• Wind and Structures
• /
• 제25권2호
• /
• pp.131-156
• /
• 2017

This paper deals with the dynamic stability of embedded functionally graded (FG)-carbon nanotubes (CNTs)-reinforced micro cylindrical shells. The structure is subjected to harmonic non-uniform temperature distribution and 2D magnetic field. The CNT reinforcement is either uniformly distributed or FG along the thickness direction where the effective properties of nano-composite structure are estimated through Mixture low. The viscoelastic properties of structure are captured based on the Kelvin-Voigt theory. The surrounding viscoelastic medium is considered nonhomogeneous with the spring, orthotropic shear and damper constants. The material properties of cylindrical shell and the viscoelastic medium constants are assumed temperature-dependent. The first order shear deformation theory (FSDT) or Mindlin theory in conjunction with Hamilton's principle is utilized for deriving the motion equations where the size effects are considered based on Eringen's nonlocal theory. Based on differential quadrature (DQ) and Bolotin methods, the dynamic instability region (DIR) of structure is obtained for different boundary conditions. The effects of different parameters such as volume percent and distribution type of CNTs, mode number, viscoelastic medium type, temperature, boundary conditions, magnetic field, nonlocal parameter and structural damping constant are shown on the DIR of system. Numerical results indicate that the FGX distribution of CNTs is better than other considered cases. In addition, considering structural damping of system reduces the resonance frequency.

• 한국콘텐츠학회논문지
• /
• 제12권11호
• /
• pp.39-48
• /
• 2012

소프트웨어 테스팅이 소프트웨어 개발 비용의 상당 부분을 차지하는 것은 잘 알려진 사실이다. 소프트웨어 테스팅 비용을 줄이기 위해 소프트웨어 테스트 데이터를 자동으로 생성하는 방법에 많은 연구가 이루어지고 있다. 일반적으로 테스트 데이터 자동 생성을 지원하기 위해 심볼릭 실행기나 제약 해결기와 같은 정교한 도구들을 요구한다. 그러나 이와 같은 도구들을 개발하거나 구입하는 것은 소프트웨어 테스트 관련 비용을 증가시키는 또 다른 요소로 작용된다. 이 논문에서는 심볼릭 실행이나 제약 해결에 의존되지 않는 동적 테스트 데이터 방법을 제안한다. 제안된 방식은 분기 커버리지 기준을 효과적으로 만족하도록 Korel의 경로 지향 테스트 데이터 생성 방법을 확장한다. 이 논문에서는 삼각형 분류 프로그램에 대한 실험을 통하여 제안된 방법이 분기 커버리지를 매우 효과적으로 달성함을 보인다.

• 대한한의학회지
• /
• 제26권1호
• /
• pp.11-17
• /
• 2005

This study was carried out to identify the components of the human heart meridian muscle, the regional muscle group being divided into outer, middle, and inner layers. The inner parts of the body surface were opened widely to demonstrate muscles, nerves, blood vessels and to expose the inner structure of the heart meridian muscle in the order of layers. We obtained the following results; $\cdot$ The heart meridian muscle is composed of muscles, nerves and blood vessels. $\cdot$ In human anatomy, the difference between terms is present (that is, between nerves or blood vessels which control the meridian muscle and those which pass near by). $\cdot$ The inner composition of the heart meridian muscle in the human arm is as follows: 1) Muscle H-l: latissimus dorsi muscle tendon, teres major muscle, coracobrachialis muscle H-2: biceps brachialis muscle, triceps brachialis muscle, brachialis muscle H-3: pronator teres muscle and brachialis muscle H-4: palmar carpal ligament and flexor ulnaris tendon H-5: palmar carpal ligament & flexor retinaculum, tissue between flexor carpi ulnaris tendon and flexor digitorum superficialis tendon, flexor digitorum profundus tendon H-6: palmar carpal ligament & flexor retinaculum, flexor carpi ulnaris tendon H-7: palmar carpal ligament & flexor retinaculum, tissue between flexor carpi ulnaris tendon and flexor digitorum superficial is tendon, flexor digitorum profundus tendon H-8: palmar aponeurosis, 4th lumbrical muscle, dorsal & palmar interrosseous muscle H-9: dorsal fascia, radiad of extensor digiti minimi tendon & extensor digitorum tendon 2) Blood vessel H-1: axillary artery, posterior circumflex humeral artery H-2: basilic vein, brachial artery H-3: basilic vein, inferior ulnar collateral artery, brachial artery H-4: ulnar artery H-5: ulnar artery H-6: ulnar artery H-7: ulnar artery H-8: palmar digital artery H-9: dorsal digital vein, the dorsal branch of palmar digital artery 3) Nerve H-1: medial antebrachial cutaneous nerve, median n., ulnar n., radial n., musculocutaneous n., axillary nerve H-2: median nerve, ulnar n., medial antebrachial cutaneous n., the branch of muscular cutaneous nerve H-3: median nerve, medial antebrachial cutaneous nerve H-4: medial antebrachial cutaneous nerve, ulnar nerve H-5: ulnar nerve H-6: ulnar nerve H-7: ulnar nerve H-8: superficial branch of ulnar nerve H-9: dorsal digital branch of ulnar nerve.

• 한국동물위생학회지
• /
• 제36권2호
• /
• pp.139-145
• /
• 2013

Porcine respiratory disease complex (PRDC) continues to be a significant economic problem to the swine industry. In order to elucidate the etiology of PRDC including porcine circovirus type 2 (PCV2), porcine reproductive and respiratory disease syndrome virus (PRRSV), swine influenza virus (SIV), Mycoplasma hyopneumoniae (MH), Pasteurella multocida (PM) and Actinobacillus pleuropneumoniae (APP) in Namwon, the 455 lung samples were randomly collected from slaughtered pigs, examined gross lesions indicative of respiratory disease of lung and classified the lung lesion according to the severity of lung lesions. Two hundred pigs lung tissues with pneumonic lesions were examined for pathogen by PCR. As a result, the numbers of pneumonic lesions were 357 (78.5%), mean pneumonic score ($mean{\pm}SD$) was $2.03{\pm}0.90$ and the highest gross lesion according to stages was 1 (11~20%). In detection of pathogens, PCV2, PRRSV, SIV, MH, APP and PM were positive in 76.5%, 5.0%, 6.0%, 9.0%, 4.5% and 6.0%, respectively and PCV2-MH was the most detected causative pathogens of PRDC in co-infection. In the serological test for PRRSV, PCV2, MH, APP2, APP5, HP and PM, showed high antibody positive rates 93% or more.

• The Korean Journal of Ecology
• /
• 제18권1호
• /
• pp.189-201
• /
• 1995

In order to clarify regeneration processes and mechanisms of the disturbed Pinus densiflora forest, responses of Pinus densiflora to gap formed by disturbance were analysed by growth of saplings and mature and growth equations were obtained from branch growth of mature trees and height growth of saplings, and age distribution of saplings and young trees recruited within gap was analysed in relation to gap age. Height growth of saplings within gaps was accelerated after gap formation. Such abrupt increases of growth of saplings after the gap formation might be resulted in the difference of growth of saplings between gap and non-gap areas. In fact, height and diameter of saplings in the central part of gap were larger than those of saplings in marginal parts of gap and non-gap area. However, density of saplings was not different in both parts. In addition, growth of annual rings of mature trees bordering on gap also increased after gap formation. Branch growth of mature trees bodering on gap was 6.3 - 6.5 cm /year and the mean radius of gaps created by death of only one canopy tree was about 3 m. Therefore, for those gaps to be closed by branch growth it will take 46 years. Growth of saplings within gap showed exponential equation. Fifty years will be required for the saplings to enter the forest canopy by the exponential growth equation. Therefore, gap created by only one tree might be closed by branch growth of surrounding canopy trees in advance of being done by height growth of saplings. But gaps created by death of trees more than 2 will be closed by the growth of saplings. Among the regenerating saplings and young trees within gaps, individuals established in advance of gap formation were more than those established after the gap formation. From these results, it was assumed that the disturbed Pinus densiflora forests in these sites were regenerated by height growth of saplings recruited in advance of gap formation.

• 한국세라믹학회지
• /
• 제48권3호
• /
• pp.236-240
• /
• 2011

In order to deposit a homogeneous and uniform ${\beta}$-SiC films by chemical vapor deposition, we demonstrated the phase stability of ${\beta}$-SiC over graphite and silicon via computational thermodynamic calculation considering pressure, temperature and gas composition as variables. The ${\beta}$-SiC predominant region over other solid phases like carbon and silicon was changed gradually and consistently with temperature and pressure. Practically these maps provide necessary conditions for homogeneous ${\beta}$-SiC deposition of single phase. With the thermodynamic analyses, the CVD apparatus for uniform coating was modeled and simulated with computational fluid dynamics to obtain temperature and flow distribution in the CVD chamber. It gave an inspiration for the uniform temperature distribution and low local flow velocity over the deposition chamber. These calculation and model simulation could provide milestones for improving the thickness uniformity and phase homogeneity.

• Archives of Plastic Surgery
• /
• 제37권6호
• /
• pp.769-774
• /
• 2010

Purpose: As the soft tissue defect around the knee is difficult to reconstruct, local flap or free flap is used. Distally based anterolateral thigh pedicled flap introduced by Zhang uses sufficient reverse flow supplied from the vascular network around the knee. We report successful reconstruction of defect around knee by this method. Methods: Four patients with skin & soft tissue defect around knee have been treated for reconstruction using the distally based anterolateral thigh pedicled flap. First, the doppler was used to check the perforator flap of the descending branch of the lateral circumflex femoral artery and to draw and dissect the perforator flap as much as needed. After the dissection, the proximal of the descending branch was clamped and checked for sufficient supply of blood flow from the reverse flow and then ligated. It was dissected along the descending branch and in order to prevent damage to the joined parts of the descending branch and the lateral superior geniculate artery, a more careful ligation was done starting from 10 cm superior to the knee. The defect was reconstructed after securing enough vascular pedicle to cover all the damaged parts. Results: Not all patients suffered from flap necrosis. In case of the patient with chronic osteomyelitis, slight venous congestion was observed right after the surgery but it disappeared the following day. All three patients had no occurences of additional complications. Conclusion: Distally based anterolateral thigh pedicled flap was enough to provide large flap for knee reconstruction. It had sufficient blood flow and vascular pedicle. It also had taken short operation time compared to the free flap operation. The distally based anterolateral thigh pedicled flap used by the authors is a very useful way of reconstructing the area around knee.

• Corrosion Science and Technology
• /
• 제18권5호
• /
• pp.212-219
• /
• 2019

This paper reviews recent approaches to develop composite polymer-containing coatings by plasma electrolytic oxidation (PEO) using various low-molecular fractions of superdispersed polytetrafluoroethylene (SPTFE). The features of the unique approaches to form the composite polymer-containing coating on the surface of MA8 magnesium alloy were summarized. Improvement in the corrosion and tribological behavior of the polymer-containing coating can be attributed to the morphology and insulating properties of the surface layers and solid lubrication effect of the SPTFE particles. Such multifunctional coatings have high corrosion resistance ($R_p=3.0{\times}10^7{\Omega}cm^2$) and low friction coefficient (0.13) under dry wear conditions. The effect of dispersity and ${\xi}$-potential of the nanoscale materials ($ZrO_2$ and $SiO_2$) used as electrolyte components for the plasma electrolytic oxidation on the composition and properties of the coatings was investigated. Improvement in the protective properties of the coatings with the incorporated nanoparticles was explained by the greater thickness of the protective layer, relatively low porosity, and the presence of narrow non-through pores. The impedance modulus measured at low frequency for the zirconia-containing layer (${\mid}Z{\mid}_{f=0.01Hz}=1.8{\times}10^6{\Omega}{\cdot}cm^2$) was more than one order of magnitude higher than that of the PEO-coating formed in the nanoparticles-free electrolyte (${\mid}Z{\mid}_{f=0.01Hz}=5.4{\times}10^4{\Omega}{\cdot}cm^2$).

• Korean Chemical Engineering Research
• /
• 제59권4호
• /
• pp.493-502
• /
• 2021

We prepared and investigated a biosynthesized nanoparticulate system with high adsorption and release capacity of letrozole. Silver nanoparticles (AgNPs) were biosynthesized using olive leaf extract. Cysteine was capped AgNPs to increase the adsorption capacity and suitable interaction between nanoparticles and drug. Morphology and size of nanoparticles were confirmed using transmission electron microscopy (TEM). Nanoparticles were spherical with an average diameter of less than 100 nm. Cysteine capping was successfully confirmed by Fourier transform infrared resonance (FTIR) spectroscopy and elemental analysis (CHN). Also, the factors of letrozole adsorption were optimized and the linear and non-linear forms of isotherms and kinetics were studied. Confirmation of the adsorption data of letrozole by cysteine capped nanoparticles in the Langmuir isotherm model indicated the homogeneous binding site of modified nanoparticles surface. Furthermore, the adsorption rate was kinetically adjusted to the pseudo-second-order model, and a high adsorption rate was observed, indicating that cysteine coated nanoparticles are a promising adsorbent for letrozole delivery. Finally, the kinetic release profile of letrozole loaded modified nanoparticles in simulated gastric and intestinal buffers was studied. Nearly 40% of letrozole was released in simulated gastric fluid with pH 1.2, in 30 min and the rest of it (60%) was released in simulated intestinal fluid with pH 7.4 in 10 h. These results indicate the efficiency of the cysteine capped AgNPs for adsorption and release of drug letrozole for breast cancer therapy.

• Advances in concrete construction
• /
• 제14권5호
• /
• pp.299-307
• /
• 2022

Cement-based matrixes have low tensile strength and negligible ductility. Adding fibres to these matrixes will improve their mechanical properties and make these composites suitable for structural applications. Post-cracking tensile strength of steel fibers-reinforced cementitious composite materials is directly related to the number of transverse fibers passing through the crack width and the pulling-out behavior of each of the fibers. Therefore, the exact recognition of the pullout behavior of single fibers is necessary to understand the uniaxial tensile and bending behavior of steel fiber-reinforced concrete. In this paper, an experimental study has been carried out on the pullout behavior of 3D (steel fibers with totally two hooks at both ends), 4D (steel fibers with a total of four hooks at both ends), and 5D (steel fibers with totally six hooks at both ends) in which the fibers have been located either perpendicular to the crack width or in an inclined manner. The pullout behavior of the mentioned steel fibers at an inclination angle of 0, 15, 30, 45, and 60 degrees and with embedded lengths of 10, 15, 20, 25, and 30 millimetres is studied in order to explore the simultaneous effect of the inclination angle of the fibers relative to the alongside loading and the embedded length of fibers on the pullout response in each case, including the maximal pullout force, the slip of the maximum point of pullout force, pullout energy, fiber rupture, and concrete matrix spalling. The results showed that the maximum pullout energy in 3D, 4D, and 5D steel fibers with different embedded lengths occurs at 0 to 30° inclination angles. In 5D fibers, maximum pullout energy occurs at a 30° angle with a 25 mm embedded length.