• Title/Summary/Keyword: Stress Parameters

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A Study on the Consolidation Settlement Due to the Vertical Drain Method by the Implicit Finite Difference Scheme (음적차분해석법을 이용한 연직배수 공법에 의한 압밀침하에 관한 연구)

  • Park, Sung Zae;Jung, Du Hwoe;Jeong, Gyeong Hwan;Lee, Kyeong Joon
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.14 no.5
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    • pp.1243-1251
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    • 1994
  • The implicit finite difference program was developed to evaluate the relationship between time and consolidation ratio within the zone of vertical drain effective radius. In the evaluation, the excess pore water pressure was considered to dissipate in two directions, namely, vertical and radial flow direction. To calculate subsoil stress increments in the soil due to multi-step embanking, the foundation soil was assumed to be an isotropic and homogeneous elastic medium and the initial excess pore water pressure was estimated by using Skempton's parameters whose condition is plane strain and elastic phase of pore pressure response within the soft ground. Regarding to the settlement estimation, immediate and primary consolidation settlements were calculated. The secondary or delayed consolidation settlement was not considered. Numerically calculated excess pore water pressure and settlements were similar to the measured data in situ. Thus, this method can be used to predict the time-consolidation ratio of each layer treated by vertical drain method.

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Study of Ultrasonic Nonlinearity in Heat-Treated Material (열처리된 재료의 초음파 비선형성에 관한 연구)

  • Li, Weibin;Lee, Jae-Sun;Cho, Youn-Ho
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.34 no.6
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    • pp.751-756
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    • 2010
  • Ultrasonic nonlinearity is very sensitive to changes in material properties. This paper describes the study of the correlation between heat treatment and ultrasonic nonlinearity by taking nonlinear factors into consideration. A modified formula was proposed for ultrasonic velocity. This formula indicated that the changes occurring in nonlinearity during heat treatments cause changes in the ultrasonic velocity. The experimental results show that the relative nonlinearity parameters calculated from the modified ultrasonic velocities and the ratio of amplitudes of the second harmonic and fundamental wave are in good agreement. The experimental results prove that heat treatment can result in changes in material nonlinearity. Moreover, the relative nonlinearity parameter calculated from the modified velocity formula is has a large value. Since this parameter has high sensitivity to changes in nonlinearity, it can be used to represent the relative nonlinearity change calculated in this study by using the modified formula for ultrasonic velocity.

Effects of Photoperiod Manipulation on Growth Performance and Hematological Responses of Juvenile Caspian Roach Rutilus rutilus caspicus

  • Shahkar, Erfan;Kim, Dae-Jung;Mohseni, Mahmoud;Khara, Hossein;Yun, Hyeonho;Bai, Sungchul C.
    • Fisheries and Aquatic Sciences
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    • v.18 no.1
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    • pp.51-56
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    • 2015
  • A 8-week trial was conducted to evaluate the effects of photoperiod manipulation on the growth performance and hematological parameters of juvenile Caspian roach, Rutilus rutilus caspicus (average weight $1.46{\pm}0.12g$ mean${\pm}$SD) reared under five photoperiods (24 h Light, 24L; 18 h Light & 6 h Dark, 18L:6D; 12 h Light & 12 h Dark, 12L:12D; 6 h Light & 18 h Dark, 6L:18D; 24 h Dark, 24D) with constant light intensity 1,500 lx on the water surface. Triplicate of 20 fish were allocated into each of 15 fiberglass tanks of 50 L capacity and they were fed three times per day with the commercial feed (SFK, Co., Sari - Iran) contains 50.0% protein and 10.5% lipid. At the end of experimental period, final body weight, weight gain and specific growth rates of fish exposed to 24L were significantly higher than those of fish exposed to 12L:12D, 6L:18D and 24D (P < 0.05). Red blood cell and hemoglobin of fish exposed to 24L were significantly higher than those of fish exposed to 24D. No significant difference observed in hematocrit, white blood cell and plasma glucose among the different treatments groups. Therefore, these results demonstrated that the growth performance of juvenile Caspian roach can be significantly stimulated by using 24L and 18L:6D photoperiods without any measurable significant stress response such as plasma glucose concentration.

Effects of Salinity Changes on Hematological Responses in Juvenile Ship Sturgeon Acipenser nudiventris

  • Shahkar, Erfan;Kim, Dae-jung;Mohseni, Mahmoud;Yun, Hyeonho;Bai, Sungchul C.
    • Fisheries and Aquatic Sciences
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    • v.18 no.1
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    • pp.45-50
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    • 2015
  • A 10-day trial was conducted to evaluate the salinity tolerance and hematological responses of juvenile ship sturgeon Acipenser nudiventris under different salinity levels. A total of 240 fish averaging $6.2{\pm}0.13g$ (mean${\pm}$SD) were randomly distributed into 12 tanks in groups of 20, and each tank was then randomly assigned to one of three replicates of four different salinities at 0, 4, 8 and 12‰. At the end of 10 days of experimental period, plasma protein value of fish exposed to 0‰ and 4‰ salinities was significantly higher than those of fish exposed to 8‰ and 12‰ salinities (P < 0.05). Significantly higher values for plasma cortisol and glucose were obtained in fish exposed to 12‰ salinity compared to the fish exposed to 0‰ and 4‰ salinities (P < 0.05). Plasma potassium and sodium values increased significantly by increment of salinity levels (P < 0.05). Therefore, these results indicated that in natural environments, juvenile ship sturgeon, A. nudiventris in migratory populations could be able to migrate and adjust successfully into brackish water with a salinity of up to 8‰ without any short-term hematological stress responses.

Thermal Residual Stresses in the Frequency Selective Surface Embedded Composite Structures and Design of Frequency Selective Surface (주파수 선택적 투과막이 결합된 복합재료의 잔류응력평가 및 선택적 투과막 설계)

  • Kim, Ka-Yeon;Chun, Heoung-Jae;Kang, Kyung-Tak;Lee, Kyung-Won;Hong, Ic-Pyo;Lee, Myoung-Keon
    • Composites Research
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    • v.24 no.1
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    • pp.37-44
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    • 2011
  • In this paper, Particle Swarm Optimization(PSO) is applied to the design of the Frequency Selective Surface(FSS) and residual stresses of hybrid radome is predicted. An equivalent circuit model with Square Loops arrays was derived and then PSO was applied for acquiring the optimized geometrical parameters with proper resonant frequency. Residual stresses occur in the FSS embedded composite structures after cocuring and have a great influence on the strength of the FSS embedded composite structures. They also effect transmission quality because of delamination. Therefore, the thermal residual stresses of FSS embedded composite structures were analyzed using finite element analysis with considering the effects of FSS pattern, and composite stacking sequence.

Ameliorating Effects of Moxifloxacin on Endotoxin-Induced Acute Lung Injury in Rats (흰쥐에서 내독소로 유도된 급성 폐손상에서 moxofloxacin의 개선효과)

  • Lee, Young-Man;Chae, Whi-Gun
    • Journal of Life Science
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    • v.21 no.8
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    • pp.1100-1108
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    • 2011
  • The immunomodulating effects of moxifloxacin seem to be effective in downregulating inflammatory reactions. This presumed effect was tested in endotoxin (ETX)-induced acute lung injury (ALI) in rats. After moxifloxacin treatment (10 mg/kg) of ETX-given rats, lung myeloperoxidase (MPO) activity, bronchoalveolar-lavage (BAL) protein, and the number of neutrophils in the BAL cells were measured. Light and electron microscopic structures were also examined. Electron microscopic $CeCl_3$ histochemistry for the detection of hydrogen peroxide in the lungs and immunohistochemistry of cytosolic phospholipase A2 (cPLA2) in the lung tissues and BAL cells were performed. To examine the expression of TNF${\alpha}$ in the lungs, western blotting was carried out with the lung tissues. ETX had accumulated neutrophils in the lungs, which was followed by lung leak. Oxidative stress occurred, and increased expression of cPLA2 in the lung tissues and BAL cells was observed in the ETX-given rats. Simultaneously, the expression of TNF${\alpha}$ was enhanced by ETX. Moxifloxacin, however, decreased all these parameters, indicating that ALI may have been ameliorated. Moxifloxacin appears to ameliorate ETX-induced ALI partially through the suppression of cPLA2 in the lungs of rats.

Numerical modeless of the damage, around inclusion in the orthopedic cement PMMA

  • Mohamed, Cherfi;Smail, Benbarek;Bouiadjra, Bachir;Serier, B.
    • Structural Engineering and Mechanics
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    • v.57 no.4
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    • pp.717-731
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    • 2016
  • In orthopedic surgery and more especially in total arthroplastie of hip, the fixing of the implants generally takes place essentially by means of constituted surgical polymer cement. The damage of this materiel led to the fatal rupture and thus loosening of the prosthesis in total hip, the effect of over loading as the case of tripping of the patient during walking is one of the parameters that led to the damage of this binder. From this phenomenon we supposed that a remain of bone is included in the cement implantation. The object of this work is to study the effect of this bony inclusion in the zones where the outside conditions (loads and geometric shapes) can provoke the fracture of the cement and therefore the aseptic lousing of the prosthesis. In this study it was assumed the presence of two bones -type inclusions in this material, one after we analyzed the effect of interaction between these two inclusions damage of damage to this material. One have modeled the damage in the cement around this bone inclusion and estimate the crack length from the damaged cement zone in the acetabulum using the finite element method, for every position of the implant under the extreme effort undergone by the prosthesis. We noted that the most intense stress position is around the sharp corner of the bone fragment and the higher level of damage leads directly the fracture of the total prosthesis of the hip.

Interaction analysis of a building frame supported on pile groups

  • Dode, P.A.;Chore, H.S.;Agrawal, D.K.
    • Coupled systems mechanics
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    • v.3 no.3
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    • pp.305-318
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    • 2014
  • The study deals with the physical modeling of a typical building frame resting on pile foundation and embedded in cohesive soil mass using complete three-dimensional finite element analysis. Two different pile groups comprising four piles ($2{\times}2$) and nine piles ($3{\times}3$) are considered. Further, three different pile diameters along with the various pile spacings are considered. The elements of the superstructure frame and those of the pile foundation are descretized using twenty-node isoparametric continuum elements. The interface between the pile and pile and soil is idealized using sixteen-node isoparametric surface elements. The current study is an improved version of finite element modeling for the soil elements compared to the one reported in the literature (Chore and Ingle 2008). The soil elements are discretized using eight-, nine- and twelve-node continuum elements. Both the elements of superstructure and substructure (i.e., foundation) including soil are assumed to remain in the elastic state at all the time. The interaction analysis is carried out using sub-structure approach in the parametric study. The total stress analysis is carried out considering the immediate behaviour of the soil. The effect of various parameters of the pile foundation such as spacing in a group and number piles in a group, along with pile diameter, is evaluated on the response of superstructure. The response includes the displacement at the top of the frame and bending moment in columns. The soil-structure interaction effect is found to increase displacement in the range of 58 -152% and increase the absolute maximum positive and negative moments in the column in the range of 14-15% and 26-28%, respectively. The effect of the soil- structure interaction is observed to be significant for the configuration of the pile groups and the soil considered in the present study.

Prognostic Significance of Altered Blood and Tissue Glutathione Levels in Head and Neck Squamous Cell Carcinoma Cases

  • Khan, Sami Ullah;Mahjabeen, Ishrat;Malik, Faraz Arshad;Kayani, Mahmood Akhtar
    • Asian Pacific Journal of Cancer Prevention
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    • v.15 no.18
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    • pp.7603-7609
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    • 2014
  • Glutathione is a thiol compound that plays an important role in the antioxidant defense system of the cell and its deficiency leads to an increased susceptibility to oxidative stress and, thus, progression of many disease states including head and neck cancer. In the present study, alterations of glutathione levels were investigated in study cohort of 500 samples (cohort 1 containing 200 head and neck cancer blood samples along with 200 healthy controls and cohort II with 50 head and neck squamous cell carcinoma tissue samples along with 50 control tissues) by high performance liquid chromatography. The results indicated that mean blood glutathione levels were significantly reduced in head and neck cancer patients (p<0.001) compared to respective controls. In contrast, the levels of glutathione total (p<0.05) and glutathione reduced (p<0.05) were significantly elevated in head and neck squamous cell carcinoma tissues compared to the adjacent cancer-free control tissues. In addition to this, pearson correlation performed to correlate different tissue glutathione levels (GSH) with clinical/pathological parameters demonstrated a significant negative correlation between pT-stage and GSH level ($r=-0.263^{**}$; p<0.01), C-stage and GSH level ($r=-0.335^{**}$; p<0.01), grade and GSH ($r=-0.329^{**}$; p<0.01) and grade versus redox index ($r=-0.213^{**}$; p<0.01) in HNSCC tissues. Our study suggests that dysregulation of glutathione levels in head and neck cancer has the potential to predict metastasis, and may serve as a prognostic marker.

Analysis of a Novel Self-Aligned ESD MOSFET having Reduced Hot-Carrier Effects (Hot-Carrier 현상을 줄인 새로운 구조의 자기-정렬된 ESD MOSFET의 분석)

  • 김경환;장민우;최우영
    • Journal of the Korean Institute of Telematics and Electronics D
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    • v.36D no.5
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    • pp.21-28
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    • 1999
  • A new method of making high speed self-aligned ESD (Elevated Source/Drain) MOSFET is proposed. Different from the conventional LDD (Lightly-Doped Drain) structure, the proposed ESD structure needs only one ion implantation step for the source/drain junctions, and makes it possible to modify the depth of the recessed channel by use of dry etching process. This structure alleviates hot-carrier stress by use of removable nitride sidewall spacers. Furthermore, the inverted sidewall spacers are used as a self-aligning mask to solve the self-align problem. Simulation results show that the impact ionization rate ($I_{SUB}/I_{D}$) is reduced and DIBL (Drain Induced Barrier Lowering) characteristics are improved by proper design of the structure parameters such as channel depth and sidewall spacer width. In addition, the use of removable nitride sidewall spacers also enhances hot-carrier characteristics by reducing the peak lateral electric field in the channel.

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