• Korean Journal of Cognitive Science
• /
• v.22 no.2
• /
• pp.103-121
• /
• 2011

This study investigated how spatial dimension information and dimensional consistency between learning and testing phase would influence the target search performance. The participants learned spatial layouts of Lego blocks shown in either two- (2D) or three-dimension (3D) and were tested with the rotated stimuli ($0^{\circ}$, $90^{\circ}$, $180^{\circ}$, or $270^{\circ}$ from the initial view) in consistent or inconsistent dimension. Significantly better performance was observed when initial learning display appeared in 2D than in 3D. Particularly, the participants showed difficulties in flexible usage of spatial information presented in 3D especially if the dimensional information in the testing phase also was 3D and required mental rotation. The present study indicates that spatial map presented in 2D may be more useful than 3D in driving situations in which acquired spatial information from navigating device, such as GPS, and location of driver continuously changes.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.16 no.1
• /
• pp.169-175
• /
• 2016

Geofence is a virtual perimeter for a real-world geographical area, which could be statically or dynamically established the specified area if necessary. Many geofencing applications incorporate 2D(two-dimensional) map such as the Google map, allowing administrators to define boundaries on top of a satellite view of a specific geographical area. But these applications do not provide 3D(three-dimensional) spatial information as well as 2D location information no matter where indoor or outdoor. Therefore we propose a mechanism to identify indoor or outdoor location for 3D geofence, and implement 3D geofence using smartphone. The proposed mechanism identifies the position information on 3D geofence regardless of indoor or outdoor, inter-floor with only GPS and WiFi. In the near future, 3D geofence as well as LBS are promising applications that become possible when IoT can become organized and connected by location.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.33 no.3
• /
• pp.1191-1202
• /
• 2013

The former researches on earthwork automation were mainly focused on GPS and sensor application, environment modelling, equipment path planning, work information management, and remote control etc. Recently, reducing $CO_2$ emission becomes one of main focuses for an automation research. In the case of earthwork operations, many kinds of construction machines or robots are involved, which can cause high level of $CO_2$ in a construction site. An effective earthwork plan and construction machine operation can both increase productivity and safety and decrease $CO_2$ emission level. In this research, some automation concepts for green earthworks are suggested such as a 3D construction site model, a 3D earthwork distribution based on two different earthwork methods, and an earthwork package construction method. A excel-based simulator is developed to generate the 3D earthwork distribution and to estimate the level of $CO_2$ emission for the given earthwork.

• Journal of Ocean Engineering and Technology
• /
• v.19 no.2 s.63
• /
• pp.74-81
• /
• 2005

A 3-D localization method of an autonomous underwater vehicle (AUV) has been developed, which can solve the limitations oj the conventional localization, such as LBL or SBL that reduces the flexibility and availability of the AUV. The system is composed of a mother ship (small unmanned marine prober) on the surface of the water and an unmanned underwater vehicle in the water. The mother ship is equipped with a digital compass and a GPS for position information, and an extended Kalman filter is used for position estimation. For the localization of the AUV, we used only non-inertial sensors, such as a digital compass, a pressure sensor, a clinometer, and ultrasonic sensors. From the orientation and velocity information, a priori position of the AUV is estimated by applying the dead reckoning method. Based on the extended Kalman filter algorithm, a posteriori position of the AUV is, then, updated by using the distance between the AUV and a mother ship on the surface of the water, together with the depth information from the pressure sensor.

• International Journal of Aeronautical and Space Sciences
• /
• v.5 no.1
• /
• pp.94-100
• /
• 2004

Ionospheric time delay is the biggest error source for single-frequency DGPSapplications, including time transfer and Wide Area Differential GPS (WADGPS).Currently, there are many attempts to develop real-time ionospheric time delayestimation techniques to reduce positioning error due to the ionospheric time delay.Klobuchar model is now widely used for ionosphehc time delay calculation forsingle-frequency users. It uses flat surface at night time and cosine surface atdaytime[1], However, the model was developed for worldwide ionosphere fit, it isnot adequate for local area single-frequency users who want to estimateionospheric time delay accurate1y[2]. Therefore, 3-D ionosphere model usingtomographic estimation has been developed. 3-D tomographic inversion modelshows better accuracy compared with prior a1gorithms[3]. But that existing 3-Dmodel still has problem that it requires many coefficients and measurements forgood accuracy. So, that algorithm has Umitation with many coefficients incontinuous estimation at the small region which is obliged to have fewermeasurements.In this paper, we developed an modified 3-D ionosphehc time delay modelusing tomography, which requires only fewer coefficients. Because the combinationsof our base coefficients correspond to the full coefficients of the existing model, ourmodel has equivalent accuracy to the existing. We confirmed our algorithm bysimulations. The results proved that our modified algohthm can perform continuousestimation with fewer coefficients.

• Journal of electromagnetic engineering and science
• /
• v.14 no.4
• /
• pp.360-366
• /
• 2014

A single-feed composite cavity-backed four-arm curl antenna is presented for use in global positioning systems (GPS). Its primary radiating element is fed by a vacant-quarter printed ring, which helps the antenna directly match to a $50-{\Omega}$ coaxial line and produce a good circular polarization (CP). The cavity-backed reflector is employed to improve the CP radiation characteristics in terms of 3-dB axial ratio (AR) beamwidth and minimum AR value. The optimized design with an overall size of $90{\times}90{\times}25mm^3$ ($0.4725{\lambda}_o{\times}0.4725{\lambda}_o{\times}0.13{\lambda}_o$ at 1,575 MHz) results in a ${\mid}S_{11}{\mid}<-10dB$ bandwidth of 8.66% (1,514-1,651 MHz) and a 3-dB AR bandwidth of 2.23% (1,555-1,590 MHz). The antenna radiates a widebeam right-hand circular polarization and operates with a measured radiation efficiency greater than 90% within its impedance matching bandwidth.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• v.2
• /
• pp.71-76
• /
• 2006

With the rapid development of spatial infrastructure in US, Europe, Japan, China and India, there is no doubt that the next generation Global Navigation Satellite System (GNSS) will improve the integrity, accuracy, reliability and availability of the position solution. GNSS is becoming an essential element of personal, commercial and public infrastructure and consequently part of our daily lives. However, the applicability of GPS in supporting a range of location-sensitive applications such as location based services in an urban environment is severely curtailed by the interference of the 3D urban settings. To characterize and gain in-depth understanding of such interferences and to be able to provide location-based optimization alternatives, a high-fidelity 3D urban model of Melbourne CBD built with ArcGIS and large scale high-resolution spatial data sets is used in this study to support a comprehensive simulation of current and future GNSS signal performance, in terms of signal continuity, availability, strength, geometry, positioning accuracy and reliability based on a number of scenarios. The design, structure and major components of the simulator are outlined. Useful time-stamped spatial patterns of the signal performance over the experimental urban area have been revealed which are valuable for supporting location based services applications, such as emergency responses, the optimization of wireless communication infrastructures and vehicle navigation services.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2016.05a
• /
• pp.162-162
• /
• 2016

본 연구에서는 한국 낙동강에 위치한 강정-고령보에 설치된 by-pass 어도의 유인효율을 유량 변화에 따라 살펴보고, 어도 유인효율을 극대화할 수 있는 최적의 본류 방류량을 산정하였다. 강정-고령보는 고정보와 가동보로 구성된 혼합식 보로 유량조절이 가능하며, 가동보의 조작에 따라 by-pass 어도 내의 유량이 결정된다. 유인효율의 지표로 목표어종의 HSC(Habitat Suitability Criteria) 지수에 기반한 WUA(Weighted Usable Area)를 삼았다. WUA는 평면 2차원 물리서식처 모형인 River2D를 활용하여 계산하였다. 또한 River2D로 계산된 유속장은 GPS Floater를 활용한 현장관측 자료로 검증하였으며, 어망을 이용한 월별 어류 모니터링 자료로 유인효율 평가의 타당성을 간접적으로 검증하였다. 결과적으로 본 연구 대상인 강정-고령보의 by-pass 어도에서 가장 효과적으로 목표 어류를 유인하기 위해서는 본류의 유량이 190 cms내외를 유지해야 한다. 특히 목표 어류인 모래무지가 봄철(4월~6월)에 산란기를 맞아 상하류로 이동하려는 경향을 띄므로, 이때 적절한 가동보 운영을 통해 본류 유량을 190 cms로 유지하는 것이 필요하리라 사료된다.

• Bulletin of the Korean Mathematical Society
• /
• v.59 no.2
• /
• pp.285-301
• /
• 2022

In this paper, we mainly study the random sampling and reconstruction of signals living in the subspace V^p(𝚽, 𝚲) of L^p(ℝ^d), which is generated by a family of molecules 𝚽 located on a relatively separated subset 𝚲 ⊂ ℝ^d. The space V^p(𝚽, 𝚲) is used to model signals with finite rate of innovation, such as stream of pulses in GPS applications, cellular radio and ultra wide-band communication. The sampling set is independently and randomly drawn from a general probability distribution over ℝ^d. Under some proper conditions for the generators 𝚽 = {𝜙_λ : λ ∈ 𝚲} and the probability density function 𝜌, we first approximate V^p(𝚽, 𝚲) by a finite dimensional subspace V^p_N (𝚽, 𝚲) on any bounded domains. Then, we prove that the random sampling stability holds with high probability for all signals in V^p(𝚽, 𝚲) whose energy concentrate on a cube when the sampling size is large enough. Finally, a reconstruction algorithm based on random samples is given for signals in V^p_N (𝚽, 𝚲).

• Journal of Korean Society for Geospatial Information Science
• /
• v.17 no.1
• /
• pp.157-166
• /
• 2009

There is a growing interest in ubiquitous-related research and applications. Among them, GPS-based LBS have been developed and used actively. Recently, with the increase of large size buildings and disastrous events, indoor spaces are getting attention and related research activities are being carried out. Core technologies regarding indoor applications may include 3D indoor data modeling and localization sensor techniques that can integrate with indoor data. However, these technologies have not been standardized and established enough to be applied to indoor implementation. Thus, in this paper, we propose a method to build a relatively simple 3D indoor data modeling technique that can be applied to indoor location based applications. The proposed model takes the form of 2D-based multi-layered structure and has capability for 2D and 3D visualization. We tested three prototype applications using the proposed model; CA(cellular automata)-based 3D evacuation simulation, network-based routing, and indoor moving objects tracking using a stereo camera.