• Tribology and Lubricants
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• 제13권2호
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• pp.68-73
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• 1997

The adhesion between wheel and rail plays an important role in the braking performance of trains. Though there have been numerous studies on the characteristics of adhesion phenomenon, a general understanding from the physical point of view is still lacking. In this work, the adhesion mechanism between wheel and rail was investigated by studying the mechanisms of pure rolling and sliding experiments. Tests were performed under various conditions to determine the physical phenomenon responsible for adhesion between wheel and rail. The results of this study is expected to aid in improving the braking performance of trains.

• 한국자기학회지
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• 제5권5호
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• pp.351-353
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• 1995

The physical origins of anomalous volume effect (Invar effect) and elastic effect (Elinvar effect) are critically examined. We found that, unlike the volume effect, the shear elastic properties are not much influenced by the ferromagnetic transition. This finding shows that the two anomalies originate from different physical origins, thus contradicting the conventional wisdom. We discuss the consequences of this finding in the light of recent experiments.

• The Journal of Korean Physical Therapy
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• 제22권5호
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• pp.33-38
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• 2010

Purpose: This study examined the activation of the rectus abdominis (RA), external abdominal oblique (EO), transversus abdominis, internal abdominal oblique (TrA/IO), and Multifidus (MF) muscles while stabilization exercise was performed in a four-point kneeling position. Methods: Experiments were conducted on 21 healthy male adults (mean age=25.29 years) who voluntarily agreed to participate in the study. Each subject was instructed regarding maximal voluntary contractions (MVC) and stabilization exercise in four-point kneeling. While MVC and stabilization exercise of individual muscles were being performed, activation of the muscles was measured using surface electromyography (EMG). Activation of the muscles while performing stabilization exercise in four-point kneeling was normalized to a percentages of the MVC. Results: Left RA, right TrA/IO, right and left MF muscles showed significant differences among the positions. Conclusion: Selecting an optimal position can aid subjects on physical conditions while performing stabilization exercises in the four-point kneeling position.

• 산업경영시스템학회지
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• 제33권4호
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• pp.28-37
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• 2010

In this study, services for promoting health were provided to kindergarten children. As u-Health services for children, services centered of positioning of children are provided. However, since problems related with obesity and mental health are increasing day by day due to westernized eating habits, the necessity of physical and mental health care for children is on the rise. Considering this state, in this study, experiments of u-Health services under the concept of wellness were conducted on kindergarten children. For physical health, the children's obesity was controlled and for mental health, services of diagnosing hyperactivity disorder which is a sub symptom of ADHD were provided. Based on the results, it could be identified that parents' satisfaction and children's health conditions were improved.

• Elastomers and Composites
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• 제7권1호
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• pp.45-52
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• 1972

As a series of the studies of EPDM-Polymer blends, the experiments are concentracted to the investigation of the physical properties of the EPDM-NBR blends. The results are shown as follows; 1. As EPDM addition ratio is increased, the physical properties such as resistance to ozone and aging have also improved, on the other hand, elongation and abrasion resistance decreased. 2. Tear strength is less influenced by blending and character after aging exhibited the same result. 3. Tensile strength decreased with increase in EPDM contents, especially the ratio of EPDM/NBR are 50/50 and 75/25.

• Elastomers and Composites
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• 제7권2호
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• pp.175-182
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• 1972

As a series of the studies of EPDM-Polymer blonds, the experiments are concentrated to the investigation of the physical properties of the EPDM-CR blends. The results are shown as follows: 1. In blending, tensile strength decreased with increase in EPDM contents and decreasing value was good results than various EPDM blending. 2. As EPDM Addition ratio is increased physical properties such as elongation have also improved, on the other hand, hardness and abrasion resistance decreased. 3. Aging resistance is less influenced by blending. 4. Tear strength is less influenced by blending and character after aging exhibited the same result. 5. Ozone resistance was much improved after blending. It was effective more than the ratio of EPDM/CR is 25/75.

• 국제학술발표논문집
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• The 6th International Conference on Construction Engineering and Project Management
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• pp.101-103
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• 2015

Scientific methods that measure the physical demand requirements of a construction operation have not been arrived at maturity in construction community. It is attributed to the difficulty involved in performing controlled experiments on the operation and its' volatile jobsite environment. This paper presents a method that measures the physical demand requirement of the waterproofing activity and verifies the differences between various operations (e.g., a primer painting and a polyurethane coating) consisting of the activity. Two hypotheses, which are involved in the operations, are summarized as follows: [Hypothesis 1] when one performs the same amount of work; the one's average heart rate required for the polyurethane coating operation is higher than that required for the primer painting operation. [Hypothesis 2] when one performs the same amount of work, the one's break time required for the polyurethane coating operation is longer than that required for the primer painting operation.

• 아동학회지
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• 제34권1호
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• pp.53-70
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• 2013

This study proposes to find out what effects physical effort using props has on infants' ability in relation to their creative physical expression and physical self-concept. This study targets three-year-old preschoolers who attend S and T nursery, located in Yeonje, Busan, of which 16 belong to an experimental group. The research tools used in the study are the creative physical expression test by Kim Eun-Shim(1994), which is the modified version of Bae Hyun-Suck's testing tool(1990), and an altered version of the questionnaire focusing on physical self-concept by Whang Sun-Gack(2001). The experimental group is divided into a large and small sub-group and then physical activities involving props are done by these divided experimental groups once or twice a week for 12 weeks, while outdoor activities are carried out with the comparison group once or twice a week for 12 weeks. For both groups, a total of 20 experiments are done. To obtain answers to the research questions, an individual version of the T-test is conducted using means and standard variations of the experimental and comparison groups. The results of this study are as follows : 1) the physical efforts of the experimental group using props reaped more positive effects as regards creative physical expression than the comparison group, 2) the positive effect on the participants' physical self-concept is also more evident in the case of the experimental group.

• 자원환경지질
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• 제53권1호
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• pp.87-98
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• 2020

함안층 새발자국 화석지는 퇴적순서와 구조 및 암상에 따라 7개의 지층으로 구분되며, 새발자국은 최상부층에서 나타난다. 이 화석층에는 연흔과 건열 등이 분포하며, 주로 적회색 미사암과 흑색 이암이 교호하는 암상을 보인다. 화석층과 동일 암석을 수습하여 물리적 및 광물학적 특성 분석 결과, 흡수율 0.62%, 공극률 1.64%, 비중 2.63이며, 조암 광물로는 사장석, 석영, 방해석, 녹니석 및 운모가 동정되었다. 화석지의 암석학적 및 풍화특성을 바탕으로 보존처리에 적합한 강화제 적정성 실험 결과, 시료의 무게변화가 가장 적은 것은 OH 100이었다. 강화실험에 따른 색차도 OH 100을 적용한 시료에서 가장 안정적임을 보였다. 팽윤저지제와 병행하여 강화제를 처리한 시료는 색차에 큰 변화가 있었다. 초음파 속도 변화 역시 OH 100에서 가장 높아져 암석의 물성이 강화된 것으로 나타났다. 팽윤저지제와 함께 OH 100을 적용한 경우에 공극율이 감소하여 물성강화에 영향을 미친 것으로 확인되었다. 그러나 함안층 새발자국 화석지는 점토광물을 포함하는 세립질 퇴적암으로 점토광물의 층간간격 및 흡수율 감소를 통한 물성강화를 위해 실제 화석지에는 팽윤저지제(antihygro)와 OH 100 강화제를 병행해 처리하는 것이 가장 안정적일 것으로 판단된다. 이는 실내 함침실험 결과이므로 화석지에 직접 사용하기 위해서는 현장 적용실험 등의 검증이 필요하다.

• Coupled systems mechanics
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• 제4권1호
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• pp.37-65
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• 2015

Modeling and simulation of mechanical response of infrastructure object, solids and structures, relies on the use of computational models to foretell the state of a physical system under conditions for which such computational model has not been validated. Verification and Validation (V&V) procedures are the primary means of assessing accuracy, building confidence and credibility in modeling and computational simulations of behavior of those infrastructure objects. Validation is the process of determining a degree to which a model is an accurate representation of the real world from the perspective of the intended uses of the model. It is mainly a physics issue and provides evidence that the correct model is solved (Oberkampf et al. 2002). Our primary interest is in modeling and simulating behavior of porous particulate media that is fully saturated with pore fluid, including cyclic mobility and liquefaction. Fully saturated soils undergoing dynamic shaking fall in this category. Verification modeling and simulation of fully saturated porous soils is addressed in more detail by (Tasiopoulou et al. 2014), and in this paper we address validation. A set of centrifuge experiments is used for this purpose. Discussion is provided assessing the effects of scaling laws on centrifuge experiments and their influence on the validation. Available validation test are reviewed in view of first and second order phenomena and their importance to validation. For example, dynamics behavior of the system, following the dynamic time, and dissipation of the pore fluid pressures, following diffusion time, are not happening in the same time scale and those discrepancies are discussed. Laboratory tests, performed on soil that is used in centrifuge experiments, were used to calibrate material models that are then used in a validation process. Number of physical and numerical examples are used for validation and to illustrate presented discussion. In particular, it is shown that for the most part, numerical prediction of behavior, using laboratory test data to calibrate soil material model, prior to centrifuge experiments, can be validated using scaled tests. There are, of course, discrepancies, sources of which are analyzed and discussed.