• Journal of KSNVE
• /
• v.4 no.2
• /
• pp.155-161
• /
• 1994

The dynamic behavior of a complex mechanical structure can be identified by dividing the structure into a series of smaller structure, called sub- structure and by studying the dynamic characteristics of these components. Generally, the dynamic characteristics of mechanical structure are strongly affected by the properties of joint parameters. In this paper, to identify the dynamic characteristics of mechanical structure, and experimental identification method in which directrly measured frequency response function(FRF) is used is considered. The method does not use the procedure of complex matrix calculation but use that of real matrix calculation. To confirm this method, computer simulation is performed by using frequency response function mixed with noise, and the experimental study is performed about the simple structure. The dynamic characteristics of joint parameters and identified more accurately than in using the prcedure of complex matrix calculation.

• Journal of the Korean Ceramic Society
• /
• v.43 no.12 s.295
• /
• pp.859-864
• /
• 2006

For the pressure compaction process of the ceramic powder, the green density is very different with both the ceramic body shape and the processing conditions. The density difference cause non-uniform shrinkages and deformations, and make cracks in the sintered ceramics. In this paper, Material properties of the alumina powder mixed with binder and the friction coefficient between the powder and the tool set were determined through the simple compaction experiments: Also the powder flow characteristics were simulated and the green density was analyzed during the powder compaction process with Finite Element Method (FEM). The results show that the density distributions of the green body were improved at the optimized processing condition and both the possibility of the farming crack generation and rho deformation of the sintered Alumina body were reduced.

• The Journal of the Korean dental association
• /
• v.52 no.5
• /
• pp.281-290
• /
• 2014

Tooth eruption disturbance is seen commonly in mixed dentition or early permanent dentition. During this period of time, children experience the growth and development of craniofacial skeleton and dentition, so the impaction and eruption disturbance of permanent teeth make many problems in oral and maxillofacial areas. Eruption guidance of impacted tooth is not simple because many factors related to impaction are considered. Several factors such as etiology, tooth development stage, location of impacted teeth or eruption pathway, patient cooperation, etc. need to be taken into consideration in deciding the management of the impacted tooth. In the present study, it was assessed the etiology and impaction status of impacted tooth through various cases, and try to explain the treatment method to guide eruption by surgical exposure.

• Journal of the Korean Society of Safety
• /
• v.7 no.1
• /
• pp.5-12
• /
• 1992

Disc specimen with the center crack and edge crack simulated by two-dimensional static method is used to analyze the stress field around the crack tip in terms of the stress intensity factor, K. A simple and convenient method of testing to realize the mifed mode stress intensity factor of the cracked body is used, The conclusions obtatined in this photoelastlc analysis are as follows ; 1. According to this experiment, cracked disc specimen can be used to demonstrate the mixed mode stress intensity factor analysis by simply changing the crack angle from the loading line. 2. Despite the simplicity and continuous data reading, the photoelastic method shows the slightly lower strain reading comparing to the FEM analysis method. 3. In this photoelastic analysis, $K_{I}$ of center cracked disc specimen under a pair of compressive load shows negative value as the crack angle increases over 30$^{\circ}$.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.58 no.2
• /
• pp.335-341
• /
• 2009

Analysis of the partial discharge signal, a technique to diagnose the stator winding insulation is a key function for the diagnosis of high voltage rotating machines and requires high precision. To satisfy this requirement, various denoising techniques such as filtering and differential methods were proposed. However, these techniques can not eliminate a adjacent induction noise that decreases reliability of the diagnosis. A simple novel denoising algorithm, therefore, is proposed for removing the adjacent induction noise in this paper. The algorithm shows good performance in the real partial discharge signals measured by 13kV class capacitive couplers installed at hydro-generator in Dae-cheong Dam.

• Journal of Korean Institute of Industrial Engineers
• /
• v.22 no.3
• /
• pp.517-532
• /
• 1996

The area and time-dependent vehicle scheduling problem(ATVSP) is a generalization of the vehicle scheduling problem in which the travel speed between two locations depends on the passing areas and time of day. We propose a simple model for estimating area and time-dependent travel speeds in the ATVSP that relieves much burden for the data collection and storage problems. A mixed integer nonlinear programming formulation of the ATVSP is presented. We also propose three heuristics for the ATVSP, developed by extending and modifying existing heuristics for conventional vehicle scheduling problems. The results of computational experiments demonstrate that the proposed estimation model performs well and the saving method is the best among the three heuristics.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2009.11a
• /
• pp.149-152
• /
• 2009

Recent trends show an increased usage of 'colored concrete', a inorganic pigmented concrete mix, especially in smalll to large scale buildings. However, due to lack of varieties, current usage of colored concrete is limited to the one or two simple color of the time in construction work. so, this study is to investigate the properties of concrete adding temperature reactive pigment. The results of the experiment, the basic material characteristics of concrete such as of compressive strength and slump is affected by the amount rate of adding the temperature reactive pigment. And, it showed the excellent color expression and changing with temperature reactive pigment.

• Bulletin of the Korean Chemical Society
• /
• v.26 no.10
• /
• pp.1565-1568
• /
• 2005

A surface renewable pH electrode was prepared by utilizing composite electrode technique. Iridium oxide micro-fine particles was prepared by hydrolysis of $(NH_4)_2IrCl_6$ at elevated temperature. The iridium oxide particles were mixed with well-dispersed carbon black and then filtered. The mixture was suspended in DMF containing PVC as a binder. The mixture was precipitated rapidly by adding large amount of water. The precipitate was ground and pressure-molded to iridium oxide composite electrode material. The electrode showed linear response between pH 1-13 with 50 to 60 mV/pH slope. The electrode maintained the pH response without appreciable slope drift for 170 days if stored in deionized water. The electrode surface can be renewed reproducibly by simple grinding process whenever contaminated or deactivated.

• Solar Energy
• /
• v.6 no.2
• /
• pp.62-69
• /
• 1986

An analysis is made of the fully developed laminar flow and heat transfer in a parallel flat plate with heated rectangular block arrays to investigated the influence of bouyancy force. The shrouds is considered as adiabatic, while the heated block surface transmit a uniform rate of heat flux per unit axial length. The governing equations for velocity and temperature are solved by SIMPLE(Semi-Implicit Method Pressure Linked Equation) algorithm. Detailed velocity and temperature fields and overall heat transfer on wide range of Rayleigh number and various aspect ratios of heated rectangular blocks are computed. The result show that bouyancy leads to a significient enhancement in heat transfer along with a smaller increase in pressure drop, with the great enhancement found when the aspect ratio is 3.0.

• Journal of the Korean Ceramic Society
• /
• v.44 no.5 s.300
• /
• pp.141-143
• /
• 2007

Nanotubes and microtubes of ferroelectric lead zirconate titanate (PZT) were synthesized by means of a simple and convenient process called a template-wetting process. Nanoporous alumina and macroporous Si were used as template materials to fabricate the corresponding tubes. For the improvement of the wetting properties of the wetting solution, the PZT solution was mixed with a polymer. The polymer was removed completely during annealing. The grain growth processes of the PZT nanotubes during baking and furnace annealing were examined by means of field emission electron microscope (FE-SEM) and X-ray diffractometry (XRD).