• 대한기계학회논문집A
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• 제24권1호
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• pp.38-51
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• 2000

The study on the mechanical behavior of a spot-welded specimen is largely divided into the quasi-static overload failure analysis and the fatigue failure prediction. The main issue in an overload analysis is to examine the critical loads, thereby providing a generalized overload failure criterion. As the welding spot forms a singular geometry of an external crack type, fatigue failure of spot-welded specimens can be evaluated by means of a fracture parameter. In this study, we first present the limit loads of 4 representative types of single spot-welded specimens in terms of the base metal yield strength and specimen geometries. Recasting the load vs. fatigue life relationships experimentally, obtained here, we then predict the fatigue life of spot-weld specimens with a single parameter denoted the equivalent stress intensity factor. This crack driving parameter is demonstrated to successfully describe the effects of specimen geometry and loading type in a comprehensive manner. The suggested fatigue life formula for a single spot weld can play a key, role in the design and assessment of spot-welded panel structures, in that the fatigue strength of multi-spots is eventually determined by the fatigue strength of each single spot.

• 한국학교ㆍ지역보건교육학회지
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• 제19권2호
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• pp.31-42
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• 2018

Objectives: This study was conducted to analyze the mediating effect of self-identity on the relationship between aggression and school life adaptation of early adolescents. Methods: This study used the 5th-year data of the Korean Children & Youth Panel Survey (KCYPS) including 159 middle school 2nd students from single-parent families. The data was analyzed with open source statistics program R 3.5.0 to determine whether self-identity had a mediating effect on school life adaptation as an independent variable. Results: A moderate correlation was found among aggression, self-identity, and school life adaptation. As a result of the Sobel test, self-identity of early adolescents demonstrated a significant mediating effect on the relationship between aggression and school life adaptation. Conclusions: Given the significant mediating factor of self-identity, the strategies for early adolescents to boost their overall school life adaptation should be considered through intervention programs that help to enhance their self-identity.

• Clinical Nutrition Research
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• 제13권1호
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• pp.42-50
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• 2024

This study analyzed the 2019 Community Health Survey data to compare and analyze the health levels and life satisfaction of single-person elderly households based on food security. The final study subjects were 15,606 single-person elderly individuals aged 65 and above. These subjects were classified based on their response to food security into three groups: food sufficient-diverse, food sufficient-not diverse, and food insufficient. The study results showed that the proportion of the food insufficient group among single-person elderly households was 7.4% for men and 10.6% for women, with a slightly higher rate for female elderly. Both male and female elderly over 80 years of age, with low education levels, and basic living support recipients showed significantly higher proportions in the sufficient-not diverse and food insufficient groups. For male elderly, significant differences were observed in subjective health status and oral health level in the food insufficient group, and for female elderly, stress levels also showed significant differences. Life satisfaction scores were generally lower for female elderly compared to male, and significant differences were found in both male and female elderly based on food security. Common factors that significantly influence life satisfaction among single-person elderly households, both male and female, include food security, subjective health status, and living environment satisfaction, with food security being the most impactful factor. The study suggests that it is necessary to include these significant factors in the development of various social activity programs, such as dietary programs, to enhance life satisfaction and food security of single-person elderly households.

• Journal of Ecology and Environment
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• 제31권3호
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• pp.207-211
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• 2008

We investigated the leaf demography of a temperate woody liana, Akebia trifoliata, in a temperate forest in Japan, Akebia is semi-evergreen: some leaves are shed before winter, while others remain through the winter. Previous studies of semi-evergreen species found that variation in leaf life span was caused by variation in the timing of leaf emergence, Leaves that appeared just before winter over-wintered, while leaves appearing earlier were shed, However, it is unclear whether leaves of the same cohort (i.e., leaves that appear at the same time within a single site) show variation in life span under the effect of strong seasonality. To separate variation in life span among the leaves in each cohort from variation among cohorts, we propose a new method - the single leaf diagram, which shows the emergence and death of each leaf. Using single leaf diagrams, our study revealed that Akebia leaves within a cohort showed substantial variation in life span, with some over-wintering and some not. In addition, leaves on small ramets in the understory showed great variation in life span, while leaves on large ramets, which typically reach higher positions in the forest canopy, have shorter lives, As a result, small ramets were semi-evergreen, whereas large ramets were deciduous, The longer lives of leaves on small ramets can be interpreted as a shade-adaptive strategy in understory plants.

• 한국융합학회논문지
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• 제12권8호
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• pp.67-75
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• 2021

본 연구는 50-69세의 저소득 1인 가구를 대상으로 그들의 자존감에 미치는 영향요인을 확인하기 위하여 시행되었다. 분석대상은 보건복지부에서 제공하는 2019년 복지패널자료로부터 50-69세 저소득 1인 가구에 해당하는 233명이었다. 연구방법은 자존감을 종속변수로 하고, 관계만족도와 생활만족도를 독립변수로 정의한 후, 구조방정식 모형을 이용하여 분석하였다. 분석결과, 관계만족도는 경로계수 0.24로 자존감에 직접적으로 영향을 나타내지 않았다. 그러나, 관계만족도는 경로계수 0.71로 생활만족도에 긍정적 영향을 주었고, 생활만족도는 경로계수 0.46으로 자존감에 유의미하게 긍정적 직접영향을 나타내었다. 또한 생활만족도가 관계만족도와 자존감에 경로계수 0.32로 매개효과를 미치고 있는 것으로 나타났다. 그러므로, 열악한 1인 가구를 지원하는 전략을 세울 때, 정책입안자들은 관계만족도와 생활만족도를 개선시키는 방법을 고려해야 할 것이다.

• 가족자원경영과 정책
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• 제28권1호
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• pp.13-25
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• 2024

1인가구 증가는 전 세계적 현상으로 한국 또한 1인가구 비중의 증가가 급속히 진행 중이다. 1인가구는 그 형성 계기, 성별, 생애주기 등에 따라 매우 다양한 스펙트럼을 갖고 있으며, 각각의 특성을 반영한 지원이 가능하도록 1인가구 집단을 세분화하여 연구할 필요가 있다. 이 연구는 생애주기에 따라 청년기, 중장년기, 노년기 1인가구 등 세 개의 집단으로 분류하고, 1인가구 건강성 수준에 있어 집단 간 유의한 차이가 있는지, 나아가 건강성에 영향을 미치는 인구사회학적 특성 및 1인가구 삶의 특성에는 어떠한 것들이 있는지 살펴보았다. 분석을 위해 2022년도 김포시 거주 1인가구 237명을 대상으로 설문조사를 통해 수집된 자료를 이용하였고, 기술통계, 평균차이 검증(t-test, ANOVA), 중다회귀분석 등을 실시하였다. 1인가구의 전반적 건강성 수준을 살펴보면 생애주기별로 차이가 있었는데, 청년기 1인가구가 노년기 1인가구에 비해 건강성 수준이 유의하게 높았다. 중다회귀분석 결과, 1인가구 건강성에는 성별, 교육수준, 자발성, 차별경험 여부가 유의한 영향을 미치는 것으로 나타났으며, 건강성을 구성하는 하위영역별로 영향을 미치는 변수에는 차이가 있었다. 생애주기에 따른 1인가구의 건강성 수준에 대한 결과를 토대로 하여 1인가구 정책의 방향성을 논의하고 실천적 함의를 제공하였다.

• 산업경영시스템학회지
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• 제37권3호
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• pp.36-42
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• 2014

Domestic 105mm HE (High Explosive) shell is composed of three parts that are Fuze, Projectile and Propellants. Among three parts, propelling charge of propellants part consists of single base propellants. It has been known that the lifespan of single base propellants is affected by a storage period. These are because Nitrocellulose (NC) which is the main component of propelling gunpowder can be naturally decomposed to unstable substances similar with other nitric acid ester. Even though it cannot be prevented fundamentally from being disassembled, a decomposition product ($NO_2$, $NO_3$, and $HNO_3$) and tranquillizer DPA (Diphenylamine) having high reactivity are added into a propellant to restrain induction of automatic catalysis by a decomposition product. The decay rate of the tranquillizer is also affected by a production rate of the decomposition product of NC. Therefore, an accurate prediction of the Self-Life is required to ensure against risks such as explosion. Hereupon, this paper presents a new methodology to estimate the shelf-life of single base propellants using data of ASRP (Ammunition Stockpile Reliability Program) to domestic 105mm HE (propelling charge of propellants part). We selected four attributes that are inferred to have influence on distribution of the DPA amount in a propellant from the ASRP dataset through data mining processes. Then the selected attributes were used as independent variables in a regression analysis in order to estimate the shelf-life of single base propellants.

• 가족자원경영과 정책
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• 제18권2호
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• pp.121-141
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• 2014

The purpose of this research is to determine how effective individual resources, family resources and developed environmental resources are in assisting the adaptation of a single parent's child to school life. The subjects were 284 first-year middle-school students with a single parent who were included in the first year of the Korean Children and Youth Research Panel 2010 data. The data were statistically processed using SPSS 18.0software. The results were as follows. First, the research participants' adaptation to school life, self-esteem, self-resilience, and peer relations were all shown to have an average of higher than 2 on a 4-point scale. Positive perceptions of parenting attitudes were 2.87, and negative perceptions 2.38. Computer usage was high, scoring 2.42, but mobile phone usage was average, at 2.02. Of the participants, 83.8% did not participate in a club or extracurricular activity. Second, self-esteem, self-resilience, peer relations, and positive parenting attitudes were correlated positively with adaptation to school life, but relying on a mobile phone was correlated negatively. Third, regarding the consequences of the relative effectiveness of the variables for adaptation to school life, as self-esteem, self-elasticity, and positive perceptions of parenting attitudes increased, Adaptation of a single parent's child to school life was more successful. Additionally, as annual family income and reliance on mobile phones increased, students' adaptation to school was less successful.

• 한국주거학회논문집
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• 제8권3호
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• pp.111-118
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• 1997

This study is intended to analyze the preference of one-room apartment according to the type of life style of single people between 20 and 30 years age. The major findings were as follows: 1) The single people prefer the one-roon apartment(90.2%). 2) The Life styles were classified into 5 types: tradition preservation. self-fulfillment, fashion-pursuit. economy priority. convenience-pursuit. 3) The preference of a one room apartment is strongly influenced by all types of life styles regardless of tradition preservation.

• Tribology and Lubricants
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• 제11권3호
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• pp.40-47
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• 1995

The engine oil life was examined experimentally for small size single cylinder engines. This study was conducted in the laboratory. An Eddy Current type engine dynamometer was used with a motorcycle and a cultivator engine. Physical and chemical properties of used oil was analyzed to examine the oil life. Flushed oil was used for the reference instead of the new oil. It were found that deterioration of dynamic viscosity and anti-wear property of engine oil was due to dilution by fuel not depletion of ZDTP.