• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.7
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• pp.30-36
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• 2011

Three-dimensional (3D) memories using through-silicon vias (TSVs) as vertical bus across memory layers are implemented by many semiconductor companies. 3D memories are composed of known-good-dies (KGDs). If additional faults are arisen during bonding, they should be repaired. In order to enhance the yield of 3D memories with inter-die redundancies, a die-matching method is needed to effectively stack memory dies in a 3D memory. In this paper, a new die-matching method is proposed for 3D memory yield enhancement with inter-die redundancies considering additional faults arisen during bonding. Three boundary-limited conditions are used in the proposed die-matching method; they set bounds to the search spaces for selecting memory dies to manufacture a 3D memory. Simulation results show that the proposed die-matching method can greatly enhance the 3D memory yield.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.9
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• pp.872-879
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• 2004

The TX/RX broadband L-type circular polarization antenna using LTCC(Low Temperature Co-fired Ceramic) for satellite communication at K, Ka band(20～21 GHz/30～31 GHz) has been presented. This antenna has been analyzed in compensation for LTCC with relative permittivity 5.2 and could have been integrated with RF component. Also antennas on LTCC enable :o reduce loss of RF system due to integrate with RF circuits and to light weight, and thus, generally one can reduce size of the RF system. As the geometry of this antenna presented is made simple by L type of monopole antenna, it is easily manufactured by LTCC progress and enables to reduce loss.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.8
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• pp.42-51
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• 2021

Investigations of process parameters are essential when fabricating high-quality parts using additive manufacturing. This study investigates the change in the mechanical characteristics of a SUS316L specimen fabricated using selective laser melting based on the energy density and bead overlap ratio. The SUS316L powder particles were spherical and 35 ㎛ in size. Single-bead and hexahedral shape deposition experiments were performed sequentially. A single bead experiment was performed to obtain the bead overlap ratios for different laser parameters utilizing laser power and scan speed as experimental parameters. A hexahedral shape deposition experiment was also performed to observe the difference in mechanical properties, such as the internal porosity, surface roughness, and hardness, based on the energy density and bead overlap ratio of the three-dimensional printed part. Laser power, scan speed, overlap ratio, and layer thickness were chosen as parameters for the hexahedral shape deposition experiment. Accordingly, the energy density applied for three-dimensional printing, and the experimental parameters were calculated, and the energy density and bead overlap ratio for fabricating parts with good properties have been suggested.

• Journal of the Korean Vacuum Society
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• v.19 no.5
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• pp.341-346
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• 2010

In this paper, anti-reflection coating was investigated for decreasing the reflection in visible range of 400~650 [nm] through four staked layers of $Si_xO_y$ and $Si_xN_y$ thin films prepared by reactive sputtering method. Si single crystal of 6 [inch] diameter was used as a sputtering target. Ar and $O_2$ gases were used as sputtering gases for reactive sputtering for the $Si_xO_y$ thin film, and Ar and $N_2$ gases were used for reactive sputtering for the $Si_xN_y$ thin film. DC pulse power of 1900 [W] was used for the reactive sputtering. Refractive index and deposition rate were 1.50 and 2.3 [nm/sec] for the $Si_xO_y$, and 1.94 and 1.8 [nm/sec] for the $Si_xN_y$ thin film, respectively. Considering the simulation of the four layer anti-reflection coating structure with the above mentioned films, the $Si_xO_y-Si_xN_y$ stacked four-layer structure was prepared. The reflection measurement result for that structure showed that a "W" shaped anti-reflection was obtained successfully with a reflection of 1.7 [%] at 550 [nm] region and a reflection of 1 [%] at 400~650 [nm] range.

• Journal of the Korean Ceramic Society
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• v.40 no.10
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• pp.961-966
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• 2003

A Multi-Layer Ceramic (MLC) chip type Band-Pass Filter (BPF) using BiNb$\_$0.975/Sb$\_$0.025/ $O_4$ LTCC (Low Temperature Co-fired Ceramics) and MLC processing is presented. The MLC chip BPF has the benefits of low cost and small size. The BPF consists of coupled stripline resonators and coupling capacitors. The BPF is designed to have an attenuation pole at below the passband for a receiver band of IMT-2000 handset. The computer-aided design technology is applied for analysis of the BPF frequency characteristics. The attenuation pole depends on the coupling between resonators and the coupling capacitance. An equivalent circuit and structure of MLC chip BPF are proposed. The frequency characteristics of the manufactured BPF is well acceptable for IMT-2000 application.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.505-505
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• 2013

유기발광소자는 저전력, 고휘도 및 빠른 응답속도와 넓은 시야각 등의 장점을 가지고 있어 소형 디스플레이 및 대형 디스플레이로 상용화하기 위해 많은 연구가 진행되고 있다. 고분자 유기발광소자는 저분자 유기발광소자에 비하여 용액공정을 사용하여 저비용으로 대면적 디스플레이를 제작하기 유리하기 때문에 많은 연구가 되고 있다. 하지만, 고분자 유기발광 소자는 구동 전압이 높고 발광효율이 낮은 단점을 가지고 있다. 본 연구에서는 고분자 유기발광 소자의 구동전압 감소와 발광효율을 증가 시키기 위해 정공주입층을 가진 적색 고분자 유기발광소자를 제작하였다. 정공주입층을 포함하는 고분자 유기발광소자는 Indium thin oxide (ITO)위에 정공주입층 형성 후 스핀코팅 방법으로 poly (3,4-ethylenedioxythiopene): poly (styrenesulfonate) (PEDOT: PSS)을 정공수송층으로, poly (2-methoxy-5-(2-ethylhexoxy)-1,4-phenylence vinylene) (MEH-PPV)를 발광층으로 적층하고, Al을 음극 전극으로 진공 증착하여 소자를 제작하였다. 정공주입층의 특성 분석을 위해 정공주입층의 투과도와 ITO/PEDOT:PSS와 ITO/정공주입층/PEDOT:PSS의 표면을 원자힘 현미경으로 측정하였다. 정공주입층의 가시광선 영역 투과도는 90% 이상으로 높게 나왔으며, ITO/정공주입층/PEDOT:PSS의 경우 ITO/PEDOT:PSS 보다 표면 거칠기가 감소하였다. 높은 가시광선 영역 투과도와 낮은 표면 거칠기는 발광층으로 정공주입을 원활하게 하여 소자의 발광 효율이 증가한다. 정공주입층을 포함하는 적색 고분자 유기발광소자의 경우 전류밀도-전압, 휘도-전압의 관계에서 정공주입층을 사용하지 않은 소자에 비하여 높은 전기적 및 광학적 특성이 나타났다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.7
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• pp.1267-1271
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• 2009

In this paper, a diplexer circuit to separate GSM from CDMA band is designed using a LTCC (Low Temperature Cofired Ceramic) multi-layer technology. In order to increase a integration capability of the diplexer, it is designed using 3-dimensional (3-D) multi-layer compact inductor and capacitors in e-layer LTCC substrate with a relative dielectric constant of 7. In order to achieve high selectivity of the bands, a shunt capacitor and inductor are designed in the high-pass filter (HPF) and low-pass filter (LPF), respectively. The size of the fabricated diplexer including CPW pads is 3,450 ${\times}$4,000 ${\times}$694 ${\mu}m^3$An insertion loss (IL) and return loss in GSM band are less than -1.35dB and more than -5.66dB,respectively. In the case of CDMA band, the IL of -1.54dBandRLof above -9.30dBare archived.

• Composites Research
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• v.28 no.4
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• pp.212-218
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• 2015

A large composite spar was manufactured using an automatic fiber placement (AFP) machine. To verify its structural performance, the weakest part of the structure, which is called 'corner radius', was tested under bending and examined by finite element analysis. Since the application of AFP machine to composite structure fabrication is still in early stage in Korea, this paper presents the summary of whole process for manufacturing composite spar using AFP machine from mandrel design and analysis to verification test. The deflection and stress by mandrel weight and AFP machine force, thermal deformation and natural frequency were all examined for mandrel design. The target structure was composite C-spar and cured in an autoclave. Test results were compared with nonlinear finite element analysis results to show that the structure has the strength close to the theoretical value. It was confirmed that the corner radius of the spar manufactured by AFP process showed deviation less than 20% compared with first ply failure strength. The results indicate that the AFP technology could be used for large scale composite structure production in the near future.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.6
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• pp.531-539
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• 2017

This paper deals with the development of bonded joints for fibre reinforced plastic (FRP) hull structures using moulding-in concept. Focus is placed on bonded in-plane connections between two adjacent panels that could form the boundaries of hull structural module. Traditional construction in FRP hull structures requires the construction of a mould, usually from steel or aluminium. In this construction the FRP materials are laid in the mould, and resin is saturated, and then the structural member is cured. This is expensive since it involves the fabrication of metal hull mould for every different hull type, which is sacrificed after the production of the FRP ship. One way of encouraging greater use of FRP in ship construction is to investigate the possible construction of FRP hull structures in a similar manner to metallic ships, that is in terms of blocks or modules. Such a manner of construction would eliminate the need for expensive hull moulds permitting greater flexibility in the construction of FRP ships. The main issue then would be the design and construction of adequate bonded connections between adjacent panels. To fulfill this object, the simplified and automated way of manufacturing joint edge shapes for bonded joints is developed, and their structural assessment is performed in both experimentally and numerically.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.273-273
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• 2009

고체산화물 연료전지 (Solid Oxide Fuel Cell, 이하 SOFC)는 제조형태에 따라 크게 평판형과 원통형으로 구분할 수 있다. 단위면적당 출력 효율이 높은 평판형의 장점과 원통형의 밀봉이 용이한 장점을 동시에 가지는 평관형 형태로 지지체를 제작하였으며, 셀의 배치를 평면상 직렬로 연결하는 다전지식으로 구성함으로 전극의 길이나, 셀 간격을 기존 평판형이나 원통형에 비해 대폭 감소시켜 단위면적당 전압 및 출력효율을 높이고자 하였다. Segmented 평관형 지지체의 소재로는 연료전지의 성능 특성에 관여하지 않으며 열사이클 저항성과 기계적 강도가 우수한 spinel구조를 가지는 $MgAl_2O_4$를 선정하였다. 연료가스의 원활한 공급이 가능하도록 carbon을 기공 전구체로 사용하여 압출성형하였으며 건조과정에서 crack이 생기지 않는 공정을 확립한 후 $1400^{\circ}C$ 에서 소결하였다. 제조된 지지체는 수은침투법과 3점 굽힘 강도법으로 기공율과 기계적 강도를 각각 측정하였다. Anode를 스크린 프린팅법으로 지지체 위에 적층한 후 미세구조를 확인하였고 이를 바탕으로 다공성이며 기계적 강도를 가지고 음극과의 반응이 없는 우수한 지지체를 제조할 수 있었다.