• 대한치과의사협회지
• /
• 제47권7호
• /
• pp.444-454
• /
• 2009

The purpose of this study was to compare the shaping abilities of LightSpeed, ProTaper-Universal, and hybrid technique using S-series of ProTaper-Universal and LigthSpeed. The 72 simulated root canals of J-shape were used and classified as flowing 3 groups according to the instrumentation methods; Group P of 24 canal blocks were prepared with ProTaper-Universal, Group L was prepared with LightSpeed, and Group H was prepared with hybrid technique (initial shaping with ProTaper-Universal SI and S2 and apical shaping with LightSpeed from #25 to #50). A second-year resident of Endodontic department prepared the resin block canals to apical size #50 (F5 in Group P). The time lapses for instrumentation and the reduction of root canal curvature after shaping were measured. The pre- and post-instrumented root canals were scanned and superimposed to evaluate and calculate the increased canal width and apical centering ratio. The results were as followings: Group Land H showed significant less instrumentation time than Group P (p < 0.05). The ProTaper system showed greater reduction of root canal curvature and working length diminishment than other methods (p < 0.05). LightSpeed system showed best canal curvature preserving characteristics. The Group P had greater instrumented widths at all levels examined (p < 0.05). Group L and Group H showed lower centering ratio (ability to preserve the canal center; the lower ratio means the better canal center preservation) than Group P (p < 0.05). Group H had the lowest centering ratio at the 1 mm level.

• 한국디자인학회:학술대회논문집
• /
• 한국디자인학회 2004년도 추계 학술발표대회 논문집
• /
• pp.184-185
• /
• 2004

• 한국방송∙미디어공학회:학술대회논문집
• /
• 한국방송공학회 1996년도 학술대회
• /
• pp.147-151
• /
• 1996

This paper describes two traffic shaping methods for VBR(variable bit rate) video bit streams encoded in the MPEG-2 syntax. Difficulties in control of VBR video traffic are lessened by traffic shaping. Burstness of single layer MPEG-2 video can be reduced by performing intra-refresh in more than one consecutive frames. In two layer encoding of spatial scalability, burstness can be reduced by setting the temporal locations of GOP starting frame of a layer, differently from the other. Queueing analysis shows that these two methods outperform conventional encoding schemes in terms of temporal and semantic QoS requirements.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2003년도 ICCAS
• /
• pp.428-432
• /
• 2003

Quantitative Feedback Theory (QFT) is one of most effective methods of robust controller design and can be considered as a suitable method for systems with parametric uncertainties. Particularly it allows us to obtain controllers less conservative than other methods like $H_{\infty}$ and ${\mu}$-synthesis. In QFT method, we transform all the uncertainties and desired specifications to some boundaries in Nichols chart and then we have to find the nominal loop transfer function such that satisfies the boundaries and has the minimum high frequency gain. The major drawback of the QFT method is that there is no effective and useful method for finding this nominal loop transfer function. The usual approach to this problem involves loop-shaping in the Nichols chart by manipulating the poles and zeros of the nominal loop transfer function. This process now aided by recently developed computer aided design tools proceeds by trial and error and its success often depends heavily on the experience of the loop-shaper. Thus for the novice and First time QFT user, there is a genuine need for an automatic loop-shaping tool to generate a first-cut solution. In this paper, we approach the automatic QFT loop-shaping problem by using an algorithm involving Linear Programming (LP) techniques and Genetic Algorithm (GA).

• 대한기계학회논문집A
• /
• 제31권11호
• /
• pp.1053-1058
• /
• 2007

Micro-EDM technology (or the manufacture of miniature parts is used to make a micro hole. Two electrode shaping methods, mechanical electrode grinding and WEDG technique, have been studied. In this study, an electrode shaping method by using previously machined hole is introduced in order to obtain an optimal hole-making condition. Key factors such as applied voltage, capacitance, feedrate, and hole-dimension have an influence on the fabricating error of electrode shaping, which are taper ratio of a hole, electrode form accuracy, and electrode surface. Therefore, we try to investigate the optimal fabricating of electrode shaping from various experiments. Results from experiments, it was able to minimize the electrode fabricating error as voltage increases, and also applied feedrate and capacitance decreases.

• 한국산업융합학회 논문집
• /
• 제2권1호
• /
• pp.53-59
• /
• 1999

Input shaping technique has been used as a simple method of controlling vibration. With the conventional methods previously proposed by several authors, the frequency range that shows a good performance is restricted. When the designed frequency being different from the natural frequency of a system, the performance of control degrades remarkably. This paper introduced a new technique that uses digital IIR filter to control vibration. This technique has robustness for changing of parameter. In order to prove this we applied input shaping method to 2 axial overhead crane.

• 제어로봇시스템학회논문지
• /
• 제5권8호
• /
• pp.883-888
• /
• 1999

To obtain high positioning auccuracy for a long, flex bleman Ipulator, residual vibration must be removed from the tip motion. But it is difficult to control the vibration of low frequency. There are open-loop and closed loop methods in the elimination of the residual vibration. We inroduce input shaping technique has been used as a simple open-loop method of controlling the residual vibration of a flexible manipulator. Design of input shaper in the continuous time domain is complicated. This paper presents a new technique that designs input shaper in the z-domain and analyzes input shaping method in the z-domain. This technique is simple and easy to design input shaper.

• 한국정밀공학회지
• /
• 제16권4호통권97호
• /
• pp.155-162
• /
• 1999

Input shaping technique has been used as a simple method of controlling the residual vibration of a flexible manipulator. With the conventional methods previously proposed by several authors, the frequency range that shows a good performance is restricted. When the designed frequency being different from the natural frequency of a system, the performance of control degrades remarkably. This paper introduced a new technique that designs input shaping with robustness in the z-domain.

• 한국항공운항학회지
• /
• 제14권4호
• /
• pp.31-37
• /
• 2006

In this paper, an experimental study on the robust input shaping for control of the residual vibration of flexible structures has been investigated. Two approaches has been used for the robustness of input shaping: the first method is to increase the number of impulses, and the other includes an EI shaper using vector diagram. The input case designed by the application of the above methods has been applied to a control problem involving residual vibration of a rotating hub with two flexible appendages. It has been found by a series of experiments that the input shaper designed in this paper works well for the residual vibration control of the flexible structure.

• 대한인간공학회:학술대회논문집
• /
• 대한인간공학회 1995년도 춘계학술대회논문집
• /
• pp.30-34
• /
• 1995

The operator's performance of nuclear power plants is affected by many performance shaping factors(PSF). The objective of this study is to find out the PSFs and their effect on the nuclear power plant operations. We extracted PSFs in five category, and identified the relationships between PSFs and performance using the four survey methods; literture survey, case study, video task analysis and questionnaire survey. Finally the knowledge on PSFs and their effect was represented as rule form for cognitive simulation.