• Korean Journal of Applied Biomechanics
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• v.25 no.1
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• pp.49-56
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• 2015

Objectives : The purpose of this study was to present quantitative data and basic references to decrease the accident risk of soccer instructors. Methods : To obtain data, we conducted an investigation on how H/Q ratio affects the dynamic stability of the lower extremity at the time of drop landing. The study targeted 13 soccer players from C University who have not had any injuries or wounds in the lower extremity joints and in any other parts of their bodies over the last 6 months. By using CMIS (USA), the players were divided into two groups according to H/Q ratios higher and lower than 69%, respectively. The subjects in each group were instructed to perform a drop landing. Results : The H/Q ratio did not affect the maximal flexion angle of the knee joints at the time of drop landing. In addition the dominant group with a relatively high H/Q ratio was observed to have increased time to reduce shock and to efficiently absorb the ground reaction force during drop landing. Also, the dominant group with a relatively high H/Q ratio utilized the strong performances of the antagonistic muscles around the hamstrings and the controlled rotatory powers of the thighs that were applied to the tibias supported by the ground. Finally, H/Q ratio, load factors, and mean and maximum EMG were significantly negatively related, whereas GRFx showed a positive relationship. In fact, these factors all affected the impact of the load from the H/Q ratio to the knee joints. Conclusion : From these findings it can be concluded that unbalanced H/Q ratio can be considered as a predictor of knee joint injury at the time of drop landing.

• Physical Therapy Korea
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• v.12 no.1
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• pp.45-54
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• 2005

The quadriceps-angle (Q-angle) and the ratio of hamstring/quadriceps (H/Q) are important for the stability of the knee and for protection from excessive stress. The aim of this study was to examine the association between Q-angle and H/Q ratio with and without knee osteoarthritis. We compared knee osteoarthritis patients with symptom-free women. The mean age of the patients in the arthritis group (25 women, osteoarthritis) was 59.7 years. The non-arthritis group consisted of 25 women with a mean age of 55.2 years. Of the 25 women with osteoarthritis, 5 had the condition in their left knee, 5 had it in their right knee, and 15 had it on both sides. There was no significant difference in the knee Q-angle of the left and right knees of the arthritis group and the non-arthritis-group (p>.05). The strength of all the muscles around the involved right knee in the arthritis group was significantly weaker than that of the non-arthritis group (p<.05). However, in the left knee, only the strength of the knee extensors and internal rotators was significantly weaker than that of the non-arthritis group (p<.05). The Q-angle was not associated with the H/Q ratio and internal rotators/external rotators ratio of the involved knee in the arthritis group (p>.05). Neither was the Q-angle associated with the pain level of an involved knee in the arthritis group (p>.05). The knee pain was not associated with the H/Q ratio of the involved knee in the arthritis group (p>.05). The Q-angle was not associated with the ratio of H/Q and pain level of the involved knee in the osteoarthritis women.

• Korean Journal of Applied Biomechanics
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• v.19 no.4
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• pp.617-625
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• 2009

The primary purpose of this study was to compare the hamstring-to-quadriceps strength(H/Q) ratios in collegiate soccer players and normal age-matched healthy students, and the secondary purpose was to investigate the changes in the H/Q ratio according to the degree of knee flexion. Twenty-five subjects volunteered to participate in this study. The study group comprised 12 healthy male collegiate soccer players, and the control group, 13 healthy age-matched male collegiate students. The modified N-K table was used for isometric strength measurement(unit: N). Mann-Whitney tests were performed to determine the differences in the H/Q ratios of soccer players and age-matched students at different knee flexion angles of the dominant leg. The strength of the hamstring muscle in the study group was significantly lower than that observed in the control group at knee flexion angles of $60^{\circ}$ (p<.001), $90^{\circ}$ (p<.01), and $120^{\circ}$ (p<05). The strength of the quadriceps muscle in the study group was significantly higher than that observed in the control group at flexion angles of $30^{\circ}$ (p<.001) and $60^{\circ}$ (p<.05). The H/Q ratios in the study and control groups differed significantly at all angles ($60^{\circ}$, p<.001, $90^{\circ}$, p<.001 and $120^{\circ}$, p<.001).

• The Korean Journal of Nuclear Medicine Technology
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• v.23 no.2
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• pp.29-37
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• 2019

Purpose DMIDR(Discovery Molecular Imaging Digital Ready, General Electric Healthcare, USA) is a PET/CT scanner designed to allow application of PSF(Point Spread Function), TOF(Time of Flight) and Q.Clear algorithm. Especially, Q.Clear is a reconstruction algorithm which can overcome the limitation of OSEM(Ordered Subset Expectation Maximization) and reduce the image noise based on voxel unit. The aim of this paper is to evaluate the performance of reconstruction algorithms and optimize the algorithm combination to improve the accurate SUV(Standardized Uptake Value) measurement and lesion detectability. Materials and Methods PET phantom was filled with $^{18}F-FDG$ radioactivity concentration ratio of hot to background was in a ratio of 2:1, 4:1 and 8:1. Scan was performed using the NEMA protocols. Scan data was reconstructed using combination of (1)VPFX(VUE point FX(TOF)), (2)VPHD-S(VUE Point HD+PSF), (3)VPFX-S (TOF+PSF), (4)QCHD-S-400((VUE Point HD+Q.Clear(${\beta}-strength$ 400)+PSF), (5)QCFX-S-400(TOF +Q.Clear(${\beta}-strength$ 400)+PSF), (6)QCHD-S-50(VUE Point HD+Q.Clear(${\beta}-strength$ 50)+PSF) and (7)QCFX-S-50(TOF+Q.Clear(${\beta}-strength$ 50)+PSF). CR(Contrast Recovery) and BV(Background Variability) were compared. Also, SNR(Signal to Noise Ratio) and RC(Recovery Coefficient) of counts and SUV were compared respectively. Results VPFX-S showed the highest CR value in sphere size of 10 and 13 mm, and QCFX-S-50 showed the highest value in spheres greater than 17 mm. In comparison of BV and SNR, QCFX-S-400 and QCHD-S-400 showed good results. The results of SUV measurement were proportional to the H/B ratio. RC for SUV is in inverse proportion to the H/B ratio and QCFX-S-50 showed highest value. In addition, reconstruction algorithm of Q.Clear using 400 of ${\beta}-strength$ showed lower value. Conclusion When higher ${\beta}-strength$ was applied Q.Clear showed better image quality by reducing the noise. On the contrary, lower ${\beta}-strength$ was applied Q.Clear showed that sharpness increase and PVE(Partial Volume Effect) decrease, so it is possible to measure SUV based on high RC comparing to conventional reconstruction conditions. An appropriate choice of these reconstruction algorithm can improve the accuracy and lesion detectability. In this reason, it is necessary to optimize the algorithm parameter according to the purpose.

• Korean Chemical Engineering Research
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• v.54 no.1
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• pp.101-107
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• 2016

This paper investigates the feasibility of applying the jet loop reactor for the neutralization of alkaline wastewater using carbon dioxide ($CO_2$). In this study, pH changes and $CO_2$ removal characteristics were examined by changing influent flow rate of alkaline wastewater (initial pH=10.1) and influent $CO_2$ flow rates. Influent flow rates of alkaline wastewater ($Q_{L,in}$) ranged between 0.9 and 6.6 L/min, and inlet gas flow rate ($Q_{G,in}$) of 1 and 6 L/min in a lab-scale continuous flow jet loop reactor. The outlet pH of wastewater was maintained at 7.2 when the ratio ($Q_{L,in}/Q_{G,in}$) of $Q_{L,in}$ and $Q_{G,in}$ was 1.1. However, the $CO_2$ removal efficiency and the outlet pH of wastewater were increased when $Q_{L,in}/Q_{G,in}$ ratio was higher than 1.1. Throughout the experiments, the maximum $CO_2$ removal efficiency and the outlet pH of wastewater were 98.06% and 8.43 at the condition when $Q_{G,in}$ and $Q_{L,in}$ were 2 L/min and 4 L/min, respectively.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.1
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• pp.198-208
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• 2011

When a structure which has relatively low load constructs on soft clay, the bearing capacity of the ground will be improved by sand overlying clay. In this condition, verifying the bearing capacity is difficult from the P.B.T etcetera in the in-situ. So, it is needed to estimate precise bearing capacity in the design process. In this study, 2-dimensional chamber tests and FEM analyses are conducted to evaluate behavior of bearing capacity for shallow foundations on a sand overlying clay. Because depth ratio H/B and bearing capacity ratio $q_c/q_s$ are selected as main factors, height of a sand, undrained shear strength of a clay and width of a loading are designated as variables. Results from chamber tests are very similar with those of FEM analyses. And it shows that punching shear mechanism is more suitable than the equation of Okamura et al.(1998). To make continual application of load spread mechanism, the equivalent load spread angle is proposed for H/B and $q_c/q_s$. Also, the linear regression equation of critical depth ratio Hf is suggested for $q_c/q_s$.

• Journal of Life Science
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• v.18 no.1
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• pp.30-37
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• 2008

The purpose of this study was to investigate the effect of Isotonic Training and Isotonic isometric complex Training to Knee joint Isokinetic muscle function in the high-school Taekwondo athlete. This subjects were randomly divided into two groups; a Isotonic Training group (n=7) Isotonic isometric complex Training group (n=7), Taekwondo athletes share each, 12 weeks between executes a motion. peak torque, H/Q ratio, bilateral muscular ratio muscular endurance of knee joint measured. For this study, two-way ANOVA with repeated measure were used. The result of this study presents between groups was not plain difference expressed. H/Q ratio, bilateral muscular ratio, muscular endurance was plain difference expressed after 12 weeks point of time (p>0.05) and peak torque was plain difference expressed (p<0.05). Conclusion each group did not appear all but one (peak torque), but point of view exercise was effect H/Q ratio, bilateral muscular ratio, muscular endurance, peak torque plain difference expressed.

• Bulletin of the Korean Mathematical Society
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• v.55 no.5
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• pp.1317-1332
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• 2018

In this paper, we introduce the D-ratio of a rational map $f:{\mathbb{P}}^n{\dashrightarrow}{\mathbb{P}}^n$, defined over ${\bar{\mathbb{Q}}}$, whose indeterminacy locus is contained in a hyperplane H on ${\mathbb{P}}^n$. The D-ratio r(f; ${\bar{V}}$) characterizes endomorphisms and provides a useful height inequality on ${\mathbb{P}}^n({\bar{\mathbb{Q}}}){\backslash}H$. We also provide a dynamical application: preperiodic points of dynamical systems of small D-ratio are of bounded height.

• Physical Therapy Korea
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• v.27 no.4
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• pp.241-249
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• 2020

Background: Prolonged standing during work causes a lower extremity pain and disorders. Patellofemoral pain syndrome (PFPS) is one of the common diagnoses of the knee pain. Although the etiology of PFPS is not completely understood, it is considered to be multifactorial. Objects: The purpose of this study was to investigate difference in strength of knee muscles, quadriceps:hamstring muscles strength ratio (Q:H ratio), asymmetry ratio of knee muscles strength and dorsiflexion range of motion (ROM) between standing workers with and without PFPS. Methods: Twenty-eight standing workers with PFPS and 26 age-, height-, and weight-matched standing workers without PFPS participated in this study. A tension sensor measured knee muscle strength, and motion sensor measured dorsiflexion ROM. The asymmetry ratio of knee muscles was calculated by a specific formula using the knee muscles strength of the dominant side and the sound side. An independent t-test was used to identify significant differences in the strength, ROM, Q:H ratio, and asymmetry ratio between the PFPS and normal groups. Results: The standing worker with PFPS have significantly lower dorsiflexion ROM (p < 0.000) and higher asymmetry ratio of the hamstring muscles strength (p < 0.000) compare to the standing worker without PFPS. No significant differences were seen in the strength of quadriceps muscle and hamstring muscles, Q:H ratio, and asymmetry ratio of quadriceps muscle strength. Conclusion: There was a significant difference in the asymmetry ratio of the isometric hamstring muscle strength. This finding suggests that the asymmetry ratio of isometric hamstring muscle strength may be more important than measuring only the hamstring muscle strength of the PFPS side. Furthermore, the results of this study showed a significant difference in dorsiflexion ROM between the standing industrial workers with and without PFPS. Dorsiflexion ROM and isometric hamstring muscle strength should be considered when evaluating the subjects with PFPS.

• Journal of the Korean Ceramic Society
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• v.36 no.9
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• pp.937-945
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• 1999

In an effort to protect a RBSC(reaction -bonded SiC) tube SiC films from methyltrichlorosilane(MTS) by low pressure chemical vapor deposition were deposited in hydrogen atmosphere on the RBSC(reaction-bonded SiC) substrates over a range of input gas ratio(${\alpha}=P_{H2}/P_{MTS}=Q_{H2}/Q_{MTS}$=1 to 10) and deposition temperatures(T=1050~1300$^{\circ}C$). At the temper-ature of 1250$^{\circ}C$ the growth rate of SiC films increased and then decreased with decreasing the input gas ratio. The microstructure of SiC films was changed from granular type structure exhibiting (111) preferred orientation in the high input gas ratios to faceted columnar grain structure showing (220) in the low input gas ratios. The similar microstructure change was obtained by increasing the deposition temperature. These results were closely related to a change of deposition mechanism. Double layer structure having granular type and faceted ciolumnar grain structure from the manipulation of mechanism. Double layer structure having granular type and faceted columnar grain structure from the manipulation of the input gas ratio without changing the deposition temperatue was successfully fabricated through in -site process.