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1APPLICATION TO LEVELING USING TOTAL STATIONJongchool LEE and Taeho RHO, KoreaKey words: Total station, Indirect leveling method, Incidence angle, Regression analysis.ABSTRACTTotal Station are spread to many measuring sites, however, their functions are not fully understood yet. Leveling is one of the misunderstandings. The indirect leveling method using total station for leveling is considered to have due accuracy, applications of the indirect leveling is gradually expanding for public works such as construction of roads, airports and cities.Instead of direct leveling method, indirect leveling method using total station is applied in this research to assure the technicians in performing the tests, it is more economical as well.The results are expected to be used for many public works including routine survey, wide residential land development and subsidence measuring instruments.1. INTRODUCTIONAt present, Total Station has been widely spread and used in many survey sites, and sometimes it is not fully used since users misunderstand the principles of this unit. One of them is the leveling, and in case we use Total Station for leveling, this is classified as the indirect leveling method, and since it is judged that this method can maintain the considerable accuracy, now it has been increasingly used for many public works such as road, airport and city etc. This study empirically made a research in the improvement of accuracy of precise leveling by using the indirect leveling method, Total Station that can more simply and quickly find elevation by replacing the direct leveling.2. MEASUREMENT PRINCIPLE & ERROR OF EDM2.1. Measurement principle of EDMThe principle of the measurement device, EDM, which is currently used, is that it calculates the distance by measuring the phase shift during the radiated light wave from EDM's main unit returns by being reflected through the reflector, which is positioned at measurement point. This phase shift can be regarded as a part of frequency that appears as the unit of time or length under a specific condition.2Figure 1. EDM's structureWhen the slope distance L and slope angle φ is measured by EDM, if the elevation of point A is the reference point, we can find the elevation of point B by the following formula(2-1). Elevation of Point B = Elevation of Point A + HI±L sinφ - HR (2-1)Figure 2. EDM's measurement principle2.2. EDM's errorThe distance measured by EDM is expressed as the formula (2-2).2λmUS+= (2-2)Here, we have U: Phase shift of the reflected light waveλ : Wavelengthm : Number of transmitted wavelength If we measure repeatedly 2 or 3 respectively different wavelengths in order to check Value m, we can know Wavelength λ is the function of Frequency f and Electric wave’s velocity v.3fv=λ (2-3)Though electronic wave's velocity v is 299792.5km/sec the same as light velocity c under vacuum, but since it always slower than light velocity in the atmosphere, we can correct the influence by the atmosphere and calculate it by the following formula.ncv= (2-4)Here, we have n : air's refractive index. We should measure the temperature and humidity in the air according to measurement line if we try to find the exact Value n. If we substitute formula (2-4) for formula (2-3), the Value λ of the transmitted signal becomes,nfc=λ (2-5)and if we assume the wavelength under a specific atmosphere condition is 1λ, since it is described asfnc11=λ (2-6)we can express EDM's distance 1S is 21 1λmU=, and 1U can be expressed by the phaseshift of 121λ.If it is 12nnn≠= during the measurement, the corrected value of λ is,fnc22 `=λ (2-7)and at this time, the real distance S is22 2λmUS+= (2-8)From the formula (2-7) and formula (2-8), we can get21 12 `nnλλ= (2-9)and the corrected distance, that is, the correction formula of the measurement distance under a specific atmosphere condition is expressed as the following formula (2-10).21 1 21121 12nnSnnm nnUS=+=λ(2-10)In order to find the final corrected distance, we should correct the error of EDM's zero point 0Z and add Earth curvature, slope and the corrected error of average sea level S∆, and consequently the formula for the final corrected distance is as shown in the following formula (2-11).SZnnSS∆++=0 21 10(2-11)4Here, we have 1S : Measured distance1n : Refractive index when correcting in Lab2n : Refractive index at the moment of measuring If we substitute the formula (2-6) and (2-10) for (2-11), the corrected distance 0S is as follows.SZfncmnnUS∆+++=0 221 102(2-12)The variance of the distance S is as follows.22222222222200) 2() 2()2(Sznfcusfnmnfm nfm∆+++++=σσσσσσσ (2-13)And if we simply express the formula (2-13) by nfmcmS==λ2, it is described asfollows.2222222200])()()[(Sznfc usnfcS∆+++++=σσσσσσσ (2-14)Here, we have uσ : 21 1nnU, the standard deviation of the total valueEDM's accuracy is expressed as the following general formula. 2222Sbas+=σ or 222Sbas±±=σ (2-15)And if we express the formula (2-14) by the form of formula (2-15), 2a , 2b is exp。