• 환경생물
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• 제24권4호
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• pp.329-336
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• 2006

하계 완도 연안역에 출현하는 동물플랑크톤의 군집양상을 연구하기 위하여 8월 30일에 6개의 정점에서 NORPAC net를 이용하여 수직 채집한 자료를 사용하였다. 동물플랑크톤은 37개 분류군이 출현하였으며,출현 개체수는 $147{\sim}1696\;indiv.\;m^{-3}$의 범위를 나타냈다. 우점종은 E. tergesrina, A. pacifica, P. parvus s. 1, 십각류 유생, S. crassa로서 전체 출현 개체수에 90%이상을 차지하였다. 동물플랑크톤은 세 개의 군집으로 구분되어졌으며, 소안도 인근해역의 A군집, 소안도와 청산도의 중앙부해역인 B군집, 청산도 북부해역의 C군집으로 구분되었다. 군집으로 구분되는 세 그룹간의 동물플랑크톤의 종조성과 출현 개체수는 유의한 차이를 나타냈다(p<0.05). 결과적으로 하계 완도 연안역의 동물플랑크톤 분포는 대마난류와 황해저층냉수의 확장에 의해 지배되고 있음을 암시하고 있다.

• 대한환경공학회지
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• 제33권7호
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• pp.501-510
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• 2011

한강의 주요 14개 지류하천 유역의 수질오염원을 평가하고, 2007. 1~2009. 12의 하천 수질자료(14 data set)로 SPSS-17.0을 이용하여 하천별 수질 특성을 평가하였다. 시 공간변화에 대한 군집 분석을 실시한 결과 공간변화에 따라 4그룹으로 평가되었으며, 유역의 오염원 종류 및 밀도가 군집분류에 가장 큰 영향을 미치는 것으로 나타났다. 시간변화에 따라 여름에서 가을까지(7~10월)와 겨울에서 초여름까지(11~6월)의 2그룹으로 분류되어 강우와 기온 그리고 부영양화 현상이 군집화에 기여하는 것으로 평가되었다. 조사대상 하천의 수질오염 요인은 유기물질 영양염류 세균오염요인과 하천 내 물질대사요인으로(71~90%) 설명되었고, 계절에 따라 주요인(수질오염물질)은 변화하는 것으로 나타났다. 각 하천의 수질특성은 요인과 유역 오염원을 같이 평가하였을 때 유용한 결과를 얻을 수 있었다.

• 한국의료질향상학회지
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• 제7권2호
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• pp.218-228
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• 2000

Background : Among 'structure', 'process' and 'outcome' approaches, outcome evaluation is considered as the most direct and best approach to assess the quality of health care providers. Risk-adjustment is an essential method to compare outcome across providers. This study has aims to judge performance of hospitals by severity adjusted mortality rates of coronary artery bypass graft (CABG) surgery. Methods : Medical records of 584 patients who got the CABG surgery in 6 general hospitals during 1996 and 1997 were reviewed by trained nurses. The MedisGroups was used to quantify severity of patients. The predictive probability of death was calculated for each patient in the sample from a multivariate logistic regression model including the severity score, age and sex. For evaluation of hospital performance, we calculated ratio of observed number to expected number of deaths and z score [(observed number of deaths - expected number of deaths)/square root of the variance in the number of deaths], and compared observed mortality rate with confidence interval of adjusted mortality rate for each hospital. Results : The overall in-hospital mortality was 7.0%, ranged from 2.7% to 15.7% by hospital. After severity adjustment the mortality by hospital was from 2.7% to 10.7%. One hospital with poor performance was distinctly divided from others with good performance. Conclusion : In conclusion, severity-adjusted mortality rate of CABG surgery might be applied as an indicator for hospital performance evaluation in Korea. But more pilot studies and improvement of methodologies has to be done to use it as quality indicator.

• 한국산학기술학회논문지
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• 제1권2호
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• pp.85-92
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• 2000

Warrant란 소유자에게 일반회사채의 권리에 일정한 기간내에 일정한 가격으로 정해진 수의 발행회사 주식을 매입할 수 있는 권리인 신주인수권을 함께 부여한 사채로서 금융파생상품의 하나이다. Warrant는 콜옵션과 동일한 성격을 가지면서도 투자자가 아니라 기업에 의해서 발행된다는 점이 콜옵션과 상이하다. 이러한 warrant의 특징은 특히 배당(dividend)을 지급하는 경우 블랙ㆍ숄즈 옵션가격 모형으로 평가하는데 문제가 있다. 또한 신주인수권의 행사는 발행주식의 수를 증가 시킴으로써 기업의 자산과 이익이 희석화(dilution) 된다. 본 연구는 OPM 대신에, 다변량 분석기법중의 하나인 다중회귀분석을 통하여 warrant가격에 영향을 미치는 주요 변수를 분석함으로써 warrant 가격결정 문제를 해결하고자 한다. 이를 위하여 1995년과 1996년의 일본동경주식시장의 300여개 warrant 자료를 토대로 실증분석 함으로써 warrant 가격결정 주요변수와 warrant 가격 예측 모형을 검토하였다.

• Journal of Preventive Medicine and Public Health
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• 제42권5호
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• pp.283-292
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• 2009

Objectives : This study was performed to assess the community capacity building ability of health promotion workers of public health centers and to identify influential factors to the ability. Methods : The subjects were 43 public officers from 16 public health centers in Busan Metropolitan City. Questionnaire was developed based on 'Community Capacity Building Tool' of Public Health Agency of Canada which consists of 9 feathers. Each feather of capacity was assessed in 4 point rating scale. Univariate analysis by characteristics of subjects and multivariate analysis by multiple regression was done. Results : The mean score of the 9 features were 2.35. Among the 9 feathers, 'Obtaining resources' scored 3.0 point which was the highest but Community structure scored 2.1 which was the lowest. The mean score of the feathers was relatively lower than that of Canadian data. The significant influential factors affecting community capacity building ability were 'Service length', 'Heath promotion skill level', 'Existence of an executive department', and 'Cooperative partnership for health promotion'. According to the result of multiple linear regression, the 'Existence of an executive department' had significant influence. Conclusions : Community capacity building ability of subjects showed relatively lower scores in general. Building and activating an executive department and cooperative partnerships for health promotion may be helpful to achieve community capacity building ability.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.14-14
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• 2017

The discipline of plant breeding is experiencing a renaissance impacting crop improvement as a result of new technologies, however fundamental questions remain for predicting the phenotype and how the environment and genetics shape it. Inexpensive DNA sequencing, genotyping, new statistical methods, high throughput phenotyping and gene-editing are revolutionizing breeding methods and strategies for improving both quantitative and qualitative traits. Genomic selection (GS) models use genome-wide markers to predict performance for both phenotyped and non-phenotyped individuals. Aerial and ground imaging systems generate data on correlated traits such as canopy temperature and normalized difference vegetative index that can be combined with genotypes in multivariate models to further increase prediction accuracy and reduce the cost of advanced trials with limited replication in time and space. Design of a GS training population is crucial to the accuracy of prediction models and can be affected by many factors including population structure and composition. Prediction models can incorporate performance over multiple environments and assess GxE effects to identify a highly predictive subset of environments. We have developed a methodology for analyzing unbalanced datasets using genome-wide marker effects to group environments and identify outlier environments. Environmental covariates can be identified using a crop model and used in a GS model to predict GxE in unobserved environments and to predict performance in climate change scenarios. These new tools and knowledge challenge the plant breeder to ask the right questions and choose the tools that are appropriate for their crop and target traits. Contemporary plant breeding requires teams of people with expertise in genetics, phenotyping and statistics to improve efficiency and increase prediction accuracy in terms of genotypes, experimental design and environment sampling.

• 한국주거학회논문집
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• 제24권5호
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• pp.49-56
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• 2013

The goal of this research is to explore quantitative and residential features and spatial patterns of two-person households to suggest policy implications for housing supply and development in Seoul. Major findings of this study are as follows. First, the number of two-person households has increased rapidly mainly due to the growth of the elderly and single-parent households. They are mainly composed of the elderly over 60s and the youth of 30s of householder age. They are less likely to have well-paying jobs, and thus more likely to suffer from poverty. They are also inclined to live in rental and small-sized residential units and spatial segregation between the youth and the elderly became serious. In addition, their residential area can be classified into four types: area adjacent to employment centers, hinterland of urban centers, affordable multi-family housing area and redeveloped apartment area. It is necessary to change the current housing policy directions to take changing population and household structure into consideration. Also, diversified housing strategies and programs should be prepared to consider various household types and their needs and demands. Place-based strategies for housing supply and development are needed in consideration of spatial patterns and locational attributes of two-person households. Attention needs to be paid to resolving the social issue of residential segregation between different generations.

• 대한기계학회논문집A
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• 제35권8호
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• pp.921-931
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• 2011

본 연구는 B-스플라인 하이퍼볼륨을 사용하여 주어진 비정렬 데이터를 근사화하는 데이터 근사기법에 관한 것이다. 개발 구현을 위한 B-스플라인 하이퍼볼륨의 자료 구조가 기술되며 해당 메모리 크기의 측정을 통해 간결한 표현 모델임을 보인다. 제안하는 근사 기법은 두 가지 알고리즘으로 구성된다. 하나는 B-스플라인 하이퍼볼륨의 절점 벡터 결정에 관한 것이고, 다른 하나는 조정점 결정에 관한 것으로 최소자승 최소화 문제의 해를 구함으로써 얻게 된다. 여기서 구한 해는 데이터 복잡성에 의존하지 않는다. 본 연구 방식은 다양한 형태의 데이터 분포를 가지고 근사 정밀도, 메모리 사용량, 계산 시간 등의 근사화 성능(수준)을 평가한다. 더불어 기존 방법과의 비교를 통해 유용성을 보이며, 비구속 최적화 예제를 통하여 다양한 응용 분야로의 가능성을 보여준다.

• 디지털융복합연구
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• 제18권2호
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• pp.261-268
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• 2020

기계학습은 주어진 디지털 신호 Data로부터 비용함수를 만들고, 그 비용함수를 최소화함으로 학습이 이루어진다. 비용함수는 디지털 신호 Data의 양과 인공신경망의 구조에 따라 비용함수에 부분 최솟값(local minimum)들이 생기게 된다. 비용함수의 부분 최솟값들은 학습을 방해하는 요소가 된다. 이러한 방법을 해결하는 여러 방법 중 우리의 제안 방법은 학습률(Step-size)을 변화시키는 방법이다. 학습률을 고정된 상수로 이용하는 기존의 방법과는 다르게 비용함수를 이용한 다변수함수를 이용함으로써 불필요한 기계학습이 이루어지는 것을 방지할 수 있으며, 최솟값으로 가는 최적의 길을 찾을 수 있다. 수치적 실험을 통하여 기존의 방법보다 우리가 제안하는 방법을 이용하여 약 3%(88.8%→91.5%)의 성능이 향상하는 결과를 얻었다.

• International Journal of Aeronautical and Space Sciences
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• 제13권1호
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• pp.14-26
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• 2012

The only extraterrestrial life detection experiments ever conducted were the three which were components of the 1976 Viking Mission to Mars. Of these, only the Labeled Release experiment obtained a clearly positive response. In this experiment $^{14}C$ radiolabeled nutrient was added to the Mars soil samples. Active soils exhibited rapid, substantial gas release. The gas was probably $CO_2$ and, possibly, other radiocarbon-containing gases. We have applied complexity analysis to the Viking LR data. Measures of mathematical complexity permit deep analysis of data structure along continua including signal vs. noise, entropy vs.negentropy, periodicity vs. aperiodicity, order vs. disorder etc. We have employed seven complexity variables, all derived from LR data, to show that Viking LR active responses can be distinguished from controls via cluster analysis and other multivariate techniques. Furthermore, Martian LR active response data cluster with known biological time series while the control data cluster with purely physical measures. We conclude that the complexity pattern seen in active experiments strongly suggests biology while the different pattern in the control responses is more likely to be non-biological. Control responses that exhibit relatively low initial order rapidly devolve into near-random noise, while the active experiments exhibit higher initial order which decays only slowly. This suggests a robust biological response. These analyses support the interpretation that the Viking LR experiment did detect extant microbial life on Mars.