• Animal Bioscience
• /
• v.34 no.7
• /
• pp.1243-1252
• /
• 2021

Objective: An experiment was conducted to investigate the continuous and intermittent lighting program effects on terms of the productive performance, carcass traits, blood biochemical parameters, innate immune and oxidative status in broiler chicks. Methods: A total of 600 Cobb-500 one day old chicks were randomly allocated into six equal groups (100 chicks per treated group with five replicates of 20 chicks each) based on lighting program; 22 continuous lighting (22 C), 11 h lighting+1 darkness twice daily (11 L/1 D), 20 h continuous lighting (20 C), 5 h lighting+1 darkness four times daily (5 L/1 D), 18 h continuous lighting (18 C) and the final group subjected for 3 h lighting+1 h darkness six times daily (3 L/1 D). The experimental period lasted 42 days. Results: Compared with those under the intermittent light program, broiler chicks exposed to continuous lighting for 22 h had significant improvement in live body weight and carcass (dressing and breast percentage) measured traits. Though reducing lighting hours significantly reduced feed intake and feed conversion ratio values. Different lighting programs revealed no significant effect on all blood biochemical parameters. Oxidative stress and innate immunity parameters significantly enhance by reducing lighting hours (3L/1D). Conclusion: The findings suggest that reducing lighting hours up to 3L/1D would be more useful in enhancing feed efficiency, innate immunity, and oxidative status compared with continuous lighting programs on broilers.

• Journal of Korean Dental Hygiene Science
• /
• v.4 no.1
• /
• pp.39-51
• /
• 2021

Background: Limited information is available regarding the associations of various nutrients and periodontitis in Korea. Furthermore, these associations have been controversial in previous studies. Therefore, the present study aimed to evaluate the associations between several nutrients and periodontitis. Methods: Pooled data from the 2007~2010 and 2012 Korea National Health and Nutrition Examination Surveys (KNHANES) were used for the present study. Periodontitis was defined using the World Health Organization (WHO) Community Periodontal Index. All participants completed the Food Frequency Questionnaire (FFQ), which was analyzed using CAN-Pro 4.0. Vitamins A, B₁, B₂, and C, iron, phosphorus, calcium, and protein were selected for analysis. Multiple logistic regression analyses were used to estimate the odds ratios (ORs) for periodontitis. Results: Lower intake of phosphorus (adjusted odds ratio [AOR] = 1.86), calcium (AOR = 1.25), and protein (AOR = 1.52) were associated with periodontitis in males, and lower intake of vitamins A (AOR = 1.32), B1 (AOR = 1.21), B2 (AOR = 1.24), and C (AOR = 1.21), iron (AOR = 1.25), phosphorus (AOR = 1.33), and protein (AOR = 1.27) showed significant relationships with periodontitis in females. In the sociodemographic, somatic, and health behavior-adjusted models, lower phosphorus (AOR = 2.68) and protein (AOR = 1.68) intake in younger males, and lower vitamin A intake (AOR = 1.37) in middle-aged females were significantly associated with periodontitis. Conclusions: The results of the present study demonstrated a significant association between periodontitis and nutrient intake. To avoid an insufficient nutrient supply for a patient with periodontal disease, the patient's diet should be closely monitored.

• Composites Research
• /
• v.34 no.4
• /
• pp.257-263
• /
• 2021

Composite materials have been widely applied for fabricating pressure vessels used for storing gaseous and liquid fuel because of their high specific stiffness and specific strength. Accordingly, the accurate measurement of their mechanical property, particularly the burst pressure or fracture strain, is essential prior to the commercial release. However, verification of the safety of composite pressure vessels using conventional test methods poses some limitations because it may lead to the deformation of the load transferring media or provoke an additional energy loss that cannot be ignored. Therefore, in this study, the segment-type ring burst test device was designed considering the theoretical load transferring ratio and applicable displacement of the vertical column. Moreover, to verifying the uniform distribution of pressure of the segment type ring burst test device, the hoop stress and strain distribution of ring specimens were compared with that of the hydraulic pressure test method via FEM. To conduct a simulation of the fracture behavior of the composite pressure vessel, a Hashin failure criterion was applied to the ring specimen. Furthermore, the fracture strain was also measured from the experiment and compared with that of the result from the FEM.

• Journal of Convergence for Information Technology
• /
• v.11 no.1
• /
• pp.199-207
• /
• 2021

This study was attempted to understand the effect of the violence victim experience of Korean adolescents on smoking using the data of the 15th (2019) online youth health behavior survey. The subjects of this study were 57,303 people, and the data were analyzed using the SPSS / Win 26.0 program for frequency analysis of complex samples, cross sample analysis (Rao-Scott ��2 test), and logistic regression analysis of complex samples. The main result was 12.7% of the smoking subjects. Those who smoked were significantly more 9.6% and 22.0%, respectively, compared to those who had no more than 1 or 2 times of violence. Smoking of Korean adolescents adjusted for gender, grade, academic record, economic status, drinking, family living, and usual stress increased the odds ratio for smoking by 1.66 times when the degree of violence damage experience increased by 1 unit. As a result of the above, as the degree of violence victimization of adolescents increases, the likelihood of smoking increases. Therefore, it is necessary to multidisciplinary convergence effort to the prevention and management of violence of adolescents, and to reduce the smoking of adolescents.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.26 no.1
• /
• pp.58-66
• /
• 2022

In this study, to examine the effect of the transverse thermal expansion behavior of FRP reinforcing bars and concrete on the concrete cover thickness, based on 20℃, when the temperature changes from -70℃ to 80℃, the behavior of concrete was studied theoretically and numerically. Theoretical elastic analysis and nonlinear finite element analysis were performed on FRP reinforced concrete with different diameters and cover thicknesses of FRP reinforcement. As a result, at a negative temperature difference, concrete was compressed, and the theoretical strain result and the finite element result were similar, but at a positive temperature difference, tensile stress and further cracks occurred in the concrete, which was 1.2 to 1.4 times larger than the theoretical result. The ratio of the diameter of the FRP reinforcing bar to the thickness of the concrete cover (c/db) is closely related to the occurrence of cracks. Since the transverse thermal expansion coefficient of FRP reinforcing bars is three times greater than that of concrete, it is necessary to consider this in design.

• Geomechanics and Engineering
• /
• v.30 no.4
• /
• pp.373-382
• /
• 2022

Unsaturated soil at high suctions is widespread. Many civil engineering projects are related to the hydro-mechanical behavior of unsaturated soils at high suctions, particularly in arid and semiarid areas. To investigate water retention behaviors of nine clayey soils (one is classified as fat clay and the others are classified as lean clay according to the unified soil classification system), the high suction (3.29-286.7 MPa) was imposed on the specimens at zero net stress by the vapor equilibrium technique. In this paper, the effect of void ratio on the water retention behavior at high suction was discussed in detail. Validation data showed that soil types, i.e., different mineralogical compositions, are critical in the soil water retention behavior at a high suction range. Second, the hysteresis behavior at a high suction range is mainly related to the clay content and the specific surface area. And the mechanism of water retention and hysteresis behavior at high suctions was discussed. Moreover, the maximum suction is not a unique value, and it is crucial to determine the maximum suction value accurately, especially for the shear strength prediction at high suctions. If the soil consists of hydrophilic minerals such as montmorillonite and illite, the maximum suction will be lower than 10⁶ kPa. Finally, using the area of hysteresis to quantify the degree of hysteresis at a high suction range is proposed. There was a good correlation between the area of hydraulic hysteresis and the specific surface area.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
• /
• v.32 no.4
• /
• pp.144-153
• /
• 2021

Objectives: Anxiety disorders are the most common psychiatric disorders in adolescents and seem to occur the earliest among all forms of psychopathology. The aim of this study was to investigate the association of anxiety severity with health risk behaviors and mental health in adolescents. Methods: Data from the 2020 Korean Youth Risk Behavior Web-Based Survey were analyzed. A total of 54948 adolescents responded to the 7-item Generalized Anxiety Disorder Scale (GAD-7) for the assessment of their anxiety severity as well as to the mental health and health risk behavior survey. Logistic regression analysis, t tests, and variance analysis of a complex sample general linear model were used to examine the association of anxiety severity with health behaviors and mental health. Results: After statistical adjustment for sociodemographic characteristics, the subjects in the severe anxiety group were significantly more likely to be current smokers (odds ratio [OR]: 2.08, 95% confidence interval [CI]: 1.72-2.50), current drinkers (OR: 1.91, 95% CI: 1.67-2.19), experience habitual substance use (OR: 10.89, 95% CI: 8.22-14.42), have sexual intercourse (OR: 2.10, 95% CI: 1.76-2.51), and have unprotected intercourse (OR: 2.21, 95% CI: 1.67-2.92) than those in the normal group. Anxiety severity negatively correlated with sleep satisfaction and happiness, but positively correlated with stress perception, loneliness, depressive symptoms, and suicidality. Conclusion: Adolescent anxiety is associated with health risk behaviors and poor mental health. Thus, early screening and intervention for anxiety in adolescents could contribute to the management and coping of youth health risk behaviors in the community.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.26 no.4
• /
• pp.40-47
• /
• 2022

The present study aimed to examine the effectiveness of different techniques for controlling the diagonal cracks at the corners of openings on the strength, deformation, and crack propagation in reinforced concrete walls. The crack control strip proposed in this study, the conventional diagonal steel reinforcing bars, and stress-dispersion curved plates were investigated for controlling the diagonal cracks at the opening corners. An additional crack self-healing function was also considered for the crack control strip. To evaluate the volume change ratio and crack width propagation around the opening, downsized wall specimens with a opening were tested under the diagonal shear force at the opening corner. Test result showed that the proposed crack control strip was more effective in reducing the volume change and controlling the crack width around the opening when compared to the conventional previous methods. The crack control strip with crack healing feature displayed the superior performance in improving the strength of the wall and reducing the crack width while healing cracks occurred in the previous tests.

• Journal of the Korean Society of Industry Convergence
• /
• v.25 no.5
• /
• pp.791-797
• /
• 2022

Using the fatigue limit (△σ_unsm) and residual stress (σ_r) of the UNSM smooth specimen, the harmless maximum crack depth (α_hml) according to the crack aspect ratio (As) was evaluated. α_hml evaluated the reliability in the relationship between the minimum crack depth (α_NDI1, α_NDI2) detectable by nondestructive inspection(NDI) and the crack depth (α₂₅, α₅₀) that reduces the fatigue limit by 25% and 50%. All α_hml was determined by the crack depth. The α_hml of 80N UNSM with high σ_r and high △σ_unsm was found to be large. σ_r in the depth direction had a much effect on α_hml. Since α_hml>α₅₀(As=0.6-0.1) and α_hml>α₂₅, α₂₅ and α₅₀(some range) can secure the safety and reliability. Since α_hml<α₅₀ (As=1. 0-0. 6), it cannot be made harmless by UNSM. So safety and reliability cannot be secured. α_NDI1 and α_NDI2 are larger than α₂₅, α₂₅ cannot be detected by NDI. α_NDI1 and α_NDI2 are smaller than α₅₀, α₂₅ can detected by NDI.

• Animal Bioscience
• /
• v.35 no.5
• /
• pp.721-729
• /
• 2022

Objective: An experiment was conducted to determine the effects of supplementing graded concentrations of inorganic sulphur (S) without and with folic acid (FA) in maize-soybean meal diets on performance, slaughter and anti-oxidant variables, immune responses and serum protein fractions in broiler chicken. Methods: Inorganic S was supplemented at 0.05%, 0.10%, 0.15%, and 0.20% alone or in combination with FA (4 mg/kg) in basal diet (BD) containing no supplemental methionine (Met) and FA. A control group was fed with the recommended concentration of Met. Each diet was offered to 10 pens of 5 male broiler chicks (Cobb 400) and fed ad libitum from day 1 to 42. Results: The broilers fed the BD had lower body weight gain (BWG), feed efficiency (FE), higher lipid peroxidation (LP), lower activity of glutathione peroxidase (GSHPx), lower lymphocyte proliferation ratio (LPR), and reduced concentrations of total protein, albumin, and globulin in serum. Supplementation of FA and S to the BD improved the BWG (all concentrations of S) and FE (0.20% S) similar to the control group. Similarly, the combination of S and FA significantly improved the concentrations of total protein, albumin, and globulin in serum, reduced the LP and increased the activity of GSHPx and LPR. However, responses in the above parameters were related to the concentration of S in the diet. The slaughter variables and antibody titres against the Newcastle disease were not affected with the treatments. Conclusion: Based on the results, it is concluded that the combination of S (0.2%) and FA (4 mg/kg) improved the BWG and FE, similarly supplementation of these nutrients improved the concentration of protein fractions and reduced the stress (reduced LP and improved GSHPx) variables in serum and improved the cell mediated immune response (LPR) in broilers fed sub-optimal concentrations of Met in diet.