• 대한조선학회논문집
• /
• 제47권3호
• /
• pp.369-376
• /
• 2010

In this study, a radiation and a diffraction problems of a floating body in two-layer fluids were solved by the Numerical Wave Tank(NWT) technique in the frequency domain. In two-layer fluids, two different wave modes exist and the hydrodynamic coefficients can be obtained separately for each mode. The two-domain Boundary Element Method(BEM) in the potential fluid using the whole-domain matrix scheme was used to investigate the characteristics of wave forces, added mass and damping coefficients. The effects of the ratio of density and water depth in the lower domain were also evaluated and compared with given references.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2003년도 봄 학술발표회 논문집
• /
• pp.822-827
• /
• 2003

This study was performed to evaluate the internal and external factors affecting external strength of the 3-layer polymer composite pipes made of polymer mortar and fiber-glass reinforced plastic. Twenty four sandwich type 3-layer polymer composite pipes were made of polymer mortar and fiber-glass reinforced plastic by centrifugal method. The objective of this study was to evaluate the effects the of polymer mortar thickness for and core fiber-glass contents per unit area on external strength of 3-layer polymer composite pipes. For the more economical and practical design of 3-layer polymer composite pipe, further study should be done for the various polymer mortar, fiber-glass and different ratio of the inside/outside FRP thickness.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
• /
• pp.346.2-346.2
• /
• 2014

To use the GaN based light-emitting diodes (LEDs) as solid state lighting sources, the improvement of light extraction and internal quantum efficiency is essential factors for high brightness LEDs. In this study, we suggested the new materials system of a zinc tin oxide (ZTO) layer formed on blue LED epi-structures to improve the light extraction. ZTO is a representative n-type oxide material consisted of ZnO and SnO system. Moreover, ZTO is one of the promising oxide semiconductor material. Even though ZTO has higher chemical stability than IGZO owing to its SnO2 content this has high mobility and high reliability. After formation of ZTO layer on p-GaN layer by using the spin coating method, structural and optical properties are investigated. The x-ray diffraction (XRD) measurement results show the successful formation of ZTO. The photoluminescence (PL) and absorption spectrum shows that it has 3.6-4.1eV band gap. Finally, the light extraction properties of ZTO/LED chip using electroluminescence (EL) measurement were investigated. The experimental and theoretical analyses were simultaneously conducted.

• 열처리공학회지
• /
• 제30권5호
• /
• pp.207-214
• /
• 2017

In this study, failure behavior of piercing plug for seamless tube manufacturing process was studied. Three different kinds of passed piercing plugs (10, 90, 215 times) were prepared. The shape deformation of the passed piercing plugs was observed by 3D coordinate measuring machine, and the oxidized layer on the surface of piercing plug was observed by optical microscopy. The length reduction of piercing plug presented at 215 times passed plug. It was found that the oxidized layer consisted of outer scale, inner scale and internal oxidation layers, and the inner scale layer had vertical cracks, and interfaces had horizontal cracks. We proposed the failure mechanism of piercing plug during seamless tube manufacturing process based on the formation of vertical and horizontal crack.

• Journal of the Korean Wood Science and Technology
• /
• 제51권4호
• /
• pp.239-252
• /
• 2023

In this study, bending and compression strength tests were performed to investigate effect of composition of layer layout of Larix cross-laminated timber (CLT) on mechanical properties. The Larix CLT consists of five laminae, and specimens were classified into four types according to grade and composition of layer. The layer's layout were composited as follows 1) cross-laminating layers in major and minor direction (Type A), and 2) cross-laminating external layer in major direction and internal layer applied grade of layer in minor direction (Type B). E12 and E16 were used as grades of lamina for major direction layer of Type A and external layer of Type B according to KS F 3020. In results of the bending test of CLT using same grade layer according to layer composition, the modulus of elasticity (MOE) of Type B was higher than Type A. In case of prediction of bending MOE of Larix CLT, the experimental MOE was higher than 1.00 to 1.09 times for Shear analogy method and 1.14 to 1.25 times for Gamma method. Therefore, it is recommended to predict the bending MOE for Larix CLT by shear analogy method. Compression strength of CLT in accordance with layer composition was measured to be 2% and 9% higher for Type A using E12 and E16 layers than Type B, respectively. In failure mode of Type A, progress direction of failure generated under compression load was confirmed to transfer from major layer to minor layer by rolling shear or bonding line failure due to the middle lamina in major direction.

• Steel and Composite Structures
• /
• 제52권6호
• /
• pp.663-672
• /
• 2024

This paper researched on the bending vibration characteristics of composite drive shaft with internal damping. To analyze the unbalanced excitation response in full speed range, a transfer matrix model was built based on the improved Layer-wise theory and the numerical damping, and compared with the metal drive shaft. The results show that the effect of internal damping of the composite shaft tube on bending vibration response was different in the subcritical, critical and supercritical speed ranges. Then, the finite element analysis and vibration tests were carried out to verify the analysis results of transfer matrix model.

• 한국해양학회지
• /
• 제29권3호
• /
• pp.296-303
• /
• 1994

회전하는 원통형 이층 유체에 하층 유체와 동일한 밀도의 유체를 경사진 하층 바 닥의 둘레를 통하여 주입시 하층 내부는 일정한 수직 운동을 하게 되며 이러한 수직운 동은 결국 하층 유체에 Sverdrup type의 운동인 남향의 서안 경계류와 북향의 내부 운 동을 발생시킨다. 이때 $\beta$-효과와 동시에 하층 유체가 상층 경계면과 만나게 하므로써 소위 극전선 효과를 갖고 있는 상층 유체의 운동 특성을 관찰하였다. 서안에서 의 순 압성, 동안에서 의 경압성 운동이 뚜렷하게 나타나고 특히 동안 경계류의 남향과 서안 경계류의 남향은 서안에서 의 이안 현상을 야기시킨다. 상층에 $\beta$-효과를 증가시 서안 경계류의 폭이 감소하는 이안 현상후 내부에 "eddy" 모양의 흐름이 존재한다. 한편 경압성 Rossby wave는 동안 부근에서 뚜렷하게 관측되나 서쪽으로 진행하면서 소멸되 는 현상이 관측되었다. 하층 유체에 국지적 지형 효과서 준 경우 상층수의 서안 경계 류 및 동안 경계류가 민감하게 반응하여 동안에서는 정상파 형태의 운동이 나타나고 서안에서는 이안 현상 없이 경계류의 폭이 증가함을 보인다. 이는 하층의 순압성 운동 이 지형 효과를 느끼는 반면, 그 영향은 상층에 직접전달되지 못하고 있음을 보여주고 있는 것이라 사료된다. 상층의 $\beta$-효과 증가시 internal radius보다 훨씬 큰 규모의 파형이 내부에 존재하는 특성을 보여 주고 있다. 보여 주고 있다.

• 한국정보전자통신기술학회논문지
• /
• 제11권6호
• /
• pp.742-750
• /
• 2018

본 논문에서는 $0.13{\mu}m$ BCD 공정 기반에서 5V MOS 소자만 사용하여 zero layer FTP 셀이 가능하도록 하기 위해 tunnel oxide 두께를 기존의 $82{\AA}$에서 5V MOS 소자의 gate oxide 두께인 $125{\AA}$을 그대로 사용하였고, 기존의 DNW은 BCD 공정에서 default로 사용하는 HDNW layer를 사용하였다. 그래서 제안된 zero layer FTP 셀은 tunnel oxide와 DNW 마스크의 추가가 필요 없도록 하였다. 그리고 메모리 IP 설계 관점에서는 designer memory 영역과 user memory 영역으로 나누는 dual memory 구조 대신 PMIC 칩의 아날로그 회로의 트리밍에만 사용하는 single memory 구조를 사용하였다. 또한 BGR(Bandgap Reference Voltage) 발생회로의 start-up 회로는 1.8V~5.5V의 전압 영역에서 동작하도록 설계하였다. 한편 64비트 FTP 메모리 IP가 power-on 되면 internal reset 신호에 의해 initial read data를 00H를 유지하도록 설계하였다. $0.13{\mu}m$ Magnachip 반도체 BCD 공정을 이용하여 설계된 64비트 FTP IP의 레이아웃 사이즈는 $485.21{\mu}m{\times}440.665{\mu}m$($=0.214mm^2$)이다.

• 펄프종이기술
• /
• 제30권2호
• /
• pp.5-12
• /
• 1998

Exploitation of the papermaking technology to reduce the strength loss that accompanies when using recycled papers as raw materials for papermaking is one of the most important issues imposed upon today's paper industry. Multi-layer sheet forming technology has been suggested as a way that provides some answers to this issue. In this study strength properties of single- and two-layer handsheets formed with recycled fiber and unbleached softwood kraft pulp have been examined to quantify the benefits when using two-layer sheet forming technology rather than a conventional single layer sheet forming precess. Single- and two-layer handsheets were made from 50% of OCC and 50% of Sw-UKP and their strength properties were evaluated. Also the strength properties made from Sw-UKP and OCC sheets were determined. A multihead, which can be attached on the top of hand- sheet former, was used to form two-layer sheets. Maximum strength properties could be obtained in the freeness range of 500∼300mL CSF for Sw-UKP Most of the strength properties was reduced by 30∼35% when 50% OCC was blended with UKP. Decrease of strength properties, however, could be reduced by employing a two-layer sheet forming method. Creator strengths could be obtained when UKP was positioned at the top layer of two layered sheets indicating greater UKP fines retention due to the filtration effect of the OCC layer formed prior to UKP layer contributed the strength improvement. Two-layer sheet showed lower Scott internal bond strength than single layer sheet. By incorporating some of UKP fibers into OCC layer this reduction could be reduced.

• 대한수의학회지
• /
• 제39권3호
• /
• pp.407-416
• /
• 1999

This study was carried out to investigate the NPY-immunohistochemical characteristics of the olfactory bulb in the striped field mouse(Apodemus agrarius). The animals were anesthesized with thiopental sodium and perfused with 4% paraformaldehyde through left ventricle and aorta. Brains were removed and tranfered 10%, 20% and 30% sucrose. Sections were then cut on a cryostat into $40{\mu}m$-thick. The tissue immunostained with avidin-biotinylated complex method. The main olfactory bulb consisted of seven circumferential laminae : an olfactory nerve fiber layer, a glomerular layer with glomeruli surrounding by periglomerular cells, an external plexiform layer having granule and tufted cells, a mitral cell layer, a narrow internal plexiform layer, a granule cell layer forming several cell rows and a layer of white matter. The accessory olfactory bulb had four layers : an olfactory or vomeronasal nerve fiber layer, a glomerular layer consisting of small glomeruli, a mixed layer not distinguishing the external plexiform/mitral cell/granule cell layers and a granule cell layer. Most of NPY-immunoreactive(NPY-IR) neurons in main olfactory bulb were localized in the deeper portion of granule cell layer, white matter and anterior olfactory nucleus. In addition, some NPY-IR neurons were identified in the external plexiform layer. The shape of NPY-IR neurons of all olfactory bulb were predominant round or oval, sometime multipolar in shape. And most NPY-IR processes were parallel to long axis of white matter. In accessory olfactory bulb, NPY-IR neurons were not found in all region.