• Journal of Biosystems Engineering
• /
• 제43권4호
• /
• pp.331-341
• /
• 2018

Purpose: This study was conducted to develop a linear Proportional-Integral-Derivative (PID) control algorithm for the ascending and descending system of a rice transplanter and to analyze its response characteristics. Methods: A hydraulic model using a single-acting actuator, proportional valve and a PID control algorithm were developed for the ascending and descending system. The PID coefficients are tuned using the Ziegler-Nichols (Z-N) method and the characteristics of unit step response are analyzed to select the PID coefficients at various pump speeds. Results: Results showed that the performance of the PID controller was superior in any condition. It was found that the highest settling time and maximum overshoot were less than 0.210 s and 5%, respectively at all pump speed. It was determined that the steady state errors were 0% in all the cases. The lowest overshoot and settling time were calculated to be nearly 2.56% and 0.205 s, respectively at the pump rated speed (2650 rpm). Conclusions: The results indicated that the developed PID control algorithm would be feasible for the ascending and descending system of a rice transplanter. Finally, it would be helpful to plant the seedlings uniformly and improve the performance of the rice transplanter.

• 한국전자통신학회논문지
• /
• 제13권6호
• /
• pp.1365-1372
• /
• 2018

최근 농업 사회의 고령화로 인해 농기계로 인한 안전사고가 급증하고 있다. 어떤 경우에는 부상자가 사고를 주위에 알리지 못한 채 홀로 방치되어 심각한 상황에 이를 수 있다. 경운기, 이앙기, 트랙터, 콤바인 등 농기계를 대상으로 작업 및 이동 중에 전복, 충돌, 기타 사고 등의 안전사고 발생 시 ICT 기술을 이용하여 신속하게 사고 상황을 외부에서 감지하고 전달함으로써 인명 피해를 최소화 할 수 있는 시스템이 요구되고 있다. 본 연구에서는 농기계의 충돌 및 전복 사고를 감지하고, 위험상황을 전송하는 ICT 기반의 농기계 안전사고 자동상황전파시스템을 제안한다. 제안된 시스템은 농기계 사고 발생 시 자동으로 가족, 지인, 병원 및 119로 문자 메시지를 보냄으로써 빠른 사후 조치를 통한 인명구조를 가능하게 한다.

• 연구논문집
• /
• 통권29호
• /
• pp.185-194
• /
• 1999

The shape and thickness distribution according to the pressure-time curve were carried out using the FEM and experiment. Also, mechanical properties were investigated. The square cup parts have been formed with pressure-time curve generated by result of analysis. The tensile strength and elongation have been investigated according to applied pressure conditions using the tensile test specimen obtained from the superplastic formed cup. We can use to predict the shape of formed part under the applied pressure using the FEM analysis. In the case of optimum pressure condition, the thickness distribution and mechanical properties were improved. From this study, we can find the important of optimum pressure-time condition. We have investigated about the forming of airplane part and fuel tank for motorcycle. If the applied load used in boundary conditions was appropriate, the simulation result coincides with the formed part. However, it is very difficult to define the pressure condition in complicated shape. Thus, it is need to develop the optimum pressure condition for superplastic forming.

• 한국생산제조학회지
• /
• 제7권5호
• /
• pp.92-97
• /
• 1998

The morpholgies of the wear particles are directly indicative of wear processes occuring in machinery and their severity. The neural network was applied to identify wear debris generated from the machine driving system. The four parameters(50% volumetric diameter, aspect, roundness and reflectivity) of wear debris are used as inputs to the network and learned the friction condition of five values(material 3, applied load 1, sliding distance 1). It is shown that identification results depend on the ranges of these shape parameters learned. The three kinds of the wear debris had a different patter characteristic and recognized the friction condition and materials very well by artificial neural network. We discussed how the network determines differencee in wear debris feature, and this approach can be applied to foreseeability and decisio for moving condition of the Machine driving system.

• 연구논문집
• /
• 통권22호
• /
• pp.65-74
• /
• 1992

This paper aims at calculating optimum design dimensions to minimize the weight satisfied strain and stress intensity of the frame while loading maximum weight into a mechanical press in the static condition. Analysis of the frame was carried out by using the FEM, then the optimum condition was obtained by using these data. As modeling in the finite element analysis has great impact on the reliablity of analysis results, the analyzed object was selected a 150-ton mechanical press of J Company, the part little affected to structural rigidity was simplified, the load condition was considered in the only maximum load, the boundary condition was used by giving symmetric displacement due to symmetric boundary condition, the finite element was applied a linear membrane element. An intermediate processor program applied the normal ANSYS to analyze finite elements was developed, and the design sensitivity was calculated. This program was applied to the optimum design.

• 한국기계연구소 소보
• /
• 통권9호
• /
• pp.115-131
• /
• 1982

• 열병합발전
• /
• 통권37호
• /
• pp.18-21
• /
• 2004

There are several bearing system at large steam-turbines in thermal power plant. The bearing system is one of the most important parts of rotating machinery. The steam turbine vibrations mainly depend on the bearing oil the shaft alignment condition. This paper describes on the steam turbine abnormal vibration due to the oil whip in terms of the shaft alignment in the thermal power plant.

• 유체기계공업학회:학술대회논문집
• /
• 유체기계공업학회 2002년도 유체기계 연구개발 발표회 논문집
• /
• pp.161-164
• /
• 2002

Present condition of small fan used in appliances and IT industry is briefly reviewed. Here, fans used in refrigerator, air-conditioner, vacuum cleaner, microwave oven and computer are surveyed. Also some comments about the issue of each fan is described.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2013년도 춘계학술대회 논문집
• /
• pp.672-673
• /
• 2013

• 한국가스학회지
• /
• 제25권2호
• /
• pp.34-41
• /
• 2021

국내에서 사용되는 천연가스가 저열량화 되면서 발생할 수 있는 문제점에 대응하기 위해서는 국내 산업용 가스기기에 미칠 수 있는 문제점을 사전에 파악하고, 이를 기반으로 에너지의 효율적인 사용을 위한 대응방안이 선행되어야 한다. 본 연구에서는 EURO-6 규제를 대응하는 희박연소방식의 천연가스 엔진을 이용할 경우, 저열량 가스의 도입으로 인한 엔진 출력성능과 효율의 저하 문제를 해결하기 위해, 실험을 토대로 한 구체적인 제어방안과 결과를 제시하고자 하였다. 전부하 운전조건인 1,400 rpm의 엔진 회전수에서 스로틀이 전부 개방된 전부하 조건과 정격운전조건의 엔진회전수인 2,100 rpm, 450 Nm의 토크 조건에서 점화시기로 대표되는 제어변수에 의한 개선효과 확인을 위해, 각 가스연료에 대해서 점화시기를 변경하여 열효율 및 배출가스특성을 파악하고 최적화하였다. 전부하조건에서 토크를 기준으로 가장 낮은 값을 보이는 순수메탄의 경우 기준 조건에서 약 2 CAD 정도 점화시기를 진각하면 NOx 배출의 큰 증가 없이 토크를 보상할 수 있다.