• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.6
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• pp.879-888
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• 1999

A Study on the ARQ scheme of data error control is important for more reliable information transmission. Since performance difference is large by the long transmission delay time in satellite communication, the performances of SR ARQ and conventional type-I hybrid ARQ with fixed code rate are investigated by using the parameters of packet length, channel capacity, BER, and transmission delay time especially. BCH code is used in type-I hybrid ARQ for FEC method. This paper presents the throughput analyses according to such various parameters as BCH code rate, window size, data rate and round-trip delay time. Especially we derive a performance equation of type-I hybrid ARQ with the factor of the transmission delay time using the equation of SAW ARQ. Also, the performance of type-I hybrid ARQ specially considering transmission delay time is analyzed through numerical analysis and computer simulation so we can get a important characteristics variation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.9
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• pp.1057-1063
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• 2007

To analyze the performance of mobile communication systems, the exact information of the carrier-to-interference ratio is important. Under the presence of an interferer in a cell, the carrier-to-interference ratio of the receiver is determined by the ratio between the informer-receiver distance$(d_0)$ and the receiver-interferer distance$(d_1)$. In this paper, we derive the carrier-to-interference distribution based on $d_0/d_1$ values using the geometric relation among the informer, interferer and receiver, and confirm its exactness using the simulation result. We also apply the derivation result to a system with the adjacent channel interference, and analyze the outage probability.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.11C
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• pp.901-906
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• 2010

Low density parity check (LDPC) code, first introduced by Gallager and re-discovered by MacKay et al, has attracted researcher's interest mainly due to their performance and low decoding complexity. It was remarkable that the performance is very close to Shannon capacity limit under the assumption of having long codeword length and iterative decoder. However, comparing to turbo codes widely used in the current mobile communication, the encoding complexity of LDPC codes has been regarded as the drawback. This paper proposes a solution for DVB-S2 LDPC encoder to reduce the encoder latency. We use the fast IRA encoder that use the transformation of the parity check matrix into block-wise form and the partial parallel process to reduce the number of system clocks for the IRA code encoding. We compare the proposed encoder with the current DVB-S2 encoder to show that the performance of proposal is better than that of the current DVB-S2 encoder.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.5
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• pp.885-891
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• 2012

The synchronous flash of a marine lantern, differentiated from the flash pattern of other risk indicators, supports the safe sailing of vessels. General marine lanterns flash according to the flash protocol through sensing the day and the night. Thus, there can be time error over time and the marine lantern does not synchronously flash as a whole. To resolve this problem, this study designed LED marine lantern based on constant-current system using synchronous flash technique enabling all marine lanterns to keep its time based on GPS satellite time. Also we suggested a radiation method with an effective heat emission performance in the restricted and closed space of a marine lantern.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.9
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• pp.2124-2130
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• 2014

The standard for DGPS reference station system defined by RTCM is in the current version of 1.2. This standard currently supports only GPS of the United States. However, the current operating GNSS satellite consisted of not only GPS, but also GALILEO of Europe, GLONASS of Russia, QZSS of Japan, BeiDou of China and so on. Therefore, the existing standard is not able to support them. Accordingly, a new standard in the version of RTCM's RSIM 1.3 is established in order to provide correctional services to GNSS satellites. In this paper, the version of RSIM 1.3 is analyzed and the software for DGNSS reference station architecture supporting the version of RSIM 1.3 is designed.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.11
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• pp.2745-2752
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• 2014

In recent years, Transport Demand Management has been conducted for the efficient management of transport. In ITS applications in particular, the prerequisite is accurate and reliable positioning. However, the major problems are satellite signal outage, and multipath. This paper proposes that outage and multipath measurement can be detected and estimated using elevation angle and signal to noise ratio data association relation in stand-alone GPS. In order to verify the performance of the proposed method, it is then evaluated by the car test. the evaluation test environment has low accuracy and unreliable positioning because of signal outage or multipath such as steep hill and high buildings. In the evaluation test result, 918times abnormal signal occurred and it was confirmed that the proposed method showed more improved 9.48m(RMS) horizontal positioning error than without proposed method.

• Journal of Korea Society of Industrial Information Systems
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• v.28 no.1
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• pp.83-94
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• 2023

The study examines the current status of introducing technological innovation in the Uzbekistan logistics industry and proposes opportunities and challenging factors for the logistics industry following the introduction of technological innovation in the future. The analysis results revealed that the information technology used in the Uzbekistan logistics industry following technologies: RFID, barcode, Cool Guardian, tracking system, transport satellite monitoring, digital TIR, and GPS monitoring. In addition, Uzbekistan has recently been increasing investment in advanced information and communication technology not only at the corporate level but also at the governmental level in anticipation of becoming a hub for logistics. Based on these analysis results, the Uzbekistan logistics industry's proposed opportunities and challenging factors can be used as basic information for government policymakers, transportation and logistics companies, and various partners. It can also be used by logistic companies that seek to take advantage of Uzbekistan's strategic location to create a logistics hub in Central Asia.

• Journal of Navigation and Port Research
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• v.45 no.1
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• pp.26-32
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• 2021

In ocean field, the spread of the Fourth Industrial Revolution based on information and communication technology requires high precision and stable PNT&D (Position, Navigation, Timing and Data). As the IMO (International Maritime Organization) and IALA (The International Association of Marine Aids to Navigation and Lighthouse Authorities) are requiring backup systems due to mitigate vulnerabilities and the increase of dependency on GNSS (Global Navigation Satellite System), Korea is conducting a research & development of R-Mode. An DGPS (Differentiate Global Positioning System) reference station that uses MF, an existing maritime infrastructure, and AIS (Automatic Identification System) base stations that use 34 integrity station and VHF will be utilized in this study to avoid redundant investment. Because there are radio shadow areas that display low signal levels in the west sea, the establishment of new R-Mode reference and integrity station will be intended to resolve problems regrading the radio shadow area. Because the frequency has a characteristic in that radio wave transmits well along the ground (water surface) in low frequency band, simulation and measurement were conducted therefore this paper to propose candidate sites for R-Mode reference and integrity station resulted through p wave's propagation characteristics analysis. Using this paper, R-Mode reference and integrity station can be established at appropriate locations to resolve radio shadow areas in other regions.

• Korean journal of communication and information
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• v.18
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• pp.199-229
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• 2002

This study analyzed the trends of broadcaster licensing policy during 1990-2001 in Korea. It is to seek the answers about how the examination standards and procedures applied to broadcaster licensing has been changed for the last decade. For the purpose this study inquired six cases such as private broadcasting licence (1990 October), cable TV program provider licences(1993 July), cable TV system operator licences(1994 January), private local broadcaster licences(1994 July), satellite broadcaster licence(2000 December) and cable TV home shopping channel licences(2001 March). It examined the degree of specification and measurement of the standards based upon the government white paper; average points per item, average points per quantitative item, and average points per qualitative item etc. The government hadn't opened the standards and procedures how it licensed broadcasters until 1990 and the uncertain attitude brought distrust on the government broadcasting policy. The first white paper about broadcaster licensing was made in 1994 after cable TV broadcaster licensing was finished. The results indicated that Korean broadcasting licensing policy rapidly developed in the dimension of transparency from 'a secret room policy' to 'a sunshine policy' for the last decade. But it still needs improvement in the dimension of fairness of examination. Now one of the main distrust is the ratio that the one of qualitative examination standards are much more than the qualitative one.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.6
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• pp.1089-1098
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• 2020

In this study, we propose a method to detect red tide Cochlodinium Polykrikoide using by machine learning and geostationary marine satellite images. To learn the machine learning model, GOCI Level 2 data were used, and the red tide location data of the National Fisheries Research and Development Institute was used. The machine learning model used logistic regression model, decision tree model, and random forest model. As a result of the performance evaluation, compared to the traditional GOCI image-based red tide detection algorithm without machine learning (Son et al., 2012) (75%), it was confirmed that the accuracy was improved by about 13~22%p (88~98%). In addition, as a result of comparing and analyzing the detection performance between machine learning models, the random forest model (98%) showed the highest detection accuracy.It is believed that this machine learning-based red tide detection algorithm can be used to detect red tide early in the future and track and monitor its movement and spread.