• 한국생산제조학회지
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• 제25권4호
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• pp.295-300
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• 2016

In the design of passive and active boring bars, the structural dimensions and shape of the vibration control boring bar are modified depending on the diameter and depth of the workpiece, which changes the dynamic behavior. Thus, the natural frequency, effective mass, and stiffness for the main structure of a tube-type boring bar need to be reset for each vibration control case. However, commercial finite element method (FEM) software and experimental modal analysis are mostly used at present despite being too time-consuming. To overcome the weaknesses of the two methods currently used for vibration control, we realized a graphical user interface (GUI) program for the modal analysis of a modified tube-type damping structure. The analysis results with the GUI program were compared to those with commercial FEM software in order to confirm the effectiveness of the former.

• Structural Engineering and Mechanics
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• 제11권4호
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• pp.341-356
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• 2001

A new class of semi-active tuned mass dampers, named as "Ground Hook Tuned Mass Damper" (GHTMD) is introduced. This TMD uses a continuously variable semi-active damper (so called 'Ground-Hook') in order to achieve more reduction in the vibration level. The ground-hook dampers have been used in the auto-industry as a means of reducing the vibration of primary suspension systems in vehicles. This paper investigates the application of this damper as an element of a tuned damper for the vibration reduction of force-excited single degree of freedom (SDOF) models that can be representative of many structural systems. The optimum design parameters of GHTMDs are obtained based on the minimization of the steady-state displacement response of the main mass. The optimum design parameters which are evaluated in terms of non-dimensional values of the GHTMD are obtained for different mass ratios and main mass damping ratios. Using the frequency responses of the resulting systems, performance of the GHTMD is compared to that of equivalent passive TMD, and it is found that GHTMDs are more efficient. A design methodology to obtain the tuning parameters of GHTMD using the relationships developed in this paper is presented.

• 한국의류학회지
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• 제16권1호
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• pp.3-21
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• 1992

The main objective of this study was to find out the relationship between life style types and clothing evaluatie criteriria. Social wear was selected according to the defined time, place, and occasion's. The questionnaire was administered to 640 housewives during the fall of 1988. The research problems were as follows: 1. To segment the target according to their life styles, and to profile the characteristics of the categorized life style types. 2. To determine the differences in the clothing evaluatie criteria among the various life style types. The result were as follows: 1. Five life style types were defined. They were the Achievement oriented type, the Active- leisure type, the Material oriented type, Conservative-frugal type, and the Passive-stagnant type. 2. The differences in consumer preferences at the element level evaluative criteria including color, fiber content, fabric construction, fabric design, and classes of clothes among the five life style types were also analyzed revealing partial significance.

• Smart Structures and Systems
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• 제17권5호
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• pp.773-793
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• 2016

This work presents a methodology to distribute piezoelectric material for structural vibration active control. The objective is to design controlled structures with actuators which maximizes the system controllability. A topology optimization was formulated in order to distribute two material phases in the domain: a passive linear elastic material and an active linear piezoelectric material. The objective is the maximization of the smallest eigenvalue of the system controllability Gramian. Analytical sensitivities for the finite element model are derived for the objective functions and constraints. Results and comparisons with previous works are presented for the vibration control of a two-dimensional short beam.

• Structural Engineering and Mechanics
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• 제53권5호
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• pp.1031-1049
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• 2015

This paper highlights the role of innovative vibration control system based on two promising properties in a parallel configuration. Hybrid device consists of two main components; recentering wires of shape memory alloy (SMA) and steel pipe section as an energy dissipater element. This approach concentrates damage in the steel pipe and prevents the main structural members from yielding. By regulation of the main adjustable design parameter, an optimum performance of the device is obtained. The effectiveness of the device in passive control of structures is evaluated through nonlinear time history analyses of a five-story steel frame with and without the hybrid device. Comparing the results proves that the hybrid device has a considerable potential to mitigate the residual drift ratio, peak absolute acceleration and peak interstory drift of the structure.

• 산업기술연구
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• 제28권B호
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• pp.123-127
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• 2008

This paper studied the sensitivity characteries of the electronic ballast for the discharge lamps, which implies variation ratio of the output power by the passive element variation. We have derived the equation to represent the lamp power, and obtained the sensitivity characteristic equations. The simulation result shows that the proposed equations are correct and very useful to design the electronic ballast with the LCpCs-type resonant tank.

• 한국주거학회논문집
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• 제17권4호
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• pp.145-153
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• 2006

Ubiquitous space can be described as a combined space of physical space and digital space. Ubiquitous space possesses new possibilities by combining the two. The concept of ubiquitous home will bring new changes in residential space design. First of all, it makes possible for more convenient and secure home. It has to be developed along with city and town level changes as ubiquitous environment. Secondly, concept of extended space as an extension of living space becomes possible by linking with outside spaces. Thirdly, as consumer requirements for residential spaces will become more versatile by social changes, ubiquitous home can be a good means to meet these versatile consumer requirements by accommodating concept of multi-functional space and flexible space. It is quite important to predict user requirements in rapidly changing social environment and versatile personal inclinations. Instead of POE methodology which can analyze and evaluate in exiting types of designs, storytelling methodology can be used to predict and direct for future requirements of living. The methodology makes scenarios of space usage for future living and extracts design requirements for the living. The concept of intelligent space has to be introduced. It is different from digital home that only accomodate digital devices in space. In intelligent space, space itself has to be recognized as an identity that interacts human directly. Intelligent space recognize human requirements and control digital devices as a response. Multi-functional space is closely related with intelligent space that can changes for business, entertainments as well as for rests by user requirements instantly. Flexible space that also intends to meet requirements of mobility and versatility can be attained through the integration of digital technology into current physical mobile systems. Interaction design becomes integral part for ubiquitous space design along with physical design. For the residential space design, digital illiteracy has to be considered for interaction design. Instead of the concept of passive existence, space itself has to be recognized as active subsistence that reacts with human. Intuitive and natural interaction for human will be a key design element for space-human interface design.

• Transactions on Electrical and Electronic Materials
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• 제17권2호
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• pp.79-85
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• 2016

In this study, we proposed a new single-stage small power MH lamp electronic ballast and power-factor correction circuit with improved circuit by the current of passive power factor correction. Main circuit integrates traditional DC/DC and DC/AC circuits into one-stage DC/AC inverter. Moreover, we described the working principle and control strategy of the new circuit; it's soft switching principle; and resonant element parameter design formula. An experimental prototype of HID lamp electronic ballast with output power of 70 W was built to verify the feasibility of the analysis and design. The simulation and experimental results proved that the power factor of this circuit could reach 94%, with efficiency of 90%. The input current harmonics conform to IEC 61000-3-2 standards and its cost is low. These superior performances of the new circuit indicate certain practical values.

• ETRI Journal
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• 제28권1호
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• pp.9-16
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• 2006

In this paper, we analyzed and measured the electrical crosstalk characteristics of a 1.25 Gbps triplexer module for Ethernet passive optical networks to realize fiber-tothe-home services. Electrical crosstalk characteristic of the 1.25 Gbps optical triplexer module on a resistive silicon substrate should be more serious than on a dielectric substrate. Consequently, using the finite element method, we analyze the electrical crosstalk phenomena and propose a silicon substrate structure with a dummy ground line that is the simplest low-crosstalk layout configuration in the 1.25 Gbps optical triplexer module. The triplexer module consists of a laser diode as a transmitter, a digital photodetector as a digital data receiver, and an analog photodetector as a cable television signal receiver. According to IEEE 802.3ah and ITU-T G.983.3, the digital receiver and analog receiver sensitivities have to meet -24 dBm at $BER=10^{-12}$ and -7.7 dBm at 44 dB SNR. The electrical crosstalk levels have to maintain less than -86 dB from DC to 3 GHz. From analysis and measurement results, the proposed silicon substrate structure that contains the dummy line with $100\;{\mu}m$ space from the signal lines and 4 mm separations among the devices satisfies the electrical crosstalk level compared to a simple structure. This proposed structure can be easily implemented with design convenience and greatly reduce the silicon substrate size by about 50 %.

• 대한전자공학회논문지TC
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• 제43권12호
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• pp.75-82
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• 2006

본 논문에서는 개구를 갖는 접지면의 높은 특성 임피던스를 이용하여 주파수에 대한 민감도가 좋고 높은 품질 계수를 갖는 미앤더 라인 인덕터들을 설계하였다. 주파수에 대한 민감도는 자기 공진 주파수 (SRF) 대신에 해석 주파수 범위에 대한 유효 인덕턴스 변화량으로 새로 정의 되었다. 등가 집중 소자 회로는 고주파 인덕터의 특성을 설명하기 위해 전개되었다. 개구 접지면을 갖는 4 nH 미앤더 라인 인덕터는 0.45 nH/GHz의 좋은 민감도와 0.7 GHz에서 86의 Q 값을 갖는다.