• Journal of Korea Ship Safrty Technology Authority
• /
• v.12
• /
• pp.36-43
• /
• 2003

Fatigue life estimation by the theoretical stress concentration factors are, in general, considerably different from test results. And in calculating stress concentration factor, it is very difficult to consider actual geometry and material property which are the notch shapes, imperfections or defects of materials such as porosities inclusions and casting defects, etc. Therefore, the paper deals with the experimental method to find out the more exact stress concentration factors by measuring the strain distributions on each specimen by 3D-ESPI(Electronic Speckle Pattern Interferometry) System. Then the fatigue lives are compared between theoretical calculations using stress concentration factors determined by 3D-ESPI system and fatigue test results

• Journal of the Korea Safety Management & Science
• /
• v.11 no.3
• /
• pp.27-32
• /
• 2009

Human physical activity to lead daily life is performed by a variety of muscular activity strategies. These strategies can be influenced by characteristics, difficulty and muscle fatigue of work. Therefore this study examines muscular strengths (grip and back strength) of workers engaged in electronics industry in Korea, compares them to mean value of muscular strength by sex and age, accumulates related data and then aims to develop improvement methods of working environment and prevention/management program.

• Journal of Families and Better Life
• /
• v.17 no.3
• /
• pp.83-92
• /
• 1999

Many Policies were made to increase women's employment since the latter half of the 1980s in Korean. But work-family conflict of married women can not be solved without reducing the household work load, because all of Korean wives have the responsibilities of household work. So this study aims to establish the supporting system of household work in the women's policies. For this purpose this study examine the actual conditions for supporting the household work. And supporting system and strategies for policy making related to household work and suggested. Supporting system includes arrangement in household raise in social consciousness improvement of market circumstance establishment of relating acts and public facilities.

• Korean Institute of Interior Design Journal
• /
• no.29
• /
• pp.249-256
• /
• 2001

The Purpose of this study is to Provide a basic data for Projects of residential bathroom remodeling according to contemporary life style. The subjects of this investigation are collected through questionnaire from adult resident who live in Seoul Korea. Four hundred ten cases are collected, and frequencies, percentile, crosstabs, and factor analysis and varianc analysis using Spss-win program analyze adequate cases in necessary condition. In this study, residents demographic informations, bathroom preferences, types, sizes, cost construction period, instruments needs, behaviors and facilities seperation are included. By statistics treatment, the significance of the data is analyzed.

• The Korean Journal of Nuclear Medicine
• /
• v.9 no.1
• /
• pp.59-71
• /
• 1975

53 patients with hyperthyroidism have been analyzed with special reference to therapeutic response to radioactive iodine ($^{131}I$) treatment. Mean effective half-life, 24 hour uptake rate and radiation dose of $^{131}I$ in hyperthyroid patients included in this study were respectively. 1. Mean effective half-life of $^{131}I\;was\;4.7{\pm}1.5$ days in the tracer dose and $5.0{\pm}1.5$ days in the therapeutic dose. 2. Mean 24 hour uptake rate of $^{131}I\;was\;72.7{\pm}11.1%$ in the tracer dose and $73.4{\pm}12.3%$ in the theapeutic dose. 3. Mean radiation dose of $^{131}I\;was\;5,319{\pm}2,648$ RAD as predicted and $5,692{\pm}2,843$ RAD as actual. A single dose of radioactive iodine treatment was satisfactory in 34 patients (radioiodine sensitive) and multiple doses of radioactive iodine treatments were required in 19 patients (radioiodine resistant). A radioiodine resistant group of patients with hyperthyroidism was distinctively characteristic in the following aspects. 1. Mean thyroid weight calculated in the resistant group ($63.9{\pm}14.0gm$) was significantly (p<0.01) greater than that of the sensitive group ($46.6{\pm}13.3gm$). 2. Mean 24 hour uptake rate of the tracer dose in the resistant group ($67.3{\pm}10.7%$) was significantly (p<0.01) lower than that of the sensitive group ($75.7{\pm}10.5%$). 3. Mean 24 hour uptake rate of the therapeutic dose in the resistant group ($68.5{\pm}13.7%$) was significantly (p<0.05) lower than that of the sensitive group ($76.1{\pm}10.9%$). 4. Mean predicted radiation dose, of $^{131}I$ in the resistant group ($3,684{\pm}1,745$ RAD) was significantly (p<0.01) lower than that of the sensitive group ($6,232{\pm}2,683$ RAD). 5. Mean actual radiation dose of $^{131}I$ in the resistant group ($4,100{\pm}1,691$ RAD) was significantly (p<0.01) lower than that of the sensitive group ($6,582{\pm}3,024$ RAD). 6. No significant difference was detected in terms of effective half-life of $^{131}I$ among the groups (p>0.05). 7. The average mean % difference of effective half-life, uptake rate and radiation dose measured following the tracer and therapeutic dose of $^{131}I$ were not statistically significant (p>0.05). Therefore effective half-life, uptake rate and radiation dose of the therapeutic dose of $^{131}I$ were readily predictable following the tracer dose of $^{131}I$. 8. It is concluded that the possibility of resistance to radioactive iodine treatment may be anticipated in patients with thyroid gland large in size and compromised $^{131}I$ uptake rate.

• Journal of Venture Innovation
• /
• v.2 no.1
• /
• pp.57-79
• /
• 2019

We have been experiencing an lengthened life expectancy due to rapid industrialization, economic and medical development. In particular, the elderly population was only 5.1% of the total population in 1900s when the senior centers were established, but 30 years later, the elderly population aged 65 or older reached 6.54 million in 2015 and became 14% in 2017. There is a very meaningful correlation between service quality of the senior welfare center and the life satisfaction of the elderly, where the elderly spend their leisure time on a daily basis. Accordingly, this study tried to identify the desirable conditions that the elderly think and the difference from the desired status and the actual status to identify what information and services should be provided by senior welfare centers. Gwanak Senior Welfare Center has provided senior welfare service for local seniors for 30 years since its establishment and contributed to silver welfare policy establishment based on the accumulated experiences. In the coming era of GDP 30,000 dollars, National Pension era and average life span 100 years, the new creative silver welfare programs should be introduced such as qualitative programs rather than quantitative, programs for caring minorities, complimentary or actual expense programs, creative programs rather than passive ones, and diversity of the subjects. This study would like to present the future direction for the next 30 years.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.38 no.11
• /
• pp.1221-1229
• /
• 2014

This paper proposes an approach for predicting the fatigue life of a propeller shaft of a forklift truck by an accelerated life test method. The accelerated life test method adopted in this study is the calibrated accelerated life test, which is highly effective in the prediction of the lifetime and enables significant reduction of the test time as well as a quantification of reliability in the case of small sample sizes. First, the fatigue test was performed under two high stress levels, and then, it was performed by setting low stress levels in consideration of the available test time and extrapolation. Major reliability parameters such as the lifetime, accelerated power index, and shape parameter were obtained experimentally, and the experimentally predicted lifetime of the propeller shaft was verified through comparison with results of an analysis of load spectrum data under actual operating conditions.

• Journal of the Korean Wood Science and Technology
• /
• v.44 no.6
• /
• pp.821-827
• /
• 2016

This study evaluates the economic feasibility of industrializing fluidized bed dryer for wood particles. The theoretically required heat energy and energy efficiency were evaluated using a pilot scale fluidized bed dryer. When Mongolian Oak wood particles with 50% initial moisture content were dried in the fluidized bed dryer with air of $70^{\circ}C$ air circulating at 1.1-1.3 m/s for 30 minutes, the total theoretically required heat energy was 2,177 kJ. Of this, 1,763 kJ (approximately 81.0%) was used to heat the air flowing in from outside the dryer and 386 kJ (approximately 17.7%) was used to heat and remove water from the wood particles. Actual energy consumed was 7,560 kJ, giving energy efficiency of 28.8%. Thus, to industrialize a drying method such as fluidized bed drying, where the dryer volume is significantly larger than the volume of wood particles, it is necessary to minimize energy loss and maximize energy efficiency by designing the dryer size considering the amount of wood particles and choosing a suitable air circulation rate.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.38 no.10
• /
• pp.1163-1169
• /
• 2014

In this study, a fatigue assessment method for vehicle suspension systems having welded geometries was established under a bending loading condition. For the fatigue life estimation of the actual product's welded joints made of different steels, bending fatigue tests were performed on welded specimens with a simplified shape for obtaining the moment-fatigue-life plot. Further, geometry modeling of the simplified welded specimens was conducted. Results of finite element analysis were used to obtain the stress-fatigue-life plot. The analysis results were also used to calculate the stress concentration factors for notch-factor-based fatigue life estimation. The test results were compared with results of the general notch-factor-based fatigue life estimation for improving fatigue assessment. As a result, it was concluded that both the welded fatigue tests and the notch-factor-based fatigue life estimation are necessary for accurate fatigue assessment.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.24 no.3 s.174
• /
• pp.701-709
• /
• 2000

As the welding spot forms a singular geometry of an external crack type, fatigue failure of spot-welded specimens can be evaluated by means of a fracture parameter. Recasting the load vs. fatigue life relationships experimentally obtained, we predicted the fatigue life of spot-weld specimens with a single parameter denoted the equivalent stress intensity factor. This crack driving parameter is demonstrated to successfully describe the effects of specimen geometry and loading type in a comprehensive manner. The suggested fatigue life formula for a single spot weld can play a key role in the design and assessment of spot-welded panel structures, in that the fatigue strength of multi-spots is eventually determined by the fatigue strength of each single spot. We therefore attempt to evaluate the effectiveness and validity of $K_e$ in predicting the fatigue life of auto seat belt anchor panel. We first establish finite element models reflecting the actual mechanical behavior of 3 types of seat belt anchor specimens. Using finite element models elaborately established, we then obtain the effective crack driving parameter $K_e$ composed of its ductility -dependent modal components. It is confirmed that the $K_e$ concept successfully predicts the fatigue life of multi-spot welded panel structures represented by auto seat belt anchors here.