• Ocean and Polar Research
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• v.21 no.2
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• pp.117-126
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• 1999

To meet increasing needs for environmentally sustainable management of coastal area, there has been compelling pressure to establish a cost-effective and long-term coastal water quality (CWQ) monitoring system. A remote CWQ monitoring system, STAMP, has been developed and is in operation along the route between Kyema harbor and Anma Island in the southwestern coastal area of Korea. STAMP uses a PCS phone as a telemetry unit to transmit acquired data for monitoring general water quality parameters, and a routinely operating coastal passenger ship or car ferry. STAMP has various merits of low-cost operations; long-term monitoring with secure instrumentation; and stable real-time telemetry of acquired data with-out the loss and noise. It is expected that the system will serve as a very useful tool in the CWQ managing programs of Korea taking the advantage of many coastal passenger ships in various routes including the ships departing from the coastal industrial cities. The acquired data compiled on suspended surface sediment concentrations (SSSC) will be also valuably helpful in understanding the sediment budget across the routes of the vessel.

• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.2747-2749
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• 2000

The KEPRI has been developing the medium/small scale Distribution Automation System(DAS) that adopts wireless transmission media for exchanging information between master and remote terminals. It was concluded that Short Message Service(SMS) of Personal Communication Service(PCS) was the best wireless transmission media for the medium/small scale DAS in the last year. However. we had problem that PCS had long transmission delay. Therefore. SMS phones will be substituted with Radio Link Protocol(RLP) modems having transmission delay less than 5 seconds. This paper describes wireless networks for DAS, practical experience.

• Journal of Korean Institute of Industrial Engineers
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• v.22 no.4
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• pp.551-565
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• 1996

We present the required handover capacity of personal communication service exchange(PCX). We use the flow-based mobility model. The dimension of PCX area and the number of radio port controller(RPC) in a PCX are determined according to the traffic carrying capacity of switching system and RPC. For the rectangular or square-shaped PCX/RPC area and the personal communication service environment with pedestrian traffic, we perform numerical computations to investigate the sensitivity to cell size, portable station(PS) terminating traffic, its density, and its average speed. The results how that the size of PCX/RPC area decreases as the PS terminating traffic and the PS density increase, and the PCX handover capacity required is more than 73,000 in the number of transactions per hour.

• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.1
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• pp.71-77
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• 2013

Smart work has been gaining more popularity recently. Smart work means that employees perform their works anytime and anywhere as utilizing the information and communication technology. It can be divided into four categories; the mobile office, the home office, the work-at-center and the tele-cooperation. Among them, the mobile office based on tablet personal computers(PCs) or smart phones, employees can exchange information with tablet PCs or smart phones via mobile radio communication networks and portable terminals. Smart devices such as tablet PCs and smart phones help to access intranet system for requests, approvals, information search whenever employees need. This mobile office system for real-time HSE managing can contribute to improve the productivity and work efficiency in a shipyard. In this study, the main goal is to design the specialized mobile application for the HSE management system on the shipbuilding industry. The mobile application including 10 functions is designed based on ooCBD(object-oriented Component Based Development) methodology.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.4
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• pp.668-675
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• 2001

Recently, the performance of the commercial PCS(Personal Communication Service) system has been improved to the uppermost limit and ultimately the next generation mobile communication is to be realized by IMT-2000 (International Mobile Communication-2000) to provide multimedia services. Therefore, the new type receiving system is researched actively and one of the most important part in a receiver is direct conversion method. The direct conversion method is suitable for low power consumption, small size, MMIC, and low price, which is to be adopted to the next generation mobile communication systems. In this case, however, several problems occur due to DC-offset. The DC-offset suppresses amplification of the required signal because of the leakage signal of frequency synthesizer in the system. In this thesis, the removing method of DC-offset was considered. There are four removing techniques of DC-offset, which are AC-coupling, large capacitor, DC-feedback loop, and DC-free coding. Among these, the AC-coupling method is the most simplest method and the DC-feedback loop method has the best performance. Then, the performance of the AC-coupling method and DC-feedback loop method are evaluated by HP's ADS simulation tool. As a result, the AC-coupling method cannot be used to the digital communication systems due to data loss. On the other hand, it was confirmed that the DC-feedback loop method is suitable for the direct conversion receiver.

• Journal of IKEEE
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• v.12 no.4
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• pp.185-195
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• 2008

In this paper, PIFA(Planar Inverted F Antenna) which operates in PCS(Personal Communication System) band is designed and characteristics are investigated. Designed PIFA was installed in three types of handsets, folder, bar, slide, and the performance was evaluated. Head and hand phantom were added to make the most similar environment to real condition of mobile phone use, and influences on antenna performance were analyzed. The simulation results confirm radiation patterns are greatly changed and antenna efficiency is decreased by the effect of human body. Performance variation of the mobile handset antenna was observed as changing the angle between mobile handset and head phantom from $0^{\circ}$ to $2^{\circ},\;4^{\circ}$ to confirm the variation caused by the relative position of mobile handset and head phantom. Directivity was decreased gradually as the antenna goes away from head phantom, and showed the trend of increasing efficiency. But in the case of bar type, where the position of antenna is relatively close to head phantom, that trend didn't show. It was confirmed that the shape of handset has a great effect on the performance.

• Journal of IKEEE
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• v.4 no.2 s.7
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• pp.241-248
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• 2000

A linear power amplifier is particular emphasized on the CDMA system using a linear modulation scheme, because intermodulation distortion which cause adjacent channel interference and co channel interference is mostly generated in a nonlinear power amplifier. In this paper, a new type of linearization technique proposed. It is presented that balanced MESFET predistortion linearizer added. Experimental result are present for Korea PCS(Personal Communication Service) frequency band. The implemented linearizer is applied to a 30dBm class A power amplifier for simulation Performance. The predistortion linearizer improves the 1dB compression point of the HPA about 2dBm, and intermoudulation distortion about 12.5dBc.

• Journal of information and communication convergence engineering
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• v.8 no.6
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• pp.630-634
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• 2010

In this paper, we designed and fabricated a multi-band folded monopole antenna for mobile handsets that can be used for multiple services. The proposed antenna, with a small size of $28.060{\times}12.665{\times}5.035mm^3$ can provide sufficient bandwidth to cover the GSM900 (Global System for Mobile Communications: 880-960 MHz), DCS (Digital Cellular System: 1710-1880 MHz), K-PCS (Korea-Personal Communication Service: 1750-1870 MHz), Wibro (2300-2390 MHz) and Bluetooth (2400-2483 MHz) bands.

• Journal of the Korea Society of Computer and Information
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• v.12 no.6
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• pp.213-218
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• 2007

We propose a compact internal quard-band antenna with sufficient impedance bandwidths and gains for the GSM(Global Systems for Mobile), GPS(Global Positing System). DCS(Digital Codeless System), PCS (Personal Communication System) operation. The proposed antenna on a substrate. which is small enough to be installed in practical mobile phones, has heights of only 6mm from the substrate. In addition, the proposed antenna decreases the construction complex on the substrate. The GSM ($880MHz{\sim}960MHz$) GPS(1575MHz) DCS($1710MHz{\sim}1880MHz$). PCS($1750MHz{\sim}1870MHz$) bands. Details of the design and analysis of the proposed antenna are described and the experimental results of the constructed prototype are presented.

• Journal of Korean Society of Transportation
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• v.17 no.3
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• pp.7-20
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• 1999

This Paper Presents a Internet-based Real-Time Automated Vehicle Location System(AVLS), which is able to Provide users with real-time vehicle Positioning information. When Inverted Differential GPS is available, this system does more aggressive position correction than GPS, and more useful for public transportation and commercial application than DGPS in terms of cost.