• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2008년도 한국우주과학회보 제17권2호
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• pp.25.3-26
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• 2008

The direct way to the moon is to start from the parking orbit by using impulsive thruster In previous domestic research, the direct way has been studied by using a single impulsive shot. However, when a single impulsive shot occurs to go into a Translunar orbit, gravity losses occur because thruster is not impulsive shot but the finite burns and it causes the gravity losses. To make up for the weak point of a single impulsive shot, this paper divides TLI (Trans Lunar Injection) into several small burns. Therefore, departure loop trajectory and the Translunar trajectory. This method is useful not only to reduce the gravity losses but also to check the condition of satellite. By using this method, this paper demostrates the optimized trajectory from Earth parking orbit to lunar mission orbit which minimizes the fuel, and the SNOPT (Sparse Nonlinear OPTimizer software) is used to find optimal solution. Also, this paper provides lunar mission profile which includes the mission schedule when TLI, LOI (Lunar Orbit Insertion) maneuvers occur, a mount of fuel when thruster is used and other mission parameters.

• 분석과학
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• 제8권4호
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• pp.779-786
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• 1995

Environmental and industrial aerosols can be analyzed on-line by laser plasma spectroscopy. The main problem in direct (no preparation or presorting) aerosol analysis is the extensive spectral fluctuations. A method to partially solve this problem is proposed. It is based on single shot measurements and application of a special rejection algorithm. The major factors that influence the spectral variations are discussed, in relation to the correction possibility by a rejection program. The method works well when average intensity of the single spectra is relatively high, as compared to detector's saturation limit. If intensities are too low, the accumulation of readout noise is critical, and no improvement is expected.

• 한국정보과학회논문지:소프트웨어및응용
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• 제29권1_2호
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• pp.114-125
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• 2002

본 논문에서는 MPEG 비디오 데이터의 컷(cut)과 디졸브(dissolve)를 검출하여 샷(shot) 단위로 분할하고 각 샷의 카메라 동작 또는 객체 움직임의 형태를 분류하는 방법을 제안하고자 한다. 정확한 샷의 위치와 카메라, 객체의 세분화된 동작을 구별하기 위한 전단계의 연구에서[1] 우선 MPEG 데이터의 I(Intra) 프레임의 DC(Direct Current) 계수를 분석하여 픽처 그룹을 Shot(장면이 바뀐 경우), Move(카메라 동작 또는 객체가 움직인 경우), Static(영상의 변화가 거의 없는 경우)으로 세분화하여 분류하였다. 이 과정에서 2단계 구조의 신경망을 구성하고 여러 종류의 특징을 서로 다른 해상도에서 추출하여 결합시키는 방법을 제안하였다. 다음 단계로 Shot 또는 Move로 분류된 픽처 그룹의 P(Predicted), B(Bi-directional) 프레임을 선별적, 계층적으로 탐색하여 컷의 정확한 발생 위치와 카메라 동작 또는 객체 움직임의 종류를 결정하는 방법을 제안한다. P, B 프레임의 매크로 블록의 종류별 분포를 통계적으로 이용하여 컷의 발생 위치를 검출하여, P, B 프레임의 매크로 블록 종류와 움직임 벡터를 동시에 사용하는 신경망을 구성하여 디졸브, 카메라 동작, 객체 움직임의 종류를 검출한다. 본 논문에서 제안하는 방법은 MPEG 데이터의 압축을 풀지 않은 상태에서 I 프레임의 DC 계수만을 사용하여 픽처 그룹을 분류하며, 분류된 픽처 그룹 내에서 일부의 P, B 프레임만을 계층적으로 선택하여 탐색함으로서 처리 시간을 감소시키고자 하였다. 세 종류의 서로 다른 비디오 데이터를 사용한 실험에서 93.9-100.0%로 픽처 그룹을, 96.1-100.0%로 컷을 검출하였다. 또한 두 종류의 비디오 데이터를 사용한 실험에서 90.13% 및 89.28%의 정확성으로 카메라 동작 또는 객체 움직임을 분류하였다.

• 한국산학기술학회논문지
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• 제13권11호
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• pp.5148-5154
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• 2012

본 논문은 포환던지기 여자 기록보유자의 실제 경기에서 포환과 신체 무게중심의 운동학적 특성을 분석하는데 있다. 이를 위해 2대의 비디오카메라를 이용하여 촬영 한 후, 3차원 영상분석을 위해 DLT 방법을 이용하였으며, 자료 분석을 위해 Kwon3D 프로그램을 이용하였다. 그 결과는 다음과 같다. 첫째, 포환의 투사 속도와 투사 높이는 각각 13.73 m/s, 198.6 cm(신장비 119%)로 선행연구들과 비교했을 때, 최적의 수행을 한 것으로 판단되나 투사 각도는 $34^{\circ}$로 다소 작게 나타났다. 둘째, 신체 무게중심의 이동은 글라이드 구간에서 투사 방향으로의 이동이 필요하며, 딜리버리 구간에서 신체 무게중심의 상하 이동을 제어해야 한다. 셋째, 릴리즈 순간 신체 무게중심의 좌우방향과 상하방향의 흔들림 없이 정확한 타이밍에 포환이 투사되어야 한다.

• 한국태양에너지학회 논문집
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• 제22권4호
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• pp.35-43
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• 2002

This research makes that quantitative radiation property of an actual town ward is obtained in quest of the parameter with regard to a radiation heat transfer property and set up several town ward models that reproduced a solid form of a city along the attribute of the city. A regular trend possibility that is able to evaluate a radiation characteristics of a town ward quantitatively from a town ward guideline and confirmation that is produced about each parameter as a result of a numerical value simulation it obtained. This research shot a coefficient of Gebhart's emission absorption. sky radiation absorption rate direct solar radiation absorption rate the parameter with regard to a radiation heat transfer characteristics of a town ward in each town ward model and a volume rate of a town ward advances case study under regular such condition and shot the absorption rate, direct and others days and calculated an absorption rate and checked about the relation between a town ward and each radiation heat transfer property of a city.

• Smart Structures and Systems
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• 제28권6호
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• pp.811-825
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• 2021

High-voltage isolating switches play a paramount role in ensuring the safety of power supply systems. However, their exposure to outdoor environmental conditions may cause serious physical defects, which may result in great risk to power supply systems and society. Image processing-based methods have been used for anomaly detection. However, their accuracy is affected by numerous uncertainties due to manually extracted features, which makes the anomaly detection of isolating switches still challenging. In this paper, a vision-based anomaly detection method for isolating switches, which uses the rotational angle of the switch system for more accurate and direct anomaly detection with the help of deep learning (DL) and image processing methods (Single Shot Multibox Detector (SSD), improved frame differencing method, and Hough transform), is proposed. The SSD is a deep learning method for object classification and localization. In addition, an improved frame differencing method is introduced for better feature extraction and a hough transform method is adopted for rotational angle calculation. A number of experiments are conducted for anomaly detection of single and multiple switches using video frames. The results of the experiments demonstrate that the SSD outperforms the You-Only-Look-Once network. The effectiveness and robustness of the proposed method have been proven under various conditions, such as different illumination and camera locations using 96 videos from the experiments.

• 대한의용생체공학회:의공학회지
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• 제26권4호
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• pp.251-255
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• 2005

When the extracorporeal shock wave lithotriptor is operated, sounds can be heard. Then that might be a question about the location where the sounds come from. For the purpose of investigating the fact, we identify the location of the sounds radiated using one hydrophone. In order to carry out the experiment, it is needed to obtain direct waves from objects. Therefore, we present an experimental method to reduce reflected waves for obtaining direct waves only. The experimental results show the amplitude of waves can be attenuated about 28dB due to a silicon rubber plate of 8.5mm attached at the bottom. This is a quantified result that can expect to obtain the direct waves using the proposed method. Then, we carried out the experiment for the sound source location. From the experimental results, we can undoubtedly present a fact that the sounds are radiated from the objects to be shot due to shock waves.

• 한국산학기술학회논문지
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• 제8권6호
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• pp.1449-1457
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• 2007

파노라마 영상은 여러 장의 겹쳐지는 영상을 하나의 큰 영상으로 병합하여 만들어진다. 그 방법에는 크게 특징 기반 방법과 직접 방법의 두 종류가 있으며, 특징 기반 방법은 직접 방법에 비해 처리 속도가 빠른 장점이 있다. 그러나 모바일 단말기와 같은 처리속도가 느린 환경에서 구현하기에는 어려움이 있다. 본 논문에서는 고속 파노라마 영상 생성 방법을 제안하였다 이 방법은 촬영 장면 가이더를 적용함으로써 정합 파라미터의 개수를 줄여 정합속도를 크게 향상시켰다. 또한, 적은 수의 파라미터 사용에 따른 정합 오차를 줄이기 위해 국소 정합법을 추가로 적용하였다. 실험에서, $320{\times}240$ 크기의 24비트 칼라 영상에 대해 약 0.078초의 처리속도로 기존의 특징 기반 방법보다 처리속도 면에서 약 17배의 처리 속도 개선을 보였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 학술회의 논문집 정보 및 제어부문 B
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• pp.735-739
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• 2003

This paper presents a direct seek control algorithm for swing-arm type dual stage servo system that consists of a coarse actuator and a fine actuator. The proposed scheme is to design a control system that attenuates the effect of dynamic coupling between the two actuators so that the seek operation can be performed in a single-shot with stability. In an optical drive system with dual stage servo mechanism, the effect of dynamic coupling between the two actuators needs to be handled during the coarse seek operation due to its inherent structure. In an extreme case, the two actuators can collide each other, which leads to critical degradation of the seek performance. To handle this problem, our proposed control scheme is to generate the drive signals such that the two actuators behave as if they are a single fixed body. To this end, a feedforward controller and two feedback controllers are designed that enable the current drive system perform wide range of track seek. Simulation results are provided to show the validity and feasibility of our proposed algorithm.

• Corrosion Science and Technology
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• 제12권2호
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• pp.93-101
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• 2013

The object of this work is to establish an electrochemical noise(EN) measurement technique combined with a direct current potential drop(DCPD) method for monitoring of localized corrosion cracking of nickel-based alloy, and to analyze its mechanism. The electrochemical current and potential noises were measured under various conditions of applied stress to a compact tension specimen in a simulated primary water chemistry of a pressurized water reactor. The amplitude and frequency of the EN signals were evaluated in both time and frequency domains based on a shot noise theory, and then quantitatively analyzed using statistical Weibull distribution function. From the spectral analysis, the effect of the current application in DCPD was found to be effectively excluded from the EN signals generated from the localized corrosion cracking. With the aid of a microstructural analysis, the relationship between EN signals and the localized corrosion cracking mechanism was investigated by comparing the shape parameter of Weibull distribution of a mean time-to-failure.