• ETRI Journal
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• 제43권4호
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• pp.603-616
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• 2021

Over the last few years, autonomous vehicles have progressed very rapidly. The odometry technique that estimates displacement from consecutive sensor inputs is an essential technique for autonomous driving. In this article, we propose a fast, robust, and accurate odometry technique. The proposed technique is light detection and ranging (LiDAR)-based direct odometry, which uses a spherical range image (SRI) that projects a three-dimensional point cloud onto a two-dimensional spherical image plane. Direct odometry is developed in a vision-based method, and a fast execution speed can be expected. However, applying LiDAR data is difficult because of the sparsity. To solve this problem, we propose an SRI generation method and mathematical analysis, two key point sampling methods using SRI to increase precision and robustness, and a fast optimization method. The proposed technique was tested with the KITTI dataset and real environments. Evaluation results yielded a translation error of 0.69%, a rotation error of 0.0031°/m in the KITTI training dataset, and an execution time of 17 ms. The results demonstrated high precision comparable with state-of-the-art and remarkably higher speed than conventional techniques.

• 한국생산제조학회지
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• 제9권6호
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• pp.133-139
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• 2000

Vibrational characteristics of the vehicle structure are mainly influenced by the shape of the pillar cross section. In this paper a vehicle structural optimization technique has been developed to investigate a lightweight vehicle structure subject to constraints on natural frequencies in a simple beam-and-shell model. In this technique, the optimization procedures involve two stages. In the first stage, the section procedures involve tow stages. In the first stage, the section properties of beam elements of the vehicle structure has been optimized to have minimum weight while satisfying the constraints of natural frequencies. And, in the second stage, the shape of the cross section of the elements of the structure has been determined.

• Clinical Endoscopy
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• 제57권2호
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• pp.280-281
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• 2024

• ETRI Journal
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• 제45권4호
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• pp.650-665
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• 2023

A novel smart metering technique capable of anomaly detection was proposed for real-time home power management system. Smart meter data generated in real-time were obtained from 900 households of single apartments. To detect outliers and missing values in smart meter data, a deep learning model, the autoencoder, consisting of a graph convolutional network and bidirectional long short-term memory network, was applied to the smart metering technique. Power management based on the smart metering technique was executed by multi-objective optimization in the presence of a battery storage system and an electric vehicle. The results of the power management employing the proposed smart metering technique indicate a reduction in electricity cost and amount of power supplied by the grid compared to the results of power management without anomaly detection.

• 헤리티지:역사와 과학
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• 제50권3호
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• pp.4-29
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• 2017

본 글은 중국 자료의 편년을 통해 한국식동검문화의 개시 연대를 파악하는 데 목적을 두었다. 여기에서는 한반도의 한국식동검과 중국의 동주식동검에 동일한 구분마연 기술이 존재하는 점을 주목하였다. A1식 구분마연 기술이 관찰되는 동주식동검은 '1958년 산동성 안구시 수습품'으로 전해져 명확한 출토양상을 파악할 수 없다. 때문에 비교자료인 제남 좌가와 1호묘 출토 동주식동검과 공반품을 제시하였다. 공반품은 청동무기, 청동예기 등이 출토되어 유적의 연대는 춘추-전국시대 과도기~전국시대 전기로 편년된다. 출토된 양 동검은 형식학적 유사성 및 편년적 위치를 동일하게 설정할 수 있게 된다. 따라서 한반도 제유적 출토의 한국식동검은 중국 출토 A1식 구분마연 기술의 동주식동검과 일정기간 병행되어 성립되는 것으로 볼 수 있다. 또한 A2식 구분마연 기술이 확인되는 산서성 만영묘전 61M1호묘의 연대는 전국시대 전기~중기로 편년되며 A1식 구분마연 기술과 연동되어 전개되는 것으로 확인된다. 결국 중국 자료의 편년을 통해 볼 때 한국식동검문화의 개시 연대는 춘추-전국시대 과도기~전국시대 전기로 이해되고, 기원전 5~4세기로 편년된다. 이와 같은 연대는 기원전 6~5세기로 편년되는 심양 정가와자 6512호묘에 후행되며 요령식동검문화와 한국식동검문화는 자연스럽게 연동되는 것을 알 수 있다. 나아가 A1식 구분마연 기술은 한반도 서남부지역과 중국 산동반도, A2식 구분마연 기술은 한반도 남부지역과 중국 산서지역 및 일본 북부구주지역에 분포한다. 구분마연 기술의 무기형청동기를 통해 볼 때 중국 산동반도(중원지역) ${\leftrightarrows}$ 한반도 서남부지역(서북부지역) ${\leftrightarrows}$ 일본 북부구주지역은 하나의 교통로(전파 경로)로 설정된다. 이는 한반도를 중심으로 구분마연 기술이 출현하고, 지역적 확산이 전개되는 바이다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 A
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• pp.534-536
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• 2003

It is important to classily fault types and discriminate fault section by any detecting technique for combined transmission lines. This paper proposes the technique to classify the fault types and fault section using neuro-fuzzy systems. Neuro-fuzzy systems are composed of two parts to perform different works. First, neuro-fuzzy system for fault type classification is performed with approximation coefficient of currents obtained by wavelet transform. Another neuro-fuzzy system discriminates the fault section between overhead and underground with detail coefficients of voltage and current. In this paper, neuro-fuzzy system shows the excellent results for classification of fault types and discrimination of fault section.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 추계학술대회 논문집 전력기술부문
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• pp.412-415
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• 2003

It is important to classily fault types, discriminate fault section and calculate the fault location by any detecting technique for combined transmission lines. This paper proposes the technique to classily the fault types and fault section using neuro-fuzzy systems. Neuro-fuzzy systems are composed of three parts to perform different works. First, neuro-fuzzy system for fault type classification is performed with approximation coefficient of currents obtained by wavelet transform. The second neuro-fuzzy system discriminates the fault section between overhead and underground with detail coefficients of voltage and current. The last neuro-fuzzy system calculates the fault location with impedance in this paper, neuro-furry system shows the excellent results for classification of fault types and discrimination of fault section.

• Structural Engineering and Mechanics
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• 제73권1호
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• pp.75-82
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• 2020

In this study, the problem of torsion of bars with open cross section surrounded by corrugated boundaries is analyzed. An approximate analytical solution is given using perturbation technique. First, the stress analysis for circular open cross-section for arbitrary opening angle is formulated and the problem is analytically solved. Second, the open cross-section with corrugated cross section is analyzed using perturbation method. First order contributions to the stresses and the torques have been added. The results have been exemplified and compared by considering special examples.

• 대한토목학회논문집
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• 제30권6A호
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• pp.581-590
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• 2010

본 연구는 곡선배치 텐던을 갖는 변단면 PSC의 전단을 고려한 층상화 단면해석기술을 소개한다. 곡선배치 텐던의 전단평형을 고려하기 위해서, 각 층상화 단면에서 전단응력을 직접 산출 할 수 있는 새로운 방법과 각 층상화 단면의 변형률 산정시 기존의 반복법보다 수렴 속도가 효율적인 시스템인식기법을 적용하였다. 제안기법은 변단면 PSC보의 정재하실험 결과와 비교분석 되었으며, 추정된 구조응답과 실험결과가 잘 일치하고 있다. 또한, 동일 조건에서 변단면 PSC보와 균등단면 PSC보의 거동특성이 비교분석되었다. 분석결과을 살펴보면, 휨강성은 변단면과 균등단면이 동일하지만, 전단강성은 변단면이 균등단면 보다 크다. 더욱이, 변단면의 자중이 균등단면보다 크지만 변단면의 최대처짐이 균등단면 보다 작다.

• The Journal of the Acoustical Society of Korea
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• 제21권2E호
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• pp.63-70
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• 2002

In this paper, an optimization technique for thin walled beams of vehicle body structure is proposed. Stiffness of thin walled beam structure is characterized by the thickness and typical section shape of the beam structure. Approximate functions for the section properties such as area, area moment of inertia, and torsional constant are derived by using the response surface method. The approximate functions can be used for the optimal design of the vehicle body that consists of complicated thin walled beams. A passenger car body structure is optimized to demonstrate the proposed technique.