• Journal of Advanced Marine Engineering and Technology
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• 제22권4호
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• pp.490-497
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• 1998

An elast-biscoplastic finite element analysis is performed to investigate detailed growth behavior of creep cracks and the numerical results are compared with experimental results. The results of mesh translation method are compared with those of node release method. Load line displancement curve obtained from the crack growth analysis by mesh translation shows the improved results than that obtained from the crack growth by node release method when the secondary creep rate is only used as creep material property. The results of accounting for primary creep rate and instantaneous plasticity shows a good agreement with the experimental result.

• 한국세라믹학회지
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• 제32권5호
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• pp.587-593
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• 1995

Abnomal grain growth behavior of BaTiO3 ceramics was investigated with addition of seed grains. It was foudn that the nucleation rate of abnormal grain was constant and growth of abnormal grain was linearly increased with sitnering time, regardless of amount of seed grains. These facts were also confirmed by fitting of the volume fraction of abnormal grain vs. sintering time using Avrami type equation (n=4). It was suggested that seed grains did not change the nucleation rate or growth mechanism of abnormal grain but increase the number of abnormal grains at initial stage of sintering and then it led to fine microstructure of BaTiO3 ceramics.

• 대한기계학회논문집A
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• 제24권8호
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• pp.2074-2082
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• 2000

In this study, to investigate and to predict the crack growth behavior under variable amplitude loading, crack growth tests are conducted on 7075-T6 aluminum alloy. The loading wave forms are generated by normal random number generator. All wave forms have same average and RMS(root mean square) value, but different standard deviation, which is to vary the maximum load in each wave. The modified Forman's equation is used as crack growth equation. Using the retardation coefficient D defined in previous study, the load interaction effect is considered. The variability in crack growth process is described by the random variable Z which was obtained from crack growth tests under constant amplitude loading in previous work. From these, a statistical model is developed. The curves predicted by the proposed model well describe the crack growth behavior under variable amplitude loading and agree with experimental data. In addition, this model well predicts the variability in crack growth process under variable amplitude loading.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2003년도 춘계학술발표대회 논문집
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• pp.113-116
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• 2003

The investigation of delamination growth behavior in hybrid composite material such as FRMLs should be considered delamination growth rate, dA_D/da$ using the delamination shape factor, $f_S$ instead of traditional fracture mechanics parameters. The main objective of this study is to evaluate the relationship between delamination element (i. e. delamination width, b, delamination contour, c, delamination shape factor, $f_S$ and delamination growth rate, dA_D/da$) and delamination growth in FRMLs under cyclic bending moment. The delamination shape formed along the fatigue crack between aluminum layer and glass fiber/epoxy layer are measured by scanning method. The details of study are as follow : ⅰ) Relationship between crack length, a and delamination width, b. ⅱ) Variation of delamination growth rate, dA_D/da$ was attendant on delamination shape factors, $f_{S1}$, $f_{S2}$, $f_{S3}$. The test result indicated the delamination growth behavior depends in delamination element such as delamination width, b, delamination shape factors, $f_{S1}$, $f_{S2}$, $f_{S3}$.

• 한국컴퓨터정보학회논문지
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• 제21권8호
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• pp.95-103
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• 2016

Food habit forming the basis for a lifetime of food and nutrient intake is established in early childhood and has an effect to the child's growth, sociality, and obesity. A variety of nutrition screening tools exists for assessing the health and nutrition status of children such as the Growth Curve, for determining if growth is appropriate. Body mass index(BMI) as a more reliable index of overweight to prevent childhood obesity, and Nutrition Quotient(NQ) and eating behaviors questionnaire for young children and parents to estimate their nutrient intake adequate or not. Such tools are mainly used by health practitioners, such as doctor and dietitian to provide nutrition intervention services to children at risk, especially and are not easy to use for general parents, who need assessment at any time and at any place. We propose Growth Assistance System for infants and children, which is possible to assess their physical condition, nutritional status, and eating behavior integrated. To be convenient and portable, it is implemented over the smartphone as an application. The system offers the growth charts, the BMI curves, NQ and eating behavior questionnaire to take a monitoring and the functionalities operate well. We hereby expect this system support the normal growth and development of infants and young children. And also support for the health practitioner (dietitians and nutritionists) to take a role in providing nutrition counseling and education to children needing nutrition services.

• 한국해양공학회지
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• 제11권3호
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• pp.76-88
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• 1997

Constant .DELTA.K fatigue crack growth rate experiments were performed by applying an intermediate single and multiple overload for structural steel, SM45C. The purpose of the present study is to investigate the influence of multiple overloads at various stress intensity factor ranges and the effect of statistical variability of crack retardation behavior. The normalized delayed load cycle, delayed crack length and the minimum crack growth rate are increased with increasing baseline stress intensity factor range when the overload ratio and the number of overload application were constant. The crack retardation under low baseline stress intensity factor range increases by increasing the number of overload application, but the minimum crack growth rate decreases by increasing the number of overload application. A strong linear correlation exists between the minimum crack growth rate and the number of overload applications. And, it was observed that the variability in the crack growth retardation behavior are presented, the probability distribution functions of delayed load cycle, delayed crack length and crack growth life are 2-parameter Weibull. The coefficient of variation of delayed load cycle and delayed crack length for the number of 10 overload applications data are 14.8 and 9.2%, respectively.

• 한국강구조학회 논문집
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• 제11권1호통권38호
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• pp.33-42
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• 1999

궤도용 차량의 안전성 확보를 위한 연구의 일환으로서 레일강의 균열 발생 조건과 모재와 용접부에 대한 정적파괴거동 및 단일모드 하중하의 피로균열진전거동을 검토하였다. 레일에서 횡방향 균열의 원점은 표면하층균열이며 이는 최대전단응력에 의해 발생하였다. 또한 표면하층균열의 크기가 증가함에 따라 균열의 진전은 전단모드에서 혼합모드로 천이될 가능성이 증가하였다. 용접부의 평면변형률 파괴인성은 조직의 조대화와 경도의 상승으로 인하여 모재에 비하여 약 10% 저하하였다. 용접부의 제 2단계 영역의 피로 균열진전속도는 낮은 ${\Delta}K$ 영역에서 모재에 비하여 저하하였으나 높은 ${\Delta}K$영역에서는 이의 차이가 소멸되었으며 이러한 경향은 R=0.1의 낮은 응력비에서 현저하였다. 이는 용접부의 미시조직이 모재에 비하여 성장하였기 때문이라고 판단된다.

• 품질경영학회지
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• 제25권1호
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• pp.44-55
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• 1997

In order to determine procedures for a, pp.opriate model selection of technological growth curves, numerous time series that were representative of growth behavior were collected according to data characteristics. Three different growth curve models were fitted onto data sets in an attempt to determine which growth curve models achieved the best forecasts for types of growth data. The analysis of the results gives rise to an a, pp.oach for selecting a, pp.opriate growth curve models for a given set of data, prior to fitting the models, based on the characteristics of the goodness of fit test.

• 대한간호
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• 제29권5호
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• pp.54-68
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• 1991

This study was conducted to provide the basic information for nursing intervention in infant teach. ing and feeding situation. The subjects were 30 pairs of mother and her infant(9 month) who were normally delivered at 3 university hospital in Seoul area. The data collection was conducted by observation using videotaperecord from September 27, 1989 to Feburary 26, 1990 in their home. The measulsement tools used by this researcher were Nursing child Assessment Teaching scale (NCATS) and Nursing child Assessment Feeding Scale(NCAFS) which was developed by Barnard. The higher sum of "yes" score means the higher mother-infant interaction level. Mother-Infant interaction behaviors in both sitution were based on 6 subcategories; sensitivity to cue, response to distress, social-emotional growth fostering, cognitive growth 'fostering, clarity of + cues, and responsiveness to parent. The data collected through above method were analyzed by mean and t-test and the results were as follows. 1. The sum of maternal behavior score was 40.2 out of 50.0 in teaching situation and 37.9 out of 50.0 in feeding situation. Out of the 4 subcategories on maternal behavior in both situation, the highest subcategory was shown by response to infant's distress and the lowest subcategory by cegnitive growth fostering. 2. The sum of infant behavior score was 14.7 out of 23 in teaching situation and 17.9 out of 26 in feeding situation. Out of the 2 categories on infant behavior in both situation, the highest sub categroy was shown by the clarity of infant's cue in both situation. 3. There was a statistical significance between father's educational level and mother-infant interaction in teaching situation; college group was higher than high school group, particulary in category of sensitivity to infant's cue and congnitive growth fostering. 4. There was a statistical significance in teaching situation between mother's educational level and mother-infant interaction;college group was higher than high school group, particulary sensitivity to infant cue, social-emotional growth fostering and cognitive fostering. 5. There was no statistical difference in between parent educational level and mother.infant interaction in feeding situation.situation.

• 대한기계학회논문집A
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• 제28권1호
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• pp.55-62
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• 2004

Although the previous researches evaluated the fatigue behavior of glass fiber/epoxy laminates using the traditional fracture mechanism, their researches were not sufficient to do it: the damage zone of glass fiber/epoxy laminates was occurred at the delamination zone instead of the crack-metallic damages. Thus, previous researches were not applicable to the fatigue behavior of glass fiber/epoxy laminates. The major purpose of this study was to evaluate delamination behavior using the relationship between crack length and delamination width in hybrid composite material such as Al/GFRP laminate. The details of investigation were as follows : 1) Relationship between crack length and delamination width, 2) Relationship between delamination aspect ratio and delamination area rate, 3) Variation of delamination growth rate is attendant on delamination shape factors. The test results indicated that the delamination growth rate depends on delamination width delamination aspect ratio and delamination shape factors.