• Journal of Magnetics
• /
• v.20 no.1
• /
• pp.79-85
• /
• 2015

This paper presents a comparative study of a Tubular Linear Machine (TLM) with an Axially Magnetized Single-sided Permanent Magnet (AMSPM) and an Axially Magnetized Double-sided Permanent Magnet (AMDPM) based on analytical field calculations. Using a two-dimensional (2-D) polar coordinate system and a magnetic vector potential, analytical solutions for the flux density produced by the stator windings are derived. This technique is significant for the design and control implementation of electromagnetic machines. The field solution is obtained by solving Maxwell's equations in the simplified boundary value problem consisting of the air gap and coil. These analytical solutions are then used to estimate the self and mutual inductances. Two different types of machine are used to verify the validity of these model simplifications, and the analytical results are compared to results obtained using the finite element method (FEM) and experimental measurement.

• Journal of the Optical Society of Korea
• /
• v.15 no.1
• /
• pp.30-37
• /
• 2011

Binocular-pair images obtained from two cameras can be used to calculate the three-dimensional (3D) world coordinate of a feature point. However, to apply this method, measurement accuracy of binocular vision depends on some structure factors. This paper presents an experimental study of measurement distance, baseline distance, and baseline direction. Their effects on camera reconstruction accuracy are investigated. The testing set for the binocular model consists of a series of feature points in stereo-pair images and corresponding 3D world coordinates. This paper discusses a method to increase the baseline distance of two cameras for enhancing the accuracy of a binocular vision system. Moreover, there is an inflexion point of the value and distribution of measurement errors when the baseline distance is increased. The accuracy benefit from increasing the baseline distance is not obvious, since the baseline distance exceeds 1000 mm in this experiment. Furthermore, it is observed that the direction errors deduced from the set-up are lower when the main measurement direction is similar to the baseline direction.

• Journal of Korea Society of Digital Industry and Information Management
• /
• v.17 no.4
• /
• pp.133-146
• /
• 2021

In the field of food and drug, the role of the Ministry of Food and Drug Safety is becoming more important for national and public safety as well as national development and improvement of public welfare. Food and drug statistics are being used to determine the priorities and directions of policy for the promotion of public health and the development of the health industry. This study focuses on statistics from the MFDS. Through the analysis of the MFDS's statistics, the current status of the MFDS's production statistics was identified, and the survey of utilization and satisfaction of the MFDS's statistics was conducted on food and drug experts who actually use the statistics of the MFDS. In order to identify problems of the MFDS statistics, environmental factors affecting the MFDS statistics were derived, and the priorities of improvement tasks for its statistics were identified using AHP and IPA. In addition, the current situation of the statistical system, which serve as the basic coordinate for the establishment and execution of domestic food and drug policies, was identified and implications were provided.

• International Journal of Computer Science & Network Security
• /
• v.21 no.9
• /
• pp.247-260
• /
• 2021

Data modeling is a process of developing a model to design and develop a data system that supports an organization's various business processes. A conceptual data model represents a technology-independent specification of structure of data to be stored within a database. The model aims to provide richer expressiveness and incorporate a set of semantics to (a) support the design, control, and integrity parts of the data stored in data management structures and (b) coordinate the viewing of connections and ideas on a database. The described structure of the data is often represented in an entity–relationship (ER) model, which was one of the first data-modeling techniques and is likely to continue to be a popular way of characterizing entity classes, attributes, and relationships. This paper attempts to examine the basic ER modeling notions in order to analyze the concepts to which they refer as well as ways to represent them. In such a mission, we apply a new modeling methodology (thinging machine; TM) to ER in terms of its fundamental building constructs, representation entities, relationships, and attributes. The goal of this venture is to further the understanding of data models and enrich their semantics. Three specific contributions to modeling in this context are incorporated: (a) using the TM model's five generic actions to inject processing in the ER structure; (b) relating the single ontological element of TM modeling (i.e., a thing/machine or thimac) to ER entities and relationships; and (c) proposing a high-level integrated, extended ER model that includes structural and time-oriented notions (e.g., events or behavior).

• Steel and Composite Structures
• /
• v.29 no.5
• /
• pp.569-578
• /
• 2018

This paper aims to investigate the transient vibration behavior of functionally graded carbon nanotube (FG-CNT) reinforced nanocomposite plate resting on Pasternak foundation under pulse excitation. The plate is considered to be composed of matrix material and multi-walled carbon nanotubes (MWCNTs) with distribution as per the functional grading concept. The functionally graded distribution patterns in nanocomposite plate are explained more appropriately with the layer-wise variation of carbon nanotubes weight fraction in the thickness coordinate. The layers are stacked up in such a way that it yields uniform and three other types of distribution patterns. The effective material properties of each layer in nanocomposite plate are obtained by modified Halpin-Tsai model and rule of mixtures. The governing equations of an illustrative case of simply-supported nanocomposite plate resting on the Pasternak foundation are derived from third order shear deformation theory and Navier's solution technique. A converge transient response of nanocompiste plate under uniformly distributed load with triangular pulse is obtained by varying number of layer in thickness direction. The validity and accuracy of the present model is also checked by comparing the results with those available in literature for isotropic case. Then, numerical examples are presented to highlight the effects of distribution patterns, foundation stiffness, carbon nanotube parameters and plate aspect ratio on the central deflection response. The results are extended with the consideration of proportional damping in the system and found that nanocomposite plate with distribution III have minimum settling time as compared to the other distributions.

• Structural Engineering and Mechanics
• /
• v.71 no.6
• /
• pp.713-738
• /
• 2019

In the paper the dynamics of the oscillating moving load acting in the interior of the hollow cylinder surrounded with elastic medium is studied within the scope of the exact field equations of 3D elastodynamics. It is assumed that the oscillating load act on the certain arc of the internal circle of the cylinder's cross section and this load moves with constant velocity along the cylinder's axis. The corresponding 3D dynamic problem is solved by employing moving coordinate system, the exponential Fourier transform and the presentation these transforms with the Fourier series. The expressions of the transforms are determined analytically, however their originals are found numerically. Under the investigations carried out in the paper the main attention is focused on the so-called "gyroscopic effect", according to which, the influence of the vibration frequency on the values of the critical velocity and interface stresses are determined. Numerical results illustrated this effect are presented and discussed. In particular, it is established how the non-axisymmetricity of the problem acts on the influence of the load oscillation on its critical velocity and on the interface stresses.

• Journal of The Korean Society of Integrative Medicine
• /
• v.7 no.2
• /
• pp.59-67
• /
• 2019

Purpose : The purpose of this study was to analyze the dynamic range of motion (ROM) of pelvic and translation of center of mass (COM) when wearing different shoe insole lifts according to leg length discrepancy (LLD) during free speed gait. Methods : Thirty-five healthy adults were participated in this study. Kinematic data were collected using a Vicon motion capture system. Reflective and cluster 40 markers attached to participants lower extremities and were asked to walk in a 6 m gait way under three different shoe lift conditions (without any insole, 1 cm insole, and 2 cm insole). The pelvic ROM and COM translation in three planes were sorted using a Nexus software, and a Visual3D motion analysis software was used to coordinate all kinematic data. Results : There were significantly increased maximal pelvic elevation and total pelvic range in coronal plane when wearing a standard shoe with 2 cm insole lift during gait (p<.05). When wearing a standard shoe with 2 cm insole lift, the total range of the pelvic segment were significantly different in all three motion planes (p<.05). Conclusion : Although LLD of less than 2 cm develops abnormal movement pattern of the pelvis and may cause of musculoskeletal diseases such as low back pain, hip and knee joint osteoarthritis, therefore intensive various physical therapy interventions for LLD are needed.

• Progress in Superconductivity and Cryogenics
• /
• v.21 no.1
• /
• pp.25-30
• /
• 2019

This paper presents a conceptual design approach of air-cored synchronous machine with high temperature superconductor (HTS) field winding. With a given configuration of a target machine, boundary conditions are set in the cylindrical coordinate system and analytic field calculation is performed by solving a governing equation. To set proper boundary conditions, current distributions of the field winding and the armature winding are expressed by the Fourier expansion. Based on analytic magnetic field calculation results, key machine parameters are calculated: 1) inductance, 2) critical current of field winding, 3) weight, 4) HTS conductor consumption, and 5) efficiency. To investigate all potential design options, 6 sweeping parameters are determined to characterize the geometry of the machine and the parameter calculation process is performed for each design options. Among design options satisfying constraints including >80 % critical current margin and >95 % efficiency, in this paper, a first-cut design was selected in terms of overall machine weight and HTS conductor consumption to obtain a lightweight and economical design. The goal is to design a 5-MW machine by referring to the same capacity machine that was previously constructed by another group. Our design output is compared with finite element method (FEM) simulation to validate our design approach.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.11 no.1
• /
• pp.233-243
• /
• 2019

In this paper, numerical and experimental studies are performed to investigate the liquid impact on a free falling wedge. In the numerical simulation, the structure is assumed to be rigid and the elastic response is ignored. The fully nonlinear coupling between wedge and water is considered by an auxiliary function method based on the Boundary Element Method (BEM). At the intersection of the wedge surface and liquid surface, two coincident nodes are used to decouple the boundary conditions. The Eulerian free surface conditions in the local coordinate system are adopted to update the deformed free surface. In the experiments, five pressure sensors are fixed on each side of the wedge which is released from an experimental installation. Steel and aluminum wedges that have different structural elasticity are used in the experiments to investigate the influence of structural elasticity on the impact force. Numerical results are compared with experimental data and they agree very well. The influence of fluid gravity, body mass, initial entry speed and deadrise angle on the impact pressure are further investigated.

• Annual Conference of KIPS
• /
• 2013.05a
• /
• pp.363-366
• /
• 2013

오늘날 도난방지, 화재, 범죄예방 등의 안전한 생활을 위한 감시 시스템의 중요성이 강조되고 있다. 이에 영상보안 시장 규모가 급속히 증가하고 있으며 관련 기술도 인공지능을 겸비한 형태로 발전하고 있다. 우리나라도 영상보안 시스템의 수요가 2002년부터 기업과 정부를 중심으로 증가하고 있으며 급속한 성장을 거듭하는 추세는 2012년 이후에도 지속될 전망이다. 특히, 최근에는 적은 대수의 카메라로 보다 넓은 지역을 관찰하고 특정 부분을 확대 관찰할 수 있는 PTZ 카메라의 활용이 증가하고 있다. PTZ 카메라는 카메라에 구동 장치를 추가하여 좌우(Pan), 상하(Tilt)로 카메라의 시점을 이동시킬 수 있으며 특정 부분을 확대하여 관찰할 수 있는 줌(Zoom) 기능을 가진 카메라를 말한다. 이와 같은 장점으로 지능형 PTZ 카메라는 점차 대중화 되고 있다. 하지만, 현재 시중에 판매되는 많은 종류의 PTZ 카메라를 이용한 영상보안 감시는 실제로 사용자들이 동작하고 사용하는데 있어서 많은 문제점을 가지고 있다. 이에 본 논문에서는 카메라 별로 제공하는 상이하고 왜곡된 좌표 값에서 새롭게 가공한 직관적 절대좌표 값을 추출하여 정확한 목표지점으로의 위치이동과 간편한 카메라 조작을 위한 시스템을 설계하였다.