• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.125.2-125.2
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• 2011

청정 에너지원으로 높은 잠재력을 가지고 있는 가스하이드레이트는 상업적 기술개발이 미확보된 상태이다. 현재 전 세계적으로 가스하이드레이트 개발 및 생산에 관한 연구가 활발히 진행되고 있으며 이에 대한 기초자료로서 가스하이드레이트가 함유된 퇴적층의 물성자료가 필요하다. 특히, 현장 시료에 대한 물성 측정은 향후 가스하이드레이트 개발 및 생산 계획을 수립하는데 있어서 매우 중요하다. 탄성파 측정 결과는 다른 물성 들에 비하여 하이드레이트 함유 시료의 성형과정에 큰 영향을 받는다. 또한 그 외의 실험 경계조건과 취득 자료의 처리 과정에도 매우 민감하게 반응한다. 따라서 측정을 하는 과정은 물론 측정 후 자료의 활용 과정에서 다양히 고려해야 할 점들이 있다. 본 연구에서는 인공 모래를 이용하여 다양한 조건에서 탄성파 속도를 측정한 후 그 결과를 토대로 하여 기존의 연구 결과와 비교하여 음파 측정연구 시 고려해야 할 기술적 사항 들을 정리해 보았다. 실험에 사용된 장비는 고압의 퇴적층을 모사할 수 있는 압력셀과 메탄과 염수 주입에 사용되는 유체 주입장비, 하이드레이트 형성을 위한 온도조절장비, 자료 획득 장비로 구성되어 있다. p파 속도는 음파 송수신장비를 사용하였다.

• Design & Manufacturing
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• v.7 no.1
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• pp.45-49
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• 2013

Since the shell-molds are used to make casting the metal parts for the automobile industry, the quality may well be inconsistent with the lower productivity, increasing the cost of the end products. The primary elbow design shell molded steel castings being produced through extrusion process has $180^{\varnothing}$ O.D., $150^{\varnothing}$ I.D., 14mm thickness and 400mm length, while being processed onto the left side of the tubing. The primary cause for the poor processing is the uneven manual shell molding. If the manual shell molds should be produced to have even quality, they would not be processed for tube linking. The purpose of this study was to develop the flask-molds for manufacturing of the shell molds to ensure mass-production, consistent quality, ommission of processing and comfortable working environment. For this purpose, four flask-molds were produced and thereby, four shell molds were assembled. In particular, the shell molds for processing were formed of the fine coated sand to be blown. As a result, productivity increased about three times, while a consistent quality was ensured. Furthermore, the tubes could be linked with each other without being processed, while pallets could be stacked, stored, transported and managed more easily. In a nut-shell, the molding theory could be applied more effectively. However, it is conceived that this study should be followed up by future studies which will research into reliability and endurability of the end products.

• Journal of the Korean Geotechnical Society
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• v.24 no.12
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• pp.75-84
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• 2008

Recycled-aggregate porous concrete pile (RAPP) which forms a composite ground is one of new ground improvement techniques. In this paper, triaxial compression tests are carried out to investigate the shear strength characteristics of RAPP-Clay composite samples. The main purpose of the tests was to investigate the effects of area replacement ratio ($15%{\sim}100%$) on behaviors of RAPP-Clay samples during shearing. Also, triaxial compression tests using Sand-Clay composite samples were performed to compare with the behaviors of RAPP-Clay samples. The test results showed that the friction angle and cohesion of the RAPP-Clay composite were $18{\sim}34$ degree and $557.0{\sim}588.0\;kPa$, respectively, whereas those of sand-clay composite samples were 26~35 degree of friction angel and $4.0{\sim}18.0\;kPa$.

• Applied Chemistry for Engineering
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• v.23 no.3
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• pp.259-265
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• 2012

Differently from fly ash, the bottom ash produced from thermal power generation has been treated as an industrial waste matter, and almost reclaimed or was applied with the additive of the part concrete. Bottom ash has various problems to use with the aggregate. Bottom ash is lighter than typically the sand or the gravel and it's physical properties (compressive strength etc.) is somewhat low because of high absorptance. In order to manufacture the ash concrete, we used a bottom ash as a main material and a pure sulfur as a binder. In this study, fundamental research methods that vary the grain-size of bottom ash and the ratio of sulfur vs ash were investigated to improve the quality of ash concrete such as compressive strength. Bottom ash in this research which occurs from domestic 4 place power plants, was checked physical and chemical properties. The compressive strength seems the result which simultaneously undergoes an influence in content of the sulfur and Bottom ash grain-size. We got the result of the maximum 92 MPa. The compressive strength was high result for grain size below 1.2 mm and high sulfur content.