• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.3 no.1
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• pp.63-69
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• 2010

In this paper, a new design method of asymmetrical configuration of main amplifier and peaking amplifier using changed bias point is proposed for excellent linearity, instead of the conventional Doherty structure. We have utilized the uneven wilkinson power divider for the unequal power drive at the input network of amplifiers. And we proposed a compensating method of the decreasing efficiency due to improving linearity using 3-stage Doherty structures. From the simulation results of asymmetrical Dohertry power amplifier and asymmetrical 3-stage Doherty power amplifier with uneven power drive are implemented. From the implementation and measurement results of the each amplifier, IMD characteristics have -55 dBc as the good efficiency of 13% compensates the decreased entire efficiency due to the improving linearity characteristics.

• Journal of the Korea Safety Management & Science
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• v.9 no.5
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• pp.17-25
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• 2007

All of the city gas companies in Korea must employ the gas safety patrols by law. The gas safety patrols are responsible for the various tasks including daily gas pipeline patrol to prevent gas accidents. Since the size of jurisdiction varies among the city gas companies, it is very difficult to compare their efficiency for the operations of the safety patrol each other directly. The objective of this research is to develop the methodology to analyze and compare the efficiency of the safety patrol's operations among various city gas companies. Several factors that are related to the safety patrol's duty on the gas safety factors were identified and DEA(Data Envelopment Analysis) model for efficiency analysis was developed. Finally, the DEA model was applied to the collected data from six city gas companies. The less efficient city gas companies can benchmark the higher efficient city gas companies in order to improve the safety control systems.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2006.06b
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• pp.91-96
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• 2006

In this paper, the high efficiency Doherty power amplifier has been designed and realized for microwave applications. The Doherty amplifier has been implemented using silicon MRF 281 LOMOS FET. The RF performances of the Doherty power amplifier (a combination of a class AB carrier amplifier and a bias..tuned class C peaking amplifier) have been compared with those of a class AB amplifier alone. The realized Doherty power amplifier PldB output power has 33dBm at 2.3GHz frequency. Also the Doherty power amplifier shows 11dB gain and -17.8dB input return loss at 2.3GHz to 2.4GHz. The designed Doherty amplifier has been improved the average PAE by 10% higher efficiency than a class AB amplifier alone. The Maximum PAE of designed Doherty power amplifier has been 39%.

• Journal of Ocean Engineering and Technology
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• v.34 no.3
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• pp.217-226
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• 2020

An offshore plant is an offshore platform that can process oil and gas resources in rough seas with a poor working environment. Moreover, it is a complex structure with different types of offshore facilities and a large amount of outfitting that connects different offshore installations. In particular, an enormous amount of various piping materials is installed in a relatively narrow space, and thus, the difficulty of working is relatively high compared to working in ships or ground plants. Generally, when the 3D detailed design is completed, an offshore plant piping process is carried out at the shipyard with ISO 2D fabrication drawings and ISO 2D installation drawings. If a worker wants to understand the three-dimensional piping composition in the working area, he can only use three-dimensional viewers that provide limited functionality. As offshore plant construction progresses, correlating work with predecessors becomes more complicated and rework occurs because of frequent design changes. This viewer function makes it difficult to identify the 3D piping structure of the urgently needed part. This study deals with the process support method based on a system using a 3D simulator to improve the efficiency of the piping process. The 3D simulator is based on the Unity3D engine and can be simulated by considering the classification and priority of 3D models by the piping process in the system. Further, it makes it possible to visualize progress information of the process. In addition, the punch content can be displayed on the 3D model after the pipe inspection. Finally, in supporting the data in relation to the piping process, it is considered that 3D-simulator-supported piping installing could improve the work efficiency by more than 99% compared to the existing method.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.11
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• pp.5209-5228
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• 2016

Device-to-device (D2D) communication underlaying cellular networks can bring significate benefits for improving the performance of mobile services. However, it hinges on elaborate resource sharing scheme to coordinate interference between cellular users and D2D pairs. We formulate a joint mode selection, link allocation and power control optimization problem for D2D communication sharing uplink resources in a multi-user cellular network and consider the efficiency and the fairness simultaneously. Due to the non-convex difficulty, we propose a three-step scheme: firstly, we conduct mode selection for D2D pairs based on a minimum distance metric after an admission control and obtain some cellular candidates for them. And then, a cellular candidate will be paired to each D2D pair based on fairness. Finally, we use Lagrangian Algorithm to formulate a joint power control strategy for D2D pairs and their reused cellular users and a closed-form of solution is derived. Simulation results demonstrate that our proposed algorithms converge in a short time. Moreover, both the sum rate of D2D pairs and the energy efficiency of cellular users are improved.

• Nuclear Engineering and Technology
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• v.54 no.1
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• pp.19-29
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• 2022

The 2D/1D method has become the mainstream of the direct transport calculation considering the balance of accuracy and efficiency. However, the 2D/1D method still suffers from stability issues. Recently, a quasi-3D method has been proposed with axial Legendre expansion. Analysis and comparison of the 2D/1D and quasi-3D method is conducted in theory from the equation derivation. Besides, the C5G7 benchmark, the KUCA benchmark and the macro BEAVRS benchmark are calculated to verify the theory comparisons of these two methods with the direct transport code SHARK. All results show that the quasi-3D method has better stability and accuracy than the 2D/1D method with worse efficiency and memory cost. It provides a new option for direct transport calculation with the quasi-3D method.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.9
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• pp.1065-1071
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• 2010

In this paper, we proposed a novel harmonic load circuit to design a high efficiency class-F amplifier. The proposed load circuit controls termination impedances to enhance the efficiency of class-F power amplifier. The termination impedances at the 2nd and the 3rd harmonics are showed short and open condition, respectively. Also, a fabricated load circuit showed an attenuation characteristic more than 29 dB, that is enough to eliminate harmonics of the class-F power amplifier. The measured drain and power-added efficiency are 75.7 % and 71.3 % at the point of maximum output power 35.17 dBm.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.195-196
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• 2008

Doping depth, doping concentration, and resistivity of crystalline silicon solar cell are variables which take important portion in cell's efficiency. To get highly efficient solar cell, PC1D is used to calculate $I_{sc}$, $V_{oc}$, and $P_{max}$. Depth factor, peak doping, and base resistivity was used as variables. As a result, the optimized value of emitter peak doping is $1\times10^{19}cm^{-3}$, depth factor is $1{\mu}m$, and base $\rho$ is $ 0.1\Omega$-cm. Under the optimized condition, the solar cell gets efficiency 19.03(%).

• Korean Journal of Optics and Photonics
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• v.14 no.3
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• pp.306-311
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• 2003

In this paper, we modeled the incident beam in order to analyze and evaluate the optical thin film device for wavelength division multiplexing in optical telecommunication network. As applied ray tracing method to the optical path, we were compared the accuracy of coupling efficiency simulated by two modeling methods. In the results of sinulation, ceil modeling method was preferred to annual modeling method in micro-optic device because of accuracy for coupling efficiency and Gaussian intensity distribution. In the results of optimal simulation for optical device using thin film filter, the distance (d1) between optical fiber and GRIN lens, the distance (d2) between GRIN lens and thin film filter and the coupling efficiency were 0.24 mm, 0.25 mm and -0.11 ㏈ respectively. As d2 was displaced at 0.25 mm and d1 was varied in order to evaluate the optimal value, d1 and maximum coupling efficiency were 0.24 mm and -0.35㏈, respectively. Then the results of experiment were corresponded to that of optimal simulation by cell modeling and it was possible to analyze the performance for optical device using thin film filter by the simulation.

• Asian-Australasian Journal of Animal Sciences
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• v.27 no.1
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• pp.69-76
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• 2014

This study was carried out to evaluate the relationship between threonine (Thr) efficiency and Thr dehydrogenase (TDG) activity as an indicator of Thr oxidation on chicks fed with levels of diets (CP [17.5% and 21.5%] and Thr [3.8 and 4.7 g/100 g CP]; glycine [Gly][0.64% and 0.98%] and true digestible Thr [dThr] [0.45% and 0.60%]). Calculation of the Thr efficiency was based on N-balance data and an exponential N-utilization model, and TDG activity was determined as accumulation of aminoacetone and Gly during incubation of hepatic mitochondria. This study found that in the liver of chicks who received a diet containing up to 0.79% Thr (4.7 g Thr/100 g of CP) in the 17.5% CP diet, no significant (p>0.05) effect on TDG activity was observed. However, significantly (p = 0.014) increased TDG activity was observed with a diet containing 21.5% CP (4.7 g Thr/100 g of CP) and the efficiency of Thr utilization showed a significant (p = 0.001) decrease, indicating the end of the Thr limiting range. No significant (p>0.05) effect on the total TDG activity and accumulation of Gly was observed with addition of Gly to a diet containing 0.45% dThr. In addition, addition of Gly to a diet containing 0.60% dThr also did not result in a change in accumulation of Gly. Due to an increase in accumulation of aminoacetone, an elevated effect on total TDG activity was also observed. No significant (p>0.05) reduction in the efficiency of Thr utilization was observed after addition of Gly at the level of 0.45% dThr. However, significantly (p<0.001) reduced efficiency of Thr utilization was observed after addition of Gly at the level of 0.60% dThr. Collectively, we found that TDG was stimulated not only by addition of Thr and protein to the diet, but also by addition of Gly, and efficiency of Thr utilization was favorably affected by addition of Gly at the level near to the optimal Thr concentration. In addition, no metabolic requirement of Gly through the TDG pathway was observed with almost the same accumulation of Gly and a slight increase in TDG activity by addition of Gly. Thus, our findings suggest that determination of TDG activity and parameter of efficiency of Thr utilization may be useful for evaluation of dietary Thr level.