• Journal of the Korean Society for Precision Engineering
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• v.17 no.3
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• pp.102-107
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• 2000

This study describes computer-aided design system for stepped asymmetric forgings. To establish the appropriate process sequence, an integrated approach based on a rule-base system was accomplished. This system has four modules, which are undercut prevention module, shape cognition module, 3D modelling module and corner/fillet correction module. These modules can be used independently or at all. The proposed shape cognition method could be widely used in forging design of asymmetric parts.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.263-264
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• 2008

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.1403-1405
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• 2003

This paper focuses on the image correction under few GCPs, utilizes the collinearity equation, and builds up this mathematics model of space backside resection based on condition adjustment. Then calculates the adjusted elements of exterior orientation by iteration algorithm, and evaluates the precision. And demonstrates the high-precision, affection and wide-supplying-perspective of this model.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.1
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• pp.57.5-58
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• 2015

We describe relations between modern cosmology and general relativity in the historical context. We reveal some ironies imbedded in Einstein's final correction of his gravitational field equation in the context of cosmology in 1917 which has apparently opened a new era of modern physical cosmology. The ugly (according to Einstein) correction term was introduced only to build a static cosmology which turns out to be in flat contradiction with observation. Somehow, however, it is the correction term which has saved the modern cosmology from the genuine creativity of nature continuously revealed by astronomical observations. Whether the present precision cosmology is also a correct one is often ignored by the practitioners but still a pressing open question left for future theoretical and observational pursuits.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.5
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• pp.94-101
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• 1996

When objects are scanned spatially by a laser-beam and mechanical mirror scanners, spatial information can be obtained, and then it is improtant to accurately obtain the parameters relating the light source and camera positions, etc.. In this paper, a calibration technique is presented for correction of measuremtn errors in a three-dimensional laser scanner system with two galvanometers. First, a model of the systematic errors is developed based on the geometry of the scanning system. Calibration parameter values are then iteratively adjusted with coarse-fine search in order to minimize errors (evaluation function) between measured and computed distances. It is shown that this correction method results in measurement precision suitable for practical use.

• Proceedings of the KIEE Conference
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• 2006.04a
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• pp.342-344
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• 2006

During last years, large investments have been directed to development and research of nano-technological products like semiconductor, display panel, optic-fiber communication components, life technology, and ultra-precision components. All quantitative measurements at nanometre scale should guarantees accurate results and high quality. Laser interferometer is one of most famous nanometre scale devices to be able to measure metre-scale distance with nanometre scale resolution, but it is easily affected by various error causes like geometrical, instrumental and environmental factor. On the other side, capacitive sensor is robust to above error factors, but it is able to measure relatively shorter distance, under $100{\mu}m$, than laser interferometer. New error correction method for laser interferometry using capacitive sensor will be introduced in this paper.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.1592-1596
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• 2007

Accuracy of flood forecasting is an important non-structural measure on the flood control and mitigation. Hence, combination of horologic model with real time error correction became an important issue. It is one of the efficient ways to improve the forecasting precision. In this work, an approach based on Kalman Filter (KF) is proposed to continuously revise state estimates to promote the accuracy of flood forecasting results. The case study refers to the Wi River in Korea, with the flood forecasting results of Xinanjiang model. Compared to the results, the corrected results based on the Kalman filter are more accurate. It proved that this method can take good effect on hydrologic forecasting of Wi River, Korea, although there are also flood peak discharge and flood reach time biases. The average determined coefficient and the peak discharge are quite improved, with the determined coefficient exceeding 0.95 for every year.

• Journal of the Korea Institute of Military Science and Technology
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• v.11 no.4
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• pp.5-12
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• 2008

There are some ways to improve precision of conventional munitions by low-cost method. 2D Course Correction Munition(CCM) is one of those ways, which is a 155mm projectile integrated with 2D Guidance Fuze(GF) instead of conventional fuze. 2D GF can correct the projectile trajectory and minimize range and deflection errors from its aimpoint using canard control. In this paper 2D CCM system concept is introduced and its course correction capability is analyzed using PRODAS.

• The KIPS Transactions:PartD
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• v.18D no.1
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• pp.67-80
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• 2011

On an automated business document processing system maintaining financial data, errors on query based retrieval of numbers are critical to overall performance and usability of the system. Automatic spelling correction methods have been emerged and have played important role in development of information retrieval system. However scope of the methods was limited to the symbols, for example alphabetic letter strings, which can be reserved in the form of trainable templates or custom dictionary. On the other hand, numbers, a sequence of digits, are not the objects that can be reserved into a dictionary but a pure markov sequence. In this paper we proposed a new OCR model for spelling correction for numbers using the multiple streams and the context based correction on top of probabilistic information retrieval framework. We implemented the proposed error correction model as a sub-module and integrated into an existing automated invoice document processing system. We also presented the comparative test results that indicated significant enhancement of overall precision of the system by our model.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.12
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• pp.3115-3123
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• 1993

This paper presents a real-time correction method of the movemont errors of a translatory precision machine axis. This method is a null-balances technique in which two plane mirrors are used to generate an interferometric fringe pattern utilizing the optical principles of TwymanGreen interferometry. One mirror is fixed on a reference frame, while the other is placed on the machine axis being supported by three piezoelectric actuators. From the fringe pattern, one translatory and two rotational error components of the machine axis are simultaneously detected by using CCD camera vision and image processing techniques. These errors are then independently suppressed by activating the peizoelectric actuators by real-time feedback control while the machine axis is moving. Experimental results demonstrate that a machine axis can be controlled with movement errors less than 10 nm in vertical straightness, 0.1 arcsec in pitch, and 0.06 arcsec in roll for 50mm travel by adopting the real-time correction method.