• 농업과학연구
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• 제37권3호
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• pp.471-479
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• 2010

Forest roads of 16,424km have been constructed as infrastructure for efficient management of forest. The demand of forest road have been also increased steadily with SOC conception for forest management and wood production. But, accuracy verification by completion drawing of forest road needed aspects extration of geographic information to sound like forest road construction and completion drawing. However, verification for completion drawing has not ascertained. This study carried out the evaluation for position accuracy about constructed forest road in Chungcheongnam-do for evaluating horizontal position accuracy of completion drawing of forest road. In result, first of distance of completion drawing and real route designed completion drawing longer than the real route as Gongju 83m, Seosan 66m, Nonsan 27m and Dangjin 19m, respectively. Second, RMSE by point-correspondence was 11m~14.7m, buffering analysis appeared difference of 18~24m. Finally, index of shape was the similar completion and real route through 6.5~7.4 and data information of forest road corresponds to be perfect. For such reasons, the existing completion drawings have a problem that it cannot use graphic information for drawing digital map according to the regulation, and there is an urgent need for improvement to solve this problem in the process of design and construction.

• 대한공간정보학회지
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• 제24권3호
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• pp.3-9
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• 2016

UAV(unmanned aerial vehicle)은 적은 비용으로 고해상도 정사영상과 DSM(digital surface model)을 빠르게 생성할 수 있다. 그러나, UAV에 의하여 획득된 정사영상과 DSM의 수직 및 수평위치 정확도는 영상처리 기술, 항공사진의 품질, GCPs(ground control points)의 개수와 위치, 촬영경로 상의 중복도에 영향을 받는다. 본 연구에서는, 정사영상과 DSM의 생성에 있어 중복도와 GCP의 개수가 미치는 영향을 분석하고자 하였다. 위치정확도는 9쌍의 자료를 이용한 RMSE(root mean square error)을 기반으로 평가하였다. 실험결과, GCP의 개수와 중복도는 수평위치 및 수직위치 정확도에 영향을 미치는 것을 확인하였다.

• 방송공학회논문지
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• 제19권6호
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• pp.789-797
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• 2014

일반적으로 격행주사(interlace) 된 Side-by-Side (SbS) 영상의 경우 화면 재생 시, 전송받은 영상을 먼저 디인터레이싱(de-interlacing)한 후에 좌우 영상을 분리하여 수평 해상도를 보간하는데, 이때 한번 가공된 디인터레이싱 값을 참조하여 보간 값을 결정하게 되는 관계로 수평 해상도의 정확성이 크게 떨어지게 된다. 이러한 문제점을 해결하기 위해 격행주사 방식의 SbS 3D 영상의 수평 해상도 보간 방법을 제안한다. 수평 해상도 보간 시에 격행주사 방식으로 전송받은 라인과 디인터레이싱 기법을 이용해 보간한 라인의 특성에 따라 각 라인에서 활용할 수 있는 전송받은 값을 가지고 각각 다른 보간 방법을 적용함으로써 정확도를 향상하는 방법을 제안한다. 제안된 방법의 실험 결과는 기존의 보간 기법들보다 주관적, 객관적 화질에서 더욱 우수한 성능을 보여준다.

• Journal of Mechanical Science and Technology
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• 제15권12호
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• pp.1711-1727
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• 2001

Heat transfer coefficient were measured and new correlations were developed for two-phase heat transfer in a horizontal pipe for different patterns. Flow patterns were observed in a transparent circular pipe (2.54 cm I. D. and L/D=96) using an air/water mixture. Visual identification of the flow patterns was supplemented with photographic data and the results were plotted on the flow regime map proposed by Taitel and Dukler and agreed quite well with each other. A two-phase heat transfer experimental setup was built for this study and a total of 150 two-phase heat transfer data with different flow patterns were obtained under a uniform wall heat flux boundary condition. For these data, the superficial Reynolds number ranged from 640 to 35,500 for the liquid and from 540 to 21,200 for the gas. Our previously developed robust two-phase heat transfer correlation for a vertical pipe with modified constants predicted the horizontal pipe air-water heat transfer experimental data with good accuracy. Overall the proposed correlations predicted the data with a mean deviation of 1.0% and an rms deviation of 12%.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2002년도 금형가공 심포지엄
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• pp.53-60
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• 2002

Recently, the development of aerospace and automobile industries brought new technological challenges, related to the growing complexity of products and new geometry models. High speed machining using 5-Axis milling machine is widely used for 3D sculptured surface parts. 5-axis milling of turbine blade generates the vibration, deflection and twisting caused from thin and cantilever shape. So, the surface roughness and the waviness of workpiece are not good. In this paper, The effects of cutter orientation and lead/tilt angle in 5-Axis high speed ball end-milling of turbine blade were investigated to improve the geometric accuracy and surface integrity. The experiments were performed at lead/tilt angle $15^{\circ}$ of workpiece with four cutter directions such as horizontal outward, horizontal inward, vertical outward, and vertical inward. Workpiece deflection, surface roughness and machined surface were measured with various cutter orientations such as cutting direction, and lead/tilt angle. The results show that when 5-axis machining of turbine blade, the best cutting strategy is horizontal inward direction with tilt angle. The results show that when 5-axis machining of turbine blade, the best cutting strategy is horizontal inward direction with tilt angle.

• Geomechanics and Engineering
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• 제24권5호
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• pp.491-503
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• 2021

Shallow tunnels are vulnerable to earthquakes, and shallow ground is usually inhomogeneous. Based on the limit equilibrium method and variational principle, a solution for the seismic collapse mechanism of shallow tunnel in inhomogeneous ground is presented. And the finite difference method is employed to compare with the analytical solution. It shows that the analytical results are conservative when the horizontal and vertical stresses equal the static earth pressure and zero at vault section, respectively. The safety factor of shallow tunnel changes greatly during an earthquake. Hence, the cyclic loading characteristics should be considered to evaluate tunnel stability. And the curve sliding surface agrees with the numerical simulation and previous studies. To save time and ensure accuracy, the curve sliding surface with 2 undetermined constants is a good choice to analyze shallow tunnel stability. Parameter analysis demonstrates that the horizontal semiaxis, acceleration, ground cohesion and homogeneity affect tunnel stability greatly, and the horizontal semiaxis, vertical semiaxis, tunnel depth and ground homogeneity have obvious influence on tunnel sliding surface. It concludes that the most applicable approaches to enhance tunnel stability are reducing the horizontal semiaxis, strengthening cohesion and setting the tunnel into good ground.

• Journal of Astronomy and Space Sciences
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• 제20권4호
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• pp.359-364
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• 2003

In this paper, we present multi-sensor data fusion for telematics application. Successful telematics can be realized through the integration of navigation and spatial information. The well-determined acquisition of vehicle's position plays a vital role in application service. The development of GPS is used to provide the navigation data, but the performance is limited in areas where poor satellite visibility environment exists. Hence, multi-sensor fusion including IMU (Inertial Measurement Unit), GPS(Global Positioning System), and DMI (Distance Measurement Indicator) is required to provide the vehicle's position to service provider and driver behind the wheel. The multi-sensor fusion is implemented via algorithm based on Kalman filtering technique. Navigation accuracy can be enhanced using this filtering approach. For the verification of fusion approach, land vehicle test was performed and the results were discussed. Results showed that the horizontal position errors were suppressed around 1 meter level accuracy under simulated non-GPS availability environment. Under normal GPS environment, the horizontal position errors were under 40㎝ in curve trajectory and 27㎝ in linear trajectory, which are definitely depending on vehicular dynamics.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권2호
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• pp.723-743
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• 2016

Indoor positioning is considered an enabler for a variety of applications, the demand for an indoor positioning service has also been accelerated. That is because that people spend most of their time indoor environment. Meanwhile, the smartphone integrated powerful camera is an efficient platform for navigation and positioning. However, for high accuracy indoor positioning by using a smartphone, there are two constraints that includes: (1) limited computational and memory resources of smartphone; (2) users' moving in large buildings. To address those issues, this paper uses the TC-OFDM for calculating the coarse positioning information includes horizontal and altitude information for assisting smartphone camera-based positioning. Moreover, a unified representation model of image features under variety of scenarios whose name is FAST-SURF is established for computing the fine location. Finally, an optimization marginalized particle filter is proposed for fusing the positioning information from TC-OFDM and images. The experimental result shows that the wide location detection accuracy is 0.823 m (1σ) at horizontal and 0.5 m at vertical. Comparing to the WiFi-based and ibeacon-based positioning methods, our method is powerful while being easy to be deployed and optimized.

• 생물환경조절학회지
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• 제13권2호
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• pp.90-95
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• 2004

대립종자의 자동정렬파종기의 씨눈위치 자동판정장치를 개발하기 위한 연구로서 수행된 이 연구는 기계 시각을 이용하여 대립종자의 씨눈 위치가 공급 방향을 기준으로 앞 또는 뒤쪽 어느 쪽에 위치해 있는지를 검출하기 위함이다. 참박, 특토좌, 흑종에 대한 씨눈위치를 판정하기 위하여 종자의 공급자세에 따른 판정정도를 조사하였다. 참박의 경우 공급자세가 $30^{\circ}$ 경우에는 77.8%의 정확도를 나타냈지만,$ 0^{\circ}$와 $15^{\circ}$때는 100% 검출 정확도를 나타내었다. 특토좌의 경우 공급자세 $30^{\circ}$에서 89.5%, $0^{\circ}$와 $15^{\circ}$에서는 100%의 판정 정확도가 나타났다. 흑종의 경우에 있어서는 공급자세 $30^{\circ}$에서 94.4%이었고 나머지는 100%의 정확도를 나타냈다. 따라서 정렬파종장치의 공급부에서 종자가 공급될 때 기계적인 메카니즘으로 $30^{\circ}$ 이상 기울어지는 것을 방지할 수 있고 $15^{\circ}$까지 기울어진다 해도 씨눈위치를 판정할 수 있기 때문에 향후 파종장치의 한 부분으로서 사용할 수 있을 것으로 판단되었다.

• Journal of Positioning, Navigation, and Timing
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• 제5권4호
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• pp.213-219
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• 2016

Most existing studies on the wide-area differential global positioning system (WADGPS) employed a grid ionosphere model for error correction in the ionospheric delay. The present study discusses the application of satellite-based ionospheric delay model that provides an error model as a plane function with regard to individual satellites in order to improve accuracy in the WADGPS. The satellite-based ionospheric delay model was developed by Stanford University in the USA. In the present study, the algorithm in the model is applied to the WADGPS system and experimental results using measurements in the Korean Peninsula are presented. Around 1 m horizontal accuracy was exhibited in the existing planar fit grid model but when the satellite-based model was applied, correction performance within 1 m was verified.