• Journal of IKEEE
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• v.24 no.4
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• pp.1004-1010
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• 2020

This paper proposes an initial rotor magnetic pole detection method for single-phase permanent magnet synchronous motors. The target motor cannot obtain position information based on the back emf in the low speed and stop state. Therefore, an open loop starting process is required, and in this process, initial rotor position information for low current and soft start is need. The proposed initial rotor magnetic pole detection algorithm considers the effect of asymmetric air- gap and magnetic flux. In addition, the high-frequency voltage signal injection and the offset voltage for accurate detection is used. As a result, the permanent magnet poles are is determined by acquiring the maximum value of the induced current using the virtual dq-axis.

• The Journal of the Korea Contents Association
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• v.22 no.4
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• pp.83-93
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• 2022

Research is underway to solve the traffic problem by using crowdsourcing, where drivers use their mobile devices to provide traffic information. If it is used for traffic event detection through crowdsourcing, the task of collecting related data is reduced, which lowers time cost and increases accuracy. In this paper, we propose a scheme to collect traffic-related data using crowdsourcing and to detect events affecting traffic through this. The proposed scheme uses machine learning algorithms for processing large amounts of data to determine the event type of the collected data. In addition, to find out the location where the event occurs, a keyword indicating the location is extracted from the collected data, and the administrative area of the keyword is returned. In this way, it is possible to resolve a location that is broadly defined in the existing location information or incorrect location information. Various performance evaluations are performed to prove the superiority and feasibility of the proposed scheme.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.6
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• pp.859-864
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• 2022

Drowsy driving, one of the biggest causes of traffic accidents every year, is accompanied by various factors. As a general method to check whether or not there is drowsiness, a method of identifying a driver's expression and driving pattern, and a method of analyzing bio-signals are being studied. This paper proposes a driver fatigue detection system using deep learning technology and bio-signal measurement technology. As the first step in the proposed method, deep learning is used to detect the driver's eye shape, yawning presence, and body movement to detect drowsiness. In the second stage, it was designed to increase the accuracy of the system by identifying the driver's fatigue state using the pulse wave signal and body temperature. As a result of the experiment, it was possible to reliably determine the driver's drowsiness and fatigue in real-time images.

• Korean Journal of Social Welfare Studies
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• v.42 no.1
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• pp.151-177
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• 2011

With the expansion of Voucher program, academic and practical concerns of performance evaluation of voucher service has been more emphasized. Accordingly, client satisfaction survey are expanding these days, but the study of client satisfaction as a performance indicator aimed at service client has not been yet conducted systematically. The purpose of this study is to develop Satisfaction Index, targeting at client of community-development voucher program in Community Service Investment Project conducted by the Ministry of Health and Welfare. Data were collected from 1800 client of community-development voucher program. This study summarized theoretically many kinds of satisfaction measurement and composed the Satisfaction Index reflecting characteristics of Voucher. By the item analysis and reliability analysis, the element satisfaction was identified as homogeneous items. General satisfaction were obtained using element satisfaction and overall satisfaction, it was found to be valid through the evaluation of convergent and discriminant validity as a tool for satisfaction. This study suggest using the '1step weighted approach' than '2step weighted approach' having weakness of complex overlapping manner.

• The Journal of the Acoustical Society of Korea
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• v.28 no.4
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• pp.308-317
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• 2009

In the present work, a sensor system composed of an oscillator sensor and a Lamb wave sensor is proposed for the purpose of structural health monitoring. The oscillator sensing system detecting the shift of a structural resonant frequency in proportion to the amount of defects in the structure is a pretty sensitive and simple device, but its detectable range is limited to its local zone. The Lamb wave sensor system, however, is applicable to global detection of the defects. This study is aimed at investigating the feasible combination of the two systems to exploits their merits simultaneously. The scheme to use PZT patches as the oscillator sensor as well as the Lamb wave sensor was proposed to identify the position, length and number of cracks by means of TOF and amplitude of signals, and its validity was confirmed through experiments.

• Management & Information Systems Review
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• v.36 no.2
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• pp.157-185
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• 2017

This study was carried out with the attention that the concept of entrepreneurial orientation has been applied at various levels of CEO, employee, management, and organization as a whole. The differences between these concepts were examined by discriminant validity and convergence validity, and the causal relationship between these concepts and performance was analyzed. A total of 96 questionnaires were collected and analyzed. The results show that CEO's entrepreneurial orientation, employee's entrepreneurial orientation, manager's entrepreneurial orientation and organizational entrepreneurial orientation have convergent validity and discriminant validity, and that these variables have different effects on the firm 's innovation performance and financial performance. In the analysis of the mediating effect, when the variables of all levels were put into a single variable, the innovation performance mediates between the entrepreneurial orientation and the financial performance in all variables. However, when all variables are applied simultaneously, innovation performance has mediating effect only on the relationship between organizational entrepreneurship orientation and financial performance. This shows that there is a conceptual difference according to applied level. As a result of the analysis of the causal relationship by the application level of entrepreneurial orientation, it is found that causality is formed among the entrepreneurial orientation variables. In particular, CEO's entrepreneurial orientation influences employee's entrepreneurial orientation, manager's entrepreneurial orientation, and organization's entrepreneurial orientation, and again, employee's entrepreneurial orientation and managerial entrepreneurial orientation form a causal relationship that influences organization's entrepreneurial orientation. In the relationship between innovation performance and financial performance, CEO's entrepreneurial orientation, organization's entrepreneurial orientation, and manager's entrepreneurial orientation are influencing innovation performance, and the only variables influencing financial performance are organization's entrepreneurial orientation. In conclusion, the limitations of the study and its future direction are presented.

• Journal of Preventive Medicine and Public Health
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• v.22 no.1 s.25
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• pp.146-152
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• 1989

To test the validity of referral of high risk pregnancy in the MCH Center, 6,017 pregnant women who visited MCH Center of South District Health Center for delivery between 1 April 1985 and 31 March 1987 were interviewed on arrival to obtain the data for demographic characteristics and obsteric history and traced to check the delivery outcome. Out of 5,820 women whose delivery outcomes were confrmed, 704 women(12.1%) were referred to other hospital or clinic for high risk factors. The proportion of poor delivery outcome(stillbirth, low birth weight and neonatal death) among referred cases was 4.4% while that of the women delivered at the MCH Center was 2.2% (p<0.01). Decision of the midwives for the referral of high risk pregnancy based on their clinical assessment was consistent with the delivery outcome (good or poor) in 86.5%. Major reasons for referral were premature rupture of membrane(46.5%) and cephalopelvic disproportion(20.0%) and the C-section rates for these cases were 10.1%, 17.6%, respectively. Discriminant analysis of the demographic characteristics and obstertric history for the discrimination of delivery outcome showed that gestational age had the highest discriminant function coefficient(0.88) and it was followed by parity(0.37) and maternal education(0.30). Referral of high risk pregnancy by the midwives based on their clinical assessment was considered to be reasonably valid. However, a risk scoring system for an MCH Center which can improve the validity may be developed if one applies the discriminant analysis for more comprehensive independent variable(including clinical assessment of midwife, demographic characteristics and obstetric history) and dependent variable (including medically indicated C-section, complication of pregnancy and delivery, stillbirth, low birth weight, neonatal death and maternal death).

• Korean Journal of Childcare and Education
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• v.9 no.6
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• pp.309-337
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• 2013

The purpose of this study was to validate Preschool Child Observation Record-II developed by High/Scope for Korean preschool children. The subjects of the study were 255 children aged three to six attending child care centers and their head teachers. They were observed for at least two months and completed the Korean version of Child Observation Record-II(K-COR-II). K-COR-II consisted of six categories and 32 items which had five-level-rubrics. The results from an exploratory factor analysis identified one dimension of the scale, there was no evidence of discriminant validity even after face validity was examined. The concurrent validity and internal consistency of the revised scale were relatively high. Also, the mean between the upper and lower groups with regard to item discrimination showed significant difference. It was concluded that K-COR-II can be used as a valid and reliable instrument to various aspects of preschool children's development.

• Journal of Nutrition and Health
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• v.53 no.2
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• pp.175-189
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• 2020

Purpose: This study was conducted to develop, validate, and assess the reliability of a questionnaire for nutritional literacy among young Korean adults. Methods: The draft questionnaire contained 65 items in 7 domains (i.e., dietary guideline, nutrition and health, nutrients, 5 food groups [food bicycle], nutrition labeling, portion size, and nutrition management for disease prevention). The authors developed a draft questionnaire based on a literature review. After multiple drafts, 52 items were retained and 13 were eliminated in the 7 domains according to professional advice from 5 nutrition experts. A panel of experts (n = 20) comprised of clinical dietitians and nutrition professors completed the content validity assessment, including quantitative and qualitative feedback. As the results, all items of the portion size were eliminated from the questionnaire. A sample of 211 young adults completed the test-retest reliability assessment. Test-retest reliability was evaluated using intra-class correlation coefficient (ICC) and inter-item reliability by Cronbach α coefficient. Results: The final questionnaire contained 30 items with 5 questions each on the dietary guideline, nutrition and health, nutrients, 5 food groups (food bicycle), nutrition labeling, and nutrition management for disease prevention. The Lawshe content validity ratio for domains ranged from 0.60 to 1.00. The ICC scores for questions ranged from 0.64 to 0.86. Cronbach's α for domains ranged from 0.83 to 0.90 and for the overall questionnaire was 0.87. Conclusion: The questionnaire showed strong content validity, test-retest reliability, and high inter-item reliability, indicating that it is a useful tool for assessing nutritional literacy of young adults.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.8
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• pp.621-630
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• 2018

In the case of launch vehicles using liquid fuel, natural frequency changes due to fuel consumption after launch, and a modal test is essential to investigate its effect. However, when relying on modal test to characterize the free vibration characteristics, the testing time is excessively increased and accuracy is reduced. Therefore, this paper suggests a modal test method with finite element analysis to overcome these drawbacks. A cylindrical structure filled with liquid are considered as a study model, and modal tests and finite element analyses are performed. The modal tests are conducted by an impulsive method using an impact hammer and accelerometers. Through the comparison of the modal test and the finite element analysis results, the validity of the proposed modal test method is verified. In addition, the free vibration characteristics and the tendency for the cylindrical structure according to the liquid filled ratio were investigated.