• Proceedings of the Korean Society for Agricultural Machinery Conference
• /
• 1993.10a
• /
• pp.192-196
• /
• 1993

Following the transfer of China's economy from planning to market economy, it is necessary to develop and strength the service system for agricultural mechanization . The current situation of the service system was investigated and some suggestions are proposed in this paper.

• Archives of Plastic Surgery
• /
• v.44 no.5
• /
• pp.470-471
• /
• 2017

• Journal of Applied Reliability
• /
• v.14 no.2
• /
• pp.122-128
• /
• 2014

In this paper, we consider the periodic preventive maintenance model for a repairable system following the expiration of extended warranty under replacement-repair warranty. Under the replacement-repair warranty, the failed system is replaced or minimally repaired by the manufacturer at no cost to the user. Also, under extended warranty, the failed system is minimally repaired by the manufacturer at no cost to the user during the original extended warranty period. As a criterion of the optimality, we utilize the expected cost rate per unit time during the life cycle from the user's perspective. And then we determine the optimal preventive maintenance period and the optimal preventive maintenance number by minimizing the expected cost rate per unit time. Finally, the optimal periodic preventive maintenance policy is given for Weibull distribution case.

• Journal of the Korean Institute of Navigation
• /
• v.25 no.4
• /
• pp.407-415
• /
• 2001

In the present study, irregular disturbances to ship dynamics is proposed, where irregular disturbances implying irregular wave and the fluctuating component of wind for the evaluation of automatic steering system of ship in following seas. Prediction method based on the principle of linear superposition. Irregular wave disturbances in following seas is calculated by frequency variation method. The mathematical model of each element of an automatic steering system is derived, which takes account of a few non-linear mechanisms. PD(Proportional-Derivative) controller and low-pass filter with a weather adjustment are adopted to modelling the characteristics of an autopilot. Performance index is introduced from the viewpoint of energy saving, which derived from the concept of energy loss on ship propulsion. Finally, the present methods are applied to two typical types of ship ; an ore carrier and a fishing boat. The various effects of control constants of autopilot on propulsive energy loss are investigated

• Proceedings of the KIEE Conference
• /
• summer
• /
• pp.248-250
• /
• 2004

Following the needs for increment of public transportation system electric railroad system should be expended. There are several solutions to expend. One of these solutions is to reduce the interval between two railroad vehicles. However, it cannot be reduced too much because reduction of interval means increment of loads and induces supplying voltage decrement. In this paper, voltage variation according to railroad intervals is simulated and optimal operation in railroad system is proposed.

• Proceedings of the KIEE Conference
• /
• 2001.05a
• /
• pp.95-99
• /
• 2001

Frequency is the unique physical value for all the interconnected systems. Therefore. the load frequency control is in the responsibility of all members in the interconnection power unbalance in one of the interconnected system can cause the problems in others. In the following text a brief description and the role of frequency in an interconnected system will be presented. Following is the short description of the Balkan Interconnection (UCTE Second Synchronous Zone) with schematic diagram. A Power-Frequency (P-f) dynamic model of a control area wil1 be shown. Model gives the analytical solution for frequency change versus a time after outage of a generator in the power system. This model will be applied to the Balkan Interconnection and compared with numerical approach. Advantages and drawbacks of the analytical method will be discussed Purpose of using this model is to investigate if the pumps in reversible hydropower plant will be underfrequency shed after the outage of the biggest generator unit in the interconnection, according %o (n-1) security postulate.

• 제어로봇시스템학회:학술대회논문집
• /
• 1992.10a
• /
• pp.1024-1027
• /
• 1992

This paper deals with design method of the model following servo system in which optimal regulator probelm is used to design the controllers that make the step/ramp response of the plant be keptclose to a specified ideal step/ramp response of the model. The characteristics of this system is robust in the presence of the specified disturbances or the partameter perturbations of the plant. Especially, by direct feedforward compensator from the reference input the steady state offset of plant output response is excluded and the transient response is improved. Examples are give and the results of the design of the model follwing servo systems are verified by the computer simulation.

• Journal of the Korea Safety Management & Science
• /
• v.16 no.3
• /
• pp.421-432
• /
• 2014

This study is intended to analyze the relation between G. D. Weisman's Way finding 4 elements the accessibility and efficiency of consumers as to eternal area for Seoul historical museum. The findings are summarized as the following three aspects. First, G. D. Weisman's Way finding element introduced in this study had a significant impact on visitor satisfaction.. It leads to the following conclusion: The higher the impact is, the greater accessaccessibility and efficiency are. Second, among 4 elements, the factor that had the biggest impact on the accessibility was 'visual-perceptual accessibility'. Thus, 'visual-perceptual accessibility' should be considered first to boost the accessibility to consumers. Third, among 4 elements, the factor that had the biggest impact on the efficiency was 'sign system'. Thus, 'sign system' should be considered first to boost the efficiency to consumers.

• Proceedings of the KSR Conference
• /
• 2007.11a
• /
• pp.57-64
• /
• 2007

RIMS（Rolling Stock Information Maintenance System)　was installed in structure which it can analyze the data base in need of credibility maintenance. So it could accumulate real data without repulsion of working spot. Information system was installed not following to system but following to working spot. The development of RIMS project was started from March 29, 2001 and it has been operating from October 12, 2004 in Chang-dong Car depot for light maintenance in charge subway line4. So substantial data base was accumulated for three years. This study calculated all RAMS data by analyzing data base accumulated in RIMS and used in dada base about credibility maintenance and found investigation of propriety, expectation of the life cycle cost, the improvement plan on credibility of sorts of cars and formation about the cycle of repairing and maintenance. This got MKBSF MKBF and MTBF about devices and sorts of line4 Rolling Stocks for it.

• Proceedings of the KSR Conference
• /
• 2007.11a
• /
• pp.143-150
• /
• 2007

RIMS（Rolling Stock Information Maintenance System)　was installed in structure which it can analyze the data base in need of credibility maintenance. So it could accumulate real data without repulsion of working spot. Information system was installed not following to system but following to working spot. The development of RIMS project was started from March 29, 2001 and it has been operating from October 12, 2004 in Chang-dong Car depot for light maintenance in charge subway line4. So substantial data base was accumulated for three years. This study calculated all RAMS data by analyzing data base accumulated in RIMS and used in dada base about credibility maintenance and found investigation of propriety, expectation of the life cycle cost, the improvement plan on credibility of sorts of cars and formation about the cycle of repairing and maintenance. This got MKBSF MKBF and MTBF about devices and sorts of line4 Rolling Stocks for it.