• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.258-261
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• 2006

This study introduces the control of duration time of impulse noises emitted from a high voltage COS fuse of a transformer. When a high voltage COS fuse becomes a short circuit by the over current, the peak sound pressure level over 150 dB(A) is generated at the distance of 2m from a COS Fuse. For the purpose of the reduction of impulse noise, in this study, the reactive type silencer has been utilized. And also electrical interrupting test was experimented. From the experimental results, the reactive type silencer has been shown to have the noise reduction of about 13 dB(A). It has been found that the electrical interception performance of the COS fuse was related to the control of the duration time of impulse noise.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.60-68
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• 2010

In this study, the seepage flow monitoring method by hydaulic head loss rate graph was developed for the purpose of monitoring the seepage flow from the see side or from the lake on sea dike in which seepage force was varied periodically. The hydraulic head loss rate was defined in this method. The value of the rate is in the range from 0 to 1. the value of 0 means perfectly free flow of seepage. the value of 1 means perfect waterproofing. The value of coefficient of determination in the hydraulic head loss rate graph closer to 1 means that the seepage flow way is stable. The value of coefficient of determination in the hydraulic head loss rate graph closer to 0 means that the hole may exist or the piping may be in the progress. The pore water pressure data measured in Saemangeum sea dike was analyzed with the developed method The result showed that the variation of seepage flow state was detected sensitively by this method and the interception effect of sea dike could be estimated quantitatively.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.10a
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• pp.581-590
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• 2005

The grouting method is widely used as the impermeable effect and ground reinforcement in construction. But, it has a problem that cement and grout material are not mixed well in the injection tip equipment and an opposite flow and interception state of the chemical grouting is happened. so, continuous work is difficult. McG method installed a special grouting and device, made possible go well mixing of grouting material and prevent flowing backward and block of nozzle also diversify powder rate of cement that is grouting material to select sutible material in layer conditions. YSS that lowered $Na_2O$ influencing durability and circumstance is developed by gel-forming reaction material. so eco-circumstance and durability is increased by minimizing dissolution of underground water. In this study, it is assumed that seepage state of the injection material using a special injection tip equipment and a unconfined compressive strenth by mixing a various injection material of various. And it is confirmed that strenth increase effect and permeable decrease of the improved body through the test execution and field execution.

• Magazine of the Korean Society of Agricultural Engineers
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• v.12 no.2
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• pp.1965-1970
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• 1970

The experiment was carried out in order to improve the leakage stopping work in the irrigation canal founding on the porous soil. But the experiment had many problems to be studied more owing to the insufficient time and facilities. The results obtained are summarized as follows; 1. Polyethylene film is estimated not to make strength decrease owing to buring in the subsoil, but to make owing to the sunlight. 2. Coated nylon shows the tendency to deteriorate strength when it is buried in the earth or exposed to the sun for long time, but leakage is all but impermeability generally. 3. Leakage loss rates for one hour show some differences in the canal to be full with water in accordance with operating methods, that is, the clay lining section is 12.6%, the coated nylon lining section is 1.7%, the polyethylene film lining section is 1.3%, respectively. 4. Leakage quantities per wetted perimeter unit area show $3.556cc/cm^2/hr$. in the clay lining section, $1.574cc/cm^2/hr$. in the coated nylon section, $0.695cc/cm^2/hr$. in the polyethylene film lining section, respectively. 5. When the construction fund make the clay lining section as a standard, the polyethylene film section is 92.1%, the coated nylon section is 174.2%, respectively. But, the unit cost of execution may be low when the polyethylene film and the coated nylon will enable to mass-produce for the purpose of execution.

• International Journal of Aeronautical and Space Sciences
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• v.18 no.4
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• pp.719-728
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• 2017

This paper proposes a synthesis of new guidance law to generate an evasive maneuver against enemy's missile interception while considering its impact angle, acceleration, and field-of-view constraints. The first component of the synthesis is a new function of repulsive Artificial Potential Field to generate the evasive maneuver as a real-time dynamic obstacle avoidance. The terminal impact angle and terminal acceleration constraints compliance are based on Time-to-Go Polynomial Guidance as the second component. The last component is the Logarithmic Barrier Function to satisfy the field-of-view limitation constraint by compensating the excessive total acceleration command. These three components are synthesized into a new guidance law, which involves three design parameter gains. Parameter study and numerical simulations are delivered to demonstrate the performance of the proposed repulsive function and guidance law. Finally, the guidance law simulations effectively achieve the zero terminal miss distance, while satisfying an evasive maneuver against intercept missile, considering impact angle, acceleration, and field-of-view limitation constraints simultaneously.

• Advances in aircraft and spacecraft science
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• v.7 no.1
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• pp.1-17
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• 2020

In this paper, a new model-based Fault Detection and Diagnosis (FDD) method for an agile supersonic flight vehicle is presented. A nonlinear model, controlled by a classical closed loop controller and proportional navigation guidance in interception scenario, describes the behavior of the vehicle. The proposed FDD method employs the Inertial Navigation System (INS) data and nonlinear dynamic model of the vehicle to inform fins damage to the controller before leading to an undesired performance or mission failure. Broken, burnt, unactuated or not opened control surfaces cause a drastic change in aerodynamic coefficients and consequently in the dynamic model. Therefore, in addition to the changes in the control forces and moments, system dynamics will change too, leading to the failure detection process being encountered with difficulty. To this purpose, an equivalent aerodynamic model is proposed to express the dynamics of the vehicle, and the health of each fin is monitored by the value of a parameter which is estimated using an adaptive robust filter. The proposed method detects and isolates fins damages in a few seconds with good accuracy.

• Journal of The Korean Society of Agricultural Engineers
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• v.54 no.4
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• pp.47-53
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• 2012

It is needed to install a one-way drainage filter to prevent a seepage from lake or river outside of embankment and to promote a drainage from a flood inside of embankment when dikes such as lake dike, river dike, etc are constructed. However, the results of research for one-way drainage filter are insufficient. Therefore, through the field test of one-way drainage filter, this study checked a function of one-way drainage filter with a test of performance. As a result of field test, water flow in dike was blocked in the interception direction of the section that one-way drainage filter was installed, but water passed to the flow allowance direction of the section. Therefore we confirmed the function of one-way drainage filter. Seepage quantity in the flow allowance direction of the one-way drainage filter section was low as 74.6~80.5 % than that in the section without installation of filter because of a reduction effect of seepage with filter. And seepage quantity of field test was low as 64.3~90.0 % than that in results of seepage analysis because the coefficient of permeability of embankment in field is different from the results of laboratory test. In the future, more study will be needed to solve several problems which are related to fix the filter on slide, durability of filter, etc.

• Journal of the Korean Institute of Landscape Architecture
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• v.22 no.3
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• pp.65-78
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• 1994

This study deals with the consciousness and visual preference and image about the fence that is an important factor and a vertical element in the streetscape. The analysis was performed by the data obtained from the questionnaires and the photos for the fence scene. 1. The answerers considering the fence had great influence on the beauty of a city were over 80%, also the fence influence good effect on a city was higher than 63%. 2. The answerers prefering the fence materials mixed with inanimate materials and plants was higher than 50%. Also the design offence was regarded to be the most important element when established. 3. While the satisfying factors for the visual preference were peculiarity, abundance and harmony, the dissatisfying factors were commonplaceness, disharmony and isolation(closing). Also the preference factors were the design and material in several elements of the fence. 4. At the part of function, the preferable places were estimated highly as boundary mark, eye interception but in the visual effect were so low. 5. Psychological factor, related to the satisfaction of the fence, had a grip of three factors, evaluation, formation, potentiality, and the presumption formula was: Satisfaction=1.61(Evaluation)+0.30(Formation)+0.55(Potentiality)+6.23(R2=0. 63)

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.805-809
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• 2008

Measurement of leaf area index (LAI) is useful for understanding rice growth, water use, and canopy light interception. The top nitrogen content(TNC) per unit area is an important quantitative index of the condition of nitrogen nutrition in rice production. The rapid and simple method of estimation of TNC, with the use of the existing nondestructive analyzing instruments chlorophyll meter SPAD-502 and plant canopy analyzer (PCA) LAI-2000, was scrutinized. Destructive measurement is time consuming and labor intensive. Our objective was to evaluate sampling procedures using the Li-Cor LI-1800, LAI 2000 plant canopy analyzer (PCA) for nondestructive estimation of rice LAI, and SPAD-502 on the Northern Plains of Cheongju. The LAI estimated by PCA tended to underestimate the LAI determined by actual measurement by about 20%. The estimation of LAI by PCA was judged to have a sufficient accuracy as a practical technique. A high positive correlation was obtained between the values of the SPAD reading and LAI. NDVI and LAI also showed a very high correlation. The values of the SPAD reading and LAI, and NDVI gave a high positive correlation. These results indicated that the method described in this study was effective as a simple and rapid method for the estimation of rice growth.

• Proceedings of the Korea Information Assurance Society Conference
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• 2004.05a
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• pp.125-130
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• 2004

The Internet is aggregate of trustless networks essentially. Because the Internet is very difficult to control flowing of information, taking advantage of enough sporadic resource, security problem that can protect internal important stock from the Internet is risen seriously. Recently, virus accident and generation rate about system intrusion that happen become much higher and various than past. On these time, is progressing researcher for invasion cutout to keep away illegal act vigorouslyand do continuous development. In this paper, reporting administrator log information about invader's illegal act depending on XML format form, and I wished to solve problem that happen in administration side developing invasion interception system that can control to remote.