• 한국토양비료학회지
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• 제32권4호
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• pp.344-356
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• 1999

토양수분 확산계수 추정을 위한 이론식(Mualem's principle)과 실측법(Hopmans' equation)을 제시하여 실험한 결과 실측치와 이론치의 상당한 근접을 보였으므로 Hopmans의 수치해석적 모형을 실측모형으로 재시하고자 한다. 작물계수 측정에 있어서는 생육시기에 따른 모형화보다는 생육온도에 따른 모형화가 함수 관계에 있어서 보다 더 유의성 있는 상관성을 보였다.

• Journal of Power Electronics
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• 제9권1호
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• pp.74-84
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• 2009

The design and implementation of a high performance PID (Proportional Integral & Differential) style controller with zero-phase error tracking property is considered in this article. Unlike a ball screw driven system, the controller in a direct drive system should provide a high level of tracking performance while avoiding the problems due to the absence of the gear system. The stiff mechanical element in a direct drive system allows high precise positioning capability, but relatively high tracking ability with minimal position error is required. In this work, a feasible position controller named 'Unified PID controller' is presented. It will be shown that the function of the closed position loop can be designed into unity gain system in continuous time domain to provide minimal position error. The focus of this work is in two areas. First, easy gain tunable PID position controller without speed control loop is designed in order to construct feasible high performance drive system. Second, a simple but powerful zero phase error tracking strategy using the pre-designed function of the main control loop is presented for minimal tracking error in all operating conditions. Experimental results with a s-curve based position pattern commonly used in industrial field demonstrate the feasibility and effective performance of the approach.

• Journal of Trauma and Injury
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• 제26권3호
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• pp.104-110
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• 2013

Purpose: Bedside ultrasonography is available in most emergency departments, and detecting the intracranial pressure is elevated is critical. Our objective is to evaluate the availability of bedside optic nerve ultrasound (ONUS) as a secondary survey for patients with head injuries in the emergency department (ED). Methods: From September, 2012, to March, 2013, we performed a prospective study of patients presenting to the ED after an accident. Patients with head injuries but without obvious ocular trauma or ocular disease were included. The ONUS was performed using a 3 to 12 MHz linear probe on closed eyelids after a primary survey. We analyzed the correlation between the brain computed tomography (CT) findings that suggested elevated intracranial pressure (ICP) and the Optic nerve sheath diameter (ONSD) measured by using ONUS. Results: A total of 81 patients were enrolled. Forty-seven had CT results consistent with elevated ICP, and their mean ONSD was $5.98{\pm}0.59$ mm; the mean ONSD of patients who showed no signs of elevated ICP on CT was $4.63{\pm}0.21$ mm. The sensitivity and the specificity for the ONSD, compared with elevated ICP, were 98.87% and 100%, respectively, when the cut-off value was set to 4.96 mm. The area under curve (AUC) was 0.997 in the receiver operating characteristic curve (ROC curve). Conclusion: An evaluation using ONUS is a simple noninvasive procedure and is a potentially useful tool as a secondary survey to identify an elevated ICP.