• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.17 no.2
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• pp.111-114
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• 2006

Objective : The anterior approach to the cervical spine now selves as the surgical across of choice for cervical spine disease. Vocal cord paryalysis(VCP) follow the procedure as a complication, and it is most common complication of this procedure. However, the frequency and etiology of this injury are not clearly defined. This study was performed to establish the clinical features of vocal cord paralysis in anterior cervical spine surgery(ACSS). Material and Method : Retrospectively, medical records of patients who underwent ACSS at Hallym university medical center, Hangang Sacred Heart Hospital between January 2000 and March 2006 were reviewed. Further detailed review of the patients with documented VCP after surgery was then performed. Results : 242 ACSSs were performed and 9 patients with VCP were identified (3.71%) In 9 patients with VCP, 8 patients had right-sided approaches (6.01%) and 1 patient had left-sided approach (0.91%). All 9 patients had VCP on ipsilateral side and 8 patients were recovered completely on follow up period. Duration of ACSS, multilevel exposure and low-level (below the C6 level) exposure have been found to be associated with higher risk. Conclusion : For avoiding the recurrent laryngeal nerve injury, surgeon have to understand the clinical features of VCP in ACSS. As right-sided approach has a greater risk of recurrent laryngeal nerve injury, we suggest that the left-sided approach be given more consideration.

• Journal of Korean Society of Steel Construction
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• v.16 no.1 s.68
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• pp.123-134
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• 2004

In this research, a multilevel decomposition technique to enhance the efficiency of the configuration optimization of truss structures was proposed. On the first level, the nonlinear programming problem was formulated considering cross-sectional areas as design variables, weight, or volume as objective function and behavior under multiloading condition as design constraint. Said nonlinear programming problem was transformed into a sequential linear programming problem. which was effective in calculation through the approximation of member forces using behavior space approach. Such approach has proven to be efficient in sensitivity analysis and different form existing shape optimization studies. The modified method of feasible direction (MMFD) was used for the optimization process. On the second level, by treating only shape design variables, the optimum problem was transformed into and unconstrained optimal design problem. A unidirectional search technique was used. As numerical examples, some truss structures were applied to illustrate the applicability. and validity of the formulated algorithm.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.12 no.3
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• pp.397-406
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• 1999

A new solution procedure for approximate reanalysis, using the staged hybrid methods with substructuring, is proposed in this study. Displacements are calculated with two step mixed procedures. First step is to introduce the conservative approximation, which is a hybrid form of the linear and reciprocal approximation, as local approximation. In the next step, it is combined with the global approximation by reduced basis approach. Stresses are evaluated from the displacements by matrix transformation. The quality of reanalyzed quantities can be greatly improved through these staged hybrid approximations, specially for large changes in the design. Overall procedures are based on substructuring scheme. Several numerical examples illustrate the validity and effectiveness of the proposed methods.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2005.04a
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• pp.663-671
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• 2005

Distributed operation of overall structural design process, by which product and process optimization are implemented, is presented in this paper. The database-interconnected multilevel hybrid method, in which the conventional design method and the optimal design approach are combined, is utilized there. The method selectively takes the accustomed procedure of the conventional method in the conceptional framework of the optimal design. Design conditions are divided into primary and secondary criteria This staged application of design conditions reduces the computational burden for large complex optimization problems. Two kinds of numeric and graphic processes, are simultaneously implemented on the basis of concurrent engineering concepts in the distributed environment of PC networks. Numerical computation on server and graphic works on independent client are communicated through message passing. Numerical design is based on the optimization methodology and the drawing process is carried out by AutoCAD using the AutoLISP programming language. The prototype design experimentation for some steel trusses shows the validity and usability of the method. This study has sufficient adaptability and expandability in methodology, in that it is based on general theory and industry standard systems.

• Journal of Korean Neurosurgical Society
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• v.49 no.5
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• pp.308-313
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• 2011

Posterior cervical foraminotomy is an attractive therapeutic option in selected cases of cervical radiculopathy that maintains cervical range of motion and minimize adjacent-segment degeneration. The focus of this procedure is to preserve as much of the facet as possible with decompression. Posterior cervical inclinatory foraminotomy (PCIF) is a new technique developed to offer excellent results by inclinatory decompression with minimal facet resection. The highlight of our PCIF technique is the use of inclinatory drilling out for preserving more of facet joint. The operative indications are radiculopathy from cervical foraminal stenosis (single or multilevel) with persistent or recurrent root symptoms. The PCIFs were performed between April 2007 and December 2009 on 26 male and 8 female patients with a total of 55 spinal levels. Complete and partial improvement in radiculopathic pain were seen in 26 patients (76%), and 8 patients (24%), respectively, with preserving more of facet joint. We believe that PCIF allows for preserving more of the facet joint and capsule when decompressing cervical foraminal stenosis due to spondylosis. We suggest that our PCIF technique can be an effective alternative surgical approach in the management of cervical spondylotic radiculopathy.

• Communications for Statistical Applications and Methods
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• v.25 no.2
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• pp.173-184
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• 2018

In medical or public health research, it is common to encounter clustered or longitudinal count data that exhibit excess zeros. For example, health care utilization data often have a multi-modal distribution with excess zeroes as well as a multilevel structure where patients are nested within physicians and hospitals. To analyze this type of data, zero-inflated count models with mixed effects have been developed where a count response variable is assumed to be distributed as a mixture of a Poisson or negative binomial and a distribution with a point mass of zeros that include random effects. However, no study has considered a situation where data are also censored due to the finite nature of the observation period or follow-up. In this paper, we present a weighted version of zero-inflated Poisson model with random effects accounting for variable individual follow-up times. We suggested two different types of weight function. The performance of the proposed model is evaluated and compared to a standard zero-inflated mixed model through simulation studies. This approach is then applied to Medicaid data analysis.

• Journal of Power Electronics
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• v.12 no.2
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• pp.344-356
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• 2012

In recent years, multilevel technology has become an effective and practical solution in the field of moderate and high voltage applications. This paper discusses an APF with a three-level NPC inverter. Obviously, the application of such converter to APFs is hindered by the problem of the voltage unbalance of DC capacitors, which leads to system instability. This paper comprehensively analyzes the theoretical limitations of the neutral-point voltage balancing problem for tracking different harmonic currents utilizing current switching functions from the space vector PWM (SVPWM) point of view. The fluctuation of the neutral point caused by the load currents of certain order harmonic frequency is reported and quantified. Furthermore, this paper presents a close-loop digital control algorithm of the DC voltage for this APF. A PI controller regulates the DC voltage in the outer-loop controller. In the current-loop controller, this paper proposes a simple neutral-point voltage control method. The neutral-point voltage imbalance is restrained by selecting small vectors that will move the neutral-point voltage in the direction opposite the direction of the unbalance. The experiment results illustrate that the performance of the proposed approach is satisfactory.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.12
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• pp.5888-5903
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• 2019

The Relational ranking method applies authority-based ranking in relational dataset that can be modeled as graphs considering also their tuples' values. Authority directions from tuples that contain the given keywords and transfer to their corresponding neighboring nodes in accordance with their values and semantic connections. From our previous work, ObjectRank extends to ValueRank that also takes into account the value of tuples in authority transfer flows. In a maked difference from ObjectRank, which only considers authority flows through relationships, it is only valid in the bibliographic databases e.g. DBLP dataset, ValueRank facilitates the estimation of importance for any databases, e.g. trading databases, etc. A relational keyword search paradigm Object Summary (denote as OS) is proposed recently, given a set of keywords, a group of Object Summaries as its query result. An OS is a multilevel-tree data structure, in which node (namely the tuple with keywords) is OS's root node, and the surrounding nodes are the summary of all data on the graph. But, some of these trees have a very large in total number of tuples, size-l OSs are the OS snippets, have also been investigated using ValueRank.We evaluated the real bibliographical dataset and Microsoft business databases to verify of our proposed approach.

• Journal of Digital Contents Society
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• v.14 no.2
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• pp.143-149
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• 2013

Many researchers and developers take a greater interest on the LOD AI techniques as users demand more elaborate and sophisticated game AI in recent years. However, contrary to the traditional geometry LOD, existing LOD AI techniques can be used only to a limited extent. Therefore, in this paper, I propose an LOD AI technique, which uses HSM(Hierarchical State Machine) and the Lua script language as the method to control game objects. Using the proposed approach, we can easily produce multilevel AI models for LOD and design various objects without hard-coding state machines. Moreover, in order to show the effectiveness of the presented technique, this paper exemplifies the results of the efficiency test through the prototype engine.

• International Journal of Naval Architecture and Ocean Engineering
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• v.8 no.4
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• pp.344-359
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• 2016

Due to the increasing occurrence of maritime accidents and high-level requirements and modernization of naval wars, the concept of ship environment adaptability becomes more and more important. Therefore, it is of great importance to carry out an evaluation system for ship environment adaptability, which contributes to both ship design and classification. This paper develops a comprehensive evaluation system for ship environment adaptability based on fuzzy mathematics theory. An evaluation index system for ship environment adaptability is elaborately summarized first. Then the analytic hierarchy process (AHP) and entropy weighting methods are applied to aggregate the evaluations of criteria weights for each criterion and the corresponding subcriteria. Next, the multilevel fuzzy comprehensive evaluation method is applied to assess the ship integrative environment adaptability. Finally, in order to verify the proposed approach, an illustrative example for optimization and evaluation of five ship alternatives is adopted. Moreover, the influence of criteria weights, membership functions and fuzzy operators on the results is also analyzed.