• Title/Summary/Keyword: Quasi-Experiment Design

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Design of a compact coplanar waveguide-fed 2-element quasi-Yagi antenna (코플래너 도파관으로 급전되는 소형 2-소자 준-야기 안테나 설계)

  • Baek, Woon-Seok
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.20 no.12
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    • pp.2199-2205
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    • 2016
  • In this paper, a design method for a coplanar waveguide (CPW)-fed 2-element quasi-Yagi antenna (QYA) is studied. A balun between CPW and coplanar strip (CPS) which feeds a planar dipole is implemented by connecting the one end of ground strips in a CPW to a signal strip. The antenna size is reduced by bent strip dipole and reflector, and an integrated balun. The proposed antenna was designed for the operation in a UHF radio frequency identification (RFID) band of 902-928 MHz, and the effects of various parameters such as dipole length, reflector length, distance between dipole and reflector, feed position were examined. The antenna with a size of $90mm{\times}80mm$ was fabricated on an FR4 substrate, and the experiment results reveal a frequency band of 885-942 MHz for a voltage standing wave ratio < 2, a gain > 4.3 dBi, and a front-to-back ratio > 7 dB over the frequency band for the UHF RFID.

Study on Reinforcement Effect of Circular RC Columns by Helical Bar Under Cyclic Lateral Load (반복 횡하중을 받는 원형 철근콘크리트 기둥의 Helical Bar 보강효과에 대한 연구)

  • Kim, Seong-Kyum;Park, Jong-Kwon;Han, Sang-Hee;Kim, Byung-Cheol;Jang, Il-Young
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.18 no.1
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    • pp.48-58
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    • 2014
  • In this study, quasi-static according to the displacement-controlled (strain control) method tests on RC columns for seismic reinforcement performance in accordance with the provisions of the seismic design and construction before 1992 design code for highway bridges in korea. Used reinforcement that improves the performance of Inorganic Helical Bar, a kind of alloy steel, circular columns were tested outside the seismic reinforcing. In the experiment, fracture behavior, lateral load-displacement relation, ductility and energy assessment evaluation was performed through tests. The variables in experimental are section force of reinforcement, spiral reinforcement spacing, reinforcement method. Improved seismic performance and effect were confirmed through quasi-static test experiments. The results of study confirmed determination the appropriate size of reinforcement, reinforcement forces, spacing and selection of the type required, furthermore, not only mechanical reinforcement but also substitution of high-strength concrete reinforced with concrete cover improved seismic performance.

Experiment and Analysis of Mooring System for Floating Fish Cage (해상 양식시설의 계류시스템 실험 및 해석)

  • KIM Jin-Ha;KIM Hyeon-Ju;HONG Sup
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.34 no.6
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    • pp.661-665
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    • 2001
  • This paper deals with optimal mooring system to secure fish cage in a desired location, Through field investigation and paper works, we surveyed disasters by breakdown of cage frame and mooring system due to higher wave attack and selected compliant buoy mooring method for shallow water mooring system against severe coastal external forces. To analyze interaction between external forces and compliant buoy mooring system, theoretical model has developed as quasi-static nonlinear analysis. After verifying the feasibility of the numerical model compared with experiment, static analysis has tried for various mooring systems with different angle of array, number of mooring points, length of horizontal and inclined rope. Optimal mooring method using compliant buoy has selected for fish cage through numerical simulation. This results can apply for preliminary design for cage mooring system.

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The Effects of Foot Reflexology Massage on Sleep and Fatigue of Elderly Women (발반사 마사지가 여성노인의 수면과 피로에 미치는 효과)

  • Jin, Su Jin;Kim, Yeong Kyeong
    • Korean Journal of Adult Nursing
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    • v.17 no.3
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    • pp.493-502
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    • 2005
  • Purpose: To investigate the effects of foot reflexology massage on sleep and fatigue of elderly women. Method: The study was performed from April thru July of 2004 on the nonequivalent control group non-synchronized quasi-experimental design. Fifty elderly women were selected for each group. The foot reflexology massage was performed for 45 minutes every three days for experimental group. The data were analyzed using the Cronbach's $\alpha$, Chi-Square test, t-test and Repeated measures ANOVA and Bonferroni. Result: 1. The sleep score of the experiment group is significantly higher than that of the control group(t=-5.944, p=.000). 2. For the experiment group, it is seen that the sleep score increases as the frequency of the foot reflexology massage increases(F=96.362, p=.000). 3. The fatigue score of the experiment group is significantly lower than that of the control group(t=4.356, p=.000). 4. For the experiment group, the fatigue is relieved gradually as the frequency of the foot reflexology massage increases(F=118.444, p=.000). Conclusion: Based on the results described above, it is considered that the foot reflexology massage is effective for elderly women in promoting a good sleep and relieving the fatigue.

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The Effect of Motives of Ramie Fabrics on Sensory Image Evaluation (모시 소재의 문양에 따른 감성 이미지 평가)

  • Lee, Soon-Im;Kim, Jae-Sook
    • The Research Journal of the Costume Culture
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    • v.14 no.6
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    • pp.1015-1026
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    • 2006
  • The purpose of the study were to find out (1) the effect of motives on perceiver's image perception on ramie fabrics, and perceiver's trait, age and gender on sensory image evaluation of ramie fabrics. The research was a quasi experiment and experimental materials developed for the study were a set of material stimuli and semantic differential scales to measure sensory image of the stimuli, an aesthetic value scale. the independent design was motif design techniques(Plain Weave, burnt-out, embroidery, stripe, check). The subjects were 421 adults in Daejeon and Seachun. The results was as follows: The factor analysis of semantic differential scales for the ramie materials emerged 4 different image dimensions: attractiveness, hand, elegance, weight). The five design techniques showed significantly different image affects on some selective dimensions. The burn-out design gave the most attractive image, the embroidery design gave the softest image and plain weaved fabric presented the lightest hand image. Consumer's aesthetic values, gender and age tended to affect sensory image evaluation of ramie materials. On conclusion the result revealed that design strategy for the ramie material, design development though motives will be an essential process. and for material design pursued design image and target consumer's trait should be carefully considered.

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Flutter and Buffeting Control of Long-span Suspension Bridge by Passive Flaps: Experiment and Numerical Simulation

  • Phan, Duc-Huynh;Nguyen, Ngoc-Trung
    • International Journal of Aeronautical and Space Sciences
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    • v.14 no.1
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    • pp.46-57
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    • 2013
  • Flutter stability and buffeting response have been the topics of most concern in the design state of long-span suspension bridges. Among approaches towards the aerodynamic stability, the aerodynamic-based control method which uses control surfaces to generate forces counteracting the unstable excitations has shown to be promising. This study focused on the mechanically controlled system using flaps; two flaps were attached on both sides of a bridge deck and were driven by the motions of the bridge deck. When the flaps moved, the overall cross section of the bridge deck containing these flaps was continuously changing. As a consequence, the aerodynamic forces also changed. The efficiency of the control was studied through the numerical simulation and experimental investigations. The values of quasi-steady forces, together with the experimental aerodynamic force coefficients, were proposed in the simulation. The results showed that the passive flap control can, with appropriate motion of the flaps, solve the aerodynamic instability. The efficiency of the flap control on the full span of a simple suspension bridge was also carried out. The mode-by-mode technique was applied for the investigation. The results revealed that the efficiency of the flap control relates to the mode number, the installed location of the flap, and the flap length.

A Study on Axial Collapse Characteristics of Spot Welded Double-Hat Shaped Section Members by FEM (FEM에 의한 점용접된 이중모자형 단면부재의 축방향 압궤특성에 관한 연구)

  • Cha, Cheon-Seok;Kim, Young-Nam;Yang, In-Young
    • Journal of the Korean Society for Precision Engineering
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    • v.18 no.7
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    • pp.120-126
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    • 2001
  • The widely used spot welded section members of vehicles are structures which absorb most of the energy in a front-end collision. In front-end collision, sufficiently absorbed in the front parts, the impact energy does not reach the passengers. Simultaneously, the frame gets less damaged. This structures have to be very stiff, but collapse progressively to absorb the kinetic energy as expected. In the view of stiffness, the double-hat shaped section member is stiffer than the hat shaped section member. In progress of collapse, the hat shaped section member is collapsing progressively, but the double-hat shaped section member does not due to stiffness. An analysis on the hat shaped section member was previously completed. This paper concerns the collapse characteristic of the double-hat shaped section member. In the program system presented in this study, an explicit finite element code, LS-DYNA3D is adopted for simulating complicate collapse behavior of double hat shaped section members with respect to spot weld pitches. And comparing with the results from the quasi-static and impact experiment, the simulation has been verified.

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A study on the fatigue bending strength of quasi-isotropic CFRP laminates subjected to impact damage (축격손상을 받은 의사등방성 탄소섬유강화 복합재의 굽힘피로강도)

  • Park, Soo-Chul;Park, Seol-Hyeon;Jung, Jong-An;Cha, Cheon-Seok;Yang, Yong-Jun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.18 no.10
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    • pp.688-695
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    • 2017
  • Compared to metal, CFRP has excellent mechanical characteristics in terms of intensity, hardness, and heat resistance as well as its light weight that it is used widely in various fields. Therefore, this material has been used recently in the aerospace field. On the other hand, the material has shortcomings in terms of its extreme vulnerability to damage occurring internally from an external impact. This study examined the intensity up to its destruction from repeated use with the internal impact of a CFRP laminated plate that had also been exposed to external impact obtain design data for the external plate of aircraft used in the aerospace field. For the experimental method, regarding the quasi-isotopic type CFRP specimen and orthotropic CFRP specimen that are produced with a different layer structure, steel spheres with a diameter of 5 mm were collided to observe the resulting impact damage. Through a 3-point flexural fatigue experiment, the progress of internal layer separation and impact damage was observed. Measurements of the flexural fatigue strength after the flexural fatigue experiment until internal damage occurs and the surface impacted by the steel spheres revealed the quasi-isotopic layer structure to have a higher intensity for both cases.

Effects of Aromatherapy Massage on Pain, Physical Function, Sleep Disturbance and Depression in Elderly Women with Osteoarthritis (향 요법 마사지가 골관절염 여성 노인의 통증, 신체기능, 수면장애 및 우울에 미치는 효과)

  • Choi, In-Ryoung
    • Women's Health Nursing
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    • v.12 no.2
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    • pp.168-176
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    • 2006
  • Purpose: This study was to investigate the effects of aromatherapy massage on pain, physical function, sleep disturbance and depression in elderly women with osteoarthritis. Method: The study design was a quasi-experiment design with a non-equivalent control group pre and post-test. The study pool included elderly female patients older than 65years old suffering from osteoarthritis. Results: Pain in the experimental group after the aromatherapy massage was significantly decreased than that in the control group. The physical disability in the experimental group after the aromatherapy massage was significantly decreased than that in the control group. The sleep disturbance in the experimental group after the aromatherapy massage was significantly decreased than that in the control group. The depression in the experimental group after the aromatherapy massage was significantly decreased than that in the control group. Conclusion: Aromatherapy may be adopted as an effective nursing intervention for osteoarthritis.

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Evaluating the Mechanical Properties of Fiber Yarns for Developing Synthetic Fiber Chains

  • Kim, Kyeongsoo;Kim, Taewan;Kim, Namhun;Kim, Dokyoun;Kang, Yongjun;Kim, Seonjin
    • Journal of Ocean Engineering and Technology
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    • v.35 no.6
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    • pp.426-433
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    • 2021
  • In this study, three types of synthetic fiber materials were evaluated, namely, DM20, SK78, and T147, to replace steel chains in shipbuilding and offshore fields with fiber chains as there is increasing demand for chains with lighter weights and improved usabilities. The strength and quasi-static stiffness were analyzed to select suitable yarns for the fiber chains. The durability of the yarn was evaluated by performing a 3-T (time to rupture) test as a specific tension level. The results of the experiment revealed excellent dynamic stiffness in DM20 and highest values of the windward and leeward stiffness in T147. 3-T linear design characteristic curves for a specific tension level were derived for the three types of fiber materials. The findings of this study can provide insights for improving strength and durability in fiber chain design.