• Computers and Concrete
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• 제8권6호
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• pp.677-692
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• 2011

Particle packing on meso-level has a significant influence on workability of fresh concrete and also on the mechanical and durability properties of the matured material. It was demonstrated earlier that shape exerts but a marginal influence on the elastic properties of concrete provided being packed to the same density, which is not necessarily the case with different types of aggregate. Hence, elastic properties of concrete can be treated as approximately structure-insensitive parameters. However, fracture behaviour can be expected structure-sensitive. This is supported by the present study based on discrete element method (DEM) simulated three-phase concrete, namely aggregate, matrix and interfacial transition zones (ITZs). Fracture properties are assessed with the aid of a finite element method (FEM) based on the damage materials model. Effects on tensile strength due to grain shape and packing density are investigated. Shape differences are shown to have only modest influence. Significant effects are exerted by packing density and physical-mechanical properties of the phases, whereby the ITZ takes up a major position.

• 한국약용작물학회지
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• 제16권3호
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• pp.188-191
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• 2008

Poncirus trifoliata Rafinesque has been used as the immature fruit of the trifoliate orange tree. This study was carried out to investigate the quality change of Poncirus trifoliata Rafinesque depending on packing materials (vacuum packing, PP (polypropylene) packing, gunny sack packing), storage places and storage periods up to 12 months. The change of loss on drying content, content of poncirin were measured during the 12 months. As a result, the loss on drying content was decreased rapidly in gunny sack packing after storage of 12 months at room temperature. The content of poncirin was decreased generally according to storage conditions and its average loss percent was 38.8%.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2008년도 제34회 동계학술대회 초록집
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• pp.147-147
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• 2008

• 한국식품위생안전성학회지
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• 제28권4호
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• pp.376-380
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• 2013

퍼플루오르옥탄설포네이트를 LC/MS/MS를 이용하여 분석한 결과 분석 대상물질의 고유한 스팩트럼을 얻어 정량하여 머므름 시간은 4.33분이었으며 상관계수($R^2$)은 0.9998로 양호한 직선상의 그래프를 얻을 수 있었다. 퍼플루오르옥탄설포네이트에 대한 분석법의 회수율은 99.84%로 전반적으로 좋은 회수율을 보였으며 또한 이 연구에 적용되기에 충분한 정밀도와 정확도를 가지고 있음을 확인할 수 있었다. 퍼플루오르옥탄설포네이트 정량한계 및 검출한계는 0.03, 0.009 ug/L이었다. 따라서 식품 용기포장재에서의 분석에 적용이 가능하였다.

• Geomechanics and Engineering
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• 제18권3호
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• pp.315-328
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• 2019

This paper presents an investigation on bearing capacity, load-settlement behavior and safety factor of rock-soil slopes reinforced using geogrid-box method (GBM). To this end, small-scale laboratory studies were carried out to study the load-settlement response of a circular footing resting on unreinforced and reinforced rock-soil slopes. Several parameters including unit weight of rock-soil materials (loose- and dense-packing modes), slope height, location of footing relative to the slope crest, and geogrid tensile strength were studied. A series of finite element analysis were conducted using ABAQUS software to predict the bearing capacity behavior of slopes. Limit equilibrium and finite element analysis were also performed using commercially available software SLIDE and ABAQUS, respectively to calculate the safety factor. It was found that stabilization of rock-soil slopes using GBM significantly improves the bearing capacity and settlement behavior of slopes. It was established that, the displacement contours in the dense-packing mode distribute in a broader and deeper area as compared with the loose-packing mode, which results in higher ultimate bearing load. Moreover, it was found that in the loose-packing mode an increase in the vertical pressure load is accompanied with an increase in the soil settlement, while in the dense-packing mode the load-settlement curves show a pronounced peak. Comparison of bearing capacity ratios for the dense- and loose-packing modes demonstrated that the maximum benefit of GBM is achieved for rock-soil slopes in loose-packing mode. It was also found that by increasing the slope height, both the initial stiffness and the bearing load decreases. The results indicated a significant increase in the ultimate bearing load as the distance of the footing to the slope crest increases. For all the cases, a good agreement between the laboratory and numerical results was observed.

• 한국미생물·생명공학회지
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• 제45권4호
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• pp.322-329
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• 2017

본 연구에서는 생활 폐기물 매립지 현장에 파일럿 규모의 바이오커버(pilot-scale biocover, PBC) 2기를 설치하고, 240일 동안 메탄 제거 효율을 모니터링하였다. 또한, 바이오커버 충전 소재를 채취하여 혈청병에서 잠재 메탄 산화능을 평가하였다. 바이오커버로 유입되는 메탄 농도는 23.7-47.9%(평균 값 = 41.3%, 중간값 = 42.6%) 수준이었다. 토양, 지렁이 분변토 및 퇴비 혼합물(7:2:1, v/v)을 충전 소재로 구축한 PBC1의 메탄 제거 효율은 60.7-85.5%이었다. 토양, 지렁이 분변토, perlite 및 퇴비 혼합물(4:2:3:1, v/v)을 충전 소재로 구축한 PBC2의 표메탄 제거 효율은 29.2-78.5%이었다. 그러나, 바이오커버의 충전 소재 자체의 메탄 잠재 산화 능력이 우수함에도 불구하고(평균메탄산화속도 = $180-199{\mu}g\;CH_4{\cdot}g\;packing\;material^{-1}{\cdot}h^{-1}$), 충전 소재의 다짐현상과 채널링이 발생하면 PBC1과 PBC2의 메탄 제거 효율은 0-30%로 저하되었다. 한편, 바이오커버의 메탄 제거 효율은 계절(외부 기온)에 따른 유의적인 차이를 보이지 않았다. 본 연구로부터 도출된 결과는 향후 매립지 현장에 실규모의 메탄 저감용 바이오커버를 설계하고 운전 조건을 구축하는데 유용하게 활용 가능하다.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.68-69
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• 2006

When an alloy such as Ni-W is liquid phase sintered, heavy solid W particles sedimentate to the bottom of the container, provided that their volume fraction is less than a critical value. The sintering process evolves typically in two stages, diffusiondriven macrosegregation sedimentation followed by true sedimentation. During macrosegregation sedimentation, the overall solid volume fraction decreases concurrently with elimination of liquid concentration gradient. However, in the second stage of true sedimentation, the average solid volume fraction in the mushy zone increases with time. It is proposed that the true sedimentation results from particle rearrangement for higher packing efficiency.

• 생물환경조절학회지
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• 제18권4호
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• pp.475-480
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• 2009

신선 퉁퉁마디의 저장성 향상을 위해 MAP에 적절한 포장재와 저장온도를 구명하고자 본 실험을 수행하였다. 저장중 생체중 감소는 $10^{\circ}C$ 이하의 저온과 무공필름에서는 2% 이하로 유지되었으나 $25^{\circ}C$의 유공필름처리는 4% 이상의 감소를 보이면서 품질저하가 발생하였다. 저장중 포장재내 대기조성은 필름 투과율에 비례하였는데 이산화탄소는 1~2%, 산소는 15% 이상으로 유지되었다. $25^{\circ}C$를 제외한 모든 처리에서 저장 중 포장재내 에틸렌 농도는 7일 이후 급격히 증가하였는데, $2^{\circ}C$에서 가장 높아 저온 장해가 발생한 것으로 추측되었다. 저장 최종일에 이취와 부패율은 $5^{\circ}C$에서 가장 낮았으며, 포장재별로는 다른 양상을 보였는데 저장온도중 가장 낮았던 $5^{\circ}C$에서는 $50{\mu}m$ 두께의 ceramic 필름이 가장 낮은 이취와 부패율을 보였다. 외관상 품질로 본 저장수명 역시 $5^{\circ}C$에서 $50{\mu}m$ ceramic 필름으로 포장하였을 때 28일 이상으로 가장 길었다.

• 대한본초학회지
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• 제23권2호
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• pp.9-17
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• 2008

Objectives : The purpose of this report was to provide the information packaging of herbal medicines by analyzing papers. We investigated the packaging materials, packaging methods and expiration date of herbal medicines by analyzing papers of the Korea, Japan and China. Methods : We survey herbal medicine-related law and crude drug monograph of compendium in each three country, we purchased herbal medicine of the Korea, Japan and China in the market and verify the expressed-item in packing paper. In case of Japan, we examine packaging materials, packaging methods, and expiration date of herbal medicine in pharmaceutical company. Results : The pharmaceutical company in japan used the methods of nitrogen gas pouring, vacuum packing for the herbal medicine packaging. The expiration date of the herbal products in Japan is generally 3 to 5 year after packaging. And packaging materials were aluminium and polyethylene. In Korea, pharmaceutical company used airtight packing for the herbal medicine packaging and expiration date of the herbal product were generally 3 year after packaging. Packaging materials were polyethylene, nylon or polyethylene-nylon mixed materials. In China, pharmaceutical company also used airtight packing for the herbal medicine packaging, and the expiration date were generally 5 year after packaging. Packaging materials were polyethylene, wrapping paper-used parcel or tea leaves filter paper. Conclusion : This results can present the basic data for expiration date and preservation methods of the herbal roots in Korea.

• 한국세라믹학회지
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• 제45권8호
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• pp.439-442
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• 2008

A series of reaction-sintered SiC was fabricated from preforms with varying volume fractions of two resin-coated SiC particles of different sizes (63 and $18{\mu}m$). The electrical resistivity and mechanical strength were eventually optimized at the small particle volume fraction of $0.3{\sim}0.4$, at which point the porosity of the preform was minimized. This study experimentally proves that additional processes after the formation of the preform, such as silicon infiltration and reaction sintering, do not apparently alter the optimum volume fraction of the preform packing, predicted by an existing analytical model based on solid packing. Thus, the volume fraction of particles of different sizes can be determined practically through the solid packing model to fabricate RSSCs with optimal properties.