• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.5
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• pp.49-56
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• 2023

This study proposed a damage location estimation method for automated image-based port infrastructure inspection. Memory efficiency was improved by calculating the homography matrix using feature detection technology and outlier removal technology, without going through the 3D modeling process and storing only damage information. To develop an algorithm specialized for port infrastructure, the algorithm was optimized through ground-truth coordinate pairs created using images of port infrastructure. The location errors obtained by applying this to the sample and concrete wall were (X: 6.5cm, Y: 1.3cm) and (X: 12.7cm, Y: 6.4cm), respectively. In addition, by applying the algorithm to the concrete wall and displaying it in the form of an exterior damage map, the possibility of field application was demonstrated.

• Journal of Ocean Engineering and Technology
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• v.25 no.4
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• pp.42-47
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• 2011

In this paper, wake equalizing duct (WED) form optimization was carried out using computational fluid dynamics (CFD) techniques. A WED is a ring-shaped flow vane with a foil-type cross-section fitted to a hull in front of the upper propeller area. The main advantage of a WED is the power savings resulting from the uniformity of the velocity distribution on the propeller plane, a reduction in the flow separation at the aft-body, and lift generation with a forward force component on the foil section. This paper intends to evaluate these functions and find an optimized WED form for minimizing the viscous resistance and equalizing the wake distribution. In the optimization process, the study uses four WED parameters: the angle of the section, longitudinal location, and angles of the axes for the half rings against the longitudinal and transverse planes of the ship. KRISO 300K VLCC2 (KVLCC2) is chosen as an example ship to demonstrate the WED optimization. The optimization procedure uses genetic algorithms (GAs), a gradient-based optimizer for the refinement of the solution, and Non-dominated Sorting GA-II(NSGA-II) for Multiobjective Optimization. The results show that the optimized WED can reduce the viscous resistance at the expense of the uniformity of the wake distribution.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.10a
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• pp.73-76
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• 2009

The optical structure of edge-lit LED backlight has been optimized via simulation study in order to remove bright spots appearing on the entrance region of the light guide plate (LGP) and thus to improve the luminance uniformity. The density of scattering dots located on the back surface of LGP was adjusted according to the location of LED's. In addition, lenticular lenses or a diffuse transmissive surface were formed on the side surface of LGP facing the LED's, and the density of lenticular lenses was optimized for redistributing rays emitted from LED's into wider angles. The bright spots which could be seen from conventional LED backlight were removed by the combination of these two optical structures. The application of diffuse surface to the entrance face gave better uniformity than the application of lenticular lenses. However, dark regions still appear on the entrance region of LGP, which should be removed by more appropriate optical design for achieving better luminance uniformity on the LED backlight.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.4 s.181
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• pp.91-98
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• 2006

A light guide panel (LGP) is an element of the LCD back light unit, which is used for display devices. In this study, the laser marking process is applied to the fabrication of light guide panels as the new fabrication process. In order to obtain a light guide panel which has high luminance and uniformity, four principal parameters such as power, scanning speed, ratio of line gap, and number of line were selected. A Web-based design tool was developed to generate patterns of light guide panel at any location, and the tool may assist the designer to develop optimized patterns. Topcon-BM7 was used for luminance measurement of each specimen with $100mm{\times}100mm$ area. By Taguchi method optimized levels of each parameters were found, and luminance of $3523cd/cm^2$ and uniformity of 92% were achieved using the laser machined BLU.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.04a
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• pp.413-417
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• 1997

Distributed piezoelectric sensor and actuator have been designed for efficient vibration control of a cantilevered beam. Both PZT and PVDF are used in this study, the former as an actuator and the latter as a sensor for our integrated structure. For the PZT actuator, the position and size have been optimized. Optimal electrode shape of the PVDF sensor has been determined. For multi-mode vibration control, we have used two PZT actuators and a PVDF sensor. Electrode shading of PVDF is more powerful for modal force adjustment than the sizing and positioning of PZT. Finite element method is used to model the structure that includes the PZT actuator and the PVDF sensor. By deciding on or off of each PZT segment, the length and the location of the PZT actuator are optimize. Considering both of the host structure and the optimized actuators, it is designed that the active electrode width of PVDF sensor along the span of the beam. Actuator design is based on the criterion of minimizing the system energy in the control modes under a given initial condition. Sensor is designed to minimize the observation spill-over. Modal control forces for the residual(uncontrolled) modes have been minimized during the sensor design. Genetic algorithm, which is suitable for this kind of discrete problems, has been utilized for optimization. Discrete LQG control law has been applied to the integrated structure for real time vibration control. Performance of the sensor, the actuator, and the integrated smart structure has been demonstrated by experiments.

• Reproductive and Developmental Biology
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• v.28 no.4
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• pp.257-260
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• 2004

Efficiency of somatic cell nuclear transfer was investigated in mice. First, oocyte activation was induced by SrCl₂, and the rate of development was compared with embryos from normal fertilization. Although more than one half of SrCl₂-treated oocytes developed to blastocysts (146/262, 55.7%), the rate of blastocyst formation was significantly lower than normal fertilization controls (59/79, 74.6%). Second, enucleation of oocytes was performed using Polscope that enables non-invasive visualization of metaphase spindles. Such approach could not only avoid damage of oocytes during an exposure to UV light often employed in conventional enucleation procedures, but could also assure the removal of nuclei from all oocytes operated because of monitoring the location of spindles during an entire process of enucleation. Morphologically normal blastocysts were obtained from the transfer of cumulus cell nuclei into enucleated oocytes. However, the rate of development into the blastocyst stage was still low (4/93, 4.3%). This reflects that the nuclear transfer procedure used in this study was not sufficiently optimized, and other factors may also impact greatly the efficiency of nuclear transfer. Including an induction of oocyte activation and method of enucleation tested in this study, a lot more elements are remained to be optimized to improve the efficiency of somatic cell nuclear transfer in mice.

• 한국정보디스플레이학회:학술대회논문집
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• 2000.01a
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• pp.73-74
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• 2000

In recent years, attempts have been made to greatly improve the display quality of active-matrix liquid crystal display devices, and many techniques have been proposed to solve such problems as gate signal delay, feed-through voltage and image sticking[1-3]. To improve these problems which are caused by the feed-through voltage, we have evaluated new driving methods to reduce the feed-through voltage. Two level gate-pulse was used for the gate driving of the cst-on-common structure pixels. These gate driving methods offer better feed-through characteristics than conventional simple gate pulse. Optimized step signal will compensate by step pulse time and voltage. The evaluation of the suggested driving methods were performed by using a TFT-LCD array simulator PDAST which can simulate the gate, data and pixel voltages of a certain pixel at any time and at any location on a TFT array. The effect of the new driving method was effectively analyzed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.1205-1205
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• 2003

Rotary compressors are one of the most important parts of air-conditioners in the industry This device usually has noise problems during the circulation process of the refrigerant and muffler is used for the noise reduction. The acoustic performance of the muffler depends on its shape and its hole locations on the upper surface. Therefore finding the optimum location of the muffler holes is a topic of increasing importance in the compressor industry. In this research the optimization of the muffler hole locations and the importance of the resonator cavity on the lower surface of the muffler in acoustic point of view is studied. At first, the topology optimization for the 2 hole muffler is performed based on a model without resonator cavity by using genetic algorithm. The 2 hole muffler's acoustic analysis and experiment results are matching, however, the optimized model's results are not. By adding the resonator cavity and also by changing the cavity shape, the acoustic analysis and experiment result comparison is Performed for different cavity shapes. The topology optimization of the revised model with cavity is carried out for noise reduction. Finally, the optimized design is produced and tested for validation.

• The KSFM Journal of Fluid Machinery
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• v.20 no.1
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• pp.21-28
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• 2017

Optimization process of pre-swirl nozzle geometry was conducted to improve the discharge coefficient of pre-swirl system by using CFD. The optimization of pre-swirl nozzle shape covered the converging angle and the location of the converging nozzle. Optimization process included Optimal Latin Hyper-cube Design method to get the experimental points and the Kriging method to create the response surface which gives candidate points. The process was finished when the difference between the predicted value and CFD value of candidate point was less than 0.1 %. This paper compared the Reference model, Initial model which is the first model of optimization and Optimized model to study flow characteristics. Finally, the discharge coefficient of Optimized model is improved about 17 % to the Reference model.

• Journal of the Korean Society of Radiology
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• v.11 no.4
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• pp.183-188
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• 2017

In recent years, the automatic remote control controller of the gamma ray irradiator malfunctions, and radiation workers are continuously exposed to radiation exposure accidents. In the non-destructive testing field, much time and resources are invested in establishing a radioactive source monitoring system in order to prevent potential incidents of radiation. In this study, the gamma-ray response properties of the lead monoxide-based radiation detector were estimated through monte carlo simulation as a previous study for the development of a radioactive source location monitoring system that can be applied universally to various non-destructive testing equipment. As a result of the study, the optimized thickness of the radiation detector varies according to the gamma-ray energy emitted from the radioactive source, and the optimized thickness gradually increases with increasing energy. In conclusion, the optimized thickness of the lead monoxide-based radiation detector was $200{\mu}m$ for the Ir-192, $150{\mu}m$ for the Se-75 and $300{\mu}m$ for the Co-60. Based on these results, the appropriate thickness of lead monoxide-based radiation detector considering secondary-electron equilibrium was evaluated to be $300{\mu}m$ for general application. These results can be used as a basic data for determining the appropriate thickness required in the radiation detector when developing a radiation source location monitoring system for universal application to various non-destructive testing equipment in the future.