• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.26 no.2
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• pp.157-164
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• 2008

GPS baseline analysis is a mathematical procedure which estimates a baseline vector from carrier-phase double-differenced observations. Least squares technique is generally applied for the processing and integer ambiguities in the observations should be resolved to obtain maximum accuracy of the solution. In GPS control surveying, after assembling the baseline solutions into a network, adjustment is performed to derive final coordinate sets of unknown points. This paper deals with details of GPS baseline analysis for the $2^{nd}$ order national geodetic network adjustment. After reviewing GPS campaigns carried out by National Geographic Information Institute (NGII) and their observations. technical issues and considerations for the GPS baseline analysis are presented with emphasis of selecting the processing strategies and software. Finally, the analyzed results will be evaluated by examining the close of figures formed by joining the processed baseline vectors.

• Journal of Korea Multimedia Society
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• v.12 no.4
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• pp.502-511
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• 2009

In order to simulate a depth-of-field effect in real world, there have been several researches in computer graphics field. It can represent an out-of-focused scene by calculating focal plane. When a point in a 3D coordinate lies on further or nearer than focal plane, the point is presented as a blurred circle on image plane according to the characteristic of the aperture and the lens. We can generate a realistic image by simulating the effect because it provides an out-of-focused scene like human eye dose. In this paper, we propose a method to calculate a disparity value of a viewer using a customized stereoscopic eye-tracking system and a GPU-based depth-of-field control method. They enable us to generate more realistic images reducing side effects such as dizziness. Since stereoscopic imaging system compels the users to fix their focal position, they usually feel discomfort during watching the stereoscopic images. The proposed method can reduce the side effect of stereoscopic display system and generate more immersive images.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.3 no.4
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• pp.867-873
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• 1999

Camera calibration is a procedure which calculates internal and external parameters of a camera with the Down world coordinates of the control points. Accurate camera calibration is required for achieving accurate visual measurements. In this paper, we propose a simple and flexible camera calibration using neural networks which doesn't require a special knowledge of 3D geometry and camera optics. There are some applications which are not in need of the values of the internal and external parameters. The proposed method is very useful to these applications. Also, the proposed camera calibration has advantage that resolves the ill-condition as object plane is near parallel image plane. The ill-condition is frequently met in product inspection. For little more accurate calibration, acquired image is divided into two regions according to radial distortion of lens and neural network is applied to each region. Experimental results and comparison with Tsai's algorithm prove the validity of the proposed camera calibration.

• Journal of Electrical Engineering and Technology
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• v.11 no.1
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• pp.157-166
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• 2016

In this paper, a new sag and peak voltage detector is proposed for a single-phase inverter using delta square operation. The conventional sag detector is from a single-phase digital phase-locked loop (DPLL) that is based on d-q transformations using an all-pass filter (APF). The d-q transformation is typically used in the three-phase coordinate system. The APF generates a virtual q-axis voltage component with a 90° phase delay, but this virtual phase cannot reflect a sudden change in the grid voltage at the instant the voltage sag occurs. As a result, the peak value is drastically distorted, and it settles down slowly. A modified APF generates the virtual q-axis voltage component from the difference between the current and the previous values of the d-axis voltage component in the stationary reference frame. However, the modified APF cannot detect the voltage sag and peak value when the sag occurs around the zero crossing points such as 0° and 180°, because the difference voltage is not sufficient to detect the voltage sag. The proposed algorithm detects the sag voltage through all regions including the zero crossing voltage. Moreover, the exact voltage drop can be acquired by calculating the q-axis component that is proportional to the d-axis component. To verify the feasibility of the proposed system, the conventional and proposed methods are compared using simulations and experimental results.

• 제어로봇시스템학회:학술대회논문집
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• 1994.10a
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• pp.561-565
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• 1994

An automatic measuring system of three dimensional shape by a projection method with grating pattern from in optical spatial modulator has been developed. The characteristics of the system were studied. This system is composed of a projector, an optical spatial modulator, a CCD camera, and computer. A liquid crystal is used as the optical spatial modulator. The grating patterns that ire projected on the surface of the object are controlled by the computer connected with the optical spatial modulator. The projector patterns are measured by the CCD camera. The data are transferred to the computer. After a transformation into line data, the data are analyzed to obtain the coordinate of the surface of the object. This system has advantages as follows. (1) It is possible to capture the surface topography without any contact. (2) The time required for the measurements is shorter than the light-section method. (3) An optical spatial modulator using a liquid crystal is possible to control the grating patterns accurately by a computer. Surfaces of a plate and a cylinder were measured. The threshold level had an influence on the measurement. It was shown that this system has adequae accuracy in the measurements.

• Journal of the Korean Society for Nondestructive Testing
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• v.22 no.5
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• pp.523-531
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• 2002

This study is concentrated on the development of high speed multi-object image processing algorithm in real time. Recently, the use of vision system is rapidly increasing in inspection and robot's position control. To apply the vision system, it is necessary to transform the physical coordinate of object into the image information acquired by CCD camera. Thus, to use the application of the vision system to the inspection and robot's position control in real time, we have to know the position of object in the image plane. Particularly, in case of rigid body using multi-cue to identify its shape, the each position of multi-cue must be calculated in an image plane at the same time. To solve these problems, the image processing algorithm on the position of multi-cue is developed.

• Journal of Bio-Environment Control
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• v.1 no.1
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• pp.72-83
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• 1992

우리 나라 축사는 생산효율 제고를 위하여 대형화, 밀폐화, 고밀도화, 자동화 경향이 뚜렷하다. 대형의 밀폐된 고밀도 축사는 쾌적한 실내환경을 전제로 하기 때문에 기계적으로 실내환경을 적절히 제어하지 않으면 안된다. 제한된 공간에 먼지, 병원성 미생물, 유해기체, 수분이나 열의 과도한 집적은 생산과 재생산효율에 심각한 영향을 미친다. 그러므로 축사내 생산주체인 가축과 작업인이 쾌적한 실내환경에서 생산활동을 할 수 있도록 열적, 화학적/생물학적 환경을 물리적으로 제어하지 않으면 안된다. 본 연구는 실험축사내 가축이 일정한 열을 발생할 때 실내공기의 유동형태를 예측하기 위해서 수행하였다. 이 연구의 결과를 실내환경제어를 위한 환기시스템 책략 개발의 기초자료로 활용할 수 있다. 실험축사내의 공기유동을 예측하기 위해 Body-Fitted Coordinate(BFC)의 격자배열과 k-$\varepsilon$ 난류모형 및 SIMPLE계열 solution scheme을 사용하였으며, 예측의 유효성 검정은 Boon(1978)의 실험결과를 이용하였다. 예측한 공기유동의 형태와 실험한 공기유동의 형태를 비교한 결과 대체로 만족할만한 결과를 얻었다. 그러나 유입공기의 온도가 1$0^{\circ}C$인 경우의 공기유동은 실험유동형태와 약간의 차이가 있었다. 즉, 실험에서는 수평슬롯으로 유입 된 공기가 바로 아래로 굴절되어 유동하였으나, 예측의 결과는 일정 거리로 수평방향으로 유동하다가 아래로 굴절하였다. 이런 유동의 차이는 k-$\varepsilon$ 난류모형 자체가 경험적으로 부력에 민감하게 반응않는 결함이 원인이 될 수도 있으며, 실험의 부적절한 수행이 원인이 될 수도 있다. 이 유동의 경우 Reynolds 수가 3,000정도의 난류이며, 완전발달유동 (fully-developed flow)이므로 관성력 (inertia force)이 부력 (buoyancy force)보다 커, 일정거리 수평으로 유동하다가 아래로 굴절할 수도 있기 때문이다. 앞으로 이를 규명하기 위한 보다 깊이 있는 연구가 이루어져야 할 것이다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.10
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• pp.4296-4301
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• 2011

Gantry loader which is also called as gantry robot is a kind of cartesian coordinate robot with two or more linear motions. A conventional gantry system has cableveyor for protecting power and signal cables, but the use of cableveyor makes a delay of work due to frequent repairing for its aging. This study reports that a wireless gantry loader is able to be operated without a power line for power transmission or a signal cable for motion control. The wireless gantry loader enables a convenient maintenance and a stable productivity by the reduction of wire broken from fatigue. The developed loader system is controlled by PC-based motion controller and is communicated by wireless LAN devices. The line from a power source to the loader system was substituted by attaching trolley bar on the traveling beam. The loader system was designed to be moved with high speed and high repeatability, and the motion was observed continuously by monitoring system in the PC-based controller. The maximum speed and the repeatability for the transferring and loading axes are 200 m/min, 60 mm and 100 m/min, 40 mm respectively.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.25 no.5
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• pp.465-474
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• 2007

This paper focuses on examining and evaluating results of the Korean Geodetic Datum 2002 (KGD2002) of the national horizontal network adjustment. To this end, 137 geodetic control points were independently observed by GPS technology. After processing all the observations, their results were compared with ones derived by the national network adjustment which was recently performed to determine new KGD 2002 coordinate sets over the national geodetic control points. The comparisons results showed that RMSE was ${\pm}2.7cm$ and ${pm}6.5cm$ in horizontal and vertical component in the case of GPS network, whereas RMSE was ${\pm}3.0cm$, in horizontal component in the case of EDM network.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.29 no.6
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• pp.687-695
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• 2011

Many internet portals provide maps with spatial information services. Recently, various images including aerial, satellite, street view, and photo-realistic 3D city models are provided as well as maps. This study suggested a method for geometric correction of the panoramic aerial images in the internet portal and 3D building modeling using information which is available in the internet. The key of this study is to obtain all necessary data easily from internet without restrictions. Practically, the ground control coordinates could be available from geo-referenced internet maps, and stereo pairs of the aerial images and close-range photographs for photo-realistic object modeling are provided by the internet service. However, the ground control points are not suitable for accurate mapping. RMSE of the plotting was about 9 meters and reduced upto 4 meters after coordinate transformation. The proposed methods would be applicable to various applications of photo-realistic object modeling which do not require high accuracy.