• The Journal of the Acoustical Society of Korea
• /
• v.19 no.3
• /
• pp.3-10
• /
• 2000

This paper proposes acoustic holographic measuring system to estimate an absolute position of sound source. Using the measured signals, the estimation of the position is calculated by the Cross-spectrum algorithm of the beamformed signal and a linear arrayed microphone's signals. As the results of comparing the reference microphone method with beamforming method through the measurement of sound field, the beamforming acoustic holographic method is progressed above 20 percent than that of a reference microphone method in the resolution, and the utility of the proposed system could be confirmed.

• Proceedings of the Korean Information Science Society Conference
• /
• 2012.06b
• /
• pp.498-500
• /
• 2012

비디오 해석 및 추적기술은 특정한 시스템에서만 적용되는 것이 아니다. 이것은 비디오 내에서 의미 있는 정보를 능동적으로 감시 대상을 정의, 해석, 모델화, 추정 및 추적 할 수 있는 기반 기술을 의미하다. 일반적으로 감시시스템에서 감시 대상은 사람이나 차량이며, 상황에 따라 출입통제 구역으로 설정하기도 한다. 이는 연속된 영상에서 객체의 형태, 모양, 행동 분석, 움직임, 색상정보를 가지고 데이터 정의, 검출, 모델화를 통하여 인식, 식별 그리고 추적한다. 본 논문에서는 비디오 영상분석을 통해 단일카메라기반의 감시시스템과 PTZ 카메라기반 감시시스템 제안한다. 이때 단일 카메라기반의 감시는 배경생성방법을 이용하여 연속된 영상내의 객체를 지속적으로 관리가 가능하도록 설계하였고, PTZ 카메라기반의 감시는 카메라의 이동에 따른 배경안정화 방법과 카메라의 절대좌표를 활용하여 카메라 이동을 제어함과 동시에 오검출 문제를 해결하였다. 실험 및 결과분석으로는 시나리오 환경에서 배경생성방법을 이용한 검출의 정확성과 PTZ카메라 위치 변화에도 강인한 검출 결과를 비교 분석하였다.

• Journal of Korean Society of Transportation
• /
• v.23 no.1
• /
• pp.93-102
• /
• 2005

An Origin-Destination (O/D) is considered as one of the important information in route choices and trip assignments. A household interview survey is deemed to be the traditional and the most widely used method in making sample O/D and its conversion to the total O/D. Some researchers have studied to estimate dynamic O/D from the relationship between link volumes and trip assignment model. Nowadays, owing to the recent rapid spread of cellular phones. Location information of the cellular phone through the Base Station(BS) is considered as an alternative to O/D estimation. In this study, the methodology of generating BS-based O/D and the methodology of converting this O/D into an administrative district-based O/D are proposed. The information of GPS positions and cellular BS positions have acquired by establishing GPS equipment and cellular phone on taxies in Cheongju. Three weeks data are collected and used in estimating O/D by matching them on a digital map. Scatter diagram and sample correlation coefficients are used to investigate the similarity of the GPS-based O/D pattern among weeks, among days, and among times in day. The results show that there are few significant differences among weeks. But there is a difference in O/C pattern between weekday and weekend. Furthermore, there is a difference between morning peak and afternoon peak. Two methodologies are proposed to convert BS-based O/D into an administrative district-based O/D. The first one is to use the distribution pattern of GPS coordinates, the other is to use the coverage area of the BSs. To validate such converted O/D, GPS O/D is used as a true value. The statical analyses through scatter diagram, MAE and RMSE shows that there is few significant defference of pattern between the estimated BS-based O/D and GPS O/D. In the case of using only cellular information, the methodology using coverage area of the BSs is recommended for estimating O/D.

• Korean Journal of Ecology and Environment
• /
• v.39 no.1 s.115
• /
• pp.13-20
• /
• 2006

The changing patterns of water temperature and turbidity in streams entering Imha Reservoir were studied. The turbidity variation near the intake tower in Imha Reservoir was investigated in relation with the variation of water temperature and turbidity in streams. Water temperature was estimated using multi-regression method with air temperature and dew point as independent variables. Peak turbidity was also estimated using non-linear regression method with rainfall intensity as an independent variable. Although more independent variables representing watershed characteristics seem to be needed to increase estimation accuracies, the methodology used in this study can be applied to estimate water temperature and peak turbidity in other streams.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.54 no.2
• /
• pp.123-129
• /
• 2017

This paper proposes a new nonnegative matrix factorization (NMF) based direction-of-arrival (DOA) estimation method for multiple sound sources using a dual microphone array. First of all, sound signals coming from the dual microphone array are segmented into consecutive analysis frames, and a steered-response power phase transform (SRP-PHAT) beamformer is applied to each frame so that stereo signals of each frame are represented in a time-direction domain. The time-direction outputs of SRP-PHAT are stored for a pre-defined number of frames, which is referred to as a time-direction block. Next, In order to estimate DOAs robust to noise, each time-direction block is normalized along the time by using a block subtraction technique. After that, an unsupervised NMF method is applied to the normalized time-direction block in order to cluster the directions of each sound source in a multiple sound source environments. In particular, the activation and basis matrices are used to estimate the number of sound sources and their DOAs, respectively. The DOA estimation performance of the proposed method is evaluated by measuring a mean absolute error (MAE) and the standard deviation of errors between the oracle and estimated DOAs under a three source condition, where the sources are located in [$-35{\circ}$, 5m], [$12{\circ}$, 4m], and [$38{\circ}$, 4.m] from the dual microphone array. It is shown from the experiment that the proposed method could relatively reduce MAE by 56.83%, compared to a conventional SRP-PHAT based DOA estimation method.

• Journal of the Korean Geographical Society
• /
• v.49 no.5
• /
• pp.747-760
• /
• 2014

This study presents the extent of disparity of human capital across regions, its trend, and the impact of aging on it, using Korean census data of years 1985, 1995, and 2005. Main results are as follows. First, the absolute level of human capital in cities and districts have increased, but the relative positions of those regions have not changed over time. Second, the proportion of college graduated tends to increase as the size of cities increases. Third, following Berry and Glaeser(2005), the increase in the proportion of college graduated is regressed on the initial proportion and the estimates indicate that the disparity of human capital across regions has increased over time. Fourth, the proportion of aging population is shown to have a negative relationship with the proportion of college graduated. Finally, using a counter-factual scenario that there were no differences in proportions of aging population across regions, it is shown that the disparity of human capital across regions could be reduced substantially.

• Journal of Korean Society of Forest Science
• /
• v.104 no.3
• /
• pp.368-374
• /
• 2015

On the basis of vegetation data by point quarter sampling method, the natural forest of Jirisan(Mt.) was classified into eight forest types by cluster analysis. They were Quercus mogolica forest type, Fraxinus mandshurica - Betula costata forest type, Mixed mesophytic forest type, Abies koreana forest type, Carpinus laxiflora forest type, Quercus serrata forest type, Pinus densiflora forest type, and Quercus variabilis forest type. Then, succession index was estimated for each forest type so as to evaluate succession process comparatively among forest types. The results showed that Carpinus laxiflora forest type had highest succession index of 219.7, followed by Mixed mesophytic forest type with little difference of the index of 218.3. Pinus densiflora forest type had lowest index. Succession indices were hardly correlated with species diversity indices of forest types. We presumed that the higher value of succession index a forest type had, the closer toward the climax forest. However, the estimated index was not supposed to be absolute level of successional stage, but it could play a role of comparative assessment in the position of the seral stage among forest types.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.40 no.3
• /
• pp.588-594
• /
• 2015

Although GPS technology for location positioning system has been widely used, it is difficult to be used in intelligent transport systems, due to the large positioning error and limited area for receiving radio signals. Thanks to the rapid development of LED technology, LED lights become popular in many applications. Especially, visible light communications (VLC) has raised a lot of interests because of the simultaneous functioning of LED illumination and communication. Recent studies on positioning system using VLC mainly focused on indoor environments and still difficult to satisfy positioning accuracy and simple implementation simultaneously. In this paper, we propose a positioning system based on VLC using the coordinate information of LEDs installed on the road infrastructure. Extracting the LED signal, obtained through VLC, from the easily accessible camera image, it is possible to estimate the position of the car on the road. Simulation results show that the proposed scheme can achieve a high positioning accuracy of 1 m when large number of pixels is utilized and the distance from the LED light is close.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.29 no.2
• /
• pp.201-208
• /
• 2011

With the increase in the number of smartphone users, precise 3D positional information is required by various applications. The positioning accuracy using civilian single-frequency pseudoranges is at the level of 10 m or so, but most applications these days are asking for a sub-meter level Therefore, instead of an absolute positioning technique, the VRS-based differential approach is applied along with the correction of the double-differenced (DD) residual errors using FKP (Flachen-Korrektur-Parameter). The VRS (Virual Reference Station) is located close to the rover, and the measurements are generated by correcting the geometrical distance to those of the master reference station. Since the unmodeled errors are generally proportional to the length of the baselines, the correction parameters are estimated by fitting a plane to the DD pseudorange errors of the CORS network. The DD positioning accuracy using 24 hours of C/A code measurements provides the RMS errors of 37 cm, 28 cm for latitudinal and longitudinal direction, respectively, and 76 cm for height. The accuracy of the horizontal components is within ${\pm}0.5m$ for about 90% of total epochs, and in particular the biases are significantly decreased to the level of 2-3 cm due to the network-based error modeling. Consequently, it is possible to consistently achieve a sub-meter level accuracy from the single-frequency pseudoranges using the VRS and double-differenced error modeling.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2005.05b
• /
• pp.996-1000
• /
• 2005

본 연구에서는 마포대교 확장 공사의 인해 일부 교각의 우물통 기초 주변 하상변화와 세굴 현상을 파악하기 위한 심도추정 방법으로 현재 다양하게 토목분야에서 적용되고 있는 치하투과레이더 탐사기법을 사용하였다. 교각 우물통 주변의 안정적인 GPR 탐사를 수행하기 위한 보조장비를 고안하여 마포대교 P6의 우물통 주변을 2004년 6월(1차)과 2004년 10월(2차)에 걸쳐 탐사를 실시하였으며, 탐사 기간 중 약 12,000 cms의 유출량이 발생하여 국부세굴과 하상 변화 가능성을 충분히 검토 할 수 있을 것으로 판단되었다. 수집된 자료를 통해 양질의 자료 획득을 위해서 자료의 보정 과정을 마친 후 각각의 구간에 대해서 1, 2차 탐사된 두 개의 자료를 비교 분석하였다. 전구간의 반사파를 이용하여 기존의 연구결과에서 얻어진 반사파의 양상(Beres and Haeni, 1991)과 비교한 결과 하상 표면은 미사 혹은 실트로 구성되어 있고 주요한 하상 하부 매질은 전석(boulder), 호박돌 등으로 이루어져 있었다. 그리고 1차 및 2차 탐사 자료와 DATAPCS의 세굴센서가 설치된 측점을 기준으로 심도 및 위치 보정을 한 결과 큰 오차는 발생하지 않았으며, 400 MHz 안테나를 활용하여 최대수심 약 10 m 이상 하상을 탐사할 수 있었다. 수심이 깊은 구간은 하상과 가까운 위치에서 탐사를 실시하여 양질의 하상 변화 양상을 파악할 수 있어 하상 재료의 정성적인 평가를 높일 수 있도록 하였다. 마포대교의 탐사 대상 교각 우물통 주변은 계획홍수량의 1/3 수준으로 비교적 적은 홍수량이 발생한 2004년의 호우사상으로 인해 일부구간이 약 $10\~20\;cm$ 정도의 퇴적과 세굴 영향이 나타난 것을 제외하고는 유의할 만한 세굴과 하상 변화가 발생하지 않고 매우 안정적인 상태를 보이고 있으며 되메움이나 두드러진 퇴적층의 양상 또한 확인할 수 없었다. 대상구간에 설치한 유속계 최대유속이 2.0 m/s 이상 발생하였지만 우물통 주변의 자갈 및 호박돌 등과 같은 평균입경이 큰 유사의 이동에 절대적인 한계유속을 초과하지 못한 것으로 판단된다. GPR 탐사의 적용 한계성을 극복한 본 연구는 홍수 전$\cdot$후의 하상변화 및 최대세굴심, 되메움 깊이 및 범위 등의 세굴현상을 현장탐사를 바탕으로 현재 다양하게 적용하고 있는 세굴 실험식과 비교 분석함으로써 우물통 주변의 효율적인 세굴 보호 대책을 강구하는 목적으로 그 활용성을 증대할 수 있을 것이다.