• Geomechanics and Engineering
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• v.36 no.6
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• pp.589-599
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• 2024

Dispersion occurs when clay soil disperses under specific conditions and is rapidly washed away. While there are numerous methods for rectifying it, they are neither cost nor time-effective. The current study used metakaolin and zeolite to improve heavily dispersive clay soil either separately or in combination at 0%, 2%, 4%, 6%, and 8% of the soil weight. After 7 days of curing, the samples were tested to determine the extent of change in the dispersion potential, as well as the improvement of the geotechnical properties of the soil. The results indicated that the addition of 2% zeolite with 6% to 8% metakaolin decreased the dispersion potential considerably. Double hydrometry test findings revealed that the dispersion potential decreased by almost 70% and entered the non-dispersive group; the crumb test also revealed this. Atterberg limits testing indicated a decrease in the plasticity index which reduced the flexibility of the samples. The greatest decrease in PI (67.5%) was achieved with the addition of 8% zeolite plus 8% metakaolin to the soil. The results of density tests revealed that a decrease in the optimal moisture content increased the maximum dry density of soil. This increase in density was a response to the high reactivity of metakaolin with calcium hydroxide and the formation of calcium hydroxide hydrate gel. This eventually caused an increase in the unconfined compressive strength, the greatest increase in strength of about 1.8-fold was observed with a combination of 2% zeolite and 6% metakaolin compared to the unmodified sample.

• The Journal of Korean Physical Therapy
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• v.35 no.6
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• pp.167-176
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• 2023

Purpose: Due to the high incidence of shoulder injuries, including shoulder impingement syndrome (SIS), among CrossFit practitioners due to frequent overhead movements, serratus anterior exercises are considered crucial for scapular stabilization in both intervention and prevention. Objective: The objective of this study is to compare the muscle activity and ratios of scapular stabilizing and shoulder girdle muscles between individuals with and without SIS during serratus punch and wall slide exercises, both targeting the serratus anterior muscle, in CrossFit training practitioners. Methods: Surface electromyography was used to compare the muscle activity and activity ratio of scapular stabilizing muscles and shoulder muscles during serratus punch and wall slide exercises in two groups of 20 CrossFit practitioners: ten with SIS and ten without symptoms. Results: The group with SIS showed higher activation of the pectoralis major, upper trapezius, and a higher pectoralis major/serratus anterior and upper trapezius/serratus anterior muscle activation ratio during the serratus punch exercise compared to the group without SIS. Similarly, during the wall slide exercise, the group with SIS exhibited higher activation of the upper trapezius and a higher upper trapezius/serratus anterior muscle activation ratio compared to the group without SIS. However, no significant difference in serratus anterior muscle activation was observed between the two groups. Conclusions: This study highlights the higher activation of the pectoralis major and upper trapezius muscles in CrossFit practitioners with SIS during the serratus anterior exercise, suggesting the importance of minimizing the overactivation of these muscles to prevent impingement syndrome in this population.

• Clinical and Experimental Reproductive Medicine
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• v.50 no.4
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• pp.244-252
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• 2023

Objective: We evaluated the efficacy of the newly developed optimized in vitro culture (OIVC) dish for cultivating preimplantation mouse embryos. This dish minimizes the need for mineral oil and incorporates microwells, providing a stable culture environment and enabling independent monitoring of individual embryos. Methods: Mouse pronuclear (PN) zygotes and two-cell-stage embryos were collected at 18 and 46 hours after human chorionic gonadotropin injection, respectively. These were cultured for 120 hours using potassium simplex optimized medium (KSOM) to reach the blastocyst stage. The embryos were randomly allocated into three groups, each cultured in one of three dishes: a 60-mm culture dish, a microdrop dish, and an OIVC dish that we developed. Results: The OIVC dish effectively maintained the osmolarity of the KSOM culture medium over a 5-day period using only 2 mL of mineral oil. This contrasts with the significant osmolarity increase observed in the 60-mm culture dish. Additionally, the OIVC dish exhibited higher blastulation rates from two-cell embryos (100%) relative to the other dish types. Moreover, blastocysts derived from both PN zygotes and two-cell embryos in the OIVC dish group demonstrated significantly elevated mean cell numbers. Conclusion: Use of the OIVC dish markedly increased the number of cells in blastocysts derived from the in vitro culture of preimplantation mouse embryos. The capacity of this dish to maintain medium osmolarity with minimal mineral oil usage represents a breakthrough that may advance embryo culture techniques for various mammals, including human in vitro fertilization and embryo transfer programs.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.8
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• pp.895-903
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• 2007

As for the increasing demanding on the development of direct-ecological landfill monitoring methods, it is needed for critically defining the condition of landfills and their influence on the environment, quantifying the amount of enzymes and bacteria mainly concerned with biochemical reaction in the landfills. This study was thus conducted to understand the fates of contaminants in association with groundwater quality parameters. For the study, groundwater was seasonally sampled from four closed unsanitary landfills(i.e. Cheonan(C), Wonju(W), Nonsan(N), Pyeongtaek(P) sites) in which microbial diversity was simultaneously obtained by 16S rDNA methods. Subsequently, a number of primer sets were prepared for quantifying the specific gene of representative bacteria and the gene of encoding enzymes dominantly found in the landfills. The relationship between water quality parameters and gene quantification were compared based on correlation factors. Correlation between DSR(Sulfate reduction bacteria) gene and BOD(Biochemical Oxygen Demand) was greater than 0.8 while NSR(Nitrification bacteria-Nitrospira sp.) gene and nitrate were related more than 0.9. A stabilization indicator(BOD/COD) and MTOT(Methane Oxidation bacteria), MCR(Methyl coenzyme M reductase), Dde(Dechloromonas denitrificans) genes were correlated over 0.8, but ferric iron and Fli(Ferribacterium limineticm) gene were at the lowest of 0.7. For MTOT, it was at the highest related at 100% over BOD/COD. In addition, anaerobic genes(i.e., nirS-Nitrite reductase, MCR. Dde, DSR) and DO were also related more than 0.8, which showing anaerobic reactions generally dependant upon DO. As demonstrated in the study, molecular biological investigation and water quality parameters are highly co-linked, so that quantitative real-time PCR could be cooperatively used for assessing landfill stabilization in association with the conventional monitoring parameters.

• Economic and Environmental Geology
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• v.53 no.4
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• pp.347-362
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• 2020

Iron (hydro)oxides in aqueous environments are primarily formed due to mining activities, and they are known to be typical colloidal particles disturbing surrounding environments. Among them, hematites are widespread in surface environments, and their behavior is controlled by diverse factors in aqueous environments. This study was conducted to elucidate the effect of environmental factors, such as ionic composition and strength, pH, and natural organic matter (NOM) on the behavior of colloidal hematite particles. In particular, two analytical methods, such as dynamic light scattering (DLS) and single-particle ICP-MS (spICP-MS), were compared to quantify and characterize the behavior of colloidal hematites. According to the variation of ionic composition and strength, the aggregation/dispersion characteristics of the hematite particles were affected as a result of the change in the thickness of the diffuse double layer as well as the total force of electrostatic repulsion and van der Walls attraction. Besides, the more dispersed the particles were, the farther away the aqueous pH was from their point of zero charge (PZC). The results indicate that the electrostatic and steric (structural) stabilization of the particles was enhanced by the functional groups of the natural organic matter, such as carboxyl and phenolic, as the NOM coated the surface of colloidal hematite particles in aqueous environments. Furthermore, such coating effects seemed to increase with decreasing molar mass of NOM. On the contrary, these stabilization (dispersion) effects of NOM were much more diminished by divalent cations such as Ca²⁺ than monovalent ones (Na⁺), and it could be attributed to the fact that the former acted as bridges much more strongly between the NOM-coated hematite particles than the latter because of the relatively larger ionic potential of the former. Consequently, it was quantitatively confirmed that the behavior of colloidal hematites in aqueous environments was significantly affected by diverse factors, such as ionic composition and strength, pH, and NOM. Among them, the NOM seemed to be the primary and dominant one controlling the behavior of hematite colloids. Meanwhile, the results of the comparative study on DLS and spICPMS suggest that the analyses combining both methods are likely to improve the effectiveness on the quantitative characterization of colloidal behavior in aqueous environments because they showed different strengths: the main advantage of the DLS method is the speed and ease of the operation, while the outstanding merit of the spICP-MS are to consider the shape of particles and the type of aggregation.

• Journal of Yeungnam Medical Science
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• v.14 no.1
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• pp.209-219
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• 1997

Objectives: Anterior approach to achieve arthrodesis of the cervical spine has become a widely accepted and often-used approach since its earliest reports by Bailey and Badgley, Smith and Robinson and Cloward. However, anterior interbody fusion in the presence of the posterior instability may be complicated by the bone graft dislodgement, kyphotic defomity or nonunion. As an attemp to prevent this undesirable complication, additional methods such as skeletal traction, halo appratus or even posterior fusion has been utilized. Therefore, The cervical spine locking plate(CSLP) with the anterior intervertebral body bone grafting provide immediate cervical stabilization and widely successful in achieving fusion. Material and methods: This study analysed 14 patients who underwent a single anterior procedure and application of CSLP for the treatment of the cervical spinal disorder. Eleven patients were disc herniations and three patients were traumatic lesion. The average age of the patient was 47 years and the mean follow up periods was 20 months ranging from 13 to 27 months. Results: Ambulation was started 2nd day after the operation with the aid of the Philadelpia orthoses. Bone union was observed 13 cases on average 12 weeks after operation. The one case was nonunion with plate breakage without clinical symptom. Conclusion: Anterior fusion with CSLP are thought to be a safe and valuable method for treating cervical spine disorder.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.250-254
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• 2002

Intergranular corrosion of austenitic stainless steels is a conventional and momentous problem during welding and high temperature use. One of the major reasons for such intergranular corrosion is so-called sensitization, i.e., chromium depletion due to chromium carbide precipitation at grain boundaries. Conventional methods for preventing sensitization of austenitic stainless steels include reduction of carbon content in the material, stabilization of carbon atoms as non-chromium carbides by the addition of titanium, niobium or zirconium, local solution-heat-treatment by laser beam, etc. These methods, however, are not without drawbacks. Recent grain boundary structure studies have demonstrated that grain boundary phenomena strongly depend on the crystallographic nature and atomic structure of the grain boundary, and that grain boundaries with coincidence site lattices are immune to intergranular corrosion. The concept of "grain boundary design and control", which involves a desirable grain boundary character distribution, has been developed as grain boundary engineering. The feasibility of grain boundary engineering has been demonstrated mainly by thermomechanical treatments. In the present study, a thermomechanical treatment was tried to improve the resistance to the sensitization by grain boundary engineering. A type 304 austenitic stainless steel was pre-strained and heat-treated, and then sensitized, varying the parameters (pre-strain, temperature, time, etc.) during the thermomechanical treatment. The grain boundary character distribution was examined by orientation imaging microscopy. The intergranular corrosion resistance was evaluated by electrochemical potentiokinetic reactivation and ferric sulfate-sulfuric acid tests. The sensitivity to intergranular corrosion was reduced by the thermomechanical treatment and indicated a minimum at a small roll-reduction. The frequency of coincidence-site-lattice boundaries indicated a maximum at a small strain. The ferric sulfate-sulfuric acid test showed much smaller corrosion rate in the thermomechanically-treated specimen than in the base material. An excellent intergranular corrosion resistance was obtained by a small strain annealing at a relatively low temperature for long time. The optimum parameters created a uniform distribution of a high frequency of coincidence site lattice boundaries in the specimen where corrosive random boundaries were isolated. The results suggest that the thermomechanical treatment can introduce low energy segments in the grain boundary network by annealing twins and can arrest the percolation of intergranular corrosion from the surface.

• Physical Therapy Korea
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• v.25 no.1
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• pp.22-30
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• 2018

Background: Improvement of lumbo-pelvic stability can reduce the compensatory action of the quadratus lumborum (QL) and selectively strengthen the gluteus medius (GM) during side-lying hip abduction (SHA). There are abdominal draw-in maneuver (ADIM) and abdominal bracing (AB) as active ways, and pelvic compression belt (PCB) as a passive way to increase of lumbo-pelvic stability. It is necessary to compare how these stabilization methods affect the selective strengthening of the GM. Objects: To investigate the effects of ADIM, AB, and PCB during SHA on the electromyography (EMG) activity of the GM, QL, external oblique (EO) and internal oblique (IO), and the GM/QL EMG activity ratio. Methods: A total of 20 healthy male adults participated in the study. The subjects performed three conditions in side-lying in random order: SHA with ADIM (SHA-ADIM), SHA with AB (SHA-AB), and SHA with PCB (SHA-PCB). To compare the differences among the three conditions, the EMG activities of the GM, QL, EO and IO, and GM/QL EMG activity ratio were analyzed using one-way repeated ANOVA. Results: The EMG activity of the QL was significantly higher in SHA-AB than in SHA-ADIM and SHA-PCB. The GM/QL activity ratio was significantly higher in SHA-PCB than in SHA-ADIM and SHA-AB. In addition, the figure for SHA-ADIM was significantly higher than that for SHA-AB. In the case of the EO, the figure for SHA-AB was significantly higher than corresponding values for the other two conditions. The figure for SHA-ADIM was significantly higher than that for SHA-PCB. The EMG activity of the IO was significantly higher in SHA-AH than in SHA-PCB. Conclusion: It can be suggested that wearing the PCB can more selectively strengthen the GM than to perform ADIM and AB during SHA. In addition, the ADIM can be recommended when there is a need to strengthen abdominal muscles during SHA.

• Journal of Conservation Science
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• v.25 no.1
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• pp.49-60
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• 2009

Outdoor iron artefacts are easily corroded by salts, especially $Cl^-$ion, from environmental pollutants and acid rain because of their location, so that they need conservational treatments such as stabilization. However the conservation of outdoor iron artefacts are limited to be consolidated for the present and there are a few the studies for the desalinization. The general desalinization method is that objects are immersed in reagent such as alkaline corrosion inhibiting solutions targeting on buried iron artefacts, thus they are not available for outdoor iron artefacts. In this study, concerning those difficulties, the different desalting method is experimented that materials soaked in alkaline solutions attach to objects and they are packed by waterproof to avoid evaporation. This paper experiment burial iron artefacts at first in order to fine out an adaptable method for outdoor iron artefacts. The soaking materials are Korean traditional paper, gauze, cotton wipers, spill pads and the desalting regent is NaOH 0.1M. Additionally the exiting desalinization method which is to immerse objects in solution is performed to compare. The analyses are microscopes, SEM-EDS, X-ray diffraction, pH meter and Ion chromatography. The result is that spill pads show the best desalting effect out of other materials similar to immersing desalting method.

• The Journal of the Korea Contents Association
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• v.18 no.11
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• pp.611-622
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• 2018

In this study, I was to investigate the trends in research on walking and positioning in Korea and to compare the results of researches on the Visually Impaired and the Non-disabled. I selected 113 papers in order to know the current status of the study for the visually impaired and to suggest future research directions. This study analyzed the general features (publication year, academic journals, number of authors, keywords, research methods, research types, implementation methods, research support, references) and research themes and contents of domestic research on walking and positioning. As a result, there was no an upward trend in number of publications by the Visually Impaired compared to the Non-disabled. In addition, in the case of the non-disabled, Research topics, types of research, implementation include various attempts of location-related technologies, and system development, improvement, stabilization, and accuracy, whereas in the case of the visually impaired, there were focused on development of systems, portable or attachable devices that reflect the characteristics of the visually impaired. There were not many studies on system improvement. Research support also showed that the non-disabled received various research support. Therefore, I suggested the need to continuously develop and improve the research, to diversify research topics and research types, to expand the research scope, to improvement feasibility for the visually impaired.