• Journal for History of Mathematics
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• v.28 no.5
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• pp.207-231
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• 2015

We discuss several issues relating to the meaning of the terms and phrases in the first half of Chapter One fang tian 方田章 of ${\ll}$Jiuzhang suanshu九章算術${\gg}$. I understood those issues more clearly in the course of the translation of ${\ll}$Kujang sulhae 九章術解${\gg}$. Those are '今有' in the beginning of each problem, '積' and '冪' in the method of square field 方田術, '齊' in the method of reduction to a common denominator 齊同術, '經' and '有分者通之重有分者同而通之' in the method of dividing fraction 經分術, '實如法而一' in the calculation using the rods, '兩邪' in the method of trapezium field with a perpendicular side 邪田術. We may find out the value of ${\ll}$Kujang sulhae 九章術解${\gg}$ through our discussion.

• The Mathematical Education
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• v.46 no.3
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• pp.245-261
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• 2007

This paper deals with the possible problems which may arise when students learn the names of elementary geometric figures in the languages of Korean, Chinese, English. The names of some simple geometric figures in these languages are analyzed, and a specially designed test was administered to some grade eight students from the three language groups to explore the possible influence of the characteristics of the languages on students' capability in identifying the figures, the way students define the figures, and students' understanding of the inclusive relationship among figures. It was found that the usage of the terms to describe geometric figures may indeed have affected students' understanding of the figures. The names of geometric figures borrowed from those of everyday life objects may cause students to fix on some attributes of the objects which may not be consistent with the definition of the figures. Even when the names of the geometric figures depict the features of the figures, the words used in the naming of the figures may still affect students' understanding of the inclusive relations. If there is discrepancy between the definition of a geometric figure and the features that the name depicts, it may affect students' understanding of the definition of the figure, and if there is inconsistency in the classification of figures, it may affect students' understanding of the inclusive relationship involving those figures. Some implications of the study are then discussed.

• Journal of The Korean Astronomical Society
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• v.20 no.1
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• pp.1-26
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• 1987

By inverting the brightness integral for the dust-scattered continuum, we have determined how the dust grains are distributed inside the Orion nebula. The scattering characteristics of the Orion dust at a given wavelength is kept constant within the nebula, and the geometry of the nebula is assumed to have a hemispherical shape. The resulting radial distance dependence of the distribution of dust number density, $N_d(r)$, shows that the dust grains are depleted at the central region of the Orion nebula and concentrated in the region $5'{\sim}6'$ away from the Trapezium stars. The scattering characteristics of the Orion dust are of moderately forward throwing nature, and the Orion dust has low values of albedo.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.2
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• pp.36.1-36.1
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• 2015

We present $5-14{\mu}m$ Infrared Spectrograph spectra of 14 T Tauri stars which show Polycyclic Aromatic Hydrocarbon (PAH) features and reside in 0.7 pc from ${\Theta}_1$ Ori C. The spectral types of nine out of 11 stars have spectral type information, with types ranging from K7-M5. These stars do not supply strong enough UV photons to excite PAH emission in their disks. Therefore, we consider the detection of PAH emission in disks around low mass stars illuminated by an external source of UV photons, namely, from Trapezium OB association, including ${\Theta}_1$ Ori C. The morphological features of PAH emission from most disks around K-M type host stars are unique, not belonging to any known classes of PAH features. We found that the PAH emission strengths decrease as the projected distance of the objects from ${\Theta}_1$ Ori C increase. We suggest future far-IR and submm/mm observations for better understanding of the characteristics and distribution of PAHs in these disks.

• The Transactions of the Korean Institute of Power Electronics
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• v.27 no.3
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• pp.200-205
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• 2022

This paper presents an improved maximum power point tracking method that can fast track the global maximum power point (GMPP) for a photovoltaic system under partial shading conditions. The proposed method combines the advantages of the maximum power trapezium (MPT) method and the search-skip-judge method to minimize the tracking voltage intervals. Thus, the proposed method can quickly track the GMPP by skipping unnecessary tracking voltage intervals. The superiority of the proposed method is verified through simulation results in the MATLAB/Simulink and experimental real-time operation results with the hardware-in-the-loop simulation. The simulation and experimental results demonstrated that the proposed method has a faster tracking time than the MPT method under various partial shading conditions.

• The Journal of the Korean bone and joint tumor society
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• v.13 no.2
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• pp.124-129
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• 2007

Synovial sarcomas of the hand are rare. It should be treated with wide resection. In the cases of soft tissue sarcomas of the hand, functional reconstruction must be considered. We report 46-year-old male patient with synovial sarcoma of the right thenar muscle which was treated with unplanned intralesional resection at outside hospital, that has been treated with wide resection including trapezium and first metacarapl bone then, reconstructed with nonvascularized fibular graft and anterolateral thigh free flap.

• International Journal of Naval Architecture and Ocean Engineering
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• v.11 no.1
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• pp.344-352
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• 2019

Marine production strings are continuously affected by unstable internal fluid during operation. In this paper, the structural governing equation for marine production string self-induced vibration is constructed. A finite element analysis model is established based on Euler-Bernoulli theory and solved by the Newmark method. Furthermore, based on reliability theory, a self-design procedure is developed to determine the operability envelope for marine production string self-induced vibration. Case studies show: the response frequency of the production strings is consistent with the excitation frequency under harmonic fluctuation and mainly determined by the first-order natural frequency under stochastic fluctuation. The operability envelope for marine production string self-induced vibration is a near symmetrical trapezium. With the increasing of natural gas output, the permissible fluctuation coefficient dramatically decreases. A reasonable centralizer spacing, increasing top tension, and controlling natural gas output are of great significance to the risk control in marine production string operation.

• Archives of Hand and Microsurgery
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• v.23 no.4
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• pp.223-229
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• 2018

Purpose: A number of procedures were introduced to stabilize the 1st metacarpal bone after resection of the trapezium in the thumb carpometacarpal joint (CMCJ) arthroplasty. However, some surgical procedures may inevitably damage normal structures, such as harvesting tendons or drilling of a bone for tendon passage. Suture suspension arthroplasty is relatively less invasive and easier to perform than the previously described surgical methods. The purpose of this study was to report the therapeutic efficiency of the suture suspension arthroplasty. Methods: We retrospectively reviewed 12 patients who underwent suture suspension arthroplasty for the treatment of thumb CMCJ arthritis. Pain visual analogue scale (VAS), satisfaction about surgical outcomes, and the disabilities of the arm, shoulder and hand (DASH) scores were measured to evaluate the functional outcomes and the Trapezial Space Ratios were measured. Satisfaction was measured in the range of "very dissatisfied" (0) to "very satisfied" (10). Results: The mean follow-up period was 23 months. Pain VAS score improved significantly from 7.0 to 2.9 (p<0.05). And mean satisfaction scale was 6.9. However, there was no significant difference in DASH scores between before and after surgery (p=0.06). The mean trapezial space ratio was calculated to be 0.45 before surgery, 0.33 immediately after surgery, 0.23 at the last follow-up. Conclusion: Suture suspension arthroplasty is a satisfactory surgical procedure. And compared with other procedures, there is no significant difference in the reduction of the trapezial space. It may be useful in advanced thumb CMCJ arthritis.