• Journal of Korean Society for Geospatial Information Science
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• v.23 no.3
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• pp.41-47
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• 2015

To determine the accurate height, it should be considered geometric height difference obtained by levelling as well as the physical height difference what so called orthometric correction. The orthometric correction amount is small enough to ignore at flatland but the amount is big at high mountains, so it should be considered to obtain accurate height at high mountains. But the calculation process is difficult and complex, not easy to calculate. So, to make the process easy using a user-friendly visual, a orthometric correction calculation program Ortho-Calc. v1.0 was developed in this study. This program was adopted the algorithm of Nassar and Hwang & Hsiao, and Strang Van Hees and it could be to selectivily calculate the correction amount. The inspection result exhibited high accuracy with the standard deviation of 0.024mm by the comparison of previous study. Therefore, This program Ortho-Calc. v1.0 developed in this study, will contribute orthometric correction calculation quickly and easily. And, if this program is widely popular, it could be expected to make a contribution the Benchmark's official height renewal using orthometric correction.

• Journal of the korean academy of Pediatric Dentistry
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• v.27 no.3
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• pp.438-443
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• 2000

Ectopic eruption should be understood as a change in the course of the normal eruption path of a dental bud at any moment its origin. An example of this alteration is the dental transposition, a rare and more specific dental anomaly that may be defined as a change of position between two teeth. This case shows ectopic eruption of transposed mandibular lateral incisor beneath primary first molar at the first transitional period of the mixed dentition The crown of the lateral incisor has tipped distally, compelling root resorption and exfoliation of the adjacent primary cuspid and primary first molar. The reason for such eruption is not clearly understood, but it may involve; (1)trauma history, (2)prolonged retention of the deciduous teeth, (3)premature exfoliation of the deciduous teeth, and (4)genetic factor. Treatment is divided into interceptive and definitive treatment. Ectopically erupting mandibular incisor tends to become transposed with the adjacent cuspid and thus seems to warrant early orthodontic intervention. Early treatment may obviate later extraction or transposition of the incisor and canine in the permanent dentition. Timing is an important factor to be considered regarding in the correction of the lateral incisor transposition. This case advocates treatment with an active orthodontic therapy at the early stage of the mixed dentiton, before the eruption of the permanent cuspid.

• Journal of the Korean Association of Geographic Information Studies
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• v.24 no.2
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• pp.78-90
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• 2021

In order to construct a precision geoid, it has been diversified into land, sea, aviation, and satellite gravity measurement methods, and measurement technology has developed, making it possible to secure high-resolution, high-precision gravity data. The construction of precision geoids can be fast and conveniently decided through GNSS surveys without separate leveling, and since 2014, the National Geographic Information Institute has been developing a hybrid geoid model to improve the accuracy of height surveying based on GNSS. In this study, the results of the GNSS height measurement were compared and analyzed choosing existing public reference points to verify the GNSS height measurement of public surveys. Experiments are conducted with GNSS height measurements and analyzed precision for public reference points on coastal, border, and mountainous terrain presented as low-precision areas or expected-to-be low-precision in research reports. To verify the GNSS height measurement, the GNSS ellipsoid height of the surrounding integrated datum to be used as a base point for the GNSS height measurement at the public datum. Based on the checked integrated datum, the GNSS ellipsoid of the public datum was calculated, and the elevation was calculated using the KNGeoid18 model and compared with the results of the direct level measurement elevation. The analysis showed that the results of GNSS height measurement at public reference points in the coastal, border, and mountainous areas were satisfied with the accuracy of public level measurement in grades 3 and 4. Through this study, GNSS level measurement can be used more efficiently than existing direct level measurements depending on the height accuracy required by users, and KNGeoids 18 can also be used in various fields such as autonomous vehicles and unmanned aerial vehicles.

• Magazine of the Korean Society of Agricultural Engineers
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• v.21 no.2
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• pp.21-27
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• 1979

Canal construction is not the only area in which mechanization has advanced with great strides. All phases of the construction industry, including earthmoving, land clearing and levelling, road construction, and drainage and water control projects, have benefited from today's technological advancements. Lasers, an excellant example of advanced technology, have been refined for use as guidance systems for construction machinery, increasing accuracy and the speed of operation. The use of explosives by contractors is becoming more commonplace. One of the most valuable modern tools available today is the two-way radio. On today's sophisticated projects a single machine being down can frequently stop the progress of the entire project, delaying hundreds of men and machines from completing their assigned work for the day. The use of two-way radios in all the pickups and cars being used on a project facilitates communication so that emergency repairs can be effected immediately, and costly down time on any project can be reduced to a minimum. Not every construction project is suitable to mechanization. However, on the majority of projects mechanization has a great deal to offer the Korean contractor, and all contractors, in savings of time and money. Each and every project being considered by a contractor, should be closely examined for the most effective and efficient machinery application available. The International Commission on Irrigation and Drainage (ICID) has formed a committee on construction techniques being used in canal construction today. Two publications are now available describing the advances made in recent years. Standards for construction have been established for mechanized systems and this information is being distributed worldwide.