• Structural Engineering and Mechanics
• /
• v.4 no.4
• /
• pp.451-460
• /
• 1996

We propose a new shape of cylindrical shell formed by multiples vaults which gives a self-stiffening against buckling. By an experimental and numerical study of cylindrical shells with a repeated defect, on the circumferential direction made only of outside oriented wave-defects, we show that multiple vault cylindrical shells can have a good behaviour in buckling. An optimal behaviour is obtained by optimization of the vaults number, with conduces to a special multiple vault cylindrical shell named "ASTER shell".

• Journal of Digital Convergence
• /
• v.13 no.11
• /
• pp.441-448
• /
• 2015

The purpose of the study was to perform a comparative analysis of the success and failure cases to increase the completeness of vault "Shirai-Kim Hee Hoon" technique. The subject of the study was "K" a male gymnast from Korean Artistic Gymnastic National team. The results obtained through the three-dimensional analysis during international as well as practice session are as follows: Firstly, excluding BC, the lead time in each PrF, HC and PoF phases were shorter during successful trials than in failure trials. Secondly, during successful trials, the horizontal and vertical velocity appeared to be higher during taking off, which contributed positively to the leaping motion in the horizontal direction. Thirdly, when compared with successful and failure trials, the body's angular rotation was highly maintained during the takeoff from the spring board followed by larger thigh angular displacement at the vault before actually attempting the backward rotation.

• Korean Journal of Applied Biomechanics
• /
• v.13 no.3
• /
• pp.47-65
• /
• 2003

The purpose of this study was to investigate the differences of the kinematical and the kinetical factors that calculated from preflight to postflight of salto forward straight 3/2 turn motion between skitters and less-skitters. four S-VHS video cameras operating at 60Hz were used to record the performances. five elite male gymnasts were participated in this study as subjects. three-dimensional coordinates of 20 body landmarks during each trial were collected using a Direct Linear Transformation method. The digitized body landmarks were smoothed using a Butterworth second order with low pass digital filter and a cutoff frequency of 10Hz. 1. A skitter, got a high score for performance, showed shorter time and faster horizontal velocity than a less-skitter at the board contact. also, a skitter extended quickly his knee and hip joint after contacting board for preflight phase. 2. A skitter revealed faster time and horizontal velocity the vault from taking off board than a less-skiller. A skitter took a long time and high distance to get the vertical peak compared with a less-skiller. 3. For the second phase, a skitter, who executes the most optimal motions among the subjects, displayed a long flight time, a high height, and a far flight distance as well as maintaining consistent horizontal speed even at the peak of post flight. On the other side, a less-scorer displayed a slow vertical velocity, distance and a short time at the point of take-off from vault as well as low height at the peak of post flight.

• Journal of KIISE:Computer Systems and Theory
• /
• v.35 no.4
• /
• pp.172-177
• /
• 2008

In this paper, we design an authentication protocol based on Fuzzy Signature Vault Scheme using a light signature feature extraction method for user convenience and efficiency of electronic commerce. The signature is used broadly in electronic commerce because it is one of the simple and low-cost biometric items. However, signature has a problem that there are few low-cost and safe protocols. To solve this problem, we design a feature extraction method which is adequate for characters of signature and Fuzzy Vault Scheme. In addition, we design and analyze an efficient authentication protocol with some parameters used in this procedure. The followings are advantages when this protocol is applied to authentication procedure; 1) using convenient and low-cost signatures, 2) being possible to verify users with spending only about second for signature processing and authentication, 3) one time on transmission for sign-in and verification and 4) getting user authentication with secret value at the same time.

• Korean Journal of Applied Biomechanics
• /
• v.21 no.5
• /
• pp.561-571
• /
• 2011

The purpose of this study was to perform the kinematic analyses of the women's pole vault skills in IAAF World Championships Daegu 2011. Subjects were the 1st through 8th place finishers in the pole vault. The kinematic analyses were divided into four phases: two dimensional run up analysis, and three dimensional analyses for the remaining plant, swing up, and extension phases. Run-up variables consisted of run up distance, number of steps, average step length, ratio of step length to height, average velocity at the final 5~10 m, approach position. Three variables were analyzed during plant: pole angle, center of gravity (COG) velocity, and COG takeoff angle. Swing up phase variables included: pole flection angle, COG velocity (horizontal, vertical, resultant), COG trajectory and bar approach angle of COG. Compared to the 2009 World Championships in Berlin, the average vault height increased, while run up velocity and approach position were almost unchanged. However, horizontal velocity during the last two steps of the final approach decreased noticeably compared to speeds from 1990. These results reflect the change in both technique and physical fitness in pole vaulters. During extension, the peak height of COG surpassed the clearance height by an average of 0.11m. These specific results can help coaches and athletes modify training and improve performance.

• Korean Journal of Applied Biomechanics
• /
• v.21 no.5
• /
• pp.551-560
• /
• 2011

The purpose of this study was to perform the kinematic analyses of the men's pole vault skills in IAAF World Championships Daegu 2011. Subjects were the 1st through 8th place finishers in the pole vault. The kinematic analyses were divided into four phases: two dimensional run up analysis, and three dimensional analyses for the remaining plant, swing up, and extension phases. Run-up variables consisted of run up distance, number of steps, average step length, the ratio of step length to his height, average velocity at the final 6~11 m, approach position. Three variables were analyzed during plant: pole angle, center of gravity (COG) velocity, and takeoff angle of COG. Swing up phase variables included: pole flexion angle, COG velocity (horizontal, vertical, resultant), COG trajectory and bar approach angle of COG. Compared to the 2009 World Championships in Berlin, the average vault height, run up velocity and approach position increased. However, horizontal velocity during the last two steps of the final approach decreased dramatically compared to speeds from 1990. These results reflect the change in both technique and improved physical fitness in pole vaulters. During extension, the peak height of COG averaged 0.3m higher then COG height when the pole was released. These specific results can help coaches and athletes modify training and improve performance.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.4 no.6
• /
• pp.1294-1310
• /
• 2010

User authentication using fingerprint information provides convenience as well as strong security. However, serious problems may occur if fingerprint information stored for user authentication is used illegally by a different person since it cannot be changed freely as a password due to a limited number of fingers. Recently, research in fuzzy fingerprint vault system has been carried out actively to safely protect fingerprint information in a fingerprint authentication system. In addition, research to solve the fingerprint alignment problem by applying a geometric hashing technique has also been carried out. In this paper, we propose the hardware architecture for a geometric hashing based fuzzy fingerprint vault system that consists of the software module and hardware module. The hardware module performs the matching for the transformed minutiae in the enrollment hash table and verification hash table. On the other hand, the software module is responsible for hardware feature extraction. We also propose the hardware architecture which parallel processing technique is applied for high speed processing. Based on the experimental results, we confirmed that execution time for the proposed hardware architecture was 0.24 second when number of real minutiae was 36 and number of chaff minutiae was 200, whereas that of the software solution was 1.13 second. For the same condition, execution time of the hardware architecture which parallel processing technique was applied was 0.01 second. Note that the proposed hardware architecture can achieve a speed-up of close to 100 times compared to a software based solution.

• Korean Journal of Applied Biomechanics
• /
• v.15 no.4
• /
• pp.143-151
• /
• 2005

This study was conducted to investigate the technical factors of Cuervo forward straight vaults with single twist, single and half twists, and double twists actually performed by three execellent male gymnasts participated in artistic gymnastics competition of 2003 summer Universiade in Daegu and the 85th National Sports Festival in Cheongju. To accomplish the research goals the Cuervo vaults of three gymnasts were filmed by using three digital camcorders set by 60 Hz, and data were collected through the DLT method of three dimensional cinematography. The kinematic and kinetic variables as each phasic time, CM displacement velocity, release angle inclination angle hip joint angle landing angle, average horse reaction force average moment arm average torque, whoe body's total remote local angular momentum were analyzed, so the following conclusions were reached. Generally to perform the better Cuervo vault, a gymnast should touch down on the board with the great horizontal velocity of the whole body through the fast run-up, and touch down on the horse by decreasing the horizontal displacement of the whole body during the preflight, so raise CM height gradually within a short horse contact time. He should increase the horse reaction force through checking the horizontal velocity of the whole body effectively and the inclination angular displacement of the handstand, if so he can have the large vertical velocity of the whole body. By using the acquired the velocity and the angular momentum of the whole body, he can vault himself higher and twist sufficiently, then he can get better if the body could be tilted by swinging both arms and perform the cat twist with a little flexions at hip joints. According to the above outcomes we can judge that the best athletes is LuBin, the better is YTY, and the next is JSM.

• Archives of Craniofacial Surgery
• /
• v.15 no.2
• /
• pp.47-52
• /
• 2014

Background: Management of positional plagiocephaly by wearing a cranial molding helmet has become a matter of growing medical interest. Some research studies reported that starting helmet therapy early (age 5 to 6 months) is important and leads to a significantly better outcome in a shorter treatment time. The aim of the present study was to evaluate the effectiveness of cranial remodeling treatment with wearing helmet for older infants (${\geq}18$ months). Methods: We conducted a retrospective study of 27 infants with positional plagiocephaly without synostosis, who were started from 2008 to 2012. Every child underwent a computerized tomography (CT) before starting helmet therapy to exclude synostosis of the cranial sutures and had CT performed once again after satisfactory completion of therapy. Anthropometric measurements were taken on using spreading calipers in every child. The treatment effect was compared using cranial vault asymmetry (CVA) and the cranial vault asymmetry index (CVAI), which were obtained from diagonal measurements before and after therapy. Results: The discrepancy of CVA and CVAI of all the patients significantly decreased after cranial molding helmet treatment in older infants (${\geq}18$ months) 7.6 mm from 15.6 mm to 8 mm and 4.51% from 9.42% to 4.91%. Six patients had confirmed successful outcome, and all subjects were good compliance patients. The treatment lasted an average of 16.4 months, was well tolerated, and had no complication. Additionally, the rate of the successful treatment (final CVA ${\leq}5mm$) significantly decreased when the wearing time per was shorter. Conclusion: This study showed that treatment by cranial remodeling orthosis was effective if the patient could wear the helmet longer and treatment duration was somewhat longer than in younger patients, well tolerated in older infants and had no morbidity. This therapeutic option is available and indicated in these older infants before other cranial remodeling surgery.

• Korean Journal of Applied Biomechanics
• /
• v.23 no.3
• /
• pp.189-200
• /
• 2013

The purpose of this study was to compare the kinematic analyses of the women's pole vault skills difference between skilled group (1st to 8th place) and less skilled group (10th to 15th place) who participated in IAAF World Championships Daegu 2011. To achieve this goal, 16 women's pole vault player's kinematic analyses was conducted. Player's best performance was recorded by five normal video cameras operating at 60 Hz. The results of this study through the research procedures above are as follows. First, Skilled group's average step length and the ratio of step length to her height were longer than less skilled's group in run-up phase. Second, Skilled group's horizontal velocity was faster than less Skilled group's results. And pole plant angle was lower than less Skilled group's results in take-off phase. Third, Maximum pole flexion angle did not show difference of between two groups in pole bending phase. However, Skilled group's vertical velocity was higher than less skilled group's results.