• Journal of Institute of Control, Robotics and Systems
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• v.18 no.6
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• pp.571-578
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• 2012

In the paper, we proposed a ring type structured light image based embedded ranging sensor for a mobile robot. Since the proposed ranging sensor obtains omnidirectional object distance, it is useful for autonomous navigation of a mobile robot. By matching the local omnidirectional distance map with a given global object map, it is possible to get position and heading angle of mobile robot in the global coordinates. Experiments for matching and navigation were carried out to verify the performance of the proposed ranging sensor.

• Journal of the Korean Mathematical Society
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• v.53 no.2
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• pp.447-459
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• 2016

Let D be an integral domain, {$X_{\alpha}$} be a nonempty set of indeterminates over D, and $D{\mathbb{[}}\{X_{\alpha}\}{\mathbb{]}_1}$ be the first type power series ring over D. We show that if D is a t-SFT $Pr{\ddot{u}}fer$ v-multiplication domain, then $D{\mathbb{[}}\{X_{\alpha}\}{\mathbb{]}}_{1_{D-\{0\}}}$ is a Krull domain, and $D{\mathbb{[}}\{X_{\alpha}\}{\mathbb{]}}_1$ is a $Pr{\ddot{u}}fer$ v-multiplication domain if and only if D is a Krull domain.

• Journal of Chest Surgery
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• v.16 no.3
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• pp.337-341
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• 1983

The experience with operative treatment for total correction of Tetralogy of Fallot at the department of Thoracic and Cardiovascular Surgery, Korea University Hospital from January, 1977, through April, 1983 was reviewed. Of the 29 patients reviewed, male to female occurrence ratio was 22:7 Type of V.S.D. was type II in 26 cases[90%] and total conus defect in 3 cases[10%]. Average size of V.S.D. was 19 mm. Type of Right ventricular outflow tract stenosis was highest frequency with pulmonary valvular and infundibular stenosis combined type in 21 cases[72%], and there were 8 deaths In this group. Type of R.V.O.T. reconstruction contains 2 cases of infundibulectomy only, 1 case of infundibulectomy with valvular commissurotomy, 2 cases of pericardial patch, 23 Cases of pericardial patch with Teflon or Dacron felt reinforced and 1 case of pulmonary valved conduit reconstruction. Operative mortality was higher in outflow patch through pulmonary valve ring. Overall mortality was 31%. Major causes of death and postoperative complications were low output syndrome, complete A-V block acute renal failure, ventricular fibrillation, bleeding brain abscess, and sudden cardiac arrest.

• Journal for History of Mathematics
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• v.32 no.4
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• pp.159-173
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• 2019

In this paper, we examine the brief history of the ring of four almonds regarding Mesopotamian mathematics, and present reasons why the Omar Khayyam's triangle, a special right triangle in a ring of four almonds, was essential for artisans due to its unique pattern. We presume that the ring of four almonds originated from a point symmetry figure given two concentric squares used in the proto-Sumerian Jemdet Nasr period (approximately 3000 B.C.) and a square halfway between two given concentric squares used during the time of the Old Akkadian period (2340-2200 B.C.) and the Old Babylonian age (2000-1600 B.C.). Artisans tried to create a new intricate pattern as almonds and 6-pointed stars by subdividing right triangles in the pattern of the popular altered Old Akkadian square band at the time. Therefore, artisans needed the Omar Khayyam's triangle, whose hypotenuse equals the sum of the short side and the perpendicular to the hypotenuse. We presume that artisans asked mathematicians how to construct the Omar Khayyam's triangle at a meeting between artisans and mathematicians in Isfahan. The construction of Omar Khayyam's triangle requires solving an irreducible cubic polynomial. Omar Khayyam was the first to classify equations of integer polynomials of degree up to three and then proceeded to solve all types of cubic equations by means of intersections of conic sections. Omar Khayyam's triangle gave practical meaning to the type of cubic equation $x^3+bx=cx^2+a$. The work of Omar Khayyam was completed by Descartes in the 17th century.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.12 no.1
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• pp.49-55
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• 2016

This paper analyzed a root cause of abnormality in the temperature and vibration at generator-side bearing of motor generator set (MG Set), which is a power supply system to control element drive mechanism (CEDM) of nuclear power plants (NPPs), and modified the design of roller-type and sealing method to improve the abnormalities. From the inspection of MG Set and analysis of temperature variation during service, it was found that the abnormal temperature transition was basically associated with original design of generator-side bearing, whose roller was axially restrained by inner race, and that the abnormal vibration level was caused by inserting small chips of cage and V-ring, which were generated due to the abnormal temperature transition at roller bearing. Type of bearing and sealing method were modified based on these analyses. The temperature and vibration level measured at roller bearing showed that the modifications clearly improved the operational stability of MG Set.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.13 no.2
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• pp.160-170
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• 1988

This paper describes the outboard NIU(Network Interface Unit) using microprocessor and the hardware and software of concentrator for constructing star typed LAN(Local Area Network) based on token ring method. The NIU adapter can adapter up to four parallel and serial typed terminals. Because it has PAD function on input output data, any type of terminals can be adapted. Since the concentrator has logical switching circuit which enables data to bypass the faulted NIU adapter, this network prevents communication break. When user transmits and receives data, the concentrator constructs star typed LAN which connct both transmitting and receiving sides. A s result, this network eliminated ring latency time in other NIU exculding transmitting and receiving NIU. So the throughput of this LAN is increased. Because this LAN system consists of several modultes according to it's function, the expansion of function or the modification of method is easy.

• YAKHAK HOEJI
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• v.54 no.6
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• pp.461-465
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• 2010

We investigated the role of L-type $Ca^{2+}$ channel in receptor activator of nuclear factor-kappaB ligand (RANKL)-induced osteoclast formation. BayK 8644, a L-type $Ca^{2+}$ channel agonist, was shown to increase the RANKLinduced osteoclastogenesis and actin ring formation in mouse bone marrow-dereived macrophage (BMM) culture system. BayK 8644 stimulated RANKL-induced extracellular signal-regulated kinase (ERK) and p38 MAP kinase (MAPK) activation, which leads to increased nuclear factor of activated T cells (NFAT)c1 expression. Taken together, these data indicate that L-type $Ca^{2+}$ channel regulates osteoclast formation possibly through ERK- and p38-mediated NFATc1 expression.

• Journal of Biosystems Engineering
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• v.17 no.4
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• pp.305-313
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• 1992

Dynamic seals have been continue to be one of the major technical problems facing stirling engine designers. Most of the modern engines use some version of the dry ring seal for piston and displacer seals. Friction power losses associated with seals are typically several percent of gross output power, with piston ring seals usually being the main contributor. Much effort has been expended to develop the seal mechanism of piston, but the performance of these seal devices is very poor. This study was conducted to examine the efficiency of the various types of the trial-made piston seal mechanism with reference to leakage of working fluid and friction losses. This paper described the successful hardware implementation of a stainless steel bellows element in stirling engine application with test data in power performance. The indicated power by use of the bellows was more than two times as that by use of the piston ring types. As the result of this study, bellows was provide as a reliable and efficient seal mechanism for any stirling engine application.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.5
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• pp.3535-3541
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• 2015

In this study, series of tests were performed for drying shrinkage characteristics of concrete with power type shrinkage reducing agent (SRA) and fly ash as a part of research to reduce drying shrinkage of concrete. Firstly, for the mechanical properties, a target strength was acquired securely. In the unrestraint shrinkage tests, the SRA decreased the drying shrinkage about $200{\mu}{\varepsilon}$. Lastly, in the ring tests, due to the tensile creep effect, the concrete with SRA showed the cracking times as much again as the concrete with ordinary Portland cement only did.

• Korean Journal of Optics and Photonics
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• v.14 no.6
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• pp.649-656
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• 2003

In this paper we confirm the relation between the phase and phase error of the beat signal at the lock-in region of the dither type ring laser gyroscope by numerical calculation. We also study the requirement of the dither noise of an amplitude modulation type for statistical zero averaging of the beat signal phase error, without accumulation. As a result, we find that the dither noise requires the increase and decrease gradients of the dither amplitude, and those gradients should be combined with similar white noise. The slope of the gradient and maximum/minimum amplitude must be changed randomly. We confirm the error accumulation characteristic related to the dither noise by comparison of the two outputs during temperature change, by operating the two kinds dither noise, one is satisfied with the requirement and the other is not.