• Journal of the Korean Ceramic Society
• /
• v.35 no.1
• /
• pp.48-54
• /
• 1998

The effect of coating thickness on the contact fracture was studied, in Si3N4 coated Si3N4-BN system When the elastic/plastic mismatch is relatively large betwen two layers in bilayer certain critical coating thickness was required to prevent cone crack initiation and this critical thickness was decreased by de-creasing the elastic/plastic mismatch,. In addition the required critical thickness should be increased when higher loads apply. In conclusion an appropriate coating thickness should be designed by elastic/plastic mismatch between two layers and environment (applied load) to prevent the coating fracture

• Journal of Electrochemical Science and Technology
• /
• v.4 no.1
• /
• pp.27-33
• /
• 2013

The consequences of electrode density and thickness for electrochemical performance of lithium-ion cells are investigated using 2032-type coin half cells. While the cathode composition is maintained by 90:5:5 (wt.%) with $LiCoO_2$ active material, Super-P electric conductor and polyvinylidene fluoride polymeric binder, its density and thickness are independently controlled to 20, 35, 50 um and 1.5, 2.0, 2.5, 3.0, 3.5 g $cm^{-3}$, respectively, which are based on commercial lithium-ion battery cathode system. As the cathode thickness is increased in all densities, the rate capability and cycle life of lithium-ion cells become significantly worse. On the other hand, even though the cathode density shows similar behavior, its effect is not as high as the thickness in our experimental range. This trend is also investigated by cross-sectional morphology, porosity and electric conductivity of cathodes with different densities and thicknesses. This work suggests that the electrode density and thickness should be chosen properly and mentioned in detail in any kinds of research works.

• PNF and Movement
• /
• v.18 no.3
• /
• pp.425-433
• /
• 2020

Purpose: The purpose of this study was to investigate the effect of 7Hz vibration on the thickness of the rectus femoris, medial femur, rectus femoris tendon, and Achilles tendon. Methods: The statistical methods before and after working around the average value of each of the legs included repeated measures ANOVA. The subjects were 26 males residing in the N area, and we measured the change in muscle thickness and tendon thickness before, four weeks, and eight weeks after the experiment in two groups of 13 subjects each. The analysis method was a two-way repeated measurement variance analysis (ANOVA) with a significance level of 0.05 Results: The rectus femoris, medial broad muscle, rectus femur, and Achilles tendon showed significant increases in the interaction between the periods as well as between the periods and groups (p < 0.05). Conclusion: As a result of this study, the 7Hz vibration had a positive effect on the thickness of the rectus femoris and the vastus medialis muscle as well as the thickness of the rectus femoris tendon and Achilles tendon. It is expected to be used as basic data for vibrational exercises in the future studies and is expected to be used as an exercise to strengthen the leg muscles and tendons.

• Physical Therapy Rehabilitation Science
• /
• v.10 no.4
• /
• pp.444-449
• /
• 2021

Objective: The purpose of this study is to observe the change in the thickness of abdominal muscles when electrical muscle stimulation (EMS) is applied to the abdomen during rest and abdominal muscle exercise to investigate the effect of EMS applied to the abdomen on the superficial and deep muscles thickness. Design: Cross sectional design. Methods: Twenty healthy subjects participated in this study. Subjects were performed resting position, resting position with EMS, curl-up and curl-up with EMS. The electrode of the EMS belt is attached to the abdominal wall between the 12th rib and iliac crest. The thickness of abdominal muscles including rectus abdominis (RA), external oblique (EO), internal oblique (IO), and transverse abdominis (TrA) were captured in each position by ultrasound image during expiration. All subjects were performed four positions randomly. Data were analyzed using repeated ANOVA with the level of significance set at 𝛼=0.05. Results: The muscle thickness of RA, EO, IO and TrA were significantly different at each position (p<0.05). The thickness of all abdominal muscles increased significantly when curl-up than curl-up with EMS. Both RA and EO thickness were significantly increased at resting position than resting position and EMS were combined(p<0.05). But IO and TrA thickness were decreased at resting position when EMS were combined. Conclusions: The results suggest that EMS activates superficial abdominal muscles RA and EO. Therefore, abdominal strengthening exercise combined EMS can activate abdominal muscles and can be applied to various patients and rehabilitation in clinical practice.

• Computers and Concrete
• /
• v.31 no.1
• /
• pp.71-84
• /
• 2023

In this paper, the effects of the thickness of cubic samples on the tensile strength of concrete blocks were studied using experimental tests in the laboratory and numerical simulation by the particle flow code in three dimensions (PFC3D). Firstly, the physical concrete blocks with dimensions of 150 mm×190 mm (width×height) were prepared. Then, three specimens for each of seven different samples with various thicknesses were built in the laboratory. Simultaneously with the experimental tests, their numerical simulations were performed with PFC3D models. The widths, heights, and thicknesses of the numerical models were the same as those of the experimental samples. These samples were tested with a new tensile testing apparatus. The loading rate was kept at 1 kg/sec during the testing operation. Based on these analyses, it is concluded that when the thickness was less than 5 cm, the tensile strength decreased by increasing the sample thickness. On the other hand, the tensile strength was nearly constant when the sample thickness was raised to more than 5 cm (which can be regarded as a threshold limit for the specimens' thickness). The numerical outputs were similar to the experimental results, demonstrating the validity of the present analyses.

• Steel and Composite Structures
• /
• v.34 no.5
• /
• pp.657-670
• /
• 2020

In this paper, vibration analysis of functionally graded nanoshell is studied based on the sinusoidal higher-order shear and normal deformation theory to account thickness stretching effect. To account size-dependency, Eringen nonlocal elasticity theory is used. For more accurate modeling the problem and corresponding numerical results, sinusoidal higher-order shear and normal deformation theory including out of plane normal strain is employed in this paper. The radial displacement is decomposed into three terms to show variation along the thickness direction. Governing differential equations of motion are derived using Hamilton's principle. It is assumed that the cylindrical shell is made of an arbitrary composition of metal and ceramic in which the local material properties are measured based on power law distribution. To justify trueness and necessity of this work, a comprehensive comparison with some lower order and lower dimension works and also some 3D works is presented. After presentation of comparative study, full numerical results are presented in terms of significant parameters of the problem such as small scale parameter, length to radius ratio, thickness to radius ratio, and number of modes.

• Archives of Plastic Surgery
• /
• v.32 no.3
• /
• pp.357-362
• /
• 2005

The aim of this study is to elucidate the effect of keratinase on epidermis of rat skin. Twenty-five male Sprague-Dolly rats were used. The hair on the back were removed and $2{\times}2cm$ area was marked. The rats were divided five groups; 1) Control group(Co), 2) Cleansing gel group(Cl), 3) Cleansing gel+keratinase group, 4) Exfoliant gel group(Ex), and 5) Exfoliant gel+ keratinase group(Ex+K). The solutions were applied to the back area twice a day for five days. On fifth day, the skins were harvested, fixed and prepared for histologic sections. The thickness of keratin layer, living epidermis, dermis, and cell layer number of living epidermis were measured. In the group containing keratinase(Cl+K, Ex+K), the thickness of keratin layer and living layer were thinner than other groups. However, there were no significant differences of the cell layer number of living epidermis and thickness of the dermis among the five groups. We think the keratinase may have the effect thinning the keratin layer as well as the thickness of living epidermis, without effecting the living cell and dermal component. The keratinase containing soap may be of benefit to remove the excess keratin layers in human.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.27 no.9
• /
• pp.1531-1538
• /
• 2003

This paper compiles solutions of plastic $\eta$ factors and crack tip stress triaxialites for standard and nonstandard fracture toughness testing specimens, via detailed three-dimensional (3-D) finite element (FE) analyses. Fracture toughness testing specimens include a middle cracked tension (M(T)) specimen, SE(B), single-edge cracked bar in tension (SE(T)) and C(T) specimen. The ligament-to-thickness ratio of the specimen is systematically varied. It is found that the use of the CMOD overall provides more robust experimental J estimation than that of the LLD, for all cases considered in the present work. Moreover, the J estimation based on the load-CMOD record is shown to be insensitive to the specimen thickness, and thus can be used for testing specimen with any thickness. The effects of in-plane and out-of-plane constraint on the crack tip stress triaxiality are also quantified, so that when experimental J value is estimated according to the procedure recommended in this paper, the corresponding crack tip stress triaxiality can be estimated. Moreover, it is found that the out-of-plane constraint effect is related to the in-plane constraint effect.

• The Journal of Korean Physical Therapy
• /
• v.34 no.2
• /
• pp.68-72
• /
• 2022

Purpose: This study examined the effect of vibration exercise on the thickness of the oblique extrinsic, oblique abdominal, and biceps muscles, which are trunk muscles, targeting children with spastic cerebral palsy. Methods: The participants in this study were 20 children (8 male and 12 female) with cerebral palsy aged 5-10 years. They were classified into two groups using a randomized allocation method, and the trunk muscle thickness was measured using an ultrasound-imaging device before and six weeks after the experiment. A paired t-test was used for the within-group changes, and an independent t-test was used for the inter-group changes. The significance level was set to α=0.05. Results: There was a significant increase in the inter-group change in the experimental group and control group in the intra-group change in the external oblique muscle and internal oblique muscle. After six weeks, there was a significant increase in the experimental group compared to the control group. Conclusion: Vibration exercise had a positive effect on the trunk muscle thickness of children with cerebral palsy. Vibration exercise produced a significant difference in the changes in the trunk muscle thickness in children with cerebral palsy compared to no vibration exercise. These results may provide basic data for future research and as a training method for strengthening the trunk muscles in clinical trials.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.26 no.6
• /
• pp.343-351
• /
• 2014

The reflection and transmission coefficients of waves due to perforated wall are mainly determined by both the porosity and wall thickness of the perforated wall and the period and nonlinearity of incident waves. Among them the wall thickness is very important because it affects the head loss coefficient and the inertia length of the wall. However, by employing the head loss coefficient derived for sharp crested orifice, the previous researches have neglected, or incorrectly considered the effect of wall thickness on the head loss coefficient. Even though it is considered, the effect of the inertia length is neglected in some empirical formulae. Thus, the effect of wall thickness on the reflection and transmission coefficients of waves is not properly considered. In this study comprehensive experiments are conducted for the perforated walls with various thicknesses, and the results are compared with those predicted by the empirical formulae. As a result it is found that the existing formulae can not properly consider the effect of wall thickness, and it is confirmed that a new formula which can correctly consider the effect of wall thickness on the head loss coefficient is necessary.