• Title/Summary/Keyword: Heo-Control Technique

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Experiment on Performance of Vibration Isolation System (능동 고립 시스템의 성능 실험)

  • Kim, Seung-Rok;Heo, Seok;Kwak, Moon-K
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2003.05a
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    • pp.142-147
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    • 2003
  • This paper is concerned with the experiment of vibration isolation device whit can cope with heave, pitch and roll type vibrations. This new device consists of S-shaped piezoceramic actuators supporting each corner of the plate. Small piezoceramic sensors are located at the middle of each side. This paper also presents the development and the movement of the system. The active control technique was also developed to cope with base excitation. Experimental results show that vibrations can be reduced by the new device in the case of base excitation of harmonic type.

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Efficient CP Reconstruction Algorithm for High Speed Data Transmission System with WiBro system (WiBro 시스템에서 고속 데이터 전송 시스템을 위한 효율적인 CP 재편성 알고리즘)

  • Kim, Yoon-Ryun;Heo, Si-Young;Koo, Sung-Wan;Yang, Jae-Soo;Kim, Jin-Young
    • 한국정보통신설비학회:학술대회논문집
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    • 2008.08a
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    • pp.398-402
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    • 2008
  • Cyclic prefix (CP) is one of the most important technique to OFDM system and is reducing inter-symbol interference (ISI) effects in high speed wireless mobile communication system. At the time varying channel condition, however, fixed CP length is not only increasing power consumption but also reducing data transmission rate. So in this paper, we propose the system that has adaptive CP length for high speed data transmission system. We don't control CP length of every symbol but adjust symbol interval depending on channel condition to CP reconstruction.

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RESPONSE ANALYSIS OF A STOCHSTIC UNDER PARAMETRIC ND EXTERNL EXCITATION HAVING COLORED NOISE CHARACTERISTICS (유색잡음 매개변수가진과 외부가진을 받는 확률 시스템의 응답해석)

  • Heo, Hoon;Paik, Jong-Han;Oh, Jin-Hyong
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 1993.10a
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    • pp.55-59
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    • 1993
  • Interaction between system and disturbance results in system with time-dependent parameter. Parameter variation due to interaction has random characteristics. Most of the randomly varying parameters in control problem is regarded as white noise random process, which is not a realistic model. In real situation those random variation is colored noise random process. Modified F-P-K equation is proposed to get the response of the random parametric system using some correction factor. Proposed technique is employed to obtain the colored noise parametric system response and confirmed via Monte-Carlo Simulation.

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A Study on the Impact of CSA on Internal Control (CSA가 내부통제에 미치는 영향)

  • Park, Seong-Kyu;Heo, Young-Kyun;Jeong, Jeong-Seob
    • Korean Business Review
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    • v.18 no.2
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    • pp.45-60
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    • 2005
  • CSA(Control Self Assessment) is a new internal control technique whose objective is to control the human resource performance, the manager's philosophy, the business ethics, the effective communication and decision making etc. The purpose of this study is to find out if the CSA improve the quality of internal control. With the questionnaire method the following conclusions are reached. 1) Level of the management supports influence the level of the workshop participation. 2) Anonymity during the workshop session influences the level of workshop participation. 3) Level of the organizational committment influences the level of the participation 4) The level of workshop performance significantly influences the level of internal contro improvement.

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Tension Control of a Winding Machine using Time-delay Estimation (시간 지연 추정 기법을 이용한 권취기의 장력 제어 알고리즘)

  • Heo, Jeong-Heon;You, Byungyong;Kim, Jinwook
    • Journal of Drive and Control
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    • v.15 no.3
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    • pp.21-28
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    • 2018
  • We propose a tension controller based on a time-delay estimation (TDE) technique for a winding machine. Firstly, we perform the necessary calculations to derive a mathematical model of the winding machine. In this sense, it is revealed that the roll radius of the winding machine is characteristically seen to be increasing or decreasing during the winding process. That being said, it is noted that the parameters of the winding machine are coupled and constantly changing during this process. Understandably then, it is noted that the model is shown to be nonlinear and time-varying. Secondly, we propose the way to apply the TDE based controller which is the so-called Time-delay Control (TDC). The TDC utilizes the time-delayed information intentionally to compensate the nonlinear and time-varying characteristics. As we have seen, the proposed controller consists of two parts: one is a TDE component, and the other is an error dynamics component which is defined by a user. In a computer simulation based on the Matlab/Simulink program, the proposed controller is compared with a conventional PID controller, which is widely used in the tension control of the winding machine. The proposed controller reduces the incidence of overshoot and steady-state error in the tension control, as compared to the conventional PID controller.

Effect of Encapsulated Bacteriocin on Acid Production and Growth of Starter Cultures in Yoghurt

  • Oh, Se-Jong;Heo, Ho-Jin;Park, Dong-June;Kim, Sae-Hun;Lee, Sung-Je;Imm, Jee-Young
    • Food Science and Biotechnology
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    • v.15 no.6
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    • pp.902-907
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    • 2006
  • Freeze dried crude bacteriocin was encapsulated within an acid-soluble coating material, Eudragit EPO, using a surface modification technique through a hybridization system. The pH and titratable acidity of control yoghurt were 3.92 and 1.56%, respectively, after 24 hr of fermentation at $42^{\circ}C$, whereas yoghurt containing 500 AU/mL encapsulated bacteriocin exhibited a higher pH (4.37) and lower titratable acidity (1.2%). Yoghurt containing encapsulated bacteriocin had significantly lower titratable acidity when the duration of fermentation (to pH 4.5) and subsequent refrigerated storage ($4^{\circ}C$) was longer than 20 days. There were no significant differences in the viability of lactic acid bacteria after 15 hr of fermentation. This suggests that microencapsulated bacteriocin has the potential to control the excessive growth of yoghurt starters caused by temperature abuse or post-acidification.

A New Algorithm for Control of Robotic Arc Welding Process (로봇 아크용접 공정제어를 위한 새로운 알고리즘)

  • Park, Yo-Chang;Kim, Il-Su;Park, Chang-Eon;Kim, Jung-Sik;Heo, Eop;Jung, Young-Jae
    • Proceedings of the KWS Conference
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    • 2001.05a
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    • pp.65-68
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    • 2001
  • The application of a feedback control system in robotic arc welding is becoming more and more demanding than ever before. This requirement arises from the fact that robotic arc welding process needs no manual operator to monitor and manipulate the process parameters and hence a means of controlling the quality of the robotic arc welding process becomes apparent. Arc force sensor employed in this research to monitor the bead geometry of the arc welding process, A relationship between the bead dimension and the arc force distributions was established. Experimental configuration for measurement of arc force was used to quantify the changes in the arc force distributions of the plate being welded. Arc force sensor mounted at the end of the robot wrist was employed to measure the arc force applied to the weld. The sensor information was the used to establish a relationship between welding current and arc force. Arc force sensor have shown to be on of the most sophisticated technique to monitor perturbations that occurred during arc welding process.

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A Study on Operation Characteristics of Co-flow Fluidic Thrust Vector Control under Over-expanded Jet Condition (동축류 이차유동 분사를 이용한 초음속 과팽창 제트유동의 유체역학적 추력방향제어 작동특성 연구)

  • Heo, Jun-Young;Jeon, Dong-Hyun;Lee, Yeol;Sung, Hong-Gye
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.39 no.5
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    • pp.416-423
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    • 2011
  • The purpose of this research is to investigate the operation characteristics of fluidic thrust vector control using injection of the control flow parallel to the main jet direction; Co-flow injection. The technique bases on the Coanda effect of flow. Both numerical and experimental studies were conducted to investigate operation parameters; flow structure, the jet deflection angle, and shock effects near the nozzle exit. While the total pressure of main jet is the range of 300 to 790 kPa, the total pressure of control flow varies from 120 to 200 kPa. The jet deflection angle and thrust coefficient have linear relation with the pressure ratio(PR) of main jet to control flow in 0.15 < PR < 0.4 but show their limit above PR = 0.4.

BIOMECHANICAL EVALUATION ON BONE REGENERATION IN MANDIBULAR DISTRACTION OSTEOGENESIS COMBINED WITH COMPRESSION STIMULATION (하악골 신장술에서 압축자극을 통한 골 재생방식에 대한 생체 역학적 평가)

  • Heo, June;Kim, Uk-Kyu;Hwang, Dae-Seok;Kim, Yong-Deok;Shin, Sang-Hun;Chung, In-Kyo;Kim, Cheol-Hun;Yun, Seok-Young
    • Journal of the Korean Association of Oral and Maxillofacial Surgeons
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    • v.33 no.5
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    • pp.470-478
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    • 2007
  • The purpose of this study was to investigate the clinical, biomechanical, and histologic changes in new distraction osteogenesis(DO) technique combined with a compression stimulation in accordance to different compression-distraction force ratio. 23 adult male rabbits underwent open-osteotomy at the mandibular body area and a external distraction device was applied. In the control group of 8 rabbits, only a 8 mm of distraction was performed by conventional DO technique. In an experimental group of 15 rabbits, a distraction followed by a compression force was performed according to the ratio of compression-distraction suggested by authors. The rate of experimental group I was set up as a 2 mm compression versus 10 mm distraction and the rate of experimental group II was set up as a 3 mm compression versus 11 mm distraction. All the rabbits were sacrificed for a gross finding, biomechanical, histomorphometric and histologic findings at the time of 55 days from the operation day. The results were as follows: 1. On the gross findings, because all rabbits had a sufficient healing time, every distracted new bone had good bone quality and we could not find any difference among all three groups. 2. In the histologic findings, rapid bone maturation(wide lamellar bone formation in the cancellous and cortical bone areas) was observed in two experimental groups compared to the control group. 3. On the bone density tests, the experimental group II showed higher bone density than the other experimental group and control group(control group-$0,2906g/cm^2$, experimental group I-$0.2961g/cm^2$, experimental group II-$0.3328g/cm^2$). 4. On the biomechanical tests, the experimental group II had significantly higher bone microhardness than the other experimental group and control group(control group-252.7 MPa, experimental group I-263.5 MPa, experimental group II-426.0 MPa). 5. On the microhardness tests, when we compared the hardness ratio of distracted bone versus normal bone, we could find experimental group II had significantly higher hardness ratio than the other experimental group and control group(control group-0.47, experimental group I-0.575, experimental group II-0.80). From this study, we could deduce that the modified distraction osteogenesis method with a compression stimulation might improve the quality of bone regeneration and shorten the consolidation period in comparison with conventional distraction osteogenesis techniques.

MANDIBULAR DISTRACTION OSTEOGENESIS WITH COMPRESSION FORCE - BONE DENSITY, HISTOLOGICAL FINDINGS AND TMJ RESPONSE (압축력을 병용한 하악골 신장술)

  • Hwang, Young-Seob;Heo, June;Kim, Uk-Kyu;Park, Seong-Jin;Hwang, Dae-Seok;Kim, Yong-Deok;Chung, In-Kyo;Kim, Kyu-Cheon
    • Maxillofacial Plastic and Reconstructive Surgery
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    • v.28 no.6
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    • pp.531-548
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    • 2006
  • The purpose of this study was to investigate the biomechanical, histologic findings of distracted regenerate and TMJ response in modified distraction osteogenesis (DO) technique combined with compression force as biomechanical stimulation method which has been suggested in 2002, and developed thereafter by authors. This study was performed with two experiments. First experiment was designed to explore the optimal ratio of compression force versus distraction force for the new DO technique. Second experiment was planned to evaluate the reaction of TMJ tissue, especially condyle, disc after application of the DO technique with compression force. Total 52 New Zealand adult male-rabbits with 3.0kg body weight were used for the study. For the first study, 30 adult male-rabbits underwent osteotomy at one side of mandibular body and a external distraction device was applied on each rabbit with same manner. In the control group of 10 rabbits, final 8 mm of distraction with 1 mm rate per day was done with conventional DO technique after 5 latency days. For the experimental group of 20 rabbits, a compression force with 1 mm rate per day was added to the distracted mandible on 3-latency day after over-distraction (over-lengthening). As the amount of the rate of compression versus distraction, experimental subgroup I (10 rabbits) was set up as 2 mm compression versus 10 mm distraction (1/5) and experimental subgroup II (10 rabbits) was set up as 3 mm compression versus 11 mm distraction (about 1/3). All 30 rabbits were set up to obtain final 8 mm distraction and sacrificed on postoperative 55 day to analysis on biomechanical, and histologic findings of the bone regenerates. For second study, 22 adult male-rabbits were used to evaluate TMJ response after the DO method application with compression force. In the control group, 10 rabbits was used to be performed with conventional DO method, on the other hand, in a experimental group of 10 rabbits, 10 mm distraction with 2 mm compression (1/5 ratio) was done. The remaining 2 rabbits served as the normal control group. Histomorphologic examinations on both condyle, histological studies on condyle, disc were done at 1, 2, 3, 4, 7 weeks after distraction force application. The results were as follows: 1. On the bone density findings, the experimental group II (force ratio - 1/3) showed higher bone density than the other experimental group (force ratio - 1/5) and control group (control group - $0,2906\;g/cm^2$, experimental group I - $0.2961\;g/cm^2$, experimental group II - $0.3328\;g/cm^2$). 2. In the histologic findings, more rapid bone maturation like as wide lamellar bone site, more trabeculae formation was observed in two experimental groups compared to the conventional DO control group. 3. In morphologic findings of condyle, there were no differences of size and architecture in the condyle in the control and experimental groups. 4. In histologic findings of condyles, there were thicker fiberous and proliferative layers in experimental group than those of control group until 2 weeks after distraction with compression force. But, no differences were seen between two groups on 3, 4, 7 weeks after compression. 5. In histologic findings of disc, more collagen contents in extracellular matrix, more regular fiber bundles, and less elastin fibers were seen in experimental group than control group until 2 weeks after distraction with compression. But, no differences were seen between two groups on 3, 4, 7 weeks after distraction with compression. From this study, we could identify that the new distraction osteogenesis technique with compression stimulation might improve the quality of bone regeneration. The no remarkable differences on TMJ response between control and experimental groups were seen and TMJ tissues were recovered similarly to normal TMJ condition after 3 weeks.