• Journal of Life Science
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• v.7 no.4
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• pp.282-288
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• 1997

To obtain a basic information on the development of Genus Viola, ultrastructure and electrofusion process between the two protoplasts from wild Viola callus cells and pansy mesophyll cells were observed with a scanning electron microscopy(SEM) and transmission electron microscopy(TEM). In the ultrastructural observation of wild viola callus protoplasts and pansy mesophyll protoplasts using SEM, their cell walls were removed completely. A knob-like formation was observed on the enlarge surface of viola callus protoplasts. On the surface of pansy mesophyll protoplasts net-like chloroplasts were observed. In SEM observation of pansy mesophyll protoplasts, chloroplasts devoid of membrane were observed on the surface the protoplasts. Pearl chain was formed by applying AC field of 200 V/cm at 1.0 MHz for 43 sec. The lysis of plasma membranes and fusion process occurred by applying a 1,600 V/cm DC pulse twice for 1 sec. After 1-2 hours of a DC pulse application, it was observed that the two protoplasts were fused completely into one cell. In TEM observation of the fused cell, many small vacuoles were located in the fusion area of the two protoplasts. Indeed, two distinct regions were observed during fusing process; in one region, a nucleus was found, while in the other region, both nucleus and nucleous were found.

• Journal of Surface Science and Engineering
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• v.32 no.3
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• pp.467-471
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• 1999

BN films were grown on silicon (l00) substrate by magnetically enhanced activated reactive evaporation (ME-ARE) with pulsed DC power instead of r.f. for substrate biasing. The deposited films were analyzed using Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). FTIR results show that the intensity of absorption band of $sp^2$ bond of BN decreased and that of $sp^3$ bond of c-BN increased with increasing pulsed DC bias voltage applied to substrate. The initially grown layer at the interface was observed by TEM and considered to be of$ sp^2$-bonded BN. The cross-sectional and planar TEM micrographs show that the upper layer on the initial layer was the single phase c-BN. It is concluded that cubic boron nitride films could be synthesized by ME-ARE process with pulsed DC biasing.

• Journal of Convergence for Information Technology
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• v.9 no.12
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• pp.157-165
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• 2019

Charles Lindbergh has experienced the uncontrolled situation of the aircraft while he was asleep with open eyes during his Atlantic crossing flight around 20 hours after departure from the New York in 1927 because of the fatigue. According to the NTSB(National Transportation Safety Board) reports, about 40 incidents are related fatigue in each year. The sleep loss is the most wanted item for the NTSB and may cause the similar effect as the alcohol does. The fatigue may affect the management of the threats and errors especially during take-off and landing. In this study, threats and errors of major accidents that NTSB analysed fatigue as a causal factor will be identified in order to understand the seriousness of fatigue.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.1
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• pp.64-69
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• 2019

Methylammonium lead triiodide ($MAPbI_3$)-based perovskite solar cells potentially have potential advantages such as high efficiency and low-cost manufacturing procedures. However, $MAPbI_3$ is structurally unstable and has low phase-change temperatures ($30^{\circ}C$ and $130^{\circ}C$); it is necessary to solve these problems. We investigated the crystal structure and phase separation using real-time temperature-change X-ray diffraction, transmission electron microscopy, and electron energy loss spectroscopy. $MAPbI_3$ has a tetragonal structure, and at about $35^{\circ}C$ the c-axis contracts, transforming $MAPbI_3$ into the related cubic crystal structure. In addition, at $130^{\circ}C$, phase separation occurs in which $CH_3NH_2$ and HI at the center of the unit cell of the perovskite structure are extracted by gas, leavingand only $PbI_2$ of the three-component structure, is produced as the final solid product.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.29 no.4
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• pp.124-133
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• 2021

The airline industry has been growing steadily since 2016 with more than 100 million air passengers, renewing the largest number of air passengers every year. Increasing air demand leads to an increase in air traffic in limited airspace, increasing the likelihood of accidents between aircraft. Due to the massive human and material damage caused by a single mistake, aviation safety is being heavily focused around the world to efficiently use limited airspace. Studies related to various human factors are underway as most of the aviation accidents are found to be caused by human factors, but research on human factors by controllers is insufficient while they are active in terms of control and operation. Given that 82% of air accidents caused by controllers are caused by human error, the importance of management of human error and changes in perception are urgently needed. This study aims to understand the seriousness of the controller's human error by analyzing the accident cases caused by the controller's human error using TEM to identify threats and errors and derive common human factors.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.31 no.2
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• pp.72-80
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• 2023

Line Operations Safety Audit (LOSA) is a well known preventive aviation safety program for Threat and Error management (TEM). High quality LOSA data suitable for safety management is obtained when a flight crew flies at the same level of attention as ordinary flight. Factors contributing to LOSA data quality may include flight crew's understanding on LOSA purpose, observer's career, and characteristics of the organization responsible for LOSA operations. This study explored purposes of TEM and LOSA, as well as their relationship. Previous studies mentioned quality of LOSA data can be influenced by heuristic judgment, hawthorne effect, and priming effect. This study recognized the importance of LOSA data quality to be effectively used for preventive safety management. It was confirmed that the level of understanding on LOSA concept, experience of the observer, and the characteristics of the department in charge of LOSA operation could affect the quality of LOSA data.

• Applied Microscopy
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• v.40 no.1
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• pp.47-51
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• 2010

The capability of real-time observation in TEM is quite useful to study dynamic phenomena of materials in a certain variable ambience. In performing the experiment, the choice of video recording program is an important factor to obtain high quality of movie streaming. Window Movie Maker (WMM) is generally recommended as a default video recording program if one uses "DV Capture" function in DigitalMicrograph$^{TM}$ (DM) software. However, the image quality does not often satisfy the condition for high-resolution microscopic analysis since the severe information loss in the final result occurs during the conversion process. As a good candidate to overcome this problem, Virtual-Dub is highly recommended since the information loss can be minimized through the streaming process. In this report, we demonstrated how useful VirtualDub works in a high-resolution movie recording. Quantitative comparison of the information quality between the images recorded by each software, WMM and VirtualDub, was carried out based on histogram analysis. As a result, the image recorded by VirtualDub was improved ~13% in brightness and ~122% in contrast compared with the image obtained by WMM at the same imaging condition. Remarkably, the gray gradation (meaning an amount of information) becomes wider up to ~115% than that of the WMM result.

• Korean Chemical Engineering Research
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• v.48 no.1
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• pp.98-102
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• 2010

Magnolia kobus leaf extract was used for the synthesis of bimetallic Au core-Ag shell nanoparticles. Gold seeds and silver shells were formed by first treating aqueous solution of $HAuCl_4$ and then $AgNO_3$ with the plant leaf extract as reducing agent. UV-visible spectroscopy was monitored as a function of reaction time to follow the formation of bimetallic nanoparticles. The synthesized bimetallic nanoparticles were characterized with transmission electron microscopy(TEM), energy dispersive X-ray spectroscopy(EDS), and X-ray photoelectron spectroscopy(XPS). TEM images showed that the bimetallic nanoparticles are a mixture of plate(triangles, pentagons, and hexagons) and spherical structures. The atomic Ag contents of the bimetallic Au/Ag nanoparticles determined from EDS and XPS analysis were 34 and 65 wt%, respectively, suggesting the formation of bimetallic Au core-Ag shell nanostructure. This core-shell type nanostructure is expected to have potential for application in surface enhanced Raman spectroscopy and in the sensitive detection of biomolecules.

• Applied Chemistry for Engineering
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• v.18 no.2
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• pp.173-177
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• 2007

EB irradiation method was used to prepare polyvinyl alcohol (PVA) capped silver nanoparticles under various conditions including PVA concentration, $AgNO_3$ concentration, IPA concentration, and EB dosage. The increase in the distribution of particles size was observed with an increase in the concentrations of PVA, $AgNO_3$, IPA, and EB dosage. $AgNO_3$ concentration, IPA concentration, and EB dosage were found to have a great effect on the amount of silver particles formed in PVA matrix by EB irradiation method. These results were confirmed by XRD, UV, and TEM. XRD (X-ray diffraction) technique confirmed the zero valent state of silver. Optical studies were done using UV-visible spectrophotometer to see the variation of silver particles formed in PVA matrix. Transmission Electron Microscopic (TEM) was employed to show the particle size and distribution of silver foamed in PVA matrix.

• Biomedical Science Letters
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• v.11 no.3
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• pp.389-396
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• 2005

Resent studies have reported increased isolation of extended-spectrum $\beta-lactamase$ (ESBL) producing strains at several hospital in Korea. We studied to investigate the isolation rates of ESBL strains from clinical isolates of Klebsiella pneumoniae and to characterize differences in types using analyses of genotyping and antibiotic susceptibility test. Antibiotic susceptibility test with confirmation of ESBL by double disk synergy test was performed on the 54 ESBL strains of Klebsiella pneumoniae from a hospital in Busan. Transfer of resistant gene in ESBL strains resistant to 3rd generated antibiotics was confirmed by transconjugation test using E. coli $RG176^{nal(r)}$. blaTEM, blaSHV, blaCTX-M genes were detected by PCR. ESBL producing strains had 100% of resistant rate to ampicillin, azteronam, cefazolin, cefepime and ceftriaxone ($\beta-lactam$ antibiotics). Forty strains of bla TEM$(74\%)$, 41 strains of bla SHV $(76\%)$, 23 strains of bla CTX-M $(43\%)$ were found, respectively. The strains had one or more genes. They had high resistant rates to $\beta-lactam$ antibiotics including cephalosporin. The resistant rates of strains with multiple resistant genes were higher than those of strains with single resistant gene.