• The Journal of the Korea Contents Association
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• v.17 no.6
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• pp.1-8
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• 2017

A smart leveling equipment was developed in this study by improving present leveling equipment. Both hardware and software of the equipment was developed and several accuracy tests of bench mark were conducted using various survey equipments. National control point (UO992-A), control points (15-00-06-24)-B and (15-00-06-23)-C were used for the accuracy test. As a result, the stable results in the range of errors were obtained in the cases of auto-level and digital level. Approximately 24mm error in the section of A-B and 26mm of B-C section was occurred in Smart Level equipment. This is due to the lack of technology completion and errors via relatively many numbers of installation tests. 46mm error of RMSE of smart level survey was occurred through the difference of section test. A small error was detected in short range but errors were accumulated far from the bench mark. It's concluded that an in-depth study emphasizing accuracy improvement can be practically applied to the various areas of industry.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.11 no.2
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• pp.35-41
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• 1993

The height differences in Mean Sea Level is an important factor in geodetic leveling net, because MSL is the reference datum for height. Geodesists and Oceanographers agree on the height differences in MSL in the east-west direction, but they disagree almost always on the north-south slope, each suspecting systematic errors in the leveling methods of the others. A promising method for determining this slope is comparison of MSL at the tidal station connected by geodetic leveling. The slopes of the sea surface along the coast of Korean Peninsular is estimated from conventional local MSL at the tidal station and bench mark height of first order leveling net in Korea. As a reference level surface, MSL at Inchon is chosen. The results indicate that sea level rises along coast of Korean Peninsular from south to north about 5.5 cm/latitude. In the east-west direction, sea level along East Sea coast stands about 5 cm higher than that along Yellow Sea coast. These are not invariable but provisional phenomena. It may become certain provided that the exact MSL is estimated.

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.5
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• pp.322-330
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• 2009

In order to utilize NAND flash memory as storage media which does not allow update-in-place and limits the number of block erase count, various garbage collection policies supporting wear-leveling have been investigated. Conventional garbage collection policies require cleaning-index calculation for the entire blocks to choose a block to be garbage-collected to support wear-leveling whenever a garbage collection is required, which results in performance degradation of system. This paper proposes a garbage collection policy which supports wear-leveling using a threshold value, which is in fact a variance of erase counts and by the maximum erase count of all blocks, without calculating the cleaning-index. During garbage collection, the erase cost is minimized by using the Greedy Policy if the variance is less than the threshold value. It achieves wear-leveling by excluding the block with the largest erase count from erase target blocks if the variance is larger than threshold value. The proposed scheme shows that a standard deviation approaches to zero as the erase count of blocks approaches to its upper limit and the measured speed of garbage collection is two times faster than the conventional schemes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.7
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• pp.425-432
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• 2014

This paper proposes a wear-leveling algorithm that exploits the properties of SSD memories with multi-channel and multi-way architecture. When a write request arrives, the proposed algorithm classifies the stored data in DRAM buffer into hot or cold according to logical address access frequency, and performs data allocation to reduce deviation of block erase counts. It lowers the chance of increasing erase count by allocating cold data to blocks which have high erase count. Effectiveness of the proposed algorithm is verified by executing various applications on a multi-channel, multi-way SSD simulator. Experimental results show that differences in erase count among blocks is reduced by an average of 9.3%, and total erase count decreases by 4.6%, when compared to previous wear-leveling algorithm.

• IEMEK Journal of Embedded Systems and Applications
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• v.12 no.3
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• pp.121-130
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• 2017

NAND flash memory has advantages of non-volatility, little power consumption and fast access time. However, it suffers from inability that does not provide to update-in-place and the erase cycle is limited. Moreover, the unit of read/write operation is a page and the unit of erase operation is a block. Therefore, erase operation is slower than other operations. The AGC, the proposed garbage collection policy focuses on not only garbage collection time reduction for real-time guarantee but also wear-leveling for a flash memory lifetime. In order to achieve above goals, we define three garbage collection operating modes: Fast Mode, Smart Mode, and Wear-leveling Mode. The proposed policy decides the garbage collection mode depending on system CPU usage rate. Fast Mode selects the dirtiest block as victim block to minimize the erase operation time. However, Smart Mode selects the victim block by reflecting the invalid page number and block erase count to minimizing the erase operation time and deviation of block erase count. Wear-leveling Mode operates similar to Smart Mode and it makes groups and relocates the pages which has the similar update time. We implemented the proposed policy and measured the performance compare with the existing policies. Simulation results show that the proposed policy performs better than Cost-benefit policy with the 55% reduction in the operation time. Also, it performs better than Greedy policy with the 87% reduction in the deviation of erase count. Most of all, the proposed policy works adaptively according to the CPU usage rate, and guarantees the real-time performance of the system.

• Journal of the Korean Association of Geographic Information Studies
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• v.16 no.4
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• pp.54-63
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• 2013

In this paper, we evaluate the accuracy of the vertical positioning by distance using Network RTK-GPS. The experimental results confirm that Network RTK-GPS method can acquire data quickly and accurately than conventional leveling methods so that the Network RTK-GPS method is a relatively efficient and economical way for the vertical positioning. Results of validation using permanent GPS stations indicate that visible satellites, PDOP, and VDOP are very good for the vertical positioning. Integrated reference points such as U0997 and U0921 are satisfied with 3 ratings in the rules of public leveling and all the rest are proved improper. When the vertical positioning using Network RTK-GPS is implemented, the geoid height of EGM2008 should be applied for leveling. If the number of geodetic satellite are increasing in the near future, the vertical positioning using Network RTK-GPS can be possible in all the range.

• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.6
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• pp.423-438
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• 2021

The blade of motor grader is used for scattering and leveling the aggregates on the foundation of road construction site. The paper performed a design improvement research of the blade part to enhance the working efficiency of motor graders. The scattering works of aggregates by blade driving were simulated by DEM (discrete element method) of a dynamic code. The four design parameters were selected and a specific leveling scenario for the simulation was determined. The nine blade models were numerically experimented, and the sensitivity of each factors was analyzed. Next, the design factors that influence a blade performance have been selected by ANOVA, and these key design factors were applied to the progressive quadratic response surface method (PQRSM). The optimum set of design factors of the blade was finally proposed.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.1
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• pp.131-136
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• 2017

In this study, we design a controller that regulates the water leveling system which suffers from the disturbance. A number of control techniques have been reported which can reduce the amplitude of disturbance. But due to input-delay, these methods do not perform as expected. To overcome the problem, this paper introduces a filter and proposes a proportional and integral (PI) controller that combined with the filter (modifed PI controller). Moreover, we combine the controller with disturbance observer (DOB) that can estimate and eliminate disturbance. The proposed controller and combined the controller with DOB are tested using MATLAB.

• Journal of Biosystems Engineering
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• v.29 no.5 s.106
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• pp.425-432
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• 2004

In harvesting rice and barley using combine, the inclination of the body caused by the irregular surface condition of the field and the soil sinking from the unbalanced weight during the grain collection used to make harvesting operation difficult and even impossible. To overcome such a problem hydraulic system far automatic and manual leveling control of a combine has been developed. The system was composed of the combine body and the hydraulic level control system mounted on it. The maximum height of ground clearance was set up to be 290mm. And the limit angle of the leveling control was set up to be $\pm7^{\circ}$. The proposed controller and hydraulic system was implemented to the prototype combine. The prototype combine was designed and built as a separable structure with the body and the track of it. This paper shows results of a specification and design testing with the hydraulic level control system far body of combine.

• Korean Journal of Construction Engineering and Management
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• v.3 no.4 s.12
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• pp.104-113
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• 2002

Knowledge Management(KM), represented as a way to sustain or gain competitive edge in domestic construction companies since late 1990s economic fluctuation, whose priority is to transform individual tacit knowledge into explicit organizational one. Also, accompanied by academic researches, they come to turn their interests on KM leveling and its results. However, they went too far to KM results without commenting what their KM capabilities are and where they should lead. Thus, this research work suggests a leveling model for KM, especially construction company, whose role is to diagnose which parts they should be encouraged or how to strengthen their present capabilities.