플라이애쉬를 혼입한 콘크리트포장의 배합특성에 관한 실험적 연구

이주형,최성용,윤경구,정영화 江原大學校 産業技術硏究所 1997 産業技術硏究 Vol.17 No.-

As the weight of trucks increases, the need for concrete pavement also increases. Therefore, the addition of fly-ash may improve the properties of pavement concrete as well as recycle fly-ash. A full factorial experiment was performed using the primary variables, such as water-cement ratio, fly-ash substitution ratio, and maximum size of coarse aggregate, as a preliminary study for optimum mixture design for pavement concrete. The results of preliminary study indicates that the addition of fly-ash is the most important factor determining concrete strength, followed by the maximum size of coarse aggregate and water-cement ratio. It, also, shows the relative importance of fly-ash substitution ratio, compared to the water-cement ratio, and the interaction effects between the primary variables. Optimum mixture designs for pavement concrete incorporating fly-ash, that satisfied the target responses, were proposed in terms of fly-ash substitution ratio, water cement ratio and maximum size of coarse aggregate.

경량골재 콘크리트에 현무암의 재활용 방안연구

정영화,이정호,윤경구,윤청호 강원대학교 석재복합신소재제품연구센터 1997 석재연 논문집 Vol.2 No.-

현무암을 콘크리트 골재로 이용하여, 환경오염 방지와 에너지 절감 효과를 얻을 수 있다. 반요인실험법을 사용하여 현무암을 굵은골재에 일정한 비율로 치환한 콘크리트의 최적배합설계 제시를 위한 예비 실험에서 현무암의 굵은골재 치환율, 물-시멘트비, 잔골재율, 슬럼프와 같은 주요 변수와 변수 사이의 2차 상관관계를 파악하였다. 예비실험을 한 결과 현무암을 굵은골재로 100%까지 치환했을 때 현무암을 혼입한 콘크리트의 강도 발현에 가장 중요한 변수는 물-시멘트비로 분석되었고, 현무암의 굵은골재 치환율은 강도 발현에 거의 영향이 없는 것으로 분석되어 현무암을 콘크리트의 굵은골재로 대체할 수 있다는 것을 알게 되었다. 변수 사이의 2차 상관관계에서는 현무암의 굵은골재 치환율과 잔골재율의 상관관계가 콘크리트의 강도 발현에 가장 큰 영향을 미치는 것으로 나타났다. 목표압축강도를 만족하는 현무암을 혼입한 콘크리트의 최적배합설계는 현무암의 굵은골재 치환율, 물-시멘트비, 잔골재율에 관하여 제시하였다. The waste basalt might be used in concrete aggregate, saving energy and protecting environment. An half-factorial experiments were performed with the primarary variable such as water-cement ratio, waste basalt substitution ratio, fine aggregate ratio and slump as a preliminary study for optimum mix design of concrete. The preliminary study show that the water-cement ratio is the most important factor to the concrete strength, followed by slump. The substitute of waste basalt up to 70% has little infulence, indicating that it can substitute the coarse aggregate without damaging the Concrete strength. The interaction between waste basalt substitution ratio and fine aggregate ratio was most significant to the concrete strength among the 2-way interaction variable. Only compressive strength affect to the formation of optimum mix design area as target compressive strengh becomes bigger. Optimum mix designs of concrete incorporating waste basalt, satisfying the target responses, were proposed in terms of waste basalt substitution ratio, water-cement ratio and fine aggregate ratio.

韓國産 표고버섯 飮料의 品質에 關한 硏究

鄭永化,趙德鳳,崔春淳,馬相朝 광주보건대학 1984 論文集 Vol.9 No.-

To develop a beverage indigenous to Korea, Extracts from the mushroom were investigated for their chemical composition, extraction conditions and processing methods. Mushroom, Lentinus edodes which had been dried at 50℃ for 20 hours were extracted with hot water for 5 minutes, respectively. Fructose(10%, w/w) and licorice extracts(4 %, v/v) were added in the extracts. In an attemt to evalluate the quality of food by sensory testing, the difference testing for samples was conducted by selected members of a sensory panel. The results of the present study were as follows: 1. Amino acids of the final products were mostly composed of threonine and prolamine, glutamic acid, arginine, alanine, phenylalanine, etc. 2. GMP content of the final products was 2.09%(w/v). 3. It was concluded that extracts from the mushroom processes sufficiently acceptable qualities as a favorite beverage.

不變量과 修正係數를 使用한 [αββγααβ]r 積層復合板의 振動解析

김남윤,홍창우,심도식,정영화 江原大學校 産業技術硏究所 1996 産業技術硏究 Vol.16 No.-

For a large scale civil and architectural structures, mainly steel, concrete and aluminum have been used and weight and corrosion of materials became a major concern. Designing with composite materials is very much complicated. Simple classical theory may yield good results for selecting "initial" sections for preliminary design. D.H. Kim proposed to use the quasi-isotropic constants by Tsai for the preliminary design of the composite primary structures for the civil construction. Also he made simple equation using correction factor. In this paper, the simple formulas developed by D. H. Kim to obtain "exact" values of the natural frequencies of [ABBCAAB]r laminate are compared with reinforcing fiber orientations, are compared with nastural frequencies of bean. This work can be a guideline to obtain data in many other cases.

국부가열을 이용한 면외거셋의 피로강도 향상

정영화,남왕현,장동휘 江原大學校 産業技術硏究所 2001 産業技術硏究 Vol.21 No.B

In the study, the fatigue strength improvement and mechanism have been estimated by the Spot-Heating treatment on welded bead toes. For this, web-gusset specimens were made without residual stresses and the others with residual stresses imposed by Spot-Heating. The 4-point bending tests were performed in order to estimate the effect of spot-heating on fatigue strength and fatigue characteristics quantitatively for non load-carrying fillet welded joints subjected to pure bending. As a result of fatigue test, fatigue strength of As-Welded specimen for non load-carrying fillet welded joints subjected to pure bending has satisfied the grade of fatigue prescribed in specifications of korea, AASHTO and JSSC. As compare with As-Welded specimen and Spot-Heating specimen have increased about 20% for the fatigue strength at 7.7×106 cycles. The Spot-Heating by reformation of the residual stress on welded bead toes has greatly affected the fatigue crack propagation life, but has slightly affected the fatigue crack initiation life.

실측응력 및 시뮬레이션에 의한 트러스 철도교의 피로피해도 분석

정영화,김익겸,김지훈,김은성 강원대학교 산업기술연구소 2000 産業技術硏究 Vol.20 No.A

After measuring actual stress by two measurements(Dynamic Strain Meter, Histogram Recorder)on truss rail road bridge, we could perform time history analysis by 3-D beam element method on modelling bridge. And then,after analyzing bridge structure in static by 3-D modelling, we estimated degree of fatigue damage in main member, secondary member of tie zone,cutting area of base metal cross section for confirming the result. In case that the simulate stress is carried out on medeling bridge, most of those simulation mainly is performed by main members.But in real bridge fatigue damage problems generally caused by junctions, connections, joints in which especially local stress is activated. Therefore, in this paper actual stress on critical area was estimated through the analysis result by simulation. With this study, we can estimate the degree of fatigue damage from a safety point of view and comparative accuracy.

파형강판 지중암거의 시공상 문제점 및 보완에 대한 고찰

정영화,성유경,장동휘 江原大學校 産業技術硏究所 2008 産業技術硏究 Vol.28 No.A

The Corrugated steel plate structure(CPS) can be applied to construction sites with various purposes, and the merits of CPS such as economical efficiency and swiftness can be utilized when it is constructed properly in consideration of its characteristics. However, in Korea, since the history of corrugated steel plate culvert is relatively short, there are not enough design standards. This research is prepared for finding out the causes through examining and analyzing the problems based on the examples from the existing constructions. Moreover, this study can be utilized in preparing designs and design standards of corrugated steel plate culvert in the future and devising prevention measures and complementary measures by studying construction methods considering features of construction sites and circumstances, several points to be considered while carrying out construction works and prevention measures of a problem with the existing structures.

프리캐스트용 고성능 콘크리트의 내구특성 검토

정영화,윤경구,용석응,김형균 강원대학교 부설 석재복합신소재 제품연구센터 1999 석재연 논문집 Vol.4 No.-

포장용 콘크리트는 열악한 환경조건에 의해 손상을 받지 않을 정도의 충분한 내구성을 가지고 있어야 한다. 포장 콘크리트는 실질적으로 겨울철에 제설제로 인한 동해를 받는 열악한 환경에 놓이기 때문에 동결-융해에 대한 손실을 쉽게 받을 수 있다. 이 연구에서는 폴리프로필렌 섬유를 혼입한 포장 콘크리트의 내구특성을 검토하여 현장적용가능성을 검토하기 위하여 섬유종류, 섬유혼입율, 콘크리트 배합종류를 주요 실험변수로 하여 실내시험을 수행하였다. 이를 위하여 먼저 폴리프로필렌 섬유보강 콘크리트의 압축강도시험을 통하여 강도특성을 분석하고 박 저항성 시험을 통하여 내구특성을 분석하였다. 박리저항성 시험은 국내에서 제설제로 사용하고 있는 4%의 염화칼슘을 콘크리트시편 표면에 유지시켜 동결-융해 사이클을 진행시켜 매5사이클마다 겉보기 등급과 무게변화를 측정하였다. 그 결과, 압축강도는 섬유 혼입율이 증가할수록 증가하였으며, 망사형 섬유보다는 단사형 섬유가 강도증진에 효과적임을 확인할 수 있었다. 박리저항성은 섬유의 혼입율이 증가할수록 모든 배합에서 우수한 것으로 나타났다. 무게 변화는 모든 배합에서 단사형 섬유와 망사형 섬유 모두 혼입율이 증가할수록 무게 손실량이 섬유를 혼입하지 않은 시험편에 비해 1.85∼27.5%로 감소하는 것으로 나타나 박리저항성 증진에 효과적임을 확인할 수 있었다. 폴리프로필렌 섬유보강 콘크리트의 강도특성의 내구특성을 분석한 결과 고속도로 배합인 경우 단사형 섬유와 망사형 섬유 모두 혼입율 0.10%에서 강도와 내구성 증진효과가 가장 우수한 것으로 나타났다. 강도특성과 내구특성을 분석한 결과, 내구특성이 보통 콘크리트보다 내구특성이 우수하여 현장적용이 가능한 것으로 나타났다. Pavement concrete subjected to severe environmental condition may be vulnerable to frost attack practically where de-icing chemicals are used. This study focused on the investigation of durability characteristics of pavement concrete incorporating polypropylene fibers and application feasibility of these into the pavements of local roads and highway. A series of labortory tests were performed with main experimental variable such as fiber types, fiber contents and type of concrete mix. The test of compressive strength was executed as primary tests, before the durability tests such as a scaling resistance were performed. De-icing salt resistance test was progressed by recycling freeze and thaw in the presence of a 4% calcium chloride solution. The deteriorated surfaces were rated by visual inspection and the loss weight were measured at every 5 cycles. The compressive strength of polypropylene fiber reinforced concrete increased as the fiber contents increased. The loss of weight decreased by 1.85∼27.5% compared to those of plain concrete as the fiber contents increased in the all kind of concrete mix. Thus de-icing salt scaling resistance of polypropylene fiber reinforced concrete increased as the fiber contents increased in the all concrete mix. From the results of strength and durability of polypropylene fiber reinforced concrete, it was concluded that they may be applied to the pavement of local roads and highway due to their excellent durability characteristics superior to those of plain concrete.

탄성반력의 영향에 따른 직교 이방성 복합판의 고유 진동 해석

정영화,심도식,김경진,이세진 江原大學校 産業技術硏究所 1997 産業技術硏究 Vol.17 No.-

In this paper, the result of application of vibration method to the orthotropic plates with free edges supported on elastic foundation and with a pair of opposite edges under axial forces is presented. Such plates represent the concrete highway slab and hybrid composite pavement of bridges. The reinforced concrete slab can be assumed as a special orthotropic plate, as a close approximation. The highway slab is supported on elastic foundation, with free boundaries. Sometimes, the pair of edges perpendicular to the traffic direction amy be subject to the axial forces. The plate is subject to the concentrated load/loads, in the form of traffic loads, or the test equipments. Finite difference method is used to obtain the deflection influence surfaces needed for vibration analysis. The influence of the modulus of the foundation, the aspect ration of the plate, and the magnitudes of the axial forces and the concentrated attached mass on the plate, under the natural frequency is thoroughly studied.

鎔接이음한 構造用鋼의 疲勞龜裂進展擧動

정영화,이형근,김익겸,정진석 江原大學校 産業技術硏究所 1998 産業技術硏究 Vol.18 No.-

In recently, according to increase the construction rate fo steel bridge, it is necessary to develop the high strength, high toughness steel. Thus, this study show to evaluate the fatigue characteristic of SWS 570 B first used within a country. With the weld-joined compact tension specimens compared with each other, that is, transverse and lengthwise about the crack propagation, high and low in the imput heat level, the fatigue test were performed. The log-log curves between the fatigue crack propagation rate da/dN and the transition range of the stress intensity factor △K ahead the crack tip were drawed, with these data. By using this curve, we obtained C and m which is material constant from Paris-Erdogan power law. The opbtained resutls from this study indicate that fatigue crack growth rate of SWS 570 B is not heat input weld is carried out. Softening effects, which affect fatigue properties, are shown that it is not affected to the fatigue growth rates significantly.