• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.382-385
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• 2003

In this paper, the solenoid for high-voltage circuit breaker which is composed of bobbin, solenoid coil, stationary core and plunger was studied. The solenoid is made of a soft magnetic iron bar with a large number of coil windings. when an electric current passes through this, this stationary core becomes the strong magnet used for hydraulic and pneumatic valve of a solenoid operated valve. For the performance evaluation of the solenoid for high-voltage circuit breaker, electromagnetic characteristics and dynamic characteristics were analyzed. And, the parameters which is related to performance improvement were investigated.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2011년도 춘계학술대회 논문집
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• pp.513-514
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• 2011

• Wind and Structures
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• 제39권2호
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• pp.125-140
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• 2024

The simulation of non-stationary wind velocity is particularly crucial for the wind resistant design of slender structures. Recently, some data-driven simulation methods have received much attention due to their straightforwardness. However, as the number of simulation points increases, it will face efficiency issues. Under such a background, in this paper, a time-varying coherence matrix decomposition method based on Diagonal Proper Orthogonal Decomposition (DPOD) interpolation is proposed for the data-driven simulation of non-stationary wind velocity based on S-transform (ST). Its core idea is to use coherence matrix decomposition instead of the decomposition of the measured time-frequency power spectrum matrix based on ST. The decomposition result of the time-varying coherence matrix is relatively smooth, so DPOD interpolation can be introduced to accelerate its decomposition, and the DPOD interpolation technology is extended to the simulation based on measured wind velocity. The numerical experiment has shown that the reconstruction results of coherence matrix interpolation are consistent with the target values, and the interpolation calculation efficiency is higher than that of the coherence matrix time-frequency interpolation method and the coherence matrix POD interpolation method. Compared to existing data-driven simulation methods, it addresses the efficiency issue in simulations where the number of Cholesky decompositions increases with the increase of simulation points, significantly enhancing the efficiency of simulating multivariate non-stationary wind velocities. Meanwhile, the simulation data preserved the time-frequency characteristics of the measured wind velocity well.

• Journal of Magnetics
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• 제16권3호
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• pp.281-287
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• 2011

The stationary discontinuous armatures that are used in permanent magnet linear synchronous motors (PM-LSMs) have been proposed as a driving source for transportation systems. However, the stationary discontinuous armature PM-LSM contains the outlet edges which always exist as a result of the discontinuous arrangement of the armature. For this reason, the high alteration of the outlet edge cogging force produced between the armature's core and the mover's permanent magnet when a mover passes the boundary between the armature's installation part and non-installation part has been indicated as a problem. Therefore, we have examined the outlet edge cogging force by installing the auxiliary teeth at the armature's outlet edge in order to minimize the outlet edge cogging force generated when the armature is arranged discontinuously. Moreover, we obtained the calculation by analyzing the shape of the auxiliary teeth in which the outlet edge cogging force is minimized the most.

• 한국전자통신학회논문지
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• 제5권6호
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• pp.613-619
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• 2010

최근 반송장치 시스템의 구동원으로 전기자 분산배치를 이용한 영구자석 리니어 동기 모터가 사용되고 있다. 하지만, 전기자 분산배치를 이용한 영구자석 리니어 동기 모터는 구조상 필연적으로 단부가 존재하게 된다. 이러한 이유로 전기자의 철심과 가동자의 영구자석 사이에 단부 코깅력이 발생한다. 본 논문은 유한요소법을 이용한 2차원 수치해석을 통해 단부 코깅력을 고찰하였다. 또한, 단부 코깅력을 최소화하기 위해 가동자에 보조극을 설치한 형상을 제안하였다.

• FOCUS: LIFE SCIENCE
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• 제1호
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• pp.3.1-3.7
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• 2024

The article discusses the critical role of chromatography in the analysis and purification of proteins in biopharmaceuticals, emphasizing the importance of comprehensive characterization for ensuring their safety and efficacy. It highlights the use of Avantor® ACE® HPLC columns for the separation and purification of proteins, focusing on the analysis of intact proteins using reversed-phase liquid chromatography (RPLC) with fully porous particles. This article also details the application of different mobile phase additives, such as TFA and formic acid, and emphasizes the advantages of using type B ultra-pure silica-based columns for efficiency and peak shape in biomolecule analysis. Additionally, it addresses the challenges of analyzing intact proteins due to slow molecular diffusion and introduces the concept of solid-core (or superficially porous) particles, emphasizing their benefits over traditional porous particles for the analysis of therapeutic proteins. Furthermore, it discusses the development of Avantor® ACE® UltraCore BIO columns, specifically designed for the high-efficiency separation of large biomolecules, such as proteins, and demonstrates their effectiveness in achieving high-resolution separations, even for higher molecular weight proteins like monoclonal antibodies (mAbs). In addition, it underscores the complexity of analyzing and characterizing intact protein biopharmaceuticals, requiring a range of analytical techniques and the use of wide-pore stationary phases, operated at elevated temperatures and with relatively shallow gradients. It highlights the comprehensive range of options offered by Avantor® ACE® wide pore columns, including both fully porous and solid-core particles, bonded with a variety of complementary stationary phase chemistries to optimize selectivity during method development. The use of ultrapure and highly inert base silica is emphasized for enabling the use of lower concentrations of mobile phase modifiers without compromising analyte peak shape, particularly beneficial for LC-MS applications. Then the article concludes by emphasizing the significance of reversed-phase liquid chromatography and its compatibility with mass spectrometry as a valuable tool for the separation and analysis of intact proteins and their closely related variants in biopharmaceuticals.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2009년도 춘계학술대회 논문집
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• pp.659-660
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• 2009

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2007년도 춘계학술대회 논문집
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• pp.15-16
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• 2007

• 한국자동차공학회논문집
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• 제1권3호
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• pp.34-45
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• 1993

This study aims to analyze the mixing characteristics of hydrogen considered as a new fuel for internal combustion engines. As the physical property of helium gas is similar to that of hydrogen, helium gas was used in this study. To analyze the steady and unsteady behavior of jet, helium gas was injected into the stationary atmosphere at the normal temperature and pressure. Concentration of helium gas in the center of jet flow is in inverse proportion with axial distance from the nozzle tip. This agrees with the free jet theory of Schlichting. The relative equation for dimensionless concentration to radial/axial distance the axial distance of potential core region, the cone angle a of the jet flow and the relative equation for arriving distance of the front of jet flow to the lapse of time are obtained. But free jet theory of Schlichting in the dimensionless concentration is not in agreement with the present experimental results of the distance of the radial direction. It needs more study. When the arrival frequency of jet flow is used as a parameter, the transition area changing from unsteady flow area into steady flow area becomes gradually wider downstream, but its ratio for the whole unsteady flow area gradually decreases.

• Bulletin of the Korean Chemical Society
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• 제35권12호
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• pp.3465-3474
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• 2014

Porous silica particles are the most prevailing raw material for stationary phases of liquid chromatography. During a long period of time, various methodologies for production of porous silica particles have been proposed, such as crashing and sieving of xerogel, traditional dry or wet process preparation of conventional spherical particles, preparation of hierarchical mesoporous particles by template-mediated pore formation, repeated formation of a thin layer of porous silica upon nonporous silica core (core-shell particles), and formation of specific silica monolith followed by grinding and calcination. Recent developments and applications of useful porous silica particles will be covered in this review. Discussion on sub-$3{\mu}m$ silica particles including nonporous silica particles, carbon or metal oxide clad silica particles, and molecularly imprinted silica particles, will also be included. Next, the individual preparation methods and their feasibilities will be collectively and critically compared and evaluated, being followed by conclusive remarks and future perspectives.