Sungim Lee

Method to classify dental arch forms

INTRODUCTION The aim of this study was to propose a method to classify dental arch forms of subjects with normal occlusion into several types that can ensure both goodness of fit and clinical application. METHODS We selected 306 subjects with normal occlusion from 15,836 young adults, recorded 14 reference points that defined the distance between 2 arch forms as the area between 2 arches, and then classified the dental arch forms by using the partitioning around medoids clustering and silhouette method. We measured tooth size, arch width, basal arch width, arch depth, mesiodistal angulations, and buccolingual inclinations. RESULTS We identified 3 types of arch forms, and cross-classification of the maxillary by mandibular arch forms showed a more frequent distribution in the diagonal elements than in the off-diagonal elements. The 3 arch forms showed differences in tooth size, arch width, basal arch width, and inclination of the posterior teeth. CONCLUSIONS By defining area discrepancies as distance measures and applying them to the cluster method by using medoids, the dental arch form can be classified keeping control for the extremes without bias. It is hoped that this method will have possible clinical applications in determining the shape and number of preformed orthodontic arch forms.

Variation of the intermaxillary tooth-size relationship in normal occlusion

The purpose of this study was to explore the intermaxillary tooth-size relationship that is attributed to normal occlusion using multivariate cluster analysis, while simultaneously incorporating the full dentition as a data set. From the central incisor to the second molar, the tooth sizes of 307 subjects (188 males and 119 females; mean age ± standard deviation, 19.9 ± 3.3 years) with normal occlusion were investigated. Tooth-size data were analysed separately for the maxilla and the mandible. When clustering, the partitioning around medoids (PAM) algorithm was performed with the transformed data based on principal component analysis (PCA). After the subjects were classified into four groups, the cluster memberships were cross-classified, and the distribution pattern and intermaxillary tooth-size relationships were explored. Bolton tooth ratio showed a relatively wide range, and this was indicative of the variability in tooth size in subjects with a normal occlusion. However, the patterns of the intermaxillary tooth-size relationship were similar for males and females, and this result was concordant with the findings of the classic Bolton analysis. Using the multivariate approach to analyse the tooth-size data set of an individual patient and then comparing the results with the normal occlusion cluster has possible clinical applications in determining the amount and location of tooth-size control in orthodontics.

Relationships Between Respiratory Symptoms and FEV1 in Men and Women with Normal Lung Function: The Korean Health and Genome Study

Although the prevalence of chronic obstructive pulmonary disease (COPD) and its relationship with respiratory symptoms are well documented, few studies have focused on individuals with normal lung function, particularly in developed regions of Asia. The purpose of this report is to examine the relationship between respiratory symptoms and FEV1 in a population-based sample of Korean men and women with normal lung function. Subjects comprised 7518 individuals aged 40–69 years without airflow obstruction based on spirometric testing and in the absence of a medical history of pulmonary disease. Respiratory symptoms included chronic cough, chronic phlegm, wheezing, and shortness of breath. In men, the age-adjusted mean FEV1 was lower by 165 ml in smokers and 133 ml in nonsmokers in the presence versus the absence of wheezing (p < 0.05). While walking at a usual pace, FEV1 in smoking men was 210 ml lower in the presence versus the absence of shortness of breath (p < 0.05). Among nonsmoking men, overall shortness of breath and shortness of breath while walking uphill were associated with a lower FEV1 by 56 and 80 ml, respectively) versus those who reported having no shortness of breath (p < 0.05). Respiratory symptoms were unrelated to FEV1 in women smokers, although only 3.5% smoked cigarettes. In nonsmoking women, FEV1 was lower by an average of 89 ml in the presence versus the absence of wheezing (p < 0.001). Nonsmoking women also had a lower FEV1 in the presence of shortness of breath (overall, while at rest, and while walking uphill or at a usual pace, p < 0.001). Our findings suggest that respiratory symptoms are associated with a lower FEV1 in men and nonsmoking women with normal lung function. Whether respiratory symptoms can be used to identify individuals at risk for developing COPD needs further study.

Electromagnetically actuated 2-axis scanning micromirror with large aperture and tilting angle for lidar applications

This paper presents electromagnetically actuated 2-axis scanning micromirror with large aperture and tilting angle for laser pointing applications such as LIDAR systems. The 2-axis micromirror with the plate size of 3 mm in diameter was fabricated using gimbaled single crystal silicon with a coil and assembled with permanent magnet forming radial magnetic field. The micromirror was realized on SiOG (Silicon on Glass) wafer using 4 photolithography masks and the magnet assembly was optimized to maximize the torque. Horizontal resonance frequency of manufactured micromirror was measured 1.421 kHz and vertical resonant frequency was 396 Hz. The vertical scan angle was 16.87°, 26.32° and 22.61° with the cylindrical magnet diameter of 2.6 mm, 4.0 mm and 4.8 mm respectively. Horizontal maximum scan angle was 24.45° using a cylindrical magnet with the diameter of 4.0 mm. Proposed 2-axial electromagnetically actuated large size micromirror is expected to be applicable to LIDAR system because it can handle high power laser and fast 2-dimensional scanning.

Phenotype difference between familial and sporadic ankylosing spondylitis in Korean patients.

Clustered occurrences of ankylosing spondylitis (AS) in family have been noticed. We evaluated patients with AS confirmed by the modified New York criteria for familial history of AS (one or more first to third degree relatives). The clinical characteristics and the recurrence risks (number of AS patients/number of familial members) of the familial AS compared to sporadic AS were investigated. Out of a total of 204 AS patients, 38 patients (18.6%) reported that they had a familial history of AS. The recurrence risks in the familial AS patients for first, second and third degree family members were 14.5%, 5.2%, and 4.4% respectively. Erythrocyte sedimentation rate (ESR) (22.6±22.2 vs 35.4±34.4, P=0.029) and C-reactive protein (CRP) (1.24±1.7 vs 2.43±3.3, P=0.003) at diagnosis, body mass index (21.9±2.7 vs 23.7±3.3, P=0.002) and frequency of oligoarthritis (13.2% vs 33.7%, P=0.021) were significantly lower in the familial form. The presence of HLA-B27 (97.4% vs 83.1%, P=0.044) was significantly higher in familial AS. In conclusion, Korean familial AS patients show a lower frequency of oligoarthritis, lower BMI, lower ESR and CRP at diagnosis and higher presence of HLA-B27. Graphical Abstract

Fiber-Optic Localized Surface Plasmon Resonance sensor combined with micro fluidic channel

This paper proposes Fiber-Optic Localized Surface Plasmon Resonance (FO LSPR) sensor combined with micro fluidic channel, which enables the continuous supply of fluid for bio-reaction. The proposed method can prevent the degradation of the sensing characteristics due to the change of measurement condition. The feasibility of the FO LSPR sensor with micro fluidic channel is proved by Computational Fluid Dynamics simulation (CFD). Also, the proposed method has been evidenced by measuring the output intensity of the FO LSPR sensor at various refractive index solutions. Finally, Prostate Specific Antigen (PSA) immunoassay was measured to verify the possibility of the fabricated sensor system as a biosensor.

Bootstrap method to evaluate tightness of clusters with application to the Korean standard occlusion study

Dental arch form is an important part of dental orthodontic practice. Distance-based clustering methods are often used to find standard arch forms. In particular, S-J. Lee, S.I. Lee, J. Lim, H-J. Park, and T. Wheeler Method to classify human dental arch form, Am. J. Orthod. Dentofacial Orthop. (2010), to appear] propose a 1-type distance which is invariant to the location-shift and the rotational transformation. Despite the popularity of the distance-based methods, little attention is given to the choice of the distance which has a great influence on final clusters. We have three goals in this paper. First, we study the properties of the 1-type distance by Lee et al. (2010). Second, we propose a bootstrap-based procedure to evaluate quantitatively how good the clusters are. Finally, we apply the bootstrap procedure to the Korean standard occlusion study and compare the existing distance-based clustering methods in previous literature.

Assessment of chemical equivalence in herbal materials using chromatographic fingerprints by combination of three similarity indices and three-dimensional kernel density estimation

An intuitive and practical way to control chemical equivalence of secondary metabolites in herbal materials based on chromatographic fingerprints deserves a thorough discussion, yet it is relatively unexplored. For the first time, we propose a mixture of three similarity indices, the congruence coefficient, the average of the peak area ratios, and the larger value between the maximum peak area ratio and the reciprocal of the minimum peak area ratio, to make up for the weak points of some widely used similarity indices and to evaluate the chemical equivalence of two fingerprints from various perspectives. The three similarity values are fed into a three-dimensional kernel density estimation to determine the quality of herbal materials. This estimation enables precise detection of anomalies in the absence of prior quality determination experience. Forty Atractylodes samples similar in appearance and indiscriminately used for medical purposes were used to demonstrate the effectiveness of the developed approach. After a reference sample was postulated, a quality assessment of the 40 samples was performed using the three similarity values and the estimated kernel density. The samples that were judged by the developed approach to be of good quality were compared with those chosen by the most popular approach using decision criterion of a single similarity index. The benefits of the proposed approach were evident in that the qualified samples had the composition ratio and individual concentrations of multi-components closer to those of the reference in general, and their inter-sample deviation was significantly smaller.

Testing the effect of treatment on survival time with an immediate intermediate event

ABSTRACT In this paper, we consider testing the effects of treatment on survival time when a subject experiences an immediate intermediate event (IE) prior to death or predetermined endpoint. A two-stage model incorporating both (i) the effects of the covariates on the immediate IE and (ii) survival regression with the immediate IE and other covariates is presented. We study the likelihood ratio test (LRT) for testing the treatment effect based on the proposed two stage model. We propose two procedures: an asymptotic-based procedure and a resampling-based procedure, to approximate the null distribution of the LRT. We numerically show the advantages of the two stage modeling over the existing single stage survival model with interactions between the covariates and the immediate IE. In addition, an illustrative empirical example is provided.

AB0696 Phenotype Difference in Familial Ankylosing Spondylitis (AS) Compared to Sporadic as in Korea

Background Clustered occurrences of ankylosing spondylitis (AS) in the family have been noticed. Few phenotype studies on familial AS suggest the distinct features of the disease compared to sporadic disease. Objectives The aim of this study is to investigate clinical characteristics and incidence of familial form of AS compared to sporadic AS. Methods We evaluated patients with AS confirmed by the modified New York criteria for familial history of AS (one or more first to third degrees relatives). The clinical characteristics and the recurrence risks (number of AS patients/number of familial members) of the familial AS compared to sporadic AS were investigated. Results Out of a total of 204 AS patients (165 males, 39 females, mean age 37.0±13.1 years), 38 patients (18.6%) reported that they had a familial history of AS. The recurrence risks in the familial AS patients for first, second and third degree family members were 14.5%, 5.2%, and 4.4% respectively. ESR (22.6±22.2 vs. 35.4±34.4, p=0.029) and CRP (1.24±1.7 vs. 2.43±3.3, p=0.003) at diagnosis, body mass index (21.9±2.7 vs. 23.7±3.3, p=0.002) and frequency of oligoarthritis (13.2% vs. 33.7%, p=0.021) were significantly lower in the familial form. The presence of HLA-B27 (97.4% vs. 83.1%, p=0.044) was significantly higher in familial AS. Conclusions We report that Korean AS patients with a familial history had a higher presence of HLA-B27 than sporadic AS. The recurrence risk in the familial AS was highest in first degree relatives, indicating higher susceptibility to the disease. Distinct phenotypes of familial AS were lower frequency of oligoarthritis, lower ESR and CRP at diagnosis and lower body mass index. Disclosure of Interest None declared DOI 10.1136/annrheumdis-2014-eular.3469