• Title/Summary/Keyword: falling impact

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A Study on the Applicability of a Cumulative Rebound Angle for the Assessment of Compressive Strength of Construction Materials Nondestructively (건설재료의 비파괴 압축강도산정을 위한 누적 반발각의 적용성에 관한 연구)

  • Son, Moorak;Jang, Byungsik;Kim, Moojun
    • Journal of the Korean GEO-environmental Society
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    • v.18 no.2
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    • pp.39-45
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    • 2017
  • This paper is to grasp the applicability of a cumulative rebound angle measured from the rebound action generated after impacting an object for the assessment of compressive strength of construction materials nondestructively and to propose the test results. For this study, an impact device was devised and used for impacting an object by an initial rotating free falling impact and following repetitive impacts from the rebound action which eventually disappears. Five types of construction materials, which are soil cement, cement paste, wood (pine tree), and two types of rock (shale and granite), were tested and both peak rebound angle and cumulative rebound angle were measured for each material by using a high-speed camera. The measured angles were compared with the directly measured compressive strength for each material. The comparison showed that for materials such as cement and rock the cumulative rebound angle, which reflects energy dissipation, rather than the peak rebound angle is more appropriate indicator for assessing the compressive strength of a material, but for a construction material such as wood which has a high toughness the magnitude of rebound is not an indicator to assess the compressive strength of a material.

Impact Analysis of Coaching Activities over Entrepreneur with respect to Entrepreneurs' Personal Characteristics on the Performance of Startups: Focusing on Entrepreneurs's Awareness Conversion Effect (창업가 특성요인과 창업코칭활동이 창업성과에 미치는 영향: 의식전환을 매개로)

  • Jeon, Eunjee;Yang, Youngseok;Kim, Myungseuk
    • Asia-Pacific Journal of Business Venturing and Entrepreneurship
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    • v.14 no.1
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    • pp.47-58
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    • 2019
  • This paper is brought to analyze an impact of coaching activities over entrepreneur with respect to entrepreneurs' personal characteristics on the performance of Startups focusing on entrepreneur's awareness conversion effect. In particular, the situation of falling focus of serious startup failure on uncoachable obstinate entrepreneur among the several causes of startup failures, this paper define the research mission of reducing this risk by inducing coaching types of cooperations between senior entrepreneur having serial successful startup experiences and beginning entrepreneur. This paper carry out literature reviews chiefly on startup coaching researches rather than mentoring studies because coaching stressing on self-oriented problem defining and solving by entrepreneur actively tend to be more effective than mentoring relying on mentor's guideline passively as solving startup's main upcoming problems. This paper implement four related researches. First, the impact analysis of entrepreneur's personal characteristics on coaching activities, second, influences of entrepreneurs environmental factors on them, Third, impact of coaching activities on entrepreneur's awareness conversion effect, Fourth, how strongly this conversion effect contributing on the performance of startup. As results of empirical research, first, this paper prove that entrepreneur's environmental factors impact positively on coaching activities over entrepreneur although failing on validating on significant impact of entrepreneur's personal characteristics on coaching activities. Second, this paper prove that coaching activities positively influence on entrepreneur's awareness conversion, hence ultimately positively on the performance of startups. As conclusion, this paper validate that coaching activities over entrepreneur through inducing on the conversion of entrepreneur's awareness lead entrepreneur to setting the bar high and accountable planning of business milestone. This paper contribute on delivering policy implication that government initiatin action-oriented training program for entrepreneurs should accept the module of coaching session to produce more effective results.

Interaction Analysis between Construction Business Indicators and Business Performance Indicators of Civil Specialty Contractors (토목 전문건설업체의 건설경기지표와 경영성과지표의 상관성 분석)

  • Kim, Nam-Sik;Lee, Dong Wook
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.34 no.5
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    • pp.1599-1608
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    • 2014
  • This study is to suggest specialty contractors with countermeasures to construction orders falling off, one of the construction business indicators for the construction industry, by analyzing the impact of dwindling construction orders to business performance indicators of specialty contractors as well as identifying inter-relationships between those performance indicators. For specialty contractors of civil construction, it is analyzed that their current ratio is significantly affecting obtention of construction orders, which in turn greatly affecting the ratio of owner's equity. It seems that the amount of construction orders has a direct relationship with the corporate stability. Therefore, this type of specialty contractors are determined to be able to obtain more orders for construction by improving current ratio.

Effect on the Balance Ability after Four Week Training Using the System for 3-D Dynamic Exercise Equipment (3차원 동적 운동기기를 이용한 4주간의 운동 시 균형 능력에 미치는 효과)

  • Shin, S.H.;Yu, M.;Jeong, G.Y.;Yu, C.H.;Kim, K.;Jeong, H.C.;Kwon, T.K.
    • Journal of rehabilitation welfare engineering & assistive technology
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    • v.6 no.2
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    • pp.1-8
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    • 2012
  • In previous studies, the dynamic exercise equipment just focused on the trunk stabilization exercise. However, our study is targeted at evaluation for the impact on the postural balance of those researches. Twelve male and twelve female subjects were volunteered for the balance training using this system. They had no medical history of backpain for the past six months. Trunk Stability and postural balance training was performed for 15 minutes a day, three times a week duing four weeks. To evaluate characterization of the postural balance using Balance System SD, Evaluation consist of the postural stability test and the postural limit test. As a result, this training with 3D dynamic exercise equipment help subjects improve the postural balance. These results are expected for using basic materials to the elderly with a high risk of falling and trained athletes needed to be a postural control.

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Effects on Balance and Gait for Chronic Stroke Patients with Side Walking Training (만성 뇌졸중 환자에게 측방 보행 훈련이 균형과 보행에 미치는 영향)

  • Kim, Inseop;Jeon, Seungjae;Lee, Geoncheol;An, Byungwook
    • Journal of The Korean Society of Integrative Medicine
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    • v.1 no.1
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    • pp.1-9
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    • 2013
  • Purpose : The purpose of this study is to investigate the impact on the ability to walk, balance after side walking training of hemiplegic patients caused by stroke. Method : The subjects were training before stroke onset whether more than one year elapsed 15 patients with chronic stroke patients, and Berg balance scale(BBS) and Timed up and go test(TUG), Functional reaching test(FRT), 20m walking time 200m walking time were measured and recorded. Training period, a total of three weeks, and training frequency circuit training times 10 minutes per training, 5-minute break, the 10-minute training total 25-minute training was conducted. Gait line of 3m to be based on the patient's side walking, and the risk of falling compared to the presence of the experimenter trained under was carried out. Result : 1. TUG, 2. 20m walking time, 3. 200m walking time 4. FRT, 5. All showed significant improvement in BBS. Judging from the results, the side walking training conducted three weeks due to chronic stroke hemiplegic patient's ability to balance and showed a positive effect on the improvement of walking ability. Conclusion : Accordingly, it was more effective to train hemiplegic patients with chronic stroke on side walking.

Effect Analysis of Korea Economic about the Growth Slowdown of China Economic under FTA (FTA 시대에 중국 경제의 성장둔화가 한국경제에 미치는 영향분석)

  • Kim, Kyoung-Hee;Yoo, Seung-Gyun
    • International Commerce and Information Review
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    • v.16 no.5
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    • pp.225-248
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    • 2014
  • Korea and China signed an FTA at November 10, 2014. The entry of China - the factory of the World - can be more active and easier. But Recently, China's economic growth is slowdown, and it began to emerge as a voice of concern. Therefore I analyze Chnia's economic slowdown is the impact on Korea's economy in this study. This study presented current trends and future prospects on China's economic situation. The changes of China's economic growth are the reduction of economic growth rate, falling proportion of processing trade, and the competition relationship of two countries. So they will be analyzed on this study. And this study presents ways that Korea economy reacts for China's economic growth slowdown. Trade statistics system of Korea International trade Association(KITA) is leveraged for this analysis. For competition relationship analysis, I analyze to use Contribution to the Trade Balance, Trade Specialization Index, Revealed Comparative Advantage of Country.

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Correlation and Hysteresis Analysis of Air-Water Temperature in Four Rivers: Preliminary study for water temperature prediction (우리나라 하천의 기온-수온의 상관관계 및 이력현상 분석: 미래 하천수온 변화 예측을 위한 사전검토)

  • An, Ji-Hyuck;Lee, Khil-Ha
    • Journal of Environmental Policy
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    • v.12 no.2
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    • pp.17-32
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    • 2013
  • The potential impact of water temperature on air temperature in response to recent anthropogenic global warming has been noticed. To predict climate, induced change in river aquatic environment, it is necessary to understand the thermal constrains of fish species and the timing of the projected river temperature. As a preliminary study, air-water temperature relationship was analyzed on the basis of the observed data during the time period of 2009-2011 and the number of data corresponds to 873-1083. As a result of analyzing the auto-and cross-correlation coefficient between air-water temperature, high correlation is shown (~0.9). It is also found that the correlation coefficient of air temperature is higher than that of water temperature at the lag time less than approximately 10 days. Observed data was divided into two groups to investigate hysteresis: rising limb and falling limb. For some stations there is strong evidence that hysteresis exist between air-water temperature relationships. Consequently it is recommended that seasonal hysteresis needs to be included in determining an airwater relationship.

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A Numerical Analysis of the Binary Droplet Collision by Using a Level Set Method (레벨셋 방법을 이용한 액적 충돌에 대한 수치해석)

  • Lee, Sang-Hyuk;Hur, Nahm-Keon
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.35 no.4
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    • pp.353-360
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    • 2011
  • The prediction of binary droplet collisions is important in the formation of falling drops and the evolution of sprays. The droplet velocity, impact parameter, and drop-size ratio influence the interaction between the droplets. The effect of these parameters results in complicated collision phenomena. Droplet collisions can be classified into four types of interactions: bouncing, coalescence, reflexive separation, and stretching separation. In the present study, the interfacial flow problem of the droplet collision was numerically simulated by using the level set method. 2D axisymmetric simulations on the head-on collisions and 3D simulation on the off-center collisions were performed. The numerical results of droplet behavior after the collision agreed well with the experimental and analytical results. The mixing of the mass of the initial droplets after the collision was also predicted by using different species index of colliding droplets.

An Analysis of Effects of Water Perturbation Exercise on Physiological Cost Index and Gait Ability in Stroke Patients (수중 동요 훈련이 뇌졸중 환자의 생리학적 소비지수와 보행 능력에 미치는 효과 분석)

  • Park, Seungkyu;Park, Samheon
    • Journal of The Korean Society of Integrative Medicine
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    • v.4 no.3
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    • pp.39-47
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    • 2016
  • PURPOSE : This study attempts to find the effects of water perturbation exercise performed on stroke patients in their physiological cost index and gait ability tests. METHOD : The subjects were 30 stroke patients, water perturbation exercise group was performed 3 day per week, for 40 minutes a day, for a period of eight weeks. The physiological cost index and gait of all subjects were assessed by using the polar, 6 Minute Walk Test (6MWT), and 10 meter Walk Test(10mWT) at pre training and post training. Paired t-test was used to analyze change before and after intervention in group. Pearson's correlation was used to analyze correlation of all variables. RESULT : Water perturbation exercise group showed increased physiological cost index. Water perturbation exercise increased gait ability, showing a significant difference. Showing the correlation between the relatively high amount between physiological cost index and 6 minutes walking test. CONCLUSION : From the result of the study, we found that water perturbation exercise was effective in improving physiological cost index and gait ability. The patient is considered to be used by itself to involve the treatment and the risk of falling from the lowered state into the treatment method for the intensive treatment of stroke patients to be useful in improving the cardiovascular system and ability to walk. Through underwater training for stroke patients in the future on the basis of this study it is considered to require additional clinical studies on the impact on daily living and quality of life of stroke patients.

Dynamic performance of girder bridges with explosion-proof and aseismic system

  • Wang, Jingyu;Yuan, Wancheng;Wu, Xun;Wei, Kai
    • Structural Engineering and Mechanics
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    • v.61 no.3
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    • pp.419-426
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    • 2017
  • Recently, the transportation of dangerous explosive goods is increasing, which makes vehicle blasting accidents a potential threat for the safety of bridge structures. In addition, blasting accidents happen more easily when earthquake occurs. Excessive dynamic response of bridges under extreme loads may cause local member damage, serviceability issues, or even failure of the whole structure. In this paper, a new explosion-proof and aseismic system is proposed including cable support damping bearing and steel-fiber reinforced concrete based on the existing researches. Then, considering one 40m-span simply supported concrete T-bridge as the prototype, through scale model test and numerical simulation, the dynamic response of the bridge under three conditions including only earthquake, only blast load and the combination of the two extreme loads is obtained and the applicability of this explosion-proof and aseismic system is explored. Results of the study show that this explosion-proof and aseismic system has good adaptability to seism and blast load at different level. The reducing vibration isolation efficiency of cable support damping bearing is pretty high. Increasing cables does not affect the good shock-absorption performance of the original bearing. The new system is good at shock absorption and displacement limitation. It works well in reducing the vertical dynamic response of beam body, and could limit the relative displacement between main girder and capping beam in different orientation so as to solve the problem of beam falling. The study also shows that the enhancement of steel fibers in concrete could significantly improve the blast resistance of main beam. Results of this paper can be used in the process of antiknock design, and provide strong theoretical basis for comprehensive protection and support of girder bridges.