• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.10 s.352
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• pp.80-89
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• 2006

The rapid development of process technology and the introduction of new materials not only make it difficult for process control but also as a result increase process variations. These process variations are barriers to successful implementation of design circuits because there are disparities between data on layout and that on wafer. This paper proposes a new design environment to determine the interconnect worstcase with accuracy and speed so that the interconnect effects due to process-induced variations can be applied to designs of $0.13{\mu}m$ and below. Common Geometry and Maximum Probability methods have been developed and integrated into the new worstcase optimization algorithm. The delay time of the 31-stage Ring Oscillator, manufactured in UMC $0.13{\mu}m$ Logic, was measured, and the results proved the accuracy of the algorithm. When the algorithm was used to optimize worstcase determination, the relative error was less than 1.00%, two times more accurate than the conventional methods. Furthermore, the new worstcase design environment improved optimization speed by 32.01% compared to that of conventional worstcase optimizers. Moreover, the new worstcitse design environment accurately predicted the worstcase of non-normal distribution which conventional methods cannot do well.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.28 no.2
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• pp.247-254
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• 2010

In this paper, a new approach has been studied correcting the geometric distortion of SPOT 4 imagery. Two new equations were induced by the relationship between satellite and the Earth in the space. line-of-sight (LOS) vector adjustment model for SPOT 4 imagery was implemented in this study. This model is to adjust LOS vector under the assumption that the orbital information of satellite provided by receiving station is uncertain and this uncertainty makes a constant error over the image. This model is verified using SPOT 4 satellite image with high look angle and thirty five ground points, which include 10 GCPs(Ground Control Points) and 25 check points, measured by the GPS. In total thirty five points, the geometry of satellite image calculated by given satellite information(such as satellite position, velocity, attitude and look angles, etc) from SPOT 4 satellite image was distorted with a constant error. Through out the study, it was confirmed that the LOS vector adjustment model was able to be applied to SPOT4 satellite image. Using this model, RMSEs (Root Mean Square Errors) of twenty five check points taken by increasing the number of GCPs from two to ten were less than one pixel. As a result, LOS vector adjustment model could efficiently correct the geometry of SPOT4 images with only two GCPs. This method also is expected to get good results for the different satellite images that are similar to the geometry of SPOT images.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.162-168
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• 2008

Recently surround molding parts using stainless steel are applied to international and domestic high grade vehicles, but there are great difficulties in die manufacture because of springback and twist after forming process. To solve this problem, finding the method of reduction springback is very important. In this study the springback which might happen during making a die that produce stainless steel surround molding parts is predicted and the geometry of die which satisfy the tolerance between product and panel after forming and springback will be suggested using automatic die compensation module.

• Journal of Ship and Ocean Technology
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• v.6 no.3
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• pp.37-45
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• 2002

A series of detailed study was performed to identify the sources of the propeller blade failure and resolve the problem systematically, by use of the theoretical tools and by the direct measurement and observation in the full-scale sea trials. The selection of inexperienced propulsion control system with a reversible gear system is shown to cause the serious damage to the propeller blades in crash astern maneuver, when the rotational direction of the propeller is changed rapidly. Quasi-steady analysis for propeller blade strength using FEM code in bollard backing condition indicates that the safety factor should be order of 18∼20 to avoid the structural failure for the selected propeller geometry and reduction gear system.

• Journal of the korean Society of Automotive Engineers
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• v.7 no.2
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• pp.55-63
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• 1985

This study is focused on deposition process leading to inefficiency and hot corrosion in fossil fuel-fired furnaces and engines. An improved understanding of the coupled thermodynamics, kinetics, and transport processes governing the deposition rate of inorganic oxides and salts from hot gases containing these compounds can suggest more efficient test strategies and control measures. Accordingly, an optical re-evaporation method for accurately measuring the growth rate of deposits under laboratory burner conditions has been developed. To demonstrate the technique and provide data suitable for theoretical model development, a deliberately simple chemical system and target geometry are used. Potassium sulfate(K$_{2}$SO$_{4}$)is introduced into a premixed propane-air flat flame at atmospheric pressure. The growth rate of $K_{2}$SO$_{4}$ on an electrically heated Pt ribbon is measured by re-evaporation technique.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2007.04a
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• pp.135-140
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• 2007

Due to the expensiveness of IKONOS Pro and Precision Products, it is attractive to use the low-cost IKONOS Geo Product with vendor-provided RPCs to produce highly accurate mapping products. The imaging geometry of IKONOS high-resolution imagery is described by RFs instead of rigorous sensor models. This paper presents four different models defined respectively in object space and image space to improve the accuracies of the RF-derived ground coordinates. The four models include the offset model, the scale & offset model, the affine model and the 2nd-order polynomial model. Different configurations of ground control points (GCPs) are carefully examined to evaluate the effect of the GCPs arrangement on the accuracy of ground coordinates. The experiment also evaluates the effect of different cartographic parameters such as the number location, and accuracy of GCPs on the accuracy of geopositioning.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1999.06a
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• pp.197-202
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• 1999

A mechanical face seal is a tribe-element intended to control the leakage of working fluid at the interface of a rotating shaft and its housing. The leakage of working fluid decreases as the seal surfaces get closer each other. But a very small seal clearance results in a drastic reduction of seal life because of high wear and heat generation. Therefore, in the design of mechanical face seals the compromise between low leakage and acceptable life is important and presents a difficult design problem. And the gap geometry of seal clearance affects seal performance very much and becomes an important design variable. In this study the Reynolds equation for the sealing dam of mechanical face seals is numerically analyzed using the Galerkin Finite Element Method, which can be readily applied to various seal geometries. The film pressures of the sealing dam are analyzed, including the effects of the seal face coning and tilt. Then, opening forces, restoring moments, leakages, and dynamic coefficients are calculated.

• Research in Mathematical Education
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• v.17 no.2
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• pp.99-118
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• 2013

The present study focuses on the contribution of a teaching unit to the development of spatial ability of third graders in general and from a gender point of view in particular. The research population consisted of seventy-four pupils: thirty-seven pupils in the experimental group who attended the teaching unit and thirty-seven pupils in the control group. The spatial ability of all the pupils was examined by means of common tests which checked cognitive capabilities of spatial ability. The research findings illustrate an improvement in the spatial ability of the experimental group pupils following the participation in the teaching unit. Moreover, regarding the gender aspect, the findings show that there was no significant differentiation between the spatial ability of third grade boys and the spatial ability of girls of the same age group.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.1407-1410
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• 1997

Advanced sensor design and filtering technology have been studied to obtain information for condition monitoring and diagnostics inmachining processes. To develope and economic monitoring system in end milling processes, indirect and reliable type of cutting force estimators were required. In this paper, an estimation method of cutting forces during end milling processes was studied through the measurement of current signals obtained from spindle and feeddrive motors. Cutting force and torque models were derived from the cutting geometry in down milling processes. Relationships between motor currents and cutting forces were also developed in the form of AC and DC components from the developed force models. The validity of the cutting force estimator was confirmed by the experiments under various cutting conditions.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.1342-1347
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• 1997

In this paper, we performed simulations of aircraft automatic landing using GPS, DGPS and CDGPS. Our purpose is examining the possibility of aircraft landing using GPS through the simulation results. The aircraft landing is composed of two stages, glide-slope and flare. Therefore, LQG controllers are designed separately. In simulations, measurement noise depends not only on UERE and UERRE(which have different values in GPS, DGPS, and CDGPS) but also on DOPs. DOPs are determined only by the geometry of GPS satellite constellation. For DOP calculation, we also made program for GPS satellites orbit simulatiion. Accordin to the simulation results, ICAO CAT III can be achieved of CDGPS is used.