• Journal of ILASS-Korea
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• v.27 no.1
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• pp.42-49
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• 2022

Flash boiling occurs in a couple of modern engineering systems and understanding its mechanism is important. In this experimental study, discharge coefficient of flash boiling spray from simple orifice nozzle was measured, and backlight imaging was acquired at injection pressure to 6.0 bar and temperature to 163℃ for the purpose. Pressurized water by pump was used for working fluid and was heated by electric heater and ejected through simple orifice nozzle diameter of 0.5 mm. High speed camera with long distance microscope was used for backlight imaging in two FoV having magnification of 3.3 and 0.64. The decrease of discharge coefficient according to degree of superheating and evolution of flash boiling spray imaged at various pressure and temperature were explained by the pressure field inside the injector.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2020.11a
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• pp.172-175
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• 2020

최근 스마트시티, 자율 주행 자동차 등 기계에 의해 소비되는 영상 데이터의 양이 증가함에 따라 기계의 임무 수행 능력을 향상시킬 수 있는 압축기술이 필요하게 되었다. 그런데, 전통적 방식의 영상 코덱은 사람의 인지 화질 특성을 고려해 개발된 기술이기 때문에 기계의 임무 수행에 필수적인 정보 외에도 불필요한 정보가 존재한다. 따라서 사람이 아닌 기계의 임무 수행에 대해 효율적으로 영상을 압축하기 위한 비디오 코덱 기술이 필요하다. 이와 관련하여, 최근 MPEG에서 Video Coding for Machines라는 영상 압축기술에 대한 표준화가 논의되고 있다. 본 논문에서는 기계를 위한 영상 압축기술의 연구배경과 연구를 통해 전통적인 영상 압축 코덱 방식과 neural network 기반 압축 코덱 방식에 대해 각각의 방식이 머신비전 임무를 수행한 정확도를 기준으로 영상 압축성능을 비교해 효율적인 압축 코덱 방식에 대해 분석한다.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.5
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• pp.92-99
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• 1997

A model reference adaptive control(MRAC) theory is very useful for controlling a plant of which the parameters are unknown or vary during operation usint only input-output signal of plant. In this study, 2' nd order discreter time MRAC controller is designed for an electrohydraulic position control system which is represented with nonlinear mathematical model and the least square method is adopted for the para-meter adjustment law. This control algorthm is applied to the position control of electrohydraulic servosystem through computer simulation and the effect of the change of load, sampling time upon the performance following reference model and upon the performance of estimating plant parameters are examined.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.6_2
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• pp.1127-1134
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• 2023

In this paper, we proposes a study on air gap control for magnetic levitation of transverse flux permanent magnet electromagnets. In general, mechanical systems have a high failure rate of bearings. Bearings in particular are problematic because they have high surface wear rate and degradations. To solve this problem, replacing the bearing with a magnetic levitation electromagnet system can provide lightweight and efficiency improvements. However, precise air gap control is essential to control the magnetic levitation electromagnet system. Therefore, in this paper, we identify the instable cause of gap control through a mathematical modeling and verify through experiment a control algorithm that can use compensation.

• Proceedings of the Korean Society of Crop Science Conference
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• 2021.04a
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• pp.39-39
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• 2021

• Journal of the Korea Convergence Society
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• v.10 no.9
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• pp.75-84
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• 2019

This study aimed to identify the factors affecting the nursing performance and the convergence relationships of leisure satisfaction, job stress, and nursing performance among nurses. Participants included 150 nurses working at 2 hospitals in C city from August 3 to September 15, 2018. The data were analyzed using descriptive statistics, independent t-test, one-way ANOVA with Scheffe's test, Pearson correlation coefficients, and multiple regression by SPSS 23.0 program. Nursing performance were significantly differences in age (F=4.78, p=.003), marital status (F=2.74, p=.007), length of clinical career (F=3.34, p=.012), and health condition (F=5.23, p=.002). Nursing performance was a positively correlated with leisure satisfaction (r=.32, p<.001) and a negatively correlated with job stress (r=-19, p=.020), and job stress was a negatively correlated with leisure satisfaction (r=-.32, p=.005). The factors affecting the nursing performance of clinical nurses were age (${\beta}=.20$, p=.008) and leisure satisfaction (${\beta}=.28$, p<.001), and these variables explained about 19.6% of the variance in nursing performance. In order to improve nursing performance, it is necessary to provide working environment and institutional support for increasing leisure satisfaction and reducing job stress and age-differentiated approaches.

• Journal of Korean Physical Therapy Science
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• v.28 no.2
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• pp.30-39
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• 2021

Background: The purpose of this study was to compare the differences in gait and mobility according to the types of assistive device for ankle joint including ankle foot orthosis (AFO), non-elastic tape, elastic tape, and high ankle shoes in chronic hemiplegic stroke survivors. Design: A cross-over design. Methods: Twelve hemiplegic stroke survivors participated in this study, and they walked under 5 different conditions including bare feet, wearing a AFO, wearing a non-elastic tape, wearing a elastic tape, and wearing a high ankle shoes. During the participants walked, the spatio-temporal gait analysis and mobility examinations were performed. For the spatio-temporal gait analysis (gait velocity and cadence, step length, stride length, and single and double leg support time) and mobility examinations, the gait mat, TUG and TUDS were used. Results: As s results, on the AFO, non-elastic tape, elastic tape, and high ankle shoes, there were significantly differences in the all spatio-temporal gait parameters, TUG, and TUDS compared to barefoot (p<0.05). In particular, all spatio-temporal gait parameters, TUG, TUDS were significantly improved with AFO compared to barefoot. TUG was significantly improved with AFO compared to non-elastic tape, TUG and TUDS were significantly improved with AFO compared to elastic tape, gait velocity was significantly improved with non-elastic tape compared to high ankle shoes, gait velocity and TUG were significantly improved with elastic tape compared to high ankle shoes, and TUDS was significantly improved with non-elastic tape compared to elastic tape. Conclusion: The AFO, non-elastic tape, elastic tape, and high ankle shoes showed a positive effect on gait and mobility compared to barefoot, and among them, wearing AFO was most effective for improving gait and mobility of chronic hemiplegic stroke survivors.

• The Journal of the Korea Contents Association
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• v.21 no.12
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• pp.155-166
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• 2021

The purpose of this study was to investigate the effects of empathy and communication skills on nursing problem-solving skills of nursing students who received simulation classes. The subjects of this study were composed of 234 students in the 3rd and 4th grades who already took simulation classes. The data was collected from April 26th to May 10th, 2021. The data was analyzed with the SPSS WIN 25.0 program. Descriptive statistics and mean differences were analyzed using an independent t-test, one-way ANOVA, Pearson's correlation coefficient, and multiple regression. As a result, the average points of empathy skills were 5.29 out of 7, communication skills were 3.30 out of 5, and problem-solving skills were 3.51 out of 5. Empathy skills and communication skills were positively correlated with problem-solving skills. The predicting factors on problem-solving skills were empathy and communication skills, on-campus practice period, and gender in order. The explanatory power of these factors was 64.6%. In conclusion, in order to improve the problem-solving ability of nursing students, a strategy is needed to enhance empathy and communication skills through continuous simulation classes.

• Korean Architects
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• no.9 s.198
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• pp.5-19
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• 1985

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2020.10a
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• pp.77-77
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• 2020