• Korean Journal of Applied Biomechanics
• /
• v.26 no.4
• /
• pp.369-375
• /
• 2016

Objective: The purpose of this study was to investigate the possibility of injuries and the types of movement related to damage by body parts, and to prepare for prevention of injuries and development of a training program. Method: For this study, the experiment was conducted according to levels of 60 percentages (ST) and 85 percentages (MA) and 10 subjects from the Korean elite national weightlifting team were included. Furthermore, we analyzed joint moment and muscle activation pattern with three-dimensional video analysis. Ground reaction force and EMG analyses were performed to measure the factors related to injuries and motion. Results: Knee reinjuries such as anterior cruciate ligament damage caused by deterioration of the control ability for the forward movement function of the tibia based on the movement of the biceps femoris when the rectus femoris is activated with the powerful last-pull movement. In particular, athletes with previous or current injuries should perceive a careful contiguity of the ratio of the biceps femoris to the rectus femoris. This shows that athletes can exert five times greater force than the injury threshold in contrast to the inversion moment of the ankle, which is actively performed for a powerful last pull motion and is positively considered in terms of intentional motion. It is activated by excessive adduction and internal rotation moment to avoid excessive abduction and external rotation of the knee at lockout motion. It is an injury risk to muscles and ligaments, causing large adduction moment and internal rotation moment at the knee. Adduction moment in the elbow joint increased to higher than the injury threshold at ST (60% level) in the lockout phase. Hence, all athletes are indicated to be at a high risk of injury of the elbow adductor muscle. Lockout motion is similar to the "high five" posture, and repetitive training in this motion increases the likelihood of injuries because of occurrence of strong internal rotation and adduction of the shoulder. Training volume of lockout motion has to be considered when developing a training program. Conclusion: The important factors related to injury at snatch include B/R rate, muscles to activate the adduction moment and internal rotation moment at the elbow joint in the lockout phase, and muscles to activate the internal rotation moment at the shoulder joint in the lockout phase.

• Natural Product Sciences
• /
• v.22 no.2
• /
• pp.93-101
• /
• 2016

For efficient quality control of the Samryeongbaekchul-san decoction, a powerful and accurate an ultra-performance liquid chromatography (UPLC) coupled with electrospray ionization (ESI) tandem mass spectrometry (MS) method was developed for quantitative analysis of the thirteen constituents: allantoin (1), spinosin (2), liquiritin (3), ginsenoside Rg1 (4), liquiritigenin (5), platycodin D2 (6), platycodin D (7), ginsenoside Rb1 (8), glycyrrhizin (9), 6-gingerol (10), atractylenolide III (11), atractylenolide II (12), and atractylenolide I (13). Separation of the compounds 1 - 13 was performed on a UPLC BEH $C_{18}$ column ($2.1{\times}100mm$, $1.7{\mu}m$) at a column temperature of $40^{\circ}C$ with a gradient solvent system of 0.1% (v/v) formic acid aqueous-acetonitrile. The flow rate and injection volume were 0.3 mL/min and $2.0{\mu}L$. Calibration curves of all compounds were showed good linearity with values of the correlation coefficient ${\geq}0.9920$ within the test ranges. The values of limits of detection and quantification for all analytes were 0.04 - 4.53 ng/mL and 0.13 - 13.60 ng/mL. The result of an experiment, compounds 2, 6, 12, and 13 were not detected while compounds 1, 3 - 5, and 7 - 11 were detected with 1,570.42, 5,239.85, 299.35, 318.88, 562.27, 340.87, 12,253.69, 73.80, and $115.01{\mu}g/g$, respectively.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.21 no.1
• /
• pp.8-16
• /
• 2017

Structural integrity of solid rocket depends on the residual reactions between constituents of its composition(post cure, migration etc.), the oxygen(or anti-oxydent) in the free volume and humidity (desiccant) under the perfect sealed condition. Mechanical Properties of composite solid propellant arising from those factors are very complex. Moreover the propulsion are faced with thermal loads from diurnal & seasonal cycle till firing. In this study, the fast evaluation method of long term mechanical properties is suggested based on Thermo-Rheological Simplicity from curing oven to cool-down stage in view point of thermal stabilization. For this subject, endurance tester having temperature control capability are devised. From the results from incremental load and strain, non-linear characteristics are discussed.

• Journal of the Society of Naval Architects of Korea
• /
• v.53 no.6
• /
• pp.494-502
• /
• 2016

The accurate assessment of hull-appendage interaction in the early design stage is important to control the inflow to the propeller plane, which can cause undesirable hydrodynamic effects in terms of cavitation phenomenon. This paper describes a numerical analysis for the flow around a fully appended surface ship model for which KRISO has carried out a model test in the Large Cavitation Tunnel(LCT). This numerical study was performed with the LCT model test in a complementary manner for a good reproduction of the wake distribution of surface ships. A second order accurate finite volume method provided by a commercial computational fluid dynamics(CFD) program was used to solve the governing Reynolds Averaged Navier-Stokes(RANS) equations, where the SST $k-{\omega}$ model was used for turbulence closure. The numerical results were compared to available LCT experimental data for validation. The calculations gave good predictions for the boundary layer profiles on the walls of the empty cavitation tunnel and the wake at the propeller plane of the fully appended hull model in the LCT.

• Journal of the Society of Disaster Information
• /
• v.15 no.2
• /
• pp.214-222
• /
• 2019

Purpose: The purpose of this study is to develop a sprinkler head that can be controlled and initial suppressed by installing it in a rack-type warehouse. Method: Considering the spray radius and spray pattern, various deflectors were designed, and the spray angle, discharge characteristics and protection performance test was conducted, and these results were compared and analyzed. Results: An optimal sprinkler head was developed to protect full load, front side of a commodity with minimum water volume 115L/min. Conclusion: The developed head of K-115 and 1Bar pressure was tested with one tier storage confirming that the fire control is carried out without burning all the loadings. In addition, the vertical distance from the top of the load to the deflector shall be separated by 450mm and installed to allow sufficient discharge to the outer part of the commodity.

• Nuclear Engineering and Technology
• /
• v.51 no.1
• /
• pp.257-262
• /
• 2019

The control of microstructure is critical for the porous fuel particles used for infiltrating actinide nuclides. This study concerns the effect of heating processes on properties and microstructure of the fuel particles. The uniform gel precursor beads were synthesized by a microfluidic sol-gel process and then the porous $CeO_2$ microspheres, as a surrogate for the ceramic nuclear fuel particles, were obtained by heating treatment of the gel precursors. The fabricated $CeO_2$ microspheres have a narrow size distribution and good sphericity due to the feature of microfluidics. The effects of heating processes parameters, such as heating mode and peak temperatures on the properties of microspheres were studied in detail. An optimized heating mode and the peak temperature of $650^{\circ}C$ were selected to produce porous $CeO_2$ microspheres. The optimized heating mode can avoid the appearance of broken or crack microspheres in the heating process, and as-prepared porous microspheres were of suitable pore size distribution and pore volume for loading minor actinide (MA) solution by an infiltration method that is used for fabrication of MA-bearing nuclear fuel beads. After the infiltration process, $1000^{\circ}C$ was selected as the final temperature to improve the compressive strength of microspheres.

• Journal of Drive and Control
• /
• v.18 no.1
• /
• pp.1-8
• /
• 2021

This paper presents research on methods for the reduction of forklifts' noise level for the increased comfort and safety of its operator. A cooling fan with a high air volume flow rate installed in the forklift acts as an important design parameter which efficiently cools the heat exchanger system, helping to transfer internal heat from the engine room to the outdoors with both transmitted and diffracted opening noises. The cooling fan contributes significantly to both the forklift's emitted sound power and the operator room's noise level, thereby necessitating research on the forklift's reduction of acoustic power level and transmission. A noise analysis for various fan models with a biomimetic design based on eagle-wing geometry was conducted. In addition to the acoustic power generation, the aerodynamic performance of the cooling blade is also strongly influenced by the design of airfoil distribution, thereby requiring optimization. The cooling fans were fabricated and installed in the forklift in order to check the efficacy of the forklift engine's cooling, and the final version of the fan was measured for its ability to lower acoustic power level and cool the engine room. This study explains the aerodynamic and acoustic features of the designed fans with the use of BEM analysis and forklift test results.

• Journal of Acupuncture Research
• /
• v.38 no.1
• /
• pp.1-7
• /
• 2021

This review of national and international randomized controlled trials of Salviae miltiorrhizae radix pharmacopuncture for lumbar herniated intervertebral discs was performed to assess its clinical efficacy. There were 5 online databases (PubMed, EMBASE, CNKI, NDSL, OASIS, and RISS) searched on June 1st, 2020. Studies were selected according to the inclusion and exclusion criteria and were reviewed by risk of bias assessment. This review included 14 Chinese studies. The sample sizes ranged from 50 to 100. The numbers of treatments ranged from 20 to 30, with most patients receiving 20 treatments. The longest treatment periods were 10-15 and 15-20 days, of which each accounted for 29% of the studies. The most frequently used evaluation indices were the Japanese Orthopedic Association and the Visual Analog Scale scoring method. The most frequently used acupoints were EX18 and BL25, which accounted for 31% of the total number of acupoints. In 50% of the studies, the pharmacopuncture injection volume was 2 mL. Acupuncture treatment was the most common control group. Eleven studies reported that the intervention group had significantly improved symptoms. However, most of the included studies were of low quality.

• Journal of The Korean Society of Integrative Medicine
• /
• v.10 no.1
• /
• pp.149-155
• /
• 2022

Purpose : This study investigated the effects of wearing a mask and different mask filters on the respiratory function of stroke patients. Methods : A total of 15 stroke patients were selected according to the inclusion and exclusion criteria. The respiratory functions were compared between participants with and without masks and among respiratory functions with three different mask filters. The order of using masks was non-wearing masks, Dental masks, KF80 masks, and KF94 masks; the difference in respiratory volumes among these conditions were measured. For accuracy of the measurement, sufficient education on the respiratory measurement method was provided to the researcher, and the heart rate of the participants was estimated to confirm their stability before the measurements. To ensure accuracy, the subjects were educated on the researchers' respiratory measurement methods. Each measurement was followed by 10 min breathing stability before replacing the next mask. Results : The results of this study showed that the difference in respiratory functions, including forced vital capacity (FVC), forced expiratory volume in the first second (FEV₁), and maximal voluntary ventilation (MVV), in stroke patients was statistically significant among different masks (p<.05). Afterwards, the values of FVC, FEV₁, and MVV in stroke patients wearing masks were significantly lower than those of the non-masked control group (p<.05). The difference in respiratory functions with different mask filters showed no statistical significance (p<.05). Conclusion : This study showed that participants wearing any of the masks presented a lower respiratory function than that of those without using masks; additionally, no difference in respiratory functions was observed with differences in mask filters. Therefore, wearing a mask for a prolonged period is confirmed to affect breathing in stroke patients with weak respiratory function.

• Korean Journal of Exercise Nutrition
• /
• v.23 no.3
• /
• pp.45-49
• /
• 2019

[Purpose] Recent studies suggest that ursolic acid (UA) is a potential candidate for a resistance exercise mimetic that can increase muscle mass and alleviate the deleterious effect of skeletal muscle atrophy on bone health. However, these studies evaluated the effects of UA on skeletal muscle and bone tissues, and they have not verified whether such effect could occur concurrently on muscle and bone, as is the case with resistance exercise. Thus, the aim of this study was to analyze the effect of UA injection on muscle mass and bone microstructure using an animal model of atrophy to demonstrate the potential of UA as a resistance exercise mimetic. [Methods] The immobilization (IM) method was used on the left hindlimb of Sprague Dawley (SD) rats for 10 days to induce muscle atrophy, whereas the right hindlimb was used as an internal control (IC). The animal models were divided into two groups, SED (sedentary, n=6) and UA (n=6) to demonstrate the effect of UA on atrophic skeletal muscles. The UA group received a daily intraperitoneal injection of UA (5 mg/kg/day) for 8 weeks. After 10 days of IM, the data collected for the IC were compared with that of IM to determine whether muscle atrophy might occur. [Results] Muscle atrophy was induced and bone mineral density (BMD) decreased significantly. The 8-week UA treatment significantly increased the gastrocnemius muscle mass compared to the SED group. In regard to the effect of UA on bones, negative results such as a decrease in BMD, trabecular bone volume fraction, and trabecular number, and an increase in trabecular separation, were observed in the SED group, but no such difference was observed in the UA group. No significant difference was observed in atrophic hindlimbs between SED and UA groups. [Conclusion] These results alone are insufficient to suggest that UA is a potential resistance exercise mimetic for atrophic skeletal muscle and weakened bone. However, this study will help determine the potential of UA as a resistance exercise mimetic.