• Computers and Concrete
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• 제19권5호
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• pp.579-588
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• 2017

Creep and shrinkage are the main types of volume change with time in concrete. These changes cause deflection, cracking and stresses that affect durability, serviceability, long-term reliability and structural integrity of civil engineering infrastructure. Although laboratory test may be undertaken to determine the deformation properties of concrete, these are time-consuming, often expensive and generally not a practical option. Therefore, relatively simple empirically design code models are relied to predict the creep strain. This paper reviews the accuracy of creep and shrinkage predictions of reinforced concrete (RC) shear walls structures strengthened with carbon fibre reinforced polymer (CFRP) plates, which is characterized by a widthwise varying fibre volume fraction. This review is yielded by three commonly used international "code type" models. The assessed are the: CEB-FIP MC 90 model, ACI 209 model and Bazant & Baweja (B3) model. The time-dependent behavior was investigated to analyze their seismic behavior. In the numerical formulation, the adherents and the adhesives are all modelled as shear wall elements, using the mixed finite element method. Several tests were used to demonstrate the accuracy and effectiveness of the proposed method. Numerical results from the present analysis are presented to illustrate the significance of the time-dependency of the lateral displacements and eigenfrequencies modes.

• Advances in concrete construction
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• 제7권3호
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• pp.151-166
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• 2019

This paper introduces a new efficient analytical method, based on shear deformations obtained with 2D elasticity theory approach, to perform an explicit closed-form solution for calculation the interfacial shear and normal stresses in plated RC beam. The materials of plate, necessary for the reinforcement of the beam, are in general made with fiber reinforced polymers (Carbon or Glass) or steel. The experimental tests showed that at the ends of the plate, high shear and normal stresses are developed, consequently a debonding phenomenon at this position produce a sudden failure of the soffit plate. The interfacial stresses play a significant role in understanding this premature debonding failure of such repaired structures. In order to efficiently model the calculation of the interfacial stresses we have integrated the effect of shear deformations using the equilibrium equations of the elasticity. The approach of this method includes stress-strain and strain-displacement relationships for the adhesive and adherends. The use of the stresses continuity conditions at interfaces between the adhesive and adherents, results pair of second-order and fourth-order coupled ordinary differential equations. The analytical solution for this coupled differential equations give new explicit closed-form solution including shear deformations effects. This new solution is indented for applications of all plated beam. Finally, numerical results obtained with this method are in agreement of the existing solutions and the experimental results.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 춘계학술대회논문집
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• pp.911-916
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• 2001

Structural acoustic modification method based on the structural mobility analysis is applied to reduce the structure-borne noise radiated from hard disk drive system. Sound intensity techniques and ODS(Operational Deflection Shape) techniques are also used in order to provide the structural acoustic information for the mobility modification. The sound intensity is for the acoustic visualization of the noise source locations, and the ODS is for the visualization of the vibration pattern and its dynamic characteristics of the noise sources. Using visualization information of sound and vibration, local structural input mobility is reduced in the frequency band of interest by designing asymmetrical wave-stringer structure in the wave-number domain as well as frequency domain. The overall sound pressure level is reduced by 4dB and its controlled sound power radiated from the disk drive is proved to under 2.8Bel in idle-spinning mode and 3.1 Bel in random-seeking mode, which are the lowest noise levels in the hard disk drive industry.

• Asian-Australasian Journal of Animal Sciences
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• 제28권3호
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• pp.369-373
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• 2015

An experiment was conducted to determine the effect of cellulose concentration in diets containing no phosphorus (P) on the basal endogenous loss (BEL) of P in growing pigs. Twelve barrows (an initial mean body weight = $49.6{\pm}3.2kg$) were individually housed in metabolism crates. Pigs were allotted to 4 experimental diets according to a cross-over design with 12 animals and 2 periods. Four P-free diets were mainly based on corn starch, sucrose, and gelatin, and were formulated to contain 0%, 4%, 8%, or 12% cellulose. Each period consisted of a 5-d adaptation and a 5-d collection period. The marker-to-marker method was used for fecal collection. The feed intake (p<0.05, linear and quadratic) and dry feces output (p<0.01, linear and quadratic) were increased with increasing dietary cellulose concentration. However, P concentration in the feces was decreased (p<0.01, linear and quadratic) with increasing dietary cellulose concentration. There was no significant difference in total P output and the BEL of P as mg per kg DMI (ranging from 157 to 214 mg/kg of dry matter intake) among experimental diets. However, values for the apparent total tract digestibility of energy, dry matter, organic matter, crude protein, and calcium were linearly decreased (p<0.01) with increasing cellulose concentration in the diet. In conclusion, dietary cellulose affected the amount of feces and digestibility of energy and nutrients, but did not affect the endogenous loss of P.

• Bulletin of the Korean Chemical Society
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• 제34권5호
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• pp.1349-1354
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• 2013

Twenty two new 5-fluorouracil (5-FU) derivatives, 2-butoxy-4-substituted 5-fluoropyrimidines, were synthesized and characterized by IR, $^1H$ NMR, MS, HRMS. All compounds were preliminarily evaluated by MTT assay on human liver BEL-7402 cancer cell line in vitro. Ten compounds were selected to test their cytotoxic activity against A549, HL-60 and MCF-7 cancer cell lines in vitro. These compounds were more sensitive to BEL-7402 than other cell lines, particularly, cytotoxic activity of compounds 6b, 6d-f, 6p, 6s-u were in sub-micromolar scale. The highest cytotoxic potency against A549, HL-60 and MCF-7 was shown by 2-butoxy-4-chloro-5-fluoropyrimidine (5) with $IC_{50}$ values of 0.10, 1.66 and $0.59{\mu}M$, respectively. Compounds 6d and 6e were effective against MCF-7 with $IC_{50}$ $9.73{\mu}M$ and HL-60 with $IC_{50}$ $8.83{\mu}M$, respectively.

• Kyungpook Mathematical Journal
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• 제56권3호
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• pp.819-829
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• 2016

In this paper, we study the order of growth of solutions to the non-homogeneous linear differential equation $$f^{(k)}+A_{k-1}e^{az}f^{(k-1)}+{\cdots}+A_1e^{az}f^{\prime}+A_0e^{az}f=F_1e^{az}+F_2e^{bz}$$, where $A_j(z)$ (${\not\equiv}0$) ($j=0,1,{\cdots},k-1$), $F_j(z)$ (${\not\equiv}0$) (j = 1, 2) are entire functions and a, b are complex numbers such that $ab(a-b){\neq}0$.

• Advances in aircraft and spacecraft science
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• 제11권1호
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• pp.1-21
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• 2024

The stiffness reduction of cross-ply composite laminates featuring a transverse cracking and delamination within the mid-layer is predicted through utilization of a modified shear-lag model, incorporating a stress perturbation function. Good agreement is obtained by comparing the prediction models and experimental data. The material characteristics of the composite are affected by fluctuations in temperature and transient moisture concentration distribution in desorption case, based on a micro-mechanical model of laminates. The transient and non-uniform moisture concentration distribution induces a stiffness reduction. The obtained results demonstrate the stiffness degradation dependence on factors such as cracks density, thickness ratio and environmental conditions. The present study underscores the significance of comprehending the degradation of material properties in the failure progression of laminates, particularly in instances of extensive delamination growth.

• 한국전자파학회논문지
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• 제10권5호
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• pp.653-662
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• 1999

본 논문에서는 부고조파를 이용한 주입 동기 발진기를 설계, 제작하였다. 발진기는 Two Signal Method ( (TSM)의 방법을 사용하여 직렬 궤환회로로 설계하였다. 발진기의 발진주파수 9.4 GHz에서 출력전력 6dBm으 로 free-running하고 었고, 입력선호가 들어가연 주파수가 체배되어 locking되었다. 이때 원하는 출력 파형의 크 기는 다른 부고조파 신호에 비해 최소 40dB 이상이며, 2차 부고조파를 이용한 경우 locking range는 최대 220 MHz 정도이고,4차 부고조파를 이용한 경우 10 MHz이었다 이때의 위상잡음은 각각 100 KHz offset에서 -111dBe/Hz, - 104 dBelHz 정도의 특성을 나타내었다.

• 원예과학기술지
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• 제34권2호
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• pp.331-341
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• 2016

본 연구는 기능성 지표물질 확인을 위한 동양란 심비디움(Cymbidium) 향기 성분 비교 분석을 목적으로 하며, GC/MS 방법을 사용하여 한국춘란(Cymbidium goerigii L.), 중국춘란(C. forrestii R.)과 일경구화(C. faberi R.)의 향기성분을 비교 분석하였다. 분석은 한국춘란으로 '민춘란', '주금화', 중국춘란으로 '취개', '송매', '용자', 일경구화로 '최매', '남양매', '화자'등을 사용하였다. GC/MS 방법을 통해 검출된 성분들을 peak area(%)값 분석을 사용하여 3%이상의 주요 향기성분으로 분류하였다. 향기 성분 분석 결과 한국춘란에서는 유방암, 자궁경부암, 교모세포종암에 세포독성 기능성을 가진 ${\alpha}$-bergamotene과, 인체 간암 세포(HepG2)의 사멸과 성장 억제, 항진균제 및 바베스열원충, 충치균에 대한 억제 기능성을 가진 nerolidol이 가장 많았다. 중국 춘란에서는 nerolidol과 악성 흑색종 세포(B16-F10), 인체 간암 세포와 백혈병 세포(HL-60, K562)의 사멸과 억제 등의 기능성을 가진 ${\beta}$-bisabolene이 가장 많았다. 일경구화에서는 교모세포종(SF-767)의 억제와 간암세포주(BEL-7402)에 소염작용 억제 효과를 가진 ${\alpha}$-pinene, 위장 보호 효과 기능을 가진 1,8-cineole과 페로몬의 기능을 가진 1,3,7-octatriene이 가장 많았다. 이상에서 동양란의 주요 향기 성분으로 밝혀진 물질들은 인간에게 유익한 다양한 기능성을 갖고 있는 것으로 확인되었다.

• Journal of Genetic Medicine
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• 제8권1호
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• pp.53-57
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• 2011

목 적: 윌슨병은 간조직에 구리의 과도한 침착으로 발병하는 상염색체 열성 유전질환이다. 지금까지 ATP7B 유전자가 유일한 원인유전자로 알려져 왔다. 그러나, 약 15%의 환자에서는 ATP7B 유전자 돌연변이가 발견되지 않는다. 본 연구는 ATP7B 유전자의 돌연변이가 발견되지 않은 윌슨병 환자를 대상으로 새로운 원인 유전자를 발견하기 위하여 시행되었다. 대상 및 방법: ATP7B 돌연변이가 발견되지 않은 12명의 윌슨병 환자를 대상으로 ATP7B 와 상호작용을 하는 것으로 알려진 ATOX1, COMMD1, GLRX, DCTN4와 ZBTB16 유전자의 전사부위와 엑손-인트론 경계부위의 염기서열을 분석하였다. 결 과: DCTN4 유전자의 12번 엑손에 존재하는 c.1084A>G(p.Thr362Ala)를 포함하는 3가지의 변이가 환자에서 발견되었다. in silico 분석을 통해 3가지 변이 중 c.1084A>G가 유일하게 단백질 기능 변화를 일으킬 것으로 예측되었다. 176명의 윌슨병 환자와 414명의 정상인을 대상으로 이 변이의 빈도를 조사한 결과, 정상인보다 윌슨병 환자에서 더 높은 빈도를 나타내었다(상대비, odds ratio [OR]=3.14, 95% 신뢰도=1.36-7.22, P=0.0094). 결 론: 본 연구의 결과는 ATP7B 와 상호작용하는 DCTN4 유전자의 c.1084A>G (p.Thr362Ala) 다형성이 윌슨병의 발병과 연관이 있음을 시사한다.