• Journal of Advanced Marine Engineering and Technology
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• v.35 no.8
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• pp.1092-1097
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• 2011

Data communications at sea are done by the traditional radio and satellite carriers. Because of the restrictions on the data rate and cost of the carriers, a novel data communication system at sea is needed. Nowadays the efforts to make use of the broadband land carriers at sea have been pursued. This paper proposes a routing scheme (NTCR) using the various carriers on land for a MANET model at sea. The NTCR scheme optimizes the route using a chosen carrier by taking considerations of normalized transmission characteristics (NTC) of applications and carriers. The NTCR scheme is compared with the MWR (max-win based routing) scheme.

• Journal of Broadcast Engineering
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• v.21 no.4
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• pp.552-561
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• 2016

In OFDM system, frequency-domain sub-carriers of a symbol generally consist of data sub-carriers and scattered pilot sub-carriers and in the receiver, channel is estimated through time-axis interpolating pilot sub-carriers of several OFDM symbols. However, time-axis interpolation fails to keep track of rapid channel variation caused by fast moving receiver. Although symbol by symbol channel estimation without time-axis interpolation enables fast estimation, the performance is severely degraded for a long delay spread channel in a single frequency networks (SFNs) because of insufficient pilot sub-carriers. In this paper, a channel estimation scheme for OFDM receiver in a fast mobile SFN channel is proposed. The proposed scheme is applied to DVB-T receiver to improve the Doppler mobile performance in SFN channel.

• Journal of Distribution Science
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• v.15 no.11
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• pp.59-72
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• 2017

Purpose - This paper evaluated the efficiency performance of the three major maritime transport markets and examined the determinants of the performance. The firms' revenue fluctuates with the changes of the economic cycle; hence it is important for them to set up business strategies to improve efficiencies. A lack of efficiency measurements for shipping firms leads to a significant gap in determining their overall performance. Research design, data, and methodology - Each of DEA scores was adopted for the evaluation and panel regression was used to examine the impact of determinants on the performance. The analysis included 50 shipping firms from three maritime transport markets as follows; 15 firms of container liners, 18 firms of bulk carrier and 17 firms of tanker carriers, and its period was from 2010 to 2016. Results - In the CCR model, container liners were the highest, tanker carriers were the second, and bulk carriers were the lowest in operation efficiency and financial efficiency. By region, operation efficiency and financial efficiency was high in the order of America, Asia, and Europe. Conclusions - This study suggests business strategies for maritime transport companies based on the analytical results of determinants of operational and financial efficiency.

• Transactions of the Korean hydrogen and new energy society
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• v.27 no.5
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• pp.581-588
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• 2016

To compare reduction reactivity of oxygen carrier particles, $CH_4$ combustion characteristics were measured and investigated in a bubbling fluidized bed reactor with increasing $CH_4$ concentration from 10 to 100 %. Among five oxygen carriers (OC-1, OC-2, SDN70, C14, C28), OC-1, OC-2, SDN70 particles were selected as better oxygen carriers from the viewpoints of fuel conversion and $CO_2$ selectivity. However, some oxygen carriers showed lower fuel conversion and $CO_2$ selectivity even though they have high oxygen transfer capacity. Therefore, we could conclude that not only TGA tests to measure the oxygen transfer capacity but also fluidized bed tests to analyze exhaust gas concentration should be performed to select better oxygen carrier without misunderstanding of carriers reactivity.

• Journal of Navigation and Port Research
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• v.46 no.5
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• pp.441-448
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• 2022

The aim of this study was to examine determinants of secondhand Bulk carrier and Oil tanker prices. This study compiled S& P transaction data taken from the Clarksons Research during J anuary 2018 to April 2022 to see how independent variables influenced secondhand ship prices. In the secondhand ship pricing model of entire segments, size, age, and LIBOR showed significant effects on prices. A vessel built in J apan and Korea was traded at a higher price than a vessel built in other countries. In the bulk segment, size, age, Clarksea index, LIBOR, and inflation were meaningful variables. In the Tanker segment, unlike Bulk carrier, only size and age were useful variables. This study performed regression analyses for various sizes of Bulk carriers and Oil tankers. It verified that impacts of variables other than ship size and age were significantly associated with ship type and size while macroeconomic variables had no influence except for bulk carriers. By applying diverse variables affecting secondhand ship price estimation according to various sizes of Bulk carriers and Oil tankers, this study will expand the scope of practical application for investors. It also reaffirms prior research findings that the secondhand ship market is primarily market-driven.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.2
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• pp.317-324
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• 2022

In this thesis, in consideration of the functions of general carriers, smart carriers with various convenience functions were studied for supplementation and improvement based on the disadvantages of carriers and inconvenience when using them. Based on the app inventory program, LED and motor locks were installed in carriers through smartphone applications, Bluetooth recognition and control functions that easily control on/off, load cell sensors were installed inside the carriers to detect weight, install Bluetooth and alarms on LCD panels, and prevent theft and loss.

• Journal of Environmental Health Sciences
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• v.9 no.1
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• pp.95-99
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• 1983

A study on the salmonella pullorum was carried out on 15, 000 hens of breeding chicken, when examined using pullorum antigens, and 165eggs from the isolated breeding to 35among 171carriers used in o serums in Chonnam area during the period from November 22 to December 20, 1982 The results are summarized as follows 1. Distribution on the carriers of pullorum disease was investigated 171 carriers (1.1%) among 15, 000 hens examined. 2. A majority (33.3%) of group D(transovarian transmission) was observed by classification of salmonella groups in the order of group OB (18.8%), group E(18.2%), group $C_1, C_2$ (each 15.2%~), and group OA (12.7%)

• Bulletin of the Korean Chemical Society
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• v.16 no.1
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• pp.33-36
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• 1995

Macrocyclic ligands have been studied as cation carriers in a supported liquid membrane system. Cd2+ has been transported using nitrogen substituted macrocycles as carriers and several divalent metal ions (M2+=Zn, Co, Ni, Cu, Pb, Mg, Ca, and Sr) have been transported using DBN3O2, DBN2O2and PolyNtnoen as carriers in a supported liquid membrane system. Competitive Cd2+-M2+ transport studies have also been carried out with the same system. Ligand structure, stability constant, membrane solvent and carrier concentration are also important parameters in the transport of metal ions.

• Proceedings of the IEEK Conference
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• 2000.06a
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• pp.37-40
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• 2000

As the number of CDMA subscribers increases, CDMA systems utilize more than one CDMA carrier In order to accommodate Increasing capacity requirement. In this paper, we present a new analytical method for evaluating the Erlang capacity of CDMA systems with multiple CDMA carriers. in the case of the algorithm proposed in 〔5〕, the calculation complexity for evaluating the call blocking probability Is increased proportionally to the sixth power of the number of used CDMA carriers when the CDMA system supports voice and data services. Consequently, It is Impractical to calculate Erlang capacity with the algorithm of 〔5〕especially when the number of used CDMA carriers is larger than 3. To resolve this problem, we propose a new analytical method for evaluating the Erlang capacity. The calculation complexity of the proposed method for evaluating call blocking probability is increased just proportionally to the second power of the number of used CDMA carriers when the CDMA systems support voice and data services.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.9
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• pp.72-79
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• 1997

The dominant physical process repsonsible for the nonlinear gain is from spectral-hole burning with the time constant fo about 50fs and the contribution to the nonlinea rgain form hot carriers effect is determined to be about 15% of the contribution due to spectral-hole burning. To prove the above results we fit the data of hall and found that hot carriers have a profound effect on their experimental data despite the fact that the magnitude of hot carriers effect is only 15% of spectral-hole burning. We suggest that the experimenta with a pump pulse width of 180 fs is very sensitive in detecting the effect of hot carriers, but is not sensitive in detecting much faster process associated with spectral-hole burning.