• Geotechnical Engineering
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• v.14 no.6
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• pp.73-80
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• 1998

In order to identify clay minerals in the soft ground, which has been deposited along the coastline of the Korean peninsula, 14 samples have been taken at different locations and then X-ray diffraction analysis is carried out for them. It is known from the analysis that the various kinds of clay minerals mixed with different portions exist in the soft ground, but halloysite is not traced in any samples. It is featured regionally that kaolinite and illite are found in the western coast and the southern coast. Montmorillonites exists only in the western coast. This feature of regional occurrences can be explained with the help of geology of the region. Activities determined from physical properties of the soils do not coincide with those of clay minerals identified from X-ray diffraction analysis.

• Journal of the Korean Magnetics Society
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• v.24 no.2
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• pp.66-69
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• 2014

The spreading tube of X-ray cathode tube displayed with an electromagnetic finite element method was designed. To analyze a feature design and the concrete coordinate performance of soft X-ray tube modeling, the orbit of electron beam was simulated by OPERA-3D SW program. The fixed conditions were the applied voltage, the temperature, the work function of thermal electron between cathode and anode of tungsten. Through the analysis of distribution of electron beam and the variation of dividing region, the design of soft X-ray spreading tube equipped with two cross filaments was optimized.

• Current Applied Physics
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• v.18 no.11
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• pp.1174-1181
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• 2018

In nanomagnetism, one of the crucial scientific questions is whether magnetic behaviors are deterministic or stochastic on a nanoscale. Apart from the exciting physical issue, this question is also of paramount highest relevance for using magnetic materials in a wealth of technological applications such as magnetic storage and sensor devices. In the past, the research on the stochasticity of a magnetic process has been mainly done by macroscopic measurements, which only offer ensemble-averaged information. To give more accurate answer for the question and to fully understand related underlying physics, the direct observation of statistical behaviors in magnetic structures and magnetic phenomena utilizing advanced characterization techniques is highly required. One of the ideal tools for such study is a full-field soft X-ray microscope since it enables imaging of magnetic structures on the large field of view within a few seconds. Here we review the stochastic behaviors of various magnetic processes including magnetization reversal process in thin films, magnetic domain wall motions in nanowires, and magnetic vortex formations in nanodisks studied by full-field soft X-ray microscopy. The origin triggering the stochastic nature witnessed in each magnetic process and the way to control the intrinsic nature are also discussed.

• Journal of the Korean Society of Safety
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• v.32 no.2
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• pp.34-37
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• 2017

In recent emerging industry, Display field becomes bigger and bigger, and also semiconductor technology becomes high density integration. In Flat Panel Display, there is an issue that electrostatic phenomenon results in fine dust adsorption as electrostatic capacity increases due to bigger size. Destruction of high integrated circuit and pattern deterioration occur in semiconductor and this causes the problem of weakening of thermal resistance. In order to solve this sort of electrostatic failure in this process, Soft X-ray ionizer is mainly used. Soft X-ray Ionizer does not only generate electrical noise and minute particle but also is efficient to remove electrostatic as it has a wide range of ionization. X-ray Generating efficiency has an effect on soft X-ray Ionizer affects neutralizing performance. There exist variable factors such as type of anode, thickness, tube voltage etc., and it takes a lot of time and financial resource to find optimal performance by manufacturing with actual X-ray tube source. MCNPX (Monte Carlo N-Particle Extended) is used for simulation to solve this kind of problem, and optimum efficiency of X-ray generation is anticipated. In this study, X-ray generation efficiency was measured according to target material thickness using MCNPX under the conditions that tube voltage is 5 keV, 10 keV, 15 keV and the target Material is Tungsten(W), Gold(Au), Silver(Ag). At the result, Gold(Au) shows optimum efficiency. In Tube voltage 5 keV, optimal target thickness is $0.05{\mu}m$ and Largest energy of Light flux appears $2.22{\times}10^8$ x-ray flux. In Tube voltage 10 keV, optimal target Thickness is $0.18{\mu}m$ and Largest energy of Light flux appears $1.97{\times}10^9$ x-ray flux. In Tube voltage 15 keV, optimal target Thickness is $0.29{\mu}m$ and Largest energy of Light flux appears $4.59{\times}10^9$ x-ray flux.

• Journal of Ginseng Research
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• v.8 no.2
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• pp.167-171
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• 1984

Soft X-ray is useful to identify the quality of fresh ginseng causing the inside cavity or white pan of red ginseng. The portion of low mass density identified by the difference in absorption of soft X-ray showed lower dry matter density and less or no response to iodine test indicating less accumulation or excess consumption of starch. The inside white part of red ginseng absorbed less X-ray than the normal part did. Probability for identification of the inside cavity or white at fresh ginseng was rather high (80-90%) in screen observation than f'3m reading and seemed to be increased further by using the developed screen and with training. The inside white of red ginseng appeared to be due to starch deficiency. Dry matter density appeared to be better than fresh weight density for the quality criterion.

• Journal of the Korean Geotechnical Society
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• v.20 no.9
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• pp.155-166
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• 2004

The characteristics of soft clays are very important for the land development plan. This study is to investigate correlations between the engineering properties and the characteristics of clay minerals of the undisturbed clay samples obtained from Sihwa area. This study included X-Ray diffraction analysis, X-Ray fluorescence spectrometer analysis, scanning electron microscopy analysis and energy dispersive X-Ray spectrometer analysis. The correlations between the clay mineral properties and the laboratory and field testing results were investigated. The characteristics of soft clay in Sihwa area were compared with those in Yangsan and Kunsan area.

• Current Applied Physics
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• v.18 no.11
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• pp.1201-1204
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• 2018

The effect of electric current pulses on a sub-100 nm magnetic bubble state in a symmetric Pt/Co multilayer was directly observed using a full-field transmission soft X-ray microscope (MTXM). Field-induced evolution of the magnetic stripe domains into isolated bubbles with their sizes down to 100 nm was imaged under varying external magnetic fields. Electric current pulses were then applied to the created magnetic bubbles, and it was observed that the bubbles could be either created or annihilated by the current pulse depending on the strength of applied magnetic field. The results suggest that the Joule heating plays a critical role in the formation and/or elimination of the bubbles and skyrmions. Finally, the schematic phase diagram for the creation and annihilation of bubbles is presented, suggesting an optimized scheme with the combination of magnetic field and electric current necessary to utilize skyrmions in the practical devices.

• Korean Journal of Optics and Photonics
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• v.13 no.3
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• pp.189-196
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• 2002

The components and alignment parameters of a flat-field soft x-ray spectrometer used in the wavelength range below 50 $\AA$ are determined, and the characteristics of the spectrometer are analyzed. It consists of a toroidal mirror, a slit, a varied line-spacing concave grating, and a soft x-ray detector. The space-resolved spectral image of a source is formed on a single plane using the tordidal mirror and the 2400-grooves/mm varied line-spacing concave grating. The former is used to compensate for the astigmatism caused by the grazing incidence of soft x-ray light on the concave grating. The spectral and spatial resolutions of the spectrometer are calculated by applying the wave front aberration theory, and the diffraction efficiency is calculated by applying the scalar diffraction theory.

• Journal of Korean Neurosurgical Society
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• v.42 no.2
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• pp.97-102
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• 2007

Objective : The authors attempted to evaluate the pattern of the airway narrowing due to prevertebral soft tissue swelling after surgery of the anterior cervical spine and their clinical significances using plain cervical X-ray images. Methods : Twenty-four patients undergoing anterior cervical spine surgery were reviewed from January 2004 to December 2005. Postoperatively, in daily basis, lateral radiograph of the neck was obtained in neutral position. We measured the upper airway diameter above and below the epiglottis level and prevertebral soft tissue diameter every day for a week and finally 2 weeks after surgery using their simple lateral cervical X-ray films. Results : Both airway narrowing and prevertebral soft tissue swelling were maximum in postoperative 2 days, and decreased rapidly in postoperative 7 days. Airway narrowing was aggravated postoperatively but slowly decreased as prevertebral soft tissue swelling diminished. But, the severity of airway narrowing showed no clinical correlations with clinical symptom and radiologic severity. Conclusion : Not all patients who show severe airway narrowing and prevertebral soft tissue swelling on their plain cervical X-ray film complain respiratory insufficiency. But, the patients with undergoing anterior cervical spine surgery should be monitored carefully for respiratory insufficiency, especially during several days following operation because both airway narrowing and prevertebral soft tissue swelling become peak at postoperative 2-3 days.

• Applied Microscopy
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• v.38 no.3
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• pp.235-243
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• 2008

A compact soft x-ray microscope operated in the 'water window' wavelength region ($2.3{\sim}4.4nm$) was used for observing cells with nano-scale spatial resolution. To obtain cellular imaging captured with colloidal gold nanoparticles using a compact soft x-ray microscope. The colloidal gold nanoparticles showed higher contrast and lower transmission more than 7 times than that of cellular protein on the soft x-ray wavelength region. The structure and thickness of the cell membrane of the Coscinodiscus oculoides (diatome) and red blood cells were seen clearly. The gold nanoparticles within the HT1080 and MDA-MB 231 cells were seen clearly on the soft x-ray microscopy. The gold nanoparticles were aggregated within vesicles by endocytosis.