• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.3A
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• pp.201-209
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• 2010

Generally, PSC girder bridge uses total gross cross section to resist applied loads unlike reinforced concrete member. Also, it is used as short and middle span (less than 30 m) bridges due to advantages such as ease of design and construction, reduction of cost, and convenience of maintenance. But, due to recent increased public interests for environmental friendly and appearance appealing bridges all over the world, the demands for longer span bridges have been continuously increasing. This trend is shown not only in ordinary long span bridge types such as cable supported bridges but also in PSC girder bridges. In order to meet the increasing demands for new type of long span bridges, PSC hollow box girder with H-type steel as compression reinforcements is developed for bridge with a single span of more than 50 m. The developed PSC girder applies compressive prestressing at H-type compression reinforcements using unbonded PS tendon. The purpose of compressive prestressing is to recover plastic displacement of PSC girder after long term service by releasing the prestressing. The static test composed of 4 different stages in 3-point bending test is performed to verify safety of the bridge. First stage loading is applied until tensile cracks form. Then in second stage, the load is removed and the girder is unloaded. In third stage, after removal of loading, recovery of remaining plastic deformation is verified as the compressive prestressing is removed at H-type reinforcements. Then, in fourth stage, loading is continued until the girder fails. The experimental results showed that the first crack occurs at 1,615 kN with a corresponding displacement of 187.0 mm. The introduction of the additional compressive stress in the lower part of the girder from the removal of unbonded compressive prestressing of the H-type steel showed a capacity improvement of about 60% (7.7 mm) recovery of the residual deformation (18.7 mm) that occurred from load increase. By using prestressed H-type steel as compression reinforcements in the upper part of cross section, repair and rehabilitation of PSC girders are relatively easy, and the cost of maintenance is expected to decrease.

• Health Policy and Management
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• v.34 no.1
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• pp.78-86
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• 2024

Background: The purpose of this study was to determine the effectiveness of the specialty hospital system by comparing the medical use of inpatients who had artificial joint replacement surgery in specialty hospitals and non-specialty hospitals. Methods: This study utilized 2021-2022 healthcare benefit claims data provided by the Health Insurance Review and Assessment Service. The dependent variable is inpatient medical use which is measured in terms of charges per case and length of stay. The independent variable was whether the hospital was designated as a specialty hospital, and the control variables were patient-level variables (age, gender, insurer type, surgery type, and Charlson comorbidity index) and medical institution-level variables (establishment type, classification, location, number of orthopedic surgeons, and number of nurses). Results: The results of the multiple regression analysis between charges per case and whether a hospital is designated as a specialty hospital showed a statistically significant negative relationship between charges per case and whether a hospital is designated as a specialty hospital. This suggests a significant low in charges per case when a hospital is designated as a specialty hospital compared to a non-specialty hospital, indicating that there is a difference in medical use outcomes between specialty hospitals and non-specialty hospitals inpatients. Conclusion: The practical implications of this study are as follows. First, the criteria for designating specialty hospitals should be alleviated. In our study, the results show that specialty hospitals have significantly lower per-case costs than non-specialty hospitals. Despite the cost-effectiveness of specialty hospitals, the high barriers to be designated for specialty hospitals have gathered the specialty hospitals in metropolitan and major cities. To address the regional imbalance of specialty hospitals, it is believed that ease the criteria for designating specialty hospitals in non-metropolitan areas, such as introducing "semi-specialty hospitals (tentative name)," will lead to a reduction in health disparities between regions and reduce medical costs. Second, it is necessary to determine the appropriateness of the size of hospitals' medical staff. The study found that the number of orthopedic surgeons and nurses varied in charges per case. Therefore, it is believed that appropriately allocating hospital medical staff can maximize the cost-effectiveness of medical services and ultimately reduce medical costs.

• Journal of Nutrition and Health
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• v.49 no.5
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• pp.378-394
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• 2016

Purpose: Screening of preschool-age children for nutrition programs to improve dietary intake and behaviors requires cost-effective and easily administered validated assessment tools. The purpose of this study was to develop a parent/caregiver-administered instrument for measuring diet quality and behaviors of preschoolers as a nutrition quotient for preschoolers (NQ-P). Methods: Development of NQ-P was carried out in three steps: item generation, item reduction, and validation. The 24-h dietary record was selected as the gold standard reference tool. The 38 items of the NQ-P checklist were derived from a systematic literature review, expert in-depth interviews, statistical analysis of the fifth Korean National Health and Nutrition Examination Survey data, and national nutrition policies and recommendations. Self-administered questionnaires were delivered to parents who recorded 24-h dietary intakes of 100 responders aged 3~5 yr. Pearson's correlation was used to measure the level of agreement between questionnaires. Item reduction was performed, and 20 items were selected based on survey results, expert reviews, and priorities of national nutrition policy and recommendations. The 412 nationwide subjects sampled through daycare centers completed the 20-item checklist questionnaire. The construct validity of the NQ-P was assessed using confirmatory factor analysis, LISREL. Results: After analyses of exploratory factors, NQ-P items identified three dimensions of diet (balance, moderation, and environment). The three-factor structure accounted for 49.28% of the total variance. Standardized path coefficients were used as weights of the items. The NQ-P and three-factor scores of the subjects were calculated by the obtained weights of the questionnaire items. Conclusion: A food behavior checklist for preschoolers' NQ would be a useful and suitable instrument for evaluating nutrition adequacy and dietary quality of Korean preschoolers.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.12
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• pp.5937-5942
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• 2012

This study used silicon that is similar to the density of the tissue of the human body to compensate for the uneven areas that are in contact with air in order to reduce susceptible artifacts. The subjects of the study were 16 normal people and the areas of the human body in which there are a lot of uneven areas with complicated structure and a lot of susceptible artifacts were formed since the surface area that comes into contact with the air is large were the areas that were chosen to be examined. A 3.0T superconducting magnetic resonance device was used as the test equipment and SPIR images that are sensitive to magnetic differences were obtained as sagittal planes on a line that extended the metatarsal and the phalanges, including the middle of the longitudinal arc and the 5 distal phalanxes. The method of analysis was to reduce the susceptibility between the tissue and the air to discover the reduction of susceptible artifacts by comparing the SNR and CNR before and after applying silicon. A statistical analysis was utilized for the sample matching T examination. The results of the study revealed that the susceptible artifacts were reduced in the images of the uneven areas that were compensated and applied with silicon. The SNR increased in significant amount in correlation from $3.91{\pm}1.33$ before application to $21.69{\pm}4.52$ after application and the CNR decreased in significant amount in correlation from $28.97{\pm}8.20$ before application to $4.88{\pm}2.14$. In conclusion, this study did not affect the voxel but it was an innovative method of improvement that compensated for the fundamental issue of the difference in susceptibility between the air and the body. The application is simple and the study has great significance in that it proposed a method to reduce susceptible artifacts in a low cost and highly efficient manner.

• Journal of Korean Society for Atmospheric Environment
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• v.33 no.4
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• pp.377-392
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• 2017

A set of BFM (Brute Force Method) simulations with the CMAQ (Community Multiscale Air Quality) model were conducted in order to estimate self-contributions and conversion rates of PPM (Primary $PM_{2.5}$), $NO_x$, $SO_2$, $NH_3$, and VOC emissions to $PM_{2.5}$ concentrations over the SMA (Seoul Metropolitan Area). CAPSS (Clean Air Policy Support System) 2013 EI (emissions inventory) from the NIER (National Institute of Environmental Research) was used for the base and sensitivity simulations. SCCs (Source Classification Codes) in the EI were utilized to group the emissions into area, mobile, and point source categories. PPM and $PM_{2.5}$ precursor emissions from each source category were reduced by 50%. In turn, air quality was simulated with CMAQ during January, April, July, and October in 2014 for the BFM runs. In this study, seasonal variations of SMA $PM_{2.5}$ self-sensitivities to PPM, $SO_2$, and $NH_3$ emissions can be observed even when the seasonal emission rates are almost identical. For example, when the mobile PPM emissions from the SMA were 634 TPM (Tons Per Month) and 603 TPM in January and July, self-contributions of the emissions to monthly mean $PM_{2.5}$ were $2.7{\mu}g/m^3$ and $1.3{\mu}g/m^3$ for the months, respectively. Similarly, while $NH_3$ emissions from area sources were 4,169 TPM and 3,951 TPM in January and July, the self-contributions to monthly mean $PM_{2.5}$ for the months were $2.0{\mu}g/m^3$ and $4.4{\mu}g/m^3$, respectively. Meanwhile, emission-to-$PM_{2.5}$ conversion rates of precursors vary among source categories. For instance, the annual mean conversion rates of the SMA mobile, area, and point sources were 19.3, 10.8, and $6.6{\mu}g/m^3/10^6TPY$ for $SO_2$ emissions while those rates for PPM emissions were 268.6, 207.7, and 181.5 (${\mu}g/m^3/10^6TPY$), respectively, over the region. The results demonstrate that SMA $PM_{2.5}$ responses to the same amount of reduction in precursor emissions differ for source categories and in time (e.g. seasons), which is important when the cost-benefit analysis is conducted during air quality improvement planning. On the other hand, annual mean $PM_{2.5}$ sensitivities to the SMA $NO_x$ emissions remains still negative even after a 50% reduction in emission category which implies that more aggressive $NO_x$ reductions are required for the SMA to overcome '$NO_x$ disbenefit' under the base condition.

• Korean Chemical Engineering Research
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• v.58 no.3
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• pp.325-345
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• 2020

Determination of Best available technology (BAT) was suggested to reduce volatile organic compounds (VOCs) in a petrochemical industrial complex, by conducting human health risk, environmental, and economic assessment based on multimedia fugacity model. Fate and distribution of benzene, toluene, ethylbenzene, and xylene (BTEX) was predicted by the multimedia fugacity model, which represent VOCs emitted from the industrial complex in U-city. Media-integrated human health risk assessment and sensitivity analysis were conducted to predict the human health risk of BTEX and identify the critical variable which has adverse effects on human health. Besides, the environmental and economic assessment was conducted to determine the BAT for VOCs reduction. It is concluded that BTEX highly remained in soil media (60%, 61%, 64% and 63%), and xylene has remained as the highest proportion of BTEX in each environment media. From the candidates of BAT, the absorption was excluded due to its high human health risk. Moreover, it is identified that the half-life and exposure coefficient of each exposure route are highly correlated with human health risk by sensitivity analysis. In last, considering environmental and economic assessment, the regenerative thermal oxidation, the regenerative catalytic oxidation, the bio-filtration, the UV oxidation, and the activated carbon adsorption were determined as BAT for reducing VOCs in the petrochemical industrial complex. The suggested BAT determination methodology based on the media-integrated approach can contribute to the application of BAT into the workplace to efficiently manage the discharge facilities and operate an integrated environmental management system.

• Journal of the Korean Wood Science and Technology
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• v.46 no.1
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• pp.48-59
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• 2018

This study was conducted to suggest the effective management and recycling processes of coffee waste, which can be easily obtained from coffee shops and coffee-related products industries. Prior to the fabrication of pellets, the potential of coffee waste as a raw material of pellet was investigated through the examination of its chemical compositions and fuel characteristics. Major gradient included in coffee waste was holocellulose, followed by fat/oil and protein. Coffee waste contained a small quantity of ash (0.7%), such as calcium, sodium, potassium and magnesium. Interestingly, coffee waste was easily dried probably due to its porous structure. Pellets fabricated with coffee waste and larch sawdust showed good fuel characteristics, such as moisture content, ash content, density and durability. The pellets exceed greatly the minimum requirements of $1^{st}$-grade wood pellet standard designated by National Institute of Forest Science (NIFOS). Particularly, the high calorific value of coffee waste showed the potential as a raw material of pellet. However, owing to high nitrogen and sulfur contents, coffee waste is like to be used as a raw material of wood pellet for combined heat and power plants equipped with a reduction system of $NO_x$ and $SO_x$ gases. On the other hand, 91 wt% larch sawdust and 9 wt% coffee waste are required to fabricate the $1^{st}$-grade wood pellets designated by NIFOS. Pellets fabricated with the conditions are estimated to have nitrogen content of 0.298% and sulfur content of 0.03%. Lastly, if amounts of coffee waste and sawdust in the production of wood pellets are adequately adjusted according to its purchasing price, the manufacturing cost of pellet can effectively be reduced. In addition, it is expected tp prepare the effective recycling process of waste and to relieve the environmental burden with the reduction of waste from the commercialization of coffee waste/larch pellets.

• Journal of agricultural medicine and community health
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• v.27 no.2
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• pp.17-26
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• 2002

Reducing the level of stress and insomnia by aromatherapy is proposed as a method of self-care and health promotion in the future. Of the people who received aromatherapy from July, 1999 to February, 2000 at the Complementary and Alternative Medicine Center at the Gyeongu City Health Center, 48 people agreed to participate in a questionnaire survey, presented before and after their aromatherapy, and the data were analyzed. When the people received aromatherapy at the Complementary and Alternative Medicine Center, they inhaled the aroma from a vaporizer and when at home, they inhaled from a tissue, gauze or washbowl. Two sessions per week (2 hrs./session) were provided at the Center in the total 1-month duration of the therapy. The oil made from a blend of clarysage, geranium, rose at a ratio of 3:2:1 was used for relieving stress, and the oil made from a blend of clarysage, lavender, and lemon at 2:2:1 ratio was used for relieving insomnia. The scores of stress of 92.5 17.5 points before aromatherapy significantly reduced to $87.4{\pm}4.2$ points after therapy(p<0.01), and the scores of insomnia of $2.5{\pm}1.2$ points before aromatherapy significantly reduced to $1.0{\pm}1.1$ points after therapy(p<0.01). The reduction in stress and insomnia from aromatherapy was more significant in those who were experiencing high levels of stress and insomnia. Therefore, stress and its related insomnia can be effectively relieved with proper application of aromatherapy. With benefits such as little side-effects, convenient and simple education, low cost, and the do-it-yourself feature. aromatherapy can be expanded into a self-management program for promoting health of the community people.

• Korean Journal of Weed Science
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• v.30 no.3
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• pp.272-281
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• 2010

The objective of this research was to find out the weed management techniques in environment-friendly rice paddy fields through the study on herbicidal effects and problems of various organic materials. This experiment was conducted under different conditions of weed species and weed densities in environment-friendly rice paddy fields. There was no difference in weedy efficacy on golden apple snail (GAS), paper mulching (PM), and machine weeding (MW) between low and high weed densities. However, the effect of weed control in rice bran (RB) and effective microorganism (EM) + molasses was higher in high weed density than in low weed density. In general, the effect of weed control as affected by various organic materials was in the order of GAS (97-100%) > PM (93-98%) > RB (15-80%) > EM (7-31%). GAS provided excellent control of all weed species tested except for Persicaria hydropiper. PM gave acceptable control of the weed species except for Echinochloa crus-galli, Ludwigia prostrata, and Eleocharis kuroguwai. However, MW gave fair control (70% biomass reduction) of all weed species tested. BR followed by MW or EM followed by MW treatments had similar effect on weed control compared to each treatment alone. However, BR followed by GAS or EM followed by GAS provided 100% control of weed species tested. The level of rice foliar injury caused by various organic materials was in the order of GAS and MW (10-20%) > RB (10-15%) > PM and EM (5-7%). Typical symptoms of organic materials are wilting, inhibition of growth, missing hill, and reduction of tiller. Cost for weed control of GAS, RB, EM, and PM were 2.1, 3.1, 2.3, and 13.2 times higher than that of the herbicide. These data indicate that GAS was the best method for weed management in environmentfriendly rice paddy fields. Further study is required to elucidate the mechanisms underlying the rice injury as affected by GAS.

• KDI Journal of Economic Policy
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• v.12 no.2
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• pp.81-94
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• 1990

Illegal transactions such as blackmarketing and smuggling allegedly result from too restrictive trade policies. A recent U.S. Senate hearing on the blackmarketing of American goods imported into Korea for the purpose of supporting United States troops and their dependents stationed in Korea concluded with the allegation that Korea's highly restrictive trade practices are responsible for the emergence of the black market. It has also suggested that the removal of such restrictive trade policies would eliminate black market activities. This study addresses the relationship between trade policy and blackmarketing by investigating whether trade liberalization results in the reduction of illegal transactions, and whether the eradication of blackmarketing indeed improves social welfare. When both legally imported goods and illegally exchanged items command the same price, trade liberalization, meaning a decrease in tariff rates or an increase in import quotas, will increase the quantity of legal imports at the expense of illegally transacted goods on the black market. But the price of legally imported goods usually differs from that of illegally sold ones. In this case, a change in the relative prices of these two groups of goods due to a change in trade policy will give rise to income, as well as substitution, effects. Initially, a decrease in the import price due to a decrease in import tax rates or an increase in the allotted quota will reduce illegal transactions, since the decrease in the import price will induce the substitution of legal imports for illegally exchanged, but otherwise, identical goods. On the other hand, the demand for the illegally transacted goods will rise, because of the income effect of the reduced import price. Thus, assuming the positive income effect overwhelms the negative substitution effect, the demand for illegal goods will increase, thwarting the reduction of blackmarketing through trade liberalization. Yet, stepping up the enforcement measures which are geared to preventing blackmarketing itself will drastically reduce the extent of illegal transactions, since it increases the cost of blackmarketing and hence the price of the illegally transacted goods. What this study suggests is that the emergence of the black market in Korea should be attributed more to the excessive supply of duty-free goods imported through U.S. commissaries and exchanges than to the excessive demand for foreign goods. On the other hand, blackmarketing, in most cases, improves economic welfare, since it constitutes an increase in the "actual" amount of imported goods. Suppressing blackmarketing through stepped-up enforcement methods is beneficial only when the substitution effect of the legally transacted goods resulting from the increase in the price of the illegal goods prevails, since the increase in the demand for legal imports must override the decrease in the demand for black market goods as well as the negative income effect.