• Journal of the Korean Society for Precision Engineering
• /
• v.23 no.5 s.182
• /
• pp.143-148
• /
• 2006

It is still very difficult to generate a geometry model and finite element model, which has complex and many free surface, even though 3D CAD solutions are applied. Furthermore, in the medical field, which is a big growth area of recent years, there is no drawing. For these reasons, making a geometry model, which is used in finite element analysis, is very difficult. To resolve these problems and satisfy the requests of the need to create a 3D digital file for an object where none had existed before, new technologies are appeared recently. Among the recent technologies, there is a growing interest in the availability of fast, affordable optical range laser scanning. The development of 3D laser scan technology to obtain 3D point cloud data, made it possible to generate 3D model of complex object. To generate CAD and finite element model using point cloud data from 3D scanning, surface reconstruction applications have widely used. In the early stage, these applications have many difficulties, such as data handling, model creation time and so on. Recently developed point-based surface generation applications partly resolve these difficulties. However there are still many problems. In case of large and complex object scanning, generation of CAD and finite element model has a significant amount of working time and effort. Hence, we concerned developing a good direct finite element model generation method using point cloud's location coordinate value to save working time and obtain accurate finite element model.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.17 no.5
• /
• pp.552-559
• /
• 2004

In recent, there have been several developments in lamp technology that promise savings in electrical power consumption and improved quality of the lighting space. Above all, the advantage of ring-shaped electrodeless fluorescent lamp is the removal of internal electrodes and heating filaments that are a light-limiting factor of conventional fluorescent lamps. The ring-shaped electrodeless lamp is intended as a high efficiency replacement for the incandescent reflector lamp in many applications. Therefore, the life time of ring-shaped electrodeless fluorescent lamps is substantially higher than that of conventional fluorescent lamps and last up to 60,000 hours. In this paper, maxwell 3D finite element analysis program(Ansoft) was used to obtain electromagnetic properties associated with the coil and nearby structures. The electromagnetic emitting properties were presented by 3D simulation software operated at 250 KHz and some specific conditions. The optical characteristics were measured luminance and a temperature and an optical spectrum distribution for 10 min in a one minute interval at the same time. With a goal of finding alternative materials, we show measurement results of electrical characteristics of a ring-shaped electrodeless fluorescent lamp as a function of frequency and the number of coil turns using a highly permeable($\mu$$_{r}$(equation omitted) 2,000) Mn-Zn ferrite. These results are compared with those of conventional ring-shaped electrodeless fluorescent lamp. It is found that the resistance, inductance and impedance are increased while the quality factor decreases as frequency increases.s.

• Fashion & Textile Research Journal
• /
• v.18 no.3
• /
• pp.261-271
• /
• 2016

The aim of this study was to gain an understanding of the element playfulness in fashion photographs related to openness and multiple significance in contemporary art. A total of 105 fashion photographs from US and UK Vogue magazine editorials and advertisements for the last five years were selected for the study. The photographs were analyzed in two main categories - the contextual element of themes, and the elements of visual expression; composition, models, objects and editing technology. The element of playfulness in the photographs were found to be divided into themes of infantile fantasy, social satire and situational dissonance, and elements of visual expression were found to express image distortion, expansion, exaggeration, reduction, and optical illusions. A photography type termed as infantile fantasy and social satire have descriptive characteristics and usually deliver the message by using models and objects to present a certain situation or express social satirical viewpoint and reflective attitude by using objects and photographic skills. A photography type termed as situational dissonance is characterized by immediately understood expressions and usually clarify the message by using a photographic technology such as editing the printed image or expect the model to express an exaggerated poses and ridiculous expressions, causing an optical illusion. Visually expressed and composed scene using composition, models, objects and editing technology is a specific character of photograph and due to the advances in computer editing technology it has been able to express the various playfulness.

• International Journal of Safety
• /
• v.6 no.2
• /
• pp.1-7
• /
• 2007

In this study mechanical strength of A53B carbon steel was analyzed using several types of test specimens directly machined from oil recycling pipe experienced a failure due to hydrogen attack in chemical plants. High temperature hydrogen attack (HTHA) is the damage process of grain boundary facets due to a chemical reaction of carbides with hydrogen, thus forming cavities with high pressure methane gas. Driven by the methane gas pressure, the cavities grow on grain boundaries forming intergranular micro cracks. Microscopic optical examination, tensile test, Charpy impact test, hardness measurement, and small punch (SP) test were performed. Carbon content of the hydrogen attacked specimens was dramatically reduced compared with that of standard specification of A53B. Traces of decarburization and micro-cracks were observed by optical and scanning electron microscopy. Charpy impact energy in hydrogen attacked part of the pipe exhibited very low values due to the decarburization and micro fissure formation by HTHA, on the other hand, data tested from the sound part of the pipe showed high and scattered impact energy. Maximum reaction forces and ductility in SP test were decreased at hydrogen attacked part of the pipe compared with sound part of the pipe. Finite element analyses for SP test were performed to estimate tensile properties for untested part of the pipe in tensile test. And fracture toughness was calculated using an equivalent strain concept with SP test and finite element analysis results.

• Smart Structures and Systems
• /
• v.24 no.6
• /
• pp.709-721
• /
• 2019

This paper investigates the framework of vision-based dense displacement and strain measurement of miter gates with the approach for the quantitative evaluation of the expected performance. The proposed framework consists of the following steps: (i) Estimation of 3D displacement and strain from images before and after deformation (water-fill event), (ii) evaluation of the expected performance of the measurement, and (iii) selection of measurement setting with the highest expected accuracy. The framework first estimates the full-field optical flow between the images before and after water-fill event, and project the flow to the finite element (FE) model to estimate the 3D displacement and strain. Then, the expected displacement/strain estimation accuracy is evaluated at each node/element of the FE model. Finally, methods and measurement settings with the highest expected accuracy are selected to achieve the best results from the field measurement. A physics-based graphics model (PBGM) of miter gates of the Greenup Lock and Dam with the updated texturing step is used to simulate the vision-based measurements in a photo-realistic environment and evaluate the expected performance of different measurement plans (camera properties, camera placement, post-processing algorithms). The framework investigated in this paper can be used to analyze and optimize the performance of the measurement with different camera placement and post-processing steps prior to the field test.

• Corrosion Science and Technology
• /
• v.17 no.1
• /
• pp.1-5
• /
• 2018

As structural materials, magnesium (Mg) alloys have been widely used in the fields of aviation, automobiles, optical instruments, and electronic products. There are few studies on the effect of coating conditions on the compositional variation during the formation process of the conversion coatings. Rare-earth based conversion coating on AZ91 magnesium alloy was prepared in ceric sulfate and hydrogen peroxide contained solution. The element composition and valence as well as their distribution in the coating were analyzed with energy dispersive X-ray spectroscopy (EDS), Electron probe micro-analyzer (EPMA), X-ray photoelectron spectroscopy (XPS). The effect of treating process on the element composition were also studied. It was found that the conversion coating surface consists of Mg, Al, O, Ce, and the weight content of Ce in the coating was affected by the treating solution concentration and immersion time; the Ce element was distributed in the coating non-uniformly and existed in the form of $Ce^{+3}$ and $Ce^{+4}$, while the O element existed in the form of $OH^-$, $O^{2-}$, $H_2O$. Based on microscopic analysis results, the electrochemical deposition mechanism on the micro-anode and micro-cathode in the process of the coating growth was suggested.

• Journal of the Institute of Electronics Engineers of Korea CI
• /
• v.39 no.6
• /
• pp.24-35
• /
• 2002

The wavelet transform is combined with the boundary element method (BEM), to solve efficiently the Maxwell's equation and the proposed method is applied to the electromagnetic problem for the analysis of topological effects of phase-shifting masks. The accuracy of the module developed was verified by comparison with both analytic solutions and published results. In addition, it was found that the boundary element method in combination with the wavelet matrix transform would be more efficient than the conventional methods based on the BEM in views of the calculation speed and the usage of computer memory.

• Journal of the Institute of Electronics Engineers of Korea CI
• /
• v.43 no.4 s.310
• /
• pp.23-30
• /
• 2006

This paper presents design andd verification of a circuit that improves the control-operation problems of Stored Program Optical Computer (SPOC), which is an optical computer using $LiNbO_3$ optical switching element. Since the memory of SPOC takes the Delay Line Memory (DLM) architecture and instructions that are needless of operands should go though memory access stages, SPOC memory have problems; it takes immoderate access time and unnecessary operations are executed in Arithmetic Logical Unit (ALU) because desired operations can't be selectively executed. In this paper, improvement on circuit has been achieved by removing the memory access of instructions that are needless of operands by decoding instructions before locating operand. Unnecessary operations have been reduced by sending operands to some specific operational units, not to all the operational units in ALD. We show that total execution time of a program is minimized by using the Dual Instruction Register(DIR) architecture.

• Journal of Sensor Science and Technology
• /
• v.10 no.1
• /
• pp.42-51
• /
• 2001

In this study, the effects of embedded optical fibers on the static properties under tensile load and dynamic properties under fatigue load of composite laminates were investigated by experimental tests and finite element analysis. Based on the results, it can be concluded that the embedded optical fiber sensors do not have significant effects on the structural integrity of the smart composite structures except when the sensors are embedded perpendicular to the adjacent reinforcing fibers under fatigue loading. An intensity-based optical fiber sensor was embedded in the crossply composite laminates to monitor the fatigue damage by detecting the stiffness changes of the laminates. The result of this experiment has shown that the intensity-based optical fiber sensor has large potential to monitor the fatigue damage of composite structures by detecting the stiffness changes of the structures with simple and inexpensive instruments and without complex post-processing of measured signals. In addition, the optical fiber sensor showed good resistance to fatigue loading and wide sensing ranges of stiffness.

• 한국전산유체공학회:학술대회논문집
• /
• 2009.04a
• /
• pp.135-141
• /
• 2009

A preliminary thermal analysis is performed for the optical payload system of a geostationary satellite. The optical payload considered in this paper is GOCI(Geostationary Ocean Color Imager) of COMS of Korea. The radiative and conductive thermal models are employed in order to predict thermal responses of the GOCI on the geostationary orbit. According to the results of this analysis are as follows: 1) the GOCI instrument thermal control is satisfactory to provide the temperatures for the GOCI performances, 2) the thermal control is defined and interfaces are validated, and 3) the entrance baffle temperature is found slightly out its specification, therefore further detailed analyses should be continued on this element.