• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2006.09a
• /
• pp.287-288
• /
• 2006

Two approaches for the fabrication of tailored powder composites with specially distributed pore-grain structure and chemical composition are investigated. Electrophoretic Deposition (EPD) followed by microwave sintering is employed to obtain functionally graded materials (FGM) by in-situ controlling the deposition bath suspension composition. $Al_2O_3/ZrO_2$ and zeolite FGM are successfully synthesized using this technique. In order to fabricate an aligned porous structure, unidirectional freezing followed by freeze drying and sintering is employed. By controlling the temperature gradient during freezing of powder slurry, a unidirectional ice-ceramic structure is obtained. The frozen specimen is then subjected to freeze drying to sublimate the ice. The obtained capillary-porous ceramic specimen is consolidated by sintering. The sintering of the graded structure is modeled by the continuum theory of sintering.

• Journal of Microbiology and Biotechnology
• /
• v.22 no.10
• /
• pp.1336-1342
• /
• 2012

In Burkholderia pseudomallei, the pathogen that causes melioidosis, the gene cluster encoding the capsular polysaccharide, is located on chromosome 1. Among the 19 capsular genes in this cluster, wzm has not been thoroughly studied. To study the function of wzm, we generated a deletion mutant and compared it with the wild-type strain. The mutant produced less biofilm in minimal media and was more sensitive to desiccation and oxidative stress compared with the wild-type strain, indicating that wzm is involved in biofilm formation and membrane integrity. Scanning electron microscopy showed that the bacterial cells of the mutant strain have more defined surfaces with indentations, whereas cells of the wild-type strain do not.

• Journal of Microbiology
• /
• v.41 no.1
• /
• pp.41-45
• /
• 2003

N crassa mutant strain nap showed reduced growth rate, decreased electric membrane potential, and elevated intracellular ATP content in comparison to the wild type. Blue light induced a hyperpolarization of the membrane potential in both strains. The analysis of oxidative and phosphorylation activities of mitochondria isolated from the two strains has revealed that nap utilized more efficient oxidative pathways. The higher intracellular ATP content in the nap was presumably due to impaired transport systems of the plasma membrane, and to a lesser extent to the functioning of the fully competent respiratory chain. The excess ATP possibly accounts for carotenoid accumulation in the mutant.

• Mass Spectrometry Letters
• /
• v.9 no.1
• /
• pp.17-23
• /
• 2018

Studies on the interactions of amyloidogenic proteins with trace metals, such as copper, have indicated that the metal ions perform a critical function in the early oligomerization process. Herein, we investigate the effects of Cu(II) ions on the active sequence regions of amyloidogenic proteins using electrospray ionization mass spectrometry (ESI-MS) and collision induced dissociation tandem MS (CID-MS/MS). We chose three amyloidogenic peptides NNQQNY, LYQLEN, and VQIVYK from yeast prion like protein Sup35, insulin chain A, and tau protein, respectively. [Cu-peptide] complexes for all three peptides were observed in the mass spectra. The mass spectra also show that increasing Cu(II) concentrations decrease the population of existing peptide oligomers. The tandem mass spectrum of NNQQNY shows preferential binding for the N-terminal region. All three peptides are likely to appear to be in a Cu-monomer-monomer (Cu-M-M) structure instead of a monomer-Cu-monomer (M-Cu-M) structure.

• The Journal of Natural Sciences
• /
• v.12 no.1
• /
• pp.61-67
• /
• 2002

The results of laboratory experiments with microcosms containing Daphnia magna and Chlorella vulgaris demonstrated decrease of the structural exergy of artificial communities after the addition of model toxicants phenol and cobalt chloride. Structural exergy changes were more expressed than changes of components biomasses and total biomass of the community. It once more points to the possibility of the use structural exergy as ecosystem health reflecting parameter.

• Journal of Contemporary Eastern Asia
• /
• v.18 no.1
• /
• pp.70-93
• /
• 2019

The contemporary educational system in South Korea is built on high-stakes standardised tests, a manifestation of the national project of social reconstruction and reform. One recent outcome is the emergence of an unfamiliar yet ubiquitous phenomenon: the "pig mum"; a Korean parent who is fully involved in organising, scheduling and managing the educational process from primary to secondary school for a group of children in a neighbourhood. Based on a quasimixed method utilizing a survey of a group of students and parents, this pilot study explores the "pig mum" phenomenon and its linkage to education policy. The authors conclude that the current educational policy fails to achieve the ideals it professes to value. This creates deep and negative societal norms that endanger a growing generation of students by creating a parallel private education market environment where "pig mums" thrive.

• Elastomers and Composites
• /
• v.54 no.2
• /
• pp.91-96
• /
• 2019

The purpose of this study was to examine the effect of different yarn twisting methods on physical properties. Plain single jersey structured fabrics were knitted from Kevlar yarn, and from Kevlar/HPPE, and from Kevlar/Basalt fiber, and from Kevlar/Glass fiber and Kevlar/Stainless steel fiber blended and core-spun yarns. and then, The fabrics were coated NBR Latex. The physical properties, including tear strength, modulus, degree of penetration, heat resistance, and cut resistance of the knitted fabrics were investigated and compared. Kevlar/HPPE blended yarn fabrics recorded the highest heat resistance (13 Sec.). and Kevlar/HPPE blended yarn fabrics had good cut resistance (Cut Level 4).

• Journal of the Semiconductor & Display Technology
• /
• v.20 no.3
• /
• pp.83-86
• /
• 2021

In this paper, electric fields in electromagnetic reverberation chambers, which are used as a substitute facility for EM-free anechoic chambers, are analyzed. This paper focused on the 4-5 GHz band, which is expected to adversely affect equipment. To analyze the field uniformity inside the electromagnetic reverberation chamber, electric field strengths are sampled and finite-difference time-domain method was used for numerical analysis. Moreover, Quadratic residue diffuser was used to improve the characteristics of the electromagnetic reverberation chamber and the uniformity of the internal field strength. Standard deviation, tolerance characteristics, and partiality characteristics were compared while varying the aiming point of transmission antenna.

• Educational Technology International
• /
• v.22 no.2
• /
• pp.199-225
• /
• 2021

The aim of the current study was to suggest priorities needed to be considered by university instructors when designing online learning. Based on three types of interactions (learner-content, learner-instructor, and learner-learner interactions) for effective online learning (Moore, 1989), draft questionnaires representing each type of interaction were written. After examining content validity by two Ph.D. experts, the survey was constructed with an Importance-Performance Analysis (IPA) form. Data of 133 university instructors were collected online. Results showed that support for designing learner-learner interaction was the priority for improving online learning. In terms of learner-instructor interaction, instructors needed to provide social-emotional support to learners so that learners could have a sense of belonging. For learner-instructor interaction, supporting instructors to monitor the level of understanding was the most highly demanding strategy for online learning. Limitations and suggestions for further studies were discussed.

• Nutrition Research and Practice
• /
• v.16 no.sup1
• /
• pp.126-133
• /
• 2022

Choline is a water-soluble organic compound that is important for the normal functioning of the body. It is an essential dietary component as de novo synthesis by the human body is insufficient. Since the United States set the Adequate Intakes (AIs) for total choline as dietary reference values in 1998, Australia, China, and the European Union have also established the choline AIs. Although choline is clearly essential to life, the 2020 Dietary Reference Intakes for Koreans (KDRIs) has not established the values because very few studies have been done on choline intake in Koreans. Since choline intake levels differ by race and country, human studies on Koreans are essential to set KDRIs. Therefore, the present study was undertaken to provide basic data for developing choline KDRIs in the future by analyzing data on choline intake in Koreans to date and reference values of choline intake and dietary choline intake status by country and race.