• Journal of the Korean earth science society
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• v.42 no.2
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• pp.164-174
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• 2021

The study examines the shearing and crushing characteristics of land-derived subaqueous granular materials in a gravel-bed river. A series of large-sized ring shear tests were performed to examine the effect of shear time and shear velocity on the shear stress characteristics of aquarium gravels with a 6-mm mean grain size. Three different shear velocities (i.e., 0.01, 0.1, and 1 mm/sec) were applied to measure the shear stress under the drained (long-term shearing) and undrained (short-term shearing) conditions. Different initial shear velocities, i.e., 0.01→0.1→1 mm/sec and 0.1→0.01→1 mm/sec, were considered in this study. The test results show that the grain crushing effect is significant regardless of drainage conditions. The shear stress of coarse-grained materials is influenced by initial shear velocities, regardless of the drainage conditions. In particular, particle breakage increases as grain size increases. The shearing time and initial shear velocity are the primary influencing factors determining the shear stress of gravels. The granular materials may be broken easily into particles through frictional resistance, such as abrasion, interlocking and fracture due to the particle-particle interaction, resulting in the high mobility of granular materials in a subaqueous environment.

• Journal of the Society of Disaster Information
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• v.20 no.2
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• pp.270-283
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• 2024

Purpose: Considering the rising frequency of earthquakes in Korea, it is crucial to revise the rainfall thresholds for landslide triggering following earthquake events. This study was conducted to provide scientific justification and preliminary data for adjusting rainfall thresholds for landslide early warnings after earthquakes through soil physical experiments. Method: The study analyzed the change in soil shear strength by direct shear tests on disturbed and undisturbed samples collected from cut slopes. Also, The study analyzed the soil strength parameters of remolded soil samples subjected to drying and wetting conditions, focusing on the relationship between the degree of saturation after submergence and the strength parameters. Result: Compaction water content variation in direct shear tests showed that higher water content and saturation in disturbed samples led to a significant decrease in cohesion (over 50%) and a reduction in shear resistance angle (1~2°). Additionally, during the ring shear tests, the shear strength was observed to gradually decrease once water was supplied to the shear plane. The maximum shear strength decreased by approximately 65-75%, while the residual shear strength decreased by approximately 53-60%. Conclusion: Seismic activity amplifies landslide risk during subsequent rainfall, necessitating proactive mitigation strategies in earthquake-prone areas. This research is anticipated to provide scientific justification and preliminary data for reducing the rainfall threshold for landslide initiation in earthquake-susceptible regions.

• The Korean Journal of Physiology
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• v.27 no.2
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• pp.199-207
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• 1993

To study the underlying mechanism through which the endothelium-dependent relaxation is inhibited by blocking the $Na^+\;-K^+$ pump, the effects of $Na^+\;-K^+$ pump blockade on the release of EDRF and its relaxing activity were examined, using organ bath study, bioassay technique, and cGMP measurement. Endothelium-dependent relaxation was attenuated by blocking the $Na^+\;-K^+$ pump in the vascular ring with intact endothelium. In bioassay experiment EDRF release was decreased with the blockade of the $Na^+\;-K^+$ pump in the EDRF donor strip. Endothelium-dependent increase of cGMP level was suppressed by inhibiting the $Na^+\;-K^+$ pump in the test strips. The magnitude of relaxation of test strip which was induced by the perfusate that had passed through the EDRF donor strip was decreased with the blockade of the $Na^+\;-K^+$ pump in the test strip. Therefore, it could be suggested that the attenuation of endothelium-dependent relaxation caused by inhibiting $Na^+\;-K^+$ pump activity is due to both the decreased release of EDRF from endothelial cells and the decreased sensitivity of the smooth muscle cells to EDRF.

• Archives of Plastic Surgery
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• v.43 no.3
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• pp.272-277
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• 2016

Background One-per-mil tumescent solution, which contains 0.2% lidocaine with 1:1,000,000 epinephrine, has been reported to be clinically effective for hand surgery under local anesthesia. However, it was lacking in its basic pharmacokinetics profile in regard to the onset of action (OOA) and duration of action (DOA). Methods A randomized, double-blind study was conducted on 12 volunteers who met the inclusion criteria from October to November 2014. All volunteers had their right and left ring finger pulps injected with either one-per-mil solution or 2% lidocaine. Semmes-Weinstein and two-point discrimination tests were used to test sensation. Visual analogue scale was recorded at the time when the finger lost its sensation and when it regained normal sensation to measure the OOA and DOA. The data were then analyzed with a paired t-test and a Wilcoxon signed-rank test. Results The OOA and DOA of 2% plain lidocaine were 1 minute and 99.67 minutes, respectively. Meanwhile, 0.2% lidocaine in a one-per-mil tumescent solution showed an OOA of 5 minutes and a DOA of 186.83 minutes. The OOA of 0.2% lidocaine in a one-per-mil tumescent solution is statistically shorter than 2% plain lidocaine (P=0.04); while its DOA is statistically longer than 2% plain lidocaine (P<0.001). Conclusions The 0.2% lidocaine in a one-per-mil tumescent solution is statistically and clinically superior to 2% plain lidocaine in achieving longer duration of local anesthesia.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.7
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• pp.592-600
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• 2007

Nowadays, researches for replacing material systems for cryotanks by composites have been being performed for the purpose of lightweight launch vehicle. In this paper, a type 3 propellant tank, which is composed of the composite developed for cryogenic use and an aluminum liner, was fabricated and tested considering actual operating environment, that is, cryogenic temperature and pressure. For this aim, liquid nitrogen (LN2) was injected into the fabricated tank and in turn, gaseous nitrogen (GN2) was used for pressurization. During this test procedure, strains and temperatures on the tank surface were measured. The delamination between hoop layer and helical one, was detected during the experiment. Several attempts were followed to investigate the cause analytically and experimentally. Thermo-elastic analysis in consideration of the progressive failure was done to evaluate the failure index. Experimental approach through a LN2 immersion test of composite/aluminum ring specimens suitable for simulating the Type 3 tank structure.

• Journal of ILASS-Korea
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• v.11 no.2
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• pp.59-68
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• 2006

Experimental results of the metal powder production with internal mixing, internal impinging and the atomizer coupled with substrate design are presented in this paper. In a test with internal mixing atomizer, mean powder size was decreased from $37{\mu}m\;to\;23{\mu}m$ for Pb65Sn35 alloy as the gas-to-melt mass ratio was increased from 0.04 to 0.17. The particle size further reduces to $16.01{\mu}m$ as the orifice area is increased to $24mm^2$. The micrograph of the metal powder indicates that very fine and spherical metal powder has been produced by this process. In a test program using the internal impinging atomizers, the mean particle size of the metal powder was decreased from $22{\mu}m\;to\;12{\mu}m$ as the gas-to-melt-mass ratio increased from 0.05 to 0.22. The test results of an atomizer coupled with a substrate indicates that the deposition rate of the molten spray on the substrate is controlled by the diameter of the substrate, the height of the substrate ring and the distance of the substrate from the outlet of the atomizer. This in rum determines the powder production rate of the spraying processes. Experimental results indicate that the deposition rate of the spray forming material decreases as the distance between the substrate and the atomizer increases. For example, the deposition rate decreases from 48% to 19% as the substrate is placed at a distance from 20cm to 40cm. On the other hand, the metal powder production rate and its particle size increases as the subsrate is placed far away from the atomizer. The production of metal powder with mean particle size as low as $3.13{\mu}m$ has been achieved, a level which is not achievable by the conventional gas atomization processes.

• Aerospace Engineering and Technology
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• v.3 no.2
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• pp.81-90
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• 2004

This paper describes the results of combustion performance test of fuel-rich gas generator(GG) using LOx and kerosene as propellant at off-design conditions. The chamber pressure is thought to be a function of O/F ratio and total propellant mass flow rate. The test shows that the spatial temperature deviation at the exit of gas generator remains within 7.5K and that the average gas temperature at the exit is a function of propellant O/F ratio. The results of firing test of gas generator at off-design conditions, especially the relation between gas temperature and O/F ratio, can provide useful data for the design of future gas generator and for the development of low-O/F ratio reaction analysis code.

• Archives of Plastic Surgery
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• v.33 no.4
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• pp.521-524
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• 2006

Purpose: The history of biometry dates back to ancient Greek. The ideal body ratio from biometry is used as a guideline in many works of art. Biometry is also used as a medical standard to determine normal or abnormal. Since the biometry of face is so complicated, many surgeons tend to regard preoperative evaluation as a bother and substitute medical records with some photographs. We introduce a new method to measure $MRD_1$ and levator function using digital photographs, which becomes widely used lately. Methods: $MRD_1$ can be measured with the primary-gaze-view photo which is magnified by PhotoshopR 7.0.1. The distance from coneal reflex of ring flash to upper eyelid margin is converted to mm-unit using the piece of ruler attached on the patient's face. Levator function can be measured with up-gaze-view photo and down-gaze-view photo which are superimposed on another. The excursion distance of upper eyelid margin (a) and the excursion distance of eyebrow (b) are measured respectively. The levator function can be assessed through subtraction of two values (a-b). This method is simple and precise and can be applied directly to patient without photos. Results: Using magnified digital photos and computer, this method can reduce personal error and instrumental error. Taking some digital photos doesn't take long time, so it can reduce the effort of preoperative evaluation and discomfort of patients. Conclusion: Digital photo-biometry is useful for retrospective study. Especially reducing personal error, it is useful when the number of specimens is huge. New levator function test is much more useful for Asian-specific eyes than Berke's method allowing frontalis muscle compensation.

• Physical Therapy Rehabilitation Science
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• v.9 no.3
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• pp.140-148
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• 2020

Objective: The purpose of this study was to examine the effectiveness of pelvic displacement when self-hamstring muscle stretches were applied to persons with low back pain. Design: Three-group pretest-posttest design. Methods: Forty persons with low back pain participated in this study. Pelvic tilt angle, hamstring flexibility, Quadruple Visual Analogue Scale (QVAS), Fear Avoidance Beliefs Questionnaire (FABQ), Korea version of the Oswestry Disability Index (KODI) and pelvic mobility were measured at pre-post. All participants were divided into either the pevic anterior tilt group (PAT group, n=12), pelvic midrange group (PMR group, n=18), or the pelvic posterior tilt group (PPT group, n=10). Self-stretching was performed using the pilates ring three times a week for a total of four weeks and the post-test was conducted and compared with the pre-test. Results: Hamstring flexibility, QVAS, KODI scores were significantly different compared to before the intervention (p<0.05). The changes in hamstring flexibility of the three groups were significantly different (p<0.05). Changes in KODI and FABQ results of the three groups were not significant. The pelvic posterior tilt range were significantly different in the PMR and PPT groups (p<0.05). The pelvic anterior tilt ranges showed significant differences after stretching in the PPT group (p<0.05). Conclusions: A large amount of change of hamstring flexibility, pelvic mobility of anterior and posterior tilt test in the PPT group was observed. Furthermore, therapists should consider pelvic displacement of the participant when applying intervention, which may, accordingly, have different effectiveness.

• Mycobiology
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• v.45 no.3
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• pp.178-183
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• 2017

Diabetes mellitus is a chronic disorder which affects millions of population worldwide. Global estimates published in 2010 reported the world diabetic prevalence as 6.4%, affecting 285 million adults. Foot ulceration and wound infection are major forms of disabilities arising from diabetic diseases. This study was aimed to develop a natural antimicrobial finishing on medical grade textile that meets American Association of Textiles Chemists and Colorists (AATCC) standard. The textile samples were finished with the ethanolic extract of Penicillium amestolkiae elv609, an endophytic fungus isolated from Orthosiphon stamineus Benth (common name: cat's whiskers). Endophyte is defined as microorganism that reside in the living plant tissue, without causing apparent disease symptom to the host. The antimicrobial efficacy of the ethanolic extract of P. minioluteum was tested on clinical pathogens isolated from diabetic wound. The extract exhibited significant inhibitory activity against 4 bacteria and 1 yeast with the minimal inhibitory concentration ranged from 6.25 to 12.5 mg/mL. The results indicate different susceptibility levels of the test microorganism to the ethanolic extract. However, the killing activity of the extract was concentration-dependent. The finished medical textile showed excellent antimicrobial efficacy on AATCC test assays. All the microbial cultures treated with the textile sample displayed a growth reduction of 99.9% on Hoheinstein Challenge Test. The wash durability of the finished textile was found good even after 50 washes with commercial detergent. Besides, the gas chromatography mass spectrometry analysis showed that 6-octadecenoic acid and diethyl phthalate were the main bioactive constituents of the extract. In conclusion, the developed medical textile showed good antimicrobial efficacy on laboratory tests. This work can be extended to in vivo trials for developing healthcare textile products for antimicrobial applications.