• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.6
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• pp.1731-1741
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• 2014

Recently, many overpasses, highway, and advanced transit systems have been constructed to distribute the traffic congestion, thus small size of curved bridges with small curvature such as ramp structures have been increasing. Many of early curved bridges had been constructed by using straight beams with curved slabs, but curved steel beams have replaced them due to the cost, aesthetic and the advantage in building the section form and manipulating the curvature of beams, thereby large portion of curved bridges were applied with steel box girders. However, steel box girder bridges needs comparatively high initial costs and continuous maintenance such as repainting, which is the one of the reason for increasing the cost. Moreover, I-type steel plate girder which is being studied by many researchers recently, seem to have problems in stability due to the low torsional stiffness, resulting from the section characteristics with thin plate used for web and open section forms. Therefore, in recent studies, researchers have proposed curved precast PSC girders with low cost and could secured safety which could replace the curved steel girder type bridges. Hence, this study developed a Smart Mold system to manufacture efficient curved precast PSC girders. And by using this mold system a 40 m 2-girder bridge was constructed for a static flexural test, to evaluate the safety and performance under ultimate load. At the manufacturing stage, each single girder showed problems in the stability due to the torsional moment, but after the girders were connected by cross beams and decks, the bridge successfully distributed the stress, thereby the stability was confirmed. The static loading test results show that the initial crack was observed at 1,400 kN when the design load was 450 kN, and the load at the allowable deflection by code was 1,800 kN, which shows that the safety and usability of the curved precast PSC bridge manufactured by Smart Mold system is secured.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.3
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• pp.343-349
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• 2010

The liver is the major target of ethanol toxicity and oxidative stress plays a role in development of alcoholic liver disease. This study was performed to investigate the effects of green tea extracts (GTE) on acute ethanol-induced hepatotoxicity in rats. Experimental animals were divided into 4 groups, control, GTE, ethanol, and GTE+ethanol treatment, with 5 rats in each group. Ethanol (6 g/kg body weight (BW)) and GTE (200 mg/kg BW) were treated by gavage. At 1 hour, 3 hours and 20 days (6 g/kg BW every 2 days for total 10 doses) after ethanol and/or GTE treatments, animals were killed; hepatic tumor necrosis factor-alpha (TNF-$\alpha$) and glutathione level, serum aspartate aminotransferase (AST), serum alanine aminotransferase (ALT), hepatic antioxidant enzymes (SOD, CAT, GPx) activities and hepatic thiobarbituric acid reactive substances (TBARS) were measured. At 1 hour and 3 hours, hepatic TNF-$\alpha$ levels were increased significantly in ethanol group and ethanol+GTE group but that levels was significantly lower in ethanol+GTE group compared with ethanol group. Hepatic glutathione level was decreased by ethanol treatment but GTE prevented the ethanol-induced glutathione decrement. The levels of liver marker enzymes (AST, ALT), liver antioxidant enzymes (SOD, CAT, GPx) and lipid peroxidation marker (TBARS) were not changed in rats of 1 and 3 hours after ethanol treatment. After 20 days, GTE decreased the changes of liver marker enzymes (AST, ALT) activities and TBARS level by ethanol. This study shows that GTE beneficially modulates TNF-$\alpha$ and glutathione levels in liver of ethanol administered rats. The GTE supplementation could be beneficial to liver by decreasing early changes of biomarkers of liver damage caused by ethanol.

• Journal of Korean Society of Forest Science
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• v.109 no.3
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• pp.259-270
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• 2020

Extreme weather events, such as heat and drought, have occurred frequently over the past two decades. This has led to continuous reports of cases of forest damage due to physiological stress, not pest damage. In 2014, pine trees were collectively damaged in the forest genetic resources reserve of Sogwang-ri, Uljin, South Korea. An investigation was launched to determine the causes of the dieback, so that a forest management plan could be prepared to deal with the current dieback, and to prevent future damage. This study aimedto 1) understand the topographic and structural characteristics of the area which experienced pine tree dieback, 2) identify the main causes of the dieback, and 3) predict future risk areas through the use of machine-learning techniques. A model for identifying risk areas was developed using 14 explanatory variables, including location, elevation, slope, and age class. When three machine-learning techniques-Decision Tree, Random Forest (RF), and Support Vector Machine (SVM) were applied to the model, RF and SVM showed higher predictability scores, with accuracies over 93%. Our analysis of the variable set showed that the topographical areas most vulnerable to pine dieback were those with high altitudes, high daily solar radiation, and limited water availability. We also found that, when it came to forest stand characteristics, pine trees with high vertical stand densities (5-15 m high) and higher age classes experienced a higher risk of dieback. The RF and SVM models predicted that 9.5% or 115 ha of the Geumgang Pine Forest are at high risk for pine dieback. Our study suggests the need for further investigation into the vulnerable areas of the Geumgang Pine Forest, and also for climate change adaptive forest management steps to protect those areas which remain undamaged.

• Investigative Magnetic Resonance Imaging
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• v.7 no.2
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• pp.100-107
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• 2003

Purpose : To assess the usefulness of cardiac MR imaging (MRI) in the diagnosis of acute myocardial infarction and in the assessment of myocardial viability in comparision with T1-201 SPECT. Materials and Methods : We retrospectively studied 17 patients who complained of chest pain and dyspnea with cardiac MRI . The patients were evaluated for the presence or absence of high signal intensity on T2-weighted image (T2wI), abnormal wall motion on 2D-FIESTA, perfusion defect on Gd-DTPA enhanced T1WI, and delayed myocardial enhancement on 15-minutes delay Gd-DTPA enhanced T1WI. The results were correlated with the images on T1-201 SPECT, taken at rest and stress, through which reversibility of perfusion defect was assessed. Results : Both cardiac MRI and T1-201 SPECT proved to be useful methods for diagnosing acute myocardial infarction. In order of decreasing correspondence, T2WI, T1-201 SPECT, delayed enhancement study, and wall motion images all showed significant statistical correlation with the clinical diagnosis of myocardial infarction. Perfusion MRI, on the other hand, showed no significant statistical difference was found between T1-201 SPECT and cardiac MRI. The results on T2WI showed high accordance with those on Tl-201 SPECT, while delayed myocardial enhancement and wall motion studies showed no agreement with Tl-201 SPECT. Conclusion : Cardiac MRI is useful method for diagnosis of acute myocardiac infarction. With respect to the assessment of myocardial viability, the results obtained on cardiac MRI showed high agreement with those on Tl-201 SPECT. However, further study is necessary at this point for standardization and establishment of the methods for assessing myocardial viability on cardiac MRI.

• Journal of agricultural medicine and community health
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• v.31 no.3
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• pp.275-284
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• 2006

Objectives: This investigation was carried out to understand the status of the urinary incontinence (UI) and overactive bladder (OABs) syndrome of women in a rural region. Methods: The authors conducted a questionnaire survey among the 322 females who voluntarily participated in a health examination, from 16 to 18 August 2001. Using by definition of UI and OABs, we calculated the proportion of UI, OABs I, and OABs II. The data collected was evaluated using the SPSS 12.0 statistical package, and the differences of symptoms and problems related to daily life between UI, OABs patients and the others were analyzed using a Chi-square test or Fisher's exact test. Results: The overall proportion of UI was 35.4%, and stress UI (32.9%) is more common than urgency UI (17.4%) and mixed UI (14.9%). The proportion of OABs I and OABs II were respectively 36.0%, 14.0%. Symptoms related to UI or OABs were nocturia (35.1%), frequency (23.9%), urgency (21.4%) etc. Of the incontinence cases, 27.2% had experienced UI for a period of one to three years. The proportion of OABs increased significantly by age (p<0.05), UI didn't. The most frequent symptoms in UI and OABs were respectively 'slow stream', 'urgency'. The most frequent problem of daily life in UI and OABs was 'seeking toilet firstly at stranger place'. Conclusions: The proportion of UI and OABs in our study were respectively 35.4%, 14.0%. UI and OABs must be very significant health problems in women, especially rural region. Systemic and profound interventions for UI and OABs need to administer to women in Korea.

• Journal of agricultural medicine and community health
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• v.36 no.2
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• pp.87-100
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• 2011

Objectives: This study aimed to identify factors associated with smoking relapse. Methods: The study sample was recruited among subjects who were enrolled in the smoking cessation clinic of a public health center and had succeeded in quitting smoking for at least six months. A total of 159 male subjects were followed via mail survey one year later. The independent variables in the analyses were socio-demographic characteristics, smoking history and behavior, receipt of smoking cessation aids, health behaviors and components of the health belief model (HBM). The dependent variable was smoking relapse assessed one year after quitting. Ordered logit regressions were used to identify factors associated with smoking relapse. Results: The relapse rate of the ex-smokers in our sample was 25.8%, and the occasional smoking rate was 17.0%. Univariate analyses revealed that only factors related to the HBM, such as perceived susceptibility to diseases (p<0.01), perceived severity of diseases (p<0.01), perceived health benefits of not smoking (p<0.01), perceived barriers to quitting smoking due to increasing stress and difficulty in social life (p<0.01), and self-efficacy (p<0.01) were associated with the likelihood of relapse for ex-smokers. Ordered logit analyses yielded two significant factors affecting the likelihood of relapse, the perceived barriers to quitting smoking and self-efficacy. Conclusions: Our results indicate that higher levels of barriers to quitting smoking and lower levels of self-efficacy were significantly related to risk of smoking relapse. These findings may be useful for identifying those at highest risk for relapse and choosing the optimal strategies for prevention of relapse for ex-smokers.

• Korean Journal of Community Nutrition
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• v.19 no.3
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• pp.241-249
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• 2014

Objectives: This study was to determine diabetes fatalism of diabetic patients with and without diabetic foot and its association with lifestyle, diet, and self-care. Methods: The subjects were diabetic patients with (male/female 48/21) and without diabetic foot (male/female 33/26). We administered the questionnaires which were designed to determine diabetes fatalism, lifestyle, diet, and self-care. Diabetes fatalism was determined by Diabetes fatalism scale (DFS), which consisted of total 12 items in three subscales namely, emotional stress, religiou spiritual coping, and perceived self-efficacy. Results: The patients with diabetic foot had undesirable diets more frequently (1.37 and 0.91 days/week respectively) and their desirable diets (2.74 and 3.61 days/week respectively) and foot care (4.61 and 5.53 days/week respectively) were less frequent than those without diabetic foot (p < 0.05). An item analysis of the 12 DFS items revealed a Chronbach' ${\alpha}$ of 0.614 and 0.869, respectively in diabetic patients with and without diabetic foot. Perceived self-efficacy related DFS of subjects without diabetic foot was positively associated with smoking (r=0.350, p<0.01), undesirable diet (r=0.295, p<0.05), and drinking (r=0.257, p<0.05), while its negative association with exercise (r=-0.224, p<0.088) and foot care (r=-0.247, p<0.059) did not reach to statistical significance. Conclusions: This work was the first study reporting the potential usefulness of DFS, especially perceived self-efficacy related subscale as a predictor of lifestyle, diet and self-care on the Korean diabetic patients, at least those without severe diabetic foot to screen those who should be the first target for diabetes education.

• The Journal of Korean Academy of Prosthodontics
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• v.48 no.1
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• pp.55-60
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• 2010

Purpose: The shrinkage of dental resin cement may cause several clinical problems such as distortion that may jeopardize the accurate fit to the prepared tooth and internal stress within the restorations. It is important to know the polymerization shrinkage-strain of dental resin cement to reduce clinical complications. The purpose of this study was to investigate the polymerization shrinkage-strain kinetics of six commercially available dental resin cements. Material and methods: Three self-cure resin cements (Fujicem, Superbond, M-bond) and three dual-cure resin cements (Maxcem, Panavia-F, Variolink II) were investigated. Time dependent polymerization shrinkage-strain kinetics of the materials were measured by the Bonded-disk method as a function of time at $23^{\circ}C$, with values particularly noted at 1, 5, 10, 30, 60, 120 min after mixing. Five recordings were taken for each materials. The data were analyzed with one-way ANOVA and Scheffe post hoc test at the significance level of 0.05. Results: Polymerization shrinkage-strain values were 3.72%, 4.19%, 4.13%, 2.44%, 7.57%, 2.90% for Fujicem, Maxcem, M bond, Panavia F, Superbond, Variolink II, respectively at 120 minutes after the start of mixing. Panavia F exhibited maximum polymerization shrinkage-strain values, but Superbond showed minimum polymerization shrinkage-strain values among the investigated materials (P < .05). There was no significant differences of shrinkage-strain value between Maxcem and M bond at 120 minutes after the start of mixing (P > .05). Most shrinkage of the resin cement materials investigated occurred in the first 30 minutes after the start of mixing. Conclusion: The onset of polymerization shrinkage of self-cure resin cements was slower than that of dual-cure resin cements after mixing, but the net shrinkage strain values of self-cure resin cements was higher than that of dual-cure resin cements at 120 minutes after mixing. Most shrinkage of the dental resin cements occurred in the first 30 minutes after mixing.

• Journal of the Korea Concrete Institute
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• v.14 no.1
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• pp.126-135
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• 2002

Plate bonding technique has been widely used in strengthening of existing concrete structures, although it has often a serious problem of premature falure such as interface separation and rip-off. However, this premature failure problem has not been well explored yet especially in view of local failure mechanism around the interface of plate ends. The purpose of the present study is, therefore, to identify the local failure of strengthened plates and to derive a separation criterion at the interface of plates. To this end, a comprehensive experimental program has been set up. The double lap pull-out tests considering pure shear force and half beam tests considering combined flexure-shear force were performed. The main experimental parameters include plate thickness, adhesive thickness, and plate end arrangement. The strains along the longitudinal direction of steel plates have been measured and the shear stress were calculated from those measures strains. The effects of plate thickness, bonded length, and plate end treatment have been also clarified from the present test results. Nonlinear finite element analysis has been performed and compared with test results. The Interface properties are also modeled to present the separation failure behavior of strengthened members. The cracking patterns as well as maximum failure loads agree well with test data. The relation between maximum shear and normal stresses at the interface has been derived to propose a separation failure criterion of strengthened members. The present study allows more realistic analysis and design of externally strengthened flexural member with steel plates.

• Journal of Bio-Environment Control
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• v.21 no.4
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• pp.419-427
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• 2012

This study was carried out to investigate the effect of two shading methods, shading agent spray on the glasshouse and internal shading screen treatment, on the growth and fruit quality of paprika (Capsicum annuum L. 'Cupra' and 'Coletti') in summer season cultivation. In the shading agent treatment, a commercial shading agent diluted with water at a ratio of 1 : 4 was sprayed on the roof of a glasshouse. In the internal shading screen treatment, a 10~20% shaded screen was used during the day time when the sun radiation was greater than $700W{\cdot}m^{-2}$. Compared to the unshaded control, photosynthetic photon flux density (PPFD) decreased in the greenhouse in the shading agent (SA) and shading screen (SS) treatments by 20% and 30%, respectively. Lower air temperatures and higher relative humidities were observed in the SA than in both the control and the SS treatment. Time to reach the break point of humidity deficit $8g{\cdot}m^{-3}$ was 2 hours late in the SA than in both the control and the SS treatment. Compared to control, both the SA and the SS treatments showed lower instantaneous temperatures of leaf, fruit, and flower by $2^{\circ}C$, $5^{\circ}C$ and $3^{\circ}C$, respectively. There were no differences in number of branches, stem diameter, and leaf size among treatments although both shading treatments promoted plant height in both cultivars. Botrytis infection ratio declined with the SA treatment by 14.7% in 'Cupra' and 22.1% in 'Coletti' as compared to that in the control. Shading increased fruit size in both cultivars, whereas no differences were observed in the number of locules and thickness of fruit tissue among treatments. Shading treatment increased mean fruit weight by a range of 10 to 15 g per fruit, while it decreased soluble solids contents as compared to that in the control. Similar Hunter values were observed among treatments, while fruit firmness increased slightly in shading treatments. Compared to the control, shading treatments improved marketable fruits by 11.7~22.6% and increased the number of fruits per plant by 4~9.2 in both 'Cupra' and 'Coletti'. The results of this study indicate that shading agent application on the roof of glasshouse would be one of the most effective options to reduce heat stress imposed on the paprika crop in summer cultivation, resulting in improved crop growth and fruit yield.