• Clinical and Experimental Pediatrics
• /
• 제45권4호
• /
• pp.439-448
• /
• 2002

목 적 : 신생아 호중구 감소증이 합병된 신생아 패혈증 환아의 치료에 있어서 부가적으로 rhG-CSF(recombinant human granulocye colony-stimulating factor)를 투여함에 있어서 서로 다른 용량의 rhG-CSF를 투여함으로써 나타나는 신생아 패혈증에 합병된 호중구 감소증의 치료와 환아들의 생존율에 미치는 영향을 평가, 비교하려고 하였다(group I/II형 연구). 방 법: 1995년 10월부터 1996년까지 신생아 호중구 감소증이 합병된 신생아 패혈증 환아는 모두 10명으로 이들에게는 $10{\mu}g/kg$을 피하주사 하였고(rhG-CSF $10{\mu}g/kg$ 투여군), 1996년 10월부터 1997년 9 월까지는 신생아 호중구 감소증이 합병된 신생아 패혈증 환아는 모두 12명으로 이들에게는 rhG-CSF를 $5{\mu}g/kg$ 피하주사 하였다(rhG-CSF $5{\mu}g/kg$ 투여군). 각 군의 호중구 증가 정도와 임상적 결과를 서로 비교하였다. 결 과 : RhG-CSF $10{\mu}g/kg$ 투여군은 조발형 신생아 패혈증 1명과 지발형 신생아 패혈증 9명으로 이루어졌고, 모두에게 호중구 감소증이 합병되었다. rhG-CSF $5{\mu}g/kg$ 투여군은 조발형 신생아 패혈증 1명과 지발형 신생아 패혈증 11명이 대상이 되었고, 이들 모두 호중구 감소증이 합병되었다. 두 군간에 출생체중, 재태주령, 항생제 사용, 신생아 패혈증 시기에 기계적 환기요법 투여, 승압제로 dopamine 투여 또는 다른 지지적 요법의 투여에 있어서 차이가 없었다. rhG-CSF 투여 전의 순 호중구 수(ANC)는 rhG-CSF $10{\mu}g/kg$ 투여군이 $1,065{\pm}89$($mean{\pm}SEM$), $5{\mu}g/kg$ 투여군이 $1,053{\pm}131$로 차이가 없었다. 투여 후의 ANC의 증가는 rhG-CSF $10{\mu}g/kg$ 투여군과 $5{\mu}g/kg$ 투여군에서 각각 투여 후 24시간에 7배, 6배, 투여 후 48시간에 10배, 6배, 투여 후 72시간에 8배, 4배, 투여 후 120시간에 8배, 4배로 투여 전에 비하여 두 군 모두에서 각 시간에 의미 있는 증가를 보였다(repeated measure ANOVA와 Kruskall-Wallis test, within subjects effect). 그러나 두 군 간의 차이는 투여 후 48시간에 ANC 최고치에서만 의미 있는 차이를 보였다(student t-test와 Wilcoxon rank sum test). 단핵구 수도 이 기간 동안 의미 있게 증가하였으나 정상범위를 넘지는 않았다. rhG-CSF $10{\mu}g/kg$ 투여군에서 1명의 환아가 자의 퇴원하였고, 1명의 환아가 사망하여 신생아 패혈증에서 회복하여 문제없이 퇴원한 생존율은 자의 퇴원 환아를 제외한 9명 중 8명으로 88.9％였고, rhG-CSF $5{\mu}g/kg$ 투여 군은 12명 중 10명이 생존하여 생존율은 83.3%였다. 두 군 모두에서 특별한 독성이나 부작용은 관찰되지 않았다. 결 론 : RhG-CSF의 투여는 호중구 감소증이 합병된 극심한 신생아 패혈증 환아에서 호중구의 증가를 일으켰다. 두가지 투여 용량에 따르는 효과는 거의 동일하였으며, 단지 투여 후 48시간에 ANC 최고치에서만 의미 있는 차이가 있었다. 두 군의 생존율은 80%이상이었다. 이와 같은 호중구 감소증이 합병된 신생아 패혈증에서 rhG-CSF의 투여 효과는 골수 억압이나 호중구 소모에 의하여 호중구 감소증이 합병된 신생아 패혈증에서 시기적으로 적절히 투여하면 효과적인 치료를 이룰 수 있다는 것을 시사한다. 향후 rhG-CSF의 효능과 부작용에 대하여 무작위 대조실험이 필요시 된다.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
• /
• pp.189-189
• /
• 2008

Due to the environmental issue vast research is going on to replace the widely used lead contented piezoelectric materials. Bismuth sodium titanate (abbreviated as BNT) based bismuth sodium titanate-barium titanate (abbreviated as BNBT) ceramic was prepared by using modified method rather than conventional mixed oxide method. This modification was made to improve the properties of BNT based ceramic. In this procedure $BaTiO_3$ (abbreviated as BT) was prepared using conventional mixed oxide method. Analytical grade raw materials of $BaCO_3$ and $TiO_2$ were weighted and ball milled using ethanol medium. The mixed slurry was dried and sieved under 80 mesh. Then the powder was calcined at $1100^{\circ}C$ for 2 hours. This calcined BT powder was used in the preparation of BNBT. Stoichiometric amount of $Bi_2O_3$, $Na_2CO_3$, $TiO_2$ and BT were weighted and mixed by using ball mill. The used calcination temperature was $850^{\circ}C$ for 2 hours. Calcined powder was taken for another milling step. BNBT disks were pressed to 15 mm of diameter and then cold isostatical press (CIP) was used. Pressed samples were sintered at $1150^{\circ}C$ for 2 hours. The SEM microstructure analysis revealed that the grain shape of the sintered ceramic was polyhedral and grain boundary was well matched where as the sample prepared by conventional method showed irregular arrangement and grain boundary not well matched. And sintered density was better (5.78 g/cc) for the modified method. It was strongly observed that the properties of BNBT ceramic near MPB composition was found to be improved by the modified method compare to the conventional mixed oxide method. The piezoelectric constant dB of 177.33 pC/N, electromechanical coupling factor $k_p$ of 33.4%, dielectric constant $K_{33}^T$ of 688.237 and mechanical quality factor $Q_m$ of 109.37 was found.

• Advances in materials Research
• /
• 제1권2호
• /
• pp.147-160
• /
• 2012

In the present study, diffusion bonding was carried out between AZ31B magnesium and AA2024 aluminium in the temperature range of $405^{\circ}C$ to $475^{\circ}C$ for 15 min to 85 min and 5MPa to 20 MPa uniaxial loads was applied. Interface quality of the joints was assessed by microhardness and shear testing. Also, the bonding interfaces were analyzed by means of optical microscopy, scanning electron microscopy, energy dispersive spectrometer and XRD. The maximum bonding and shear strength was obtained at $440^{\circ}C$, 12 MPa and 70 min. The maximum hardness values were obtained from the area next to the interface in magnesium side of the joint. The hardness values were found to decrease with increasing distance from the interface in magnesium side while it remained constant in aluminium side. It was seen that the diffusion transition zone near the interface consists of various phases of $MgAl_2O_4$, $Mg_2SiO_4$ and $Al_2SiO_5$.

• Structural Engineering and Mechanics
• /
• 제9권4호
• /
• pp.323-338
• /
• 2000

An analytical approach for the prediction of the behaviour of steel-fiber reinforced concrete beams subjected to torsion is described. The analysis method employs a special stress-strain model with a non-linear post cracking branch for the material behaviour in tension. Predictions of this model for the behaviour of steel-fiber concrete in direct tension are also presented and compared with results from tests conducted for this reason. Further in this work, the validation of the proposed torsional analysis by providing comparisons between experimental curves and analytical predictions, is attempted. For this purpose a series of 10 steel-fiber concrete beams with various cross-sections and steel-fiber volume fractions tested in pure torsion, are reported here. Furthermore, experimental information compiled from works around the world are also used in an attempt to establish the validity of the described approach based on test results of a broad range of studies. From these comparisons it is demonstrated that the proposed analysis describes well the behaviour of steel-fiber concrete in pure torsion even in the case of elements with non-rectangular cross-sections.

• Structural Engineering and Mechanics
• /
• 제11권2호
• /
• pp.221-236
• /
• 2001

A local point interpolation method (LPIM) is presented for the stress analysis of two-dimensional solids. A local weak form is developed using the weighted residual method locally in two-dimensional solids. The polynomial interpolation, which is based only on a group of arbitrarily distributed nodes, is used to obtain shape functions. The LPIM equations are derived, based on the local weak form and point interpolation. Since the shape functions possess the Kronecker delta function property, the essential boundary condition can be implemented with ease as in the conventional finite element method (FEM). The presented LPIM method is a truly meshless method, as it does not need any element or mesh for both field interpolation and background integration. The implementation procedure is as simple as strong form formulation methods. The LPIM has been coded in FORTRAN. The validity and efficiency of the present LPIM formulation are demonstrated through example problems. It is found that the present LPIM is very easy to implement, and very robust for obtaining displacements and stresses of desired accuracy in solids.

• Structural Engineering and Mechanics
• /
• 제28권1호
• /
• pp.19-38
• /
• 2008

A general solution to the field equations of homogeneous isotropic generalized thermoelastic diffusion with two relaxation times (Green and Lindsay theory) has been obtained using the Fourier transform. Assuming the disturbances to be harmonically time.dependent, the transformed solution is obtained in the frequency domain. The application of a time harmonic concentrated and distributed loads have been considered to show the utility of the solution obtained. The transformed components of displacement, stress, temperature distribution and chemical potential distribution are inverted numerically, using a numerical inversion technique. Effect of diffusion on the resulting expressions have been depicted graphically for Green and Lindsay (G-L) and coupled (C-T) theories of thermoelasticity.

• Structural Engineering and Mechanics
• /
• 제66권5호
• /
• pp.595-608
• /
• 2018

This paper deals with the lateral - torsional motion of bridges provided with external cables acting as dampers under the action of horizontal dynamic loads or of walking human crowd loads. A three dimensional analysis is performed for the solution of the bridge models. The theoretical formulation is based on a continuum approach, which has been widely used in the literature to analyze bridges. The resulting equations of the uncoupled motion are solved using the Laplace Transformation, while the case of the coupled motion is solved through the use of the potential energy. Finally, characteristic examples are presented and useful results are obtained.

• Structural Engineering and Mechanics
• /
• 제46권3호
• /
• pp.433-445
• /
• 2013

Vibration-based structural identification has become an important tool for structural health monitoring and safety evaluation. However, various kinds of uncertainties (e.g., observation noise) involved in the field test data obstruct automation system identification for accurate and fast structural safety evaluation. A practical way including a data preprocessing procedure and a vector backward auto-regressive (VBAR) method has been investigated for practical bridge identification. The data preprocessing procedure serves to improve the data quality, which consists of multi-level uncertainty mitigation techniques. The VBAR method provides a determinative way to automatically distinguish structural modes from extraneous modes arising from uncertainty. Ambient test data of a cantilever beam is investigated to demonstrate how the proposed method automatically interprets vibration data for structural modal estimation. Especially, structural identification of a truss bridge using field test data is also performed to study the effectiveness of the proposed method for real bridge identification.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
• /
• pp.927-931
• /
• 2004

본 논문에서는 혈당측정기 제작에 있어 PDMS(Su-8)를 이용하였다. 이는 일종의 고분자로서 기계적 특성이 우수하고 제작이 간단하며, 가격이 저렴하고 다른 물질과의 접합이 용이하다. 혈액의 펌핑과 믹싱을 할 수 있도록 새로운 구조체를 설계하였으며 제안된 모델의 핵심 부분인 측정전극의 제작에 필요한 기초적인 실험을 수행하였다. 측정전극의 성능향상과 제작편의성, 저가격화를 위해 효소고정화방법으로 Electrospinning (전기방사)으로 제조된 PVA nanofiber web을 이용하였으며, 이는 중합도 Pn=1700, 비누화도 98%인 공업용으로 상용화된 값싼 제품이다. 따라서 이를 이용하면 측정용 전극의 효소고정화에 있어 저가격화를 이룰 수 있을 것으로 기대된다 고정화된 전극분석을 위해 SEM(주사전자현미경)과 NMR(핵자기공명분광계), FT-IR(적외선분광분석)장비를 사용하였다. 그리고 기존의 효소고정화법(전기중합법)과의 응답특성을 비교분석하였다.

• 한국정밀공학회지
• /
• 제29권11호
• /
• pp.1178-1182
• /
• 2012

The organic linings at flue gas desulfurization systems (FGD system) in power plant have the excellent chemical properties but, lose the anticorrosive properties according to the aging with environment conditions. The properties of the organic linings depend on the manufacturing company. Therefore, the basic properties of organic linings for the preestimate of life time should be examined by conducting the aging and the bond strength test according to temperature. The pre-aging samples were compared with the post-aging samples. The temperature conditions of the aging process were 70, 150 and $200^{\circ}C$. The bond strength was calculated and the cross sections of fracture surface were examined by optical microscope and SEM. The $T_g$ was examined by DSC, DTA and TGA.