• 한국해양공학회지
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• 제28권5호
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• pp.440-451
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• 2014

A multi-static SONAR system consists of the transmitters and receivers separately in space. The active target echoes are received along the transmitter-target-receiver path and depend on the shape and aspect angle of the submerged objects at each receiver. Thus, the target echo algorithm used with a mono-static system, in which the transmitter and receiver are located at the same position, has limits in simulating the target echoes for a multi-static SONAR system. In this paper, a target echo modeling procedure for a 3D submerged object in space is described based on the Kirchhoff approximation, and the SONAR system is extended to a multi-static SONAR system. The scattered field from external structures is calculated on the visible surfaces, which is determined based on the locations of the transmitter and receiver. A series of experiments in an acoustic water tank was conducted to measure the target echoes from scaled targets with a single transmitter and 16 receivers. Finally, the numerical results were compared with experimental results and shown to be useful for simulating the target echoes/target strength in a multi-static SONAR system.

• 한국정보과학회논문지:정보통신
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• 제30권4호
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• pp.504-512
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• 2003

본 논문에서는 디졸브 모델링 오차를 이용한 디졸브 검출 방법을 제안한다. 디졸브 모델링 오차는 디졸브 구간을 구성하는 두 장면 사이에 상관성이 없는 이상적인 디졸브 모델과 상관성이 존재하는 실제 디졸브 사이의 차이로 정의된다. 제안된 방법은 두 단계로 구성된다. 첫 번째 단계에서는 분산 곡선에서 나타나는 디졸브 구간의 특성인 아래로 볼록한 포물선을 검출하여 디졸브 후보 구간을 설정한다. 두 번째 단계에서는 선택된 후보 구간 자각에 대해 디졸브 모델링 오차를 정의하고 모델링 오차가 기준치와 비교한다. 기준치는 목표 모델링 오차로 각 후보 구간의 분산과 사용자에 의해 주어지는 목표 상관성에 대한 함수로 표현됨으로 제안된 기준치, 목표 모델링 오차는 각 후보 구간의 분산 변화에 적응적이다. 제안한 디졸브 검출 방법은 디졸브 구간을 구성하는 두 장면의 상관성을 고려하므로, 의미론적 디졸브 검출 방법이 될 수 있다. 제안된 방법을 다양한 동영상에 적용하여 성능을 평가하였다. 실험 결과 제안한 방법이 다양한 분산의 변화에도 불구하고 기존의 방법보다 정확하고 신뢰성 높은 디졸브 검출 결과를 나타내었다.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제12권3호
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• pp.238-244
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• 2012

A modeling of vision based robot formation control system using fuzzy logic controller and extended Kalman filter is presented in this paper. The main problems affecting formation controls using fuzzy logic controller and vision based robots are: a robot's position in a formation need to be maintained, how to develop the membership function in order to obtain the optimal fuzzy system control that has the ability to do the formation control and the noise coming from camera process changes the position of references view. In order to handle these problems, we propose a fuzzy logic controller system equipped with a dynamic output membership function that controls the speed of the robot wheels to handle the maintenance position in formation. The output membership function changes over time based on changes in input at time t-1 to t. The noises appearing in image processing change the virtual target point positions are handled by Extended Kalman filter. The virtual target positions are established in order to define the formations. The virtual target point positions can be changed at any time in accordance with the desired formation. These algorithms have been validated through simulation. The simulations confirm that the follower robots reach their target point in a short time and are able to maintain their position in the formation although the noises change the target point positions.

• 한국군사과학기술학회지
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• 제22권4호
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• pp.475-483
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• 2019

Although radar target signatures(RTS), such as range profiles have played an important role for target recognition in the X-band radar, they would be less effective when a target is designed to have low radar cross section(RCS). Recently, a number of research groups have conducted the studies on the RTS in the VHF-band where such targets can be better detected than in the X-band. However, there is a lack of work carried out on the mathematical description of the VHF-band RTS. In this paper, chirplet decomposition is employed for modeling of the VHF-band RTS and its performance is compared with that of existing scattering center model generally used for the X-band. In addition, the discriminative signal analysis is performed by chirplet parameterization of range profiles from in an ISAR image. Because the chirplet decomposition takes long computation time, its fast form is further proposed for enhanced practicality.

• 농업과학연구
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• 제37권2호
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• pp.245-248
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• 2010

This study was conducted to investigate effect of changes in target fat and protein contents in milk on feed cost using a simulation modeling approach based on the 2001 dairy NRC. Two simulations were done; simulation I had a limitation (up to 20%), but simulation II had no limitation for the use of cottonseed hull in a diet. Using commonly used feed ingredients in Korea, we formulated least cost diets that meet nutrient requirement of a lactating dairy cow producing 36 kg of milk with combinations of 0.1% decrease or 0.1% increase in target milk fat or protein, respectively, from the national average milk fat (4.0%) and milk protein (3.1%). The contents of alfalfa and corn in a least-cost diet were decreased and those of tall fescue, whole cottonseed and rapeseed meal were increased with decreasing fat and/or increasing protein in milk. Scenarios that decreased target milk fat percentage from 4.0% to 3.9% reduced feed cost by 2 won per kg. Due to decrease in feed intake, daily feed cost was even more reduced (136 won per head) by decreasing target milk fat percentage. Increase in target milk protein percentage from 3.1% to 3.2% reduced feed cost by 6 won per kg. Among scenarios simulated, the least feed cost was obtained in scenario aimed for 3.9% fat and 3.2% of protein in milk. We conclude that a feeding practice for increasing milk protein percentage does not directly increase feed cost. In addition, feeding practices that increase protein content in milk is expected to improve economic life-span and reproductive performance of dairy cows.

• 한국CDE학회논문집
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• 제20권3호
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• pp.238-245
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• 2015

Vulnerability assessment is a process to calculate the damage degree of a combat vehicle when the combat vehicle is attacked by an enemy. When the vehicle is hit, it is necessary to analyze the shot line to calculate which components are damaged and judge whether the armor of the vehicle is penetrated by enemy's warhead. To analyze the shot line efficiently, this paper presents the target modeling and the shot line analysis system to assess vulnerability of the ground combat vehicle. This system is easily able to do several functions: 1) the program reads STL files converted from CAD model which is designed by commercial CAD software. 2) It calculates the intersection between triangle of STL mesh and the shot line, and check if the components of the model are penetrated. 3) This program can visualize the results using OpenGL. The vulnerability assessment using the shot line analysis can be used to model the armor of the combat vehicle and arrange the inner components effectively in the early stage of development of the combat vehicle.

• Current Optics and Photonics
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• 제8권2호
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• pp.138-150
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• 2024

This study is essential for advancing our knowledge about the interaction between long-range high-power lasers and energetic materials, with a particular emphasis on understanding the response of a 155-mm shell under various surface irradiations, taking into account external factors such as atmospheric disturbances. The analysis addresses known limitations in understanding the use of non-realistic targets and the negligence of ambient conditions. The model employs the three-dimensional level-set method, computer-aided design (CAD)-based target design, and a message-passing interface (MPI) parallelization scheme that enables rapid calculations of the complex chemical reactions of the irradiated high explosives. Important outcomes from interaction modeling include the accurate prediction of the initiation time of ignition, transient pressure, and temperature responses with the location of the initial hot spot within the shell, and the relative magnitude of noise with and without the presence of physical ambient disturbances. The initiation time of combustion was increased by approximately a factor of two with atmospheric disturbance considered, while slower heating of the target resulted in an average temperature rise of approximately 650 K and average pressure increase of approximately 1 GPa compared to the no ambient disturbance condition. The results provide an understanding of the interaction between the high-power laser and energetic target at a long distance in an atmospheric condition.

• 대한음성학회지:말소리
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• 제67호
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• pp.167-180
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• 2008

This paper describes a novel spectral envelope conversion method based on Gaussian mixture model (GMM). The core of this paper is rearranging source feature vectors in input space to the transformed feature vectors in feature space for the better modeling of GMM of source and target features. The quality of statistical modeling is dependent on the distribution and the dimension of data. The proposed method transforms both of the distribution and dimension of data and gives us the chance to model the same data with different configuration. Because the converted feature vectors should be on the input space, only source feature vectors are rearranged in the feature space and target feature vectors remain unchanged for the joint pdf of source and target features using KPCA. The experimental result shows that the proposed method outperforms the conventional GMM-based conversion method in various training environment.

• 한국빅데이터학회지
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• 제7권1호
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• pp.99-111
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• 2022

불확실성과 복잡성이 존재하는 제조시스템의 생산성 분석과 의사결정을 위하여 시뮬레이션 기법이 활용될 수 있다. 이러한 시스템의 시뮬레이션을 위해 대상의 특성을 반영하는 입력 모델링 과정이 필요하다. 하지만 건설기계 조립라인과 같은 수작업 중심과 긴 리드타임을 가지는 복잡한 환경에서는 시뮬레이션에 활용할 데이터의 수집이 제한된다. 본 연구는 입력 데이터의 수집이 어려운 환경에서 동영상 데이터를 이용한 시뮬레이션 입력 모델링 절차를 제안한다. 동영상 데이터 기반 작업분석을 통해 측정시간을 정미시간과 표준시간으로 산정하고, 시뮬레이션의 입력 분포로 활용할 수 있다. 제안하는 절차로 산정된 확률분포를 시뮬레이션에 이용하여 대상 시스템의 주요 생산성 지표를 분석하였다. 본 연구에서 제안하는 절차는 데이터가 적은 상황에서 시뮬레이션을 활용한 생산성 분석으로 의사결정 보조에 도움을 줄 것으로 기대된다.

• 통합자연과학논문집
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• 제7권4호
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• pp.234-240
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• 2014

C-C chemokine receptor type 4 (CCR4) is a chemokine receptor with seven transmembrane helices and it belongs to the GPCR family. It plays an important role in asthma, lung disease, atopic dermatitis, allergic bronchopulmonary aspergillosis, cancer, inflammatory bowel disease, the mosquito-borne tropical diseases, such as dengue fever and allergic rhinitis. Because of its role in wide spectrum of disease processes, CCR4 is considered to be an important drug target. Three dimensional structure of the protein is essential to determine the functions. In the present study homology modeling of human CCR4 was performed based on crystal structure of CCR5 chemokine receptor. The generated models were validated using various parameters. Among the generated homology models the best one is selected based on validation result. The model can be used for performing further docking studies to identifying the critical interacting residues.