• 한국정밀공학회지
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• 제20권12호
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• pp.73-79
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• 2003

Recently, the tole-robot operations to an unstructured environment have been widely researched. The human's interaction with the tole-robot system can be used to improve robot operation and performance for an unknown environment. The exact modeling based on real environment is fundamental and important process for this interaction. In this paper, we propose an extrinsic parameter calibration and data augmentation method that only uses a circular jig in the hand-eye laser virtual environment. Compared to other methods, easier estimation and overlay can be done by this algorithm. Experimental results using synthetic graphic demonstrate the usefulness of the proposed algorithm.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 I
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• pp.609-612
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• 2003

For combating multipath fading in wireless radio environment, diversity schemes is useful. In this paper, for performance improvement of polarization diversity system, we analyzed a two-branch polarization diversity at the receiving end of a mobile link when the transmitter emits a circularly polarized wave. And In order to calculate the correlation coefficient considering the XPD(cross polarization discrimination) between the received signals for the two diversity branches, a simple theoretical model of circular polarization diversity is adopted and calculate correlation coefficient. From the analysis results, it is seen that the correlation coefficient of circular polarization diversity evaluated by the XPD is less than that of vertical polarization diversity. And also, we designed and fabricated circular polarization diversity system with microstrip antenna. we analyzed data measured in indoor NLOS environment using fabricated circular polarization diversity system. From the measurement results, it is clearly seen that the diversity effect of circular polarization diversity system is higher 3dB than vertical polarization diversity system.

• Geomechanics and Engineering
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• 제31권6호
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• pp.615-622
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• 2022

In this paper, considering the temperature dependence of material physical parameters as well as the effects of thermal effect and shear deformation, we have conducted an in-depth study on the wave propagation of functionally graded (FG) materials circular plate in thermal environment based on the physical neutral surface concept. The dynamic governing equations of functionally graded plates are established, and the dispersion relation of wave propagation is derived. The influence of different temperature fields on the propagation characteristics of flexural waves in FG circular plates is discussed in detail. It can be found that the phase velocity and group velocity of wave propagation in the plate decrease with the increase of temperature.

• International journal of advanced smart convergence
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• 제13권2호
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• pp.276-283
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• 2024

Currently, the overall tendency for green and sustainable economic development is creating a circular economy. In actuality, agricultural output is currently benefiting greatly from the growth of the circular economy. The creation of a circular economy helps address resource scarcity, save the environment, combat climate change, and increase economic efficiency. Vietnam's economy can grow quickly and sustainably by shifting to a circular economy production model. Comparing prior growth techniques to the digital age and implementing circular economic development connected with high technology will be a fantastic opportunity to boost growth efficiency. In actuality, Vietnam currently has a large number of agricultural circular economy models. These are models: Creating and using gas from waste and wastewater in livestock and farming; model combining cultivation, livestock, and aquaculture; agro-forestry model; garden-forest model; Circular model using agricultural by-products as a catalyst or creating other valuable products; model of moderation, linked to reducing the use of growth hormones, veterinary medications, pesticides, and artificial fertilizers in agriculture and animal husbandry. Unfortunately, there have been few studies and applications of the aforementioned models, which has made it difficult to build the agricultural sector sustainably. In this paper, we outline the current situation and propose solutions to develop a circular economy model in agriculture in Vietnam for sustainable development.

• 해양환경안전학회지
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• 제23권5호
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• pp.558-565
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• 2017

해양환경의 극한 환경조건에 노출 된 고정식 및 부유식 해양구조물의 안전성과 설계비용 효율성에 있어서 파랑-구조물 상호작용의 정확한 예측은 중요하다. 본 연구에서는 규칙파 중 원형 기둥에 대한 파랑-구조물 상호작용을 해석하였다. 3차원 이상유동(two-phase flow)을 해석하기 위해 오픈소스 전산유체역학 라이브러리인 오픈폼을 사용하였다. 4개의 원형기둥이 정사각형 배열을 이루고 있을 때 규칙파의 입사각도에 따른 상호작용을 해석하였다. 원형 기둥 구조물에서의 wave run-up을 입사파의 기울기에 따라 비교하였다. 원형 기둥과 입사파의 상호작용으로 인해 원형 기둥 사이에 높은 파가 생성되는 것을 확인하였다. 본 해석 결과는 구조물과 입사파의 상호작용에 의한 air gap에 대한 연구의 기초자료로 활용될 것으로 기대된다.

• 한국해양환경ㆍ에너지학회지
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• 제1권1호
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• pp.102-111
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• 1998

해양관측시설은 고정식과 부유식으로 나뉘는데 본 고에서는 부유식 해상관측시설과 관련된 파랑하중 및 계류계에 대해 다루었다. 부유식 해상관측시설의 일 예에 대해 운동계산과 표류력 계산을 수행하고 고찰하였다. 또한 계류앵커의 일종인 원형 파일앵커가 수평력을 받는 경우의 모형실험과 파주력 계산을 위한 프로그램을 작성하여 그 계산결과와 비교 고찰하였다. SCUBA 활동으로 설치가능한 파일앵커의 파주력 추정에 기여할 것으로 기대된다.

• 반도체디스플레이기술학회지
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• 제6권4호
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• pp.39-42
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• 2007

Temperature distribution of the circular heat source was studied by analyzing the heat transfer of the environment of the circular source for OLED. Circular nozzle source was used to fabricate thin organic layer as the organic material in it was heated, vaporized and deposited to the large size panel. A modified heater structure of circular source has been suggested. The results of numerical analysis shows that the modified heater structure can use 15% more powder in a batch than the original heater structure does. Moreover, the modified heater structure can improve the uniformity of organic vapor deposition by controlling the temperature.

• Steel and Composite Structures
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• 제6권2호
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• pp.87-101
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• 2006

The deformation and dynamic behavior mechanism of submerged shell-like lattice structures with membranes are in principle of a non-conservative nature as circulatory system under hydrostatic pressure and disturbance forces of various types, existing in a marine environment. This paper deals with a characteristic analysis on quasi-periodic and chaotic behavior of a circular arch under follower forces with small disturbances. The stability region chart of the disturbed equilibrium in an excitation field was calculated numerically. Then, the periodic and chaotic behaviors of a circular arch were investigated by executing the time histories of motion, power spectrum, phase plane portraits and the Poincare section. According to the results of these studies, the state of a dynamic aspect scenario of a circular arch could be shifted from one of quasi-oscillatory motion to one of chaotic motion. Moreover, the correlation dimension of fractal dynamics was calculated corresponding to stochastic behaviors of a circular arch. This research indicates the possibility of making use of the correlation dimension as a stability index.

• Steel and Composite Structures
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• 제24권3호
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• pp.309-322
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• 2017

This paper conducted both numerical and theoretical studies to investigate the composite action of notched circular concrete-filled steel tubular (CFT) stub columns under axial compression and established a theoretical method to predict their ultimate bearing capacity. 3D finite element (FE) analysis was conducted to simulate the composite action and the results were in good agreement with experimental results on circular CFT stub columns with differently oriented notches in steel tubes. Parametric study was conducted to understand the effects of different parameters on the mechanical behavior of circular CFT stub columns and also the composite action between the steel tube and the core concrete. Based on the results, a theoretical formula was proposed to calculate the ultimate bearing capacity of notched CFT stub columns under compression with consideration of the composite action between the steel tube and the core concrete.

• 한국해양환경ㆍ에너지학회지
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• 제20권2호
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• pp.63-75
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• 2017

해양환경에서 파랑-구조물 상호작용의 정확한 예측은 극한 환경조건에 노출 된 고정식 및 부유식 해양구조물의 안전성과 설계비용 효율성에 있어서 중요하다. 본 연구에서는 규칙파 와 원형 기둥의 파랑-구조물 상호작용을 해석하였다. 3차원 이상유동(two-phase flow)을 해석하기 위해 오픈소스 전산유체역학 라이브러리인 OpenFOAM을 사용하였다. 수치파랑수조에서 파를 생성 및 흡수하기 위해 소스항을 이용한 relaxation method를 적용하였다. 수치기법을 검증하기 위해 심해조건에서 생성된 2차 stokes 파형은 이론적인 해와 비교하였다. 검증과정을 통해 파장과 진폭에 대한 길이 및 높이 방향의 격자크기를 정하였다. 원형 기둥에 작용하는 파랑 하중과 wave run-up을 계산하고 기존의 실험 데이터와 비교하였다.