• Korean Journal of Applied Biomechanics
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• v.19 no.1
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• pp.87-98
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• 2009

This study was conducted to compare biomechanical differences in throwing movement between skilled and unskilled high school students using three-dimensional analysis system with a force platform. The findings indicated that skilled students showed shorter throwing time, faster horizontal speed of (1) the center of mass at heel contact of left foot, (2) the forearm throughout swing phase, (3) the hand after heel contact while unskilled students showed faster horizontal speed of, (1) the center of mass after heel contact and (2) the hand at heel contact of left foot. Skilled students showed greater (1) shoulder angle during throwing, (2) elbow angle after take off of foot, (3) peak vertical ground reaction force during throwing and (4) peak anterior-posterior ground reaction force at heel contact of right foot. While skilled students showed leaning backward of the trunk during throwing, unskilled students showed leaning forward during release phase with leaning backward before release.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.43 no.3 s.309
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• pp.16-24
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• 2006

In this paper, fault-tolerant gait planning of a hexapod robot for walking over irregular terrain is presented. The failure concerned in this paper is a locked joint failure for which a joint in a leg cannot move and is locked in place. Based on the previously proposed fault-tolerant tripod gait for walking over even terrain, fault-tolerant follow-the-leader(FTL) gaits are proposed for a hexapod robot with a failed leg to be able to walk over two-dimensional rough terrain, maintaining static stability and fault tolerance. The proposed FTL gait can have maximum stride length for a given foot position of a failed leg, and yields better ditch crossing ability than the previously developed gaits. The applicability of the proposed FTL gait is verified by using computer graphics simulations.

• Korean journal of applied entomology
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• v.32 no.1
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• pp.76-82
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• 1993

Phonotaxis of the African mole cricket, Gryllotalpa africana palisot de Beauvois, was investigated in 1990 and 1992 at the agronomy Experiment Station of Korea Ginseng & Tobacco Research Institute in Hwaseong-gun, Kyonggi-do, Male adults produced calling sounds (calling songs) through the openings of subsurface burrows. Intensities of the sound were 77-80 dB at 15 cm above the openings. When tape recordings of male calling songs were broadcasted outdoors at 105-110 dB by two horn speakers installed at the center of a 1.4 m diameter-funnel, flying adults were attracted for 1.5 hours from about 30 minutes after sunset. Among attracted adults, 14.3-16.9% landed in the funnel, and 65.7-74.7% landed on the ground within 2m form the sound source. Females were 66.7-74.3%, which seemed to be due to the sex ratio of the population in the field. Adults landing in the funnel and at the distance of within 2m from the center of the funnel were tend to be a little more than those attracted to a blacklight trap.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.1
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• pp.77-84
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• 2013

Most research on the inkjet printing technology has focused on the development of inkjet head itself, and of process, not on the landing accuracy of the droplets to a target. Thus, this paper presents the modeling and experimental verification on the static landing accuracy and precision of the droplets from the magnetostrictive inkjet head. A simple model based on the angle deviation of a nozzle tip and on a distance to a substrate is considered, assuming that there is no ambient effect. The angle deviation of the nozzle tip is determined by using its digital image with the aid of a pixel calculation program, and the distance to the substrate is set to 1 mm. Three experiments have planned and preformed. The first experiment is to collect the initial data for the landing distribution of the droplets. The second experiment is to collect the repeatability data of the stage used. Then, these data are used to rederive the equation for the final landing position of the droplet. The final experiment is to verify the equation and to show the calibration results. The respective landing accuracy of the droplet after calibration on the x-axis and on y axis has improved from $338.51{\mu}m$ and $-133.63{\mu}m$ to $7.06{\mu}m$ and $13.11{\mu}m$. The respective percent improvement on the x-axis and on y axis reaches about 98 and about 90. The respective landing precision of the droplet after calibration on the x-axis and on y axis has improved from ${\pm}182.6{\mu}m$ and ${\pm}182.88{\mu}m$ to ${\pm}24.64{\mu}m$ and ${\pm}42.76{\mu}m$. The respective percent improvement on the x-axis and on y axis reaches about 87 and about 77.

• Journal of the Korean Geographical Society
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• v.48 no.4
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• pp.545-556
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• 2013

This study sets up nodal regions for shopping and leisure with 424 district units located in Seoul and examines the characteristics of the vertical structure and the regional system. According to the higher-order analysis result, the trip for leisure forms a greater part, and about each of the nodal regions of the first stratum, major spots for origin and destination are located in the center, and those spots are connected to adjacent district units located nearby. As the factor's eigenvalue is bigger, the spatial range gets greater, too, and is located in outsides. And in the third or higher strata, either linkage between Gangnam and Gangbuk or leapfrogging linkage according to the bipolar factors is distinctive. Linkage between nodal regions centering around Jongro-gu, Jung-gu, Gangnam-gu, or Yeoungdeungpo-gu is not distinct, and in particular, the nodal regions of Jongro Geumcheon are maintained as the upper strata being independent from other nodal regions from the second or higher strata.

• Journal of the Korean Applied Science and Technology
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• v.37 no.4
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• pp.786-793
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• 2020

The purpose of this study is to analysis the horizontal distance of COM and COP and the movement patterns of COM and COP during the badminton high-clear of woman middle school student. The select variables used in the statistical analyses(independent sample T-test) were the horizontal distance of COM and COP at (E4), and the maximum COM displacement of the back-, forward-, whole-swing phases between expert and novice groups. Based on the results in this study, it was concluded that: First, expert group showed the shorter horizontal distance between COM and COP in anteroposterior axis (X-axis) at Event 4 compared to the novice group. Second, expert group dominantly used COM vertical movement while novice group actively used COM horizontal movement during the badminton high-clear stroke.

• Proceeding of EDISON Challenge
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• 2016.03a
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• pp.610-613
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• 2016

항공기의 착륙 과정에서 지면효과에 의해 기체가 원하는 위치에 착지하지 못하는 경우가 있다. 이러한 현상들로 인해 항공기의 착륙 실패 또는 활주로 이탈로 인한 인명피해로 이어질 수 있다. 본 연구에서는 이러한 착륙과정에서 쓰이는 날개의 부품중 하나인 Spoiler에 대한 공력 해석을 EDISON 전산열유체 시스템을 이용하여 진행해 보았다. 특히 Spoiler의 전개 각도를 다양하게 변화시켜가며 그 전개 각도에 의한 Lift dumping effect에 초점을 맞추어 연구를 진행하였다. 예상과 동일하게 전개각도가 커질수록 양력은 감소하였으며 항력의 경우 선형적으로 증가하는 양상을 보였다. 또한 전개각도가 20도보다 커지는 구간부터는 양력이 음수로 작아지는 현상을 확인할 수 있었다.

• Proceedings of the Korea Information Processing Society Conference
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• 2018.10a
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• pp.144-146
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• 2018

새로운 회사, 학교에 면접을 보러가는 사람이나 신규 건물 이용자들은 그러한 복잡한 건물을 이용하기 힘들다. 이러한 문제들을 상호작용 가능한 증강현실 어플리케이션을 해결한다. 본 논문의 어플리케이션은 스마트폰의 내장 GPS와 자이로스코프, 카메라를 이용하여 최종도착지 건물의 위치와 정보를 확인 할 수 있고, 그 과정에서 증강현실 기술을 이용하여 사용자에게 효율적이고 직관적인 서비스를 제공한다.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.20 no.3
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• pp.177-184
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• 1987

The quantitative mechanics on the sideways walking of the crabs may provide a basic solution for entanglements of the walking legs in gillnets. The gaiting behaviour of the crabs on the flat board and the nettings 10, 16 and 23 mm in mesh size were experimented concerning about stepping positions and times in the laboratory using video set on July, 1984, It was found that the irregular movements of walking crabs in stepping positions and patterns were appeared on the nettings due to the absence of mechanical contact in spite of neural control of compensating, while on the flat surface evolved systematic leg movements. The mean stride length and walking velocity, which were increased with the carapace width on the flat board, as well as the step period and forward by backward stroke time were greater than those values on the netting, not associated with the carapace or the mesh size. Also, the step period and the Phase difference on the nettings revealed larger fluctuation than on the flat board. The joint angles of the walking legs, on the nettings in meropodite-carporodite and thorax-meropodite, which joint was varied especially up to below horizon because of the falling legs through the netting twine, were virtually wider than those on the flat substrate.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.2
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• pp.167-174
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• 2020

The purpose of this study was to investigate the kinematic comparison between successful and failed trials of Lopez vault techniques in male gymnastics. The subject, an Olympic gold medalist, was YHS (age: 27 years, height: 1.6 m, and mass: 53 kg) and fourteen high speed motion capturing cameras were used for data collection. The 26 reflective sensors were attached on major anatomical positions and 15 segment-body model was used to calculate the kinematic variables. According to results, the contact duration of the spring-board for successful trial(ST) was longer and that of failed trial(FT) and the range of motion of knee joint for ST was greater than that of FT. The movement times during pre-flight between ST and FT were same, but the movement time of horse contact period for ST was shorter than that of FT. The ST showed a longer movement time during post-flight and the longer horizontal distance than those of FT. Conclusively, YHS needs to approach the horse with a higher position of the body and higher incidence angle, as well as make faster twist angular velocity in an attempt to achieve ST.