• Journal of the Korean Geotechnical Society
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• v.24 no.12
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• pp.65-73
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• 2008

In the current practice for slope stability problem in Japan, the shear strength, $\tau$, mobilized along the failure surface is usually estimated based on an empirical approximation in which the cohesion, c, is assumed to be equal to the soil thickness above the supposed slip surface, d(m). This approximation is advantageous in that the result of stability analysis is not influenced by the designers in charge. However, since the methodology has little theoretical background, the cohesion may often be grossly overestimated, and conversely the angle of shear resistance, $\phi$, is significantly underestimated, when the soil thickness above the supposed slip surface is quite large. In this paper, a case record of natural slope failure that took place in Hyogo Prefecture in 2007, is described in detail for the case in which the shear strength along the collapsed surface was carefully examined in a series of direct shear box (DSB) tests by considering the effects of in-situ shear stress along the slip surface. It is demonstrated that the factor of safety agrees with that of in-situ conditions when the shear strength from this kind of DSB test was employed for the back-analysis of the slope failure.

• Earthquakes and Structures
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• v.23 no.4
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• pp.373-384
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• 2022

To improve the seismic performance of suspended ceiling structures, various vibration-damping devices have been developed. However, the devices made of metals have a limit in that they cause large deformation and seriously damages the exterior of the suspended ceiling structure from the wall. As a results, their strengthening effect of the suspended ceiling structure was minimal. Thus, this study employed a spring and vibration-proof rubber effectively controlled vibrations without increasing horizontal seismic loads on the ceiling to enhance the seismic resistance of suspended ceiling structures. The objective of the study is to examine the dynamic properties of a seismic damping-isolation unit (SDI) with various details developed. The developed SDI was composed of a spring, embossed rubbers, and prestressed bolts, which were the main factors enhancing the damping effect. The shaking table tests were performed on eight SDI specimens produced with the number of layers of embossed rubber (n_s), presence or absence of a spring, prestressed force magnitude introduced in bolts (f_ps), and mass weight (W_m) as the main parameters. To identify the enhancement effect of the SDI, the dynamic properties of the control specimen with a conventional hanger bolt were compared to those of the SDI specimens. The SDI specimens were effective in reducing the maximum acceleration (A_{c max}), acceleration amplification factor (α_p), relative displacement (δ_R), and increasing the damping ratio (ξ) when compared to the control specimen. The A_{c max}, α_p, and δ_R of the SDI specimens with two rubbers, spring, and f_ps of 0.1f_by, where f_by is the yielding strength of the screw bolt were 57.8%, 58.0%, and 61.9% lower than those of the conventional hanger bolt specimens, respectively, resulting in the highest ξ (=0.127). In addition, the α_p of the SDI specimens was 50.8% lower than those specified in ASCE 7 and FEMA 356. Consequently, to accurately estimate the α_p of the SDI specimens, a simple model was proposed based on the functions of f_ps, stiffness constant of the spring (K), W_m, and n_s.

• Korean Journal of Breeding Science
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• v.51 no.4
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• pp.318-325
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• 2019

Salt stress is a significant factor limiting growth and productivity in crops. However, little is known about the response and resistance mechanism to salt stress in maize. The objective of this research was to develop an enhanced salt-tolerant silage maize by mutagenesis with gamma radiation. To generate gamma radiation-induced salt-tolerant silage maize, we irradiated a KS140 inbred line with 100 Gy gamma rays. Salt tolerance was determined by evaluating plant growth, morphological changes, and gene expression under NaCl stress. We screened 10 salt-tolerant maize inbred lines from 2,248 M₂ mutant populations and selected a line showing better growth under salt stress conditions. The selected 140RS516 mutant exhibited improved seed germination and plant growth when compared with the wild-type under salt stress conditions. Enhanced salt tolerance of the 140RS516 mutant was attributed to higher stomatal conductance and proline content. Using whole-genome re-sequencing analysis, a total of 328 single nucleotide polymorphisms and insertions or deletions were identified in the 140RS516 mutant. We found that the expression of the genes involved in salt stress tolerance, ABP9, CIPK21, and CIPK31, was increased by salt stress in the 140RS516 mutant. Our results suggest that the 140RS516 mutant induced by gamma rays could be a good material for developing cultivars with salt tolerance in maize.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.34 no.2
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• pp.73-77
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• 2024

The spinel-type oxide (Ni_x, Mn_y, Co_3-x-y)O₄ (NMC) is widely utilized as a material for temperature sensors with a negative temperature coefficient (NTC), finding applications across various industries including electric vehicle battery management systems. Typically, NMC is manufactured using solid-state reaction methods employing powders of Ni, Mn, and Co compounds, with the densification process through sintering recognized as a crucial factor determining the electrical properties of the temperature sensor material. In this study, NMC pellets were synthesized via solid-state reaction and their crystallographic and microstructural characteristics were investigated. Also, the activation energy for densification behavior during the sintering process was determined. According to the analysis results, the room temperature resistance of the NMC pellets was measured at 10.03 Kohm, with the sensitivity parameter, B-value, recorded at 3601.8 K, indicating their potential applicability as temperature sensors across various industrial fields. Furthermore, the activation energy for densification was found to be 273.3 ± 0.4 kJ/mol, providing valuable insights into the thermodynamic aspects of the sintering process of the NMC.

• Journal of the Korean Society of Marine Environment & Safety
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• v.30 no.1
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• pp.108-117
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• 2024

In this study, simulations based on computational fluid dynamics were performed for self-propulsion performance prediction of a catamaran that has asymmetrical inside and outside hull form and numerous knuckle lines. In the simulations, the Moving Reference Frame (MRF) or Sliding Mesh (SDM) techniques were used, and the rotation angle of the propeller per time step was different to identify the difference using the analysis technique and condition. The propeller rotation angle used in the MRF technique was 1˚ and those used in the SDM technique were 1˚, 5˚, or 10˚. The torque of the propeller was similar in both the techniques; however, the thrust and resistance of the hull were computed lower when the SDM technique was applied than when the MRF technique was applied, and higher as the rotation angle of the propeller per time step in the SDM technique was smaller in the simulations for several revolutions of the propeller to estimate the self-propulsion condition. The revolutions, thrust, and torque of the propeller in the self-propulsion condition obtained using linear interpolation and the delivered power, wake fraction, thrust deduction factor, and revolutions of the propeller obtained using the full-scale prediction method showed the same trend for both the techniques; however, most of the self-propulsion efficiency showed the opposite trend for these techniques. The accuracy of the propeller wake was low in the simulations when the MRF technique was applied, and slight difference existed in the expression of the wake according to the rotation angle of the propeller per time step when the SDM technique was applied.

• Journal of the Korean Society of Marine Environment & Safety
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• v.30 no.2
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• pp.184-193
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• 2024

Harbor and Fishery Design Criteria defines that ship routing should be designed to ensure safe ship navigation and easy maneuvering. The design of the channel width is one of the critical conditions in routeing of ships. For the criteria of the channel width, qualitative evaluation criteria are used in South Korea, whereas quantitative evaluation criteria are used in other countries. Environmental factors, such as winds, tidal currents, and waves directly or indirectly affect ship resistance when sailing. Depending on their strength the environmental factors may pose a threat to the safe navigation of ships. Thus, vessel traffic control was regulated in South Korea according to the Beaufort scale. In order to design the channel width to reflect the environmental factors closely related to the safe navigation of ships, quantitative evaluation criteria reflected with environmental factors were presented in other countries, however, these external factors were not considered in South Korea. This study analyzed the relationship between the channel width actually used by ships and environmental factors by using the trajectories of ships entering and leaving Mokpo Port. This study also suggested the required channel width according to tidal currents and compared it with the channel width design criteria of other countries.

• Journal of the Korean Electrochemical Society
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• v.27 no.3
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• pp.97-104
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• 2024

The electrodes of commercialized lithium secondary batteries are manufactured through a wet coating process, and the drying process (DC) is a very important factor as to electrode production speed and process cost. In this study, silicon anodes were manufactured under high-temperature (180 ℃) and low-temperature (50 ℃) DC to investigate the quality and the electrochemical performance of Si-electrodes according to DC. High-temperature DC can quickly evaporate the solvent in the Si-electrode slurry, improving the electrode production rate. However, this also causes the electrode composite to peel off from the current collector. As a result, the Si-electrode's adhesion weakened, and the electrode coating's quality deteriorated. In addition, the Si-electrode manufactured under high-temperature was found to have a thicker composite material than the Si-electrode manufactured under low-temperature. Si-electrodes manufactured under high-temperature had higher sheet resistance and lower electrical conductivity than those manufactured under low-temperature. Consequently, the Si-electrode manufactured under low-temperature showed 152.5% superior cycle performance compared to the Si-electrode manufactured under high-temperature. (Discharge capacities of Si-electrodes manufactured under high-temperature and low-temperature DC were 844 and 1287 mAh g^-1, respectively, after 300 cycles). Establishing the DC of Si-electrodes can easily provide new perspectives to improve the quality and stability of Si-electrodes.

• Korean Journal of Organic Agriculture
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• v.32 no.2
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• pp.233-245
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• 2024

In a field study, we investigated the consequences associated with the irrigation of red pepper with water contaminated by three types of veterinary antibiotics (amoxicillin, oxytetracycline, and chlortetracycline) on the soil residue, the absorption-translocation, and crop yields. As a result of evaluating the residue of veterinary antibiotics in pepper cultivation soil treated with veterinary antibiotics a total of 7 times from June 7 to August 26, 2023, the three antibiotics were not detected at the background level, but in the group treated with 10-fold and 50-fold of the background level was detected at a level of 2-10 ㎍/kg. For the leaf (stem) and fruit of red pepper, all three types of veterinary antibiotics were found to be below the detection limit at all treatments. However, trace levels were detected in red pepper roots. If veterinary antibiotics are unintentionally introduced into agricultural soil in the short term, the soil environment and crop safety will not be a problem. However, long-term introduction of veterinary antibiotics in agricultural soil may have negative effects by affecting soil microbial diversity and antibiotic resistance problems, so continuous monitoring and risk assessment are deemed necessary.

• 한국균학회소식:학술대회논문집
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• 2015.05a
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• pp.59-59
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• 2015

Cryptococcus neoformans causes life-threatening meningoencephalitis in humans, but the treatment of cryptococcosis remains challenging. To develop novel therapeutic targets and approaches, signaling cascades controlling pathogenicity of C. neoformans have been extensively studied but the underlying biological regulatory circuits remain elusive, particularly due to the presence of an evolutionarily divergent set of transcription factors (TFs) in this basidiomycetous fungus. In this study, we constructed a high-quality of 322 signature-tagged gene deletion strains for 155 putative TF genes, which were previously predicted using the DNA-binding domain TF database (http://www.transcriptionfactor.org/). We tested in vivo and in vitro phenotypic traits under 32 distinct growth conditions using 322 TF gene deletion strains. At least one phenotypic trait was exhibited by 145 out of 155 TF mutants (93%) and approximately 85% of the TFs (132/155) have been functionally characterized for the first time in this study. Through high-coverage phenome analysis, we discovered myriad novel TFs that play critical roles in growth, differentiation, virulence-factor (melanin, capsule, and urease) formation, stress responses, antifungal drug resistance, and virulence. Large-scale virulence and infectivity assays in insect (Galleria mellonella) and mouse host models identified 34 novel TFs that are critical for pathogenicity. The genotypic and phenotypic data for each TF are available in the C. neoformans TF phenome database (http://tf.cryptococcus.org). In conclusion, our phenome-based functional analysis of the C. neoformans TF mutant library provides key insights into transcriptional networks of basidiomycetous fungi and ubiquitous human fungal pathogens.

• Korean Journal of Microbiology
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• v.41 no.3
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• pp.216-224
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• 2005

Chromatography has now been used successfully to provide the requisite purity for human plasma-derived biop-harmaceuticals such as coagulation factors and immunoglobulins. Recently, increasing attention has been focused on establishing efficient cleaning procedures to prevent potential contamination by microorganisms as well as carry-over contamination from batch to batch. The purpose of present study was to develop a cleaning validation system for the assurance of virus removal and/or inactivation during chromatography process. In order to establish an assay system for the validation of virus clearance during chromatography cleaning process, a quantitative real-time PCR method for porcine parvovirus(PPV) was developed, since PPV, a model virus for human parvovirus B19, has a high resistance to a range of physico-chemical treatment. Specific primers for amplification of PPV DNA was selected, and PPV DNA was quantified by use of SYBR Green I. The sensitivity of the assay was calculated to be 1.5 $TCID_{50}/ml$. The established real-time PCR assay was successfully applied to the validation of PPV removal and cleaning during SP-Sepharose cation chromatography for thrombin purification and Q-Sepharose anion chromatography for factor VIII purification. The comparative results obtained by real-time PCR assay and infectivity titrations suggested that the real-time PCR assay could be a useful method for chromatography cleaning validation and that it could have an additive effect on the interpretation and evaluation of virus clearance during the virus removal process.