• Korean Journal of Construction Engineering and Management
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• v.25 no.3
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• pp.68-82
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• 2024

The planning stage of laser scanning is crucial for acquiring high-quality 3D source data. It involves assessing the target space's environment and formulating an effective measurement strategy. However, existing practices often overlook on-site conditions, with decisions on scanner deployment and scanning locations relying heavily on the operators' experience. This approach has resulted in frequent modifications to scanning locations and diminished 3D data quality. Previous research has explored the selection of optimal scanner locations and conducted preliminary reviews through simulation, but these methods have significant drawbacks. They fail to consider scanner inaccuracies, do not support the use of multiple scanners, rely on less accurate 2D drawings, and require specialized knowledge in 3D modeling and programming. This study introduces an optimization technique for laser scanning planning using 3D simulation to address these issues. By evaluating the accuracy of scan data from various laser scanners and their positioning for scanning a retaining wall structure in a small-scale building, this method aids in refining the laser scanning plan. It enhances the decision-making process for end-users by ensuring data quality and reducing the need for plan adjustments during the planning phase.

• Journal of Korean Society of Steel Construction
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• v.23 no.1
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• pp.73-81
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• 2011

The wind force coefficient of a transmission tower frame shows several characteristics when the section shape, solidity ratio, and wind direction angle are changed. In this study, the wind force characteristics of a transmission tower frame with a basic structure were evaluated using different solidity ratios and wind direction angles in a wind tunnel test. According to the solidity ratio, the size of the structure and the rectangular-frame model of the transmission tower were changed by adding a two-dimensional (2D) or three-dimensional (3D) structure. The transmission tower's rectangular frame was tested by changing the wind direction angle of the 2D-type structure from 0 to $90^{\circ}$ and by changing the wind direction angle of the 3D-type structure from 0 to $45^{\circ}$ Based on the results that were obtained, it can be concluded that the wind force coefficient of a transmission tower frame can be used as preliminary data in deciding the transmission tower's wind load.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.19 no.3
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• pp.16-24
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• 2011

In this research, a cockpit display system using 3 dimensional geographic information was developed. A coordinate transformation method from WGS84 to TM was first studied. Octree data structure was used for efficient 2D and 3D graphic display. Also, a 3D graphic engine was developed for fast display with large amount of geographic data which can be practically used in aircraft onboard computer having low performance. This 3D engine contains additional function such as geographic and object information loading, many kinds of camera mode, aircraft position and rotation control function, character strip display. In the future research, actual GPS signal should be used and additional information that can help pilot's decision should be display.

• Korean Journal of Materials Research
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• v.23 no.8
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• pp.447-452
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• 2013

Recently, products that a have 3-dimensional(3D) micro structure have been in wide use. To fabricate these 3D micro structures, several methods, such as stereo lithography, reflow process, and diffuser lithography, have been used. However, these methods are either very complicated, have limitations in terms of patterns dimensions or need expensive components. To overcome these limitations, we fabricated various 3D micro structures in one step using a pair of diffusers that diffract the incident beam of UV light at wide angles. In the experiment, we used positive photoresist to coat the Si substrate. A pair of diffusers(ground glass diffuser, opal glass diffuser) with Gaussian and Lambertian scattering was placed above the photomask in the passage of UV light in the photolithography equipment. The incident rays of UV light diffracted twice at wider angles while passing through the diffusers. After exposure, the photoresist was developed fabricating the desired 3D micro structure. These micro structures were analyzed using FE-SEM and 3D-profiler data. As a result, this dual diffuser lithography(DDL) technique enabled us to fabricate various microstructures with different dimensions by just changing the combination of diffusers, making this technology an efficient alternative to other complex techniques.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.54 no.3
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• pp.186-190
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• 2005

In this paper, the pipelined A/D converter with multi S/H stage structure is proposed for high resolution and high-speed data conversion rate. In order to improve a resolution and operational speed, the proposed structure increased the sampling time that is sampled input signal. In order to verify the operation characteristics, 20MS/s pipelined A/D converter is designed with two S/H stage. The simulation result shows that INL and DNL are $0.52LSB\~-0.63LSB$ and $0.53LSB\~-0.56LSB$, respectively. Also, the designed Analog-to-Digital converter has the SNR of 43dB and power consumption is 18.5mW.

• International conference on construction engineering and project management
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• 2015.10a
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• pp.667-668
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• 2015

While the plant projects grow bigger and global attention to the plant is increasing, efficient space arrangement is not working in plant project because of the complex structure in installing the equipment unlike the construction project. In addition to this, presently, problem in installation process caused by the disagreement between floor plan and real spot is rising. Therefore the target of this research is to solve the problems and reaction differences, caused by changing the space arrangement in installing the equipment of plant construction. And this research suggests the equipment arrangement method for construction and related processes. To solve the problem, 3D cloud point data of space and equipment is collected by 3D laser scanning and the space matching is operated. In processing the space matching, data is simplified by applying the octree algorithm. This research simplifies the 3D configuration data acquired by 3D scanner equipment through the octree algorithm, and by comparing this data, identifies the space for target equipment, and finally suggests the algorithm that makes the auto space arrangement of equipment possible in construction site and also suggests the process to actualize this algorithm.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.8
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• pp.5695-5706
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• 2015

Recently adoption of BIM technology for building renovation and remodeling has been increased in construction industry. However most buildings have trouble in 2D drawing-based BIM modeling, because 2D drawings have not been updated real situations continually. Applying reverse engineering, this study analysed the point cloud data structure and the process for guideline of reverse engineering of architectural MEP, and deducted the relating considerations. To active usage of 3D scanning technique in domestic, the objective of this study is to analyze the point cloud data processing from real site with terrestrial LiDAR and the process from data gathering to data acquisition.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.12
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• pp.1846-1854
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• 2022

The sophistication and diversification of mission equipment for surveillance and reconnaissance is leading to a demand for large-capacity public data links. Overseas, a T4 class(274Mbps) common data link was applied to the Global hwak, a high-altitude unmanned aerial vehicle, and various research and development are being conducted in Korea. In this paper, we propose a structure in which pilot is additionally applied to improve SNR performance while minimizing data transmission rate loss in the DVB-S2 frame structure, which is a european satellite broadcasting standard, for high-capacity transmission of T4 class or higher in the common data link. For the performance evaluation of the proposed structure, the performance of the DVB-S2 was compared and analyzed by simulating the UAV data link channel environment. As a result of simulation, 0.15% of transmission rate loss occurred at T4 class transmission rate compared to DVB-S2 in the proposed structure, but improved SNR reception performance of 0.2~0.3dB was confirmed in the UAV channel environment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.3
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• pp.795-806
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• 1996

A structure which transmits and receives 3 subscribers packet data through an optical splitter node in an optical subscriber network of PON wave suggested and realized. All the functions which are necessary to use PON structure such as 155.52Mb/s multiplexer/demultiplexer of down-stream signal, 25.92Mb/s multiplexer/demultiplexer of up-stream signal, frame synchronizer, and phase aligner for aligning phase of the clock and received data have been integrated within 2 ICs using CMOS technonology. TDMAtechnology was suggested for up-stream transmission. In the optical up-stream transmission of the urst signals transmissionquality degradataion by APC and AGC of optical tranceiver was observed. By compensating the degradation, more than 17dB of link budget which is enough to satisfy 11.2dBthat is required in SWAN of PON architecture has been obtained with optical transceiver whose power and sensitivity are -17dBm and -34dBm respectively.

• Bulletin of the Korean Chemical Society
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• v.8 no.1
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• pp.1-3
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• 1987

The crystal structure of $K_5Na_2[SbW_6O_{24}]{\cdot}12H_2O$ has been determined. Final R = 0.081 for 890 observed independent reflections collected by diffractometry. Crystal data as follows; trigonal, space group R3m, a = 9.794(1) ${\AA},\;{\alpha}$ = 84.72$(1)^{\circ}$, Z = 1. The heteropolyanion has a structure with point symmetry $D_{3d}$ (3m), of the ideal Anderson-type heteropolyanion. The Sb-W and W-W distances are 3.259(2) and 3.259(3) ${\AA}$. Three types of W-O ($W-O_t,\;W-O_b\;and\;W-O_c$) distances are 1.73(2), 1.95(4) and 2.20(3) ${\AA}$. The Sb-O distance is 1.97(3) ${\AA}$.