• Proceedings of the Korean Institute of Building Construction Conference
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• 2009.05b
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• pp.101-106
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• 2009

We study on the segregation reduction effect of Self-Leveling Color Mortar by using variable composition set of plasticizer and thickener, Naphthalene, melamine and polycarbonate-based dispersants were employed as plasticizers for examining on fluidity of mortar mixtures. For enhancement of mortar stability without loss of it's fluidity, two types of thickener were used such as polysaccharide(PS) and hydroxyethylcellulose(HEC). As a result, the most effective mortar was composed by feeding 0.519% of polycarbonate-based dispersant with 0.002587% of PS and 0.155844% of HEC on amount of basic mortar.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.1 no.2
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• pp.30-41
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• 1983

This study aims at carrying out the precision leveling by getting the coeicffients of refraction (K) through experiment presented necessarily in the zenith distance measurements of trigonometrical leveling. Thus, the process and characteristics of seasonal and hourly variation of the coefficients of refraction (K) in the Honan district are presented in this paper, especially in the mountainous area surrounded with the Mt. Mudeung, in the coastal area of Mokpo and Yeosu district, and in the plain area of Gwangju district.

• Journal of Surface Science and Engineering
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• v.52 no.5
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• pp.239-245
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• 2019

To increase the throughput of tip-based nanolithography (TBN), one approach is to use a large array of such tips working in parallel. It is important to maintain co-planarity between the tip array and the writing surface. A slight misalignment can cause large discrepancies of contact force and feature sizes. We report a capacitive proximity sensor built-in with the TBN array for leveling an arrayed polymer pen array. The device allows alignment between an array of writing tips and the writing substrate without contact and contamination. The angular sensitivity of the sensor is $0.05^{\circ}$ for an array with maximum tip-to-tip separation of 100 mm.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.29 no.4
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• pp.393-403
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• 2011

In this study, we suggested the period of tide observations is proper to calculate the mean sea level(MSL) precisely on Incheon tide station using wavelet analysis, and newly determined then the vertical reference surface of Korea using the calculated MSL. In order to calculate the height difference between the calculated MSL and specific ground station (ICGP) near the Incheon tide stations, we performed the laser measurements directly to the sea surface where located below ICGP. The orthometric-height of ICGP was determined that corrected the height difference to the calculated MSL using linear interpolation method. Finally, we connected the orthometric-height of ICGP with the original benchmark (ORBM) using GPS leveling methods for determining the new orthometric-height of ORBM. As the results, there is a variation amount of 0.026m between the new MSL was calculated in this study and old MSL was calculated in 1910's. Also, there is a difference of 0.035m between the new and old orthometric-heights of ORBM. The connection (or leveling) error of 0.009m was revealed in new orthometric height of ORBM with consideration of MSL variation which may caused by the error of GPS ellipsoid height and/or geoid model. In this study, we could be determined precisely the orthometric-height of ORBM based on the new MSL of Incheon Bay using only GPS leveling method, not a spirit leveling method. Therefore, it is necessary to determine the vertical datum strictly using long-term and continuously tide observations more than 19 years and to use the GPS leveling method widely in the height leveling work for the effective changeover from the orthonormal to the orthometric in national height system.

• Journal of Korean Society for Geospatial Information Science
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• v.16 no.3
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• pp.117-126
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• 2008

Earth geopotential models were used to determine the reference surface in geoid modelling and many global geopotential models were developed after 1980's. Nowadays, EGM96 and EIGEN-GL04C geopotential models have been most widely used in the world, but what so called EGM2008 earth geopotential model were developed in 2008 by NGA. In this paper, we intended to compare the results of spherical harmonic analyses using the three geopotential model, EGM96, EIGEN-GL04C and EGM2008. So, the spherical harmonic analyses were performed up to degree and order 360(in case of EGM2008, up to degree and order 720, 1440, 2190 in addition), on each $1'{\times}1'$grid point in and around Korean peninsula. Geometric geoid were calculated at 464 GPS/leveling points for accuracy evaluation and then the results of three geopotential models were compared to geometric geoid. The results show that the accuracy of EGM2008 is improved considerablely compared to EGM96 and EIGEN-GL04C and it is possible to calculate geoidal heights within 14cm standard deviation and 5.5cm standard deviation after LSC fitting in and around Korean peninsula using EGM2008 geopotential model.

• Journal of the military operations research society of Korea
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• v.3 no.1
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• pp.123-136
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• 1977

This thesis presents a modification and extension to the Burgess and Killebrew heuristic resource leveling procedure for project networks. In contrast to previous algorithms appearing in the literature, the objective function of this algorithm. is the minimization of the sum of the squared errors in each time period (deviations around the mean usage) of all resources over the duration of the project. This objective function continues the search for an improved schedule beyond that of previous algorithms with their associated objective functions. One important feature is that the algorithm tends to reduce the number of periods that a resource is idle during its duration on the project.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10a
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• pp.289-291
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• 2003

최근 들어 임베디드 시스템이 많은 발전을 하고 있고, 공간적인 장점으로 인해서 임베디드 시스템에 플래시 메모리가 많이 사용되고 있다. 그러나 플래시 메모리는 일반 자기 저장 매체와는 다른 특성을 가지고 있어서 플래시 메모리에 알맞은 효율적인 파일 관리 시스템을 필요로 한다. 현재 임베디드 리눅스에서는 JFFS2파일 시스템을 많이 사용하고 있는데, 이 논문에서는 JFFS2의 wear-leveling 알고리즘을 개선한 빈도수를 이용한 지움정책을 제안하고, 시뮬레이션을 통해서 빈도수를 이용한 지움정책의 wear-leveling이 효과적인 성능을 나타냄을 보였다.

• Cement Symposium
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• no.25
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• pp.200-205
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• 1997

• 레미콘
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• no.4 s.63
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• pp.69-76
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• 2000

• The korean journal of orthodontics
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• v.46 no.2
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• pp.87-95
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• 2016

Objective: We evaluated the effects of tooth displacement on frictional force when conventional ligating lingual brackets (CL-LBs), CL-LBs with a narrow bracket width, and self-ligating lingual brackets (SL-LBs) were used with initial leveling and alignment wires. Methods: CL-LBs (7th Generation), CL-LBs with a narrow bracket width (STb), and SL-LBs (In-Ovation L) were tested under three tooth displacement conditions: no displacement (control); a 2-mm palatal displacement (PD) of the maxillary right lateral incisor (MXLI); and a 2-mm gingival displacement (GD) of the maxillary right canine (MXC) (nine groups, n = 7 per group). A stereolithographic typodont system and artificial saliva were used. Static and kinetic frictional forces (SFF and KFF, respectively) were measured while drawing a 0.013-inch copper-nickel-titanium archwire through brackets at 0.5 mm/min for 5 minutes at $36.5^{\circ}C$. Results: The In-Ovation L exhibited lower SFF under control conditions and lower KFF under all displacement conditions than the 7th Generation and STb (all p < 0.001). No significant difference in SFF existed between the In-Ovation L and STb for a 2-mm GD of the MXC and 2-mm PD of the MXLI. A 2-mm GD of the MXC produced higher SFF and KFF than a 2-mm PD of the MXLI in all brackets (all p < 0.001). Conclusions: CL-LBs with narrow bracket widths exhibited higher KFF than SL-LBs under tooth displacement conditions. CL-LBs and ligation methods should be developed to produce SFF and KFF as low as those in SL-LBs during the initial and leveling stage.