• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.7 s.361
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• pp.54-61
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• 2007

A variable gain low noise amplifier (VG-LNA) implemented in TSMC 0.18 um process is presented. This VG-LNA is designed of two stage amplifier, and its gain is controlled by the shunt feedback loop composed of a gain control transistor (GCT) and a coupling capacitor in second stage. The channel resistance of GCT in the shunt feedback loop influences the input and output stages of a second stage by the Miller effect. Total gain of the proposed VG-LNA is changed by two factors, the load impedance reduction and the interstage mismatch by controlling the channel resistance of the GCT. Consequently, by adding a shunt feedback with a gain control transistor, this proposed VG-LNA achieves both wide gain tuning range of 37 dB and continuous gain control simultaneously.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.10C
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• pp.963-972
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• 2002

An 8192-point pipelined FFT/IFFT processor core is designed, which can be used in multi-carrier modulation systems such as DUf-based VDSL modem and OFDM-based DVB system. In order to improve the signal-to-quantization-noise ratio (SQNR) of FFT/IFFT results, two-step convergent block floating-point (TS_CBFP) scaling is employed. Since the proposed TS_CBFP scaling does not require additional buffer memory, it reduces memory as much as about 80% when compared with conventional CBFP methods, resulting in area-and power-efficient implementation. The SQNR of about 60-㏈ is achieved with 10-bit input, 14-bit internal data and twiddle factors, and 16-bit output. The core synthesized using 0.25-$\mu\textrm{m}$ CMOS library has about 76,300 gates, 390K bits RAM, and twiddle factor ROM of 39K bits. Simulation results show that it can safely operate up to 50-㎒ clock frequency at 2.5-V supply, resulting that a 8192-point FFT/IFFT can be computed every 164-${\mu}\textrm{s}$. It was verified by Xilinx FPGA implementation.

• The Transactions of the Korea Information Processing Society
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• v.6 no.9
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• pp.2403-2413
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• 1999

There is a strong need to develop a software cost estimation model on economic value perspective. The objective of this research is to improve current software cost estimation method on economic value perspective. We reviewed domestic and foreign researches and practices on software cost estimation with function point method, and derived promising alternative models. Pilot simulation was performed with real project data, and the probable best model was chosen. We collected data from 39 Korean companies, and assesed statistical significance of the model with those data. Empirical data shows that more practical model has better prediction accuracy. That is, the number of input and output modules, the number of tables, and the number of algorithms are chosen to be best set of functions. There exists strong correlation between the calculated function points and project effort. And, the revised set of technical complexity factors and evaluation guidelines show practical usefulness. We suggest that the above result be incorporated in a new improved guideline for software cost estimation. By adopting the results of this research to the guideline, we expect that technology innovation will be expedited, and that overall productivity of software industry will be increased.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.7
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• pp.2406-2419
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• 2010

This study aims to elevate the usefulness of the current annual Accreditation of Hospitals. To achieve this purpose, A modeling of an efficiency analysis based on DEA and AHP to the Accreditation of Hospitals Data from 2004 to 2008. By applying to AHP and DEA_AR to the scores derived from the various domains in data, An adequate prediction model about conversion factor in fee contract is made. By summarizing information derived from DEA, factor analysis and Generalized Linear Model, The linear functions combining conversion factor and efficiency index is successfully established. The factor analysis with AHP was used to merge diverse scores from the domains of evaluation. Not only the input and output initially introduced, AHP scores, dummy variables of hospital classification, geographical location are effective variables to forecast a conversion factor. If a predicted conversion factors from efficiency is used, It will be a great contributions to the annul doctor's fee contract.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.10
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• pp.19-26
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• 2021

In fine-particle injection processing, hard fine particles, such as silicon carbide or aluminum oxide, are injected - using high-pressure air, and a small amount of material is removed by applying an impact to the workpiece by spraying at high speeds. In this study, a two-axis stage device capable of sequence control was developed to spray various shapes, such as circles and squares, on the surface during the micro-particle jetting process to understand the surface-shape micro-particle-processing characteristics. In the experimental device, two stepper motors were used for the linear movement of the two degree-of-freedom mechanism. The signal output from the microcontroller is - converted into a signal with a current sufficient to drive the stepper motor. The stepper motor rotates precisely in synchronization with the pulse-signal input from the outside, eliminating the need for a separate rotation-angle sensor. The major factors of the processing conditions are fine particles (silicon carbide, aluminum oxide), injection pressure, nozzle diameter, feed rate, and number of injection cycles. They were identified using the ANOVA technique on the design of the experimental method. Based on this, the surface roughness of the spraying surface, surface depth of the spraying surface, and radius of the corner of the spraying surface were measured, and depending on the characteristics, the required spraying conditions were studied.

• Journal of Digital Convergence
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• v.19 no.5
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• pp.353-363
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• 2021

This study analyzed to provide information for business improvement by analyzing the management efficiency of start-up investment companies so that startup investment companies can operate efficiently and by presenting information on inefficient factors. From 2014 to 2018, 83 start-up investment companies were analyzed using the DEA model. Input variables were he number of employees, capital, and output variables were selected for start-up investment assets, operating income, and net profit. As a result of the analysis, technical efficiency and pure technical efficiency showed a pattern with an increase in average, but scale efficiency repeatedly increased and decreased. It is believed that the decline in technology efficiency was due to the decrease in pure technology efficiency, and the inefficiency of start-up investment companies seems to have influenced the inefficiency of start-up investment companies rather than the inefficiency of scale. In addition, the size revenue shows that the DRS value is gradually decreasing, and the IRS value is generally increasing. It is believed that efficiency can be improved if operational inefficiency is improved based on the results and efficiency measures are established through scale expansion.

• Korean Journal of Environmental Agriculture
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• v.38 no.3
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• pp.133-138
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• 2019

BACKGROUND: Production function gives the equation that shows the relationship between the quantities of productive factors used and the amount of product obtained, and can answer a variety of questions. This study was carried out to evaluate the relationship between irrigation water used for rice production and rice productivity by the production function which shows the mathematical relation between input and output. METHODS AND RESULTS: The statistical data on rice production and on the amount of irrigation water were used for the production function analysis. The analysis period was separated for 1966-1981 and 1982-2011, based on goal's change on agriculture from 'increasing food' to 'complex farming'. The relation between irrigation and yield considering production function is a short-term production function both before and after 1982. These results can be expressed by the sigmoid relation. When comparing the graphs of the two analyzed periods, there are differences in quantity between the maximum point and the minimum point during the same analysis period, which can be called an 'Irrigation Effect' by the difference of irrigation, and 'Technical Effect' by the difference by inputs like as fertilizers etc. CONCLUSION: The results could be useful as information for assessing the relationship between agricultural water and the productivity of rice and predicting rice productivity by irrigation water in Korea.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.36 no.5
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• pp.177-185
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• 2020

The building energy performance indicator, called Energy Performance Index (EPI), has been used for the past decades in South Korea. It has a list of design variables assigned with weighting factors (a, b). Unfortunately, the current EPI method is not performance-based but very close to a prescriptive rating. With this in mind, this study aims to propose a new performance-based EPI method. For this purpose, a global sensitivity analysis method, Sobol, is employed. The Sobol method is suitable for complex nonlinear models and can decompose all the output variance due to every input. The Sobol sensitivity index of each variable is defined as 0 to 1 (0 to 100%), and the sum of all sensitivity indices is equal to 1 (100%). In this study, an office building was modeled using EnergyPlus and then the Latin Hypercube Sampling (LHS) was conducted to generate a surrogate model to EnergyPlus. The sensitivity index was suggested to replace weight (a) in the existing EPI. In addition, the discrete weight (b) in the existing EPI was replaced by a set of continuous regression functions. Due to the introduction of the sensitivity index and the continuous regression functions, the new proposed approach can provide far more accurate outcome than the existing EPI (R²: 0.83 vs. R²: 0.01 for cooling, R²: 0.66 vs. R²: 0.01 for total energy). The new proposed approach proves to be more rational, objective and performance-based than the existing EPI method.

• Journal of East Asia Management
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• v.3 no.1
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• pp.11-23
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• 2022

Under the circumstances of China's slower economic growth, the first document ofthe central committee of the CPC continue to focus on "three agricultures" problems, agriculture play a basic role on China's economic. Since 2007, the first document directly stresses the important role of agricultural and fisheries every year. Central Government Working Report of 2015 also stresses that under the new normal of economy, it is important to improve quality and efficiency of agriculture. Agricultural focus going forward will be on improving capacity of competitiveness, innovation and sustainable development.The fishery as an important part of agriculture plays a vital role in the protection of national food security, the prosperity of the rural economy and the optimization of national food structure. However, the situation faced on accelerating the speed of Chinese fisheries is still grim. As an important fishery breeding city in my country, Weihai has achieved remarkable results in the development of fisheries. Based on the input-output indicators of Weihai City from 2010 to 2020, this article uses the DEA model method to conduct a comprehensive analysis of the factors affecting the fishery production efficiency in Weihai City. This paper calculates the two stages of comprehensive efficiency, pure technical efficiency and scale efficiency, and comprehensive compares the two stages. The research results show that: From 2010 to 2020, the average comprehensive technical efficiency of Weihai fishery was 0.928, the average scale efficiency was 0.963, and the average pure technical efficiency was 0.963. The comprehensive technical efficiency of Weihai fishery production showed an upward and downward trend, the pure technical efficiency showed a downward and then upward trend, and the pure technical efficiency showed a fluctuating trend.

• Journal of the Korea Society of Computer and Information
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• v.27 no.9
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• pp.225-234
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• 2022

Innovation is not only one of the factors determining the competitiveness of national regions, but also an engine for economic development, and plays an important role in breaking out of the trap of middle-income countries. This paper constructs a regional innovation index from the perspectives of innovation input, innovation output, and innovation environment, and measures the regional innovation index of 31 provinces, municipalities, and autonomous regions in China from 2006 to 2019 by using principal component analysis and cluster analysis. The results concluded that there are large provincial and municipal differences in China's regional innovation capacities, and the provinces with higher comprehensive levels are mainly concentrated in the southeastern coastal region. Cluster analysis divides the 31 provinces, municipalities, and autonomous regions into five types, and the results find that the respectively developed coastal regions are in the high-level and the high-level regions relying on the advantages of location and national policies.