• 대한기계학회논문집
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• 제18권3호
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• pp.548-554
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• 1994

The high temperature fatigue crack growth behavior of SUS 304 stainless steel at $550^{\circ}C$ and $650^{\circ}C$ was investigated under various kinds of stress ratio and frequency in sinusoidal waveform on the basis of the non-linear fracture mechanics. The result arranging crack growth rate by modified J-integral J' showed influence of stress ratio and frequency. All the data obtained under the test at $550^{\circ}C$ were plotted within data band of da/dN-${\triangle}J_f$ relationship for cycle-dependent crack growth. On the basis of static creep and cycle-dependent data band; both time- and cycle-dependent crack growth behavior was observed under loading conditions at $650^{\circ}C$, but cycle-dependent crack growth behavior predominantly appeared and time-dependent crack growth behaviour was little observed under loading conditions at $550^{\circ}C$. Fractographic examinations for fracture surface indicated that the fracture mode was generally transgranular. The stripes were found on fracture surface and each stripe was accompanied by a crack tip blunting and an abrupt increase in the load-point displacement. The $J'_{an}$ had a validity in case of $650^{\circ}C, but scarcely had it in case of $550^{\circ}C$.

• 한국지반환경공학회 논문집
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• 제11권4호
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• pp.19-24
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• 2010

사면의 거동에 관한 종래의 해석 기법은 사면거동을 시간과 변위의 2차원 크리프로 해석하는 것이었으나, 이러한 해석 기법은 강우에 의한 응력변화를 고려 않고 시간에 따른 변위만을 고려하여, 강우 시 사면의 거동 및 붕괴를 설명하지 못한다. 또한 강우에 의한 이력현상으로 인해 파괴면내의 전단에너지가 감소한다. 크리프 해석은 응력항을, 이력현상 해석은 시간항을 무시한 해석이므로, 두 가지 해석을 결합하여, 사면의 거동을 해석한다면, 응력변화, 변위 및 시간을 모두 고려한 실제 사면의 거동해석이 됨을 알 수 있다. 그러나 응력변화에 관한 항은, 강우로 인한 실제 사면의 침투 및 배수 시, 전단응력의 변화 및 전단강도의 변화를 동시에 유발하므로, 이 두 항을 동시에 고려할 수 있는 안전계수항으로 바꾸어야 한다. 본 논문은 강우의 지반침투 및 배수로 인하여 사면의 단위중량이 변하는 과정에 대한 크리프와 이력현상을 고려할 수 있는 결합해석으로 고찰하고 이에 따른 사면붕괴에 관한 전단응력과 전단강도의 변화 및 안전계수변화를 3차원으로 나타내고자 수행한 결과이다.

• 한국도로학회논문집
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• 제13권2호
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• pp.195-202
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• 2011

본 연구에서는 운전자의 일관성 있는 교통 정보 학습과정을 기반으로 한 일별 동적 모형을 개발하였다. 개발된 모형은 교통 정보 서비스의 효과 분석이 가능한 형태의 체계를 갖추었다. 즉, 교통 시스템에는 교통 정보 서비스 업체(ISP, Information Service Provider)가 존재하며, ISP의 가입자는 과거 실시간 교통 정보를 제공받으며, 이를 바탕으로 경로를 선택한다. 반면, 교통 정보 미가입자는 개인의 경험 또는 친구, 교통방송 등을 통해서만 교통 정보를 학습하게 된다. 운전자의 경로 선택은 Boundedly-rational 모형으로 표현되었으며, 주어진 동적 통행 수요와 경로 선택에 따른 도로 교통망의 성능을 평가하기 위해 미시 교통 시뮬레이션 모형 (파라믹스)이 사용되었다. 개발된 모형은 실제 도로망에 적용되었으며, 도출된 결과는 개발된 모형의 수렴성과 일관성있는 교통 정보 학습 모형의 효과를 입증하였다.

• 대한수의학회지
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• 제43권1호
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• pp.165-169
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• 2003

The aim of the present study was to analyse grunts of the sows and to extract parameters from the time and frequency signals in nursing behavior. Five crossbred $Landrace{\times}Yorkshire$ sows were used on day 5 or 6 postpartum. The grunts and the behaviors of the five sows were recorded with five digital camcorders. Three parameter groups [Group I: Formant vector alone, Group II: Formant vector+parameters from time signal, Group III: Formant vector+parameters from time signal-parameters eliminated by stepwise discriminant analysis backward (SDAB)] with parameter vectors extracted from single grunts in the maximum grunting rate period were used for individuality of the sows. The parameter groups were compared by a discriminant function analysis. The classification system adopted in the Group II represented the higher discriniation rate than those in other groups (Group I: 63.3%, Group II: 83.0%, Group III: 80.0%). This study demonstrated that formant, intensity, and pitch were available sound parameters for individuality of the sows during nursing behavior.

• 한국정보시스템학회지:정보시스템연구
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• 제26권4호
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• pp.1-15
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• 2017

Purpose Through the provision of real time performance information about who is contributing and who is not in Electronic Brainstorming, prior studies evidenced a significant performance gain. However, it has been observed that the quantity-based performance feedback alone does not have enough restrictiveness to guide the performance behavior throughout the idea generation session. We included the notion of goal setting into the process performance feedback mechanism in an effort to regulate performance behavior and to better understand why individuals in Electronic Brainstorming are not obtaining enough stimulation benefits in the group interaction process. Design/methodology/approach We had developed real-time visual process performance feedback and modified to include goal setting. This mechanism visually displays individuals' performances two-dimensionally (quality for each idea vertically and quantity of ideas horizontally along with their goals). As individuals' contributions accumulate, the mechanism reveals performance histories by connecting the sequence of ideas in a time-series format, telling stories of individuals' performances. Then, we compared the performance outcome from this study with the outcomes from two prior studies (i.e., Jung et al., 2010 and Jung, 2014). Findings The results showed that the inclusion of goal setting into the process performance feedback solved the issue in the previous study. That was the lower than expected magnitude of performance enhancement of process performance feedback when compared to that of quantity-based feedback. It appears that goals as a motivational technique provide standards for systematic self-evaluation, serving as a cue to regulate performance behavior by strengthening the linkage between effort and performance. Thus, goals seem to set up a self-fulfilling prophecy, preconditioning better performance. However, the outcome still showed that its performance magnitude is unsatisfactory because the outcome of this study turned out to be close to the outcome of just quantity-based performance feedback in Jung et al.'s (2010) study.

• 한국가금학회지
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• 제46권4호
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• pp.297-304
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• 2019

This study evaluated the effects of stocking density on performance and behavioral activities of 35-day-old broilers in relation to incandescent white bulb (IB) light and LED yellow and white light. A total of 1,650 day-old chicks were weighed and randomly allocated into six treatment groups in a 2 × 3 factorial arrangement based on stocking density (14 birds m^-2 and 22 birds m^-2) and color of lights (IB; monochromatic LED yellow and white light) with five replicates for each treatment. The results showed that final body weight, weight gain and feed conversion of broilers were improved at a stocking density of 14 birds m^-2 with exposure to LED lights. Similarly, broilers spent more time exhibiting inactive behavior (e.g. standing) and active behaviors (e.g. walking and walking plus pecking) under 14 birds m^-2 with exposure to lights as compared that of other treatment groups. Regarding a stocking density of 22 birds m^-2, broilers performance traits were negatively affected and also activities were less. The performance of broilers was not significantly altered for the main factor of different lights but broilers were less inactive (e.g less time spent sitting plus standing) and more time spent active behavior in walking under IB light than LED light. Thus, we concluded that a stocking density 14 birds m^-2 with exposure to LED light significantly improved broiler performance and behavioral activity and these conditions could therefore improve the overall welfare of farmed chickens.

• Journal of Community Nutrition
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• 제2권2호
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• pp.97-104
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• 2000

The purpose of this study was to investigate meal behavior and food preferences of children with different body types. This survey was conducted using a questionnaire for 274 boys and 257 girls in the 6th grade of elementary school in Anyang city. A questionnaire method was used. Food preferences of 14 food groups were tested with 5 likert scale points. Body types were divided with weight-length index(WLI) calculated by height and weight. The cut-off point for the underweight children was 90, and that of the overweight children was 100. The mean weight of the underweight children(26.2%) was 31.9$\pm$4.0kg, and that of the overweight children(26.9%) was 49.4$\pm$6.3kg. The average BMI of overweight children and underweight children was 21.0kg/$m^2$ and 15.5kg/$m^2$respectively. Perceived health status was different based on body types, and more of the overweight children answered they are healthy compared to the underweight children, Body types were not significantly different based on parent's education and occupation. Only 56.7% of the children ate breakfast at a regular time, 60% and 42.9% of the children had their lunch and dinner at regular time, respectively. Higher percentage of overweight children had irregular breakfast(20.1%) and skipped their breakfast and dinner compared to the other groups, however only dinner was statistically significant. The most frequently answered reasons for skipping meals were 'no time to eat'(50%) and 'bad side-dishes'(17.0%). Food preference was not different among the body type groups, however rice-cake was preferred in the underweight group, as well as milk and lettuce were preferred in overweight group. The preferences for milk and grain powdered drink(misitgaru) were same as or a carbonated soft drink. Focusing pubericant, it is necessary to have a regular breakfast. With regard to the importance of nutrition and health for children, the nutrition education for meal behavior and food preference to achieve a balanced diet should be considered.

• 대한지역사회영양학회지
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• 제13권2호
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• pp.199-206
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• 2008

The purpose of this study was to investigate snacking behavior in adolescents. We selected one middle school and one high school in 11 school districts in Seoul. The subjects were 1,813 students (904 boys and 909 girls) in 21 schools (11 middle schools and 10 high schools). Subjects reported their snacking behavior: snack frequency, snack type, snack time, with whom to eat snack, place to purchase snack. The subjects were classified into four groups by gender and schooling. The mean snack frequency was 2.8. Girls ate snacks more frequently than boys (p < 0.001). More than half of subjects ate 1 to 3 snacks a day. Only 9.3% of them did not eat any snack. Tangerine was highly ranked in snack type. Each subject groups had different snack time (p < 0.01) and type of snack (p < 0.001). Most snack was consumed alone (46.6%), however they mainly ate fruits and other foods with family. 46.9% of snacks were purchased outside. A typical snack time was 'before dinner' for most snacks except fruits. Unhealthy foods like soft drinks, cookies, chips, candies, chocolates, ice creams had relatively high proportion in snack consumption with friends. In conclusion, adolescents had different snacking behaviors by their age and gender. These results indicate necessities of multi-dimensional efforts at home, school, media and government level considering adolescents' age and gender for their healthy snacking behavior.

• 한국강구조학회 논문집
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• 제19권5호
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• pp.503-513
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• 2007

구조물의 지진응답은 구조물의 강성도에 영향을 미치는 접합부의 특성에 영향을 받는다. 본 연구에서는 합성반강접 접합부를 갖는 2차원 8층 비가새 철골구조물에 대하여 동적 비선형 해석 프로그램을 이용한 푸쉬오버 해석과 시간이력해석을 실시하여 구조물의 거동을 예측하였다. 접합부 비선형 모멘트-회전 특성, 합성보 및 철골기둥의 재료 비선형 특성을 고려하여 구조해석을 실시하였다. 합성반강접 접합부를 완전 강접합부로 이상화하면 푸쉬오버 해석에서 구조물의 초기강성도와 종국강도가 증가되었고 시간이력해석에서는 밑면전단력, 최대층간변위, 보 및 기둥에 발생되는 최대 휨모멘트가 접합부 강성 및 이력거동의 영향을 받았다. 최대지반가속도가 0.4g인 지진파에 대하여 합성반강접 구조물에서는 FEMA 273의 최대 층간변위에 대한 인명손상방지 기준을 만족하였으며 보와 기둥이 비탄성 거동을 경험하지 않은 반면 완전 강접합부로 이상화한 구조물에서는 보 및 기둥이 비탄성 거동을 경험하였다.

• 아동학회지
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• 제17권1호
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• pp.5-21
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• 1996

The purpose of the present study was to investigate how 4-to 5-year-olds approach a competitive/cooperative task to obtain a resource. Sex and age differences were examined for the behavior and resource utilization of this task. The subjects were 74 same-age, mixed sex groups of 4 children each in three kindergartens in a large city. Each group of 4 children were classmates. The children were videotaped in a play situation where one child could view a cartoon movie (i. e. acquiring a resource) with the assistance of two children (one to turn the film tape and one to push the light-button), and the fourth child was a bystander. Time at each position and physical and verbal behavior constitute the data which were analyzed by ANOVA and ${\chi}^2$. The results of the time analysis showed that children cooperated quickly and were able to view the cartoon(resource utilization) for a large part of the session. High resource utilizers compared with low resource utilizers, exhibited more self-assertive and helping behaviors. Boys achieved more viewing time while girls were bystanders for a greater amount of time. Boys showed more physical and verbal behaviors during the task. Four-year-olds achieved less viewing time than 5-year-olds, indicating 4-year-olds were less effective in eliciting the help of their peers.