• Economic and Environmental Geology
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• v.56 no.6
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• pp.745-764
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• 2023

In the Republic of Congo, Banded iron formations (BIFs) occur in two areas: the Chaillu Massif and the Ivindo Basement Complex, which are segments of the Archean Congo craton outcropping in the northwestern and southwestern parts of the country. They show interesting potential with significant mineral resources reaching 2 Bt and grades up to 60% Fe. BIFs consist mostly of oxide-rich facies (hematite/magnetite), but carbonate-rich facies are also highlighted. They are found across the country within the similar geological sequences composed of amphibolites, gneisses and greenschists. The Post-Archean Australian Shale (PAAS)-normalized patterns of BIFs show enrichment in elements such as SiO₂, Fe₂O₃, CaO, P₂O₅, Cr, Cu, Zn, Nb, Hf, U and depletion in TiO₂, Al₂O₃, MgO, Na₂O, K₂O, Sc, Th, Ba, Zr, Rb, Ni, V. REE diagrams show slight light REEs (rare earth elements; LREEs) compared to heavy REEs (HREEs), and positive La and Eu anomalies. The lithological associations, as well as the very high (Eu/Eu^*)_SN ratios> 1.8 shown by the BIFs, suggest that they are related to Algoma-type BIFs. The positive correlations between Zr and TiO₂, Al₂O₃, Hf suggest that the contamination comes mainly from felsic rocks, while the absence of correlations between MgO and Cr, Ni argues for negligeable contributions from mafic sources. Pr/Pr^* vs. Ce/Ce^* diagram indicates that the Congolese BIFs were formed in basins with redox heterogeneity, which varies from suboxic to anoxic and from oxic to anoxic conditions. They were formed through hydrothermal vents in the seawater, with relatively low proportions of detrital inputs derived from igneous sources through continental weathering. Some Congolese BIFs show high contents in Cr, Ni and Cu, which suggest that iron (Fe) and silicon (Si) have been leached through hydrothermal processes associated with submarine volcanism. We discussed their tectonic setting and depositional environment and proposed that they were deposited in extensional back-arc basins, which also recorded hydrothermal vent fluids.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2021.04a
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• pp.15-15
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• 2021

Seed coat color and seed weight are among the key agronomical traits that determine the nutritional quality of soybean seeds. This study aimed to evaluate the contents of total protein, total oil and five prominent fatty acids in seeds of 49 soybean varieties recently cultivated in Korea, and assess the influences of seed coat color and seed weight on each. Total protein and total oil contents were in the ranges of 36.28-44.19% and 13.45-19.20%, respectively. Likewise, individual fatty acid contents were in the ranges of 9.90-12.55, 2.45-4.00, 14.97-38.74, 43.22-60.26, and 5.37-12.33% for palmitic, stearic, oleic, linoleic, and linolenic acids, respectively. Our results found significant variations of protein, oil and fatty acid contents between the soybean varieties. Moreover, both seed coat color and seed weight significantly affected total oil and fatty acid contents. Total protein content, however, was not significantly affected by any factor. Among colored soybeans, pale-yellow soybeans were characterized by a high level of oleic acid (30.70%) and low levels of stearic (2.72%), linoleic (49.30%) and linolenic (6.44%) acids, each being significantly different from the rest of colored soybeans (p < 0.05). On the other hand, small soybeans were characterized by high levels of all individual fatty acids except oleic acid. The level of oleic acid was significantly high in large seeds. Cluster analysis grouped the soybeans into two classes with notable content differences. Principal component analysis also revealed fatty acids as the prime factors for the variability observed among the soybean varieties. As expected, total oil and total protein contents showed a negative association with each other (r = -0.714, p < 0.0001). Besides, oleic acid and linoleic acid showed a tradeoff relationship (r = -0.936, p < 0.0001) which was reflected with respect to both seed coat color and seed weight. In general, the results of this study shade light on the significance of seed coat color and seed weight to distinguish soybeans in terms of protein, oil and fatty acid contents. Moreover, the soybean varieties with distinct characteristics and nutritional contents identified in this study could be important genetic resources for consumption and cultivar development.

• Journal of Cadastre & Land InformatiX
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• v.53 no.2
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• pp.53-66
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• 2023

Recently, there has been a significant interest in the development of autonomous driving simulation environment based on digital twin. In the development of such digital twin-based simulation environment, many researches has been conducted not only performance and functionality validation of autonomous driving, but also generation of virtual training data for deep learning. However, such digital twin-based autonomous driving simulation system has the problem of requiring a significant amount of time and cost for the system development and the data construction. Therefore, in this research, we aim to propose a method for rapidly designing and implementing a digital twin-based autonomous driving simulation system, using only the existing 3D models and high-definition map. Specifically, we propose a method for integrating 3D model of FBX and NGII HD Map for the Busan EDC area into CARLA, and a method for adding and modifying CARLA functions. The results of this research show that it is possible to rapidly design and implement the simulation system at a low cost by using the existing 3D models and NGII HD map. Also, the results show that our system can support various functions such as simulation scenario configuration, user-defined driving, and real-time simulation of traffic light states. We expect that usability of the system will be significantly improved when it is applied to broader geographical area in the future.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.34 no.1
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• pp.8-15
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• 2024

The CaF₂ single crystal has notable characteristics such as a large band gap (12 eV), excellent transparency over a wide wavelength range, low refractive index and dispersion. Due to these outstanding properties, CaF₂ single crystal has considered as a promising material for short-wavelength light sources in recent lithography processes. However, there is an inherent birefringence of the material at 157 nm and the resulting aberration can be compensated for through the combination of the (100) plane and the (111) plane. Therefore, it is necessary to investigate the characteristics according to the plane. In this study, we analyzed crystallinity, optical properties of commercial CaF₂ single crystal wafers grown by the Czochralski method. In particular, through chemical etching under various conditions, it was confirmed that the shape of etch pits appears differently depending on the plane and the shape and array of specific etch pits affected by dislocations and defects were examined.

• Journal of the Korean Geosynthetics Society
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• v.23 no.2
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• pp.43-52
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• 2024

Recent abnormal climate conditions have increased the risk of slope collapses, which frequently result in significant loss of life and property due to the absence of early prediction and warning dissemination. In this paper, we develop a slope condition analysis system using IoT sensors and AI-based camera to assess the condition of slopes. To develop the system, we conducted hardware and firmware design for measurement sensors considering the ground conditions of slopes, designed AI-based image analysis algorithms, and developed prediction and warning solutions and systems. We aimed to minimize errors in sensor data through the integration of IoT sensor data and AI camera image analysis, ultimately enhancing the reliability of the data. Additionally, we evaluated the accuracy (reliability) by applying it to actual slopes. As a result, sensor measurement errors were maintained within 0.1°, and the data transmission rate exceeded 95%. Moreover, the AI-based image analysis system demonstrated nighttime partial recognition rates of over 99%, indicating excellent performance even in low-light conditions. Through this research, it is anticipated that the analysis of slope conditions and smart maintenance management in various fields of Social Overhead Capital (SOC) facilities can be applied.

• The Journal of the Acoustical Society of Korea
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• v.28 no.2
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• pp.96-106
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• 2009

In this paper, correlation between the headphone's acoustical characteristics and the subjective preferences is analyzed, and a possibility of predicting the subjective preferences using the acoustical characteristics is investigated, The headphone's acoustical characteristics include the total harmonic distortions, the variation of the frequency response which were measured by separate channel and the inter-aural correlation coefficients, Those characteristics were measured in a noise-free anechoic chamber, using a head and torso simulator, The subjective preferences were scored in terms of loudness, clearness, spaciousness, fullness and overall impression, In the subjective listening test, 12 subjects were participated who have plentiful listening experiences, The programs include 5 kinds of musics; korean popular song, pop song, light music, male-voice and classic, The 8 models of the headphones were employed, including 4 closed-type circumaural headphones, 2 open-type supraaural headphones and 2 intra-concha headphones, A significant test was carred on the results from the subjective test, using a two-way ANOVA test, The correlation coefficients between the acoustical parameters and the subjective preferences were computed, Experimental results showed that the variation of the magnitude of frequency response measured from a right channel revealed higher correlation with the subjective preferences. Whereas the inter-aural correlation coefficients have very low correlation coefficients.

• Information Systems Review
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• v.19 no.3
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• pp.127-154
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• 2017

This study aims to identify various service innovation patterns in the service industry and understand the main differences among them. We attempt to create a new typology of service innovation by analyzing its patterns based on the four major dimensions of service innovation (i.e., service concept, service delivery, customer interaction, and technology). We then investigate whether firms pursuing different service innovation patterns significantly differ from one another in terms of their performance (high and low performance). Based on empirical data collected from 198 Korean firms in the knowledge-intensive business service sector, four major clusters composed of different service innovation dimensions are identified. These four clusters can be interpreted as specific service innovation patterns, including "technology based high customer interaction," "high technology based high service delivery," "service delivery and high customer interaction-integrated," and "strongly balanced" innovators. High firm performance does not depend on the individual service innovation dimension but on the specific configurations of such service dimensions. Customer interaction also has an important role in achieving innovation success and improving firm performance, while technology has a key role in enhancing firm performance. This study sheds new light on service innovation research by developing a new typology of service innovation, identifying four major clusters as service innovation patterns, and exploring the relationship between service innovation patterns and firm performance.

• The Korean Journal of Coaching Psychology
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• v.7 no.3
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• pp.109-125
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• 2023

This study aimed to investigate the influence of power distance on organizational outcome variables from the perspective of employee-organizational fit. Through cluster analysis, we sought to identify the subgroups that exist based on the combination of employees' power distance and organizational power distance. Additionally, we examined whether differences exist among these subgroups in terms of positive and negative organizational outcomes. A total of 398 participants were included in the study, and three distinct clusters were identified through cluster analysis. Cluster 1 comprised individuals with low power distance among employees and high power distance within the organization(LH), Cluster 2 consisted of individuals with high power distance in both employees and organizations(HH), and Cluster 3 represented individuals with significantly higher power distance among employees compared to their respective organizations(HL). When analyzing the differences between these three subgroups in relation to organizational outcomes, no significant differences were found in positive work affects. Overall, the LH group exhibited the most favorable organizational results, while the HH group displayed the most negative organizational outcomes. In light of these findings, we discussed the academic and practical implications of this study, as well as its limitations.

• Journal of the Korean Applied Science and Technology
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• v.41 no.2
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• pp.159-171
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• 2024

This study confirmed the antioxidant activity and antimicrobial efficacy and formulation stability for the effectiveness experiment of Rumex crispus. L root extract. For antioxidant activity, DPPH radical scavenging, FRAP activity, ABTS+ radical scavenging, and SOD-like activity were performed. Antimicrobial activity was evaluated for Staphylococcus epidermidis, Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and Candida albicans strains. In addition, skin containing Rumex crispus. L root extract is checked over time for pH, temperature, and daylight for 21 days. As a result of antioxidant evaluation, it was confirmed that the activity increased in a concentration-dependent manner at a concentration of 0.0625-1 mg/mL. The clear zones of each bacterium at 100mg/mL concentrations were 10.45±0.34, 9.77±0.59, 9.92±0.22, and 10.08±0.12, which were superior to the control group Methyl paraben, and the antibacterial power of S. aureus and E. coli was confirmed at 100mg/mL concentration for MIC. There was little change in absorbance when the pH of the skin was 4.0, 6.0, and 7.0 and At 4℃, 25℃, and 40℃, it was discolored as the temperature increased. It was also observed that discoloration occurred when exposed to daylight. This is presumed to be able to prevent discoloration when it is shielded and stored at low temperatures. When the results of this study are summarized, Rumex crispus. L root extract is considered to have high value in use as a cosmetic raw material that can expect antioxidant and antibacterial activities.

• The Journal of the Acoustical Society of Korea
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• v.43 no.1
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• pp.60-71
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• 2024

The present study aims to investigate the level difference of floor impact noises of composite floor structure using EVA resilient materials. In order to this, four different types of resilient materials were designed combining PET, PP sheet and EVA mount including Flat type, Deck type, Cavity type and Mount type. Totally 9 different samples were made for acoustic measurements which were carried out twice with bang-machine and impact ball as the heavy-weight floor impact noise sources. All the floor impact noise measurements were undertaken at the authentication institution. As a result, concerning Flat and Cavity types, it was found that 2 dB ~ 5 dB of heavy-weight floor impact noise was reduced supplementally when PET was added, while floor impact noise larger than 50 dB was acquired when single resilient material was used. Especially, most high performance was obtained for Mount type with 1st grade of light-weight floor impact noise and 2nd grade of heavy-weight floor impact noise. This is because of material property with low dense PET sound absorption materials which fill all around EVA mounts. Also, it was considered that this results are due to the sound impact absorption by the both EVA mounts and the air cavity between EVA mount and PP sheet. Also, it was found that at least 36 EVA mounts per 1m2 area of resilient panel make more noise reduction of heavy-weight floor impact noises.