• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.37 no.12
• /
• pp.1513-1519
• /
• 2013

A genetic algorithm (GA) is an optimization technique based on natural evolution theory to find the global optimal solution. Unlike the gradient-based method, it can design nanoscale structures in the electric field because it does not require sensitivity calculation. This research intends to design a nanoaperture with an unprecedented shape by the topology optimization scheme based on the GA and ON/OFF method in the visible frequency range. This research mainly aims to maximize the transmission rate at a measuring area located 10nm under the exit plane and to minimize the electric distribution at other locations. The finite element analysis (FEA) and optimization process are performed by using the commercial package COMSOL combined with the Matlab programming. The final results of the optimized model are analyzed by a comparison of the electric field intensity and the spot size of near field with those of the initial model.

• The korean journal of orthodontics
• /
• v.24 no.2
• /
• pp.479-508
• /
• 1994

This study was designed to investigate the reciprocal movement which was derived form application of active torque in ideal archwire by computer-aided three-dimensional finite element analysis of maxillary teeth and surrounding periodontal ligament composed of 2617 elements and 3725 nodes. Ideal archwire model was also made using the beam elements and the contact between the wire and the bracket slot was made using the gap element. In this study non-linear elastic behaviors of contact between the wire and the bracket slot were considered on. We put the active torque between the lateral and cenral incisor and between the second premolar and the first molar with/without cinch-back. The results were expressed by quantitative and visible ways. The findings of this study were as follows: 1. Reciprocal actions to active torque were complex system consisting of a combination of counter-torque, bucco-lingual linear displacement and tipping, rotation of the teeth, occluso-gingival linear displacement. 2. When active anterior crown labial torque was applied, crown labial tippings of the lateral were the greatest, and those of the central incisor was the next, Crown lingual tippings of the canine and the first premolar, mesial rotations and extrusion of the lateral and distal rotations and intrusion of the canine occurred. When anterior torque with the cinch-back was applied, amount of crown labial tippings of the lateral and central incisor were reduced. Amount of crown lingual tipping of the canine and the first premolar were increased. Mesial tippings and mesial rotations of the second molar occurred. 3. When active posterior crown lingual torque was applied, crown lingual tippings of the first moalr were the greatest, and crown labial tippings of the second premolar and the first premolar were the next, the crown lingual tipping of the second molar were a little. Mesial rotations of the second premolar occurred but those of the first premolar didn't occurred.

• Journal of the Institute of Convergence Signal Processing
• /
• v.20 no.1
• /
• pp.16-23
• /
• 2019

Fine particulate matter known as PM 2.5 refers to the atmospheric particulate matter that has a diameter less than 2.5 micrometer identified as dangerous element for human health and its concentration can provide us a clear picture about air dust concentration. Humans stay indoor almost 90% of their life time and also there is no official indoor dust concentration data, so our study is focused on measuring the indoor air quality. Indoor dust data monitoring is very important in hospital environments beside that other places can also be considered for monitoring like classrooms, cements factories, computer server rooms, petrochemical storage etc. In this paper, visible light communication system is proposed by Manchester encoding technique for electromagnetic interference (EMI)-free indoor dust monitoring. Important indoor environment information like dust concentration is transferred by visible light channel in wide range. An average voltage-tracking technique is utilized for robust light detection to eliminate ambient light and low-frequency noise. The incoming light is recognized by a photo diode and are simultaneously processed by a receiver micro-controller. We can monitor indoor air quality in real-time and can take necessary action according to the result.

• Nuclear Engineering and Technology
• /
• v.52 no.8
• /
• pp.1749-1755
• /
• 2020

In present study, TEM foils of Ni-Mo-Cr alloy were directly irradiated with 30 keV Ar ions to allow direct characterization. The defects evolution and element segregation after irradiation were investigated by TEM and HAADF-EDS linear scanning. At low irradiation doses (1.38 and 2.76 dpa), black dots were formed and grew with increasing dose. Complicated defects including peas-shaped dislocation loops, polygon dislocation networks and large loops were visible in samples irradiated to high doses (13.8 and 27.6 dpa). Meanwhile, dislocation channels appeared, in which defects were swept out. Significant Mo depletions at dislocation lines and grain boundaries were induced by irradiation due to large misfits between Mo-Ni atoms and high content of Mo.

• Coupled systems mechanics
• /
• v.2 no.1
• /
• pp.1-22
• /
• 2013

Under thermal environment, Magneto-Electro-Elastic (MEE) material exhibits pyroelectric and pyromagnetic effects which can be used for enhancing the performance of MEE sensors. Recently studies have been published on material constants such as pyroelectric constant and pyromagnetic constant for magneto-electro-thermo-elastic smart composite. Hence, the main aim of this paper is to study the pyroelectric and pyromagnetic effects on behavior of MEE plate under different boundary conditions subjected to uniform temperature. A numerical study is carried out using eight noded brick finite element under uniform temperature rise of 100 K. The study focused on the pyroelectric and pyromagnetic effects on system parameters like displacements, thermal stresses, electric potential, magnetic potential, electric displacements and magnetic flux densities. It is found that, there is a significant increase in electric potential due to the pyroelectric and pyromagnetic effects. These effects are visible on electric and magnetic potentials when CFFC and FCFC boundary conditions are applied. Additionally, the pyroelectric and pyromagnetic effects at free edge is dominant (nearly thrice the value in CFFC in comparison with FCFC) than at middle of the plate. This study is a significant contribution to sensor applications.

• Journal of Environmental Science International
• /
• v.12 no.10
• /
• pp.1025-1032
• /
• 2003

The purpose of this study is to analyze the characteristics of the urban landscape by CG(Computer Graphic) pictures and visibility analysis. In this study, the CG picture was created by using zoning data and DEM(Digital Elevation Model) on Chunchon city. The landscape type was classified into three by cluster analysis using the area rate of the element which constitutes CG picture. Visible analysis used DEM as fundamental data, and was performed by using GIS(Geographic Information System). And the frequency seen on viewshed was classified into five grades. The result of this study are as follows: 1. The area rate of the element which constitutes CG picture was high development restriction zone(43%) in type 1, green land area(39%) in type 2, and city area(24%) in type 3. 2. In the analysis results of GIS visibility analysis, it turns out that Euiam lake is important area on the landscape in all types. 3. The land use of high frequency seen on viewshed was water area, residential area in type 1, development restriction area, park area in type 2, and development restriction zone, water area in type 3.

• Proceeding of EDISON Challenge
• /
• 2016.03a
• /
• pp.167-174
• /
• 2016

Recently laminated plates like composite materials has been used in a various field to grow the specific strength of the composition. However, delamination area caused by barely visible impact damage has potential risk that it can raise buckling of the delaminated plate. Because it can interrupt compressive behavior of laminated plates and reduce their strength, the whole structure can't be constituted by these materials. Many studies assume that behavior of the delaminated plate which is in lamanated plates equals theoretical buckling but their actual motion doesn't coincide because of initial imperfections of materials like deflection, residual stress, eccentricity and so on. In this paper, we change laminated plates with initial delamination into a beam of rectangular cross section with the initial crack and analyze compressive behavior according to initial imperfections through finite element method(FEM). Consequently analysis results show that behavior of laminated plates involving delamination differs from ideal buckling of the delaminated plate in actual conditions and we can predict its motion through imperfections relationship.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2006.11a
• /
• pp.91-92
• /
• 2006

Aluminum-doped zinc oxide (AZO) films are attractive materials as transparent conductive electrode because they are inexpensive, nontoxic and abundant element compared with indium tin oxide (ITO). AZO films have been deposited on glass (corning 1737) substrates by RF magnetron sputtering system. The electrical resistivity of AZO films was $1.81{\times}10^{-2}{\Omega}cm$ and the average transmittance in the visible range 400-800 nm was more than 76% Organic light-emitting diodes (OLEDs) with AZO/TPD/$Alq_3$/Al configuration were fabricated. The current density-voltage properties of devices were studied and compared with ITO devices fabricated under the same conditions.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2004.05a
• /
• pp.74-79
• /
• 2004

The shape of cold rolled steel sheets is the degree of flatness, and the flatter, the better. Because undesirable strip shapes of cold rolled steel sheets can affect not only visible problem but also automatic working process in customer's lines, the requirement of the customers is more and more stringent. So we usually used the tension leveler to make high quality of strip flatness. For the improvement of the quality of strip flatness, this report developed three-dimensional FEM (Finite Element Method) simulation model, and analysis about the strain and stress distribution of strip in the tension leveling process.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.4 no.4
• /
• pp.34-38
• /
• 2005

This is a widespread requirement for low cost lightweight thermal imaging sensors for both military and civilian applications. Today, a large number of uncooled infrared detector developments are under progress due to the availability of silicon technology that enables realization of low cost IR sensor. System prices are continuing to drop, and swelling production volume will soon drive process substantially lower. The feasibility of micromechanical optical and infrared (IR) detection using microcantilevers is demonstrated. Microcantilevers provide a simple Structurefor developing single- and multi-element sensors for visible and infrared radiation that are smaller, more sensitive and lower in cost than quantum or thermal detectors. Microcantilevers coated with a heat absorbing layer undergo bending due to the differential stress originating from the bimetallic effect. This paper reports a micromachined silicon uncooled thermal imager intended for applications in automated process control. This paper presents the design, fabrication, and the behavior of cantilever for thermomechanical sensing.