• The Journal of the Korea Contents Association
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• v.15 no.3
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• pp.477-487
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• 2015

The purposes of this study was to analyze the relative efficiency of nineteen Jeju Self-Governing Schools (JSGS) in elementary level by using DEA (Data Envelopment Analysis). Major results from the study are as follows: First, there were significant differences on the relative efficiency among JSGS, which might come from operation factors rather than from size factors of JSGS. Second, to improve the relative inefficiency of JSGS, it is quite suggestive that satisfaction of both students and parents would be developed, and that the quality of educational programs should be developed by analyzing especially parents characteristics and reflecting their needs. Lastly, the perspective of efficiency, which is a measure of the optimal usage of available school resources, should be adopted and used for school assessment in order to develop the relative efficiency of JSGS.

• The Journal of the Korea Contents Association
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• v.11 no.5
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• pp.41-49
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• 2011

Recently, the infrastructure of stereoscopy is growing fast. Though, the stereoscopy producing capacity is insufficient to meet the demand of the market. Because, at the moment most people who produce the stereoscopy are skilled for the two-dimensional images. So the characteristics of the human stereopsis and stereoscopic cameras are not well considered, it occurs many problems to the viewer. According to this, we studied about the optical axis distance adjustment of stereoscopic camera considering size perception in human stereopsis. First, we measured the area of the object in the image which depends on the optical axis distance. Second, based on the output of first experiment, we conducted a survey and figured out that if we keep the optical axis distance between 3.9cm to 130cm, it wouldn't occur any size perception and will be possible to produce high quality stereoscopy.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.11C
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• pp.1098-1110
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• 2003

In this paper, we propose a homomorphic wavelet-based MMSE filter with edge detection to restore images degraded by speckle noise. In the proposed method, a noisy image is first transformed into logarithmic domain. Each pixel in the transformed image is then classified into flat and edge regions by applying DIP operator to the image restored by homomorphic directional MMSE filter. Each pixel in flat region is restored by homomorphic wavelet-based MMSE filter. Each pixel in edge region is restored by the weighted sum of the output of homomorphic wavelet-based MMSE filtering and that of homomorphic directional MMSE filtering. The restored image in spatial domain is finally obtained by applying the exponential function to the restored image in logarithmic domain. Experimental results show that the restored images by the proposed method have ISNR improvement of 3.3-4.0 ㏈ and ${\beta}$, a measurement parameter on edge preservation, improvement of 0.0103-0.0126 and superior subjective image quality over those by conventional methods.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.1
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• pp.20-26
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• 2016

This paper presents an X-band two-stage power amplifier using GaN-HEMT. Two-stage structure was adopted to take its high gain and simple inter-stage matching network. Based on a 3D EM simulation, the bond-wire inductance and the parasitic capacitance were predicted. By reducing bond-wire inductance, Q of the matching network is decreased and the bandwidth is improved. The implemented two-stage PA shows a power gain of more than 16 dB, saturated output power of more than 42.5 dBm, and a efficiency of more than 35 % in frequency range of 8.1~8.5 GHz with an operating voltage of 40 V.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.40 no.2
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• pp.51-59
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• 2017

Due to the rapid change of global business environment, the growth of China's steel industry and the inflow of cheap products, domestic steel industry is faced on downward trend. The change of business paradigms from a quantitative growth to a qualitative product is needed in this steel industry. In this environment, it is very important for domestic steel distribution companies to secure their competitiveness by selecting good supply companies through a efficient procurement strategy and effective method. This study tried to find out the success factors of steel distribution industry based on survey research from experts. Weighted values of each factors were found by using AHP (analytic hierarchy process) analysis. The weighted values were applied to DEA(data envelopment analysis) model and eventually the best steel supply company were selected. This paper used 29 domestic steel distribution firms for case example and 5 steps of decision process to select good vendors were suggested. This study used quality, price, delivery and finance as a selection criteria. Using this four criterions, nine variable were suggested. Which were product diversity, base price, discount, payment position, average delivery date, urgency order responsibility and financial condition. These variables were used as a output variable of DEA. Sales and facilities were used as an input variable. Pairwise comparison was conducted using these variables. The weighted value calculated by AHP pairwise comparison were used for DEA analysis. Through the analysis of DEA efficiency process, good DMU (decision making unit) were recommended as a steel supply company. The domestic case example was used to show the effectiveness of this study.

• Journal of the Korea Safety Management & Science
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• v.16 no.4
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• pp.71-80
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• 2014

This study is performed to determine the priorites of the evaluation factors for the improvement of fire emergency medical service by increasing it's efficiency to protect the people's lives effectively, and by recognizing it's mid-long term development. Based on the output of the analysis, the critical evaluation factors of the fire emergency medical services to be improved shall be identified, and shall be intended to use strategically for increasing the efficiency of all the activity in the EMT service, and also for providing the basic date to product and manage the good quality services. To calculate the priority of the evaluation factor for each level as shown on this study, AHP(anaysis hierarchy process) with pairwise comparison method is applied. According to the priority analysis for the evaluation factors in main category (evaluation zone), 'medical service professional aspect' is recognized as highest one, and 'service infrastructure aspect', 'service management aspect' are indicated in order. According to the priority analysis for the evaluation factors in evaluation index, 'professional personal arrangement' in the service infrastructure aspect, 'appropriateness and timeliness of emergency medical care' in the medical service professional aspect, and 'clinical training' in the service management aspect are respectively recognized as most important factors.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.8
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• pp.1024-1030
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• 2018

Recently, the large scaled energy storage system(ESS) which has various functions such as peak saving, demand management, output stabilization of renewable energy and frequency regulation(FR) is being energetically installed and operated. Especially, as the use case of frequency regulation ESS, the KEPCO has demonstrated the total of 376[MW] ESS since 2014. However, there are no operational experiences and international technical standards on frequency regulation application in ESS. Therefore, this paper propose the evaluation algorithm for power system performance of ESS by considering the frequency characteristics between governor of existing generator and frequency regulation ESS, in order to verify the power system performance of ESS. And also, this paper propose an evaluation modeling for small scaled power system including the existing generator, frequency control ESS and customer loads based on the PSCAD/EMTDC S/W. From the simulation results in 360[MW] model power system, it is confirmed that frequency regulation ESS has better performances than conventional generators.

• Korean Journal of Agricultural Science
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• v.25 no.2
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• pp.310-320
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• 1998

This study is aimed at identifying the socio-economic effects of storage of ginger in artificial caves. The gingers stored in artificial caves in Seochun, 12 sampled areas, were surveyed to get information on the socio-economic effects. The surveyed data were processed by TSP, Qbasic and B/C Ratio computer programs and analyzed the decision making criteria such as B/C ratio, NPV and IRR. The socio-economic effects of the storages of the gingers are as follows. 1. The storage benefits per ton was showed as 184,050won. 2. Considering 10% of the opportunity cost of capital, the uper limits of investments for the cave storages was analyzed as 6,784 thousand won for ginger. 3. The investment of the natural cave storages was revealed economically feasible considering the decision making criteria as B/C ratio = 1.33, NPV = 35.059 thousand won and IRR = more than 100%. The other socio-economic effects of the ginger storages was expected as ; 1. The cave storages will contribute to increase consumer's and producer's welfare through the control of supply and demand and price stability. 2. Long-term storage of ginger without damaging quality and grades will be made on account of the storage conditions as relatively low temperature, high humidity and indifferent affects from the outside climate. 3. Utilization of the underground space, the caves, for storage will maximize the land use and the sustainable environment considering the mountainous area, two third of the total national land area. 4. Construction costs of the underground storage facilities as caves are cheaper than the ground storage facilities by 15 to 20% in general. In conclusion, the underground space like natural and artificial caves are considered the most suitable for storage of ginger on account of the storage conditions as temperature, humidity and blocking the sun light. Accordingly a study on convenient utilization of new development of artificial caves should be made considering transportation and input-output of the farms. Financial support of the government should be institutionally rearranged for the successful implementation of storing farm products like ginger in natural and man-made caves.

• The Transactions of the Korean Institute of Power Electronics
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• v.23 no.2
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• pp.86-93
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• 2018

In this work, control methods and operating modes are proposed to manage standalone microgrid. A standalone microgrid generally consists of two sources, namely, battery energy storage system (BESS) and diesel generator (DG). BESS is the main source that supplies active and reactive power regardless of load conditions, whereas DG functions as an auxiliary power source. BESS operates in a constant voltage constant frequency (CVCF) control, which includes proportional-integral + resonant controller in a parallel structure. In CVCF control, the concept of fundamental positive and negative transformation is utilized to generate a three-phase sinusoidal voltage under imbalanced load condition. Operation modes of a standalone microgrid are divided into three modes, namely, normal, charge, and manual modes. To verify the standalone microgrid along with the proposed control methods, a demonstration site is constructed, which contains 115 kWh lead-acid battery bank, 50 kVA three-phase DC - AC inverter, and 50 kVA DG and controllable loads. In the CVCF control, the total harmonic distortion of output voltage is improved to 1.1% under imbalanced load. This work verifies that the standalone microgrid provides high-quality voltage, and three operation modes are performed from the experimental results.

• Journal of Korean Society for Geospatial Information Science
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• v.22 no.2
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• pp.11-16
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• 2014

GOSAT satellite $CO_2$ signal in years (June, 2009-December 2012) were compared with ground-based measurement at Anmyeon-do Korea Global Atmosphere Watch Center (KGAWC), located on the west coast of the Korean Peninsula. The result reveals that GOSAT signature is closely associated with ground-based measurement($R^2=0.49$). Strong correlation occurred between summer and fall ($R^2=0.62$) while weak relationship between satellite and ground-based measurement were identified in winter and spring ($R^2=0.37$). Average $CO_2$ concentration of GOSAT were 6.31 ppm lower than the corresponding values obtained from ground-based measurements on the same date. It is anticipated that this research output could be used as a valuable reference in introducing GOSAT to confirm data quality assurance for area-wide carbon monitoring process in relation to Anmyeon-do KGAWC $CO_2$ Concentration data.