• 한국지반공학회논문집
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• 제36권12호
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• pp.77-86
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• 2020

본 논문에서는 얕은 기반암 심도 및 지진 위험도가 상대적으로 낮은 지역에서 부지의 고유주기와 입력지진파의 평균주기의 영향에 따른 전단강도 보정의 필요성을 평가하였다. 이를 위해 일반적으로 널리 사용되는 Modified Kondner-Zelasko(MKZ) 모델과 함께 미소변형률뿐만 아니라 대변형률 영역에서의 응력-변형률 거동을 모사할 수 있는 General Quadratic/Hyperbolic(GQ/H) 모델을 사용하였다. 6개 부지의 다운홀 시험 자료와 평균주기가 다른 3개의 입력지진파를 사용하여 1차원 부지응답해석을 수행하였다. 그 결과, 입력지진파의 평균주기뿐만 아니라 부지의 고유주기에 따라 전단강도 보정 적용 유무에 따른 해석 결과의 차이가 발생했다. 부지의 고유주기의 영향을 파악하기 위해 유효최대지반가속도, 최대전단변형률 및 증폭계수와의 상관관계를 분석하였다. 분석 결과, 부지의 고유주기가 길고 연약한 지반일수록 그 차이가 더욱 커지는 것을 확인하였다.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2006년도 제33회 KOSCO SYMPOSIUM 논문집
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• pp.60-64
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• 2006

Propagation rates ($U_{edge}$) of various premixed, twin edge-flames were measured as a function of global strain rate ($\sigma$), mixture strength, and Lewis number (Le). Using a counterflow slot-jet burner with electrical heaters at each end, both advancing (positive $U_{edge}$) and retreating (negative $U_{edge}$) edge-flames can be studied as they propagate along the long dimension of the burner. Experimental results are presented for premixed methane/air twin flames in terms of the effects of $\sigma$ on $U_{edge}$. Both low-$\sigma$ and high-$\sigma$ extinction limits were discovered for all mixtures tested. As a result, the domain of edge-flame stability was obtained in terms of heat loss factor and normalized flame thickness, and comparison with the numerical result of other researchers was also made. For low ($CH_4/O_2/CO_2$) and high ($C_3H_8$/air) Lewis number cases, propagation rates clearly show a strong dependence on Le.

• 대한산업공학회지
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• 제38권4호
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• pp.254-257
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• 2012

Hedge funds can be established in Korea after the deregulation about setting up private equity funds on September, 2011. Although the variety of asset allocation strategies is the strength of hedge funds, most of Korean hedge funds uses only the equity long/short strategy. Therefore, it is need to introduce other strategies into Korea hedge funds, however all strategies can not be adopted at once because of the infrastructure of Korea financial market. In this paper, we find the optimal introductive order of strategies for Korea hedge fund in view of individual or institutional investors. For this analysis, HFRI data are used for the historical return of each hedge fund strategy and three methods (network visualization, principle component analysis and efficient frontier optimization) are used for finding the optimal order.

• 복식
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• 제48권
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• pp.197-216
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• 1999

This study reflects the aim of analyzing the formality and symbolism of the Chanel suit. Chanel had designed jersey and tweed cardigan suits in the 1910s and 1920s while her suits of the 1930s were crisply fitted. The suits of the 1950s and 960s while were comfortable and slightly boxy marked a significant step forword. Lagerfeld's mission at Chanel was to tranmute the basic elements of the Chanel style and make them contemporary. He has also introduced the contemporay wide shoulders and short tihht skirt In place of sensible knee-length skirts he offered hemlines that either grazed the ankles or exposed most of the thighs. Besides her very influential jersey and tweed cardigan suit Chanel continued to assert her considerable strength with materials often making her suits in very delicate feminizing fabrics. in place of the classic boxy tweed jacket Lagerfeld introduced jackets made of terrycloth denim and stretch fabric Many of Chanel's suits show a stylish sense of colour that would have made artist envious. Chanel and Lagerfeld chose variety of colours from beige and grey and black to blue green cerisen and red for her suits. They was completely in tune with the twentieth century understanding the changes in lifestyles of woman and also understanding how her clothes should cater to them Thus the Chanel suit is more a way of life than just a fashion and is synonymous with wealth and aritocracy. It is one of the most popular status-symbol styles of the 20th century.

• 한국안전학회지
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• 제27권5호
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• pp.117-125
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• 2012

In recent years, polymer concrete based on polyester resin have been widely generalized and the research of polymer concrete have been actively pursued by the technical innovations. Polymer concrete is a composite consisting of aggregates and an organic resin binder that hardens by polymerization. Polymer concrete are stronger by a factor of three or more in compression, a factor of four to six in tension and flexural and a factor of two in impact when compared with portland cement concrete. In view of the growing use of polymer concrete, it is important to study the physical characteristics of the material, emphasizing the short term properties as well as long term mechanical behavior. If polymer concrete is to be used in flexural load-bearing application such as in beam, it is imperative to understand the deformation of the material under sustained loading conditions. This study is proposed to empirical and mechanical model of polymer concrete tension creep using long-term experimental results and mathematical development. The test results showed that proposed model has been used successfully to predict creep deformations at a stress level that was 20 percent of the ultimate strength and viscoelastic behavior of recycled-PET polymer concrete is linear of stress level up to 30 percent. It is expected that the present model allows more realistic evaluation of varying stresses in polymer concrete structures with a constant loading.

• Structural Engineering and Mechanics
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• 제62권3호
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• pp.373-380
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• 2017

Concrete structures are often subjected to long-term static and short-term dynamic loads. Due to a relatively low tensile strength and energy dissipating characteristics, the impact resistance of concrete is considered poor. This study investigates the feasibility of using polypropylene fibers to improve the impact resistance of reinforced concrete slabs. Fourteen polypropylene fiber reinforced concrete slabs were fabricated and tested using a drop weight test. The effects of slab thickness, fiber volume fractions, and impact energy on the dynamic behaviors were evaluated mainly in terms of impact resistant, crack patterns, and failure modes. The post impact induced strains versus time responses were obtained for all slabs. The results showed that adding the polypropylene fiber at a dosage of 0.90% by volume of concrete leads to significant improvement in the overall structural behavior of the slabs and their resistance to impact loading. Interestingly, the enhancement in the behavior of the slabs using a higher fiber dosage of 1.2% was not as good as achieved with 0.90%.

• 한국연소학회지
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• 제14권1호
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• pp.25-30
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• 2009

Propagation rates ($U_{edge}$) of various premixed, twin edge-flames were measured as a function of global strain rate ($\sigma$), mixture strength, and Lewis number (Le). Using a counterflow slot-jet burner with electrical heaters at each end, both advancing (positive $U_{edge}$) and retreating (negative $U_{edge}$) edge-flames can be studied as they propagate along the long dimension of the burner. Experimental results are presented for premixed methane/air twin flames in terms of the effects of $\sigma$ on $U_{edge}$. Both low-$\sigma$ and high-$\sigma$ extinction limits were discovered for all mixtures tested. As a result, the domain of edge-flame stability was obtained in terms of heat loss factor and normalized flame thickness, and comparison with the numerical result of other researchers was also made. For low ($CH_4/O_2/CO_2$) and high ($C_{3}H_{8}$/air) Lewis number cases, propagation rates clearly show a strong dependence on Le.

• 한국지진공학회논문집
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• 제17권5호
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• pp.197-207
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• 2013

The seismic performance of school buildings has been a matter of common interest socially and academically. The structural system of the school buildings is representative of the domestic low-rise reinforced concrete moment resisting frames, which apply extensively infills in their masonry walls. The masonry infilled walls are divided into full masonry infill in the transverse direction and partial masonry infill in the longitudinal direction. The masonry infilled walls are usually not included in structural analysis during the design process, but affect significantly the seismic performance because they behave with surrounding frames simultaneously during earthquakes. Many researchers have studied the effect of the masonry infilled walls, but several issues have been missed such as the increase of asymmetry by adding the full masonry infill, the size of the mean strength of the full masonry infill, and short column effect by the partial masonry infill. The issues were analytically investigated and the results showed that they should be checked at least by nonlinear pushover analysis in the seismic performance evaluation process. The results also confirm the weakness of the guideline of Korean Educational Development Institute where the seismic performance is basically assessed without structural analysis.

• 한국기계가공학회지
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• 제3권4호
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• pp.95-100
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• 2004

Plastics is used to produce precise parts with an inclusion of a reinforcement material such as glass fiber or carbon fiber to improve the dimension accuracy. The plastic goods can be produced with inaccurate dimensions, low mechanical strength, or residual stress due to the over packing of cavity inside, if the filling balance of melt resin is not accomplished. To overcome this problem, it is necessary to design the runner system with the geometrical balance at the mold design stage. However, even if the balanced runner system is achieved, a severe filling imbalance is observed practically in a multi-cavity mold. In this study, experiments were performed with Taguchi method to achieve the filling balance in multi-cavity mold with a symmetric runner system, by the use of pure PA and PA with glass fiber 33%. The experimental results were investigated to understand the effect of related molding factors on the filling imbalance for two resins.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2006년도 제32회 KOSCO SYMPOSIUM 논문집
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• pp.7-12
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• 2006

The propagation rates ($U_{edge}$) of various premixed edge-flames were measured as a function of global strain rate (${ \sigma}$), mixture strength, and Lewis number (Le). Using a counterflow slot-jet burner with electrical heaters at each end, both advancing (positive $U_{edge}$) and retreating (negative $U_{edge}$) edges can be studied as they propagate along the long dimension of the burner. Preliminary results are presented for single and twin premixed hydrocarbon edge-flames in terms of the effects on $U_{edge}$. A low-${\sigma}$ extinction limit has been discovered for all mixtures tested but further analysis is necessary for full characterization since sufficiently $high-{\sigma}$ leads to an apparent stability limit. Propagation rates clearly show a strong dependence on Le. Future work will focus on completing the premixed hydrocarbon edge-flame analysis and include investigations into non-premixed edge-flames and edge-flames composed of fuels such as hydrogen ($H_2$) with significantly lower Le.