• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 한국소음진동공학회 2002년도 춘계학술대회논문집
• /
• pp.1244-1249
• /
• 2002

In this study, the physical characteristics of steel-wire sound absorbing materials with different thickness and bulk density is experimentally obtained in terms of the porosity and specific flow resistivity. Based on the experimental results, the following conclusions can be made. The porosities of steel-wire sound absorbing materials are smaller than those of general absorbing materials, which are inversely proportional to the volume densities. For the porosity measurement with a good accuracy, the dynamic correction based on the system compliance should be involved in porosity measurement. In addition, the flow condition for the precise measurement of the specific flow resistivity of steel-wire sound absorbing materials should be limited in the laminar flow region.

• Transactions of the Korean Society of Automotive Engineers
• /
• 제13권1호
• /
• pp.109-118
• /
• 2005

A functional suspension model is proposed as a kinematic describing function of the suspension that represents the relative wheel displacement in polynomial form in terms of the vertical displacement of the wheel center and steering rack displacement. The relative velocity and acceleration of the wheel is represented in terms of first and second derivatives of the kinematic describing function. The system equations of motion for the full vehicle dynamic model are systematically derived by using velocity transformation method of multi-body dynamics. The comparison of field test results and simulation results of the ADAMS/Car demonstrates the validity of the proposed functional suspension modeling method. This model is suitable for real-time vehicle dynamics analysis.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 한국전산구조공학회 2001년도 봄 학술발표회 논문집
• /
• pp.475-480
• /
• 2001

The purpose of this study is to evaluate the validity of seismic performance evaluation using static analysis. For this purpose, Ordinary Moment Resisting Steel Frames(OMRSF) for different heights(3, 6 ,9, 12 story) and seismic zones(Zone 2A, 2B, 3, 4) were designed in compliance to AISC LRFD 1993 Seismic Provisions and NEHRP 1994 Guidelines. Nonlinear Static Procedure(NSP) and Nonlinear Dynamic Procedure(NDP) with a set of ground motion record were used to evaluate seismic demands in OMRSFs. Using the DRAIN-2DX program, this study compares peak displacement demands(Target Displacement) proposed by FEMA 273 with the peak roof displacement demands obtained from the inelastic time history analyses. Based on the results, the validity of procedure of seismic demand evaluation using Target Displacement is discussed.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• 제38권11호
• /
• pp.941-949
• /
• 1989

This two-part paper presents a control method that allows for stable interaction of a robot manipulator with environment. In part 1, we focus on the input output relationships (unstructured modeling) of the robot and environment dynamics. This analysis leads to a general condition for stability of the robot and environment taken as a whole. This stability condition, for stable maneuver, prescribes a finite sensitivity for robot and environment where sensitivity of the robot (or the environment) is defined as a mapping forces into displacement. According to this stability condition, smaller sensitivity either in robot or in environment leads to narrower stability range. In the limit, when both systems have zero sensitivity, stability cannot be guaranteed. These models do not have any particular structure, yet they can model a wide variety of industrial and research robot manipulators and environment dynamic behavior. Although this approach of modeling may not lead to and design procedure, it will allow us to understand the fundamental issues in stability when a robot interacts with an environment.

• The Journal of Korea Robotics Society
• /
• 제16권1호
• /
• pp.35-40
• /
• 2021

As the robot industry develops, industrial automation uses industrial robots in many parts of the manufacturing industry. However, rigidity-based conventional robots have a disadvantage in that they are challenging to use in environments where they grab fragile objects or interact with people because of their high rigidity. Therefore, researches on soft robot have been actively conducted. The soft robot can hold or manipulate fragile objects by using its compliance and has high safety even in an atypical environment with human interaction. However, these advantages are difficult to use in dynamic situations and control by the material's nonlinear behavior. However, for the soft robot to be used in the industry, control is essential. Therefore, in this paper, real-time PD control is applied, and the behavior of the soft actuator is analyzed by providing various waveforms as inputs. Also, Iterative learning control (ILC) is applied to reduce errors and select an ILC type suitable for soft actuators.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• 제27권3C호
• /
• pp.248-255
• /
• 2002

An RF module in compliance with the IEEE 802.11a standard has been designed and its performance has been measured. Conventional heterodyne architecture with 580MHz intermediate frequency has been realized. Measurement results show that the receiver has a low Noise Figure of 5dB, the maximum gain of 70dB, and dynamic range as wide as 61dB. Also, the SAW filter used for channel selection in the IF section allowed minimum inter-channel interference. in addition to satisfying the RF output power requirement, the transmitter features its output P1dB as high as 34dBm so that the high peak-to-average ratio of the Orthogonal Frequency Division Multiplexing (OFDM) modulation scheme can be handled with minimum nonlinear distortion. The output P1dB of 34dBm of the transmitter corresponds to back-off powers of 18dB and 11dB with respect to the output power for the low and the middle frequency bands, respectively.

• Journal of Aerospace System Engineering
• /
• 제12권4호
• /
• pp.18-25
• /
• 2018

The head frame structure of a machine tool for aircraft parts, which requires machining precision and machining of difficult-to-cut materials is required to be light-weighted for precision high-speed machining and to minimize possible deformation by cutting force. To achieve high stiffness and for light-weight structure optimization design, a preliminary model was designed based on finite element analysis. The topology optimization design of light-weight, high stiffness, and low vibration frame structure were performed by minimizing compliance. As a result, the frame weight decreased by 17.3%, the maximum deflection was less than 0.007 mm, and the natural frequency increased by 30.6%. The static stiffness was increased in each axis direction and the dynamic stiffness exhibited contrary results according to the axis. Optimized structure with the high stiffness of low vibration in topology optimization design was confirmed.

• Proceedings of the KOSOMBE Conference
• /
• 대한의용생체공학회 1996년도 추계학술대회
• /
• pp.80-85
• /
• 1996

The various function of the cardiovascular system(CVS) and the dynamic characteristics on each part of human body can be acquired in the electric analog circuit model. According to the performed outcome by other researchers, viscos resistance, flow inertia, and vascular compliance in the CVS are analogous to resister, inductor, and capacitor in electric circuit, so the CVS models were represented by the electric circuit models. these approaches were to propose the suitable models interest part of body and to simulate the various characteristics on the CVS. In this paper, the electric circuit model considering the characteristics of morphologic structure is represented, the parameter values of model is sotted up, and the dynamic characteristics of the the CVS is simulated using VisSim, one of the simulation tools. The observed simulation results are similar to the cardiovascular functions of nomal adults who have no heart failure. Besides, the simulation is operated to observe the pathophysiological abnomal symptoms(for example, bleeding within a certain period). The controller by baroreceptor, which is one of controllers to control the CVS, is appended in the model. and the dynamic response characteristics and the procedure to return normal state is observed in simulation when the bleeding last within a certain period.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• 제14권12호
• /
• pp.6353-6363
• /
• 2013

This study examined the factors associated with recurrent falls among the community-dwelling elderly. The participants were 329 community-dwelling elderly. The data was collected from February 5, 2010 to February 14, 2010. Over the past 1 year, 14.3% of the 329 participants fall once, and 4.0% experienced recurrent falls. There was a significant difference among the non fallers, single faller and recurrent fallers with regard to the static balance(F=5.86, p=.003), dynamic balance(F=24.32, p<.001), risk of fall(F=9.94, p<.001) and compliance of prevention behavior related to falls(F=3.09, p=.047). The analysis results for the correlation between variables showed that the number of falls had a negative effect on the knee flexors muscular strength(r=-.15, p=.008), static balance(r=-.16, p=.004) and compliance of prevention behavior related to falls(r=-.12, p=.030) and a positive affect for the dynamic balance(r=.26, p<.001), depression(r=.13, p=.019) and risk of falls(r=.30, p<.001). The variables explained 36.0% of the variants in the occurrence of recurrent falls. Therefore, an effective recurrent fall prevention program should focus on multiple risk factor intervention.

• Journal of the Korea Society for Simulation
• /
• 제27권2호
• /
• pp.49-59
• /
• 2018

The simulation-based weapon system effectiveness analysis is to support the decision making in the acquisition process of the defense domain. The effectiveness of the weapon system is a complexly influenced indicator from various factors such as environment, doctrine and so on. And the measurement of effectiveness can be defined differently in compliance with major issues in the weapon system. Because of this, the weapon system effectiveness analysis requires the comparative experiment of various alternatives based on the underlying assumption. This paper presents the efficient approach to reconfigure the simulation using the reflection technique. The proposed method contains the recoupling and resetting the simulation entity using DEVS(Discrete EVent System specification) formalism-based dynamic plug-in method. With the proposed method, this paper designs the effectiveness analysis environment that can efficiently handle the various alternatives of the weapon system.