• 한국산학기술학회논문지
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• 제19권11호
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• pp.8-17
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• 2018

방콕(태국) 등 동남아시아 도시 홍수의 경우 열악한 배수시설로 포장된 도로를 따라 광대한 도심지역이 저수위 홍수에 침수되고 있다. 모래가 부족한 도심지의 경우 모래주머니 등 기존 침수방지 방법은 유효하지 않으므로 인공적인 침수방어 구조물을 설치할 필요가 있다. 이와 관련하여 유럽 및 북미 일부 선진국을 중심으로 개발된 침수 월류방어장비들은 고가에 복잡한 시공성을 가지고 있어 동남아시아 지역에 저변을 확대하기 어려운 상황이다. 따라서 저가 및 단순 고기능형 도심형 홍수임시차수시스템(FRDS)을 개발할 필요가 있다. 이에 본 연구에서는 FRDS의 개요 고찰, 국내외 개발 동향 분석, 개발 니즈 및 방향 제시 등을 통해 동남아시아에 적용할 수 있는 FRDS를 개발하였다. 개발한 시스템은 한국건설생활시험연구원 서산 옥외실증시험센터에서 누수율변형 시험 및 내충격성 시험에 관한 KS 성능평가를 실시하였으며, KS F 2639(누수율 변형 시험)과 KS F2236(내충격성 시험) 기준을 통과하였다. 본 연구결과는 홍수재난과 관련하여 동남아국가 도시홍수에 적용할 뿐만 아니라, 국내 홍수빈발지역 및 주요시설 등에 활용할 수 있을 것으로 판단되며, 도시홍수와 관련하여 주요지자체 및 시설물 관리기관의 과학적 능동적 대응을 유도할 수 있을 것이다.

• 한국지반공학회논문집
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• 제39권10호
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• pp.5-18
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• 2023

일반적인 토공사에서 사용하는 진동롤러에 의한 층다짐을 급속충격다짐(RIC)공법을 이용한 일시 다짐으로 대체하면 토공에 소요되는 공사기간을 획기적으로 단축할 수 있다. 동적하중에 의한 다짐은 모래와 같은 조립질 토사에 적합한 공법으로 인식되고 있는데, 최근에는 매립 프로젝트의 주요 재료인 모래의 공급부족으로 세립분을 함유한 토사의 사용이 점차 증가하고 있다. 따라서 RIC와 같은 동적하중에 의한 다짐공법을 적용하기 위해, 세립분을 함유한 매립재료 사용 시의 유효개량심도에 대한 검증이 필요하다. 본 연구에서는 깨끗한 모래인 Sand fill과 세립분이 함유된 Public fill에 대한 RIC공법 적용 전·후의 현장시험 결과를 비교하여 세립분 함량에 따른 RIC공법의 유효개량심도에 대한 영향을 검토하고, 콘저항치 q_c를 사용한 다짐 품질관리기준과 관련된 문제를 논의하였다. 결론적으로 세립분을 포함하는 다양한 종류의 매립토사에 대한 다짐 품질관리를 위해서는 q_c 측정값의 정규화가 필요하며, 깨끗한 모래의 상대밀도 Dr=70%에 해당하는 다짐 품질관리기준은 정규화 콘저항치 Q_tn,cs=110으로 평가되었다. 이러한 결과를 바탕으로, RIC 품질관리 시에 적용 가능한 매립토사의 세립분 함량을 고려한 심도별 q_c 품질관리기준을 제안하였다.

• 한국농공학회지
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• 제26권1호
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• pp.52-72
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• 1984

This study was performed to obtain the basic data which can be applied to the use of epoxy resin mortars. The data was based on the properties of epoxy resin mortars depending upon various mixing ratios to compare those of cement mortar. The resin which was used at this experiment was Epi-Bis type epoxy resin which is extensively being used as concrete structures. In the case of epoxy resin mortar, mixing ratios of resin to fine aggregate were 1: 2, 1: 4, 1: 6, 1: 8, 1:10, 1 :12 and 1:14, but the ratio of cement to fine aggregate in cement mortar was 1 : 2.5. The results obtained are summarized as follows; 1.When the mixing ratio was 1: 6, the highest density was 2.01 g/cm$^3$, being lower than 2.13 g/cm$^3$ of that of cement mortar. 2.According to the water absorption and water permeability test, the watertightness was shown very high at the mixing ratios of 1: 2, 1: 4 and 1: 6. But then the mixing ratio was less than 1 : 6, the watertightness considerably decreased. By this result, it was regarded that optimum mixing ratio of epoxy resin mortar for watertight structures should be richer mixing ratio than 1: 6. 3.The hardening shrinkage was large as the mixing ratio became leaner, but the values were remarkably small as compared with cement mortar. And the influence of dryness and moisture was exerted little at richer mixing ratio than 1: 6, but its effect was obvious at the lean mixing ratio, 1: 8, 1:10,1:12 and 1:14. It was confirmed that the optimum mixing ratio for concrete structures which would be influenced by the repeated dryness and moisture should be rich mixing ratio higher than 1: 6. 4.The compressive, bending and splitting tensile strenghs were observed very high, even the value at the mixing ratio of 1:14 was higher than that of cement mortar. It showed that epoxy resin mortar especially was to have high strength in bending and splitting tensile strength. Also, the initial strength within 24 hours gave rise to high value. Thus it was clear that epoxy resin was rapid hardening material. The multiple regression equations of strength were computed depending on a function of mixing ratios and curing times. 5.The elastic moduli derived from the compressive stress-strain curve were slightly smaller than the value of cement mortar, and the toughness of epoxy resin mortar was larger than that of cement mortar. 6.The impact resistance was strong compared with cement mortar at all mixing ratios. Especially, bending impact strength by the square pillar specimens was higher than the impact resistance of flat specimens or cylinderic specimens. 7.The Brinell hardness was relatively larger than that of cement mortar, but it gradually decreased with the decline of mixing ratio, and Brinell hardness at mixing ratio of 1 :14 was much the same as cement mortar. 8.The abrasion rate of epoxy resin mortar at all mixing ratio, when Losangeles abation testing machine revolved 500 times, was very low. Even mixing ratio of 1 :14 was no more than 31.41%, which was less than critical abrasion rate 40% of coarse aggregate for cement concrete. Consequently, the abrasion rate of epoxy resin mortar was superior to cement mortar, and the relation between abrasion rate and Brinell hardness was highly significant as exponential curve. 9.The highest bond strength of epoxy resin mortar was 12.9 kg/cm$^2$ at the mixing ratio of 1:2. The failure of bonded flat steel specimens occurred on the part of epoxy resin mortar at the mixing ratio of 1: 2 and 1: 4, and that of bonded cement concrete specimens was fond on the part of combained concrete at the mixing ratio of 1 : 2 ,1: 4 and 1: 6. It was confirmed that the optimum mixing ratio for bonding of steel plate, and of cement concrete should be rich mixing ratio above 1 : 4 and 1 : 6 respectively. 10.The variations of color tone by heating began to take place at about 60˚C, and the ultimate change occurred at 120˚C. The compressive, bending and splitting tensile strengths increased with rising temperature up to 80˚ C, but these rapidly decreased when temperature was above 800 C. Accordingly, it was evident that the resistance temperature of epoxy resin mortar was about 80˚C which was generally considered lower than that of the other concrete materials. But it is likely that there is no problem in epoxy resin mortar when used for unnecessary materials of high temperature resistance. The multiple regression equations of strength were computed depending on a function of mixing ratios and heating temperatures. 11.The susceptibility to chemical attack of cement mortar was easily affected by inorganic and organic acid. and that of epoxy resin mortar with mixing ratio of 1: 4 was of great resistance. On the other hand, when mixing ratio was lower than 1 : 8 epoxy resin mortar had very poor resistance, especially being poor resistant to organicacid. Therefore, for the structures requiring chemical resistance optimum mixing of epoxy resin mortar should be rich mixing ratio higher than 1: 4.

• 설비공학논문집
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• 제30권1호
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• pp.44-49
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• 2018

High-strength plastic water supply pipe evaluation method was evaluated in this study. Up to date, high strength water supply pipes that we install are mostly ductile cast iron pipes. Sometimes, a few PVC pipes are installed. Metal pipes have rust problem on the surface, causing serious damage to metal pipes and reducing the expected life span of water piping system. Nowadays, depending on technology development, some companies have improved properties of general PVC pipe performance with remarkable properties that exceed KS and ASTM standard. Here, we suggest a new method of performance evaluation for high-strength water plastic pipes.

• 한국산업안전학회:학술대회논문집
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• 한국안전학회 1998년도 추계 학술논문발표회 논문집
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• pp.59-69
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• 1998

ABS sensor ring has been manufactured by P/M method using 400 series ferrite stainless steel. the results are as following : It is supposedly sufficient to use for control computer due to good experimental results of magnetic characteristics. Compared with sensor ring made by iron, 400 series ferrite stainless steel has shown a good corrosion resistance without an addition surface treatment. Thus the decreasing production process has been obtained. As a result of hardness and tensile test, 400 series ferrite stainless steel shown a good endurance when it is combined to C/V joint, and has a good hardness properties endurable In sand and pebble impact.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
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• pp.1109-1112
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• 2004

This study reports on the pressure relief design and braided composite of surge arrester. Surge arresters with porcelain housing must not have explosive breakage of the housing to minimize damage to other equipment when subjected to internal high short circuit current. As a solution, this study describes pressure relief design performance of arresters with braided composite module. In general, braided composite has Potential for improved impact and delamination resistance. Manufacturing processes of the braided composite could also be automated and could potentially lead to lower costs. Therefore, in consideration of characteristics of pressure relief for polymer arrester, the fabric pattern of braided composite was decided. And Polymer arrester module was manufactured with braid. The mechanisms of pressure occurrence and relief were investigated basically by analyzing arc energy and the correlation between thermal shock and indoor pressure in pressure relief test.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1996년도 봄 학술발표회 논문집
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• pp.146-152
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• 1996

Polypropylene fiber reinforced mortar and concrete as civil material or architectural material have been used in America and British etc, and have been researched. Polypropylene fibers have many advantages in many points ; in economical costs, chemical stability and durability. It has been reported that polypropylene fiber can control restrained tensile stresses and cracks and increase toughness, resistance to impact, corrosion, fatigue and durability. This study has been performed to obtain the properties of polypropylene fiber reinforced concrete such as compressive strength, flexural strength, toughness, slump, drying shrinkage crack and drying shrinkage characteristics. The test variables are fiber contents, fiber length, fiber types, and so on. From the results of this study, we can expect the effects of the admixtures of polypropylene fiber about strength and drying shrinkage properties in concrete and mortar.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1570-1574
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• 2008

Various mechanical test were conducted on conventional and crosslinked ultra-high molecular weight polyethylene(UHMWPE) all prepared from the same lot of medical grade GUR 1050 for artificial joint. The conventional materials were not irradiated and treated by heating. The cosslinked materials were irradiated with $25kGy{\sim}200kGy$ by gamma-ray andthen annealed or remelted. Gamma-ray irradiation and heat treatment process were found to significantly impact the crystallinity, and hence the mechanical behavior, of the highly crosslinked UHMWPE. The radiation dose and heating conditions were key predictors of the uniaxial yielding, plastic flow, and failure properties of conventional and highly crosslinked UHMWPE. The correlation model from experiments would be the basic information to enhance the were resistance of artificial joint liner.

• 자원환경지질
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• 제23권4호
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• pp.411-424
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• 1990

Mechanical, physical and petrographic properties of seventeen marble specimens collected from ten marble mines in Korea were investigated. Studied marbles were mainly composed of calcite, dolomite, and various amounts of serpentine, tremolite, olivine, quartz and opaque minerals. Complete and sutured textures were dominant. Compressive strength measured normal to the bedding plane is larger almost two times than that measured parallel to the bedding plane. From the results of Shore hardness test on marbles, water content was an important factor to decrease Shore hardness values. Engineering geological properties, especially, compressive strength, Young's modulus, wear resistance and water absorption could be controlled by the presence of quartz, and the type of marble texture. Water absorption-porosity, compressive strength-Young's modulus, and impact strength index-Los Angeles abrasion couples show good correlation. According to the comparative utility as commercial stone, it could be concluded that marbles from the Banglim mine, Songbo mine, Kwangdeok mine and Bongjeong mine were superior to that of other studied marbles.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 추계학술대회 논문집
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• pp.406-411
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• 2005

The Cement-Asphalt Mortar is a mixture of cement and asphalt emulsion, and is utilized as a grouting material for the railway track which is used to fill under-slab space so as to provide a stabilized track support and a tool for adjustment of track level. In addition, the cement-asphalt mortar is unique in that it can provide more resiliency to the track so that one can expect the impact mitigation. To develop the cement-asphalt mortar suitable for the requirements for track grouting material, this study have selected several mixture proportions which can satisfy those requirements and minimize the material segregation, and the properties of those mixtures, such as flowability(flow time), strength and the resistance to freezing-thawing have been tested. According to the test results, the cement-asphalt mortar well satisfies the requirements and it is found that the properties of the cement-asphalt mortar is suitable for the application to the railway track.