• Title/Summary/Keyword: t Distribution

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Infrared thermographic imaging in patients with alopecia. (탈모 환자의 적외선 체열 진단상 안면부 체열 특성)

  • Yi, Tae-Hoo;Moon, Jung-Bae;An, Kyung-Eh;Lee, Hye-Jung
    • Journal of Oriental Medical Thermology
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    • v.5 no.1
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    • pp.78-86
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    • 2006
  • Objectives: To examine any potential relationships between the types of alopecia and the facial heat distribution in patients with alopecia Methods: 183 patients with alopecia participated in this study to provide facial heat distribution measured by the Infrared Thermography Scanner (ITS, Nec San-ei Instruments Ltd, Japan). The thermography scan was used in a light-and heat-protected room after 20 minutes’of resting period. 1.5m of distance maintained between the patients and ITS. Results: Specificity in the type of facial heat distribution was found as follow. 1. Types of facial heat distribution can be classified as T-type and diffused patterns. 2. There was a significant difference in the pattern of facial heat distribution among different types of alopecia (p=0.002): facial heat distribution appeared T-type in Androgenic Alopecia, Alopecia Areata, and Telogen Effluvium (71.3%, 85.7%, 70.4%), whereas diffused pattern was dominant in Seborrheic Alopecia(55.6%). 3. There was a significant difference in the pattern of facialheat distribution between men and women (p<0.001): While the T-type and diffused type were equally appeared in men (50.6%: 49.4%), T-type was dominant in women (88.0% vs. 12.0%). Conclusions: We conclude that the pattern of facial heat distribution differs depends on the types of alopecia and gender. These differences may provide useful information for the diagnosis and clinical therapy for this population.

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Changes of NMR Relaxation Pattern of Pork Loins during Freezing and Thawing Using Continuous Distribution Analysis (Continuous distribution analysis를 이용한 냉.해동과정 중 돈육의 NMR relaxation pattern의 변화)

  • Lee, Sun-Min;Rho, Jeong-Hae;Yoon, Hye-Hyun;Lee, Taek-Soo
    • Korean Journal of Food Science and Technology
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    • v.35 no.1
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    • pp.57-61
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    • 2003
  • Variations in NMR relaxation time during freezing and thawing processes in pork loins were investigated. Continuous distribution analysis of data obtained from $T_2\;CPMG$ were carried out to observe the changes in water content in the muscles. Solid fat content slightly increased with decreasing temperature, then showed sharp increase at $-4^{\circ}C$, reaching 85% at $-25^{\circ}C$. Relaxation time decreased with decreasing temperature, suggesting that ice crystals gradually formed at freezing temperature. $T_2$ relaxation time during thawing was higher than that during freezing, suggesting that ice crystals melted by thawing and resulted in water loss from meat. Continuous distribution analysis of data obtained from Carr-Purcell-Meiboom-Gill experiments shows one to four components on the spectra during freezing and thawing processes. The area of major components between 30 to 45 ms decreased with decreasing temperature, and were not detected below $-4^{\circ}C$, below which only $T_s$ signal was detected. The area of $T_s$ decreased with decreasing temperature. Between -4 to $10^{\circ}C$, the areas of $T_m$ and $T_l$ during thawing were larger than those during freezing. These results suggest that the exchange between bound water and free water takes place during freezing and thawing.

Can the Skewed Student-t Distribution Assumption Provide Accurate Estimates of Value-at-Risk?

  • Kang, Sang-Hoon;Yoon, Seong-Min
    • The Korean Journal of Financial Management
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    • v.24 no.3
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    • pp.153-186
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    • 2007
  • It is well known that the distributional properties of financial asset returns exhibit fatter-tails and skewer-mean than the assumption of normal distribution. The correct assumption of return distribution might improve the estimated performance of the Value-at-Risk(VaR) models in financial markets. In this paper, we estimate and compare the VaR performance using the RiskMetrics, GARCH and FIGARCH models based on the normal and skewed-Student-t distributions in two daily returns of the Korean Composite Stock Index(KOSPI) and Korean Won-US Dollar(KRW-USD) exchange rate. We also perform the expected shortfall to assess the size of expected loss in terms of the estimation of the empirical failure rate. From the results of empirical VaR analysis, it is found that the presence of long memory in the volatility of sample returns is not an important in estimating an accurate VaR performance. However, it is more important to consider a model with skewed-Student-t distribution innovation in determining better VaR. In short, the appropriate assumption of return distribution provides more accurate VaR models for the portfolio managers and investors.

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Distribution Patterns of the Members of Phylum Acidobacteria in Global Soil Samples

  • Lee, Sang-Hoon;Cho, Jae-Chang
    • Journal of Microbiology and Biotechnology
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    • v.19 no.11
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    • pp.1281-1287
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    • 2009
  • The distribution pattern of the phylum Acidobacteria, a previously uncultured bacterial group, was investigated by molecular ecological analyses of global soil samples collected from pristine ecosystems across five continents. Acidobacterial 16S rDNAs were observed in almost all soil samples, and members of acidobacterial primer group A were detected in all samples that harbored the phylum Acidobacteria. Other primer groups, Y, G, and O, showed limited distribution patterns. We further divided the primer groups into acidobacterial subdivisions (class-level). Subdivisional distribution patterns were determined by comparing the observed T-RFs with theoretical T-RFs predicted by in silico digestion of acidobacterial 16S rDNAs. Consistent with the PCR results obtained with subgroup-specific primers, T-RFLP analyses showed that acidobacterial subdivision 1 belonging to primer group A was present in the majority of the soil samples. This study revealed that the phylum Acidobacteria could be globally distributed. At the subdivisional level, acidobacterial subdivision 1 might be the most widely distributed group in this phylum, indicating that members of subdivision 1 might be adapted to various soil environments, and members belonging to other subdivisions might be restricted to certain geographic regions or habitats.

A joint probability distribution model of directional extreme wind speeds based on the t-Copula function

  • Quan, Yong;Wang, Jingcheng;Gu, Ming
    • Wind and Structures
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    • v.25 no.3
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    • pp.261-282
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    • 2017
  • The probabilistic information of directional extreme wind speeds is important for precisely estimating the design wind loads on structures. A new joint probability distribution model of directional extreme wind speeds is established based on observed wind-speed data using multivariate extreme value theory with the t-Copula function in the present study. At first, the theoretical deficiencies of the Gaussian-Copula and Gumbel-Copula models proposed by previous researchers for the joint probability distribution of directional extreme wind speeds are analysed. Then, the t-Copula model is adopted to solve this deficiency. Next, these three types of Copula models are discussed and evaluated with Spearman's rho, the parametric bootstrap test and the selection criteria based on the empirical Copula. Finally, the extreme wind speeds for a given return period are predicted by the t-Copula model with observed wind-speed records from several areas and the influence of dependence among directional extreme wind speeds on the predicted results is discussed.

A Study on Establishment of the IoT-Based Remote Management System for District Heating Facilities (지역난방설비를 위한 IoT 기반 원격 관리 시스템 구축에 대한 연구)

  • Kim, Jun-hyeok;Lee, Sang-hak;Kim, Byung-min
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.42 no.3
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    • pp.698-701
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    • 2017
  • The district heating system supports currently 1.3 million of houses in South Korea, and it is composed of two main parts: provision and distribution. For the provision part, Korea District Heating Corporation supervises the system with proper devices and experts, whereas for the distribution parts, there is no main supervision system and it depends highly on experts although it is very difficult to find the proper experts. In this paper, we consider IoT based remote management system for district heating distribution to properly supervise heating distribution by experts and/or programs remotely.

Thai Classical Music Matching Using t-Distribution on Instantaneous Robust Algorithm for Pitch Tracking Framework

  • Boonmatham, Pheerasut;Pongpinigpinyo, Sunee;Soonklang, Tasanawan
    • Journal of Information Processing Systems
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    • v.13 no.5
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    • pp.1213-1228
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    • 2017
  • The pitch tracking of music has been researched for several decades. Several possible improvements are available for creating a good t-distribution, using the instantaneous robust algorithm for pitch tracking framework to perfectly detect pitch. This article shows how to detect the pitch of music utilizing an improved detection method which applies a statistical method; this approach uses a pitch track, or a sequence of frequency bin numbers. This sequence is used to create an index that offers useful features for comparing similar songs. The pitch frequency spectrum is extracted using a modified instantaneous robust algorithm for pitch tracking (IRAPT) as a base combined with the statistical method. The pitch detection algorithm was implemented, and the percentage of performance matching in Thai classical music was assessed in order to test the accuracy of the algorithm. We used the longest common subsequence to compare the similarities in pitch sequence alignments in the music. The experimental results of this research show that the accuracy of retrieval of Thai classical music using the t-distribution of instantaneous robust algorithm for pitch tracking (t-IRAPT) is 99.01%, and is in the top five ranking, with the shortest query sample being five seconds long.

Effects of Influent Flow Distribution Ratio and HRT on Sewage Treatment Efficiency of the ASA Process (유입수 분배비와 체류시간이 ASA 공정의 가정오수 처리효율에 미치는 영향)

  • Yang, Eun-Gyoung;Sung, Il-Wha
    • Journal of environmental and Sanitary engineering
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    • v.24 no.1
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    • pp.13-24
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    • 2009
  • This study was performed to determine the effect of the influent flow distribution ratio and hydraulic retention time(HRT) on removal of organic matter, nitrogen and phosphorus when domestic sewage was treated by the advanced step aeration(ASA) process. Results of the experiment for the determination of the optimum influent flow distribution ratio between the anaerobic reactor and the anoxic reactor showed BOD removal efficiencies of above 92.0% at all influent flow distribution ratios from 9:1 to 4:6. The highest T-N removal efficiency was 82.6% at the influent flow distribution ratio of 6:4. On the other hand, the highest T-P removal efficiency was 67.8% at the influent flow distribution ratio of 9:1. Considering both the T-N and T-P removal efficiencies, the influent distribution ratio of 6:4 was considered the optimum. Results of the experiment for the determination of the optimum HRT at the optimum influent flow distribution ratio of 6:4 revealed BOD removal efficiencies better than 92.7% at all HRTs from 12hr down to 6hr. The highest T-N and T-P removal efficiency were 82.6% and 59.5%, respectively both at the HRT of 8hr. In conclusion, the optimum influent flow distribution ratio and HRT for treatment of domestic sewage by the ASA process were determined to be 6:4 and 8hr, respectively.

Distribution Types of the Relict Conifer Community and the Approach for the Ecological Management in Ulleung-Island (울릉도에 자생하는 침엽수류 유존군락의 분포유형과 생태적 관리방안에 대한 연구)

  • Cho, Hyun-Je;Lee, Jung-Hyo;Choo, Yeon-Sik;Hong, Sung-Cheon
    • Journal of Korean Society of Forest Science
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    • v.100 no.1
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    • pp.95-104
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    • 2011
  • Distribution types of native conifers (Juniperus chinensis, Pinus parviflora, Tusga sieboldii and Taxus cuspidata var. latifolia) were studied by phytosociological investigation and ZM method in Ulleung Island, South Korea. Two main types were divided maritime vegetation (Juniperus chinensis forest) and mountain vegetation (Taxus cuspidata var. latifolia forest and Pinus parviflora-Tusga sieboldii forest). The former was divided into sea cliff distribution (J-SC) and sea ridge distribution (J-SR) type. The latter was classified 7 distribution types; Taxus cuspidata var. latifolia forest was rock distribution (Ta-R) and mountain slope distribution (Ta-MS) type, and Pinus parviflora-Tusga sieboldii forest was rock distribution (P T-R), upper and ridge distribution (P T-UR, 3 units sub-types:1sub, 2sub, 3sub), and Mountain slope distribution (P T-MS) type. It was considered that J-SC, Ta- R, and P T-R were maintained by topographic climax, but J-SR, Ta-MS, P T-UR and P T-MS were the process of vegetation succession. Distribution types of topographic climax are entrusted to process of vegetation succession. Types in the process of vegetation succession will be needed tending of forest to promote saplings growth and seedlings germination. Especially in order to restore Tsuga sieboldii forest should be afforest and make forest gap because It is mid shade tolerant tree and purity percentage of its seed is 1~2%. It was considered that the composition of group mixture forest constituted Pinus parviflora, Tsuga sieboldii, Taxus cuspidata, Camellia japonica, Machilus thunbergii and Acer okamotoanum, etc. will be able to restore native vegetation, after take the form of forest gap by strong thinning and pruning of Pinus thunbergii forest.