Experimental Mechanics in Nano and Biotechnology

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Authors: Yun Young Kim, Sung Chul Shin, Jae Yong Ko
Abstract: The optimum design for a bow structure of high tensile steel yacht belongs to the nonlinear constrained optimization problem. The determination of scantling for the bow structure is a very crucial matter out of whole structural design process of a yacht. This determination may be a process of satisfying a lot of complicated design constraints empirically, rather than optimizing some objective function. However, in order to realize optimum or rational design for bow structure with complicated design constraints, it is necessary to model the design problem as strictly as possible and to accomplish more highly numerical optimization. Real-coded Micro-Genetic Algorithm is proposed to find the optimum scantling for the bow structure of high tensile steel yacht without handling any of penalty functions.
Authors: Jong Ha Chung, Jin Seok Heo, Myoung Sik Won, Woo Yong Lee, Jung Ju Lee
Abstract: The transformation kinetics formulation is the principal factor underlying the constitutive model of shape memory alloys. Therefore, the transformation kinetics formulation, which is applicable to any status of stress and temperature, is essential for predicting the material behavior of SMAs. In this work, we show that the transformation kinetics of the Brinson model, which is the most widely used 1-dimensional model, has shortcomings under certain stress and temperature histories. In addition, we propose a modified transformation kinetics model that can be used for any stress or temperature conditions. The martensite transformation kinetics is modified so that the transformation from austenite into temperature-induced martensite, due to the decrement of temperature, is coupled with a transformation from austenite or temperature-induced martensite into stress-induced martensite, due to the increment of the stress. Through this modification, the suggested model can simulate the behavior of shape memory alloy materials under arbitrarily changed circumstances at every stress-temperature region.
Authors: Jea Hong Kwon, Kyong Soo Lee, Byeong Kwon Ju
Abstract: The concentration of the hydroxyl radical is a critical parameter to be measured for monitoring the condition of aqueous biological species, or for predicting the path of chemical reactions. This paper describes a novel method for fabricating a very simple and fast response pH sensor compose of single walled-carbon nanotubes (SW-CNTs) using an ultra-precision spray. Such CNT-based sensor shows amperometric response in buffer solution at different hydroxyl radical concentrations and electrical conductance of SW-CNTs depends on the pH value. Our results suggest that sprayed CNT sensors are potential candidates as biosensors in future large-scale throughput devices.
Authors: Dong Seok Oh, Young Ho Lee, Chang Hwan Shin, Tae Hyun Chun, Hyung Kyu Kim, Kye Bock Lee
Abstract: A new device for measuring an acceleration in a fuel rod has been developed. The primary purpose is to apply it to the experiments for a nuclear fuel fretting, which is caused by a fuel rod and grid interaction due to a flow-induced vibration of the rods. A bi-axial accelerationdetecting device of a cylindrical shape for an insertion into a cladding tube is designed. Two unimorph piezoelectric accelerometers of small size and for special use in a high temperature condition were attached to the housing’s inner wall of the mounting device, which were oriented perpendicularly with each other to accommodate the acceleration signal during a fretting. Verification is carried out by a displacement and a frequency response analysis. The verification results of the bi-axial acceleration-detecting device showed a good response for the amplitude and bi-directional trace. This paper mainly presents the detailed design of the bi-axial accelerationdetecting device which is developed by using the design optimization of a cylindrical type and applying it to the lower and upper plugs to sustain the device in the tube wall. The verification is carried out by a displacement analysis and a frequency response analysis. An elaboration of the development procedure, calibration method and results are also given in this paper.
Authors: Won Youl Choi, Jun Sik Hwang, Sang On Choi
Abstract: We have developed a micro fluxgate magnetic sensor using new printed circuit board (PCB) technology. The fluxgate sensor consisted of five PCB stack layers including one layer of magnetic core and four layers of excitation and pick-up coils. The center layer as a magnetic core was made of micro patterned amorphous magnetic ribbon with an extremely high DC permeability of ~100,000, and the core had a rectangular ring shape. Four outer layers as an excitation and pickup coils had a planar solenoid structure. The amorphous magnetic core was easily saturated due to the high permeability, low coercive field, and closed magnetic path for the excitation field. The chip size of the fabricated sensing element was 7.3 × 5.7 mm2. Excellent linear response over the range of –100 μT to +100 μT was obtained with sensitivity of 780 V/T at excitation sine wave of 3 Vp-p and 360 kHz. A very low power consumption of ~8 mW was measured. This low power, small size, and high sensitive fluxgate sensor to measure a low magnetic field is very useful for various applications.
Authors: Won Kyu Jeung, Chang Hyun Lim, Tae Hoon Kim, Seog Moon Choi
Abstract: A novel rectangular shape microlens array having high sag for solid-state lighting is presented. The rectangular shape of proposed microlens can maximize the fill factor of silicon based light-emitting-diode (LED) packaging and minimize the optical loss through the reduction of unnecessary reflection at the same time. Microlens, which has high sag, over 3 75 μm and large diameter, over 3 mm can enormously enhance output optical extraction eff iciency. Moreover wafer level packaging technology is adopted to improve the aligning accu racy and mass production of LED packaging. This wafer level microlens array can be direc tly fabricated on LED packaging using replication method. It has many advantages in optica l properties, low cost, high aligning accuracy, and mass production.
Authors: Chul Hyun, Jang Gyu Lee, Tae Sam Kang
Abstract: This paper presents an oscillation loop for an INS (Inertial Navigation System) grade, surface micro-machined resonant type accelerometer. This resonant type sensor utilizes the electrostatic stiffness changing effect of an electrostatic actuator. This device produces a frequency output upon an applied acceleration. A closed loop system called self-sustained oscillation loop is prerequisite for its operation as a resonant accelerometer. A self-sustained oscillation loop induces the system’s dynamic states into its primary mode, thus keeps track of its resonant state under applied acceleration or perturbation. For this, a simple self-sustained oscillation loop is designed and the feature of the loop is analyzed in the viewpoint of nonlinear dynamic system. From the standpoint of feedback control system, both determination of resonance point and its stability analysis are required. In the actual system, which has several noise sources, noise can affect the output resonant frequency. We analyzed the effect of a noise on oscillation frequency. Finally, simulation and experimental result is given
Authors: Shao Peng Wu, Xiao Ming Liu, Lian Tong Mo, Qun Shan Ye
Abstract: Fatigue damage self-monitoring mechanism of graphite modified asphalt-based composite materials is demonstrated in this paper, as damage (occurring in the 70% of fatigue life) caused the volume electrical resistance to increase irreversibly. Results showed that when the initial resistance is relatively high (10k), the resistance variation sensitivity of microcrack is lower, but it has relatively high sensitivity to microcrack when the initial resistance 1k. The longer the loading time, the greater the damage, and the greater the resistance increases monotonically occurred. The resistance increase is attributed to the proximity effect, microcrack and the disconnection of conductive paths due to shear strength of aggregates. The self-monitoring mechanism of damage is the resistance change aroused by the variation of interior structure.
Authors: Xian Hui Song, Li Xia Zheng, Zhuo Qiu Li
Abstract: Carbon fiber reinforced concrete (CFRC) structures exhibit both strain sensibility and temperature sensibility, which are coupled with each other when used in traffic or health monitoring for concrete structures. This coupling property results in inaccurateness of measured deformation. In this paper Four-probe Difference Method is used to detach the above two effects according to loaded conditions of structures and different characteristics of the two effects. The theoretical and experimental results indicate that the method is feasible and effective.
Authors: Heung Soo Kim, Jae Hwan Kim, Li Jie Zhao, Sang Dong Jang, Kyu Young Yun, Sun Kon Lee
Abstract: The application of electroactive polymer devices requires the availability of their properties at various operating conditions. This in turn necessitates a structure-property relationship based on an in-depth understanding of the underlying mechanism responsible for their strain-field response. Cellulose-based Electro-Active Paper (EAPap) has been studied as an attractive Electro Active Polymer (EAP) material for artificial muscles. The feasibility of EAPap material as an actuator/sensor application is greatly dependant on piezoelectric effect. In this paper, converse and di rect piezoelectric ef fect s of Electro-Active Paper materials are studied to characterize piezoelectric effects of EAPap. All experiments were conducted in an environmental chamber that can control temperature and humidity.

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