• 한국주조공학회지
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• 제42권1호
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• pp.61-66
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• 2022

Hydraulic units are important components of agricultural and construction machinery, and thus require high-quality castings. However, gas defects occurring inside the sand cores of the castings due to the resin used is a problem. This study therefore aimed to develop a casting simulation method that can clarify the gas defect positions. Gas defects are thought to be caused by gas generated after the molten metal fills up the mold cavity. The gas constant is the most effective factor for simulating this gas generated from sand cores. It is calculated by gas generating temperature and analysis of composition in the inert gas atmosphere modified according to the mold filling conditions of molten metal. It is assumed that gases generated from the inside of castings remain if the following formula is established. [Time of occurrence of gas generation] + [Time of occurrence of gas floating] > [Time of occurrence of casting surface solidification] The possibility of gas defects is evaluated by the time of occurrence of gas generation and gas floating calculated using the gas constant. The residual position of generated gases is decided by the closed loops indicating the final solidification location in the casting simulation. The above procedure enables us to suggest suitable casting designs with zero gas defects, without the need to repeat casting tests.

• 한국지반공학회지:지반
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• 제9권3호
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• pp.49-60
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• 1993

국내 폐기물 매립장에서 이용이 기대되는3종의 자연 및 인공혼합차폐재를선정하여 실내 투수 실험을 실시하여 자폐재와 화학용액과의 상호작용에 의한 반응성을 검토하였다. 연구에 사용된 차폐재 주재료는 김포해안 매립장 주변의 자연해성점토, 서천화력발전소의 부산물인 플라이애쉬 그리고 인천시 만수동 주변의 화강토이며 플라이애쉬와 화강토에는 벤토나이트를 각각 20%, 10%씩 첨가하였다. 시험에 사용된 투수 용액으로는 침출수에 많이 함유되고 있는 acetic acid, methanol, heptane, aniline의 4종이며 투수용액의 농도변화에 따른 차폐재의 투수특성을 살펴보기 위하여 투수용액 의 농도를 100, 75%로 하여 실험을 실시하였다. 시험 결과 화학원액 의 통과에 의하여 차폐 재의 투수성이 수배에서 수백배까지 증가하였고 증가정도는 서천플라이애쉬 흔합차폐재가 가장 작고 해성점토가가장 크게 나타났다. 화학용액중에서 투수성에 미치는 영향은 aceticacid가 가장 작고 aniline이 가장 큰 것으로 나타났으며 농도가 75%인 용액을 침출시킨 경우에는 차폐재 모두 투수성의 증가를 보이지 않아 원액을 제외한 상당한 고농도의 용액에도 본 실험에 사용된 차폐 재의 투수계수가 안정함을 보여 주었다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.107-112
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• 2005

Road is built continuously along with development of industry and cut slope is happened necessarily in road construction. Geoengineers are executing cut slope stability analysis considering various cut slope condition such as topography, geology, hydraulic condition and so on. The Tertiary Jungja Basin is located in the southeastern coastal area of the Korea Peninsula. Jungja Basin area is created by geotectonic movement of the plate after Early Miocene epoch. The northwestern and southwestern boundary of the basin is fault zone. The Basement rock is hornfels (Ulsan Formation). Basin-fills consist of extrusive volcanic rock(Tangsa Andesites), unconsolidated fluviatile conglomerate(Kangdong Formation) and shallow brackish-water sandstone(Sinhyun Formation). The characteristics of cut slopes in this area is different with cut slopes in the other site. Soil layers in this area is unconsolidated sediments and is not formed the weathering and erosion of the rock. So, the depth of soil layer is very thick. Faults of this area are northwest-southeast and northeast-southwest direction. Expandible clay mineral as smectite, chlorite et al. detected from fault gouge using XRD. Therefore, Jungja Basin area must consider the characteristics of the faults and soil layers thickness necessarily cut slopes stability analysis.