• Spatial Information Research
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• 제21권4호
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• pp.35-45
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• 2013

대부분의 멀티미디어 데이터는 위치정보를 가지고 있다. 따라서 각 멀티미디어 데이터에 적절한 위치정보를 추가하면, 다양한 용도로 활용이 가능하다. 특히 멀티미디어의 위치검색이 다양한 검색조건으로 제공될 수 있다. 지금까지 멀티미디어의 위치는 주로 실외공간의 (x, y, z) 좌표공간을 기반으로 정의된다. 최근 실내공간 정보기술이 발달하면서 실외뿐 아니라, 실내공간에서도 다양한 위치기반 서비스가 가능하며, 멀티미디어의 실내공간 안에서의 위치를 정의할 수 있게 되었다. 그러나 실내공간의 위치는 실외공간의 위치참조체계와 다르다. 예를 들어, 실내공간에서 위치를 지정할 때는 좌표를 이용하지 않고, 층과 방의 번호를 이용한다. 방 번호와 같은 기호를 이용하여 위치를 지정하는 공간을 기호공간이라고 한다. 본 논문에서는 기호공간을 기반으로 실내공간에서 만들어진 멀티미디어 자료의 위치를 지정하는 방법을 제안한다. 이 방법은 특히 현재 진행 중인 OGC의 실내공간정보 표준인 IndoorGML에서 제시하는 데이터모델을 이용한다. 따라서 본 방법은 실내공간에서 만들어진 멀티미디어의 위치를 효과적으로 표현하며, 동시에 여러 시스템이나 서비스간의 호환성을 높이는데 유용하다.

• Steel and Composite Structures
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• 제44권1호
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• pp.65-79
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• 2022

The main goal of this paper is to study the vibration of damaged core laminated annular plates with FG face sheets based on a three-dimensional theory of elasticity. The structures are made of a damaged isotropic core and two external face sheets. These skins are strengthened at the nanoscale level by randomly oriented Carbon nanotubes (CNTs) and are reinforced at the microscale stage by oriented straight fibers. These reinforcing phases are included in a polymer matrix and a three-phase approach based on the Eshelby-Mori-Tanaka scheme and on the Halpin-Tsai approach, which is developed to compute the overall mechanical properties of the composite material. In this study the effect of microcracks on the vibrational characteristic of the sandwich plate is considered. In particular, the structures are made by an isotropic core that undergoes a progressive uniform damage, which is modeled as a decay of the mechanical properties expressed in terms of engineering constants. These defects are uniformly distributed and affect the central layer of the plates independently from the direction, this phenomenon is known as "isotropic damage" and it is fully described by a scalar parameter. Three complicated equations of motion for the sectorial plates under consideration are semi-analytically solved by using 2-D differential quadrature method. Using the 2-D differential quadrature method in the r- and z-directions, allows one to deal with sandwich annular plate with arbitrary thickness distribution of material properties and also to implement the effects of different boundary conditions of the structure efficiently and in an exact manner. The fast rate of convergence and accuracy of the method are investigated through the different solved examples. The sandwich annular plate is assumed to have any arbitrary boundary conditions at the circular edges including simply supported, clamped and, free. Several parametric analyses are carried out to investigate the mechanical behavior of these multi-layered structures depending on the damage features, through-the-thickness distribution, and boundary conditions.

• Steel and Composite Structures
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• 제48권1호
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• pp.1-17
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• 2023

The main goal of this paper is to study vibration of damaged core laminated sectorial plates with Functionally graded (FG) face sheets based on three-dimensional theory of elasticity. The structures are made of a damaged isotropic core and two external face sheets. These skins are strengthened at the nanoscale level by randomly oriented Carbon nanotubes (CNTs) and are reinforced at the microscale stage by oriented straight fibers. These reinforcing phases are included in a polymer matrix and a three-phase approach based on the Eshelby-Mori-Tanaka scheme and on the Halpin-Tsai approach, which is developed to compute the overall mechanical properties of the composite material. Three complicated equations of motion for the sectorial plates under consideration are semi-analytically solved by using 2-D differential quadrature method. Using the 2-D differential quadrature method in the r- and z-directions, allows one to deal with sandwich annular sector plate with arbitrary thickness distribution of material properties and also to implement the effects of different boundary conditions of the structure efficiently and in an exact manner. The fast rate of convergence and accuracy of the method are investigated through the different solved examples. The sandwich annular sector plate is assumed to be simply supported in the radial edges while any arbitrary boundary conditions are applied to the other two circular edges including simply supported, clamped and free. Several parametric analyses are carried out to investigate the mechanical behavior of these multi-layered structures depending on the damage features, through-the-thickness distribution and boundary conditions.

• 대한의용생체공학회:의공학회지
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• 제18권3호
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• pp.243-251
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• 1997

본 연구에서는 유체보상 경사자장 기법(flow-compensation-gradient of gradient-moment nulling method)을 이용하지 않은 Tailored RF를 이용한 TRFGE(tailored rf gradient echo) 영상에는 유체유입효과(in-flow effect)가 나타나지 않지만 절편(slice)내에서 판독경사자장(reading gradient)과 같은 방향으로 흐르는 유체는 신호가 강조가 됨을 이론과 실험으로 보였다. 절편 내에서 판독경사자장과 같은 방향으로 흐르는 유체의 신호가 TRFGE 영상에서 강조되는 이유를 이론적으로 설명하였으며 이 이론을 뒷받침 할 실험을 위해 유체 모형을 제작하였다. 원통 모양의 물 모형 중앙으로 유체 관을 통해 식염수(saline)가 주자장(B$B_0$)와 평행인 z 축 방향으로 흐를 수 있도록 하였다. 유체가 흐를 때와 흐르지 않을 때 CGE(conventional gradient echo) 영상과 TRFGE 영사을 얻어 각각 비교하였다. 유체 유입효과를 관찰하기 위해서는 횡단면(axial)의 영상을 얻었고 절편 내에서 판독경사자장과 같은 방향으로 흐르는 유체의 영상신호를 관찰하기 위해서 시상면(sagittal) 영상을 얻었다.

• 분석과학
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• 제20권3호
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• pp.183-192
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• 2007

최근의 전기전자제품 중 유해물질규제지침(RoHS)이나 폐전기전자제품 처리 지침(WEEE) 등의 각종 환경규제는 국제교역에 있어 실질적인 무역장벽으로 작용하고 있다. 한국표준과학연구원(KRISS)에서는 이와 같은 환경규제와 관련하여 국내시험연구기관 및 관련산업체실험실의 측정 신뢰성 확보를 위한 숙련도 시험을 실시하였다. 참여기관은 국내 전기전자 제품 및 자동차 관련 실험실 31개소이다. 숙련도시험용 시료는 pellet type 폴리프로필렌 소재 2 종이며, 측정대상원소는 유럽공동체의 RoHS 지침에서 규정하고 있는 6개 성분 중 카드뮴 (Cd)과 납 (Pb)이다. 시료는 2006년 9월 1일 각 참여실험실에 우편 송부하였으며 10월 10일까지 측정 결과를 접수하였다. 각 실험실의 측정 결과는 KRISS 기준값과의 비교, Robustic Z-score, Youden plot 등에 의해 비교 평가하고 전처리 방법에 따른 측정 결과도 비교 검토하였다. 전반적으로 기준값과의 10% 범위 내에서 일치되는 결과를 보고하였으나 일부 실험실은 심각한 bias를 보이고 있어 측정결과의 신뢰성 향상을 위한 품질보증 시스템을 갖추어야 할 필요가 있다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 추계학술대회 논문집
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• pp.245-249
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• 2009

According to the increase of intelligent vehicles many automotive electric components are installed. The wire harness which connects those also increases. The crimping process for compressing the copper wire bundle into the terminal is a key process to assure the good quality of wire harness. For the case of inadequate forming condition many shape failures such as less-filling, over-filling are happen in the crimping process. Even though the quality of crimping shape is satisfactory the quality check for electrical resistance of wire harness is sometime not satisfied the qualification due to large variation of electrical resistance of wire harness under climate test. This large variation is thought to be related with the malfunction automotive electric system and caused by the internal stress of wire, which occurred during the crimping process. In this paper we develop the 3D-FEM simulation scheme and design methodology of optimum terminal shape. Also the effect of terminal shape on the residual stress is discussed.

• 천문학회보
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• 제40권1호
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• pp.73.1-73.1
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• 2015

Isolated galaxies in low-density regions are significant in the sense that they are least affected by the hierarchical pattern of galaxy growth and interactions with perturbers at least for the last few Gyr. To form a comprehensive picture of the star formation history of isolated galaxies, we construct a catalog of isolated galaxies and their comparison sample in relatively denser environments. The galaxies are drawn from SDSS DR7 in the redshift range of 0.025 < z < 0.044. We performed visual inspection and classified their morphology following the Hubble classification scheme. We have investigated the color-magnitude diagram and found elliptical and unbarred spiral galaxies in isolated systems are relatively fainter and bluer than those in denser regions. For the spectroscopic study, we make use of the OSSY catalog (Oh et al. 2011). Our analysis on the absorption-line properties based on the comparison with stellar population models suggests that isolated elliptical galaxies are likely to be younger and metal poorer, while isolated Sc-type galaxies seem to have older luminosity-weighted ages, than their high-density counterpart. In addition, according to the BPT diagnostics, early-type galaxies among isolated galaxies are rather evenly classified into star forming, composite, Seyfert and LINER, whereas their comparisons are mainly populated in the LINER region. On the other hand, late-type galaxies do not show any prominent difference. We discuss the evolutionary histories of isolated galaxies in the context of the standard ${\Lambda}CDM$ cosmology.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국제학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.202-207
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• 1993

A theoretical and experimental study is presented for the force holding control of a miniature robotic ringer which is driven by a pair of piezoelectric unimorph cells. In the theoretical analysis, one finger is modeled as a flexible cantilever with a tactile force sensor at the tip and the mate of the finger is a solid beam supposed with sufficient stiffness. Further, the force sensor is modeled by a one-degree-of-freedom, mass-spring system and the output of sensor is then described by the sensor stiffness multiplied by the relative displacement. The problem investigated in this paper is that two typical holding tasks of the human finger are picked up and applied to the robotic finger. One is the work holding a stationary object with a prescribed, time-varying force and the other one is to keep the contacted force constant even if the object is in motion. The simple PID feedback control scheme is used to control the minute gripping force of order 0.01 Newton. It is shown both experimentally and theoretically that the artificial finger with the piezoelectric actuator works well in the minute force holding of the tiny object.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2005년도 춘계학술대회
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• pp.260-263
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• 2005

The effects of internal manifold designs the reactant feed-stream in Polymer Electrolyte Fuel Cells (PEFCs) is studied to figure out mass flow-distribution patterns over an entire fuel cell stack domain. Reactants flows are modeled either laminar or turbulent depending on regions and the open channels in the bipolar plates are simulated by porous media where permeability should be pre-determined for computational analysis. In this work, numerical models for reactant feed-stream in the PEFC manifolds are classified into two major flow patterns: Z-shape and U-shape. Several types of manifold geometries are analyzed to find the optimal manifold configurations. The effect of heat generation in PEFC on the flow distribution is also investigated applying a simplified heat transfer model in the stack level (i.e. multi-cell electrochemical power-generation unit). This modeling technique is well suited for many large scale problems and this scheme can be used not only to account for the manifold flow pattern but also to obtain information on the optimal design and operation of a PEMC system.

• 한국정밀공학회지
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• 제21권12호
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• pp.100-108
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• 2004

In reverse engineering, data acquisition methodology can generally be categorized into contacting and non-contacting types. Recently, researches on hybrid or sensor fusion of the two types have been increasing. In addition, efficient construction of a geometric model from the measurement data is required, where considerable amount of user interaction to classify and localize regions of interest is inevitable. Our research focuses on the classification of each bounded region into a pre-defined feature shape fer a hybrid measuring scheme, where the overall procedures are described as fellows. Firstly, the physical model is digitized by a non-contacting laser scanner which rapidly provides cloud-of-points data. Secondly, the overall digitized data are approximated to a z-map model. Each bounding curve of a region of interest (featured area) can be 1.aced out based on our previous research. Then each confined area is systematically classified into one of the pre-defined feature types such as floor, wall, strip or volume, followed by a more accurate measuring step via a contacting probe. Assigned to each feature is a specific digitizing path topology which may reflect its own geometric character. The research can play an important role in minimizing user interaction at the stage of digitizing path planning.