• Publications of The Korean Astronomical Society
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• v.27 no.3
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• pp.39-47
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• 2012

MIRIS, Multi-purpose Infra-Red Imaging System, is the main payload of STSAT-3 (Korea Science & Technology Satellite 3), which will be launched in the end of 2012 (the exact date to be determined) by a Russian Dnepr rocket. MIRIS consists of two camera systems, SOC (Space Observation Camera) and EOC (Earth Observation Camera). During a shock test for the flight model stability in the launching environment, some lenses of SOC EQM (Engineering Qualification Model) were broken. In order to resolve the lens failure, analyses for cause were performed with visual inspections for lenses and opto-mechanical parts. After modifications of SOC opto-mechanical parts, the shock test was performed again and passed. In this paper, we introduce the solution for lens safety and report the test results.

• Journal of the Korean Society of Propulsion Engineers
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• v.6 no.2
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• pp.1-7
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• 2002

In the modern propulsion systems, requited thrust is obtained using a nozzle. Sometimes shock and induced boundary layer separation is generated in an over-expanded convergent-divergent supersonic nozzle. It occurs because the nozzle expansion ratio is too large for a given nozzle pressure ratio (NPR). This phenomenon can be explained that it redefines effective nozzle geometry, shorer nozzle geometry and lower pressure ratio, in a given pressure ratio. Numerical studies were conducted about a fixed geometry 2D nozzle in overexpanded condition and compared with Hunter's experimental result. For the numerical simulation of the supersonic nozzle, Navier-Stokes equations are considered and as a turbulent model, $\kappa$-$\varepsilon$ /$\kappa$-$\omega$ blended SST two equation turbulent model is used. The characteristics of $\lambda$-shape shock systems due to the interaction of shock and boundary layer was investigated in a low NPR. And the result of comparison of thrust value shows that a fixed geometry nozzle can cover required flight mission.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.1
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• pp.64.1-64.1
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• 2011

MIRIS (Multipurpose Infra-Red Imaging System), is a small infrared space telescope which is being developed by KASI, as the main payload of Science and Technology Satellite 3 (STSAT-3). Two wideband filters (I and H) of the MIRIS enables us to study the cosmic infrared background by detecting the absolute background brightness. The narrow band filter for Paschen ${\alpha}$ emission line observation will be employed to survey the Galactic plane for the study of warm ionized medium and interstellar turbulence. The opto-mechanical design of the MIRIS is optimized to operate around 200K for the telescope, and the cryogenic temperature around 90K for the sensor in the orbit, by using passive and active cooling technique, respectively. The engineering and qualification model of the MIRIS has been fabricated and successfully passed various environmental tests, including thermal, vacuum, vibration and shock tests. The flight model was also assembled and is in the process of system optimization to be launched in 2012 by a Russian rocket. The mission operation scenario and the data reduction software is now being developed. After the successful mission of FIMS (the main payload of STSAT-1), MIRIS is the second Korean space telescope, and will be an important step towards the future of Korean space astronomy.

• Bulletin of the Korean Space Science Society
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• 2010.04a
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• pp.37.4-37.4
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• 2010

KASI is developing the MIRIS (Multi-purpose IR Imaging System), as the main payload of Science and Technology Satellite-3 (STSAT-3). The Engineering Qualification Model (EQM) of the MIRIS has been recently fabricated, and Flight Model (FM) is now in final development stage. The system performance tests have been made mainly with EQM, and partly with FM in the laboratory, including opto-mechanics test, vibration test, thermal-vacuum test and passive cooling test down to 200K, using a thermal controlled vacuum chamber. Most of the system performance test results of the MIRIS are satisfied with the required specifications and its results were reflected in development of the FM with several revisions of the system design. In this paper, we present detailed system performance test procedures of the MIRIS and its results.

• Journal of Magnetics
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• v.20 no.1
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• pp.40-46
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• 2015

This study investigated the accuracy of magnetic resonance angiography (MRA) and computed tomography angiography (CTA) in terms of reflecting the actual vascular length. Three-dimensional time of flight (3D TOF) MRA, 3D contrast-enhanced (CE) MRA, volume-rendering after CTA and maximum intensity projection were investigated using a flow model phantom with a diameter of 2.11 mm and area of $0.26cm^2$. 1.5 and 3.0 Tesla devices were used for 3D TOF MRA and 3D CE MRA. CTA was investigated using 16 and 64 channel CT scanners, and the images were transmitted and reconstructed by volume-rendering and maximum intensity projection, followed by conduit length measurement as described above. The smallest 3D TOF MRA measure was $2.51{\pm}0.12mm$ with a flow velocity of 40 cm/s using the 3.0 Tesla apparatus, and $2.57{\pm}0.07mm$ with a velocity of 71.5 cm/s using the 1.5 Tesla apparatus; both images were magnified from the actual measurement of 2.11 mm. The measurement with the 16 channel CT scanner was smaller ($3.83{\pm}0.37mm$) than the reconstructed image on maximum intensity projection. The images from CTA from examination apparatus and reconstruction technique were all larger than the actual measurement.

• Journal of Convergence for Information Technology
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• v.9 no.4
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• pp.68-77
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• 2019

The purpose of this study is to identify the optimal model to explain safety behavioral intention according to the recognition of safety communication in cabin through comparison of Planned behavioral theory and Triandis' theory of interpersonal behavior. In order to accomplish the study purpose, research model and hypothesis were established based on the previous research. As a result of the analysis, it was found that attitude and Perceived Behavioral Control had a positive effect on the safety behavioral intention. Triandis theory shows that social factors and habits have a positive impact on safety behavioral intention. In addition, A comparison of the two models confirms that both psychological processes of recognition and emotion are accompanied by the relationship between safety information awareness and safety behavioral intention.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.2
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• pp.187-192
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• 2021

This study proposes a system for take-off in a forest or similar complex environment using an object detector. In the simulator, a raspberry pi is mounted on a quadcopter with a length of 550mm between motors on a diagonal line, and the experiment is conducted based on edge computing. As for the images to be used for learning, about 150 images of 640⁎480 size were obtained by selecting three points inside Kunsan University, and then converting them to black and white, and pre-processing the binarization by placing a boundary value of 127. After that, we trained the SSD_Inception model. In the simulation, as a result of the experiment of taking off the drone through the model trained with the verification image as an input, a trajectory similar to the takeoff was drawn using the label.

• Advances in aircraft and spacecraft science
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• v.10 no.2
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• pp.107-125
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• 2023

Drag reduction is significant research in aircraft design due to its effect on the cost of operation and carbon footprint reduction. Aircraft currently use conventional solid winglets to reduce the induced drag, adding extra structural weight. Fluidic on-demand winglets can effectively reduce drag for low-speed flight regimes without adding any extra weight. These utilize the spanwise airflow from the wingtips using hydraulic actuators to create jets that negate tip vortices. This study develops a computational model to investigate fluidic on-demand winglets. The well-validated computational model is applied to investigate the effect of injection velocity and angle on the aerodynamic coefficients of a rectangular wing. Further, the turbulence parameters such as turbulent kinetic energy (TKE) and turbulent dissipation rate are studied in detail at various velocity injections and at an angle of 30°. The results show that the increase in injection velocity shifted the vortex core away from the wing tip and the increase in injection angle shifted the vortex core in the vertical direction. Further, it was found that a 30° injection is efficient among all injection velocities and highly efficient at a velocity ratio of 3. This technology can be adopted in any aircraft, effectively working at various angles of attack. The culmination of this study is that the implementation of fluidic winglets leads to a significant reduction in drag at low speeds for low aspect ratio wings.

• Asia Marketing Journal
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• v.20 no.3
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• pp.83-103
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• 2018

The purpose of this research is to investigate the effect of customer-contact employees support on service recovery efforts. Service companies should try to prevent the service failure situation from occurring, but it is realistic that the service failure occurs due to the characteristics of the service. Service recovery efforts of service providers are important because effective responses to service failures can enhance customer satisfaction despite service failures. Social support for customer-contact employees needs to improve service recovery efforts. Specifically, this study focuses on the mediation roles of job burnout and customer orientation in relationship between social support for customer-contact employees and service recovery efforts. Social exchange theory was used as the theoretical underpinning of the research model. Based on reciprocity principle, this paper suppose that support for customer-contact employees and service recovery effort are a kind of social exchange relationship. Social supports for customer-contact employees are categorized into internal and external organization. Internal organization is POS(perceived organizational support) and external organization is customer support. The research model was tested with the data gathered from the flight attendants whose emotional labor intensity was relatively high and the service failure frequently occurred. As a result of analysis, social supports for customer-contact employees classified into organizational support, supervisor support, and customer support are found to have differential impacts on job burnout and customer orientation. It has been found that job burnout of service providers is negatively affecting service recovery efforts. On the other hand, customer orientation of service providers has a positive influence on service recovery efforts. Based on the results of the analysis, we provide practical implications for effective service recovery efforts in service failure situations, and suggest the theoretical implications to explain the process of service recovery effort. Finally, limitations of the study and directions for future research are suggested.

• Korean Journal of Remote Sensing
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• v.39 no.6_1
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• pp.1331-1339
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• 2023

In support of the National ATM Reformation and Enhancement Plan (NARAE), a trajectory-based aviation weather service is under development through the NARAE-Weather project. Specifically, weather data presented in a standardized digital format facilitates the seamless integration of digital weather data with air traffic information. Thus, this paper introduces an approach that entails structuring numerical model data to integrate aviation weather information and flight trajectory data. The extraction results using structurally transformed data showed superior performance compared to the results extracted from the original data in terms of performance, and this research is poised to enhance the safety and efficiency of airline operations.