• Journal of applied mathematics & informatics
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• 제5권3호
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• pp.819-826
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• 1998

The purpose of this paper is to prove the following results; (1) Let R be a prime ring of char $(R)\neq 2$ and I a nonzero left ideal of R. The existence of a nonzero symmetric bi-derivation D : $R\timesR\;\longrightarrow\;$ such that d is sew-commuting on I where d is the trace of D forces R to be commutative (2) Let m and n be integers with $m\;\neq\;0.\;or\;n\neq\;0$. Let R be a noncommutative prime ring of char$ (R))\neq \; 2-1\; p_1 \;n_1$ where p is a prime number which is a divisor of m, and I a nonzero two-sided ideal of R. Let $D_1$ ; $R\;\times\;R\;\longrightarrow\;and\;$ $D_2\;:\;R\;\times\;R\;longrightarrow\;R$ be symmetric bi-derivations. Suppose further that there exists a symmetric bi-additive mapping B ; $R\;\times\;R\;\longrightarrow\;and\;$ such that $md_1(\chi)\chi ＋ n\chi d_2(\chi)=f(\chi$) holds for all $\chi$$\in$I, where $d_1 \;and\; d_2$ are the traces of $D_1 \;and\; D_2$ respectively and f is the trace of B. Then we have $D_1=0 \;and\; D_2=0$.

• Korean Circulation Journal
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• 제54권3호
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• pp.126-137
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• 2024

Background and Objectives: The impact of off-hours admission (such as weekends, nighttime, and non-working hours) vs. regular hours (weekdays and daytime working hours) on the mortality risk of patients undergoing surgery for type A aortic dissection (TAAD) repair is still uncertain. To address this uncertainty, we undertook a comprehensive systematic review and meta-analysis. We aimed to assess the potential link between off-hours admission and the risk of mortality in patients undergoing TAAD repair surgery. Methods: We conducted a thorough search of the PubMed, Embase, and Cochrane Library databases, covering the period from their inception to May 20, 2023. Our inclusion criteria encompassed all studies that examined the potential relationship between off-hour admission and mortality in individuals who had undergone surgery for TAAD repair. The odds ratios (ORs) were extracted and combined utilizing a random effects model for our synthesis. Results: Nine studies with 16,501 patients undergoing TAAD repair surgery were included in the meta-analysis. Overall, patients who underwent surgery during the weekend had higher in-hospital mortality (pooled OR, 1.41; 95% confidence interval [CI], 1.14-1.75; p=0.002) than those treated on weekdays. However, the mortality risks among patients who underwent TAAD surgery during nighttime and non-working hours were not significantly elevated compared to daytime and working hours admission. Conclusions: Weekend surgery for TAAD was associated with a higher in-hospital mortality risk than weekday surgery. However, further studies are warranted to identify and develop strategies to improve the quality of round-the-clock care for patients with TAAD.

• 대한수학회보
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• 제35권4호
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• pp.625-627
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• 1998

Let f: S$\rightarrow$ C be a fiber space with connected fibers. We may have an information about a surface S from the fiber space structure. The result we have is ${\chi}({\mathcal O}_C){\chi}({\mathcal O}_F){\leq}{\chi}({\mathcal O}_S)$.

• 전자공학회논문지CI
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• 제42권4호
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• pp.51-58
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• 2005

본 논문에서는 비디오 시퀀스의 자동분류를 지원하기 위한 기반기술로서, 변형된 $\chi^2$-테스트와 자동 임계치-결정 알고리즘을 이용한 장면전환 검출 기법을 제안하였다. 변형된 $\chi^2$-테스트는 기존의 컬러 히스토그램에서 컬러의 각 채널공간(RGB)에 NTSC표준에 따른 명암도 등급을 따로 계산하여 채널의 차이 값을 보다 세분화 할 수 있으며, 인접한 두 프레임사이의 상대적인 컬러 값의 차이를 강조하는$\chi^2$- 테스트를 결합하여 보다 강건한 장면전환 곁출을 시도하고 있다. 자동 임계치-결정 알고리즘은 변형된 $\chi^2$-테스트를 통하여 획득된 인접한 프레임들 사이의 차이 값들을 이용한다. 먼저, 차이 값들에 대한 전체 평균값을 계산한 후, 이 평균값을 만족하는 차이 값들만을 이용하여 다시 평균값을 계산하며, 이러한 평균값의 연속적인 계산 및 누적을 통하여 분산된 차이 값들로부터 가장 최적의 중간 평균값을 취하여 임계치로 설정하는 방법이다. 실험결과 제안된 장면전환 검출 방법과 자동 임계치-결정 알고리즘은 기존의 접근방법보다 효과적이며, 그 우수성을 보여주었다.

• 한국학교ㆍ지역보건교육학회지
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• 제16권3호
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• pp.31-40
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• 2015

Objectives: The study investigated constipation in male and female high school students and in order to provide data base for development of education and intervention programs aimed at preventing and managing constipation in high school students. Methods: The study used a technique of convenience sampling to mobilize the entire students in an academic high school in D region. Of the combined 360 copies of questionnaire distributed, 340 copies were collected and used for the final analysis. The gathered data were analyzed using frequency, percentage, and ${\chi}^2-test$ in SPSS 21. Results: The ratio of female students with constipation is significantly higher than that of male students with the condition(${\chi}^2=5.73$, p=0.017), and there were significant differences in exercise habits(${\chi}^2=26.75$, p<0.001), eating habits(${\chi}^2=43.19$, p<0.001), and bowel habits(${\chi}^2=22.96$, p<0.001) between female students and male students. Also there was significant difference in water intake between the normal group and the constipation group(${\chi}^2=10.01$, p=0.040). Significant differences between the two groups were also discovered in the level of perception of constipation(${\chi}^2=98.76$, p<0.001), bowel movement time(${\chi}^2=15.74$, p=0.008), and use of laxatives(${\chi}^2=17.68$, p<0.001) and enema(${\chi}^2=16.97$, p<0.001) for constipation relief. Conclusions: To prevent and manage constipation in high school students, education about healthy dietary, and bowel habits is required. Also there is an urgent need to improve the school toilet environment in order to respect the rights of students to void or defecate when necessary, a process which will require involvement of students, teachers, and other school staff.

• 한국조경학회지
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• 제32권5호
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• pp.129-138
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• 2004

Cherishing the dead is based in sadness. Designing a memorial space therefore has an inherent challenge to evoke the feeling that is so personal and varied by providing a physical space. The tendency of memorials, especially in the US after the mid 20th century, has been to emphasis each dead individual, as seen at the Vietnam Veterans Memorial in Washington, D. C., the Oklahoma City National Memorial in Oklahoma City, and so forth. In the process of designing the memorial of the Taiwanese Chi-chi earth-quake, Cheng Kim Park Robidoux tried to set up a series of spaces through which not only the relatives of the dead but also unrelated visitors could have their own spatial experiences, private rituals and public events, so that they can finally build up a collective memory. Sky-Well consists of a large bamboo forest enclosing a void. Without a particular entrance and guiding system, visitors stroll and get lost in the bamboo forest before they find the central void. The horror they experienced during the earthquake is melted down into the motion and phenomenology of the bamboo forest whereas the central void is reinterpreted as an empty mind, where people find solace from the sky. Details, such as the bamboo wall to place commemorative flowers and lotus blossom paving, are echoing the theme of rebirth.

• Journal of applied mathematics & informatics
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• 제6권1호
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• pp.239-246
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• 1999

The purpose of this paper is to prove the following result: Let R be a 2-torsion free noncommutative semi-prime ring and D:RlongrightarrowR a derivation. Suppose that $[[D(\chi),\chi],\chi]\in$ Z(R) holds for all $\chi \in R$. Then D is commuting on R.

• 대한수학회논문집
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• 제22권2호
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• pp.219-225
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• 2007

Since the time of Euler, the dilogarithm and polylogarithm functions have been studied by many mathematicians who used various notations for the dilogarithm function $Li_2(z)$. These functions are related to many other mathematical functions and have a variety of application. The main objective of this paper is to present corrected versions of two equivalent factorization formulas involving the Legendre's Chi-function $\chi_2$ and an evaluation of a class of integrals which is useful to evaluate some integrals associated with the dilogarithm function.

• Journal of the Korean Data and Information Science Society
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• 제20권3호
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• pp.587-592
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• 2009

The most frequent use of the chi-square distribution is in the area of goodness-of-t of a distribution. The likelihood ratio test is a commonly used test statistic as the maximum likelihood estimate in statistical inferences. The recently revised versions of the likelihood ratio test statistics are used in estimating the parameter in the chi-square distribution. The estimates are compared with the commonly used method of moments and the maximum likelihood estimate.

• Journal of the Korean Statistical Society
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• 제27권2호
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• pp.197-203
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• 1998

To test the hypothesis of complete or total independence for a multi-way contingency table, the Pearson chi-squared test statistic is usually employed under Poisson or multinomial models. It is well known that, under the hypothesis, this statistic follows an asymptotic chi-squared distribution. We consider the case where all marginal sums of the contingency table are fixed. Using conditional limit theorems, we show that the chi-squared test statistic has the same limiting distribution for this case.