• Environmental Engineering Research
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• 제25권3호
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• pp.345-355
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• 2020

This study has been carried out to evaluate the leaching behavior of Tunisian phosphogypsum (PG) tailings in Skhira city (southern Tunisia). Two PG samples, including old and freshly deposited samples, were characterized in terms of physical, geotechnical, mechanical, chemical and mineralogical properties. Special attention was paid to their leaching behavior when subjected to standard leaching tests. Our results indicated that both samples are mainly composed of more than 31.85% CaO and 31.4% SO3, indicating the predominance of gypsum. This was further confirmed by XRD patterns that revealed the presence of characteristic reflections of gypsum, brushite, quartz and Maladrite. Compressive strength after 90 d exceeded 769 kPa, but still lower than that of natural sand (1,800 kPa). Leaching test was proposed as an appropriate method to determine the released contaminants from PG. The obtained results showed that Fluorine and Phosphorus are the most released elements from PG with 40 and 30%, respectively. The released Se, Cd, and Zn were the only trace elements that exceeded the threshold limits. It seemed that leached element concentrations were independent aging or particle size of the PG. Based on the assessment of leaching behavior, an integrated management approach of the PG deposits was proposed.

• 한국약용작물학회지
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• 제20권6호
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• pp.415-420
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• 2012

In order to evaluate the effect of seed weight on different aspect of safflower (Carthamus tinctorius L.) seed germination and growth characteristics. Quantity of sinapine leaked from seed was greater as the viability of seeds was dropped by the time elapsed of seed aging model and long storage condition in safflower (Carthamus tinctorius L.). The cultivar of safflower was Jin-Sun and the seeds that are separated to three different weights of small, middle, and large were used in this experiment. Large seeds revealed the highest germination percent, coleoptiles fresh weight, coleoptiles dry weight, radicle fresh weight and 1000 seed weights than other seed weight. Seed weight had little effect on yield while seed number exerted a positive influence. Interestingly, yield per plant and its major components, number of capsules and capsule weights, revealed a negligible relationship with oil content.

• Structural Engineering and Mechanics
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• 제20권6호
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• pp.673-693
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• 2005

A general step-by-step simulation for the time-dependent analysis of segmentally-erected prestressed concrete box-girder bridges is presented. A three dimensional finite-element model for the balanced-cantilever construction of segmental bridges, including effects of the load history, material nonlinearity, creep, shrinkage, and aging of concrete and the relaxation of prestressing steel was developed using ABAQUS software. The models included three-dimensional shell elements to model the box-girder walls and Rebar elements representing the prestressing tendons. The step-by-step procedure allows simulating the construction stages, effects of time-dependent deformations of materials and changes in the structural system of the bridges. The structural responses during construction and throughout the service life were traced. A comparison of the developed computer simulation with available experimental results was conducted and good agreement was found. Deflection of the bridge deck, changes in stresses and strains and the redistribution of internal forces were calculated for different examples of bridges, built by the balanced-cantilever method, over thirty-year duration. Significant time-dependent effects on the bridge deflections and redistribution of internal forces and stresses were observed. The ultimate load carrying capacities of the bridges and the behavior before collapse were also determined. It was observed that the ultimate load carrying capacity of such bridges decreases with time as a result of time-dependent effects.

• 대한토목학회논문집
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• 제31권2A호
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• pp.51-58
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• 2011

이 연구는 중소경간 교량상판의 구조적 효율성과 경제성을 향상시키고 시공시 환경오염이나 교통흐름을 방해할 수 있는 공정을 최소화하기 위한 새로운 형식의 Inverted-T형 거더(이하 IT거더)의 개발을 위한 시험연구이다. 이 공법은 기존의 교량형식보다 미관이 아름답고, 시야확보가 우수한 합성교량상판의 형식으로서 최근 국내 현장에서 당면하고 있는 기능 인력의 고령화로 인한 인력 수급의 어려움을 해결할 수 있는 방편의 하나이다. 따라서 중소경간 교량상판의 설계와 시공을 위한 새로운 IT거더 공법은 시공성 향상과 건설비용 절감을 위한 효과적인 방법으로 사료된다.

• 한국환경복원기술학회지
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• 제10권1호
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• pp.36-43
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• 2007

This study was carried out to know how erosion control function of forests varies as forests develop in watersheds. The erosion control function among the forest welfare functions can be estimated by comparing sediment yield in stocked with non-stocked area. Sediment yield of reservoirs in stocked area were collected from farmland improvement associations. The sediment yields in non-stocked area were using USLE (Universal Soil Loss Equation) in the same reservoirs. Forests' erosion control function estimated by differences of the sediment yield between stocked and non-stocked area was static model because of no consideration on forest aging. Dynamic model was developed to consider a forest stand age. The model comprises the relationship between average forest age in watershed and sediment yield. The amount of sediment yield was different depending mother rocks. It decreased exponentially according to the forest's grow up. In case of igneous rock, the volume of sediment yield $Y_{ig}=1.4431e\;^{0.023x}$(x=average forest age), metamorphic rock $Y_{me}=4.7115e\;^{0.0694x}$, and sedimentary rock $Y_{se}=1.2808e\;^{0.028x}$.

• 한국주거학회논문집
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• 제23권6호
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• pp.31-38
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• 2012

In this paper, we draws tendency of the electricity consumption in residential buildings according to inhabitants Composition types and the level of incomes. it is necessary to reduce energy cost and keep energy security through the electricity demand forecasting and management technology. Progressive social change such as increases of single household, the aging of society, increases in the income level will replace the existing residential electricity demand pattern. However, Only with conventional methods that using only the energy consumption per-unit area are based on Energy final consumption data can not respond to those social and environmental change. To develop electricity demand estimation model that can cope flexibly to changes in the social and environmental, In this paper researches propensity of electricity consumption according to the type of residents configuration, the level of income. First, we typed form of inhabitants in residential that existed in Korea. after that we calculated hourly electricity consumption for each type through National Time-Use Survey performed at the National Statistical Office with considering overlapping behavior. Household appliances and retention standards according to income level is also considered.

• 보건교육건강증진학회지
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• 제8권1호
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• pp.5-13
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• 1991

While the threat from traditional communicable diseases have been decreasing non communicable chronic diseases are increasing due to the aging of population and change in life pattern of the people such as over intake of cholesterol and lack of physical exercise etc. On the other hand, since 1980s, AIDS is spreading rapidly throughout the globe and environmental pollution, accidents, addictive diseases such as drug abuse and alcoholism are becoming serious factors to hinder the health promotion of the people. In order to improve general public health and promote individual health status, existing program for communicable disease control by the government such as tuberculosis, leprosy, STD and acute communicable diseases should be effectively continued. In principle, effort should be placed on eradication of source of infection, reduction of communicability of source in infection, treatment of source of infection as well as increase of individual registance to the diseases through immunization and improvement of physical status. Since the pattern of illness is being shifted from communicable diseases to non communicable chronic diseases such as cancer, cerebral hemorrhage, heart disease and hypertention etc., special emphasis should be placed on the prevention and control of those adult diseases. Early detection of the patients, registration and treatment of patients and health education should be systematically developed for effective control of the diseases. In addition, program activities on MCH, nutrition, dentistry, mental health, environmental health, accident prevention. medical delivery system, health insurance. and all other health issues should be improved in order to achieve our goal of health promotion.

• 자원환경지질
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• 제45권2호
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• pp.205-215
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• 2012

금속이온은 토양이나 퇴적물 내의 광물에 수착되어 고착화될 수 있다. 여기서는 광물 표면의 화학적 특성과 금속이온의 수착에 관련된 이론 및 수착 연구를 위한 X-선 흡수 미세구조(extended X-ray absorption fine structure, EXAFS) 분석방법에 대해 알아보고 금속이온의 광물표면 수착에 관한 원자 단위 연구 결과를 정리하였다. 광물표면의 특성과 금속이온의 수착에 관한 원자 단위 이론의 이해는 원자 단위 분광법의 분석을 수행하는데 있어서 기초가 된다. 여기에 정리된 원자 단위 수착상 연구 결과는 외부권 착물, 내부권 착물, 표면침전뿐 아니라 공침전, 삼성분 착물, 수착반응 시간의 효과, 탈착가능성을 포함한다.

• 한국식품영양학회지
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• 제33권4호
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• pp.399-405
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• 2020

The purpose of this study was to analyze existence of active senior and their sodium intake using the 7th Korea National Health and Nutrition Survey. The samples used for this study were 1,336 males and 1,857 females older than age 45. We used the K-means cluster analysis to distinguish the elderly and one-way analysis of variance (ANOVA) to compare the means statistically among the groups. The analysis confirmed the existence of active seniors and showed different characteristics from other clusters. Also, the sodium intake in active seniors varies with other clusters depending on gender, economic status, social participation and health. In conclusion to reduce the unnecessary social cost of health deterioration of the elderly caused by aging, it is desirable to implement a class-specific policy based on the results of this study.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• 제31권2호
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• pp.80-87
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• 2020

Objectives: The prevalence of psychiatric disorders among young adults is different from that among younger or older age groups because of biological and environmental changes. The purpose of this study was to analyze the diagnostic distribution of psychiatric disorders in 19-30-year-old Koreans based on their age and gender using data from the Korean National Health Insurance Service (NHIS). Methods: From the 2011 medical claims sample data of NHIS of 1,375,842 people, we extracted the data of 221,038 people aged 19-30 years, including 106,232 (48.1%) men and 114,806 (51.9%) women. We evaluated the overall changes in the diagnostic distribution of psychiatric disorders over a 3-year period. Results: The diagnostic frequency in women was 13,627 (59.0%), which was significantly higher than that in men. "Other anxiety disorders" was the most common psychiatric disorder in both genders, followed by depressive episodes, somatoform disorders, "other neurotic disorders," and nonorganic sleep disorders. In men, attention-deficit/hyperactivity disorder or intellectual disabilities were not among the top 10 disorders. In women, no significant changes in major psychiatric disorders were seen over the 3-year period. Conclusion: These results reveal the trends of diagnostic distribution of mental illnesses depending on the development, particularly in young adulthood. It is necessary to identify whether such trends are due to biological or environmental factors, aging processes, or complex influences.