• Journal of Korean Society of Coastal and Ocean Engineers
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• v.33 no.6
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• pp.383-390
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• 2021

The experiments in coastal engineering are very complex and a lot of components should be concerned. The experience has an important role in the successful execution. Hydraulic model experiments have been improved with the development of the wave generator and the advanced measuring apparatus. The hydraulic experiments have the advantage, that is, the stability of coastal structures and the hydraulic characteristics could be observed more intuitively rather than the numerical modelings. However, different experimental results can be drawn depending on the model scale, facilities, apparatus, and experimenters. In this study, two-dimensional hydraulic experiments were performed to suggest the guide of the test wave(random wave) generation, which is the most basic and important factor for the model test. The techniques for generating the random waves with frequency energy spectrum and the range for the incident wave height [(H_S)_M/(H_S)_T = 1~1.05] were suggested. The proposed guide for the test wave generation will contribute to enhancing the reliability of the experimental results in coastal engineering.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.41 no.6
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• pp.687-695
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• 2021

With the recent occurrence of large-scale earthquakes in Korea, the importance of seismic design has greatly increased. Seismic design standards stipulate that dynamic time history analysis be performed for important or special structures. In the seismic analysis and design of such structures, determining a rational design input seismic wave is a very important factor in ensuring the reliability of the analysis and design. In the seismic design standards, rational design seismic waves must reflect the characteristics of the area (fault) and satisfy the design response spectrum for each seismic performance level. This requirement can be partially satisfied by modifying the actual seismic wave measured in the area (fault) according to the design response spectrum. In this study, a method of correcting and generating seismic wave time histories according to the design response spectrum based on actual measured seismic waves using the harmonic wavelet transform was proposed. To examine the applicability of the proposed technique, the technique was applied to earthquakes of magnitude 5.8 and 5.4, respectively, that occurred in Gyeongju (2016) and Pohang (2017), and the seismic wave time histories corresponding to the design response spectrum were modified and generated.

• Journal of Digital Convergence
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• v.20 no.4
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• pp.715-724
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• 2022

The purpose of this study was investigates the effects of perception the importance of patient safety management, professional autonomy and safety climate on patient safety nursing activity on hospital nurses. Participants were 211 nurses working in 4 general hospitals. Data were collected with structured questionnaires from January 11 to January 25, 2021. Data were analyzed descriptive statistics, t-test, ANOVA, Pearson's correlation coefficient and stepwise multiple regression with SPSS 21.0 program. Factor affecting the patient safety nursing activity were safety climate(β=.297, p<.001), perception the importance of patient safety management(β=.287, p<.001), and work place(β=.169, p=.004). In summary, in order to promote patient safety nursing activities, it is necessary to develop and apply educational programs considering the work of nurses' working place and various characteristics, improve perception the importance of patient safety, and positive safety climate. This study is meaningful in providing basic data for the development of programs related to the promotion of patient safety nursing activities for hospital nurses.

• Journal of Industrial Convergence
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• v.20 no.3
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• pp.73-79
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• 2022

The purpose of this study was to examine the relationship between parental participation motivation, satisfaction, and intention to reuse children with developmental disabilities using psychomotor centers. To this end, a questionnaire survey was conducted on the parents of children participating in psycho-exercise programs at a private developmental disability center located in the metropolitan area. The collected data was 188 copies, and the causal relationship was verified through descriptive statistics, factor analysis and reliability analysis, correlation analysis and regression analysis. As a result of the analysis, the following conclusions were obtained. First, in the relationship between parental participation motivation and satisfaction with regard to psychological exercise participation of children with developmental disabilities, only pleasure and social factors were significant in use satisfaction, and only social, health and physical fitness factors in performance satisfaction showed a significant influence. Second, in the relationship between participation motivation and intention to reuse, there were significant influences on pleasure, skill development and sense of achievement, and social factors. Third, in the relationship between satisfaction and intention to reuse, intention to reuse was significantly explained in factors of satisfaction with use and satisfaction with performance. In order to increase the reuse rate of psychomotor centers in the future, it is judged that additional analysis is necessary in addition to the measurement variables of this study.

• Journal of the Korean Geosynthetics Society
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• v.20 no.4
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• pp.19-32
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• 2021

In this study, evaluation and consideration of domestic/overseas design, construction, and quality control performed by the authors on the deep cement mixing method were performed, and improvements for the development of the DCM method were suggested in the future. As a result of this study, it was found that the cross-sectional area correction for strength is required during the laboratory test of mix proportion, and caution is required because the extrapolation method may lead to different results from the actual one. Applicable design methods should be selected in consideration of both the improvement ratio and the type of improvement during design, and it was confirmed that the allowable compressive strength to which the safety factor was applied refers to the standard value for stability review and not the design parameters. In the case of the stress concentration ratio, rather than applying a conventional value, it was possible to perform economical design by calculating the experimental and theoretical stress concentration ratio reflecting the design conditions. In the case where pre-boring is expected during construction, if the increased water content is not large compared to the original, there were cases where a major problem did not occur even if the result that did not consider the increase in water content was used. In addition, it was confirmed that when the ratio of the top treatment length to the improved length is high, a small amount of design cement contents per unit length can be injected during construction. In the case of quality control, it was evaluated that D/4~2D/4 for single-axis and D/4 point for multi-axis were optimal for coring of grouting mixtures. As an item for quality control, it is judged that the standard that considers the TCR along with the unconfined compressive strength of grouting mixtures is more suitable for the domestic situation.

• Journal of the Korean Applied Science and Technology
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• v.38 no.6
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• pp.1667-1677
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• 2021

In this study, we tried to investigate the relationship between the cosmetology major student's major satisfaction and the professionals by analyzing the effect of the cosmetology major student's major satisfaction on the beauty professional hall. Research Results It was found that there is a correlation (p <0.001) between the degree of satisfaction of college students in the hair beauty department and the beauty professionals (p <0.001), and the satisfaction of the department is "specialty" t = 4.625 (p =). .000),'Occupational recognition' t = 3.152 (p = .002), major value is'specialty' t = 2.330 (p = .021),'professional activity' t = 2.438 (p = .015), 'Occupation recognition' t = 4.843 (p = .000), university student activity adaptation is a subordinate factor of the cosmetology profession, "professional activity" t = 2.746 (p = .006), "occupation recognition" t = 4.303 ( Appearing as p = .000), it was found that the degree of satisfaction of college students in the hair beauty department has a significant effect on beauty professionals. For cosmetology college students, major satisfaction not only leads to satisfaction with the university and department, but also to self-satisfaction and cosmetology job confidence, allowing them to adapt to social life with a positive impact, and cosmetologists are hair With the values and attitude toward the beauty profession, you will be able to become a professional officer when you are a university student majoring in cosmetology. Through the research results, the formation of a positive professional hall for college students majoring in hair beauty and the satisfaction of the major will be enhanced, and the self-development of students, as well as professors and educational relations, will be established so that beauty professionals can be established through correct theory and practical education. Education and continued guidance on the professional ethics and values of the person is considered necessary.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.47 no.4
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• pp.273-280
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• 2021

The water resistance is important factor for sunscreen formulations. Generally a sunscreen cream was formulated by a water-in-oil (W/O) emulsion. In the W/O emulsion system, silicone oils are added to improve the texture of formulations. Silicone oils have low compatibility with organic sunscreen agent, causing problems with the stability in emulsion. In this study, the compatibility between various oils in the W/O emulsion was derived numerically using Hansen solubility parameter (HSP) at first. HSP is represented a dispersion degree, a polarity, and a hydrgen bond in a composition. In this study, various emulsions were prepared according to the types of oils with different HSP values and then monitored by a viscosity and morphology according to the time and temperature. The HSP values of components and the experimental results have similar activities for the stability of emulsions. HSP made it easy to select oil with high compatibility. When the compatibility of the oil phase in the W/O emulsion was high, the viscosity change over time was small. The stability was improved under the freeze-thaw cycle (-15 ℃ ~ 45 ℃). In the future, if the composition of the ingredients is optimized through HSP, it is expected that it will be helpful in the development of W/O type sunscreen formulations that are excellent in use and stability.

• Journal of Korean Neurosurgical Society
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• v.65 no.4
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• pp.549-557
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• 2022

Objective : This study analyzed the risk factors in patients who developed distal junctional kyphosis (DJK) after posterior cervical fusion. Methods : We retrospectively analyzed the clinical and radiographic outcomes of 64 patients, aged ≥18 years (51 and 13 male and female patients, respectively), who underwent single-staged multilevel (3-6 levels) posterior cervical fusion surgery due to multiple cervical spondylotic myelopathy. The surgeries were performed by a single spinal surgeon between January 2012 and December 2017. Demographic data, clinical outcomes, and radiological results were collected. We divided the patients into a DJK group and a non-DJK group according to the presence of DJK and investigated the risk factors by comparing the differences between the two groups. Results : Of the 64 patients, 13 developed DJK. No significant differences in clinical results were observed between the two groups before and immediately after the surgery. At the final follow-up, a higher visual analog score for neck pain was observed in the DJK group compared to the non-DJK group (p<0.01). The DJK group had a significantly lower T1 slope and a significantly higher C2-7 sagittal vertical axis (SVA) before surgery compared to the non-DJK group (p=0.03 and p<0.01, respectively). Immediately after surgery, the difference between the two groups decreased and no significant difference was observed. However, at the last follow-up, a significantly higher C2-7 SVA was observed in the DJK group (p<0.01). At the last follow up, there is no discrepancy in T1S-CL. In multiple logistic regression analysis, preoperative higher C2-7 SVA and preoperative lower T1 slope were identified as independent risk factors (p=0.03 and p<0.01, respectively). As a result, it was confirmed that DJK occurred along the process of returning to preoperative values. Conclusion : DJK can be considered to be caused by cervical misalignment due to excessive change in the surgical site in patients with low T1 slope and high C2-7 SVA before surgery. This also affects the clinical outcome after surgery. It is recommended to refrain from excessive segmental lordosis changes during multilevel cervical post fusion surgery, especially in patients with a small preoperative T1 slope and a large SVA value.

• Journal of Space Technology and Applications
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• v.1 no.1
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• pp.23-32
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• 2021

The high-level Space Situational Awareness (SSA) objective is to provide to the users dependable, accurate and timely information in order to support risk management on orbit and during re-entry and support safe and secure operation of space assets and related services. Therefore the risk assessment for the re-entry of space objects should be managed nationally. In this research, the Software for Re-Entry Prediction of space objects (SREP) was developed for national SSA system. In particular, the rate of change of the drag coefficient is estimated through a newly proposed Drag Scale Factor Estimation (DSFE), and is used for high-precision orbit propagator (HPOP) up to an altitude of 100 km to predict the re-entry time and position of the space object. The effectiveness of this re-entry prediction is shown through the re-entry time window and ground track of space objects falling in real events, Grace-1, Grace-2, Tiangong-1, and Chang Zheng-5B Rocket body. As a result, through analysis 12 hours before the final re-entry time, it is shown that the re-entry time window and crash time can be accurately predicted with an error of less than 20 minutes.

• Journal of the Korea Society for Simulation
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• v.31 no.1
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• pp.29-41
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• 2022

As one of the alternatives to solve the problem of unstable food supply and demand imbalance caused by abnormal climate change, the need for plant factories is increasing. Airflow in plant factory is recognized as one of important factor of plant which influence transpiration and heat transfer. On the other hand, Digital Twin (DT) is getting attention as a means of providing various services that are impossible only with the real system by replicating the real system in the virtual world. This study aimed to develop a digital twin model for airflow prediction that can predict airflow in various situations by applying the concept of digital twin to a plant factory in operation. To this end, first, the mathematical formalism of the digital twin model for airflow analysis in plant factories is presented, and based on this, the information necessary for airflow prediction modeling of a plant factory in operation is specified. Then, the shape of the plant factory is implemented in CAD and the DT model is developed by combining the computational fluid dynamics (CFD) components for airflow behavior analysis. Finally, the DT model for high-accuracy airflow prediction is completed through the validation of the model and the machine learning-based calibration process by comparing the simulation analysis result of the DT model with the actual airflow value collected from the plant factory.