• Journal of Astronomy and Space Sciences
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• v.14 no.2
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• pp.367-374
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• 1997

Slewing maneuver and vibration suppression control of flexible spacecraft model by Lyapunov stability theory are considered. The specific model considered in this paper consists of a rigid hub with an elastic appendage attached to the central hub and tip mass. Attitude control to point and stabilize single axis using reaction wheel type device is tested. To control all flexible modes is so critical to designing an active control law. We therefore considered an direct output feeback control design by using Lyapunov stability theory. It is shown that the ouput feedback control law design with proposed configuration gives satisfactory result in slewing performance and vibration suppression control.

• Proceedings of the CALSEC Conference
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• 2001.08a
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• pp.327-336
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• 2001

For Business †각국의 상이한 Infra 및 상거래 관행을 수용하는 모델 †구매자, 판매자의 관련 비용 절감 †국제간 상거래를 위한 e-Marketplace의 유지/운영 비용절감 For Technique †확장성을 고려한 모델 및 시나리오 구성 †국제 표준안의 활용 → XML 표준, Catalog 표준 †각국의 다양한 Market을 인정한 상호인터페이스를 통한 네트워크 형성(중략)

• The Journal of the Convergence on Culture Technology
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• v.9 no.5
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• pp.737-745
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• 2023

This paper discusses a study on developing an artificial intelligence model to detect incidents of fires in distribution switchboard using thermal images. The objective of the research is to preprocess collected thermal images into suitable data for object detection models and design a model capable of determining the occurrence of fires within distribution panels. The study utilizes thermal image data from AI-HUB's industrial complex for training. Two CNN-based deep learning object detection algorithms, namely Faster R-CNN and RetinaNet, are employed to construct models. The paper compares and analyzes these two models, ultimately proposing the optimal model for the task.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.3
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• pp.199-207
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• 2021

This study aimed to improve the performance of the KTX (Korea Train Express) brake system. To develop a braking disc-hub for the high-speed rail, the model performance was analyzed by finite element analysis, and the analysis results were verified using the braking test results. In addition, heat transfer analysis, thermal stress analysis, natural frequency analysis, and static analysis were conducted to examine the mechanical performance of the braking system. By deriving the design factors and conducting parametric analyses according to the shape of the hub, this study derived the optimal specifications that could improve heat dissipation and reduce weight. The cooling efficiency and structural performance of the optimization model were improved during braking compared to the existing model. It is expected that the design verification will be carried out through analyses of the optimal specifications so that it can be used in the development of brakes in railway vehicles and motor vehicles.

• Journal of Navigation and Port Research
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• v.29 no.6 s.102
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• pp.501-508
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• 2005

The purpose of this paper is to present the alternatives for improving coostal shipping logistics system to be a logistic hub-nation with a competitive edge. For this purpose, major environmental factors in Northeast Asia and accordingly its effects are analyzed And then the effects of coastal shipping system's development strategy is analysed using Structural Equation Model and Multiple Regression Model. Research results show that three types of coastal shipping development strategy( connected transportation system, structure of coastal shipping system, governmental support policy) will contribute much to being a logistics hub-nation. From the results, some implications are derived as follows. Firstly, environmental-friendly balanced ocean-coastal transport system is required Secondly, a excusive feeder port, Ro-Ro ship & high-speed ship are necessary to establish the one-stop logistics service system Finally, governmental support policy and subsidy(tax-exempted oil & various tax benefits) are required to reactivate lagged coastal shipping system to be a logistic hub-nation with a competitive edge.

• Journal of Korean Society of Transportation
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• v.26 no.5
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• pp.117-127
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• 2008

After the deregulation of the aviation market in the United States in 1978, airlines took advantage of the possibilities of the liberalized market and reorganized their networks. Then, the hub-and-spoke networks became widely used in the aviation market. The framework of hub-and-spoke network made it feasible to amplify flight networks. Thus, a number of airlines were able to fly to more destinations than ever before through the networks. Amplification of networks can be implementing through the transfer of passengers, transshipment of cargo, or both most researches have been concentrated on the passenger aspect at airports worldwide. Air cargo, however, has become one of the most significant areas at hub airports to keep their leading position in terms of the provision of services and handling volumes. This paper investigates the connectivity of airfreight networks as the temporal concentrations in current network at Incheon International Airport. In order to evaluate airline flight schedule effects to stimulate hubbing at an airport, the indirect connectivity can be considered to be the number of direct frequencies, the minimum connecting times and the quality of the connection determine indirect connectivity. Therefore the connectivity of freight transshipment depends on both the quality of the connection at the hub airport and the quality of the indirect flight compared to the direct flight. In addressing these issues, this paper analyzes the connectivity of flight schedules using a temporal wave-system structure and estimates the degree of connectivity and quality of connectivity applying the NETSCAN model.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.4
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• pp.289-296
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• 2014

The rebar detailing is an important work influencing the final performance and quality of RC structures. But it is one of the most irrational and illogical activity in construction site. Many groups of workers, including main contractors, structural engineers, shop drawers, rebar fabricators, and etc., participate in this activity. A loosely-organized process for this activity is apt to produce a big amount of rebar loss or even degraded structures. A 3-dimensional rebar auto-placing system, called as Rebar Hub, has been designed and implemented in this research. Rebar Hub provides a totally integrated service from 3D structural modeling of buildings to rebar auto-placing considering anchorage, splice, and the length of ordered rebar. In addition, Rebar Hub can recognize the 2D drawing CAD files and then build 3D structural models which are used for the start point of 3D rebar auto-placing. After rebar auto-placing, each members of the 3D structural model have rebar information belonging to them. It means that the rebar information can be used for the afterward works such as quantity-survey, manufacturing and fabrication of rebars. Rebar Hub is showing outstanding performance while applying to practical projects. It has almost five times productivity and reduces the rebar loss up to 3~8% of the initially-surveyed amount of rebar.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.1 s.94
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• pp.63-71
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• 2005

In this study, structural vibration analyses of a composite smart unmanned aerial vehicle (UAV) have been conducted considering dynamic hub-loads of tilt-rotor. Practical computational structural dynamics technique based on the finite element method is applied using MSC/NASTRAN. The present smart UAV(TR-S2) structural model is constructed as full 3D configurations with both the helicopter flight mode and the airplane flight mode. Modal based transient response and frequency response analyses are used to efficiently investigate vibration characteristics of structure and installed electronic equipments. It is typically shown that the helicopter flight mode with the 90-deg tilting angle is the most critical case for the induced vibration of installed electronic equipments in the front.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.05a
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• pp.131-134
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• 2004

The hub hole is usually formed with a stretch flanging process followed by a blanking process of a hole. Since the hole is made by blanking, the blanked surface is so rough that the formability in the region is rather poor. The emerging task is to identify the formability of the blanked region in the forming simulation and to relate the criterion to the real forming process by experiments. In this paper, the blanked region of a hole surface is modeled by a defected-edge finite element for stretch flanging simulation. The analysis deals with the level of defect in the blanked region in order to identify the formability in the real process. The analysis provides the formability depending on the level of defect and seeks the way to match the level of defect to that of the real surface. The approach makes the analysis possible to deal with the formability of the high strength steel and predict the fracture at the hole surface during the stretch flanging simulation.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.8 s.239
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• pp.956-962
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• 2005

A three-dimensional computation was conducted to make a study about effects of the inlet boundary layer thickness on the total pressure loss in a low-speed axial compressor operating at the design condition ($\phi=85\%$) and near stall condition($\phi=65\%$). Differences of the tip leakage flow and hub corner-stall induced by the inlet boundary layer thickness enable the loss distribution of total pressure along the span to be altered. At design condition, total pressure losses for two different inlet boundary layers are almost alike in the core flow region but the larger loss is generated at both hub and tip when the inlet boundary layer is thin. At the near stall condition, however, total pressure loss fer the thick inlet boundary layer is found to be greater than that for the thin inlet boundary layer on most of the span except the region near hub and casing. Total pressure loss is scrutinized through three major loss categories in a subsonic axial compressor such as profile loss, tip leakage loss and endwall loss using Denton's loss model, and effects of the inlet boundary layer thickness on the loss structure are analyzed in detail.