• 대한기계학회논문집
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• 제19권5호
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• pp.1158-1167
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• 1995

In this study, the dynamic instabilities of a beam, subjected to periodic short impulsive loading, are investigated using simple 2-DoF beam model. The behaviors of beam model whose axial motions are constrained are studied for the case of elastic and elastic-plastic behavior. In the case of elastic behavior, the chaotic responses due to the periodic pulse are identified, and the characteristics of the behavior are analysed by investigating the fractal attractors in the Poincare map. The short-term and long-term responses of the beam are unpredictable because of the extreme sensitivities to parameters, a hallmark of chaotic response. In the case of elastic-plastic behavior, the responses are governed by the plastic strains which occur continuously and irregularly as time increases. Thus the characteristics of the response behavior change continuously due to the plastic strain increments, and are unpredictable as well as the elastic case.

• Biomolecules & Therapeutics
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• 제23권3호
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• pp.245-250
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• 2015

Silibinin, a natural flavonoid antioxidant isolated from extracts of the milk thistle herb, has recently been identified as having anti-hepatotoxic and anticancer properties. In this paper, we investigated the effects of silibinin on behavior and neuroplasticity in mice subjected to chronic unpredictable mild stress (CUMS). After 5 consecutive weeks of CUMS, the mice were treated with silibinin (100 mg/kg, 200 mg/kg and 400 mg/kg by oral gavage) for 3 consecutive weeks. The results showed that silibinin administration significantly alleviated the CUMS-induced depressive-like behavior, including the total number of squares crossed and the frequency of rearing in the open field test, the immobility time in the tail suspension test and the forced swimming test. Furthermore, silibinin treatment increased the levels of brain-derived neurotrophic factor (BDNF), serotonin (5-HT) and norepinephrine (NE) in the prefrontal cortex and hippocampus. Our study provides new insight into the protective effects of silibinin on the depressive status of CUMS mice, specifically by improving neuroplasticity and neurotransmission.

• 한국동물생명공학회지
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• 제34권1호
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• pp.40-49
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• 2019

Chronic and unpredictable stress can disrupt the female reproductive system by suppression for secretion of gonadotrophin-releasing hormone (GnRH) and gonadotrophin, resulted in ovarian malfunction and infertility. In the recent days, kisspeptin has been highly highlighted as a hypothalamic peptide which directly stimulates synthesis and release for GnRH. However, in spite of the key role of kisspeptin in the female reproductive system, little information is still available on the changes of its expression during ovarian cycle under stressed condition. Therefore, we induced chronic and unpredictable stress series to the female mice to analyze kisspeptin expression in the brain and ovary. Stressed mice exhibited changes of behavior and body weight gain during the stress assessment, which suggested that the present stress model in mice was successfully established. In the brain level, kisspeptin expression was attenuated than control. In the ovary level, the stressed mice displayed irregularly shrunk oocytes with broken zona pellucida throughout the follicle stages, pyknotic granulosa cells, decreased number of developing follicles and increased number of atretic follicles than the control. In case of kisspeptin expression in the whole ovary tissue, the expression level was decreased in the stressed mice. In detail, the less intensity of kisspeptin expression in the antral follicles phase was observed in the stressed mice than control mice, indicating that local function of kisspeptin during ovary cycle is highly associated with development of ovarian follicles. We expect that the present study has important implications for the fields of reproductive biology.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2002년도 추계 학술발표회 논문집
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• pp.285-291
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• 2002

This paper proposes the concept and the general framework of the risk-based seismic design. Because earthquakes and the behaviors of structures are very unpredictable, probabilistic seismic design methods have been proposed after deterministic design methods. Considering these changes, we can find that the important point of seismic design is not the structural behavior itself, but the consequence of structural behavior under possible earthquakes. Risk-based seismic design can tell these consequences under any earthquakes. In this paper, structural confidences are considered by using fragility curve, and risk is modeled by failure probability and consequence-property damage cost, casualty cost.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.79-82
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• 1997

The current from the feed motor of a machine tool contains substantial information about the machining state. There have been many researches that investigated the current as a measure for the cutting forces. However it has not been reported that indirect measurement of the cutting forces from the current of the feed motor at rest is possible. The cutting force normal to the machined surface influences the machined surface of the workpiece, which makes it necessary to estimate this force to control the roughness of the machined surface. But the unpredictable behavior of the current prevents applying the current to prediction of the cutting state. In this paper, empirical approach was conducted to resolve the problem. Also parametric adaptive and fuzzy logic control strategies are applied to the force regulation problem. As a result, the current is shown to be related to the accumulation of the infinitesimal rotation of the motor, and besides the unpredictable behavior of the current is shown to be caused by the relationship. Subsequently the relationship between the current and the cutting force is identified, and it is presented that control of machined surface using the current of the feed motor at rest is possible.

• Journal of Forest and Environmental Science
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• 제32권2호
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• pp.113-119
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• 2016

The long lived iteroparous conifers produce male and female gametophyte for hundreds of years once they reach the reproductive stage, however, the production of seed is not frequent. This phenomenon of infrequent seed production in conifers is yet to be understood. An attempt to study this change in cone production in Cedrus deodara of Western Himalayas -a species reported to be mainly monoecious and rarely dioecious has been made. The observations recorded on selected trees of flowering/fruiting stage for four years at four different locations have shown the species to be dioecious with higher percentage of female trees during good seed year but with no definite or predictable pattern of reproduction in the trees. A decline in production of female trees was witnessed at all but one location immediately year after reaching the maximum (good seed year). The phenomenon of seed production has been observed to be cyclic and site specific. A change in the sexual behavior of the trees from male to female or vice-versa, male or female turning monoecious or vegetative and vegetative coming to reproductive was unpredictable.

• 한국정밀공학회지
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• 제19권9호
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• pp.66-73
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• 2002

Since cross-feed directional cutting force which is normal to machined surface directly influences the machined surface of the workpiece and total force loaded in cutter, it is necessary to estimate this force to control the roughness of the machined surface and total force in cutter. However, there have been difficulties in using the current existing in a stationary motor for cutting state prediction because of some unpredictable behavior of the current. Empirical approach was conducted to resolve the problem. As a result, we showed that the current and its unpredictable behavior are related to the infinitesimal rotation of the motor. Subsequently, the relationship between the current and the cutting force was identified with the error less than 50%. And, the estimation results of the two machine tools with different characteristics were compared to each other to confirm the validity of the presented estimation method and the characteristics of current of the stationary feed motor.

• 동아시아경상학회지
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• 제5권2호
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• pp.38-47
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• 2017

In today's highly unpredictable marketing environment, where the consumer demands and behaviors are continuously and rapidly changing therefore various factors of consumer impulse buying behavior are proving to be challenging for the existing and new business organizations. Shopping has become a relaxing and rejoicing activity for the consumers making impulsive buying as a socially acceptable and common practice. So by taking into account all these aspects, the objective of this study was to understand the factors affecting impulse buying behavior of the consumer. Store atmosphere and fashion involvement were selected as independent variables while consumer impulse buying behavior was taken as dependent variable for this study. Likewise, impulse buying behavior of consumers with different monthly household income was also analyzed in this study. Primary data was collected through a questionnaire from 250 respondents of district Faisalabad, and then it was analyzed by using various statistical techniques. The results indicated a significant positive impact of store atmosphere and fashion involvement on consumer impulse buying behavior. The study also revealed that among consumer groups with different household incomes; at least one group differed from others in impulse buying behavior. These results were consistent with previous literature. These results could provide information to the marketers and retailers for planning and execution of various marketing techniques. Moreover, educators could expand on the findings by developing new studies examining consumer impulse buying behavior.

• Earthquakes and Structures
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• 제23권3호
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• pp.315-328
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• 2022

Structures designed for wind have an opposite design approach to those designed for earthquakes. These structures are usually reliable if they are constructed in an area where there is almost no or less severe earthquake. However, as seismic activity is unpredictable and it can occur anytime and anywhere, the seismic safety of structures designed for wind must be assessed. Moreover, the design approaches of wind and earthquake systems are opposite where wind design considers higher stiffness but earthquake designs demand a more flexible structure. For this reason, a novel Machine learning framework is proposed that is used to assess and classify the seismic safety of the structures designed for wind load. Moreover, suitable criteria is defined for the design of wind resistance structures considering seismic behavior. Furthermore, the structural behavior as a result of dynamic interaction between superstructure and substructure during seismic events is also studied. The proposed framework achieved an accuracy of more than 90% for classification and prediction as well, when applied to new structures and unknown ground motions.

• 대한토목학회논문집
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• 제33권4호
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• pp.1591-1601
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• 2013

본 연구에서는 초보운전자의 교통사고 위험성을 줄이고 초보운전자 교육프로그램 개발의 기초자료를 제공하기 위하여 초보운전자에 대한 심리적 특성 및 운전행동에 관한 분석을 실시하였다. 이때 초보운전자의 심리적 부분은 위험인식정도 및 교통상황 이해도를 확인하는 설문조사를 실시하였으며 주 내용은 위험예측 및 예측불허행동에 관한 특성별 범주로 분류하여 파악하였다. 그리고 차량시뮬레이터를 활용하여 초보 및 일반운전자와의 운전행동 특성을 비교 분석하고 통계결과를 토대로 초보운전자의 실제 운전행동에 있어서의 안전진단과 교통안전교육 기초연구의 방향성을 제시 하였다. 본 연구 분석결과, 운전자의 위험예측, 과속, 위반, 정보제공생략, 갑작스러운 변화, 사고건수 모든 부분에서 초보운전자가 일반운전자에 비해 높은 평균값이 나타났다. 또한 초보운전자가 일반운전자에 비해 통계적으로 유의한 위험수준을 보여주었는데 확인된 대상은 위험예측능력, 위반, 갑작스러운 변화, 교통사고건수이었고 그 이외의 과속 수준과 정보제공생략 수준은 초보운전자와 일반운전자 모두 유사한 결과를 보여주었다. 그리고 차량시뮬레이터 실험 결과는 초보운전자가 일반운전자들에 비해 전반적으로 운전 수행능력이 저조한 것으로 나타났다. 특히 충돌횟수에서의 확연한 차이를 보여주었는데 이는 초보운전자들이 일반운전자들에 비해 복잡한 도로교통 상황에서 운전경험과 학습능력이 부족하기 때문인 것으로 판단된다. 한편 초보운전자들은 일반운전자들에 비해 속도조절 능력, 위험예측 능력, 도로교통상황에 대한 인식 및 대처능력 등 전반적인 운전기술의 부족으로 인해 주행안정성이 낮은 것으로 분석되었다. 이러한 결과는 초보운전자들이 일반운전자에 비해 안전운전교육 학습기회의 결여와 운전경험 미숙 등에 따른 것으로 판단되며 운전 상황에 대한 위험예측능력이 낮은 것으로 해석할 수 있다. 결론적으로 이러한 분석결과는 실제 운전상황에서 초보운전자 자신뿐만 아니라 타인에게도 위험 요소로서 작용할 가능성이 높으므로 적절한 안전대책이 필요한 것으로 판단된다.