• Journal of Applied Reliability
• /
• v.15 no.4
• /
• pp.270-275
• /
• 2015

Purpose : UHMWPE (Ultra-high-molecular-weight-polyethylene) is one of the most widely used material in knife protection clothes because of high strength, elasticity, and light weight. The purpose of this study is to develop the accelerated life test method and predict the lifetime for the knife protection fabric composed by UHMWPE. Methods : In this study, degradation characteristics of UHMWPE fibers and knife protection fabric for cut resistance were evaluated under the hydrolysis and photo-degradation conditions. It was found out that the degradation rate of retained tensile strength was more significant in the photo-degradation than hydrolysis. Therefore, the failure time was determined as the time that the retained tensile strength in photo-degradation is less than 50%. Considering an acceleration factor for irradiance and exposure time, the lifetime was predicted from the calculated failure time. Results : As a result of the accelerated life test, the $B_{10}$ lifetime of knife protection fabric composed by UHMWPE fibers is estimated as 2.8 years for a 90% statistical confidence level. Conclusion: Since the lifetime is predicted by the view-point of radiant exposure in this study, there is a possibility that the estimated lifetime may differ from the actual lifetime. However, it is considered as an useful methodology to estimate the long-term lifetime of knife protection fabrics.

• Journal of the Korean housing association
• /
• v.13 no.5
• /
• pp.51-58
• /
• 2002

The purpose of this study is to examine residents' perception and needs for storage according to the family life cycle. In order to achieve our goal, the questionnaire survey is used. We sample the questionnaire surveys of 250 apartment households in Seoul. The data collect by the questionnaire survey was analyzed by examining the frequency, percentage on the SPSS/PC+ Statistics package. The results of the study are obtained as follows: 1) In research on the actual storage condition, residents tend to feel constraint on storage of the season goods and the storage satisfaction on the service area is founded lowest. Therefore, it is needed more efficient space plan on the balcony storage and the interior storage for the season goods. 2) In research on the storage consciousness and attitude, residents tend to keep the goods of no use and prefer to arrange neatly rather than use conveniently. Therefore, it is needed more efficient space in the balcony for the storage of the goods of no use and the colsed furniture rather than the open furniture is suited for arrangement. 3) In research on the storage needs, needs for the built-in furniture in all family life cycle show highly and residents want to a space for the exclusive use of the storage. In a solution, we propose to equip with the interior storage and the exterior cooperative storage

• Korean Journal of Community Nutrition
• /
• v.18 no.3
• /
• pp.203-212
• /
• 2013

This study was conducted to develop a dietary life education textbook and teaching manual for creative activities of elementary school students in middle grade. First, we extracted dietary life related contents from textbooks for third and fourth grade and created systematization of contents involving educational objectives, goals, contents and activities. The development of textbook and teaching manual were based on systematization of contents. The textbook was composed of five major chapters, which were 'nutrition', 'cooking', 'environment and hygiene', 'food' and 'dietary culture'. Each major chapter having six to seven smaller chapters, adding up to a total of 34 smaller chapters. The textbook was in activity format so that can be readily and directly used in actual classes. The textbook had fun characters and various activities (particularly a lot of cooking activities) to deliver the main theme of each chapter. The teaching manual was composed of background, goal, teaching plan and teaching point. The smaller chapters had learning goal, teaching-learning resources, important points, teaching-learning process and reference material. In evaluation after operating the model school, the developed textbooks were suited for students' needs and cognitive level. This textbook can be utilized at creative activities consisting of ten to fifteen students.

• Journal of Korea Foundry Society
• /
• v.26 no.2
• /
• pp.85-91
• /
• 2006

Inclusions in Ti investment castings are generally known to have detrimental effects on the performance of the castings. However, actual inclusions are infrequent and hard to be located. As a result, it is extremely difficult to obtain sufficient amount of fatigue test specimens of titanium investment castings having inclusions in the gage section. Thus, in-depth research of the adverse influence of inclusions is also hindered. To address this problem, a new casting methodology of specimens containing hard alpha inclusions was developed in this study. To guarantee successful introduction of an inclusion and casting, a carefully designed mold with 8 legs and a special tool were employed. After solidification, castings were cut, and X-ray radiography determined that the inclusions were successfully incorporated into the castings. The castings were further prepared to obtain multiple test specimens and they were fatigue-tested consecutively. Fractography analysis confirmed that fatigue cracks initiated at the hard alpha inclusion. In a nonlinear regression model, the fatigue life can be modeled as an exponential function with a negative exponent of the cross-sectional area of an inclusion. The fatigue life of Ti specimens containing inclusions is inversely proportional to the cross-sectional area of an inclusion.

• Journal of Korean Society of Steel Construction
• /
• v.13 no.5
• /
• pp.467-476
• /
• 2001

The construction of highway bridges is almost complete in many countries including the United States. The government and highway agencies change the focus from constructing to maintaining To maintain the bridges effectively there is an urgent need to assess actual bridge loading carrying capacity and to predict their remaining life. The system reliability techniques have to be used for this purpose. Based on lifetime distribution (function) techniques this study illustrates how typical highway bridges can be modeled to predict their remaining life. The parameters of lifetime distribution are generated by Monte. The results can be used for optimization of planning interventions on existing bridges.

• Journal of Applied Reliability
• /
• v.16 no.3
• /
• pp.238-244
• /
• 2016

Purpose: Domestic electric railway Regenerative Energy Storage System seriously affects the maintenance cost of the total operating expenses of nearly 60% of the total LCC (Life Cycle Cost) due to high dependence on foreign Leading company. Therefore by developing the system, it is important to lower the maintenance cost in the domestic supply. This study about the capacitor Reliability test and the purpose of this study is development electric railway Regenerative Energy Storage System. Methods: In case of, having a close relation between the temperature and the reaction rate, Accelerated Model was known that according to Arrhenius' law of chemical activity. If you apply this formula in using allowable temperature range of the capacitor can induce the Arrhenius empirical formula used in much Manufacture Fields. We evaluate the capacitors Leading company through the Arrhenius model. in order to providing a base for the localization of Ultra Capacitor. Conclusion: In this paper, we conducted a reliability test. And it was performed by the accelerated life test and Cycle Test with temperature and C-rate. and then MTBF and B10 life are estimated by analyzing the accelerated life test result. This is thought to need detailed study applying complex stress than about whether it matches the actual behavior in electric railway.

• Journal of Korean Home Economics Education Association
• /
• v.6 no.2
• /
• pp.59-71
• /
• 1994

The purpose of this study was to analyze the problems of housing education in Home Economics and then to present some suggestion for improving the housing education in the middle school and to analyze the problems of housing edcation that was investigated on the recognition and application in real life of housing area subject to male/female students in the middle school. The respondents were 600 boys and girls of middle school. Statistical methods adopted for data analysis were Frequency, Chi-square, t-test, F-test. The major findings were follows: 1. Many students(67.2%) responded that housing of home economics was wholly helpful in the actual life. 2. Many students recognized the necessity for the housing education. They particularly recognized the need about the knowlidge of sanitation and facilities of housing. 3. The degree to which housing education applied in the real life was lower than that to which it was needed. 4. There was a tendency that the more students realized the usefulness of housing education, the more positively they applied it in the real life. 5. The contents that students preferred to be additionally included in housing education were improvement of residential environment, solutions to housing environmental deterioration and pollution, future housing, and housing for the elderly.

• Advances in Computational Design
• /
• v.3 no.2
• /
• pp.201-212
• /
• 2018

Decrease in availability of suitable subbase and base course materials for highway construction leads to a search for economic method of converting locally available troublesome soil to suitable one for highway construction. Present study insights on evaluation of benefits of stabilization of subgrade soils in term of extension in service life (TBR) and layer thickness reduction (LTR). Laboratory investigation consisting of Atterberg limit, Compaction, California Bearing Ratio, unconfined compressive strength and triaxial shear strength tests were carried out on two types of soil for varying percentages of stabilizers. Vertical compressive strains at the top of unstabilized and stabilized subgrade soils were found out by elastoplastic finite element analysis using commercial software ANSYS. The values of vertical compressive strains at the top of unstabilized and stabilized subgrade, were further used to estimate layer thickness reduction or extension in service life of the pavement due to stabilization. Finite element modeling of the flexible pavement layered structure provides modern technology and sophisticated characterization of materials that can be accommodated in the analysis and enhances the reliability for the prediction of pavement response for improved design methodology. If the pavement section is kept same for unstabilized and stabilized subgrade soils, pavement resting on lime, fly ash and fiber stabilized subgrade soil B will have service life 2.84, 1.84 and 1.67 times than that of unstabilized pavement respectively. The flexible pavement resting on stabilized subgrade is beneficial in reducing the construction material. Actual savings would depend on the option exercised by the designer for reducing the thickness of an individual layer.

• KIEAE Journal
• /
• v.7 no.5
• /
• pp.35-40
• /
• 2007

The purpose of this study is to execute evaluation experiment to know the evaluation property of lighting environment of residential space for senior people, considering visual characteristics along aging, and finally provide basic data for the lighting plan to ensure the visual amenity. Processes of this study are as follows;1) Analyzed the variation property of visual sensibility and visual ability of senior people along aging. 2) Selected 3 types of life behavior(rest, conversation and reading) after checking life behavior in residential space for senior people based on advanced study. 3) Made the Mock-up Model that Dimming is possible, actual furnace to model. 4) Executed sensitivity evaluation experiment about lighting environment. 5) Analyzed evaluation property of lighting environment of residential space for senior people. Results of this study are as follows, 1) With lens-filter, we got comfort and amenity in bulb-color lamp which has similar color temperature with red of lens filter. 2) Lighting environment tests during conversation : With lens filters, they felt comfort on bulb color in case of higher illuminance than 850lux and daylight color in 500lux. 3) Lighting environment tests at reading : With lens filter, bulb color got better score in brightness and appropriateness than daylight color.

• Journal of the Korean Wood Science and Technology
• /
• v.45 no.2
• /
• pp.182-194
• /
• 2017

The optimum alkali pretreatment parameters (reaction time, reaction temperature and potassium hydroxide concentration) for facilitate the conversion into fermentable sugar (glucose) from steam exploded (severity log Ro 2.45) barley husk were determined using Response Surface Methodology (RSM) based on a factorial Central Composite Design (CCD). The prediction of the response was carried out by a second-order polynomial model and regression analysis revealed that more than 88% of the variation can be explained by the models. The optimum conditions for maximum cellulose content were determined to be 201 min reaction time, $124^{\circ}C$ reaction temperature and 0.9% potassium hydroxide concentration. This data shows that the actual value obtained was similar to the predicted value calculated from the model. The pretreated barley husk using acid hydrolysis resulted in a glucose conversion of 94.6%. This research of steam explosion and alkali pretreatment was a promising method to improve cellulose-rich residue for lignocellulosic biomass.