• The Journal of Korea Robotics Society
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• v.9 no.1
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• pp.57-66
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• 2014

This paper describes the design concept of a bio-inspired legged underwater and estimating its performance by implementing simulations. Especially the leg structure of an underwater organism, diving beetles, is fully adopted to our designing to employ its efficiency for swimming. To make it possible for the robot to both walk and swim, the transformable kinematic model according to applications of the leg is proposed. To aid in the robot development and estimate swimming performance of the robot in advance, an underwater simulator has been constructed and an approximated model based on the developing robot was set up in the simulation. Furthermore, previous work that we have done, the swimming locomotion produced by a swimming patten generator based on the control parameters, is briefly mentioned in the paper and adopted to the simulation for extensive studies such as path planning and control techniques. Through the results, we established the strategy of leg joints which make the robot swim in the three dimensional space to reach effective controls.

• Journal of Power Electronics
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• v.15 no.2
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• pp.399-410
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• 2015

A 6.5 V/50 kA high-frequency switching power supply (HSPS) system composed of 10 power modules is developed to meet the requirements of copper-foil electrolysis. The power module is composed of a two-leg pulse width modulation (PWM) rectifier and a DC/DC converter. The DC/DC converter adopts two full-wave rectifiers in parallel to enhance the output. For the two-leg PWM rectifier, the ripple of the DC-link voltage is derived. A composite control method with a ripple filter is then proposed to effectively improve the performance of the rectifier. To meet the process demand of copper-foil electrolysis, the virtual impedance-based current-sharing control method with load current full feedforward is proposed for n-parallel DC/DC converters. The roles of load current feedforward and virtual impedance are analyzed, and the current-sharing control model of the HSPS system is derived. Virtual impedance is used to adjust the current-sharing impedance without changing the equivalent output impedance, which can effectively reduce current-sharing errors. Finally, simulation and experimental results verify the structure and control method.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.11
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• pp.74-79
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• 2021

Generally, multi-legged walking robots have excellent mobility in rough and uneven terrain, and they are deployed for the safety of rescuers in various disaster environments. However, as each leg is driven by a number of actuators, it leads to a complicated structure and high power consumption; therefore, it is difficult to put them into practical use. In this article, a new concept is proposed of a walking robot whose legs are driven by a complex linkage structure to overcome the deficiencies of conventional multi-legged walking robots. A double crank-rocker mechanism is proposed, making it possible for one DC motor to actuate the left and right movements of two neighboring thighs of the multi-legged walking robot. Each leg can also move up and down through an improved cam structure. Finally, each mechanism is connected by spur and bevel gears, so that only two DC motors can drive all legs of the walking robot. The feasibility of the designed complex linkage mechanism was verified using the UG NX program. It was confirmed through actual production that the proposed multi-legged walking robot performs the desired motion.

• Journal of Korean Medicine Rehabilitation
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• v.20 no.4
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• pp.171-183
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• 2010

Objectives : The biomechanical relationship of leg length discrepancy(LLD), Lumbar lordosis, pelvic variance and degenerative scoliosis is one of the most important parameters when treat musculoskeletal disorders, however the reports are still controversial. The purpose of this study was to compare the relationships between the parameters and bothersomeness in subject with chronic ow back pain. Methods : Sixty female and eight male adults with non specific low back pain over 3 months were recruited. LLD was measured by tape measure method. Lumbar lordosis, lumbosacral angle and related pelvic parameters were measured using simple radiologic films of lumbosacral view. Results : Lumbar lordosis was significantly correlated to the lumbosacral angle, pelvic incidence and difference of the both iliac widths. Pelvic incidence had significant correlation with difference of the both iliac widths. And difference of both iliac widths was related with LLD by radiologic film. There was also significant correlation between the LLD by radiologic film and tape measurement. Visual analogue scale(chronic low back pain) of normal lordosis group was greater than hyperlordosis group. Conclusions : There were close biomechanical relationships between lumbar, pelvis, and lower extremity. But in order to determine the effect of structure on the chronic low back pain, global balance of musculoskeletal structure seems to be worth further researching.

• Journal of the Korean Society of Costume
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• v.63 no.8
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• pp.125-142
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• 2013

Soek(Xi) was the highest ranked shoe that was worn with the primary formal dress in East Asian countries including ancient Korea and China. This article examined Joseon's Seok as discussed in previous studies, and it explored factors such as the wearers' status, wearing situations, its morphology, its materials, and its colors in the Great Han Empire period (1897~1910), and then extracted three morphological characteristics of the Korean Seok to examine its origin. The results of the study are as follows. For women, the Seok in the Great Han Empire period was worn with Won-sam(圓衫) and No-eui(露衣) as well as Jeok-eui(翟衣), and hence its range of wearing was extensive. Also, red Seok was worn with deep red colored Dae-sam(大衫)-styled Jeok-eui in the Joseon period(1392~1897), and blue Seok with deep blue Jeok-eui in the Great Han Empire period. This suggests the possibility that wearing of deep blue Jeok-eui occurred after 1906 in terms of the use of blue Seok. As for its morphology, its leg-less form was maintained into the late Joseon period, and there were no great changes in its name. The characteristics of the Korean Seok's morphological structure consisted of a shoe leg, the wood-less bottom and pearl ornament. As a result of the examination of the origin of those characteristics, it has been clarified that the form in which Gu, Eok, Jun(純), are attached in the structure with a shoe leg originated from the combination of Hwa(靴) and Li(履) after the two types of shoes were alternately worn in the Song (宋) period. Also, it was confirmed that the woodless bottom appeared between the periods from Wei Jin Northern and Southern Dynasties(魏晉南北朝) to Sui(隋), and the pearl ornament occurred in the Jin(金) period.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.123.4-123
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• 2001

This paper explains the walking robot with 4 legs. One leg is composed of 4 dc server motors and have 4 d.o.f. This walking robot has simple structure using "the principle of lever". The structure of robot models the 4 legs´ animal such as dog. The walking patterns is various and complex. With inspecting the walking dogs, the walking motions implemented by patterns. The center of mass is important of this type robot. The significant issue of walking is weight. As the weight is lighter, so the robot well walks. The method of walking is patterns.

• Journal of Ocean Engineering and Technology
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• v.11 no.3
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• pp.8-19
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• 1997

In this study an adequate type of offshore structure at the Sakhalin region as cold region is proposed and its structural design results are presented based on the reliability analysis. Structural safety assessment has been carried out for the proposed offshore structure at the Sakhalin area as designed by the reliability method. And a rational design procedure is presented based on the reliability analysis. Followings are drawn through the present study : - Four colum TLP structure is proposed as an adequate offshore structure type at the cold region like the Sakhalin region and the reliability-based structural design results are presented. It is seen that the proposed type is a more adequate and economic than the fixed type. - Safety assessment of the proposed structure applying the extended incremental load method is performed. - Referring the allowable safety level for offshore structures it has been found present TLP structure has sufficient structural safety at the system level as well as at the component level.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.4
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• pp.536-543
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• 2013

In this paper, we propose a new type of hexapod robot that can walk fast. Most of the conventional hexapod robots are either rectangular type of hexagonal type. Those robots have drawbacks in the speed and stability of walking. The proposed robot has six legs, one fore leg, one hind leg, two left legs and two right legs. The proposed robot forms relatively wide supporting polygons along the walking direction, so it can walk very fast stably. We implemented the proposed hexapod robot and showed the feasibility of the robot by 3+3 walking experiment and 2+4 walking experiment.

• Journal of Power Electronics
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• v.1 no.1
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• pp.36-47
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• 2001

The carrier-based space vector pulse width modulation(SVPWM), which is considered as highly simple and efficient PWM technology, can be also used in multilevel inverters. The method was originally designed for the two-level inverter and developed to the diode clamped multilevel inverter structure. however it may be noted that it also cause bad switch utilization in cascaded multilevel inverter. This paper introduces an improved carrier-based SVPWM scheme, which is fully suitable for cascaded multilevel inverter topologies because it can achieve the optimized switch utilization through the redistribution of the triangular carrier waves considering leg voltage redundancies while having the advantages of the conventional carrier-based SVPWM. Using simulation and experimental results, the superior performance of new PWM method is shown.

• Ocean Systems Engineering
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• v.6 no.2
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• pp.203-216
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• 2016

Over recent years the offshore wind turbines are becoming more feasible solution to the energy problem, which is crucial for Egypt. In this article a three floating support structure, tension leg platform types (TLP), for 5-MW wind turbine have been considered. The dynamic behavior of a triangular, square, and pentagon TLP configurations under multi-directional regular and random waves have been investigated. The environmental loads have been considered according to the Egyptian Metrological Authority records in northern Red sea zone. The dynamic analysis were carried out using ANSYS-AQWA a finite element analysis software, FAST a wind turbine dynamic software, and MATLAB software. Investigation results give a better understanding of dynamical behavior and stability of the floating wind turbines. Results include time history, Power Spectrum densities (PSD's), and plan stability for all configurations.