• Title/Summary/Keyword: crossing changes

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A Study on the Power Factor Improvement of Single-Phase Bridgeless Voltage Doubler Converter (단상 브리지리스 배전압 변환기의 역률 개선에 관한 연구)

  • Koo, Do-Yeon;Kim, Dong-Wook;Lim, Seung-Beom;Hong, Soon-Chan
    • Proceedings of the KIPE Conference
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    • 2011.11a
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    • pp.169-170
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    • 2011
  • PFC(Power Factor Correction) converters are commonly designed for CCM(Continuous Conduction Mode). However, DCM(Discontinuous Conduction Mode) appears in the input current near the ZCP(Zero Crossing Point) at light loads, resulting in input current distortion. It is caused by inaccurate average current values obtained in DCM. This paper studies a simple digital control scheme that can be operated in both CCM and DCM with minimal changes to the CCM average current control structure.

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A Study on Muscle Fatigue Changes using AR Model-based Median Frequency in EMG (AR모델을 이용한 중앙주파수의 근피로 변화에 관한 연구)

  • Cho, EunSeuk;Cha, Sam;Lee, Sangsik;Lee, Kiyoung
    • The Journal of Korea Institute of Information, Electronics, and Communication Technology
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    • v.2 no.1
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    • pp.17-22
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    • 2009
  • In this paper, we extract well-known parameters such as zero crossing rate(ZCR), low band energy(Band) and median frequency(MDF) from surface electromyogram (EMG), and compare to evaluate themselves as measures for fatigue. In experiments, 3 males and 3 females volunteered to participate in surface EMG recordings placed on the biceps brachii and each recording experiment continued until exhaustion.

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The Relation between Human Behavior and Safety in the Collision Avoidance Situation

  • Park, Jung-Sun;Kobayashi, Hiroaki;Yea, Byeong-Deok
    • Journal of Navigation and Port Research
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    • v.27 no.6
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    • pp.611-618
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    • 2003
  • It can be said that the relationship between the maneuvering ability of operators and the navigational environment affects the safe degree of navigation in the collision avoidance situation. In order to reduce the occurrence probability of accident and to maintain the safety, it is necessary to clarify the relationship between human behavior and navigational environment. In this study, therefore, we analyzed and discussed the relationship between the maneuvering characteristics and the safety focused on human behavior as a fundamental factor of marine accidents using ship handling simulator and questionnaire. As a result, we concluded that navigational environment changes variously and the maneuvering ability of operators also varies with the navigational environment, and the ship handling characteristics strongly affect the occurrence probability of accident.

A New Analytical Representation to Robot Path Generation with Collision Avoidance through the Use of the Collision Map

  • Park Seung-Hwan;Lee Beom-Hee
    • International Journal of Control, Automation, and Systems
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    • v.4 no.1
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    • pp.77-86
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    • 2006
  • A new method in robot path generation is presented using an analysis of the characteristics of multi-robot collision avoidance. The research is based on the concept of the collision map, where the collision between two robots is presented by a collision region and a crossing curve TLVSTC (traveled length versus servo time curve). Analytic collision avoidance is considered by translating the collision region in the collision map. The 4 different translations of collision regions correspond to the 4 parallel movements of the actual original robot path in the real world. This analysis is applied to path modifications where the analysis of collision characteristics is crucial and the resultant path for collision avoidance is generated. Also, the correlations between the translations of the collision region and robot paths are clarified by analyzing the collision/non-collision areas. The influence of the changes of robot velocity is investigated analytically in view of collision avoidance as an example.

A Study on the Micro-Propagation of Landscape-Plants (조경식물의 Micro-Propagation에 관한 연구)

  • 주명칠
    • Journal of the Korean Institute of Landscape Architecture
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    • v.21 no.1
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    • pp.83-94
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    • 1993
  • After coming this century, as the propagative method of plants on a scientific foundation has been accompanied systematically, it has played an important part in the improvement of cultivar. But an existing propagative technique is not a few defects in our tasks and industrial structure which changes every hour and envirnment which undergoes a sudden change. To use developed biological knowledge recently, and existing propagative method which is main axis in sexual reproductive crossing, is increased much in the inside of internal organs by asexual reproductive means which is on a different level, and by, introducing a new character, it improves an inherited character etc. We have observed methods which supplement or replace a defect. These methods are not yet ripe for putting to practical use in the present research phase but convinced that they will offer an epoch-marking turning point.

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Change of Operating Characteristics of Latching Relay with Temperature (래칭 릴레이의 온도에 따른 동작 특성 변화)

  • Ryu, Jae-Man;Jin, In-Young;Huh, Chang-Su
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.30 no.8
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    • pp.520-524
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    • 2017
  • Electrical relay in an essential part of smart grids, electrical vehicles, and LED lightning systems. Therefore, studying relay reliability is important. Relays using permanent magnet actuators (PMAs), which are energy efficient, are also in the spotlight. However, most of the permanent magnets used in PMAs have a characteristic wherein the magnetic flux decreases as the temperature increases. When the magnetic flux is reduced, the force acting on the actuator is reduced. Therefore, in this study, we measured the decrease in the relay operating speed with permanent magnet reduction due to temperature rise. In addition, changes in the bouncing phenomena due to magnetic flux reduction were analyzed. As a result, the operating speed of the relay has decreased and the bouncing phenomenon has not significantly changed.

Uncanny as Aesthetic Experience (심미적 경험으로서의 언캐니)

  • Lee, Joo-eun
    • Psychoanalysis
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    • v.28 no.3
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    • pp.69-75
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    • 2017
  • This paper interprets the work of Hans Bellmer, who took pictures after making a doll and distorting its form, and Diane Arbus, who took documentary photographs of unusual and marginalized people, as uncanny anxiety referred to by Freud. Through these two photographers' works, this paper examined how anxiety was used as an aesthetic strategy, and discussed the uncanny as an aesthetic experience. Uncanny refers to the phenomenon of familiar things being repressed and returning to their original place, or the phenomenon of familiarity being alienated due to repression. The aesthetic strategy of uncanny is used to bring a blind spot in reality that can be easily missed with an ordinary vision into the fore, by allowing for the slight shock to an appreciator. The ultimate goal of uncanny aesthetics is to promote both inner and external changes as well as to expand the scope of imagination, through freely crossing the borders between consciousness and unconsciousness, sympathy and antipathy, and reality and fiction.

Self-Diffusion Coefficients of Colloidal Association Structures in ADS/OTAC Mixed Aqueous Solutions by Pulsed (Field) Gradient Spin Echo-NMR (Pulsed (Field) Gradient Spin Echo (PGSE) NMR에 의한 ADS/OTAC 혼합 수용액에서의 콜로이드 회합체의 자가 확산 계수)

  • Kim, Hong-Un;Lim, Kyung-Hee;Kim, Eun-Hee;Cheong, Chae-Joon
    • Journal of the Korean Applied Science and Technology
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    • v.19 no.4
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    • pp.339-348
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    • 2002
  • Self-diffusion coefficients of colloidal ass9Ciation structures in the aqueous solutions of anionic ammonium dodecyl sulfate (ADS) and cationic octadecyltrimethylammonium chloride (OTAC) surfactants were measured by pulsed-gradient spin echo NMR. The results were interpreted on the basis of the ADS/OTAC/water phase diagram. Crossing the phase boundaries, significant changes in self diffusion coefficients were observed and well correlated to the phase diagram. For the micelles their apparent radii were obtained from Stokes-Einstein equation. Their values were 15 for the ADS micelles and 54 ${{\AA}}$ for the OTAC micelles, respectively. For vesicles which were formed spontaneously at different relative amounts of the surfactants and total surfactant concentrations, the radius was measured as 50 to 200 nm. This result is in fair agreement with those by TEM and light scattering.

Design of Roll Rate Estimator using GPS Signal for Spinning Vehicle

  • Lee, Sunyong;Jin, Mihyun;Choi, Heon Ho;Lee, Sang Jeong
    • Journal of Positioning, Navigation, and Timing
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    • v.5 no.3
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    • pp.109-118
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    • 2016
  • The present paper proposes a method that can estimate a roll rate of spinning vehicles utilizing GPS receivers. The proposed method analyzes a relation between received signal and correlation value and utilizes a phenomenon that received signal power that changes according to a signal incident direction affects a correlation value. That is, a roll-rate estimation method using zero crossing detection method for correlation value, which has sinusoidal periodicity according to rotations of vehicles, is proposed. A correlation value in real environments experiences a jitter so that the proposed method includes a pre-processing filter and detection threshold setting way is also considered to reduce the effect of received signal power. In order to verify the operation of the proposed method and analyze the performance, a signal generator and software-defined receiver (SDR) are designed. The signal generator generates intermediate frequency (IF) signal by taking the rotation of vehicles, antenna gain, and signal power into consideration, and a correlation value is acquired by taking the generated IF signals into consideration. Using the generated correlation value, the operation of the proposed roll rate estimation method is verified and the performance is analyzed.

The Effect of Obstacle Height on Balance Control While Stepping Over an Obstacle From a Position of Quiet Stance in Older Adults (노인의 정적인 자세로부터 장애물 보행 시 장애물 높이의 변화가 평형감각에 미치는 효과)

  • Kim, Hyeong-Dong
    • The Journal of Korean Physical Therapy
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    • v.21 no.3
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    • pp.75-80
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    • 2009
  • Purpose: The purpose of this study was to examine the effect of an obstacle height on the balance control of older adults while stepping over an obstacle from a position of quiet stance. Methods: Fifteen community-dwelling healthy older adults (mean age, $74.4\pm4.27$ yrs; age range, 67-82 yrs) volunteered to participate in this study. The subjects performed gait initiation (GI) and they stepped over obstacles of two different heights (10 cm and 18 cm) at a self-paced speed from a position of quiet stance. Their performance was assessed by recording the changes in the displacement of the COP in the anteroposterior (A-P) and mediolateral (M-L) directions using a force platform. Results: The M-L displacement of the COP significantly increased for an 18 cm obstacle height condition as compared to the GI and a 10 cm obstacle height condition (p<0.01). Furthermore, the M-L displacement of the COP for a 10 cm high obstacle was significantly greater for that for the GI (p<0.01). However, the mean of the A-P displacement of the COP was similar between the stepping conditions for the A-P displacement of the COP (p>0.05). Conclusion: This study suggests that the M-L COP displacement could be a better parameter to identify the dynamic balance control in older adults when negotiating obstacles.

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