Hiesik Kim

Environmental Monitoring Systems: A Review

This review article discusses various techniques of environmental monitoring (EM) systems and what is required for the variations in hardware implementation and/or algorithmic logic. This review presents an overview of the existing state-of-the-art practices of environmental monitoring systems and is mainly focused on energy-efficient and low-cost environment monitoring systems. The following are some of the major factors that usually rule the development of EM systems, namely, energy efficiency, cost of the overall system, response time of the sensor module, good accuracy of the system, adequate signal-to-noise ratio, radio frequency interference/electromagnetic interference (RFI/EMI) rejection during varying atmospheric conditions and in inhomogeneous environments, a user friendly interface with the computer, and complexity of computation. The above concerns are also recognized by reference to research articles on environmental monitoring systems. Emphasis is on the necessity of robust systems that address all or most of the above mentioned criteria.

Design of Air Pollution Monitoring System Using ZigBee Networks for Ubiquitous-City

The innovative Ubiquitous-City was born through convergence of construction, home applications and culture, with development of up to date information technologies and ubiquitous IT. The U-City can be applied to a variety of special situations for managing functions of each city efficiently. This paper focuses on implementation of air pollution monitoring system. First, each sensor was tested after survey about market trends of a variety of sensors for detecting air pollution. Second, wireless communication modules for monitoring system were developed using wireless sensor networks technologies based on ZigBee. And then a performance of modules was estimated in the real-fields. Through software programs written in nesC for efficient routing in wireless networks were simulated using TOSSIM simulator. Finally, integrated wireless sensor board which employs dust, CO2, temperature/humidity sensor and a ZigBee module was developed. The board is embedded device based on AT91SAM7S64 porting uCOS. This paper accelerates the digital convergence age through continual research and development of technologies related the U-City.

Development of energy efficient ZigBee module

This study investigated and developed an energy efficient ZigBee wireless module using hardware technique. The MG2455-F48 RF SoC chip was used in developing the ZigBee wireless module. This chip consists of 2.4GHz RF part and 8051 family microcontroller. ZigBee modules are powered by a battery because it has to be movable. Energy saving of the ZigBee module has been one of important issues because its battery life time is limited. Nowadays many energy efficient software algorithms have been developed for ZigBee modules, that are used in data transmission between nodes. A node means a ZigBee module. In order to save energy in the ZigBee module, software algorithm was not used in this study, but we used the hardware technique. The microcontroller of ZigBee controls power of the sensors which connected on the ZigBee module. Sensors are active only when they need to transmit data and in other case the module switches to the power down mode and save energy.

A study of hand-geometry recognition system

This paper presents humans hand geometry recognition system in the field of bio-metric. Hand geometry recognition system is used in many application and security fields. A pattern of hand shape and palm contains much information for identifying person. Hand geometry pattern is used to identify different pattern of hand shape and palm lines. Every person has different hand lines and shapes that do not change during the life time. Simple algorithm and experiment device were implemented to identify the person by their hand image from the input camera. The geometrical characteristics in hand shape such as length of fingers, wrist width, width and length of the palm and angle thickness of middle finger also their ratios are used. Identification rate of system should be at least 98% then that system can be used application fields. In this study, identification rate equals to 91%. Therefore, we have upgraded and developed better algorithm for extracting special characteristics from hand line and shape in further work.

Upgrade of Electronic Security Fence System by Reduction of Vibration Noise by Wind Effect

Vibrational noise signal due to wind force on the electronic fence security system need to be overcome. Sensor cables were already fast fixed on to existing security fence perimeter. The wind noises generated by the strong wind were much problem by the real operation of electronical fence system. Wind noise signals receiving from sensor cables were processed and analyzed to improve the existing program in the DSP (TMS320F2812) microcontroller. The system collects signal amplitude, duration time and frequency spectrum to distinguish the wind effect from intrusion signal. The result gives the real or false alarm. Frequency analysis was done for each duration of N = 128 samples of input signal was using special algorithm of the fast Fourier transform through DSP microcontroller. The security system has been tested at border lines of Mongolia. A detection rate after apply the developed algorithm for reducing false alarms was improved up to 94%– 95% of reliable accuracy for real field application.

Implementation of Redundant Digital Excitation Control System Algorithm

Currently, Korean electric power system requires stability and reliability. All the systems demands a high reliability due to the characteristics of power plant. An algorithm for the redundant digital excitation control system has been implemented in this study. Excitation control system is one that maintains or controls output terminal voltage by supplying DC current to the field winding. Domestic controllers are needed as existing controllers are made in overseas so that it is difficult to maintain them properly. Thus, in this study, an algorithm for a redundant digital excitation control system was implemented with C language. The results of implementation were validated through on-site tests at ‘P’ power plant. The authors aims to assist system developers in understanding the flow of excitation system by disclosing the C-style pseudo code.

A Method for Replacing Protective Relay at Kanudi Power Plant and Validation

A modern electric power systems require both stability and reliability. This study involves validation of the method used for replacing the protective relays at the Kanudi power plant in Papua New Guinea. Replacement of 27 and 81 protective relays at the existing power plant was due to their failure. A new relays were installed after removing the power source of existing panel. The output section of each new relays was connected with existing relay in parallel as previous protective relay only allowed monitoring without outputting the contents so that the new protective system was designed to in a way that both existing and new relays perform detection. The validation after the replacement was successful. The new system aims to protect power generator by coping with accidents.

Minimal Electric Charge Detection Device for Perimeter Security Systems

Passive types of perimeter security systems based on the detection technique of minimal electric charge are developed and applied in the test fields. The detection technique of electric charge is based on the triboelectric effect. If two different types of materials are rubbed with each other, electric charges are generated at the friction surface. Simple telecommunication cable can be employed instead of the expensive sensor transducer for sensing the exterior intrusion. Minimal electric charges are generated between the cable conductors and isolator when little forces and impacts are applied to the cable. The developed charge detection device detects the generated minimal charges. The fixed long length of sensor cable is fastened on the various types of perimeter fences. It is a passive sensor fence based on the algorithm of electrostatic charge separation detecting the friction electromotive force. The guard alarm for perimeter fences is generated by signals on the local deformation of the fence and the sensor fastened to it at any unauthorized penetration by getting over the fence. Charge sensitivity of the developed experimental device is 1.6×10 coulombs. This system is expected to be applied widely in more field areas.

Air Pollution Monitoring and Control System for Subway Stations Using Environmental Sensors

The metropolitan city of Seoul uses more energy than any other area in South Korea due to its high population density. It also has high emissions of air pollutants. Since an individual usually spends most of his/her working hours indoors, the ambient air quality refers to indoor air quality. In particular, PM10 concentration in the underground areas should be monitored to preserve the health of commuters in the subway system. Seoul Metro and Seoul Metropolitan Rapid Transit Corporation measure several air pollutants regularly. In this study, the accuracy of an instrument for PM measurement using the light scattering method was improved with the help of a linear regression analysis technique to continuously measure the concentrations in subway stations. In addition, an air quality monitoring system based on environmental sensors was implemented to display and record the data of PM10, CO2, temperature, and humidity. Through experimental studies, we found that ventilation fans could improve air quality and decrease PM10 concentrations in the tunnels effectively by increasing the air flow rate.

Optimization of the wiring in the sequence control circuit

The sequence control circuit is widely used in 3 phase induction motor control circuit in the industry. There is a problem in the wiring process of the conventional sequence control circuit. Within a limited time it occurs often is missing wiring or wiring mistakes or repeated mistakes. Up to the conduction test from wiring in the control circuit, there is a problem that could not often be perform perfectly. In other words, it means that multiple wiring modifications are required. In this paper, written as a result of the efforts of a lot of trial and error and process improvement experience in the field, in the meantime to overcome the problems of general wiring methods and proposes a new optimal wiring method. Optimal Wiring method is the objective to minimize the problem caused by the wiring part of the wiring between the sequence control circuits. Using the optimal method of wiring to 3 phase induction motor control circuit used in many industries have attempted virtual wiring. This method is possible to identify in advance the path problem analysis on wiring. This method also improves wiring and could reduce the manufacturing cost. Optimum wiring method is also easy to debug by wiring. In addition, in the event of a missing or incorrect wiring, this method can be relatively simple circuit conduction test.