• The Journal of the Acoustical Society of Korea
• /
• v.20 no.7
• /
• pp.94-100
• /
• 2001

When using a sample covariance matrix data in paucity of snapshots, adaptive matched field processing will have problem in inverting covariance matrix due to the rank deficiency. The general solutions are diagonal loading and eigenanalysis methods, but there is a significant bias in the power output. This paper presents a quantitative study of bias of power output and the performance of source localization through the simulation and the measured data analysis in fixed source case using the diagonal loading method for the minimum variance processor. Results show that the bias in power output is reduced and the performance of source localization is improved when the number of snapshots is greater than the number of array sensors.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.14 no.3
• /
• pp.111-117
• /
• 2014

In this paper I propose a simple optimal solution seeking algorithm to a stable marriage problem. The proposed algorithm firstly constructs an $n{\times}n$ matrix of the sum of each gender's preference of the other gender $p_{ij}$. It then selects the minimum sum preference $_{min}p_{ij}$ in the constructed matrix and deletes its corresponding row i and column j. This process is repeated until $i=0{\cap}j=0$, after which the algorithm compares initially or last chosen $_{min}p_{ij}$ its alternatives to finally determine one that yields the maximum marginal increase in preference. When applied to 7 stable marriage problems, the proposed algorithm has improved on initial solutions of existing algorithms.

• The Korean Journal of Applied Statistics
• /
• v.33 no.6
• /
• pp.683-696
• /
• 2020

The aim of this research is to find an optimal gene set that provides highly accurate multi-class classification with a minimum number of genes. A two-stage procedure is proposed: Based on minimum redundancy and maximum relevance (mRMR) framework, several statistics to rank differential expression genes and K-means clustering to reduce redundancy between genes are used for data filtering procedure. And a particle swarm optimization is modified to select a small subset of informative genes. Two well known multi-class microarray data sets, ALL and SRBCT, are analyzed to indicate the effectiveness of this hybrid method.

• Journal of Astronomy and Space Sciences
• /
• v.38 no.1
• /
• pp.23-29
• /
• 2021

Utilizing a new version of the sunspot number and group sunspot number dataset available since 2015, we have statistically studied the relationship between solar activity parameters describing solar cycles and the slope of the linear relationship between the monthly sunspot numbers and the monthly number of active days in percentage (AD). As an effort of evaluating possibilities in use of the number of active days to predict solar activity, it is worthwhile to revisit and extend the analysis performed earlier. In calculating the Pearson's linear correlation coefficient r, the Spearman's rank-order correlation coefficient rs, and the Kendall's τ coefficient with the rejection probability, we have calculated the slope for a given solar cycle in three different ways, namely, by counting the spotless day that occurred during the ascending phase and the descending phase of the solar cycle separately, and during the period corresponding to solar minimum ± 2 years as well. We have found that the maximum solar sunspot number of a given solar cycle and the duration of the ascending phase are hardly correlated with the slope of a linear function of the monthly sunspot numbers and AD. On the other hand, the duration of a solar cycle is found to be marginally correlated with the slope with the rejection probabilities less than a couple of percent. We have also attempted to compare the relation of the monthly sunspot numbers with AD for the even and odd solar cycles. It is inconclusive, however, that the slopes of the linear relationship between the monthly group numbers and AD are subject to the even and odd solar cycles.

• International Journal of Computer Science & Network Security
• /
• v.22 no.4
• /
• pp.159-168
• /
• 2022

The recent outbreak of COVID-19 pandemic cases around the globe has affected Saudi Arabia with around 15, 00,000 confirmed cases within the initial 4 months of transmission. The present investigation analyzed the relationship between daily COVID-19 confirmed cases and meteorological parameters in seventeen cities of KSA. We used secondary published data from the Ministry of Health, KSA daily dataset of COVID-19 confirmed case counts. The meteorological parameters used in the present investigation are temperature, humidity, dew point, and wind speed. Pearson correlation and Spearman rank correlation tests were utilized for data analysis. The incubation period of COVID-19 varies from 1 day to 14 days as per available information. Therefore, an attempt has been made to analyze the effects of meteorological factors with bins of 1, 3, 7, and 14 days. The results suggested that the highest number of correlations (15 cities) was observed for temperature (maximum, minimum, and average) and humidity (12 cities) (minimum and average). The dew point showed relationships for 7 cities and wind showed moderate correlations only for 2 cities. The study results might be useful for authorities and stakeholders in taking specific measures to combat the Covid-19 pandemic.

• Journal of applied mathematics & informatics
• /
• v.36 no.5_6
• /
• pp.359-368
• /
• 2018

In this paper, we investigate quasi-cyclic codes over the ring $R={\mathbb{F}}_2+v{\mathbb{F}}_2$, where $v^2=v$. We investigate the structure of generators for one-generator quasi-cyclic codes over R and their minimal spanning sets. Moreover, we find the rank and a lower bound on minimum distances of free quasi-cyclic codes over R. Further, we find a relationship between cyclic codes over a different ring and quasi-cyclic codes of index 2 over R.

• Communications for Statistical Applications and Methods
• /
• v.13 no.1
• /
• pp.29-38
• /
• 2006

We proposed a procedure for detecting of multiple outliers in multivariate data. Rousseeuw and van Zomeren (1990) have suggested the robust distance $RD_i$ by using the Resampling Algorithm. But $RD_i$ are based on the assumption that X is in the general position.(X is said to be in the general position when every subsample of size p+1 has rank p) From the practical points of view, this is clearly unrealistic. In this paper, we proposed a computing method for approximating MVE, which is not subject to these problems. The procedure is easy to compute, and works well even if subsample is singular or nearly singular matrix.

• Proceedings of the Korean Information Science Society Conference
• /
• 2006.10d
• /
• pp.677-680
• /
• 2006

이 논문은 무선 센서 네트워크에서 최소 파워 구성 방법을 이용하여 에너지를 효율적으로 사용하면서 네트워크의 수명을 늘리고 지연(delay)을 줄이는 방안을 제시한다. 지금까지 에너지를 효율적으로 사용하기 위해 topology control, power-aware routing, sleep management 방법을 각각 독립적으로 연구되었는데 최소파워 구성은 위의 3가지 방법을 통합 최적화하여 에너지 효율적 사용 문제에 접근한다. 이러한 최소파워 구성 방법을 이용하여 선택적 웨이트 컨트롤(Selective weight control) 알고리즘을 제안하여 네트워크 전체 수명을 연장시키고 지연을 줄일 수 있다. 이 알고리즘은 각 노드가 주기적으로 잔류에너지를 인접노드들과 공유하여 에너지 랭크(rank)값을 유지한 상태에서 최소 에너지 경로를 사용하면서 에너지가 주위 노드들보다 작아질 때는 에너지가 많은 노드가 경로에 포함이 되도록 하여 특정 노드가 에너지 고갈되지 않고 네트워크내의 각 노드가 고르게 에너지를 소모하게 한다.

• Proceedings of the Korean Information Science Society Conference
• /
• 2005.11b
• /
• pp.745-747
• /
• 2005

수많은 웹페이지들이 하이퍼링크를 통해 복잡하게 연결된 그래프 구조를 가지고 있는 웹사이트를 계층적으로 구조화하는 것은 해당 사이트를 검색하고자 할 때, 정보를 재조직화하고 고려해야 할 대안들의 개수를 감소시킨다는 점에서 매우 유용하다. 본 논문은 웹사이트의 의미론적인 계층화를 최적화하기 위하여 사용자의 순회 경로, 즉 웹아크의 중요도 합을 최대화할 수 있는 트리 구조를 생성하였다. 구체적으로 첫째 PageRank에 기반한 웹아크 중요도를 생성하였고, 둘째 Minimum-Cost Arborescence 문제를 이용하여 최적 트리 구조를 생성하였다. 사용자의 질의에 독립적으로 생성된 트리 구조는 웹사이트의 의미 있는 계층 구조로서 사용자로 하여금 해당 사이트를 보다 효과적으로 검색할 수 있도록 도와줄 것이다.

• Journal of Korean Society of Forest Science
• /
• v.96 no.2
• /
• pp.145-150
• /
• 2007

This study was conducted to elucidate the mid-growth of Norway spruce at the age of 27 and select the superior provenances in Korea. Growth performance of twenty-four provenances from Germany and Rumania were investigated in four plantations. Significant differences were found in growth (height, DBH, volume) with plantations. Maximum growth were detected on plantation Chuncheon which located in most northern area, and minimum growth were detected on plantation Wanju located in most southern area. The rank of height in provenances has fluctuated, but superior/inferior groups have been almost fixed. 840-23, 840-10, 840-19 in Germany, G1-64-57, G1-64-54 in Rumania proved excellent provenances. Height in early stage positively correlated with that in late stage. The growth was positively correlated with latitude and altitude of plantations, but negatively correlated with temperature.