• Journal of the Korea Computer Industry Society
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• v.10 no.4
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• pp.135-142
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• 2009

In this thesis, we designed and implemented a tracking filter which can be used for FH/2-FSK communication system in band of 40~60[MHz]. After measuring a performance of a tracking filter, an insertion loss was measured from 3.7 to 4.3 dB, depending upon a hopping center frequency. The 3 dB bandwidth of a tracking filter was specified 5.1 to 5.33% depend upon a hopping and 30/3 dB shape factor indication for interrupting property of a filter shows 6.828 to 6.98 satisfying a required specification. Also the attenuation $2{\times}f_0$, the characteristic parameter for interference degree, was specified 46~52dB, not satisfying a required specification.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.270-273
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• 2015

In shipbuilding and marine industry, engineering and design software solutions have upgraded from the original 2D schematic data based CAD system to a modern 3D drawing-based system. Due to the fact that the massive amount of data usage in real time and data volumes of various engineering models including graphic data have increased, several problems such as lack of server resources and improper handling of 3D drawings have been raised. Besides, increasing the number of session connections per server can cause deterioration of server performance. Recently, increasing the yard's sophisticated design capabilities highlighted the need to develop engineering and design system which would not only overcome the network performance issues, but would provide efficient collaborative design environment. This paper presents an overview of the framework for collaborative engineering design system based on the virtual application (Citrix XenApp 6.5)and acceleration hardware technology of 3D graphics (NVIDIA GRID K2 solution).

• Journal of Sensor Science and Technology
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• v.30 no.6
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• pp.388-394
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• 2021

The conventional microelectromechanical system (MEMS) process has been used to fabricate sensors with high costs and high-volume productions. Emerging 3D printing can utilize various materials and quickly fabricate a product using low-cost equipment rather than traditional manufacturing processes. 3D printing also can produce the sensor using various materials and design its sensing structure with freely optimized shapes. Hence, 3D printing is expected to be a new technology that can produce sensors on-site and respond to on-demand demand by combining it with open platform technology. Therefore, this paper reviews three standard 3D printing technologies, such as Fused Deposition Modeling (FDM), Direct Ink Writing (DIW), and Digital Light Processing (DLP), which can apply to the sensor fabrication process. The review focuses on strain/load sensors having both sensing material features and structural features as well. NCPC (Nano Carbon Piezoresistive Composite) is also introduced as a promising 3D material due to its favorable sensing characteristics.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.546-549
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• 2003

본 논문에서는 GPS용 안테나의 소형화를 위해 패치 길이 방향으로 T자형 슬릿 구조를 이용하여 GPS 중심 주파수인 1.575 GHz로 안테나를 설계, 제작하였다. 선형편파의 경우, 설계 주파수에서 패치 높이 3 mm 일 때, 패치 길이 $48 mm{\times}$폭 90 mm로 평면형($84 mm{\times}90 mm$)에 비해 42.9 %의 길이 단축 효과를 얻었으며, 반사손실 -20.3 dB, -10dB 대역폭 9 MHz (0.5 %), E-면 -3dB 빔폭 $77.7^{\circ}$, H-면 -3dB 빔폭 $66.2^{\circ}$, 이득 5.3 dBd의 특성을 나타내었다. 원형편파의 경우, 설계 주파수에서 패치 크기는 $57 mm{\times}57 mm$의 정방형으로서 T자형 슬릿 길이만을 조절하여 $90^{\circ}$의 위상차를 야기시켰으며 평면형 원형편파($82 mm{\times}86.5 mm$)에 비해 54.2 %의 면적 축소 효과 및 이득 3.89 dBd, 반사손실 -28.9 dB, 축비 1.96 dB, 2dB 축비 유지 대역폭 18 MHz로 양호한 원형편파 특성을 얻었다.

• Korean Journal of Construction Engineering and Management
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• v.1 no.3 s.3
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• pp.124-134
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• 2000

In construction projects, the design information, which should contain accurate product information in a systematic way, needs to be applicable through the life-cycle of projects. However, paper-based 2D drawings and relevant documents has difficulties in communicating and sharing the owner's and architect's intention and requirement effectively and building a corporate knowledge base through on-going projects due to Tack of interoperability between specific task or function-oriented software and handling massive information. Meanwhile, computer and information technologies are being developed so rapidly that the practitioners are even hard to adapt them into the industry efficiently. 3D modeling capabilities in CAD systems are enormously developed and enables users to associate 3D models with other relevant information. However, this still requires a great deal of efforts and costs to have all the design information represented in CAD system, and the sophisticated system is difficult to manage. This research focuses on the transition period from 2D-based design Information management to 3D-based, which means co-existence of 2D and 3D-based management. This research proposes a model of a compound system of 2D and 3D-based CAD system which presents the general design information using 3D model integrating with 2D CAD drawings for detailed design information. This research developed an integrated information management system for design and specification by associating 2D drawings and 3D models, where 2D drawings represents detailed design and parts that are hard to express in 3D objects. To do this, related management processes was analyzed to build an information model which in turn became the basis of the integrated information management system.

• Korean Journal of Construction Engineering and Management
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• v.14 no.5
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• pp.35-43
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• 2013

Nowadays the widely used media in architecture include visualizations, animations and three-dimensional models. 3D digital methods using active CAM(Computer Aided Manufacturing) and CNC(Computerized Numerical Control) imaging have been developed for accurate shape and 3D measurements in freeform buildings. In contrast to a conventional building using auto CAD system and others, the proposed digital optimization method is based on a combination of 3D numerical data and parametric 3D model for design and construction. The objective of this paper is therefore to present digital optimization process for constructability of freeform building. The method can be useful in the effective implementation of an error-proofing process of freeform building during design and construction phase. 3D digital coordinate data can be used effectively to identify correct size of structural and finish members and installation location of each members in construction field. In addition, architects, engineers and contractors can evaluate design, materials, constructability and identify error-proofing opportunities. Other project participants can also include representatives from all levels of management, departments as well as workers and key subcontractors' personnel, if necessary. The 3D digital optimization process is therefore appropriate to serious variations in freeform shape. For future study, the developed digital optimization method is necessary to be carried out to verify the robustness and accuracy for constructability in construction field.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.1
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• pp.115-121
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• 2012

In this paper, the design and fabrication of slot array in the broad wall of the waveguide for Ka-band monopulse radar are discussed. The aperture distributions are designed for the desired antenna gain, beamwidth and Side-lobe Level(SLL), and then slot parameters, such as lengths and offsets, are obtained for corresponding to each slot admittance in the equivalent circuit by using Elliot's array synthesis procedure. MWS-CST simulation shows the return loss below -10 dB, antenna gain above 32 dBi, 3 dB beamwidth of 3.7 degree and SLL of -20 dB. In order to demonstrate the expected results, the designed antenna is fabricated and measured.

• Journal of Korean Society for Geospatial Information Science
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• v.21 no.1
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• pp.87-93
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• 2013

As the progress regarding spatial analysis on features such as landscape, sunlight, shadow, and direct ray using 3D simulation, it is required to research the creation of 3D terrain models crucial for 3D simulations. In this paper, we suggested the methods to create the 3D terrain model for the state after development, by transfer the 2D plan to 3D terrain model using the normal equation. Automated algorithm producing 3D terrain model from 2D plan was developed. And It is expected to be needed more studies detailed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.2
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• pp.171-178
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• 1998

Generally, the output matching circuit has the most influence to the output power of oscillator and existing method for output matching has difficulty for making the optimum output matching circuit because the matching has to be done nearby the infinite impedance area of the Smith Chart. In this paper, it is studied for the output matching circuit of the microwave oscillator to get the maximum output power. The maximum output point can be found by adjusting the position of moving short in the Tuner while the oscillator is operating after connect the 3-dB coupler Tuner to the oscillator without output matching circuit. To design the oscillator for the maximum output power can be done easily with the microstrip line which is realized from the measured S-parameters of Tuner. In compare the oscillator by the existing method with another one by the suggested method in this paper, the first one has 6.45 dBm output power and second one has 9.71 dBm which is 3.26 dBm higher than the first one at the oscillation frequency 1.0338 GHz.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.10
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• pp.49-54
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• 2007

As digital contents based on 3D graphics are increased, the requirement for low power 3D graphic hardware for mobile devices is increased. We design a transformation engine for mobile 3D graphic processor. We propose a simplified transformation engine for mobile 3D graphic processor. The area of the transformation engine is reduced by merging a mapping transformation unit into a projective transformation unit and by replacing a clipping unit with a selection unit. It consists of a viewing transformation unit a projective transformation unit a divide by w nit, and a selection unit. It can process 32 bit floating point format of the IEEE-754 standard or a reduced 24 bit floating point format. It has a pipelined architecture so that a vertex is processed every 4 cycles except for the initial latency. The RTL code is verified using an FPGA.