• 자원환경지질
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• 제19권4호
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• pp.297-304
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• 1986

Earthquake disaster is dependent upon both site intensity and strength of structures. The higher the strength, structures become more safe, which in turn increases the construction cost. Therefore, it is necessary to decide an optimum design intensity in which the safety is balanced with the cost. Such an optimum design intensity for major man-made structures in Korea is determined in the present study from a simulation model as follows. 1) Hypothetical earthquake time series are generated from the probability distribution to represent appropriately the seismicity of Korea. 2) The strength of structures constructed with a certain design intensity is assumed to exponentially decrease with the elapsed time. The construction cost is also expressed as a function of design intensity. 3) Comparing the seismic intensity generated from the earthquake time series with the strength of structures, the safety of structures is examined. Then the time until the structure is damaged by an earthquake is obtained within the designed life time. 4) The above simulation is iterated several hundred times and hence the mean life time of structures having a certain design intensity is obtained. 5) After all, the optimum design intensity to minimize the annual mean loss, the ratio of construction cost to mean life time, is estimated. The major conclusions obtained from the above simulation model are as follows. 1) Depending upon the designed life time ($T_p$), the optimum design intensities are appeared to be 0. 05-0. 10g for $T_p=50yr$ and 0. 08-0.13g for $T_p=100yr$. 2) According to the sensitivity analysis, the optimum design intensity increases with the rapid strength decrease of structure and decreases with the increase of initial construction cost.

• 한국산학기술학회논문지
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• 제12권2호
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• pp.805-812
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• 2011

이 연구의 목적은 고강도로 실시되는 12주간의 웨이트 트레이닝을 통하여 노인 여성들의 신체조성 및 기능적 체력에 어떠한 변화가 있는지를 규명하는 것이다. 연구대상자들은 U경로당에 정기적으로 출입하는 70세 이상 노인 여성 중에 실험의 취지를 알고 자발적 참여의사를 가진 24명을 선정하였다. 선정된 24명을 무선할당 방법을 통해 두 개의 운동집단인 고강도 저항성 운동 집단 (High intensity resistance group, n=8), 저강도 저항성 운동 집단(Low intensity resistance group, n=8) 그리고 비교군 (Control group, n=8)으로 나누었다. 운동집단은 12주간의 고강도 및 저강도 저항성 운동을 실시하였으며, 비교군은 12주간 어떠한 운동에도 참가하지 못하도록 제한하였다. 연구결과, 12주간 실시된 고강도 웨이트 트레이닝은 근력과 민첩성을 유의하게 향상시켰으며, 체지방률과 체지방량은 유의하게 감소시켰다(p<0.05). 평형성 및 심폐능력은 향상되었으나 통계적 유의성은 없었다. 종합해보면 정기적인 고강도 웨이트 트레이닝은 노인 여성들의 체력 개선에 도움을 줄 수 있는 운동이라 사료된다.

• 오토저널
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• 제13권5호
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• pp.42-50
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• 1991

According as the members and inner and outer plates of the automobile body structure have been thinned their thickness and have become high strength, each part of the body structure has been put more severe stress condition. Therefore, it has been increasingly required to improve the fatigue strength of the spot welded structures. As one of the improving methods for such problem, the author had previously proposed the method of alleviating stress concentration at nugget edge of the spot weld part and improving its fatigue strength [1]. But, because fatigue strength of the spot welded lap joint is influenced by its geometrical and mechanical factors, welding condition and etc., there needs a quantitative and systematic estimation method of them. In this report, by considering nugget edge of the spot weld part of the spot welded lap joint subjected to tensile load to the ligament crack, fatigue strength of various spot welded lap joints was estimated with the stress intensity factor (S.I.F.) K which is fracture mechanical parameter. It is known that evaluation of fatigue strength of the spot welded lap joint by the stress intensity factor (S.I.F.) K is more effective than the maximum stress $(\sigma_{ymax}$) at edge of the spot weld part on the center line of width of the plate.

• Coupled systems mechanics
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• 제7권3호
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• pp.297-319
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• 2018

In this paper, the vibro-acoustic behaviors of vibrational cylindrical shells are investigated by using structural intensity approach. The reducing interior noise method for vibrating cylindrical shells is proposed by altering and redistributing the structural intensity through changing the damping property of the structure. The concept of proposed novel method is based on the properties of structural intensity distribution on cylindrical shells under different load and damping conditions, which can reflects power flow in the structures. In the study, the modal formulas of structural intensity are developed for the steady state vibration of cylindrical shell structures. The detailed formulas of structural intensity are derived by substituting modal quantities, in which the effect of main parameters such as weight coefficients and distribution functions on structure intensity are analyzed and discussed. Numerical simulations are first carried out based on the structural intensity analytical solutions of modal formulas. Through simulating the coupling vibration and acoustical radiation problems of cylindrical shell, the relationship between vibro-acoustic and structural intensity distribution is derived. We find that for cylindrical shell, by properly arranging damping conditions, the structural intensity can be efficiently changed and further the noise property can be improved. The proposed methodology has important implications and potential applications in the vibration and noise control of fuselage structure.

• 한국간호교육학회지
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• 제22권3호
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• pp.345-354
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• 2016

Purpose: The purpose of this study was to determine the effects of a low intensity exercise program with telephone coaching on the physical fitness and physiological index of elderly women who are receiving home visiting health program. Methods: This study was conducted using a non-equivalent control group pretest-posttest design. The participants were 53 senior citizens. The subjects (15) in experimental group 1 performed only a low-intensity exercise program and the subjects (16) in experimental group 2 performed a low intensity exercise program with telephone coaching for 16 weeks. The low intensity exercise program consisted of muscle strength band exercise, stretching, and hand exercise using balls. Results: There were statistical differences in the right grip strength (p=.030), left grip strength (p=.035), raising behind of right arm (p=.046), raising behind of left arm (p=.045), postprandial blood sugar (p=.021), body mass index (p=.029). Conclusion: The low intensity exercise program with telephone coaching is recommended as a physical fitness and physiological index for elderly women in a home visiting health program.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2009년도 춘계 학술논문 발표대회 학계
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• pp.49-52
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• 2009

This paper aims to evaluate hydration and intensity property of different kind of members and intensity in order to evaluate compressive strength of structural concrete using Joint Separation Test Body(JSTB). In fact it is difficult to test and evaluate already have constructed member. In this case, common method used by construction engineer is that ; Schmidt rebound hammer test, Ultrasonic pulse test, Method of using test specimen previously cast. However, these method to control the structural intensity involve many problem and impossibility to adapt construction. 80, this paper proposes advance an opinion which have proper to examine intensity. has also aims to examine its validity and the plan to make similar environment with structural concrete and joint separation test body in order to verify efficiency assessment and on-site application.

• The Journal of Korean Physical Therapy
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• 제27권5호
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• pp.339-344
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• 2015

Purpose: The purpose of this study was to determine the effects of high and low resistance exercise using an elastic band on the strength and lymphedema of upper extremity in patients with breast cancer. Methods: Seventeen female patients with breast cancer related lymphedema were randomly allocated to the high (n=9) or low (n=8) resistance exercise group. Both groups participated in the elastic band exercise program three times a week for eight weeks. For the high resistance exercise group (HR), the resistance was gradually increased, while maintaining constant intensity of exercise for the low resistance exercise group (LR). Assessments made include the upper extremity muscle strength and lymphedema before and after training. Results: After the exercise program, the HR showed significantly improved shoulder flexion and elbow flexion strength variation compared to the LR (p<0.05). Upper arm edema rate was significantly decreased in HR (p<0.05), but the difference between the two groups was not significant. Conclusion: These findings suggest that the elastic band exercise helps improve the strength and lymphedema of upper extremity in patients with breast cancer. In particular, high resistance exercise is more effective in improving muscle strength and does not exacerbate lymphedema, rather may improve upper arm edema if it is applied with a low elastic bandage or compression sleeve.

• Structural Engineering and Mechanics
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• 제14권2호
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• pp.209-221
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• 2002

In this paper a fracture criterion is proposed for cracked cylindrical samples of high-strength prestressing steels of different yield strength. The surface crack is assumed to be semi-elliptical, a geometry very adequate to model sharp defects produced by any subcritical mechanism of cracking: mechanical fatigue, stress-corrosion cracking, hydrogen embrittlement or corrosion fatigue. Two fracture criteria with different meanings are considered: a global (energetic) criterion based on the energy release rate G, and a local (stress) criterion based on the stress intensity factor $K_I$. The advantages and disadvantages of both criteria for engineering design are discussed in this paper on the basis of many experimental results of fracture tests on cracked wires of high-strength prestressing steels of different yield strength and with different degrees of strength anisotropy.

• The Journal of Korean Physical Therapy
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• 제33권6호
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• pp.292-296
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• 2021

Purpose: The purpose of this study was to investigate the exercise effect of two types of training with a recumbent cycle ergometer on ankle muscle strength (dorsiflexor strength, DFS; dorsiflexor strength/weight, DFS/kg; plantar flexor strength, PFS; and plantar flexor strength/weight, PFS/kg) in healthy male subjects. Methods: Twenty-three healthy males (27.91±8.66 yr) were randomly allocated into two groups (high-intensity interval training (HIIT), and aerobic exercise training (AET) after the first measurement. The subjects were trained for 24 sessions (40 min/rep, three times/week) and ankle strength was measured for a second time. Two-way mixed model analysis of variance (ANOVA) was used to identify significant differences between changes in ankle muscle strength between before and after training (within factors) in the HIIT and AET groups (between factors). The statistical significance level was set at α=0.05. Results: In both HIIT and AET groups, all variables of ankle muscle strength were significantly increased after training compared to before training (p=0.001). However, there were no differences in all variables of ankle strength between the HIIT and AET group (p>0.05). Conclusion: Both types (HIIT and AET) of recumbent cycle exercise training could be effective training methods to increase ankle muscle strength in healthy individuals, and the HIIT type with high intensity and low frequency pedaling could be recommended more to strengthen ankle muscles.

• 대한소아치과학회지
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• 제28권1호
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• pp.45-53
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• 2001

레진 수복에서 초기에 저광도로 중합하여 레진의 유동성을 허용함으로써 중합시 내부응력을 상쇄하며, 다시 고광도로 중합하여 레진의 물성도 유지할 수 있는 방법이 시도되고 있어 초기 저광도 중합이 상아질과의 결합 강도와 레진의 미세경도에 미치는 영향을 알아보고자 하였다. 소의 건전한 하악 전치 20개를 3개의 절편으로 절단하여 각 군에 배분하고 상아질면에 레진을 충전한 후, I군은 $450mW/cm^2$의 광도도 40초간, II군은 $300mW/cm^2$와 $600mW/cm^2$의 광도로 각각 20초씩 III군은 $250mW/cm^2$와 $450mW/cm^2$에서 각각 20초씩 광중합하여 전단 결합 강도를 측정하였고, 직경 5.0mm깊이 2.0mm레진 시편을 제작하여 상, 하면 중앙에서 Vickers 미세 경도를 측정하였다. 전단결합 강도는 초기 저광도 중합군의 평균이 다소 높았으나 각 군간 통계학적 유의한 차이는 없었으며, 미세 경도는 상하면 모두에서 각 군간 통계학적으로 유의한 차이는 보이지 않았다.