• Title/Summary/Keyword: gravity center

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Depositional features and sedimentary facies of steep-faced fan-delta systems: modern and ancient (현생 및 고기 급경사 선상지-삼각쭈계 퇴적층의 특성과 퇴적상)

  • Choe M. Y.;Chough S. K.;Hwang I. G.
    • The Korean Journal of Petroleum Geology
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    • v.2 no.2 s.3
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    • pp.71-81
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    • 1994
  • Alluvial fan delta often extends into deep water, forming steep-faced delta front. Depositional features of modern steep-faced fan-delta slope and prodelta are characterized by slump scar, chute/channel, swale, lobe, splay and debris fall. These features largely originate from sediment failure or sediment-laden underflows (sediment-gravity flows) off river mouth. Sedimentary facies of equivalent ancient systems comprise sheetlike and/or wedged bodies of gravelstone and sandstones, slump-scar and -fill, chute/channel-fills, and sheetlike, lobate and slump mass on steeply-inclined fan-delta foreset and prodelta.

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The Effect of Exercise Program for Falls Prevention on Balance and Quality of Life in the Elderly Women (낙상예방 운동프로그램이 노인여성의 균형과 삶의 질에 미치는 영향)

  • Kim, Myung-Chul;Ahn, Chang-Sik;Kim, Yong-Seong
    • Journal of the Korean Society of Physical Medicine
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    • v.5 no.2
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    • pp.245-254
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    • 2010
  • Purpose : The purpose of this study is to investigate the effects of falls prevention exercise program(center of gravity control training, multiple sensory training, strategic posture training, ambulation training, muscle strengthening training) to balance and muscular strength in the elderly females. Methods : A total of 30 elderly womens participated in this study. All subjects have participated in exercise program on three times a week for eight weeks. Before and after of exercise program, They have measured about Berg Balance Scale (BBS), Performance Oriented Mobility Assessment (POMA), Time Up & Go (TUG), Sit to stand, Fall Efficacy Scale (FES), Quality of Life (QOL). Results : The results of this study were as follows ; 1) There were statistically significant difference in the BBS, POMA, FES, QOL test on within-subject. 2) There were not significant difference in the TUG, Sit to stand test on within-subject. 3) The BBS was correlated with POMA and QOL. The POMA was also correlated with QOL. Conclusion : The result of this study shows that falls prevention exercise program was meaningful increasing of balance ability and quality of life on elderly women

Evaluation of Seismic Performance of Steel Frame before and after Application of Seismic Isolator (면진 장치 적용 전, 후의 철골조의 내진 성능 평가)

  • 김대곤;이상훈;안재현;박칠림
    • Journal of the Earthquake Engineering Society of Korea
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    • v.2 no.1
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    • pp.47-62
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    • 1998
  • The laminated elastomeric bearing and the lead-rubber bearing were designed to isolate one bay-two story steel frame which is designed for only gravity load. The seismic performance is evaluated for the designed steel frame before and after application of these seismic isolators between the super structure and the foundation. These isolators can improve the seismic capacity of the steel frame. Especially, by inserting the lead plug into the center of the laminated elastomeric bearing, the initial stiffness of th bearing can be increased, thus rather large lateral displacement can be prevented under the frequent service lateral load. During the strong earthquake, yielding of the lead can increase the capacity of the energy dissipation.

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Data Pattern Estimation with Movement of the Center of Gravity

  • Ahn Tae-Chon;Jang Kyung-Won;Shin Dong-Du;Kang Hak-Soo;Yoon Yang-Woong
    • International Journal of Fuzzy Logic and Intelligent Systems
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    • v.6 no.3
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    • pp.210-216
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    • 2006
  • In the rule based modeling, data partitioning plays crucial role be cause partitioned sub data set implies particular information of the given data set or system. In this paper, we present an empirical study result of the data pattern estimation to find underlying data patterns of the given data. Presented method performs crisp type clustering with given n number of data samples by means of the sequential agglomerative hierarchical nested model (SAHN). In each sequence, the average value of the sum of all inter-distance between centroid and data point. In the sequel, compute the derivation of the weighted average distance to observe a pattern distribution. For the final step, after overall clustering process is completed, weighted average distance value is applied to estimate range of the number of clusters in given dataset. The proposed estimation method and its result are considered with the use of FCM demo data set in MATLAB fuzzy logic toolbox and Box and Jenkins's gas furnace data.

Experimental Studies of Controller Design for a Car-like Balancing Robot with a Variable Mass (무게 변화에 따른 차륜형 밸런싱 로봇의 제어기 설계 및 실험연구)

  • Kim, Hyun-Wook;Jung, Seul
    • Journal of the Korean Institute of Intelligent Systems
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    • v.20 no.4
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    • pp.469-475
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    • 2010
  • This paper presents controller design of a two wheeled mobile inverted pendulum robot for one man transportation vehicle. Since the overall mass is varying with different drivers, suitable controller gains are obtained through experimental studies. Variation of the center of gravity due to different masses also affects stable balancing control. Thus, the desired balancing angle si required to be modified with respect to different masses. To measure masses for different drivers, a weight scale is used and those data are used for balancing control through communication. The gain scheduling method of using data obtained from experimental studies allows the robot to have stable balancing performances.

Effects of Virtual Reality Horse Riding Simulator Training Using a Head-Mounted Display on Balance and Gait Functions in Children with Cerebral Palsy: A Preliminary Pilot Study

  • Kim, Hae Won;Nam, Ki Seok;Son, Sung Min
    • The Journal of Korean Physical Therapy
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    • v.31 no.5
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    • pp.273-278
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    • 2019
  • Purpose: The purpose of this study was to investigate the effects of three-dimensional virtual reality horse riding simulator training using a head-mounted display on gait and balance in children with cerebral palsy. Methods: Ten children with cerebral palsy were randomly assigned to the horse riding simulator (HRS) group (n=5) or the horse riding simulator with virtual reality (HRSVR) group (n=5). To evaluate balance, center of gravity (COG) sway velocity and total sway distance of each group were assessed using the Wii balance board, and gait speed and stride length of each group were assessed using a gait analysis system. Results: Intra-group comparisons between pre- and post-intervention measures revealed that there were significant changes in all gait and balance variables such as stride length, gait velocity, COG sway velocity and COG sway distance in the HRSVR group (p<0.05). In the HRS group, there were significant changes in all variables except stride length (p<0.05). In addition, inter-group comparisons showed significant differences between the two groups in stride length, gait velocity and COG sway distance except COG sway velocity (p<0.05). Conclusion: The findings of this study suggest that horse riding simulator training combined with 3D virtual reality can be a new positive therapeutic approach for improving functional performance in children with cerebral palsy.

Prediction of Kick Motor Mass Variation (킥모터 무게 변화 예측)

  • Kil, Gyoung-Sub;Kho, Hyeon-Seok;Kim, Byung-Hun;Cho, In-Hyun
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2008.11a
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    • pp.203-206
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    • 2008
  • Kick motor(KM) for KSLV-I second stage propulsion system is the main hardware that is necessary for launching satellite to it's track. The mass of the kick motor changes with combustion time because the heat insulator is ablated and propellant is used and slag is piled up. We predicted mass change with the flight time using ground combustion data of KM composed of case, propellant, nozzle, ignitor and slag. The mass prediction of kick motor can be used for calculating the two stage mass and center of gravity history.

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An Experimental Study on the Motion Response of a High-Speed Planing Craft in Regular Head Waves (정면 규칙파 중 활주형 고속선의 운동 응답에 대한 실험적 연구)

  • Kim, Dong-Jin;Rhee, Key-Pyo;Hwang, Seung-Hyun;Park, Han-Sol
    • Journal of the Society of Naval Architects of Korea
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    • v.46 no.4
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    • pp.373-381
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    • 2009
  • The running attitude of a high-speed planing craft may change significantly depending on its speed in seaway. Other variables that may influence its running attitude are its weight, center of gravity, sea conditions, and so on. In this paper, planing craft model tests were carried out with respect to above variables in SNU towing tank, and vertical motion responses of a planing craft in regular head waves were analyzed. The experimental results in regular waves were compared with those in calm water, and compared with the theoretical estimations. Finally, the effects of running speeds of a planing craft on its motion amplitudes are confirmed.

Finite element analysis of long-term changes of the breast after augmentation mammoplasty: Implications for implant design

  • Myung, Yujin;Lee, Jong-Gu;Cho, Maenghyo;Heo, Chan Yeong
    • Archives of Plastic Surgery
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    • v.46 no.4
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    • pp.386-389
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    • 2019
  • The development of breast implant technology continues to evolve over time, but changes in breast shape after implantation have not been fully elucidated. Thus, we performed computerized finite element analysis in order to better understand the trajectory of changes and stress variation after breast implantation. The finite element analysis of changes in breast shape involved two components: a static analysis of the position where the implant is inserted, and a dynamic analysis of the downward pressure applied in the direction of gravity during physical activity. Through this finite element analysis, in terms of extrinsic changes, it was found that the dimensions of the breast implant and the position of the top-point did not directly correspond to the trajectory of changes in the breast after implantation. In addition, in terms of internal changes, static and dynamic analysis showed that implants with a lower top-point led to an increased amount of stress applied to the lower thorax. The maximum stress values were 1.6 to 2 times larger in the dynamic analysis than in the static analysis. This finding has important implications for plastic surgeons who are concerned with long-term changes or side effects, such as bottoming-out, after anatomic implant placement.

Partial Discharge Data Analysis with Unsupervised Classification (무감독분류 기법에 의한 부분방전 데이터 분석)

  • Cho, Kyungsoon;Hong, Seonhack
    • Journal of Korea Society of Digital Industry and Information Management
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    • v.14 no.4
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    • pp.9-16
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    • 2018
  • This study described partial discharge(PD) distribution analysis between the XLPE(Cross-Linked PolyEthylene)and EPDM(Ethylene Propylene Diene Monomer) interface with unsupervised classification. The ${\phi}-q-n$ patterns were analyzed using phase resolved partial discharge(PRPD). K-means cluster analysis forms a cluster based on similarities and distances among scattered individuals, and analyzes the characteristics of the formed clusters, dividing the multivariate data into several groups according to the similarity of each characteristic, Is a statistical analysis that makes it easier to navigate. It was confirmed that the phase angle of the cluster with the maximum discharge charge was concentrated around $0^{\circ}$ and $180^{\circ}$ at 30 kV after the initial phase distribution localized around $90^{\circ}$ and $300^{\circ}$ expanded to the whole phase angle according to the voltage rise. The Euclidean distance between the center of gravity and the discharge charge in the ${\Phi}-q$ cluster increased with increasing applied voltage.