• Journal of Animal Reproduction and Biotechnology
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• v.37 no.4
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• pp.292-297
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• 2022

Direct injection of CRISPR/Cas9 into zygotes enables the production of genetically modified nonhuman primates (NHPs) essential for modeling specific human diseases, such as Usher syndrome, and for developing novel therapeutic strategies. Usher syndrome is a rare genetic disease that causes loss of hearing, retinal degeneration, and problems with balance, and is attributed to a mutation in MYO7A, a gene that encodes an uncommon myosin motor protein expressed in the inner ear and retinal photoreceptors. To produce an Usher syndrome type 1B (USH1B) rhesus macaque model, we disrupted the MYO7A gene in developing zygotes. Identification of appropriately edited MYO7A embryos for knockout embryo transfer requires sequence analysis of material recovered from a trophectoderm (TE) cell biopsy. However, the TE biopsy procedure is labor intensive and could adversely impact embryo development. Recent studies have reported using cell-free DNA (cfDNA) from embryo culture media to detect aneuploid embryos in human in vitro fertilization (IVF) clinics. The cfDNA is released from the embryo during cell division or cell death, suggesting that cfDNA may be a viable resource for sequence analysis. Moreover, cfDNA collection is not invasive to the embryo and does not require special tools or expertise. We hypothesized that selection of appropriate edited embryos could be performed by analyzing cfDNA for MYO7A editing in embryo culture medium, and that this method would be advantageous for the subsequent generation of genetically modified NHPs. The purpose of this experiment is to determine whether cfDNA can be used to identify the target gene mutation of CRISPR/Cas9 injected embryos. In this study, we were able to obtain and utilize cfDNA to confirm the mutagenesis of MYO7A, but the method will require further optimization to obtain better accuracy before it can replace the TE biopsy approach.

• Composites Research
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• v.19 no.5
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• pp.7-11
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• 2006

The improved SWNTs/PANi composite actuator films applicable to an artificial muscle were fabricated successfully using a new process of manufacture that consists of 90% pure single-walled carbon nanotubes (SWNT) and chemical polymerization. PANi is electrically conducting polyaniline polymer. The conductivities of the composite SWNTs/PANi film-type actuators and the pure PANi films fabricated were measured as 56.15 S/cm and 17.38 S/cm, respectively, by the 4-prove method. The conductivity of the composite actuator is 3.2 times higher than the pure PANi film. The fabricated composite actuator showed higher conductivity than any other similar ones. The quality of samples was investigated by an electron scanning microscope (SEM). To measure the actuating strains, a specially designed beam balance apparatus was developed and strains of the composite actuators was measured by a laser displacement sensor subjected to electric currents. During the operation, the sample was soaked in the $NaNO_3$ solution and the sine-wave voltage in the range of $+1V{\sim}-1V$ was applied. The length of the composite actuator changed from $l_0=12.690$ mm to $l_1=12.733$ so that the change of length was l=0.043 mm and the strain was 0.34 %. This is a very high strain for this kind of a composite actuator. Other result reported by Tahhan showed 0.23 % strain, so that the present result is improved by 48%.

• Clean Technology
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• v.29 no.4
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• pp.244-248
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• 2023

Recently, displays play an important role in quickly delivering a lot of information. Research is underway to reproduce various colors close to natural colors. In particular, research is being conducted on the light emitting structure of displays as a method of expressing accurate and rich colors. Due to the advancement of technology and the miniaturization of devices, the need for small but high visibility displays with high efficiency in energy consumption continues to increase. Efforts are being made in various ways to improve OLED efficiency, such as improving carrier injection, structuring devices that can efficiently recombine electrons and holes in a numerical balance, and developing materials with high luminous efficiency. In this study, the electrical and optical properties of the seven-layer stacked structure rear-light emitting blue OLED device were analyzed. 4,4'-Bis(carazol-9-yl)biphenyl:Ir(difppy)2(pic), a blue light emitting material that is easy to manufacture and can be highly efficient and brightened, was used. OLED device manufacturing was performed via the in-situ method in a high vacuum state of 5×10-8 Torr or less using a Sunicel Plus 200 system. The experiment was conducted with a seven-layer structure in which an electron or hole blocking layer (EBL or HBL) was added to a five-layer structure in which an electron or hole injection layer (EIL or HIL) or an electron or hole transport layer (ETL or HTL) was added. Analysis of the electrical and optical properties showed that the device that prevented color diffusion by inserting an EBL layer and a HBL layer showed excellent color purity. The results of this study are expected to greatly contribute to the R&D foundation and practical use of blue OLED display devices.

• Economic and Environmental Geology
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• v.57 no.2
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• pp.177-184
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• 2024

This study was conducted to find a way to reduce the production of cakes generated in the domestic aggregate production process. Cakes from 8 wet aggregate producers were collected and particle size was analyzed. Samples were collected step by step from an aggregate producer A, particle size analysis was performed, and the material balance was calculated before and after an sand recovery unit by modeling the production process. As a result of the particle size analysis of eight cakes, one sample contained 50% sand, and the rest contained about 5% to 25% sand. The results showing that the cake contained a variety of sand in cakes may indicate that the recovery efficiency of the sand recovery units in the field varied. Sieve analysis of the samples showed that the generation of sand particles increased 2.8 times during the third crushing compared to the second crushing, and more cake particles were generated. As a result of simulating the sand recovery unit model, the lower the cut point of the cyclone and dewatering screen, the higher the sand production and the less cake production appeared. In order to reduce the production of cake in the field, it was determined that an optimal operation of the sand recovery unit was necessary in the aggregate production process.

• Tunnel and Underground Space
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• v.34 no.3
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• pp.185-195
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• 2024

The Incheon Metro Line 1 Geomdan Extension Phase 1 is the first project in South Korea where both a roadheader and TBM (Tunnel Boring Machine) are being used together. The shield TBM tunnel section is 1,057 m long, and is mostly composed of rock, including the section beneath the Airport Railroad and the Gyeongin Ara Waterway. A 7.8 m earth pressure balance shield TBM was used for tunnel excavation. The average monthly advance rate for both the North and South tracks is 239.1 m, with a maximum monthly advance rate of 334.5 m. This technical article comprehensively evaluates the productivity of the shield TBM, focusing on the TBM excavation performance. Above all, it aims to provide useful reference material for the successful execution of shield TBM tunnel construction.

• Maritime Security
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• v.8 no.1
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• pp.41-71
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• 2024

In international armed conflict, 'the contraband of war' under 'the law of neutrality' was developed to balance the interests of belligerents' belligerent rights and neutrals' economic interests and it began to change and evolve with the development of trade in the 19th century. The scope of material control expanded during the First and Second World Wars and continues to this day. In particular, a trend toward preventing the military use of 'conditional contraband' that could be used for both military and civilian purposes. In the process, the law regulating contraband of war expanded conceptually to become an 'international export control system' led by international organizations. Today, the contraband of war is still in effect, but there are no laws or guidelines related to the contraband of war in Korea in case of an emergency for the Korean Peninsula. Considering that it is an international practice to create and publicize a list of the contraband of war, it is necessary for Korea to prepare for it. Therefore, this paper examines the historical origins and development of the law regulating of war under the law of neutrality and examines the state practice of the contraband of war control over time. In doing so, this paper will examine the implications of the law regulating contraband of war for the Korean Peninsula through changing in the law regulating contraband of war and state practice.

• Steel and Composite Structures
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• v.50 no.5
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• pp.595-608
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• 2024

In this study, aluminum lathe waste was used by replacing aggregates in certain proportions in order to obtain expansive concrete using recycled materials. For this reason, five different aluminum wastes of 1%, 2%, 3%, 4% and 5% were selected and also reference without aluminum waste was produced. Based on the mechanical tests conducted, which included slump, compression, splitting tensile, and flexural tests, it was evident that the workability of the material declined dramatically once the volume ratio of aluminum exceeded 2%. As determined by the compressive strength test (CST), the CS of concrete (1% aluminum lathe wastes replaced with aggregate) was 11% reducer than that of reference concrete. It was noted that the reference concrete's CS values, which did not include aluminum waste, were greater than those of the concrete that contained 5% aluminum. When comparing for splitting tensile strength (STS), it was observed that the results of STS generally follow the parallel inclination as the CS. The reduction in these strengths when 1% aluminum is utilized is less than 10%. These ratios modified 18% when flexural strength (FS) is considered. Therefore, 1% of aluminum waste is recommended to obtain expansive concrete with recycled materials considering minimum loss of strength. Moreover, Scanning Electron Microscope (SEM) analysis was performed and the results also confirm that there was expansion in the aluminum added concrete. The presence of pores throughout the concrete leads to the formation of gaps, resulting in its expansion. Additionally, for practical applications, basic equations were developed to forecast the CS, STS, and FS of the concrete with aluminum lathe waste using the data already available in the literature and the findings of the current study. In conclusion, this study establishes that aluminum lathe wastes are suitable, readily available in significant quantities, locally sourced eco-materials, cost-effective, and might be selected for construction using concrete, striking a balance among financially and ecological considerations.

• Korean Journal of Environment and Ecology
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• v.38 no.4
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• pp.405-415
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• 2024

The bioacoustics generated in urban parks contribute to the overall sound diversity of a city, creating a harmonious acoustic environment and maintaining the balance of the soundscape. However, due to the rapid urbanization process, the acoustic environment in urban parks is continuously deteriorating due to increased noise. In this study, we present an approach to monitoring the acoustic environment of urban parks by analyzing the soundscape of Namsan Urban Natural Park in Seoul. Acoustic data were collected continuously for one month from August 2021 in four facility districts of the study site using autonomous recording units, and a total of 2,784 hours of sound material were obtained. We also compared soundscape characteristics over time in each district using acoustic indices (ACI, ADI, BI, NDSI) representing soundscape complexity, acoustic diversity, degree of bioacoustics, and anthropogenic disturbance. The results showed that acoustic indices related to bioacoustics varied between districts, but most indices showed similar variation patterns due to the influence of anthropogenic sounds. In particular, regional differences closed during periods of high bird activity but not during periods of high human activity. We suggest that considering both acoustic characteristics and multiple acoustic indices is necessary for managing the soundscape of urban parks. The results of this study are expected to provide essential data for assessing the health of urban ecosystems based on soundscapes and to be used for monitoring the acoustic environment of urban parks.

• Korean Journal of Food Science and Technology
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• v.37 no.3
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• pp.352-359
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• 2005

Uncertainty involved during determination of vitamin C content in infant formula was quantified by indophenol titration method. Uncertainty sources in measurand, such as purity, weight, final volume of standard, volume of standard solution used for titration, sample weight, final volume of sample, extraction solution used for titration, titration of extraction solution and standard solution by indophenol solution were identified and used as parameters for combined standard uncertainty based on Guide to the expression of uncertainty in measurement (GUM) and Draft EURACHEM/CITAC Guide. Uncertainty parameters of each source in measurand were identified as resolution, reproducibility and stability of chemical balance, standard material purity, repeatability, reproducibility, end point of titration, 1 mL pipet, 5 mL autopipet, and 100 mL mass flask. Each uncertainty component was evaluated by types A and B and included to calculate combined uncertainty. Analytical test result for traceability under laboratorial conditions using Certified Reference Material (CRM) test was certified as $108.4{\pm}1.7mg/100g$, which was within CRM certification range of $114.6{\pm}6.6mg/100g$. Uncertainty test result of vitamin C content of 5 g sampling was $56.7{\pm}2.44mg/100g$. Uncertainty could be reduced by identification of uncertainty sources and components related with vitamin C determination by indophenol titration method and by decreasing uncertainty sources and components.

• Clean Technology
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• v.17 no.1
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• pp.62-68
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• 2011

Hydrodynamic characteristics in multistage annular type fluidized bed (riser: $0.01{\times}0.025{\times}2.8m^3$, J-valve: $0.009{\times}0.015m^2$)were investigated. Glass beads ($d_p=101{\mu}m$, ${\rho}_b=1,590kg/m^3$, $U_{mf}=1.25{\times}10^{-2}m/s$, Geldart classification B) was used as a bed material. Accumulated weight by the electronic balance was measured to determine the solid flow rate in batch-type. In circulation condition, we measured the accumulated weight of particle transported from riser. At the steady state condition, solid circulation rate was calculated from time interval of the heated bed material passing between two thermocouples. Solid flow rate increased with increasing inlet gas velocity ($1.2-2.6U_{mf}$) and the static bed height (z, 0.24-0.68 m) from 2.2 to 23.4 kg/s. However, mean residence time decreased with increasing inlet gas velocity ($1.2-2.6U_{mf}$) and the static bed height (z, 0.24-0.68 m) from 1,438 to 440 s. The solid holdup in the riser was determined by measuring pressure differences according to the riser height. These results showed a similar trend to that of simple exponential decay type except for the top section of the riser. To verify the gas bypassing from top bubbling beds to middle bubbling beds, $CO_2$ gas was injected by tracer gas in constant ratio, and then was measured $CO_2$ concentration in outlet gas by gas chromatography. Gas bypassing occurred below 2.6% which is negligible value.