• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.20 no.1
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• pp.30-36
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• 1984

It is well known that the application of linear elastic fracture mechanics is inadequate to solve the large deformation fracture failures which occurr in ductile manner because of the large scale yielding due to the severe stress concentration in the region adjacent to the crack tip. The authors have been evolved a fracture model, the crack plane equilibrium model, for this kinds of elastic-plastic fracture problems in the previous report. In this report, the crack plane equilibrium model was compared with the Irwin's plastic zone corrected linear elastic fracture mechanics through theoretical comparisons and experimental results to examine the validity of the crack plane equilibrium model as an available tool for nonlinear fracture analysis. Through this study, the main results were reached as follows; Irwin's plastic zone corrected linear elastic fracture mechanics could be applicable only for small scale yielding problems as expected while the crack plane equilibrium model valid as a fracture model for large deformation fracture failure. However, the followings should be considered for the more precise evaluations of CPE model; 1) It is necessary to test more specimens which contain small cracks in the range of 2a/W<0.1. 2) It is important to detect the crack initiation point during the fracture test for determining an accurate fracture load. 3) Effects of specimen thickness in the fracture process zone should be examined.

• Journal of the Korean Geotechnical Society
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• v.23 no.3
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• pp.89-100
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• 2007

In the companion paper, we provided the novel elastic-plastic constitutive model based on the micromechanics theory. Herein, the elastic and elastic-plastic deformation of granular soils is meticulously analyzed. To guarantee high accuracy of the microscopic parameter, the systematic procedure to evaluate the parameters is provided. The analysis of the elastic response during the isotropic and triaxial compression shows that the stress-level dependency of cross-anisotropic elastic moduli is induced by the power relationship of the contact force in the normal contact stiffness, while the evolution of fabric anisotropy is more pronounced during triaxial compression. The micromechanical analysis indicates that the plastic strains are likely to occur at very small strains. The plastic deformation of tangential contacts has an important role in the reduction of soil stiffness during axial loading.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.6
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• pp.111-119
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• 2023

Recently, a variety of new cement-based materials have been developed, and attempts to predict the properties of these new materials are increasing. In this study, we aimed to predict the rheological properties of binary blended pastes. The cementitious materials used in the study included Portland cement (PC), fly ash (FA), blast furnace slag (BS), and silica fume (SF). The three binder components, fly ash, blast furnace slag, and silica fume, were blended with cement as the foundational composition. We predicted the yield stress and plastic viscosity of the pastes using the YODEL (Yield stress mODEL) and Krieger-Dougherty's equation. The predictive model's performance was validated by comparing it with experimental results obtained using a rheometer. When the rheological properties of the binary blended paste were predicted by reconstructing the properties and parameters used to predict the individual materials, it was evident that the predictions made using the proposed method closely matched the experimental results.

• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.2
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• pp.69-76
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• 2024

The rheological properties of fresh concrete significantly influence its manufacturing and performance. However, the diversification of newly developed mixtures and manufacturing techniques has made it challenging to accurately predict these properties using traditional empirical methods. This study introduces a multiscale rheological property prediction model designed to quantitatively anticipate the rheological characteristics from nano-scale interparticle interactions, such as those among cement particles, to micro-scale behaviors, such as those involving fine aggregates. The Yield Stress Model (YODEL), the Chateau-Ovarlez-Trung equation, and the Krieger-Dougherty equation were utilized to predict the yield stress for cement paste and mortar, as well as the plastic viscosity. Initially, predictions were made for the paste scale, using the water-cement ratio (W/C) of the cement paste. These predictions then served as a basis for further forecasting of the rheological properties at the mortar scale, incorporating the same W/C and adding the cement-sand volume ratio (C/S). Lastly, the practicality of the predictive model was assessed by comparing the forecasted outcomes to experimental results obtained from rotational rheometer.

• Korean journal of food and cookery science
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• v.11 no.5
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• pp.472-478
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• 1995

녹두가루와 전분의 일반성분 및 무기성분을 조사하고 녹두가루의 농도(4-8%,건량기준), 녹두전분의 농도(3-8%,건량기준)에 따른 호화 특성 및 리올로지특성을 비교하였다. 녹두가루의 일반성분은 수분 6.8%, 단백질 25.0%,지방 1.21%,회분 1.77%,비타민 B$_1$과 B$_2$는 각각 0.57과 0.11 mg/100 g이었다. 전분의 비타민 함량은 B$_1$이 0.002 mg/100 g, B$_2$가 0.02 mg/100 g이었다. 가루의 무기질함량은 칼슘이 374.9 mg/100 g으로 가장 높았고 인(353.0 mg/100 g), 칼륨(176.3 mg/100 g), 마그네슘(116.9 mg/100 g), 나트륨(107.6 mg/100 g) 순서이었다. 전분현탁액의 광투과도로 부터 예측한 전분의 호화온도는 67$^{\circ}C$이었다 녹두가루와전분의 팽윤력은 60-8$0^{\circ}C$의 가열온도에서 직선적으로 증가하였으며 그 정도는 전분이 가루보다 컸다. 용해도는 $65^{\circ}C$이후부터 증가하여 녹두 가루는 8$0^{\circ}C$까지 지속적으로 증가하였으나 전분은 7$0^{\circ}C$ 이후에는 완만하게 증가하였다 녹두가루는 농도가 증가함에 따라 아밀로그래프의 최고 점도가 증가하였으나 전분은 6-8%의 농도에서 최고점도를 나타내지 않았으며92.5$^{\circ}C$에서 15분간 유지하는 동안 점도는 지속적으로 증가하였다. 최고점도의 대수값과 농도는 직선적인 관계를 나타냈으며 동일한 최고점도를 나타내는 농도는 전분이 가루보다 2.6ft'3도 낮았다. 녹두가루(4-8%, 건량기준)와 전분(3-8%, 건량기준)현탁액을 95$^{\circ}C$에서 40분간 유지시켜 호화시킨 액을 6$0^{\circ}C$에서 측정한 결과, 항복응력과 점조 도지수는 농도가 증가함에 따라 커졌고 유동지수값은 1.0보다 작아 녹두가 루와 전분호화액은 항복응력을 가진 의가소성 유체의 성질을 나타내었다 동일한 점조도지수값을 나타내는 농도는 전분이 가루보다 약 1.3%정도 낮았다.

• Korean Journal of Food Science and Technology
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• v.20 no.6
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• pp.812-819
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• 1988

Rheological properties of rehydrated suspensions of freeze dried tomato ketchup were measured by Brabender Viscotron at the temperature range of $30-90^{\circ}C$, at the concentration of 15-50%, and at the shear rate of $0-250sec^{-1}$. At the shear rate of $0-210sec^{-1}$, tomato ketchup was found to be a thixotropic food product. The values of flow behavior index, consistency index and yield stress at the shear rate of $0-210sec^{-1}$, at the temperature of $30^{\circ}C$ and at the concentration of 33% , were 0.2131, 22.5047 $Pa\;sec^{-n}$, and 8.544 Pa, respectively. It was found that the apparent viscosity model for temperature was expressed by Andrade model and the model for concentration was expressed by Power model, and the model for both temperature and concentration was described by exponential and power models. The activation energies at the concentrations of 15, 20, 30, 33, 40, and 50% were 3.973, 4.985. 5.078, 5.226, 5.357, and 7.655 $kcal/g{\cdot}mole$, respectively.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.265-265
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• 2014

일반적으로 태양전지 및 반도체 공정에서 불순물 주입 과정인 도핑(Doping)공정은 크게 몇 가지 방법으로 구분해 볼 수 있다. 소성로(Furnace)를 이용하여 열을 통해 불순물을 웨이퍼 내부로 확산시키는 열확산 방법과 진공 챔버 내부에서 전자기장을 걸어 이온을 극도로 가속시켜 진행하는 이온 주입(Ion implantation)이나 이온 샤워(Ion shower)를 이용한 도핑 방법이 있다. 또한 최근 자외영역 파장의 레이저광을 조사하여 광화학 반응에 의해 도펀트 물질를 분해하는 동시에 조사 부분을 용해하여 불순물을 도포하는 기법인 레이져 도핑(Laser doping) 방법이 개발중이다. 그러나 레이져나 이온 도핑 공정기술은 고가의 복잡한 장비가 필요하여 매출 수익성 및 대량생산에 비효율적이며 이온 주입에 의한 박막의 손상을 치료하기 위한 후속 어닐링(Post-annealing) 과정이 요구되는 단점을 가지고 있고 열확산 도핑 방법은 정량적인 불순물 주입 제어가 어렵고 시간 대비 생산량의 한계가 있다. 반면 대기압 플라즈마로 도핑을 할 경우 기존에 진공개념을 벗어나 공정상에서 보다 저가의 생산을 가능케 할 뿐아니라 멀티 플라즈마 소스 개발로 이어진다면 시간적인 측면에서도 단연 단축시킬 수가 있어 보다 대량 생산 공정에 효과적이다. 따라서 본 연구에서는 새로운 도핑 방법인 대기압 플라즈마를 이용한 도핑 공정기술의 가능성을 제안하고자 도핑 공정 시 웨이퍼 내 전류 패스(Current path)에 대한 메카니즘을 연구하였다. 대기압 플라즈마 방전 시 전류가 웨이퍼 내부에 흐를 때 발생되는 열을 이용하여 도핑이 되는 형식이란 점을 가정하고 이 점에 대한 원리를 증명하고자 실험을 진행하였다. 실험 방식은 그라운드(Ground) 내 웨이퍼의 위치와 웨이퍼 내 방전 위치에 따라 적외선 화상(IR image: Infrared image) 화상을 서로 비교하였다. 적외선 화상은 실험 조건에 따라 화상 내 고온의 표식이 상이하게 변하는 경향성을 나타내었다. 이 고온의 표식이 전류 패스라는 점을 증명하고자 시뮬레이션을 통해 자기장의 전산모사를 한 결과 전류 패스의 수직 방향으로 자기장이 형성이 됨을 확인하였으며 이는 즉 웨이퍼 내부 전류 패스에 따라 도핑이 된다는 사실을 명백히 말해주는 것이며 전류 패스 제어의 가능성과 이에 따라 SE(Selective Emitter) 공정 분야 응용 가능성을 보여준다.

• Korean Journal of Materials Research
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• v.9 no.7
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• pp.663-669
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• 1999

Ag thick film conductors were fabricated with Ag powders having different degree of dispersion and glasses having different viscosity, and then the relationship between microstructure and electrical properties of the Ag films was investigated. Under the same processing condition. the Ag thick film that was prepared with the well-dispersed Ag powder and glass having low viscosity had denser microstructure and lower resistance than those of the film which was fabricated with the agglomerated Ag powder and glass having high viscosity It is believed to be due to the fast micro rearrangement kinetics when the well dispersed Ag powder was used, and all the microstructure development kinetics were impeded when low viscosity glass used. It was found that theme fast microstructure development kinetics resulted in the dense microstructure and the lower sheet resistance of the films. Also, the saturation time, at which at a given temperature no further decrease in the sheet resistance was obtained, was found to be shortened when well-dispersed Ag powder and low viscosity glass were used.

• Korean Journal of Food Science and Technology
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• v.17 no.3
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• pp.131-135
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• 1985

The rheological studies on dilute and concentrate solutions of naked and covered barley starches were carried out with various viscosimeters. The rheology of dilute solutions (0.05-0.3%) were characterized by intrinsic viscosity and related parameter according to Huggins equation. Also, the rheology of the solutions of higher concentrations (1-5%) were characterized by time dependent characteristics and pseudoplastic behaviors. The values of consistency index according to the power equation were exponen tially dependent upon concentration and temperature. The results showed that the rheological properties could differ greatly due to difference in varieties. The naked barley starch exhibited higher intrinsic viscosity, more thixotropic behavior and more dependence of consistency index on concentration and temperature than the covered barley starch.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.1
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• pp.75-81
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• 2003

Rheological properties of micronized full-fat soyflour (MFS ) milk were determined according to solid content, heat-treatment and type of coagulants. Heat-treated MFS milk showed a pseudoplastic flow pattern. The consistency and flow index of heated MFS milk was greatly affected by increasing the concentration of MFS and/or soy protein isolate (SPI). Apparent viscosity of MFS milk was gradually decreased by heating below 6$0^{\circ}C$, but was drastically increased by raising temperature further. Addition of coagulants and SPI resulted in dropping the temperature that allows to increase apparent viscosity drastically. A coagulant for MFS tofu was formulated based on the gelling Property of a single coagulant. The textural properties of MFS tofu were improved using 7.1% total protein fortified with SPI.