• Journal of Power Electronics
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• v.8 no.4
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• pp.317-324
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• 2008

This paper proposes a Multiband Shunt Hybrid Active Filter (SHAF) with sensorless control. A plant is modeled in the discrete- time domain and a controller is designed using the Pole shifting law in the polynomial domain. This control approach is very useful for filtering the load harmonics with reduced sensor counts where a low cost solution like SHAF is required. Multiple Synchronous Reference Frames (MSRF) and low pass filters are used to measure the $5^{th}$ and $7^{th}$ harmonic components separately from the load and filter currents. Individual current controllers are designed for the $5^{th}$ and $7^{th}$ harmonic currents. Control is realized in the stationary, three-phase (abc) reference frame. Performance of the controller is validated through simulation, using realistic plant and controller models, as well as experimentally on a full-scale distribution system.

• ETRI Journal
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• v.23 no.3
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• pp.129-137
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• 2001

A random sampling or systematic sampling method is commonly used to assess the accuracy of classification results. In remote sensing, with these sampling methods, much time and tedious work are required to acquire sufficient ground truth data. So, a more effective sampling method that can represent the characteristics of the population is required. In this study, fractal analysis is adopted as an index for reference sampling. The fractal dimensions of the whole study area and the sub-regions are calculated to select sub-regions that have the most similar dimensionality to that of the whole area. Then the whole area's classification accuracy is compared with those of sub-regions, and it is verified that the accuracies of selected sub-regions are similar to that of whole area. A new kind of reference sampling method using the above procedure is proposed. The results show that it is possible to reduce sampling area and sample size, while keeping the same level of accuracy as the existing methods.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.34C no.2
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• pp.71-79
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• 1997

In this paper, we propose a new nearest-neighbor classifier with reduced computational complexity in search process. In the proposed classifier, the classes are divided into two sets: reference and non-reference sets. It reduces computational requriement by approximating the distance between the input and a class iwth the information of distances among the calsses. It calculates only the distance between the input and the reference classes. We convert a given classifier into RCC (reduced computational complexity but smal lincrease in misclassification probability of its corresponding RCC classifier. We designed RCC classifiers for the recognition of digits from the NIST database. We obtained an RCC classifier with 60% reduction in the computational complexity with the cost of 0.5% increase in misclassification probability.

• International Journal of Aeronautical and Space Sciences
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• v.18 no.3
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• pp.555-564
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• 2017

In this paper, a new technique for attitude and heading reference system (AHRS) using low-cost MEMS sensors of the gyroscope, accelerometer, and magnetometer is addressed particularly in vibration environments. The motion of MEMS sensors interact with the scale factor and cross-coupling errors to produce random errors by the harsh environment. A new adaptive attitude estimation algorithm based on the Kalman filter is developed to overcome these undesirable side effects by analyzing windowed measurement error covariance. The key idea is that performance degradation of accelerometers, for example, due to linear vibrations can be reduced by the proposed measurement error covariance analysis. The computed error covariance is utilized to the measurement covariance of Kalman filters adaptively. Finally, the proposed approach is verified by using numerical simulations and experiments in an acceleration phase and/or vibrating environments.

• Journal of Information Management
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• v.33 no.2
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• pp.33-48
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• 2002

This paper describes evaluation methods of serials and also introduces a case study related to the selection and evaluation of serials. A total of 1,291 titles of serials, which were subscription titles of POSTECH in the field of science and technology in 2002, were analyzed. This study employs the analysis of POSTECH SCI Article reference data to suggest the models for evaluating serials and to identify the guideline for journal selection and collection development.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.4
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• pp.109-119
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• 2004

Rapid prototyping (RP) technologies have been widely used to reduce the lead-time and development cost of new products. $VLM-_{ST}$ process has been developed to overcome the currently developed RP technologies such as a large building time, a high building cost, an additional post-processing and a large apparatus cost. $VLM-_{ST}$ process requires an additional human interaction due to the manual stacking and bonding. Hence, building time, building cost and the part quality are dependent on the skill of labor. A novel RP process, fully automated $VLM-_{ST}$ process ($VLM-_{ST}$), has been developed to improve building efficiency of the process and the human dependency of the part. The objective of this work is to propose a $VLM-_{ST}$ process and to develop an apparatus for implementation of the process. $VLM-_{ST}$ process and its apparatus have various technical novelties such as two step cutting using a rotating table, an automatic stacking method using two pilot holes and two reference shapes, a concept of automatic unit shape layer (AUSL), and an automatic bonding using the bonding roller and building magazine. In order to examine the efficiency and the applicability of the proposed process, various three-dimensional shapes, such as a piston, a human head shape and a human bust shape, were fabricated on the apparatus.

• Journal of Korean Society of Forest Science
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• v.101 no.4
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• pp.729-736
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• 2012

Korea Forest Service is recently focused on forest tending works for promoting in green jobs. The purpose of forest tending work is not only maintaining ecologically stable forest stand structure but also developing commercial forest. These trends are also emphasized by creation of various benefits and expanding carbon absorption in forest management. For achieving these purposes, Management efficiency of output was analized by the inputs such as labor cost, material cost and expense cost using DEA technique. The results show that, 19 sub-compartments are appeared to be the optimal in the efficiency of the forest tending works among total 52 sub-compartments. Among those there were 5 sub-compartment 8-0-3, 9-3-3, 6-0-3, 7-0-6, 1-0-5 and 3-0-3 to be considered in the high reference. The high reference areas mean those areas which is well accomplished in forest tending works as the desirable model.

• KIEAE Journal
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• v.14 no.5
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• pp.21-28
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• 2014

To improve environmental problem as globally climate changes, domestic and foreign government have been trying to reduce green gas emitted by all industries. With making the green building certification system that assess the substantiality and energy performance of building, a governments have been using by a way for reducing green gas emitted in building industry. G-SEED(Green Standard for Energy & Environmental Design) developed in Korea have been reinforcing, and a number of projects certifying the G-SEED have been increasing continuously. As a demand of G-SEED certification is rising, a question on the additional cost data as certifying G-SEED is rising. It is because additional cost as getting the certification is important fact for G-SEED level decision and whether getting the certification or not. Therefore, this study analyzed additional construction cost as certifying G-SEED through performance improvement and design change of general office building not to get G-SEED. In conclusion, an additional construction cost ratio of G-SEED projects to the reference building is drawn as certified level; +0.26%, silver level; +2.29%, gold level; +3.89%, and platinum level; +5.48%.

• Journal of Nutrition and Health
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• v.36 no.5
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• pp.515-527
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• 2003

Objectives： A meta-analysis of the literatures was conducted to evaluate the cost-effectiveness of medical nutrition therapy by dietitians. Methods : The 30 studies were identified from a computerized search of published research on MEDLINE, Science-Direct and the PQD database until May, 2002 and a review of reference lists. The main search terms were“dietitian”,“dietary intervention”,“nutrition intervention”, “cost”,“cost-effectiveness”and“cost-benefit analysis”. The subgroup analysis was performed by publication year, study design, intervention provider, type of patient (in/out-patient) and type of cost (total cost/direct cost). Two reviewers independently selected trials for inclusion, assessed the quality and extracted the data. Results : The 30 studies were identified using the electric database search and bibliographies. The 17 trials were eligible for inclusion criteria, then the systematic review and a meta-analysis were conducted on effectiveness and cost-effectiveness of medical nutrition therapy. The quality of the studies was evaluated using the quality assessment tool for observational studies. The quality score was 0.515 $\pm$ 0.121 (range : 0.279-0.711, median : 0.466). The meta-analysis of 17 studies based on the random effect model showed that medical nutrition therapy was highly effective in treating the diseases (effect size 0.3092 : 95% confidence interval 0.2282-0.3303). The vote-counting method, one of meta-analysis methods, was applied to evaluate the cost-effectiveness of medical nutrition therapy conducted by dietitians. Two criteria (method 1, method 2) for voting were used. The calculated p-values for method 1 (more conservative method) and method 2 (less conservative method) were 0.1250 and 0.0106, respectively. Medical nutrition therapy by dietitians was significantly cost-effective in the method 2. Conclusion. This meta-analysis showed that the effectiveness of medical nutrition therapy was statistically significant in treating disease (effect size 0.3092), and that the cost-effectiveness of medical nutrition therapy was statistically significant in the method 2 (less conservative method) of vote counting. (Korean J Nutrition 36(5): 515~527, 2003)

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.3
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• pp.645-650
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• 2015

Image restoration is required when the image is blurred due to out of focus or motion during the image acquisition. This type of image restoration is known as ill-posed inverse problem because the estimate of an original image should be derived from only one blurred image. This paper introduces a reference image to facilitate the restoration process. The experimental result shows that computation time is significantly reduced, compared with other methods. The proposed method obtains the estimate of the kernel used in blurring processing. New cost function is defined to update both the image and the kernel alternately. In the last stage, Wiener filter produces the estimate of an original image using the kernel and the reference image.