• Korean Journal of Veterinary Research
• /
• v.61 no.3
• /
• pp.20.1-20.9
• /
• 2021

This study is to develop a new scoring system for rating Hazard analysis and critical control points prerequisite evaluation items for meat shops to provide a more objective and accurate evaluation of food safety compliance. The importance of each item was measured by looking at the hazard severity level and the rate of non-compliance associated with it. It was found that the new scoring system is more stringent and gives a clearer picture of compliance with the most critical safety standards, and therefore is expected to have a positive effect on the hygiene and safety of livestock products.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2010.10a
• /
• pp.324-329
• /
• 2010

Vibrations caused by automobile engine are absorbed mostly by a passive-type engine mount. However, user specifications for automobile vibrations require more stringent conditions and higher standard. Hence, active-type engine mount have been developed to cope with such specifications. The active-type engine mount consists of sensor, actuator and controller where a control algorithm is implemented. The performance of the active engine mount depends on the control algorithm if the sensor and actuator satisfies the specification. The control algorithm should be able to suppress persistent vibrations caused by the engine which are related to engine revolution. In this study, three control algorithms are considered for suppressing persistent vibrations, which are the positive position feedback control algorithm, the strain-rate feedback control algorithm, and the modified higher harmonic control algorithm. Experimental results show that all the control algorithms considered in this study are effective in suppressing resonant vibrations but the modified higher harmonic controller is the most effective controller for non-resonant vibrations.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.20 no.12
• /
• pp.1176-1182
• /
• 2010

Vibrations caused by automobile engine are absorbed mostly by a passive-type engine mount. However, user specifications for automobile vibrations require more stringent conditions and higher standard. Hence, active-type engine mount have been developed to cope with such specifications. The active-type engine mount consists of sensor, actuator and controller where a control algorithm is implemented. The performance of the active engine mount depends on the control algorithm if the sensor and actuator satisfies the specification. The control algorithm should be able to suppress persistent vibrations caused by the engine which are related to engine revolution. In this study, three control algorithms are considered for suppressing persistent vibrations, which are the positive position feedback control algorithm, the strain-rate feedback control algorithm, and the modified higher harmonic control algorithm. Experimental results show that all the control algorithms considered in this study are effective in suppressing resonant vibrations but the modified higher harmonic controller is the most effective controller for non-resonant vibrations.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.32 no.9
• /
• pp.80-87
• /
• 2004

Active control of on-orbit spacecraft jitter is a significant problem for future spacecraft mission requiring stringent pointing performance. Jitter is major disturbance source degrading payload pointing performance. Both passive and active jitter isolation techniques have been studied during the last decade. We present active jitter isolation for a model device in this work. The device provides active control capability by 3 degree-of-freedom control of payload in feedback control strategy. Mathematical modeling of the device is pursued which is naturally used for a baseline controller design. Simulation results are used to validate the designed control law.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.21 no.8
• /
• pp.741-751
• /
• 2011

Vibrations caused by automobile engine are absorbed mostly by a passive-type engine mount. However, user specifications for automobile vibrations require more stringent conditions and higher standard. Hence, active-type engine mounts have been developed to cope with such specifications. In this study, the active vibration absorber which can be attached to the sub-frame of automobile is used for the suppression of vibrations caused by engine. The active vibration absorbing system consists of sensor, actuator and controller where a control algorithm is implemented using DSP. The vibration caused by engine reveals harmonic disturbances varying with engine revolution. Therefore, the control algorithm should be able to cope with harmonic disturbances. In this study, the modified higher harmonic control technique which can selectively suppress harmonic disturbance is considered. Experimental results on automobile show that the proposed active vibration absorbing system is effective in suppressing vibrations caused by engine.

• ETRI Journal
• /
• v.30 no.5
• /
• pp.729-734
• /
• 2008

Wireless communication systems, such as WLAN or Bluetooth receivers, employ preamble data to estimate the channel characteristics, introducing stringent settling-time constraints. This makes the use of traditional closed-loop feedback automatic gain control (AGC) circuits impractical for these applications. In this paper, a compact feedforward AGC circuit is proposed to obtain a fast-settling response. The AGC has been implemented in a 0.35 ${\mu}m$ standard CMOS technology. Supplied at 1.8 V, it operates with a power consumption of 1.6 mW at frequencies as high as 100 MHz, while its gain ranges from 0 dB to 21 dB in 3 dB steps through a digital word. The settling time of the circuit is below 0.25 ${\mu}s$.

• Journal of Institute of Control, Robotics and Systems
• /
• v.6 no.6
• /
• pp.433-440
• /
• 2000

To flexibly evaluate performance and reliability of a real-time system which is intrinsically characterized by stringent timing constraints to generate correct responses, we propose fuzzyrandom variables and build a discrete event model embedded with fuzzy-random variables. Also, we adapt fuzzy-variables to a path-space approach, which derives the upper and lower bounds of reliability by using a semi-Markov model that explicitly contains the deadline information. Consequently, we propose certain formulas of state automata properly transformed by fuzzy-random variables, and present numerical examples applying the formulas to RTP(Rapid Thermal Process) to show that a complex system can be properly evaluated based on this model by computer simulation.

• Proceedings of the Korean Society of Agricultural Engineers Conference
• /
• 2001.10a
• /
• pp.399-402
• /
• 2001

After the legal foundation for the Total Load Control System (TLCS) process is embedded in integrated water management counterplan for 4 major river basins (1998), Kyunggido Kwangju City prepared the implementation plan of TLCS at first time. There is little difference between TLCS and TMDL(Total Daily Maxium Loading; U.S.A). TMDL is applied only when mandatory effluent limitations are not stringent enough to attain any water quality standard. But object of TLCS not only attain water quality standard at distributed watershed but also consider development of area at non-distributed watershed. For applying of systematic and consistent TLCS, we need to establish a system integrated watershed and point source, non-point source and assessed massive database easily. Now we are study on applicable possibility of BASINS on Korea, we think that BASINS's tool and many models are more easily apply to TLCS, so we recommend TLCS will be applied using BASINS.

• The Transactions of the Korean Institute of Electrical Engineers D
• /
• v.55 no.5
• /
• pp.199-204
• /
• 2006

To develop a safety-critical network in nuclear power plants that puts more stringent requirements than the competitive commercial ones do, we establish four design criteria - deterministic communication, explicit separation/isolation structure, reliability, verification & validation. According to those design criteria, the fundamental design elements are chosen as follows - a star topology, point-to-point physical link, connection-oriented link control and fixed allocation access control. After analyzing the design elements, we also build a communication architecture with TDM (Time Division Multiplexing) bus switching scheme. Finally, We develop a DDCNet (Deterministic Data Communication Network) based on the established architecture. The DDCNet is composed of 64 nodes and guarantees the transmission bandwidth of 10Mbps and the delay of 10 msec for each node. It turns out that the DDCNet satisfies the aforementioned design criteria and can be adequately utilized for our purpose.

• Journal of Korean Society for Atmospheric Environment
• /
• v.10 no.4
• /
• pp.217-223
• /
• 1994

Carbon dioxide emission has been increased by 7% in an annual average toward 212.5 million tons in 1990 from 108.7 million tons in 1980. Among emissions in 1990, industry, residential / commercial, transportation, other and non-energy have occupied 91.12, 68.04, 42.13, 7.13 and 4.09 million tons respectively. The Korea-scenarios corresponding to those of IPCC that is Intergovernmental Panel on Climate Change (A : modest control of $CO_2$; B : stringent control of $CO_2$, C: shifting fuel to renewable and nuclear energy in the second half of the next century ; and D: shifting fuel to renewable and nuclear energy in the first half of the next century show that the global-scale contributions of atmospheric $CO_2$ concentration are 0.77, 0.64 and 0.78% in 2050 for cases A,B, and C respectively. In all cases, the contributions were smaller than 0.09 % in 1985.