• 전력전자학회:학술대회논문집
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• 전력전자학회 2015년도 추계학술대회 논문집
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• pp.209-210
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• 2015

This paper presents a new model predictive control method without the effect of a weighting factor in order to reduce common-mode voltage (CMV) for a three-phase voltage source inverter (VSI). By utilizing two active states with same dwell time during a sampling period instead of one state used in conventional method, the proposed method can reduce the CMV of VSI without the weighting factor. Simulation is carried out to verify the effectiveness of the proposed predictive control method with the aid of PSIM software.

• 한국산학기술학회논문지
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• 제14권10호
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• pp.5134-5139
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• 2013

복잡한 현대의 제어시스템 설계에 PLC를 사용하면 프로그램은 LD언어나 SFC언어를 사용한다. 대부분은 LD 언어를 사용하지만 최근에는 SFC 언어의 사용빈도수가 높아졌다. SFC 언어는 제어의 흐름을 이해하기가 쉽지만, 조합논리를 표현하는데는 단점을 가지고 있다. SFC언어에서 인터럽트를 처리할 때 인터럽트 요인이 발생하게 되면 메인프로그램을 중지하고 인터럽트 프로그램을 실행하여 프로그램이 종료된 후 메인프로그램으로 복귀하게 된다. 그러면 인터럽트 프로그램이 복잡할수록 메인프로그램 정지시간은 그만큼 길어지게 된다. 본 논문에서는 SFC언어에서 메인프로그램의 휴지시간이 없는 인터럽트 처리방법을 제안하고, 시뮬레이션을 통해 그의 타당성을 확인하였다.

• 대한조선학회 특별논문집
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• 대한조선학회 2005년도 특별논문집
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• pp.171-176
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• 2005

This paper presents a novel Intelligent-Welding-Carriage (IWC) for automation of curved block in shipbuilding. The curved block is usually used in both front and back side of the ship. In curved block root gap is big, 1-7 (mm) and inclination, 0-30 (deg). Since available conventional carriage type is limited to use below root gap of 3 (mm), only manual welding is employed in curved block. To adopt an IWC in curved block, it requires control of the welding conditions, i.e., voltage. current, weaving speed, dwell time and travel speed, with respect to root gap and inclination to achieve good welding qualify. In this paper, an IWC is developed for automization of welding operation to accommodate gap and inclination. Kinematics model and dynamics using Lagrangian formulation of the manipulator is introduced. IWC utilizes a database to perform accurate welding. The database is programmed based on numerous experimental test results with respect to gap, inclination, material, travel speed, weaving condition, voltage, and current. Finally, experimental result using PID control is addressed for verifying the trajectory tracking accuracy of end-effector.

• 한국전문물리치료학회지
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• 제16권4호
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• pp.44-52
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• 2009

It is known that individual factors as cognitive, perception, emotion, and motivation may greatly influence on recovery from neurologic region. This study was to investigate the effects of environmental reinforcement through motivation to perform the tasks voluntarily on motor and cognition function in rats with focal ischemic brain injury. Focal ischemic brain injury was induced in Sprague-Dawley rats (15 rats, $250{\pm}50$ g) through middle cerebral artery occlusion (MCAo). And then, experiment groups were randomly divided into three groups; The control group: MCAo induction ($n_1$=5), the environmental reinforcement (ER) group: the application for ER after MCAo induction ($n_2$=5), the environmental reinforcement through motivation (ERM) group: the application for ERM after MCAo induction ($n_3$=5). The climbing test (CT) and the modified limb placing tests (MLPTs) to measure the motor function and the Morris water maze acquisition test (MWMAT) and the Morris water maze retention test (MWMRT) to measure the cognitive function were performed. For the CT, the ERM group was significantly larger than the ER group. For the MLPTs, the ERM group was significantly decreased compared to other groups. For the MWMAT, the time to find the circular platform in the ERM group significantly decreased compared to other groups. For the MWMRT, the time to dwell on the quadrant circular platform in the ERM group was significantly increased compared to other groups. These results suggested that the ERM could improve the motor and cognitive functions in the rats with focal ischemic brain injury.

• 대한기계학회논문집A
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• 제32권3호
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• pp.209-216
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• 2008

The application of focused ion beam (FIB) depends on the optimal interaction of the operation parameters between operating parameters which control beam and samples on the stage during the FIB deposition process. This deposition process was investigated systematically in C precursor gas. Under the fine beam conditions (30kV, 40nm beam size, etc), the effect of considered process parameters - dwell time, beam overlap, incident beam angle to tilted surface, minimum frame time and pattern size were investigated from deposition results by the design of experiment. For the process analysis, influence of the parameters on FIB-CVD process was examined with respect to dimensions and constructed shapes of single and multi- patterns. Throughout the single patterning process, optimal conditions were selected. Multi-patterning deposition were presented to show the effect of on-stage parameters. The analysis have provided the sequent beam scan method and the aspect-ratio had the most significant influence for the multi-patterning deposition in the FIB processing. The bitmapped scan method was more efficient than the one-by-one scan type method for obtaining high aspect-ratio (Width/Height > 1) patterns.

• 한국의학물리학회지:의학물리
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• 제8권1호
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• pp.25-29
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• 1997

고선량률 근접치료시 사용되는 Ir-192 선원의 방사능을 이온형 전리함을 이용하여 평가하였다. 측정지점으로부터 각각 10 cm 떨어진 거리에 선원을 일정시간동안 위치시킨 후 측정된 전하량을 방사능값으로 환산하였으며 측정된 결과는 제작회사로부터 제공된 값과 비교하였다. 선원의 방사능은 시간이 경과함에 따라 감소하므로 일정기간동안 규칙적으로 방사능를 측정하였으며 측정값은 Ir-192 에 대해서 알려진 반감기를 고려한 계산 값과 비교 분석하였다. 선원의 방사능 측정의 정확도는 측정장치 setup의 정확도에 크게 영향을 받기 때문에 원격조정으로 제어되는 선원위치의 정확도를 평가하였다. 필름에 감광된 감마선의 영상을 Film scanner를 이용하여 분석하였으며 프로그램된 지점에 제대로 위치하는지의 정도를 평가하였다. 예상된 선원위치와 실제 선원위치간의 차이는 최대 1 mm 이내이었으며 이러한 조건하에서 제작회사로부터 제공된 방사능값과 본 연구를 통하여 측정된 값과의 차이는 0.7$\pm$1.5 % 이며 시간에 따른 선원의 변화량을 확인해 본 결과 0.l$\pm$1.2%이었다. 결론적으로, 본 연구에서 사용된 측정방법에 의한 실측값과 제작회사로부터 제공된 방사능값은 현재까지 서로 잘 일치하였고 치료기의 정확성도 확인되었다, 그러나 고선량률 근접치료시 사용되는 선원의 정확한 위치 및 방사능값은 환자치료의 성패를 결정짓는 매우 중요한 인자이므로 지속적인 정도관리가 요구된다.

• Tribology and Lubricants
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• 제35권6호
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• pp.330-336
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• 2019

Conditioning is a process involving pad surface scraping by a moving metallic disk that is electrodeposited with diamond abrasives. It is an indispensable process in chemical-mechanical planarization, which regulates the pad roughness by removing the surface residues. Additionally, conditioning maintains the material removal rates and increases the pad lifetime. As the conditioning continues, the pad profile becomes unevenly to be deformed, which causes poor polishing quality. Simulation calculates the density at which the diamond abrasives on the conditioner scratch the unit area on the pad. It can predict the profile deformation through the control of conditioner dwell time. Previously, this effect of the diamond shape on conditioning has been investigated with regard to microscopic areas, such as surface roughness, rather than global pad-profile deformation. In this study, the effect of diamond shape on the pad profile is evaluated by comparing the simulated and experimental conditioning using two conditioners: a) random-shaped abrasive conditioner (RSC) and b) uniform-shaped abrasive conditioner (USC). Consequently, it is confirmed that the USC is incapable of controlling the pad profile, which is consistent with the simulation results.

• 대한기계학회논문집B
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• 제24권12호
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• pp.1652-1661
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• 2000

A visualization study using the schlieren method is adopted in an optically-accessible, cylindrical constant volume combustion chamber to identify the mechanism of ignition energy and ignition system interaction in spark ignited, lean gasoline-air mixture. In order to research the effects of ignition system on flame propagation, two kinds of ignition system are designed, and several kinds of spark plugs are tested and evaluated. To control the discharge energy, the dwell time is varied. The initial flame development is quantified in terms of 2-D images which provides information about the projected flame area and development velocity as a function of ignition system and discharge energy. The results show that high ignition energy and extended spark plug gap can shorten the combustion duration in lean mixtures. The material, diameter and configuration of electrodes the flame development by changing the transfer efficiency from electrical energy to chemical energy and discharge energy. However these factors do not affect of flame development as much a ignition energy or extended gap does.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 전력전자학술대회 논문집
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• pp.247-251
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• 2001

Universal motors are mainly used for vacuum cleaner application. There are a lot of researches on SRM that applys home appliance throughout the world. The manufacturing cost of SRM drive makes it hard to expand its application to home appliance. This paper presents Single Phase SRM for the vacuum cleaner that has advantge in cost and performance over conventional universal motor. This paper proposes new power device driving scheme by using SRM switching characteristic. The driving scheme is very simple and inexpensive. Dwell Time Control method is used for the minimum switching loss of power device. The switching frequency of power device is less than 4.5kHz at 45,000rpm. By use of this scheme, power device based on very small switching losses can be used on SRM drive. Also, the biggest problem in single phase SRM is starting, this paper shows a new starting algorithm with two hall sensors, accelerating and running sensors, respectively. Finally, the proposed Single Phase SRM achieves higher efficiency and long life time compared to universal motor. Its life time is more than 1500 hours. Its life time is extended 4 times than that of conventional motor and its suction power is increased $20\%$ at the same volume of conventional universal motor.

• 대한치과보철학회지
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• 제38권3호
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• pp.336-347
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• 2000

Statement of problem. Luster loss in esthetic anterior ceromer restoration can occur and can be related with rough surface texture. Understanding durability of surface finishing methods like polishing and surface coating have critical importance. Purpose. This study evaluated the effect of tooth brushing and thermal cycling on surface luster of 3 ceromer systems (Artglass, Targis, Sculpture) treated with different surface finishing methods. Material and methods. Seventy-two samples were prepared: 12 for control group Z100, 12 for Artglass, 24 for Targis, and 24 for Sculpture. Half of the Targis and Sculpture were polished according to the manufacturer's recommendation. The rest of the samples were coated with staining and glazing solution for Targis and Sculpture, respectively. All specimens were subjected to 10,000 cycles between $5^{\circ}C\;and\;55^{\circ}C$ with 30 seconds dwell time. Tooth brushing abrasion tests were performed in a customized tooth brushing machine with 500g back and forth for 20,000 cycle. Luster comparisons were based on grading after direct observation, and light reflection area was measured with Image analysis software. Results. All materials showed an decrease in luster grade after thermal cycling and tooth brushing. The post-tooth brushing results revealed that the glazed Sculpture had greater mean luster grade than did any other groups. While, the stained Targis group showed greatest changes after tooth brushing (p < 0.05), polished Targis and Sculpture did not show significant changes. However, glazed Sculpture showed discretely fallen out glaze resin. Conclusion. From the results of this study, all of the ceromer specimens were much glossy than control composite group after tooth brushing. coatings used for Targis and Sculpture had not durability for long term use.