• 한국정밀공학회지
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• 제4권2호
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• pp.47-55
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• 1987

Recently, in precision working, precision is in submicron. Therefore, when we measure various finished goods in superfine measurement, because it is relatively difficult to disregard effect of surroundings, these effect of surroundings must be compensated or canceled. In this study, for roundness measurement, three point method is researched which is able to cancel the effect of rotation accuracy of axis and eccenricity of workpiece. It is difference between this three point method and tradi- tional three point method whose measuring apparatus have three movable pickups posit- ioned with angle and between the pickups. As a results, when rotation accuracy of axis is varied from $0.02\mu\textrm{m}$ to $0.05\mu\textrm{m}$ the width of variation of measured roundness is $0.04\mu\textrm{m}$. And, when eccentricity of workpiece is varied from 0 to $4\mu\textrm{m}$, the width of variation of measured roundness is $0.005\mu\textrm{m}$. These error width are disregardable because they are in 10% of measured roundness. Therefore, by this three point method, the effect of rotation accuracy of axis and the effect of eccentricity of workpiece are canceled. And we are able to select the angle between the pickups ($\phi$ and $\tau$) by means of relation between $F_{k}$ and K.

• Structural Engineering and Mechanics
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• 제53권5호
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• pp.897-919
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• 2015

In this study, the effects of ground shocks due to explosive loads on the dynamic response of historical masonry bridges are investigated by using the multi-point shock response spectrum method. With this purpose, different charge weights and distances from the charge center are considered for the analyses of a masonry bridge and depending on these parameters frequency-varying shock spectra are determined and applied to each support of the two-span masonry bridge. The net blast induced ground motion consists of air-induced and direct-induced ground motions. Acceleration time histories of blast induced ground motions are obtained depending on a deterministic shape function and a stationary process. Shock response spectrums determined from the ground shock time histories are simulated using BlastGM software. The results obtained from uniform and multi-point response spectrum analyses cases show that significant differences take place between the uniform and multi-point blast-induced ground motions.

• International journal of advanced smart convergence
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• 제9권3호
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• pp.192-198
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• 2020

The 3D point cloud is a key technology of object detection for virtual reality and augmented reality. In order to apply various areas of object detection, it is necessary to obtain 3D information and even color information more easily. In general, to generate a 3D point cloud, it is acquired using an expensive scanner device. However, 3D and characteristic information such as RGB and depth can be easily obtained in a mobile device. GNN (Graph Neural Network) can be used for object detection based on these characteristics. In this paper, we have generated RGB and RGBD by detecting basic information and characteristic information from the KITTI dataset, which is often used in 3D point cloud object detection. We have generated RGB-GNN with i-GNN, which is the most widely used LiDAR characteristic information, and color information characteristics that can be obtained from mobile devices. We compared and analyzed object detection accuracy using RGBD-GNN, which characterizes color and depth information.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
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• pp.366-376
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• 2008

The model tests of short pile with very small pile length/diameter(L/D) were performed in this paper. Varying the pile diameter, length, and the lateral loading point, the lateral resistance and behavior of very short pile were studied in this model tests. The experimental and analytical results are as follows. The lateral ultimate resistance of short pile in sands was the maximum at the point of h/L=0.75, regardless of pile length/diameter(L/D). As the pile diameter is larger, the lateral ultimate resistance of pile with L/D=1 decreases a little and the lateral resistance increases according to the ratio of pile length/diameter. As the lateral loads are acting on the pile, the displacement of pile head is maximum at the pile top of h/L=0, but minimum at the middle point of the pile. And if the loading point is under the middle of pile, the displacement of pile head occurs oposite in the loading direction, but its magnitude is very small.

• 제어로봇시스템학회논문지
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• 제21권10호
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• pp.958-964
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• 2015

In this paper, an object recognition method based on the depth information from the RGB-D camera, Xtion, is proposed for an indoor mobile robot. First, the RANdom SAmple Consensus (RANSAC) algorithm is applied to the point cloud obtained from the RGB-D camera to detect and remove the floor points. Next, the removed point cloud is classified by the k-means clustering method as each object's point cloud, and the normal vector of each point is obtained by using the k-d tree search. The obtained normal vectors are classified by the trained multi-layer perceptron as 18 classes and used as features for object recognition. To distinguish an object from another object, the similarity between them is measured by using Levenshtein distance. To verify the effectiveness and feasibility of the proposed object recognition method, the experiments are carried out with several similar boxes.

• BMB Reports
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• 제29권5호
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• pp.442-447
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• 1996

Mutations in codon 12, 13 and 61 of one of the three ras genes, H-ras, K-ras and N-ras, convert these genes into active oncogenes. The presence of H-ras gene mutations have important prognostic implications in various cancers. In this study, the H-ras gene mutations were investigated by two-step PCRRFLP in patients with bladder and stomach cancer. For the control experiments, T24 and SK2 cell lines were used. In a total of 36 bladder cancer patient cases, five (13.9%) mutations were found by this method. Of these, point 12 mutations were two (5.6%) cases and point 61 mutations were three (8.3%) cases. On the other hand, H-ras mutation was not found in 29 cases of stomach cancer. The results of the mutated H-ras gene confirmed by direct sequencing analysis were correlated well with PCR analysis. From the sensitivity test, the H-ras mutation was found to have about 0.2% of mutated DNA mingled in normal DNA. In conclusion, the H-ras mutation has a higher clinical Significance in bladder cancer than stomach cancer. Moreover the two-step PCR-RFLP method is sensitive, rapid and relatively simple for clinical work in detecting H-ras point mutations.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(2)
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• pp.560-564
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• 2003

This paper proposes a simple control strategy based on the discontinuous PWM(DPWM) to balance the DC-link voltage of three-level Neutral-Point-Clamped(WPC) inverters at low modulation index. New DPWM methods in multi-level inverter are also introduced. The proposed DPWM method changes the path and duration to flow the neutral point current out of or into neutral point of the DC-link and it makes the overall fluctuation of the DC-link voltage zero during a sampling time of reference voltage vector. Therefore, the voltage of the DC-link can be balanced fairly well and also the voltage ripple of the DC-link is reduced significantly. Moreover, comparing with conventional methods, the proposed strategy is very simple. The validity of the proposed DPWM method is verified by experiment

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2007년도 Proceedings of ISRS 2007
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• pp.61-64
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• 2007

Subsurface Internal Waves (IWs) can be detected in satellite images as periodic alternating brighter/darker stripes. It is known that there are two types of IWs - depression type and elevation type - depending on the water depth in stratified oceans. In this study, we have quantitatively verified the process of converting polarity from depression waves to elevation waves using ERS-2 SAR images acquired over the northern South China Sea. We simulated the evolution of IWs near a turning point with a numerical model for internal wave propagation. The simulation results near the turning point clearly showed us not only a conversion process of IWs from depression to elevation waves, but also a similar wave pattern with the observed SAR image. We also simulated SAR intensity variation near the turning point. The upper layer currents were computed at regular intervals using the numerical model, as the IWs were passing through the turning point. Then, an integrated hydrodynamic-electromagnetic model was used for simulating SAR intensity profiles from the upper layer currents at each position. The simulated SAR intensity profiles at each position were compared with the observed SAR intensities.

• Journal of Mechanical Science and Technology
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• 제15권9호
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• pp.1257-1267
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• 2001

For efficient mechanical system optimization, a new two-point approximation method is presented. Unlike the conventional two-point approximation methods such as TPEA, TANA, TANA-1, TANA-2 and TANA-3, this introduces the shifting level into each exponential intervening variable to avoid the lack of definition of the conventional exponential intervening variables due to zero-or negative-valued design variables. Then a new quadratic approximation whose Hessian matrix has only diagonal elements of different values is proposed in terms of these shifted exponential intervening variables. These diagonal elements are determined in a closed form that corrects the typical error in the approximate gradient of the TANA series due to the lack of definition of exponential type intervening variables and their incomplete second-order terms. Also, a correction coefficient is multiplied to the pre-determined quadratic term to match the value of approximate function with that of the previous point. Finally, in order to show the numerical performance of the proposed method, a sequential approximate optimizer is developed and applied to solve six typical design problems. These optimization results are compared with those of TANA-3. These comparisons show that the proposed method gives more efficient and reliable results than TANA-3.

• 열처리공학회지
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• 제25권4호
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• pp.181-189
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• 2012

The demand on quantitative measurement of the heat flux is motivated in making higher-quality steel product through a water quenching process of plate mill. To improve a spatial degree of heat flux measurement, the multi-point heat flux measurement was carried out by a unique experimental technique that has a combination of the existing single-point heat flux gauge. The corresponding heat flux can be easily determined by Fourier's law in a conventional way. The multi-point heat flux gauge developed in this study can be applicable to measure the surface heat flux, the surface heat transfer coefficient during a water quenching applications of steelmaking process. The results exhibit different heat transfer regimes; such as single-phase forced convection, nucleate boiling, and film boiling, that are occurred in close proximity on the multi-point heat flux gauge quenched by water impinging jet.