• 한국초전도ㆍ저온공학회논문지
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• 제18권3호
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• pp.25-29
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• 2016

A quench detection system of KSTAR Poloidal Field (PF) coils is inevitable for stable operation because normal zone generates overheating during quench occurrence. Recently, new voltage quench detection method, combination of Central Difference Averaging (CDA) and Mutual Inductance Compensation (MIK) for compensating mutual inductive voltage more effectively than conventional voltage detection method, has been suggested and studied. For better performance of mutual induction cancellation by adjacent coils of CDA+MIK method for KSTAR coil system, balance coefficients of CDA must be estimated and adjusted preferentially. In this paper, the balance coefficients of CDA for KSTAR PF coils were numerically estimated. The estimated result was adopted and tested by using simulation. The CDA method adopting balance coefficients effectively eliminated mutual inductive voltage, and also it is expected to improve performance of CDA+MIK method for quench detection of KSTAR PF coils.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 추계학술대회논문집
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• pp.531-536
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• 2006

In four cylinder engine, the second order inertia force occurs due to the reciprocating parts of the cylinder. Because the magnitude of the inertia force is proportional to a square of the angular velocity of crank shaft, engine gets suffered from vibration excited by unbalanced inertia force in high speed. This vibration excited by the unbalanced inertia force can be canceled by applying a balance shaft. Balance shaft has one or more unbalance mass and rotates twice quickly than the crank shaft. In this paper, an unbalanced force caused by the rotating of unbalance mass of balance shafts was calculated. The directional equivalent stiffness and damping coefficients of the journal bearing of balance shafts was calculated. Equations of rotational vibration modes were derived using directional stiffness and damping coefficients. The dynamic stability of balance shafts was analyzed and evaluated for two type models using the equivalent stiffness and damping coefficients. An efficient procedure to he able to evaluate dynamic stability and design optimal balance shaft was proposed.

• 유공압시스템학회논문집
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• 제5권1호
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• pp.13-19
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• 2008

The typical hydraulic system of hoist is composed of a hydraulic supply unit, a directional control valve, counter balance valve, and flow control valves. The flow capacity coefficients of flow control valves should be adjusted so that the hoist is operated at moderate speed and the hydraulic energy loss is minimized. However, it is difficult to adjust the flow coefficients of flow control valves by trial and error for optimal operation. Here, the steady state model of the hoist hydraulic system including the differential cylinder circuit is derived and the optimal flow capacity coefficients of flow control valves are obtained using the complex method that is one kind of constrained direct search method.

• 소음진동
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• 제8권5호
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• pp.887-899
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• 1998

It has been resulted that Lagrange multiplier method with statistical approach was superior to traditional harmonic balance method in identifying the nonlinear loudspeaker parameters when output signals were contaminated with Gaussian random noise. We have known that the displacement-dependent characteristic values of nonlinear parameters identified by traditional harmonic balance method were estimated less than original values by the increase of output noise and the stiffness coefficients were very sensitive to output noise. Also, by the sensitivity analysis we have verified that the harmonic distortions in acoustic radiation was mainly due to nonlinearity of force factor caused by uneven magnetic fields and that reducing the nonlinearity of damping coefficients were very effective for improving second harmonic distrotion of acoustic radiation.

• 한국전문물리치료학회지
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• 제14권4호
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• pp.28-34
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• 2007

The purposes of this study were to provide the basic data and investigate the reliability of functional reach test and identify correlation of Berg balance scale (BBS) and functional reach test (FRT). The subjects were twenty healthy young adults and forty-five over 65 years old in order to compare balance ability. These data were analyzed by independent t-test and Pearson's correlation test using SPSS WIN 10.0. The results were as follows. Intrarater reliability coefficients of FRT was .976 and interrater was .942. FRT was significantly correlated with age, height, and BBS (p<.05). There were no significant differences in FRT and BBS by sex. There was significant difference in reach distance between below 74 elderly and above in FRT. FRT is very reliable test for balance and significantly correlated with BBS. Therefore, it is suggested that FRT is a clinically useful tool to substitute for BBS measuring balance ability in the elderly.

• 한국전문물리치료학회지
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• 제5권1호
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• pp.17-29
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• 1998

The purpose of this study was to identify the relationship between sitting and standing balance in acute stroke patients and gait outcome, and to determine appropriate test times. The subjects of this study were 20 hemiplegic patients who had been hospitalized in Sangji University Oriental Medical Hospital from August 26, 1997 through November 3, 1997. Twenty patients with cerebral infarcts had sitting and standing balance assessed on the 5th day and 10th day of stroke onset. Gait outcome was assessed 5 weeks later using the MMAS (Modified Motor Assessment Scale) score. The data were analyzed by the Spearman's Rho test and Wilcoxon signed rank test. The results were as follows: 1) Correlation coefficients between sitting balance on the 5th day and 10th day after their stroke and gait outcome 5 weeks after their stroke were $r_s$=0.89 and $r_s$=0.83, respectively. All of the sitting balance data significantly correlated with gait outcome (p<0.05). 2) Correlation coefficients between standing balance on the 5th day and 10th day after their stroke and gait outcome 5 weeks after their stroke were $r_s$=0.82 and $r_s$=0.87, respectively. All of the standing balance data significant1y correlated with gait outcome (p<0.05). 3) The difference between sitting balance scores on the 5th day and 10th day after stroke onset were statistically significant (p<0.05). But the difference between standing balance scores on the 5th day and 10th day after stroke onset were not statistically significant (p>0.05). In conclusion, sitting and standing balance tests on the 5th day and 10th day after their stroke appear to be predictive of gait outcome. Also, the result of this study can provide reference for appropriate test times as an assessment of sitting and standing balance in stroke patients.

• 정보통신설비학회논문지
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• 제9권2호
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• pp.35-41
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• 2010

The balance coefficients between telecommunication lines are specified in the technical standard and the power induction computation method varies in the order of 100 times in magnitude according to the amount of impedance. The results of actual balance measurements, differing from time to time with the measurement circuit or increasing proportionally as the induction voltage increases, appeared as a measurement error because of not using the standard measurement circuit. This article investigates such errors and proposes the use of a standard balance measurement circuit and a measurement device impedance under the domestic notification standard and the ITU-T international standard.

• 한국전문물리치료학회지
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• 제4권3호
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• pp.61-69
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• 1997

The ability to maintain an upright position during quiet standing is a useful motor skill. The Sensory Organization Test (SOT) is a timed balance test that evaluates somatosensory, visual, and vestibular function for maintenance of upright posture. The Fugl-Meyer Sensorimotor Assessment (FMSA) balance subscale is the functional status assessment that indicates amount of assistance needed during various balance tasks. Functional Independence Measure (FIM) is the functional status assessment tool and FIM can be used clinically as an outcome measure. The purpose of this study was to see if the SOT can be used as a evaluation tool to measure hemiplegic patients' balance ability. Thirty-six patients with hemiplegia participated in this study. SOT scores were significantly correlated with FMSA balance scores and FIM scores(p<0.05). However correlation coefficients were not so high (r=0.60, and r=0.51, respectively). Therefore, further study is needed to verify the SOT's usefulness when physical therapists are evaluating for hemiplegic patients' balance ability.

• 한국농공학회논문집
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• 제66권5호
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• pp.67-79
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• 2024

Water balance analysis in heightened reservoirs, which have been raised to ensure a stable supply of irrigation water and secure water against floods and heavy rainfall, is essential for evaluating water supply capacity and reservoir maintenance. The consecutively linked reservoir system, which involves preserving the existing embankment while constructing a new one, affects the water balance between the existing and new reservoirs. This study aims to analyze the linked water balance between reservoirs in a consecutively linked reservoir system using the DIROM (Daily Irrigation Reservoir Operation Model) model. Surveys were conducted to investigate actual water use, and multiple water supply quantities were estimated based on these findings. Methods to supplement missing data and improve the limitations of simulated inflow were proposed and applied, and the performance of the daily storage simulation was evaluated. By supplementing the missing water use data, the NSE (Nash-Sutcliffe Efficiency) of the Sonhang reservoir storage rate simulation improved by approximately 30%. Additionally, result of using inflow coefficients significantly enhanced the simulation performance for the Sonhang2 and Sonhang reservoirs. This study confirms the necessity of incorporating appropriate inflow coefficients in reservoir design to overcome the model's tendency to overestimate inflow, highlighting the critical importance of quality control in observational data. The findings are expected to be useful for the design and analysis of future reservoir systems through embankment heightening.

• 한국농공학회지
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• 제32권E호
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• pp.80-87
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• 1990

Energy balance equations Were developed to describe the heat transfer mechanisms in a double layer plastic greenhouse with a water curtain system. Heat transfer variables were determined by using various temperature data measured in a conventional prototype semicircular cross-section greenhouse over a range of water temperatures and water flow rates. The heat transfer coefficient between flowing water and greenhouse air was independent of water flow rates. But the heat transfer coefficient between water surface and the stagnant air space within the double plastic layer was dependent on water flow rates. Substituting the heat transfer coefficients, determined from the energy balance equations in the heat transfer equations, demonstrated various relationships among ambient air temperature, greenhouse air temperature, water temperature, and water flow rates. The heating benefits were linearly related to not only the inside and outside air temperatures but also to the water temperature. The energy conservation effects of the water curtain system were found even initial water temperatures were considerably lower than the greenhouse setting temperatures. Sensitivity analysis for heat transfer coefficients demonstrated that the heat transfer coefficient between greenhouse air and the stagnant air within the plastic layers was the most significant coefficient in the estimation of heating effects.