• Korea Journal of Cosmetic Science
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• 제2권1호
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• pp.1-10
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• 2020

Protection mechanisms for skin damage of ultraviolet (UV) absorbers in personal care products for protection against UV are well studied, but not for hair protection. The purpose of this study is to describe and compare the changes of physical property produced in human hair by doses of the UV-B exposure causing protein degradation. To observe the change of physical properties in hair, the experimental intensity of UV-B exposure has been established on the basis of statistical data from official meterological administration as daily one hour sunlight exposure for two weeks. Polysilicone-15, ethylhexyl methoxycinnamate (OMC), and octocrylene were employed for UV-B absorber, and those were treated to hair swatch by rubbing wash through shampoo and conditioner. Bending rigidity displayed kinetically successive reduction at high doses of UV exposure up to the 8,000 s, and exhibited different level at each sample of UV-B absorber. However, the values of Bossa Nova Technologies (BNT) for shinning factor were already saturable at the 2,000 s exposure except that treated with polysilicone-15. The differential scanning calorimetry (DSC) to measure a strength of inner protein produces a successive reduction of enthalpy as like a reduction of bending rigidity upon UV exposure. Surface roughness from lateral force microscope (LFM) acquired immediately after UV exposure show a saturable frictional voltage which has been also found in a saturable BNT data as the time of UV exposure increases. Through researching the DSC and the LFM, shinning of hair was much correlated to the protein damage at the surface, and bending rigidity could be regulated by the protein structural damage inside hair. Therefore, the optimization of efficient strategy for simultaneous prevention of hair protein on the surface and internal hair was required to maintain physical properties against UV.

• 가족자원경영과 정책
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• 제25권2호
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• pp.41-52
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• 2021

본 연구의 목적은 여성의 경제활동참가율과 가족정책변수, 양성평등가치변수가 출산율에 미치는 영향을 규명하는 것이다. 이를 위해 1990년부터 2019년까지 30년 간 OECD회원국의 출산율 자료와 UNDP 자료, World Value Survey 자료를 시계열로 결합한 패널데이터를 분석하였다. 종속변수인 출산율에 영향을 미치는 독립변수는 1단계에서 여성의 경제활동참가율과 통제변수를 투입하였고, 가족정책변수, 양성 평등가치변수 순으로 변수를 추가하면서 각 변수들의 변화를 비교하였다. 주요 분석 결과 첫째, 여성의 경제활동참가율은 각 모형에서 출산율에 양의 영향을 보였다. 즉, 여성의 경제활동참가로 인해 출산율이 감소되는 현상이 나타나지 않았다. 둘째, 가족정책변수인 부성 출산휴가기간이 출산율에 정적 영향을, 모성 출산휴가기간이 부적 영향을 미치는 상반된 효과를 보였다. 셋째, 양성평등가치변수인 성불평등지수가 높은 국가에서 출산율이 높았다. 또한 성평등 가치 수준이 높은 국가일수록 출산율이 낮았으며, 성평등 가치관을 3개 하위지표로 분리하여 분석했을 때 대학교육의 중요성에 양성 평등한 가치를 보일수록 출산율이 낮았다. 여성의 경제활동참가율이 출산율에 정적 영향을 미친 결과는 경제활동이 저출산의 원인이 아니며, 경제활동참여와 출산율이 동시에 상승할 수 있음을 보여준다. 또한 남녀의 출산휴가와 같은 정책적 지원, 그리고 남녀의 성평등 가치가 출산율을 조절할 수 있는 요인임이 확인되었다. 따라서 출산율은 가족의 시간, 소득 등 자원에 대한 배분과 관리, 자녀양육분담의 차원에서 이루어지는 의사결정이나 이를 지원하는 가족정책과 성평등 가치가 통용되는 사회적 기반 위에서 제고될 수 있을 것이다.

• 한국지반공학회논문집
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• 제25권4호
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• pp.19-29
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• 2009

본 연구에서는 실제 붕괴가 발생한 토류벽을 대상으로 해석 기법에 따른 시공단계별 거동특성을 분석하기 위하여, 단계별 굴착에 따른 토류벽의 변위, 휨모멘트, 토압분포, 예상 활동 파괴면을 수치해석을 통해 분석하였다. 특히 수치해석에 사용되는 해석기법으로, 벽계와 지반의 상호작용이 고려되는 전단강도 감소기법과 상호작용을 고려하지 않는 탄소성 해석으로 나누어 해석기법에 따른 벽체의 거동 차이를 비교 하였다. 본 연구결과, 벽체의 휨모멘트와 토압은 해석기법에 따른 차이가 크지 않았지만, 지표 근처에서의 벽체 변위는 큰 차이를 나타냈다. 또한 실측 데이터와의 비교결과 탄소성 해석을 통한 해석 결과가 전단강도 감소기법을 통한 해석 결과보다 전체적으로 변위 및 파괴면 예측에서 과소 평가 되는 것으로 나타났다. 따라서, 전단강도 감소기법을 통한 유한요소 해석은 벽체의 시공 안정성 및 붕괴 후 원인 분석 등의 좀 더 세밀한 검토가 필요한 작업에서 유용하게 사용할 수 있으며, 탄소성 해석기법은 1차적인 설계 정도에 사용하여야 할 것으로 판단된다.

• 문화기술의 융합
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• 제6권3호
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• pp.443-448
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• 2020

본 연구에서는 영종대교를 구성하고 있는 교량형식(트러스교, 현수교)별 열차종류(AREX, AREX Express, KTX, KTX-Sancheon) 및 열차속도가 강직결 궤도구조의 동적거동에 미치는 영향을 분석하고자 현장측정을 수행하였다. 현장측정결과를 바탕으로 궤도충격계수 및 열차주행안정성(탈선계수, 윤중감소율, 레일두부횡변위)을 국내, 외 관련기준 및 법규와의 비교하여 영종대교 교량상 강직결 궤도구조의 동적거동에 영향을 미치는 열차하중 및 속도의 효과를 분석하였다. 연구결과, 영종대교 교량형식별 궤도의 동적거동의 차이는 뚜렷하지 않으나 열차하중의 크기에 보다 직접적인 영향을 받는 것으로 분석되었다. 따라서 향후 열차속도 증가에 따른 궤도충격계수의 증가와 이에 따른 궤도부담력의 증가수준을 감안한 영종대교 강직결 궤도구조의 보강방안 수립이 필요할 것으로 판단된다.

• 문화기술의 융합
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• 제6권4호
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• pp.685-692
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• 2020

본 연구에서는 철근 겹침이음 위치가 부적정하게 시공된 사례를 바탕으로 콘크리트 구조기준에서 제시한 설치기준에 대하여 분석 및 고찰을 하였으며, 현행 구조기준에서 제시한 겹침이음에 대한 기준이 적정함을 해석적으로 입증하였다. 실제 종방향 균열이 발생된 지하 박스구조물 단면에 대한 철근 겹침이음부의 철근강도감소비 및 설계유효 모멘트를 산출하여 철근 겹침이음부의 균열 발생원인에 대하여 해석적으로 입증하였다. 연구결과, 최대 인장응력이 발생되는 지하 박스구조물 중앙부에 철근 겹침이음이 설치될 경우 철근 겹침이음부의 철근강도감소비는 82.8% 수준인 것으로 분석되었다. 따라서, 콘크리트 구조기준에서 정하고 있는 바와 같이 철근 겹침이음부의 위치는 최대 인장응력이 발생하는 지점을 피해야 하며, 부득이하게 겹침이음이 부적정한 위치에 설치되는 경우 본 연구에서 검토한 바와 같이 충분한 겹침이음길이를 확보하여야 하며, 구조물 단면력에 대하여 검토하여 충분한 안전율을 확보하는 것이 중장기적인 균열 제어 방법으로 적정할 것으로 검토되었다.

• PNF and Movement
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• 제17권3호
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• pp.487-497
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• 2019

Purpose: This tutorial review investigated the effect of prior fatigue and passive stretches on eccentric contraction-induced muscle injuries, as well as the underlying mechanisms of eccentric contraction-related injuries. Methods: Contraction-induced muscle damage is the most common disabling problem in sports and routines. The mechanisms underlying the pathology and prevention of muscle damage lessened by prior fatigue or stretches are critical in assessing musculoskeletal injuries. Even though there are treatments to reduce eccentric contraction-induced muscle injuries, fatigue negatively influences them. Therefore, we reviewed previous studies on eccentric contraction-induced muscle injuries with prior treatments using the MEDLINE and PubMed databases. Results: Prior passive stretching had a preventative and therapeutic effect, but prior lengthening contractions did not. On the other hand, prior isometric contractions involving relatively small forces may not provide a sufficient stimulus to induce protection. As a result, high force isometric contractions may be necessary. The studies supported the positive effects of prior fatigue, concluding that it was a factor in determining the amount of damage caused by eccentric exercise. This was due to a reduction in force and increased temperature. Studies that did not support the positive effects of prior fatigue concluded that a shift in optimal length to a longer length and reduced energy absorption during lengthening are evidence that fatigue is not related to muscle injuries induced by lengthening. Conclusion: The variability of the experiment models, conditions, muscles, and treatment methods make it necessary to interpret the conditions of previous studies carefully and draw conclusions without making direct comparisons. Thus, additional studies should be carefully conducted to investigate the positive effect of fatigue on lengthening.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.1248-1253
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• 2011

It is increasing construction of long span railway bridge with concrete track system for speed up of railway and efficient maintenance of track. As the sleeper of the concrete track system layed on a bridge is fixed on deck of the bridge, the displacement of the sleeper and deck is same. Therefore, the spacing between two sleeper installed at the end of the adjacent deck near the expansion joint of bridge becomes vary according to the longitudinal expansion of a deck by temperature change. By the way, if the spacing of sleepers become increase excessively, it causes large bending stress of in a rail, and it can leads failure or reduction of fatigue life of the rail. Further more, the excessive displacement of the rail may induce decrease ride comfort as well as corrugation of rail surface. Therefore, it is required to determine the allowable maximum sleeper spacing to prevent such problems. For the purpose, investigation on the influence factor on sleeper spacing for straight track was carried out. Variation of bending moment in a rail, wheel force, and the ratio of primary and secondary deflection of the rail according to sleeper spacing was investigated, and, as a result, the maximum allowable sleeper spacing at the bridge expansion joint was suggested.

• Steel and Composite Structures
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• 제12권5호
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• pp.445-464
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• 2012

In order to evaluate the dynamic behavior of passive energy dissipation system, two steps need to be considered for prediction of structural response in the presence of ductile element in an off-centre bracing system. The first is a detailed analysis of the proposed ductile element and the second is the effect of this ductile element on an off-centre bracing system. The use of ductile bracing system is expanding in steel structures in order to increase the force reduction factor. Therefore, regarding the nonlinear behavior of steel material used in an off-centre bracing systems and using ductile element in OBS bracing systems, the seismic evaluation of the mentioned systems seems to be necessary. This paper aims to study linear and nonlinear behavior of steel frames with off-centre bracing system and ductile element, in order to get the best position of these bracing elements. To achieve this purpose, the modeling has been done with ANSYS software. The optimum eccentricity has been obtained by modeling three steel frames with different eccentricities and evaluating the results of them. The analytical results showed that the model OBS-C with 0.3 eccentricities has higher performance among the models.

• 동력기계공학회지
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• 제3권2호
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• pp.26-33
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• 1999

Pressure pulsation Inside the discharge and suction cavity of rotary and scroll compressor are often a major source of objectionable noise and vibration. The key factor of these noise and vibration is due to the cavity resonance. It is not only necessary to understanding the characteristics of pulsation in order to reduce the excitation force of gas to the cavity but also to verifying the phenomena of cavity resonance. For the purpose of these understandings, measurement and simulation of cavity resonance can lead to a better understandings how they occur and be very important to identify the ways to reduce the noise efficiently. In this paper, modeling of the cavity(internal acoustics inside the shell) is discussed and simulated using FEM. Results from the simulation are compared with those measurement in experiments. In describing of cavity mode by experiments, it is very important to specify the exact conditions under which they are measured. Finally, this paper shows the one example of reduced cavity resonance in the compressor.

• Ocean Systems Engineering
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• 제8권2호
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• pp.101-118
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• 2018

In case of conventional shallow-draft semisubmersibles, unacceptably large riser stroke was the restricting factor for dry-tree-riser-semisubmersible development. Many attempts to address this issue have focused on using larger draft and size with extra heave-damping plates, which results in a huge cost increase. The objective of this paper is to investigate an alternative solution by improving riser systems through the implementation of a magneto-rheological damper (MR Damper) so that it can be used with moderate-size/draft semisubmersibles. In this regard, MR-damper riser systems and connections are numerically modeled so that they can couple with hull-mooring time-domain simulations. The simulation results show that the moderate-size semisubmersible with MR damper system can be used with conventional dry-tree pneumatic tensioners by effectively reducing stroke-distance even in the most severe (1000-yr) storm environments. Furthermore, the damping level of the MR damper can be controlled to best fit target cases by changing input electric currents. The reduction in stroke allows smaller topside deck spacing, which in turn leads to smaller deck and hull. As the penalty of reducing riser stroke by MR damper, the force on the MR-damper can significantly be increased, which requires applying optimal electric currents.