• Korean Journal of Remote Sensing
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• v.18 no.2
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• pp.117-125
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• 2002

Multitemporal analysis with remotely sensed data is complicated by numerous intervening factors, including atmospheric attenuation and occurrence of clouds that obscure the relationship between ground and satellite observed spectral measurements. Using an adaptive reconstruction system, dynamic compositing approach was developed to recover missing/bad observations. The reconstruction method incorporates temporal variation in physical properties of targets and anisotropic spatial optical properties into image processing. The adaptive system performs the dynamic compositing by obtaining a composite image as a weighted sum of the observed value and the value predicted according to local temporal trend. The proposed system was applied to the sequence of NDVI images of AVHRR observed on the Korean Peninsula from 1999 year to 2000 year. The experiment shows that the reconstructed series can be used as an estimated series with complete data for the observations including bad/missing values. Additionally, the gradient image, which represents the amount of temporal change at the corresponding time, was generated by the proposed system. It shows more clearly temporal variation than the data image series.

• Proceedings of the Materials Research Society of Korea Conference
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• 1994.11a
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• pp.76-77
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• 1994

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.130.2-130.2
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• 2005

• Journal of the Society of Naval Architects of Korea
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• v.38 no.4
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• pp.48-55
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• 2001

In this paper, sensitivity analysis for the coupled axial and torsional undamped free vibration of ship propulsion shafting is proposed. The purpose of this study is to effectively and optimally design the resonance frequencies of propulsion shafting affecting barred speed range of main engine by modifying the diameters of intermediate and propeller shafts. The presented method is validated by the sensitivity analysis for the natural frequencies of propulsion shafting of two real large merchant ships. In addition, the changes of natural frequency and resonance main engine speed are discussed in case that the diameter is varied within the range regulated by the rule of shipping register.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.271-271
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• 2007

LTCC 소재는 glass/ceramic composite로 구성된다. LTCC 소재에 embedding 되는 고유전율 소재 또한 이와 같은 소재설계를 통하여 무수축 접합이 가능할 것으로 판단된다. 그러나 이에 대한 연구결과가 보고된바 없고 몇몇 $Al_2O_3$의 infiltration에 대한 무수축 소성 관련 선행 연구를 바탕으로 고유전율 소재인 $BaTiO_3$의 무수축 소성이 연구되는 것이 필요한 시점이다. 따라서 본 연구는 저온에서의 glass infiltration에 의한 무수축 $BaTiO_3$ layer의 저온소성특성 및 유전특성을 평가하였다. 실험결과 $785^{\circ}C$에서 glass의 충분한 침투가 확인되며 결정구조에서는 glass/$BaTiO_3$ composite이 형성되었다. 무수축 접합 layer의 소성조건과 glass 두께 변화에 따른 유전특성 및 layer의 결정구조를 비교평가 하였다.

• Proceedings of KOSOMES biannual meeting
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• 2001.05a
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• pp.53-77
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• 2001

선박의 항행안전의 문제가 중요시됨에 따라 선박조종시뮬레이터에 의한 안전성 검토의 필요성이 크게 인식되고 있다. 또한 조종성능을 향상시킬 목적으로 다양한 선종이 출현하고 있고, 이에 따라 선박조종시뮬레이터의 개발에 있어서 선박의 데이터베이스는 필수적이라고 할 수 있다. 따라서 선종에 따른 수학모델을 각각 선박조종시뮬레이터에 적용시킴으로써 다양성이라는 가상현실의 잇점을 한층 부각시킬 수 있다. 본 연구에서는 우수한 추진성능을 목적으로 한 2축2타선박을 대상으로 조종운동 수학모델을 정식화하였다. 구체적으로 항만내에서의 저속시 조종운동을 구현할 수 있는 수학모델에 대해서 검토하였으며, 선체·프로펠러·타의 상호간섭에 대해서도 고려하였다. 또한, 수치시뮬레이션을 수행함으로써 2축2타선박의 기본적인 조종성능을 확인할 수 있었다.

• Journal of the Korean Geosynthetics Society
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• v.21 no.2
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• pp.39-48
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• 2022

Unlike the horizontal strut, the corner strut causes bending behavior by the installation angle when soil pressure occurs, so there is a limit to its application as a elasto plastic method that requires only the axial stiffness of struts. Therefore, this study attempted to approach a method of modifying axial stiffness data to present an analysis method for corner struts in elasto plastic method, and linear elasticity analysis was used for this. And, through Linear elasticity analysis, axial stiffness data for corner struts installed at the actual site were calculated. The behavior of the retainingwall was confirmed by applying the calculated axial stiffness data of corner struts to elasto plastic method, and its applicability was evaluated by comparing it with the measurement results and the finite element analysis results. As a result of the study, when the axial stiffness data of the corner struts was applied using Linear elasticity analysis(Case 1, Case 3), the axial stiffness data decreased to 9% to 17% compared to the general method of applying the axial stiffness of the struts(Case 2, Case 4), and the displacement of the retainingwall increased to 25.33% to 64.42%. Comparing this result with the measurement results, when Linear elasticity analysis was used(Case 1, Case 3), the behavior of the retainingwall during the elasto plastic method was better shown.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.5
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• pp.933-940
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• 2022

In this paper, the algorithm was developed to recognize hand 3D position through 2D image sensor and implemented a system to remotely control the 6 d.o.f. robot arm by using it. The system consists of a camera that acquires hand position in 2D, a computer that controls robot arm that performs movement by hand position recognition. The image sensor recognizes the specific color of the glove putting on operator's hand and outputs the recognized range and position by including the color area of the glove as a shape of rectangle. We recognize the velocity vector of end effector and control the robot arm by the output data of the position and size of the detected rectangle. Through the several experiments using developed 6 axis robot, it was confirmed that the 6 d.o.f. robot arm remote control was successfully performed.

• Journal of Practical Engineering Education
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• v.13 no.2
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• pp.327-332
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• 2021

Materials used for education include SM20C, Al6061, and acrylic. SM20C materials are used a lot in certification tests and functional competitions as carbon steel, but they are also used in industrial sites. Al6061 is said to be a material that produces a lot of tools because it has lower hardness than carbon steel and is highly flexible. When practical guidance is given to students using acrylic materials, it is a material that causes vibration and tool damage due to excessive cutting. In this process, we examine how impact on the 5-axis equipment 2NC head can affect precision control. The weakest part of a five-axis equipment is the head that controls the AC axis. In the event of precision and cumulative tolerances in this area, the precision of all products is reduced. Thus, a key part of the 2NC head, the spindle housing was carried out using Al7075 T6 (U.S. Alcoasa) material and the entire body using FCD450 (spherical graphite cast iron). In the vibration and cutting process acting on these two materials, the analysis was carried out to determine the value of applying the force as a finite element analysis under extreme conditions. We hope that using these analytical data will help students see and understand the structure of 5-axis machining rather than 5-axis cutting.

• The Korean Journal of Nuclear Medicine
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• v.39 no.1
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• pp.49-56
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• 2005

Purpose: Dedicated animal PET is useful equipment for the study of new PET tracer. recently, microPET R4 was installed in the Korea institute of radiology and medical science. In this study, we measured the characteristics of scanner. Materials and methods: Resolution was measured using a line source (F-18:65 ${\mu}Ci$, inner diameter: 0.5 mm). The line source was put in the axial direction and was moved from the center of field of view to outside with 1 mm interval. PET images were reconstructed using a filtered back-protection and ordered subset expectation maximization. line source (16.5 ${\mu}Ci$, 78 mm) was put on the tenter of axial direction to measure the sensitivity when the deadtime was under 1%. Images were acquired during 4 minutes respectively from center to 39 mm outward. Delayed count was subtracted from total count and then decay was corrected for the calculation of sensitivity. Noise equivalent count ratio and scatter fraction were calculated using cylindrical phantom. Results: Spatial resolution of reconstructed image using filtered back-projection was 1.86 mm(radial), 1.95 mm(tangential), 1.95 mm(axial) in the tenter of field of view, and 2.54 mm, 2.8 mm, 1.61 mm in 2 cm away from the center respectively. Sensitivity was 2.36% at the center of transaxial field of view. Scatter fraction was 20%. Maximal noise equivalent count ratio was 66.4 kcps at 242 kBq/mL. Small animal images were acquired for confirmation of performance. Conclusion: Performance characteristics of microPET R4 were similar with reported value. So this will be a useful tool for small animal imaging.