• Computers and Concrete
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• 제19권5호
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• pp.467-475
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• 2017

The purpose of this study is to establish a prediction model for the electrical resistivity ($E_r$) of self-consolidating concrete by using waste LCD (liquid crystal display) glass as part of the fine aggregate and then, to analyze the results obtained from a series of laboratory tests. A hyperbolic function is used to perform nonlinear multivariate regression analysis of the electrical resistivity prediction model, with parameters such as water-binder ratio (w/b), curing age (t) and waste glass content (G). Furthermore, the relationship of compressive strength and electrical resistivity of waste LCD glass concrete is also found by a logarithm function, while compressive strength is evaluated by the electrical resistivity of non-destructive testing (NDT). According to relative regression analysis, the electrical resistivity and compressive strength prediction models are developed, and the results show that a good agreement is obtained using the proposed prediction models. From the comparison between the predicted analysis values and test results, the MAPE value of electrical resistivity is 17.0-18.2% and less than 20%, the MAPE value of compressive strength evaluated by $E_r$ is 5.9-10.6% and nearly less than 10%. Therefore, the prediction models established in this study have good predictive ability for electrical resistivity and compressive strength of waste LCD glass concrete. However, further study is needed in regard to applying the proposed prediction models to other ranges of mixture parameters.

• 한국산업융합학회 논문집
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• 제11권4호
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• pp.201-208
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• 2008

This thesis is the result of the study about 'How we should develop the human resources program to gain human strength in the strategic environment of the future?' Once again, regional stability is interdependent with economic stability, political stability, and military stability of all the factors in the region. History shows that if a militarily capable regime lacks economic resources, then there is political pressure on the regime to use their military to acquire needed resources. The purpose of this study is to find the way that how to gain excellent human resources now and in the future. Military man power should be strong whenever. The Ministry of National Defense has "Reform Military Structure Plan". The focus of this Plan is Korean military strategy in the situation of the confrontation between South and North Korea and in the situation of the international relationship and the way of constructing the military strength for the future. To study these subjects, I reviewed the theories of "Acquisition Program of Human Strength" were developed and assessed the future strategic environment of the Korean Peninsula. From these studies, I suggest that The Ministry of National Defense should pursue preparing for the future military strategy and military structure. we should be skillful in supplementing the Human Strength. We should study about Military Revolution Plan and Human Strength structure for the future.

• 한국구조물진단유지관리공학회 논문집
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• 제12권3호
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• pp.199-207
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• 2008

최근 구조물이 노후화되면서 기존 구조물과 시공품질을 관리하는 비파괴검사 평가의 요구가 증가되고 있다. 콘크리트 구조물의 압축강도 추정의 중요성이 건설업계에서 또한 점차적으로 증대되고 있는 실정이고, 시공관리와 품질관리에 있어서 중요한 요소이다. 본 연구는 콘크리트의 압축강도를 비교하기 위한 비파괴 검사법 중 슈미트해머 시험과 충격반향기법을 이용하여 수행되었다. 콘크리트 압축강도와 슈미트해머에 의한 반발경도 값과 충격반향기법 실험결과와의 관계를 알아내는데 초점을 두었으며, 콘크리트의 압축강도와 반발경도 값은 밀접한 관계가 있음을 알 수 있었다.

• 한국세라믹학회지
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• 제41권7호
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• pp.503-507
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• 2004

The importance of porous ceramics has been increasingly recognized and adequate strength of porous ceramics is now required for structural applications. Porosities of porous ceramics act as flaws in inner volume and outer surface which result in severe strength degradation. The effect of pore structure, however, on strength and reliability of porous ceramics has not been clearly understood. We investigate the relationship between pore structure and mechanical properties using a sphere indentation on bilayer structure, porous ceramic top layer with soft polymer substrate. Porous alumina and silica were prepared to characterize the isolated pore structure and interconnected pore structure, respectively. The porous ceramic with 1mm thickness were bonded to soft polycarbonate substrate and then fracture strengths were estimated from critical loads for radial cracking of porous ceramics during sphere indentation from top surface. This simple and reproducible technique provides Weibull modulus of strength of porous ceramics with different pore structure. It shows that the porous ceramics with isolated pore structure have higher strength and higher Weibull modulus as well, than those with interconnected pore structure even with the same porosity.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(II)
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• pp.317-320
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• 2005

In recent years, according to the development of construction technique, the constructions of longer span bridges, taller buildings, deeper offshore structures, and other megastructures are calling for construction materials with increasingly improve properties. So, the demand for high-strength concrete(HSC) have been increased and many new structures have been built using HSC with the compressive strength about 100MPa. However, it is well-known that as the strength of concrete increases, concrete becomes more brittle. Recent studies, however, shown that the brittleness of HSC can be improved by adding some fibers to the concrete. Especially steel fiber reinforced concrete(SFRC) can be used in this case. Many research works have shown that SFRC results in better crack and deflection control, higher shear strength, improved fatigue performance, increased impact strength, reformed flexural strength, advanced fracture toughness and enhanced postcracking resistance. So, this is a study on the long-term response of SFRC applied to HPC about 40MPa. Therefore, in this study, the test results of twenty-six high-strength concrete specimens and steel fiber-reinforced concrete specimens, with steel fiber content of 1 $\%$ by volume were presented. And the results are analyzed by using of the factors of time, mix properties, humidity/temperature, and loading conditions.

• 한국방재학회 논문집
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• 제11권2호
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• pp.23-29
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• 2011

본 연구는 거친 표면을 갖는 GFRP 보강근의 쪼갬에 의한 부착파괴 거동과 파괴강도를 인발실험을 통해 규명하였다. 실험변수로서, 보강근의 직경, 콘크리트 피복 및 콘크리트 압축강도에 대하여 실험을 수행하였으며, 동일한 변수에 대하여 5개의 실험 결과를 평균하여 실험에 대한 오차를 최소화 하였다. 또한 쪼갬에 의한 부착파괴거동을 인발력과 변위결과로부터 고찰하였다. 쪼갬부착파괴강도 결과는 여러 연구자가 제안한 이형철근 및 FRP 보강근의 쪼갬부착파괴강도 평가모델식과 비교하였다. 분석결과, 거친표면을 갖는 GFRP 보강근의 쪼갬부착파괴강도는 Harajli 등(1995)이 제안한 모델을 이용하여 가장 근사하게 평가할 수 있는 것으로 나타났다.

• PNF and Movement
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• 제17권2호
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• pp.303-310
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• 2019

Purpose: This study aimed to investigate the correlation between abdominal muscle strength and measures of respiratory function in stroke patients. Methods: The study participants comprised 17 (male: 12, female: 5) stroke patients hospitalized at W rehabilitation hospital in Busan, South Korea. Abdominal muscle strength was assessed using a digital manual dynamometer for 5 seconds contacting the sternal notch of the participants to bend the trunk. Respiratory function (forced vital capacity, forced expiratory volume in one second, forced expiratory volume in one second/forced vital capacity, and peak expiratory flow) was assessed using a spirometer. The collected data were analyzed using Pearson's correlation analysis, and the significance level was set 0.05. Results: A statistically significant correlation was found between abdominal muscle strength and forced vital capacity, forced expiratory volume in one second, and peak expiratory flow. However, abdominal muscle strength and forced expiratory volume in one second/forced vital capacity were not significantly correlated. Conclusion: This study demonstrated that there is a relationship between abdominal muscle strength and respiratory function. Exercise programs to strengthen the abdominal muscles are therefore necessary to improve respiratory function in stroke patients.

• 한국분말재료학회지
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• 제28권1호
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• pp.13-19
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• 2021

Bulk graphite is manufactured using graphite scrap as the filler and phenolic resin as the binder. Graphite scrap, which is the by-product of processing the final graphite product, is pulverized and sieved by particle size. The relationship between the density and porosity is analyzed by measuring the mechanical properties of bulk graphite. The filler materials are sieved into mean particle sizes of 10.62, 23.38, 54.09, 84.29, and 126.64 ㎛. The bulk graphite density using the filler powder with a particle size of 54.09 ㎛ is 1.38 g/㎤, which is the highest value in this study. The compressive strength tends to increase as the bulk graphite density increases. The highest compressive strength of 43.14 MPa is achieved with the 54.09 ㎛ powder. The highest flexural strength of 23.08 MPa is achieved using the 10.62 ㎛ powder, having the smallest average particle size. The compressive strength is affected by the density of bulk graphite, and the flexural strength is affected by the filler particle size of bulk graphite.

• Physical Therapy Rehabilitation Science
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• 제11권2호
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• pp.181-188
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• 2022

Objective: The purpose of this study to investigate the correlations among the motor function, balance, and gait velocity and the strength that could explain the variation of gait velocity of chronic stroke survivors. Design: This was a cross-sectional cohort study. Methods: Thirty hemiplegic stroke survivors hospitalized in an inpatient rehabilitation center were participated. The muscle tone of ankle plantarflexor and muscle strength of ankle dorsiflexor were measured respectively with modified Ashworth scale (MAS) and hand-held dynamometer. And the motor recovery and function with Fugl-Meyer assessment (FMA), balance with Berg balance scale (BBS) and timed up and go (TUG) test were measured. Gait velocity was measured with GAITRite. The correlation among motor function, muscle tone, muscle strength, balance, and gait were analyzed. In addition, the strength of the relationship between the response (gait velocity) and the explanatory variables was analyzed. Results: The gait velocity had positive correlations with FMA, muscle strength, and BBS, and negative correlation with MAS and TUG. Regression analysis showed that TUG (𝛽=-0.829) was a major explanatory variable for gait velocity. Conclusions: Our results suggest that gait velocity had correlations with muscle strength, MAS, FMA, BBS, and TUG. The tests and measurements affecting the variation of gait velocity the greatest were TUG, followed by FMA, BBS, muscle strength, and MAS. This study shows that TUG would be a possible assessment tool to determine the variation of gait velocity in stroke rehabilitation.

• 한국수산과학회지
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• 제25권4호
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• pp.322-323
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• 1992