• Journal of the Korea Organic Resources Recycling Association
• /
• v.31 no.1
• /
• pp.47-56
• /
• 2023

This study describes the successful synthesize strategy for the silica nanoparticles utilizing various water sources, including tap, industrial, and stream waters without using deionized water. Also, as-synthesized silica nanoparticles are employed as dispersive materials for the electro-responsive smart fluid application. Specifically, homogeneous silica nanoparticles with sizes of 500-700nm are successfully prepared in large scale at once (ca. 12.0 g) with the described experimental method and showing similar structural and chemical characteristics with silica nanoparticles synthesized using the deionized water. The size of silica nanoparticles are varied according to the ion conductivity differences of tap, industrial, stream water, and deionized water. The size of silica nanoparticles decresed with the increased ion conductivity, indicating the ion suppression of growth of silica nanoparticles. Moreover, as-synthesized silica nanoparticles from various water sources of electro-responsive characteristic are investigated by the smart fluid application. The smart fluids containing silica nanoparticles synthesized by tap, industrial, and stream water exhibited higher shear stress compared to the deionized water, owing to the more rigid fibril-like structures formed by the smaller silica nanoparticles. Conclusively, uniform silica nanoparticles from various water sources without any purification are able to successfully prepared without usage of deionized water and resulting silica nanoparticles manifested higher electro-responsive performance.

• Korean Journal of Poultry Science
• /
• v.51 no.2
• /
• pp.97-106
• /
• 2024

This study utilized the non-invasive MyotonPRO^® device to analyze the stiffness in breast muscles of commercial broilers (Ross 308 and Arbor Acres) and compared these findings with data reported for Ross 708, where Woody Breast (WB) symptoms had been previously documented. The research revealed that Ross 308 and Arbor Acres displayed relatively lower stiffness values compared to Ross 708, suggesting a lack of WB expression. These results indicate differentiation in breast muscle traits across strains and underscore the necessity for further research into factors influencing WB manifestation. The study also measured additional muscle tone characteristics such as Frequency, Decrement, Relaxation, and Creep across various growth stages (2, 4, 6, and 8 weeks), finding significant variations with pronounced severity at weeks 2 and 8. An increase in stiffness was observed as the broilers aged, pointing to potential growth-related or stress-induced changes affecting WB severity. A strong positive correlation was established between increased breast meat weight and WB severity, highlighting that heavier breast meat could exacerbate the condition. This correlation is vital for the poultry industry, suggesting that weight management could help mitigate WB effects. Moreover, the potential for genetic selection and breeding strategies to reduce WB occurrence was emphasized, which could aid in enhancing management practices in commercial poultry production. Collectively, these insights contribute to a deeper understanding of WB in broilers and propose avenues for future research and practical strategies to minimize its impact.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.34 no.2
• /
• pp.515-527
• /
• 2014

This study conducted experiment for understanding engineering characteristics of domestic sands by examining standard sand and sand from Yokji Island and Nakdong River in terms of confining pressure, $K_0$, over consolidation and relative density factors through triaxial compression test. The test showed that deviator stress by strain positively changed as confining pressure and relative density grow while $K_0$ and over consolidation factors do not directly correlated with it. Angle of internal friction decreases as confining pressure increases which strengthens contact force between particles, and declines as relative density drops, whereas $K_0$ and over consolidation factors hardly affect the results. When it comes to volumetric strain, volume expansion decreases as confining pressure increase due to crushability and rearrangement of particles while $K_0$ and over consolidation shows same movement unconditionally, and relative density appears compressed as it grows at the beginning however it expands as axial strain increases. Modulus of elasticity ($E_{sec}$) by strain has tendency into convergence resulting in initial secant modulus of elasticity ($E_{ini}$) > secant modulus of elasticity($E_{sec}$) > tangent modulus of elasticity ($E_{tan}$). On the other hand, it grows as confining pressure and relative density increase while indicating similar modulus of elasticity ($E_{sec}$) regarding on $K_0$ and over consolidation. Slope of critical line (M) tended to decrease as confining pressure increases, follow same line according to $K_0$, confining pressure and relative density, and increase as relative density grows.

• Journal of agricultural medicine and community health
• /
• v.35 no.4
• /
• pp.370-382
• /
• 2010

Objectives: The purpose of this study was to investigate the level of health promoting behaviors and the significant factors in rural elderly(young-old vs old-old). Methods: The data was collected using structured questionnaires from June 22th to Sep. 18th, 2009. A total of 556 elderly aged 65 years or over were selected from 14 rural districts in C province, South Korea. Age was divided into two groups as below 65-74 and 75 or older. A structured questionnaire was used to obtain information on the demographic characteristics, their perceived health status, the difficulty of activities of daily living, quality of life, self-efficacy and health promoting behaviors. The health promoting behaviors included nutrition, stress management, interpersonal support, exercise, health responsibility and self-actualization. The scores for health promoting behaviors were used mean and standard deviation. The data was analyzed using SPSS Win 12.0. Results: Of the 556 subjects, we found that the young-old(65-74 aged) were 359 and the old-old elderly(over 75 aged) were 197. We found that the level of health promoting behavior was higher for young-old ($2.75{\pm}0.374$) compared to old-old elderly people ($2.67{\pm}0.399$). In multiple linear regression, quality of life, self-efficacy, living with spouse, and number of generation living together for the young-old, and quality of life for old-old elderly were significantly associated with health promoting behaviors. Conclusions: The study findings indicate that there are age differences in associated factor of health promoting behaviors. Therefore our findings may provide useful assistance in developing effective intervention programs to improve health promoting behavior of the elderly in rural areas according to their age differences.

• The korean journal of orthodontics
• /
• v.25 no.1 s.48
• /
• pp.55-72
• /
• 1995

The purpose of this study is to evaluate the effects of mechanical and thermal fatigue on the shear bond strength(SBS) in orthodontic brackets bonded to human premolars with chemically cured adhesive(Mono-$Lok^2$, Rocky Mountain Orthodontics). Two types of metal brackets (Ormesh, Microloc) and three types of ceramic brackets (Fascination, Starfire, Transcend 2000) were used in this study. The $10^6$ loadcycles of $|7.4{\times}10{^2}sin2{\pi}ft|g{\cdot}cm$ and the 1,000 thermocycles of 15 second dwell time each in $5^{\circ}C\;and\;55^{\circ}C$ baths were acturated as mechanical and thermal fatigue stress, and SBS were measured after each fatigue test. The fracture sites were examined by stereoscope and scanning electron microscope. The results obtained were summarized as follows, 1. In static shear bond test, Fascination brackets showed the maximum SBS($20.78\pm3.45$ MPa) and Microloc brackets showed the minimum SBS($14.88\pm3.10$ MPa). Fascination and Starfire brackets showed significantly greater SBS than Microloc brackets(P<0.05). 2. In mechanical fatigue test, Fascination brackets showed the maximum SBS ($20.19\pm3.45$ MPa) and Starfire brackets showed the minimum SBS($9.10\pm8.33$ MPa). The SBS or Transcend 2000 brackets(P<0.01) and Starfire brackets(P<0.05) significantly decreased after $10^6$ loadcycles. 3. In thermocycling test, Ormesh brackets showed the maximum SBS ($19.36\pm2.76$ MPa) and Starfire brackets showed the minimum SBS($11.94\pm6.86$ MPa). The SBS of Transcend 2000(P<0.01), Microloc and Starfire brackets(P<0.05) significantly decreased after $10^3$ thermocycles. 4. Failure sites of thermocycling groups were similar to those of static groups but after mechanical fatigue test, Ormesh and Transcend 2000 brackets failed at the bracket/resin interface and Microloc brackets failed within adhesive. Facination brackets failed at the enamel/resin interface irrespective of experimental condition.

• Journal of the Korean Wood Science and Technology
• /
• v.13 no.2
• /
• pp.14-34
• /
• 1985

One of the techniques for altering the properties of wood that has received considerable attention in the last twenty years is the formation of a wood-polymer composite (WPC) by irradiation and heat-catalyst polymerization of a monomer incorporated into the wood matrix. Wood-polymer composites are the new products having the superior mechanical and physical properties and the combinated characteristics of wood and plastic. The purpose of this experiment was to obtain the basic data for the improvement of wooden materials by manufacturing WPC and Staypak. The species examined was Hyunsasi-Namoo (Populus alba ${\times}$ P. glandulosa) which had not been utilized yet. Methylmethacrylate (MMA) as monomer, benzoyl peroxide (BPO) as initiator and methyl alcohol as bulking agent were used. The monomer containing BPO was impregnated into wood pieces by the dipping and the vacuum process for 2 hours. After impregnation, the treated samples were polymerized on the hot press with pressure and heat-catalyst methods. The results obtained were summarized as follows 1. The monomer loading into wood by the dipping process was 12.13 percent and 29.99 percent by the vacuum. The polymer loading into wood by the dipping process was 6.79 percent and 15.44 percent by the vacuum. 2. Comparing with Staypak, antishrink efficiency (ASE) of WPC was 12.5 to 13.6 percent on the radial direction and 14.70 to 18.63 percent on the tangential. Antiswelling efficiency (AE) was 14.40 to 17.22 percent on the radial direction and 17.18 to 42.1 8 to 42.14 percent on the tangential. Reduction in water absorptivity (RWA) was 8.19 to 15.5 percent. As a whole, the vacuum process was better than the dipping. 3. The specific gravity of control, Staypak and WPC were 0.44, 0.66 and 0.61 to 0.62, respectively. 4. In the bending strength test, the strength in case that the load direction is on the radial surface was greater than that which the load direction is on the tangential. 5. Increasing rate of stress at proportional limit in compression perpendicular to grain was 72.26 percent in case of WPC by the dipping process, 78.93 percent by the vacuum and 99.09 percent in case of Staypak.

• The Journal of Korean society of community based occupational therapy
• /
• v.3 no.1
• /
• pp.1-10
• /
• 2013

Objective : This study investigates the impact of the musculoskeletal disorder prevention exercise program designed on the basis of agricultural work posture on the balance ability, Oswestry Disability level, and Psychosocial stress of participants from one rural village in Chungnam area. Method : The exercise program was provided to 21 farmers with musculoskeletal symptoms living in one village in Chungnam area. Such program was performed once a week, 90 minutes per session, for a total of twelve weeks from July 10 to October 11, 2008, and was constructed in a way to increase flexibility and muscular strength, taking agricultural work posture into account. The balance ability, Oswestry Disability Index, and Psychosocial Well-being Index scores were analyzed based on the data of 13 of the farmers who participated in the program for more than eight times and in all of the pre- and post-assessments. Result : Thirteen participants were all women who were 70.55(${\pm}6.78$) years old on average. Most of them were engaged in general dry-filed farming. The parts where they mainly felt the pain were low back(69.2%) and knees(61.5%), and 46.2% responded 'not healthy' to the question on the overall health status. The static balance ability when standing on the right foot significantly increased from the average 9.27(${\pm}5.53$) seconds before intervention to 14.22(${\pm}5.47$) seconds after intervention(p<.05). The Oswestry Disability Index showed a significant change, decreasing from the average 19.84(${\pm}6.89$) seconds to 14.38(${\pm}7.58$) seconds(p<.05). However, there was no change in the Psychosocial Well-being Index. Conclusion : This exercise program that has been conducted for the female farmers who are mainly engaged in the dry-filed farming has contributed to the improvement of their static ability and reduction of their Oswestry Disability Index scores. It is expected that the studies on the effects of the differentiated exercise programs depending on work characteristics will make progress in the future.

• Journal of the Korean Geophysical Society
• /
• v.7 no.3
• /
• pp.193-206
• /
• 2004

Geophysical data including chirp (3 7 kHz) subbottom profile and detailed bathymetry were obtained over three seamounts in the Ogasawara Fracture Zone (OFZ) of the western Pacific, as a part of manganese crust survey onboard R/V Onnuri in 2003. The OFZ is a 150-km-wide, 600-km-long rift zone, which separates the East Mariana and Pigafetta Basin. The OFZ is unique in that it includes many seamounts (e.g., Magellan Seamounts andseamounts on the Dutton Ridge). The sub-seafloor acoustic echoes obtained near the OFZ were classified into following types on the basis of their characteristics: types I-1(pelagic sediment with parallel or subparallel reflectors), I-2 (pelagic sediment with no internal reflectors), and III-1 (reef build-up complex) on summit; types II-1 and III-2 (basement outcrop) on flank rift zone and upper slope, respectively; type III-3 (slump) on the lower slope and embayment between the flank rift zones; types II-2 (debrite) on the base of slope and basin floor; and types II-3 (turbidite or pelagic sediment) and II-4 (turbidite) on the basin floor. The mass-wasting that produced the complex of type II-2 debrite and III-3 slump on the lower slope and basin may have been caused by (1) strong tensional stress in the OFZ which may cause the numerous fissures or basement faults and (2) complex of the faults on the summit and steep upper slope. The variations in the echo type of pelagic sediment in the summit of seamounts may be related with the changes in the depositional and/or erosional environments. Type I-2 pelagic sediment, which is characterized by a thin and intermittent coverage, was probably deposited at a sheltered area when the current was strong, whereas type I-1 pelagic deposit occurred during a stage of progressive sedimentation.

• Pediatric Gastroenterology, Hepatology & Nutrition
• /
• v.11 no.2
• /
• pp.179-186
• /
• 2008

Purpose: Feeding problems are common for typically developing children and have negative effects on physical, behavioral, and cognitive development. The purpose of the current study was to examine factors related to childhood feeding problems for typically developing children via parental reports. Methods: The feeding questionnaire developed by the authors and the Childhood Eating Behavior Inventory (CEBI) were administered to 796 parents of children who recruited from 2 pediatric outpatient clinics (n=379) and community (n=417). Problem eaters (PE) were identified by parental report and frequency analysis was conducted for types of feeding problems and its severity, problem behaviors during mealtime, the feeding methods of the parents, and the need for treatment. Results: The CEBI scores were significantly different between the PE and non-problem eaters (NPE), which suggests that the parental reports were reliable. The younger children had more feeding problems than the older children. The most frequent and severe feeding problems were selective eating and longer mealtimes across all age groups. One-half of the children had more than one problem behaviors during mealtime. Most parents of PE used ineffective methods to deal with children's behaviors during meal time, such as cajoling, which was related to their increased level of stress. Many parents reported their children need professional help for the feeding problems. Conclusion: Feeding problems are prevalent among children, especially younger children. Children with feeding problems showed a number of problem behaviors during mealtime and parental coping methods appeared to be ineffective. The need for treatment was considerable, thus the characteristics of this population must be acknowledged for providing proper treatment and advice.

• Korean journal of communication and information
• /
• v.46
• /
• pp.108-147
• /
• 2009

This study explores the news frames on the U. S. beef imports and candlelight vigils covered by the two national dailies such as ChosunIlbo and the Hankyoreh Shinmun; the KwangwonIlbo, a local daily. The news frames extracted based on the models of Iyengar(1987), Semetko & Valkenburg(2000) and other researchers are attribution of responsibility, economic sequences, protest against the authorities, national health and governmental public relations and so on. The result shows that the news reports are consisted of the straight news(75.9%), feature stories(11.7%) and editorials(6.3%). More specifically, there is a comparatively hight ratio of editorials(11.0%) for the ChosunIlbo, feature stories(20.9%) for the Hankyoreh, and the straight news(89.7%) for the KwangwonIlbo. In terms of the news frames stressed by the three dailies, the ChosunIlbo focuses and stresses on the national health(17.8%) and the attribution of responsibilities(10.6%). However, the Hankyoreh have a tendency to stress on the protest against the authorities(31.3%) and attribution of responsibilities(38.4%); the KwangwonIlbo, focuses on the protest against the authorities(38.4%) and the economic sequences(17.9%). Finally, in the case of the main characteristics of the dailies, the governmental public relations frame is found only on the ChosunIlbo that has a comparatively high ratio; the Hankyoreh also has a high ratio of the feature stories on the U. S. beef imports. Even thought the KwangwonIlbo has a high ratio of the economic sequence frame, the ratio of opinion pages, such as editorial and columns, the local newspaper has not spoken up for the potential economic crisis of the local Kwangwon province beef industry, mainly caused by the U. S. import beef.