• Journal of the Korean Society of Safety
• /
• v.12 no.2
• /
• pp.17-21
• /
• 1997

The fatigue crack propagation rate has so far been measured by the effective stress intensity factor range Δ K/sub eff/. But no research has been done to study how much the crack opening ratio influences the expectation of the fatigue crack propagation. Therefore, this paper evaluates of the crack opening ratio on the fatigue crack propagation life by using the method of parameter sensitivity study. Summarizing the result ; ( 1 ) When the crack opening ratio U' is high, the effect of U' gets larger than any other except for the material factor m. But when U' is low, the effect is also diminished. Therefore, the selection of the lowest value possible is desirable in the evaluation of life. (2) When the value of the material factor m is high, the effect of crack opening ratio U' is increased, at the same time the effect of the other parameters also increased wholly. The effect of material factor m itself on life is high, but in case the material factor m is high, that the effect of each parameter on life get higher is unique. In designing, better attention to the material selection should be drawn. (3) In case the stress ratio R gets smaller, the effect of crack opening ratio U' is unchangeable. But the effect of R itself remarkably decreases, and the effect of material factor m somewhat decreases.

• Membrane and Water Treatment
• /
• v.8 no.2
• /
• pp.137-147
• /
• 2017

A water treatment utility in South Korea operates a large system of pressurized hollow fiber membrane (PHFM) modules. The optimal selection of membrane module for the full scale plant was critical issue and carried out using Risk-based Life Cycle Cost (RbLCC) analysis based on the historical data of operation and maintenance. The RbLCC analysis was used in the process of decision-making for replacing aged modules. The initial purchasing cost and the value at risk during operation were considered together. The failure of modules occurs stochastically depending on the physical deterioration with usage over time. The life span of module was used as a factor for the failure of Poisson's probability model, which was used to obtain the probability of failure during the operation. The RbLCC was calculated by combining the initial cost and the value at risk without its warranty term. Additionally, the properties of membrane were considered to select the optimum product. Results showed that the module's life span in the system was ten years (120 month) with safety factor. The optimum product was selected from six candidates membrane for a full scale water treatment facility. This method could be used to make the optimum and rational decision for the operation of membrane water purification facility.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.12
• /
• pp.339-345
• /
• 2020

In the field of defense, one-shot devices such as missiles are stored for a long period of time after they are manufactured, so it is essential to predict their storage life. A study was conducted to find the shelf life of a Li-ion battery used in one-shot devices. To do this, a Li-ion battery that has been used in weapon systems for more than 5 years was secured. A non-functional test was performed on the battery to check for external changes or failures. After the non-functional test, a discharge test was performed to measure the performance after storing it. Through the test, the performance was checked, including the initial charging voltage, discharge time, and battery temperature, and the trend of the change was identified. An F-test, One-way ANOVA, and regression analysis were performed to verify the aging, and the shelf life of the battery was estimated by an approximation formula that was derived through a regression analysis. As a result of the ANOVA, the p-value was less than the reference value of 0.05, and the performance of the battery decreased by more than 15% after a certain period of time. This change is assumed to result from the change in physical properties of the lithium polymer cell.

• Journal of Advanced Technology Convergence
• /
• v.2 no.1
• /
• pp.41-47
• /
• 2023

This study was aimed at adult students majoring in the healthcare field to hear stories about life and leisure following work and study at the same time. To this end, four adult students were asked to describe their current life and leisure, positive and negative aspects of their leisure, and future life and leisure, along with interviews, focusing on the daily content they felt during the course of work and study. Afterwards, the technical contents were mutually reinforced with the interview contents and described in the form of self-recording. The decrease in leisure time in adult students' work and study balance inevitably reduces the quality of life. However, each of them was making an effort not to lose the balance between the purpose of their studies and their leisure time. A student's work-study balance is a choice and process for balancing life and leisure, and the joys and sorrows in the process are thought to be the value and hope of life.

• Journal of Life Science
• /
• v.20 no.12
• /
• pp.1896-1901
• /
• 2010

This study was conducted using quantitative real-time PCR using Lactobacilli as probiotics. Quantitative real-time PCR (RT PCR) was conducted via a method involving SYBR Green 1 and a probe. Plasmid DNA was cloned using the 16S-23S rRNA intergenic species region. Gene clones were diluted from $10^2$ to $10^{10}$. Standard curves were constructed via Ct values obtained from the results of Real-time PCR via the aforementioned SYBR Green 1 and probe method. Plasmid DNA was also cloned using the 16S-23S rRNA intergenic species region and the gene clones were diluted from $10^2$ to $10^{10}$ copy numbers via the probe method. Using RT PCR, a standard curve of plasmid DNA copy numbers was also determined. The slope value for the Y-axis intercept and $R^2$ value were measured as -3.346, 33.18, and 0.993, respectively, via the first method. For the second method, the slope value for the Y-axis intercept and $R^2$ were -3.321, 31.10 and 0.995, respectively. The PCR inhibitor could not express the detection curve at a copy number over $10^{10}$ via either method, owing to high DNA density. The DNA extract from probiotics was diluted without pre-culturing, and 16 products were amplified via both methods. The Ct value was 11.06~18.12 in the first method and 16.74~22.11 in the second method. Measured probiotics and log copy values were largely similar among the methods used. It was concluded that both methods are effective for analysis, but further research will be required to verify the optimal method.

• Journal of Families and Better Life
• /
• v.30 no.3
• /
• pp.105-118
• /
• 2012

This study aims to recognize cognition of credit card and shopping value in contemporary society, cognition of credit card and shopping value according to types of consumption orientation, and factors that influence cognition of credit card and shopping value, and ultimately provide a foundation for establishing proper shopping value. A total of 453 women and men residing in Seoul have been set as research object in order to achieve the purpose of the study. The data was analyzed by Cronbach' alpha, frequencies, percentile, mean, factor analysis, K-mean cluster analysis, t-test, ANOVA and Duncan's multiple range test, multiple linear regression. All analysis progress was done by spsswin12.0 statistics program. A summary of this research goes as follows: First, categorization of consumption orientation lead to two clusters of rational and symbolic & conspicuity consumption patterns and cognition of credit card was categorized into positive and negative cognition and shopping value was categorized into hedonic shopping value, utilitarian shopping value and time-save shopping value. Second, rational shoppers had high utilitarian shopping values and symbolic & conspicuity shoppers had high both hedonic shopping values and utilitarian shopping values. Third, the most influential factor in hedonic shopping value and utilitarian was consumption orientation. In conclusion, this research has showed that cognition of credit card and shopping value according to types of consumption orientation patterns varied, and that consumption orientation was an influential factor on cognition of credit card and shopping value.

• Food Science and Preservation
• /
• v.22 no.3
• /
• pp.408-420
• /
• 2015

This study investigated the effect of heat treatment conditions on the quality and antioxidant activities of Korean traditional actinidia (Actinidia arguta) cultivars puree. Heat treatment on actinidia puree was conducted at $70{\sim}90^{\circ}C$ for 1 min to 5 mins, while a control sample of the actinidia puree was prepared without heat treatment. In all the samples, except for the sample treated at $90^{\circ}C$ for 5 mins, pH and Brix degree was not dramatically changed. Pulp content decreased with increasing temperature and time. L and the a value of color increased with increasing temperature and time. However, the b value showed a reverse tendency with L and the a value. Viscosity and gumminess increased as heat temperature and time increased, though cohesiveness was not significantly changed depending on temperature and time. Coliform and yeast were not detected on all samples and the number of aerobic bacteria and mold decreased as temperature and time increased. Vitamin C and total phenolic content of the puree was not changed for 1, 3, and 5 mins at $70^{\circ}C$ and for 1 and 3 mins at $80^{\circ}C$, but significantly decreased with increasing time at $90^{\circ}C$. Furthermore, the antioxidant activities of the puree, such as DPPH radical scavenging activity, ABTS radical scavenging activity, and FRAP (ferric reducing antioxidant power) showed a similar tendency with total phenolic content.

• Korean Journal of Human Ecology
• /
• v.19 no.3
• /
• pp.537-553
• /
• 2010

Culture represents forms of life appeared in various dimensions. Advertisements which represent these forms of life show the most important social and cultural phenomenon. The necessity of research on the cultural characteristics of society has been raised because the effectiveness of advertisement could have been varied depending on the cultural value. Moreover, within a society, values reflected by advertisements tend to vary in different eras. Thus, this study aims to clarify the differences between cultural values from different eras through an analysis of cultural characteristics and symptoms with consideration of the time flow. This study also examines the meanings of cultural characteristics highlighted by the study. For the investigation, two Korean women's magazines were selected, from 1955 to 2008. Data were analyzed using chi-squared test which was conducted with Crosstab using the PASW statistics 17.0 Program. The results were as follows: there were changing aspects from traditional values to modern values by years. Additionally, each period was described using several keywords. The keywords were divided by decade: in the '50s keywords were 'lifestyle change', 'material value increase' and the 'challenge to traditional values', in the '60s keywords were 'American culture acceptance', 'material success', in the '70s keywords were 'the rise of nonmaterial value', 'rationalism' and 'egalitarianism', in the '80s 'individualism', 'Life style and culture group differentiation', 'conspicuous consumption', in the '90s 'globalization', 'emphasis on personality sensitivity', 'health-oriented', 'improve the quality of life', while in the '00s keywords were 'spread of digital life', 'rational consumption patterns', 'the 3rd distribution'. Through the research, important changes in the cultural characteristics of Korea were observed. Furthermore, we may be able to think of the most effective way of advertising by identification of the cultural characteristics of the society.

• Journal of the East Asian Society of Dietary Life
• /
• v.12 no.2
• /
• pp.141-153
• /
• 2002

Water activity of sausage added Umbelliferaeceae wild plants powder was decreased as storage time was prolonged and all samples were lower than those of the control. During the storage period, pH values of all samples were decreased. Cooking loss and storage loss was decreased as storage time was prolonged and showed differential from added sample. L, a, b values had a tendency to decrease, during the storage period. As the percentage of the wild plants powder in sausage, L, a values were decreased and b value was increased. Total plate counts of bacteria were increased as storage time was prolonged and wild plants powder added sausages were lower than control. Coriander 3.0% added sausage was the lowest total plate counts of bacteria, 1.3$\times$10$^{6}$ at four week'storage. As the percentage of wild plants powder in sausage was increased, total plate counts of bacteria decreased. Springiness, cohesiveness, chewiness, gumminess and hardness value of all sample were increased or decreased as storage time was longer. But they did not showed greatest various with storage time as well as additives. The sensory score of wild plants powder 0.5% added sausage were the highest, but wild plants powder 3.0% added sausage were the lowest. All the sensory score of coriander added sausage were high. The sensory score of all sample were decreased as storage time was prolonged. In wild plants powder 3.0% added sausage, the relationship between color, flavor, chewiness, wetness, taste and overall of sensory evaluation and all item of the textural characteristic showed huh correlation score. When storaging sausage for two weeks, the correlation of relationship between hardness of sensory evaluation and chewiness of textural characteristic was high.

• Proceedings of the KSME Conference
• /
• 2008.11a
• /
• pp.576-580
• /
• 2008

Rubber material properties and useful life evaluation are very important in design procedure to assure the safety and reliability of the rubber components. In this paper, the evaluation of characteristics and useful life prediction of rubber component for elevator cabin were experimentally investigated. The material test and accelerated heat-aging test were carried. Rubber material constants were obtained by curve fittings of simple tension, pure shear and bi-axial tension test data. Heat aging test results changes as the threshold are used for assessment of the useful life and time to threshold value were plotted against reciprocal of absolute temperature to give the Arrhenius plot. By using the rubber material and component test several useful life prediction equations for rubber component were proposed. Predicted useful life of rubber component for elevator cabin agreed fairly with the experimental lives.