• Applied Chemistry for Engineering
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• v.10 no.5
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• pp.718-725
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• 1999

In order to investigate the interaction characteristics of poly(dimethylsiloxane) (PDMS) with various solvents such as water, ethanol, and iso-propanol, Inverse Gas Chromatography(IGC) at finite concentration, which is a very fast, accurate, and thus promising technique in thermodynamic study of polymer systems, is employed. By measuring the specific retention volumes of the probes, the interaction parameters are calculated by means of the Flory-Huggins equation. From the results, the interaction parameters of the probes are, as expected due to the hydrophobicity of the polymer, found to be of large positive values (2$2.0{\times}10^{-3}mol/g$. For the linear PDMS, interpretation of the space distribution of molecules is performed by the Kirkwood-Buff-Zimm(KBZ) integrals, which give intuitive information about physical properties. From the KBZ integrals, water does not show the tendency of preferential solvation with the PDMS but formed self-cluster. The larger solvent molecules show a stronger tendency to distribute more randomly in the mixture.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.32 no.3
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• pp.78-84
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• 2009

The purpose of this study was to compare gait patterns during pregnancy. Because of the changes in hormone levels and anatomical changes such as body mass, body-mass distribution, joint laxity, and musculotendinous strength that result from pregnancy, it was possible that there would be certain gait deviations associated with these changes. Three-dimensional gait analyses were performed from a self-selected pace, and six subjects(height : $163{\pm}5.3cm$, mass : $61.3{\pm}3.80kg$, $65.3{\pm}5.14kg$, $70.2{\pm}4.98kg$) participated in the three times(the early, middle and last years). 7 cameras(Proreflex MCU-240, Qualisys) and 2 force plates (Type 9286AA, Kistler) were used to acquire raw data. The parameters were calculated and analyzed with Visual-3D and Joint moments computed using inverse dynamics. In conclusion, pregnant women's gait patterns were changed during pregnancy period because pregnancy makes them physical changes. The main changes were joint moments and kinematic factors during pregnancy period. The pregnancy transformed normal gait pattern Into toe out position. Therefore, exercise programs to improve muscle activity were necessary where joint moments were small. The development of simulator should be studied for pregnant women's tailored shoes and accessories in future.

• Korean Journal of Occupational Health Nursing
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• v.18 no.2
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• pp.262-269
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• 2009

Purpose: The purpose of this study was to explore job stress, job satisfaction and their relationship among Workers' Compensation Case Managers. Method: 137 Workers' Compensation Case Managers (89 case workers and 48 nurses) responded to a self-administered questionnaire. The data were collected in october, 2006 and analyzed using t-test and Pearson's Correlation Coefficient with SPSS WIN 14.0 program. Result: The mean score of job stress of nurses was 2.60 which was higher than that of the Korean female workers'. The mean score of job satisfaction was 2.30. The significant inverse correlation between job stress and job satisfaction was found (P<.01). In regard to the 7 items, the significant inverse correlations were found in lack of reward, interpersonal conflict, organizational system, insufficient job control, and occupational environment. Conclusion: The result indicated that the Workers' Compensation Case Managers have higher occupational stress and lower job satisfaction. To improve their job satisfaction, it is necessary to reinforce reward, organizational system, job autonomy, and cooperative occupational environment.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.7
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• pp.723-729
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• 2012

Spring-like leg models have been employed to explain various dynamic characteristics in human walking. However, this leg stiffness model has limitations to represent complex motion of actual human gait, especially the behaviors of each lower limb joint. The purpose of this research was to determine changes of total leg stiffness and lower limb joint stiffness with gait speed in knee osteoarthritis. Joint stiffness defined as the ratio of the joint torque change to the angular displacement change. Eight subjects with knee osteoarthritis participated to this study. The subject walked on a 12 m long and 1 m wide walkway with three sets of four different randomly ordered gait speeds, ranging from their self-selected speed to maximum speed. Kinetic and kinematic data were measured using three force plates and an optical marker system, respectively. Joint torques of lower limb joints calculated by a multi-segment inverse dynamics model. Total leg and each lower limb joint had constant stiffness during single support phase. The leg and hip joint stiffness increased with gait speed. The correlation between knee joint angles and torques had significant changed by the degree of severity of knee osteoarthritis.

• Steel and Composite Structures
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• v.49 no.2
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• pp.125-141
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• 2023

Firstly, a new kind of prismatic tensegrity structures with redundant cables is defined, the topology, geometry and forming conditions of which are introduced further. The development of its mechanical properties including self-stress states and structural stiffness with the increment of the twist angle is also investigated carefully. Combined with the topology of this kind of structures, a reasonable erection scheme is proposed, in which some temporary lifting points need to be set and two groups of vertical cables are tensioned in batches. Then, a simplified dynamic relaxation method is employed to track the erection process inversely, which aims to predict each intermediate equilibrium state during the construction, and give the key structural parameters that can effectively guide the construction. The removal of the active cables, the relaxation or tension of the passive cables are simulated by controlling their axial stiffness, so that the structural composition as well as the serial numbers of the elements always keep invariant regardless of the withdrawal of the slack cables. The whole analysis process is clear in concept, simple to implement and easy to popularize. Finally, several examples are given to verify the practicability and effectiveness of the proposed method further.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.6 no.3
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• pp.369-381
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• 1999

The purpose of this study was to determine the predictors of health promoting lifestyles(Health Promoting Lifestyle Profile HPLP) of Koreans in the Philippines. The sample consisted of 100 Koreans who have lived in Manila, Philippines. Data were collected for two months from Feb, 1 to March 30, 1998. Analysis of the data was done by use of percentage, t-test, ANOVA, Pearson's Correlation Coefficients, and Stepwise Multiple Regression. The results of this study were summarized as follows : 1. The range of total HPLP score was from 73 to 175 and the mean score of that was 117.23. In comparison of mean scores depending on each item of six dimensions, self-actualization dimension tended to show the hightest score(2.98) and responsibility for health dimension, the lowest score(1.83). 2. The HPLP score showed a positive correlation with age(r=.19), social support (r=.39), self-efficacy(r=.52) and perceived health status(r=.27), but a inverse correlation with perceived health care service utilization barriers(r=-.20). 3. By using stepwise multiple regression analysis it was determined that the main influencing factors on the HPLP score were self-efficacy(27.2%), social support(5.3%), age(5.3%) and perceived health status(2.9%). These variables made it possible to explain 40.7% of variance in HPLP score.

• Macromolecular Research
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• v.14 no.1
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• pp.52-58
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• 2006

A novel fabrication of the patterned surfaces in the polymer films was demonstrated by using the self-organizing character of the block copolymers of polystyrene-b-oligothiophenes and polystyrene-b-aromatic amide dendron. Hexagonally arranged open pores with a micrometer-size were spontaneously formed by casting the polymer solutions under a moist air flow. The amphiphilic character of the block copolymers played the crucial role as a surfactant to stabilize the inverse emulsion of water in the organic solvent, and subsequently the aggregated structure of the hydrophilic oligothiophene or aromatic amide dendron segments remained on the interiors of the micropores. The chemical composition on the top of the surface of the microporous films was characterized by energy-filtering transmission electron microscopy (EFTEM) or a time-of-flight secondary ion mass spectrometer (ToF-SIMS). The characterizations clearly indicated that the patterned surfaces in the self-organized block copolymer films with the hexagonally ordered microporous structures were fabricated in a single step.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.5 no.2
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• pp.353-361
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• 1998

The purpose of this study was to determine the predictors of health promoting behavior in postpartal $4{\sim}6$ week women. The sample consisted of 104 postpartal women who experienced a vaginal delivery at four obstetrical clinics located in Kwangju city. Data were collected for two months from June 1 to July 30, 1997. Analysis of the data was done by use of percentage, t-test, ANOVA, Pearson's Correlation Coeficients, and Stepwise Multiple Regression. The results of this study were summarized as follows : 1. The range of total HPLP score was from 93 to 182 and the mean score of that was 142.28. In comparison of mean scores defending on each item of six demensions, self-actualization demension tended to showed hightest score(3.33) and exercise & rest demension, the lowest score(2.47). 2. The HPLP score was not significantly different defending on the general characteristics. 3. The HPLP score showed a positive correlation with family-support(r=.51) and self-efficacy(r=.41), but a inverse correlation with perceived barriers(r=-.27). 4. By using stepwise multiple regression analysis it was determined that the main influencing factors on the HPLP score were family-support(26%) and self-efficacy (8%). These variables made it possible to explain 34% of variance in HPLP score.

• Journal of the Korean Society of Food Culture
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• v.34 no.2
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• pp.159-167
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• 2019

The purpose of this study is to provide basic information to improve understanding of contemporary kimchi culture in Korea. Many Koreans are now purchasing kimchi at markets, while the proportion of self-preparation is gradually decreasing. This commodification tendency of kimchi is considered to be associated with changes in consumer's behavior and attitude. In this study, a linear regression and a logistic regression model were used to identify relationships between kimchi consumption behavior and household characteristics. The results showed that the probability of kimjang activity was positively related with family size, possession of a kimchi refrigerator, self-preparation practice, and the intensity of sharing behavior. I also found that kimchi consumption volume per capita of 'purchasing' household was greater than that of 'self-preparing ' or 'sharing-dependent' households, and that the number of family members was inversely related with kimchi consumption volume per capita. The inverse relationship between family size and kimchi consumption volume per capita is considered to be contrary to the widespread thoughts in Korea, which have been developed while experiencing kimchi preparation and consumption in traditional extended families. I think that the relationship comes from differences in menu varieties, which appear to vary with family size. This issue will be investigated in subsequent studies.

• Advances in nano research
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• v.15 no.6
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• pp.495-511
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• 2023

In this research, the impact of micro-silica, nano-silica, and polypropylene fibers on the fracture energy of self-compacting concrete was thoroughly examined. Enhancing the fracture energy is very important to increase the crack propagation resistance. The study focused on evaluating the self-compacting properties of the concrete through various tests, including J-ring, V-funnel, slump flow, and T50 tests. Additionally, the mechanical properties of the concrete, such as compressive and tensile strengths, modulus of elasticity, and fracture parameters were investigated on hardened specimens after 28 days. The results demonstrated that the incorporation of micro-silica and nano-silica not only decreased the rheological aspects of self-compacting concrete but also significantly enhanced its mechanical properties, particularly the compressive strength. On the other hand, the inclusion of polypropylene fibers had a positive impact on fracture parameters, tensile strength, and flexural strength of the specimens. Utilizing the response surface method, the relationship between micro-silica, nano-silica, and fibers was established. The optimal combination for achieving the highest compressive strength was found to be 5% micro-silica, 0.75% nano-silica, and 0.1% fibers. Furthermore, for obtaining the best mixture with superior tensile strength, flexural strength, modulus of elasticity, and fracture energy, the ideal proportion was determined as 5% micro-silica, 0.75% nano-silica, and 0.15% fibers. Compared to the control mixture, the aforementioned parameters showed significant improvements of 26.3%, 30.3%, 34.3%, and 34.3%, respectively. In order to accurately model the tensile cracking of concrete, the authors used softening curves derived from an inverse algorithm proposed by them. This method allowed for a precise and detailed analysis of the concrete under tensile stress. This study explores the effects of micro-silica, nano-silica, and polypropylene fibers on self-compacting concrete and shows their influences on the fracture energy and various mechanical properties of the concrete. The results offer valuable insights for optimizing the concrete mix to achieve desired strength and performance characteristics.