• Journal of Advanced Navigation Technology
• /
• v.25 no.3
• /
• pp.203-210
• /
• 2021

In many metropolitan cities around the world, ground and underground transportation networks are saturated due to urbanization. In addition, regulations on carbon emissions to prevent global warming are becoming stricter, and eVTOL, which will be operating in complex cities, is gaining popularity as the next generation of eco-friendly transportation. In this study, the hover lift efficiency and disc loading of eVTOLs for each type were calculated by classifying eVTOLs into following types: multicopter, lift+cruise, and vectored thrust. In addition, using the aerodynamic analysis programs OpenVSP, Fluent and Javaprop, the specific battery energy required for the smooth operation of eVTOL, which will be realized in the near future, was calculated and analyzed base on reports published by Uber and airworthiness authorities of each country.

• Journal of the Society of Naval Architects of Korea
• /
• v.57 no.5
• /
• pp.262-270
• /
• 2020

An outdoor free-running model test system was designed for assessing ship maneuverability with test uncertainty. The test model was a surface combatant of tumblehome hull geometry. The straight forward tests were conducted first to obtain the relationship between the propeller revolution rate and advance speed. During the outdoor tests, the propeller revolution rate to achieve a certain Froude number condition was higher than that in the indoor free-running model tests. Turning circle and zigzag tests for evaluating ship maneuverability criteria were carried out at the propeller revolution rate determined by the straight forward test results. The random and systematic standard uncertainties of maneuvering criteria were obtained by repeated tests and comparison with the indoor free-running model test results, respectively. The test uncertainty was largely dominated by the systematic standard uncertainty, while the random standard uncertainty was small with good repeatability.

• Journal of Advanced Navigation Technology
• /
• v.25 no.1
• /
• pp.29-39
• /
• 2021

As a means of solving traffic congestion in the downtown of large city, the interest in urban air mobility (UAM) using electric vertical take-off landing personal aerial vehicle (eVTOL PAV) is increasing. eVTOL configurations that will be used for UAM are classified by lift-and-cruise, tilt rotors, tilt-wings, tilted-ducted fans, multicopters, depending on propulsion types. This study tries to perform preliminary conceptual design for a given mission profile using reverse engineering techniques by taking the multicopter type Airbus's CityAirbus as a basic model. Wetted area, lift to drag ratio, drag coefficients were calculated using the OpenVSP which is an aerodynamic analysis software. The power required for each mission section of CityAirbus were calculated, and the corresponding battery and motor were selected. Also, total weight was predicted by estimating component weights of eVTOL.

• The Journal of the Convergence on Culture Technology
• /
• v.7 no.3
• /
• pp.463-468
• /
• 2021

In this paper, when a refractive index grating and a gain grating were simultaneously present in a DFB laser having a wavelength of 1.55 ㎛, a dielectric film coating was applied so that reflection did not occur on the right mirror surface, so that 𝜌_r=0. In case of 𝛿L>0, the characteristics of the oscillation frequency and oscillation gain were analyzed. When the grating phase of the left mirror surface continues to decrease from 𝜋, the graph lines of each mode gradually shift to the left. In case of 𝜅L=10, the threshold gain of the oscillation mode is the lowest. In this case, the mode selectivity is relatively low. From 𝜅L=0.5 to 𝜅L=6, the mode selectivity and the frequency stability are excellent. In the case of DFB lasers with an anti-reflection coated mirror, the threshold gain of the oscillation mode increases but the mode selectivity is about twice as excellent, compared with DFB lasers of having two cleaved facets.

• The Journal of the Convergence on Culture Technology
• /
• v.7 no.4
• /
• pp.267-272
• /
• 2021

This study's purpose is to investigate the effects of reading movie scripts aloud in non-face-to-face general English courses on international students' English ability in the COVID-19 era. A general English class was delivered once a week for 15 weeks to 47 international students at a Seoul-based university. The animated movie Tangled and its script were used as learning materials. Biweekly, students had to watch video lectures using the university's learning management system(LMS) and read scripts aloud through Zoom. In the video lectures, the teacher went over specific vocabulary and interpreted the movie scripts in easy Korean. For the second activity through Zoom, international students read the movie script aloud individually and in groups. The post-test revealed significant improvements in both reading and writing, as compared to the pre-test. Through the study's survey, participants exhibited positive attitudes in affective domains(understanding, satisfaction, interest, and recommendation).

• Journal of Industrial Convergence
• /
• v.19 no.6
• /
• pp.177-186
• /
• 2021

This review aims to propose a model that can reinterpret the abnormal and functional connections between cognitive processes and emotional regulations based on the neurocognitive networks for a comprehensive understanding of pathologic processes and treatment approach of depression and anxiety disorder. Through the processes of rebuilding the network model for depression and anxiety disorder, it was confirmed that depression can be said to be 'over-immersion in self-referencing' due to hyper-activation of default mode network (DMN), and anxiety disorders to be 'disconnection with self-referencing' due to hypo-activation of DMN. The attempts to link up between abnormal activation and pathological function of DMN which is thought to be involved in self-referential processing associated with self-consciousness and projection among neurocognitive networks may be another starting point that can afford to be suggestive in integrated interpretation and therapeutic approach to depression and anxiety disorder.

• The Journal of the Convergence on Culture Technology
• /
• v.7 no.4
• /
• pp.331-336
• /
• 2021

This study first examined the social meanings of typicality found in the prison, (solitary) confinement, and conduit(passage) in Peter Halley's works, in which both the prison and (solitary) confinement represent a suppressed structural framework. The former has freedom and escape excluded from it, and the latter allows for mutual regulation and connection as a space of positive mediation. Conduits are interpreted to be flexible and have the potential of creating something new through connection and communication with the outside world. The study then compared and analyzed the meanings of typicality in Halley's works and the concept of segments proposed by Gilles Deleuze and Félix Guattari as social justice in that both of them were in the same context. The findings lead to a conclusion that Halley's prison, (solitary) confinement, and conduit(passage) can be connected to a solid, flexible, and escape segment, respectively, by Deleuze and Guattari.

• The Journal of the Korea Contents Association
• /
• v.22 no.3
• /
• pp.54-61
• /
• 2022

Ship is a huge system including a variety of pipe arrangements. Pipes are installed according to the design layout, however the end poistion of pipes are not well matched owing to its measurement and construction errors. In this situation, the customized pipe fitting is frequently designed to connect with both pipes, the position of which are manually measured. This paper focused that these two coordinates are measured by point cloud from RGBD sensor and the relative transformation induced by positional and orientational differences is calculated by inverse kinematics in robotics theory. Therefore, the result applies for the methodology of the pipe connection design. The pipe coordinate that is estimated by the matching and the probabilistic RANSAC method will be verified by experiments. The kinematic design parameters are computationally calculated by using the minimum degree of freedom that connects both pipe coordinates.

• The Journal of the Convergence on Culture Technology
• /
• v.8 no.6
• /
• pp.881-889
• /
• 2022

This study is to empirically investigate the impact of product placement on purchase intention. Product placement is growing due to its advantages that it is cheaper than general advertising and free from restrictions from exposure time. Considering that, this study includes variables reflecting high importance and characteristic changes in product placement. The study selects fashion involvement, celebrity involvement, bald exposure, and exposure strength as variables reflecting the unique characteristics of product placement, observance of ethics and consumer deception as ones reflecting ethical aspects, and program popularity and media familiarity as variables reflecting means of using product placement. As a result, celebrity involvement and program popularity have a positive influence on purchase intention, and consumer deception has a negative impact. However, fashion involvement, bald exposure, exposure strength, observance of ethics, and media familiarity do not have a statistically significant impact. This study explains the results through comparison with previous studies and suggests implications based on the association between product placement and purchase intention.

• Journal of Advanced Navigation Technology
• /
• v.27 no.1
• /
• pp.77-95
• /
• 2023

In this study, the conceptual design of a tilt + stopped rotor type electric vertical take-off and landing (eVTOL) aircraft was performed using design iteration. Based on Hyundai Motor's S-A1, the mission profile was defined using the concept of urban air mobility (UAM), and configuration design and aerodynamic analysis were performed using OpenVSP and XFLR5 software. After estimating the required power for the designed eVTOL, the required performance of the battery and the maximum take-off weight (MTOW) were calculated. . It was iteratively calculated using Microsoft Excel and Visual Basic Application, and a new electric motor weight estimation formula was derived. Also, the sensitivity analyses of each design variables of an eVTOL was performed using the automated program.