• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.12
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• pp.22-31
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• 2015

Recently, 3rd Generation Partnership Project (3GPP) has developed device-to-device (D2D) communication to cope with the explosively increasing mobile data traffic. The D2D communication uses sidelink based on single carrier-frequency division multiple access (SC-FMDA) due to its low peak-to-average power ratio (PAPR). In addition, demodulation reference signal (DMRS) is designed to support multiple input multiple output (MIMO). In this paper, we propose the DFT-based channel estimation scheme for sidelink in D2D communication. The proposed scheme uses the 2-Dimensional Minimum Mean Square Error (2-D MMSE) interpolation scheme for the user moving at a high speed. We perform the system level simulation based on 20MHz bandwidth of 3GPP LTE-Advanced system. Simulation results show that the proposed channel estimation scheme can improve signal-to-interference-plus-noise ratio (SINR), throughput and spectral efficiency of conventional scheme.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.8
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• pp.1328-1336
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• 2003

This study was done to investigate the effects of n-3, n-6 fatty acid and d-limonene on the hepatic membrane lipid composition, protein kinase C (PKC) and glutathione S-transferase (GST) activities in experimental rat hepatocarcinogenesis. Sprague-Dawley female rats were fed with two different types of dietary oil for 20 weeks. Corn oil (CO) and sardine oil (SO) were used at 15% by weight as a source of n-6 and n-3 fatty acid, respectively. One week after feeding, rats were intraperitoneally injected twice with a dose of diethylnitrosamine (DEN, 50 mg/kg body weight) and after 1 week 0.05% phenobarbital (PB) was provided with drinking water. Membrane fractional lipid composition showed that the content of cholesterol was higher in 50 group than CO group and also significantly decreased by d-limonene. The content of phospholipid was increased by carcinogen treatment but not affected by dietary oils or d-limonene. Membrane C/PL molar ratio was significantly decreased by d-limonene or carcinogen treatment in 50 groups but not in CO groups. Fatty acid composition was changed by dietary oils but not by carcinogen treatment or d-limonene. Cytosolic PKC activity was not significantly different by dietary oils, d-limonene or carcinogen treatment. However, membrane PKC activity was significantly increased by carcinogen treatment and decreased by d-limonene. Cytosolic GST activity was affected by d-limonene or carcinogen treatment in all dietary groups. These data indicate that dietary oils, d-limonene and carcinogen treatment can not change much membrane phospholipid composition. But membrane C/PL molar ratio was changed by carcinogen treatment and d -limonene although the effect was different between dietary oils. Therefore, it is suggested that different dietary oils and d-limonene can somewhat modulate the changes of membrane fluidity and activities of membrane bound enzymes like membrane associated PKC during carcinogenesis.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.4
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• pp.94-100
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• 2007

The purpose of this work is to investigate the effect of properties of diesel and biodiesel fuels on the nozzle cavitation and the effect of the length/diameter(L/D) ratio on internal and external flow pattern of nozzle at the various injection conditions. In order to study the effect of the L/D ratio on the nozzle cavitation characteristics of diesel and biodiesel, the characteristics of cavitation flow in the nozzle are visualized and analyzed at the injection pressure of 0.1 MPa to 0.7 MPa by using the visualized images. It was founded that the cavitation was formed in the nozzle orifice at the low injection pressure and the breakup of the issuing liquid jet was promoted at the low L/D ratio. When the L/D ratio decrease, cavitation beginning and growth were affect by cavitation number and Reynolds number.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.2075-2076
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• 2011

The stator winding faults diagnosis technique based on MCSA is as follows. Firstly, collecting the 3 phase motor currents, that signal is transformed by (d-q transform, $i_d$, $i_q$). Park's vector pattern, the circle that is down by d-q transformed currents($i_d$, $i_q$). The circle is widely used for stator winding faults detection. The current distortion ratio(DR), defined by the ratio of max-axis and min-axis of ellipse of Park's vector's pattern. In this study, distortion ratio of Park's vector pattern is suggested for Auto diagnosis of stator winding short fault and usefulness of distortion ratio is verified through simulation using LabVIEW program.

• Journal of Korea Technology Innovation Society
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• v.21 no.1
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• pp.420-453
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• 2018

In the growth of the government's investment in national R&D project and the abuse of research expense, an effective control and management mechanism is strongly demanded. However, an excessive regulation might hinder the R&D performance, which also endangers the underlying objective of R&D policy. Especially, an excessive regulation on the R&D expenditure may damage the SMEs (Small and Medium sized Enterprises) where securing an adequate level of R&D funding is vital. This study investigates the R&D funding and R&D performance of SMEs participating in the national R&D project by using fixed effect panel model. As a result, this paper reveals the effectiveness of 'Government R&D subsidy'. However, that of 'private R&D fund' is not supported strongly. Also, this paper empirically demonstrates the efficiency of both 'Government R&D subsidy' and 'Private R&D fund' as the R&D costs are spent discretionarily (as the degree of 'Indirect Cost Ratio' increases). Especially, the effectiveness of 'Private R&D fund' can be moderated by 'Indirect Cost Ratio'. On the basis of the conclusions, this paper draws an implication that can increase R&D performance of SMEs through the interactions of manifold administrative values (i.e. effectiveness, efficiency and responsibility).

• Journal of the Korean Operations Research and Management Science Society
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• v.40 no.4
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• pp.19-33
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• 2015

Recently, interest in research and development (R&D) investment decisions have increased among Korean domestic enterprises. However, existing R&D investment studies only focused on government R&D investment policies while only a few studies investigated firm level R&D investment. Prior literatures also overlooked the feedback loop between R&D investment and firm performance. Therefore, this paper identifies a system dynamics model for R&D investment decision making in domestic electronics firms. The conceptual model is derived from R&D investment-related theories found in bodies of literature on company performance, enterprise activity, and market maturity. This study investigates the dynamic feedback between R&D activities and sales using the system dynamics model. In other words, the system dynamics model is used to explain the change in the closed feedback circulation structure in R&D investment activities including technology development, production process, and marketing that subsequently result in sales increase and re-investment into R&D from the generated revenues. There are two major results. First, a similar ratio of investment on technology development and production process derives the higher company sales. Second, regardless of market maturity, marketing investment ratio positively affects sales and R&D budget growth. This study provides a system dynamics model to find the optimal ratio for R&D investment and suggests managerial strategic implications on electronic firm R&D investment decision making under market maturity condition.

• Journal of Fisheries and Marine Sciences Education
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• v.12 no.1
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• pp.1-10
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• 2000

In order to obtain the fundamental data on the auditory thresholds of fishes for marine ranching, the auditory thresholds of black rock fish Sebastes Schlegeli were measured in the presence of masking noise in the spectrum level range of 73 - 83dB (0dB re $1{\mu}Pa/{\sqrt{Hz}}$) with a classical cardiac conditioning technique. Critical ratios were about 19 - 30dB at 80 - 300Hz and 46 - 54dB at 500 - 800Hz. The ratio increased almost linearly with increasing frequency to 500Hz. The noise spectrum level at the start of masking was about 70dB within the frequency range of 80 - 800Hz excepting 65dB at 300Hz. This suggests that hearing of the black rock fish is masked in the natural environment with the noise spectrum level above 65dB. The sound pressure level of which the signal sound of 100 - 200Hz is recognized by black rock fish under the ambient noise is above 90dB and the critical ratio of them is above 20dB.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.4
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• pp.1415-1435
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• 2018

Resource allocation in device-to-device (D2D) aided cellular systems, in which the proximity users are allowed to communicate directly with each other without relying on the intervention of base stations (BSs), is investigated in this paper. A new uplink resource allocation policy is proposed by exploiting the relationship between D2D-access probability and channel gain among variant devices, such as cellular user equipments (CUEs), D2D user equipments (DUEs) and BSs, etc., under the constraints of their minimum signal to interference-plus-noise ratio (SINR) requirements. Furthermore, the proposed resource-allocation problem can be formulated as the cost function of "maximizing the number of simultaneously activated D2D pairs subject to the SINR constraints at both CUEs and DUEs". Numerical results relying on system-level simulations show that the proposed scheme is capable of substantially improving both the D2D-access probability and the network throughput without sacrificing the performance of conventional CUEs.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.349-356
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• 2010

In this study, a new design method of pile bent structure considering plastic hinge was proposed on the basis of the beam-column model. Based on the analysis results, it is found that the positioning of plastic hinge on the pile bent structure was influenced by nonlinear behavior of material and p-$\Delta$ effect. Moreover, concrete cracking began to occur at the joint section between the pile and column in case of pile bent structure with different cross-sections. The plastic hinge can be developed on the pile bent structure when large displacement was occurred, and pile bent structures can be maintained well only if it is developed on the column part. Therefore, in this study, the optimized cross-section ratio between column and pile was analyzed to induce the plastic hinge at the joint section between the pile and column. Based on this, the optimized diameter ratio of pile and column can be obtained below the inflection point of the bi-linear curve depending on the relations between column-pile diameter ratio($D_c/D_p$) and normalized lateral cracking load ratio($F/F_{Dc=Dp}$). And through this study, it is founded that in-depth limit($L_{As}$=0.4%) normalized by the pile length($L_P$) are proportionally decreased as the pile length($L_P/D_P$) increases up to $L_P/D_P$=17.5, and beyond that in-depth limit converges to a constant value. Finally, it is found that the proposed limit depth by taking into account the minimum concrete-steel ratio would be more economical design of the pile bent structure.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.3 s.118
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• pp.341-350
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• 2007

In this paper, the derivation of protection ratio is newly proposed for the detailed planning of frequency coordination in microwave relay networks, and computed results for protection ratio of co-channel and adjacent channel are illustrated over the actual system and its frequency. It is shown that the suggested method based upon availability prediction can be expressed in terms of composite fade margin, interference-to-noise ratio(I/N), net filter discrimination, and system parameters. According to results, for 6.7 GHz, 60 km, 64-QAM, and I/N= -6 dB at BER $10^{-6}$, composite fade margin and co-channel protection ratio provide 25.5 and 50.7 dB, respectively. Also, net filter discrimination and adjacent channel protection ratio are obtained as 26.3 and 24.4 dB, respectively, at the first adjacent channel of 40 MHz. The proposed method provides some merits in computing protection ratio for microwave relay networks in view of an easy extension and practical applications considering more detailed and various system parameters.