• Journal of Korean Society for Quality Management
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• v.44 no.3
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• pp.553-564
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• 2016

Purpose: The purpose of this study was to propose useful suggestions by analyzing reliability of guided missile using field data in Military industry. Methods: The collected data from Defense industry company and the military were analyzed using probit analysis which is non-linear model because field data contain binary variable. Results: The results of this study are as follows; It was found that the effect of time was significant. It takes about 12.4 years when 10st percentile of guided missiles are not working and it takes about 18.6 years when 50st percentile of guided missiles are not working. It was found that period between 10years to 15years comes less than reliability 0.0. Conclusion: Periodical check needs to extend from 4 year to 10 year partially. Early LOT need to check per 4 year and follow-up LOT extend the period of check to 10 year by reflecting the result of reliability.

• Korean Journal of Computational Design and Engineering
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• v.19 no.4
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• pp.340-346
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• 2014

There are many factors that contribute to hit probability of the gun shot of ground combat vehicles. Aiming accuracy is mainly affected by the dynamic state of the vehicle. The stabilization error of the turret under system vibration is one of the major factors that affect the aiming accuracy. The vibration of the vehicle is affected by both the state of the road and the speed of the vehicle. This paper analyzes the aiming accuracy of the gun equipped on the GCV when the vehicle drives on the different roads and at different speed. The vertical displacement and the pitch angle of the gun are calculated and the impact points of the target are calculated. Distribution of the impact points on the target is greatly influenced by the pitch rotation rather than vertical displacement. And this aiming errors result in the errors of point of impacts on the target after the bullet flies through the air under trajectory equations. The GCV is modeled using a half-car model with 6 D.O.F. and the specifications of the M2 machine gun are used in trajectory calculation simulation and the target is located in 1000 m away from the gun.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.154-156
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• 2017

Constant variance of degradation data over time has been generally assumed to estimate storage lifetime using destructive, accelerated degradation data over time. However, performance data of ammunitions deteriorate over time, and the standard deviation would tend to increase over time. This paper shows storage lifetime comparison results for constant variance and time-variant variance assumptions of degradation data over time, and proposes that time-variant variance assumption should be considered to increase accuracy in lifetime estimation.

• Journal of Biomedical Engineering Research
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• v.26 no.1
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• pp.1-7
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• 2005

This study aimed to investigate the hypothesis that administration of the air with 30% oxygen compared with normal air (21% oxygen) enhances cognitive functioning through increased activation in the brain. Seventeen college students (right­handed, average age of 24.3) were selected as subjects for this study. An oxygen supply equipment that provides 21% and 30% oxygen at a constant rate of 8L/min was developed. In order to measure the performance level of visuospatial and verbal cognition, two psychological tests were developed. The experiment consisted of two runs, one for cognition task with normal air (21% oxygen) and the other for cognition task with hyperoxic air (30% oxygen). Visuospatial and verbal tasks were presented while brain images were scanned by a 3T fMRI system using the single-shot EPI method. The results showed that there was an improvement in performance and also increased activation in several brain areas in the higher oxygen condition. These results suggest that while performing cognitive tasks, high concentrations of oxygen administration make oxygen administration sufficient, thus making neural network activate more, and the ability to perform cognitive tasks increase.

• International Journal of Internet, Broadcasting and Communication
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• v.11 no.4
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• pp.76-85
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• 2019

We introduce a vision-based object detection method for real-time video surveillance system in low-end edge computing environments. Recently, the accuracy of object detection has been improved due to the performance of approaches based on deep learning algorithm such as Region Convolutional Neural Network(R-CNN) which has two stage for inferencing. On the other hand, one stage detection algorithms such as single-shot detection (SSD) and you only look once (YOLO) have been developed at the expense of some accuracy and can be used for real-time systems. However, high-performance hardware such as General-Purpose computing on Graphics Processing Unit(GPGPU) is required to still achieve excellent object detection performance and speed. To address hardware requirement that is burdensome to low-end edge computing environments, We propose sub-frame analysis method for the object detection. In specific, We divide a whole image frame into smaller ones then inference them on Convolutional Neural Network (CNN) based image detection network, which is much faster than conventional network designed forfull frame image. We reduced its computationalrequirementsignificantly without losing throughput and object detection accuracy with the proposed method.

• Journal of the Korean Society for Heat Treatment
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• v.34 no.4
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• pp.185-190
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• 2021

The extrusion experiments using the 7075 aluminum billet have been performed to investigate the effects of die cooling and ram speed on the occurrence of surface defects on the extrudate. The purpose of die cooling was to suppress overheating of the extrudate at the moment of extrusion. In the present die cooling system, liquid nitrogen has been injected in to the die and sprayed to the surface of extrudate. Ram speed was either kept or varied in the range of 1.1~1.7 mm/sec. throughout one extrusion shot to check the occurrence of surface defects. Every extrusion started at a ram speed of 1.25 mm/sec. The temperature of extrudate was measured using a laser thermometer. The 7075 billet of 180 mm in diameter and 550 mm in length was preheated at 390℃ and extruded to get a single plate of 8000 mm in length, 150 mm in width and 10 mm in thickness. Each extrudate was checked by eye to find the surface defects. The microstructures were obtained in the specimen cut from each corner of the extrudate using the EBSD micrographs.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.22 no.1
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• pp.67-80
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• 2024

Fundamental aspects of creating passivation layers for corrosion resistance in nuclear engineering applications, specifically the ability to form complete layers versus porous ones, are being explored in this study. Utilizing a laser ablation technique, 1,064 nm fire at 10 Hz with 60 pulses per shot and 0.5 mm between impact points, aluminum samples are treated in an attempt to create a fully formed passivation layer that will be tested in a LiCl-KCl eutectic salt. By placing these samples into an electrochemical environment mimicking a pyroprocessing system, corrosion rates, resistances and material characteristics are tested for one week and then compared between treated and untreated samples. In initial testing, linear sweep voltammetry indicates corrosion current density for the untreated sample at -0.038 mA·cm^-2 and treated samples at -0.024 mA·cm^-2 and -0.016 mA·cm^-2, respectively. This correlates to a control sample corrosion rate of -0.205 mm·yr^-1 and treated rates of -0.130 mm·yr^-1 and -0.086 mm·yr^-1 for samples 1 and 2. In addition, electrochemical impedance spectroscopy circuits show application of a longer-lasting porous passivation layer on the treated metal, compared to the naturally forming layer. However, the current technique fails to create a uniform protection layer across the sample.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.218.2-218.2
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• 2012

In the remote sensing researches, the reflected bright source such as snow, cloud have effects on the image quality of wanted signal. Even though those signal from bright source are adjusted in corresponding pixel level with atmospheric correction algorithm or radiometric correction, those can be problem to the nearby signal as one of the stray light source. Especially, in the step and stare observational method which makes one mosaic image with several snap shots, one of target area can affect next to the other snap shot each other. Presented in this paper focused on the stray light analysis from unwanted reflected bright source for geostationary ocean color sensor. The stray light effect for total 16 slot images each other were performed according to 8 band filters. For the realistic simulation, we constructed system modeling with integrated ray tracing technique which realizes the same space time in the remote sensing observation among the Sun, the Earth, and the satellite. Computed stray light effect in the results of paper demonstrates the distinguishable radiance value at the specific time and space.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2004.04a
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• pp.389-394
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• 2004

Structure-typed cultural heritage, objects of preservation are positioned as one of the very important heritage in the nation, and the preservation of prototypical structures become influential in national development and against natural disaster. For this reason, Digital Close Range Photogrammetry has recently been diversely used. Despite its popular use, the measurement has limits that make it unsuitable for photographing precise cultural heritage situated at high mountainous terrain or where people can not approach easily. These high gigantic stone statues are among the preserved structure-typed cultural heritage. In order to supplement the limits, when using the measurement, a camera tripod with +30m, a ladder truck and a shore should be equipped, which means additional equipment leads to it being a waste of cost and time. In this vein, a device was developed in detail, using a RC Helicopter installed with a CCD video camera with ease of control, safety, equipment, carrying, movement and approach, then checked image shot by a wireless modem at real time and considered the economical efficiency without re-photographing. Next, the author digitized the images of the nationally designated structure-typed cultural heritage, used materials on their restoration as the third dimension in order to construct the integrated management-information system for cultural heritage. Through the above processes, this study can provide specific information on 3D images and 3D CAD sections of structured-typed cultural heritage for both the public and specialists on the web. Moreover, it suggests the foundation to restore the damaged cultural heritage in the future by aiming for their effective management and preservation.

• Proceedings of the KSMRM Conference
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• 2001.11a
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• pp.111-111
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• 2001

목적： To evaluate the feasibility of the event-related functional MR study using power grip studying the hand motor system 대상 및 방법： Event-related functional MRI was performed on a 1.5T MR unit in seven norm volunteers (man=7, right-handedness=2, left-handedness=5, mean age： 25 years). A single-shot GRE-EPI sequence (TR/TE/flip angle： 1000ms/40ms/90, FOV = 240 mm matrix= 64$\times$64, slice thickness/gap = 5mm/0mm, 7 true axial slices) was used for functiona MR images. A flow-sensitive conventional gradient echo sequence (TR/TE/flip angl 50ms/4ms/60) was used for high-resolution anatomical images. To minimize the gross hea motion, neck-holders (MJ-200, USA) were used. A series of MR images were obtained in axial planes covering motor areas. To exclude motion-corrupted images, all MR images wer surveyed in a movie procedure and evaluated using the estimation of center of mass of ima signal intensities. Power grip task consisted of the powerful grip of all right fingers and hand movement ta used very fast right finger tapping at a speed of 3 per 1 second. All tasks were visual-guid by LCD projector (SHARP, Japan). Two tasks consisted of 134 phases including 7 activatio and 8 rest periods. Active stimulations were performed during 2 seconds and rest period were 15 seconds and total scan time per one task was 2 min 14 sec. Statistical maps we obtained using cross-correlation method. Reference vector was time-shifted by 4 seconds an Gaussian convolution with a FWHM of 4 seconds was applied to it. The threshold in p val for the activation sites was set to be 0.001. All mapping procedures were peformed usin homemade program an IDL (Research Systems Inc., USA) platform. We evaluated the activation patterns of the motor system of power grip compared to hand movement in t event-related functional MRI.