• 한국국방경영분석학회지
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• 제28권1호
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• pp.47-66
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• 2002

Instead of using signal-to-noise ratio, we attempt to optimize both the mean and variance responses using dual response optimization technique. The alternative experimental strategy analyzes a robust parameter design problem to obtain the best settings that give a target condition on the mean while minimizing its variance. The mean and variance are treated as the two responses of interest to be optimized. Unlike to the crossed array and combined array approaches, our experimental setup requires replicated runs for each control factor's treatment under noise sampling. When the postulated response models are true, they enable the coefficients to be estimated and the desired performance measure to be analyzed more efficiently. The procedure and illustrative example are given for the dual response optimization techniques of nonlinear goal programming.

• 대한청각학회지
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• 제25권2호
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• pp.110-114
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• 2021

We report a case of hearing rehabilitation following combined cochlear implantation and ossiculoplasty. A 71-year-old patient visited the clinic for right-sided mixed hearing loss. We targeted neural and conductive components, performing two different operations simultaneously. At two months post-operative, the patient showed satisfactory results with respect to hearing threshold and speech comprehension. Our experience suggests that careful evaluation of patients and consideration of the diverse array of available treatment strategies can be used to provide personalized rehabilitation with maximal effectiveness. To the best of our knowledge, this is the first report to take such an integrated approach to treat hearing impairment and is thus likely to have clinical importance for otologists.

• Journal of Audiology & Otology
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• 제25권2호
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• pp.110-114
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• 2021

We report a case of hearing rehabilitation following combined cochlear implantation and ossiculoplasty. A 71-year-old patient visited the clinic for right-sided mixed hearing loss. We targeted neural and conductive components, performing two different operations simultaneously. At two months post-operative, the patient showed satisfactory results with respect to hearing threshold and speech comprehension. Our experience suggests that careful evaluation of patients and consideration of the diverse array of available treatment strategies can be used to provide personalized rehabilitation with maximal effectiveness. To the best of our knowledge, this is the first report to take such an integrated approach to treat hearing impairment and is thus likely to have clinical importance for otologists.

• Journal of Mechanical Science and Technology
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• 제18권2호
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• pp.230-239
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• 2004

A compact model approach of a network of spring elements for elastic loading is presented for the thermal deformation analysis of BGA package assembly. High-sensitivity moire interferometry is applied to evaluate and calibrated the model quantitatively. Two ball grid array (BGA) package assemblies are employed for moire experiments. For a package assembly with a small global bending, the spring model can predict the boundary conditions of the critical solder ball excellently well. For a package assembly with a large global bending, however, the relative displacements determined by spring model agree well with that by experiment after accounting for the rigid-body rotation. The shear strain results of the FEM with the input from the calibrated compact spring model agree reasonably well with the experimental data. The results imply that the combined approach of the compact spring model and the local FE analysis is an effective way to predict strains and stresses and to determine solder damage of the critical solder ball.

• 한국정밀공학회지
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• 제18권12호
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• pp.130-136
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• 2001

Burrs formed during face milling operations are very hard to characterize because there are many parameters that affect the cutting process. Many researchers have tried to predict burr characteristics including burr size and shapes with various experimental conditions such as cutting speed, feed rate, in-plane exit angle, number of inserts, etc., but it still remains as a challenging problem for the complex combined effects between the parameters. In this paper, the Taguchi method, which is a systematic optimization application in design and analysis of experiments, is introduced to acquire optimum cutting parameters for burr minimization in face milling. Also, analysis of variance (AVOVA) is employed to study the performance characteristics in more detail. Experimental verifications are provided to show the effectiveness of this approach.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.972-975
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• 2004

In order to reduce the noise of BLDC motor, a systematic optimization procedure for rotor structure is presented. The noise index is defined as the sum of volume velocity of FE-model that are calculated at the dominant frequencies during dehydration process, which is based on the principle of radiation simple volume source. Then, the five design variables are selected to represent the shape and layout or rotor structure. This discrete design optimization problem for minimizing the noise index is solved by 3-level orthogonal array based effect analysis. Finally, the response surface method (RSM) combined optimization approach is employed for more refining the approximate optimum.

• Smart Structures and Systems
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• 제30권5호
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• pp.463-477
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• 2022

In this paper, a hybrid vibration-impedance-based damage monitoring approach is experimentally evaluated for prestressed concrete (PSC) structures with local strand breakage. Firstly, the hybrid monitoring scheme is designed to alert damage occurrence from changes in vibration characteristics and to localize strand breakage from changes in impedance signatures. Secondly, a full-scale PSC anchorage is experimented to measure global vibration responses and local impedance responses under a sequence of simulated strand-breakage events. Finally, the measured data are analyzed using the hybrid monitoring framework. The change of structural condition (i.e., damage extent) induced by the local strand breakage is estimated by changes in a few natural frequencies obtained from a few accelerometers in the structure. The damaged strand is locally identified by tomography analysis of impedance features measured via an array of PZT (lead-zirconate-titanate) sensors mounted on the anchorage. Experimental results demonstrate that the strand breakage in the PSC structure can be accurately assessed by using the combined vibration and impedance features.

• 한국전자파학회논문지
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• 제10권6호
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• pp.959-967
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• 1999

본 논문에서는 등간격 선형어레이로 입사하는 다중 인코히어런트 평면파의 도래각을 추정하기 위하여 신 호부각법과 결합된 선형예측방법을 제안한다. 선호부각법의 기본 개념은 Frobenius norm변에서 주어진 추정 행렬에 가장 가까이에 있는 주어진 rank의 공분산 행렬을 찾는 것이다. 선형예측방법은 높은 분해능을 보이나 낮은 신호대 잡음비 환정에서 낮은 통계적 성능을 보이는 것으로 알려져 있다. 이 문제를 해결하기 위하여 선형예측방볍에 신호부각법을 적용하였다. 낮은 신호대 잡음비 환경에서도 제안된 선호부각 선형예측 방법의 성능이 기존의 선형예측방법보다 우수한 통계적 성능을 제공함을 컴퓨터 시율레이션을 통하여 알 수 있었다.

• Structural Engineering and Mechanics
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• 제71권2호
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• pp.197-210
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• 2019

Probabilistic buckling behavior of sandwich panel considering random system parameters using a radial basis function (RBF) approach is presented in this paper. The random system properties result in an uncertain response of the sandwich structure. The buckling load of laminated sandwich panel is obtained by employing higher-order-zigzag theory (HOZT) coupled with RBF and probabilistic finite element (FE) model. The in-plane displacement variation of core as well as facesheet is considered to be cubic while transverse displacement is considered to be quadratic within the core and constant in the facesheets. Individual and combined stochasticity in all elemental input parameters (like facesheets thickness, ply-orientation angle, core thickness and properties of material) are considered to know the effect of different degree of stochasticity, ply- orientation angle, boundary conditions, core thickness, number of laminates, and material properties on global response of the structure. In order to achieve the computational efficiency, RBF model is employed as a surrogate to the original finite element model. The stiffness matrix of global response is stored in a single array using skyline technique and simultaneous iteration technique is used to solve the stochastic buckling equations.

• Journal of Korean Neurosurgical Society
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• 제44권3호
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• pp.146-150
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• 2008

Objective : The authors reviewed the experience of 19 patients with orbital tumors and summarize the clinical features, surgical treatment and outcomes. Methods : The authors searched the database for all patients who underwent surgery for the treatment of orbital tumors at a single institution between 1999 and 2007. Data from clinical notes, surgical reports, and radiological findings were obtained for the analysis. Results : Orbital tumors constituted a heterogenous array of histopathology. The presenting symptoms were exophthalmos (52.6%), visual disturbance (26.3%) and pain (21.1%). The surgical approaches used were transcranial in 17 patients. Tumors located in the intraconal or perioptic space were surgically excised using a frontoorbital approach (8 cases). while pterional (3 cases). orbital (2 cases) and combined approaches (6 cases) were used for tumors in other sites. Total resection of tumors was achieved in 12 of 19 patients. In 4 patients with glioma and lymphoma only diagnostic biopsy was done. Three patients experienced visual deterioration postoperatively. Two patients had temporary diplopia, and one patient had temporary ptosis. Conclusion : Surgical treatment could be the mainstay of therapy for the majority of symptomatic orbital tumors. Many orbital tumors can be treated safely via a transcranial approach. Frontoorbital approach allows the surgeon to reach both the intraorbital and intracranial structures. Knowledge of the microanatomy of the orbit and meticulous surgical skills are necessary to overcome the pitfalls of intraorbital surgery.