• Journal of the Korea Concrete Institute
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• v.25 no.5
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• pp.517-528
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• 2013

The modular technology has been already applied in automotive industry, plant and shipbuilding industry. Recently, the modular technology was applied in bridge construction. The modular bridge is different from the existing precast bridges in terms of standardized design that the detailed design of members is omitted by using the standard modules; the design of the modular bridge is completed by only assembling the standard modules without design in member level. The girder-type precast modular bridge has been developed as a simply supported bridge. The girder-type precast modular bridge could be applied to the multi-span bridges through the continuity method. The continuity of the girder-type precast modular bridge is achieved by using the link slab which is easy to construction and appropriate to the rapid construction. The link slabs have been used as the type of reinforced concrete structure in US from the 1950's. In 2000's, the link slab using the engineered cementitious concrete (ECC link slab) has been developed. In this study, the RC type link slab which is more reproducible and economic relative to the ECC link slab was used for the continuity of the girder-type precast modular bridges, and the construction detail of RC type link slab was modified. In addition, the modified iterative design method of RC type link slab was proposed in this study. To verify the proposed design method, the flexural tests were conducted using the RC type link slab specimens. Also, the fatigue test using the mock-up specimen was conducted with cyclic loading condition up to two million cycles.

• Journal of the Korean Applied Science and Technology
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• v.32 no.4
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• pp.649-660
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• 2015

Data obtained from the Calpuff inverse modeling estimate the emission amount of pollutants, and enable to establish the aim for reduction through the comparison of various cases. This study pursued to accumulate the fundamental data by the Calpuff inverse modeling for five areas in the vicinity of Donghae harbor, which focused on reduction of atmospheric fine dust. As a result of evaluation of the allowed emission amount for local sites, site-D required the most reduction, $4.95{\mu}g/m^2{\cdot}S$, based on the atmospheric guideline, $50{\mu}g/m^3$. The theoretical mitigation could decrease the average concentration of PM10 to $42.6{\mu}g/m^3$ for the study field (Donghae waste water treatment plant). Modeling only for site-A emission showed the potential concentration around the residential area of Donghae harbor, $40{\sim}50{\mu}g/m^3$. However, it will rise over $50{\mu}g/m^3$ with the addition of background level. Therefore no more emission would be allowed. Site-B including commercial area and unpaved field required the reduction of $0.11{\mu}g/m^2{\cdot}S$ due to vehicles and fugitive dust. Site-C and E did not emit additional pollutants.

• Journal of the Korean Applied Science and Technology
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• v.30 no.2
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• pp.320-332
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• 2013

The feed air to MSW incinerator influences on the residence time of combustion gas, removal of unburnt ash and exiting gas temperature. Thus the secondary air volume could present sufficient residence time which can maintain the exiting temperature over $850^{\circ}C$. The secondary air also relates directly with the turbulence in the inside of combustion chamber, which finally provide the stable combustion condition. The present study designed a modern incinerator for a field scale, and evaluation of the potential amount of primary air based on the daily combustible quantity. From the evaluated primary air volume, the secondary air flow rate could be estimated, and its dynamic behavior was verified. In addition, the obtained air volume enables to find an optimum operation condition of the combustion. As a result of the CFD simulation, the air ratio 75 : 25 between primary and secondary air amount was optimum ratio than design criteria 72 : 28. And the flow velocity ratio of front-back of secondary air jet nozzle was found excellent at 1 : 3. In addition, the result of applied to the plant, the removal efficiency of NOx and CO generation would concentration of CO.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.10
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• pp.259-266
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• 2020

In this study, required drill bits and excavation methods were developed for an uneven drilling method that can solve the problem of performance degradation of rock bolts. The developed drill bit's excavation performance was verified using rock with a strength of 100 MPa or more. In addition, for the relative evaluation of the uneven excavation method, experimental specimens were prepared for models with and without irregularities, and tests were performed. As a result of the experiment, the model with unevenness exhibited an average critical draw resistance of 801.6 kN, which is about 1.7 times the value of 468.7 kN for the model without unevenness, thus confirming the effect sufficiently. Therefore, it is expected that the resistance performance will significantly increase despite an increase in the uneven hole diameter of 20 mm. In the future, the results of this study could be used as basic data when performing other studies using numerical analysis models and performance verification through experiments to obtain an optimized rock forming method.

• Journal of Nutrition and Health
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• v.35 no.5
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• pp.544-557
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• 2002

This study was performed to evaluate the quality of nutrient intakes of the hemodialysis patients (26 men and 23 women) according to the socioeconomic status by 3-day dietary recall in Daejeon city and Chungnam area, Korea. Mean age of the subjects was 50.7 yrs and BMI was 22.0 $\pm$ 0.4 kg/$m^2$. Education level was divided into two groups ($\leq$ 9 years： LE group, 9 years： HE group), and monthly family income level was divided into three groups (< 500,000 won: LI group, 500,000-1,499,999 won: MI group, $\geq$ 1,500,000 won : HI group). The data were analyzed by Student t-test and Oneway ANOVA using SPSS 9.0 version at p < 0.05 level. Intakes of energy, carbohydrates, cholesterol, potassium, thiamin and riboflavin were significantly higher in HE group than in LE group (p < 0.05). Intakes of all the nutrients except protein and phosphorus were less than Korean RDA, and INQs (Index of Nutritional Quality) of most nutrients were lower than 1.0 but cholesterol, phosphorus. thiamin and niacin being over 1.0 in HE group. MAR (Mean adequacy ratio) of all the nutrients (e.g., energy, protein, calcium, phosphorus, iron, vitamin A, vitamin C, thiamin, riboflavin and niacin) was significantly higher in HE group (0.61 $\pm$ 0.04) than in LE group (0.48 $\pm$ 0.03) at p = 0.036. Intakes of energy, protein (total, animal and plant), fat, cholesterol, potassium, calcium, phosphorus, iron, vitamin A, thiamin and riboflavin were also significantly higher in HI group than in LI and MI group (p < 0.05). Daily intakes of most nutrients were less than Korean RDA except protein ed phosphorus in HI poop, and INQs of thiamin, niacin and phosphorus were higher than 1.0, while those of calcium, iron, vitamin A and riboflavin were lower than 1.0. MAR of energy and 9 nutrients was significantly higher in HI group (0.70 $\pm$ 0.04) than in LI group (0. 56 0.04) and MI poop (0.47 $\pm$ 0.03) at p = 0.000. In conclusion, quality of nutrient intakes, especially energy and protein, was significantly influenced by socioeconomic status such as education and monthly income (p < 0.05). This result suggests that it would be very helpful to develop nutritional education programs considering hemodialysis patients' education levels, and to improve public supports (e.g., medical insurance system, low-rate lease system of dialysis equipments, etc.) focusing on the patients' family income levels f3r their better nutrition and health.

• Journal of Nutrition and Health
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• v.42 no.2
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• pp.146-157
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• 2009

Korean diet is high in plant foods but also high in salted vegetables. World Cancer Research Fund (WCRF) recommends consumption of fruits and vegetables excluding salted vegetables for prevention cancer. This study aimed to analyze relations between intakes of salted and non-salted vegetables and socioeconomic factors, providing a data for targeted groups in promotion of fruits and vegetables consumption. Dietary and socioeconomic status data of the 5,400 subjects over 30 years of age from the 2005 Korea National Health and Nutrition Examination Survey (KNHANESIII) were used. Dietary intake data from KNHANESIII was obtained by one day 24-hour recall method. Mean daily intakes of salted vegetables, non-salted vegetables and fruits of subjects were 151 g, 237 g, and 71 g respectively. Mean daily intake of salted vegetables was significantly higher in men than women for daily amount (173 g vs. 133 g) as well as percentage of total food intake (9.9% vs. 9.6%). Subjects living in rural area consumed more salted vegetables. Salted vegetables as percent of total food were lower in subjects with higher education levels (p < 0.001). Intakes of non-salted vegetables were significantly affected by age and gender. Intake levels of fruit were significantly higher in younger groups, in females, and subjects with higher income and education levels (p < 0.05). Average intake of fruits and non-salted vegetables was 307 g, lower than WCRF recommended level of 400 g for personal guideline. Intake of salted vegetables was positively correlated with sodium intake (Pearson's correlation coefficient, r = 0.43) but less so with potassium (r = 0.16) and other micronutrients intake (r < 0.1). On the other hand, non-salted vegetables had higher correlations with potassium (r = 0.45), carotene (r = 0.38), vitamin A (r = 0.37), iron (r = 0.34) and low for sodium (r = 0.13). Fruits intake was highly correlated with vitamin C intake (r = 0.46). Proportion of subjects satisfying WCRF personal guideline of fruits and non-salted vegetables was 25.7%. Results of this study indicate that intake of salted vegetable is considerably high among Koreans, and it is highly correlated with sodium intake and less so with other micronutrients.

• Journal of Wetlands Research
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• v.14 no.4
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• pp.699-713
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• 2012

Palustrine wetland is often used for development work and green area creation. However, the ecological characteristic of vegetation is not frequently considered in planning. Therefore, this study was conducted to investigate vegetation characteristic according to land-use of palustrine wetland and to provide basic materials in assessment of palustrine wetland and restoration and creation of wetland. Survey sites were caterogized into paddy, field, and mountain. Each category had two sites, so total 6 survey sites were investigated for vegetation. As a result, with a range of 61~92 species, total 216 taxa were confirmed, consisting of 71 families, 168 generic, 187 species, 2 variety 1 forma 1 subforma. Mountain received a high score in the evaluation score range of floristic regional indicator plants, and it was found that there were 10 families and 28 species of naturalized plant. Mountain showed low appearance, and fiddy and field showed relatively high appearance. Naturalized plants with slightly high vegetation cover ratio are Erigeron annuus, Amorpha fruticosa, Dactylis glomerata, Festuca arundinacea, Eragrostis curvula, Trifolium repens, Erigeron Canadensis, Ambrosia trifida, Oenothera odorata, Bidens frondosa, etc. Such naturalized plants should be removed to prevent terrestrialization of wetland and its harmful damages. Long-term monitoring and proper management of naturalized plants are expected to improve palustrine wetland into high quality biotope of rural area in the future.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.4
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• pp.53-60
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• 2017

Fly ash(FA) which is a byproduct in the coal combustion in thermal power plant contributes to pore structure densification due to pozzolanic reaction, and this leads to long-term strength development and excellent resistance to chloride penetration. In the work, compressive strength and chloride resistance in OPC(Ordinary Portland Cement) and FA-based concrete are evaluated, and the relationships are investigated considering ages. For the work, 3 different W/B (Water to Binder) ratios of 37%, 42%, and 47% are prepared, and 3 substitution ratio of fly ash(0%, 30%, and 50%) are considered as well. At the age of 28 days and 180 days, test results of compressive strength, diffusion coefficients based on Tang's method, and passed charges referred to ASTM C 1202 and KS F 2711 are obtained. With increasing replacement ratio of FA and decreasing W/B, the resistances to chlorides(diffusion coefficient and passed charge) are improved, and the results at the age of 180 days decrease to only 15% level at the age of 28 days due to pozzolanic reaction in FA 50 mixture, which shows that resistance to chloride is much dependent on age effect than strength development. After 180 days, more clear linear relationships are observed between strength and resistance to chloride.

• Journal of Korean Society of Forest Science
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• v.69 no.1
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• pp.42-50
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• 1985

The vegetation of common Cryptomeria (Cryptomeria japonica D. Don) stands planted in Chonnam- province was investigated to obtain the fundamental informations for evaluation of suitable site and the improvement of managing method of the Cryptomeria stands in this region. The results investigated were summarized as follows; 1) The growth condition of common Cryptomeria planted 21-25-year-old stands was similar that of same species growing in Akidaken-district in Japan, while the growth condition of 51-58-year-old stands was not so good as that of Japanese. 2) Total number of plant species was 256. The number of floristic composition varied in the range of 42-99- species, which should be mere than those of Japanese. 3) The investigated sites were located in temperate southern part and in subtropic northern part of Korean peninsular. The types of understory vegetation were classified from I to IV class. 4) From the results of high max. possible diversity (H' max), and dominance (1-J') and from the low simple dominance (${\lambda}$) and evenness (J'), It could be concluded that vegetation was relatively in evenness. 5) From the low percent similarity, the specificity among the stands could be evaluated as considerable. 6) After the index of Morista, the 8th stand in Chang sung showed the generalized vegetation, while the 12th stand in Chang hung showed the specialized vegetation. 7) From the low values of Sneath-Sokal distance, the similarity among the stands investigated appeared very high.

• Korean Journal of Community Nutrition
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• v.14 no.5
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• pp.495-508
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• 2009

The purpose of this study was to evaluate the eating behaviors and dietary quality of various aged adults. This study conducted through questionnaire and dietary survey by 24-hr recall to 850 adults residing in Samcheok. Subjects were divided into four groups according to the age in male and female, which included 20~29 yrs group (male n = 94, female n = 66), 30~49 yrs group (male n = 201, female n = 216), 50~64 yrs group (male n = 88, female n = 96), and $\geq65$ yrs group (n = 46, female n = 43). In male, 20~29 yrs group had a larger proportion of subjects who skipped breakfast, lunch and dinner compared to other groups (p < 0.001, p < 0.05, p < 0.01). The daily food and energy intakes in $\geq50$ yrs group were significantly lower than those of < 50 yrs. Protein and fat intakes of 20~29 yrs group were significantly higher than those of the other groups. But ND (Nutrient Density) of minerals as like calcium, iron and plant iron in 20~29 yrs group were significantly lower than those of other groups. The KDDS (Korean's Dietary Diversity Score) of 20~29 yrs group, 30~49 yrs group, 50~64 yrs group and $\geq65$ yrs group in male were 4.1, 3.8, 3.7 and 3.5 respectively and there was significant difference (p < 0.001). In female, skipping breakfast and dinner were significantly higher in 20~29 yrs group than in other groups (p < 0.001, p < 0.001). And the use of nutrient supplementation was higher in 30~49 yrs group than that of other groups (p < 0.05). The daily energy intakes was higher in 20~49 yrs group than that of $\geq65$ yrs group. The ND (Nutrient Density) of animal protein, vitamins A and $B_1$ in 20~29 yrs group were significantly lower than those of other groups. The KDDS of 20~29 yrs group, 30~49 yrs group, 50~64 yrs group and $\geq65$ yrs group in female were 4.0, 3.9, 3.9 and 3.6 respectively and $\geq65$ yrs group was significant lower than other groups. According to these results, $\geq65$ yrs and 20~29 yrs group had more dietary habit problems and poor nutrition status than 30~64 yrs group. The results of this study revealed that nutritional management and education for adequate meals should be emphasized in adults and elderly.