Kyomin Choi

Sampling-Based Sensitivity Approach to Electromagnetic Designs Utilizing Surrogate Models Combined with a Local Window

This paper proposes a sampling-based optimization method for electromagnetic design problems, where design sensitivities are obtained from the elaborate surrogate models based on the universal Kriging method and a local window concept. After inserting additional sequential samples to satisfy the certain convergence criterion, the elaborate surrogate model for each true performance function is generated within a relatively small area, called a hyper-cubic local window, with the center of a nominal design. From Jacobian matrices of the local models, the accurate design sensitivity values at the design point of interest are extracted, and so they make it possible to use deterministic search algorithms for fast search of an optimum in design space. The proposed method is applied to a mathematical problem and a loudspeaker design with constraint functions and is compared with the sensitivity-based optimization adopting the finite difference method.

Optimization of a SMES Magnet in the Presence of Uncertainty Utilizing Sampling-based Reliability Analysis

This paper proposes an efficient reliability-based optimization method for designing a superconducting magnetic energy system in presence of uncertainty. To evaluate the probability of failure of constraints, samplingbased reliability analysis method is employed, where Monte Carlo simulation is incorporated into dynamic Kriging models. Its main feature is to drastically reduce the numbers of iterative designs and computer simulations during the optimization process without sacrificing the accuracy of reliability analysis. Through comparison with existing methods, the validity of the proposed method is examined with the TEAM Workshop Problem 22.

Long-term retention rate of zonisamide in patients with epilepsy: an observational study.

IntroductionZonisamide (ZNS) is an antiepileptic drug with a broad spectrum of action mechanisms. Although ZNS is usually indicated for the adjunctive treatment of partial seizures in Western countries, it has long been used for partial and generalized seizures as monotherapy or adjunctive treatment in South Korea and Japan. The present study was to evaluate the long-term retention rate of ZNS in clinical practice. MethodsThis was a retrospective, single-center, long-term observational study. A total of 148 patients (82 men, 66 women; 14–85 years) who were treated with ZNS as monotherapy or adjunctive treatment were included. Zonisamide was administrated with a starting dose of 100 mg/d, and optimal-dose adjustments were made according to individual clinical responses. Efficacy and tolerability were analyzed during a 6-year follow-up. ResultsThe overall retention rate was 66.1% at 1-year and 55.1% at 6-year follow-up. Patients with monotherapy (70.8% vs 44.1%) and generalized seizures (71.6% vs 48.2%) were more likely to continue ZNS at 6-year follow-up compared with those with adjunctive therapy and partial seizures. The most common cause of discontinuation was adverse events such as somnolence, rash, and gastrointestinal problems. ConclusionsOur study shows the high retention rate of ZNS in the treatment of patients with epilepsy. The retention rate of ZNS was comparable with those of other antiepileptic drugs including lamotrigine, topiramate, and levetiracetam, and it can be suggested that ZNS can be considered for monotherapy and for the patients with generalized seizures.

Efficient Methodology for Reliability Assessment of Electromagnetic Devices Utilizing Accurate Surrogate Models Based on Dynamic Kriging Method

This paper presents an efficient methodology for accurate reliability assessment of electromagnetic devices. To achieve the goal, elaborate surrogated models to approximate constraint functions of interest are generated based on the dynamic Kriging method and a hypercube local window. Then, the Monte Carlo simulation scheme is applied to the surrogate models. This leads to reducing computational cost dramatically without degrading accuracy of the reliability analysis. The validity of the proposed method is tested and examined with a mathematical example and a loudspeaker design.

Spinobulbar muscular atrophy combined with atypical hereditary neuropathy with liability to pressure palsy

Spinobulbar muscular atrophy (SBMA) is an X-linked recessive disease, presenting motor weakness and wasting of facial, bulbar and limb muscles. Hereditary neuropathy with liability to pressure palsy (HNPP) is autosomal dominant disorder characterized by recurrent neuropathies at common entrapment sites. We report a case of co-existence of SBMA and atypical HNPP with genetic confirmation of CAG expansion in the androgen receptor (AR) gene and deletion of the peripheral myelin protein 22 (PMP22) gene. A 62-year-old man presented with progressive muscle weakness, fasciculations in upper and lower limbs and dysesthesia predominantly in the distal regions. No family members, including his children, experienced similar symptoms. The electrodiagnostic examination was compatible with demyelinating sensorimotor polyneuropathy. Simultaneous hereditary polyneuropathy and motor neuron disease were suspected and relevant genetic testing was confirmed HNPP and SBMA. This case presented with 2 rare genetic neuromuscular disorders and the atypical HNPP phenotype. This case highlight the importance of detailed patient histories, as well as neurological and electrophysiological examinations for diagnosis of atypical and combination of rare genetic disorders.

Characteristics of South Korean Patients with Hereditary Transthyretin Amyloidosis

Background and Purpose This retrospective cross-sectional study included 18 patients from unrelated families harboring mutations of the transthyretin gene (TTR), and analyzed their characteristics and geographical distribution in South Korea. Methods The included patients had a diagnosis of systemic amyloidosis, clinical symptoms, such as amyloid neuropathy or cardiomyopathy, and confirmation of a TTR gene mutation using genetic analysis recorded between April 1995 and November 2014. Results The mean age at disease onset was 49.6 years, and the mean disease duration from symptom onset to diagnosis was 3.67 years. Fifteen of the 18 patients were classified as mixed phenotype, 2 as the neurological phenotype, and only 1 patient as the cardiac phenotype. The most-common mutation pattern in South Korea was Asp38Ala, which was detected in eight patients. Thirteen patients reported their family hometowns, and five of the eight harboring the Asp38Ala mutation were from the Gyeongsang province in southeast Korea. The other eight patients exhibited a widespread geographical distribution. A particularly noteworthy finding was that the valine at position 30 (Val30Met) mutation, which was previously reported as the most-common TTR mutation worldwide and also the most common in the Japanese population, was not detected in the present South Korean patients. Conclusions South Korean patients with hereditary TTR amyloidosis exhibited heterogeneous TTR genotypes and clinical phenotypes. The findings of this study suggest that the distribution of TTR amyloidosis in South Korea is due to de novo mutations and/or related to the other countries in East Asia.

Hybrid Reliability Analysis Method for Electromagnetic Design Problems With Non-Gaussian Probabilistic Parameters

This paper proposes an efficient and stable reliability analysis method for reliability-based electromagnetic design problems with non-normal probability distributions of input parameters. The reliability analysis strongly depends on distribution types of random variables since nonlinear transformations between an original random space and a standard normal random space cause additional nonlinearity into the reliability assessment of probabilistic constraint functions. That can lead to numerical inaccuracy and instability in the reliability-based design process, or may fail to have a solution to the probabilistic constraint assessment. To overcome these difficulties, a hybrid mean-value method is introduced to seeking a most probable failure point in the performance measure approach, which is one of the first-order reliability analysis methods. The proposed method is tested with a mathematical model and a loudspeaker design, of which random variables are assumed to follow five different probability distributions case by case.