• Korean Chemical Engineering Research
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• v.44 no.3
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• pp.259-264
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• 2006

The separation and purification of $TaCl_5$is indispensable in the synthetic process of $TaCl_5$by chlorination of tantalum oxide. The reaction products are mainly $TaCl_5$, $NbCl_5$, $TiCl_4$ and $FeCl_2$. However, we need to separate $TaCl_5/NbCl_5$ mixture from the reaction product, because $TaCl_5$ and $NbCl_5$ are easily separated each other by distillation or hydrogen reduction process. In this work, a comparison study was carried out between direct sequence and indirect sequence to obtain $TaCl_5/NbCl_5$ mixture from the reaction product by removing light component, $TiCl_4$ and heavy component, $FeCl_2$ using two distillation columns. It was concluded that the direct sequence gave better results than indirect sequence in the aspect of initial capital costs and the associative operating costs.

• Journal of Power Electronics
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• v.19 no.5
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• pp.1142-1152
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• 2019

This paper presents a control method for reducing the current distortion in an indirect matrix converter (IMC) operating in boost mode under unbalanced input conditions. IMCs operating in boost mode are useful in distributed generation (DG) systems. They are connected with renewable energy systems (RESs) and the grid to transmit the power generated by the RES. However, under unbalanced voltage conditions of the RES, which is connected with the input stage of the IMC operating in boost mode, the input-output currents are distorted. In particular, the output current distortions cause a ripple of the power, which is transferred to the grid. This aggravates the reliability and stability of the DG system. Therefore, in this paper, a control method using positive/negative sequence voltages and currents is proposed for reducing the current distortion of both side in IMCs operating in boost mode. Simulation and experimental results have been presented to validate effectiveness of the proposed control method.

• Journal of the Korea Institute of Military Science and Technology
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• v.20 no.1
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• pp.25-32
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• 2017

Most of weapon systems use aided navigation system which integrates inertial navigation and aiding sensors to compensate the INS errors increasing with the passage of time. Various aid sensors can be applied such as Global Navigation Satellite System (GNSS), radar, barometer, etc., but there might exist time delay caused by signal processing or transferring aid information. This time delay leads out-of-sequence measurements (OOSM) systems. Previously, optimal and suboptimal measurment update method for OOSM systems, where the time delay length are known, are proposed. However, previous algorithm does not guarantee the positive definite property of covariance matrix. In order to improve numerical stability for aided navigation using delayed-measurement, this paper proposes a new measurement covariance update algorithm be similar to Joseph-form in Kalman filter. Futhermore, we propose how to implement it in indirect feedback Kalman filter structure, which is commonly used in aided navigation systems, for time-delayed measurement systems. Simulation and vehicle test results show effectiveness of a proposed algorithm.

• Korean Journal of Human Ecology
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• v.13 no.5
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• pp.659-672
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• 2004

This study examines different individual, family, and school environmental variables that affect victimization by peer aggression among adolescents. The sample consists of 868 seventh and eighth graders. Statistics and method for data analysis include Cronbach's alpha, percentage, means, standard deviation, Pearson correlation, multiple regression, and hierarchical regression. The major findings of this study are as follows: First, adolescents, both withdrawn and aggressive, have lower achievement in school work. Boys experience more direct victimization by peer aggression. Adolescents, especially boys, often experience indirect victimization by peer aggression, when they become withdrawn, own lower self-esteem, and have lower achievement in school work. Second, adolescents have more direct victimization by peer aggression when their parents are negligent of them. Also, adolescents seem exposed to indirect victimization by peer aggression when they receive more physical and emotional abuse and negligence from their parents. Third, adolescents experience more victimization by peer aggression-whether it's direct or indirect, when they cannot get adjusted to peer relations and get teachers' supervision. Fourth, as to direct victimization by peer aggression, withdrawal, one of the individual variables, is the most reliable prediction followed by gender, negligence, adaptability in peer relations, aggression, and teacher's supervision in sequence. For indirect victimization by peer aggression, withdrawal is the most reliable prediction followed by adaptability in peer relations, gender, physical and emotional abuse, and negligence in sequence.

• Journal of The Korean Astronomical Society
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• v.38 no.2
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• pp.319-324
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• 2005

To date, more than 150 exo-solar planets have been observed by various methods such as spectroscopic, photometric, astrometric, gravitational lensing, pulsar timing methods. However, all these are indirect methods; they do not directly image the planets. Only free-floating planets or their 'ana-log' have been directly detected so far. Thus the next milestone is the direct imaging of any kinds of planetary mass objects orbiting around normal (young) stars, which might have been associated with protoplanetary disks, the sites of planet formation. I will describe some SUBARU efforts to detect self-luminous young giant planets as companions as well as direct imaging of the protoplanetary disks of ${\~}$100 AU size. The results of near-infrared coronagraphic imaging with adaptive optics are briefly presented on AB Aur, HD 142527, T Tau, and DH Tau. Our results demonstrate the importance of high-resolution (${\~}$0.1 arcsec) direct imaging over indirect observations such as modeling based on spectral energy distributions. The SUBARU observations are a prelude to ALMA from the morphological point of view.

• English Language & Literature Teaching
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• v.11 no.4
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• pp.49-77
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• 2005

This paper has an aim to examine English native speakers' requests, and offer an instructional technique to develop EFL students' pragmatic ability. For this purpose, English-speaking native speakers' requests were collected in six different face-threatening situations, and analyzed in three ways: directness levels, internal modification and sequence of request. The analysis of requests showed that they were realized mainly through conventionally indirect level in most situations, were internally modified frequently through the use of downgraders, and had a certain sequence of utterances realizing a request. On the basis of these findings, two kinds of interactional activities (Jigsaw and pair work) were provided as sample activities to promote EFL students' pragmatic knowledge about the appropriate ways of making requests given the fact that pragmatic errors can be more serious and more problematic than grammatical errors in social interaction.

• Journal of Veterinary Science
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• v.22 no.4
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• pp.49.1-49.6
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• 2021

The S1 protein of the infectious bronchitis virus (IBV) is a major structural protein that induces the production of the virus-neutralization antibodies. The monoclonal antibody against the IBV M41 S1 protein was used as a target for biopanning. After three rounds of biopanning, randomly selected phages bound to the monoclonal antibody. Sequence analysis showed that the dominant sequence was SFYDFEMQGFFI. Indirect competitive enzyme-linked immunosorbent assay showed that SFYDFEMQGFFI is a mimotope of the S1 protein that was predicted by PepSurf. The mimotope may provide information for further structural and functional analyses of the S1 protein.

• BMB Reports
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• v.42 no.5
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• pp.271-276
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• 2009

Sweetpotato (Ipomoea batatas (L). Lam.) is relatively tolerant to unfavorable growth conditions such as drought, yet has not been exploited to provide a better understanding of the molecular basis of drought stress tolerance. We obtained 983 high-quality expressed sequence tags of 100 bp or longer (average length of 700 bp) from cDNA libraries of detached white fibrous root tissues by subjecting them to dehydration for 6 h. The 431 cDNAs were each assigned a function by alignment using the BLASTX algorithm. Among them, three genes associated with various abiotic stresses and nine genes not previously associated with drought stress were selected for expression pattern analysis through detailed reverse transcription-polymerase chain reaction. The direct and indirect relationships of the 12 genes with drought tolerance mechanisms were ascertained at different developmental stages and under various stress conditions.

• Magazine of the Korea Concrete Institute
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• v.11 no.1
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• pp.119-127
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• 1999

The objective of this study is to simulate the fracture behavior of composite structure bonded with more than 2 different cementitious materials. For this, concrete and cement were stacked and bonded in a direction perpendicular to loading and specimens were tested. Each constituent material of concrete and cement was fabricated independently also, and three point bending and indirect tensile tests were carried out for the acquisition of measured values applicable to the proposed model. As a result of comparing theoretical results and experimental ones, it was found that the proposed model derived from fictitious crack theory can be used to predict the fracture behavior of composite structures on the vases of well agreement with experimental results. It was also noted that the degree of improvement of fracture energies and strengths is greatly dependent on the stacking sequence of layers composing of a composite structure. Thus, it can be concluded that brittleness or ductility of a composite structure can be accomplished by a proper arrangement of layers on one's purpose throughout the proposed analysis.

• Korean Journal of Microbiology
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• v.38 no.3
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• pp.173-179
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• 2002

The functions of riboflavin synthesis genes ( ribI,II,III and IV) found immediately downstream of luxG in the lux operon from Photobacterium species were identified using the biochemical and genetical analysis. The ribI-III gene codes for protein corresponding to that coded by the second (riboflavin synthase), third (3,4-dihydroxy 2-butanone 4-phosphate synthase/GTP cyclohydrolase II) and fourth (lumazine synthase) gene, respectively, of Bacillus subtilis rib operon with the respective gene procuct sharing 41-50% amino acid sequence identity. Unexpectedly, the sequence of the ribIV product of Photobacterium phosphoreum does not correspond in sequence to the protein encoded by the fifth rib gene of Bacillus subtilis. Instead the gene (ribIV) codes for a polypeptide similar in sequence to GTP cyclohydrolase II of Escherichia coli and the carboxy terminal domain of the third rib gene from Bacillus subtilis. Complementation of Escherichia coli riboflavin auxotrophs showed that the function of the gene products of ribII and ribIV are DHBP synthase and GTP cyclohydrolase II, respectively. In addition the experiment, showing that increase in thermal stability of riboflavin synthase coded by ribIon coexpression with ribIII, provided indirect evidence that the latter gene codes for lumazine synthase.