• Journal of Korea Water Resources Association
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• v.54 no.8
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• pp.567-576
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• 2021

Climate change threatens the security of domestic water resources in South Korea. To overcome the potential water shortage, various approaches are being studied by alterning the operation of dams or by integrated operation of multiple dams and reservoirs. However, most of the related researches were developed and applied for multi-purpose dams, and few studies were conducted for the hydropower dams. The main purpose of the hydropower dam is to generate electric energy; however, the potential water shortage due to prolonged droughts brings the idea to supply water from the hydropower dam in the basin. To that end, it is required to estimate the water supply ability of the hydropower dams. In this study, we proposed a methodology to classify the hydropower dam into a "storage-type" and "run-of-river type" dam. The proposed approach was demonstrated using the hydropower dams located in North-han River basin. The results of this study are expected to contribute for further analysis of the hydropower dams, such as evaluation of water supply capacity and drought mitigation purpose operation of the hydropower dams.

• Clean Technology
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• v.28 no.1
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• pp.1-8
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• 2022

To confirm the applicability of the water gas shift reaction for the production of high purity hydrogen for petroleum cokes, an unutilized low grade resource, Cu/ZnO/MgO/Al₂O₃ (CZMA), catalyst was prepared using the co-precipitation method. The prepared catalyst was analyzed using BET and H₂-TPR. Catalyst reactivity tests were compared and analyzed in two cases: a single LTS reaction from syngas containing a high concentration of CO, and an LTS reaction immediately after the syngas passed through a HTS reaction without condensation of steam. Reaction characteristics in accordance with steam/CO ratio, flow rate, and temperature were confirmed under both conditions. When the converted low concentration of CO and steam were immediately injected into the LTS, the CO conversion was rather low in most conditions despite the presence of large amounts of steam. In addition, because the influence of the steam/CO ratio, temperature, and flow rate was significant, additional analysis was required to determine the optimal operating conditions. Meanwhile, carbon deposition or activity degradation of the catalyst did not appear under high CO concentration, and high CO conversion was exhibited in most cases. In conclusion, it was confirmed that when the Cu/ZnO/MgO/Al₂O₃ catalyst and the appropriate operating conditions were applied to the syngas composition containing a high concentration of CO, the high concentration of CO could be converted in sufficient amounts into CO₂ by applying a single LTS reaction.

• Korean Journal of Mineralogy and Petrology
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• v.35 no.1
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• pp.75-81
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• 2022

Given that China's resource research, exploration and development and resource economy policies are closely related to Korea's industrial competitiveness in the field of global mineral energy resources, it is important to establish the domestic and overseas resource development strategies. In 2020, China will revise and set standards for mineral resources to ensure efficiency in exploration and development and storage management. China's Ministry of Natural Resources has established the National Mineral Resources Plan (2021-2025), aiming to achieve national goals and strategies, and local governments at all levels are also establishing and implementing regional mineral resources plans. As a result, the supervision and management of geological mineral exploration activities have been strengthened, and the safety of industrial production management in the field of geological mineral exploration and development has been strengthened. China has developed guidelines for high-quality geological exploration, surveying and mapping, improved the level of geological mineral exploration and strengthened the mining supervision and management system. According to China's standardization of mineral resources such as solid mineral resources and petroleum gas mineral resources, a new standard system for resource management will be established in China to improve scientific understanding, rational management and utilization.

• Animal Bioscience
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• v.35 no.7
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• pp.1010-1020
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• 2022

Objective: The experiment was conducted to evaluate the effects of maternal undernutrition during late pregnancy on the expressions of genes involved in growth and development in ovine fetal perirenal brown adipose tissue (BAT). Methods: Eighteen ewes with singleton fetuses were allocated to three groups at day 90 of pregnancy: restricted group 1 (RG1, 0.33 MJ metabolisable energy [ME]/kg body weight [BW]^0.75/d, n = 6), restricted group 2 (RG2, 0.18 MJ ME/kg BW^0.75/d, n = 6), and a control group (CG, ad libitum, 0.67 MJ ME/kg BW^0.75/d, n = 6). The fetuses were removed at day 140 of pregnancy. All data were analyzed by using the analysis of variance procedure. Results: The perirenal fat weight (p = 0.0077) and perirenal fat growth rate (p = 0.0074) were reduced in RG2 compared to CG. In fetal perirenal BAT, the protein level of uncoupling protein 1 (UCP1) (p = 0.0001) was lower in RG1 and RG2 compared with CG and UCP1 mRNA expression (p = 0.0265) was decreased in RG2. The protein level of myogenic factor 5 (Myf5) was also decreased in RG2 (p = 0.0001). In addition, mRNA expressions of CyclinA (p = 0.0109), CyclinB (p = 0.0019), CyclinD (p = 0.0015), cyclin-dependent kinase 1 (CDK1) (p = 0.0001), E2F transcription factor 1 (E2F1) (p = 0.0323), E2F4 (p = 0.0101), and E2F5 (p = 0.0018) were lower in RG1 and RG2. There were decreased protein expression of peroxisome proliferator-activated receptor-γ (PPARγ) (p = 0.0043) and mRNA expression of CCAAT/enhancer-binding protein-α (C/EBPα) (p = 0.0307) in RG2 and decreased PPARγ mRNA expression (p = 0.0008) and C/EBPα protein expression (p = 0.0015) in both RG2 and RG1. Furthermore, mRNA expression of bone morphogenetic protein 4 (BMP4) (p = 0.0083) and BMP7 (p = 0.0330) decreased in RG2 and peroxisome proliferator-activated receptor co-activator-1α (PGC-1α) reduced in RG2 and RG1. Conclusion: Our observations support that repression of regulatory factors promoting differentiation and development results in the inhibition of BAT maturation in fetal perirenal fat during late pregnancy with maternal undernutrition.

• Conservation Science in Museum
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• v.26
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• pp.67-82
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• 2021

Two golden beads (Buyeo 5336) housed at the Buyeo National Museum were discovered in 1993 near the site of an ancient workshop in Neungsan-ri in Buyeo-gun, Chungcheongnam-do Province. These rare examples from the Baekje Kingdom of an application of granulation have maintained their original form intact, and thus serve as important materials for the investigation of production techniques applied. This study analyzed the composition of the golden beads using a portable X-ray fluorescence analyzer, a stereo microscope, and a scanning electron microscope with an energy dispersive X-ray spectrometer. The manufacturing technique was examined through the observation of the micro-shape and the surface condition and by a composition analysis of the joint part. In both beads, a hole was pierced in a hollow body and the bead was decorated with golden wires around the hole and gold granules in other parts. In some areas, golden granules had been attached to the gold plate and golden wires were then placed over the granules. The purity of both the wires and the granules was analyzed as 23.6 - 23.7K. A high copper content was detected in some of the parts where the granules were attached. The findings of a previous reproduction experiment and study of production methods suggest that the beads were made using the copper diffusion technique.

• Journal of Environmental Health Sciences
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• v.48 no.2
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• pp.86-95
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• 2022

Background: As high concentrations of uranium and radon have been detected in some areas in Korea, it is considered necessary to investigate natural radioactive materials in the Gwangju area. Objectives: This study aimed to identify the hydrochemical characteristics of groundwater in Gwangju and investigate the distribution characteristics of uranium and radon, which are naturally radioactive substances. Methods: To determine the uranium and radon concentrations in groundwater according to the geology of the Gwangju area, we measured 62 groundwater wells. A geological distribution map of uranium and radon content was prepared for this study. Results: The groundwater type, defined using a Piper diagram, was mainly Ca-HCO₃. The concentration of uranium in the groundwater ranged from 0 to 29.3 ㎍/L, with a mean of 3.3 ㎍/L and a median of 0.9 ㎍/L. The median concentration of uranium in groundwater was highest in alluvium, granitic gneiss, and biotite granite (classified by geological unit), in that order. The concentration of radon in the groundwater ranged from 4.8 to 313.2 Bq/L, with a mean of 75.6 Bq/L and a median of 59.6 Bq/L. The median concentration of radon in groundwater was highest in biotite granite, alluvium, and granitic gneiss, in that order. As a result of the correlation analysis of groundwater in the study area, there was no significant correlation between uranium and radon. Conclusions: In this study area, uranium was shown to be far below the concentrations allowed by drinking water quality standards, but radon concentrations exceeded drinking water quality monitoring standards in 11% of the samples. It was judged that appropriate measures, such as the installation of radon reduction facilities, will be required after a thorough review of high-concentration radon detection sites of in the research area.

• Animal Bioscience
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• v.35 no.7
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• pp.1069-1079
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• 2022

Objective: The objective of this study was to investigate the effect of 4-month intensive feeding on the meat quality, fatty acid profile, flavor, and growth performance of grazing Hulunbuir sheep (HBS). Methods: The HBS were selected 4-months after birth in a pasture rearing system as the experimental animals (n = 44, female, average body weight 23.8±2.2 kg) then divided equally into pasture-based grazing fattening (PAS) and concentrate-included intensive fattening (CON) groups for another 4-month finishing. When finished fattening, all animals were slaughtered to collect musculus longissimus dorsi subcutaneous adipose tissue and to investigate the influences on meat quality, fatty acid profile, flavor and growth performance. Results: The results showed lambs in CON group got significantly higher live weight, hot carcass weight, and dressing percentage. The CON group had significantly higher value of redness (a^*), lightness (L^*) and water holding capacity (p<0.05), significantly lower value of Warner-Bratzler shear force than the PAS group (p<0.05). The subcutaneous fat from CON group lambs demonstrated a significantly higher content of C18:1 and C18:2 (p<0.05), but lower C14:0 and C16:0, indicating an increased degree of unsaturated fatty acid. The content of 4-methyloctanoic acid, 4-ethyloctanoic acid and 4-methylnonanoic acid had increased 2 to 4 times, representing a more intense odor in the CON group. However, the values were still lower than most sheep breeds reported, indicating the indoor feeding system could not fundamentally deteriorate the excellent meat characteristic of HBS. Conclusion: It was evident that lambs in CON group exhibited a better meat production performance, improved in meat color, texture and healthier fatty acid profile through pasture-weaned concentrate included intensive fattening system, which offers a good alternative regimen for lamb finishing and has a wide prospection in the HBS meat industry.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.2
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• pp.84-91
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• 2022

This study investigated the behavior of out-of-plane skewed moment connections that were designed as IMFs, as per the Korean standards. A total of 14 finite element models were constructed with the consideration of two types (single- and double-sided connections) and four levels of skew angle (0°, 10°, 20°, and 30°). The results indicated that the skewed connections considered in this study met the acceptance criteria for IMFs given by the codes. However, the load-carrying capacities of skewed connections were decreased as the skew angle increased. For the connection with a skew angle of 30°, the peak load was noted to be 13% less and the energy dissipation capacity could be 26% less than that of non-skewed connection. In addition, because of the skewed nature, the stress distribution in the skewed beam flange near the connection was asymmetric and the stresses were concentrated on the beam inner flange. Column twisting induced by the skewed configuration was very small and negligible in the beam and column combination considered in this study.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.2
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• pp.1-8
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• 2022

The corrosion of reinforcement is the main reason for the performance degradation of concrete structures. The pre-rusted parts of rebar in concrete structures are vulnerable to the corrosion, especially if the structure is exposed to wet or chlorinated environments. In this study, effects of different curing solution on corrosion behavior of the pre-rusted rebars in the cement composites were investigated. HCl(3%) and CaCl₂(10%) solution were utilized to accelerate the pre-rust of the rebar, and each pre-rust condition rebar including reference (RE) were placed in mortar cylinder. Three kinds of samples then were cured in CaCl₂ (3%) solution and tap water respectively for 120 days. Electrochemical polarization and half-cell potential measurement were used to monitor the influence of curing water on the corrosion behavior of pre-rusted steel bar in cement composite. The surface morphology and composition of corroded steel bar were analyzed by scanning electron microscope and energy dispersive X-ray diffraction. The results show that the corrosion rates of pre-rusted samples in both curing water are higher than that of non-pre-rusted samples. The corrosion rates of RE, CaCl₂ and HCl pre-rusted samples in salt water were 8.14, 4.48, 13.81 times higher than those in tap water respectively, on the 120th day.

• Animal Bioscience
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• v.35 no.11
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• pp.1698-1710
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• 2022

Objective: Raw potato starch (RPS) is resistant to digestion, escapes absorption, and is metabolized by intestinal microflora in the large intestine and acts as their energy source. In this study, we compared the effect of different concentrations of RPS on the intestinal bacterial community of weaned piglets. Methods: Male weaned piglets (25-days-old, 7.03±0.49 kg) were either fed a corn/soybean-based control diet (CON, n = 6) or two treatment diets supplemented with 5% RPS (RPS5, n = 4) or 10% RPS (RPS10, n = 4) for 20 days and their fecal samples were collected. The day 0 and 20 samples were analyzed using a 16S rRNA gene sequencing technology, followed by total genomic DNA extraction, library construction, and high-throughput sequencing. After statistical analysis, five phyla and 45 genera accounting for over 0.5% of the reads in any of the three groups were further analyzed. Furthermore, short-chain fatty acids (SCFAs) in the day 20 fecal samples were analyzed using gas chromatography. Results: Significant changes were not observed in the bacterial composition at the phylum level even after 20 d post feeding (dpf); however, the abundance of Intestinimonas and Barnesiella decreased in both RPS treatment groups compared to the CON group. Consumption of 5% RPS increased the abundance of Roseburia (p<0.05) and decreased the abundance of Clostridium (p<0.01) and Mediterraneibacter (p< 0.05). In contrast, consumption of 10% RPS increased the abundance of Olsenella (p<0.05) and decreased the abundance of Campylobacter (p<0.05), Kineothrix (p<0.05), Paraprevotella (p<0.05), and Vallitalea (p<0.05). Additionally, acetate (p<0.01), butyrate (p<0.05), valerate (p = 0.01), and total SCFAs (p = 0.01) were upregulated in the RPS5 treatment group Conclusion: Feeding 5% RPS altered bacterial community composition and promoted gut health in weaned piglets. Thus, resistant starch as a feed additive may prevent diarrhea in piglets during weaning.