• Structural Engineering and Mechanics
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• v.38 no.2
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• pp.157-169
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• 2011

In this paper the time-dependent closed-form static solution of the suspended pre-stressed biconcave and biconvex cable trusses with unmovable, movable and elastic or viscoelastic yielding supports subjected to various types of vertical load is presented. Irvine's forms of the deflections and the cable equations are modified because the effects of the rheological behaviour needed to be incorporated in them. The concrete cable equations in the form of the explicit relations are derived and presented. From a solution of a vertical equilibrium equation for a loaded cable truss with rheological properties, the additional vertical deflection as a time-function is determined. The time-dependent closed-form model serves to determine the time-dependent response, i.e., horizontal components of cable forces and deflection of the cable truss due to applied loading at the investigated time considering effects of elastic deformations, creep strains, temperature changes and elastic supports. Results obtained by the present closed-form solution are compared with those obtained by FEM. The derived time-dependent closed-form computational model is used for a time-dependent simulation-based reliability assessment of cable trusses as is described in the second part of this paper.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.219-221
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• 1996

A reluctance motor is a electric machine in which torque is produced by the tendency of its movable part to move to a position where the inductance of the excited winding is maximized. This means physical fact that the energy stored in the field tend to be minimized as the energy stored in the field is converted the mechanical work. In this paper, we have studied the characteristics of the electromagnetic energy conversion about SRM which have 6 stator and 4 rotor poles with 3 phase. In addition we design the fundamental model of SRM with requirements(e.g. power, speed) and simulate with PC-SRD.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.04a
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• pp.55-56
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• 2009

A light guiding plate (LGP) with nanometer-sized patterns was fabricated by injection molding method which employed electrically healed mold and the transcription of injection-molded parts was investigated. A Ni stamper was fabricated using MEMS technology. The Ni stamper was then installed in a movable heated core which is a key part of the mold. Using this mold, injection-molded plastic LGP parts were manufactured at different mold temperatures and the effect of the temperature on the transcription of the parts was investigated.

• Transactions on Electrical and Electronic Materials
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• v.14 no.3
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• pp.116-120
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• 2013

This paper proposes a novel RF MEMS dc-contact switch with stiff membrane on a quartz substrate. The uniqueness of this work lies in the utilization of a seesaw mechanism to restore the movable part to its rest position. The switching action is done by using separate pull-down and pull-up electrodes, and hence operation of the switch does not rely on the elastic recovery force of the membrane. One of the main problems faced by electrostatically actuated MEMS switches is the high operational voltages, which results from bending of the membrane, due to internal stress gradient. This is resolved by using a stiff and thick membrane. This membrane consists of flexible meanders, for easy movement between the two states. The device operates with an actuation voltage of 6.43 V, an insertion loss of -0.047 dB and isolation of -51.82 dB at 2 GHz.

• 제어로봇시스템학회:학술대회논문집
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• 1995.10a
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• pp.150-153
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• 1995

In this paper the attitude control system is developed for longitudinal motion of Foil-Catamaran in regular waves with all-movable foils which attached to fore and after part of the ship and verified the system by theoretical calculation and model-tests. The linearized equations of motion of the ship is employed to apply the linear control theories, the PID control and the LQR. The strip method was used to calculate hydrodynamic coefficients and wave exciting forces of the demi hull, and unsteady hydrodynamic forces of foils are considered by using the result of Wu(1972). About 40-60% of motions is reduced in experiments. The control system described in this paper is able to extended to 6-DOF motions or control in irregular wave with trivial modification. And it is applicable to hull shape development for better seakeeping performance and to determine the size and the position of hydrofoils for the attitude control.

• Journal of Advanced Marine Engineering and Technology
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• v.23 no.1
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• pp.79-87
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• 1999

The most part of the faculty drop a trouble and damage of machine equipment even if whatever cause they break out take place at local and trifling place and the factor dominating their trouble is due to wear debris occurred in the lubricated machine moving surface. This study has been car-ried out to identify morphology of wear debris on the lubricated machine moving system by means of computer image analysis. Namely the wear debris contained in lubricating oil extracted from movable machine equipment will be filtered through membrane filter(void diameter 0.45${\mu}m$) and will be analyzed with its data information such as 50% volume diameter aspect roundness and reflectivity. Morphological characteristic of wear debris is easily distinguished by four shape parameters it is necessary to divide small class of every 100 wear debris in total wear particles in order to distinguish morphological characteristic of wear debris more easily by computer image analysis. We are sure that operation condition diagnosis of the lubricated machine moving surfaces is possible by computer image analysis.

• Proceedings of the KIEE Conference
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• 1997.07a
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• pp.297-299
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• 1997

The switched reluctance motor is an electric machine in which torque is produced by the tendency of its movable part to move to a position where the inductance of the excited winding is maxmized. It is as well as PM brushless do systems. It's many advantages-a wide speed range, and inherently simplicity and ruggedness, low manufacturing cost, make it a vigorous challenger to these drives. It is a fascinating machine with all kinds of interesting application possibilities. In this paper, the design and evaluate the performance is treated.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.10a
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• pp.295-300
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• 1996

The design of formwork system for vertical form faces is controlled by pressures predicted to act against the formwork by fresh concrete. An overestimation of pressure results in heavy, and ex-pensive formwork. An underestimation results in malformed structure, of in some cases, it causes the failure of the formwork. This study is a preliminary step in determination lateral pressures with High folwable concrete. To estimate lateral formwork pressures, we measured tensile strain of formtie in the movable part of the form. From the experimental results maximum lateral pressure and the location at which maximum pressures occurs, were determined. The experimental results are compared with the results predicted by the Gardner & Qureshi's proposed equation and the accepted Korean Standard Specification for concrete and ACI equation.

• Proceedings of the KIEE Conference
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• 1996.11a
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• pp.9-11
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• 1996

The Switched Reluctance Motor is an electric machine in which torque is produced by the tendency of its movable part to move to a position where the inductance of the excited winding is maximized. The main advantages of this motor lie in the simple robust construction and low manufacturing cost. In this paper, we describe the design features of single-phase switched reluctance motor for low-power variable-speed drives.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.6
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• pp.61-66
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• 2008

In railroad operation, turnout is the device designed to provide very critical functions of moving the train to the neighboring rail. It's the only movable section among the rail and track equipment, which has a complicated structure and as rapid movement between the wheel and rail during operation is unavoidable, the safety and the vibration caused by the impact load of the passing train becomes always the major concern. Response to rail vibration tends to vary depending on physical properties of the rail, rail base and the ground, making it difficult to estimate the quantitative outcome through the measurement. Thus, experimental or empirical approach, rather than an analytic method, has been more commonly employed to deal with the ground vibration. To predict the vibration of the turnout, an experimental value and the measured values are applied in parallel to the factors with a high degree of uncertainty. This study hence was intended to compare and analyze the vibration values measured at the crossing part of manganese turnout by type of train and turnout and distance, as well as predict the intensity of vibration generated at the crossing part of manganese turnout when tilting train accelerates.