• Title/Summary/Keyword: force improvement effectiveness

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Examination on Active Pneumatic Vibration Isolation Table with Moving Masses on It by Time Delay Control (이동 질량을 포함하는 능동형 공압제진대에 대한 시간지연제어기법의 적용 검토)

  • Shin, Yun-Ho;Moon, Seok-Jun;Chung, Jung-Hoon;Kim, Byung-Hyun
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.21 no.9
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    • pp.858-867
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    • 2011
  • As applying an active control technique to a pneumatic vibration isolation system, the settling time for the payload excitation could be remarkably reduced as well as the improvement of isolation performance for the ground vibration. Some previous researches were dealt with the settling time through the simulation or experiment but, the discussion on the simulation or experimental results including moving parts, such as a XY-stage, on the isolation table rarely exists. As considering the moving part, the dynamic model could be time varying system and in such a case the force imposed on pneumatic vibration isolation table could be described by inertial forces of moving parts according to Newton's 3rd law, the action and reaction law. In this paper, the simulation procedure of the 3-DOF active pneumatic vibration isolation system including moving parts by TDC(time delay control) technique is proposed and the effectiveness through simulation results are also shown.

Experimental and analytical evaluation of a low-cost seismic retrofitting method for masonry-infilled non-ductile RC frames

  • Srechai, Jarun;Leelataviwat, Sutat;Wongkaew, Arnon;Lukkunaprasit, Panitan
    • Earthquakes and Structures
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    • v.12 no.6
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    • pp.699-712
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    • 2017
  • This study evaluates the effectiveness of a newly developed retrofitting scheme for masonry-infilled non-ductile RC frames experimentally and by numerical simulation. The technique focuses on modifying the load path and yield mechanism of the infilled frame to enhance the ductility. A vertical gap between the column and the infill panel was strategically introduced so that no shear force is directly transferred to the column. Steel brackets and small vertical steel members were then provided to transfer the interactive forces between the RC frame and the masonry panel. Wire meshes and high-strength mortar were provided in areas with high stress concentration and in the panel to further reduce damage. Cyclic load tests on a large-scale specimen of a single-bay, single-story, masonry-infilled RC frame were carried out. Based on those tests, the retrofitting scheme provided significant improvement, especially in terms of ductility enhancement. All retrofitted specimens clearly exhibited much better performances than those stipulated in building standards for masonry-infilled structures. A macro-scale computer model based on a diagonal-strut concept was also developed for predicting the global behavior of the retrofitted masonry-infilled frames. This proposed model was effectively used to evaluate the global responses of the test specimens with acceptable accuracy, especially in terms of strength, stiffness and damage condition.

The Effect of a Sealed Cover and POSS-type Cutting Oil on MQL Drilling (MQL드릴링 가공에서 밀폐커버와 타입 절삭유의 효과)

  • Park, Ki-Beom;Cho, Young-Tae;Chin, Dong-Soo;Jung, Yoon-Gyo
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.15 no.6
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    • pp.77-82
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    • 2016
  • When drilling through Inconel 601 nickel-chromium-based alloys, a large amount of cutting oil is required to prevent tools from wear and fracturing due to heat buildup resulting from the high temperature resistance and toughness of this alloy. However, cutting oil supply has become a factor compromising the machining environment, and this has caused attention to shift to a more environmentally friendly cutting fluid supply system called minimum quantity lubrication (MQL). Our aim in this study was to find a more efficient drill processing method using MQL, and to verify its performance. To that end, we proposed a sealed cover, a step feed, and POSS-type cutting oil as measures to increase the effectiveness of MQL in view of the cutting force and tool wear, and established an improvement in efficiency using the proposed measures.

Design and Analysis of a Material Efficient Sinusoidal Consequent-Pole High-Speed Axial-Flux Machine

  • Kumar, Sunil;Kwon, Byung-il
    • Journal of IKEEE
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    • v.22 no.3
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    • pp.759-766
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    • 2018
  • This paper presents a high-speed axial-flux machine which utilizes the idea of sinusoidal shaped pole combined with a consequent iron-pole. The target of the proposed machine is the cost reduction of the relatively expensive Samarium-Cobalt (SmCo) permanent magnet (PM) material and the torque per PM volume improvement by using sinusoidal consequent-pole rotor. The effectiveness of the proposed machine is validated by comparing it with conventional consequent-pole and with conventional PM machines using 3-D finite element method (FEM) simulations. The comparison and analysis is done in terms of back electro-motive force (back-EMF) harmonic contents, torque per PM volume and torque ripple characteristics. The simulation results show that the proposed machine is suitable and cost-effective for high-speed and high torque per PM volume applications. Furthermore, due to the consequent pole, the magnetic flux saturation and the overload current torque-capability are also presented and discussed in the paper.

Effects of Transcutaneous Electrical Nerve Stimulation depending on Frequency and Intensity for Postural Sway during Sit to Stand with Stroke Patients

  • Byun, Dong-Uk;Shin, Won-Seob
    • The Journal of Korean Physical Therapy
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    • v.25 no.3
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    • pp.136-142
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    • 2013
  • Purpose: The application of transcutaneous electrical nerve stimulation (TENS) is beneficial for joint movements, inhibition of spasticity, and the improvement of walking ability in patients with chronic hemiplegia. This study aimed to identify the effect of the application of TENS to the knee extensor on the affected side with respect to postural-sway distance and velocity during the sit-to stand movement. Methods: We included 19 patients with post-stroke hemiplegia in this study. They underwent measurements during the sit-to stand movement on a force plate with 5 different stimulation dosages applied over 7 s:No TENS, high-frequency and high intensity TENS, high-frequency and low intensity TENS, low-frequency and high intensity TENS, and low-frequency and low intensity TENS The 5 different condition were administered in random order. Results: The group that received TENS application exhibited a significant decrease in path length and average velocity of center of pressure (COP) displacement compared with the group that did not receive TENS application. TENS dosage at low frequency (3Hz) and high intensity yielded a significant decrease in path length, average velocity, mediolateral distance and anteroposterior distance of COP displacement (p<0.05). Conclusion: Our results demonstrated the effectiveness of the application of low-frequency TENS on STS performance. These findings provide useful information on the application of TENS for the reduction of postural sway during the sit-to-stand movement after stroke.

Shear Strength and Seismic Behavior of the Composite Shear Wall with the Steel Plate Embedded in the RC Wall (철판삽입 합성전단벽의 전단강도와 내진거동)

  • Chun, Young-Soo;Park, Ji-Young;Lee, Jong-Yoon
    • Land and Housing Review
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    • v.8 no.3
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    • pp.211-221
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    • 2017
  • This study proposed hybrid coupled shear wall in the steel plate insertion method, which is capable of reinforcing the shear strength of the entire wall without increasing wall thickness in the wall-slab apartment buildings. The proposed hybrid coupled shear wall was tested for its effectiveness, shear strength and seismic behavior in experiment. As a test result, the shear strength improvement by the proposed hybrid coupled shear was found effective. Integral-type of steel plate insertion was found more effective than separate-type steel plate insertion. In this case, if the stud enforcement method proposed in this study was used, the shear strength of hybrid coupled shear wall was recommended to calculate using the KBC2016 0709.4.1(3) method. The steel plate inserted in the proposed method was found to have no significant impact on the final fracture behavior and bending strength of hybrid coupled shear wall. The shear strength at the final destruction of the wall was merely about 1/50 of the entire design shear strength. Thus, it is deemed that the wall was over excessively designed regarding the shear force in the existing design method. This finding indicates further study on wall designing to ensure effective and economic designing based on appropriate strength estimation under the destruction mechanism.

Analysis of Sealing Effectiveness Based on Spring Stiffness of a Spring-Energized Static Seal (스프링 보강 정적 실의 스프링 강성에 따른 기밀 성능 해석)

  • Jang, Soo Yeon;Sung, In-Ha
    • Tribology and Lubricants
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    • v.34 no.6
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    • pp.307-312
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    • 2018
  • Unlike a typical static seals, spring-energized static seals exhibit improvement in leak-tightness by reinforcing the spring inside the aluminum lining. Thus, spring-energized static seals are widely used in various industrial fields, such as aerospace, semiconductors, and petrochemical industries. The primary objective of this study is to develop design guidelines for spring-energized static seals in a wide range of temperatures, including that of cryogenic environments, by analyzing the required performance and influence of design variables through simulations. There are various parameters that can be controlled to design a leak-tight seal. In this study, the finite element analysis (FEA) is performed by controlling the parameters related to the spring and the thickness of the aluminum lining, and the result of the leakage between the seal and the casing is confirmed. Considering the influence of each parameters, all of them are found to be important. However, it is observed that the spring-related variables are more important than the aluminum lining or other variables when complexity is considered. We can identify the threshold value of spring stiffness that changes leak-tight performance of the seal by performing FEA. Simulation results, under the conditions that are considered in this study, show that spring stiffness should be at least 3.6 N/m to maintain leak-tightness caused by the sufficient contact force between the aluminum lining and the upper and lower casings.

Design and Implementation of a Cohort for Quality Management of Medical Education: A Case Study from Konyang University College of Medicine (교육의 질 관리를 위한 의과대학 코호트 구축과 운영: 건양대학교 의과대학 사례)

  • Kyunghee Chun;Tae Hee Lee;Soojin Jung;Young-soon Park
    • Korean Medical Education Review
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    • v.25 no.2
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    • pp.102-108
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    • 2023
  • This study shares details on the operating process and results of the cohort of students and graduates that was designed and implemented at Konyang University College of Medicine in Daejeon and discusses future directions for cohort establishment and improvement. First, Konyang University College of Medicine established the necessity and defined the purpose of cohort design and implementation. A task force was formed to establish guidelines for analysis targets, procedures, reports, and data management, and cohort operation was classified as a quality control activity. Data were collected through surveys of current students and graduates, and data generated during the curriculum were collected, analyzed, and reported every 2 years. The cohort data collection and analysis methods are designed by the Department of Medical Education, and data collection is carried out by the administrative team and each committee. Data management and analysis are handled by the Center for Medical Education Support, and analysis and reporting are conducted by the Department of Medical Education. Various members of the medical school are working to collect and analyze data, report findings, provide feedback, and improve. In the future, we plan to advance database computerization and work toward more effective data analysis. Cohort operation should not be another burden for medical schools; instead, it is hoped that operating cohorts will be a meaningful activity to increase the effectiveness of medical education and help in the operation and policy decisions of medical schools.

Improvement of Runtime Intrusion Prevention Evaluator (RIPE) (실행시간 침입 방지 평가 프로그램(RIPE)의 개선)

  • Lee, Hyungyu;Lee, Damho;Kim, Taehwan;Cho, Donghwang;Lee, Sanghoon;Kim, Hoonkyu;Pyo, Changwoo
    • Journal of KIISE
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    • v.42 no.8
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    • pp.1049-1056
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    • 2015
  • Runtime Intrusion Prevention Evaluator (RIPE), published in 2011, is a benchmark suite for evaluating mitigation techniques against 850 attack patterns using only buffer overflow. Since RIPE is built as a single process, defense and attack routines cannot help sharing process states and address space layouts when RIPE is tested. As a result, attack routines can access the memory space for defense routines without restriction. We separate RIPE into two independent processes of defense and attacks so that mitigations based on confidentiality such as address space layout randomization are properly evaluated. In addition, we add an execution mode to test robustness against brute force attacks. Finally, we extend RIPE by adding 38 attack forms to perform format string attacks and virtual table (vtable) hijacking attacks. The revised RIPE contributes to the diversification of attack patterns and precise evaluation of the effectiveness of mitigations.

Efficacy and Safety of Cheong-A-Won Gagambang (JCE003) on Knee Osteoarthritis: Randomized Controlled Pilot Trial

  • Kong, Haejin;Kang, Jaehui;Lee, Hyun
    • Journal of Acupuncture Research
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    • v.39 no.3
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    • pp.202-212
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    • 2022
  • Background: The aim of this study was to evaluate the effectiveness and safety of Cheong-A-Won Gagambang (JCE003) treatment for degenerative knee osteoarthritis. Methods: This was a single-center, randomized, double-blind, placebo-controlled pilot clinical trial. There were 36 adults with degenerative knee osteoarthritis who were randomly allocated into JCE003 1,000 mg, JCE003 2,000 mg, or the placebo group (in a 1:1:1 ratio). The participants received 12 weeks of treatment and had scheduled tests every 6 weeks. The primary outcomes were measured using the Korean Western Ontario and McMaster Universities scale, and the secondary outcomes were measured using the visual analog scale, European quality of life-5-dimensions, patient global impression of change, C-reactive protein, and erythrocyte sedimentation rate. Changes between baseline scores and scores following study completion were analyzed. Results: There were 29 participants whose data were analyzed in this study. The change of Korean Western Ontario and McMaster Universities, visual analog scale, European quality of life-5-dimensions scores showed significant improvement in the JCE003 1,000 mg group. The change of patient global impression of change was significantly improved in the placebo group. There were 14 adverse events, but there was no clinically significant relationship with the intake of JCE003 compared with the placebo. Conclusion: Taking JCE003 may be effective at improving knee pain in patients with degenerative knee osteoarthritis and appears to be safe. Based on this study, the concentration and feasibility of the test group may be used when conducting a large-scale clinical trial of degenerative knee osteoarthritis in the future.