• Journal of the Korean Ceramic Society
• /
• v.34 no.4
• /
• pp.337-342
• /
• 1997

This paper describes the design and evaluation of new type piezoelectric bimorph actuator that shows much large mechanical response than those conventional types. The bimorph actuator has modified structure combined with the multilayer actuator(MLA) and the composite multilayer actuator called "Moonie". The design and performancean alysis of bimorph actuator are carried out with Finite Element Method (FEM). Theoretical calculation results show that the generating force and displacement of Moonie-modified bimorph actuator can be improved by about 130% and 150%, respectively. The overshooting and ringing phenomena of the bimorph can be effectively restrained by the pseudo step electric field having a rising time coincied with a period of the fundamental vibration mode of the bimorph.e bimorph.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.13 no.2
• /
• pp.227-234
• /
• 2010

When a weapon system is developed, climate elements such as temperature, rainfall, and so on have an effect on development costs and a developing period. Therefore, effects of environment and climate must be examined throughly before the design of weapon systems and be applied to their developments. And so, operational and storage requirements for weapon systems are determined and are applied to related tests through analyzing not only environmental factors such as vibration, shock, and so on, but also climate factors. In this paper, the distribution and the frequency of occurrence of rainfall were analyzed and were suggested as a good guide to determine standards of tests for weapon systems when it's raining.

• Proceedings of the KSR Conference
• /
• 2000.11a
• /
• pp.295-302
• /
• 2000

Slab guideway, surface treatment, heat line installation, and joint connection for Automated Guideway Transit with rubber tire are researched. While the AGT with rubber tire is constructed in city, the precast slab guideway must be considered a reduction of the construction period and the noise under construction. which related with environment. To do that, a basic design and the structural analysis for the precast slab guideway with rubber tire are studied. The surface treatment and the heat line installation of that are also compared with currently used methods. Tining method is applied to the surface treatment adopted from the concrete pavement application currently in use. The connection method between the slab of bridge and precast guideway are suggested with a bolt type and a bond type. To minimize noise and vibration of the connection while the AGT is in driving, the slop connection method can be enhanced the serviceability.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2021.11a
• /
• pp.230-231
• /
• 2021

In this study, Dr. Bae Kyu-woong of the Korea Institute of Construction Technology developed a concrete module that was lightweighted to 1700kN with KC modules and met housing performance standards. It solves Construction lifts problem that was the limit of the PC module, and is an innovative model that greatly improves Construction period and economics with boxed modules, and is manufactured in the factory by extruded molding in vibration, noise, fireproofing standards, etc., and has the advantage of excellent precision and high strength. Therefore, if the framing house of a precast concretecan only be standardized in construction, its potential for growth will be endless. To do this, standardization, standardization, and modularization of the design are essential.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.25 no.3
• /
• pp.7-14
• /
• 2011

Many countries and researchers in the lighting field have focused on the LED light source as a solution to energy savings and environmental pollution. The LED light source consumes less power, has a long life and is highly economical. It is vibration and shock-resistant, and environment friendly as well. But LED lighting has some problems. In particular, the photobiological safety of LED light sources is emerging as an issue. Ultraviolet radiation from the LED light source emitted directly to the human body over a long period of time is harmful. In this paper, UV radiation from white LED was measured. Finally, the LED light source emits UV radiation, but it is relatively small when compared to others.

• International Journal of Railway
• /
• v.6 no.1
• /
• pp.13-25
• /
• 2013

Railpad prevents damage of the tie and ballast by reducing the impact and high frequency vibration, which occurs when a vehicle load transfers to a tie. But elasticity of the railpad can decrease under vehicle load and over usable period. If that happens, railpad will become stiffer. Increase in stiffness of the railpad also translates into a rise in track maintenance cost because it accelerates the damage of the track. In this study, accelerated heat ageing test was performed to predict an expectable lifetime of the railpad. As a result, it was predicted to be about sixteen years at $25^{\circ}C$ that life time of railpad using NR rubber from Arrhenius relationship. Also, it was predicted to be about thirty-two days at $100^{\circ}C$. At this time, a standard rate of thickness change is approximately within 12%.

• Journal of Aerospace System Engineering
• /
• v.4 no.2
• /
• pp.16-20
• /
• 2010

In General, the hydraulic system of T-50 Advanced Trainer is applied to flight control system, wheel & Brake system and fuel system for aircraft operation. The hydraulic system is operation with pressure of 3000psi. and many mechanical parts which is operated by hydraulic system has been stressed in incomplete environment same as heat and friction. for example, Oil leakage had occurred in the shutoff valve of FFP used in a certain period of time. After study, The crack progressed by fatigue due to the irregular hydraulic pressure and vibration has been identified as the reason of oil leakage. This paper presents life cycle extension plans of FFP shutoff valve by configuration improvements of shutoff valve and FFP hydraulic motor.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.7 no.6
• /
• pp.28-35
• /
• 1998

Computer simulation technique has been applied on the various engineering fields to reduce cost and development period. On this paper, we introduce a crane analysis program. Using this program, we can predict reaction force of each part or supporting force of truck crane on a personal computer system with out exclusive knowledge of multi-body dynamics. In order to consider the effect of boom flexibility according to each working condition, flexible dynamic theory is applied to the program. Actual crane model is analyzed on special work condition using this program and the results are compared with those of rigid boom model.

• Proceedings of the KSR Conference
• /
• 2011.05a
• /
• pp.1681-1688
• /
• 2011

The platform screen door open-close mechanisms at today's subway are divided by "Radio Frequency method" and "Method at entrance perception sensor". In the case of "method at entrance perception sensor", there happen a lot of occasions of malfunctioning that may cause problems in terms of timeliness, swiftness and reliability of train operation and even ends up to train operation stop since the perceiving process is complicated and it is prone to have dust on lenses, position alteration by train vibration, and less reflection light in the case of new train. In this study, we find how to minimize possible problems in terms of maintenance during train operation period, and seek its alternatives in order not only to have no malfunction in perception but also to cause no disturbance in train operation through dealing organically when perceiving door open-close to minimize delay time.

• Proceedings of the Earthquake Engineering Society of Korea Conference
• /
• 2005.03a
• /
• pp.185-192
• /
• 2005

Using existing static methods, it is possible to estimate accurately the reponses of structures governed by the fundamental mode. However, these methods do not provide reliable estimates for the structure where higher mode effects are significant. Parametric study was performed to analyze the dynamic characteristics of the structure with long vibration period. Based on the investigations, a new modal combination method using modal combination coefficients, Factored Modal Combination, was developed, and static earthquake load patterns addressing higher mode effects reasonably were proposed. Existing modal combination methods, such as SRSS and CQC, lack a theoretical basis to be applied to inelastic structures. In contrast, the proposed method can be applied conveniently in inelastic range as well as in elastic range.