• Journal of Institute of Control, Robotics and Systems
• /
• v.8 no.1
• /
• pp.15-20
• /
• 2002

An electro-hydraulic manipulator using hydraulic actuators has many nonlinear elements, and its parameter fluctuations are greater than those of an electrically driven manipulator. So it is relatively difficult to realize not only stable contact work but also accurate force control for the automatic assembly tasks using hydraulic manipulators. In this manuscript, we applied a compliance control, which is based on the position control by a disturbance observer for our manipulator system. A reference trajectory modification method is proposed in order to achieve accurate force control even though the stiffness and the position of the environment change. Experimental results show that highly robust force tracking by a 6-link electro-hydraulic manipulator could be achieved under various environment conditions. The proposed force control algorithm is applied to the approaching of bolt and the wrenching of nut tasks as one typical task in the maintenance work of live power electric line and is experimentally confirmed very effective for the task.

• Proceedings of the KSRS Conference
• /
• 1998.09a
• /
• pp.325-330
• /
• 1998

The first Korean remote sensing satellite, Korea Multi-Purpose Satellite (KOMPSAT-1), is going to be launched in 1999. This will carry a 7m resolution Electro-Optical Camera (EOC) for earth observation. The primary mission of the KOMPSAT-1 is to acquire stereo imagery over the Korean peninsular for the generation of 1:25,000 cartographic maps. For this mission, research is being carried out to assess the possibilities of automated or semi-automated mapping of EOC data and to develop, if necessary, such enabling tools. This paper discusses the issue of automated DEM generation from EOC data and identifies some important aspects in developing a for DEM generation system from EOC data. This paper also presents the current status of the development work for such a system. The development work has focused on sensor modelling, stereo matching and DEM interpolation techniques. The performance of the system is shown with a SPOT stereo pair. A DEM generated from a commercial software is also presented for comparison. The paper concludes that the proposed system creates preferable results to the commercial software and suggests future developments for successful generation of DEM for EOC data.

• Proceedings of the Korean Institute of Landscape Architecture Conference
• /
• 2007.10b
• /
• pp.72-77
• /
• 2007

Civic participation in managing the work of a park is a natural experience, and urban culture has a role in forming and communicating ideas. However, when it comes to managing a copse, there is no clear scenic image. In this study, my intention was to determine a desirable scene involving a copse and suggest a target image for managing work from a scenic perspective. I selected 12 photographs and listed 10 pairs of adjectives that were judged to reflect the effect produced by the copse scene using the repertory grid development technique. In addition, I performed a scenic evaluation using the semantic differential(SD) method with each pair of adjectives. Factor analysis was performed based on questionnaire survey results, such that the scenic structure of the copse had a clear definition. In addition, the physical characteristics of the photographs were analyzed using Adobe Photoshop 6.0 and the correlations between the results of the questionnaire survey were understood using multiple regression analysis. A desirable scenic image of the copse became clear through this process and I was able to suggest various options of scenic images. Taking the aspects of urban culture into consideration, park improvement projects(including their planning stages) should be implemented by involving residents, which will lead to further development of park planning and maintenance theories and projects giving due consideration to residents' opinions.

• Journal of The Korean Astronomical Society
• /
• v.35 no.3
• /
• pp.143-149
• /
• 2002

In this paper we present a methodology to derive the temporal change of the magnetic shear angle from a series of vector magnetograms, with a high time cadence. This method looks for the minimum change of the shear angle between a pair of magnetograms, free from the $180^{\circ}$ ambiguity, and then accumulates this change over many successive pairs to derive the temporal change of magnetic shear. This methodology will work well if only the successive magnetograms occurred in an active region are well aligned and its helicity sign is reasonably determined. We have applied this methodology to a set of vector magnetograms of NOAA Active Region 9661 on October 19, 2001 by the new digital magnetograph at the Big Bear Solar Observatory (BBSO). For this work we considered well aligned magnetograms whose cross-correlation values are larger than 0.95. As a result, we have confirmed the recent report of Wang et al. that there was the abrupt shear change associated with the X1.6 flare. It is also demonstrated that the shear change map can be an useful tool to highlight the local areas that experienced the abrupt shear change. Finally, we suggest that this observation should be a direct support of the emergence of sheared magnetic fields.

• English Language & Literature Teaching
• /
• v.11 no.4
• /
• pp.49-77
• /
• 2005

This paper has an aim to examine English native speakers' requests, and offer an instructional technique to develop EFL students' pragmatic ability. For this purpose, English-speaking native speakers' requests were collected in six different face-threatening situations, and analyzed in three ways: directness levels, internal modification and sequence of request. The analysis of requests showed that they were realized mainly through conventionally indirect level in most situations, were internally modified frequently through the use of downgraders, and had a certain sequence of utterances realizing a request. On the basis of these findings, two kinds of interactional activities (Jigsaw and pair work) were provided as sample activities to promote EFL students' pragmatic knowledge about the appropriate ways of making requests given the fact that pragmatic errors can be more serious and more problematic than grammatical errors in social interaction.

• 제어로봇시스템학회:학술대회논문집
• /
• 1997.10a
• /
• pp.1704-1707
• /
• 1997

In this work, position and vibratiion control of a two-link manipulator with one flexible link, which an unkoun but bounded payload mass and two pair of artificial muscle-type penumatic actuators, are investgated. A flexible link robot has advantages over a figid link robot in the sense that it is much safer when it cones into contact with its environment, including humans. Furthermore, for the sake of safety, it would be more desirabel if an actuator could deliver required force while maintaining proper compliance. An artificial muscle-type penumatic actuator is adequate for such cases. In this study, a controller based on singular perturbation method, adaptive and sliding mode contro, and .mu.-synthesis is developed. The effectiveness of the proposed control scheme is confirmed through simulations and experiments.

• Bulletin of the Korean Chemical Society
• /
• v.33 no.3
• /
• pp.1020-1028
• /
• 2012

This work compares various models for geminate reversible diffusion influenced reactions. The commonly utilized contact reactivity model (an extension of the Collins-Kimball radiation boundary condition) is augmented here by a volume reactivity model, which extends the celebrated Feynman-Kac equation for irreversible depletion within a reaction sphere. We obtain the exact analytic solution in Laplace space for an initially bound pair, which can dissociate, diffuse or undergo "sticky" recombination. We show that the same expression for the binding probability holds also for "mixed" reaction products. Two different derivations are pursued, yielding seemingly different expressions, which nevertheless coincide numerically. These binding probabilities and their Laplace transforms are compared graphically with those from the contact reactivity model and a previously suggested coarse grained approximation. Mathematically, all these Laplace transforms conform to a single generic equation, in which different reactionless Green's functions, g(s), are incorporated. In most of parameter space the sensitivity to g(s) is not large, so that the binding probabilities for the volume and contact reactivity models are rather similar.

• Proceedings of the IEEK Conference
• /
• 2003.07c
• /
• pp.2843-2846
• /
• 2003

This paper proposes a PWM(Pulse Width Modulation) circuit using CMOS OTA with a single-voltage supply. The OTA employed has an input stage which consists of a pair of two MOSFETs operating in plural operation regions. The MOSFETs work complemetarily and realize a rail-to-rail input range. The input stage requires no matching of an n-channel type input circuit and a p-channel type input circuit unlike conventional rail-to-rail input stages because the input stage is realized by single channel type MOSFETs. In order to confirm the validity of the proposed circuit, it is simulated by H-SPICE program. Futhermore, the proposed circuit will be integrated on chip using 0.35 $\mu\textrm{m}$ CMOS technology.

• Architectural research
• /
• v.9 no.1
• /
• pp.47-52
• /
• 2007

The purpose of this research is to evaluate the feasibility of outsourcing test/inspection activity in construction work. This research conducted a questionnaire of interested parties as well as a survey by Analytic Hierarchy Process (AHP) with experts on quality control. For the evaluation by AHP, five criteria were adopted and a number of pair-wise comparisons were conducted through two stages. Finally, the weighting coefficient to approve the outsourcing was calculated at 0.606 and it therefore appeared more reasonable to permit rather than prohibit outsourcing. According to the AHP result, it was found that outsourcing would be necessary to enhance the objectivity and specialties of quality testing and inspection, even though somewhat undesirable in terms of enhancing a sense of responsibility and systemically conducting the testing and inspection.

• ETRI Journal
• /
• v.36 no.3
• /
• pp.460-468
• /
• 2014

This paper addresses the problem of joint time of arrival (TOA) and direction of arrival (DOA) estimation in impulse radio ultra-wideband systems with a two-antenna receiver and links the joint estimation of TOA and DOA to the sparse representation framework. Exploiting this link, an orthogonal matching pursuit algorithm is used for TOA estimation in the two antennas, and then the DOA parameters are estimated via the difference in the TOAs between the two antennas. The proposed algorithm can work well with a single measurement vector and can pair TOA and DOA parameters. Furthermore, it has better parameter-estimation performance than traditional propagator methods, such as, estimation of signal parameters via rotational invariance techniques algorithms matrix pencil algorithms, and other new joint-estimation schemes, with one single snapshot. The simulation results verify the usefulness of the proposed algorithm.