• 마이크로전자및패키징학회지
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• 제19권4호
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• pp.45-50
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• 2012

A family of multi-die DRAM packages was developed that incorporate the full functionality of an SODIMM into a single package. Using a common ball assignment analogous to the edge connector of an SODIMM, a broad range of memory types and assembly structures are supported in this new package. In particular DDR3U, LPDDR3 and DDR4RS are all supported. The center-bonded DRAM use face-down wirebond assembly, while the peripherybonded LPDDR3 use the face-up configuration. Flip chip assembly as well as TSV stacked memory is also supported in this new technology. For the center-bonded devices (DDR3, DDR4 and LPDDR3 ${\times}16$ die) and for the face up wirebonded ${\times}32$ LPDDR3 devices, a simple manufacturing flow is used: all die are placed on the strip in a single machine insertion and are sourced from a single wafer. Wirebonding is also a single insertion operation: all die on a strip are wirebonded at the same time. Because the locations of the power signals is unchanged for these different types of memories, a single consolidated set of test hardware can be used for testing and burn-in for all three memory types.

• 한국정밀공학회지
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• 제27권10호
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• pp.14-22
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• 2010

The most costly and time-consuming process in the fabrication of today's multi-layer circuit board is drilling interconnection holes between adjacent layers and via holes within a layer. Decreasing size of via holes being demanded and growing number of via holes per panel increase drilling costs. Component density and electronic functionality of today's multi-layer circuit boards can be improved with the introduction of cost-effective, variable depth laser drilled blind micro via holes, and interconnection holes. Laser technology is being quickly adopted into the circuit board industry but can be accelerated with the introduction of a true production laser drilling system. In order to get optimized condition for drilling to FPCB (Flexible Printed Circuit Board), we use various drill pattern as drill step. For productivity, we investigate drill path optimization method. And for the precise drilling the thermal drift of scanner and temperature change of scan system are tested.

• 로봇학회논문지
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• 제6권3호
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• pp.237-246
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• 2011

Robots have been used in many fields due to its performance improvement and variety of its functionality, to the extent which robots can replace human tasks. Individual feature and better performance of robots are expected and required to be created. As their performances and functions have increased, systems have gotten more complicated. Multi mobile robots can perform complex tasks with simple robot system and algorithm. But multi mobile robots face much more complex driving problem than singular driving. To solve the problem, in this study, driving algorithm based on the energy method is applied to the individual robot in a group. This makes a cluster be in a formation automatically and suggests a cluster the automatic driving method so that they stably arrive at the target. The energy method mentioned above is applying attractive force and repulsive force to a special target, other robots or obstacles. This creates the potential energy, and the robot is controlled to drive in the direction of decreasing energy, which basically satisfies lyapunov function. Through this method, a cluster robot is able to create a formation and stably arrives at its target.

• 대한기계학회논문집A
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• 제31권2호
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• pp.245-252
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• 2007

Since the new millennium, truss PCMs(Periodic Cellular Metals) have drawn attention because of their superior specific stiffness, strength and multi-functionality. Prior studies have focused on the structural design and optimization. Kagome truss PCM has been proved to have the higher resistance to plastic buckling, more plastic deformation energy and lower anisotropy than other truss PCMs. In this study, we introduce a new idea to fabricate multi-layered Kagome truss PCM from continuous wires which can gain high strength as in piano wires and can be controlled to be defect free owing to drawing process. The relative density, the stiffness and the strength under bending and compressive load are estimated through elementary mechanics and compared with the results from experiments and FEA. The failure mechanisms are analyzed, and also mechanical performance and production are discussed.

• 한국실내디자인학회:학술대회논문집
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• 한국실내디자인학회 2005년도 춘계학술발표대회 논문집
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• pp.237-240
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• 2005

Nowadays living space has been small-sized due to a rise in the standard of living, change of recognition on the increase of housing for the singles, and frequent movements of duty place, etc. and the furnitures naturally evolved assembly and multi-functionality. However, it retuned with an economic charge in the consumers and lost the uniformity in a small-sized living space as well since the furniture depended on the each miscellaneous household goods or products and came to be used. Hereupon it was demanded the system where the various furnitures are to fit to here. This study aimed at this point firstly examined a new environment change which it follows till a small living space is demanded through lots of literature, after understanding the concept of the system furniture, I classified expressive types of system furniture in modern environment and analyzed the design quality and characteristics in it by selecting well-known furniture magazines inside and outside of the country and extracting and analyzing system furniture images which are recorded in advertisements or articles. The objective of this study is to present MMC(Multi Modular Coordination, a system furniture design based on this analysis that inquiring the problems with function, structure, assembly which other existing system furnitures are facing enabled to apply a basic data in unit-module planning and by sampling embodiment modeling by uses.

• 한국염색가공학회지
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• 제29권2호
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• pp.62-68
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• 2017

Coffee sludge and onion shells are known typically as waste resources as well as simultaneously being the raw material for dye having a golden brown color. This research studies the dyeability, functionality, and colors of woolen fabric after being dyed by different dyeing method using coffee sludge and onion shells extract. The woolen fabric was refined and pre-mordanted with tannin. The dyeing process conducted was single-dye, using coffee sludge and onion shells extract, sequential multi-dye, consecutively dyeing with coffee sludge and onion shells, and mixed-dye, blending coffee sludge extract and onion shells extract to dye. The dyeing was measured on the surface color, color fastness, and UV-protection ability. As a result, the expression of various hues of tan using coffee sludge and onion shells extract were shown to be possible. Additionally, single-dye, sequential multi-dye, mixed-dye had generally superiority in color fastness to light, all rating 3 and color fastness to washing, rating 3 or 4, showing relatively stable color fastness to washing. The UV protection ability was shown to be better, especially appearing satisfactory in the UV-B protection, all measured to be over 90%.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권8호
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• pp.4160-4173
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• 2019

Borescopes facilitate the inspection of areas inside machines and systems that are not directly accessible for visual inspection. They offer real-time, up-close access to confined and hard-to-access spaces without having to dismantle or destructure the object under inspection. Borescopes are ideal instruments for routine maintenance, quality inspection and monitoring of systems and structures. The main application being fault or defect detection, it is useful to have measuring capability to quantify object dimensions in a target area. High-end borescopes use multi-optic solutions to provide measurement information of viewed objects. Multi-optic solutions can provide accurate measurements at the expense of structural complexity and cost increase. Measuring functionality is often unavailable in low-end, single camera borescopes. In this paper, a single camera measurement solution that enables the size estimation of viewed objects is proposed. The proposed solution computes and overlays a scaled grid of known spacing value over the screen view, enabling the human inspector to estimate the size of the objects in view. The proposed method provides a simple means of measurement that is applicable to low-end borescopes with no built-in measurement capability.

• Structural Engineering and Mechanics
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• 제85권2호
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• pp.233-246
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• 2023

Bending and buckling analysis of multi-directional porous functionally graded sandwich plate has been performed for two cases namely: FG skin with homogeneous core and FG core with homogeneous skin. The principle of virtual displacements was employed and the solution was obtained using Navier's technique. This theory imposes traction-free boundary conditions on the surfaces and does not require shear correction factors. The validation of the present study has been performed with those available in the literature. The composition of metal-ceramic-based FGM changes in longitudinal and transverse directions according to the power law. Different porosity laws, such as uniform distribution, unevenly and logarithmically uneven distributions were used to mimic the imperfections in the functionally graded material that were introduced during the fabrication process. Several sandwich plates schemes were studied based on the plate's symmetry and the thickness of each layer. The effects of grading parameters and porosity laws on the bending and buckling of sandwich plates were examined.

• 로봇학회논문지
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• 제17권4호
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• pp.407-416
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• 2022

Multiple AMRs have been proved to be effective in improving warehouse productivity by eliminating workers' wasteful walking time. Although Multi-agent Path Finding (MAPF)-based solution is an optimal approach for this task, its deployment in practice is challenging mainly due to its imperfect plan-execution capabilities and insufficient computing resources for high-density environments. In this paper, we present a MAPF-based fleet management system architecture that robustly manages multiple robots by re-computing their paths whenever it is necessary. To achieve this, we defined four events that trigger our MAPF solver framework to generate new paths. These paths are then delivered to each AMR through ROS2 message topic. We also optimized a graph structure that effectively captures spatial information of the warehouse. By using this graph structure we can reduce computational burden while keeping its rescheduling functionality. With proposed MAPF-based fleet management system, we can control AMRs without collision or deadlock. We applied our fleet management system to the real logistics warehouse with 10 AMRs and observed that it works without a problem. We also present the usage statistic of adopting AMRs with proposed fleet management system to the warehouse. We show that it is useful over 25% of daily working time.

• 한국음향학회지
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• 제26권6호
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• pp.269-275
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• 2007

디지털 기술의 발전으로 어디서나 음악을 들을 수 있는 다채널 편재형 오디오 시스템의 개발이 구체화 되고 있다. 본 논문에서는 SoC 설계 기술을 기반으로 양방향 디지털 통신을 이용하여 각 스피커를 효율적으로 직렬 연결하는 시스템을 제시한다. 특히 각 스피커는 해당하는 비트 스트림을 확인하여 아날로그 오디오 신호로 변경한다. 또한 스피커는 여러 구형파 테스트 신호의 주파수를 측정하여 스피커 자체의 고장 유무를 진단하는 기능을 가진다. 본 논문에서 제시한 시스템은 200Mhz의 속도로 작동하고 있으며, 기존의 아날로그 방식의 시스템에서는 신호가 직접 출력되지만 $500{\mu}s$ 정도의 지연으로 아날로그 신호를 복원하고 있다.