• Journal of Ocean Engineering and Technology
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• v.19 no.1 s.62
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• pp.87-94
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• 2005

This paper investigates the constant-level luffing and time optimal control of jib cranes. The constant-level luffing, which is the sustainment of the load at a constant height during luffing, is achieved by analyzing the kinematic relationship between the angular displacement of a boom and that of the main hoist motor of a jib crane. Under the assumption that the main body of the crane does not rotate, the equations of motion of the boom are derived using Newton's Second Law. The dynamic equations for the crane system are highly nonlinear; therefore, they are linearized under the small angular motion of the load to apply linear control theory. This paper investigates the time optimal control from the perspective of no-sway at a target point. A stepped velocity pattern is used to design the moving path of the jib crane. Simulation results demonstrate the effectiveness of the time optimal control, in terms of anti-sway motion of the load, while luffing the crane.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.10
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• pp.3641-3646
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• 2010

In this study, the deformation analysis is done at tower crane by applying the load at the end of jib and the moment at mast. The greatest stain and stress are happened at the end of wire supporting jib. The great deformation takes place at the end of jib applied by stress and there is no deformation at the lower part of mast. As the life becomes smallest at the upper part of mast, this part becomes weakest. The safety design and durability can be improved by applying the result of structural safety analysis at tower crane.

• Journal for History of Mathematics
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• v.22 no.4
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• pp.41-52
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• 2009

This study investigates a mathematical subject, 'triangles' in mathematics books of Chosun Dynasty, in special Muk Sa Jib San Bub(默思集算法), Gu Il Jib(九一集), San Hak Ib Mun(算學入門), Ju Hae Su Yong(籌解需用), and San Sul Gwan Gyun(算術管見). It is likely that they apt to avoid manipulating general triangles except the right triangles and the isosceles triangles etc. Our investigation says that the progress of triangle-related contents in Chosun mathematics can fall into three stages: measurement of the triangle-shaped fields, transition from the object of measurement to the object of geometrical study, and examination of definition, properties and validation influenced by western mathematics.

• Journal of the Society of Naval Architects of Korea
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• v.42 no.1 s.139
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• pp.24-33
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• 2005

It is important to understand the flow characteristics around two sails of a sloop yacht. In this paper a computational aerodynamic investigation is performed over sail-like airfoils similar to the main and iIb sails of a 30 feet sailing yacht. Lift and drag are calculated for various conditions of slit distance between the two sails and overlapped length of the jib sail. The thrust and CE(center of effort) of the sail system are obtained. It is found that the combination of two sails produces the thrust force larger than the sum of the thrust force of each sail standing separately and the slit distance of the two sails are important factor to increase lift force.

• Journal for History of Mathematics
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• v.25 no.4
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• pp.11-19
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• 2012

Zhu Shi Jie's Suan Xue Qi Meng (算學啓蒙) is one of the most important books which had a great influence to the development of Chosun Mathematics and Gyung SunJing's Muk Sa Jib San Bub is the oldest Chosun mathematics book. In this paper, comparing Suan Xue Qi Meng (算學啓蒙) with Muk Sa Jib San Bub, we study the mathematics educational constructions and structures in books and then conclude that their structure can be used in present school mathematics.

• The Journal of Korean Medical History
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• v.30 no.2
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• pp.73-81
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• 2017

This literature review focuses on external treatments for the throat, as found in the classic Korean text, Hyang-Yak-Jib-Sung-Bang Throat. Sections of the text related to external treatment of throat disorders were reviewed. Examples of frequently used external methods include gargling, application of powder, and brushing of the throat. These methods are still used in modern Korean Medicine treatments for Ear-Nose-Throat (ENT) disorders. This discussion is provided with intention to invigorate the ancient practices of throat treatments, by highlighting benefits and results of the therapeutic protocols described in Hyang-Yak-Jib-Sung-Bang Throat. Discovering new effective herbal medicines and developing more precise external treatments will advance ENT treatment in Korean medicine.

• Journal for History of Mathematics
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• v.28 no.5
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• pp.233-248
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• 2015

Year 2014 was very special to Korean mathematical society. Year 2014 was the Mathematical Year of Korea, and the International Congress of Mathematicians "ICM 2014" was held in Seoul, Korea. The year 2014 was also the 330th anniversary year of the birth of Joseon mathematician Hong JeongHa. He is one of the best, in fact the best, of Joseon mathematicians. So it is worth celebrating his birth. Joseon dynasty adopted a caste system, according to which Hong JeongHa was not in the higher class, but in the lower class of the Joseon society. In fact, he was a mathematician, a middle class member, called Jungin, of the society. We think over how Hong JeongHa was able to write his mathematical book GuIlJib in Joseon dynasty.

• Journal of Auto-vehicle Safety Association
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• v.13 no.2
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• pp.50-56
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• 2021

The purpose of this study is to investigate vulnerable parts of tower crane structures by analyzing extensive non-destructive test data. Approximately ten percent of domestically registered tower cranes were inspected by using magnetic particle inspection. The testing was carried out as advised in KS B 0213. The non-destructive results was analyzed with respect to jib types, age and crane size. As a result, the number of crack occurrences were the largest in mast parts, followed by main jib part. Moreover, it was found that turntables were important parts deserved to be noticed at the perspective of safe maintenance.

• The Journal of Korean Medical History
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• v.13 no.2
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• pp.93-107
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• 2000

To generalize how early-Chosun medical achievements represented by "Hyang Yak Jib Sung Bang" and "Eui Bang Yoo Chui" influenced the publishment of "Dong Eui Bo Gam", and what academic achievements of "Dong Eui Bo Gam" are, I have compared the compositions of "Dong Eui Bo Gam" to two representative medical literature of early-Chosun era and examined the changes in organizations, and I was able to find deep connections among "Dong Eui Bo Gam", "Hyang Yak Jib Sung Bang" and "Eui Bang Yoo Chui".

• Korean Architects
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• s.633
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• pp.90-95
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• 2022