• Journal of the Korean Society for Aviation and Aeronautics
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• v.13 no.2
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• pp.14-26
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• 2005

A tilt-rotor aircraft has various flight modes : helicopter, airplane, and conversion. Each of flight mode has unique and nonlinear flight characteristics. Therefore the gain schedules for whole flight envelope are required for effective flight performance. This paper proposes collective, flap, and nacelle angle scheduler for whole flight envelope of the Smart UAV(Unmanned Air Vehicle) based on CAMRAD(Comprehensive Analytical Model of Rotorcraft Aerodynamics and Dynamics) II analysis results. The scheduler designs are improved so that the pitch attitude angle of helicopter mode was minimized. The range of scheduler are reduced inside of engine performance limits. The conversion corridor and rotor governor are suggested also.

• International Journal of Aeronautical and Space Sciences
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• v.8 no.1
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• pp.87-94
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• 2007

Tilt rotor-wing concept to show enhanced performance in low speed mission is presented. Three types of stud wings on the existing tilt rotor configuration are suggested and their characteristics are compared. Aerodynamic analysis indicates that the stud wing concept gives significant performance improvement on the endurance and range in the low speed regime when compared with the tilt rotor. Penalties of the stud wing are discussed from the perspectives of conversion corridor, structural weight, configuration design, and cross wind stability. This study concludes that the advantage of the stud wing in general UAV mission performance is so significant as to surpass the penalties in other perspectives investigated.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.11
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• pp.1103-1111
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• 2014

The results of control law design for a tilt-rotor unmanned aerial vehicle that has a nacelle mounted wing extension (WE) are presented in this paper. It consists of a control surface mixer, stability and control augmentation system (SCAS), hold mode for altitude / speed / heading, and a guidance mode for preprogram and point navigation which includes automatic take-off and landing. The conversion corridor and the control moments derivatives between the original tilt-rotor and its variant of the nacelle mounted WE were compared to show the effectiveness of the WE. The nacelle conversion of the original tilt-rotor starts when the airspeed is greater than 30 km/h but its WE variant starts at 0 km/h in order to reduce the drag caused by the high incidence angle of the WE. The stability margins of the inner loop are presented with the optimization approach. The outer loops for the hold mode are designed with trial and error methods with linear and nonlinear simulation. The main control parameter for altitude control of the helicopter mode is thrust command and it is transferred to the pitch attitude command in airplane mode. Otherwise, the control parameter for the speed of the helicopter mode is the pitch attitude command and it is transferred to the thrust command in airplane mode. Therefore the speed and altitude hold mode are coupled to each other and are engaged at the same time when an internal pilot engages any of the altitude or speed hold modes. The nonlinear simulation results of the guidance control for the preprogrammed mode and point navigation are also presented including automatic take-off and landing in order to prove the full control law.

• Journal of architectural history
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• v.28 no.5
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• pp.43-58
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• 2019

After the study of Fujishima Gaijiro(1930), although it is common to see that the Tang-ruler(唐尺) was used in the construction of the Silla Sacheonwangsa temple(679), the basis of the discrimination of the construction measure and the detection of the unit length is not actually sufficient since conventional research was done before the excavation. The study was based on archaeological results, which was secured through the excavation research(2006~2012) of the temple site in recent years, to determine the construction measure and try to detect the unit length. In the analysis of the measured value of the ruins, the numerical data were obtained through measurements on drawings of the ruins, the tendency of conversion measure's number appearing by dividing each unit length of the Goguryeo-ruler(高句麗尺) and Tang-ruler within a certain range was compared from the Wansu-je(完數制) viewpoint. The research results are summarized as follows : 1)As a result of the analysis of the distance between the site's center, the case that conversion Cheok's(尺) number is converged to the unit of Jang(丈) within the range of unit length expresses three times more in Tang-ruler, and it is confirmed that a simple multiple relationship based on the unit of Jang is established between conversion Cheok's number. 2)As a result of analysis of Bokan(梁間) of the each Corridor site and the measured value of the stonework ruins, it could be confirmed that appears overwhelmingly in the Tang-ruler when conversion Cheok's number becomes an integer within the range of unit length. The results of the analysis are judged to be a clear basis for viewing the Tang-ruler as the construction measure of the Sacheonwangsa temple. 3)The estimated unit lengths of the construction measure that were obtained from the analysis of the distance between the site'scenter, the foundation stone center distance of the building site and the measured value of the stonework ruins are slightly different. There is a limit to the verification of the construction error about this, however it is difficult to specify, it is mentioned 294.37mm which is obtained from the analysis of the distance between the site's center.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.219-219
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• 2009

ceramic metal halide lamps are a subset of high intensity discharge lamps so named because of their high radiance These lamps weak ionized plasma in a fire-resisting but light transmissive wrapping by the corridor of current through atomic and molecular vapors. for commercial applications, For commercial applications, the conversion of electric power to light must occur with good efficiency and with sufficient spectral content throughout the visible (380-800 nm) to permit the light so generated to render colors comparable to natural sunlight. the purpose of this paper is to carry out a study on the variation of ageing time(2000 On/Off[hr]) on the performance of 150W CMH lamps. Experimental results show that the blackening by reacting W(tungsten)with I atomic has been created in the arc tube of an ageing lamp(2000 On/Off[hr]), the arc was unstable, and increased a lamp resistance made lamp voltage increases significantly. Also, Color temperature of the ageing lamp was moved by the losses of Ho with Dy atomics and by recombination of Na with I.

• Journal of Distribution Science
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• v.13 no.10
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• pp.123-133
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• 2015

Purpose - The Korean government has devised intermodal transportation policies and granted subsidies to shippers and logistics companies that made a conversion of transportation means through the policies. This provides support by expanding the complex uniform railroad transportation and overhauling the deteriorated railroad facilities. As for 2013, however, the freight transportation percentage of railroad was 4.5% in tons and 8.5% in ton kilometers. Meanwhile, since the 1990s, developed countries such as the U.S. and Europe have been trying to expand intermodal freight transport with a legal and institutional support to build a logistics system corresponding with social and economic environmental changes. In this study, I set out to examine the effects of the intermodal freight transport policies in the EU and the U.S., and to explore the direction of setting up a rail intermodal transport system in South Korea. Research design, data, and methodology - The paper used a qualitative research methodology through the literature review. First, was an overview of Intermodal transportation in the EU, U.S. and UN. Second, it describes the development of transport in Europe and the U.S. with particular emphasis on intermodal freight transport. Third, it explores the direction of setting up a intermodal freight transport in South Korea. The last section contains concluding remarks. Results - As for the EU, it has been promoting integration between transport and intermodal logistics network designs while utilizing ITS or ICT and supports for rail freight intermodal by giving reduction to a facilities fee or subsidizing for rail freight in order to minimize the cost of external due to freight transport. On the other hand, as for the U.S., it has been made up of an industrial-led operating project and has been promoting it to improve accessibility between intermodal hubs and cargo terminals through intermodal corridor program, and an intermodal cargo hub access corridor projects, etc. Moreover, it has tried to construct intermodal transport system using ITS or ICT and to remove Barrier. As a result, in these countries, the proportion of intermodal freight transport is going to be the second significant transport compared with rail and maritime transport. An Effective rail intermodal transport system is needed in South Korea, as seen in the case of these countries. In order to achieve this object, the following points are required to establish radical infrastructure policy; diversify investment financing measures taken under public-private partnerships, legal responsibilities, improvement of utilization of existing facilities to connect the railway terminal and truck terminal, and enhancement service competitiveness through providing cargo tracking and security information that combines the ITS and ICT. Conclusions - This study will be used as a basis for policy and support for intermodal freight transport in South Korea. In the future, it is also necessary to examine from the perspective of the shipper companies using the rail intermodal transport, ie, recognition of shipper, needed institutional supports, and transportation demand forecasting and cost-effective analysis of the railway infrastructure systems improvement.