• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2004년도 춘계학술대회
• /
• pp.186-191
• /
• 2004

we can say that the increasing range of the value of GMT Sheet's tensile strength in the direction of fiber orientation is getting wider as the fiber content increases. It shows that the value of GMT Sheet's tensile strength in the direction of fiber orientation 90 is similar with the value of pp's intensity when fiber orientation function is J= 0.7, regardless of the fiber content. Tensile strength of GMT Sheet is affected by the fiber orientation distribution more than by the fiber content.

• 한국섬유공학회:학술대회논문집
• /
• 한국섬유공학회 2003년도 가을 학술발표회 논문집
• /
• pp.112-113
• /
• 2003

한국섬유섬유산업에 있어서 섬유장에 대한 정보를 알아야 하는 이유로는 원료로부터 섬유를 분리 시키고, 길이 방향으로 배향시키며, 곧게 펼치는 과정에서 섬유의 절단을 최소화할 수 있는 기계의 조건을 산출하는데 있다. 또한 제품의 강도를 결정하는데 있어서 섬유의 길이는 중요한 역할을 한다. 그러나 섬유의 길이를 측정하는 데에는 많은 어려움이 있다. 그것은 섬유의 한올 한올의 길이를 측정하는 것은 쉽지만 수많은 섬유들을 빠른 속도로 측정해야하기 때문이다. (중략)

• 한국전기화학회:학술대회논문집
• /
• 한국전기화학회 2002년도 추계총회 및 학술발표회
• /
• pp.54-54
• /
• 2002

• 대한기계학회논문집A
• /
• 제27권3호
• /
• pp.440-449
• /
• 2003

Residual strength of fiber metal laminates after impact was studied. 3/4 lay up FML was fabricated using 4 ply prepreg, 2 ply aluminum sheets, and 1 ply steel sheet. Quasi isotropic ([0/45/90/-45]s) and orthotropic ([0/90/0/90]s) FRP were also fabricated to compare with FML. Impact test were conducted by using instrumented drop weight impact machine (Dynatup, Model 8250). Penetration load and absorbed energy of FML were superior to those of FRPs. Tensile tests were conducted to evaluate the residual strength after impact. Strength degradation of FML was less than that of FRP. This means that the damage tolerance of FML is excellent than that of FRP. Residual strength of each specimen was predicted by using Whitney and Nuismer(WN) Model. Impact damage area is assumed as a circular notch in WN model. Damage width is defined as the average of back face and top face damage width of each specimen. Average stress and point stress criterions were used to calculate the characteristic length. It is supposing that a characteristic length is a constant. The distribution of characteristic length shows that the assumption is reasonable. Prediction was well matched with experiment under both stress criterions.

• 한국항행학회논문지
• /
• 제21권2호
• /
• pp.187-192
• /
• 2017

단일 모드 광섬유 (SMF; single mode fiber)의 길이와 중계 구간 당 잉여 분산 (RDPS; residual dispersion per span)이 랜덤하게 분포하는 광 위상 공액과 결합된 분산 제어 (DM; dispersion management)가 적용된 장거리 (50 fiber spans ${\times}80km$) 전송 링크에서 SMF와 분산 보상 광섬유 (DCF; dispersion compensating fiber) 배열과 전체 잉여 분산 (NRD; net residual dispersion)을 조절하는 위치에 따른 왜곡된 WDM 채널의 보상 특성을 수치적으로 분석해 보았다. NRD 조절 위치는 중계 구간을 구성하는 SMF와 DCF의 배열과 관계되어 있지만, NRD 조절의 구체적 위치보다 중계 구간을 이루는 SMF와 DCF의 배열이 WDM 채널의 수신 성능에 영향을 미치는 것을 확인하였다.

• 한국연초학회지
• /
• 제27권2호
• /
• pp.163-170
• /
• 2005

A theoretical model for predicting the capability curve of cellulose acetate filter is derived. The pressure drop is expressed as a function of the filter dimensions, the tow fiber characteristics, the filter weight, the fluid flow rate, and a filter fiber factor. Where, the filter fiber factor is affected by the distribution of the tow fibers within the filter, the relative orientations of the tow fibers, and their cross-sectional shapes. The minimum and maximum fraction of solids in capability curves determined from experimental data. Also, the filter fiber factor is expressed as a function of the filter length, tow fiber length, and tow fiber diameter. Capability curves predicted by the suggested model in this work correspond well with capability curves by experimental data.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 1997년도 가을 학술발표회 논문집
• /
• pp.653-658
• /
• 1997

Recently, carbon Fiber sheet (CFS) is frequently used for strengthening deteriorated concrete structures. To strengthening damaged structures, the property and characteristic of the bond between CFS and the concrete surface must be understood. The tensile test of single lap shear specimen was performed to study bond strength, bond stress distribution and stress transfer between CFS and concrete surface according to the bond length. Based on the test results, there were ultimate influence length (UIL) in which bond stress was distributed, and ultimate strain reduction ratio (USRR) by which strain was reduced linearly. Bond resisting force (BRF) was estimated by UIL and USRR, and which was compared with ultimate loads. According to the results of comparison, it was shown that ultimate bond strength could be estimated reasonablely by BRF.

• 대한기계학회논문집
• /
• 제17권7호
• /
• pp.1740-1750
• /
• 1993

The aluminar short fiber reinforced composite materials for hot extrusion were fabricated by semi-solid stirring method, and extruded at extrusion temperature $400^{\circ}C$ with various extrusion ratio. The hot extrusion load of volume fraction 15% metal matrix composites and base alloy Al7075 has been compared. The fiber length distribution, fiber breakage and fiber orientation are investiged to know the fiber behaviour in before and after hot extrusion. The tensile strength of the hot extruded billet are experimentally determined for different of extrusion ratios, and compared with theorically calculated strength.

• Computers and Concrete
• /
• 제34권3호
• /
• pp.367-378
• /
• 2024

This study evaluates the direct tensile strength of ultra-high-performance concrete (UHPC) using tests. A total of 45 dogbone-shaped specimens are tested, with the test variables being the fiber volume fraction and notch length. The test results showed that the material properties of UHPC were largely dependent on the fiber volume fraction and compressive strength. When steel fibers with more than 1% fiber volume fraction are mixed in the manufacturing of UHPC, the tensile strength can be more than twice that of plain UHPC. In addition, the incorporation of steel fibers enabled the significant improvement of the initial cracking strength. However, the effect of the notch length on the tensile behavior was insignificant. An assessment of the direct tensile strength is conducted using machine-learning algorithms (ML). For evaluation of the direct tensile strength of UHPC using ML, a total of 98 test data, including 53 data from other research works and 45 data from this experimental program, were collected. In total, 67 data with a 70% confidence interval on a normal distribution curve were selected, with 47 data among 67 used for ML training and 20 data used for ML testing. As a result, the machine-learning algorithm with a steel fiber volume fraction predicted that the tensile strength has an average of 0.98 and the lowest values of regression evaluation metrics among analytical and ML-based models. It is considered that an ML-based model can help to predict a more accurate tensile strength of UHPC.

• 한국정보통신학회:학술대회논문집
• /
• 한국정보통신학회 2013년도 추계학술대회
• /
• pp.975-977
• /
• 2013

그룹 속도 분산과 비선형 효과의 상호 작용에 의해 왜곡되는 WDM 신호의 보상을 위해 전체 전송로 중간에 광 위상 공액기 (optical phase conjugator)가 적용되고 중계 구간의 단일 모드 광섬유(SMF; single mode fiber) 길이와 RDPS(residual dispersion per span)를 인위적으로 분포하는 광전송 링크의 최적 분포 패턴을 도출하였다. 최적의 전체 잉여 분산 (NRD; net residual dispersion)인 10 ps/nm와 -10 ps/nm로 설계된 링크에서 중계 구간이 증가할수록 SMF 길이는 점차 감소시키고, RDPS는 점차 증가시키는 분포가 균일한 분포에 비해 성능 면에서 우수한 것을 확인하였다.