• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계 학술발표회 논문집(II)
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• pp.365-368
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• 2006

In this paper, the post cracking stress-crack width relationship of the composite is studied from a micromechanics points of view. Cook-Gordon debonding effect is studied by more refined method with considering of chemical friction of fiber interface. As a result, fiber with pre-debonding length retards stress development and shows more wide crack width for the same force level. longer pre-debonding length and lower pre-debonding bond strength results in lower full-debonding force, but same crack width.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(I)
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• pp.123-126
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• 2005

The purpose of this study is to evaluate a effect of core reinforcement ratio to PC wide girder-column joint. Three half scale subassemblies were representing a portion of a protype structure were design, constructed, and tested to failure. From the test result, girder-column width ratio play an important role in the improvement of strength and ductility.

• 소성∙가공
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• 제6권3호
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• pp.203-212
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• 1997

In this research, to obtain the optimal die width of CV die(conventional die), which replaces FM die in free forging of large scale rotor using the flat die, the model material experiments and theoretical analysis using three dimensional FEM are performed. The FM die, which was designed to remove Mannesmann's effect at the central part of the ingot, has very bad workabiltity in real field, therefore on the empirical base they use the CV die of wide width in actual working field. In this study, the excellency of CV die is proved quantitively, and the optimal die width of CV die is determined through the model material experiments and theoretical analysis using FEM in the point of effective strain, stresses, and load.

• 한국전산구조공학회논문집
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• 제29권3호
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• pp.269-275
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• 2016

본 논문은 유공형 판 형태로 전단 보강한 넓은 보의 중심에 기둥을 삽입하여 연속한 두 경간으로 설계하여 전단파괴 실험을 통해 넓은 보의 거동을 평가하였다. 유공형 강판으로 전단 보강된 시험체 5개와 유공형 GFRP판으로 보강된 시험체 3개 총 8개의 시험체를 전단파괴 실험을 통해 계측한 전단강도와 ACI-318 규준의 설계식을 통해 얻은 전단강도와 비교 평가하였다. 또한 넓은 보의 지지부 폭, 지지부의 형상과 전단보강재의 재료를 변수로 하여 넓은 보의 전단강도에 미치는 영향을 분석하였다. 이를 통해 지지부 폭이 증가할수록 전단강도가 증가하고 하중의 집중을 방지하는 것을 확인하였다. 또한 전단보강재의 재료인 강재와 GFRP에 상관없이 전단보강량이 동일하다면 넓은 보에서 비슷한 전단보강효과를 보이는 것을 확인하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 춘계학술대회 논문집 전자세라믹스 센서 및 박막재료 반도체재료 일렉트렛트 및 응용기술
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• pp.10-13
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• 2000

The notching effect in etching of un doped amorphous silicon gate had different characteristics and mechanism comparing with reported ones. The undoped amorphous silicon was etched by using HBr gas plasma, First, in the region of small line width, the potential was increased as a result of ions in the exposed surface of oxide, and the incident ions between the small line width were deflected more wide range, therefore the depth of notching was shallow and wide, Second, in the region of large line width of gate, electrons were charged on the top of photoresist and the side of gate, a part of ions deflected, The deflected ions were locally charged positive on the side of gate, and then the potential difference was produced, therefore, ions stored up more at independent line than at dense line, and nothing became deeper by Br ion bombardment.

• 한국지반공학회논문집
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• 제24권1호
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• pp.71-80
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• 2008

본 논문에서는 보강토 구조물에 보강재로 적용되는 지오그리드의 시간 의존적 변형거동 특성에 대한 광폭 인장시험 결과를 제시하였다. 먼저, 다양한 보강재의 종류에 대해 인장속도에 따른 파단강도 및 강성의 변화에 대해 알아보았다. 또한 보강토 구조물이 사용연한 동안 받게될 다양한 하중 조건, 즉 지속하중 및 반복하중을 작용시킬 수 있는 장비를 특수 제작하여 지오그리드의 시간의존적 변형거동을 분석하였다. 그 결과 지속하중 및 반복하중 작용시 잔류변형은 보강재의 점성(viscous) 특성의 형태로서 쌍곡선 특성 곡선으로 잘 모사되는 것으로 분석되었으며 이러한 잔류변형은 시간의존적 점성거동의 측면에서 다루어야 하는 것으로 나타났다.

• Restorative Dentistry and Endodontics
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• 제27권4호
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• pp.403-410
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• 2002

Several ways of curing are being tried to improve material's properties and reduce marginal gap. However, all are considering about the pattern of light intensity. It was noted from the preliminary study the change of light wavelength from filter changing may give an impact on material's property and microleakage. The object of this study was to verify the effect of filters with various wavelength width on the microhardness and microleakage of composite resin ; hybrid type of DenFil and submicron hybrid type of Esthet X. Composite resins were cured using 3 kinds of filter; narrow-banded(465-475 nm), mid-banded(430-470 nm), wide-banded(400-500 nm). After the estimation of microhardness. degree of dye penetration and the maximum gap from SEM evaluation were done between 4 groups that showed no difference in microhardness value of the lower surface . The results were as follows : 1 Adequate microhardness could not be gained with a narrow-banded filter irrespective of curing time. At the upper surface, DenFil should be polymerized with middle or wide-banded filter for 20 seconds at least, while Esthet X be col$.$ed with middle or wide-banded filter for 30 seconds at least to get simitar hardness value to control group. 2. There was little dye penetration in enamel margin, but all dentin margins skewed much more dye penetration irrespective of curing conditions. Although there was no statistical difference, groups cured with mid-banded filter for 40 seconds and with wide-width filter for 20 seconds showed relatively less dye penetration. 3. It was revealed from the SEM examination that group cured with wide-banded filter had the smallest gap without statistical significance. Spearman's rho test showed that the correlation between the results of dye penetration and SEM examination was very low. From these results, it could be concluded that curing with wide-width filter would be better than the other techniques, even though the curing technique using mid-width filter seems to have its own unique advantage.

• 전기학회논문지P
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• 제60권2호
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• pp.53-55
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• 2011

The printed wide band monopole antenna having characteristics of dipole by modified coplanar wave guide(CPW) ground plane is presented. We are called a slot-arm printed monopole antenna and investigated the effect of the surface currents of the radiator on ground plane. The proposed antenna is treated as two asymmetric dipoles with the included angle of $90^{\circ}$ degrees which lie along Z-direction symmetrically. It is observed that the effect of the surface currents on the radiation patterns is similar to that of the corresponding dipole. The length and width of the ground plane correspond the radius and length of the dipole respectively. This approach is also valid to general printed monopole antennas. The simulation impedance bandwidth of the proposed antenna the range of 2.4 to 4.6 [GHz] for a voltage stand wave ratio (VSWR)${\leq}$2 and got pick gain of 6 [dBi]. So the proposed antenna is satisfied the requirement of the industry science medical (ISM) band operation.

• ETRI Journal
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• 제33권3호
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• pp.335-343
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• 2011

The pad pitch of modern radio frequency integrated circuits is in the order of few tens of micrometers. Connecting a large number of high-speed I/Os to the outside world with good signal fidelity at low cost is an extremely challenging task. To cope with this requirement, we need reflection-free transmission lines from an on-chip pad to on-board SMA connectors. Such a transmission line is very hard to design due to the difference in on-chip and on-board feature size and the requirement for extremely large bandwidth. In this paper, we propose the use of narrow tracks close to chip and wide tracks away from the chip. This narrow-to-wide transition in width results in impedance discontinuity. A step change in substrate thickness is utilized to cancel the effect of the width discontinuity, thus achieving a reflection-free microstrip. To verify the concept, several microstrips were designed on multilayer FR4 PCB without any additional manufacturing steps. The TDR measurements reveal that the impedance variation is less than 3 ${\Omega}$ for a 50 ${\Omega}$ microstrip and S11 better than -9 dB for the frequency range 1 GHz to 6 GHz when the width changes from 165 ${\mu}m$ to 940 ${\mu}m$, and substrate thickness changes from 100 ${\mu}m$ to 500 ${\mu}m$.

• Steel and Composite Structures
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• 제15권6호
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• pp.605-621
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• 2013

CFRP strips are widely used nowadays for repair/strengthening or capacity increase purposes. Sharp bending at the ends of the CFRP strips is frequently encountered at these applications. In this study, Reinforced Concrete (RC) beam specimens that were produced with 10 MPa compression strength concrete were strengthened by using bonded CFRP strips with end anchorages to tension region. The parameters that were investigated in this study are the width of the strip, the number of applied fan anchorages and whether additional layer of CFRP patch is used or not at the strip ends. Specimens were strengthened with 100 mm wide CFRP strips with one or two anchorages at the ends. In addition CFRP patch with two and three anchorages at the ends were tested for investigating the effect of the patches. Specimens that were strengthened with three anchorages at the ends with patches were repeated with 60 and 80 mm wide CFRP strips. The most successful result was obtained from the specimen that was strengthened with 80 mm wide CFRP strips with 3 end anchorages and patches among the others at the experimental program. The numbers of anchorages that were applied to ends of CFRP strips were more effective than the width of the CFRP strips onto strength and stiffness of the specimens. Due to limited space at the ends of the strips at most three anchorages could be applied.