• Title/Summary/Keyword: 배치각도

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Experimental Investigation of Concentrating Photovoltaic System Applying Commercial Multi-array Lens for Space Applications (상용 배열형 렌즈를 적용한 집광형 태양전력시스템의 우주 적용 가능성 실험적 검토)

  • Park, Tae-Yong;Chae, Bong-Geon;Lee, Yong-Geun;Kang, Suk-Joo;Oh, Hyun-Ung
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.42 no.7
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    • pp.622-627
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    • 2014
  • A pico-class satellite has limitation to generate power from the solar cells due to its limited accommodation area to install the solar cells. The variation of incidence angle between solar panels and sunlight induced by the revolution and rotation of the satellite is one of the key parameters to determine the power generation. In this study, we proposed a concentrating photovoltaic system for pico-class satellite applications to enhance power generation when the ${\beta}$ angle between the sunlight and the solar panel is zero by effectively concentrating solar energy on solar panels. The feasibility of the conceptual idea has been demonstrated by power measurement test using solar simulator and commercial multi-array lens system.

On the Design of ToA Based RSS Compensation Scheme for Distance Measurement in WSNs (ToA 기반 RSS 보정 센서노드 거리 측정 방법)

  • Han, Hyeun-Jin;Kwon, Tae-Wook
    • The KIPS Transactions:PartC
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    • v.16C no.5
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    • pp.615-620
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    • 2009
  • Nowadays, wireless infrastructures such as sensor networks are widely used in many different areas. In case of sensor networks, the wirelessly connected sensors can execute different kind of tasks in a diversity of environments, and one of the most important parameter for a successful execution of such tasks is the location information of each node. As to localization problems in WSNs, there are ToA (Timer of Arrival), RSS (Received Signal Strength), AoA (Angle of Arrival), etc. In this paper, we propose a modification of existing ToA and RSS based methods, adding a weighted average scheme to measure more precisely the distance between nodes. The comparison experiments with the traditional ToA method show that the average error value of proposed method is reduced by 0.1 cm in indoor environment ($5m{\times}7m$) and 0.6cm in outdoor environment ($10{\times}10m$).

Effects of Neuromuscular Electrical Stimulation of the Vastus Medialis on Pain and Muscle Function in Patients with Knee Osteoarthritis (내측광근의 신경근전기자극(NMES)이 퇴행성 슬관절염 환자의 통증 및 근 기능에 미치는 영향)

  • Jin, Yu-Shin;Jeong, Tae-Gyeong
    • The Journal of the Korea Contents Association
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    • v.12 no.1
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    • pp.329-337
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    • 2012
  • The purpose of this study was to investigate the functional changes of the vastus medialis while the neuromuscular electrical stimulation(NMES) was performed in elderly women with knee osteoarthritis. The subjects of this study were 30 women who were diagnosed degenerative arthritis, 15 in the experimental group and 15 in the control group. The experimental group performed conventional physical therapy and neuromuscular electrical stimulation, and the control group received only conventional physical therapy, five times per week for four weeks. Outcome measures were assessed before and after 4weeks using the VAS(pain), quadriceps femoris strength, thigh circumference, and Q-angle. The data of the quadriceps femoris strength and thigh circumference were significantly increased in experimental group(p<0.05). The data the pain was significantly decreased in both the two groups(p<0.05). There were statistically significant differences in quadriceps femoris strength and thigh circumference between the two groups(p<0.05). As the result, the application of neuromuscular electrical stimulation of the vastus medialis could be more effective for decrease pain and improving muscle function in patients with knee osteoarthritis.

State Observer Based Modeling of Voltage Generation Characteristic of Ionic Polymer Metal Composite (상태 관측기 설계 기법을 적용한 이온성 고분자 금속 복합체의 전압 생성 특성 모델링)

  • Lee, Hyung-Ki;Park, Kiwon;Kim, Myungsoo
    • Composites Research
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    • v.28 no.6
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    • pp.383-388
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    • 2015
  • Ionic Polymer-Metal Composite (IPMC) consisting of soft membrane plated by platinum electrode layers on both surfaces generates electric energy when subjected to various mechanical stimuli. The paper proposes a circuit model that describes the physical composition of IPMC to predict the voltage generation characteristic corresponding to bending motion. The parameter values in the model are identified to minimize the RMS error between the real and simulated outputs. Following the design of IPMC circuit model, the state observer of the model is designed by using pole placement technique which improves the model accuracy. State observer design technique is also applied to find the inverse model which estimates the input bending angles from the output voltage data. The results show that the inverse model estimates input bending angles fairly well enough for the further applications of IPMC not only as an energy harvester but also as a bending sensor.

LMI Design of Multi-Objective$ Η_2/Η_\infty$Controllers for an Inverted Pendulum on the Cart Using Polytope Models (폴리토프 모델을 이용한 도립진자의 다목적$ Η_2/Η_\infty$ 제어기의 LMI 설계)

  • 이상철
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.6 no.1
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    • pp.6-13
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    • 2002
  • This paper deals with the linear matrix inequality (LMI) design procedures for multi-objective Η$_2$$_{\infty}$ controllers with pole-placement constraints for an inverted pendulum system modeled as convex polytopes to ensure the stabilizing regulator and tracking performances. Polytopic models with multiple linear time-invariant models linearized at some operating points are derived to design controllers overcoming the conservativeness such as a controller may have when it is designed for a model linearized at a single operating point. Multi-objective controllers are designed for polytopic models by the LMT design technique with convex algorithms. It is observed that the inverted pendulum controlled by any controller designed for each polytopic model is stabilizingly restored to the vertical angle position for initial values of larger tilt anlges.

Target Localization for DIFAR Sonobuoy compensated Bearing Estimation and Sonobuoy Position Error (방위각 추정 및 소노부이 위치 오차를 보상한 DIFAR 소노부이의 표적 위치 추정 성능 향상 기법)

  • Gwak, Sang-Yell
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.21 no.2
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    • pp.221-228
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    • 2020
  • A sonobuoy is dropped onto the surface of water to estimate the bearing of an underwater target. A Directional Frequency Analysis and Recording (DIFAR) sonobuoy has an error in the specific angular section due to the method of estimating bearing and noise, which causes an error in target localization using multiple sonobuoys. In addition, the position of the sonobuoy continues to move, but since a sonobuoy with a GPS is intermittently arranged, it is difficult to estimate the exact position of the sonobuoy. This also causes target localization performance degradation. In this paper, we propose a technique to improve the target localization performance by compensating for bearing errors using characteristics of the DIFAR sonobuoy and multiple-sonobuoy position errors based on the intermittently arranged active sonobuoy with a GPS.

A Study of effective installation patterns of face bolts using 3D-FDM analysis (터널 안정화를 위한 페이스볼트의 효율적 배치에 관한 수치해석적 연구)

  • Seo, Kyoung-Won;Bae, Gyu-Jin;Nishimura, Kazuo;Domon, Tsuyoshi
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.8 no.2
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    • pp.141-149
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    • 2006
  • For application of NATM, the self-supporting until installation of the supporting system must be satisfied. However, the face of a tunnel are always unsupported and therefore it is fairly vulnerable to tunnel collapses. Face blots are well known and widely used to prevent the deformation of the tunnel face and its circumference, which are installed horizontally toward the tunnel axis generally. To maximize the supporting effect of face bolts, this study has analysed the effective design patterns of face bolts by changing their installation angles. As the conclusion, it has been found that the axial displacement of the face increases slightly by installing the outermost bolts upward from the axis but surface settlement at 2.5D behind the face decreases up to 18%.

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Design of Servo Control System Using Bilinear Transformation Approach (쌍선형 변환법을 이용한 서어보 제어계 설계)

  • Kim, Sang-Bong;An, Hwi-Ung;Ji, Seok-Geun
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.26 no.1
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    • pp.81-87
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    • 1990
  • In this paper, a new design method in which transient response behavior of a servo~system can be improved, is proposed using a bilinear transformation method which assigns the poles of the closed-loop system in a specified region. The servo-system is a dynamic system which follows the given reference input automatically. In the above meaning, the design of a servo-system is similar to a regulator design problem for the extended system which is resulted from the given system and the reference input by the well known internal moel principle. In the design problem of servo control system, it is supposed that the proposed design method has more practical meaning in comparison to the other design methods, in the views of assigning the characteristic roots of the closed loop system in a specified region satisfying a design specification for the given transient response rather than in the exact positions of the poles. The applicability of the design method proposed in this paper was proved by the simulation results for the angle control problem of an electrical servo mechanism.

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Numerical Study on Air Egress Velocity in Vestibule Pressurization System : Damper Locationfor Uniform Air Egress Velocity in the case of Two Fire Doors (부속실 가압 시스템의 방연풍속에 관한 수치해석적 연구: 2개 출입문이 존재할 경우 균일한 방연풍속을 얻기 위한 댐퍼 위치 선정방법)

  • Seo, Chanwon;Shin, Weon Gyu
    • Fire Science and Engineering
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    • v.28 no.6
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    • pp.1-7
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    • 2014
  • Vestibule pressurization system should produce uniform air egress velocity to prevent the intrusion of smoke into escape route when fire accidents occur inside a building and fire doors are open for evacuation of people. Air supplying units in the vestibule need to be arranged by taking account of the location of doors and the volume of the vestibule. In this study, computational fluid dynamics (CFD) simulations were conducted for the vestibule where two doors are installed varying the location of a damper and louver angle. From simulations, we found that when the damper in the vestibule is located at the center of the wall opposite to two fire doors, the uniform air egress velocity can be obtained.

A Study on the Optimal Angle as Modified Tangential Projection of Knee Bones (무릎뼈의 변형된 접선방향 검사 시 최적의 입사각에 관한 연구)

  • Oh, Wang-Kyun;Kim, Sang-Hyun
    • Journal of the Korean Society of Radiology
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    • v.15 no.6
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    • pp.919-926
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    • 2021
  • In this study, we wanted to find out the optimal angle as a modified tangential projection of the patella. In the experiment, we used Kyoto Kagaku's PBU-50 phantom. In the supine position, the F-T angle was set to 95°, 105°, 115°, 125°, 135°, 145°, and Patella tangential projection images were obtained by varying the X-ray tube angle by 5° so that the angle between the X-ray centerline and tibia at each angle was 5~20°. Image J was used for image analysis and the congruence angle, lateral patellofemoral angle, patellofemoral index and contrast to noise ratio(CNR) were also measured. SPSS 22 was used for statistical analysis, and the mean values of congruence angle, patellofemoral angle, patellofemoral index, and CNR were compared with Merchant method through one-way batch analysis and corresponding sample t-test. As a result of the study, in the case of congruence angle, the angle of incidence of the knee-angle X-ray centerline was 105°-72.5° (20° tangential irradiation), 115°-72.5°, 77.5° (15, 20° tangential irradiation), 125°-82.5° (20° tangential irradiation), lateral patellofemoral angle is 115°-72.5°, 77.5° (15, 20° tangential irradiation), 125°-72.5° (10° tangential irradiation), patellofemoral index is 115°-72.5° (15° tangential irradiation) and 125°-72.5° (10° tangential irradiation) were not significantly different from Merchant method (p> .05). In case of CNR, it is not different from Merchant method at 105°-67.5°, 72.5° (15, 20° tangential irradiation), 115°-67.5°, 72.5°, 77.5° (10, 15, 20° tangential irradiation). (P> .05). Based on the results of this study, high diagnostic value images can be obtained by setting the knee angle and the angle of incidence of the X-ray tube to 115°-72.5° (15° tangential irradiation) during the modified tangential examination of the knee bone. It was confirmed.