• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1526-1531
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• 2008

The objective of this study is to evaluate the loading capacity of lattice girder according to loading position. 3-point flexible strength tests were performed on three types of lattice girder, such as LG-$50{\times}20{\times}30$, LG-$70{\times}20{\times}30$, and LG-$95{\times}22{\times}32$, mainly used in Korea. Two types of loading position for each flexible strength test were used to analyze the behavior of load-deformation. In 3-point flexible strength test, the difference of the average of maximum flexible strength according to loading position had the range from 10% to 33%.

• Journal of Power Electronics
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• v.11 no.3
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• pp.319-326
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• 2011

Nowadays numerous research projects are being conducted in the field of electric motors. Non-modeling of flexible connections such as couplings and the belt-pulley do not show some real behaviors. With an increase in the number of connections and drive factors, these Non-modeled modes become more important. The coupling of two electric motors, instead of one motor, in submarine propeller force is an obvious example which shows that Non-modeled vibration modes caused by flexible connections can disturb controller operation and make undesirable vibrations in the submarine body. In this paper a dynamic model of flexible connections and a completed dynamic model of two different coupled electric models is presented. A robust controller for the completed model is also amended so that the two controlling targets of a desired speed adjustment and an appropriate load division between the two motors with sufficient accuracy are achieved.

• Journal of the Society of Naval Architects of Korea
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• v.53 no.4
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• pp.258-265
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• 2016

A flexible riser consists of several layers which have different materials, shapes and functions. The layers designed properly can take the design load safely, and each property of layer provides a complexity of flexible riser. Such complexity/unit-property is an input for global analysis of flexible riser. There are several approaches to calculate the complexity of flexible riser, those are experimental, numerical and theoretical methods. This paper provides a complexity from numerical and theoretical analysis for 2.5 inch flexible riser of which details and the experimental data are already produced under tension, external pressure, and bending moment. In addition, comparison of stiffness and stress are also provided. Especially, analysis of stress could lead to researches on ultimate strength or fatigue strength of flexible risers.

• Proceedings of the KIEE Conference
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• 2002.07a
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• pp.419-421
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• 2002

This paper presents a methodology for the application of Unified Modeling Language (UML) to develop the new load management system. Development of new load management system in competitive electricity market is very complex since it requires too much data of power system. For the efficient and flexible design to develop of new load management system, a UML approach in applied which is composed of a class diagram, package diagram using Rational Rose Unified Process.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1998.10a
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• pp.274-279
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• 1998

The structural behaviors of a arch composed of flexible membrane are investigated. The membrane is considered as thin shell with internal pressure during FEM analysis by using ABAQUS. In the paper, a wind load and uniformly distributed vertical load are considered. As a vertical load, snow loads including applied over all and half of the structure are introduced. The ends of arch are fixed to the ground. Load-Deflections relationship, buckling mode of the structure are presented.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.8
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• pp.657-664
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• 2013

The flight loads analysis was carried out on the aircraft with high aspect ratio flexible wings by using commercial software MSC/NASTRAN. The aerodynamic model for flight loads analysis was corrected, compared with results of the wind tunnel test. And in-house program was developed for pre and post works. In-house program enabling management of much data automatically consists of three modules: 'Construction of the mass distributed model', 'Selection of critical load cases', 'Generation of external loads for structural design'. By utilizing these techniques and programs, the procedure of flight loads analysis was established for effective development of an aircraft.

• Proceedings of the KIEE Conference
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• 2001.07a
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• pp.60-64
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• 2001

Recent recovery of the Korean economy drives a rapid increase in utility consumption and requires more stable utility supply and maintenance. However, power location security hardship, reinforcement of international environmental regulation and a huge cost of power plant construction have increased the burden laid on the stable supply. In addition, an efficient and flexible load management is required more than any era since an increment of the rate of increase in cooling load is expected. Therefore, according as the necessity of direct load control for cooling load during the summer in Korea was on the rise, direct load control systems by Internet communication method are constructed at five commercial buildings. Based on practical load control, this study proposes various application modes and communication methods prior to extension diffusion of direct load control hereafter.

• Korean Journal of Materials Research
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• v.33 no.7
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• pp.295-301
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• 2023

Thermoelectric (TE) energy harvesting, which converts available thermal resources into electrical energy, is attracting significant attention, as it facilitates wireless and self-powered electronics. Recently, as demand for portable/wearable electronic devices and sensors increases, organic-inorganic TE films with polymeric matrix are being studied to realize flexible thermoelectric energy harvesters (f-TEHs). Here, we developed flexible organic-inorganic TE films with p-type Bi_0.5Sb_1.5Te₃ powder and polymeric matrices such as poly(3,4-eethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and poly (vinylidene fluoride) (PVDF). The fabricated TE films with a PEDOT:PSS matrix and 1 wt% of multi-walled carbon nanotube (MWCNT) exhibited a power factor value of 3.96 µW·m^-1·K^-2 which is about 2.8 times higher than that of PVDF-based TE film. We also fabricated f-TEHs using both types of TE films and investigated the TE output performance. The f-TEH made of PEDOT:PSS-based TE films harvested the maximum load voltage of 3.4 mV, with a load current of 17.4 µA, and output power of 15.7 nW at a temperature difference of 25 K, whereas the f-TEH with PVDF-based TE films generated values of 0.6 mV, 3.3 µA, and 0.54 nW. This study will broaden the fields of the research on methods to improve TE efficiency and the development of flexible organic-inorganic TE films and f-TEH.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.11c
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• pp.21-38
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• 1999

Engineering properties of most polymers used in geosynthetics such as geogrid can be degraded by the chemical reaction (e.g., oxidization, ultraviolet rays, hydrolysis etc.), chemical and mechanical load, microorganism, and so on. In addition, polymer can be damaged by the compaction during construction, and the characteristic of tensile strength of polymer can be changed by the long-term creep effect. In this study, engineering properties of flexible geogrids which are manufactured by weaving/knitting the high-tenacity polymers such as polyester formed in a very open, grid-like configuration, coated with any one of a number of materials (e.g., PVC, latex, etc.), are investigated. Through the analysis of test results, the durability and the long-term design tensile strength of flexible geogrids are evaluated.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.10a
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• pp.791-791
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• 2009

Hybrid air-foil magnetic bearing combines two oil free bearing technologies to take advantage of the strengths of each bearing with minimizing each other weaknesses. This paper presents bending mode vibration control of a flexible shaft supported by the hybrid air-foil magnetic bearing. An experiment set-up of a flexible shaft supported by the hybrid air-foil magnetic bearing is built. In order to verify the effectiveness of the hybrid bearing, unbalance responses of the flexible shaft supported by three different bearings: air-foil, magnetic and hybrid bearings are compared. Effect of load sharing between air-foil and magnetic bearings are investigated through changing control gain and offset displacements of magnetic bearing.