• Journal of Navigation and Port Research
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• v.34 no.5
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• pp.325-330
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• 2010

An open water rudder test was carried out to figure out the flow characteristics around a twin rudder at $Re=1.5{\times}10^4$. In the analysis, the unique characteristics of a twin rudder, which affects rudder forces, were explained. The analysis includes varying angles of attack from 10 to 30 degrees. In this paper, the measured results have been compared with each other to predict the performance characteristics of a twin rudder's 2-dimensional section by 2-frame grey level cross correlation PIV method. The length L=0.75C between upper and lower rudders could be defined as the critical length.

• Korean Journal of Materials Research
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• v.10 no.10
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• pp.715-720
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• 2000

By the mechanical alloying method. Ni-WC composite materials were prepared to improve the deformation-resistance for creep and sintering of Ni-anode at the operating temperature of $650^{\circ}C$. Mechanically alloyed powder w was initially fabricated by ball milling for 80hr, and then amorphization was occurred by the destruction of ordered crystals based on XRD analysis. In order to investigate the electrochemical performance and sheet characteristics of Ni-WC anode, tape casting process was adopted. Finally, the obtained sheet thickness of Ni- we after sintering at $1180^{\circ}C$ for 60 minutes in $H_2$ atmosphere was O.9mm and the average pore size was $3~5{\mu\textrm{m}}$ with porosities of 55%. The second phase was not observed in Ni- W matrix while W particles were finely and uniformly distributed in Ni matrix. This fine and uniform distributed W particles in Ni matrix are expected to enhance the mechanical properties of Ni anode through the dispersion and solid solution hardening mechanisms.

• Korean Journal of Remote Sensing
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• v.23 no.4
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• pp.273-285
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• 2007

Most stereo matching methods use intensity values in small image patches to measure the correspondence between two points. If the noisy pixels are used in computing the corresponding point, the matching performance becomes low. For this reason, the noise plays a critical role in determining the matching performance. In this paper, we propose a method for combining intensity and edge filters robust to the noise in order to improve the performance of stereo matching using high resolution satellite imagery. We used intensity filters such as Mean, Median, Midpoint and Gaussian filter and edge filters such as Gradient, Roberts, Prewitt, Sobel and Laplacian filter. To evaluate the performance of intensity and edge filters, experiments were carried out on both synthetic images and satellite images with uniform or gaussian noise. Then each filter was ranked based on its performance. Among the intensity and edge filters, Median and Sobel filter showed best performance while Midpoint and Laplacian filter showed worst result. We used Ikonos satellite stereo imagery in the experiments and the matching method using Median and Sobel filter showed better matching results than other filter combinations.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.7
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• pp.167-175
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• 1996

Work roll wear in the cold rolling of steel strip is strongly affected by rolling materials, rolling conditions and lubrication. Tests were performed to find the effects of rolling materials under the same lubricating conditions. Surface roughness of cold rolled steel strip as well as the coating technique itself is quite improtant in obtaining high image clarity of electronic products and car outer panels. Therefore this paper reviews for improvement of roughness and peak count about the surface of Cr coated work roll is investigated from the actual temper mill. The conclusions were obtained as follows; 1) Work roll wear in the cold rolling of steel strip is strongly affected by carbon contents of rolling materials, but there is not a separating force and total reduction ratio. 2) The roughness of strip surface is larger in the direction of width than in roll direction. 3) The electro-discharge textured roll has more uniform roughness distribu- tion than shot blasted roll and it's life time is two times longer than shot blasted because it has more harmonic wave roughness, and the higher peak count of surface roughness. 4) The life time of Cr coated work roll is 2 times longer than that of shot blasted work roll and variation of peak count, roughness and life time of Cr coated work roll is similar to electro-discharge texturing work roll. 5) The proper Cr coating thickness is 10 .mu. m at the work roll of temper mill.

• Journal of Information Technology Applications and Management
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• v.31 no.4
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• pp.139-148
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• 2024

This study takes a comprehensive look at how technological advances have changed the way 2D animation is created. Humans are constantly looking for new ways and technologies to express movement, which has led to many changes in the way 2D animation is produced. In this study, we will examine the impact of these changes on 2D animation production and explore the possibilities for future developments. In the early days of 2D animation, the production method was repeatedly changed by the invention of technologies such as celluloid sheets, rotoscopes, and multiplane cameras, while the advent of digital technology has led to revolutionary changes such as the development of CAPS(computer animation production systems), various digital tools, and the combination of 2D and 3D. In addition, the recent introduction of generative AI is rapidly changing the way 2D animation is produced by automatically handling various tasks. These advances have not only streamlined the production of animation, but have also reduced costs by shortening the production period, and greatly improved the quality of animation by making it easier to implement complex and sophisticated visual effects. The introduction of generative AI has pushed the boundaries of what can be represented in 2D animation. On the other hand, the introduction of digital technology has its drawbacks, as the mechanical and uniform style produced by digital tools can reduce originality and individuality, but advances in technology will open up the possibilities for 2D animation to be produced in a variety of ways, as it fosters the creation of new expressions and creative content.

• Korean Journal of Agricultural Science
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• v.50 no.3
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• pp.415-424
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• 2023

The task of sorting and excluding blemished apples and others that lack commercial appeal is currently performed manually by human eye sorting, which not only causes musculoskeletal disorders in workers but also requires a significant amount of time and labor. In this study, an automated apple-sorting machine was developed to prevent musculoskeletal disorders in apple production workers and to streamline the process of sorting blemished and non-marketable apples from the better quality fruit. The apple-sorting machine is composed of an arm-rest, a main body, and a height-adjustable part, and uses object detection through a machine learning technology called 'You Only Look Once (YOLO)' to sort the apples. The machine was initially trained using apple image data, RoboFlow, and Google Colab, and the resulting images were analyzed using Jetson Nano. An algorithm was developed to link the Jetson Nano outputs and the conveyor belt to classify the analyzed apple images. This apple-sorting machine can immediately sort and exclude apples with surface defects, thereby reducing the time needed to sort the fruit and, accordingly, achieving cuts in labor costs. Furthermore, the apple-sorting machine can produce uniform quality sorting with a high level of accuracy compared with the subjective judgment of manual sorting by eye. This is expected to improve the productivity of apple growing operations and increase profitability.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.43 no.2 s.308
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• pp.40-47
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• 2006

This paper proposes a multitoning method using threshold modulation of MJBNM(Modified Jointly Blue Noise Mask) for banding artifacts reduction. As banding artifacts in multitoning appear as uniform dot distributions around the intermediate output levels, such multitone output results in discontinuity and visually unpleasing patterns in smooth transition regions. Therefore, to reduce these banding artifacts, the proposed method rearranges the dot distribution by introducing pixels in the neighborhood of output levels that occurs banding artifacts. First of all principal cause of banding artifacts are analyzed using mathematical description. Based on this analytical result, a threshold modulation technique of MJBNM which takes account of chrominance error and correlation between channels is applied. The original threshold range of MJBNM is first scaled linearly sot that the minimum and maximum of the scaled range include two pixel more than adjacent two output levels that cover an input value. In an input value is inside the vicinity of any intermediate output levels produce banding artifacts, the output is set to one of neighboring output levels based on the pointwise comparison result according to threshold modulation parameter that determines the dot density and distribution. In this case, adjacent pixels are introduced at the position where the scaled threshold values are located between two output levels and the minimum and maximum threshold values. Otherwise, a conventional multitoning method is applied. As a result, the proposed method effectively decreased the appearance of banding artifacts around the intermediate output levels. To evaluate the quality of the multitone result, HVS-WRMSE according to gray level for gray ramp image and S-CIELAB color difference for color ramp image are compared with other methods.

• Progress in Medical Physics
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• v.21 no.1
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• pp.9-15
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• 2010

Scatter radiation considerably affects radiographic image quality by reducing image contrast and contributing to a non-uniform background. Images containing a large portion of scatter radiation may result in an incorrect diagnosis. In the past few years, many efforts have been made to reduce the effects of scatter radiation on radiographic images. The purpose of this study is to accurately measure scatter fractions and evaluate the effectiveness of beam-stop arrays. To measure scatter fraction accurately, a beam-stop array and the SFC (Scatter Fraction Calculator) program were developed. Images were obtained using the beam-stop array for both an anti-scatter technique with an anti-scatter grid and an air gap technique. The scatter fractions of the images were measured using the SFC program. Scatter fractions obtained with an anti-scatter grid were evaluated and compared to scatter fractions obtained without an anti-scatter grid. Scatter fractions were also quantitatively measured and evaluated with an air gap technique. The effectiveness of the beam-stop array was demonstrated by quantifying scatter fractions under various conditions. The results showed that a beam-stop array and the SFC program can be used to accurately measure scatter fractions in radiographic images and can be applied for both developing scatter correction methods as well as systems.

• The Journal of Korean Academy of Prosthodontics
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• v.36 no.6
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• pp.858-866
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• 1998

Soldering is the usual method used to correct an unstable fixed partial denture framework at patient's try-in; However, presoldering base metal alloys is technique-sensitve and results are unstable because it is difficult to maintain uniform heat distribution and to prevent oxidation of an alloy. A cast-joining technique has been developed by Weiss and Munyon for repair, correction and addition to base metal framework. This joining technique eliminates the problem with presoldering of non-precious frameworks. The object of this study was to 1) compare the relative flexure strength and the joining effectiveness of Ni-Cr-Be cast in two pieces and 'pre-soldered' versus in two pieces and 'cast-joined'. 2) determine the effect of increasing the number of retentive grooves on the face of the cast and 3) determine the effect of the relative matched position of groove patterns on flexure strength. The joining effectiveness can be expressed by the ratio of the mean flexure stress of soldered or cast-joined specimens to that of one-piece cast. Resin rods 3mm in diameter were used as pattern of specimens for one-piece casted, presoldered, and cast-joined groups. Cast-joined specimens had two different patterns of retentive grooves on the joined faces. Type A had cross-shaped grooves 1mm in depth. 0.6mm in width. Type B was the same except for the addition of one more retentive groove. In the experiment connecting cast-joined specimens, half of specimens with type A pattern had their patterns on the faces of paired casts matched with each other as mirror image. With the rest pairs, it was proceeded that one of paired casts turned 45 degrees so that the patterns crossed. Half of specimens with type B pattern also had the patterns matched as mirror image; However, here, one of paired casts turned 90 degrees with the other pairs. Retentive groove in this study lacked the intentional undercuts, in contrast with the suggestion of Weiss and Munyon. The specimens were subjected to four-point flexural loading in an Instron testing machine. The midspan flexural stress was calculated at the point of initial plastic strain as determined from a strip-chart recorder or at the point of failure if this occured at a lower stress level. Within the scope of this study, the following results were obtained. 1. The presoldered group showed flexural strength at least 2 times higher than the cast-joined groups. Its joining effectiveness was 82%. 2. In cast-joined groups, the flexural strength of joints with type B patterns exhibited 1.5 times that of joints with type A patterns. Joining effectivenesses were 38% for type B patterns, 25-26% for type A patterns. 3. The relative matched position of groove patterns did not have any significant effect on flexural strength of the cast-joined specimens with either type A patterns or type B patterns(p>.05).

• Journal of radiological science and technology
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• v.38 no.4
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• pp.421-427
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• 2015

In this study, we have observed the change of the Hounsfield (HU) in the alteration of by changing in size of physical area and setting size of region of interest (ROI) at focus on kVp and mAs. Four-channel multi-detector computed tomography was used to get transverse axial scanning images and HU. Three dimensional printer which is type of fused deposition modeling (FDM) was used to produce the Phantom. The structure of the phantom was designed to be a type of cylinder that contains 33 mm, 24 mm, 19 mm, 16 mm, 9 mm size of circle holes that are symmetrically located. It was charged with mixing iodine contrast agent and distilled water in the holes. The images were gained with changing by 90 kVp, 120 kVp, 140 kVp and 50 mAs, 100 mAs, 150 mAs, respectively. The 'image J' was used to get the HU measurement of gained images of ROI. As a result, it was confirmed that kVp affects to HU more than mAs. And it is suggested that the smaller size of physical area, the more decreasing HU even in material of a uniform density and the smaller setting size of ROI, the more increasing HU. Therefore, it is reason that to set maximum ROI within 5 HU is the best way to minimize in the alteration of by changing in size of physical area and setting size of region of interest.