• Steel and Composite Structures
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• 제22권1호
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• pp.141-159
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• 2016

Commonly in steel frames, steel beam and concrete slab are connected together by shear keys to work as a unit member which is called composite beam. When a composite beam is subjected to positive bending, flexural strength and stiffness of the beam can be increased due to "composite action". At the same time despite these advantages, composite action increases the strain at the beam bottom flange and it might affect beam plastic rotation capacity. This paper presents results of study on the rotation capacity of composite beam connected to Rectangular Hollow Section (RHS) column in the steel moment resisting frame buildings. Due to out-of-plane deformation of column flange, moment transfer efficiency of web connection is reduced and this results in reduction of beam plastic rotation capacity. In order to investigate the effects of width-to-thickness ratio (B/t) of RHS column on the rotation capacity of composite beam, cyclic loading tests were conducted on three full scale beam-to-column subassemblies. Detailed study on the different steel beam damages and concrete slab damages are presented. Experimental data showed the importance of this parameter of RHS column on the seismic behavior of composite beams. It is found that occurrence of severe concrete bearing crush at the face of RHS column of specimen with smaller width-to-thickness ratio resulted in considerable reduction on the rate of strain increase in the bottom flange. This behavior resulted in considerable improvement of rotation capacity of this specimen compared with composite and even bare steel beam connected to the RHS column with larger width-to-thickness ratio.

• 한국강구조학회 논문집
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• 제23권6호
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• pp.659-667
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• 2011

최근 초고층 빌딩의 구조설계에 있어서 풍하중이 가장 중요한 하중요소로 다루어지고 있으며, 일반적으로 풍하중 산정은 풍동실험에 의하여 수행되어 왔다. 그러나 보다 간편하면서도 정밀한 산정방법의 개발에 대한 필요성이 증대되면서 그 방법의 하나로 수치해석적인 접근법인 전산유체역학이 이용되고 있다. 또한 CFD해석은 실제 스케일로 모델링 및 시뮬레이션이 가능하고 시간도 단축할 수 있는 장점을 가지고 있다. 그럼에도 불구하고 실제 프로젝트에 대한 연구의 역사와 검증과정이 일천하여 이 해석법에 의한 신뢰도가 낮기 때문에 그 활용은 미미한 실정이다. 따라서 본 연구에서는 기존연구에서 제시된 프로토타입 모델의 풍동실험 결과와 CFD해석을 통한 해석 결과의 비교를 통해 CFD해석의 신뢰도를 입증하며, 더불어 난류강도가 신뢰도에 미치는 영향에 대해 제시하고자 한다.

• Journal of Trauma and Injury
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• 제27권4호
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• pp.186-191
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• 2014

Purpose: The objectives of this study were to assess pain relief according to the time after kyphoplasty and to evaluate the factors affecting pain relief after kyphoplasty in the treatment of a single-level osteoporotic vertebral compression fracture. Methods: A retrospective review of 34 kyphoplasties for single-level osteoporotic vertebral compression fractures was performed. Pain relief was assessed by using the visual analogue scale (VAS) at preoperatively and postoperatively at 6 weeks, 3 months, and 6 months. Associated factors, including age, sex, pain duration, bone mineral density, and cement leakage, were evaluated using the patients' medical records. Statistical analyses were conducted using the paired t-test to assess pain relief and using the independent t-test and Pearson's correlation coefficient to evaluate the relationship between those factors and pain relief. Results: Preoperatively, the mean VAS score was 7.06. Postoperatively, it declined to 3.66 (p=0.001), 2.81 (p=0.001) and 2.24 (p=0.001) at 6 weeks, 3 months and 6 months, respectively. Also, statistically significant pain relief was observed during the periods from 6 weeks to 3 months (p=0.001) and from 3 months to 6 months (p=0.001). However, reduction of the VAS score showed no significant correlation with age, sex, pain duration, bone mineral density, or cement leakage (p>0.05). Conclusion: Our study suggests that a kyphoplasty may be effective in osteoporotic vertebral compression fracture patients with acute pain and that after the kyphoplasty, pain is reduced remarkably for 6 weeks and then continuously for 6 months.

• Computers and Concrete
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• 제2권6호
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• pp.423-437
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• 2005

In this study two single-bay, three-storey space frames, one with brick masonry infill in the second and third floors representing a soft-storey frame and the other without infill were designed and their 1:3 scale models were constructed according to non-seismic detailing and the similitude law. The models were excited with an intensity of earthquake motion as specified in the form of response spectrum in Indian seismic code IS 1893-2002 using a shake table. The seismic responses of the soft-storey frame such as fundamental frequency, mode shape, base shear and stiffness were compared with that of the bare frame. It was observed that the presence of open ground floor in the soft-storey infilled frame reduced the natural frequency by 30%. The shear demand in the soft-storey frame was found to be more than two and a half times greater than that in the bare frame. From the mode shape it was found that, the bare frame vibrated in the flexure mode whereas the soft-storey frame vibrated in the shear mode. The frames were tested to failure and the damaged soft-storey frame was retrofitted with concrete jacketing and, subjected to same earthquake motions as the original frames. Pushover analysis was carried out using the software package SAP 2000 to validate the test results. The performance point was obtained for all the frames under study, therefore the frames were found to be adequate for gravity loads and moderate earthquakes. It was concluded that the global nonlinear seismic response of reinforced concrete frames with masonry infill can be adequately simulated using static nonlinear pushover analysis.

• Corrosion Science and Technology
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• 제11권2호
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• pp.48-55
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• 2012

Clamping force of a high strength bolt is reduced by a certain period of time after the initial set-up. In case of special treatments on faying surfaces such as protective coating, clamping force is relaxed more severely. Tests for slip critical joints subject to various faying surface parameters were conducted. Five different surface treatments were tested including mill scale surface, blast surface, rust surface and coated surfaces. Each specimen was composed of F10T M20 of high strength bolts and steel plates. Based on the result of slip coefficient test, blast treatment surface showed 0.59, rust treatment surface showed 0.54 and inorganic zinc treatment surface exhibited 0.44. Clean mill treatment surface and red lead paint treatment surface were 0.23, 0.21 respectively. It is identified that the slip coefficient in Korean structural design guide should be determined for various surface conditions. Subsequently from long term relaxation test of ASTM A 490 high strength bolts, relaxation of no-coated surfaces such as blast, clean mill, rust treatment, the loss of initial clamping load was 10.5%, 13.6% and 7.9% for 1,000 hours, while the loss of initial clamping force was reached as 15.0%, 18.7% more than the required redundancy 10% in case of inorganic zinc and red lead painted treatment. It is required that the limit of relaxation on coated faying surface should be established separately for various surfaces.

• Journal of Electrical Engineering and Technology
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• 제13권4호
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• pp.1663-1672
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• 2018

In recent times, gas insulated medium voltage (MV) circuit breakers (CB) form a vital component in power system network, considering its advantages such as reduced size and safety margins. Gas insulation characteristics of circuit breakers are generally measured by lightning impulse (LI) test according to IEC standard 60060-1 as a factory routine test. Considering the environmental issues of $SF_6$ gas, many research works are being carried out towards the mixture of $SF_6$ gases for high voltage insulation applications. However, few reports are only available regarding the LI withstand and streamer propagation characteristics (at both positive and negative polarity of waveform) of $SF_6/N_2$ gas mixture insulated medium voltage circuit breakers. In this paper, positive and negative polarity LI tests are carried out on 22 kV medium voltage circuit breaker filled with $SF_6/N_2$ gas mixture at different gas pressures (1-5 bar) and at different gas mixture ratios. Important LI parameters such as breakdown voltage, streamer velocity, time to breakdown and acceleration voltage are evaluated with IEC standard LI ($1.2/50{\mu}s$) waveform. Weibull distribution analysis of LI breakdown voltage data is carried out and 50% probability breakdown voltage, scale parameter and shape parameter are evaluated. Results illustrate that the $25%SF_6+75%N_2$ gas filled insulation considerably enhances the LI withstand and breakdown strength of MV circuit breakers. LI breakdown voltage of circuit breaker under negative polarity shows higher value when compared with positive polarity. Results show that maintaining the gas pressure at 0.3 MPa (3 bar) with 10% $SF_6$ gas mixed with 90% $N_2$ will give optimum lighting impulse withstand performance of 22 kV MV circuit breaker.

• 대한한방부인과학회지
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• 제32권2호
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• pp.129-137
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• 2019

Objectives: Most of the time after chemotherapy for ovarian cancer, the immune system is getting even worse with reduction of whole blood cell. The purpose of this study is to report the effect of korean medical treatment on Sequela including pancytopenia after chemotherapy for recurrent ovarian cancer after hysterectomy. Methods: The patient having treated with hospital management from June 8th in 2017 until July 5th in 2017, participated. Her chief complaints were fatigue, tinnitus, dizziness, decreased appetite due to glossodynia and constipation. We diagnosed her as pancytopenia based on her whole blood test result. We treated the patient with acupuncture, herbal medicine, cupping and moxibustion. The efficacy of treatment was evaluated with Numerical Rating Scale (NRS) and blood test. Results: During hospitalization period, the symptoms including fatigue, tinnitus, dizziness, decreased appetite, constipation and pancytopenia were reduced. After discharging, we identified that her blood levels are maintained and ovarian cancer no longer recurred. Conclusions: To recover from Sequela including pancytopenia following chemotherapy for recurrent ovarian cancer after hysterectomy, Korean medical treatment is considered to be effective.

• 한국지반공학회논문집
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• 제24권12호
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• pp.41-52
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• 2008

본 논문에서는 도로 혹은 철도 분야 옹벽 시공에 많이 적용되는 Back-to-Back (BTB) 옹벽 형태의 보강토 옹벽의 하중 지지 특성을 다루었다. 이를 위해 FHWA 설계 기준에서 구분하고 있는 두 가지 시공 조건에 대한 모형 보강토 옹벽을 구축하고 보강재 포설길이를 주 변수로 하여 상부에 상재하중을 파괴 시까지 재하하는 방법으로 다양한 조건에 대한 모형실험을 수행하였다. 실험 결과에 대한 분석 결과 좌 우 옹벽의 보강재가 중첩되지 않는 시공 조건의 경우 보강재의 길이에 따른 옹벽의 거동이 일반옹벽과 유사한 거동을 보이는 것으로 나타났으나 보강재의 길이가 중첩되는 경우에는 보강재의 길이에 따른 변화가 그다지 크지 않으며 보강재의 길이에 있어서 퐁벽높이 대비 50% 이하의 경우 하중지지력이 현저히 감소하는 것으로 나타났다.

• 한국식품영양과학회지
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• 제39권12호
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• pp.1800-1806
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• 2010

본 연구는 1일 1.5 L씩 4주간의 바나듐수 음용이 비진행성 암환자의 피로감 개선에 긍정적인 효과를 미치는 지 확인하기 위하여 수행되었다. 본 연구 결과 4주간의 바나듐수 음용은 비진행성 암환자의 피로감 개선을 위해 통계적으로 경계선상의 유의성을 보였으므로 향후에는 탐색형 연구로부터 확증형 연구를 통하여 피험자 수가 증가할 경우 통계학적으로 유의성을 보일 것이라고 예상되므로 근거 확보를 위한 진일보한 연구가 이루어져야 할 것이다. 즉 1일 1.5 L씩 4주간의 바나듐수 음용은 비진행성 암환자의 피로감 개선에 대해 유의수준 10%에서 통계적으로 유의한 차이가 나타났다. 이는 바나듐수가 암 환자의 피로에 도움이 되고 또한 참여자 수가 늘어날 경우 통계학적으로 유의성을 보일 것이라는 최소한의 근거를 보여주는 것이다. 향후에는 피험자수의 증가를 비롯하여 성별, 암종별 피험자수를 매치하고 피로감 개선을 포함한 기타 추가 기능에 대한 연구 수행을 기대할 수 있겠다.

• 한국전문물리치료학회지
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• 제21권3호
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• pp.45-54
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• 2014

Fall is one of the most intimidating health conditions in elders. Comprehensive assessment is necessary to understand the individual and environmental aspects of the falls such as balancing abilities, depression, and quality of life. The purpose of this study was to compare the balancing ability, depression, and quality of life between elderly fallers and elderly non-fallers. Thirty-two community-dwelling elders (fifteen males and seventeen females between 65 and 83 years old), who have experienced fall on walking during last twelve months, were involved in the elderly fallers group. And twenty-four males and twenty-two females between 65 and 83 years old of community-dwelling elders, who have no experienced fall on walking during last twelve months, were involved in the elderly non-fallers group. Berg balance scale (BBS), timed up and go test (TUG), and functional reach test (FRT), were used to evaluate the ability of the physical balance. 'Beck depression scale in Korean' questionnaire was used to assess the depression. 'Korean version of World Health Organization Quality of Life Assessment Instrument-Bref' questionnaire was used to assess the quality of life. The results were as follows: 1) Balancing abilities measured by the BBS, TUG in the elderly fallers group were meaningfully lower than that of the elderly non-fallers group (p<.05), whereas no significant difference in the FRT was found (p>.05). 2) Depression level in the elderly fallers group was significantly higher than that of the elderly non-fallers group (p<.05). 3) Quality of life in the elderly fallers group was significantly lower than that of the elderly non-fallers group, excluding environment domain (p<.05). Therefore, in order for clinical evaluation of the community-dwelling elders those with reduced balancing ability, it is necessary to evaluate and understand the fall experience, depression, and quality of life.