• Title/Summary/Keyword: Mobility control

Search Result 997, Processing Time 0.033 seconds

The Effect of Coordinative Locomotor Training on Physical Factors for Falls in the Elderly with Mild Cognitive Impairment (협응이동훈련이 경도인지장애노인의 낙상물리요인에 미치는 영향)

  • Park, Mihee;Lee, Dong-Woo;Jeong, Mo-Beom
    • Journal of the Korean Society of Physical Medicine
    • /
    • v.15 no.2
    • /
    • pp.65-73
    • /
    • 2020
  • PURPOSE: This study examined the effects of coordinative locomotor training on the physical factors for falls in the elderly with mild cognitive impairment. METHODS: This study examined thirty subjects diagnosed with mild cognitive impairment by the radiologic findings, history, and physical examination. The subjects were assigned to a control group (n = 15) or experimental group (n = 15, coordinative locomotor training). The experimental group underwent coordinative locomotor training for four weeks, with training sessions two times per week. The control group was given a fall-prevention education for 60 minutes without coordinative locomotor training. To evaluate the physical factors for falls, the lower extremity strength and the Korean version of the Fullerton advanced balance scale and biorescue were measured for balance. These tests were conducted before and after training. RESULTS: Significant differences were observed between the two groups after the four weeks of coordinative locomotor training for the elderly with mild cognitive impairment the experimental group had a greater degree of improvement in the physical factors for falls. CONCLUSION: These findings suggest that coordinative locomotor training may have a functional effect on fall-prevention and the mobility of the elderly with mild cognitive impairment. In addition, it is expected to provide systematic and effective data that can be used as a fall prevention program for the elderly with mild cognitive impairment in each institution.

Region-based Tree Multicasting Protocol in Wireless Ad-Hoc Networks (무선 에드혹 네트워크에서 지역 기반 트리를 이용한 멀티캐스팅 프로토콜)

  • Lim Jung-Eun;Yoo Sang-Jo
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.30 no.11B
    • /
    • pp.772-783
    • /
    • 2005
  • In this paper, we propose an effective multicasting protocol in wireless ad-hoc networks. Conventional wired and wireless network multicast protocols do not perform well in wireless ad hoc networks because they were designed without consideration of ad hoc environments such as node mobility, limited bandwidth, high error probability. To solve this problem, some multicasting protocols for ad hoc network have been proposed in the literature. However, these protocols can not provide high packet delivery ratio, low control packet overhead and low expended bandwidth at the same time. Therefore, in this paper, we propose RTMA that improves multicasting performance in wireless ad hoc networks. RTMA calculates its current region from its position information by using GPS in order to make tree among the multicast group nodes in the same region. The proposed region-based tree method is for high packet delivery ratio, low control packet overhead when many senders send data packets. RTMA makes a reliable tree by using speed information to fill a gap of the weak points of the tree structure. When searching the routing path, RTMA selects the reliable path excluding high speed nodes.

High-Efficiency GaN-HEMT Doherty Power Amplifier with Compact Harmonic Control Networks (간단한 구조의 고조파 정합 네트워크를 갖는 GaN-HEMT 고효율 Doherty 전력증폭기)

  • Kim, Yoonjae;Kim, Minseok;Kang, Hyunuk;Cho, Sooho;Bae, Jongseok;Lee, Hwiseob;Yang, Youngoo
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
    • /
    • v.26 no.9
    • /
    • pp.783-789
    • /
    • 2015
  • This paper presents a Doherty power amplifier(DPA) operating in the 2.6 GHz band for long term evolution(LTE) systems. In order to achieve high efficiency, second and third harmonic impedances are controlled using a compact output matching network. The DPA was implemented using a gallium nitride high electron mobility transistor(GaN-HEMT) that has many advantages, such as high power density and high efficiency. The implemented DPA was measured using an LTE downlink signal with a 10 MHz bandwidth and 6.5 dB PAPR. The implemented DPA exhibited a gain of 13.1 dB, a power-added efficiency(PAE) of 57.6 %, and an ACLR of -25.7 dBc at an average output power of 33.4 dBm.

A study for semi-static quadruped walking robot using wave gait (물결걸음새를 이용한 준정적 4족 보행로봇에 관한 연구)

  • 최기훈;김태형;유재명;김영탁
    • Proceedings of the Korean Society of Precision Engineering Conference
    • /
    • 2001.04a
    • /
    • pp.551-554
    • /
    • 2001
  • A necessity of remote control robots or various searching robots etc. that accomplish works given instead of human under long distance and extreme environment such as volcano, universe, deep-sea exploration and nuclear power plant etc. is increasing, and so the development and the research regarding these mobile robots are actively progressing. The wheel mobile robot or the track mobile robot have a sufficient energy efficiency under this en, but also have a lot of limits to accomplish works given which are caused from the restriction of mobile ability. Therefore, recently many researches for the walking robot with superior mobility and energy efficiency on the terrain, which is uneven or where obstacles, inclination and stairways exist, have been doing. The research for these walking robots is separated into fields of mechanism and control system, gait research, circumference environment and system condition recognition etc. greatly. It is a research field that the gait research among these is the centralist in actual implementation of walking robot unlike different mobile robots. A research field for gait of walking robot is classified into two parts according to the nature of the stability and the walking speed, static gait or dynamic gait. While the speed of a static gait is lower than that of a dynamic gait, a static gait which moves the robot to maintain a static stability guarantees a superior stability relatively. A dynamic gait, which make the robot walk controlling the instability caused by the gravity during the two leg supporting period and so maintaining the stability of the robot body spontaneously, is suitable for high speed walking but has a relatively low stability and a difficulty in implementation compared with a static gait. The quadruped walking robot has a strong point that can embody these gaits together. In this research, we will develope an autonomous quadruped robot with an asaptibility to the environment by selectry appropriate gait, element such as duty factor, stride, trajectory, etc.

  • PDF

A Study on TCP Performance Enhancements in Wireless Networks (무선망에서의 TCP 성능 향상 방안에 관한 연구)

  • Park, Do-Yong;Kim, Young-Beom
    • Journal of IKEEE
    • /
    • v.10 no.1 s.18
    • /
    • pp.30-39
    • /
    • 2006
  • The TCP protocol can provide some reliability using sliding window mechanism for data transmission, flow control, and congestion control. However, TCP has some limitations in that it has basically been designed solely for wired communication environments. If traditional TCP protocol is used also in wireless networks, the end-to-end data transmission performance degrades dramatically due to frequent packet losses caused by transmission errors and hand-offs. While there have been some research efforts on TCP enhancements considering the mobility of wireless communication devices, in this paper we propose a new method to improve the TCP performance by combining the Snoop and the Freeze-TCP methods. In the proposed scheme, the TCP end-to-end semantics is maintained and no changes of existing protocols in sending systems or in routers are required. It has the advantage of simple implementation because TCP code changes are limited to mobile devices for applying the Freeze-TCP and it requires only to add Snoop modules in base stations. Accordingly, the proposed scheme can operate well in the existing networks. Finally, in this study, we compared the performance of the proposed scheme with traditional TCP, other approaches through simulations using ns-2.

  • PDF

Dynamic Carrier Sensing Threshold Scheme based on SINR for Throughput Improvement in MANET (MANET에서 처리율 향상을 위한 SINR 기반 동적 캐리어 감지 임계값 방법)

  • Lee, Hyun-No;Kim, Dong-Hoi
    • Journal of Digital Contents Society
    • /
    • v.15 no.3
    • /
    • pp.319-326
    • /
    • 2014
  • IEEE 802.11 WLAN uses CSMA/CA(Carrier Sense Multiple Access/Collision Avoidance) method in MAC(Media Access Control) protocol, and through the carrier sense checks whether other users use the channel during the data transmission to avoid the data collision. Currently, IEEE 802.11 standard recommends the use of a fixed threshold which gives an impact on carrier sensing range. However, the existing scheme using the fixed threshold causes the operation of network to be inefficiency owing to the mobility in MANET(Mobile Ad hoc NETwork). In this paper, we found the better network throughput to be obtained by applying the proposed scheme, which chooses properly the carrier sensing threshold and transmission rate considering SINR(Signal to Interference-plus-Noise Ratio), to the MANET.

Utilization of Legacy APs for Seamless Handover in a SDN Environment (네트워크 가상화 환경에서 끊김 없는 핸드오버를 위한 일반 AP 활용)

  • Lee, Hyung-Bong;Kwon, Ki-Hyeon
    • Journal of Digital Contents Society
    • /
    • v.19 no.8
    • /
    • pp.1545-1554
    • /
    • 2018
  • In order to support the mobility of the wireless devices, at least two APs (Access Points) must be arranged in a single AP area to maintain communication area. In the WLAN (Wireless LAN) environment, seamless handover is one of the most important issues in terms of effective utilization of wireless networks and maximization of services for users. On the other hand, SDN (Software-Defined Networking), which is emerging rapidly in recent years, is revolutionizing network management in terms of flexibility, fine control, and convenience. SDN originally reduces latency time or increases network robustness by real-time flow table control reducing or bypassing paths between switches in LAN-based data centers. In this study, we apply OpenFlow, a SDN platform focused on wired LAN, to a dense WLAN environment using legacy APs to implement and evaluate seamless handover for streaming services of digital contents.

A Study on the Appication of Semi-Active Supension Units for a Combat Vehicle by Using HILS (HILS를 활용한 전투차량의 반능동 현수장치 적용에 관한 연구)

  • Kim, Chi-Ung;Kim, Moon-June;Rhee, Eun-Jun;Lee, Kyoung-Hoon;Woo, Kwan-Je
    • Journal of the Korea Institute of Military Science and Technology
    • /
    • v.13 no.6
    • /
    • pp.967-975
    • /
    • 2010
  • There have been a lot of efforts on the improvement for the ride comfort and handling stability of the combat vehicles. Especially most of vehicles for military purpose have bad inertial condition and severe operating condition such as the rough road driving, and need a high mobility in the emergency status. It is necessary to apply the controlled suspension system in order to improve the vehicle mobile stability and ride comfort ability of crews. A feasibility study is performed on the application of the semi-active suspension system with a magneto-rheological controlled shock absorber for a $6{\times}6$ combat vehicle. First, the dynamic simulation model of the vehicle including the control model for the semi-active suspension system was executed. Based on this model, a hardware-in-the-loop simulation(HILS) system which has a semi-active suspension controller hardware was constructed. After full vehicle simulations were performed in virtual proving courses with this system, the semi-active suspension system was proven to give better ride comfort and handling stability in comparison with the conventional passive suspension system.

Histomorphometry and stability analysis of early loaded implants with two different surface conditions in beagle dogs

  • Kim, Dong-Seok;Kim, Dae-Gon;Park, Chan-Jin;Cho, Lee-Ra
    • The Journal of Advanced Prosthodontics
    • /
    • v.1 no.1
    • /
    • pp.10-18
    • /
    • 2009
  • STATEMENT OF PROBLEM. Despite an improved bone reactions of Mg-incorporated implants in the animals, little yet has been carried out by the experimental investigations in functional loading conditions. PURPOSE. This study investigated the clinical and histologic parameters of osseointegrated Mg-incorporated implants in early loading conditions. MATERIAL AND METHODS. A total of 36 solid screw implants(diameter 3.75 mm, length 10 mm) were placed in the mandibles of 6 beagle dogs. Test groups included 18 Mg-incorporated implants. Turned titanium implants served as control. Gold crowns were inserted 4 weeks after implant placement and the dogs were immediately put on a food diet. Implants were observed for 10 weeks after loading. Radiographic assessments and stability tests were performed at the time of fixture installation, $2^{nd}$ stage surgery, 4 weeks after loading, and 10 weeks after loading. Histological observations and morphometrical measurements were also performed. RESULTS. Of 36 implants, 33 displayed no discernible mobility, corresponding to successful clinical function. There was no statistically significant difference between test implants and controls in marginal bone levels(P=.46) and RFA values. The mean BIC % in the Mg-implants was $54.5{\pm}8.4%$. The mean BIC % in the turned implant was $45.3{\pm}12.2%$. These differences between the Mg-implant and control implant were statistically significant(P=.005). CONCLUSIONS. The anodized, Mg-incorporated implant demonstrated significantly more bone-to-implant contact(BIC) in early loading conditions. CLINICAL IMPLICATIONS. The results of this study in beagle dogs suggest the possibility of achieving predictable stability of early loaded free-standing dental implants with Mg-incorporated surface.

Design of Antenna for Beam Scanning for Dual-Band base station (이중대역 기지국용 빔 스캔 안테나 설계)

  • Ko Jin-Hyun;Jang Jae-Su;Ha Jae-Kwon;Park Sae-Houn
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
    • /
    • 2006.05a
    • /
    • pp.632-636
    • /
    • 2006
  • It is needed to use the beam scanning to control the cell coverage of the base station considering operation conditions, season, time period, radiation character and mobility of customers and vehicles for varied wireless communication service and quality improvement. This paper proposes a mobile antenna system which can obtain the characteristics of the beam scanning by controlling the directivity depending on the operation condition. Radiation block is made of 2 sub-array of $1\times3$ patched antennas for ITS of 5.8GHZ bandwidth with the gain of 13dBi, and of 2 sub-array of single patched antenna for WiBro of 2.3GHZ bandwidth with the gain of 12dBi. RF module is made of a switch, an amplifier, a PAD, a 3-Bit phase shifter, and a power divider. The system is able to control the beam tilting with electronic methode by using 3-bit phase shifter$(45^{\circ},\;90^{\circ},\;180^{\circ})$.

  • PDF