• Smart Structures and Systems
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• v.25 no.2
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• pp.169-181
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• 2020

Sensor placement is a crucial aspect of bridge health monitoring (BHM) dedicated to accurately estimate and locate structural damages. In addressing this goal, a sensor placement framework based on the deflection influence line (DIL) analysis is here proposed, for the optimal design of damage detection-oriented BHM system. In order to improve damage detection accuracy, we explore the change of global stiffness matrix, damage coefficient matrix and DIL vector caused by structural damage, and thus develop a novel sensor placement framework based on the Fisher information matrix. Our approach seeks to determine the contribution of each sensing node to damage detection, and adopts a distance correction coefficient to eliminate the information redundancy among sensors. The proposed damage detection-oriented optimal sensor placement (OSP) method is verified by two examples: (1) a numerically simulated three-span continuous beam, and (2) the Pinghu bridge which has existing real damage conditions. These two examples verify the performance of the distance corrected damage sensitivity of influence line (DSIL) method in significantly higher contribution to damage detection and lower information redundancy, and demonstrate the proposed OSP framework can be potentially employed in BHM practices.

• Journal of the Korean Society of Clothing and Textiles
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• v.31 no.5 s.164
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• pp.717-728
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• 2007

The purpose of this study is to suggest hospital clothing design which reflects ubiquitous info-communications technology as changing hospital environment in the information-oriented era of the 21st century. The methods of this study are documentary research of previous studies, observation research and deep interviews. Seoul national university hospital is selected as a target of observation for this study. Doctors, nurses, pharmacists, and patients who are the representative jobs in the hospital are interviewed from on July, 13, 2006 to on August, 1, 2006. According to observation research, the computers, OCR, and PACS are applied from registration to dosage through all courses of diagnosis. However, the most inconvenient problems to patients are the location of medical offices and confusion of reservation. Also, the needs and inconveniences of doctors, nurses, pharmacists, and patients are almost solved by using RFID technology as a result of deep interviews. They prefer wearing devices as an accessory to wearing devices as a clothing directly. In conclusion, suggested UFC design for hospital clothing with info-communications technology promotes efficiency, accuracy, convenience of work to medical personnel in changing hospital environment as the flow of the information-oriented era of the 21st century.

• Journal of Power Electronics
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• v.11 no.2
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• pp.120-131
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• 2011

This paper proposes two control strategies for the bidirectional Z-source inverters (BZSI) supplied by batteries for electric vehicle applications. The first control strategy utilizes the indirect field-oriented control (IFOC) method to control the induction motor speed. The proposed speed control strategy is able to control the motor speed from zero to the rated speed with the rated load torque in both motoring and regenerative braking modes. The IFOC is based on PWM voltage modulation with voltage decoupling compensation to insert the shoot-through state into the switching signals using the simple boost shoot-through control method. The parameters of the four PI controllers in the IFOC technique are designed based on the required dynamic specifications. The second control strategy uses a proportional plus resonance (PR) controller in the synchronous reference frame to control the AC current for connecting the BZSI to the grid during the battery charging/discharging mode. In both control strategies, a dual loop controller is proposed to control the capacitor voltage of the BZSI. This controller is designed based on a small signal model of the BZSI using a bode diagram. MATLAB simulations and experimental results verify the validity of the proposed control strategies during motoring, regenerative braking and grid connection operations.

• Journal of Korean Institute of Industrial Engineers
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• v.12 no.1
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• pp.119-131
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• 1986

Described in this paper is a modelling methodology for mass production system simulation. The mass production system under consideration consists of various types of flow lines, special purpose production facilities, conveyor lines, palletized carts, and storage facilities. This type of production system is typical in home appliance industry, automobile industry, footwear industry, etc. where a variety of product mix are mass-produced. The modelling methodology is based on the "discrete-event formalism", and an "activity-oriented world view" is adopted to formalize the system description. A distinctive feature of the modelling methodology is that only the static structure (ie, system components) is included in the fixed model. The dynamic structure of the system is specified through a "data-driven" mechanism, which is an extension of the "experimental frame" concept. Each type of system components (ie, flow line, conveyors, carts, etc.) is formally modeled by using Activity Cycle Diagrams. The issue of "model structuring" is also addressed. The modeling methodology has been successfully applied in a real simulation study of a mass production system.

• Journal of Biomedical Engineering Research
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• v.38 no.4
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• pp.205-210
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• 2017

The convergence healthcare industry in Korea has been stalled due to conflicts between stakeholders as well as a supplier-centered industry structure. This situation is caused by the structural contradiction in which the Korean industry has a prolonged conflict structure among stakeholders due to a strong regulation and an institutional inertia from the viewpoint of the sociotechnical system. Therefore, it is necessary to identify new system management plan that enhances social acceptability such as laws, customs and ideas while reducing conflicts between stakeholders. In this study, mainly adapting the stakeholder-oriented autopoiesis and focusing on publicness of healthcare, we propose the rationale and direction for policy making to harmonize various systems within the convergence healthcare industry.

• Korean Journal of Computational Design and Engineering
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• v.17 no.1
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• pp.35-44
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• 2012

Many automobile manufacturers are doing experiment on manufacturing environments by using an augmented reality technology. However, system layout and process simulation by using the virtual reality technology have been performed actively more than by using the augmented reality technology in practical use so far. Existing automobile assembly by using the augmented reality requires the precise calibrating work after setting the robot because the existing augmented reality system for the automobile assembly system configuration does not include the end tip deflection and the robot joints deflection due to the heavy weight of product and gripper. Because the robot is used mostly at the automobile assembly, the deflection problem of the robot joint and the product in the existing augmented reality system need to be improved. Moreover camera lens calibration has to be performed precisely to use augmented reality. In order to improve this problem, this paper introduces a method of the software based calibration to apply the augmented reality effectively to the automobile assembly system. On the other hand, the camera lens calibration module and the direct compensation module of the virtual object displacement for the augmented reality were designed and implemented. Furthermore, the developed automobile assembly system oriented AR-system was verified by the practical test.

• Journal of Technology Innovation
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• v.4 no.1
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• pp.1-26
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• 1996

Traditional studies of new venture performance have focused on the characteristics of entrepreneurs and have shown conflicting results on the relationship between the characteristics and performance of new ventures. Recently, some researchers have broadened their search to include aspects of the industry and the strategy of new ventures. The purposes of this study are to identify wtrategic archetypes of new ventures based on the taxonomic approach and to explain the differences in new venture characteristics and performance among strategic archetypes. To find the strategic archetypes, 114 new venture CEOs from various industries were asked to describe their ventures' competitive strategy through 19 questionnaire items on competitive methods. Using factor analysis and subsequent cluster analysis, four archetypes were identified such as : versatile type, technology-driven type, market-oriented type, and cost reduction type. The results imply that there exist different types of venture strategy even among new technology-based venture firms in Korea, and show the differences in performance among strategic archetypes: market-oriented type and versatile type are better than cost reduction type in terms of growth rate and profitability. Because the venture strategy in identified as a major determinant of the venture performance in this study, the choice of venture strategy suitable for firm's industrial characteristics and internal resource bases becomes a very strategic decision for firm's sustained growth. Further studies are needed to strengthen some methodological limitations of the study.

• Journal of the Korea Society of Computer and Information
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• v.20 no.12
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• pp.137-143
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• 2015

This study is looking to do a new model which overcomes emotional isolation phenomenons of aged people through using an advanced technology in our community approaching an aging society. Senior welfare has been oriented to economically, medically supported welfare model so far. An ageing society going on, even if the scale of welfare cost is bigger and bigger, the level of satisfaction has been decreasing. This is the fact that the expansion of economical support for the aged in emotional alienation is not only a solution for them suffering from emotional isolation phenomenons, which requires a new model for senior welfare. Above all, because the senior welfare oriented to economically, medically supported welfare model can not be continued any more, a new model is required to be sustainable in national finance. This study has a purpose that recovers emotional life of the aged, improves their quality of life, and offers emotional welfare model to be sustainable economically.

• Journal of The Korean Society of Agricultural Engineers
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• v.56 no.5
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• pp.29-36
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• 2014

The purpose of this study is to improve the Generic Agricultural Systems Simulator (GASS) which can simulate various rural systems based on object-oriented model. GASS provides the configuration platform of various system components to simplify integrated agricultural system models such as irrigation systems for rice farming. The new connection and communication modules of GASS improve applicability for modelling diverse systems. The geometric connection of GASS replaces topological connection, and communication protocols expand to analyze not only homogeneous system but also heterogeneous system. In this paper, we applied GASS2 to simulate the water heights of linked tanks and the simulation outputs were verified through comparing with analytical solutions of differential equations. The two new modules make it possible to analyze the 4-tank problem which includes topological and heterogenous issues with GASS2.

• Carbon letters
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• v.5 no.3
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• pp.108-112
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• 2004

Effect of silicon infiltration on the bend and tensile strength of 2D cross-ply carbon-carbon composites are studied. It is observed that bend strength higher than tensile strength in both types of composite is due to the different mode of fracture and loading direction. After silicon infiltrations bend and tensile strength suddenly decreases of carbon-carbon composites. This is due to the fact that, after silicon infiltration, silicon in the immediate vicinity of carbon forms the strong bond between carbon and silicon by formation silicon carbide and un-reacted silicon as free silicon. Therefore, these composites consist of three components carbon, silicon carbide and silicon. Due to mismatch between these three components secondary cracks developed and these cracks propagate from $90^{\circ}$ oriented plies to $0^{\circ}$ oriented plies by damaging the fibers (i.e., in-situ fiber damages). Hence, secondary cracks and in-situ fiber damages are responsible for degradation of mechanical properties of carbon-carbon composites after silicon infiltration which is revealed by microstructure investigation study by scanning electron microscope.