• Structural Engineering and Mechanics
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• 제56권3호
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• pp.355-367
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• 2015

This paper deals with a new designed joint system for single-layer spatial structures. As the stability of these structures is greatly influenced by the joint behaviour, the aim of this paper is the characterization of the joint response in bending through Finite Element Method (FEM) analysis using ABAQUS. The behaviour of the joints studied here was influenced by many geometrical factors, such as bolts and plate sizes, distance between bolts and end-plate thickness. The study comprised five models of joints with different values of those parameters. The numerical results were compared to the results of previous experimental tests and the agreement was good enough. The differences between the numerical and experimental initial stiffness are attributed to the simplifications introduced when modelling the bolt threads as well as the presence of residual stresses in the test specimens.

• 한국정보통신학회논문지
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• 제4권1호
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• pp.59-65
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• 2000

This paper describes the characteristics of a one dimensional narrow-wall slotted waveguide array with a single-layer linear-to-circular polarization converter consisting of a dipole array. An external boundary value Problem of one slot and three dipoles, which approximates the mutual coupling between the dipole array and an edge slot extending over three faces of a rectangular waveguide, is formulated and analyzed by the method of moments; design of polarization conversion is conducted for this model as a unit element. If every unit element has perfect circular polarization, grating lobes appear in the array pattern due to the alternating slot angle: these are suppressed in this paper by changing the dipole angle and degrading the axial ratio of the unit element. The validity of the design is confirmed by the measurements. The dipole array has negligible effects upon slot impedance; the polarization conversion for existing narrow-wall slotted arrays is realized by add-on dipole array.

• 한국표면공학회지
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• 제29권5호
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• pp.512-518
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• 1996

Amorphous carbon nitride (a-C:N) multilayerfilms are formed by using altermating conditions during film deposition in are ion plating process. Because hard a-C:N films prepared with suitable megative bias voltages have large compressive stress, it is difficult to increase film thickness more than 200nm. Preparing multilayer films composed of hard layers and soft layers, we can grow thick multilayer films on Si and SKH steel substrate. The total thickness of multilayer films is more than 1$\mu\textrm{m}$. The multilayer films are several times thicker than the single layer films and almost equal in hardness and internal stress to the single layer ones. X-ray photoelectron spectroscopy(XPS) and Raman spectroscopy reveal that multilayer films equal to single layer films in structure, which is similar to the structure of DLC films.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2008년도 추계학술대회 초록집
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• pp.69-70
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• 2008

태양전지에서 효율성은 높이고 가격은 낮추기 위한 연구가 활발히 진행이 되고 있다. 본 연구에서는 효율성 중에서도 single layer에서의 반사율에 초점을 맞추었다. 본 연구에서는 single layer 박막에서의 반사율에 대한 시뮬레이션을 수행했다. 적절한 refractive index를 갖는 박막을 사용했을 때, 반사율 감소를 simulation과 실험을 통해서 알 수가 있었으며, MgF2 박막물질을 사용했을 경우, 물질의 refractive index가 낮을수록 반사율이 낮아짐을 알 수 있었다. 시뮬레이션 결과와 실제 실험 결과를 비교했을 때, 실제 실험 결과의 반사율이 약 3%가량 큰 것으로 나타났다. 이는 반사방지막의 증착 불균일성에 기인하는 문제로 생각된다. 또한, refractive index의 차이에 의해 substrate에 따른 최적화 반사율을 얻는 조건이 달라짐을 실험을 통해 확인할 수 있었다. Glass의 경우는 MgF2가 silicon과 GaAs의 경우에는 ZrO2 나 HfO2가 낮은 반사율을 보였다.

• Steel and Composite Structures
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• 제38권3호
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• pp.281-291
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• 2021

An equivalent single-layer theory (EST) is put forward for analyzing free vibrations of steel-concrete composite beams (SCCB) based on a higher-order beam theory. In the EST, the effect of partial interaction between sub-beams and the transverse shear deformation are taken into account. After using the interlaminar shear force continuity condition and the shear stress free conditions at the top and bottom surface, the displacement function of the EST does not contain the first derivatives of transverse displacement. Therefore, the C0 interpolation functions are just demanded during its finite element implementation. Finally, the EST is validated by comparing the results of two simply-supported steel-concrete composite beams which are tested in laboratory and calculated by ANSYS software. Then, the influencing factors for free vibrations of SCCB are analyzed, such as, different boundary conditions, depth to span ratio, high-order shear terms, and interfacial shear connector stiffness.

• Nuclear Engineering and Technology
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• 제55권3호
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• pp.1015-1020
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• 2023

A multi-layer design is applied to mitigate single event effect (SEE) in a 28 nm System-on-Chip (SoC). It depends on asymmetric multiprocessing (AMP), redundancy and system watchdog. Irradiation tests utilized 70 and 90 MeV proton beams to examine its performance through comparative analysis. Via examining SEEs in on-chip memory (OCM), compared with the trial without applying the multi-layer design, the test results demonstrate that the adopted multi-layer design can effectively mitigate SEEs in the SoC.

• 한국전기전자재료학회논문지
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• 제18권3호
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• pp.231-236
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• 2005

To investigate the electrical properties at the single grainboundary of ZnO varistors, micro-electrodes were fabricated on the surface which was polished and thermally etched. Our micro-electrode had 2000 $\AA$ silicon nitride layer between micro-electrode and ZnO surface. This layer was deposited by PECVD and etched by RIE after photoresistor pattering process using by mask 1. The metal patterning of micro-electrodes used lift-off method. We found that the breakdown voltage of single grainboundary is about 3.5∼4.2 V at 0.1 mA on I-V curves. Also, capacitance-voltage measurement at single grainboundary gave several parameters( $N_{d}$, $N_{t}$, $\Phi$$_{b}$, t) which were related with grainboundary.ary.

• 한국표면공학회지
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• 제34권2호
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• pp.105-114
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• 2001

$Al_2$$O_3$ coatings were deposited on M2 high speed steels by the plasma enhanced chemical vapor deposition (PECVD) process, using a gas mixture of AlC1$_3$, $H_2$, $CO_2$ and Ar $Al_2$$O_3$ coatings had interference color and showed amorphous phase. $A1_2$X$A1_3$/($Ti_{0.5}$ /$Al_{0.5}$ )N double layer coatings were produced in the sequence of substrate $NH_3$ plasma pretreatment, ($Ti_{0.5}$$Al_{0.5}$)N depoition process, $Al_2$$O_3$ deposition process. $Al_2$ $O_3$/( $Ti_{0.5}$A $l_{0.5}$)N double layer coatings showed NaCl structure in ( $Ti_{0.5}$A $l_{0.5}$)N layer and amorphous phase in A1$_2$ $O_3$ layer. It was shown that $Al_2$ $O_3$ columns continuously grew onto ( $Ti_{0.5}$A $l_{0.5}$)N columns. ( $Ti_{0.5}$A $l_{0.5}$)N single coating and $Al_2$ $O_3$/( $Ti_{0.5}$A $l_{0.5}$)N double layer coating were oxidized at $700^{\circ}C$, 80$0^{\circ}C$, 90$0^{\circ}C$ for 1hr, 3hr in atmosphere. At 80$0^{\circ}C$, single layer coatings were oxidized, which were examined substrate oxide particle. But $Al_2$ $O_3$/ ( $Ti_{0.5}$A $l_{0.5}$)N double layer coatings maintained the asdeposited state. Therefore, $Al_2$ $O_3$/ ( $Ti_{0.5}$A $l_{0.5}$)N double layer coatings have moreexcellent oxidation resistance than ( $Ti_{0.5}$A $l_{0.5}$)N single layer coatings.X> 0.5/)N single layer coatings.s.

• Membrane and Water Treatment
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• 제5권2호
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• pp.109-122
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• 2014

Polyvinylidene fluoride (PVDF) hollow fiber membrane is widely used for water treatment. However, the weak mechanical strength of PVDF limits its application. To enhance its tensile strength, a double-layer composite hollow fiber membrane, with PVDF and polyetherimide as the external and inner layers, respectively, was successfully prepared through phase inversion technique. The effects of additive content, air gap distance, N,N-dimethyl-acetamide content in the inner core liquid, and the temperature of external coagulation bath on the membrane structure, permeation flux, rejection, tensile strength, and porosity were determined. Experimental results showed that the optimum preparation conditions for the double-layer composite hollow fiber membrane were as follows: PEG-400 and PEG-600, 5 wt%; air gap distance, 10 cm; inner core liquid and the external coagulation bath should be water; and temperature of the external coagulation bath, 40 C. A single layer PVDF hollow fiber membrane (without PEI layer) was also prepared under optimum conditions. The double-layer composite membrane remarkably improved the tensile strength compared with the single-layer PVDF hollow fiber membrane. The permeation flux, rejection, and porosity were also slightly enhanced. High-tensile strength hollow fiber PVDF ultrafiltration membrane can be fabricated using the proposed technique.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 영호남학술대회 논문집
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• pp.331-334
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• 2000

The organic electroluminescent(EL) device has gathered much interest because of its large potential in materials and simple device fabrication. We fabricated EL devices which have a blended single emitting layer containg poly(Nvinylcarbazole)[PVK] and poly(3-dodecylthiophene)[P3DoDT]. The molar ratio between P3DoDT and PVK changed with 1:0, 2:1 and 1:1. To improve the external quantum efficiency of EL devices, we applied insulating layer, LiF layer between polymer emitting layer and AI electrode. All of the devices emit orange-red light and it's can be explained that the energy transfer occurs from PVK to P3DoDT. Within the molar ratio 1:0, 2:1 and 1:1, the energy transfer was not saturated, which results in the not appearance of PVK emission in the blue region. In the voltage-current and voltage-light power characteristics of devices applied LiF layer, current and light power drastically increased with increasing with applied voltage. In the consequence of the result, the light power of the device have a molar ratio 1:1 with LiF layer was about 10 times larger than that of the device without PVK at 6V.