• Vacuum Magazine
• /
• v.3 no.4
• /
• pp.19-23
• /
• 2016

Angle resolved photoemission spectroscopy (ARPES) is a powerful technique which can directly visualize the electronic structure of solid in detail including many-body interaction information. However, ARPES has a certain limitation in applying control parameters such as doping or pressure, which helps to dig out the clue to understand the desired phenomena or the target system. During ARPES experiment, the control parameter is the temperature only. Other parameters especially electric- and magnetic- field cannot be applied. Recently introduced surface-electron doping technique highlights new avenue to overcome such limitation. In this article, starting from introducing basic concepts of ARPES and its current status, the power of new technique will be demonstrated when it is combined to ARPES by introducing recent results on iron based superconductors.

• Journal of Institute of Control, Robotics and Systems
• /
• v.11 no.11
• /
• pp.907-912
• /
• 2005

In this paper, we consider the problem of designing sliding surfaces fur a class of dynamic systems with mismatched uncertainties in the state space model. In terms of LMIs, we give necessary and sufficient conditions fir the existence of a linear sliding surface such that the reduced order sliding mode dynamics is asymptotically stable and completely independent of uncertainties. We parameterize all such linear sliding surfaces by using the solution to the given LMI conditions. And, we consider the problem of designing linear sliding surfaces guaranteeing pole placement constraints or $H_2/H_infty$ performances. Finally, we give a design example in order to show the effectiveness of our method.

• 제어로봇시스템학회:학술대회논문집
• /
• 1991.10a
• /
• pp.252-257
• /
• 1991

This paper proposed that the eddy-current measurement method can be used a means of in-process measuring the hardening depth in Laser surface treatment process. Also, this paper deal with the numerical analysis of magnetic flux distribution and experimental result of measurement. In Laser heat treatment process of steels, a thin layer of the substrate is rapidly heated to austenitizing temperature and subsequently cooled at a very fast rate due to the self-quenching by heat conduction into the bulk body, to produce a martensite structure which have low magnetic permeability. The eddy-current measurement method depends on the properties of material to be measured such as electric conductivity, magnetic permeability and geometry. In this paper, the hardening depth was measured by detecting relevant magnetic permeability changes caused by heat treatment of steels.

• Proceedings of the KIEE Conference
• /
• 2008.07a
• /
• pp.1683-1684
• /
• 2008

In this paper, a hierarchical nonsingular terminal sliding mode controller (TSMC) for overhead crane system using nonsingular terminal sliding surface (NTSS) is proposed, which can drive the error to zero in a finite time. Here, singular problem of controller is solved by NTSS. In addition, the controller has the double layer structure because the system is divided into two hierarchical subsystems. In the first layer, the nonsingular terminal sliding surfaces are hierarchically designed for each subsystem, and in the second layer, the whole sliding surface is designed as the linear combination of nonsingular terminal sliding surfaces. The asymptotic stability of the system is verified by Lyapunov analysis. Finally, we carry out simulations on the overhead crane system to illustrate the effectiveness of the proposed control method.

• The Journal of Korea Robotics Society
• /
• v.11 no.4
• /
• pp.217-225
• /
• 2016

Dynamic Positioning (DP) is used to automatically maintain the position and heading of a floating structure subjected to environmental disturbances. A DP control system is composed of a motion controller to compute the desired force and moment and a thrust allocator to distribute the computed force and moment to multiple thrusters considering mechanical and operational constraints. Among various thruster configurations, azimuth thrusters or propeller/rudder pairs tend to make the allocation problem difficult to solve, because these types of propulsion systems include nonlinear constraints. In this paper, a dynamic positioning strategy for a twin-thruster ship that is propelled by two azimuthing thrusters is addressed, and a thrust allocation method which does not require a numerical optimization solver is proposed. The applicability of the proposed method is demonstrated with an experiment using an autonomous boat.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.60 no.4
• /
• pp.843-847
• /
• 2011

In this note, a proof of Utkin's theorem is presented for the SI(Single Input) uncertain integral linear case. The invariance theorem with respect to the two transformation methods so called the two diagonalization methods are proved clearly and comparatively for SI uncertain integral linear systems. With respect to the sliding surface transformation, the equation of the sliding mode, the sliding surface is invariant. Both the applied control inputs have the same gains. By means of the two transformation methods the same results can be obtained. Through an illustrative example and simulation study, the usefulness of the main results is verified.

• 제어로봇시스템학회:학술대회논문집
• /
• 2001.10a
• /
• pp.28.2-28
• /
• 2001

Three dimensional shape measurement techniques are widely needed in industries for product quality monitoring and control. X-ray imaging method is a promising technology to achieve three-dimensional Information, both the surface and inner structure of an object, since it can overcome the limitations of conventional visual or optical methods such as an occlusion problem or surface reflection properties. In this paper, we propose three dimensional volume reconstruction method based on x-ray stereo imaging technology. Here, the stereo images of an object from two different views are taken by changing the object pose rather than moving imaging plane as in conventional stereo vision method. We propose a series of image processing techniques to extract the features efficiently from x-ray images, where the occluded features in case of normal camera vision could be found ...

• Journal of Korean Society on Water Environment
• /
• v.28 no.1
• /
• pp.137-147
• /
• 2012

Land surface temperature in ecohydrology is a variable that links surface structure to soil processes and yet its spatial prediction across landscapes with variable surface structure is poorly understood. And there are an insufficient number of soil temperature monitoring stations. In this study, a grid-based land surface temperature prediction model is proposed. Target sites are Andong and Namgang dam region. The proposed model is run in the following way. At first, geo-referenced site specific air temperatures are estimated using a kriging technique from data collected from 60 point weather stations. Then surface soil temperature is computed from the estimated geo-referenced site-specific air temperature and normalized difference vegetation index. After the model is calibrated with data collected from observed remote-sensed soil temperature, a soil temperature map is prepared based on the predictions of the model for each geo-referenced site. The daily and monthly simulated soil temperature shows that the proposed model is useful for reproducing observed soil temperature. Soil temperatures at 30 and 50 cm of soil depth are also well simulated.

• The Journal of Korean Academy of Prosthodontics
• /
• v.33 no.4
• /
• pp.693-704
• /
• 1995

This study was performed to evaluate effective surface conditioning method of In-Ceram core to improve bonding with resin cement. The surface of each sample was avraded with glass bead for 20 seconds and then subjected to one of the following conditions : no modification, sandblasting with $50{\mu}m$ slumimum oxide powders for 20 seconds, etching with 20% hydrofluoric acid for 5, 10, and 15 minutes(half of the etched samples were coated with silane), and sandblasting with $250{\mu}m$ aluminum oxide powders and silica coating whith Silicoater MD system(Kulzer, Germany). The surface morphology changes were examined with scanning electronic microscope(SEM. and the shear bond strength of In-Ceram core samples to resin cement(Panavis 21, Kurayay, Japan) were measured. It was concluded that : 1. By SEM observation, 20% HF acid etching did not create clear microretentive structure and surface roughness diminished with increace in etching time. Sandblasting was more effective than 20% hydrofluoric acid etching in producing microretentive structure. 2. The bond strengths of all In-Ceram core samples surface conditioned were increased that that of control group. 3. Silica coating showed higher bond strength than etching with 20% hydrofluoric acid. 4. The use of silane coating was more effective in improving bond strength than lengthening etching time.

• Proceedings of the Korean Fiber Society Conference
• /
• 2003.10a
• /
• pp.100-100
• /
• 2003

An image processing algorithm has been developed in order to analyze the nanofiber web images obtained from a high magnification microscope. It has been known that precise pore detection on thick webs is extremely difficult mainly due to lack of light uniformity, difficulty of fine focusing and translucency of nanofiber web. The pore detection algorithm developed has been found to show excellent performance in characterizing the porous structure, thus being a promising tool for on-line quality control system under mass production. Since the images obtained from an optical microscope represent only web surface, a scale factor has been introduced to estimate the web structure as a whole. Resulting web structures have been compared to those by mercury porosimetry, especially in pore size distribution. It has been shown that those two structures have a strong correlation, indicating that scaling of a single layer web structure can be an effective way of estimating the structure of thick fiber webs.