• 콘크리트학회논문집
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• 제19권6호
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• pp.693-700
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• 2007

성숙도는 콘크리트의 강도발현에 대한 시간과 온도의 효과를 산정하는데 사용된다. 이 논문의 목적은 변화하는 양생 온도가 성숙도 개념을 이용하여 보통 강도와 고강도의 강도발현에 어떻게 영향을 미치는지 보이는 것이다. 보통 강도콘크리트에 대한 실험 결과에서 변화하는 양생 온도의 최고점 시간이 달라짐에 따라 강도발현의 교차 (cross-over)효과가 나타난다. 그러나 이 교차 효과는 콘크리트의 실제 재령이 온도를 고려한 등가 재령 (equivalent age)로 전환된 이후에는 찾아보기 힘들다. 다른 말로 표현하자면, 기존의 성숙도는 양생 온도의 최고점에 대응하는 시간의 변화에는 민감하지 않으나 그 양생 온도 최고점의 크기에는 민감하다. 고강도콘크리트에 대해서는 그 결과가 결론을 내리기가 쉽지 않다. 보통강도콘크리트에 대한 실험 결과는 기존의 성숙도가 후기 강도에 대해 초기양생 온도에 대한 효과를 고려하지 못한다는 제한을 언급한 ASTM과 동일함이 있다. 그래서 이 연구는 향상된 콘크리트 성숙도에 대한 기초로서 사용될 것이다.

• Asian Pacific Journal of Cancer Prevention
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• 제13권4호
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• pp.1413-1418
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• 2012

Background: Previous studies generally indicate that synchronous bilateral breast cancers (SBBC) have an equivalent or moderately poorer survival compared with unilateral cases. The prognostic characteristics of SBBC would be relevant when planning adjuvant therapies and follow-up medical surveillance. The frequency of SBBC among early breast cancers in clinical settings in Australia and New Zealand was investigated, plus their prognostic significance, using the Breast Cancer Audit Database of the Society of Breast Surgeons of Australia and New Zealand, which covered an estimated 60% of early invasive lesions in those countries. Design: Rate ratios (95% confidence limits) of SBBC were investigated among 35,370 female breast cancer cases by age of woman, histology type, grade, tumour diameter, nodal status, lymphatic/vascular invasion and oestrogen receptor status. Univariate and multivariable disease-specific survival analyses were undertaken. Results: 2.3% of cases were found to be SBBC (i.e., diagnoses occurring within 3 months). The figure increased from 1.4% in women less than 40 years to 4.1% in those aged 80 years or more. Disease-specific survivals did not vary by SBBC status (p=0.206). After adjusting for age, histology type, diameter, grade, nodal status, lymphatic/vascular invasion, and oestrogen receptor status, the relative risk of breast cancer death for SBBC was 1.17 (95% CL: 0.91, 1.51). After adjusting for favourable prognostic factors more common in SBBC cases (i.e., histology type, grade, lymphatic/vascular invasion, and oestrogen receptor status), the relative risk of breast cancer death for SBBC was 1.42 (95% CL: 1.10, 1.82). After adjusting for unfavourable prognostic factors more common in SBBC cases (i.e., older age and large tumour diameter), the relative risk of breast cancer death for SBBC was 0.98 (95% CL: 0.76, 1.26). Conclusions: Results confirm previous findings of an equivalent or moderately poorer survival for SBBC but indicate that SBBC status is likely to be an important prognostic indicator for some cases.

• 한국산림과학회지
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• 제109권4호
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• pp.468-476
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• 2020

본 연구는 굴참나무 임분밀도관리도 개발을 통해 맹아갱신림의 경영목표별 벌기령을 예측하고자 하였다. 분석에 활용된 표준지 조사자료는 분석용 자료 603개소와 검증용 자료 113개소로 분류하였고, 이를 이용하여 임분밀도관리도의 개발과 적합도 검증을 실시하였다. 임분밀도관리도 구성 모델의 설명력(R2)은 등평균수고곡선식 0.732, 등평균직경곡선식 0.990으로 분석되었다. 재적 생산 최대 벌기령을 분석한 결과, ha당 900본의 맹아 잔존 시 42~44년으로 나타났고, ha당 1,800본을 잔존한 경우 38~42년으로 분석되었다. 3등급재 원목을 생산목표로 설정하였을 때의 벌기령은 지위지수 16일 때 25~28년이 소요되었고, 지위지수 14는 29~33년이 소요되는 것으로 나타났다. 본 연구의 결과는 굴참나무 맹아갱신 임분의 경영계획 수립에 있어서 기초자료로 활용될 수 있을 것으로 판단된다.

• 천문학회지
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• 제28권1호
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• pp.45-59
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• 1995

In the best observed Pleiades cluster, the luminosity function(LF) and mass function(MF) for main sequence(MS) stars extended to $Mv{\approx}15.5(V{\approx}21)$ are very similar to the initial luminosity function(ILF) and initial mass function(IMF) for field stars in the solar neighborhood showing a bump at log $m{\simeq}-0.05$ and a dip at log $m{\simeq}-0.12$. This dip is equivalent to the Wielen dip appearing in the LF for the field stars. The occurence of these bump and dip is independent of adopted mass-luminosity relation(MLR) . and their characteristics could be explained by a time-dependent bimodal IMF. The model with this IMF gives a total cluster mass of $\~700M_\bigodot,\;\~25$ brown dwarfs and $\~3$ white dwarfs if the upper mass limit of progenitor of white dwarf is greater than $4.5M_\bigodot$. The cluster age on the basis of LF for brightest stars is given by $\~8\times10^7yr$ and all stars in the cluster lie along the single age sequence in the C-M diagram without showing a large dispersion from the sequence.

• 아동학회지
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• 제22권4호
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• pp.17-32
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• 2001

The purpose of this study was to explore the developmental patterns of self-concept of pre-adolescents and adolescents by using the longitudinal data originated by the Korean Institute for Research in the Behavioral Sciences (KIRBS). Specifically, using Structural Equation Modeling (SEM), the effects of parents and peer groups on the stability and change of self-concept were examined across a 9-year-period. The subjects were 62 children(29 boys and 33 girls) from the KIRBS longitudinal data. The results showed that, peer relationships revealed consistent effects on children's self-concept from pre-adolescence to mid-adolescence. In particular, this influence was most evident at 7 years of age and at 16 years of age. However, parental influence was almost non-existent for 7-year-olds, equivalent to peer relationships for 10-year-olds, and decreased for 16-year-olds. On the whole, parental and peer influence on self-concept gradually decrease in adolescence. Nevertheless, parental and peer influence continue to maintain a certain level of influence from childhood to adolescence. This study provides an understanding of developmental change and stability in the self-concept of Korean adolescents.

• 대한가정학회지
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• 제47권1호
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• pp.1-12
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• 2009

The purpose of this study was to establish the relative influences of individual variables (sex, age, temperament) and mother's psychosocial variables (maternal attitude, parenting stress, marriage satisfaction) on daily stress levels and maladjustment of young children attending at daycare centers. Subjects were 224 pairs of children and their mothers, and 18 teachers from 5 child-care centers in Gwangju City. Children were tested individually using 22-item daily stress inventory with illustrations which described certain stressful situations. Questionnaires were also administered to mothers and teachers. Collected data were subjected to Cronbach's $\alpha$, correlation and multiple regression analysis using SPSS (WIN 14.0) program. The major findings were as follows; Overall average score of children's daily stress was equivalent with the median. 'Blame and attack situation' and 'anxiety and frustrated situation' were perceived as more stressful for children than 'lose self-respect situation'. Overall average score of children's maladjustment was lower than the median. 'Overactivity' was highest among subscores of maladjustment. Age was the only significant influential factor on children's daily stress level. Sex was the most influential factor on 'overactivity', 'aggression', and 'regression' of young children. Activity and maternal stress were the second most influential factor on 'overactivity' and 'aggression', respectively.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2018년도 추계 학술논문 발표대회
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• pp.42-43
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• 2018

The research is to suggest the compensating strength values depending on various managing periods of concrete based on the strength development model calculated with equivalent age method for 20% of blast furnace slag replaced concrete. As a result, for 28 days of managing period, 9, 6, and 3MPa of compensating strength values were suggested when the temperatures were from 4 to 6℃, from 6 to 12℃, from 12 to 17℃, respectively. Additionally, for 42 days of managing period, 6 and 3MPa of compensating strength value was suggested when the temperature was from 4 to 7℃, from 7 to 12℃, and for 56 days of managing period, 3MPa of compensating strength value was suggested when the temperature was from 4 to 9℃. Furthermore, for 28, 42, 56, and 91 days of managing periods, any compensating strength values were needed when the temperature were higher than 17, 12, 9, and 4℃, respectively.

• International Journal of Automotive Technology
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• 제7권3호
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• pp.245-249
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• 2006

Accelerated aging of engine exhaust system components such as catalytic converters are traditionally performed using an engine/dynamometer test stand. $SwRI^{(R)}'s\;FOCAS^{(R)}$ system reduces or eliminates many of the engine based aging limitations. This paper will describe several studies. These include: 1) replication of engine based catalyst aging cycles with added precision and dependability; 2) catalyst aging with and without lubricating oil effects; 3) effects of lubricant phosphorus on catalyst performance; and 4) the potential to thermally age components beyond the capabilities of engine based systems. The first study includes the development of the SwRI FOCAS system to run programmed aging conditions with or without lubricating oil. A description of the subsystems is given. The second two studies used the SwRI FOCAS system to age catalysts. One study compared thermal-only aging using of the SwRI FOCAS system with equivalent aging on a traditional engine/dynamometer test stand. The other study examined the effect on catalyst performance of two lubricating oils containing different levels of phosphorus, and compared the results to field data generated using the same oils in a fleet of vehicles.

• 한국안광학회지
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• 제15권4호
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• pp.389-397
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• 2010

목적: 본 연구는 한국인 6~80세를 대상으로 10년 동안 굴절이상과 난시축의 변화를 조사하기 위해 시행되었다. 방법: 1999년부터 2009년까지 안과 병원을 내원한 220명(345안)을 대상으로 10년 동안 매년 조절마비 굴절검사를 포함한 현성 굴절검사를 실시하였다. 시력검사는 한천석식 시표를 사용하였다. 결과: 6~10세와 11~20세 그룹의 10년간 구면등가 굴절력의 변화는 각각 -3.649D와 -2.165D였다. 21~40세 그룹은 굴절이상의 변화가 없었다. 41세에서 69세까지는 근시 쪽으로 진행이 감소하다가 70세 이상에서는 약간 증가하였으며 원시 쪽으로 진행은 반대 경향을 보였다. 6~10세와 11~20세 그룹에서는 10년 동안 굴절이상 분포가 근시 쪽으로 진행되었다. 6~10세 그룹에서 중등도(> -3.01D) 이상의 근시 빈도가 4.8% 였으나 10년 후에는 62.5%를 보였다. 난시 축의 10년 동안 변화는 젊은층은 직난시를 보였으나 나이가 들수록 도난시 쪽으로 진행하였다. 결론: 본 연구는 한국인의 굴절이상 변화가 6~20세 그룹은 근시 쪽으로 진행하다가 70세 이전까지 원시 쪽으로 진행한 후 다시 근시 쪽으로 진행하는 것으로 나타났다. 난시 축은 40대 이후 도난시 쪽으로 변하였다.

• Safety and Health at Work
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• 제14권4호
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• pp.406-414
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• 2023

Background: This study examined age-group differences in the rate, severity, and cost of injuries among construction workers to support evidence-based worker safety and health interventions in the construction industry. Methods: Ohio workers' compensation claims for construction workers were used to estimate claim rates and costs by age group. We analyzed claims data auto-coded into five event/exposure categories: transportation incidents; slips, trips, and falls (STFs); exposure to harmful substances and environments; contact with objects and equipment (COB); overexertion and bodily reaction. American Community Survey data were used to determine the percentage of workers in each age group. Results: From 2007-2017, among 72,416 accepted injury claims for ~166,000 construction full-time equivalent (FTE) per year, nearly half were caused by COB, followed by STFs (20%) and overexertion (20%). Claim rates related to COB and exposure to harmful substances and environments were highest among those 18-24 years old, with claim rates of 313.5 and 25.9 per 10,000 FTE, respectively. STFs increased with age, with the highest claim rates for those 55-64 years old (94.2 claims per 10,000 FTE). Overexertion claim rates increased and then declined with age, with the highest claim rate for those 35-44 years old (87.3 per 10,000 FTE). While younger workers had higher injury rates, older workers had higher proportions of lost-time claims and higher costs per claim. The total cost per FTE was highest for those 45-54 years old ($1,122 per FTE). Conclusion: The variation in rates of injury types by age suggests that age-specific prevention strategies may be useful.