• Korean Journal of Applied Biomechanics
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• v.12 no.2
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• pp.159-177
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• 2002

The purpose of this study was to investigate the relations between the segments of the body, the three dimensional anatomical angle and the angular velocity of the air born phase and understand the control mechanism of the high-bar movement, the somersault, the double somersault, the double somersault with full twist. For this study seven well trained university gymnastic volunteered, Zatsiorky and Seluyanov(1983, 1985)'s sixteen segment system anatomical model was used for this study. For the movement analysis three dimensional cinematographical method(Arial Performance Analysis System : APAS) was used and for the calculation of the kinematic variables a self developed program was used with the LabVIEW 5.1 graphical profromming(Johnson, 1999) program. By using Eular's equations the three dimensional anatomical Cardan angles of the joint and angular velocity were defined. As a result of this study 1. As the rotation of the body increased in the air born phase the projection angle of the CM of the total increased, this resulted the increased of the max hight of the CM. 2. In three dimensional angular velocity the Z axis(vertical direction) projection angular velocity increased as the rotation of the body increased in the airborn phase, but the Y axis and the X axis projection angular velocity did not show significant differences. 3. As the rotation of the body increased in the air born phase the angular movement of the shoulder and the hip showed significant change. These movement act as the starter in the preparation phase. 4. The somersault angle, the twist angle, the tilt angle of the upper body related to the global reference frame in the releas phase the average somersault angle of the three types of high-bar movement was $57.7^{\circ}$, $38.8^{\circ}$, $39.7^{\circ}$, the average tilt angle was $-1.5^{\circ}$, $-5.4^{\circ}$, $-8.4^{\circ}$, the average twist angle was $13.4^{\circ}$, $10.6^{\circ}$, $23.3^{\circ}$. This result showed that the somersault with full twist had the largest movement.

• Information and Communications Magazine
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• v.14 no.12
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• pp.77-85
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• 1997

지금까지 access network에서의 xDSL의 위치를 살펴보고 DSL, HDSL, ADSL 및 VDSL을 중심으로 기술 및 최근의 표준화동향을 살펴보았다. ITU의 조사에 따르면 97년 기준으로 전세계 약 8억가구에 copper access line이 연결되어 있고 그중의 70%이상이 가정에 연결되어 있는데 증가추세도 북미의 경우 년3.5%, 서유럽과 태평양연안의 경우 년4.5%의 성장율을 보이고 있어 2000년경에는 10억가구에 다다를 전망이다. 미국은 97년기준 약 1억가구에 1억6000만 copper access line이 연결되어 있는데 Yankee Group이 조사한 바에 따르면 2000년을 기준으로 3백만가구에 ADSL/RADSL/SDSL이 연결되고 관련 revenue는 10억달러에 이를것으로 추산하고 있다. 전세계 xDSL 시장규모를 미국의 5배정도로 보면 2000년경에는 전세계 twist pair의 2%정도에 xDSL이 연결되어 ADSL/RADSL/SDSL 관련 세계시장규모가 50억달러에 이르고 시장성장률은 30%에 이를 것으로 보고 있다. 현재 이러한 xDSL의 표준화작업은 3장에서 언급한 바와 같이 ANSI T1, ETSI에서 주로 주도되고 있으나 ITU-T, IEEE, ADSL Forum, ATM Forum, DAVIC 등 다른 group과 활발한 liasion meeting 을 통해서도 협력안을 마련하려 노력하고 있다. 예를 들어 DAVIC은 long range(1.5Km이상) PMD규격으로 ADSL을, mid range($300m\sim1.5km$) PMD규격으로 VDSL을, short range(300m이하) PMD규격으로 CAP방식의 FTTC를 각각구정하여 xDSL을 수용하고 있다. Microsoft의 CEO인 Bill Gates가 'Bandwidth bottleneck. No question. that's the biggest obstacle.'이라고 천명한 바와 같이 정보사회로의 진전에 있어 bandwidth는 시급히 해결되어야 할 문제이다. 정보사회의 꿈을 실현하고자 1993년부터 시작된 In-formation Infrastructure의 구축노력이 그동안 다양하게 시도되어왔으나 숱한 우여곡절과 실패를 겪은 telco등의 서비스업자들이 이제는 너무 큰 꿈을 쫓기보다는 internet이라는 현실적인 시장에서 xDSL과 cablemodem을 바탕으로 차근차근 새로 시작하고 있다고 생각된다. 그동안 ADSL, Forum을 중심으로한 일부 technology evangelist들은 전세계 8억가구에 깔려있는 copper twist pair를 경제적인 'the last mile solution'으로 활용할 것을 줄기차게 주장해왔다. 그동안 xDSL은 VDSL이라는 차세대 대안을 제시하여 interim solution이라는 울타리를 벗어나는데 성공하였을 뿐만 아니라 IDSL, SDSL, RADSL등의 새로운 고객지향적 xDSL을 개발하여 선택의 폭을 넓혀주었다. xDSL vendor들간의 치열한 경쟁속에서 값싼 xDSL 시스템들이 속속 등장하고 있으며, DSLAM[8]과 같은 switch solution도 제시되어 기존의 copper twist pair를 이용해 값싸게 다양한서비스를 제공해 줄 수 있는 기틀을 마련한 것이 오늘날의 xDSL의 성공요인이라고 생각된다. 일찌기 Bell Atlantic의 CEO Ray Smith가 'Yes. ADSL is an interim solution that will be with us for forty years.'라고 간파한대로 xDSL은 fiber가 좀 더 값싼 해결책이 될 때까지 당분간 access network에서 확고한 자리를 구축할 것으로 보인다. 최근들어 우리나라의 초고속정보통신망도 ADSL 과 VDSL을 바탕으로 FTTH으로 진화하는 전략을 수립한것은 우리의 현실과 세계적인 추세를 반영한 일이라 여겨진다.

• Journal of The Korean Society of Integrative Medicine
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• v.10 no.4
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• pp.187-197
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• 2022

Purpose: This study aimed to investigate the changes in the muscle activity of the trunk stabilizer muscles before and after incorporating Pilates breathing during three types of Pilates chair exercises. Methods: This study included 33 healthy men and women in their 20's; they were recruited according to the inclusion and exclusion criteria. sEMG was used to measure the changes in the muscle activity in the internal oblique/transverse abdominis, rectus abdominis, and erector spinae during the three types of Pilates chair movements (footwork, twist footwork, and bridging) without and with the Pilates breathing integration. The muscle activities of the trunk stabilizers between without and with Pilates breathing were statistically analyzed and compared. Results: The internal oblique/transverse abdominis showed an increase and a significant difference in the muscle activity in all three movements of footwork, twist footwork, and bridging after the Pilates breathing integration (p<.001). The muscle activity of the rectus abdominis (p<.05) and the erector spinae (p<.05) also increased and showed a significant difference after the Pilates breathing incorporation, except in the bridging movement for the erector spinae. The increase in the rate after integrating Pilates breathing was relatively greater in internal oblique/transverse abdominis than in other muscles. Conclusion: When Pilates breathing was applied, the activities of the trunk stabilizer muscles increased significantly and immediately in all three movements of Pilates chair footwork, twist footwork, and bridging. This means that the use of breathing is expected to have a positive and immediate effect on the activation of trunk stabilizers, thus indicating that it can possibly be an effective re-enforcing tool to promote trunk stability when it is integrated to the Pilates chair exercise. Incorporating Pilates breathing also seemed to have a tendency to activate the deep trunk stabilizer muscles more than the superficial stabilizer muscles.

• Korean Journal of Heritage: History & Science
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• v.51 no.4
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• pp.84-107
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• 2018

Cheommojik is a pile cloth, a type of textile whose surface is covered with short piles. The term chaedam was used during the late Joseon dynasty to refer to pile cloth rugs, while the terms yoongjeon, dantong and yangtanja were used in the early twentieth century. Various documents, newspaper articles and photographs confirm that pile cloth rugs were used by the general public as well as the royal family from the late Joseon dynasty onward, and that there were domestic manufacturers of such rugs at that time. This study investigated six pile cloth rugs that were produced after the late Joseon dynasty, five of which feature Persian knots made of cut pile, the other being made with the loop pile method. The cut pile rugs are rectangular in shape and measure between 72-98cm by 150-156cm; and they are decorated in the middle with patterns of butterfly, deer, and tiger or the ten longevity symbols, and along the edges with patterns composed of 卍 symbols. The ground warp of all six rugs are made from cotton yarn, while the ground weft is made of cotton yarn on three pieces, wool on one piece and cotton and viscose rayon. The ground weft yarn from four pieces are Z-twist yarn made with two or more S-twist cotton yarn. Four to six colors were used for the pile weft, all being natural colors except for red. Two or more S- or Z-twist yarn were twisted together in the opposite twist for the pile weft, with the thickness determining the number of threads used. Six or more weft threads were used to make the start and end points of the rug; and the ground warp ends were arranged by tying every four of them together. For the left and right edges, three or more threads were wrapped together into a round stick-like form, and the second and third inner ground warps from the edges were stitched on to the wrapped edge. For the loop pile, loops were made in the direction of the warp; the ground warp and the ground weft may have been made with cotton, the pile warp with wool yarn. An analysis of the components of three rugs was conducted to determine which types of animal hair were used for the pile weft. Despite some inconclusive results, it was revealed that goat hair and fat-tailed sheep hair were used, raising the possibility that various kinds of animal fur were used in the production of pile cloth rugs. The six rugs examined in this study are estimated to have been made between the late 1800s and the early 1900s. Although the manufacturer of the rugs cannot be confirmed, we concluded that the rugs were produced in Korea after referring to the documentation of the domestic production of pile cloth rugs during the aforementioned period and the form and placements of the patterns on the rugs.

• Journal of the Korean institute of surface engineering
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• v.28 no.2
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• pp.77-82
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• 1995

In this study, we examined the relationships between the coating film's properties, such as microhardness, adhesion of coating fil $m_strate, and machining tool's life time. Samples were prepared by coating TiN on the 5.5 diameter twist drills using reactive ion plating technology, For measuring microhardness and adhesion of fil $m_strate, HSS plate was used for substrate. TiN coated drill's life time was dependent on the adhesion of fil $m_strate and averagely increased by several ten times more than uncoated drill's. The major parameter affecting TiN coated drill's life time was the strong adhesion between coating film and substrate.ate.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.15 no.1
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• pp.61-70
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• 2005

This study investigated the spinal loads(L5/S1 disc compression and shear forces) predicted from four biomechanical models: one EMG model and three optimization models. Three objective functions used in the optimization models were to miminize 1) the cubed muscle forces : MF3, 2) the cubed muscle stress : MS3, 3) maximum muscle intensity : MI. Twelve healthy male subjects participated in the isometric voluntary exertion tests to six directions : flexion/extension, left/right lateral bending, clockwise/ counterclockwise twist. EMG signals were measured from ten trunk muscles and spinal loads were assessed at 10, 20, 30, 40, 50, 60, 70, 80, 90%MVE(maximum voluntary exertion) in each direction. Three optimization models predicted lower L5/S1 disc compression forces than the EMG model, on average, by 31%(MF3), 27%(MS3), 8%(MI). Especially, in twist and extension, the differences were relatively large. Anterior-posterior shear forces predicted from optimization models were lower, on average, by 27%(MF3), 21%(MS3), 9%(MI) than by the EMG model, especially in flexion(MF3 : 45%, MS3 : 40%, MI : 35%). Lateral shear forces were predicted far less than anterior-posterior shear forces(total average = 124 N), and the optimization models predicted larger values than the EMG model on average. These results indicated that the optimization models could underestimate compression forces during twisting and extension, and anterior-posterior shear forces during flexion. Thus, future research should address the antagonistic coactivation, one major reason of the difference between optimization models and the EMG model, in the optimization models.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.299-307
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• 2005

The 180 km/h Korean Tilting Train(TTX) which is now developing as a part of the Korean National R&D project, was elaborately designed. As the tilting trains run curve track with the $30\%$ higher speed than normal trains, the higher centrifugal and dynamic force are expected. Furthermore the complex tilting system increase the probability of failure. Therefore it is very important for tilting train to ensure safety against derailment under the various kind of failed condition in the middle of running as well as normal operating condition. The TTX train have the relatively high roll stiffness to improve the lateral ride comfort and to limit the roll displacement on the curve. But the higher roll stiffness increase the risk of derailment on the twisted track. This paper describes the study to review the safety against derailment caused by the wheel unloading on the severely twisted track. The worst combination of maximum cant change with maximum twist defect was established by numerical simulation. And also it was assumed that the air bag deflated and still the train run its speed limit. Those kind of assumption might be the worst case from the view point of wheel unloading derailment on the twisted track. The dynamic simulation was done by means of VAMPIRE S/W and non-linear transient analysis. We found that derailment quotients Q/P was only slightly influenced by track twist but the wheel unloading was greatly influenced. And we ascertained that the higher roll stiffness the higher wheel unloading. In case of air bag deflated situation, the wheel unloading reached up to $100\%$ which means the wheel lift or jumped. Therefore it was concluded that the design need to be improved to ensure the safety against derailment on the maximum twisted track in case of air bag deflated and tilting train's speed limit.

• Journal of the Korean Society of Costume
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• v.52 no.3
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• pp.149-160
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• 2002

Symbolism found in a certain object inherits characteristics from the culture that contains the objects. The purpose of this study was investigate the formative beauty of Korean trousers twisted the pieces together based on the way of Korean thinks and the Topology. The shape is formed by cutting from the fabric. From the perspective of semiology, the fabric and the pattern shape correspond to ground and figure. Ground and figure are identical with the principle of the whole and the part, which is the same in Korea, China, and the West. But In Korea, the 3-dimensional garment is made by adding a twist. This is very important and defines the difference in the way of thinking and topology. Korean trousers consist of three parts : Hury, Marupok, and Sapok. The small Sapok can be made by removing the Marupok and large Sapok (figure) from the fabric (ground) when making Korean trousers. A Mobius strip is made when the large Sapok is adjoined with the small Sapok by reversing the small Sapok, making a 180$^{\circ}$twist and then stitching together. The theory of Mobius strip can be applied in Joining Bajiburi. thus when the trousers are completed the Klein's bottle is seen because of the 2 existing Mobius strop. The theory of Mobius strip can be applied in Joining Bajiburi, thus when the trousers are completed the Klein's bottle is seen because of the 2 existing Mobius strip. Hury is cylinder while the small and large Sapok make up the Mobius strip. As a result, Mobius strip, Kleins'bottle, protective plan can be applied in cutting Hanbok used in the countryside, so I have come to see that the traditional Korean way of thinking is closely related to the theory of topological.

• Bulletin of the Korean Mathematical Society
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• v.36 no.1
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• pp.147-159
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• 1999

Tabanov investigated the global symmetric perturbation of the integrable billiard mapping in the ellipse [3]. He showed the nonintegrability of the Birkhoff billiard in the perturbed domain by proving that the principal separatrices splitting angle is not zero.In this paper, using the exact separatrix map of an one-degree-of freedom Hamiltoniam system with time periodic perturbation, we show the existence the stochastic layer including the uniformly hyperbolic invariant set which implies the nonintegrability near the separatrices of a Birkhoff's billiard in the domain bounded by $C^2$ convex simple curve constructed by the generic global perturbation of the ellipse.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.12S
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• pp.1165-1174
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• 2003

The responses of hypothetical silicon nanotubes under torsion have been investigated using an atomistic simulation based on the Tersoff potential. A torque, proportional to the deformation within Hooke's law, resulted in the ribbon-like flattened shapes and eventually led to a breaking of hypothetical silicon nanotubes. Each shape change of hypothetical silicon nanotubcs corresponded to an abrupt energy change and a singularity in the strain energy curve as a function of the external tangential force, torque, or twisted angle. The dynamics o silicon nanotubes under torsion can be modelled in the continuum elasticity theory.