• Journal of Mechanical Science and Technology
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• 제19권5호
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• pp.1087-1094
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• 2005

This paper presents the validity and limitation of the thin-shell approach for the analysis of elastic wave propagation in a pipe with nonviscous liquid. The phase velocities calculated by the thin-shell approach were compared with those calculated by the thick-cylinder approach. In contrast to the case of the empty pipe, where only two modes were obtained and the first mode was calculated in a limited frequency range, the results for the liquid-filled pipe exhibits a large number of modes due to the large number of branches of the apparent liquid mass. Several of the lowest modes of the waves in a liquid-filled pipe were calculated for various pipe thicknesses in a low frequency range. The thin-shell approach was valid for a reasonable range of pipe thicknesses.

• Journal of Ship and Ocean Technology
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• 제8권1호
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• pp.10-30
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• 2004

High-fidelity RANS simulations are presented for a ducted marine propulsor, including verification ＆ validation (V＆V) using available experimental fluid dynamics (EFD) data. CFDSHIP-IOWA is used with $\textsc{k}-\omega$ turbulence model and extensions for relative rotating coordinate system and Chimera overset grids. The mesh interpolation code PEGASUS is used for the exchange of the flow information between the overset grids. Intervals V＆V for thrust, torque, and profile averaged radial velocity just downstream of rotor tip are reasonable in comparison with previous results. Flow pattern displays interaction and merging of tip-leakage and trailing edge vortices. In interaction region, multiple peaks and vorticity are smaller, whereas in merging region, better agreement with EFD. Tip-leakage vortex core position, size, circulation, and cavitation patterns for $\sigma=5$ also show a good agreement with EFD, although vortex core size is larger and circulation in interaction region is smaller.

• Journal of the Optical Society of Korea
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• 제3권2호
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• pp.64-68
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• 1999

The performance of a fiber Bragg grating strain sensor constructed with 3$\times$3 coupler is investigated. A 3$\times$3 coupler Mach-Zehnder (M/Z) interferometer is used as wavelength discriminator, interrogating strain-induced Bragg wavelength shifts. Two quadrature-phase-shifted intensities are synthesized from the as-coupled interferometer outputs, and digital arctangent demodulation and phase unwrapping algorithm are applied to extract the phase information proportional to strain. Due to the linear relation between the input strain and the output of quadrature signal processing, signal-fading problems eliminated. In the experiment, a fiber grating that was surface adhered on an aluminum beam was strained in different ways, and the photodetector signals were transferred and processed in a computer-controlled processing unit. A phase recovery fo 7.8$\pi$ pk-pk excursion, which corresponds to ~650$\mu$strain pk-pk of applied strain, was demonstrated. The sensor system was stable over the environmental intensi쇼 perturbations because of the self-referencing effect in the demodulation process.

• 한국수소및신에너지학회논문집
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• 제16권4호
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• pp.324-333
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• 2005

The kinetics of external hydrogen embrittlememt is considered. The equation of the crack growth rate (CGR) is derived from modification of the model developed by Wilkinson and Vitek. After calculation of hydrogen pressure build-up in the void, the effect of the internal hydrogen pressure on the void growth is added. The CGR is expressed by two terms. One is the term dependent on the critical stress, which is exactly same as Wilkinson and Vitek. The other is term dependent on the pressure of the hydrogen in void.

• 산업경영시스템학회지
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• 제33권2호
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• pp.148-153
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• 2010

Nowadays, customers have increasing needs, so more and more enterprises are selling their products with additional services and or contents. The emergence of service added to the product leads to the emergence of the Product-Service Systems(PSS). Many researches related to PSS are mainly concerned with general PSS and PSS modeling, which can not readily assist manufactures of consumer products to implement and realize PSS solution. We have wondered whether customers can distinguish service functions from product functions. Through the case studies on Apple and Nintendo and the survey on the representative 5 IT products, we propose the design factors of products and services for PSS.

• 전자통신동향분석
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• 제36권2호
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• pp.1-11
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• 2021

As sensors such as Inertial Measurement Unit, cameras, and Light Detection and Rangings have become cheaper and smaller, research has been actively conducted to implement functions automating micro aerial vehicles such as multirotor type drones. This would fully enable the autonomous flight of drones in the real world without human intervention. In this article, we present a survey of state-of-the-art development on autonomous drones. To build an autonomous drone, the essential components can be classified into pose estimation, environmental perception, and obstacle-free trajectory generation. To describe the trend, we selected three leading research groups-University of Pennsylvania, ETH Zurich, and Carnegie Mellon University-which have demonstrated impressive experiment results on automating drones using their estimation, perception, and trajectory generation techniques. For each group, we summarize the core of their algorithm and describe how they implemented those in such small-sized drones. Finally, we present our up to date research status on developing an autonomous drone.

• Asia Marketing Journal
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• 제22권1호
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• pp.27-39
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• 2020

Building on the growing literature on how physical bodily expressions influence psychological processes, the authors propose that exerting physical strength decreases risk perceptions and increases preference for risky options by increasing perceptions of control or agency. The present research is based on the belief of "no pain, no gain", that when an individual exerts physical strength and effort, he believes he can be the agent in bringing about the desired outcome. Because of this automatic association between exerting physical strength and the sense of being in control of the outcome, the authors hypothesize that even in situations where the outcome is determined by chance and luck, individuals exerting effort feel they have more control and thus choose riskier, but more desirable, options. Furthermore, this research clarifies the distinction between physical exertion of strength, high- and low-power poses, and psychological power.

• 대한인간공학회지
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• 제14권1호
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• pp.69-81
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• 1995

Few studies on the biomechanical analysis of hand postures and tool handling tasks exist because of the lack of appropriate measurement techniques for hand force. A measurement system for the finger forces and joint angles for the analysis of manual tool handling tasks was developed in this study. The measurement system consists of a force sensing glove made from twelve Force Sensitive Resistors and an angle-measuring glove (Cyberglove$^{TM}$, Virtual technologies) with eighteem joint angle sensors. A biomechanical model of the hand using the data from the measurement system was also developed. Systems of computerized procedures were implemented inte- grating the hand posture measurement system, biomechanical analysis system, and the task analysis system for manual tool handling tasks. The measurement system was useful in providing the hand force data needed for an existing task analysis system used in CTD risk evaluation. It is expected that the hand posture measurement developed in this study will provide an efficient and cost-effective solution to task analysis of manual tool handling tasks.s.

• Journal of Microbiology
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• 제44권5호
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• pp.548-555
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• 2006

FaeG is the key factor in the infection process of K88ad enterotoxigenic Escherichia coli (ETEC) fimbrial adhesin. In an attempt to determine the possibility of expressing recombinant FaeG with immunogenicity for a new safe and high-production vaccine in E. coli, we constructed the recombinant strain, BL21 (DE3+K88), which harbors an expression vector with a DNA fragment of faeG, without a signal peptide. Results of 15% SDS-polyacrylamide slab gel analysis showed that FaeG can be stably over-expressed in BL21 (DE3+K88) as inclusion bodies without FaeE. Immunoglobulin G (IgG) and M (IgM) responses in pregnant pigs, with boost injections of the purified recombinant FaeG, were detected 4 weeks later in the sera and colostrum. An in vitro villius-adhesion assay verified that the elicited antibodies in the sera of vaccinated pigs were capable of preventing the adhesion of K88ad ETEC to porcine intestinal receptors. The protective effect on the mortality rates of suckling piglets born to vaccinated mothers was also observed one week after oral challenge with the virulent ETEC strain, $C_{83907}$ (K88ad, $CT^+,\;ST^+$). The results of this study proved that the adhesin of proteinaceous bacterial fimbriae or pili could be overexpressed in engineered E. coli strains, with protective immune responses to the pathogen.

• 대한지리학회지
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• 제37권5호
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• pp.536-550
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• 2002

이 연구는 7년 동안의 수문, 기후, 수질자료를 이용하여 펜실바니아 38개 유역 수질의 공간적 변이 패턴을 고찰하였다. 연구기간동안 도시적, 농업적 토지이용이 많은 유역에서 농도의 변이가 심하게 나타났다. 질소의 농도는 농업적 토지이용과. 인의 농도는 도시적 토지이용과 상관관계가 높게 나타났다. 주성분분석을 통해 이들의 농도 변이를 설명하는 주요 성분 셋이 - 토지 지형관련, 기후관련, 규모 - 도출되었다. 부분 여분 분석을 통해 기후, 토지, 지형의 복합적인 영향이 질소 농도 변이의 28.1%를 설명하고 있으며, 순수한 토지 변수의 영향이 인 농도의 41.8 o/o를 설명하고 있음을 알 수 있었다. 주 전체적인 차원에서 농도변이의 뚜렷한 지리적 패턴-북서부지역의 낮은 농도와 남동부지역의 높은 농도-이 나타나고 있으며, 이는 지역적 규모에서 수문, 기후, 토지이용, 지형 등 여러 가지 환경변수의 복합적인 상호관련성을 반영하고 있다.