• Current Optics and Photonics
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• 제4권1호
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• pp.44-49
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• 2020

In this paper, a new method is presented to measure the refractive index of single plain glass or multilayered materials, based on a laser frequency-shifted confocal feedback microscope. Combining the laser frequency-shifted feedback technique and the confocal effect, the method can attain high axial-positioning accuracy, stability and sensitivity. Measurements of different samples are given, including N-BK7 glass, Silica plain glass, and a microfluidic chip with four layers. The results for N-BK7 glass and Silica plain glass show that the measurement uncertainty in the refractive index is better than 0.001. Meanwhile, the feasibility of this method for multilayered materials is tested. Compared to conventional methods, this system is more compact and has less difficulty in sample processing, and thus is promising for applications in the area of refractive-index measurement.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 가을 학술발표회 논문집
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• pp.98-101
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• 2003

The Alkali-Aggregate Reaction (AAR) may cause a serious failure in the concrete structures. Several researchers in some nations have performed the continuous studies to prevent failure of a concrete structures by the AAR distress as well as the studies to manifest the mechanism. The ASTM Standards to prevent failure by potential AAR aggregates were established in 1950. The KS F2545 and KS F 2546 were established to test the susceptibility of aggregate to potential AAR in 1982. But the researches on the AAR have not been performed affluently in Korea because the distress due to AAR has seldom been reported officially. In this study, the Chemical Method and Scanning Electron Microscopy (SEM) were used to verifying the cause of the pattern crack on the surface and internal crack in the plain concrete pavement. It can be concluded that the distress of a specific site in plain concrete pavement was mainly due to AAR, and the chemical method and SEM may be the effective tools for verifying the cause of AAR distresses.

• 한국유체기계학회 논문집
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• 제9권3호
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• pp.14-21
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• 2006

Leakage reduction through annular type seals of turbomachinery is necessary for enhancing their efficiency and the precise prediction method of seal leakage is needed. The analysis based on Bulk-flow concept has been mainly used in predicting seal leakage. However, full Navier-Stokes Equations with turbulent model derived in the seal flow passage have to be solved for improving the prediction of seal leakage. FLUENT 6 which is commercial CFD(Computational Fluid Dynamics) code based on FVM(Finite Volume Method) and SIMPLE algorism has been used to analyze leakage of various non-contact-type seals in this presentation. Comparing with the results of Bulk-flow model analysis and experiment, the result of CFD analysis shows good agreement with that of existing theoretical analysis for the incompressible grooved seal and compressive plain and staggered seal. The CFD analysis also shows improvement on the leakage prediction of the incompressible plain seal and compressive see-through-type labyrinth seal.

• 대한가정학회지
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• 제33권4호
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• pp.149-155
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• 1995

In this study, the formative property of flare skirts is carry out by the shape horizontal sections of hem line. Flare skirts was made by 10 kinds of fabrics with different physical properties. the length of flare skirts was 60cm. The main results obtained are as follows ; 1, The shape horizontal sections of hem line has differed with number of nodes and fabrics properties, in direction of texture. 2. According to the fabrics analysis of drapability decreased in order from Polyester/nylon(20/80)>Polyester(twill, thickness 0.2441)>Polyester(plain, thickness0.3760)>Polyester(plain, thickness 0.3687)>Polyester(plain, thickness 0.3101). 3. The correlation between the number of nodes and wave-height of modes and breadth showed a high negative correlation with the drapability of fabrics.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2003년도 추계학술발표대회 논문집
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• pp.83-86
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• 2003

Complete prediction of second order permeability tensor for three dimensional preform such as plain woven fabric and braided preform is critical to understand the resin transfer molding process of composites. The permeability can be obtained by various methods such as analytic, numerical, and experimental methods. For several decades, the permeability has studied numerically to avoid practical difficulty of many experiments. However, the predicted permeabilities are a bit wrong compared with experimentally measured data. In this study, numerical calculation of permeability was conducted for two kinds of preforms i.e., plain woven fabric and circular braided preform. In order to consider intra-tow flow in the unit cell of preform the proposed flow coupled model was used for plain woven fabric and the Brinkman equation was solved in the case of the braided preform.

• 대한기계학회논문집
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• 제8권2호
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• pp.141-144
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• 1984

본 연구에서는 완전 역 피로응력(completely reversed fatgue stress)를 받는 타원 노치에서 균열 발생과 전파에 대한 이론 임계 피로 한도를 응력 세기 계수 개념 을 도입하여 임의의 재질과 임으의 타원 노치 형상에 대해서 적용할 수 있도록 유도하 며 그 결과는 기존 이론보다 Frost의 실험치에 더 잘 일치함을 보이고자 한다.

• 복식
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• 제49권
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• pp.85-94
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• 1999

The fabrics attached to the remains of the Okjeon old tomb in the Kaya period were examined. Most of fabrics examined were composed of hemp and silk. Considering that silk was found in the old tomb of the Kaya period in the late 5th century and that various kinds of silk were used in the other area silk was assumed to be used before 5th century in the Kaya period. Only the structure of the densely plain weaved fabrics were analysed as silk and the other physical properties of the fabrics could not be the examined fabrics were plain weaved and altered structure with twill and plain weaving were found indicating that diverse weaving structures were used in the Kaya period. This indicate a certain level of cultural exchange between Kaya and Silla PaikJae, Kokuryo and weaving technique were almost similar in the Korean peninsula in the 5th century.

• 대한기계학회논문집A
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• 제32권9호
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• pp.788-795
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• 2008

To understand the tensile behaviors of GFRP at low temperature, three types of specimen have been used in this study. Tensile properties and fracture mechanisms for three orthogonal orientations of plain weave glass fabric reinforced epoxy resin laminate were investigated at temperature range of about -30 to $15^{\circ}C$. The tensile properties of axial and edge type specimen decrease slightly with decreasing temperature to $-20^{\circ}C$. However, at $-30^{\circ}C$ the decreases in the tensile properties increased considerably. Below $-20^{\circ}C$, thickness type specimen showed a marked decreases in the tensile properties. It was obvious that the fracture manner of thickness type specimen was adhesive failure at above $-10^{\circ}C$ and a mixed adhesive and cohesive failure at below $-20^{\circ}C$.

• Advances in concrete construction
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• 제4권3호
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• pp.161-172
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• 2016

An experimental investigation was carried out on the strength and behavior plain and fiber reinforced geopolymer concrete beam column joints and the results were compared with plain and steel fiber reinforced conventional concrete beam column joints. The volume fraction of fibers used was 0.5%. A total of six Geopolymer concrete joints and four conventional concrete joints were cast and tested under reversed cyclic loading to evaluate the performance of the joints. First crack load, ultimate load, energy absorption capacity, energy dissipation capacity stiffness degradation and moment-curvature relation were evaluated from the test results. The comparison of test results revealed that the strength and behavior of plain and fiber reinforced geopolymer concrete beam column joints are marginally better than corresponding conventional concrete beam column joints.

• Journal of Magnetics
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• 제6권1호
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• pp.5-8
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• 2001

Cheju island is composed of volcanic tuff. The soil in Cheju island has principally sprung from basalt and partially made up of trachyte, and andesite. Also ancient relics, plain coarse pottery kilns and pantiles kilns are homogeneously distributed all over the Cheju island. In this study samples of plain coarse pottery and pantiles from five regions of Cheju island have been examined through X-ray fluorescence spectrometer and Mossbauer spectroscopy. It is thought that these samples be partially formed from neutral volcanic rock like trachyte and the valence state of iron is almost $Fe^{3+}$. Also the magnetic hyperfine field of goethite contained in these samples is less than synthetic goethite. This result shows the degradation of magnetic order caused by the partial substitution of diamagnetic positive ion $Fe^{3+}$ by $Al^{3+}$ in the goethite lattice.