• Structural Engineering and Mechanics
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• v.11 no.2
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• pp.211-219
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• 2001

This paper presents the tangent stiffness method for 3-D geometrically nonlinear folding analysis of a reversal arch. Experimental tests are conducted to verify the numerical analysis. The tangent stiffness method can accurately evaluate the geometrical nonlinearity due to the element translating as a rigid body, and the method can exactly handle the large rotation of the element in space. The arch in the experiment is made from a thin flat bar, and it is found that the folding process of the arch may be captured exactly by the numerical analysis with a model consisting of only 18 elements with the same properties.

• The Journal of the Convergence on Culture Technology
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• v.6 no.1
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• pp.515-520
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• 2020

The design and actual implementation of the four-bar parallel link was studied in the paper. The parallel four-section link is widely used as a basic kinematic mechanism for transmitting the rotation of one axis to the rotational motion of the other axis. However, the parallel 4 link has a problem that phase reversal occurs at the turning point during the movement. In order to prevent the link reversal, it is known that a double parallelogram-type link is formed by attaching an additional phase reversal suppression link with an offset. However, as a result of the actual fabrication experiment, the movement is not smooth at the transition point. In order to solve this problem, in this study, a link for smooth movement is added in addition to a link that provides an offset to prevent phase reversal, so that the phase reversal does not occur at a specific point when the driven shaft rotates along the drive shaft. The test result confirms the validity of our suggestion.

• Journal of Aquaculture
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• v.8 no.4
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• pp.271-283
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• 1995

Blue tilapia, Oreochromis aureus (Steindachner) swim-up fry were fed a ration containing 0, 1, 10, or 60 ppm $17\alpha-Methyltestosterone$ (MT) for 30 days (sex reversal period). Fish that had been fed 0 ppm MT-treated feed during the sex reversal period were subsequently fed rations containing either 0 ppm MT, 10 ppm MT, or 60 ppm MT for the next 39 days (post sex reversal period) : fish that had been fed 60 ppm MT-treated feed during the sex reversal period were subsequently fed rations containing either 0 ppm MT, 10 ppm MT, or 60 ppm MT during the post sex reversal period. One group was fed 1 ppm MT-treated feed, while another group was fed 10 ppm MT-treated feed during both periods. The following growing season (10 months later), the residual effects of MT on weight gain, body composition, and gonosomatic indices (GSI) were evaluated. MT had no residual effect on growth of either sex. Groups that ate MT-treated feed were significantly (P<0.05) larger than those that received no MT during the sex reversal period, because females in the latter group lowered average weight gain. MT had a positive residual effect on body fat content in males, but had a negative effect on body moisture content. MT had a positive residual effect on body moisture content in females. MT had a significant negative effect on male and female GSI at the end of the post sex reversal period. MT consumption during the sex reversal period had a significant negative residual effect on male GSI. MT fed after sexual development (post sex reversal period) did not have a residual effect on male or female CSI.

• Journal of radiological science and technology
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• v.43 no.2
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• pp.65-70
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• 2020

PA(postero-anterior) and AP(antero-posterior) chest projections are the most sought-after types of all kinds of projections. But if a radiological technologist puts wrong information about the position in the computer, the orientation of left and right side of an image would be reversed. In order to solve this problem, we utilized CNN(convolutional neural network) which has recently utilized a lot for studies of medical imaging technology and rule-based system. 70% of 111,622 chest images were used for training, 20% of them were used for testing and 10% of them were used for validation set in the CNN experiment. The same amount of images which were used for testing in the CNN experiment were used in rule-based system. Python 3.7 version and Tensorflow r1.14 were utilized for data environment. As a result, rule-based system had 66% accuracy on evaluating whether the orientation reversal on chest x-ray image. But the CNN had 97.9% accuracy on that. Being overcome limitations by CNN which had been shown on rule-based system and shown the high accuracy can be considered as a meaningful result. If some problems which can occur for tasks of the radiological technologist can be separated by utilizing CNN, It can contribute a lot to optimize workflow.

• Journal of Aquaculture
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• v.8 no.2
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• pp.77-83
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• 1995

The effects of six levels (0, 5, 10, 15, 20, and 25 ppm) of dietary $17\alpha-Methyltestosterone$ (MT) on sex reversal and growth of Oreochromis aureus (Steindachner) and O. niloticus (L.) were evaluated. Fifteen ppm MT produced $100\%$ male populations in both species. Both MT-treated and untreated O. niloticus grew significantly faster than their O. aureus counterparts (P<0.05).

• Smart Structures and Systems
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• v.32 no.4
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• pp.253-266
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• 2023

The time-reversal method is employed to improve the ability of pipeline defect detection, and a new approach of identifying the pipeline defect depth is proposed in this research. When the L(0,2) mode ultrasonic guided wave excited through a lead zirconate titinate (PZT) transduce array propagates along the pipeline with a defect, it will interact with the defect and be partially converted to flexural F(n, m) modes and longitudinal L(0,1) mode. Using a receiving PZT array attached axisymmetrically around the pipeline, the L(0,2) reflection signal as well as the mode conversion signals at the defect are obtained. An appropriate rectangle window is used to intercept the L(0,2) reflection signal and the mode conversion signals from the obtained direct detection signals. The intercepted signals are time reversed and re-excited in the pipeline again, result in the guided wave energy focusing on the pipeline defect, the L(0,2) reflection and the L(0,1) mode conversion signals being enhanced to a higher level, especially for the small defect in the early crack stage. Besides the L(0,2) reflection signal, the L(0,1) mode conversion signal also contains useful pipeline defect information. It is possible to identify the pipeline defect depth by monitoring the variation trend of L(0,2) and L(0,1) reflection coefficients. The finite element method (FEM) simulation and experiment results are given in the paper, the enhancement of pipeline defect reflection signals by time-reversal method is obvious, and the way to identify pipeline defect depth is demonstrated to be effective.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2008.10a
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• pp.520-524
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• 2008

This research verifies the phenomenon of which the Momentum and Reversal effect of stock price would depend on the subject of investment in the point of view of the Behavior Finance hypothesis. For the experiment, this paper uses the KOSPI200 daily data and Net Investment Flow from Jan. 1999 to Dec. 2006. And we analyze the marginal profit and loss with foreigners, individual investors, and institutions. We verify the response of the subjects of investment based on the CAR for 3 days after more than 3 percent rising or drop. We also verify the response with respect to the ascending and descending trend based on the profit trend and subjects' behaviors a week before the drop.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10b
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• pp.162-166
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• 2003

In combined forward-backward extrusion with controlled forward speed by a counter punch, accurate parts with forward rod can be formed. As an extension of this method, reverse extrusion is proposed, in which the extruded forward rod is pushed back while the main punch is kept at the final position after the forward-backward extrusion process. The experiment is carried out using lead as a model material. With the reverse extrusion method, longer forward rods can be formed without under-filling defect than that by combined extrusion with controlling extrusion speed.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.12
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• pp.709-717
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• 2004

Flux-reversal machine (FRM) is a new brushless doubly salient permanent magnet machine. Its operation is similar to that of the brushless DC motor, so it can be driven by 120 degree square wave voltage and use PWM pulse patterns in two-phase feeding scheme to control the speed. In this driving method, the back electromotive force (BEMF) current in the open phase is generated by the BEMF. It can be appeared or disappeared according to the changes of the neutral voltage of the machine. In this paper, the time-stepped voltage source finite-element method taking BEMF current into account is proposed. Its influences on the performances of the FRM are also investigated. To prove the propriety of the proposed analysis method, a Digital Signal Processor (DSP) installed experimental devices are equipped and the experiment is performed.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.546-548
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• 2010

This paper proposes a new baseline-free TR-based SHM method in which the time-reversal (TR) property of the guided Lamb waves is utilized. The new TR-based SHM method has two distinct features when compared with the other existing SHM techniques: (1) The measurement- based backward TR process is replaced by the computation-based process (2) In place of the comparison method most commonly used for SHM, the TOF information of the damage signal extracted from the reconstructed signal is utilized for the damage diagnosis. For the damage diagnosis, the imaging method is adopted to efficiently detect damage by representing the damage as an image. The proposed TR-based SHM technique is then validated through the damage diagnosis experiment for an aluminum plate with a damage at different locations.