• Journal of Microbiology and Biotechnology
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• v.29 no.8
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• pp.1221-1229
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• 2019

Mycobacterium tuberculosis, a causative pathogen of tuberculosis (TB), still threatens human health worldwide. To find a novel drug to eradicate this pathogen, we tested taurine-5-bromosalicylaldehyde Schiff base (TBSSB) as an innovative anti-mycobacterial drug using Mycobacterium smegmatis as a surrogate model for M. tuberculosis. We investigated the antimicrobial activity of TBSSB against M. smegmatis by plotting growth curves, examined the effect of TBSSB on biofilm formation, observed morphological changes by scanning electron microscopy and transmission electron microscopy, and detected differentially expressed proteins using two-dimensional gel electrophoresis coupled with mass spectrometry. TBSSB inhibited mycobacterial growth and biofilm formation, altered cell ultrastructure and intracellular content, and inhibited cell division. Furthermore, M. smegmatis adapted itself to TBSSB inhibition by regulating the metabolic pathways and enzymatic activities of the identified proteins. NDMA-dependent methanol dehydrogenase, NAD(P)H nitroreductase, and amidohydrolase AmiB1 appear to be pivotal factors to regulate the M. smegmatis survival under TBSSB. Our dataset reinforced the idea that Schiff base-taurine compounds have the potential to be developed as novel anti-mycobacterial drugs.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.2
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• pp.1-12
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• 2019

A fundamental study on a gas injection variable thrust method for thrust throttling in a liquid rocket engine was conducted. The gas injection variable thrust has the advantage of not only being able to control the thrust with a simple structure but it also increases the atomization performance through the injection pressure drop that increases in direct proportion to the density reduction. In this study, spray characteristics such as spray instability, spray pattern, spray angle, and breakup length based on changes in the liquid mass flow rate and amount of injected gas were investigated using effervescent swirl injectors.

• Microbiology and Biotechnology Letters
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• v.47 no.1
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• pp.69-77
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• 2019

Screening microorganisms that can produce glucan hydrolases for industrial, environmental, and biomedical applications is important. Herein, we describe a novel approach to perform glucan hydrolase screening-based on analysis of matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) spectra-which involves degradation of the oligo- and polysaccharides. As a proof-of-concept study, glucan hydrolases that could break down glucans made of several glucose units were used to demonstrate the MALDI-MS-based enzyme assay. First, the enzyme activities of ${\alpha}$-amylase and cellulase on a mixture of glucan oligosaccharides were successfully discriminated, where changes of the MALDI-MS profiles directly reflected the glucan hydrolase activities. Next, we validated that this MALDI-MS-based enzyme assay could be applied to glucan polysaccharides (i.e., pullulan, lichenan, and schizophyllan). Finally, the bacterial glucan hydrolase activities were screened on 96-well plate-based platforms, using cell lysates or samples of secreted enzyme. Our results demonstrated that the MALDI-MS-based enzyme assay system would be useful for investigating bacterial glucoside hydrolases in a high-throughput manner.

• Geomechanics and Engineering
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• v.18 no.1
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• pp.71-83
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• 2019

This investigation presented conventional triaxial and creep-permeability tests on sandstones considering thermally-induced damage (TID). The TID had no visible effects on rock surface color, effective porosity and permeability below $300^{\circ}C$ TID level. The permeability enlarged approximately two orders of magnitude as TID increased to $1000^{\circ}C$ level. TID of $700^{\circ}C$ level was a threshold where the influence of TID on the normalized mass and volume of the specimen can be divided into two linear phases. Moreover, no prominent variations in the deformation moduli and peak strength and strain appeared as TID< $500^{\circ}C$ level. It is interesting that the peak strength increased by 24.3% at $700^{\circ}C$ level but decreased by 11.5% at $1000^{\circ}C$ level. The time-related deformation and steady-state creep rate had positive correlations with creep loading and the TID level, whereas the instantaneous modulus showed the opposite. The strain rates under creep failure stresses raised 1-4 orders of magnitude than those at low-stress levels. The permeability was not only dependent on the TID level but also dependent on creep deformation. The TID resulted in large deformation and complexity of failure pattern for the sandstone.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.1
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• pp.63.1-63.1
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• 2019

Solar system small bodies are unusual objects in astronomical survey data in that they are moving on the celestial sphere. In addition, even in a normal status, their magnitudes are changing over time, firstly because their relative positions with respect to the Sun and Earth are continually changing, secondly because they are rotating bodies with non-spherical shapes. Furthermore, some of them might exhibit unexpected activities, which could be caused by mass ejection or disintegration. Detections and observations of such activities are challenging due to their abrupt nature. Therefore, continuous monitoring observations of large number of Solar system small bodies are required to systematically obtain detailed/transient information about them. Since 2018/2019 winter, we have launched a new project using Korea Microlensing Telescope Network (KMTNet) for detecting such transient phenomena of Solar system objects. Our main goal is to monitor the magnitudes and detect sudden brightness changes. We also plan to discover interesting new objects, and monitor rotational brightness oscillations of asteroids. We intend to monitor the magnitudes of ~ 20,000 known Solar system small bodies per night, and acquire lightcurves of ~ 1,000 asteroids.

• Journal of Drive and Control
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• v.18 no.3
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• pp.1-7
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• 2021

In a hydraulic control system, since a hydraulic cylinder drives a relatively large mass of an object, an external load force acts as a disturbance on the control performance of the system. Additionally, as the hydraulic system is used for a long period, there are disturbances that occur gradually, such as a drop in supply pressure because of abrasion of the pump, oil leakage from a valve, and oil leakage from a cylinder. In this study, a state feedback controller based on a linearization technique is applied. To prevent the performance degradation of the controller from the load disturbance, an Extended Luenberger observer (ELO) is used for the Extended system. The case of using the proportional controller, which is a representative linear controller, and the result of using the controller designed in this study are compared and reviewed through simulation. Also, we propose an experimental gain-setting method for a state feedback controller that can be used at industrial sites, and examine how the stability and control performance of the system changes because of the disturbance inputs through the experimental results.

• Journal of Surface Science and Engineering
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• v.55 no.6
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• pp.441-447
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• 2022

Silicon-based materials are one of the most promising anode active materials in lithium-ion battery. A carbon layer decorated on the surface of silicon particles efficiently suppresses the large volume expansion of silicon and improves electrical conductivity. Carbon coating through chemical vapor deposition (CVD) is one of the most effective strategies to synthesize carbon- coated silicon materials suitable for mass production. Herein, we synthesized carbon coated SiOx via pilot scale CVD reactor (P-SiO_x@C) and carbon coated SiO_x via industrial scale CVD reactor (I-SiO_x@C) to identify physical characteristic changes according to the CVD capacity. Reduced size silicon domains and local non-uniform carbon coating layer were detected in I-SiO_x@C due to non-uniform temperature distribution in the industrial scale CVD reactor with large capacity, resulting in increased surface area due to severe electrolyte consumption.

• Journal of English Language & Literature
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• v.57 no.1
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• pp.3-25
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• 2011

As extremes of climate such as heavy storms, rainfalls, and droughts tend to be routine in recent years, global climate change becomes a serious concern not only for natural scientists but also for scholars of the human sciences. Efforts to tackle the anthropogenic climate change certainly require not only scientific knowledge about it but also a new sociocultural paradigm for valorizing and respecting nature in its own right. The huge casualties and mass destruction caused by recent climate disasters also remind us that nature has been an important factor to bring about changes in human history-a fact largely ignored in traditional history. This again validates the ecocritical request to prioritize place, physical setting, or the relationship characters hold with the natural world in understanding literary works. In this context this paper aims to demonstrate the importance of the meteorological vision in creating as well as understanding literary and cultural texts by examining such works as Shelley's "The Cloud," Byron's "Darkness," Keats's "To Autumn," all produced during the period of dramatic climate change including "the year without summer." It also briefly discusses Roland Emmerich's 2004 movie The Day after Tomorrow as a way of understanding recent cultural responses to the crisis of global warming.

• Korean Journal of Plant Resources
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• v.34 no.1
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• pp.17-22
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• 2021

Plants regenerated from in vitro cultures carry chromosomal variations, especially in long-term culture. Reducing the duration of plant tissue culture is one of the ways to reduce genetic and epigenetic changes. In this study, we reduced the duration of long-term culture and repeat subculture using small bulblets derived from bulb scales in two lily cultivars. The adventitious bulblets derived from bulb-scale tissue were cultured on three different media containing Murashige and Skoog (MS) basal medium supplemented with 1 g/L Charcoal, MS medium containing 0.3 mg/L IAA and 0.4 mg/L BA hormone with or without Charcoal, respectively. About seven weeks later, the number of newly propagated multiple shoots in the two media, A and B media, showed little differentiation. Compared to both media, the number of propagated multiple shoots increased 5-fold in MS medium containing 0.3 mg/L IAA and 0.4 mg/L BA hormone without Charcoal (C medium). The number of propagated multiple shoots ranged from 5 to 6 and 4 to 6 with an average of 5 in TropicalPink and GreenStar cultivars, respectively. The flow cytometric measurements indicated no variation in the ploidy level between control and in vitro propagated plants.

• Journal of the Korean Wood Science and Technology
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• v.49 no.1
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• pp.82-92
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• 2021

Nakdong technique is an unfamiliar scorching treatment using an iron heated in a kiln over 1000℃. It is a typical convention in Asian countries to treat Nakdong on the surface of paulownia species. The scorching treatment changes the surface characteristics as well as the color of the wood. This study focused on the effects of functional features such as water resistance, anti-mold, anti-termite, and sound improvement because this treatment is usually used on paulownia wood-bodied musical instruments surface. It took 28'57" for Nakdong-iron treated surface to absorb a droplet of water. The absorbance time of iron treated surface was longer than that of torch treated one. There was no noticeable effect on the anti-mold test. On the anti-termite test, there was nearly 3% more mean mass loss on the torch samples than controlled and iron treated ones. In examining the sound radiation coefficient before and after Nakdong treatment, the Nakdong-iron treated surface showed an increase in the average value of 1.2 m4/kg s, which means that it has sound quality improvement. Through this research, the Nakdong technique results are expected to be used as basic-data for further research and give a practical idea for using the traditional treatment method on the wood surface.