• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.12
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• pp.734-739
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• 2018

The National Forestry Inventory of Korea has started the 7th (2016 ~ 2020) survey from the first (1972 ~ 1974) National Forest Situation Survey. The diameter at breast height was measured using a diameter tape, and the tree height was measured using a hypsometer in the National Forestry Inventory of Korea from the 1st to recently the 7th surveying. In the case of the diameter tape, however, irregularly shaped trees may cause a large error. In the case of a hypsometer, the height may be measured indirectly in 10 cm increments to the front edge of the tree, so that the accuracy may be lowered. This paper suggests the use of SLAM to improve the accuracy and advance forest investigations. For this purpose, a test bed for the measurement of DBH and tree height was set up, and the scan data was acquired directly using SLAM equipment. The accuracy of DBH and tree height measurements were analyzed. As a result, it was possible to calculate directly the DBH and tree height to 1mm unit, and it showed that the DBH accuracy of 2cm or less and the accuracy of the tree height accuracy of 1.3cm or less are sufficient for practical use. Based on the results, the scan data will be acquired for sample points and analyzed.

• Geophysics and Geophysical Exploration
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• v.8 no.1
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• pp.18-25
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• 2005

We derive refraction statics for seismic data recorded in a hard rock terrain, in which there are large and rapid variations in the depth of weathering. The statics corrections range from less than 10 ms to more than 70 ms, often over distances as short as 12 receiver intervals. This study is another demonstration of the importance in obtaining accurate initial refraction models of the weathering in hard rock terrains in which automatic residual statics may fail. We show that the statics values computed with a simple model of the weathering using the Generalized Reciprocal Method (GRM) and the Refraction Convolution Section (RCS) are comparable in accuracy to those computed with a more complex model of the weathering, using least-mean-squares inversion with the conjugate gradient algorithm (Taner et al., 1998). The differences in statics values between the GRM model and that of Taner et al. (1998) systematically vary from an average of 2ms to 4ms over a distance of 8.8 km. The differences between these two refraction models and the final statics model, which includes the automatic residual values, are generally less than 5 ms. The residuals for the GRM model are frequently less than those for the model of Taner et al. (1998). The RCS statics are picked approximately 10 ms later, but their relative accuracy is comparable to that of the GRM statics. The residual statics values show a general correlation with the refraction statics values, and they can be reduced in magnitude by using a lower average seismic velocity in the weathering. These results suggest that inaccurate average seismic velocities in the weathered layer may often be a source of short-wavelength statics, rather than any shortcomings with the inversion algorithms in determining averaged delay times from the traveltimes.

• The Journal of the Acoustical Society of Korea
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• v.43 no.2
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• pp.178-183
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• 2024

This study introduces an enhanced sound source localization technique, bolstered by a data-driven deep learning approach, to improve the precision and accuracy of direction of arrival estimation. Focused on refining Time Difference Of Arrival (TDOA) based sound source localization, the research hinges on accurately estimating TDOA from cross-correlation functions. Accurately estimating the TDOA still remains a limitation in this research field because the measured value from actual microphones are mixed with a lot of noise. Additionally, the digitization process of acoustic signals introduces quantization errors, associated with the sampling frequency of the measurement system, that limit the precision of TDOA estimation. A deep learning-based approach is designed to overcome these limitations in TDOA accuracy and precision. To validate the method, we conduct comprehensive evaluations using both two and three-microphone array configurations. Moreover, the feasibility and real-world applicability of the suggested method are further substantiated through experiments conducted in an anechoic chamber.

• Bulletin of the Korean Space Science Society
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• 2010.04a
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• pp.28.1-28.1
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• 2010

이 연구에서는 기존 선형 상대운동방정식에 차등중력, 주위성의 이심율, J2 섭동 등의 비선형항을 추가하여 보다 정확한 상대운동방정식을 만든 후 섭동이론을 적용하여 위성편대 연료최적화 재배치 문제에 대한 근사 해석해를 구하고자 한다. 먼저, 비선형 섭동항을 테일러 급수를 이용하여 2차항까지 전개한 후, 이를 기존 선형상대운동방정식에 추가하여 새로운 비선형 상대운동방정식을 만든다. 이 때 사용된 선형상대운동방정식은 힐스 방정식으로 주위성의 궤도가 일반적인 타원이고 위성 간 상대거리가 충분히 가깝다고 가정한다. 최적화 조건으로부터 상태벡터와 라그랑지 곱수로 이루어진 연립 미분방정식이 만들어 지는데, 이 식은 힐스 방정식에 기인한 선형부분과 2차 비선형항에 기인한 섭동부분으로 나뉜다. 이 때, 이 연립미분방정식의 해는 선형부분의 해와 섭동으로 인한 변화량의 합으로 근사할 수 있으며 그 변화량은 섭동이론을 적용하여 얻을 수 있다. 이와 같이 얻어진 해는 여러 섭동의 비선형항을 2차까지 포함한 상대운동방정식을 사용했기 때문에, 기존 선형상대운동방정식을 사용하여 구한 최적해 보다 더 정확한 결과를 얻을 것이라 예상한다.

• Proceedings of the KAIS Fall Conference
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• 2012.05b
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• pp.537-540
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• 2012

기존 2차 전지 내부저항 측정 또는 잔존 용량 측정 등의 2차전지의 수명을 예측 방법들이 있으나 이 방법은 여러 가지 사용 환경에 따른 측정 오류 발생으로 의해 잔존 수명 예측을 정확하게 판단하기는 어려운 실정이다. 따라서 본 논문은 2치전지의 전해액 비중을 이용한 수명 예측 알고리즘을 개발하고 LabVIEW프로그램을 활용한 2차 전지 상태 감시와 잔존 수명을 예측하는 프로그램을 제작하여, 2차 전지의 상태와 교체 시점에 대한 신뢰도를 높일 수 있는 방안을 제시하고자 한다.

• Journal of Korean Society for Geospatial Information Science
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• v.13 no.4 s.34
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• pp.67-73
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• 2005

The urbanization of Korea has been rapidly progressed since 1960, but satellite imagery have provided the information only after 1975. Recently released CORONA imagery is one of the few source of satellite image which can provide 1960's topographic information of the Korean Peninsular. It can be applied to change detection in various fields such as urban, forest, and environmental planning. In this research mosaic image of past Korean Peninsular using CORONA imagery in the 1960s were generated. A polynomial equation and a modified collinearity equation were applied for geo-referencing and a comparative analysis was conducted. In this research the 2nd polynomial equations were used for geo-referencing of CORONA imagery. After carrying out geo-referencing, mosaic image was generated using Erdas Imagine. It is assumed that this result image is very useful for various fields such as generation of thematic maps, urban planning, and change detection.

• Journal of Convergence for Information Technology
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• v.7 no.2
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• pp.53-58
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• 2017

This paper describes the design of a simulator for analyzing the accuracy of a correlative interferometer(CI) direction finder. CI direction finder is robust to noise, so it is often used in aircraft or ships where complex antenna installation is required, and the direction finding accuracy is very high. When the radio wave is incident at a specific azimuth angle, the phase difference calculated in a noiseless environment and the phase difference measured in a real environment with noise are fused to estimate the largest correlation coefficient as the azimuth angle of the radio wave. The simulator receives RF frequency, the number of antennas, the antenna coordinates, the transmission signal intensity, the bandwidth of the receiver, the gain and the payload effect, and calculates the direction finding accuracy of 0-360 degrees azimuth and 0-60 degree elevation with 0.5 degree. accuracy.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.1
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• pp.369-377
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• 2013

This paper deals with the state of charge(SOC) and life cycle evaluation algorithm for lead-acid battery, which is essential factor of the electric vehicle(EV) and the stabilization of renewable energy in the smart grid. In order to perform the effective operation of the lead-acid battery, SOC and life cycle evaluation algorithm is required. Specific gravity with the change of electrolyte temperature inside battery case should be obtained to evaluate the SOC of lead-acid battery, however it is difficult to measure the electrolyte temperature of sealed type lead-acid battery. To overcome this problem, this paper proposes the equation of thermal transmission to compensate internal temperature of the lead-acid battery. Also, it is difficult to exactly evaluate the life cycle of battery, depending on the operation conditions of lead-acid battery such as charging and discharging state, self discharging rate and environmental issue. In order to solve the problem, this paper presents the concept for gravity accumulation of charge and discharge cycle, which is the value converted at $20^{\circ}C$. By using the proposed algorithm, this paper propose the test device based on the Labview software. The simulation results show that it is a practical tool for the maintenance of lead-acid battery in the field of industry.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.4
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• pp.639-648
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• 1994

This paper presents a new block matching algorithm in estimation of motion information that is important technology in compressing interframe. In estimation of motion information, we find differential image using two successive frame image in order to find required real time processing and accurate moving vector, the binary image is made of edge and find more accurate moving vectors by application quadtree method to parts including many moving according to this activity. The computer simulation results show that increased PSNR and reduced computation time.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05a
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• pp.602-607
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• 1996

원자력 발전소의 효율증대 및 경제적인 측면에서 2차계통 구성부품의 보수 및 유지를 위해서는 발전소 2차계통 구성 기기의 성능저하로 인한 Heat Rate의 변화와 그에 따른 출력변화를 감시하는 것이 무엇보다 중요하다. 이를 위하여, 영광 3호기의 성능보증 시험시 사용한 방법을 이용하여 Heat Rate를 계산하는 프로그램을 개발하였으며, 이 프로그램을 이용하여 2차계통 주요 구성 기기의 성능저하에 따른 Heat Rate의 변화율 계산을 수행하였다. 이 프로그램의 계산결과와 영광 3호기 성능보증시험결과를 비교하여 이 프로그램이 Heat Rate를 정확히 계산할 수 있음과, Heat Rate의 변화율 계산의 타당성을 확인하였다. 또한, Heat Rate의 변화율을 이용한 2차계통 주요 구성 기기의 성능진단 시스템의 논리를 제시하였다.