• 한국정밀공학회지
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• 제22권4호
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• pp.27-36
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• 2005

Some studies have shown that unstable factors are inherent in WEDM process, causing the instability of the discharging pulse to reach about 40∼60％ in normal machining. Transient stability is an important subject in WEDM process since there is a close relationship between stability and machining performance, such as the characteristics of a machined surface, machining speed and problem of instability like wire rupture phenomenon. Among the many machining parameters affecting WEDM machining state, three specific parameters (Vr, Ip, off time ) are major controllable variables that can be applied in transient stability control. And, this research investigates the implementation and analysis of real-time micro control of the discharging stability of WEDM (Wire Electric Discharge Machining) process.

• 한국정밀공학회지
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• 제17권2호
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• pp.151-160
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• 2000

An experimental and theoretical analysis for the improvement of dynamic characteristics and design of electro-hydraulic flow control servo valve are performed. The theoretical results are compared with the experimental step responses, and the important design parameters of an electro-hydraulic flow control servo valve are derived by using the simulation program. Simulation parameters of nozzle jet coefficient and orifice and spool valve discharge coefficient are given through experiment. The theoretical and experimental step response curves show that the valve gain depends on the fixed orifice and nozzle $ratio(R_on)$ and is maximum at $R_on=1.$ And drain orifice in the flapper - nozzle return line creates a small back pressure, which improves the performance fur the valve.

• 가정간호학회지
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• 제17권1호
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• pp.21-27
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• 2010

Purpose: The study evaluated a program to shorten EMC stay time. Methods: The subjects were EMC patients, and comprised a control group of 8,477 and an experimental group of 8,378. Data were collected from June 2006 to August 2007, and analyzed concerning stay time for doctor visit, decision making, and discharge. The data were analyzed by $X^2$-test and ANCOVA using SPSS14.0. Result: The stay time of doctor visit, decision making and discharge of the experimental group was significantly less compared to the control group. Using second and third grade triage criteria, the stay time of experimental group was statistically reduced from the control. Conclusion: The implemented shortening program was effective in reducing EMC stay time and increasing EMC effectiveness.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.459-462
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• 2002

Many active and passive flow control methods have been studied since decades, but there are only few works about flow control methods using ion wind. This paper presents an experimental study on the wake control behind a circular cylinder using ion wind, a bulk motion of neutral molecules driven by locally ionized air of corona discharge. Experiments are done f3r different electrohydrodynamic numbers - the ratio of an electrical body farce to a fluid Inertial force - from 0 to 2 and for the Reynolds number ranging from $4{\times}10^3\;to\;8{\times}10^3$. Pressure distributions over a cylinder surface are measured and flow visualizations are carried out by smoke wire method. Flow visualizations confirm that ion wind affects significantly the wake structure behind a circular cylinder and pressure drag could be dramatically reduced by the superimposing ion wind.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 C
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• pp.1852-1854
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• 2003

In manufacturing processes, various and suitable pulse shapes are required for the purpose of material processing. In order to make various pulse shapes with variable pulse length and high duty cycle, We have fabricated the power supply consisting 6 SCRs and the Pulse Forming Network(PFN) with the precise delay time control. So our control system has three switching circuits, 3 mesh PFN, and simmer circuit. In addition, we have designed and fabricated the PIC one-chip microprocessor(16F877) to control the delay time of sequential switching.

• 한국방재학회 논문집
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• 제4권1호
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• pp.41-50
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• 2004

본 연구에서는 퍼지제어기법을 이용한 홍수조절 모형의 적용성을 파악하기 위해 한강수계 단일댐에 적용하였다. 개발된 모형들의 홍수조절능력을 비교하기 위해 1984, 1990, 1995년 대홍수 발생시 실제 운영실적과 본 연구에서 개발된 모형들의 가상운영결과를 비교하였다. 본 연구에서 개발한 3개 모형은 모두 실제 적용성을 고려하여 댐의 수위와 유입량이라는 2가지 정보량으로부터 방류량을 결정토록 하였으며, 최대방류량 역시 댐 설계시 기준인 허용최대방류량을 초과하지 않도록 하였다. 각 홍수사상에 대해 적용한 결과 기존의 댐 운영결과에 비해 홍수위를 낮출 수 있으면서도 하류부의 피해 최소화에도 적절한 것으로 나타나 퍼지제어모형의 적용성을 확인할 수 있었다.

• 기본간호학회지
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• 제18권2호
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• pp.160-167
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• 2011

Purpose: The purpose of this study was to identify the effects of an oral stimulation program on premature infant's transition from tube feeding to bottle feeding, decrease in desaturation during feeding, and early discharge. Methods: This quasi-experimental study was performed in one neonatal intensive care unit (NICU) of an university hospital. The control group data (n=69) were obtained from June 2008 to May 2009, and the experimental group data (n=67), from June 2009 to May 2010. The oral stimulation program (OSP) was provided daily before feeding for the experimental group until transition to bottle feeding was completed. Results: The OSP group began bottle feeding earlier and were on complete bottle feeding earlier than control group. Discharge delay due to feeding desaturation was lower than for the control group. Conclusion: The results indicate that OSP for premature infants was helpful in transition from tube feeding to bottle feeding and early discharge and thus can contribute health and development in premature infants.

• Child Health Nursing Research
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• 제26권3호
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• pp.376-384
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• 2020

Purpose: This study aimed to determine the influence of a breastfeeding coaching program (BCP) for mothers of late preterm infants (LPIs) on the breastfeeding rate and neonatal morbidity within 1 month after discharge. Methods: This was a non-randomized quasi-experimental study with a time series design. The participants were 40 LPIs and their mothers who were hospitalized in a neonatal intensive care unit at a university hospital. Nineteen LPIs were assigned to the control group, and 21 to the experimental group. The mothers of the LPIs in the experimental group received the BCP once on the discharge day and then once a week for 1 month. Neonatal morbidity was defined as an outpatient department or emergency room visit due to an LPI's health problem. Results: The breastfeeding rate in the experimental group was significantly higher than in the control group at the fourth week after discharge (χ²=7.17, p=.028). Five and two LPIs in the control group and the experimental group, respectively, visited a hospital due to neonatal jaundice. Neonatal morbidity was not significantly different between the two groups (χ²=1.95, p=.164). Conclusion: The BCP was useful for improving the breastfeeding rates of LPIs and may have potential to reduce neonatal morbidity.

• 한국수자원학회논문집
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• 제30권3호
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• pp.257-268
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• 1997

홍수시 최적의 방류량을 목표로 하는 댐 운영자의 경우 방류량을 결정하는데 있어 댐의 안전과 저수지의 운영효율을 고려한 이해할 만한 근거를 제시할 필요가 있다. 본 연구에서는 예측된 홍수수문곡선을 댐 규정에 명시된 무피해방류량을 기준으로 분할하여 무피해방류량으로 조절되는 부분과 홍수조절용량을 이용하여 조절되는 부분으로 구분하였다. 홍수조절용량을 이용하는 경우 예측홍수를 판단하는 기준을 마련하여 저수지 운영의 안전과 효율을 고려한 홍수조절계획을 수립하는 방안 ("저수지 홍수변환법")을 강구하였다. 본 연구에서는 연구범위를 단일 댐의 홍수시 저수지 운영 방안으로 제한하여 대청 다목적 댐을 적용하고 그 결과를 분석하였다.

• 제어로봇시스템학회논문지
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• 제16권1호
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• pp.12-17
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• 2010

The oil tanker ship over 150GRT must equip oil content meter which satisfy requirements of revised MARPOL 73/78. Online measurement of oil content in complex samples is required to have fast response, continuous measurement, and satisfaction of ${\pm}10ppm$ or ${\pm}10%$ error in this field. The research of this paper is to develop oil content measurement system using analysis of light transmission and scattering among turbidity measurement methods. Light transmission and scattering are analytical methods commonly used in instrumentation for online turbidity measurement of oil in water. Gasoline is experimented as a sample and the oil content approximately ranged from 14ppm to 600ppm. TSK Fuzzy Model may be suitable to associate variously derived spectral signals with specific content of oil having various interfering factors. Proposed Parallel TSK Fuzzy Model is reasonably used to classify oil content in comparison with other models. Those measurement methods would be effectively applied and commercialized to oil content meter that is key components of oil discharge monitoring control equipment.