• 제목/요약/키워드: External surface condition

검색결과 176건 처리시간 0.026초

Tracking Performance Test of Polymer Insulator with Salt Solution which is added Surface Active Agent (계면활성제가 첨가된 염수용액에 따른 폴리머 애자의 트래킹 성능 평가)

  • Cho, Han-Goo;Han, Dong-Hee;Lee, Un-Yong;Lim, Kee-Joe;Choi, In-Hyuk
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
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    • pp.1121-1124
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    • 2004
  • Aging test to estimate life property of polymer insulator is executed through several international standard such as IEC 61109 and CEA tracking wheel test, but is not getting clear conclusion yet. There are two methods in the diagnosis method of polymer insulator such as off-line and on-line. The diagnosis methods in off-line are external condition analysis by the eye, contaminant analysis on surface, surface analysis, pollution withstand voltage test, power frequency flashover voltage test, lightning impulse flashover test, tensile fracture load test and flexural load test. The diagnosis methods in off-line most are the method for virgin and last aged sample. However, the diagnosis method in on-line is method that can be evaluate sample state as progressing continuously aging test in beginning, The diagnosis method in on-line is arranged as following: leakage current measurement, electric field, surface state investigation, thermal image, emitting light measurement and then so. In this paper, the tracking performance of polymer insulator with salt solution which is added surface active agent. The diagnosis of insulator sample has been analyzed by leakage current and visual examination.

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Effects of Different External Loads on the Activities of the Gluteus Maximus and Biceps Femoris during Prone Hip Extension in Healthy Young Men

  • Bae, Chang-Hwan;Choe, Yu-Won;Kim, Myoung-Kwon
    • Journal of the Korean Society of Physical Medicine
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    • 제15권2호
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    • pp.1-9
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    • 2020
  • PURPOSE: This study examined the effects of different external loads on the muscle activities around the hip during prone hip extension with knee flexion (PHEKF) exercise in healthy young men. METHODS: Sixteen healthy adult males participated in the study. A pressure biofeedback unit was used to provide feedback to the participants during the abdominal drawing-in maneuver (ADIM) with PHEKF. Sandbags (0 kg, 1 kg, 2 kg, and 3 kg) were used to provide external resistance. The quadriceps was contracted to maintain knee flexion 90° against resistance. Each resistance condition using a sandbag weight was given in random order. Surface electromyography (sEMG) was used to measure the electrical activity of the gluteus maximus, biceps femoris, and erector spinae during PHEKF. RESULTS: The muscle activity of the gluteus maximus was highest with the 3 kg resistance and lowest with 0 kg (F = 128.46, P = .00). The muscle activities of the biceps femoris and erector spinae were highest with 0 kg and lowest with 3 kg (F = 29.49, P = .00). The muscle activity rate of the gluteus maximus/biceps femoris was highest with 3 kg and lowest with 0 kg (F = 37.49, P = .00). CONCLUSION: The activity of the gluteus maximus was increased using a higher external weight load during PHEKF, while the activity of the biceps femoris decreased. These findings suggest that an external weight is needed during hip extensor exercise to strengthen the gluteus maximus and inhibit the biceps femoris.

The State Estimation by Unknown Disturbance Observer of Underwater Vehicle System for Robust Control (강인한 제어를 위한 수중이동시스템의 상태추정에 대한 연구)

  • Lee, Jin-Woo;Kim, Hwan-Seong;An, Young-Joo
    • Journal of the Korean Society of Safety
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    • 제18권4호
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    • pp.169-175
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    • 2003
  • In this paper, and estimation method for estimating the states of underwater vehicle systems with external unknown disturbance is proposed. First, the dynamics of underwater vehicle are induced by Taylor series expansion in the vertical plane and horizontal plane, respectively. For constructing the system model, the external efforts, i.e., the sea surface disturbances, the current, wave and etc., are regarded as external unknown disturbances. Thus the disturbance is added as external input into state-space form of underwater vehicle system. To estimate the state of systems with unknown disturbance, a disturbance observer which does not effected the external unknown input is proposed, and the existence condition for the observer is given. Finally, the effectiveness of the proposed disturbance observer for robust control of underwater vehicle systems is verified by using numerical simulation.

Affect influenceable the Electrical and Optical Characteristics depending on the Deposition Condition of BCP (BCP의 증착조건에 따른 전기적 및 광학적 특성에 미치는 영향)

  • Kim, Weon-Jong;Choi, Hyun-Min;Kim, Joung-Sik;Jeong, In-Bum;Lee, Sang-Kyo;Hong, Jin-Woong
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 한국전기전자재료학회 2009년도 하계학술대회 논문집
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    • pp.34-35
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    • 2009
  • We have studied the electrical and optical of organic light-emitting diodes depending on hole size of crucible boat using BCP materials. The thickness of TPD, $Alq_3$ and BCP was manufactured 40 nm, 60 nm and 5 nm under a base pressure of $5\times10^{-6}$ Torr using at thermal evaporation, respectively. In order to investigate the optimal surface roughness of BCP, the BCP was thermally evaporated to be 0.8 nun, 1.0 mm, 1.2 mm and 1.5 mm as a hole size of crucible boat, respectively. As the experimental results, we found that the luminous efficiency and the external quantum efficiency of the device is superior to others when hole size of crucible boat using BCP is 1.2 mm. Also, compared to the ones from the devices having the hole size of crucible boat is 1.0 mm and 1.5mm layer, the external quantum efficiency were improved by 2.5 and 2.4 times.

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Effect of Vibrational Amplitude on Friction and Wear Properties of Magnetorheological Elastomer (진폭에 따른 자기유변탄성체의 마찰 특성 연구)

  • Lian, Chenglong;Lee, Kwang-Hee;Lee, Chul-Hee
    • Tribology and Lubricants
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    • 제32권2호
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    • pp.39-43
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    • 2016
  • Magnetorheological elastomers (MREs) are a type of “smart” material, and their properties can be controlled rapidly and reversibly under the influence of an external stimulus. The application of an external magnetic field can change the shear modulus, hardness, and friction coefficient of MREs. The friction can cause vibration; moreover, the vibration can affect friction. The change of friction depends on the relative motion, normal force, roughness of the rubbing surfaces, material type, temperature, lubrication, relative humidity, and vibration condition. As MREs are a type of “smart material,” their friction coefficient can be reduced by applying an external magnetic field—the applications of this feature in engineering have been widely studied. However, the friction properties of MREs under vibration have not been tested to date. In this study, MRE samples and a reciprocating friction tester were fabricated. The friction coefficient was measured to evaluate the friction properties under various vibration conditions; subsequently, the wear depth and wear surface profile of the MRE were observed in order to evaluate the wear properties. The results show that the friction coefficient of the MREs decreased when a magnetic field was applied. Moreover, the friction coefficient decreased when the vibrational amplitudes increased. The wear depth of the MRE also decreased as the vibrational amplitudes increased.

The Effects of Performing a One-legged Bridge with Hip Abduction and Unstable Surface on Trunk and Gluteal Muscle Activation in Healthy Adults

  • Bak, Jong-Woo;Cho, Min-Kwon;Chung, Yi-Jung
    • The Journal of Korean Physical Therapy
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    • 제28권3호
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    • pp.205-211
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    • 2016
  • Purpose: This study investigated the influence of muscle activity of the trunk and lower limb during a bridge exercise using a unstable surface and during one-legged bridge hip abduction in healthy adults. Methods: Nineteen healthy participated in this study (12 males and 7 females, aged $29.0{\pm}5.0$). The participants were instructed to perform the bridge exercises under six different conditions. Trunk and lower limb muscle activation, such as the erector spinae (ES), gluteus maximus (GM), external oblique (EO), and internal oblique (IO), was measured using surface electromyography. The six different bridge exercise conditions were conducted randomly. Data analysis was performed by using the mean scores after three trials of each condition. Results: On the ipsilateral side, muscle activity of the IO, EO, and ES during the hip abduction condition (Single-legged hip abduction bridge, Bridge with use of a ball and single-leg hip abduction, Bridge with use of a sling and single-leg hip abduction) was significantly higher than those during Unstable surface (Bridge with use of a ball, Bridge with use of a sling) and General bridging exercise (p<0.05). In the contralateral side, activities of the GM and EO during Single-legged hip abduction bridge, Bridge with use of a ball and single-leg hip abduction and Bridge with use of a sling and single-leg hip abduction was significantly higher than that during Bridge with use of a ball, Bridge with use of a sling and General bridging exercise (p<0.05). Conclusion: This study demonstrated that performing a bridge exercise with use of a sling and single-leg hip abduction had an effect on trunk and gluteal muscle activation. The findings of this study suggest that this training method can be clinically effective for unilateral training and for patients with hemiplegia.

Orientation and thickness dependence of magnetic levitation force and trapped magnetic field of single grain YBa2Cu3O7-y bulk superconductors

  • Jung, Y.;Go, S.J.;Joo, H.T.;Lee, Y.J.;Park, S.D.;Jun, B.H.;Kim, C.J.
    • Progress in Superconductivity and Cryogenics
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    • 제19권1호
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    • pp.30-35
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    • 2017
  • The effects of the crystallographic orientation and sample thickness on the magnetic levitation forces (F) and trapped magnetic field (B) of single grain YBCO bulk superconductors were examined. Single grain YBCO samples with a (001), (110) or (100) surface were used as the test samples. The samples used for the force-distance (F-d) measurement were cooled at 77 K without a magnetic field (zero field cooling, ZFC), whereas the samples used for the B measurement were cooled under the external magnetic field of a Nd-B-Fe permanent magnet (field cooling, FC). It was found that F and B of the (001) surface were higher than those of the (110) or (100) surface, which is attributed to the higher critical current density ($J_c$) of the (001) surface. For the (001) samples with t=5-18 mm, the maximum magnetic levitation forces ($F_{max}s$) of the ZFC samples were larger than 40 N. About 80% of the applied magnetic field was trapped in the FC samples. However, the F and B decreased rapidly as t decreased below 5 mm. There exists a critical sample thickness (t=5 mm for the experimental condition of this study) for maintaining the large levitation/trapping properties, which is dependent on the material properties and magnitude of the external magnetic fields.

A Study on the Optimization for a V-groove GMA Welding Process Using a Dual Response Method (듀얼 반응표면법을 이용한 V-그루브 GMA 용접공정 최적화에 관한 연구)

  • Park, Hyoung-Jin;Ahn, Seung-Ho;Kang, Mun-Jin;Rhee, Se-Hun
    • Journal of Welding and Joining
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    • 제26권2호
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    • pp.85-91
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    • 2008
  • In general, the quality of a welding process tends to vary with depending on the work environment or external disturbances. Hence, in order to achieve the desirable quality of welding, we should have the optimal welding condition that is not significantly affected by these changes in the environment or external disturbances. In this study, we used a dual response surface method in consideration of both the mean output variables and the standard deviation in order to optimize the V-groove arc welding process. The input variables for GMA welding process with the dual response surface are welding voltage, welding current and welding speed. The output variables are the welding quality function using the shape factor of bead geometry. First, we performed welding experiment on the interested area according to the central composite design. From the results obtained, we derived the regression model on the mean and standard deviation between the input and output variables of the welding process and then obtained the dual response surface. Finally, using the grid search method, we obtained the input variables that minimize the object function which led to the optimal V-groove arc welding process.

A Study on Reducing of Entrance Surface Dose with the Eye in the Computed Radiography by Using High Kilo Voltage Peak Technique (컴퓨터 방사선영상에서 고 관전압 기법을 이용한 안구 입사표면선량 감소에 관한 연구)

  • Seoung, Youl-Hun;Rhim, Jea-Dong
    • Journal of the Korea Safety Management & Science
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    • 제13권2호
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    • pp.91-96
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    • 2011
  • The purpose of this study was to minimize of entrance surface dose (ESD) at the eye using high kVp technique in the computed radiography. We used REX-650R (Listem, Korea) general X-ray unit, and external detector with ESD dosimeter of Piranha 657 (RTI Electronics, Sweden). We used head of the whole body phantom. The total 64 images of X-ray anterior-posterior of skull were acquired using the film/screen (F/S) method and the digital of computed radiography method. The three radiology professor of more 10 years of clinical career evaluated a X-rays images in the same space by 5-point scale. The external detector was performed measurement of ESD of three times by same condition on the eye of the head phantom. The good image quality in the F/S method (90 kVp, 2.5 mAs) showed at the minimized ESD of 0.310 ${\pm}$ 0.001 mGy. the good image quality in the computed radiography method (90 kVp, 2.0 mAs) showed at the minimized ESD of 0.180 ${\pm}$ 0.002 mGy (P = 0.002). Finally the radiation dose could reduced about 50% in the computed radiography method more than the F/S method. In addition the eye entrance surface dose using high kVp technique with the computed radiography was reduced 92% more than conventional technique (F/S method).

Experimental Study for the Factors Influenced on the Permeability of Concrete (콘크리트의 누설성에 미치는 영향 요인에 관한 실험적 연구)

  • 김진근;이성태;양은익;김민욱;이성규;최강룡
    • Proceedings of the Korea Concrete Institute Conference
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    • 한국콘크리트학회 1998년도 봄 학술발표회논문집(II)
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    • pp.725-730
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    • 1998
  • In the nuclear power plant, steel or polymer liner plates are adopted to prohibit inner concrete surface contacting with gas or liquid materials. If there is an accident, the plate will be damaged, and concrete shall have final responsibility to safety requirements. In this paper, an experimental research was carried out to investigate the effects of construction joint and wet and loading condition on the permeability of concrete. The test results showed that leakage rate is decreased much more at the following cases than the others : (a)wet condition, (b)without a construction joint case, and (c)case subjected to external loads. It was noted that more reinforcement is required at the latter case.

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