• Smart Structures and Systems
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• v.5 no.4
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• pp.369-379
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• 2009

The sudden collapse of Interstate 35 Bridge in Minneapolis gave a wake-up call to US municipalities to re-evaluate aging bridges. In this situation, structural health monitoring (SHM) technology can provide the essential help needed for monitoring and maintaining the nation's infrastructure. Monitoring long span bridges such as cable-stayed bridges effectively requires the use of a large number of sensors. In this article, we introduce a probabilistic approach to identify optimal locations of sensors to enhance damage detection. Probability distribution functions are established using an artificial neural network trained using a priori knowledge of damage locations. The optimal number of sensors is identified using multi-objective optimization that simultaneously considers information entropy and sensor cost-objective functions. Luling Bridge, a cable-stayed bridge over the Mississippi River, is selected as a case study to demonstrate the efficiency of the proposed approach.

• Smart Structures and Systems
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• v.5 no.2
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• pp.139-152
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• 2009

Globally, civil infrastructures are deteriorating at an alarming rate caused by overuse, overloading, aging, damage or failure due to natural or man-made hazards. With such a vast network of deteriorating infrastructure, there is a growing interest in continuous monitoring technologies. In order to provide a true distributed sensor and control system for civil structures, we are developing a Structural Nervous System that mimics key attributes of a human nervous system. This nervous system is made up of building blocks that are designed based on mechanoreceptors as a fundamentally new approach for the development of a structural health monitoring and diagnostic system that utilizes the recently developed piezo-fibers capable of sensing and actuation. In particular, our research has been focused on producing a sensory nervous system for civil structures by using piezo-fibers as sensory receptors, nerve fibers, neuronal pools, and spinocervical tract to the nodal and central processing units. This paper presents up to date results of our research, including the design and analysis of the structural nervous system.

• Smart Structures and Systems
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• v.5 no.4
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• pp.469-482
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• 2009

The emerging sensor-based structural health monitoring (SHM) technology has a potential for cost-effective maintenance of aging civil infrastructure systems. The author proposes to integrate continuous and global monitoring using on-structure sensors with targeted local non-destructive evaluation (NDE). Significant technical challenges arise, however, from the lack of cost-effective sensors for monitoring spatially large structures, as well as reliable methods for interpreting sensor data into structural health conditions. This paper reviews recent efforts and advances made in addressing these challenges, with example sensor hardware and health monitoring software developed in the author's research center. The hardware includes a novel fiber optic accelerometer, a vision-based displacement sensor, a distributed strain sensor, and a microwave imaging NDE device. The health monitoring software includes a number of system identification methods such as the neural networks, extended Kalman filter, and nonlinear damping identificaiton based on structural dynamic response measurement. These methods have been experimentally validated through seismic shaking table tests of a realistic bridge model and tested in a number of instrumented bridges and buildings.

• Proceedings of the Korean Society of Computer Information Conference
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• 2017.07a
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• pp.141-144
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• 2017

4차 산업혁명 시대에 살고 있는 현대인들은 혼자 사는 1인 가구의 증가와 고령화 사회의 진입으로 인한 실버세대가 증가하는 추세이다. 외로움, 소외감, 우울증을 겪는 1인 가구 및 실버세대의 문제점을 해소시켜 주고 더 나아가 실버세대의 스마트폰 활성화를 위해 본 논문에서는 인공지능 기반 음성인식 기능을 탑재한 'Voice' 어플리케이션을 제안하고자 한다.

• Smart Structures and Systems
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• v.20 no.6
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• pp.759-767
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• 2017

Wear and aging associated damage is a severe problem for safety and maintenance of engineering structures. To acquire structural operational state and provide warning about different types of damage, research on damage identification has gained increasing popularity in recent years. Among various damage identification methods, the Lamb wave-based methods have shown promising suitability and potential for damage identification of plate-type structures. In this paper, a comprehensive study was presented to elaborate four remarkable aspects regarding the Lamb wave-based damage identification method for plate-type structures, including wave velocity, signal denoising, image reconstruction, and sensor layout. Conclusions and path forward were summarized and classified serving as a starting point for research and application in this area.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1424-1426
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• 2003

PMN-PZT 적충형 세라믹 액츄에이터 소자를 제작한후 그 열화 특성을 조사하였다. 액츄에이터는 tape casting 방법으로 green sheet를 제작한후, screen printing방법을 이용하여 전극형상을 만들고, lamination과 cutting공정을 통하여 소자를 제작하였다. 작된 소자의 구조적인 특성을 분석하기 위하여 X-ray diffractometer를 사용하였으며, Doppler effect를 사용하는 laser vibrometer를 이용하여 전압에 따른 변위량을 측정하였다. 제작된 소자의 열화 특성을 알아보기 위하여 60 Hz의 triangular 교류 파형을 적충형 세라믹 액츄에이터에 인가하여 열화전과 후의 P-E hysteresis loop의 변화를 살펴보았으며, unipolar AC 전압을 지속적으로 인가하여 소자를 depling 시킴으로써 열화현상을 관찰하였다. 파단면에 대한 SEM 분석을 통하여 소자의 파괴 메카니즘을 알아 보도록 하였다. 이로부터 전기적, 기계적 열화가 소자의 동작에 미치는 영향에 대해서 알아 보았다.

• International journal of advanced smart convergence
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• v.10 no.4
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• pp.141-148
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• 2021

This study was tried to explore the mediating effect of workplace learning and self-efficacy on the relationship between technostress and job satisfaction in convalescent hospital nurses. Data were collected from 149 nurses working at one of 10 convalescent hospitals located in Korea's D region and between July 20 and August 12, 2019 and analyzed using SPSS 24.0. The mediating effects of workplace learning and self-efficacy in the relationship between technostress and job satisfaction were investigated by conducting hierarchical regression analysis and testing for significance based on bootstrapping p values. We found that workplace learning had a complete mediating effect, and self-efficacy a partial mediating effect, in the relationship between technostress and job satisfaction in convalescent hospital nurses. Exploring diverse factors and environmental features affecting job satisfaction in convalescent hospital nurses is highly relevant to clinicians, especially given the gradually increasing number of convalescent hospitals, changes during the era of technology fusion, and the strategic demands arising from an aging society.

• International Journal of Advanced Culture Technology
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• v.10 no.1
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• pp.242-247
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• 2022

This study analyzes the servicescape of a dog-friendly hotel, which is the most important element of travel with a dog, which is increasing as the types of families diversify, and intends to suggest implications for servicescape strategies to enhance competitiveness in the future. The number of households with companion animals is increasing in line with the aging of the population, changes in the demographic structure due to the rapid increase in single-person households, and increase in income. In order to successfully operate a hotel with companion animals, which cannot have all the facilities like a large hotel, we would like to segment the market according to the user's pursuit of convenience and propose an appropriate servicescape design method.

• International journal of advanced smart convergence
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• v.11 no.1
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• pp.70-75
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• 2022

The purpose of this study was to develop hand creams among the types of cosmetics based on domestic pumpkins grown in Yangju. Pumpkins are mostly used for cooking, but because they contain a large amount of vitamin A, they can also be used as raw materials for cosmetics to prevent skin aging. The final design was researched and developed through a graphic expression of pumpkin characteristics, a design process, and a survey on preference for differentiated packaging design. The survey targets women in their 20s and 30s who directly purchase cosmetics, and an analysis of consumers' preference for brand product decisions showed that simple and modern designs suitable for cosmetics images topped the list. In addition, it showed a positive image of cosmetics development using local agricultural products and high brand value. We present the possibility that domestic pumpkin raw materials can be applied to cosmetics and aim to develop excellent cosmetics brands through consumer preference surveys.

• International journal of advanced smart convergence
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• v.12 no.4
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• pp.464-469
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• 2023

The government has set the mechanization of paddy agriculture as a national task, aiming to achieve over 70% by 2025. The main objective is to stabilize the farming costs of rural households due to the aging and feminization of rural areas, as well as the shortage of agricultural labor. In response to this, the Korea Rural Economic Institute operates a farm machinery rental business. However, there are challenges in selecting and managing rental machinery, including issues related to labor, costs, verification, and time. Additionally, there is a limit to upgrades, and overseas models are being imported and used for transplanters and rice planters, which do not conform to domestic standards and face maintenance difficulties. In order to solve the difficulties of the agricultural machine rental business, we intend to develop an application that shares domestic and foreign machines purchased and used by individuals at a low cost and use them in gun-level administrative districts.