• Steel and Composite Structures
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• 제42권3호
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• pp.397-405
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• 2022

The existing researches on the dynamics of the fluid-conveying pipes only focus on stability and vibration problems, and there is no literature report on the wave propagation of the fluid-conveying pipes. Therefore, the purpose of this paper is to explore the propagation characteristics of longitudinal and flexural waves in the fluid-conveying pipes. First, it is assumed that the material properties of the fluid-conveying pipes vary based on a power function of the thickness. In addition, it is assumed that the material properties of both the fluid and the pipes are closely depended on temperature. Using the Euler-Bernoulli beam equation and based on the linear theory, the motion equations considering the thermal-mechanical-fluid coupling is derived. Then, the exact expressions of phase velocity and group velocity of longitudinal waves and bending waves in the fluid-conveying pipes are obtained by using the eigenvalue method. In addition, we also studied the free vibration frequency characteristics of the fluid-conveying pipes. In the numerical analysis, we successively studied the influence of temperature, functional gradient index and liquid velocity on the wave propagation and vibration problems. It is found that the temperature and functional gradient exponent decrease the phase and group velocities, on the contrary, the liquid flow velocity increases the phase and group velocities. However, for vibration problems, temperature, functional gradient exponent parameter, and fluid velocity all reduce the natural frequency.

• 식물병연구
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• 제18권2호
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• pp.109-116
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• 2012

전라남도 영남지역의 감나무 줄기로부터 다양한 식물병에 대해 방제 효과를 보이는 세균을 분리하였다. 분리균주는 16S rRNA sequencing의 방법을 이용하여 동정한 결과 B. subtilis로 동정되었으며, B. subtilis GDYA-1로 명명하였다. In vivo 생물검정에서 GDYA-1 액체 배양액은 벼 도열병, 토마토 역병 및 밀 붉은녹병에 항균 활성을 보였다. 액체 배양액으로부터 한 개의 항균물질을 분리하였으며, 질량분석과 핵자기공명분석을 통해 분리한 물질은 benzoic acid로 동정되었다. Benzoic acid는 M. oryzae, R. solani, S. sclerotiorum 및 P. capsici의 균사생육을 62.5-125 ${\mu}g/ml$에서 완전히 억제하였다. 또한 benzoic acid는 고추 역병을 효과적으로 방제하는 것으로 나타났다. 본 연구에서 benzoic acid의 식물병원성곰팡이에 대한 항균활성을 처음으로 보고하는 바이다. Benzoic acid와 B. subtilis GDYA-1는 식물병원성곰팡이로부터 작물을 친환경적으로 보호하는데 기여할 것으로 기대된다.

• Journal of Advanced Marine Engineering and Technology
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• 제28권6호
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• pp.906-915
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• 2004

In this paper, we address the development of magnetic levitation positioning system. This planar magnetic levitator employs four permanent magnet liner motors. Each motor generates vertical force for suspension against gravity, as well as horizontal force for driving levitation object called a platen. This stage can generate six degrees of freedom motion by the vertical and horizontal force. We derived the mechanical dynamics equation using Lagrangian method and used coenergy to express an electromagnetic force. We proposed a control algorithm for the position and posture control from its initial value to its desired value using sliding mode control. Some simulation results are provided to verify the effectiveness of the proposed control scheme.

• Wind and Structures
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• 제11권4호
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• pp.291-302
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• 2008

Three-dimensional engineering simulations of momentum-driven tornado-like vortices are conducted to investigate the flow dynamics dependency on swirl ratio and the possible relation with real tornado Fujita scales. Numerical results are benchmarked against the laboratory experimental results of Baker (1981) for a fixed swirl ratio: S = 0.28. The simulations are then extended for higher swirl ratios up to S = 2 and the variation of the velocity and pressure flow fields are observed. The flow evolves from the formation of a laminar vortex at low swirl ratio to turbulent vortex breakdown, followed by the vortex touch down at higher swirls. The high swirl ratios results are further matched with full scale data from the Spencer, South Dakota F4 tornado of May 30, 1998 (Sarkar, et al. 2005) and approximate velocity and length scales are determined.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 B
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• pp.755-756
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• 2006

This paper presents the temperature distribution of the oil-immersed self-cooled transformer with radiator performed by coupled magneto-fluid-thermal analysis. Particularly, 3D temperature distribution of cooling oil and sub-components under the natural convection is obtained by computational fluid dynamics analysis, while heat sources are predetermined by magnetic field analysis using F.E.M. The predicted temperature distribution of the power transformer model is compared with the measured data for verifying the validity of the proposed analysis.

• Bulletin of the Korean Chemical Society
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• 제30권10호
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• pp.2449-2452
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• 2009

• 한국생물물리학회:학술대회논문집
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• 한국생물물리학회 1996년도 정기총회 및 학술발표회
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• pp.29-29
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• 1996

The structure of an antimicrobial peptide buforin II has been studied by $^1$H NMR and CD spectroscopy. Buforin II is flexible and random structure in H$_2$O but the parts of buforin II become helical structure in trifluoroethanol (TFE)/H$_2$O (1:1, v/v) solution. From the restrained molecular dynamics calculation using NMR data, we obtained the possible conformation of buforin II in TFE/H$_2$O solution. (omitted)

• 한국농공학회지
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• 제42권2호
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• pp.71-77
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• 2000

A multi-region model for solute transport through saturated soils has been developed to describe preferential flow. The model consists of numerous discrete pore groups, which are characterized by a discrete dispersion coefficient, flow velocity, and porosity . The hydraulic properties for each pore group are derived from a soil's hydraluic conductivity and soil water characteristic functions . Flow in pore group is described by the classical advection-disersion equation (ADE). An implict finite difference scheme was applied to the governing equation that results in a block-tridiagonal system of equations that is very efficient and allows the soil to be divided into any number of pore groups. The numerical technique is derived from methods used to solve coupled equations in fluid dynamics problems and can also be applied to the transport of interacting solutes. The results of the model are compared to the experimental data from published papers. This paper contributes on the characteristics of the method when applied to the parallel porosity model to describe preferential flow of solutes in soil.

• Bulletin of the Korean Chemical Society
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• 제19권12호
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• pp.1326-1333
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• 1998

The study of coupled relaxation for methyl spin system in 2,6-dichlorotoluene was performed on the basis of the magnetization mode formalism. Using five initial perturbing pulse sequences, eight experimntal data sets were obtained, which were fitted with theoretical expressions with nine spectral density parameters. The same experiment was carried out at both 50.3 MHz and 125.6 MHz in carbon frequency. The measured spectral densities at both fields are similar in the exception of that related with carbon random field term. Furthermore, from the dipolar spectral density, the physical values may be extracted depending on the model of molecular reorientation. For example, it was assumed that the molecular framework undergoes asymmetric diffusive rotational process and methyl group reorients by either diffusive rotation about its symmetry axis or jump among internal rotational potential minima.

• Asia Marketing Journal
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• 제22권4호
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• pp.117-149
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• 2021

Over seven years, BTS have organically embedded consistent mental health messaging and modelling of various mental health modalities, representing innovation within mental health discourse, within and outside the pop and K-pop culture and fandom. Their personal and artistic journeys have resulted in songs, imagery, and relationship dynamics within the group and within and between their fans ARMY, that organically model behaviours associated with mental health therapeutic modalities and normalize the discussion of mental health and well-being. This practice is vitally important in the effort to end stigma and encourage mental health well-being and recovery. BTS's authenticity establishes empathy with their audience ARMY and increases their ability to deliver these messages effectively. This includes fostering the creation of a peer support community within the group that extends to their fanbase ARMY, and from which fan-created mental health programs have emerged. BTS's innovation will be explored by examining content creation throughout their career, illustrating their consistent and organic messaging, culminating in overt and conscious mental health content in their latest album BE, which was released three weeks after the initial paper was presented, and provides proof of concept.