• Journal of the Korean Wood Science and Technology
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• v.22 no.2
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• pp.46-53
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• 1994

This study was conducted to investigate a feasibility of manufacturing wood fiber thermoplastic composites and to evaluate their mechanical properties. Wood fiber as a potential reinforcing filler was compounded with two thermoplastics (polypropylene and high density polyethylene) in high intensity thermokinetic plastic mixer aided with a wetting agent. It was found that wood fiber thermoplastic composites could be manufactured by injection molding process. The tensile and flexural strength of injection molded specimens were improved greatly with increasing wood fiber concentration. Tensile and flexural modulus increased proportionately with wood fiber concentration. Wood fiber provided reinforcement with thermoplastics in terms of strength and modulus. However, the percent elongation at break and energy to break were reduced with increasing wood fiber loadings. Impact strength also showed similar trend.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.115-115
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• 2023

최근 기후변화의 영향으로 국내에서 강우량과 유출량의 변동성이 커짐에 따라 효율적으로 수자원을 관리하는 데 어려움을 겪고 있다. 따라서 수자원 관리 측면에서 강우관측소를 대상으로 군집 분석과 경향성 분석을 통해 사전에 강우 시계열 자료의 추세와 특징을 파악하면 용수 공급과 가뭄 및 홍수피해 저감 등에 효과적으로 대처할 수 있다. 본 연구에서는 2000년부터 2019년까지낙동강 유역의 64개 강우관측소를 대상으로 동질성 검정과 수정 Mann-Kendall (MK) 검정을 적용하여 강우 시계열 자료의 월별, 계절별, 연도별 경향성 분석을 수행하였다. 또한, 경향성이 나타나는 관측소별 세부지표(연평균 강우량, 표고 등)를 기준으로 K-means 군집 분석을 수행하여 군집별 강우 특성을 파악하고자 하였다. 분석을 수행한 결과 경향성 분석에선 3월, 4월, 11월, 12월, 봄 및 가을에는 강우량이 증가 추세를 보였고 1월, 5~9월, 여름과 연도별로는 감소 추세가 나타났다. 또한 군집 분석에서는 Silhouette analysis를 기반으로 최적의 군집 개수를 3개로 설정했을 때 군집별 강우 세부지표의 통계값이 관측소별 표고에 비례하는 특징이 나타났다. 연구를 통해 도출된 군집별 강우 특성과 관측소별 경향성 분석결과를 연계하면 강우량의 변동성을 고려한 효율적인 수자원 관리 방안을 마련하는 데 활용할 수 있을 것으로 판단된다.

• Journal of the korean academy of Pediatric Dentistry
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• v.36 no.2
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• pp.227-236
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• 2009

The purpose of this study is to examine the acidity of beverages that are sold for children in the market and to estimate by experiment the degree of the enamel erosion of deciduous teeth that is attributed to the beverages. The pH value of children beverages among top sale list in Seoul and Gyeonggi province were measured. And 7 beverages with the pH value of 3.5 or lower were selected. The enamel erosion of deciduous teeth by the children beverages for 1, 5, 10, and 30 minutes respectively was examined. The results were as follows: 1. The acidity of most of the children beverages examined in this study was the pH level of 5.5 or lower that can cause the tooth erosion. 2. The microhardness value of the enamel of deciduous teeth was lower as exposing it to children beverages. The reduction of surface microhardness value was significant from 1 minute after the exposure, and the reduction was continuously observed until 30 minutes has passed. 3. The higher the acidity of beverages, the larger the reduction in microhardness value caused after the exposure of 30 minutes to the beverages. There was no significant relation between the acidity of beverages and the reduction rate of surface microhardness value. The other factors such as calcium, phosphorus, and fluorine or buffering of the beverages may affect the enamel erosion.

• Child Health Nursing Research
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• v.20 no.3
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• pp.196-204
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• 2014

Purpose: The purpose of this study was to examine levels of knowledge, attitude towards infant oral health, and related health behavior of parents. Methods: The sample consisted of 380 parents who were providing care for a child ranging in age from 11 to 16 months. Results: Participants obtained information on infant oral health via the internet, infant care books, and friends. While showing the correct attitude towards infant oral health, the parents were ill-informed regarding infant oral health and engaged in low levels of appropriate health behavior. There were statistically significant differences in infant oral health knowledge according to parents age, education, income, and age of infant. Attitude towards infant oral health was significantly different according to parents education and income. Also, there were significant differences in health behavior practice for infant oral health according to parents age, income, caregiver, and infant age. A significant positive relationship was found between knowledge and attitude to infant oral health. Conclusion: The results of this study indicate that for maintenance and improvement of infant oral health, the parents and caregivers of infants should be provided with information and specific methods for infant oral health care.

• Proceedings of the Technology Innovation Conference
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• 2009.02a
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• pp.313-332
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• 2009

본 연구에서는 국가의 연구개발활동조사에서 기업연구개발활동 통계에 대한 효과적인 산출방법을 제시하고자 하였다. 이를 위하여 국내 외 연구개발 통계방법을 조사한 후 이를 토대로 우리나라에서 기업연구개발활동에 대한 자료의 수집 및 분석에 대한 개선방안을 제시하였다. 대부분의 국가에서는 대기업은 전수조사, 소규모 기업은 표본조사를 수행하고 있으나, 우리나라에서는 연구소 등록법인에 대하여 전수조사를 행하고 있다. 전수조사는 비용이 많이 들고 비 표본오차로 인하여 모집단에 대한 체계적인 추정이 불가능하다는 문제점이 있다. 현재 산업기술진흥협회에 등록된 연구기관의 수가 20,000개를 넘어서고 있어 전수조사는 한계에 다다른 것으로 생각되어 표본조사 도입에 대한 타당성과 방법론을 중점적으로 검토하였다. 먼저, 표본조사의 타당성을 평가하기 위하여 현재 전수조사를 통해 수집된 자료를 이용하여 표본조사를 수행한 결과를 비교 분석하였다. 산업별(24개), 그룹별(8개)로 구분하여 216개 셀별로 모집단수/표본수를 곱하여 산정 (셀별추정법)한 결과, 전수 통계치와 거의 동일하게 나타났다. 따라서, 산업별, 그룹별로 세분하여 모집단수/표본수를 곱하여 추정하는 셀별추정법이 타당한 것으로 평가할 수 있다. 이상의 분석결과를 토대로 새로운 조사설계방안을 제시하면 다음과 같다. 직전연도 조사기업은 직전연도 연구개발비 수준과 기업종류(대기업, 벤처기업, 중소기업), 그리고 산업에 따라 셀을 분할한다. 대기업, 연구개발비 수준이 높은 기업 등 주요한 셀에 대하여는 전수조사를 실시한다. 나머지 셀에 대하여는 각 셀별 연구개발지출의 분포가 동질적이기 때문에 표본 추출방법은 단순임의추출법(SRS)을 사용한다. 다만 전년도 미계상된(또는 미포함된) 기업에 대하여는 신규 대형 연구소 진입 등을 고려하여 규모비례확률추출법(PPS)을 고려하는 것이 바람직할 것으로 판단된다. 일부 기업들이 특정 항목에 대한 자료를 제공하지 않는 항목무응답의 경우, 누락된 자료에 대하여는 대체기법(Imputation Algorithm)에 따라 이를 추정한다. 이러한 표본조사방법은 전수조사에서 발생하는 비 표본오차를 해소하고, 자료수집비용 및 소규모기업의 행정적 부담을 경감할 수 있다는 장점이 있다. 향후 연구에서는 좀 더 구체적인 조사방법론을 강구할 필요가 있으며, 이와 함께, 연구개발에 대한 다양한 측면의 정보를 수집하기 위해 새로운 설문지를 개발할 필요성이 있다.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.2
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• pp.160-167
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• 1998

Proximate composition, cholesterol (CHOL) and $\alpha-tocopherol$ ($\alpha-Toc$) content of seventy-two species of fish muscle (sea water fish, 59 species; fresh water fish, 13 species), which caught off Tongyeong coast of the Southern Sea ( Nam-Hae) and caught Kyeongho river, Sancheong, Korea, were determined. Lipid content was ranked from $0.53\%$ to $20.4\%$ and was high in the following order; mid-surface dwelling and migratory fish ($6.09{\pm}4.25\%$) > fresh water fish ($4.40{\pm}5.90\%$) > coastal and reep dwelling fish ($3.41{\pm}2.68\%$) > demersal fish ($2.12{\pm}2.41\%$). There was a negative correlation between the lipid and moisture content in all fish groups (p< 0.001). Protein was approximately $17\~18\%$ in all fish group, and no correlation was between the protein and moisture content in all but the demersal fish, which there was a negative correlation between both contents. Ash content was almost constant in all fish, accounting for $1\~2\%$, Cholesterol (CHOL) content was shown a great difference according to the fish species from 6.7 mg/100 g muscle (grass fish) to 249 mg/100 g (eel) and there was a positive correlation between the lipid and CHOL content. $\alpha-Toc$ content was less than 3 mg/100 g muscle in all fish, except that of eel (4.1 mg/100 g) and was relatively rich in the fish species contained a large amount of lipid.

• The Journal of the Korea Contents Association
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• v.18 no.5
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• pp.545-553
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• 2018

As the share of leisure culture increases these days, expectations are rising for the high quality of culture while increasing interest in leisure and tourism. The percentage of the population going on weekend trips to broaden the horizons of elementary, middle and high school students has continued to rise in proportion to the expectations for cultural enjoyment. We expect that visitors' weekend family activities will include relaxing, playing and educational purposes. Recent educational programs have moved from the past where only children were allowed to be onsite, to a shared style in which parents can engage in educational activities, potentially leading to the implicit involvement of family ties and family elasticity. The effects of education are not expressed by the period that ends in a single moment of experience, but by the continuity of training and experience. The same holds true for family affinity, communication and empathy. Providing opportunities for family experience and education is a national responsibility for broken family and restoring solidarity with the growing number of single-person households. Furthermore, it is a duty of museums and galleries today, and it is necessary to come up with methods to enhance family solidarity and family affinity. In particular, it is imperative to develop and provide educational programs for educational purposes at the Education Museum, and to develop " education for family " at the social level. This paper aims to analyze the results of all family participating education programs provided by family education programs at the Education Museum through family surveys and interviews, and to enhance the activation of family types education programs more actively.

• Korean Journal of Social Welfare
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• v.69 no.1
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• pp.33-57
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• 2017

This study examines the effect of working conditions for care workers on the care quality in long-term care facilities, particularly the coexisting perspective on publicness and the marketization of Long-term care services in South Korea brings about. Prior studies have not identified a causal relationship between working conditions and the care quality, only explained cause of a low-wage labor market and low productivity of social services. Theoretical relevance of working conditions and service quality on Long-term care in Korea is to view from a integrated care model by Daly and Lewis(2002). A nonproportional stratified sampling procedure was used to consider Long-term care facility's ownership. A merged dataset combining surveys from 248 Long-Term Care facilities and online resources from NHIC administrative was used and analyzed by multiple regression. The analysis results is showed as follows. Overall, organizations with better working conditions, having higher wage, having greater a fringe benefit, being skills development and training are likely to have good care quality in each area. This research shows that the working conditions, rewards and support to care workers of organizational culture in the normative dimension beyond the minimum standard on labor market policy and evaluation system by government regulations have a positive impact on Long-term care quality.

• KDI Journal of Economic Policy
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• v.12 no.4
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• pp.97-111
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• 1990

This paper examines the effect of redistributive inheritance tax on income distribution and social welfare. The model used here is the Overlapping-Generations Model consisting of individuals with different bequest motives where the lifetime income distribution in each cohort is determined endogeneously by the dynamic bequest process. It is shown that the introduction of redistributive inheritance tax can improve the vertical equity in the sense that the increase in tax rate reduces the coefficient of variations of intra-cohort income distribution in steady-state. However, it is also shown that, the effect on social welfare, when measured by Benthamite SWF, is uncertain in general. The numerical simulations show that, in spite of its equity-enhancing effect, the tax increase can actually lower the steady-state social welfare within the plausible range of parametric values, through the long-run output effect as well as the deadweight welfare loss incurred by tax distortion. Hence, the problem of equity-efficiency trade-off can arise in this case. However, if both the market interest rate and the elasticity of marginal utility in individual's preference function are sufficiently high, it is shown to be possible that the steady-state social welfare is enhanced by the introduction of inheritance tax.

• Journal of agricultural medicine and community health
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• v.25 no.2
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• pp.293-302
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• 2000

The relationship between sodium intake and stomach cancer risk has been studied much in Japan but a great portions still remain controversial. There has been few studies on relationship between sodium intake and stomach cancer in Korea. The goal of this nested case-control study is to investigate the association between sodium intake and stomach cancer risk in a rural county of Korea We estimated sodium intake indirectly by the threshold of salt-water taste of patients. This study was based on both of the data from 'Kangwha Cohort Study' which had been conducted from March 1985 and 'Kangwha Community Cancer Registry' which had been launched on July in 1982 by the College of Medicine, Department of Preventive Medicine. Yonsei University. A total of 145 patients who developed stomach cancer in Kangwha County were initially recruited as the case group. We tried to get two community-controls per stomach cancer case by matching age and gender. Finally we got information from 90 cases and 146 controls about the threshold of the salt taste and preference of salty food and so on. Some 79% of the information about ease group came from proxy respondents and 56% among controls. Risk ratios of developing stomach cancer adjusted for smoking, body mass index and self-stated health level were estimated. No statistically significant association between the threshold of salt taste and stomach cancer risk found in this study. We recommend some further studies utilizing urinary salt excretion, diet record method for better estimating of salt intake with a paticular emphasis on interaction effect between salty and spicy food in hospital-based case-control study designs.