• ETRI Journal
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• v.38 no.2
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• pp.217-226
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• 2016

We propose an architecture that reduces the power consumption and active area of such a modulator through a reduction in the number of active components and a simplification of the topology. The proposed architecture reduces the power consumption and active area by reducing the number of active components and simplifying the modulator topology. A novel second-order loop filter that uses a single operational amplifier resonator reduces the number of active elements and enhances the controllability of the transfer function. A trapezoidal-shape half-delayed return-to-zero feedback DAC eliminates the loop-delay compensation circuitry and improves pulse-delay sensitivity. These simple features of the modulator allow higher frequency operation and more design flexibility. Implemented in a 130 nm CMOS technology, the prototype modulator occupies an active area of $0.098mm^2$ and consumes 5.23 mW power from a 1.2 V supply. It achieves a dynamic range of 62 dB and a peak SNDR of 60.95 dB over a 15 MHz signal bandwidth with a sampling frequency of 780 MHz. The figure-of-merit of the modulator is 191 fJ/conversion-step.

• Structural Monitoring and Maintenance
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• v.3 no.3
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• pp.297-314
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• 2016

As the study of internal corrosion of pipeline need a large number of experiments as well as long time, so there is a need for new computational technique to expand the spectrum of the results and to save time. The present work represents a new non-destructive evaluation (NDE) technique for detecting the internal corrosion inside pipeline by evaluating the dielectric properties of steel pipe at room temperature by using electrical capacitance sensor (ECS), then predict the effect of pipeline environment temperature (${\theta}$) on the corrosion rates by designing an efficient artificial neural network (ANN) architecture. ECS consists of number of electrodes mounted on the outer surface of pipeline, the sensor shape, electrode configuration, and the number of electrodes that comprise three key elements of two dimensional capacitance sensors are illustrated. The variation in the dielectric signatures was employed to design electrical capacitance sensor (ECS) with high sensitivity to detect such defects. The rules of 24-electrode sensor parameters such as capacitance, capacitance change, and change rate of capacitance are discussed by ANSYS and MATLAB, which are combined to simulate sensor characteristic. A feed-forward neural network (FFNN) structure are applied, trained and tested to predict the finite element (FE) results of corrosion rates under room temperature, and then used the trained FFNN to predict corrosion rates at different temperature using MATLAB neural network toolbox. The FE results are in excellent agreement with an FFNN results, thus validating the accuracy and reliability of the proposed technique and leads to better understanding of the corrosion mechanism under different pipeline environmental temperature.

• Journal of Sensor Science and Technology
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• v.26 no.6
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• pp.379-385
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• 2017

In this study, an amperometric non-enzymatic glucose sensor was developed on the surface of a glassy carbon electrode by simply drop-casting the synthesized homogeneous suspension of hexagonal boron nitride (h-BN) nanosheets with a copper metal-organic framework (Cu-MOF) composite. Comprehensive analytical methods, including field-emission scanning electron microscopy (FE-SEM), Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), cyclic voltammetry, electrochemical impedance spectroscopy, and amperometry, were used to investigate the surface and electrochemical characteristics of the h-BN-Cu-MOF composite. The FE-SEM, FT-IR, and XRD results showed that the h-BN-Cu-MOF composite was formed successfully and exhibited a good porous structure. The electrochemical results showed a sensor sensitivity of $18.1{\mu}A{\mu}M^{-1}cm^{-2}$ with a dynamic linearity range of $10-900{\mu}M$ glucose and a detection limit of $5.5{\mu}M$ glucose with a rapid turnaround time (less than 2 min). Additionally, the developed sensor exhibited satisfactory anti-interference ability against dopamine, ascorbic acid, uric acid, urea, and nitrate, and thus, can be applied to the design and development of non-enzymatic glucose sensors.

• Wind and Structures
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• v.28 no.5
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• pp.331-345
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• 2019

Long-span bridge decks are often shaped as streamlined to improve the aerodynamic performance of the deck. There are a number of important shaping parameters for a streamlined bridge deck. Their effects on aerodynamics should be well understood for shaping the bridge deck efficiently and for facilitating the bridge deck design procedure. This study examined the effect of various shaping parameters such as the bottom plate slope, width ratio and side ratio on aerodynamic responses of single box streamlined bridge decks by employing unsteady RANS simulation. Steady state responses and flow field were analyzed in detail for wide range of bottom plate slopes, width and side ratios. Then for a particular deck shape Reynolds number effect was investigated by varying its value from $1.65{\times}10^4$ to $25{\times}10^4$. The aerodynamic response showed very high sensitivity to the considered shaping parameters and exhibited high aerodynamic performance for a particular combination of shaping parameters.

• Journal of Sensor Science and Technology
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• v.33 no.3
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• pp.173-178
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• 2024

Development of pressure sensors for harsh environments with high pressure, humidity, and temperature is essential for many applications in the aerospace, marine, and automobile industries. However, existing materials such as polymers, adhesives, and semiconductors are not suitable for these conditions and require materials that are less sensitive to the external environment. This study proposed a pressure sensor that could withstand harsh environments and had high durability and precision. The sensor comprised a piezoresistor pattern and an insulating film directly formed on a stainless-steel membrane. To achieve the highest sensitivity, a pattern design method was proposed that considered the stress distribution in a circular membrane using finite element analysis. The manufacturing process involved depositing and etching a dielectric insulating film and metal piezoresistive material, resulting in a device with high linearity and slight hysteresis in the range of a maximum of 40 atm. The simplicity and effectiveness of this sensor render it a promising candidate for various applications in extreme environments.

• Korean Institute of Interior Design Journal
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• v.21 no.1
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• pp.68-77
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• 2012

Appreciating the aspect of modem architecture requires not only the comprehension of the nature of design and architects' ways of thinking and expression but also observers' views on buildings and their perceptive/cognitive stages. This calls for an in-depth study on the "system of phenomenological perceptions" that works as a new architectural experience system. The system of phenomenological perceptions makes it possible to specify the individual process of understanding architecture, that is, hands-on experiences, participations, feelings, perceptions, and cognition. The value of user experience and cognition has been emphasized by philosophical and aesthetical concepts as well. Therefore, in order to better appreciate the modern architecture, this study suggests theoretical consideration to "orientation and event" that are crucial elements in understanding a phenomenological view and materializing actual space formation. This offers the cognitive system with which we analyze modem architecture and comprehensive expressional methods. In other words, this study contemplates the system of phenomenological perceptions from an existential spatial perspective by structurizing the system of the orientation and the event in order to segmentalize users' current locations, potential directions, the relations with spaces, continual vie'wpoints as well as buildings' functions and interior and exterior division. The system of phenomenological perceptions helps understand and systemize modern architecture through a system based on relations between sensation, perception, cognition, sensitivity, and rationality. This creates a new cognitive system employing the concept of the orientation and the event, which is different from a normal cognitive system basing on the sense of vision. When observers appreciate space, they tend to relate the space to a certain event and to remember their experiences in it. During the process, they draw borders of the space in which the event takes place and give shape to their experiences including actions, movements, cognition and sensation. The process leads to the formation of "placeness," and here, the concept of the orientation comes in as the location and the center of the placeness. This study proves that a determined orientation coupled with individual experience and events settles the place ness; detailed elements in the cognitive system have close relations with one another; the orientation, actions, events, and places are the factors that materialize observers' architectural experience.

• The Journal of the Acoustical Society of Korea
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• v.34 no.3
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• pp.200-209
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• 2015

An underwater sound surveillance system detects and tracks enemy ships in real-time using hydrophone arrays, in which seabed-mounted sensor arrays play a pivotal role. In this paper the conceptual design of seabed-mounted, cylindrical hydrophone arrays for use in shallow coastal waters is performed via finite element calculations. To stabilize the receiving characteristics under the ocean ambient noise, a technique for whitening the ambient noise spectrum using a metal baffle is proposed. Optimization of the array configuration is performed to achieve the directivity in the vertical and azimuthal directions. And the effects of the sonar dome shape and material on the structural vibration and sound scattering properties are studied. It is demonstrated that a robust hydrophone array, having a sensitivity deviation less than 4 dB over the frequency range of interest, can be obtained through the whitening of the ambient noise, the optimization of the array configuration, and the design of acoustically transparent sonar domes.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.2
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• pp.38-45
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• 1999

In this paper, A novel approach on $H_{\infty}-LTR$ design scheme is presented. The proposed scheme provides a design toll which can trade-off the recovery error against the control input. In the first stage, Kalman filter is designed to shape the loop to satisfy the required performance specifications. The designed Kalman filter, together with the plant transfer function, is used as a target transfer function. In the second stage, sensitivity function weighted $H_{\infty}-LTR$suboptimal LTR is designed to recover the target loop transfer function. Simulation results of LQG/LTR, $H_{\infty}-LTR$are compared to demonstrate the good property of the proposed scheme.

• Journal of the Korean Home Economics Association
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• v.39 no.8
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• pp.137-154
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• 2001

This study was made to draft the tight fitting bodice pattern which horizontal and perpendicular stands are to be lightly set, with the consideration of characteristics of body shape in design of clothes. Measurement of body was conducted on 53 women in twenties, and observation was made on surface development pattern by adhesive tape addition method and gypsum method on three standard objects. In the study, bodice pattern was completed by using already made Somato- measurer, compared with existing bodice pattern, and the results are as follows. The result of the correlation analysis by body measurement shows that chest circumference has a relation to B$.$P-front neck point, side neck point, shoulder point, front interscye breadth point, and the item in spine scapulae point has relation to the item of back neck line, and front & back horizontal values. The degree of shoulder slant, width of armhole and of its depth, the amount of breast, back space, back length were shown to be directly measured from the body. In surface development pattern, tight-fit bodice pattern necessary to the breast volume and back space were shown to be investigated and these volume have to be given in setting up basic line for clothes design together with body measurement value. The result of sensory evaluation for appearance test on fitness shows higher value of research bodice including line of shoulder line, front and back interscye breadth, chest circumference, waist circumference, armhole circumference and of its depth, compared with the research bodice in most items. The result of this study is seen showing high effectiveness for the basic data to design the ready-made dress of high sensitivity of high value added tat.

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