• KOREAN JOURNAL OF CROP SCIENCE
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• v.30 no.2
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• pp.195-200
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• 1985

This experiment was carried out to know the processes of protoplast isolation, culture and plant regeneration in aims of introducing foreign genes into plant cells through plant gene vector, and cellular selection for plant improvement. The main results indicated that 2% cellulase plus 0.5% macerozyme is proper for isolation of protoplasts from leaf mesophyll cells of N. plumbaginifolia, plating efficiency was higher in 1.4-2.0 x 10$^4$ cells/ml, complete cell wall was regenerated after 2 days culture, cell division and cell mass were observed after 4 days and 2 weeks, respectively, colony was developed after 3 weeks culture, addition of 1-2mg/l BA promoted shoot differentiation while root differentiation did not required hormone and seeds were harvested from more than 100 cell lines for further investigation and study.

• Applied Chemistry for Engineering
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• v.34 no.2
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• pp.180-185
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• 2023

To improve the efficiency of water electrolysis, it is essential to develop an oxygen evolution reaction (OER) electrocatalyst with high performance and long-term stability, accelerating the reaction rate of OER. In this study, a hollow metal-organic framework (MOF)-derived ruthenium-cobalt oxide catalyst was developed to synthesize an efficient OER electrocatalyst. As the synthesized catalyst increases the surface exposure of ruthenium, a low overpotential (386 mV) was observed at a current density of 10 mA/cm² with a low Tafel slope. It is expected to be able to replace noble metal catalysts by showing higher mass activity and stability than commercial RuO₂ catalysts.

• Journal of the Korean Geotechnical Society
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• v.22 no.5
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• pp.47-57
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• 2006

The shear wave velocity is related with the stiffness of granular skeleton and mass density. The shear stiffness of the granular skeleton remains unaffected by the presence of the fluid. Bender elements are convenient shear wave transducers for instrumenting soil cells due to optimal soil-transducer coupling. This study addresses the principles of the shear wave, the design and implementation of bender elements including electromagnetic coupling prevention, directivity, resonant frequency, detection of first arrival, and near field effects. It is shown that electromagnetic coupling effects can be minimized using parallel-type bender elements. Thus, the in-plane S-wave directivity is quasi-circular. The resonant frequency of bender element installations depends on the geometry of the bender element, the anchor efficiency and the soil stiffness. One of the most cumbersome parts in the bender element test is near field effects, which affect the selection of arrival time. The selection of the first arrival within the near field Is effectively solved by the multiple reflection technique and signal matching technique. Bender elements, which requires several considerations, may be effective tools for the subsurface characterization by using S-wave.

• The Plant Pathology Journal
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• v.39 no.1
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• pp.39-51
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• 2023

Common bean (Phaseolus vulgaris L.) is one of the most important crops in human food production. The occurrence of diseases, such as white mold, caused by Sclerotinia sclerotiorum can limit the production of this legume. The use of Trichoderma has become an important strategy in the suppression of this disease. The aim of the present study was to evaluate the effect of volatile organic compounds (VOCs) emitted by Trichoderma azevedoi CEN1241 in five different growth periods on the severity of white mold in common bean. The in vitro assays were carried out in double-plate and split-plate, and the in vivo assays, through the exposure of the mycelia of S. sclerotiorum to the VOCs of T. azevedoi CEN1241 and subsequent inoculation in bean plants. Chemical analysis by gas chromatography coupled to mass spectrometry detected 37 VOCs produced by T. azevedoi CEN1241, covering six major chemical classes. The profile of VOCs produced by T. azevedoi CEN1241 varied according to colony age and was shown to be related to the ability of the biocontrol agent to suppress S. sclerotiorum. T. azevedoi CEN1241 VOCs reduced the size of S. sclerotiorum lesions on bean fragments in vitro and reduced disease severity in a greenhouse. This study demonstrated in a more applied way that the mechanism of antibiosis through the production of volatile compounds exerted by Trichoderma can complement other mechanisms, such as parasitism and competition, thus contributing to a better efficiency in the control of white mold in bean plants.

• Smart Structures and Systems
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• v.31 no.3
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• pp.283-299
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• 2023

Structural stability of floating platforms has long since been a crucial issue in the field of marine engineering. Excessive motions would not only deteriorate the operating conditions but also seriously impact the safety, service life, and production efficiency. In recent decades, several control devices have been proposed to reduce unwanted motions, and an attractive one is the tuned heave plate (THP). However, the THP system may reduce or even lose its effectiveness when it is mistuned due to the shift of dominant wave frequency. In the present study, a novel adaptive tuned heave plate (ATHP) is proposed based on inerter by adjusting its inertance, which allows to overcome the limitation of the conventional THP and realize adaptations to the dominant wave frequencies in real time. Specifically, the analytical model of a representative semisubmersible platform (SSP) equipped with an ATHP is created, and the equations of motion are formulated accordingly. Two optimization strategies (i.e., J₁ and J₂ optimizations) are developed to determine the optimum design parameters of ATHP. The control effectiveness of the optimized ATHP is then examined in the frequency domain by comparing to those without control and controlled by the conventional THP. Moreover, parametric analyses are systematically performed to evaluate the influences of the pre-specified frequency ratio, damping ratio, heave plate sizes, peak periods and wave heights on the performance of ATHP. Furthermore, a Simulink model is also developed to examine the control performance of ATHP in the time domain. It is demonstrated that the proposed ATHP could adaptively adjust the optimum inertance-to-mass ratio by tracking the dominant wave frequencies in real time, and the proposed system shows better control performance than the conventional THP.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.1B
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• pp.137-147
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• 2008

Soil Vapor Extraction (SVE) has been extensively used to remove volatile organic compounds (VOCs) from the vadoze zone. In order to investigate the removal mechanism during SVE operation, laboratory modeling experiments were carried out and tailing effect could be observed in later stage of the experiment. Tailing effect means that removal rate of contaminants gets significantly to decrease in later stage of SVE operation. Also, mathematical model simulating the tailing effect was used, which considers rate-limited diffusion in a water film during mass transfer among gas, liquid, and solid phases. Measurement data obtained through the experiment was used as input data of the numerical analyses. Sensitivity analysis was performed to examine the effect of each parameter on required time to reach final target concentration. Finally, it was found that the concentration in the soil phase decreased significantly with a liquid and gas diffusion coefficient larger, actual path length shorter, and water saturation smaller.

• Progress in Superconductivity and Cryogenics
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• v.25 no.3
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• pp.49-55
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• 2023

This paper presents the design of a re-liquefaction system as a BOG (boil-off gas) handling process in liquid hydrogen transport vessels. The total capacity of the re-liquefaction system was assumed to be 3 ton/day, with a BOR (boil-off rate) of 0.2 %/day inside the cargo. The re-liquefaction cycle was devised using the He-Brayton Cycle, incorporating considerations of BOG capacity and operational stability. The primary components of the system, such as compressors, expanders, and heat exchangers, were selected to meet domestically available specifications. Case studies were conducted based on the specifications of the components to determine the optimal design parameters for the re-liquefaction system. This encompassed variables such as helium mass flow rate, the number of compressors, compressor inlet pressure and compression ratio, as well as the quantity and composition of expanders. Additionally, an analysis of exergy destruction and exergy efficiency was carried out for the components within the system. Remarkably, while previous design studies of BOG re-liquefaction systems for liquid hydrogen vessels were confined to theoretical and analytical realms, this research distinguishes itself by accounting for practical implementation through equipment and system design.

• Resources Recycling
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• v.33 no.2
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• pp.24-36
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• 2024

The lithium-ion battery recycling process has been classified into direct recycling, hydrometallurgical process, and pyrometallurgical process. The commercial process based on the hydrometallurgical process produces black mass through pretreatment processes consisting of dismantling, crushing and grinding, heat treatment, and beneficiation, and then each metal is recovered by hydrometallurgical processes. Since all lithium-ion battery recycling processes under development conducts hydrometallurgical processes such as leaching, after the pretreatment process, to produce precursor raw materials, this article suggests a classification method according to the pretreatment method of the recycling process. The processes contain sulfation roasting, carbothermic reduction roasting, and alloy manufacturing, and the economic feasibility of the lithium-ion battery recycling process can be enhanced using unused by-products in the pretreatment process.

• Journal of the Semiconductor & Display Technology
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• v.23 no.1
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• pp.92-96
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• 2024

The application of the technology for forming Al₂O₃ thin films using ALD(atomic layer deposition) method is rapidly increasing in the semiconductor and display fields. In order to increase the efficiency of the ALD process in a mass production line, metallic by-products generated from the ALD process chamber must be effectively collected. By collecting by-products flowing out of the chamber with a cold trap device before they go to the vacuum pump, damage to the vacuum pump can be prevented and the work room can be maintained stably, resulting in increased process flow rate. In this study, a cold trap was installed between the ALD process chamber and the dry pump to measure and analyze by-products generated during the Al₂O₃ thin film deposition process. As a result, it was confirmed that Al and O elements were discharged, and the collection forms were two types: bulk and powder. And the binding energy peaked at 73.7 ~ 74.3 eV, the binding energy of Al 2p, and 530.7 eV, the binding energy of O 1s, indicating that the binding structure was Al-O.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.37 no.5
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• pp.554-561
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• 2024

Micro light-emitting diodes (µLEDs) have been utilized in various fields such as displays, and smart devices, due to their superior stabilities. Since the applications of the µLEDs have been extended to medical devices and wearable sensors, excellent optical properties and uniformity of the µLEDs are important. Hence, several researchers have investigated to enhance the optical efficiency of the µLEDs through micro/nano lens. However, the reported methods for realizing the micro/nano lens have some drawbacks such as complex and high-cost manufacturing processes. Herein, we developed µLEDs with 3D-printed hydrogel microlenses. The printed hydrogel had high transparency and excellent adhesive strength, allowing it to attach onto top surface of the µLEDs without any additional adhesives. Microscale printing technology using a 3D printer achieved quick and fine printing in desired shapes and arrangements, showing the possibility of mass production. The 3D-printed microlens can be applied to improve not only the optical properties of µLEDs but also other optical devices.