• Korean Journal of Computational Design and Engineering
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• v.22 no.1
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• pp.37-43
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• 2017

3D printing techniques can be used in various application fields and many researches have been reported. FDM (Fused Deposition modeling) can make multi-material or multi-color models with the simultaneous use of two or more filaments. In a dual-nozzle FDM printers, while the active nozzle is working, the remaining nozzle will be idle. The remaining molten resins inside an idle nozzle can ooze out unwantedly. The spill over from the resting nozzle produces unwanted remaining on the fabricated product. In this research, we suggest a method for optimizing building position of a model to minimize the unwanted spill-over that could possibly contaminate the final product. The method is based on minimizing the two intersection volumes. The first intersection volume is obtained by intersecting the volume defined by the first material and the Minkowski sum between the volume of the first material and the vector obtained by subtracting the center point of the first nozzle from the center point of the second nozzle. The second intersection volume can be obtained by reversing the role of the first and second volumes and nozzles. Some results obtained from the implementation using the Parasolid (Siemens) geometric modeling kernel is presented.

• Journal of Navigation and Port Research
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• v.42 no.2
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• pp.87-96
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• 2018

A trajectory control system plays an important role in controlling motions of marine vehicle when a series of way points or a path is given. In this paper, a sliding mode control (SMC)-based trajectory tracking controller for marine vehicles is presented. A small-sized unmanned ship is considered as a control object. Both speed and heading angle of a ship should be controlled for tracking control. The common point of related researches was to separate ship's speed and heading angle in control methods. In this research, a new control law from a general sliding mode theory that can be applied to MIMO (multi input multi output) system is derived and both speed and heading angle of a ship can be controlled simultaneously. The propulsion force and rudder force are also applied in modeling stage to achieve accurate simulation. Disturbance induced by wind is also tackled in the dynamics considering robustness of the proposed control scheme. In the simulation, we employed a way-point method to generate ship's trajectory and applied the proposed control scheme to ship's trajectory tracking control. Our results confirmed that the tracking error was converged to zero, thus demonstrating the effectiveness of the proposed method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.5
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• pp.833-840
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• 2015

In this paper, we are interested in a generalization of zero-knowledge interactive protocols between prover and verifier, especially to show that the product of an encrypted polynomial and a random polynomial, but published by a secure commitment scheme was correctly computed by the prover. To this end, we provide a generalized protocol for proving that the resulting polynomial is correctly computed by an encrypted polynomial and another committed polynomial. Further we show that the protocol is also secure in the random oracle model. We expect that our generalized protocol can play a role of building blocks in implementing secure multi-party computation including private set operations.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.6 s.261
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• pp.686-693
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• 2007

To perceive body movement, the nervous system uses multi-sensory cues such as vision, vestibular signals, and somatosensation. Among the multi-sensory modality, the previous researchers reported that the lower limb somatosensation plays an important role on maintaining postural balance. In this study, we examined the contribution of somatosensory cues to linear motion perception by measuring the detection threshold of the direction of linear motion with and without lower limb somatosensory constraints. Six healthy male volunteers participated in randomly ordered 33 single sinusoidal acceleration trials with the stimulus at 0.25Hz with peak magnitude ranged from 0 to 8mG. After each stimulus, subjects reported their perceived direction of motion by button press. Results showed that the reduced lower limb somatosensation significantly increased perception threshold. Without constraints, mean threshold was $0.82{\pm}0.23mG$, while it was $1.23{\pm}0.35mG$ with reduced lower limb somatosensation. The results suggest that without visual cues, perception of the movement direction strongly depends on the lower limb somatosensory information.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.17 no.30
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• pp.11-24
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• 1994

The problem of location for industries and residential quarters has undoubtedly been one of the most important factors to enhance human activities and standard of living. Nonetheless. there seem to be no such theories or approaches as to cope with this problem satisfactorily. As a matter of fact the evaluation of proposed locations so far has stuck to quantitative factors and thus the results are often rejected by the public or individuals. In deciding the location of industrial complex and/or residential quarters, the qualitative factors often play more important role than the quantitative factors. Moreover, it is quite possible for a proposed location to be disapproved for reasons other than quantifiable factors. This work presents an approach to multi-stage decision process of optimum location, particularly for residential quarters. The proposed approach consists of four stages. At the first stage, candidates for the location are searched and checked against musts. After this screening process, the candidates fulfilling the musts are evaluated both quantitatively and qualitatively at the second stage. The third stage is devoted to the integrated evaluation using diffrent weights for the two factors. At the final stage, a location is selected among the candidates evaluated at the earlier stages. This approach has been applied to and tested on a apartment-building project in Ulsan area. Difficulties arising from quantifying factors were encountered as expected. Sometimes decisions could be a matter of taste of the individuals concerned.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.116.2-116.2
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• 2012

The structure of plasmasphere plays an important role in determining properties of geomagnetic ULF pulsations such as Pi 2 pulsations and field line resonances (FLRs) in the Earth's magnetosphere. We have performed a 3-D MHD wave simulation to investigate the generation and propagation of ULF waves in dipole geometry. Various 3-D density structures are assumed, which include a relatively sharp density gradient and gradually less slopes at the plasmapause. The former condition can refer to the plasmasphere from local midnight to dawn, whereas the latter represents the region near noon to dusk where it bulges out. We show how Pi 2 pulsations and FLRs differentially appear at both multi-point satellite locations and ground stations for different local times. Our results suggest that 1) the local radial density structure significantly affects the peak frequencies for Pi 2 oscillations, while the polarization changes remain similar in the radial direction, and 2) the radial location of strong FLRs varies for different density profiles. It is also suggested how multi satellite measurements and ground-based observations can confirm this differential feature in space.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.55 no.9
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• pp.401-408
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• 2006

In a multi-sensor multi-target tracking systems, the local sensors have the role of tracking the target and transferring the measurements to the fusion center. The measurements from the same target can arrive out of sequence called the out-of-sequence measurements(OOSMs). Out-of-sequence measurements can arise at the fusion center due to communication delay and varying preprocessing time for different sensor platforms. In general, the track fusion occurs to enhance the tracking performance of the sensors using the measurements from the sensors at the fusion center. The target informations can wive at the fusion center with the clutter informations in cluttered environment. In this paper, the OOSM update step with MPDA(Most Probable Data Association) is introduced and tested in several cases with the various clutter density through the Monte Carlo simulation. The performance of the MPDA with OOSM update step is compared with the existing NN, PDA, and PDA-AI for the air target tracking in cluttered and out-of-sequence measurement environment. Simulation results show that MPDA with the OOSM has compatible root mean square errors with out-of-sequence PDA-AI filter and the MPDA is sufficient to be used in out-of-sequence environment.

• Journal of the Korean Institute of Rural Architecture
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• v.6 no.3
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• pp.1-14
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• 2004

Around the rural village area the traditional markets which are center the small capital it was active at the strong-point and the possibility the fact that it is developed. With this the same small capital currently as the city and the area where the quality of the rural village coexists, has the regional quality which belongs in guard of the capital region or strong-point city. With relative estrangement from the support process against this result past falling behind farming village it does not illustrate the possibility of knowing the fact that the duplex point who is falling behind as guard territory of reverse appears. Selects the small capital of the each area from like this point of view and the possibility of knowing center role of traditional market the possibility which is various is the possibility of doing in the process which propels an activation. Currently it is planned from the multi local self-governing group and the result which investigates the traditional market activation contents which are in the process of propelling, it will be able to discover the multi branch problem points against a traditional market activation.

• Journal of Information Processing Systems
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• v.7 no.4
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• pp.581-594
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• 2011

Due to the recent advancement of networking and high-performance computing technologies, scientists can easily access large-scale data captured by scientific measurement devices through a network, and use huge computational power harnessed on the Internet for their analyses of scientific data. However, visualization technology, which plays a role of great importance for scientists to intuitively understand the analysis results of such scientific data, is not fully utilized so that it can seamlessly benefit from recent high-performance and networking technologies. One of such visualization technologies is SAGE (Scalable Adaptive Graphics Environment), which allows people to build an arbitrarily sized tiled display wall and is expected to be applied to scientific research. In this paper, we present a multi-application controller for SAGE, which we have developed, in the hope that it will help scientists efficiently perform scientific research requiring high-performance computing and visualization. The evaluation in this paper indicates that the efficiency of completing a comparison task among multiple data is increased by our system.

• Journal of Power Electronics
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• v.3 no.4
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• pp.230-238
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• 2003

Electric vehicles (EV) demands for greater acceleration, performance and vehicle range in pure electric vehicles plus mandated requirements to further reduce emissions in hybrid electric vehicles (HEV) increase the appeal for combined on-board energy storage systems and generators. And the power electronics plays an important role in providing an interface between fuel cells (FC) and loads. This paper deals with a multiple input DC-DC power converter devoted to combine the power flowing of multi-source on energy systems. The multi-source is composed of (i) FC system as a prime power demands, (ii) super capacitor banks as energy storage devices for high and intense power demands, (iii) superconducting magnetic energy storage system (SMES), (iv) multiple input DC-DC power converter and (v) a three phase inverter-fed permanent magnet synchronous motor as a drive. In this system, It is used super capacitor banks and superconducting magnetic energy replaces from the battery system. The modeling and transient performance simulation is effective for reducing transient influence caused by sudden charge of effective load. The main purpose of power electronic converters is to convert the DC power output from the fuel cell and other to a suitable AC voltage, which can be connected to electric loads directly (PMSM). The fuel cell and other output is connected to the DC-DC converter, which regulates the DC link voltage.