• Journal of Aerospace System Engineering
• /
• v.13 no.1
• /
• pp.38-46
• /
• 2019

There is a growing interest in engine diagnostic technology for gas turbine engines. An engine simulation program, precisely simulating the engine performance, is required in order to apply it to the engine diagnosis technology for engine health monitoring. In particular, the simulation program can predict not only design point performance but also off-design point and partial load performance in accurate. So the engine simulation program for the 2-spool separate flow type turbofan engine was developed and the JT9D-7R4G engine of PW(Pratt & Whitney) was analyzed. The steady-sate performance analysis is conducted at both design and off-design points in flight path and the differences between analysis results of takeoff and cruise conditions are compared. The effect of Reynold's correction method was analyzed as a scaling method of the engine component performance. The simulation results was compared with NPSS.

• Journal of Korean Academy of Nursing
• /
• v.49 no.5
• /
• pp.631-642
• /
• 2019

Purpose: This study aimed to predict the influencing factors and the consequences of near miss in nurses' medication error based upon Salazar & Primomo's ecological system theory. Methods: A convenience sample of 198 nurses was recruited for the cross-sectional survey design. Data were collected from July to September 2016. Using the collected data, the developed model was verified by structural equation modeling analysis using SPSS and AMOS program. Results: For the fitness of the hypothetical model, the results showed that $x^2$ ($x^2=258.50$, p<.001) was not fit, but standardized $x^2$ ($x^2/df=2.35$) was a good fit for this model. Additionally, absolute fit index RMR=.06, RMSEA=.08, GFI=.86, AGFI=.81 reached the recommended level, but the Incremental fit index TLI=.82, CFI=.85 was not enough to reach to the recommended level. With the path diagram of the hypothetical model, caution (${\beta}=-.29$ p<.001), patient safety culture (${\beta}=-.20$, p=.041), and work load (${\beta}=.18$, p=.037) had a significant effect on the near miss experiences in nurses' medication error, while fatigue (${\beta}=-.06$, p=.575) did not affect it. Moreover, the near miss experience had a significant effect on work productivity (${\beta}=-.25$, p=.001). Conclusion: These results have shown that to decrease the near miss experience by nurses and increase their work productivity in hospital environments would require both personal and organizational effort.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.12 no.1
• /
• pp.376-386
• /
• 2020

The aim of this study was to develop a new efficient strategy that uses the Vector form Intrinsic Finite-element (VFIFE) method to conduct the static and dynamic analyses of marine pipes. Nonlinear problems, such as large displacement, small strain, and contact and collision, can be analyzed using a unified calculation process in the VFIFE method according to the fundamental theories of point value description, path element, and reverse motion. This method enables analysis without the need to integrate the stiffness matrix of the structure, because only motion equations of particles established according to Newton's second law are required. These characteristics of the VFIFE facilitate the modeling and computation efficiencies in analyzing the nonlinear dynamic problem of flexible pipe with large deflections. In this study, a three-dimensional (3-D) dynamical model based on 3-D beam element was established according to the VFIFE method. The deep-sea flexible pipe was described by a set of spatial mass particles linked by 3-D beam element. The motion and configuration of the pipe are determined by these spatial particles. Based on this model, a simulation procedure to predict the 3-D dynamical behavior of flexible pipe was developed and verified. It was found that the spatial configuration and static internal force of the mining pipe can be obtained by calculating the stationary state of pipe motion. Using this simulation procedure, an analysis was conducted on the static and dynamic behaviors of the flexible mining pipe based on a 1000-m sea trial system. The results of the analysis proved that the VFIFE method can be efficiently applied to the static and dynamic analyses of marine pipes.

• Journal of dental hygiene science
• /
• v.21 no.2
• /
• pp.86-95
• /
• 2021

Background: This study aimed to investigate the effects of department satisfaction and career maturity on the perceived health status, relationship, and self-efficacy of dental hygiene college students based on Alderfer's existence-relationship-growth theory. Methods: We obtained convenience samples of dental hygiene students in Daejeon and Chungnam areas; 241 questionnaires were collected from 250 persons considering the dropout rate and used for the final analysis except for 9 careless responses. The differences in perceived health status, relationship, self-efficacy, department satisfaction, and career maturity according to general characteristics were analyzed using a t-test, one-way analysis of variance and Pearson's correlation coefficients. Moreover, structural equation modeling was performed to confirm the variables. GFI, AGFI,CFI, RMR, RMSEA, TLI, and NFI indices were calculated to verify the fitness of the path model. Results: There were significant differences in self-efficacy, department satisfaction, career maturity according to grade, and significant differences in academic performance for all variables except relationship. The school system also had a significant effect on department satisfaction. Perceived health status, relationship, self-efficacy, department satisfaction, and career maturity demonstrated statistically significant positive correlations (p<0.05). The factors affecting department satisfaction were relationship and self-efficacy. The indirect and total effects of perceived health status and relationship on career maturity were not statistically significant; however, the indirect and total effects of self-efficacy on career maturity were statistically significant. Conclusion: It is necessary to develop teaching methods according to student management plans for dental hygiene by comprehensively perceived health status, relationship, and self-efficacy affecting department satisfaction and career maturity.

• The Journal of the Korea Contents Association
• /
• v.21 no.5
• /
• pp.422-434
• /
• 2021

This study aims to explore the structural relationships among experiences of being heard in home and school settings, self-esteem, and human rights awareness. Among the 2017 NYPI Cross-sectional Survey on the Rights of Youth & Children, 6,405 middle and high school students (47.8% females) were used to conduct a structural equation modeling using Mplus. It was found that children who experience being heard in the home or school display higher levels of self-esteem and awareness of human rights. It was also found that self-esteem is more likely to increase awareness of human rights. Self-esteem was also found to mediate the pathway between the experience of being heard at home or school and human rights awareness. In addition, there was no significant difference in path coefficients depending on whether they received human rights education. Practical implications for promoting home and school environments where children's opinions can be heard were discussed.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.16 no.2
• /
• pp.726-741
• /
• 2022

The purpose of this study is to provide instructive theoretical models for art (music) education institutions especially when unpredictable risks, such as pandemics, occur again. Based on the customer behavior theory of the business-to-business-to-customer (B2B2C) platform, and in combination with the technology acceptance model (TAM) and expectation confirmation model (ECM), this study proposes an online education model from the perspective of art education. The framework is based on the three decision-making processes of the customer, and includes the product owner, content owner, and customer area. This paper highlights the factors that influence customers in making decisions when art education institutions are product owners. Regression analysis was introduced to study the factors influencing the expectation confirmation, and the overall fitting testing and six hypotheses testing of 385 effective samples were performed using the structural equation modeling (SEM). The results show that the course-design and after-service positively influenced the expectation confirmation, and the domain image positively influenced the continuance behavior. Negative emotions skipped the mediator (expectation confirmation) and directly exerted a significant negative impact on customers' willingness to continue system usage (continuance behavior). In addition, expectation confirmation positively influenced continuance behavior. The paths of detailed items comprising course-design, after-service, and negative emotion were also analyzed and discussed. In this path analysis, ordinary art learners did not believe that AI partners can play a very good auxiliary role. The findings contribute to the scope of information systems acting as an art education platform academically, and provide effective and theoretical support for the actual operation of art education institutions.

• Journal of Digital Convergence
• /
• v.19 no.5
• /
• pp.269-277
• /
• 2021

The purpose of the study is to explore the effect of university's managing and system support in online classes on learning participation mediated by learning presence and to examine the structural relationship between the factors. In order to achieve the purpose of the study, 135 students who take online "College English 2" classes were analyzed for the fitness of the research model and the path and structural analysis through a confirmative factor of the structural equation model. As a result of the study, first, the university's managing support for online class showed a positive effect to learning presence. Second, the university's managing support for online classes completely mediated learning presence and had a positive effect on learning participation. This study can clarify the structural relationship between environmental factors which are online class support and learners' characteristics in university online class, learning presence, and learning participation and can broaden the understanding of learning participation in online classes. It gives the implications that should be considered in teaching and learning design.

• Current Optics and Photonics
• /
• v.6 no.2
• /
• pp.171-182
• /
• 2022

A single-photon laser and mid-wave infrared (MWIR) common aperture optical system was designed and developed to detect and range a long-distance civil aviation aircraft. The secondary mirror of the Ritchey-Chretien (R-C) optical system was chosen as a dichroic lens to realize the design of a common aperture system for the laser and MWIR. Point spread function (PSF) ellipticity was introduced to evaluate the coupling efficiency of the laser receiving system. A small aperture stop and narrow filter were set in the secondary image plane and an afocal light path of the laser system, respectively, and the stray light suppression ability of the small aperture stop was verified by modeling and simulation. With high-precision manufacturing technology by single point diamond turning (SPDT) and a high-efficiency dichroic coating, the laser/MWIR common aperture optical system with a 𝜑300 mm aluminum alloy mirror obtained images of buildings at a distance of 5 km with great quality. A civil aviation aircraft detection experiment was conducted. The results show that the common aperture system could detect and track long-distance civil aviation aircraft effectively, and the coverage was more than 450 km (signal-to-noise ratio = 6.3). It satisfied the application requirements for earlier warning and ranging of long-range targets in the area of aviation, aerospace and ground detection systems.

• IEMEK Journal of Embedded Systems and Applications
• /
• v.17 no.1
• /
• pp.33-40
• /
• 2022

With the recent increase in the development of military drones, they are adopted and used as the combat system of battalion level or higher. However, it is difficult to use drones that can be used in battles below the platoon level due to the current conditions for the formation of units in the Korean military. In this paper, therefore, we developed a program drones equipped with a thermal imaging camera and LiDAR sensor for reconnaissance and exploration that can be applied in battles below the platoon level. Using these drones, we studied the possibility and feasibility of drones for small-scale combats that can find hidden enemies, search for an appropriate detour through image processing and conduct reconnaissance and search for battlefields, hiding and cover-up through image processing. In addition to the purpose of using the proposed drone to search for an enemies lying in ambush in the battlefield, it can be used as a function to check the optimal movement path when a combat unit is moving, or as a function to check the optimal place for cover-up or hiding. In particular, it is possible to check another route other than the route recommended by the program because the features of the terrain can be checked from various viewpoints through 3D modeling. We verified the possiblity of flying by designing and assembling in a form of adding LiDAR and thermal imaging camera module to a drone assembled based on racing drone parts, which are open source hardware, and developed autonomous flight and search functions which can be used even by non-professional drone operators based on open source software, and then installed them to verify their feasibility.

• Journal of Korea Trade
• /
• v.27 no.4
• /
• pp.77-100
• /
• 2023

Purpose - Using the Model of Goal-Directed Behavior (MGB), this study identifies the critical factors that influence consumer intention to purchase an electric vehicle (EV). This study also provides differentiated policy implications to the Korean and Chinese governments and EV-related companies for the expansion of the EV market in both countries by comparing consumers' perceptions of EV purchase intentions. Design/methodology - Our extended MGB model adds to the standard model consideration of financial incentives, perceived risks, and environmental concerns. An online survey was conducted of Korean and Chinese consumers. Based on the collected responses, all tested hypotheses were verified using PLS-SEM (Partial Least Squares-Structural Equation Modeling). Differences in the path analysis results between Korea and China were compared and verified using Henseler's MGA (multi-group analysis), the parametric test, and the Welch-Satterthwaite test. Findings - The most critical factor that influences the intent to purchase an EV in consumers from both countries is personal desire. PBC and SN were identified as the critical factors that respectively increase personal desire in Korea and China. In addition, in Korea, among the three factors EC, FIP, and PR, environmental concerns were found to have the most significant impact on attitudes and purchase intention. In contrast, in China, economic factors (specifically financial incentives) had greater importance than environmental issues. Originality/value - This study has academic contributions in that it presents a new research model that includes financial incentive policies, environmental concerns, and perceived risk variables based on the MGB to explore consumers' purchase intentions. This study can also make a practical contribution in that it provides some meaningful implications to the governments and EV-related companies of both countries based on the differences in the analysis results of the Korean and Chinese markets.