• Communications for Statistical Applications and Methods
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• v.10 no.3
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• pp.1069-1086
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• 2003

This article presents the asymptotic theory of triple sampling procedure as pertain to estimating the shape parameter of Pareto distribution. Both point and confidence interval estimation are considered within the same inference unified framework. We show that this group sampling technique possesses the efficiency of Anscome (1953), Chow and Robbins (1965) purely sequential procedure as well as reduce the number of sampling operations by utilizing Stein (1945) two stages procedure. The analysis reveals that the technique performs excellent as far as the accuracy is concerned. The present problem differs from those considered by many authors, in multistage sampling, in that the final stage sample size and the parameter's estimate become highly correlated and therefore we adopted different approach.

• Nuclear Engineering and Technology
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• v.54 no.10
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• pp.3620-3630
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• 2022

The diagnosis of abnormalities in a nuclear power plant is essential to maintain power plant safety. When an abnormal event occurs, the operator diagnoses the event and selects the appropriate abnormal operating procedures and sub-procedures to implement the necessary measures. To support this, abnormality diagnosis systems using data-driven methods such as artificial neural networks and convolutional neural networks have been developed. However, data-driven models cannot always guarantee an accurate diagnosis because they cannot simulate all possible abnormal events. Therefore, abnormality diagnosis systems should be able to detect their own potential misdiagnosis. This paper proposes a rulebased diagnostic validation algorithm using a previously developed two-stage diagnosis model in abnormal situations. We analyzed the diagnostic results of the sub-procedure stage when the first diagnostic results were inaccurate and derived a rule to filter the inconsistent sub-procedure diagnostic results, which may be inaccurate diagnoses. In a case study, two abnormality diagnosis models were built using gated recurrent units and long short-term memory cells, and consistency checks on the diagnostic results from both models were performed to detect any inconsistencies. Based on this, a re-diagnosis was performed to select the label of the second-best value in the first diagnosis, after which the diagnosis accuracy increased. That is, the model proposed in this study made it possible to detect diagnostic failures by the developed consistency check of the sub-procedure diagnostic results. The consistency check process has the advantage that the operator can review the results and increase the diagnosis success rate by performing additional re-diagnoses. The developed model is expected to have increased applicability as an operator support system in terms of selecting the appropriate AOPs and sub-procedures with re-diagnosis, thereby further increasing abnormal event diagnostic accuracy.

• The Journal of the Korean dental association
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• v.55 no.1
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• pp.30-41
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• 2017

Inadequate keratinized mucosa around dental implants can lead to more plaque accumulation, tissue inflammation, marginal recession and attachment loss. We evaluated the effects of free gingival and extracellular matrix membrane grafts performed to increase the insufficient width of keratinized tissue around dental implants in the posterior mandible. A 47-year-old female patient presented with discomfort due to swelling of the lower right second premolar area. Due to severe destruction of alveolar bone, the tooth was extracted. After 3 months, a guided bone regeneration (GBR) procedure was performed and then a dental implant was placed 6 months later. During the second-stage implant surgery, free gingival grafting was performed to increase the width of the keratinized tissue. After 12 months, a clinical evaluation was performed. A 64-year-old female patient had a missing tooth area of bilateral lower molar region with narrow zone of keratinized gingiva and horizontal alveolar bone loss. Simultaneous implant placement and GBR were performed. Five months after the first-stage implant surgery, a gingival augmentation procedure was performed with an extracellular matrix membrane graft to improve the width of the keratinized tissue in the second-stage implant surgery. After 12 months, a clinical evaluation was performed. In these two clinical cases, 12 months of follow-up, revealed that the increased width of the keratinized tissue and the deepened oral vestibule was well maintained. A patient showed a good oral hygiene status. In conclusion, increased width of keratinized tissue around dental implants could improve oral hygiene and could have positive effects on the long-term stability and survival rate of dental implants. When planning a keratinized tissue augmentation procedure, clinicians should consider patient-reported outcomes.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.5
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• pp.138-151
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• 1996

This paper proposes a genetic fuzzy controller ensemble (FCE) for improving the control performance of of fuzzy controller in the non-linear and complex problems. The design procedure of each fuzzy controller in the FCF consists of the following two stages, each of which is performed by different genetic algorithms. The first stage generates a fuzzy rule base that covers the training examples as many as possible. The second stage builds fine-tuned membership funcitons that make the control error as small as possible. These two stages are repeated independently upon the different partition patterns of input-output variables. The control performance of the proposed method is compared with that of wang and mendel's approach[1] in terms of either the percentage of successful controls reaching to the goal or the average traveling distance.

• Journal of Korean Institute of Industrial Engineers
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• v.17 no.1
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• pp.29-35
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• 1991

This paper deals with a production-inventory model for two-stage batch production system. We propose a lot-sizing scheme which combines the integer multiple lot requirements (IMLR) policy and the integer split lot requirements (ISLR) policy. An iterative search procedure for optimal decision variables is presented and numerical examples are solved to illustrate the validity of the model. The results show that the proposed scheme outperforms the existing policies.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.66.2-66
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• 2002

In this study, a novel systematic design procedure by Genetic Algorithm of a two stage relief valve is proposed. First of all, a mathematical model describing the dynamics of a balanced piston type relief valve has been derived. Governing equations such as dynamic equations for the main spool and the pilot spool and flow equations for each orifice are established. The mathematical model is verified by comparing the results of simulation with that of experiments. Furthermore, influences of the parameters on the dynamic characteristics of a relief valve have been investigated by simulation of the proposed model. Major design parameters on the valve response are determin...

• International Journal of Reliability and Applications
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• v.12 no.1
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• pp.61-77
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• 2011

One of the most important problems in the estimation of the parameter of the failure model, is the cost of experimental sampling units, which can be reduced by using any prior information available about ${\theta}$, and devising a two-stage pooling shrunken estimation procedure. We have proposed an estimator of the reliability function (R(t)) of the exponential model using two-stage time censored data when a prior value about the unknown parameter (${\theta}$) is available from the past. To compare the performance of the proposed estimator with the classical estimator, computer intensive calculations for bias, mean squared error, relative efficiency, expected sample size and percentage of the overall sample size saved expressions, were done for varying the constants involved in the proposed estimator (${\tilde{R}}$(t)).

• Journal of Chest Surgery
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• v.21 no.1
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• pp.101-108
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• 1988

Between July, 19S4. and July, 1987, 9 two-stage repair of symptomatic tetralogy of Fallot were carried out at the department of thoracic and cardiovascular surgery, Kyungpook national university hospital. Their age ranged from 5 years to 18 years [mean age 9.4 years] at the time of total correction, and there were improvement of systemic oxygen saturation values by 10% and decrease of hemoglobin by 1.6gm/dl after shunt procedures. The interval between the initial shunting procedure and total correction ranged for 7 to 101 months with a mean of 32.7 months. Four of these patients required patching of the infundibulum alone, three required patching of the right ventricular outflow tract across the pulmonary annulus, and valved conduit was used in one due to coronary artery anomaly. Aortic cross clamping time averaged 122.2minutes [range from 60minutes to 150minutes], and cardiopulmonary bypass time averaged 174.4 minutes [range from 80minutes to 300minutes]. The operative mortality rate was 22% [2/9].

• Archives of Reconstructive Microsurgery
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• v.8 no.1
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• pp.50-55
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• 1999

Avascular necrosis is a significant late complication of talar neck fracture. However, treatment for early stage avascular necrosis has been not established. Two patients with post-traumatic avascular necrosis of talus treated with vascular pedicle graft using lateral tarsal artery were reviewed to determine the efficacy of procedure. The procedure involved grafting the lateral tarsal artery and vein into a hole made in the talus through a anterolateral approach. Follow-up was 12 and 24 months respectively. Two patients had significant pain relief, improved function, no worsening of their radiologic staging. The results are promising enough to recommend consideration of this procedure in early stages of avascular necrosis.

• The Transactions of the Korean Institute of Power Electronics
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• v.24 no.4
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• pp.268-272
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• 2019

A lithium polymer battery-based 9 kJ/s high-voltage capacitor charger, which comprises two stages, is proposed. A modified LCC resonant converter and resonant circuit are introduced at the first and second stages, respectively. In the first stage, the methods for handling low-voltage and high-current batteries are considered. Delta-wye three-phase transformers are used to generate a high output voltage through the difference between the phase and line-to-line voltages. Another method is placing the series resonant capacitor of the LCC resonant components on the transformer secondary side, which conducts considerably low current compared with the transformer primary side. On the basis of the stable operation of the first charging stage, the secondary charging stage generates final output voltage by using the resonance. This additional stage protects the rectifying diodes from the negative voltage when the output capacitor is discharged for a short time. The inductance and capacitance of the resonance components are selected by considering the resonance charging time. The design procedure for each stage with the aforementioned features is suggested, and its performance is verified by not only simulation but also experimental results.