• The Journal of the Korea institute of electronic communication sciences
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• v.5 no.5
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• pp.435-443
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• 2010

When testing systems that incorporate probabilistic behavior, it is necessary to apply test inputs a number of times in order to give a test verdict. Interval estimation can be used to assert the correctness of probabilities where the selection of confidence interval is one of the important issues for quality of testing. The Wald interval has been widely accepted for interval estimation. In this paper, we compare the Wald interval and the Agresti-Coull interval for various sizes of samples. The comparison is carried out based on the test pass probability of correct implementations and the test fail probability of incorrect implementations when these confidence intervals are used for probability testing. We consider two-sided confidence intervals to check if the probability is close to a given value. Also one-sided confidence intervals are considered in the comparison in order to check if the probability is not less than a given value. When testing probabilities using two-sided confidence intervals, we recommend the Agresti-Coull interval. For one-sided confidence intervals, the Agresti-Coull interval is recommended when the size of samples is large while either one of two confidence intervals can be used for small size samples.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.465-468
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• 2005

MMA(Multi-Modulus Algorithm) is inferior at a initial equalization in high ISI(intersymbol interference), because it is the inaccurate decision. To improve this probel SMMA(Sliced Multi-Modulus Algorithm) is based on using the MCMA(Modified Constant Modulus Algorithm). SMMA is a improved capability than MMA in high SNR but is inaccurate decision in low SNR. In this paper, We propose some multi-modulus blind equalization algorithm scheme. It is a method of operation in some multi-modulus algorithm which does no obstruct a convergence property at the initial equalization in the low SNR. Proposed algorithm improves the steady-state performance. And it uses residual ISI of the equalizer output in order to decide the optimum switching time between the single modulus and the multi-modulus algorithm.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.10C
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• pp.923-929
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• 2003

Turbo processing have been known as methods close to Shannon limit in the aspect of wireless multi-input multi-output (MIMO) communications similarly to wireless single antenna communication. The iterative processing can maximize the mutual effect of coding and interference cancellation, but LDPC coding has not been used for turbo processing because of the inherent decoding process delay. This paper suggests a LDPC coded MIMO system with turbo parallel space-time (Turbo-PAST) processing for high-speed wireless communications and proposes a average soft-output syndrome (ASS) check scheme at low signal to noise ratio (SNR) for the Turbo-PAST system to decide the reliability of decoded frame. Simulation results show that the suggested system outperforms conventional system and the proposed ASS scheme effectively reduces the amount of turbo processing iterations without performance degradation from the point of average number of iterations.

• The Journal of the Acoustical Society of Korea
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• v.25 no.2
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• pp.88-95
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• 2006

In this Paper. a method for improving the performance of automatic speech recognition (ASR) system for conversational speech is proposed. which mainly focuses on increasing the robustness against the rapidly speaking utterances. The proposed method doesn't require an additional speech recognition task to represent speaking rate quantitatively. Energy distribution for special bands is employed to detect the vowel regions, the number of vowels Per unit second is then computed as speaking rate. To improve the Performance for fast speech. in the pervious methods. a sequence of the feature vectors is expanded by a given scaling factor, which is computed by a ratio between the standard phoneme duration and the measured one. However, in the method proposed herein. utterances are classified by their speaking rates. and the scaling factor is determined individually for each class. In this procedure, a maximum likelihood criterion is employed. By the results from the ASR experiments devised for the 10-digits mobile phone number. it is confirmed that the overall error rate was reduced by $17.8\%$ when the proposed method is employed

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.6
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• pp.218-226
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• 2020

An experimental study was conducted on baseline model updating and damage estimation techniques for the health monitoring of offshore wind turbine tripod substructures. First, a procedure for substructure health monitoring was proposed. An initial baseline model for a scaled model of a tripod substructure was established. A baseline model was updated based on the natural frequencies and the mode shapes measured in the healthy state. A training pattern was then generated using the updated baseline model, and the damage was estimated by inputting the modal parameters measured in the damaged state into the trained neural network. The baseline model could be updated reasonably using the effective fixity model. The damage tests were performed, and the damage locations could be estimated reasonably. In addition, the estimated damage severity also increased as the actual damage severity increased. On the other hand, when the damage severity was relatively small, the corresponding damage location was detected, but it was more difficult to identify than the other cases. Further studies on small damage estimation and stiffness reduction quantification will be needed before the presented method can be used effectively for the health monitoring of tripod substructures.

• Journal of the Korean Society of Safety
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• v.25 no.6
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• pp.34-39
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• 2010

The purpose of this study is to suggest objective evaluation model as a plan to utilize as opportunity in establishing judgment standard of mutual inspection criteria and to upgrade inspection ability by reviewing and analyzing level of danger and importance in advance based on inspection results of inspection institutions regarding tower cranes used in construction fields. Tower crane is a mechanical device transporting construction supplies and heavy materials to places over 20~150M high from the ground for the period ranging from a short time of 2~3 months to two years after being installed in construction sites in vicinity of buildings or structures and is an important facility indispensable for construction sites. However, since use period after installation is short and professional technical ability of technicians working on-site about of tower crane is poor, systematic and quantitative safety management is not carried out As a part of researches on procedure of RBI(Risk Based Inspection) possible to apply to Knowledge Based System based on knowledge and experiences of experts as well as to tower cranes for solving these problems, quantitative RPN(Risk Priority Number) was applied to RPN utilizing technique of FMEA(Failure Mode and Effect Analyses). When general RBI 80/20 Rule was applied parts with high level of risks were found out as wire rope, hoist up/down safety device, reduction gear, and etc. However, since there are still many insufficient parts as risk analyses of tower crane were not established, it is necessary for experts with sufficient experiences and knowledge to supplement active RBI techniques and continuous researches on tower cranes by sharing and setting up data base of important information with this study as a starting point.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.12
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• pp.1032-1039
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• 2012

The present paper deals with precise relative positioning of formation satellites with long baseline in low Earth orbit making use of L1/L2 dual frequency GPS carrier phase measurements. Kinematic approach means to describe the motion of objects without taking its mass/dynamics model into consideration. The advantage of the kinematic approach is that information about dynamics of the system is not applied, which gives more flexibility and could improve the scientific interest of the observations made by the mission. The ionosphere terms, which are not canceled by double differenced measurement equation in the case of the long baseline, are explicitly estimated as unknown parameters by extended Kalman filter. The estimated float ambiguities by EKF are solved by existing efficient integer vector search strategy under integer least square condition. For the integer vector search, we employ well known MLAMBDA. Finally, The feasibility and accuracy of processing scheme are demonstrated using the GPS measurements for two satellites in low Earth orbit separated by baselines of 100 km.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.1
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• pp.105-114
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• 2019

Recently, the paradigm of road policy has been focused on user safety. Recently, the number of road facility improvement project has been continuously increased but the economic feasibility (B/C ratio) is insufficient. Therefore, it is necessary to select a reasonable road improvement project through accurate and objective analysis of the road safety evaluation. In this study, to develop a new road safety evaluation method, data were collected based on the current road safety evaluation method for 75 routes including national roads and provincial ones. Based on the collected data, problems were analyzed and utilized as the basic factors of the new road safety evaluation method. Therefore, in this study, traffic accidents were reflected as a general evaluation item by weighing to solve these problems, and the evaluation items were added from experiences and ideas of the local public officials. For each evaluation item, a reasonable weight was determined through AHP (Analytic Hierarchy Process) questionnaire evaluation with highway experts. In addition, the safety index was determined based on the evaluation criteria for each evaluation item. The criteria for evaluating the danger zone are determined by the overall safety index. Finally, the criteria for selection of road improvement projects based on the overall risk level were derived.

• Investigative Magnetic Resonance Imaging
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• v.11 no.1
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• pp.39-48
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• 2007

Purpose : To determine the diagnostic accuracy of four different sequences : moderately T2 weighted, two heavily T2-weighted single shot turbo spin-echo sequence and breath-hold axial-2D balanced turbo field-echo sequence(bFFE) for characterization of focal lesions. Materials and Methods : During the 3-month period between June and August 2005, seventy-six patients were proved to have ninety-three focal hepatic lesions on MR imaging. The patients consisted of 49 men and 27 women (age range, 15-75 years; mean age, 56.23 years). All MR images were acquired on a 1.5-T MR using the following sequences: 1. A breath-hold axial T2-weighted single shot turbo spin-echo sequence, 2. a breath-hold axial-2D balanced turbo field-echo sequence. Two radiologists performed quantitative analysis. Another radiologist measured the lesion-to-liver contrast-to-noise ratio at the region-of-interest in the four sequences. Results : There was no significant difference in inter-observer variability between the four sequences. The accuracy for both cyst and malignancy of moderate T2 weighted MRI (echo time: 80 msec) was also highest. There was significant difference for lesion characterization between moderate T2 weighted MRI and balanced steady state procession (p-value: 0.004) in the second reader. For longer echo time, the CNR of cystic lesions were markedly increased in comparison to lesions of other component. Conclusion : The accuracy and inter-observer variability of single shot turbo spin echo T2 weighted sequence was higher than bFFE. Although there was no statically significant difference, moderate T2 weighted MRI (echo time: 80 msec) was more accurate than heavily T2 weighted sequence (echo time: 300 msec). If the results for lesion characterization is equivocal in TE 80, the addition of heavily T2 weighted MRI (echo time: 180 msec) can be helpful.

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.5
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• pp.910-916
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• 2002

As the utilization of medicinal herbs in food and bio-industry increases, safe hygienic technologies for them are demanded. To consider the possibility of application of radiation technology for this purpose, the genotoxi-cological safety of three r -irradiated medicinal herbs were studied. Astragali Radix, Atractylodes Rhizoma and Cimicifugae Rhizoma were irradiated at 10 kGy, and then were extracted with hot water. The genotoxicity of the extracts was examined in two short-term in vitro tests: (1) Salmonella reversion assay (Ames test) in strains of TA98 and TA100; (2) Micronucleus test in cultured Chinese hamster ovary (CHO) cells. The extract was treated at maximum doses of 5 mg/plate in Salmonella reversion assay, and 1 mg/mL in micronucleus test where growth of CHO cells was inhibited by 50%. In Salmonella reversion assay with or without metabolic activation, both ex-tracts of irradiated and non-irradiated herbs showed no significant differences in formation of revertant colonies compared with the negative control. And also in micronucleus test, the incidences of micronucleus in CHO cells cultured with extracts of irradiated herbs were almost same as negative control in less than 3%. These results of two in vitro tests suggest that ${\gamma}$-irradiated herbs do not show mutagenicity and cytogenetic toxicity. Further tests of in vivo genotoxicity and chronic toxicity are needed to ascertain the safety of ${\gamma}$-irradiated herbs.