• Science of Emotion and Sensibility
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• v.26 no.4
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• pp.3-14
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• 2023

Recently, the effect of using social media on psychological well-being has been highlighted. However, studies exploring factors that may predict the quality of social media relationships are relatively rare. The present study investigated whether social media activity and psychological states, such as loneliness and depression, can predict the quality of social media relationships during the COVID-19 quarantine period using a machine learning technique. Ninety-five participants completed a self-report survey on loneliness, Instagram activity, quality of social media relationships, and depression at different time points (during the self-isolation and after the release of self-isolation). Similarity analyses, including multidimensional scaling (MDS), representational similarity analysis (RSA), and classification analyses, were conducted separately at each point in time. The results of MDS revealed that time spent on social media and depression were distinguished from others in the first dimension, and loneliness and passive use were distinguished from others in the second dimension. We divided the data into two groups based on the quality of social media relationships (high and low), and we conducted RSA on each group. Findings indicated an interaction between the quality of the social media relationships and the situation. Specifically, the effect of self-isolation on the high-quality social media relationship group is more pronounced than that on the low-quality group. The classification results also revealed that the predictors of social media relationships depend on whether or not they are isolated. Overall, the results of this study imply that social media relationship could be well predicted when people are not in isolated situations.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.881-881
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• 2012

낙동강유역에는 4대강 사업으로 8개의 보가 낙동강 본류에 새롭게 설치되었으며, 따라서 상류로부터 유입되는 유사가 보상류에 퇴적되어 하천제방이나 하천구조물의 안전을 위협할 수 있다. 또한 홍수시에는 농경지의 매몰과 저수지의 퇴적현상이 발생하는 등 유역유사에 의한 다양한 문제가 발생할 수 있으며, 강우로부터 유출되는 유사는 강우사상에 따라 빠르게 변할 수 있으나 수체에 즉각적인 영향을 유발하지 않을 경우 만성적인 특성으로 인해 침전물을 계속 이동시키며 축적되는 문제가 발생한다. 따라서 이러한 문제를 사전에 예측하고 낙동강유역에 대한 유역유사관리 대책마련을 마련하기 위해 유역유출과 유사의 이송 및 퇴적양상을 분석하여 유역관리를 위한 자료를 구축할 필요가 있다. 이러한 기초자료 분석을 위해 활용되는 유역모형 중 SWAT(Soil and Water Assessment Tool) 모형은 장기간 유역 유출로 인한 유사 모의를 수행하는데 가장 많이 활용되는 모형이며, 미국 농무성 농업연구소(USDA Agricultural Research Service, ARS)의 Jeff Amold 등에 의해 개발된 모형이다. SWAT 모형은 장기유출 및 유사 발생에 대한 시 공간적 변화를 모의하는 모형으로 넓은 범위의 유역에 대해 일단위 모의 간격으로 최대 100년까지 모의가 가능한 장기유역 모의에 최적화된 모형이다. 본 논문에서는 SWAT 모형을 이용하여 낙동강유역의 장기 유역 유출 및 유사 모의를 수행하기위해 2004년에서 2009년까지의 유출량 자료와 유량-유사량관계곡선 등을 이용하여 본류 및 지류 유출구 주요지점에 대해 검보정을 수행하고자 한다. 모의의 정확도 향상을 위해 안동댐, 임하댐, 영천댐, 합천댐, 남강댐, 밀양댐 및 낙동강 본류 등 총 7개 유역으로 구분하여 SWAT 모형을 구축하였으며, 각 유역별로 유출량과 유사량에 대하여 각각 보정 및 검증을 수행하였다. 낙동강 본류유역 총 7개의 댐 방류량자료와 20개의 대형하수종말처리장 방류량자료를 이용한 낙동강유역의 유출량 보정 및 검증 결과, 모의치가 실측치를 잘 반영하고 있는 것으로 나타났다. 또한 총 11개 지점의 수위관측소에 대해 유사량 측정 성과를 이용한 유사량 보정 및 검증 결과, 강우시 유사량 모의값은 유출량-유사량관계곡선 식을 잘 반영하였으나, 비강우시에는 모의값이 관계곡선 식의 결과값보다 대체적으로 높게 나타났다.

• The Korean Journal of Applied Statistics
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• v.30 no.4
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• pp.567-578
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• 2017

Grouped multivariate data can be tested for differences between two or more groups using multivariate analysis of variance (MANOVA). However, this method cannot be used if several assumptions of MANOVA are violated. In this case, multidimensional scaling (MDS) and analysis of distance (AOD) can be applied to grouped dissimilarities based on the various distances. A permutation test is a non-parametric method that can also be used to test differences between groups. MDS is used to calculate the coordinates of observations from dissimilarities and AOD is useful for finding group structure using the coordinates. In particular, AOD is mathematically associated with MANOVA if using the Euclidean distance when computing dissimilarities. In this paper, we study the between and within group structure by applying MDS and AOD to the grouped dissimilarities. In addition, we propose a new test statistic using the group structure for the permutation test. Finally, we investigate the relationship between AOD and MANOVA from dissimilarities based on the Euclidean distance.

• Management & Information Systems Review
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• v.32 no.4
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• pp.81-101
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• 2013

The purpose of this study was to examine the effects of mental similarity and internal locus of control, which are the characteristics of an organizational member, and individualism and power distance, which are an individual's sense of value, on mentoring function in an informal mentoring relationship of ROK army. For corroborative analysis, the sample was collected from 547 questionnaires, which contain validate data out of 1,000 questionnaires distributed to junior officers working at ROK army's division level unit. The data proved that, First, mental similarity and internal locus of control positively effected upon mentoring function. Second, individualism positively effected upon mentoring function while power distance had a negative effect on it. Thus in an informal mentoring relationship of ROK army, a mentee perceived as he or she gains more support from mentoring function when a mentee recognizes higher mental similarity, individualism, and is in an internal locus of control. On the other hand, a mentee who perceived higher power distance felt as he or she gets less support from mentoring function. Through this investigation, the significance of influential components of mentoring function in a mentoring relationship of ROK army was demonstrated, and these research results could be highly supportive for a future research based on mentoring relationship.

• Journal of the Korean Institute of Intelligent Systems
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• v.18 no.1
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• pp.139-144
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• 2008

Generally, real system that is the object of decision-making is very variable and sometimes it lies situations with uncertainty. To solve these problem, it has used statistical methods as significance level, certainty factor, sensitivity analysis and so on. In this paper, we propose a method for fuzzy decision-making based on MFAC(Multiple Fuzzy Alpha Cut) to improve the definiteness of classification results with similarity evaluation. In the proposed method, MFAC is used for extracting multiple a ${\alpha}$-level with proximity degree at proximity relation between relative Hamming distance and max-min method and for minimizing the number of data which are associated with the partition intervals extracted by MFAC. To determine final alternative of decision-making, we compute the weighted value between extracted data by MFAC From the experimental results, we can see the fact that the proposed method is simpler and more definite than classification performance of the conventional methods and determines an alternative efficiently for decision-maker by testing significance of sample data through statistical method.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.56 no.4
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• pp.322-328
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• 2011

AFLP markers were employed to detect genetic diversity and genetic relationship among 26 accessions of foxtail millet collected from Korea. Analysis of 26 accessions of foxtail millet with nine AFLP primer set combinations detected a total of 170 bands, of which 145 (85.3%) showed polymorphic at the species level. The phenotypic diversity (Hs) calculated for the nine primer combinations ranged from 1.84 to 6.8, with an average of 3.85. The average phenotypic diversity values were 3.39 and 2.99 for accessions collected from Gangwon province (Group 1), and accessions collected from the other areas including Gyeonggi province (Group 2), respectively. In the cluster analysis of 26 accessions, two major groups were recognized at 73% genetic similarity. Group I includes 13 accessions, which were collected in Gangwon province, and 1 accession, which was collected in Gyeonggi province, with genetic similarity of 76.8%. Group II includes two accessions, which were collected in Gangwon province, and 10 accessions, which were collected in the other areas with genetic similarity of 78.9%. The presenting data on the assessment of genetic diversity and genetic relationships among Korean accessions of foxtail millet will be helpful for efficient collection or conservation strategy of foxtail millet germplasm in Korea.

• Proceedings of the Korea Multimedia Society Conference
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• 2002.05d
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• pp.1063-1068
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• 2002

공간 관계는 이미지나 멀티미디어 데이터를 검색하기 위한 시스템에서 오브젝트들을 표현하는데 중요한 요소이다. 본 논문에서는 기존의 검색 방식과 다르게 이미지에 있는 여러 오브젝트들간의 공간 관계와 각 오브젝트들이 가지고 있는 특징을 이용한 새로운 방식의 이미지 데이터 검색기법을 제안한다. 이것은 질의와 데이터베이스 내에 있는 이미지들간의 유사성을 효율적으로 계산하는데 유용하다. 또한 각 오브젝트의 공간정보와 특징들에 대한 정보들이 XML형태로 주석 처리되어 있기 때문에 이전 검색 기법보다 정확도가 높다. 마지막으로 제안한 검색기법을 이용한 이미지 검색 시스템을 구현하여, 실제 데이터를 검색함으로써 성능을 평가하였다.

• 한국해양학회지
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• v.22 no.4
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• pp.228-235
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• 1987

Based on the hydrographic data for 19 years (1968-1984) at 65 stations in the West Sea of Korea, we investigate the relationships between the sea surface temperature (SST) in winter and the bottom water temperature (BWT) in summer. The spatially-averaged anomalies of BBT are highly correlated with those of SST during the preceding winter. However, due to advection of heat by ocean currents, the spatial pattern of BWT anomaly in summer does not closely resemble that of SST anomaly in the preceding winter.

• Proceedings of the Korea Information Processing Society Conference
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• 2005.05a
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• pp.19-22
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• 2005

XML은 비즈니스 메시징, 웹사이트 정보 통합, 그리고 카탈로그 통합 등의 분야에서 다양한 데이터를 표현하기 위한 포맷으로 급격하게 성장했다. 그러나 XML 데이터의 형태가 고정되어 있지 않기 때문에 전통적인 질의 방법이 항상 정확한 결과를 보여주지는 않는다. 또한 객체 지향 DBMS가 이 영역에 적합한지의 여부는 아직 명확하지 않다. 따라서 XML 데이터를 효율적으로 검색하기 위해 기존의 관계형 DBMS와 연계하여 구조 유사성을 기반으로 하는 검색 기법이 연구되고 있다. 그 중 문서, 경로, 단어로 구성된 3차원 비트맵 인덱스를 이용한 검색 시스템은 다른 XML 문서 검색 시스템보다 훨씬 빠른 수행 속도를 보여주지만, 3차원의 메모리 구조를 사용하여 많은 저장공간을 필요로 하는 단점이 있다. 본 논문에서는 XML 문서를 저장할 때 경로들 사이의 유사성을 이용하여 XML 데이터의 경로를 통합하는 기법에 대해 소개한다. 이렇게 통합된 경로를 이용하여 생성하는 3차원 비트맵 인덱스는 그 크기가 상당히 줄어들게 되고, 기존의 연구에서 보여주었던 문제점들을 해결하게 되었다.

• Management & Information Systems Review
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• v.35 no.3
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• pp.115-130
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• 2016

This study aims to identify which social information have significant influence on the improvement of recommendation trust and how these effects can be different according to the product involvement level. Based on the relevant literature reviews, this study posits four characteristics of recommendation trust, which are closeness, similarity, sincerity, and reputation, and established a research model for the relationship between social information and recommendation trust. And we found a moderating effect of product involvement on the relationship between social information and recommendation trust. 205 trust relationships(links) from 55 respondents of Google Docs. survey data have been collected and tested using multiple regression and hierarchical regression analysis. The results of our hypotheses testing are summarized as follows. Firstly, four social information characteristics of closeness, similarity, sincerity, and reputation have a significantly positive effect on recommendation trust. Secondly, a moderating effect of product involvement between recommendation trust and antecedents (e.g., closeness and reputation) of social information is significant. From the results, we provide theoretical and managerial implications, and suggestions for further research.