• Journal of the Korea Institute of Military Science and Technology
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• v.27 no.4
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• pp.495-506
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• 2024

In this study, we propose the terrain following algorithm using model predictive control and nonlinear disturbance observer-based backstepping sliding mode controller for an aircraft system. Terrain following is important for military missions because it helps the aircraft avoid detection by the enemy radar. The model predictive control is used to replace the generating trajectory and guidance with the flight path angle constraint. In addition, the aircraft is affected to the parameter uncertainty and unknown disturbance such as wind near the mountainous terrain. Therefore, we suggest the nonlinear disturbance-based backstepping sliding mode control method for the aircraft that has highly nonlinearity to enhance flight path angle tracking performance. Through the numerical simulation, the proposed method showed the better tracking performance than the traditional backstepping method. Furthermore, the proposed method presented the terrain following maneuver maintaining the desired altitude.

• Current Optics and Photonics
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• v.8 no.4
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• pp.355-365
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• 2024

Wavefront coding (WFC) imaging systems can redistribute the energy of an interference laser spot on an image plane sensor by wavefront phase modulation and reduce the peak intensity, realizing laser protection while maintaining imaging functionality by leveraging algorithmic post-processing. In this paper, a spiral axicon WFC imaging system is proposed, and the performance for laser protection is investigated by constructing a laser transmission model. An Airy disk on an image plane sensor is refactored into a symmetrical hollow ring by a spiral axicon phase mask, and the maximum intensity can be reduced to lower than 1% and single-pixel power to 1.2%. The spiral axicon phase mask exhibits strong robustness to the position of the interference laser source and can effectively reduce the risk of sensor damage for an almost arbitrary lase propagation distance. Moreover, we revealed that there is a sensor hazard distance for both conventional and WFC imaging systems where the maximum single-pixel power reaches a peak value under irradiation of a power-fixed laser source. Our findings can offer guidance for the anti-laser reinforcement design of photoelectric imaging systems, thereby enhancing the adaptability of imaging systems in a complex laser environment. The laser blinding-resistant imaging system has potential applications in security monitoring, autonomous driving, and intense-laser-pulse experiments.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.23 no.3
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• pp.212-221
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• 2013

Objectives: Asbestos fibers are accumulated in negative pressure unit (NPU) or vacuum cleaner in asbestos removal. Failure of operation or poor use performance of the NPU or vacuum cleaner causes asbestos fibers to spread in the air. Asbestos contractors should have an NPU fitted with a HEPA , vacuum cleaner, decontamination area, respirators, wetting equipment, and differential pressure manometer to register with the Ministry of Employment and Labor. There should be performance criteria of equipment used in asbestos removal. But there are none such criteria used in asbestos removal. This study was performed to investigate international or national performance criteria of equipment used in asbestos removal. Methods: Regulations, approved code of practice, guidance and national standards of the UK, USA and Korea were reviewed. A survey was done to investigate the requirements for equipment used in asbestos removal in Korea. Results: Air flow of NPUs used in Korea usually covers from$500m^3/h$ to over $3000m^3/h$. Some requirements for NPUs used in Korea were missing compared to the requirements of British standards for NPUs. All NPUs have different missing requirements. The UK also has separate British standard for leak tests for NPUs. Highly hazardous class vacuum cleaners should be used in asbestos removal in the UK. It has national standards on the operation of vacuum cleaners used in asbestos removal. There is only a certification system for less than 2.5kw rated voltage vacuum cleaners for home use in Korea. Powered (-assisted) respirators with mask are recommended in asbestos removal. Type 5 coveralls should be used in asbestos removal in the UK. There are international standards for requirements and leak tests of type 5 coveralls. A manometer for measuring differential pressure is needed in asbestos removal. The manometer's measuring range should cover less than ${\pm}125$ Pa and the gradation of manometer should be less than 2.5 Pa. The definition of decontamination area should be corrected. Installation of airlock and minimum area should be considered in decontamination area. Conclusions: Equipment should be used in asbestos removal proper performance and no leaks. There should be a certification system for equipment used in asbestos removal. This study can help to a certification system for equipment used in asbestos removal in Korea.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.200-211
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• 2019

This study analyzed the factors related to the job satisfaction and turnover rate of students in the skin care contract department, and suggested ways to enhance long-term employee retention. Frequency analysis and multiple regression analysis were performed using the SPSS statistical program and based on the survey data of 260 skin care contract students. The main results were as follows. First, contract students had high job satisfaction because of sufficient in-service training during the internship and also received the authority to perform the job duties of their positions. Second, the regular technical education for the job of contract students gave them confidence in job performance and job confidence, which led to long-term employee retention. Third, contractual students' turnover was reduced by applying compensation such as incentives, awards, and promotion opportunities in accordance with their work performance. Therefore, the results of the study suggest that compensation based on job performance, and the confidence in job performance of skin care contract students, can lead to increased job satisfaction, a reduced turnover rate and better long-term employee retention.

• Korean Journal of Environment and Ecology
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• v.23 no.1
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• pp.78-89
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• 2009

As 'design for all' and 'adaptable design', universal design is highly demanded to be adopted in neighborhood forest trail. The research areas were Mt. Doeum in Pohang, Gyeongsangbuk Province and Mt. Anma in Chuncheon, Gangwon Province which were equipped based on 7 principles of universal design. The purpose of this research is providing baseline data for effective formulation of forest trail using universal design through visitors' evaluation on forest trail facilities by importance-performance analysis. Visitor's evaluation was achieved through questionnaire survey, and total 247 pieces of subjects were used for the analysis, 114 pieces from Mt. Doeum in Pohang and 113 pieces from Mt. Anma in Chuncheon. The residential areas of the respondents were mainly near each mountain - Mt. Doeum and Mt. Anma. According to the responses, nature study and education were the biggest reasons for the respondents' visits to Mt. Doeum, and so was the health to Mt. Anma, which are representative types of visiting behavior to nearby forest trails. The mean of importance was shown to be 3.87 while that of performance was 4.04, being a little higher than importance's, in importance-performance analysis of Mt. Doeum. This result suggests that the responders placed positive value on the forest trail applying universal design. It is necessary to improve the safety and convenience of guidance-safety handrail, make information sign easy to understand, and introduce an interpretive sign meeting the visiting purposes of visitors. Also, the management to make the road surface flat is in demand for the accessibility to forest trail. The mean of importance was 3.92 and that of performance was 3.99 in Mt. Anma, which suggests the necessity of improvement in safety of pavement material and boundary safety facilities.

• Journal of the Korea Convergence Society
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• v.12 no.10
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• pp.311-320
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• 2021

The purpose of this study is to identify the mediating effect of self-efficacy in the relationship between the leadership style of badminton life sports leaders and the performance of club members. A total of 600 badminton club members were invited to participate and 593 were selected for this study. For data analysis, mediating effects were verified through frequency analysis, exploratory factor analysis, reliability analysis, correlation analysis, multiple regression analysis, and hierarchical regression analysis. For result section, first, it was found that training instruction behavior, authoritative behavior, and social behavior, which are sub-factors of the leader leadership type, have a positive effect on performance(p<.05). Second, it was found that training instruction behavior, which is a sub-factor of leader leadership type, had a positive effect on self-efficacy(p<.01), and that authoritarian behavior had a negative effect on self-efficacy(p<.01). Third, the mediating effect of self-efficacy was found indirectly in the relationship between leader leadership and performance(p<.001). Based on these results, it is judged that it will be easier to build a more effective training system if the direction for the leadership and guidance type of life sports is set by reflecting the needs of the participants.

• The Journal of the Convergence on Culture Technology
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• v.9 no.4
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• pp.39-49
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• 2023

This study data were collected from 217 nursing students in J city to analyze major satisfaction and awareness of the importance of practice and performance of nursing students' practice at the public health center, and to identify improvement plans for the practice contents of the health center. The collected data was analyzed using SPSS WIN 25.0, and the research results showed that there was a positive correlation (r=.55, p<.001) between major satisfaction and public health center clinical practice performance, and the sub-factors of performance It showed positive correlation with all (r=.41~.54, p<.001). In particular, among the sub-factors, Internal growth through practice and Correlation with the actual application of theory were highly correlated (r=.54~.56, p<.001). In order to improve nursing students' satisfaction with their major, theoretical study should be preceded, and through area analysis, in order to obtain satisfaction through identity and internal growth of nursing students while practicing health center practice, practice instructors during health center practice Establish various networks, do our best to communicate smoothly with nursing students, and strive to present opinions through meetings with practice institutions before and after practice to improve the community health center practice environment. Also, nursing college students In order for the public health center practice to be carried out smoothly, practice guidance instructors drew improvement points that nursing college students need prior learning related to practice before practicing health center practice.

• Korean Journal of Radiology
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• v.24 no.8
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• pp.729-738
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• 2023

Objective: When multiple surveillance mammograms are performed within an annual interval, the current guidance for oneyear follow-up to determine breast cancer status results in shared follow-up periods in which a single breast cancer diagnosis can be attributed to multiple preceding examinations, posing a challenge for standardized performance assessment. We assessed the impact of using follow-up periods that eliminate the artifactual inflation of second breast cancer diagnoses. Materials and Methods: We evaluated surveillance mammograms from 2007-2016 in women with treated breast cancer linked with tumor registry and pathology outcomes. Second breast cancers included ductal carcinoma in situ or invasive breast cancer diagnosed during one-year follow-up. The cancer detection rate, interval cancer rate, sensitivity, and specificity were compared using different follow-up periods: standard one-year follow-up per the American College of Radiology versus follow-up that was shortened at the next surveillance mammogram if less than one year (truncated follow-up). Performance measures were calculated overall and by indication (screening, evaluation for breast problem, and short interval follow-up). Results: Of 117971 surveillance mammograms, 20% (n = 23533) were followed by another surveillance mammogram within one year. Standard follow-up identified 1597 mammograms that were associated with second breast cancers. With truncated follow-up, the breast cancer status of 179 mammograms (11.2%) was revised, resulting in 1418 mammograms associated with unique second breast cancers. The interval cancer rate decreased with truncated versus standard follow-up (3.6 versus 4.9 per 1000 mammograms, respectively), with a difference (95% confidence interval [CI]) of -1.3 (-1.6, -1.1). The overall sensitivity increased to 70.4% from 63.7%, for the truncated versus standard follow-up, with a difference (95% CI) of 6.6% (5.6%, 7.7%). The specificity remained stable at 98.1%. Conclusion: Truncated follow-up, if less than one year to the next surveillance mammogram, enabled second breast cancers to be associated with a single preceding mammogram and resulted in more accurate estimates of diagnostic performance for national benchmarks.

• Education of Primary School Mathematics
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• v.12 no.1
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• pp.39-55
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• 2009

For this study, the 'Game Activities' lessons presented in the math textbooks from the 1st grade to the 6th were examined in terms of learning materials, the learning members' make-up, the playing structures, and the relation with the contents. In addition, the survey by means of questionnaires was conducted to analyze the actual condition of teachers' guidance in the field. The findings from this research were as follows: First, as for the activities presented in the textbooks, it turned out that too much emphasis is placed upon plays mainly using learning materials such as cards and dice played by teams of two. In addition, there have been shown negative aspects in various ways of plays putting too much emphasis on certain types of plays such as and structures. As for the relation with the contents, although lots of efforts were taken to connect the playing activity to the lesson contents, there were units presenting plays based on the preceding lesson's repeated activity, ones that have weak link with the contents. Second, it turned out that the teachers had negative attitude on the guidance using the 'Game Activities' lesson, although they were aware of the effects of playing in math learning. This seemed to result from the delicate variety and insufficient preparation for the play. Besides, the findings indicate that the appreciation and activity of the 'Game Activities' lesson presented as a way of performance evaluation. for play need to be provided in school or classrooms for teachers and students to make good use of them.

• Journal of KIISE:Databases
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• v.30 no.3
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• pp.296-309
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• 2003

One of commercial applications of mobile computing is ATIS(Advanced Traveler Information Systems) in ITS(Intelligent Transport Systems). In ATIS, a primary mobile computing task is to compute the shortest path from the current location to the destination. In this paper, we have studied the shortest path re-computation problem that arises in the DRGS(Dynamic Route Guidance System) in ATIS where the cost of topological digital road map is frequently updated as traffic condition changes dynamically. Previously suggested methods either re-compute the shortest path from scratch or re-compute the shortest path just between the two end nodes of the edge where the cost change occurs. However, these methods we trivial in that they do not intelligently utilize the previously computed shortest path information. In this paper, we propose an efficient approximate shortest path re-computation method based on the dynamic window scheme. The proposed method re-computes an approximate shortest path very quickly by utilizing the previously computed shortest path information. We first show the theoretical analysis of our methods and then present an in-depth experimental performance analysis by implementing it on grid graphs as well as a real digital road map.