• Proceedings of the Korean Geotechical Society Conference
• /
• 2003.03a
• /
• pp.265-272
• /
• 2003

In this study, the rock mass classification results from the face mapping and the resistivity inversion data are compared and analyzed for the reliability investigation of the determination of the rock support type based on the surface electrical survey. To get the quantitative correlation, rock engineering indices such as RCR(rock condition rating), N(Rock mass number), Q-system based on RMR(rock mass rating) are calculated. Kriging method as a post processing technique for global optimization is used to improve its resolution. The result of correlation analysis shows that the geological condition estimated from 2D electrical resistivity survey is coincident globally with the trend of rock type except for a few local areas. The correlation between the results of 3D electrical resistivity survey and the rock mass classification turns out to be very high. It can be concluded that 3D electrical resistivity survey is powerful to set up the reliable rock support type.

• Journal of the Korean Institute of Telematics and Electronics B
• /
• v.29B no.11
• /
• pp.73-84
• /
• 1992

In this paper, an algorithm for recovering the 3-D shape from a single shaded image is proposed. In the proposed algorithm, by using the relation between the height and surface gradient (p, q), a set of linear equations is derived from the linearized reflectance function. Then the 3-D surface is recovered by employing the conjugate gradient technique. In order to improve the convergence speed of the solution, we also employ the hierarchical basis function and multiresolution images in the algorithm. A method for determining the regularization parameter, which is determined by trial and error in the conventional approach, is also introduced. In addition, the proposed algorithm attempts to recover the 3-D surface without requiring the boundary conditions, making it suitable for a real-time implementation. Simulation results for real image as well as synthetic image are provided to demonstrate the performance of the proposed algorithm.

• Steel and Composite Structures
• /
• v.13 no.1
• /
• pp.15-33
• /
• 2012

For an axially loaded box-shaped member, the width-to-thickness ratio of the plate elements preferably should not be greater than 40 for Q235 steel grades in accordance with the Chinese code GB50017-2003. However, in practical engineering the plate width-to-thickness ratio is up to 120, much more than the limiting value. In this paper, a 3D nonlinear finite element model is developed that accounts for both geometrical imperfections and residual stresses and the ultimate capacity of welded built-up box columns, with larger width-to-thickness ratios of 60, 70, 80, and 100, is simulated. At the same time, the interaction buckling strength of these members is determined using the effective width method recommended in the Chinese code GB50018-2002, Eurocode 3 EN1993-1 and American standard ANSI/AISC 360-10 and the direct strength method developed in recent years. The studies show that the finite element model proposed can simulate the behavior of nonlinear buckling of axially loaded box-shaped members very well. The width-to-thickness ratio of the plate elements in welded box section columns can be enlarged up to 100 for Q235 steel grades. Good agreements are observed between the results obtained from the FEM and direct strength method. The modified direct strength method provides a better estimation of the column strength compared to the direct strength method over the full range of plate width-to-thickness ratio. The Chinese code and Eurocode 3 are overly conservative prediction of column capacity while the American standard provides a better prediction and is slightly conservative for b/t = 60. Therefore, it is suggested that the modified direct strength method should be adopted when revising the Chinese code.

• Proceedings of the KIEE Conference
• /
• 2007.04c
• /
• pp.65-67
• /
• 2007

This paper proposes a novel flux barrier in q-axis of rotor in IPM type BLDC motor, The proposed flux barrier can reduce cogging torqeu and diminisg torque ripple by sinusoidal waveform distribution of flux generated in the permanent magnet. To determine the optimal shape of the novel flux barrier, we also propose a modified Taguchi method which considering multiple quality characteristics, such as cogging torque, average torque, and efficiency. The proposed design and method were analyzed by using the 2D finite element method (FEM). Results of the proposed model were compared with initial model.

• Journal of Power Electronics
• /
• v.16 no.5
• /
• pp.1791-1801
• /
• 2016

This paper considers a carrier based signal injection method for use in the three shunt sensing inverter (TSSI) for sensorless motor control. It also analyzes the loss according to the injection axis of the voltage signal. To remove both the phase current and rotor position sensors, a sensorless method and a phase current reconstruction method can be simultaneously considered. However, an interaction between the two methods can be incurred when both methods inject voltage signals simultaneously. In this paper, a signal injection based sensorless method with the 120° OFF Discontinuous PWM (DPWM) is implemented in a TSSI to avoid this interaction problem. Since one leg does not have a switching event for one sampling period in the 120° OFF DPWM, the switching loss is altered according to the injection axis. The switching loss in the d-axis injection case can be up to 32% larger than that in the q-axis injection case. Other losses according to the injection axis are also analyzed.

• Structural Engineering and Mechanics
• /
• v.4 no.1
• /
• pp.61-72
• /
• 1996

The time-stepping boundary element method has been so far applied by the authors to transient heat conduction in isotropic solids as well as in orthotropic solids. In this paper, attempt is made to extend the method to 2-D transient heat conduction in arbitrarily anisotropic solids. The resulting boundary integral equation is discretized by means of the boundary element with quadratic interpolation. The final system of equations thus obtained is solved by advancing the time step from the given initial state to the final state. Through numerical compuation of a few examples the potential usefulness of the proposed method is demonstrated.

• Tunnel and Underground Space
• /
• v.13 no.4
• /
• pp.279-286
• /
• 2003

Many trials to set up the correlation between the rock mass classification and the earth resistivity have been carried out to design tunnel support type based on the interpreted electrical resistivity acquired by surface electrical survey. But it is hard to find reports on the comparison of the real rock support type determined during the excavation with the electrical resistivity by the inversion of the survey data acquired before the tunneling. In this study, the rock mass classification based on the face mapping data and the resistivity inversion data are investigated to see if it is possible to design reliably the rock support type based on the surface electrical survey. To get the quantitative correlation, rock engineering indices such as RCR(rock condition rating), N(Rock mass number), Q-system and RMR(rock mass rating) are calculated. Since resistivity data has low resolution, Kriging method as a post processing technique which minimizes the estimated variance is used to improve resolution. The result of correlation analysis shows that the 2D electrical resistivity survey is appropriate to see the general trend of the geology in the sense of rock type, though there might be some local area where these two factors do not coincide. But the correlation between the result of 3D survey and the rock mass classification turns out to be very high, and then 3D electrical resistivity survey can make it possible to set up more reliable rock support type.

• Journal of Ocean Engineering and Technology
• /
• v.35 no.4
• /
• pp.266-272
• /
• 2021

Mooring systems are among the most important elements employed to control the motion of floating offshore structures on the sea. Considering the use of polymer material, a new method is proposed to address the creep characteristics rather than the method of using a tension load cell for measuring the tension of the mooring line. This study uses a synthetic mooring rope made from a polymer material, which usually consists of three parts: center, eye, and splice, and which makes a joint for two successive ropes. We integrate the optical sensor into the synthetic mooring ropes to measure the rope tension. The different structure of the mooring line in the longitudinal direction can be used to measure the loads with the entire mooring configuration in series, which can be defined as SMART (Smart Mooring and Riser Truncation) mooring. To determine the characteristics of the basic SMART mooring, a SMART mooring with a diameter of 3 mm made of three different polymer materials is observed to change the wavelength that responds as the length changes. By performing the longitudinal tension experiment using three different SMART moorings, it was confirmed that there were linear wavelength changes in the response characteristics of the 3-mm-diameter SMART moorings. A 54-mm-diameter SMART mooring is produced to measure the response of longitudinal tension on the center, eye, and splice of the mooring, and a longitudinal tension of 100 t in step-by-step applied for the Maintained Test and Fatigue Cycle Test is conducted. By performing a longitudinal tension experiment, wavelength changes were detected in the center, eye, and splice position of the SMART moorings. The results obtained from each part of the installed sensors indicated a different strain measurement depending on the position of the SMART moorings. The variation of the strain measurement with the position was more than twice the result of the difference measurement, while the applied external load increased step-by-step. It appears that there is a correlation with an externally generated longitudinal tensional force depending on the cross-sectional area of each part of the SMART mooring.

• Korean Journal Plant Pathology
• /
• v.1 no.1
• /
• pp.61-66
• /
• 1985

Seventy-one strains collected from Korea were classified into three serovars (designated A, B-I and B-II) by using agar gel diffusion test with the antisera produced against Xanthomonas campestris pv. oryzae isolates Q7472 and Q7502. Of 71 isolates tested, 65 isolates belonged to serovar A, 5 isolates were serovar B-I, and one isolate was serovar B-II. The isolates of serovar B-I and B-II could be distinguished clearly from those of serovar A showing marked autoagglutination. Xanthomonas campestris pv. oryzae was serologically diagnosed in rice leaves by agar gel diffusion tests, possibly being distinguished from Xanthomonas campestris pv. olyzicola and E. herbicola. The pathogen could be also serologically detected from the extracts of diseased leaves, squeezed immediately, heated at $100^{\circ}C$ or incubated in PSA. Serological detection of Xanthomonas campestris pv. oryzae is a more reliable and less time-comsuming method.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.56 no.3
• /
• pp.498-505
• /
• 2007

This paper proposes the novel flux barrier that built in q-axis in rotor of IPM type BLDC motor. The novel flux barrier aims to reduce the motor vibration with reduced cogging torque and lessened torque ripple by the sinusoidal waveform distribution of the flux generated in the permanent magnet. For optimization of the novel flux barrier, the Taguchi method is effectively employed which considered multiple objective quality characteristics, such as cogging torque, average torque and efficiency. The result of proposed model compare with the initial model and it is verified by 2D finite element method (FEM) results.