• Journal of the Korean Society of Safety
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• v.26 no.2
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• pp.1-5
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• 2011

In order to evaluate fatigue endurance for an ultra-light weight inline skate frame, FEM analysis was performed. Tensile properties and a S-N curve were determined through tensile and fatigue tests on a modified Al-7075+$S_c$ alloy. The yield and ultimate tensile strengths were 553.3 MPa and 705.5 MPa, respectively. The fatigue endurance limit of this alloy was 201.2 MPa. For evaluating the fatigue endurance of the inline skate frame, the S-N data were compared with the stress analysis results through FEM analysis of the frame. The maximum Von-Mises stress of the frame was determined 106 MPa through FEM analysis of the frame, assuming that the rider weight is 75 Kg. Conclusively, on the basis of fatigue limit, the inline skate frame has a safety factor of approximately 2.0.

• Korean Journal of Computational Design and Engineering
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• v.10 no.1
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• pp.17-26
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• 2005

In-line skate generally consists of four major parts: boot, frame, bearing and wheel, and the most important part among those for necessary functionality is the frame. It is the most expensive, and it also makes a decisive role in practical race skating. The functional behavior of a frame is greatly affected by external dynamic forces as well as the static weight of a skater. We are proposing a new inline speed-skating frame design that has been improved in structural strength and weight for providing optimum speed in $20\sim40km$ marathon skating.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.3 s.96
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• pp.30-37
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• 1999

This paper represents the development of the brake system for the inline skate using bellows. The inline skate that is used at present has defects due to frequent impulse, which weakens the breaking force by damaging the parts. Therefore to solve these problems a break system for the inline skates using hydraulics is suggested. To solve the oil leakage problems, bellows is used. Also to prevent the breaks from not touching the ground when skating the bellows is placed at the heel, high as possible. To obtain fast response speed, the ratio of inner diameter of the bellows is changed so that with only a small displacement from the bellows the rubber pad attached to the bellows will touch the ground fast. The performance of the break system using bellows depends on the optimal design of the bellows. Therefore the parameters that changes the form of the bellows are tested and also the interaction between the forces are investigated. The performance of new model brake system with bellows and old model system with only a rubber pad without bellows was estimated through observation of braking posture.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.11
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• pp.1507-1514
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• 2011

Injection molding is the most commonly used process that uses plastic material. Today, the uses of plastic material are continuously increasing, and the range of application is also being extended by the development of novel materials. An inline skate consists of 4 components: the boot, frame, wheel and brake. Among these components, the frame is the most critical. The injection formability for a variety of injection materials for inline skate frames was studied. We also studied the injection formability of the product for various sizes of the runner and gate. In this study, injection molding analysis was performed using MOLDFLOW, and structural analysis was performed using ANSYS.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.1228-1231
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• 2004

We analyzed the impulse on 24 sensors location under the foot using the Parotec system for the investigation of the relationship between the shoe type and the foot pathologies. Total 7 kinds of shoes, i.e. sport shoe, high heel shoes (5cm heel, 8cm heel, 13cm heel), platform shoe, inline skate, and heelys were evaluated for 20 normal subjects. Compared with the impulse distribution of the sport shoe, greater impulses were shown at the 1$^{st}$ phalange and the 1$^{st}$ metatarsal-phalangeal head in high-heel shoes, lateral tarsal bone and medial metatarsal bone in platform shoe, medial tarsal bone in inline-skate, and medial tarsal bone and 1st phalange in heelys shoe. The result of this study is expected to provide useful information about the relationship between the shoe type and the foot pathologies.ies.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.8 s.173
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• pp.174-181
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• 2005

We analyzed the pressure, impulse on 24 sensors location under the foot using the Parolee system. Total 7 kinds of shoes, i.e. sport shoe, high heel shoes (5cm heel, 8cm heel, 13cm heel), platform shoe, inline skate, and heelys were evaluated for 20 normal subjects. Compared with those of sport shoe, greater pressure and impulse were shown on the 1 st phalange and the 1 st metatarsal head and greater impulse on the medial tarsal bone in high-heel shoes. Greater pressure and impulse were shown on medial metatarsal bone and the lateral tarsal bone in platform shoe. Greater impulse was shown on the medial tarsal bone in inline-skate. Heelys shoe showed smaller impulse on the central area of foot. The result of this study is expected to provide useful information about the relationship between the shoe type and the foot pathologies.

• Korean Journal of Applied Biomechanics
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• v.15 no.2
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• pp.11-20
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• 2005

This study has a purpose on contributing to apprehend safe and right way to stop to the inline skate beginners and to the instructors who teaches line skating on the basis for the result of the kinematical analysis on Heel brake stop movement of the inline skate, focusing on the displacement on COG, angle displacement of ankle joint, angle displacement of knee joint, angle displacement of hip joint, using a 3D image method by DLT. To achieve this goal, we analysed the kinematical factor of the 3 well-trained inline skating instructors and obtained the following results. 1. During the movement of heel-brake stop, when strong power was given to a stable and balanced stop and the lower limbs, if the physical centroid is lowered the stability increases, and if it is placed high from the base surface, as the stability decreases compared to the case of low physical centroid, we should make a stop by placing a physical centroid in the base surface and lowering the hight of physical centroid. 2. To make a stable and balanced stop and to provide a strong power to the lower limbs, it is advisable to make a stop by decreasing an angle displacement of ankle joint during a "down" movement. In case of the left ankle joint, in all events and phases the dorsiflexion angle showed a decrease. Nevertheless, in the case of the right ankle joint, the dorsiflexion angle shows an increase after a slight decrease. The dorsiflexion angle displacement of ankle joint can be diminished because of the brake pad of the rear axis frame of the right side inline skate by raising a toe, but cannot be more decreased if certain degree of an angle is made by a brake pad touching a ground surface. To provide a power to a brake pad, it is recommended to place a power by lowering a posture making the dorsiflexion angle of the left ankle joint relatively smaller than that of the right ankle. 3. To make a stable and balanced stop and to add a power to a brake pad, the power must be given to the lower limbs in lowering the hight of physical centroid. For this, it is recommended to make a down movement by decreasing the flexion angle of a knee joint and it is necessary to make a down movement by a regular decrease of the angle displacement of knee joint rather than a swift down movement in every event and phase. 4. The right angle displacement of hip joint is made by lowering vertically the hight of physical centroid as leaning slightly forward. If too narrow angle displacement of hip joint is made by leaning forward too much, the balance is lost during the stop by placing the center in front. To make a stable and balance stop and to place a strong power to the lower limbs, it is recommendable to make a narrow angle by lower the hip joint angle. However, excessive leaning of the upper body to make the angle too narrow, can cause an instable stop and loss of physical centroid. After this study, it is considered to assist the kinematical understanding during the heel brake stop movement of the inline skate, and, to present basic data in learning a method of stable and balanced stop for the inline skating beginners or for the inline skate instructors in the present situation of the complete absence of the study in inline skating.

• Korean Journal of Applied Biomechanics
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• v.18 no.4
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• pp.191-199
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• 2008

The purpose of this study was to analyze movement of inline skate players at inline roller skate T300m start so that we can find effective starting movement, and provide basic and scientific materials in improving performance of inline roller skaters for T300m inline roller skating. In doing so, five Korean national representative inline skaters who elected in 2008 Korean National Inline Roller Skating Cup were taped during the cup and analyzed through 3D viewing in terms of their starting movement Conclusions of the analysis were as follows: First, the better the record of starting phase is the shorter average of contact time on track. Second, to improve starting speed, players raised their body just like running instead of lowering them when gliding. players could shorten their strike and moved faster in order to accelerate, and it was more effective to speed up when they quickly switched from running to gliding. Third, the five country-representative players speeded up by bending their knees to a greater degree in order to improve stability. And then the most effective way was believed to minimize track connection of skating at starting in each phase.

• Korean Journal of Applied Biomechanics
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• v.17 no.2
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• pp.23-29
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• 2007

The purpose of this study was to examine if there are kinematic variables differences between national representative players (NRP) and non national representative players (NNRP) during 500 m inline skate starting motion. Four NRP and six NNRP were recruited for the study. Each subject executed starting motion five times on a $2{\times}12m$ start way in a gymnasium. Kinematic variables were analyzed by the three-dimensional motion analysis system (60Hz). It was hypothesized that there are difference in elapsed time and center of mass acceleration in starting phase between groups since starting phase has been considered important in sprinting. The results showed that the NRP had significantly shorter starting phase time than that of NNRP. 1) An elapsed time in phase P1 of NRP was shorter than that of NNRP, and excellent players have early started their first stroke. 2) Both NRP and NNRP have started at the same spot, and displacement of the center of gravity in starting posture of NRP group was at the front compared to NNRP group. 3) Average step lengths of NRP were longer than those of NNRP, and a step change of NRP was stabler compared to that of NNRP. 4) In a speed change of the center of gravity NRP showed comparatively high speed from P1 to P4.

• Korean Journal of Applied Biomechanics
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• v.20 no.4
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• pp.355-364
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• 2010

The purpose of this study was to investigate the kinematical analysis of T-stop motion by inline skate rolling speed. Six subjects were participated in the experiment(age: $35.0{\pm}3.3$ yrs, weight: $72.70{\pm}5.1\;kg$, height: $176.30{\pm}3.1\;cm$, career: $10.00{\pm}2.5$ yrs). The study method adopted 3-dimensional analysis and 2 cameras for filming to analyze the required displacement of center of mass, displacement of right and left hip joint, displacement of right and left knee joint, displacement of trunk tilt using by APAS. The results were as follows; In anterior-posterior displacement of COM, the faster rolling speed, the longer displacement at phase 2. In vertical displacement of COM, the faster rolling speed, the lower displacement. In medial-lateral displacement of COM, there was no significant on rolling speed. In angular displacement of right thigh segment, the faster rolling speed, the bigger displacement in X and Z axis. In angular displacement of left thigh segment, the faster rolling speed, the lower displacement in X axis. In angular displacement of right shank segment, the faster rolling speed, the bigger displacement in Z axis. In angular displacement of left shank segment, the faster rolling speed, the bigger displacement in X and Y axis. In angular displacement of trunk segment, the faster rolling speed, the bigger displacement in Z axis.