• Journal of Korean Society of Industrial and Systems Engineering
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• v.41 no.4
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• pp.59-69
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• 2018

This study deals with the case study on the pallet quantity determination problem for the flexible manufacturing system producing 32 different types of aircraft wing ribs which are major structures of an aircraft wings. A Korean company has constructed the WFMS (wing rib flexible manufacturing system) that is composed of several automated equipments such as the 5-axis machining centers, the RGV (rail guided vehicles)s, the AS/RS (automated storage and retrieval system), the loading/unloading stations, and so on. Pallets play a critical role in the WFMS to maintain high system utilization and continuous work flow between 5-axis machining machines and automated material handling devices. The discrete event simulation method is used to evaluate the performance of the WFMS under various pallet mix alternatives for wing rib manufacturing processes. Four performance measures including system utilization, throughput, lead-time and work in process inventory level are investigated to determine the best pallet mix alternative. The best pallet mix identified by the simulation study is adopted in setting up and operating a real Korean aircraft parts manufacturing shop. By comparing the real WFMS's performances with those of the simulation study, we discussed the cause of performance difference observed and the necessity of developing the CPS (cyber physical system).

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.7
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• pp.479-488
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• 2019

A cruise missile uses wings and a jet engine like an airplane to reach the target after cruising a considerable distance. An integrated design of a cruise missile based on radar cross section (RCS) reduction and enhanced aerodynamic performance is indispensable, since it must be able to fly long-distance at subsonic speed without being detected by enemy radar. In this study, we designed a Taurus-type cruise missile and analyzed its RCS and aerodynamic characteristics using the physical optics (PO) technique and the Navier-Stokes CFD code. As a result, we obtained the optimal shape of cruise missile with improved aerodynamic performance and reduced RCS.

• Proceedings of the National Institute of Ecology of the Republic of Korea
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• v.2 no.1
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• pp.26-31
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• 2021

Reproduction and molt are costly processes in avian life histories. These two fitness-related traits are expected to be under one of physiological trade-offs. Age-related molt is known to be higher in young birds than that in adults presumably due to the cost of reproduction in adults. The present study partially replicated a previous study using a non-invasive method of seasonal wing feather loss instead of capture-inspection for molting progress in oriental storks (Ciconia boyciana). We first examined characteristics of the known six wing feather types (i.e., primaries [P], primary coverts [PC], secondaries [S], secondary coverts [SC], and tertials [T]) from two specimens with four wings. Results were utilized as references for further investigation. We then collected a total of 3,807 wing feathers shedded by 61 captive storks for one year and classified them into six wing feather types based on the reference with structures of vane (i.e., how asymmetrical) and calamus (i.e., how rigidly attached to skin) of wing feathers. Our results indicated that annual losses of all six-type wing feathers decreased with increasing ages, ranging from 29% to 58% for PC, alula, SC, P, S, and T in order. Our results were also comparable to those of a former study, suggesting that the pattern of age-specific molt might be associated with the cost of reproduction in adults. However, juveniles might shed more wing feathers with low quality formed during the previous development stage than older birds.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.3
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• pp.185-195
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• 2021

The flapping-wing micro air vehicle (FW-MAV) in this study utilizes the cambered wings made of quite flexible material. Similar to the flying creatures, the present cambered wing uses three different materials at its leading edge, vein, and membrane. And it is constrained in various conditions. Since passive rotation uses the flexible nature of the wing, it is important to select an appropriate material for a wing. A three-dimensional fluid-structure interaction solver is developed for a realistic modeling of the cambered wing. Then a parametric study is conducted to evaluate the aerodynamic performance in terms of the elastic modulus of leading edge and vein. Consequently, the elastic modulus plays a key role in enhancing the aerodynamic performance of FW-MAVs.

• Journal of Convergence for Information Technology
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• v.10 no.12
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• pp.39-48
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• 2020

This study is a qualitative study to understand the meaning and essential structure of the experiences of Tae-um (Workplace bullying) experienced in hospital organizations for nurses. The participants were interviewed by selecting 10 persons who agreed to participate in the research through SNS in the workplace with the cooperation of the hospital. The collected data were analyzed using Colaizzi's phenomenological method. As a result of the study, Tae-um in the hospital organization of clinical nurses was divided into 4 categories(Taking the terrible first step, A series of hardships that never end, Hang on to myself, Wings flight of for adaptation) and 16 It was derived from themes. In conclusion, it was confirmed that Tae-um, not only new nurses, but even nurses who have accumulated careers, are still in progress, so they are adapting to the difficult hospital organization. Therefore, if a psychological support program for nurses is introduced, it will contribute to solving the Tae-um problem and establishing an organizational culture where nurses are respected.

• Journal of the Korea Institute of Military Science and Technology
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• v.24 no.1
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• pp.1-11
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• 2021

Thermal protection system structures such as double-panel structures are used on the skin of the fuselage and wings to prevent the transfer of high heat into the interior of an high supersonic/hypersonic aircraft. The thin-walled double-panel skin can be exposed to acoustic loads by high power engine noise and jet flow noise, which can cause sonic fatigue damage. In order to predict the fatigue life of the skin, the octave bandwidth SPL should be calculated as narrow bandwidth PSD or acoustic load history using interpolation method. In this paper, a method of converting the octave bandwidth SPL acoustic load into a narrow bandwidth PSD and reconstructed acoustic load history was investigated. The octave bandwidth SPL was converted to the narrow bandwidth PSD using various interpolation methods such as flat, log and linear scale, and the probabilistic characteristics and fatigue damage results were compared. It was found that average error of fatigue damage index by the log scale interpolation method was relatively small among three methods.

• The Research Journal of the Costume Culture
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• v.28 no.6
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• pp.858-874
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• 2020

This study attempts to analyze the social and cultural meanings of the ethnic groups to which different types of shamans belong in Siberia from the appearance characteristics in terms of clothing through Roland Barthes's semiotic theory. The research method here is to analyze three types of shaman costume classified by Holmberg, which are bird-type, deer-type, and bear-type, through theoretical research and to investigate the analysis process of Roland Barthes's semiotics theory. Roland Barthes's approach to semiotics presents an analysis model that can explore the sociocultural meaning of the Siberian shaman costume. The research results are as follows. In the first type, to be closer to the god of the upperworld, shamans transform themselves into birds by decorating their costumes with the characteristic elements of birds such as feathers and wings. In the second type, the shamans' costumes are made of deerskin, and the headdress is shown in the shape of antlers to make it easier to receive messages from the upperworld and run fast in the underworld. In the third type, the shaman's costume is made of bearskin, the head is covered with bearskin, and the body is decorated with bear pendants. Through the power of the bear, the shaman is sent to the underworld to defeat evil gods and remove diseases. Shamans can show their particularity of being a demigod and non-binary gender through clothing. They use this to reflect their authority as a medium of communication between man and god.

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

• Korean Journal of Plant Resources
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• v.34 no.1
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• pp.73-78
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• 2021

We report a technique for obtaining seeds of 'Cheongnarae' (a variety of Hosta minor cultivated at the Korea National Arboretum in 2019) by artificial crossing of H. minor, collected from Jeju Island, as the female parent and H. minor 'Krossa Regal', cultivated outside Korea, as the male parent. Among the individuals obtained after sowing, those that showed different morphological characteristics, such as leaf shape and color, were selected. Among these individuals, those with thick leaves and light-colored flowers were further selected. Vegetative propagation and cultivation steps were repeated for evaluation of the characteristics. 'Cheongnarae' has relatively thicker leaves and a darker color (RHS 137A) than the control variety 'Black Hills' and has wings at the point where the petiole meets the leaf blade. The shape of the leaf blade edge is clearly sinuous, and the flower color is close to white (White N155B). 'Cheongnarae' cultivated in this way can be used for pot plant or gardening.

• Journal of The Korean Astronomical Society
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• v.55 no.5
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• pp.149-172
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• 2022

We present a new method which constructs an Hɪ super-profile of a galaxy which is based on profile decomposition analysis. The decomposed velocity profiles of an Hɪ data cube with an optimal number of Gaussian components are co-added after being aligned in velocity with respect to their centroid velocities. This is compared to the previous approach where no prior profile decomposition is made for the velocity profiles being stacked. The S/N improved super-profile is useful for deriving the galaxy's global Hɪ properties like velocity dispersion and mass from observations which do not provide sufficient surface brightness sensitivity for the galaxy. As a practical test, we apply our new method to 64 high-resolution Hɪ data cubes of nearby galaxies in the local Universe which are taken from THINGS and LITTLE THINGS. In addition, we also construct two additional Hɪ super-profiles of the sample galaxies using symmetric and all velocity profiles of the cubes whose centroid velocities are determined from Hermite h3 polynomial fitting, respectively. We find that the Hɪ super-profiles constructed using the new method have narrower cores and broader wings in shape than the other two super-profiles. This is mainly due to the effect of either asymmetric velocity profiles' central velocity bias or the removal of asymmetric velocity profiles in the previous methods on the resulting Hɪ super-profiles. We discuss how the shapes (𝜎_n/𝜎_b, A_n/A_b, and A_n/A_tot) of the new Hɪ super-profiles which are measured from a double Gaussian fit are correlated with star formation rates of the sample galaxies and are compared with those of the other two super-profiles.