• Proceedings of the SOHE Conference
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• 1997.12a
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• pp.39-43
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• 1997

Toha-jeod was manufactured by seven methods ; low salt group (L:15% sodium chloride), high salt g group (H:23% sodium chloride), 50% conventional soybean sauce group (S), low salt group containing 2% w wheat bran (W2%-L), high saIt group containing 2% wheat bran (W2%-H),high salt group containing 2% wheat bran (W2%-H), high salt group containing 4% wheat bran (W4%-H). After these seven groups were refrigerated at $4{\pm}1^{\circ}C$, they were sampled at intervals of three months and analyzed functional components. The free amino acid in Toha-jeod which are omitine, glutamic acid, leucine, alanine, lysine and valine increased gradually up to six months of fermentation and decreased by nine months. Conventional soybean sauce group increased continuously during the fermentation process. Hypoxanthine was altered almost among other nueletides. ATP was not detected, IMP and inosine had disapapted after the six months fermentation. Polyene fatty acids and n-3 fatty acids were decreased and s saturated fatty acids were not altered in the group containing wheat bran during fermentation. In the Hunter values, the group containing wheat bran and high salt group showed lower level than the group n not containing wheat bran and low salt group. Redness indicating the value of Toha-jeod increased as Toha-jeod was fermentated. Low salt group and conventional soybean sauce group were superior to other groups in the extent of redness. As the fermentation of Toha-jeod progressed for a long time, molecular weight distribution tended to become less molecular and the formation of chitin oligosaccharides was increased significantly. After nine months of fermentation, 24.75% chitin oligosaccharides [($GlcNAd_4$ ~ ($GlcNAd_8$, M.W. 823~1789] were created in the high salt group containing 2% wheat bran. [($GlcNAd_6$. M.W. 1236J , that is NACOS-6, which was reported as an antitumor activity material, was present in 4.01~4.37% of total Toha chitin content. 66.30% chitin oligosaccharides were created in conventional soybean sauce.

• The Journal of Engineering Geology
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• v.27 no.3
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• pp.233-244
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• 2017

We conducted hydraulic fracturing experiments on cement samples to investigate the dependency of fracture propagation on the viscosity of injection fluid and the in situ stress state. Ten cubic samples (20 cm side length) were produced using cement that was cured in water for more than one month. Samples were placed in a tri-axial compression apparatus with three independent principal stresses. An injection hole was drilled and the sample was hydraulically fractured under a constant injection rate. We measured injection pressures and acoustic emissions (AE) during the experiments, and investigated the fracture patterns produced by hydraulic fracturing. Breakdown pressures increased exponentially with increasing viscosity of the injection fluid. Fracture patterns were dependent on differential stress (i.e., the difference between the major and minor principal stresses). At low differential stress, multiple fractures oriented sub-parallel to the major principal stress axis propagated from the injection hole, and in some samples the fracture orientation changed during propagation. However, at high differential stress, a single fracture propagated parallel to the major principal stress axis. AE results show similar patterns. At low differential stress, AE source locations were more widespread than at high differential stress, consistent with the fracture pattern results. Our study suggests that hydraulic fracturing during shale gas extraction should be performed parallel to the orientation of minimum differential stress.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.4
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• pp.469-477
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• 2021

In this study, the mechanical property of anti-fouling coating using CNF was evaluated to prevent the durability and stability of structure exposed the marine environment. Anti-fouling coating using CNF was prepared by CNF, AKD and waste glass powder, and contact angle test, drying time, viscosity analysis and microstructure were performed. When coating on one number of times, It was showed to relatively high hydrophobic performance in steel. And It was confirmed that the contact angle increased as the content of AKD increased in cement mortar. When coating on three number of times, the surface was confirmed super-hydrophobic at maximum of 151.6°. When mixing waste glass powder, the surface was showed to relatively high hydrophobic. It is pseudo plastic fluid when CNF and distilled water were prepared in a ratio of 1:1, And Anti fouling coating is judged to be suitable for use as coating on marine structure.

• Journal of the Korean Geotechnical Society
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• v.27 no.7
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• pp.5-16
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• 2011

Digital image analysis techniques have been developed and utilized in the field of solid mechanics and fluid mechanics to measure the deformation and velocity of a target object. The deformation measurement systems based on Particle Image Velocimetry (PIV) and Digital Image Correlation (DIC) have been attempted in geotechnical testings (e.g., physical model tests) for observing the deformation of soils. The digital image analysis is influenced by image pattern of test materials, resolution of the used digital camera, target area, image analysis techniques, and analysis conditions. Therefore, optimal analysis conditions should be determined to obtain high quality results on soil deformations. In the present study, various influence factors on the digital image analysis were described and summarized. The optimizing procedure for high accurate results was then proposed. Finally, the applicability of the developed procedure was examined.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.05a
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• pp.377-382
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• 2010

The Present study uses non-Newtonian simulant gel propellant mixed by Water, Carbopol 941, and NaOH solution in order to analyze the gel propellant flow behavior. Rheological data have been measured and obtained prior to the analysis of flow characteristics where water-gel propellant as well as water-gel propellant with $Al_2O_3$ nano particles are both used. The critical Dean number were examined by numerical simulation of gel propellant in the U-shape duct flow. It is found that though gel-nano propellants have higher apparent viscosity, the critical Dean number did not showed notable difference with respect to the water-gel propellant. It is believe that this is due to the fact that the power law index of both propellants have close value, as was demonstrated by Fellouah et al.[1]

• Journal of the Korean Geotechnical Society
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• v.33 no.11
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• pp.45-57
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• 2017

Temperature change affects consolidation behavior of soft clays. The increase of temperature in soft clays induces the increase of pore water pressure. The dissipation of the excess pore water pressure decreases volume and void ratio. Also, the consolidation rate is accelerated by high temperature which induces the decrease of viscosity of pore fluid. The effects of temperature on the consolidation behavior such as consolidation settlement, consolidation time, and pore water pressure were investigated in this study. A numerical analysis of hydro-mechanical (HM) and thermo-hydro-mechanical (THM) behavior was performed. The combination of heat injection and sand drain for consolidating the soft ground, with varying temperature (40 and $60^{\circ}C$) and sand drain diameter (40, 60, and 80 mm), was considered. The results show that the temperature inside soil specimen increases with the increase of the temperature of heating source and the diameter of sand drain. Moreover, the heat injection increases the excess pore water pressure and, accordingly, induces additional settlement in overconsolidated (OC) state and reduces the consolidation time in normally consolidated (NC) state.

• Journal of Navigation and Port Research
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• v.40 no.4
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• pp.173-181
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• 2016

From 2016, controls on reduction of NOx and SOx emissions from the vessels that are operated in the emission control area were tightened. The selectivity catalytic reduction system of the denitrification equipment which NOx among the above controlled materials is very effective and used commercially very much. But it has the disadvantage that CSR is activated at high temperatures. Therefore, the SCR and SCR activation instrument that can react even at low temperatures by using micro-nano bubbles so that the above problems can be minimized were developed. And the computational fluid dynamics technique was used by ANSYS-CFX package to prepare the plan that improves the SCR system's efficiency. Simulation for the viscous flow analysis of the SCR system was executed by applying the Navier-Stokes equation to it as a governing equation. For the SCR system's shape, 3D modeling was done by using CATIA V5. SCR jet nozzle's position was checked by changing it to the intervals of 1/3, 1/2, and 2/3 from the inlet of the vent pipe to compare the SCR system's efficiency. And the number of nozzles was compared and analyzed by simulating 4, 6, and 8 holes to check an effect of the number on the SCR system's efficiency. The simulation result has found that the closer nozzles are to the inlet of the vent pipe and the more nozzles are, the more efficiency is improved.

• 한국전산유체공학회:학술대회논문집
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• 1995.10a
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• pp.31-36
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• 1995

비유선형의 물체 주위의 유동은 정체유동, 경계층 박리 및 주기적 와열 생성 등의 복잡한 유동현상이 공존한다. 본 연구에서는 비교적 단순한 형상인 정사각주 주위의 비정상 난류 유동을 2-방정식 와점성 난류모델인 표준 $k-{\varepsilon}$ 모델과 RNG $k-{\varepsilon}$ 모델을 이용하여 예측할 수 있는지를 검증하였다. 정교하게 수행된 최근의 실험과 대와류모사(LES)의 결과를 검증을 위한 비교의 자료로 삼았다. 적절한 난류모델의 선정과 더불어 시간 정확도, 공간 정확도 및 대류항 처리법 등이 해석결과에 미치는 영향도 살펴보았다. 기존의 표준 $k-{\varepsilon}$모델은 정체점 부근에서 난류 운동에너지를 과도하게 생성하는 근본적인 문제점 때문에 실험 및 LES의 결과를 제대로 예측할 수 없었다. 난류운동에너지의 초과 예측에 따른 운동량의 과도한 혼합으로 인해, 항력계수 및 양력계수의 비정상성 뿐 아니라 평균 항력계수도 부정확하게 예측하였다. RNG $k-{\varepsilon}$ 모델을 사용한 경우에는 정체점 주위 유동현상의 예측이 상당히 향상되어 항력계수 및 양력계수의 평균치, 진폭 및 비정상성의 주기 등을 정확하게 예측하는 것이 가능하였다. 그러나 이 경우에도 예측의 정확도가 시간 증분과 격자의 크기 및 대류항 처리법등에 영향을 받으며, 특별히 대류항 처리법에 상당히 민감하게 변하는 것을 알 수 있었다. 향상된 유동예측은 RNG $k-{\varepsilon}$ 모델의 난류에너지 소산율 방정식의 개선된 항이 과도하게 생성된 난류에너지를 정체점 부근에서 제거하기 때문에 가능하다는 것을 알 수 있었다.의 20세 이하 골절 및 탈구가$30.3\%까지 감소하게되어 년도가 증가함에 따라 청장년 층에 비하여 소아골절 및 탈구가 전체적으로 감소하는 경향을 보였다. 스키골절의 부위별 발생빈도는 1990년 이전까지 하지골절 및 탈구가 많았으나 이후 점차 상지의 골절 탈구가 증가하였다 하지에서 가장 많은 골절은 경골 골절이었으며, 경골골절은 회전력에 의한 나선형골절이 $76.5\%로 가장 많았고 년도에 따른 변화는 보이지 않았다. 스키손상의 발생빈도는 초기에 비하여 점차 감소하는 경향을 보였으며, 손상의 특성도 부위별, 연령별로 다양한 변화를 나타내었다.해가능성을 가진 균이 상당수 검출되므로 원료의 수송, 김치의 제조 및 유통과정에서 병원균에 대한 오염방지에 유의하여야 할 것이다. 확인할 수 있었다. 이상의 결과에 의하면 고농도의 유기물이 함유된 음식물쓰레기는 Hybrid Anaerobic Reactor (HAR)를 이용하여 HRT 30일 정도에서 충분히 직접 혐기성처리가 가능하며, 이때 발생된 $CH_{4}$를 회수하여 이용하면 대체에너지원으로 활용 가치가 높은 것으로 판단된다./207), $99.2\%$(238/240), $98.5\%$(133/135) 및 $100\%$ (313)였다. 각각 두 개의 요골동맥과 우내흉동맥에서 부분협착이나 경쟁혈류가 관찰되었다. 결론: 동맥 도관만을 이용한 Off pump CABG를 시행하여 감염의 위험성을 증가시키지 않으면서 영구적인 신경학적 합병증을 일으키지 않았고 좋은 혈관 개존율을 보여주었다. 따라서 동맥 도관을 이용한 Off pump CABG는 관상동맥의 협착의 정도에 따라 효율적으로 시행

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.4
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• pp.562-568
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• 2016

This study investigated the effects of Yuza pectin extract (0, 0.1, 0.15, and 0.2%, w/v) on the physicochemical, microbial, rheological, and sensory properties of yogurt. Pectin extract was extracted from Yuza peel by using citrate after juicing the flesh. The total sugar content of Yuza pectin was 89.07%. The pH of Yuza pectin extract-added yogurt was 4.43. All Yuza pectin extract-added yogurt samples showed shear-thinning flow behaviors (n=0.33~0.44). The values for apparent viscosity ($0.34{\sim}0.47Pa{\cdot}s$), consistency index ($4.48{\sim}10.25Pa{\cdot}s^n$), yield stress (6.56~17.61 Pa), storage modulus (47.96~75.21 Pa), and loss modulus (19.79~26.06 Pa) for 0.1~0.2% (w/v) Yuza pectin extract-added yogurt were considerably higher than those of the control. These result indicated that Yuza pectin extract could enhance steady and dynamic shear rheological properties of yogurt. The sensory scores of Yuza pectin extract-added yogurt were higher than those of the control.

• Korean Journal of Food Science and Technology
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• v.31 no.1
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• pp.24-29
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• 1999

The physicochemical properties of tagatose, a low calorie sweetener, was investigated. Rheological property of tagatose solution was found to be Bingham fluid. As the concentration of tagatose increased from 10 to 50% at $25^{\circ}C$, the viscosity increased from 1.65 to 5.14 cp. When the temperature of 40% tagatose solution increased from 15 to $55^{\circ}C$, the viscosity decreased from 4.59 to 2.33cp. The melting onset temperature and endothermic enthalpy of tagatose were $130.4^{\circ}C$ and -202.3 J/g, respectively, which were obtained from the analysis of differential scanning calorimetry. Tagatose showed higher water absorption than sucrose under $85{\sim}100%$ of relative humidity. Tagatose was less soluble than sucrose at $20{\sim}70^{\circ}C$. Water activity of tagatose in 60% concentration was 0.892, which was lower than 0.957 of sucrose solution. Tagatose solution adjusted from pH 2 to pH 12 was stable after 3 days. Amount of tagatose was not changed after heat treatment at $154^{\circ}C$ for 4 hours. But a browning reaction was found and absorbance of a tagatose solution increased with heat treatment.