• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.7 no.1
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• pp.11-18
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• 1989

Observations to precise levelling nets contain different types of error because it has been caried out with various instruments and techniques, and also completed through long period. In order to establish a precise levelling nets, therefore, the weight function has to be selected adequately in the adjustment of nets. The purpose of the study is to determine a suitable weight function for the first order geodetic levelling nets in Korea and, therefore, the various numerical tests are performed with different statistical error models. The result of the study shows that the weight function, W＝1/$L^2$ is more efficient than W＝1/L in the first order levelling nets in the Korea.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2004.04a
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• pp.51-55
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• 2004

In this study, the levelling and the GPS levelling were carried out with 6 points in 2km${\times}$2km area and the results were analysed. As a result of this research, we had to observe more than 15 minutes to get the height accuracy of 10mm by single frequency GPS receiver in relative surveying. We could not get more better accuracy than 10mm. we could get the height accuracy of within 10mm from observing only more than 5 minutes by double frequency GPS receiver, and of within about 3mm from observing more than 10 minutes. When the number of fixed points is within 3, the level net adjustment result is very close to the one of direct levelling survey. When the number of fixed points is 3, the less the area of triangle the better the adjustment result, and the case of including measure point has more better accuracy than that of non-including measure point.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2004.04a
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• pp.3-8
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• 2004

This study describes the validation of the GPS/Levelling using GPS data that were obtained from three Permanent GPS stations of the Jeju island. Each orthometric height of three Permanent GPS stations was calculated from the Bench mark of levelling with Traverse-survey and relative baseline processing The test result shows that the error of closure of orthometric height was about 1.6cm and one of ellipsoidal height was about 1.5cm. This result represents that the geoidal height and undulations are regular in the Jeju island. According to the test results, it is identified that one can calculate the orthometric height using Permanent GPS station data rather than traditional levelling method which has a some complexity especially in Jeju island.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2007.04a
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• pp.89-92
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• 2007

This investigation aims at calculating the geoid height, distance between the ellipsoidal height and the orthometric height by GPS/Levelling data for nationwide 58 Bench Marks, and calculating the effect of geoid height to engineering public works. The accuracy of the results from baseline analyses and adjustment of a network. using GPS surveying data by nationwide 58 BM show 4mm for horizontal direction and 7cm for vertical direction. The 58 geoid height was calculated by GPS/Levelling. For a construction work field GPS/Levelling for distributed 4 BM in test area can calculate the orthometric height in 20 ppm relativity accuracy with 95% reliability. Besides the calculated geoid height in the investigation was 0.367m higher than EGM96 model. The test results of a engineering work site, the result by EGM96 model was 1.8cm in 10km and it was also 3.6cm in interpolation method. The results show that it is equivalent to levelling of $20mm\sqrt{S}$.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2002.05a
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• pp.25-28
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• 2002

This paper is concerned with the design of roller profiles in tube/pipe straightener with both methods of Computer Aided Design and Computer Aided Engineering. Design analysis is carried out from two point of view. The one is the research in the minimization of tube pitch which was very important factor in levelling process. In order to minimize tube pitch, profiles of the roller were calculated so that the contact region between roller and tube was maximized. The other is determination of an optimum amount of intermesh for the proper progress without a jam in levelling process. Generally the jamming trouble was casued by excessive amount of intermesh in levelling process. The optimum amount of intermesh was determined through the finite element analysis.

• Geophysics and Geophysical Exploration
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• v.17 no.3
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• pp.171-178
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• 2014

Aeromagnetic survey generally require much more pre-processing steps than that of common land survey due to several complex and cumbersome steps included in pre-processing stage. Therefore it is desirable to use specific processing tool especially based on graphic user interface. For this purpose, aeromagnetic pre-processing software based on graphic user interface under the Windows environment, called $KMagLevelling^{TM}$ was developed and briefly introduced. In an aspect of its user-friendliness and originality, three noticeable features of $KMagLevelling^{TM}$ are summarized as the following (1) function of representation and handling for large amount of aeromagnetic data set as a visualization in the form of flight-path (2) function of selective exclusion of unwanted data by using survey area information expressed as polygon, and (3) function of selective removal processing for the irregular flight-path data acquired within the entire survey area by implementing the segmentation of flight-path technique.

• Transactions of Materials Processing
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• v.11 no.2
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• pp.138-146
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• 2002

This paper is concerned with the simulation-based process design method involved non-steady state problem of tension levelling considering the elasto-plastic hardening behavior of a metallic strip by a commercial code ABAQUS/Standard. The tension levelling process is peformed to elongate the strip plastically in combination of tensile and bending strain by a controlled manner so that all longitudinal fibers in the strip have an approximately equal amount of length and undesirable strip shapes are corrected to the flat share. Objectives of this paper are the development of a general method for the design of a tension leveller by a finite element method and parameter studies for the deisgn variables such as the applied tension, the roll intermash includes the determination of the steady state using the simple unit of the tension levelling line and the effect of the finite element mesh size on the amount and distribution of the strain calculated. The analysis provides the information about the intermesh effect on the amount and final shapes of the strip and distribution of the strain in order to determine the amount elongation for correction of the irregular share.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2000.10a
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• pp.42-48
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• 2000

This paper is concerned with a simulation-based process design for the tension levelling of metallic strips based on the elasto-plastic finite element analysis with reduced integration and hourglass control. The tension levelling process is performed to elongate the strip plastically in combination of tensile and bending strain by a controlled manner so that all longitudinal fibers in the strip have an approximately equal amount of length and undesirable strip shapes are corrected to the flat shape. The analysis deals with a method for calculating the quantitative level of the curl to investigate the roll arrangements and intermesh suitable to elimination of the curl. The analysis provides the information about the intermesh effect on the amount, the tension effect and distribution of the strain as well as the stress in order to determine the amount of elongation for correction of the irregular shape. The desired elongation is referred to determine the number of work rolls and the value of tension. Especially, the analysis investigates tile effect of the mesh size in the non-steady state finite element analysis on the amount and distribution of the strain.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.23 no.4
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• pp.385-392
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• 2005

This paper describes an accuracy analysis of newly developed gravimetric geoid and an improvement of developed geoid using GPS/Levelling data. We developed the KGEOID05 model corrected with the correction term. The correction term is modelled using the difference between GPS/Levelling derived geoidal heights and gravimetric geoidal heights. The stochastic model used in the calculation of correction term is the least squares collocation technique based on second-order Markov covariance function. 373 GPS stations were used to model the correction term. The standard deviation of KGEOID05 is about 11 cm and it indicates that we can be determined accurate heights ($2{\sim}3\;cm$) when we made precise modelling using KGEOID05 and a few GPS measurements for the local area.

• The Research Journal of the Costume Culture
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• v.11 no.3
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• pp.416-422
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• 2003

Agricultural drainage salt generated during irrigation of crops in San Joaquin Valley, California, exceeds 600,000 tons annually and cumulates in the field in a rapid rate. As a result, the waste is taking out more farmlands for salt storage and disposal, imposing serious concerns to environment and local agricultural industry. In searching for a potential solution to reduce or eliminate the waste, this research explored feasibility of producing a value-added product, sodium sulfate, from the waste and utilizing the product in textile dyeing. The results indicated that sodium sulfate could be produced from the salt and could be purified by a recrystalization method in a temperature range within the highest and lowest daily temperatures in summer in the valley. The recovered sodium sulfate samples, with purities ranging from 67% to 99.91, were compared with commercially available sodium sulfate in the dyeing of levelling dyes with nylon/wool fabrics. In nylon/wool fabrics, C.I. Acid Yellow 23 had similar exhaustions among Na₂SO₄ I, Na₂SO₄ II, Na₂SO₄ III and Na₂SO₄ Ⅴ which had similar ratios of sodium sulfate and sodium chloride in recovered salts. Na₂SO₄ Ⅳ had low exhaustion which had low ratios of sodium sulfate and sodium chloride. In nylon/wool fabrics, C.I. Acid Blue 158 had similar exhaustions among Na₂SO₄ I, Na₂SO₄ II, Na2₂SO₄ III, Na₂SO₄ IV and Na₂SO₄ Ⅴ despite of Na₂SO₄ Ⅳ had low ratios of sodium sulfate and sodium chloride Generally, the dyeing of levelling dyes using recovered salts from farm drainage has similar or low exhaustion than the dyeing of levelling dyes using commercial sodium sulfate.