• Journal of the Korean Geotechnical Society
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• v.27 no.3
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• pp.19-26
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• 2011

Compaction tests have been performed to investigate the compaction characteristics of sands and clays with organic mixture. Weathered granite soil, kaolinite, and granulated carbon were used as the alternatives of sand, clay, and organics, respectively. The soapy water which is a kind of surfactant solutions was also used as water substitute to see the engineering properties changes of each soil. As seen when water was used, the optimum moisture contents increased and the maximum dry unit weight decreased for the soil with surfactants as the percentage of the organic contents increased. Surfactants slightly improved the compaction efficiency at low compactive energy level for the weathered granite soil with organics. As the organic contents increased for clays with surfactants, the optimum moisture contents decreased and the maximum dry unit weight increased. Surfactants slightly improved the compaction efficiency of clays with organics at all levels of compaction energy.

• Journal of the Korean Geotechnical Society
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• v.36 no.4
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• pp.5-15
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• 2020

This paper proposes a revised Modified Cam Clay type failure surface based on the critical state theory. In the plane of the mean effective and von Mises stresses, the original Modified Cam Clay model has an elliptic failure surface which leads the critical-state mean effective stress to be always half of the pre-consolidation mean effective stress without hardening and evolution rules. This feature does not agree with the real mechanical response of clay. In this study, the preconsolidation mean effective stress only reflects the consolidation history of the clay whereas the critical state mean effective stress only relies on the currenct void ratio of clay. Therefore, the proposed failure surface has a distorted elliptic shape without any fixed ratio between the preconsolidation and critical state mean effective stresses. Numerical simulations for various clays using failure surfaces as yield surface provide mechanical responses similar to the experimental data.

• Journal of the Korean Geotechnical Society
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• v.36 no.12
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• pp.117-124
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• 2020

The present research focuses on a methodology to describe shearing response of clay with respect to temperature. An increase of temperature shifts the normal consolidation line to move down in the plane of void ratio and mean effective stress. The critical state line, however, does not move as much as the normal consolidation line in accordance with temperature increase. As temperature increase, therefore, the difference between the critical state mean effective stress and the pre-consolidation pressure reduces. To reflect this easily, the present study applies a bounding surface consisting of two parts divided by the critical state mean effective stress. This study calibrated a bounding surface for the soft Bangkok clay and performed elemental simulation for undrained triaxial compression tests. The elemental simulation showed that the model can describe the mechanical response upon temperature of clay without complex hardening and evolution rules compared to the experimental data.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.151-151
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• 2011

평활입자동역학법(SPH, Smoothed Particle Hydrodynamics)은 도수, 댐붕괴류, 쇄파 등과 같이 수면 변동이 큰 유체 역학 문제를 해결하기 위한 무격자법 중의 하나이다. SPH법을 이용하여 1.5에서 8.0 범위의 여러 가지 Froude 수에 대하여 도수를 모의하였다. 또한, SPH의 모의 결과와 비교 검토하기 위해 실험실 수로에 물리모형을 구축하였다. 도수 전면의 위치와 도수 후의 수심을 대상으로 수리실험과 수치모의 결과를 비교하였다. 그 결과 Froude 수가 5 미만일 때, 수치모의결과는 물리 모형과 비교적 잘 일치하였으나, Froude 수가 클 때는 오차가 커지는 경향을 보였다. 이처럼 수치 모의의 결과가 물리 모형과 차이를 보이는 주요 이유는 점성의 처리와 난류에 따른 와도와 관련이 있는 것으로 알려져 있다. 따라서, 이 문제는 난류모형을 도입하면 어느 정도 개선될 수 있을 것으로 판단된다.

• Korean Journal of Food Science and Technology
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• v.50 no.2
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• pp.138-142
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• 2018

The physical properties and heavy metal content in rices that were grown in different conditions were compared; two paddy rices grown in irrigated water and a Jeju rice grown in dry field without irrigation. The pasting properties, color, or amylopectin chain length distribution were different, however, they were independent of growing conditions. For heavy metals such as Pb or Cd, Jeju rice showed similar content to paddy rices. However, total and inorganic arsenic (As) contents were much lower; for Jeju rice, the total arsenic content was only 10.1-17.9% of that in two paddy rices, and the inorganic arsenic was just corresponding to 15% of that in paddy rice. The inorganic arsenic content decreased by 34.1, 23.8, and 17.5% in paddy rice by soaking, cooking, and dripping with hot water, respectively.

• Journal of the Korean Society of Food Culture
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• v.13 no.5
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• pp.509-518
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• 1998

The purpose of this study was to develop korean traditional gruel 'Hodojook' as a easy-to cook product by modifying cooking method and its concentrations. Physical and sensory properties of 'Hodojook' with various levels of concentration were investigated using viskograph and sensory evaluation panel. The result showed that hydrated rice flour has higher maximum viscosity than instantly ground rice. Addition of walnut lowered maximum viscosity and gelatinization beginning temperature. But gelatinization pattern was not affected by the level of walnut and modified cooking method. Sensory characteristics on the roasted odor, roasted taste, oily odor, oily taste and viscosity were significantly increased as the walnut levels are increased. 'Hodojook' of' with the 1:1:6 ratio (rice flour walnut : water) was recommended.

• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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• 2003.10a
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• pp.224.2-225
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• 2003

흑미죽의 저장성을 조사하기 위하여 알루미늄 접착 플라스틱 백에 배합된 흑미죽의 원료들을 밀봉하여 121$^{\circ}C$에서 20, 30, 40분간 호화와 동시에 가열 살균시킨 뒤 냉각시켜 온도 4$0^{\circ}C$, 습도 58%의 저장고에 3개월 동안 저장하면서 15일 간격으로 관능검사와 물리적 변화를 조사하였다. 맛, 경도, 점성, 색깔, 향, 전반적 기호도 등 관능적 품질은 각각의 저장 15일 후가 가장 좋았으며 그 후로는 점차적으로 약간 떨어지는 경향을 나타내었다. 온도에 따른 차이는 20분간 가열 살균한 것이 제조 직후에는 다른 처리구 보다 약간 떨어졌으나 저장 15일 후부터는 처리구간에 큰 차이를 보이지 않았다. 점도는 세 처리구 모두 제조 직후에 가장 낮았는데 그 후로 저장 60일 까지 서서히 증가하다가 다시 점점 떨어지는 경향을 나타냈다. 가열살균 온도에 따른 처리구에 있어서 점도의 차이는 크지 않았다. 색도는 저장기간 동안에 L값은 점점 낮아지는 반면에 a값과 b값은 점차적으로 증가하는 경향을 나타내었으나 가열 온도에 따른 처리구간에 색도의 차이는 그다지 크지 않았다.

• Korean Journal of Ecology and Environment
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• v.33 no.1 s.89
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• pp.9-22
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• 2000

The decomposition processes of Microcystis aeruginosa under the light and dark conditions were investigated in relation to the change of microcystins, physicochemical and biological factors. Cyanobacterial cells from upper stream of Lake Dae-chong were collected and incubated in the matrix of raw water under the light and dark conditions without additional nutrients. The decomposition of Microcystis cells started from beginning of the experiment and most of the cells were decomposed on 12th day. Under the light condition the concentration of toxins in filtrate fractionwas increased with the increase of viscosity as the decomposition of algal cells proceed whereas no significant change was observed under the dark condition. Microcystin- RR was most labile toxin than the other two microcystins because it was identified mainly in lyophilized cells but detected at trace level in the filtratefraction.

• Proceedings of the Korean Society for Food Science of Animal Resources Conference
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• 2004.10a
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• pp.209-212
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• 2004

본 연구는 도토리 가루가 지방대체제로 저지방 소시지 제조 시 첨가하여 기존의 유화형 소시지와 유사한 성상을 갖는 적정 형태와 적정량을 구하기 위하여 실시하였다. 도토리가루의 첨가 형태에 따른 이화학적 및 조직학적인 성상에는 차이가 없었으며, 첨가량이 0.5에서1.0%로 증가할수록 점성이 감소하였다. 한편 도토리 가루를 첨가한 저지방 처리구는 유화형 대조구와 명도에서만 차이를 보일 뿐 다른 이화학적 및 조직학적 성상에서는 차이를 보이지 않았다. 따라서 도토리 가루 0.5%를 저지방 소시지 제조시 첨가하여 Gelcarin을 첨가한 지방대체제와 유사한 성상을 보임으로써 도토리 가루의 지방대체제로서 이용 가능성을 시사하였다.

• Korean Journal of Food Science and Technology
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• v.25 no.6
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• pp.620-625
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• 1993

This experiment was carried out to predict the sensory properties of yogurt by instrumental methodology. Sensory attributes such as viscosity, mouth-feel, taste and quality were investigated. Instrumental parameters were measured with refractometer, viscometer, consistometer and rheometer. Sensory data showed that viscosity of peach yogurt was higher than that of strawberry and tropical-fruit-mixed (TFM) yogurts (p<.05). All instrumental parameters of peach yogurt were higher than those of strawberry and TFM yogurts, except cohesiveness and elasticity (p<.05). Viscosity measured by panelists was significantly correlated with instrumental viscosity, consistency, hardness, adhesiveness and gumminess in the fruit yogurts (p<.05). But mouth-feel and quality of yogurts showed poor relationships with instrumental parameters. The effective instrumental parameters for predicting sensory viscosity ($Y_{1}$) of yogurts were consistency ($X_{1}$), viscosity ($X_{2}$) and cohesiveness ($X_{3}$). And those for predicting mouth-feel ($Y_{2}$) were consistency. The estimated regression equations were as follows; $Y_{1}=4.968-0.0486X_{1}+0.00012X_{2}+0.0348X_{3},\;Y_{2}=5.701+0.0154X_{1}$.