• 천문학회보
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• 제46권1호
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• pp.47.2-47.2
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• 2021

Focusing on both small separations and baryonic acoustic oscillation scales, the cosmic evolution of the clustering properties of peak, void, wall, and filament-type critical points is measured using two-point correlation functions in ΛCDM dark matter simulations as a function of their relative rarity. A qualitative comparison to the corresponding theory for Gaussian random fields allows us to understand the following observed features: (i) the appearance of an exclusion zone at small separation, whose size depends both on rarity and signature (i.e. the number of negative eigenvalues) of the critical points involved; (ii) the amplification of the baryonic acoustic oscillation bump with rarity and its reversal for cross-correlations involving negatively biased critical points; (iii) the orientation-dependent small-separation divergence of the cross-correlations of peaks and filaments (respectively voids and walls) that reflects the relative loci of such points in the filament's (respectively wall's) eigenframe. The (cross-) correlations involving the most non-linear critical points (peaks, voids) display significant variation with redshift, while those involving less non-linear critical points seem mostly insensitive to redshift evolution, which should prove advantageous to model. The ratios of distances to the maxima of the peak-to-wall and peak-to-void over that of the peak-to-filament cross-correlation are ~2-√~2 and ~3-√~3WJ, respectively, which could be interpreted as the cosmic crystal being on average close to a cubic lattice. The insensitivity to redshift evolution suggests that the absolute and relative clustering of critical points could become a topologically robust alternative to standard clustering techniques when analysing upcoming surveys such as Euclid or Large Synoptic Survey Telescope (LSST).

• 대한물리의학회지
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• 제19권1호
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• pp.1-10
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• 2024

PURPOSE: This pre-post intervention study aimed to examine the effects of a 12-week supervised modified Taekwondo exercise program on the functional fitness of community-dwelling older adults. METHODS: 10 participants (mean age: 72.3 ± 4.6 years) completed the program over a 12-week period. The intervention consisted of Taekwondo-based exercises modified for older persons. Changes to functional fitness were measured using the finger-to-nose test, functional reach test, timed up and go test, 30-second sit-to-stand test, 30-second arm curl test, Chester step test, chair sit-and-reach test, and back scratch test. Participants were assessed prior to the training and after the final training session, changes were measured using descriptive statistics and paired sample 't' tests. RESULTS: Effect sizes ranged from small to large (Cohen's d = .22 to 1.23). The exercise program was well- tolerated by participants, with a high level of engagement and no attrition for the duration of the program. Results showed significant improvements in most measures of functional fitness (p < .05) except for the back scratch test (p = .051). CONCLUSION: These findings suggest a well-designed, supervised, modified Taekwondo exercise program can significantly improve functional fitness in older adults.

• 대한치매학회지
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• 제22권4호
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• pp.139-147
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• 2023

Background and Purpose: Dual walking task such as crossing over an obstacle may serve as an excellent tool for predicting early cognitive decline. Thus, this study aimed to investigate correlation between walking while crossing over an obstacle and executive functions under different gait phases to validate the use of walking with an obstacle for predicting early cognitive decline. Methods: A cross-sectional study was conducted on 48 elderly individuals from 2 day-care centers and 3 welfare-centers in Seoul and Gyeonggi, Korea. Executive function tests (Trail Making Test, Stroop test) and dual walking tests (gait speed, cadence, stance time, gait cycle time) were performed and compared using partial correlation analysis. Results: There were significant correlations between executive function and most of the gait variables (stance time, cadence, and gait cycle time) (p<0.05) when crossing over an obstacle while walking. Especially, stance time exhibited significant correlations with most executive functions (p<0.05). Conclusions: When evaluating executive function during walking with an obstacle, post-obstacle-crossing phase and stance time need to be observed.

• 한국통신학회논문지
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• 제31권4A호
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• pp.421-430
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• 2006

본 논문에서는 IEEE 802.11a 무선랜(WLAN) 환경에서 Cross Layer 기반의 채널 모니터링(Cross-Layered Monitoring: CLM)을 이용한 네트워크 적응형 고선명(high definition: HD) MPEG-2 TS 비디오 스트리밍 시스템을 제안한다. 무선 채널 모니터링을 위해 AE(access point)는 MAC(medium access control) 계층의 전송 상태를 주기적으로 측정하고 응용 계층의 스트리밍 서버로 전달한다. 이것은 비디오 스트리밍 응용 프로그램이 피드백 기반의 종단간 모니터링(End-to-End Monitoring: E2EM) 기법을 적용할 때보다 가변적인 무선 채널 상태에 좀 더 빠르고 효과적으로 적응할 수 있게 한다. 스트리밍 서버는 네트워크에 적응적인 전송을 위해 측정된 무선 채널 상태에 따라 우선순위 기반의 프레임 폐기(priority-based frame dropping)를 수행한다. 이를 위해 스트리밍 서버는 실시간 파싱(real-time parsing)과 프레임 기반의 패킷 우선순위화(frame-based prioritized packetization) 기능을 제공한다. 성능 평가를 위해 IEEE 802.11a 무선랜 환경에서의 다양한 스트리밍 실험을 수행한다. 실험 결과는 제안 시스템이 시간에 따라 가변하는 무선 채널 상태에서 기존 기법에 비해 종단간 비디오 스트리밍의 품질을 향상시킬 수 있음을 보여준다.

• Nutrition Research and Practice
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• 제2권1호
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• pp.8-12
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• 2008

The objective of this study was to assess the prevalence and clinical characteristics of anemia and to define the risk factors for anemia in older Koreans in Asan. From January to February 2002, five hundred sixty two community-dwelling older adults aged over 60 years were selected from a cross sectional study. All subjects underwent laboratory tests, which included a complete blood cell count, reticulocyte, liver and renal functional tests, lipid profiles and iron status tests. The median age was 68.6 years (range, 60-92 years). The mean levels of hemoglobin were $14.4{\pm}1.3\;g/dL$ in men and $12.9{\pm}1.0\;g/dL$ in women, and the overall prevalence of anemia was 12.5% in all subjects, 10.8% in men and 13.6% in women. The prevalence of anemia was the lowest among age group of 60-69 (10.0%) followed by 70-79 (15.5%), and the highest among age over 80 (20.7%), but the difference was significant only for men. The age difference was more distinct in men than in women (p<0.05). The mean hemoglobin level was significantly lower in the subjects aged over 80 y than those in the 60-69 y group (p<0.05). According to a logistic regression analysis, lower albumin and higher creatinine levels were identified as independent risk factors of anemia among older adults in Asan. In conclusion, the overall prevalence of anemia in our study group was 12.5% and the highest (20.7%) among those aged over 80 y.

• Kyungpook Mathematical Journal
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• 제13권2호
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• pp.235-240
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• 1973

A k-dimensional vector bundle is a bundle ${\xi}=(E,P,B,F^k)$ with fibre $F^k$ satisfying the local triviality, where F is the field of real numbers R or complex numbers C ([1], [2] and [3]). Let $Vect_k(X)$ be the set consisting of all isomorphism classes of k-dimensional vector bundles over the topological space X. Then $Vect_F(X)=\{Vect_k(X)\}_{k=0,1,{\cdots}}$ is a semigroup with Whitney sum (${\S}1$). For a pair (X, A) of topological spaces, a difference isomorphism over (X, A) is a vector bundle morphism ([2], [3]) ${\alpha}:{\xi}_0{\rightarrow}{\xi}_1$ such that the restriction ${\alpha}:{\xi}_0{\mid}A{\longrightarrow}{\xi}_1{\mid}A$ is an isomorphism. Let $S_k(X,A)$ be the set of all difference isomorphism classes over (X, A) of k-dimensional vector bundles over X with fibre $F^k$. Then $S_F(X,A)=\{S_k(X,A)\}_{k=0,1,{\cdots}}$, is a semigroup with Whitney Sum (${\S}2$). In this paper, we shall prove a relation between $Vect_F(X)$ and $S_F(X,A)$ under some conditions (Theorem 2, which is the main theorem of this paper). We shall use the following theorem in the paper. THEOREM 1. Let ${\xi}=(E,P,B)$ be a locally trivial bundle with fibre F, where (B, A) is a relative CW-complex. Then all cross sections S of ${\xi}{\mid}A$ prolong to a cross section $S^*$ of ${\xi}$ under either of the following hypothesis: (H1) The space F is (m-1)-connected for each $m{\leq}dim$ B. (H2) There is a relative CW-complex (Y, X) such that $B=Y{\times}I$ and $A=(X{\times}I)$ ${\cap}(Y{\times}O)$, where I=[0, 1]. (For proof see p.21 [2]).

• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2006년도 춘계학술대회 논문집
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• pp.373-373
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• 2006

• Bulletin of the Korean Chemical Society
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• 제16권4호
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• pp.360-363
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• 1995

The photopolymerization of methyl methacrylate(MMA) with phenylsilane wasperformed. The molecular weights of the poly(MMA) containing SiH moieties were increased with augment of molar ratio of PhSiH3 over MMA by cross-linking via hydrosilation at the expense of isolated yield. Phenylsilane apparently influenced on the photopolymerization as a chain transfer agent and solvent.

• Journal of the Korean Statistical Society
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• 제5권1호
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• pp.19-28
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• 1976

In empirical study for fitting a multiple linear regression model for successive cross-sections data observed on the same set of independent variables over several time periods, one often faces the problem of poor $R^2$, the multiple coefficient of determination, which provides a standard measure of how good a specified regression line fits the sample data.

• 한국안전학회지
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• 제32권6호
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• pp.143-149
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• 2017

According to traffic accidents statistics, the number of fatalities, injuries and the rate of increase of traffic accidents have been decreasing over last 5-years. The fatality rate is 1.9 for total accidents but the fatality rate for single vehicle accidents shows a 7.9, which is 4 times greater than the average for all accidents. Single vehicle accidents, usually occur as a vehicle impacts a fixed objects on the roadside as the vehicle runs-off from the road. However, few researches have been conducted considering the accident severity of single vehicle accidents which impact to the fixed objects on the road. The single vehicle accident is directly related to the composition of road cross section, (since it is the required the minimum width of a road for all run-off-the-road vehicles to recover or come to a safe stop). Therefore, this study analyzes the influence of road cross section on traffic accidents to find out the severity of single vehicle accident. To analyze the road elements which are related to the accident severity, the Ordered Probit Model was used. As variables, the element of road cross section such as the radius(m), vertical curve(%), cross sectional grade(%), road width(m). number of climbing lane, median, and curb, were used (as was the 3-years of accidents data). This study found out that cross slope(%), road width(m), and the number of climbing lane are related to the severity of accident. The result of this study could be expected to improve the road safety and to be used as the base data for further road safety research.