• Journal of the Korean Society for Precision Engineering
• /
• v.17 no.7
• /
• pp.74-79
• /
• 2000

Integrating a 3D solid modeler with a general purpose FEM code, an automatic nonlinear analysis system of the 3D crack problems has been developed. A geometry model, i.e. a solid containing one or several 3D cracks is defined. Several distributions of local node density are chosen, and then automatically superposed on one another over the geometry model by using the fuzzy knowledge processing. Nodes are generated by the bucketing method, and ten-noded quadratic tetrahedral solid elements are generated by the Delaunay triangulation techniques. The complete finite element(FE) model generated, and a stress analysis is performed. In this system, burden to analysts fur introducing 3D cracks to the FE model as well as fur estimating their fracture mechanics parameters can be dramatically reduced. This paper describes the methodologies to realize such functions, and demonstrates the validity of the present system.

• Structural Engineering and Mechanics
• /
• v.22 no.3
• /
• pp.293-310
• /
• 2006

In seismic prone areas it is possible to meet very different objects (equipment components, on shelf artefacts, simple architectural elements) that can be modelled as a rigid body rocking on a rigid foundation. The interest in their behaviour can have different reasons: seismological, in order to estimate the ground motion intensity, or more strictly mechanical, in order to limit the response severity and to avoid overturning. The behaviour of many rigid bodies subjected to twenty wide ranging acceleration recordings is studied here. The response of the blocks is described using kinematic and energy parameters. A condition under which a so called scale effect is tangible is highlighted. The capacity of the signals to produce overturning is compared to different ground motion parameters, and a good correlation with the Peak Ground Velocity is unveiled.

• Journal of Korean Academy of Nursing
• /
• v.30 no.2
• /
• pp.319-330
• /
• 2000

This study is aimed at analyzing the trend of research on the use of exercise in nursing research, through suggesting directions for future research and implementation of the various exercise therapies. Research studies were taken from dissertations and theses selected from the Academic Society Journals of nursing science, Journals from universities, medical and nursing schools, research institutes in various universities, the Central Journal of Medicine, and the New Medical Journal. The research published between 1970 and 1997 in Korea were analyzed, 51 research were selected. The research are analyzed according to: published time, source of the research, research design, subjects, sample size, dependant variables, exercise therapy, and effect of exercise therapy. The results were as follows: 1. Research on exercise therapy increased rapidly in the 1990's. At this time, 88.2% of research was published. 2. Research areas included: 54.9% non- degree research, 27.5% Doctoral theses, and 17.6% Master's theses. 3. The experimental design included: 66.7% non- equivalent control group pre-test/ post-test design and 29.4% one group pre-test/post- test design. 4. Out of the Subjects: 52.9% were patients with various health problems, and 47.1% were healthy individuals. 5. Sample size included: 52.9% with above 31 subjects, 11.8% with 11~15 and 26~30. 6. Exercise therapy was analyzed by type, intensity, frequency, duration, and period. 1) The Types: Aerobic exercise at 60.8% was the most common, active exercise for muscle strengthening and building made up 21.6%. 2) Exercise with 40~65% intensity comprised 25.5%, 70~85% with 7.8%, and no description of the intensity was 66.7%. 3) Frequency of 3~5 per week was the most common at 78.4%. 4) Duration: 15~60 minutes was the most common length of time at 76.5%. 5) Periods: More than 5 weeks at 82.3% were the most common in their categories. 7. Dependant variables: Psychological response was measured as a dependant variable in 92.2%, Cardio-pulmonary function 88.2%, Body Composition was 86.3%, Physical Response was 60.8%, Lipid Metabolism was 58.8%, Physical Strength was 49.0%, Glucose Metabolism was 25.5%, Activities of Daily Living was 17.6% and others added to be 3.9%. 8. The effect of Exercise Therapy was categorized into 'positive', 'partially positive', and 'no effect' according to dependant variables: Having a positive effect - Glucose Metabolism (93.3%), Physical Response (85.0%), Activities of Daily Living (81.8%), Psychological Response (71.6%), Lipid Metabolism (67.6%), Cardio- pulmonary Function (63.6%), Physical Strength (68.1%), and Body Composition (56.4%). The following suggestions can be made on the above findings: 1. Research findings on Exercise Therapy as a Nursing Intervention need to be described by their elements of type, intensity, frequency, duration and period. 2. Toproperly study the positive effects of Exercise Therapy, there needs to be ⑴ appropriate research design, ⑵ selection criteria for the subjects ⑶ contents of exercise prescription to individuals or groups ⑷ measurement criterion for the dependent variables. 3. Meta-analysis on exercise therapy also needs to be done to analyze and integrate the various results.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.32 no.1A
• /
• pp.11-18
• /
• 2012

This paper deals with the numerical determination of the stress intensity factors of cracked aluminum plates under the mixed mode of $K_I$ and $K_{II}$ in glass-epoxy fiber reinforced composites. For the stress intensity factors, two different models are reviewed such as VCCT and two-step extension method. The p-convergent partial layerwise model is adopted to determine the fracture parameters in terms of energy release rates and stress intensity factors. The p-convergent approach is based on the concept of subparametric element. In assumed displacement field, strain-displacement relations and 3-D constitutive equations of a layer are obtained by combination of 2-D and 1-D higher-order shape functions. In the elements, Lobatto shape functions and Gauss-Lobatto technique are employed to interpolate displacement fields and to implement numerical quadrature. Using the models and techniques considered, effects of composite laminate configuration according to inclined angles and adhesive properties on the performance of bonded composite patch are investigated. In addition to these, the out-of-plane bending effect has been investigated across the thickness of patch repaired laminate plates due to the change of neutral axis. The present model provides accuracy and simplicity in terms of stress intensity factors, stress distribution, number of degrees of freedom, and energy release rates as compared with previous works in literatures.

• Journal of the Korean Society of Hazard Mitigation
• /
• v.7 no.2 s.25
• /
• pp.13-24
• /
• 2007

This study is to derive the rainfall intensity formula based on the representative probability distribution using multivariate analysis in Korea. The annual maximum rainfall data at 57 stations having more than 30years long records were used for 12 durations(10min, 1, 2, 3, 4, 5, 6, 8, 10, 12, 18, 24hr). 50 rainfall characteristics elements are analyzed from the collected data. The widely used 14 probability distributions are applied to the basic data in hydrologic frequency analysis. The homogeneous tests(principal component and cluster analysis) are applied to find the rainfall homogeneity. The results of this study are as followings; (1) The homogeneous test shows that there is no appropriate representative distribution for the whole duration in Korea. But hydrological homogeneous regions of point rainfall could be divided by 5 regions. (2) The GEV distribution for zones I, III, IV, V and the Gumbel distribution for zone II are determined as the representative probability distribution. (3) Comparative analysis of the results shows that the probable rainfalls of representative zones are different from those of existing researches. (4) Rainfall intensity formulas are determined on the basis of the linearization technique for the probable rainfall.

• Economic and Environmental Geology
• /
• v.44 no.2
• /
• pp.95-107
• /
• 2011

The Hwangsan volcanic rocks, hosting the Moisan epithermal Au-Ag deposit arc widely distributed throughout the Seongsan district, and associated with large hydrothermal alteration. They were analyzed as the Moisan and around voleanic rocks, and most of them show dacitic to rhyolitic compositions. Hydrothermal alteration related to epithermal system causes the host rocks to show the geochemical variation due to high mobility of alkali elements. These features can be applied for quantitative estimates of alteration intensity. Alteration intensity of volcanic rocks from the Moisan ranges from subtle to intense, based on AI vs. $Na_2O$ diagram. The pattern that ($CaO+Na_2O$) content decrease with increasing $K_2O$ content results from sericitic alteration, in which hydrothermal fluids continually provide $K^+$ into country rocks but remove $Ca^{2+}$ and $Na^{2+}$ of feldspars within country rocks. The decrease of ($CaO+Na_2O$) with decreasing $K_2O$ in some samples from the Moisan may be caused by advanced argillic alteration that all alkali elements are entirely removed from country rocks by acid hydrothermal fluids. Two alteration trends, based on Al and CCPI alteration indices suggest both sericitic alterations of feldsaprs to illite and sericite+chlorite$^{\circ}{\ae}$pyritc alteration of high Mg and Fe activities. Trace and Rare Earth Elements patterns show the similar geochemical variation related to hydrothermal alteration. Of LIL elements, strong depletion of $Sr^{2+}$, substituting for $Ca^{2+}$ in feldspars, appears to be resulted from removal of $Ca^{2+}$, during replacement of feldspars to alumino-silicates or phyllo silicates minerals by hydrothermal fluids. Relatively low total REEs contents (Moisan: 119-182 ppm; Seongsan: 111-209 ppm) and gently negative slopes suggest that significant mobility of LREEs appear to occur during hydrothermal alteration.

• FLOWER RESEARCH JOURNAL
• /
• v.18 no.1
• /
• pp.15-22
• /
• 2010

These investigations were conducted to standardize several chemical and physical environments affecting in vitro propagation of gametophytes of Climacium japonicum. Propagation of this moss species was established on basal medium containing Knop macro salts and Nitsch and Nitsch trace elements. Primary cultures were initiated from apical shoots of gametophytes. Gametophyte production was accessed using chopped gametophytes, apical shoots and basal shoots. Seven ty pes of culture media and four concentrations of total nitrogen and five strengths of sucrose were tested for in vitro gametophyte production. Light and temperature factors were also evaluated. Apical shoots were the greatest among three types explants used for gametophyte propagation. Medium containing Knop macro salts and Nitsch and Nitsch trace elements was more effective than other types of media. Higher sucrose concentrations showed a positive effect on the elongation and multiplication of gametophytes. Both nitrogen deficiency and excessiveness inhibited gametophyte growth. Light intensity variation showed highly significant changes in numbers, length and fresh weight of gametophytes. Optimum light intensity for gametophyte growth seemed to be around 3000-4000 lx. Both lower and higher temperature had a negative effect on gametophyte propagation and production. This study will provide large scale and high quality propagules, and effective moss propagation system.

• KSBB Journal
• /
• v.11 no.3
• /
• pp.303-310
• /
• 1996

The marine microalga Isochrysis galbana Parke was studied to optimize its growth conditions in flask culture. Important medium components studied include nitrogen source, buffer, trace elements and vitamins. Environmental conditions include pH, temperature, light intensity, mixing extent and working volume. The medium prepared from natural sea-waters gave a higher final cell density than the medium prepared from synthetic sea-water Nitrate was a better source than ammonium. In the range of 0.4∼2mM, the final cell density was proportional to the initial nitrate concentration and the cell yield was estimated to be 8.5g dry cell wt/g N. For phosphate, optimal growth was observed in 0.1∼1.0mM but a considerable variation in pH was resulted. The addition of Tris at 5mM or 7mM could stabilize the medium pH, but this significantly reduced both growth rate and final cell density, The effect of trace elements and vitamins was negligible. Optimal temperature and initial pH were $20^{\circ}C$ and 8. When the intensity of incident light was varied in the range of 400∼2100 lux, the growth rate increased from 10mL to 70mL, the final cell density decreased although the initial growth rate did not change. Optimal agitation speed was 100rpm when working volume was 30mL. With optimal conditions, the maximum specific growth rate obtained was 0.021hr-1 and the final cell density was 1.1g/L.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.20 no.4
• /
• pp.63-75
• /
• 2017

This study carried out for establishing the synthetic restoration plan to improve ecological quality of Mt. Mudeung National Park based on the results of conservation value assessment for yellow-throated marten habitats. Yellow-throated marten has significant implications as umbrella species for the wildlife habitats conservation, therefore, this species could be used to ecological restoration plan of the damaged forest ecosystem in Mt. Mudeung National Park. In this study, we diagnosed the quality of yellow-throated marten habitats in Mt. Mudeung National Park based on five natural and two artificial factors. In addition, we evaluated the integrity of each zone divided by trails quantitatively based on land use intensity. As a result, forest landscape quality in Mt. Mudeung National Park was influenced greatly by human activity and the degree was depended on the intensity of trails. Therefore, in this study, we suggested the closing of trails composed of the illegal and 36 legal trails. And then, we modeled the changes of habitats quality of Yellow-throated marten for each closing step. As a result the area of core habitats increased by two times and wildlife habitats quality improved in the whole area of the Mt. Mudeung National Park. As a result, the results of this study indicate that man-made linear landscape elements play a key role in the quality of habitats for predators, which require large habitats area like the Yellow-throated marten. Therefore, in order to establish an ecological restoration plan in the mountainous area, we recommend the concept of the linear landscape should be applied with the concept of area landscape.

• Korean Journal of Optics and Photonics
• /
• v.35 no.4
• /
• pp.157-163
• /
• 2024

We developed a 3-channel fiber laser with a common seed and a phase control system for laser beam combining through a diffractive optical element. Beam combining was performed by adjusting the angles of the beams incident on the diffractive optical elements, and the phase of each beam was controlled to maximize the intensity of the combined laser beam. The power of the 3-channel laser before passing through the diffractive optical elements is about 65 mW. The power of the combined beam varied between 2.9 mW and 48.3 mW depending on the phase change of each channel. Through phase control, the output of the combined beam can be maintained at 42 mW for more than 91.8% of the total time. It is expected that higher combining efficiency can be achieved by improving the transmittance of the diffractive optical elements and the performance of the phase control system.