• Digital Contents
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• no.11 s.126
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• pp.144-151
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• 2003

문제점: 하위 수준 D3D 지원_ 버텍스 버퍼를 만들기 위해 코어 Direct3D(D3D)는 하위 수준의 메모리 관리만 지원한다. 버텍스 버퍼 데이터는 void* 포인터를 사용해 액세스 된다. 코어 D3D에서 하위 수준의 지원은 매우 적절하다. D3DX는 전체 메시 클래스로서 포함한 상위 수준도 지원한다. 이 상위 수준과 하위 수준 사이에는 아무 것도 없다. 하위 수준의 버텍스 버퍼(VB)를 사용하기 위해서는 먼저 버텍스데이터 구조를 만들고 크기에 맞는 VB를 만든 후 이를 데이터로 채우고(void* 포인터 배치) 마지막으로 필요한 버텍스 선언을 한다. 애플리케이션 코드는 D3D 없이도 스스로 일관성을 가져야 하며 몇몇 하위 수준 에러가 발생할 수도 있다. 기껏해야 에러는 실행하면서 D3D의 디버그 버전으로 잡아낼 수 있다. 최악의 경우, 애플리케이션 문제를 발생시킬 수 있는데 이럴 경우 종종 디버그가 어려울 수도 있다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.2
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• pp.525-531
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• 2015

According to the increasing demand for 3D indoor spatial information, the utilization of a terrestrial laser scanner comes to the fore. However, the research for the comparison between a terrestrial laser scanning method and a traditional surveying method is insufficient. The paper evaluated the time-efficiency and the locational accuracy of an AMCW type and a direct TOF type of terrestrial laser scanning methods in comparison with the observation using a total station. As a result, an AMCW type showed higher time-efficiency than a direct TOF type and the RMSE between the two types of data was ${\pm}1mm$. Moreover, the terrestrial laser scanning method showed twice higher time-efficiency than the observation using a total station and the RMSE between the two data was ${\pm}3.4cm$. The results indicate that the terrestrial laser scanning method has better profitability and performance for 3D indoor modeling than the traditional survey using a total station. In the future, a terrestrial laser scanner can be efficiently utilized in the construction of 3D indoor spatial information.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.5 s.182
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• pp.143-148
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• 2006

It is still very difficult to generate a geometry model and finite element model, which has complex and many free surface, even though 3D CAD solutions are applied. Furthermore, in the medical field, which is a big growth area of recent years, there is no drawing. For these reasons, making a geometry model, which is used in finite element analysis, is very difficult. To resolve these problems and satisfy the requests of the need to create a 3D digital file for an object where none had existed before, new technologies are appeared recently. Among the recent technologies, there is a growing interest in the availability of fast, affordable optical range laser scanning. The development of 3D laser scan technology to obtain 3D point cloud data, made it possible to generate 3D model of complex object. To generate CAD and finite element model using point cloud data from 3D scanning, surface reconstruction applications have widely used. In the early stage, these applications have many difficulties, such as data handling, model creation time and so on. Recently developed point-based surface generation applications partly resolve these difficulties. However there are still many problems. In case of large and complex object scanning, generation of CAD and finite element model has a significant amount of working time and effort. Hence, we concerned developing a good direct finite element model generation method using point cloud's location coordinate value to save working time and obtain accurate finite element model.

• The korean journal of orthodontics
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• v.45 no.3
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• pp.105-112
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• 2015

Objective: A recently developed facial scanning method uses three-dimensional (3D) surface imaging with a light-emitting diode. Such scanning enables surface data to be captured in high-resolution color and at relatively fast speeds. The purpose of this study was to evaluate the accuracy and precision of 3D images obtained using the Morpheus 3D$^{(R)}$ scanner (Morpheus Co., Seoul, Korea). Methods: The sample comprised 30 subjects aged 24.34 years (mean $29.0{\pm}2.5$ years). To test the correlation between direct and 3D image measurements, 21 landmarks were labeled on the face of each subject. Sixteen direct measurements were obtained twice using digital calipers; the same measurements were then made on two sets of 3D facial images. The mean values of measurements obtained from both methods were compared. To investigate the precision, a comparison was made between two sets of measurements taken with each method. Results: When comparing the variables from both methods, five of the 16 possible anthropometric variables were found to be significantly different. However, in 12 of the 16 cases, the mean difference was under 1 mm. The average value of the differences for all variables was 0.75 mm. Precision was high in both methods, with error magnitudes under 0.5 mm. Conclusions: 3D scanning images have high levels of precision and fairly good congruence with traditional anthropometry methods, with mean differences of less than 1 mm. 3D surface imaging using the Morpheus 3D$^{(R)}$ scanner is therefore a clinically acceptable method of recording facial integumental data.

• Journal of the Korea Convergence Society
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• v.9 no.3
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• pp.223-230
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• 2018

This study analyzes the cost fluctuation between cost in contract stage and cost in adjustment stage in defense R&D project. This research shows that certain costs hold with the cost fluctuation and their degree of influence. The results of first analysis show that 13 out of 17 costs have a relationship with the cost fluctuation. The estimate of direct labor cost is positive and significant at the 0.1% level(direct labor = 1.022, t = 38.355). The estimate of amount of cost paid to subcontractor is positive and significant at the 1% level(amount paid to subcontractor = 0.942, t = 51.894). The results of second analysis show that all the direct costs have a relationship with the cost fluctuation(The fact that cost system is focused on direct labor cost is a consideration in this analysis). The estimate of direct labor cost is positive and significant at the 0.1% level(direct labor = 2.014, t = 21.787). The estimate of amount of cost paid to subcontractor is positive and significant at the 0.1% level(amount of cost paid to subcontractor = 1.068, t = 15.636). This finding supports a proposal theory that cost system is focused on direct labor cost through actual proof analysis and an inducement that amount of cost paid to subcontractor is a way to reduce the R&D cost.

• Electronics and Telecommunications Trends
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• v.21 no.1 s.97
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• pp.35-43
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• 2006

X 서버는 개발된 지 20년 동안 그리 큰 변경이 이루어지지 않았다. 하지만, 그래픽 하드웨어는 사양은 3D 그래픽 고성능으로 변화되었다. X 서버는 2D 그래픽을 처리하기위한 그래픽 시스템으로 설계되었다. 3D 그래픽 처리를 위해서 OpenGL 라이브러리를X 서버와 연동하는 작업을 해왔지만 구조적으로 3D 그래픽 드로잉을 처리하는 것은 X서버이기 때문에 성능에 한계를 드러내게 되었다. 마이크로소프트사 DirectX 구조처럼직접 그래픽 하드웨어를 제어해서 3D 그래픽 처리를 구현하고 있으며 리눅스 진영은X 서버와 공존하면서 3D 그래픽 처리를 향상시키기 위한 연구를 진행하고 있다. 본 고에서는 리눅스 진영에서 현재 진행중인 향상된 3D 그래픽 처리에 대한 기술 동향을 설명한다.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.3
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• pp.41-51
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• 1997

In this study, two types of the direct digital frequency synthesizers (DDFS) designed and implemented using 1.0.mu.m CMOS gatearray(SOG) technolgoies are interoduced. To analize the effect of the number of phase bits(L), address data bits(A), and DAC bits (D) on the output spectrums of the DDFSs, the NCO-based BCD-DDFS composed of L=24, A=14, and D=8, and the improved binary-DDFS composed of L=24, A=8, and D=10 have been studied. The chips have been designed with and without a noise shapper to reduce spurious noises due to phase truncation and reduced sine ROM in output spectrum.

• Transactions of Materials Processing
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• v.27 no.5
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• pp.314-322
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• 2018

AlSi12 is a heat-resistant aluminum alloy that is lightweight, corrosion-resistant, machinable and attracting attention as a functional material in aerospace and automotive industries. For that reason, AlSi12 powder has been used for high performance parts through 3D printing technology. The purpose of this study is to observe deposition characteristics of AlSi12 powder in a direct energy deposition (DED) process (one of the metal 3D printing technologies). In this study, deposition characteristics were investigated according to various process parameters such as laser power, powder feed rate, scan speed, and slicing layer thickness. In the single track deposition experiment, an irregular bead shape and balling or humping of molten metal were formed below a laser power of 1,000 W, and the good-shaped bead was obtained at 1.0 g/min powder feed rate. Similar results were observed in multi-layer deposition. Observation of deposited height after multi-layer deposition revealed that over-deposition occurred at all conditions. To prevent over-deposition, slicing layer thickness was experimentally determined at given conditions. From these results, this study presented practical conditions for good surface quality and accurate geometry of deposits.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.10a
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• pp.605-606
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• 2009

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.4
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• pp.64-71
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• 2008

SAW (Surface Acoustic Waves) ID (identification) tags have been designed and implemented for RFID (Radio frequency IDentification) systems. With SAW ID tag of pulse position encoding method, the data capacity increased 3 times compared with SAW ID tag of amplitude on/off method. Two different kinds of SAW ID tag receiver systems, heterodyne and homodyne receiver systems, were made. The direct conversion receiver showed better isolation property, 10 dB improvement than the heterodyne receiver to increase wireless interrogation distance.