthen sales person support and customer satisfaction information providing function when operating SFA system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.11
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• pp.278-286
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• 2018

The existing test-based qualification system does not sufficiently reflect the demand for skills in industries and there exist concerns regarding its efficacy. In response, an innovative national technical qualification system, which uses a course-based qualification system, has been introduced to supplement the test-type qualification system. This study investigates the impact of the national technical qualification system on companies' decisions concerning employment by analyzing survey data from companies that employed persons who obtained course-based qualifications. Analysis results found the degree of company demand for skills had a positive impact on overall employment decisions. Especially, it was highly likely for those companies that experienced loss due to the lack of technology in the past to decide continued employment and expansion of employment. This suggests that it is necessary to design the national technical qualification system in response to the demand for technological skills of each industry in the future.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.11
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• pp.550-560
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• 2018

Many countries have provided support for research and development and implemented policies for Advanced Driver Assistance Systems (ADAS) for enhancing the safety of vehicles. With such efforts, the toll of casualties due to traffic accidents has decreased gradually. Korea has exhibited the lowest toll of casualties due to traffic accidents and is ranked 32nd in mortality among the 35 OECD members. Traffic accidents typically fall into three categories depending on the cause of the accident: vehicle to vehicle (V2V), vehicle to pedestrian (V2P), and vehicle independent. Most accidents are caused by drivers' mistakes in recognition, judgment, or operation. ADAS has been proposed to prevent and reduce accidents from such human errors. Moreover, the global automobile industry has recently been developing various safety measures, but on-road tests are still limited and contain various risks. Therefore, this study investigated the international standards for evaluation tests with regard to the assessment techniques in braking capability to cope with the limitations of on-road tests. A theoretical formula for braking force and a control algorithm are proposed, which were validated by comparing the results with those from an on-road test. These results verified the braking force depending on the functions of ADAS. The risks of on-road tests can be reduced because the proposed theoretical formula allows a prediction of the tendencies.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.8
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• pp.8-14
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• 2019

Bird-strike is one of the most important design factors for safety in the aviation industry. Bird-strikes have been the cause of significant damage to aircraft and rotorcraft structures and the loss of life. This study used DYTRAN software to simulate the transient response of an Euler-Lagrangian composite helicopter blade that has been impacted by a bird. The Arbitrary Lagrangian Eulerian (ALE) method and a suitable equation of state were applied to model the bird. ALE was applied to the bird-strike analysis due to the large difference between the properties of the blade and bird. The debris of the bird was assumed to be a fluid and applied as Euler elements after the collision. Through the analysis of bird impacts, the leading-edge of the rotor blade (50.8 mm) was used to identify a positive margin of 1.18 based on the TSAI-FILL criteria. The results are assessed to be sufficiently reliable and may be evaluated to replace tests with various analysis conditions. The structural stability of the rotor blade could be assessed by applying various load conditions and different modeling methods in the future.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.8
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• pp.649-656
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• 2019

Flux cored arc welding (FCAW), which is used widely in many fields, such as shipyards, bridge structures, construction machinery, and plant industry, is an alternative to shielded metal arc welding (SMAW). FCAW is used largely in the welding of carbon and alloy steel because it can be welded in all poses and obtain excellent quality in the field under a range of working conditions. In this study, the mechanical properties of welded parts were analyzed after different welding of SS400 and SM490A using FCAW. The following conclusions were drawn. The tensile test results satisfied the KS standard tensile strength in the range of 400~510 N/mm2 in all welding positions. The bending test confirmed that most of the specimens did not show surface breakage or other defects during bending and exhibited sufficient toughness, even after plastic deformation. The hardness test results were lower than the standard value of 350 Hv of KS B 0893. Similar to the hardness test, were greater than the KS reference value. The macro test revealed no internal flaws, non-metallic inclusions, bubbles or impurities on the entire cross section of the weld, and there were no concerns regarding lamination.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.8
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• pp.139-148
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• 2019

Fostering science-gifted individuals are very important for the future of the nation, and it is especially important to cultivate information-gifted individuals in the age of the fourth industry. There is no standardized curriculum for each gifted education center of the University. Therefore, in this study, we analyzed how effective the curriculum developed on the basis of computing thinking is to affect the characteristics of the information-gifted individuals. The curriculum developed on the components of computing thinking was applied to the information-gifted students of K University. In order to verify the effectiveness of the curriculum, we developed a creative personality test and an intrinsic motivation test, and conducted tests before and after the training. We compared pre-post test results by t-test with R program. The creative personality test consisted of 36 items with 6 factors: risk-taking, self - acceptance, curiosity, humor, dominance, and autonomy. The intrinsic motivation test consisted of 20 items with 5 items: curiosity and interest oriented tendency, challenging learning task preference orientation, independent judgment dependency propensity, independent mastery propensity, and internal criterion propensity. The effect of the curriculum on the creative personality of the experimental group was significant (0.009, 0.05). The significance level of the intrinsic motivation was 0.056 and was not significant at the 0.05 level of significance.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.6
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• pp.439-447
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• 2019

In this study, experiments were conducted to establish appropriate measures for slopes with high risk of collapse and to obtain results for minimizing slope collapse damage by detecting the micro-displacement of soil in advance by installing a laser sensor and a vibration sensor in the landslide reduction model experiment. Also, the behavior characteristics of the soil layer due to rainfall and moisture ratio changes such as pore water pressure and moisture were analyzed through a landslide reduction model experiment. The artificial slope was created using granite weathering soil, and the resulting water ratio(water pressure, water) changes were measured at different rainfall conditions of 200mm/hr and 400mm/hr. Laser sensors and vibration sensors were applied to analyze the surface displacement, and the displacement time were compared with each other by video analysis. Experiments have shown that higher rainfall intensity takes shorter time to reach the limit, and increase in the pore water pressure takes shorter time as well. Although the landslide model test does not fully reflect the site conditions, measurements of the time of detection of displacement generation using vibration sensors show that the timing of collapse is faster than the method using laser sensors. If ground displacement measurements using sensors are continuously carried out in preparation for landslides, it is considered highly likely to be utilized as basic data for predicting slope collapse, reducing damage, and activating the measurement industry.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.2
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• pp.509-519
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• 2019

The size of the global game market, including Korea, is gradually expanding, there are about 80,000 people in the game industry in Korea, and it has maintained a steady increase. As the domestic game has become more influential, games have become a means of helping people to communicate with each other in everyday life. Despite these changes, There is a lack of positive perspectives such as game use and interpersonal interactivity or communication enhancement. Therefore, this study analyzed the correlation of psychological and environmental factors of adolescents, game leadership, and social capital in order to understand the positive effects of games. As a result of research, psychological factors such as social motivation, game efficacy, and game norms have a statistically significant effect on game leadership. Parental supervision has a negative effect on game leadership and a statistically influenced positive effect on social capital. Overprotective parenting has a negative effect on both game leadership and social capital. Finally, game leadership has a statistically influenced positive effect on social capital. This paper is meaningful in that the research on the positive aspect of the game was conducted for the adolescent.