• 한국건설순환자원학회논문집
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• 제9권2호
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• pp.117-126
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• 2021

이 연구에서는 사면과의 부착력과 식물 생장력이 높은 식생기반재를 개발하고자, 시멘트 기반의 결합재와 기능성 첨가제를 혼합한 녹생토의 기초물성과 식물 생장에 미치는 영향을 평가하였다. 석고계 시멘트를 혼합한 녹생토(No.3)의 전단강도가 낮게 나타났으나, 식생 환경에 가장 적합한 경도 수준(23.6mm) 및 pH 값(7.4)을 나타냈다. 또한, 보습제를 첨가하여 성능을 개선한 녹생토의 초기 식생 발현은 일반 녹생토 비해 늦고 전도도값은 다소 높은 경향을 나타냈다. 반면, 성능을 개선한 녹생토는 타설면과의 부착력이 높았으며, 일정 시간 경과 후의 식물 생장 속도 및 동절기와 환절기 재생능력이 우월한 것으로 나타났다.

• Journal of Animal Science and Technology
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• 제64권5호
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• pp.950-969
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• 2022

This study aimed to determine the effect of dietary supplementation with Acremonium terricola culture (ATC) on the quality, conventional characteristics, and flavor substances of Hortobágy goose meat. A total of 720 one-day-old goslings were divided into four dietary treatments, each consisting of six cages of 30 goslings. The dietary conditions consisted of the control group and three treatment groups supplemented with 3, 5, or 7 g/kg ATC. In male geese, supplementation with 3 g/kg ATC elevated the crude ash (CA) content of the thigh muscle compared to the control group, and the CA content of the pectoralis major was significantly elevated when geese were supplemented with 5 g/kg ATC (p < 0.05). In females, compared with the control group, supplementation with 7 g/kg ATC enhanced the crude protein (CP) content of the pectoralis major. Supplementation with 7 g/kg ATC also increased the crude fat (CF) content of the pectoralis major in females as well as in both sexes; moreover, this supplementation dose increased the inosinic acid content of the thigh muscle in males and in both sexes. In contrast, supplementation with 5 g/kg ATC decreased the pH of the thigh muscle at 12 h postmortem (p < 0.01). No significant changes in meat color, water loss rate, shear force, moisture content or amino acid (AA) levels were observed after ATC supplementation (p > 0.05). Levels of saturated fatty acids (SFAs) and polyunsaturated FAs (PUFAs) in the pectoralis major and levels of SFAs, monounsaturated FAs (MUFAs), and PUFAs in the thigh muscle were not affected by the supplementation. Overall, ATC supplementation had positive effects on the pH, and CA, CP, CF, inosinic acid contents as well as on the FA composition of gosling meat. The optimal level of ATC supplementation was 7 g/kg in goslings from 1 to 70 days of age.

• Steel and Composite Structures
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• 제43권1호
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• pp.91-106
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• 2022

This paper has focused on presenting a three dimensional theory of elasticity for free vibration of 3D-graphene foam reinforced polymer matrix composites (GrF-PMC) cylindrical panels resting on two-parameter elastic foundations. The elastic foundation is considered as a Pasternak model with adding a Shear layer to the Winkler model. The porous graphene foams possessing 3D scaffold structures have been introduced into polymers for enhancing the overall stiffness of the composite structure. Also, 3D graphene foams can distribute uniformly or non-uniformly in the shell thickness direction. The effective Young's modulus, mass density and Poisson's ratio are predicted by the rule of mixture. Three complicated equations of motion for the panel under consideration are semi-analytically solved by using 2-D differential quadrature method. The fast rate of convergence and accuracy of the method are investigated through the different solved examples. Because of using two-dimensional generalized differential quadrature method, the present approach makes possible vibration analysis of cylindrical panels with two opposite axial edges simply supported and arbitrary boundary at the curved edges. It is explicated that 3D-GrF skeleton type and weight fraction can significantly affect the vibrational characteristics of GrF-PMC panel resting on two-parameter elastic foundations.

• 한국식품영양학회지
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• 제35권4호
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• pp.247-252
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• 2022

To improve the shelf-life of Centella asiatica, Centella asiatica was treated with gel packs containing slow-released chlorine dioxide (ClO₂) gas at 3-5 ppm for 20 days at 4℃. The weight loss rate, as well as the changes in pH, color, and texture of the treated samples, were investigated. The weight of the control and ClO₂ gas-treated samples was decreased during the storage period. The change in weight of the control was slightly faster than that of the samples treated with 3 and 4 ppm ClO₂ gas. The pH of the control and the ClO₂ gas treated samples were decreased during the storage period and there was no significant difference between the control and ClO₂ gas treated samples. Concerning color (lightness, redness, and yellowness) changes of Centella asiatica during the storage period, there was no significant difference between the control and ClO₂ gas treated samples. The change in shear force in the leaf and stem of Centella asiatica during the storage period was slightly lower in the 4 ppm ClO₂ gas treated samples (in the leaf) compared to the control and 3 and 4 ppm ClO₂ gas treated samples (in the stem) compared to the control and 5 ppm ClO₂ gas treated sample.

• Computers and Concrete
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• 제31권3호
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• pp.207-221
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• 2023

In this investigation, the interaction between opening space and neighboring joint has been examined by experimental test and Particle flow code in two dimension (PFC2D) simulation. Since, firs of all PFC was calibrated using Brazilian experimental test and uniaxial compression test. Secondly, diverse configurations of opening and neighboring joint were provided and tested by uniaxial test. 12 rectangular sample with dimension of 10 cm*10 cm was prepared from gypsum mixture. One quarter of tunnel and one and or two joint were drilled into the sample. Tunnel diameter was 5.5 cm. The angularities of joint in physical test were 0°, 45° and 90°. The angularities of joint in numerical simulation were 0°, 30°, 60°, -30°, -45°, -60° and its length were 2cm and 4cm. Loading rate was 0.016 m/s. Tensile strength of material was 4.5 MPa. Results shows that dominant type of crack which took place in the model was tensile cracks and or several shear bands develop within the model. The Final stress is minimum in the cases where oriented angle is negative. The failure stress decrease by decreasing the joint angle from 30° to 60°. In addition, the failure stress decrease by incrementing the joint angle from -30° to -60°. The failure stress was incremented by decreasing the number of notches. The failure stress was incremented by decreasing the joint length. The failure stress was incremented by decreasing the number of notches. Comparing experimental results and numerical one, showed that the failure stress is approximately identical in both conditions.

• 한국미생물·생명공학회지
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• 제17권4호
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• pp.397-402
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• 1989

Methylobacterium organophilum 이 탄소원과 에너지원으로서 메탄올로부터 생성하는 새로운 다당류계 생물고분자의 화학적 성질과 물성학적 성질을 관찰하였다. 분리정제한 다당류의 분자량은 약 4-5$\times$$10^6$ dalton 정도로 고분자량을 지니고 있다. 다당류의 화학적 조성은 건조중량의 66%가 탄수화물로 구성되어 있으며 이들의 88%가 환원당으로 구성되어 있다. 특이하게 본 고분자는 건조중량의 4.7%가 단백질로 구성되어 있다. 다당류는 glucose, galactose, 그리고 mannose을 몰비로 2:3:2 함유하고 있으며 탄수화물 이외에도 pyruvic acid, uronic acid, acetic acid 등을 함유하고 있다. 정제된 다당류를 증류수에 용해시켜 농도별로 점도를 측정한 결과 비뉴톤성 성질 중 pseudoplastic 성질을 보였으며 농도가 증가함에 따라서 겉보기점도 증가가 월등히 높았다. 동일한 1% 용액의 경우 K(consistency index)값을 비교하면 xanthan gum에 비해 약 10배정도 높은 18,000 cp 값을 나타내었다.

• 대한토목학회논문집
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• 제28권1C호
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• pp.41-51
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• 2008

본 논문은 말뚝 및 기초지반의 강성이 수평재하말뚝의 거동에 미치는 영향을 알아보고자 주문진 표준사와 김해점토를 기초지반으로 수평재하말뚝에 대한 실내실험을 실시하였다. 또한 실험 결과를 바탕으로 영향계수를 정량화 할 수 있는 경험식을 산정하였다. 말뚝과 지반의 강성을 고려하기 위하여 길이가 다른 3개의 알루미늄 모형말뚝을 제작하였으며 이를 사질토와 점성토 지반에 설치한 후 기초지반의 상대밀도(사질토 지반) 및 비배수전단강도(점성토 지반)를 변화시켜가며 수평재하 실내실험을 수행하였다. 실험을 통하여 산정된 p-y 곡선의 초기기울기는 사질토와 점성토 지반 모두에서 깊이와 말뚝-지반의 강성에 비례하였으나 점성토 지반의 경우 사질토 지반에 비하여 깊이에 따른 초기기울기의 증가율이 작은 경향을 나타내었다. 또한 극한 지반반력의 경우 모든 지반 조건에서 수평지반반력계수와 유사하게 깊이와 지반강성에 비례하여 증가하였으나 말뚝 강성에 대한 영향은 적게 나타났다. 이와 같은 특성을 고려하여 본 논문에서는 p-y 곡선의 초기기울기 산정 식을 실험결과와 가장 유사한 형태를 지니는 쌍곡선으로 지반 조건에 따라 제시하였으며 제안된 식을 기존의 연구 및 현장재하시험과 비교하여 제안 식의 적용성을 검증하였다.

• 한국식품저장유통학회지
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• 제30권3호
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• pp.405-418
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• 2023

The aim of this research was to study the feasibility of the defatted wheat germ flour (DWGF) alone or in combination with xanthan gum (XG) as egg yolk substitutes in mayonnaise formulation. In this research, DWGF was used at different levels (0, 25, 75 and 100%) alone or in combination with the XG (0.2%) as egg substitutes. The effects of these substitutions on the stability, textural and rheological characteristics of mayonnaise were investigated. According to the results, DWGF can be used as an egg yolk substitute in mayonnaise. Combining DWGF and XG as egg yolk substitute, improved the stability, textural and rheological properties. Mayonnaise with 100% egg yolk replacement showed the hardest structure, while the lowest firmness value was obtained in the control containing 100% egg yolk. Also, the highest adhesiveness value occurred in the sample with 100% DWGF. The thixotropic behavior was observed for all investigated mayonnaise samples over the all ranges of the studied shear rate (0.05-450/sec). Furthermore, the highest content of consistency coefficient value was observed in the sample with 100% DWGF and 0.2% XG. Therefore, it can be concluded that low-cholesterol mayonnaise with proper stability, textural and rheological characteristics are achievable by applying of the desirable combination of DWGF and XG.

• Earthquakes and Structures
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• 제26권3호
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• pp.239-249
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• 2024

A new layered shear continuum model box was developed to address the dynamic response issues of buried oil and gas pipelines under multi-point excitation. Vibration table tests were conducted to investigate the seismic response of buried pipelines and the surrounding soil under longitudinal multi-point excitation. A nonlinear model of the pipeline-soil interaction was established using ABAQUS finite element software for simulation and analysis. The seismic response characteristics of the pipeline and soil under longitudinal multi-point excitation were clarified through vibration table tests and simulation. The results showed good consistency between the simulation and tests. The acceleration of the soil and pipeline exhibited amplification effects at loading levels of 0.1 g and 0.2 g, which significantly reduced at loading levels of 0.4 g and 0.62 g. The peak acceleration increased with increasing loading levels, and the peak frequency was in the low-frequency range of 0 Hz to 10 Hz. The amplitude in the frequency range of 10 Hz to 50 Hz showed a significant decreasing trend. The displacement peak curve of the soil increased with the loading level, and the nonlinearity of the soil resulted in a slower growth rate of displacement. The strain curve of the pipeline exhibited a parabolic shape, with the strain in the middle of the pipeline about 3 to 3.5 times larger than that on both sides. This study provides an effective theoretical basis and test basis for improving the seismic resistance of buried oil and gas pipelines.

• 한국세라믹학회지
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• 제41권5호
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• pp.395-400
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• 2004

세라믹 사출성형시 결합체의 조성에 따른 혼합물의 유동학적 특성과 제조조건에 따른 시편의 결함 생성 및 탈지공정에 대하여 조사하였다. 2wt%의 stearic acid를 코팅한 세라믹 분말(65wt% $Al_{2}O_{3}$ㆍ35 wt% 장석)에 결합체로 15,20 및 25wt%의 Paraffin Wax (PW)와 High Density Polyethylene(HDPE)을 첨가하여 $160^{\circ}C$에서 2시간 혼합하였다. Capillary rheometer로 측정한 혼합물의 겉보기 점도는 shear rate가 $1000s_{-1}$일 때 80~300Pa.s로 사출성형에 적합한 유동성을 나타내었으며, 결합제의 조성에 의존하였다. 결합제의 조성이 15H5P5(총 15wt%의 결합체중, HDPE/PW 비=5:5)인 사출성형 시편은 사출압력과 관계없이 short shot가 생성되었으나, 사출압력이 45kgf/$cm^{2}$인 10H5P5 사출성형 시편은 결함이 관찰되지 않았다. 사출성형 시편 중의 pw를 $70^{\circ}C$의 n-heptane 용매에서 5시간동안 침지하여 제거한 후, $450^{\circ}C$에서 5시간 열처리하여 HDPE를 제거하였다. PW의 추출에 의해 형성된 연속기공을 통하여 HDPE의 효과적인 제거와 기계적 강도의 손상없이 사출성형이 가능한 결합체 조성은 20H5P5이었다. $1300^{\circ}C$에서 5시간 소결한 20H5P5 시편의 부피비중은 2.8, 기공률은 3% 이하 및 3점곡강도는 약 2,400kgf/$cm^{2}$으로 구조용 재료로서 사용이 가능하였다.