• Journal of the Korean GEO-environmental Society
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• 제20권3호
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• pp.15-20
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• 2019

A large amount of site investigation data is essential to obtain reliable design value. However, site investigations are generally insufficient due to economic problems. It is important to estimate the ground profile information in unboring region for accurate earthwork-volume prediction, and such ground profile information can be estimated by using the geo-statistical approach. Furthermore, the ground profile information in unboring region can be estimated by training a model via machine learning technique such as artificial neural network. In this paper, artificial neural network-based model estimated the ground profile information in unboring region, and this results were compared with that of ordinary kriging technique, which is referred to the geo-statistical approach. Accordingly, a total of 84 ground profile information in an actual bridge environment was split into 75 training and 9 test databases. The observed ground profile information of the test database was compared with those of the ordinary kriging technique and artificial neural network.

• Journal of the Korean GEO-environmental Society
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• 제17권8호
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• pp.39-44
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• 2016

Ground deformation around construction site in urban area where typically adjacent structures are located needs to be strictly controlled. Accordingly, it is very important to precisely monitor the ground deformation. Settlement beacon is typically employed to measure the ground deformation, but meanwhile the rapid development in electronic technology enables 3D image scanner to become available for measuring the ground deformation profile in usual construction sites. With respect to the profile measurement, the 3D scanner has an advantage, whereas its accuracy is somewhat limited because it does not measure the displacement directly. In this paper, we developed a conditional merging technique to combine the ground displacement measured from settlement beacon and the profile measured by the 3D scanner. Synthetic ground deformation profile was generated to validate the proposed technique. It is found that the ground deformation measurement error can be reduced significantly via the conditional merging technique.

• Journal of the Korean Society for Precision Engineering
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• 제24권1호
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• pp.37-46
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• 2007

The vibration environment essentially companied by vehicle operation on the ground is determined by the shape of road surface, which is called profile. This paper focuses on development of a profile and severity measurement system for unpaved test courses. In general, the profile and severity of unpaved road is an important issue in the reliability of endurance test. In order to measure unpaved road profile and severity, it is necessary to develop a profilometer system. The developed profilometer system is composed of data processing computer, power unit, air compressor and sensors(encoder, vertical gyro and laser displacement) This paper presents the measuring system configuration, measurement principle of road profile and analysis method of road characteristics used at CPG(Changwon Proving Ground) for this purpose.

• Geomechanics and Engineering
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• 제20권4호
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• pp.275-285
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• 2020

Excavation usually induces considerable ground settlement in soft ground, which may result in damage of adjacent buildings. Generally, the settlement is predicted through elastic-plastic finite element method and empirical method with defects. In this paper, an analytical solution for predicting ground settlement induced by excavation is developed based on the definition of three basic modes of wall displacement: T mode, R mode and P model. A separation variable method is employed to solve the problem based on elastic theory. The solution is validated by comparing the results from the analytical method with the results from finite element method(FEM) and existing measured data. Good agreement is obtained. The results show that T mode and R mode will result in a downward-sloping ground settlement profile. The P mode will result in a concave-type ground settlement profile.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.98-101
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• 2003

As the ultra precision grinding can be applied to wafering process by the refinement of the abrasive. the development of high stiffness equipment and grinding skill, the conventional wafering process which consists of lapping, etching, 1st, 2nd and 3rd polishing could be exchanged to the new process which consists of precision surface grinding, final polishing and post cleaning. Especially, the ultra precision grinding of wafer improves the flatness of wafer and the efficiency of production. Futhermore, it has been not only used in bare wafer grinding, but also applied to wafer back grinding and SOI wafer grinding. This paper focused on the flatness of the ground wafer. Generally, the ground wafer has concave profile because of the difference of wheel path density, grinding temperature and elastic deformation of the equiptment. Tilting mathod is applied to avoid such non-uniform material removes. So, in this paper, the geometric analysis on grinding process is carried out, and then, we can predict the profile of th ground wafer by using profile simulation.

• Structural Engineering and Mechanics
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• 제11권2호
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• pp.133-149
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• 2001

A high-fidelity model of a tracked vehicle traversing a flexible ground terrain with a varying profile is presented here. In this work, we employed a recursive formulation to model the track subsystem. This method yields a minimal set of coordinates and hence, computationally more efficient than conventional approaches. Also, in the vehicle subsystem, the undercarriage frame is assumed to be connected to the chassis by a revolute joint and a spring-damper unit. This increase in system mobility makes the model more realistic. To capture the vehicle-ground interaction, a Winkler-type foundation with springs-dampers is used. Simulation runs of the integrated tracked vehicle system for vibrations for four varying ground profiles are provided.

• Proceedings of the KSR Conference
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• 한국철도학회 2005년도 춘계학술대회 논문집
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• pp.722-725
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• 2005

Recently, ground-borne noise and vibration generated by underground transit system has been recognized as an important environmental problem. This study reviews several of the improved procedures that have been used to predict ground-borne vibration. At first, ground stiffness profile is examined by SASW test which is the most reasonable surface wave test. It is very important to acquire the exact ground stiffness profile at ground response analysis. At second, the train loading to act roadbed is calculated by using the real measured phase angle data. In finite element analysis, averaged acceleration method, infinite element, Rayleigh damping and 2-dimensional wave propagation analysis is performed.

• Transactions of the Korean Society of Machine Tool Engineers
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• 제15권2호
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• pp.1-9
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• 2006

As consumers in optics, electronics, aerospace and electronics industry grow, the demand for ultra-precision aspheric surface lens increases higher. To enhance the precision and productivity of ultra precision aspheric surface micro lens, the development of ultra-precision grinding system and process for the aspheric surface micro lens are described. In the work reported in this paper, an ultra-precision grinding system for manufacturing the aspheric surface micro lens was developed by considering the factors affecting the ground surface roughness and profile accuracy. This paper deals with mirror grinding of an aspheric surface micro lens by resin bonded diamond wheel and spherical lens of BK7. The optimization of grinding conditions on ground surface roughness and profiles accuracy is investigated using the design of experiments.

• Journal of the Korean GEO-environmental Society
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• 제9권4호
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• pp.53-61
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• 2008

Various components including wave scattering, wave passage, and site amplification effects cause the ground motion to vary spatially. The spatially varying ground motion can significantly influence the dynamic response of longitudinal structures such as bridges and tunnels. While its effect on bridges has been extensively studied, there is a lack of study on its effect on underground tunnels. This paper develops a new procedure for simulating the tunnel response under spatially varying ground motion. The procedure utilizes the longitudinal displacement profile, which is developed from spatially variable ground motion time histories. The longitudinal displacement profile is used to perform a series of pseudo-static three dimensional finite element analyses. Results of the analyses show that the spatially variable ground motion cause longitudinal bending of the tunnel and can induce substantial axial stress on the tunnel lining. The effect can be significant at boundaries at which the material properties of the ground change in the longitudinal direction.

• Journal of the Korean Society for Precision Engineering
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• 제21권10호
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• pp.26-33
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• 2004

Ultra precision grinding technology has been developed from the refinement of the abrasive, the development of high stiffness equipment and grinding skill. The conventional wafering process which consists of lapping, etching, 1 st, 2nd and 3rd polishing has been changed to the new process which consists of precision surface grinding, final polishing and post cleaning. Especially, the ultra precision grinding of wafer improves the flatness of wafer and the efficiency of production. Furthermore, it has been not only used in bare wafer grinding, but also applied to wafer back grinding and SOI wafer grinding. This paper focuses on the flatness of the ground wafer. Generally, the ground wafer has concave pronto because of the difference of wheel path density, grinding temperature and elastic deformation of the equipment. Wafer tilting is applied to avoid non-uniform material removal. Through the geometric analysis of wafer grinding process, the profile of the ground wafer is predicted by the development of profile simulator.