• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.4 s.109
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• pp.420-427
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• 2006

In this study, wind loads transmitted to a transmission tower from transmission lines are mitigated using rotational viscoelastic dampers. First, the wind load characteristics in a transmission tower is investigated considering the effect of the transmission lines through stochastic analysis. The assemblage of the transmission line and insulator are modeled as a double pendulum system connected to the SDOF model of the tower. From the result of the stochastic analysis, the background component of the overturing moment caused by the wind loads acting on the transmission lines are found to have considerable portion in the total overturning moment. Based on this observation result, a strategy Installing rotational viscoelastic damper (VED) between tower arm and transmission line is proposed for the mitigation of the transmission line reactions, which play a role as dynamic loads on a transmission tower. For the purpose of verification, time history analysis is conducted for different wind velocities and VED parameters. The analysis result shows that the rotational VED is effective for the mitigation of the background component rather than the resonance component of the transmission line reactions and achieves the reduction ratio of 50% even for higher wind speed.

• Journal of Powder Materials
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• v.22 no.6
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• pp.438-442
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• 2015

Porous thick film of alumina which is fabricated by freeze tape casting using a camphene-camphor-acrylate vehicle. Alumina slurry is mixed above the melting point of the camphene-camphor solvent. Upon cooling, the camphene-camphor crystallizes from the solution as particle-free dendrites, with the $Al_2O_3$ powder and acrylate liquid in the interdendritic spaces. Subsequently, the acrylate liquid is solidified by photopolymerization to offer mechanical properties for handling. The microstructure of the porous alumina film is characterized for systems with different cooling rate around the melting temperature of camphor-camphene. The structure of the dendritic porosity is compared as a function of ratio of camphene-camphor solvent and acrylate content, and $Al_2O_3$ powder volume fraction in acrylate in terms of the dendrite arm width.

• Journal of Korean Medicine Rehabilitation
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• v.19 no.2
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• pp.275-287
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• 2009

Objectives : In order to observe clinical effects, carboxytherapy and electroacupuncture, we analyzed relation effect and patients' character, and researched correlation among reduction of BFM(Body Fat Mass), WHR(Waist-Hip Ratio) and AC(Arm Circumference). Methods : Among outpatients who had admitted to department of oriental rehabilitation medicine, Dae-Jeon oriental medicine hospital, Dae-Jeon university from January to September, 2008 for obesity treatment and abdominal fat, 44 subjects were chosen and carboxytherapy and electroacupuncture were practiced concurrently. Results : 1. The group under the concurrent practice of carboxytherapy and electroacupuncture showed significant decrease in BFM, BFR(Body Fat Rate), WHR and AC. 2. The group under the concurrent practice of carboxytherapy and electroacupuncture did not show statistical significance but showed decrease in BFM, WHR. The degree of decrease was proportional to that of obesity. 3. As AC decreased, BFM, WHR reduction tended to increase as well in the group under the concurrent practice of carboxytherapy and electroacupuncture. 4. Compared to the group under the sole practice of electroacupuncture, the group under the concurrent practice of carboxytherapy and electroacupuncture showed less change in BFM reduction and greater change in WHR reduction. Conclusions : From the above results, the concurrent practice of carboxytherapy and electroacupuncture had an effect on obesity and reducing abdominal fat, but did not show statistically significant decrease compare to the sole practice of electroacupuncture.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.3
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• pp.534-546
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• 1990

In this work, an optimum shape synthesis for rolling contact components was done to minimize contact forces considering dynamic characteristics of the system. Even this method was applied to an OHC type cam follower system, it can be expanded to general rolling contact shape design problems which are strictly forced to follow predetermined motion. First, the follower optimum angular motion was derived to minimize the valve peak acceleration while satisfying all the constraints of valve motion. Then the cam and follower contact shape were synthesized to give the proposed follower motion. Theoretically, two components shape to generate a predetermined motion can not be uniquely determined. So the cam shape was syntehsized with parametric synthesis method to minimize the peak contact force between cam and follower when the follower shape is assumed as a circle or an ellipse.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.1
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• pp.40.1-40.1
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• 2014

We have classified barred galaxies for 418 RC3 sample galaxies within z < 0.01 from SDSS DR7 using the visual inspection, ellipse fitting method and Fourier analysis. We found the bar fraction to be ~60%, 43% and 70% for each method and that the ellipse fitting method tends to miss the bar when a large bulge hides the transition from bar to disk in early spirals. We also confirmed that the Fourier analysis cannot distinguish between a bar and spiral arm structure. These systematic difficulties may have produced the long-time controversy about bar fraction dependence on Hubble sequence, mass and color. We designed a new method to fine bars by analyzing the ratio map of bar strength in polar coordinates, which yields the bar fraction of ~27% and ~32% for SAB and SB, respectively. The consistency with visual inspection reaches around 70%, and roughly 90% of visual strong bar are classified as SAB and SB in our classification. Although our method also has a weakness that a large bulge lowers the value of bar strength, the missing bar fraction in early spirals is reduced to the level of ~1/4 compared to the ellipse fitting method. Our method can make up for the demerits of the previous automatic classifications and provide a quantitative bar classification that agrees with visual classification.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.840-842
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• 2003

저 주파수에서 인덕턴스 단위(H, Henry)는 전기용량의 단위(F, Farad)로부터 Maxwell bridge 또는 LC를 이용한 resonance 방법으로써 유도가 된다. 이중 Maxwell bridge 방법은 국가의 단위표준을 유지하는 연구소 또는 기관에서 가장 많이 사용되는 "product arm" 형의 bridge로 잘 알려져 있다. 개발된 bridge는 ratio-transformer를 전압공급 쪽(source)과 신호검출 쪽(detector)에 사용하여 종래의 Maxwell bridge 평형조절 시 main balance와 Wagner balance의 2개 과정을 진행하던 것과는 달리 main balance, source balance, detector balance의 과정을 진행함으로서 기존 bridge의 불안정한 ground admittance들의 영향에 의해 나타나는 불확도를 완전히 제거하였다. 한편 개발된 bridge는 10 mH, 100 mH를 10 nF의 전기용량표준기와 $1\;k{\Omega}$, $10\;k{\Omega}$의 저항표준기로부터 유도 되도록 제작되었으며. 10 mH의 경우 $400\;Hz{\sim}5\;kHz$의 주파수 영역에서 약 $2.2{\times}10^{-6}$(k=1)의 불확도로 인덕턴스 단위를 유도할 수가 있게 되었다.

• Coupled systems mechanics
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• v.6 no.1
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• pp.97-111
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• 2017

The present paper reports an analytical study of delamination fracture in the Mixed Mode Flexure (MMF) functionally graded beam with considering the material non-linearity. The mechanical behavior of MMF beam is modeled by using a non-linear stress-strain relation. It is assumed that the material is functionally graded along the beam height. Fracture behavior is analyzed by the J-integral approach. Non-linear analytical solution is derived of the J-integral for a delamination located arbitrary along the beam height. The J-integral solution derived is verified by analyzing the strain energy release rate with considering the non-linear material behavior. The effects of material gradient, crack location along the beam height and material non-linearity on the fracture are evaluated. It is found that the J-integral value decreases with increasing the upper crack arm thickness. Concerning the influence of material gradient on the non-linear fracture, the analysis reveals that the J-integral value decreases with increasing the ratio of modulus of elasticity in the lower and upper edge of the beam. It is found also that non-linear material behavior leads to increase of the J-integral value. The present study contributes for the understanding of fracture in functionally graded beams that exhibit material non-linearity.

• Journal of the Korean Society of Clothing and Textiles
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• v.43 no.3
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• pp.416-426
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• 2019

This study measured and analyzed male firefighters hand sizes as well as suggested data for developing firefighting gloves with a good fit. Accordingly, body dimensions related to the hand were measured for 100 male firefighters. Twenty-three measuring items related to the hand and lower arm were selected. The firefighters' measurement data were compared to general adult male measurements from the 6th Korean Anthropometric data to analyze the hand sizes characteristics of firefighters. As a result, height, hand circumference, hand breadth, wrist circumference, elbow-wrist length, forearm-fingertip length and firefighter weight were significantly larger than adult males. A correlation analysis for 23 items was conducted to select items used as standards for setting a size when manufacturing firefighting gloves. Hand length and circumference were selected as representative hand parts for making firefighting gloves. Cross analysis between hand length and circumference were conducted to find the section showing the highest distribution ratio. As a result, the highest sections were between 19cm and 21cm for hand circumference and between 18.5cm and 19.5cm for hand length, which may be suggested as the most important ranges.

• Journal of Dental Anesthesia and Pain Medicine
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• v.21 no.6
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• pp.547-556
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• 2021

Background: This study aimed to determine the efficacy of Physics Forceps in pediatric dental extractions. Methods: This was a double-blind, randomized controlled trial with a parallel-arm design and identical allocation ratio (1:1). Children (n=104) were randomly divided into two groups for extraction of mandibular primary teeth (group I: Physics Forceps; group II: conventional forceps). The outcome variables assessed in the study were the time taken for extraction, pre- and postoperative anxiety (using RMS pictorial scale), incidence of fractured teeth, and postoperative pain on the first and third days (using the Wong-Baker faces pain scale). Results: A significant reduction (P < 0.001) in intraoperative time, anxiety, and incidence of tooth fracture was confined to group I. The pain significantly reduced from the first to the third postoperative day in both groups, but the mean reduction in RMS scores in the physics forceps group was far better than that in the conventional forceps group. Conclusion: Physics Forceps aid in extraction of primary teeth with minimal trauma to supporting structures, as well as reducing anxiety in the pediatric population.

• Physical Therapy Rehabilitation Science
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• v.11 no.2
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• pp.165-171
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• 2022

Objective: Nonspecific low back pain (NSLBP) is experienced worldwide by many age groups. Yoga is recommended as an exercise to reduce back pain and stress because it is a breathing exercise, posture, and meditation as key elements. The aim of this study is to compare the effects of yoga and stabilization exercise on pain intensity, function, and depression. Design: An open-label, parallel arm, randomized controlled trial Methods: Twenty-four participants were allocated to the experimental and the control group in a ratio of 1:1. Yoga (experimental group) and stabilization exercise (control group) were received twice a week for 6 weeks Participants were assessed at baseline and post-intervention for pain intensity (numeric pain rating scale), function (Aberdeen low back pain scale, flexibility,and strength), and depression (Beck depression inventory). Results: When the experimental group (Yoga) and control group (stabilization exercise) were performed twice a week for 6 weeks, numeric pain rating scale, Aberdeen low back pain scale, and flexibility in post-intervention showed significant improvement in both groups (P<0.05), However, in all variables, the experimental group showed a positive benefit compared to the control group (P<0.05). Conclusions: The results of this study show that yoga has more positive benefits compared to stabilization exercise in pain intensity, function, and depression in individuals with NSLBP.