• Journal of Korean Society of Forest Science
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• v.96 no.5
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• pp.510-514
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• 2007

The main purpose of this study was to develop Mountain Search and Rescue System for enhancing search and rescue operations in the mountains. This study also focused on presenting an alternative to using a cellular phone for requesting rescue due to their unreliability in remote areas. This system is designed to help in the search and rescue of people in emergency situations in the mountains. It is composed of buzzer sensors, environmental information sensors, and a statistical analysis program. A key feature of this system is that it does not require an infrastructure of internet or CDMA networks for its operation in the mountains. The measure for the study was conducted by using a zigbee protocol analyzer, RF module and 433MHz Helical antenna to analyze the rate of data reception in relation to the distance between nodes. This system is applicable to mountains provided the distance between nodes is over 100 m and under 150 m.

• Journal of Environmental Science International
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• v.17 no.1
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• pp.77-83
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• 2008

The purpose of this study was to develop the national park visitor counting system using the ubiquitous sensor network. This system is composed of a sensor node, sink node, gateways, CDMA module, server, and clients. The results of the study were: 1) stable data transmission distance was possible within 100 meters between sensor nodes, 2) the developed counting sensor system showed a network communication stability level of 88.3 percent in 1.2m wide trails. When installed in concentrate use areas or forks of national parks, the visitor counting system will not only contribute to provide reliable visitor counting, but also to improve the quality of national park visitor service, to manage park facilities and natural resources more efficiently, to achieve an information oriented national park system.

• 한국정보통신설비학회:학술대회논문집
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• 2007.08a
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• pp.176-180
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• 2007

In this study, we deployed the cable tunnel inspection and monitoring system by wireless sensor network. It is shown that the wireless sensor network which is composed of sensor, wireless communication module, and gateway can be applied to cable tunnel monitoring system. Sensors considered herein are flame detection sensor, flood detection sensor, intruder detection sensor, and temperature sensor, etc. It is also found that the wireless sensor network can deliver sensing data reliably by wireless sensing technology. The gateway system that can transmit sensed data to server by CDMA is developed. Monitoring system is constructed by web service technology, and it is observed that this system can monitor the present state of tunnel without difficulties. The system provides an alternative to inspect and monitor the tunnel efficiently where the conventional wired system is infeasible.

• 한국정보통신설비학회:학술대회논문집
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• 2006.08a
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• pp.91-94
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• 2006

In this paper, we deployed the tunnel inspection and monitoring system by wireless sensor network. It is shown that the wireless sensor network which is composed of sensor, wireless communication module, and gateway system can be applied to tunnel monitoring system. Sensors included herein are acceleration transducers, fire-alarm sensors, water-level sensors, and magnetic contact sensors. It is also found that the wireless sensor network can deliver sensing data reliably by ad-hoc networking technology. The gateway system that can send the sensing data to server by CDMA (code division multiple access) is developed. Finally, monitoring system is constructed by web service technology, and it is observed that this system can monitor the present state of tunnel without difficulties. Furthermore, the above system provides an alternative to inspect and monitor the tunnel efficiently where the conventional wired system cannot be applied.

• Proceedings of the KIEE Conference
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• 2002.11c
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• pp.15-18
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• 2002

This paper presents an ECG (electrocardiogram) telemetry system, in which patients can be monitored in nearly any environment by mobile communication. The ECG is transmitted to a monitor center via a built-in CDMA modem and forwarded to a cardiologist for diagnosis. Also this paper designed and implemented the receiving server which receives the ECG from the ECG aquisition module of patients by Internet. The server puts the ECG into a database. This telemetry system significantly increases the patient's safety and comfort.

• Proceedings of the KIEE Conference
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• 2002.11c
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• pp.454-456
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• 2002

Embedded system is used a lot in electric home appliances and home network equipment. However, this system is designed to operate by the system operator directly at home and operator could find out them only when he pays attention to the system in case event happens. In this paper, to improve above things, it designed to remote-control system anywhere in which internet access is possible as well as at home, and also it designed SMS(short message service) information transmission system to inform the errors to the operator when they happen. To design the system, development board(be included the Strong Arm), CDMA module, and electric door lock are used as hardware, and web browser, CGI(common gateway interface) programming, and C-language are used for implementation of software in embedded-linux platform.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.549-552
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• 2008

In this study, we deployed the cable tunnel inspection and monitoring system by wireless sensor network. It is shown that the wireless sensor network which is composed of sensor, wireless communication module, and gateway can be applied to cable tunnel monitoring system. Sensors considered herein are flame detection sensor, flood detection sensor, intruder detection sensor, and temperature sensor, etc. It is also found that the wireless sensor network can deliver sensing data reliably by wireless sensing technology. The gateway system that can transmit sensed data to server by CDMA is developed. Monitoring system is constructed by web service technology, and it is observed that this system can monitor the present state of tunnel without difficulties. The system provides an alternative to inspecting and monitoring the tunnel efficiently where the conventional wired system is infeasible.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.3
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• pp.276-282
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• 2015

Until recently, power amplifiers using LDMOS were Class-AB and Doherty type, and showed 55 % efficiency for narrowband of 60 MHz bandwidth. However, owing to the RRH application of base stations power amplifier module, a bandwidth expansion of at least 100 MHz and high efficiency power amplifiers of at least 60 % power efficiency are required. In this study, a Class-J power amplifier was designed by optimizing an output matching circuit so that the second harmonic load will contain a pure reactance element only and have broadband characteristics by using GaN HEMT. The measurements showed that a 45 W Class-J power amplifier with a power added efficiency of 60~75 % was achieved when continuous wave signals were input at 1.6~2.3 GHz, including W-CDMA application.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.6
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• pp.842-848
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• 2011

A fabricated hybrid control board using multi-communication is designed with a low power 8-bit microcontroller, ATxmega128A1. The microcontroller consists of 8 UART (Universal asynchronous receiver/transmitter) ports, 2 kbytes EEPROM, 128 kbytes flash memory, 8 kbytes SRAM. The 8 URAT ports are used for a multi-communication modem, a GPS module, etc. The EEPROM is used for saving a configuration for running programs, and the flash memory of 128 kbytes is used for storing a F/W (Firm Ware), and the 8 kbytes SRAM is used for stack and for storing memory of global variables while running programs. If we use the multi-communication of CDMA, TRS and RF to remotely control Aid to Navigation, it is able to remove the communication shadow area. Even though there is a shadow area for an individual communication method, we can select an optimal communication method. The compatibility of data has been enhanced as using of same data frame per communication device. For the test, 8640 of data have been collected from each buoy during 30 days in every 5 minutes and the receiving rate of the data has shown more than 85 %.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.1305-1312
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• 2006

This study is about the development of measurement system using ubiquitous wireless communication for river flow monitoring. The system can acquire water depth, quality (temperature, pH, conductivity, turbidity etc.) while a GPS module for getting the location data of measurement points. Also this system is able to acquire the field data via RF connection and can be controlled same time. The acquired data is transmitted to a gateway system from the remote buoy using Zigbee wireless connection. And the gateway system is able to monitor the data through GIS monitoring tool. Finally the data are transmitted to a server computer using CDMA wireless connection by gateway system. The D/B of server computer are constructed automatically and monitored the project web site. The resulting system can be used for scour monitoring, environment monitoring and the other monitoring purposes such as a river flow monitoring system.