• Structural Engineering and Mechanics
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• 제65권5호
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• pp.513-521
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• 2018

In this paper, the resonance response of spar-type floating platform in coupled heave and pitch motion is investigated using a CPU time-effective numerical method. A coupled nonlinear 2-DOF equation of motion is derived based on the potential wave theory and the rigid-body hydrodynamics. The transient responses are solved by the fourth-order Runge-Kutta (RK4) method and transformed to the frequency responses by the digital Fourier transform (DFT), and the first-order approximation of heave response is analytically derived. Through the numerical experiments, the theoretical derivation and the numerical formulation are verified from the comparison with the commercial software AQWA. And, the frequencies of resonance arising from the nonlinear coupling between heave and pitch motions are investigated and justified from the comparison with the analytically derived first-order approximation of heave response.

• Wind and Structures
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• 제23권5호
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• pp.421-447
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• 2016

Wind-induced and earthquake-induced excitations on tall structures can be effectively controlled by Tuned Liquid Damper (TLD). This work presents a numerical simulation procedure to study the performance of tuned liquid tank- structure system through ${\sigma}$-transformation based fluid-structure coupled solver. For this, a 'C' based computational code is developed. Structural equations are coupled with fluid equations in order to achieve the transfer of sloshing forces to structure for damping. Structural equations are solved by fourth order Runge-Kutta method while fluid equations are solved using finite difference based sigma transformed algorithm. Code is validated with previously published results. The minimum displacement of structure is observed when the resonance condition of the coupled system is satisfied through proper tuning of TLD. Since real-time excitations are random in nature, the performance study of TLD under random excitation is also carried out in which the Bretschneider spectrum is used to generate the random input wave.

• ETRI Journal
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• 제29권4호
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• pp.533-535
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• 2007

For the purpose of decreasing intermodulation distortion, a new multi-harmonic suppression band-pass filter based on a microstrip radial stub is studied. Compared with traditional resonator filters, the new filter can suppress the second, third, and even fourth harmonics directly. The dimension of the filter is about $0.3\;{\lambda}_{g^0}{\times}0.13\;{\lambda}_{g^0}$ (${\lambda}_{g^0}$ is the guiding wavelength at the resonant frequency). Only one gap was introduced, so lower insertion loss can be obtained. Basic agreement between the measured and simulated results has been achieved.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2007년도 추계학술대회
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• pp.181-191
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• 2007

Logistics creates a boom in accordance with the recent new technique's development along with the recent RFID/USN of ubiquitous computing technique. The wave of 4PL(Fourth Party Logistics) that added the strategic consulting based on new IT techniques to logistics outsourcing through existing 3PL service with is a great issue. Moreover, the customer enterprises which contained manufacturers and distributors need the one stop service, therefore a method for effectively dealing with global logistics' environment changes is needed. Above all, a development of the 4PL system with RFID is very urgent. We developed the RFID u-4PL system progressed more than the present system, in which we applied many international standards. Finally, we constructed the web service based on Web 2.0 because of important condition of 4PL.

• 아동학회지
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• 제35권5호
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• pp.135-154
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• 2014

This study examined the causal relationships between parenting stress and self-efficacy of Korean mothers with an infant according to employment status using the second through fourth wave data of the Panel Study of Korean Children (PSKC). Autoregressive cross-lagged modeling was performed to test the longitudinal reciprocal relationships between the two constructs. Our results indicated that both maternal parenting stress and self-efficacy were consistent over time. The results also indicated that there was a significant cross-lagged effect of maternal parenting stress on their self-efficacy, rather than vice versa. No differences between working and non-working mothers were found in the relationship between the two constructs.

• Journal of Multimedia Information System
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• 제4권2호
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• pp.83-88
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• 2017

The era of the fourth industrial revolution, which will bring about a great wave of change in the 21st century, is the age of super-connection that links humans to humans, objects to objects, and humans to objects. In the smart city and the smart space which are evolving further, emotional engineering is a field of interdisciplinary researches that still attract attention with the development of technology. This paper proposes an emotional object prototype as a possibility of emotional interaction in the relation between human and object. By suggesting emotional objects that produce color changes and movements through the emotional interactions between humans and objects against the current social issue-loneliness of modern people, we have approached the influence of our lives in the relation with objects. It is expected that emotional objects that are approached from the fundamental view will be able to be in our lives as a viable cultural intermediary in our future living space.

• 전자통신동향분석
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• 제32권6호
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• pp.66-72
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• 2017

The frequency range of a radio wave is from 3kHz to 300GHz, and radio technologies use this range to improve the quality of human lives. Radio technologies have entered a new phase of communication. The core infrastructure used as the basis for technologies leading the fourth industrial evolution, such as artificial intelligence, the Internet of Things, autonomous cars/drones, augmented reality, robots, and remote medical diagnoses, is the 5G network. The 5G network enables transmitting and receiving large amounts of data at very high speed. In particular, application technologies with artificial intelligence have been studied, including radar, wireless charging, electromagnetic devices and their effects on humans, EMI/EMC, and microwave imaging. In this study, we present a future radio technology that is needed to prepare for the upcoming industrial revolution and digital transformation.

• ETRI Journal
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• 제29권5호
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• pp.673-675
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• 2007

We present the design and fabrication of a 60 GHz medium power amplifier monolithic microwave integrated circuit with excellent gain-flatness for a 60 GHz radio-over-fiber system. The circuit has a 4-stage structure using microstrip coupled lines instead of metal-insulator-metal capacitors for unconditional stability of the amplifier and yield enhancement. The gains of each stage of the amplifier are modified to provide broadband characteristics of input/output matching for the first and fourth stages and to achieve higher gains for the second and third stages to improve the gain-flatness of the amplifier for wideband.

• 한국컴퓨터정보학회논문지
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• 제23권11호
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• pp.211-218
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• 2018

The purpose of the present study was to test the impact of depression on mobile phone dependency among elementary school students, to test the mediating effect of self-esteem between depression and mobile phone dependency, and to draw out theoretical and practical implications in terms of preventing or reducing mobile phone dependency. Based on previous studies, a longitudinal research model between the aforementioned three variables has been identified. The present study analyzed the 4th, 5th, and 6th wave data from Korea Children and Youth Panel Study 2010 (KCYPS 2010). The major results were as follows. First, depression could have a significant negative effect on self-esteem. Second, self-esteem could have a significant negative effect on mobile phone dependency. Third, the influence of depression on mobile phone dependency was not significant. Fourth, gender could be a significant moderating variable between depression and self-esteem. Finally, a number of implications of these findings were also discussed.

• 한국사회복지학
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• 제69권1호
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• pp.59-77
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• 2017

본 연구는 종단적 시각에서 손자녀 돌봄 유형과 중 고령층 여성의 건강과의 관계를 살펴봄으로써, 한국 여성노인의 노후생활에 대한 이해를 제고하는데 그 의미가 있다. 이를 위해 국민노후보장패널 2차년도 자료부터 5차년도 자료를 사용하여 손자녀 돌봄 유형을 돌봄지속, 돌봄전이, 돌봄중단, 미돌봄으로 구분하고 이 유형들이 50대 이상 중 고령층 여성의 신체건강 및 정신건강에 미치는 영향을 알아보고자 하였다. 연구결과, 인구사회학적 요인을 통제한 상태에서 손자녀를 돌보지 않는 여성에 비해 손자녀를 돌보다가 중단한 여성일수록 좋은 신체건강 수준을 보였다. 하지만 손자녀 돌봄 경험은 여성의 정신건강에 유의미한 영향을 보이지 않았다. 이를 통해, 손자녀 돌봄 유형이 중 고령층에 있는 여성의 신체건강과 정신건강에 미치는 영향은 다를 수 있음을 확인하였다. 본 연구의 결과를 바탕으로, 손자녀 돌봄을 제공하는 여성노인의 건강한 노후생활을 위한 후속 연구의 필요성 및 제고방안을 논의하였다.