• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.12 no.6
• /
• pp.2619-2643
• /
• 2018

In this paper, a new clustering algorithm based on the connected region generation (CRG-clustering) is proposed. It is an effective and robust approach to clustering on the basis of the connectivity of the points and their neighbors. In the new algorithm, a connected region generating (CRG) algorithm is developed to obtain the connected regions and an isolated point set. Each connected region corresponds to a homogeneous cluster and this ensures the separability of an arbitrary data set theoretically. Then, a region expansion strategy and a consensus criterion are used to deal with the points in the isolated point set. Experimental results on the synthetic datasets and the real world datasets show that the proposed algorithm has high performance and is insensitive to noise.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.42 no.3
• /
• pp.52-60
• /
• 2019

This paper presents a numerically robust algorithm to construct a Voronoi diagram of circles in the plane. The circles are allowed to have intersections among them, but one circle cannot fully contain another circle. The Voronoi diagram is a tessellation of the plane into Voronoi regions of given circles. Each circle has its Voronoi region which is defined by a set of points in the plane closer to the circle than any other circles. The distance from a point p to a circle $c_i$ of center $p_i$ and radius $r_i$ is ${\parallel}p-p_i{\parallel}-r_i$, which is the closest Euclidean distance from p to the circle boundary. The proposed algorithm first constructs the point Voronoi diagram of centers of given circles, then it enlarges each point to the circle and expands its Voronoi region accordingly. This region-expansion process is done by local modifications and after completing this process for the whole circles the desired circle Voronoi diagram can be obtained. The proposed algorithm is numerically robust and we provide with a few examples to show its robustness. The algorithm runs in $O(n^2)$ time in the worst case and O(n) time on average where n is the number of the circles. The experiment shows that the region-expansion algorithm is robust and runs fast with strong linear time behavior.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.28 no.4
• /
• pp.320-328
• /
• 2006

Purpose: The aim of this study was to evaluate the effects of pterygomaxillary separation on dimensional changes of dental arch following surgically-assisted rapid maxillary expansion (SARME). Patients and Methods: Eighteen adults who had been treated by SARME for transverse maxillary deficiency from May 2000 to August 2005 were evaluated. Thirteen patients (Group 1) were treated with subtotal Le Fort I osteotomy including pterygomaxillary separation and anterior midpalatal osteotomy. The same operation was performed in five patients (Group 2) except pterygomaxillary separation. Dental study casts were taken before operation and after removal of expansion device. And then, skeletal and dental parameters were measured pre- and post-operatively. Results: 1. Changes of mean interdental width 1) In group 1, mean maxillary interdental width was increased 70%($47{\sim}99%$), 95%($84{\sim}115%$), and 77%($57{\sim}94%$) of total expansion on canine, first premolar, and first molar region, respectively after retention. 2) In group 2, mean maxillary interdental width was increased 77%($59{\sim}100%$), 78%($45{\sim}107%$), and 86%($57{\sim}116%$) of total expansion on canine, first premolar, and first molar region, respectively after retention. 3) There was a statistical difference between the change of interdental width of group 1 and group 2 at first premolar(p<0.05). 2. Changes of mean interalveolar width 1) In group 1, mean maxillary alveolar bone width was increased 66%($42{\sim}84%$), 74%($42{\sim}104%$), and 57%($31{\sim}78%$) of total expansion on canine, first premolar, and first molar region, respectively after retention. 2) In Group 2, mean maxillary alveolar bone width was increased 73%($55{\sim}98%$), 67%($36{\sim}89%$), and 59%($48{\sim}73%$) of total expansion on canine, first premolar, and first molar region, respectively after retention. 3) There were no statistical differences between group 1 and group 2 at each teeth area. Conclusion: These results suggest that SARME without pterygomaxillary separation may allow the relatively equal expansion at both anterior and posterior teeth area and most amounts of maxillary interdental expansions were acquired with the expansion of the maxilla by SARME.

• Journal of the Korean Home Economics Association
• /
• v.17 no.4
• /
• pp.1-14
• /
• 1979

The functional problems of the basic pattern of clothing are a matter of the first importance to clothing construction. Therefore, the ergonomic analysis of the expansion and contraction of the upper body surface, due to motion, has become required. thus in order to obtain the measurements and rate of expansion and contraction of the upper body surface following from its motions, the development figure of " Shell" and somatometry were employed. The results obtained through the investigation can be summarized as follows : 1) According to the developmental figures of "Shell" the latitudes centering around the shoulder line present contractive tendencies by arm movement. The longitudes around the center back waist length are expansive tendencies when bent forward. In the case of a 15$^{\circ}$ lean backward posture, the longitudes around the center front waist length are expansive tendencies. 2) By somatometry, the region from the scapula to the axilla point the upper back with presents the greatest expansion (more than 30%). The region from scapla to arm presents the maximum rate of contraction. In considering the longitude , under the axilla waist length and the bust point waist length generally shows the greatest rate of expansion. 3) The bust point waist length and under the axilla waist length are of great importance to the basic pattern of clothing. and have expansive tendencies(6.3cm). Among the latitudes, the upper back width has the greatest tendency for expansion (7.83 cm). 4) The region which presents the greatest rate of the expansion and contraction is in the proximity of the arm. These results testify that the amount of room of the back width must be given consideration in constructing the basic pattern of clothing.pattern of clothing.

• International Journal of Industrial Entomology and Biomaterials
• /
• v.47 no.2
• /
• pp.99-114
• /
• 2023

Patanga japonica Bolívar, 1898 (Orthoptera: Acrididae) is listed as a climate-sensitive indicator species in South Korea and is called southern group of insects in that the main distributional range is southern region of South Korea and Asian continent. In South Korea, thus, the species was distributed mainly in southern region of South Korea including southward a remote Jeju Island, but recently the species has often been detected in mid to northern region of South Korea, implying northward range expansion in response to climate change. Understanding the characteristics of the changes in genetic diversity during range expansion in response to climate change could be a foundation for the understanding of future biodiversity. Thus, in this study, we attempted to understand the changing pattern of the genetic diversity of the P. japonica in newly expanded regions. For the purpose of study, we collected 125 individuals from seven localities throughout South Korea including two newly distributed regions (Pyeongtaek and Yeongwol at ~37° N). These were sequenced for a segment of mitochondrial cytochrome oxidase subunit I (COI) and analyzed for genetic diversity, haplotype frequency, and population genetic structure among populations. Interestingly, northward range expansion accompanied only haplotypes, which are most abundant in the core populations, providing a significant reduction in haplotype diversity, compared to other populations. Moreover, genetic diversity was still lower in the expanded regions, but no genetic isolation was detected. These results suggest that further longer time would take to reach to the comparable genetic diversity of preexisting populations in the expanded regions. Probably, availability of qualified habitats at the newly expanded region could be pivotal for successful northward range expansion in response to climate change.

• IEIE Transactions on Smart Processing and Computing
• /
• v.2 no.2
• /
• pp.97-101
• /
• 2013

Bit-depth expansion is a process of enhancing the image quality by increasing the number of intensity levels. To solve this problem, a hybrid method is proposed, where the pixels are categorized into smooth and complex regions, and are processed using different methods. The pixels in the smooth region are reconstructed with a smooth prior, and a Bayesian estimator is used for the pixels in the complex region. The proposed method effectively removes the false contour artifacts while requiring less computation than conventional methods. In addition, the method shows good quantitative performance, and the PSNR gains over the best existing method are 1.45 dB and 0.26 dB for 4 bits and 3 bits expansion cases, respectively.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2005.10a
• /
• pp.362-365
• /
• 2005

The hub hole is usually formed with a flanging process followed by a blanking process of a ]tole. Since the hole is made by blanking, the blanked surface is so rough that the formability in the region is rather poor. The emerging task is to identify the formability of the blanked region in the forming simulation and to relate the criterion to the real forming process by experiments. In this paper, hole expansion tests are carried out with respect to various hole conditions to verify the hole condition effect on the hole expansion ratio. The hole of specimens is made by machining or punching. In the case of punching, two different punching clearances are used for making the hole. From the results of test, fracture mechanism of the hole expansion is explained.

• ETRI Journal
• /
• v.29 no.1
• /
• pp.89-94
• /
• 2007

A mathematical model for the input-output characteristic of an amplifier exhibiting gain expansion and weak and strong nonlinearities is presented. The model, basically a Fourier-series function, can yield closed-form series expressions for the amplitudes of the output components resulting from multisinusoidal input signals to the amplifier. The special case of an equal-amplitude two-tone input signal is considered in detail. The results show that unless the input signal can drive the amplifier into its nonlinear region, no gain expansion or minimum intermodulation performance can be achieved. For sufficiently large input amplitudes that can drive the amplifier into its nonlinear region, gain expansion and minimum intermodulation performance can be achieved. The input amplitudes at which these phenomena are observed are strongly dependent on the amplifier characteristics.

• Geomechanics and Engineering
• /
• v.19 no.2
• /
• pp.141-151
• /
• 2019

A novel theoretical solution is presented for created (zero initial radius) cavity expansion problem based on CamClay model and considers the effect of initial anisotropic in-situ stress and drained conditions. Here the strain of this theoretical solution is small deformation in elastic region and large deformation in plastic region. The works for cylindrical and spherical cavities expanding in drained condition from zero initial radius are investigated. Most of the conventional solutions were based on the isotropic and undrained condition, however, the initial stress state of natural soil mass is anisotropy by soil deposition history, and drained cavity expansion calculation is closer to actual engineering in permeable soil mass. Finally, the parametric study is presented in order to the engineering significance of this work.

• The Bulletin of The Korean Astronomical Society
• /
• v.40 no.1
• /
• pp.58.3-59
• /
• 2015

Dynamical expansion of H II regions plays a key role in dispersing surrounding gas and therefore in limiting the efficiency of star formation in molecular clouds. We use analytic methods and numerical simulations to explore expansions of spherical dusty H II regions, taking into account the effects of direct radiation pressure, gas pressure, and total gravity of the gas and stars. Simulations show that the structure of the ionized zone closely follows Draine (2011)'s static equilibrium model in which radiation pressure acting on gas and dust grains balances the gas pressure gradient. Strong radiation pressure creates a central cavity and a compressed shell at the ionized boundary. We analytically solve for the temporal evolution of a thin shell, finding a good agreement with the numerical experiments. We estimate the minimum star formation efficiency required for a cloud of given mass and size to be destroyed by an HII region expansion. We find that typical giant molecular clouds in the Milky Way can be destroyed by the gas-pressure driven expansion of an H II region, requiring an efficiency of less than a few percent. On the other hand, more dense cluster-forming clouds in starburst environments can be destroyed by the radiation pressure driven expansion, with an efficiency of more than ~30 percent that increases with the mean surface density, independent of the total (gas+stars) mass. The time scale of the expansion is always smaller than the dynamical time scale of the cloud, suggesting that H II regions are likely to be a dominant feedback process in protoclusters before supernova explosions occurs.