• Clinical and Experimental Emergency Medicine
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• 제5권4호
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• pp.230-239
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• 2018

Objective The suicide rate in South Korea is very high and is expected to increase in coming years. Intoxication is the most common suicide attempt method as well as one of the common reason for presenting to an emergency medical center. We used decision tree modeling analysis to identify predictors of risk for suicide by intentional intoxication. Methods A single-center, retrospective study was conducted at our hospital using a 4-year registry of the institute from January 1, 2013 to December 31, 2016. Demographic factors, such as sex, age, intentionality, therapeutic adherence, alcohol consumption, smoking status, physical disease, cancer, psychiatric disease, and toxicological factors, such as type of intoxicant and poisoning severity score were collected. Candidate risk factors based on the decision tree were used to select variables for multiple logistic regression analysis. Results In total, 4,023 patients with intoxication were enrolled as study participants, with 2,247 (55.9%) identified as cases of intentional intoxication. Reported annual percentages of intentional intoxication among patients were 628/937 (67.0%), 608/1,082 (56.2%), 536/1,017 (52.7), 475/987 (48.1%) from 2013 to 2016. Significant predictors identified based on decision tree analysis were alcohol consumption, old age, psychiatric disease, smoking, and male sex; those identified based on multiple regression analysis were alcohol consumption, smoking, male sex, psychiatric disease, old age, poor therapeutic adherence, and physical disease. Conclusion We identified important predictors of suicide risk by intentional intoxication. A specific and realistic approach to analysis using the decision tree modeling technique is an effective method to determine those groups at risk of suicide by intentional intoxication.

• 한국산림과학회지
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• 제68권1호
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• pp.11-17
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• 1985

지위지수(地位指數)의 사정(査定)의 기초(基礎)가 되는 수고생장곡선(樹高生長曲線)을 작성(作成)하기 위하여 수고(樹高)(H)를 수령(樹令)(A)의 함수(凾數)로 표시(表示)한 10개(個)의 모형(模型)을 수용(授用)한 결과(結果) $H=K-ab^A$식(式)이 가장 적합(適合)한 것으로 나타났다. 이 모형(模型)에 따라 낙엽송림(林)의 수고추정식(樹高推定式) $H=28.364-26.125(0.818)^A$ ($R^2=0.999$)와 잣나무림(林)의 수고추정식(樹高推定式) $H=26.331-25.125(0.886)^A$ ($R^2=0.999$)를 각각 도출(導出)하였다 그 다음, 추정(推定)된 수고생장곡선(樹高生長曲線)에 의하여 Bryant 법(法)의 계산과정(計算過程)을 거쳐 두 수종(樹種)의 지위지수표(地位指數表) 및 지위지수곡선(地位指數曲線)을 작성(作成)하고, 이를 비교(比較)하여 보면 지위지수급(地位指數級) 6-18에서는 낙엽송이 잣나무보다 높게 추정(推定)되고, 지위지수급(地位指數級) 20에서는 잣나무가 낙엽송보다 다소 높게 추정(推定)되었다.

• 대한안전경영과학회지
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• 제16권4호
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• pp.275-284
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• 2014

Decision Tree is one of analysis techniques which conducts grouping and prediction into several sub-groups from interested groups. Researcher can easily understand this progress and explain than other techniques. Because Decision Tree is easy technique to see results. This paper uses CART algorithm which is one of data mining technique. It used 273 variables and 70094 data(2010-2011) of working environment survey conducted by Korea Occupational Safety and Health Agency(KOSHA). And then refines this data, uses final 12 variables and 35447 data. To find satisfaction factor in working environment, this page has grouped employee to 3 types (under 30 age, 30 ~ 49age, over 50 age) and analyzed factor. Using CART algorithm, finds the best grouping variables in 155 data. It appeared that 'comfortable in organization' and 'proper reward' is the best grouping factor.

• International Journal of Advanced Culture Technology
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• 제10권2호
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• pp.28-33
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• 2022

This study aims to investigate factors that affect elderly poverty based on a comprehensive and universal perspective, suggesting some alternatives for improving the poverty rate of the elderly. The comprehensive and universal approach to the poverty of the aged that this study attempts can give a better understanding of the elderly poverty beyond the contribution of the existing literature, with the research model including individual, family, labor, and income factors as the causes of old-age poverty from the comprehensive and universal perspective on the causes of poverty of the elderly. In addition, the study attempts to input variants of variables into the equation for the causes of elderly poverty by using panel data from the 8th Korean Retirement and Income Study. This study employs decision tree analysis to determine the cause of the poverty of the elderly using CHAID. The decision tree analysis shows that the most vital variable affecting elderly poverty is making income. For the poor elderly without earned income, public pensions, educational careers, and residential areas influence elderly poverty, but for the poor elderly with earned income, wage earners and gender are variables that affect poverty. This study suggests some alternatives to improve the poverty rate of the aged. The government should create a better working environment such as senior re-employment for old people to be able to participate in economic activities, improve public pension or social security for workers with unfavorable conditions for public security of old age, and give companies that create employment of the aged diverse incentives.

• 한국산림과학회지
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• 제111권3호
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• pp.394-404
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• 2022

본 연구는 우리나라의 가로경관 및 관상 목적으로 활용되는 주요 중형 조경수인 왕벚나무를 대상으로 컨테이너 재배 점적 관수 시 관수량에 따른 4년생, 8년생 묘목의 생장 및 생리 특성을 평가하여, 왕벚나무 컨테이너 재배를 위한 적정관수 기준을 제시하고자 수행되었다. 연구 결과 관수량 처리에 따른 묘고와 근원직경의 상대생장률의 경우 왕벚나무 4년생은 288 L/year/tree 처리에서 8년생은 416 L/year/tree 처리에서 가장 높은 값을 나타내었다. 물질생산량과 묘목품질지수 또한 두 연생 모두 관수처리에 따른 유의적인 차이를 보이면서 4년생은 288 L/year/tree 처리에서 8년생은 416 L/year/tree 처리에서 양호한 생장을 보였다. 뿌리발달 특성 중 총뿌리길이, 평균뿌리직경, 뿌리부피는 두 연생 모두 관수량 처리에 대해 차이를 보였다. 엽록소함량의 경우 왕벚나무 4년생은 288 L/year/tree 처리에서 8년생은 416 L/year/tree처리에서 가장 높은 활성을 보였다. 본 연구결과를 종합적으로 고려해 볼 때 컨테이너 재배 시 관수량의 차이는 묘목의 형태적 상대생장률, 물질생장량, 묘목품질, 생리적 반응에 영향을 미치며, 왕벚나무를 컨테이너로 재배 할 시 적절한 관수량은 4년생 묘목 (근원직경 3 cm급)은 288 L/year/tree, 8년생 묘목 (근원직경 7 cm급)은 416 L/year/tree가 적절한 것으로 판단된다.

• Communications for Statistical Applications and Methods
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• 제19권2호
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• pp.293-301
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• 2012

Quantile regression proposed by Koenker and Bassett (1978) is a statistical technique that estimates conditional quantiles. The advantage of using quantile regression is the robustness in response to large outliers compared to ordinary least squares(OLS) regression. A regression tree approach has been applied to OLS problems to fit flexible models. Loh (2002) proposed the GUIDE algorithm that has a negligible selection bias and relatively low computational cost. Quantile regression can be regarded as an analogue of OLS, therefore it can also be applied to GUIDE regression tree method. Chaudhuri and Loh (2002) proposed a nonparametric quantile regression method that blends key features of piecewise polynomial quantile regression and tree-structured regression based on adaptive recursive partitioning. Lee and Lee (2006) investigated wage determinants in the Korean labor market using the Korean Labor and Income Panel Study(KLIPS). Following Lee and Lee, we fit three kinds of quantile regression tree models to KLIPS data with respect to the quantiles, 0.05, 0.2, 0.5, 0.8, and 0.95. Among the three models, multiple linear piecewise quantile regression model forms the shortest tree structure, while the piecewise constant quantile regression model has a deeper tree structure with more terminal nodes in general. Age, gender, marriage status, and education seem to be the determinants of the wage level throughout the quantiles; in addition, education experience appears as the important determinant of the wage level in the highly paid group.

• 생물환경조절학회지
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• 제23권4호
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• pp.321-328
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• 2014

본 연구는 감꽃의 주요 향기성분을 알아보기 위해서 감나무 수령별로 감꽃의 향기성분을 SPME를 이용하여 분석하고, 기관을 꽃과 꽃받침으로 분류하여 향기성분을 비교하였다. 감나무 수령별 감꽃의 만개율은 15년생 이상, 10-14년생, 5-9년생 순으로 수령이 오래될수록 초기 만개율이 높았다. 감나무 수령에 따른 감꽃 향기성분 분석 시 동정된 주요 향기 성분은 a-pinene, butene, caryophyllene, cubebene, lavandulol, D-limoneneylangene, ylangene 등의 성분을 얻을 수 있었다. 대부분이 green향, fruit계, floral계의 옅은 향도 포함하고 있었다. 감꽃에 존재하는 휘발성 향기성분의 수는 5-9년생은 30종, 10-14년생은 24종, 그리고 15년생 이상에서는 32종으로 수령이 5년 미만과 15년 이상에서 많은 향기성분이 조사되었다. 감꽃을 꽃받침과 나누어 향기성분을 비교하면 단감 '부유' 품종 중 꽃의 향기 성분은 10개이고 상대적인 총 함량은 26.35%이며, 꽃받침은 향기 성분은 14개이고 상대적인 총 함량은 46.28%로 꽃에 비해서 더 다양한 향기성분이 존재하는 것으로 조사되었다. 반면 떫은감 '둥시' 품종은 꽃에서는 6개의 향기성분이 17.58%, 꽃받침에서는 9개의 향기 성분이 50.27%로, '부유' 품종에 좀더 다양한 향기성분이 존재하였다. 본 연구는 감꽃 향기를 이용하고자 하는 향기산업에 기초자료를 제공하는데 기여할 것이다.

• 자원환경지질
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• 제48권6호
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• pp.501-508
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• 2015

본 연구는 울릉도 나리칼데라에서 산출된 탄화목의 수종식별, 연륜분석, 방사성탄소 연대를 통해 고식생/고환경, 분출연대 및 화산쇄설물의 정치온도에 대한 정보를 제공하기 위해 수행되었다. 탄화목은 울릉도 최후기 화산쇄설층을 대표하는 나리테프라층의 최하부(Member N-5) 부석질 퇴적층 내에서 채취되었으며, 나이테의 원형(횡단면)이 잘 보존된 나무의 가지 부분이다. 분석결과, 수종은 소나무과 중 가문비나무속(Picea spp.)으로 식별되었으며 최외각 나이테의 연륜은 $263+{\alpha}$ 년으로 확인되었다. 나이테는 중심(pith)에서 바깥쪽을 향해 그 나이가 점차 젊어지며 $20,260{\pm}230$, $19,995{\pm}245$ 및 $19,975{\pm}265cal\;BP$ 의 보정연대를 가진다. 가장 젊은 연대인 19,710 cal BP 는 Member N-5의 분출과 관련된 연대일 가능성이 높다. 이 결과는 후기 플라이스토세 동안 울릉도 나리칼데라는 가문비나무가 번성하였으며, 한랭 습윤한 기후조건하에 있었음을 지시한다. 광택, 취성, 색 및 조흔색 등의 특성에 기초하면, 탄화를 야기한 화산쇄설물의 최소 온도는 약 $350{\sim}500^{\circ}C$ 정도일 것으로 추정된다.

• 한국환경복원기술학회지
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• 제14권2호
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• pp.1-10
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• 2011

Six pine trees (Pinus densiflora S. et Z.) at the Euilimji Lake Park in Jecheon were collected to investigate tree ages, growth decline pattern and the years of death. Tree-ring measurement was carried out using the Lintab with a resolution of 0.01mm. Tree age were 80-176 years. Cross-dating between the tree-ring series of each tree and the local chronology from Worak Mountain resulted that four and two trees died in 1998 and 1999, respectively. Three dead trees had only formed earlywood in the outermost tree ring and the others had incomplete latewood. Therefore, it was proven that the former trees died between spring and early summer, whereas the later ones died during late summer and/or autumn. The simultaneous deaths of trees suggest the insect damage and/or drought may be the crucial reason of the death, but frequent reaction woods, which were formed by leaning stem, and scars formed by physical damage may also contribute to the death.

• 대한간호학회지
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• 제50권2호
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• pp.191-199
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• 2020

Purpose: The purpose of this study was to compare sociodemographic characteristics of a normal cognitive group and mild cognitive impairment group, and establish prediction models of Mild Cognitive Impairment (MCI). Methods: This study was a secondary data analysis research using data from "the 4th Korea Longitudinal Study of Ageing" of the Korea Employment Information Service. A total of 6,405 individuals, including 1,329 individuals with MCI and 5,076 individuals with normal cognitive abilities, were part of the study. Based on the panel survey items, the research used 28 variables. The methods of analysis included a χ²-test, logistic regression analysis, decision tree analysis, predicted error rate, and an ROC curve calculated using SPSS 23.0 and SAS 13.2. Results: In the MCI group, the mean age was 71.4 and 65.8% of the participants was women. There were statistically significant differences in gender, age, and education in both groups. Predictors of MCI determined by using a logistic regression analysis were gender, age, education, instrumental activity of daily living (IADL), perceived health status, participation group, cultural activities, and life satisfaction. Decision tree analysis of predictors of MCI identified education, age, life satisfaction, and IADL as predictors. Conclusion: The accuracy of logistic regression model for MCI is slightly higher than that of decision tree model. The implementation of the prediction model for MCI established in this study may be utilized to identify middle-aged and elderly people with risks of MCI. Therefore, this study may contribute to the prevention and reduction of dementia.