• Transactions of Materials Processing
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• v.6 no.5
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• pp.400-407
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• 1997

Geometric mapping technique has been used to find the shape of initial blank for sheet forming. The method was chosen because of its simplicity and numerical efficiency. Error in blank shape were measured along deformation path by FE analysis of forming. Blank shape was modified by volume additionaddition/Subtractiontraction method with taking with taking into account of deformation path. Modified blank shape shows an acceptable result, showing the current method can be an useful tool for predicting blank shape in the practical application. More test will be done to verify the validity of the method.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.3 no.3
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• pp.597-605
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• 1999

In this paper, we propose a cardioangiography sequence image coding scheme which use a subtraction between initial image and current frame inserted contrast dye. Stable regions are obtained by the multithreshold and meaningful region is extracted by the images with stable region. The image with meaningful region is classified into contour and texture information. Contour information is coded by contour coding. And texture information is approximated by two-dimensional polynomial function and each coefficients is coded. Experimental results confirm that the sequence of cardioangiography are well reconstructed at the low bit rate (0.02∼0.04 bpp) and high compression ratio.

• Journal of the Korean Society of Industry Convergence
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• v.23 no.2_1
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• pp.107-113
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• 2020

Additive manufacturing(AM) can create complex shapes directly in 3D CAD models with internal geometry compared to conventional subtraction manufacturing. AM technology has the advantage of adopting various materials as well as the reduction of material. However, the high cost of AM is still a significant barrier preventing the wider adoption of AM in industries. This paper analyzes the technical application cases for solving these entry barriers and proposes a bi-metal 3D printing technology as an anticipated application to overcome the difficulty. The paper investigates the complications for current 3D metal printing technology to conduct bi-metal 3D printing and addresses ongoing solution research based on laser technology.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.8C
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• pp.712-719
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• 2007

In this paper, we propose a new, effective, fast motion estimation algorithms using $4{\times}4$ pixels Hadamard transform. The Hadamard transform has the advantage of simplicity because it uses only addition and subtraction. Motion estimation is composed of three stages. First, it should be decided whether to terminate the search early and use a previous motion vector with DC(Direct Current) coefficients. Then the adaptive matching scan order for motion estimation should be determined according to the image complexity using AC(Alternating Current) coefficients. Experimentally, we adapted this algorithms to MVFAST and PMVFAST algorithms, and the proposed algorithms turn out to be very efficient in terms of computational speed while remaining almost the same in terms of PSNR(Peak Signal-to-Noise Ratio) compared to MVFAST and PMVFAST algorithms.

• Publications of The Korean Astronomical Society
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• v.32 no.1
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• pp.25-27
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• 2017

We are creating all-sky diffuse maps from the AKARI mid-infrared survey data with the two photometric bands centered at wavelengths of 9 and $18{\mu}m$. The AKARI mid-infrared diffuse maps achieve higher spatial resolution and higher sensitivity than the IRAS maps. In particular, the $9{\mu}m$ data are unique resources as an all-sky tracer of the emission of polycyclic aromatic hydrocarbons (PAHs). However, the original data suffer many artifacts. Thus, we have been developing correction methods. Among them, we have recently improved correction methods for the non-linearity and the reset anomaly of the detector response. These corrections successfully reduce the artifact level down to $0.1MJy\;sr^{-1}$ on average, which is essential for discussion on faint extended emission (e.g., the Galactic PAH emission). We have also made progress in the subtraction of the scattered light caused in the camera optics. We plan to release the improved diffuse maps to the public within a year.

• Journal of Broadcast Engineering
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• v.21 no.2
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• pp.268-271
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• 2016

In video sequences, foreground object detection being composed of a background model and a background subtraction is an important part of diverse computer vision applications. However, object detection might fail in sudden illumination changes. In this letter, an illumination-robust background detection is proposed to address this problem. The method can provide quick adaption to current illumination condition using two background models with different adaption rates. Since the proposed method is a non-parametric approach, experimental results show that the proposed algorithm outperforms several state-of-art non-parametric approaches and provides low computational cost.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.109-113
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• 2001

Exhaustion and environmental problem are big problem of 21th century is flint energy and the importance of energy to alternate flint energy as being risen is embossed more. Photovoltaic system is occupying big flow along with wind force development among is many substitute energy has shortcoming that energy conversion efficiency falls behind than another thing substitute energy, This research investigates electron beam to specification energy to Module that was generalized and schematized difference of curved line after existing V-I efficiency characteristic curve and irradiation. And will analyze cause of Module's efficiency addition and subtraction by electron beam investigation.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.8
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• pp.20-26
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• 2001

In this paper, the charge pump PLL using the dual PFD to improve the trade-off between acquisition behavior and locked behavior is proposed. This dual PFD consists of a positive edge triggered PFD and a negative edge triggered PFD. The proposed charge pump shows that it is possible to overcome the issue of the charge pump current imsmatch by the current subtraction circuit. Also, this charge pump can suppress reference spurs and disturbance of the VCO control voltage. The proposed charge pump PLL is simulated by SPICE using 0.25${\mu}m$ CMOS process parameters.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.8
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• pp.848-855
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• 2008

In this paper, we describe correspondence among multiple images taken by multiple cameras. The correspondence among multiple views is an interesting problem which often appears in the application like visual surveillance or gesture recognition system. We use the principal axis and the ground plane homography to estimate foot of human. The principal axis belongs to the subtracted silhouette-based region of human using subtraction of the predetermined multiple background models with current image which includes moving person. For the calculation of the ground plane homography, we use landmarks on the ground plane in 3D space. Thus the ground plane homography means the relation of two common points in different views. In the normal human being, the foot of human has an exactly same position in the 3D space and we represent it to the intersection in this paper. The intersection occurs when the principal axis in an image crosses to the transformed ground plane from other image. However the positions of the intersection are different depend on camera views. Therefore we construct the correspondence that means the relationship between the intersection in current image and the transformed intersection from other image by homography. Those correspondences should confirm within a short distance measuring in the top viewed plane. Thus, we track a person by these corresponding points on the ground plane. Experimental result shows the accuracy of the proposed algorithm has almost 90% of detecting person for tracking based on correspondence of intersections.

• Journal of Korean Neurosurgical Society
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• v.62 no.5
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• pp.526-535
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• 2019

Objective : While the risk of aneurysmal rebleeding induced by catheter cerebral angiography is a serious concern and can delay angiography for a few hours after a subarachnoid hemorrhage (SAH), current angiographic technology and techniques have been much improved. Therefore, this study investigated the risk of aneurysmal rebleeding when using a recent angiographic technique immediately after SAH. Methods : Patients with acute SAH underwent immediate catheter angiography on admission. A four-vessel examination was conducted using a biplane digital subtraction angiography (DSA) system that applied a low injection rate and small volume of a diluted contrast, along with appropriate control of hypertension. Intra-angiographic aneurysmal rebleeding was diagnosed in cases of extravasation of the contrast medium during angiography or increased intracranial bleeding evident in flat-panel detector computed tomography scans. Results : In-hospital recurrent hemorrhages before definitive treatment to obliterate the ruptured aneurysm occurred in 11 of 266 patients (4.1%). Following a univariate analysis, a multivariate analysis using a logistic regression analysis revealed that modified Fisher grade 4 was a statistically significant risk factor for an in-hospital recurrent hemorrhage (p=0.032). Cerebral angiography after SAH was performed on 88 patients ${\leq}3$ hours, 74 patients between 3-6 hours, and 104 patients >6 hours. None of the time intervals showed any cases of intra-angiographic rebleeding. Moreover, even though the DSA ${\leq}3$ hours group included more patients with a poor clinical grade and modified Fisher grade 4, no case of aneurysmal rebleeding occurred during erebral angiography. Conclusion : Despite the high risk of aneurysmal rebleeding within a few hours after SAH, emergency cerebral angiography after SAH can be acceptable without increasing the risk of intra-angiographic rebleeding when using current angiographic techniques and equipment.