• Journal of the Korean Mathematical Society
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• v.54 no.1
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• pp.1-16
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• 2017

In this paper we study a four dimensional tourism-based social-ecological dynamical system. In fact we analyse tourism profitability, compatibility and sustainability by using bifurcation theory in terms of structural properties of attractors of system. For this purpose first we transformed it into a three dimensional system such that the reduced system is the extended and modified model of the previous three dimensional models suggested for tourism with the same dimension. Then we investigate transcritical, pitchfork and saddle-node bifurcation points of system. And numerically by finding some branches of stable equilibria for system show the profitability of tourism industry. Then by determining the Hopf bifurcation points of system we find a family of stable attractors for that by numerical techniques. Finally we conclude the existence of these stable limit cycles implies profitability and compatibility and then the sustainability of tourism.

• Journal of the Korea Fashion and Costume Design Association
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• v.6 no.3
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• pp.1-8
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• 2004

The purpose of this study was to investigate gather as decoration techniques of clothes. In this study, we defined 21st century as the modern fashion. And analyzed design that applied gather concerned with Milan, New York, London, Paris, Tokyo Woman's Collections. Data were used from Fashion News and Gap Press Magazine (2001-2004). The results of this study were as follows: 1. Gather was the most original techniques among decoration techniques of clothes and formed three-dimensional space. 2. There were many kinds of gather such as cluster gather, all gather, shirring, smoking, frill, flounce, ruffle. and it gave a different impression with Fabrics, cutting method, sewing method, parts that were used. 3. Gather had practical functions providing enough space in activity and was presented as new shape by three-dimension body motion when it was put on. 4. After analyzing design that applied gather showed in collections, there were various appearance according to designer's sensitivity.

• Journal of The Korean Astronomical Society
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• v.49 no.1
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• pp.19-23
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• 2016

Magnetic decreases are often observed in various regions of interplanetary space. Many studies are devoted to reveal the physical nature and generation mechanism of the magnetic decreases, but still we do not fully understand magnetic decreases. In this study, we investigate the structure of a magnetic decrease observed in a corotating interaction region using multi-spacecraft measurements. We use three spacecraft, ACE, Cluster, and Wind, which were widely separated in the x- and y-directions in the geocentric solar ecliptic (GSE) coordinates. The boundaries of the magnetic decrease are the same at the three locations and can be identified as tangential discontinuities. A notable feature is that the magnetic decrease has very large dimension, ≳ R_E, along the boundary, which is much larger than the size, ~ 6 R_E, along the normal direction. This suggests that the magnetic decrease has a shape of a long, thin rod or a wide slab.

• Journal of computational fluids engineering
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• v.1 no.1
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• pp.26-34
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• 1996

The performance of the SIMPLE, SIMPLE-C and PISO algorithms for the treatment of the pressure-velocity coupling in fluid flow problems were examined by comparing the computational effort required to obtain the same level of the convergence. Example problems are circular duct and 90-degree bent square-duct. For circular duct case, laminar and turbulent flow were computed. For 90-degree bent square-duct case, laminar flow was simulated by the time-marching method as well as the iterative method. The convergence speed of the other two algorithms are not always superior to SIMPLE algorithm. SIMPLE algorithm is faster than SIMPLE-C algorithm in the simple laminar flow calculations. The application of the PISO algorithm in three dimensional general coordinates is not so effective as in two-dimensional ones. Since computational time of PISO algorithm is increased at each time step(or iterative step) in three dimension, the total convergence speed is not decreased. But PISO algorithm is stable for large time step by using time marching method,.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.10
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• pp.3113-3125
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• 1996

The objective of this study is to develop novel method named mechanical and chemical machining technique, which is capable of producing three dimensional patterns of few micrometers in dimension on a silicon wafer without the use of a mask. The strategy is to impart mechanical energy along the path of the pattern to be fabricated on a single crystal silicon by way on introdusing frictional interaction under controlled conditions. Then, the surface is preferentially etched to reveal the areas that have been mechanically energized. Upon completion of the etching process, the three dimensional pattern is produced on the silicon surface. Experiments have been conducted to identify the optimal tool material, geometery, as well as fabrication condition. The new technique introduced in this paper is significantly simpler than the conventional method which require sophisticated equipment and much time.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.296-299
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• 2001

We developed a motion capture system to get angle data of human joints in the walking mode. The motion capture system is a pair of leg-shape device, which is composed of three links with ankle, knee and pelvis joints. The sensors for measurement of the joint angle are potentiometers. We used an A/D converter to get digital data from joint angles, and which are used to simulate and coordinate the biped-walking robot developed in our laboratory. To simulate and analyze walking motion, animation based on three-dimension motion is performed using the open inventor software.

• Journal of International Society for Simulation Surgery
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• v.4 no.1
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• pp.17-20
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• 2017

Purpose Interactive 3D visualization system through remote data transmission over heterogeneous network is growing due to the improvement of internet based real time streaming technology. Materials and Methods The current internet's IP layer has several weaknesses against IP spoofing or IP sniffing type of network attacks since it was developed for reliable packet exchange. In order to compensate the security issues with normal IP layer, we designed a remote medical visualization system, based on Virtual Private Network. Results Particularly in hospital, if there are many surgeons that need to receive the streaming information, too much load on the gateway can results in deficit of processing power and cause the delay. Conclusion End to end security through the network method would be required.

• Korean Journal of Optics and Photonics
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• v.5 no.4
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• pp.439-444
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• 1994

When diffraction by arbitrary two-dimensional surface-relief dielectric gratings is analyzed using the rigorous three-dimensional vector coupled-wave analysis, it is found that the matrix eigenvalue problem pertaining to the analysis can always be simplified to that for a matrix which has the dimension of a quarter of the original, so that computing time and memory requirements for computer may be greatly reduced. However this kind of simplification can not be obtained in the case of volume diffraction gratings. tings.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.1
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• pp.80-87
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• 1998

In this study, a multi-element ultrasound transducer has been developed aiming at basic experiment of three-dimension endovascular ultrasound endscopy for clinical diagnos, and experimental results of two-dimensional object imaging in the water are presented by the ultrasound tranducer and neural network. Each ultrasound echo received by thirty-six angular transducer elements is inputed to the eural network, and then backpropagation is used as a learning algorithm. A three-layer artificial neural network is used for learning and imaging of targetw placed in front of the transducer. The object shape of imaging is restricted to rectangular shapes by considering experimental restraint conditions. As a result, rough visualization can be realized even for objects with unlearned shapes through the training by primitive patterns of a various sized rectangular targets.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.3
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• pp.250-256
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• 2007

We analyzed the effect of a pixel and all the inter-electrode capacitances in a unit pixel of TFT-LCDs on the gray scale capability. The pixel and all the inter-electrode parasitic capacitances were obtained from the tree dimensional profiles of potential distribution and molecular director considering lateral fields generated at the edge of the pixel. To obtain the RMS and kickback voltages of the pixel, we constructed an equivalent circuit of the panel containing all the parasitic capacitances. The calculation was performed though H-SPICE. As results, we confirmed that the pixel becomes smaller, the effect of parasitic capacitances on the gray scale capability becomes larger.