• Journal of the Korean Geotechnical Society
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• v.38 no.10
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• pp.49-60
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• 2022

Underground urbanization appears to be a promising solution in response to the shortage of construction sites in the above-ground space. In this context, an accurate evaluation of a construction site ensures the long-term performance of geosystems. This study characterizes potential sites for complex plants built in underground space using geophysical methods (i.e., seismic refraction exploration and electrical resistivity survey) and in situ tests (i.e., standard penetration tests (SPTs) and downhole tests). SPTs are conducted in nine boreholes BH-1-BH-9 to estimate the groundwater level and vertical distribution of geological structures. The seismic refraction method enables us to obtain the elastic wave velocity and thickness of each soil layer for each cross-sectional area. An electrical resistivity survey conducted using the dipole array method provides the electrical resistivity profiles of the cross-sectional area. Data obtained using geophysical techniques are used to assess the classification of the soil layer and bedrock, particularly the fracture zone. This study suggests that geotechnical information using in situ tests and geophysical methods are useful references to design an underground complex plant construction.

• Journal of the Korean GEO-environmental Society
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• v.23 no.6
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• pp.5-17
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• 2022

The performance of the relief wells installed for the purpose of controlling seepage of the dam embankment is affected by various parameters such as diameter, spacing, penetration rate, permeability coefficient of the ground, thickness of the foundation layer. Therefore, when the relief wells are adopted for the purpose of reducing seepage pressure, these parameters should be sufficiently reviewed to determine the installation specifications of the relief wells. This study evaluated the effect of the length of the geosynthetics blanket on the performance of the relief wells installed in the downstream part of the dam embankment with blankets in the upstream and downstream part of the dam embankment as countermeasure methods to control seepage of the dam embankment. In the relationship between the length of the upstream and downstream blanket and the discharge, the discharge of the relief wells decreases as the length of the upstream blanket increases, and on the other hand, the discharge of the relief wells decreases as the length of the downstream blanket increases. In the upper and lower blanket length-spacing relationship, as the length of the upstream blanket increases, the spacing of the relief wells increases and as the length of the downstream blanket increases, the spacing of the relief wells decreases. Therefore, when installing the relief wells in parallel with the blanket, it was found that increasing the length of the upstream blanket is more efficient than increasing the length of the downstream blanket in order to minimize the discharge of seepage discharge and to ensure economic feasibility by wider installation of the relief wells.

• Journal of the Korean Wood Science and Technology
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• v.30 no.2
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• pp.87-94
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• 2002

This study was carried out to evaluate bending property on principal domestic species such as sargent cherry(Prunus sargentii), bitter wood(Picrasma quassioides), horn beam(Carpinus laxiflora), cork oak(Quercus variabilis), birch(Betula schmidtii), painted maple(Acer mono), basswood(Tilia amurensis), red pine(Pinus densiflora), pitch pine(Pinus rigtda), royal pawlonia(Paulownia tomentosa) by microwave heating. In this study, radius of curvature(ROC) for bending process was classified by radius of curvature(ROC) of bending plate such as 4 cm, 6 cm, and 10 cm, and thickness of metal-strap(TMS) was 0.6 mm and 0.8 mm. Bending process was successfully operated for 100 percent in bitter wood, horn beam, birch and painted maple. On the other hand, there was a success rate of 58 percent in sargent cherry and 83 percent in cork oak and 29 percent in basswood and 8 percent in royal pawlonia which is the worst bending property. All specimens of basswood and royal pawlonia were broken at 4 cm of ROC. Success rate of bending property was shown 44 percent in red pine and 56 percent in pitch pine. TMS has an effect on only drying speed in drying process than difficulty and facility of bending property. It was considered that the thinner TMS in drying process is the faster in drying speed of bent wood.

• Membrane Journal
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• v.32 no.2
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• pp.116-125
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• 2022

In this experiment, an α-Al₂O₃ ceramic hollow fiber was used as a support, and a hydrogen membrane plated with Pd and Pd-Ag was manufactured through electroless plating. The Pd-Ag membrane was annealed at 500℃ for 10 h to form an alloy of Pd and Ag. It was confirmed that it became a Pd-Ag alloy through EDS (Energy Dispersive X-ray Spectroscopy) analysis. Also, the thickness of the Pd, Pd-Ag plating layer was measured to be about 8.98 and 9.29 ㎛ through SEM (Scanning Electron Microscope) analysis respectively. Hydrogen permeation experiment was performed using the H₂ gas and mixed gas (H₂ and N₂) in the range of 350~450℃ and 1-4 bar using the prepared hydrogen membrane. Under the H₂ gas condition, the Pd and Pd-Ag membrane has a flux of up to 21.85 and 13.76 mL/cm²·min and also separation factors of 1216 and 361 were obtained in the mixed gas at 450℃ and 4 bar conditions respectively.

• Journal of Animal Science and Technology
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• v.64 no.2
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• pp.353-364
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• 2022

The present study aimed to assess the feasibility of increasing the slaughter weight (SW) of non-lean finishing pigs to improve their meat quality. A total of 36 (Landrace × Yorkshire) × Duroc gilts and barrows were slaughtered at 115 (Av), 125 (Hi), or 135 (XHi) kg, followed by physicochemical analyses and sensory evaluation on their longissimus dorsi (LD) and Semimembranosus (SM) muscles. Backfat thickness was greater (p < 0.05) for the XHi (31.2 mm) and Hi (29.3 mm) groups than for Av (25.0 mm). Dressing percentage and yield of the belly per whole carcass were also slightly greater for XHi and Hi vs. Av. The intramuscular fat (IMF) content of SM was greater for XHi (2.64%) than for Av (1.83%) and Hi (2.04%) and also was correlated with SW (r = 0.55). The pH value, lightness, redness, drip loss, shear force, and moisture and protein contents of LD and SM, as well as IMF content of LD, were unaffected by SW. Percentages of 14:0, 16:0, and total saturated fatty acids (FA) were less for Hi and XHi vs. Av in SM, those of total unsaturated FA, 18:2, 20:4, and n-6 being opposite; FA composition of LM was not influenced by SW except for a reduced 18:0 percentage for XHi vs. Av. The sensory score was less for XHi vs. Av for odor in fresh LD and SM, and less for Hi and XHi vs. Av for aroma in fresh LM; scores for color, drip loss, marbling, and acceptability were unaffected by SW. As for cooked muscles, none of the scores for color, aroma, flavor, juiciness, tenderness, and acceptability was affected by SW, except for a greater LD color score for Hi and XHi vs. Av. Collectively, the results suggested that the increased yield of the carcass and belly due to increased SW is outbalanced negatively by excessive backfat deposition in production efficiency, whereas the SW increase exerts little influence on overall sensory quality of fresh or cooked meat. Production of non-lean market pigs overweighing 115 kg therefore will be uneconomical unless consumers pay a substantial premium for the over-fattened pork.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.1
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• pp.71-77
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• 2023

This study aims to investigate the structural performance of hollow-core slab (HCS) memebers with 400 mm thickness. To this end, a total of four HCS specimens were fabricated based on the individual mold method to provide shear reinforcement, unlike the extrusion method. The key variables were chosen as the presence of topping concrete, core-filling concrete, and shear reinforcements. The crack patterns and load-displacement responses of the test specimens were analyzed in detail. Test results showed that inclined shear cracking occurred all the specimens, and that the specimen with shear reinforcement on the web of HCS unit had higher strength and ductility than the specimen without shear reinforcement. In particular, shear reinforcements placed on the web of HCS unit effectively resisted not only to vertical shear force but also to horizontal shear force between the interface of HCS unit and topping concrete. In addition, it was discovered that the method in which shear reinforcements are placed on the web of HCS unit is more effective in improving structural performance than core-filling method.

• Earthquakes and Structures
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• v.23 no.5
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• pp.445-462
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• 2022

To investigate and evaluate the seismic damage behaviors of steel reinforced recycled concrete (SRRC) filled circular steel tube composite columns, in this study, the cyclic loading tests of 11 composite columns was carried out by using the load-displacement joint control method. The seismic damage process, hysteretic curves and performance indexes of composite columns were observed and obtained. The effects of replacement rates of recycled coarse aggregate (RCA), diameter thickness ratio, axial compression ratio, profile steel ratio and section form of profile steel on the seismic damage behaviors of composite columns were also analyzed in detail. The results show that the failure model of columns is a typical bending failure under the combined action of horizontal loads and vertical loads, and the columns have good energy dissipation capacity and ductility. In addition, the replacement rates of RCA have a certain adverse effect on the seismic bearing capacity, energy consumption and ductility of columns. The seismic damage characteristics of composite columns are revealed according to the failure modes and hysteretic curves. A modified Park-Ang seismic damage model based on the maximum displacement and cumulative energy consumption was proposed, which can consider the adverse effect of RAC on the seismic damage of columns. On this basis, the performance levels of composite columns are divided into five categories, The interlayer displacement angle and damage index are used as the damage quantitative indicators of composite columns, and the displacement angle limits of composite columns at different performance levels under 80% assurance rate are calculated as 1/105, 1/85, 1/65, 1/28, and 1/25 respectively. On this basis, the damage index limits corresponding to each performance level are calculated as 0.045, 0.1, 0.48, 0.8, and 1.0 respectively. Finally, the corresponding relations among the performance levels, damage degrees, interlayer displacement angles and damage indexes of composite columns are established. The conclusions can provide reference for the seismic design of SRRC filled circular steel tube composite columns, it fills the vacancy in the research on seismic damage of steel reinforced recycled concrete (SRRC) filled circular steel tube composite columns.

• Journal of Periodontal and Implant Science
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• v.53 no.4
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• pp.306-317
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• 2023

Purpose: Biphasic calcium phosphate (BCP), a widely used biomaterial for bone regeneration, contains synthetic hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP), the ratio of which can be adjusted to modulate the rate of degradation. The aim of this study was to evaluate the clinical and radiographic benefits of reconstructing peri-implant bone defects with a newly developed BCP consisting of 60% β-TCP and 40% HA compared to demineralized bovine bone mineral (DBBM). Methods: This prospective, multicenter, parallel, single-blind randomized controlled trial was conducted at the periodontology departments of 3 different dental hospitals. Changes in clinical (defect width and height) and radiographic (augmented horizontal bone thickness) parameters were measured between implant surgery with guided bone regeneration (GBR) and re-entry surgery. Postoperative discomfort (severity and duration of pain and swelling) and early soft-tissue wound healing (dehiscence and inflammation) were also assessed. Data were compared between the BCP (test) and DBBM (control) groups using the independent t-test and the χ² test. Results: Of the 53 cases included, 27 were in the test group and 26 were in the control group. After a healing period of 18 weeks, the full and mean resolution of buccal dehiscence defects were 59.3% (n=16) and 71.3% in the test group and 42.3% (n=11) and 57.9% in the control group, respectively. There were no significant differences between the groups in terms of the change in mean horizontal bone augmentation (test group: -0.50±0.66 mm vs. control groups: -0.66±0.83 mm, P=0.133), postoperative discomfort, or early wound healing. No adverse or fatal complications occurred in either group. Conclusions: The GBR procedure with the newly developed BCP showed favorable clinical, radiographic, postoperative discomfort-related, and early wound healing outcomes for peri-implant dehiscence defects that were similar to those for DBBM.

• Journal of the Korean Geotechnical Society
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• v.25 no.1
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• pp.5-19
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• 2009

Most of earthquake-induced geotechnical hazards have been caused by the site effects relating to the amplification of ground motion, which is strongly influenced by the local geologic conditions such as soil thickness or bedrock depth and soil stiffness. In this study, an integrated GIS-based information system for geotechnical data, called geotechnical information system (GTIS), was constructed to establish a regional counterplan against earthquake-induced hazards at an urban area of Daejeon, which is represented as a hub of research and development in Korea. To build the GTIS for the area concerned, pre-existing geotechnical data collections were performed across the extended area including the study area and site visits were additionally carried out to acquire surface geo-knowledge data. For practical application of the GTIS used to estimate the site effects at the area concerned, seismic zoning map of the site period was created and presented as regional synthetic strategy for earthquake-induced hazards prediction. In addition, seismic zonation for site classification according to the spatial distribution of the site period was also performed to determine the site amplification coefficients for seismic design and seismic performance evaluation at any site in the study area. Based on this case study on seismic zonations in Daejeon, it was verified that the GIS-based GTIS was very useful for the regional prediction of seismic hazards and also the decision support for seismic hazard mitigation.

• Journal of the Korean Burn Society
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• v.22 no.2
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• pp.30-33
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• 2019

Purpose: Wound healing and scar management of donor site after skin graft should not be overlooked. Patients continue to complain of dryness, itching sensation. Such discomfort can cause irritation to the patients and lead to delayed healing or secondary infection. Thus, the author predicted Eucalyptus Oil, which acts on Transient Receptor Potential Melastatin 8 would be effective in regulating scar by reducing itching sensation in donor site when combining conventional silicone materials. Methods: The study was performed on 30 patients who underwent split thickness skin graft with lateral thigh as donor site between January 2017 and August 2018. First, primary evaluation of fully epithelized donor site scar three weeks after surgery was conducted. Control group (n=15) applied silicone gel (Kelo-cote, USA) solely two times a day. study group (n=15) applied Eucalyptus oil, combined with silicone gel. After 3 months of follow up, donor scar was evaluated using Vancouver scar scale and VAS scores of subjective patient reports regarding pain and itching sensation. Results: It was confirmed that both groups showed stable scar improvement comparing scar quality for 3 months. After 3 months, scar quality in study group showed superiority in pigmentation, pliability and pruritus compared to control group. Conclusion: Application of Eucalyptus Oil combined with conventional silicone gel is favorable to scar management and may give additional benefit of alleviating pruritis symptoms.