• 한국항공우주학회지
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• 제41권8호
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• pp.597-604
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• 2013

본 논문에서는 열분해 및 삭마 환경의 복합재 구조물에 대한 열기계적 연계 해석을 수행하였다. 열분해 과정의 재료 밀도 감소, 기공 가스 확산, 흡열 반응 에너지와 삭마 과정에서의 표면 침식 효과 등을 고려하였다. 상용 유한요소 코드에 교차 연계 알고리듬을 적용하여 완전 연계된 열 해석 및 구조 해석 인터페이스를 구성하였다. 수치 실험을 통해서 탄소/페놀릭 복합재료의 기본적인 열분해 및 삭마 특성을 분석하였다. 특히, 화학적 및 기계적 삭마에 영향을 미치는 주요 인자에 따른 표면 침식량 등을 비교하였다. 또한, 열분해 과정의 수축 또는 팽창 변형도가 재료의 열기계적 거동에 미치는 영향도 검토하였다.

• 펄프종이기술
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• 제38권4호
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• pp.17-23
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• 2006

Paper has fibers and fines network structure and it is strongly affected by interface bond-ing between fibers. Paper structural properties can be determined depending on the inter-fiber bonding. Fines play an important role in Campbell and consolidation effect through wet pressing and drying operations. The fines are essential for the formation of bonds between fibers and for the improvement of strength properties of papers. Since the fines are components of the pulp, there are always two factors to be considered: the quality and quantity of the fines. The quality of fines might be a potential variable to give a more accurate picture of the papermaking potential of the pulp. The object of this study is to investigate the effect of different types of pulp fines on the properties of paper and to access the potential of fines for controlling the bulk of paper. Refined Sw-BKP, Hw-BKP and BCTMP fines were used to investigate the fines effect. Wet-web strength, breaking length, scattering coefficient, and hydrodynamic specific volume, and drying shrinkage were measured. According to the results, chemical and morphological compositions of fines do not strongly affect to wet-web forming by their similar Campbell effect, but strongly affect to drying operation which forms hydrogen bonding among fiber-fines-fiber matrixes. Paper bulk should be controlled by the extent of hydrogen bonding between fibers during drying operation.

• Elastomers and Composites
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• 제36권4호
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• pp.268-277
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• 2001

PPG, PEG, trimethylolpropane(TMP) 등의 폴리올에 MDI(4,4'-diphenyl methane diisocyanate)를 각각 혼합하고 경화시켜 여러가지 물성을 측정하였다. 경화시간은 PEG와 TMP의 함량이 늘어날수록 짧게 나타났고 분자량의 효과보다는 관능기의 수에 더 큰 영향을 받았다. NCO-OH 반응은 NCO-NCO반응보다 활성적이고 빠르게 일어났다. 경도는 가교밀도와 분자구조의 영향을 받았으며 NCO-NCO 반응으로 생긴 도막은 취약하였고 NCO-OH간의 반응으로 생긴 도막은 유연하였다. 부착력은 결정화도와 수축율이 클수록 낮은 값을 나타내었으며 TMP 함량이 증량될수록 높은 값을 나타내었다. 난연성은 난연제의 종류와 함량에 영향을 받았으며 난연효과는 IXOL B-251이 가장 우수하였고 TCCP는 수지와의 상용성이 좋지 않아 부분적으로 분리되었다.

• Composites Research
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• 제17권6호
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• pp.37-43
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• 2004

경화제의 사슬길이와 화학구조 차이가 반응특성, 열적, 기계적특성에 미치는 영향을 조사하기 위하여 선형구조를 가지고 양쪽 막단기에 에폭시기를 갖는 범용 에폭시수지인 DCEBF를 양쪽 관능기가 동일하고 주쇄의 사슬길이가 서로 다른 선형아민 경화제인 EDA와 HMDA로 각자 1:1 당량비로 혼합하여 예비 및 후 경화조건으로 경화하였다. 그 결과, 수지 경화물의 특성은 경화제 주쇄의 탄소원자수에 따라 큰 영향을 받는 것으로 밝혀졌다. 즉, 주쇄의 길이가 짧은 EDA 경화계는 길이가 긴 HMDA 경화계보다 열안정성, 밀도, 부피수축(%), 유리전이온도, 인장탄성률 및 인장강도, 굴곡탄성률 및 굴곡강도의 값이 높게 나타났고, 반면에 최대발열온도, 에폭시기의 전환률, 선팽창계수의 값은 낮게 나타났다. 이는 주쇄의 탄소원자수 2개를 가지는 EDA가 3차원 망목상 공간구조 형성과정에서 packing capability가 우수하여 rigid한 특성을 가지기 때문이다. 굴곡 파단 특성은 굴곡탄성률과 굴곡강도와 밀접한 관계를 나타내었다.

• 한국축산식품학회지
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• 제35권3호
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• pp.370-381
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• 2015

This study was designed to determine the usability of lemon fiber (LF-2%, 4%, 6%) and carrot fiber (CF-2%, 4%, 6%) to produce lowfat beef hamburgers. To that end, a certain amount of fat was replaced with each fiber. The proximate composition, pH value, cholesterol content, cooking characteristics, color, texture profile, and sensory properties of low-fat beef hamburgers were investigated. LF increased moisture content and cooking yield due to its better water binding properties, while CF caused higher fat and cholesterol contents owing to its higher fat absorption capacity (p<0.05). LF resulted in a lighter, redder, and more yellow color (p<0.05). Hardness, gumminess, springiness, and chewiness parameters decreased when the usage level of both fibers increased (p<0.05). However, more tender, gummy, springy, and smoother hamburgers were produced by the addition of CF in comparison with LF (p<0.05). Moreover, hamburgers including CF were rated with higher sensory scores (p<0.05). In conclusion, LF demonstrated better technological results in terms of cooking yield, shrinkage, moisture retention, and fat retention. However it is suggested that CF produces better low-fat hamburgers since up to 2% CF presented sensory and textural properties similar to those of regular hamburgers.

• 콘크리트학회지
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• 제9권1호
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• pp.115-121
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• 1997

본 연구는 NaCl 수용액 중에서 고로 슬래그미분말의 알칼리실리카반응에 대한 팽창억제 특성 및 그의 메카니즘에 관한 것이다. 실험에 사용된 NaCl 수용액의 농도는 0%(수도수), 2.8% 및 20%였으며, 골재는 안산암을 사용하였다. 슬래그는 비표면적이 $4,100cm^2/g.\;5,960cm^2/g$ 및 $7,950cm^2/g$인 3종류를 사용하였고 치환율은 시멘트중량에 대하여 40%, 60%, 70% 및 80%로 하였다. NaCl 수용액에 있어서 슬래그를 첨가한 공시체는 치환율이 많을수록 수축률은 높게 되었고 그의 값은 비표면적이 클수록 높게 나타났다. 슬래그에 의한 알카리실리카반응의 유해한 팽창의 억제는 슬래그의 첨가에 의한 경화 콘크리트의 화학적 수축에 의해서도 달성됨이 확인되었다.

• 한국주조공학회지
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• 제14권5호
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• pp.471-479
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• 1994

Al-2%Si-2%Mg alloy containing SiC particle in 20, $70{\mu}m$ were prepared by mean of squeeze casting with various pressure 50, 100, 150 and 220MPa respectively. The specimens were made by casting into $50{\Phi}{\times}100{\ell}$ mold under various squeeze conditions(pressures, pressurizing temperature, particle sizes). Mechanical properties(hardness, tensile strength, elongation and wear characteristics) were evaluated at room temperature with those various fabrication factors. It became feasible to make favorable Al-SiCp composite free from casting defects by the injection of Ar gas during melting and 100MPa pressure squeeze casting. However, pressure of 50MPa was not sufficient to avoid completely porosity formation as a result of precessing and shrinkage during solidification. As the particle size is smaller and the squeeze pressure is higher, the hardness and tensile strength at room temperature are higher. Cell size became smaller gradually with increase of squeeze pressure. With increase of squeeze pressure(MPa), wear behaviors of those composites were changed from adhesive into abrasive wear, and the tendency of above behavior became outstanding with increasing sliding speed. The chemical reaction(4Al＋3SiC${\rightarrow}$$Al_4C_3+3Si$) is more accelerated at interface between SiCp and matrix with increase of squeeze pressure. Therefore $Al_4C_3$ intercompound and Si peak intensity is increased at interface.

• Journal of Nutrition and Health
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• 제9권2호
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• pp.24-39
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• 1976

The present study was undertaken to investigate the metabolic problems of high carbohydrate and cellulose diets of Korean. Forty males and same number of females of Albino rats, aged $45{\pm}5$days were divided into 95% high carbohydrate (H. CHO)group, 83.8% medium carbohydrate (M. CHO)group, 50% low carbohydrate (L. CHO) group and standard (Stand). group containing 72.2% sugar. Each group was divided into two again-1.55% cellulose group and non-cellulose group, 10 rats each of eight groups in both sexes. Cellulose was added to each of non-cellulose diets in the forms of spinach powder and rice bran. After 14 weeks the rats were sacrificed for chemical analysis and the results were elucidated as follows. (1) H. CHO+Cell. group showed the lowest value in body weight gained and shrinkage of almost all organs, in contrast with this group the L.CHO group showed higher body weight gained than Stand. group. M. CHO+Cell, group showed much the same body weight gained curve as Stand. group. (2) It was observed that cellulose group showed lower F.E.R and P.E.R value than non-cellulose group comparatively. (3) Total nitrogen retention and retention rate were decreaced in H. CHP groups compared with M. CHO or L. CHO groups. (4) The amount of feces was increased due to addition of cellulose to experimental diets and in accordance with the increasing total fecal excretion of nitrogen and glucose was also increased, especially noticeable in fecal glucose excretion. (5) It was noteworthy that serum cholesterol level was decreased due to addition of cellulose in H. CHO group and L. CHO group. (6) M. CHO+Cell. group was designed to reflect the average survey data of Korean diets and there was no significant differences on body weight gained, F.E.R, P.E.R, total nitrogen retention and hematology between M. CHO+Cell. and Stand. group. Total glucose excretion was increased due to dietary cellulose in M. CHO+Cell. group, but it seemed to be no metabolic problems in this group.

• 한국구조물진단유지관리공학회 논문집
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• 제21권4호
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• pp.124-131
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• 2017

본 연구는 저온환경에서 경화가 가능한 알루미나시멘트 및 아질산염을 사용한 보수용 시멘트 모르타르의 기초성능을 평가하고자 하였다. 이를 위해 국내 건설현장에서 사용되고 있는 보수용 모르타르를 조사 및 선정하였으며, 이를 대상으로 알루미나시멘트, 아질산염을 치환하여 혼입량 조절에 따른 실험평가를 실시하였다. 그 결과, 알루미나시멘트, 아질산염을 보수용 모르타르에 치환하여 사용할 경우 초기 강도발현이 증진되었다. 또한 내화학성이 개선되었고 수축거동이 감소하였으며 동결융해에 대한 저항성이 증대되었다. 알루미나시멘트와 아질산염을 2:1의 비율로 7.5% 치환하여 외부구조물에 시공한 결과 표면상태가 5개월 이상 양호하게 유지되었으며, 실제 외부구조물에 사용성이 우수한 것으로 판단된다.

• Asian-Australasian Journal of Animal Sciences
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• 제17권4호
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• pp.564-568
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• 2004

Restructuring had made it possible to utilize lower value cuts and meat trimmings from spent animals by providing convenience in product preparation besides enhancing tenderness, palatability and value. Milk co-precipitates (MCP) have been reported to improve the nutritional and functional properties of certain meat products. This study was undertaken to evaluate the influence of incorporation of milk co-precipitates at four different levels viz. 0, 10, 15 and 20% on the quality of restructured buffalo meat blocks. Low-calcium milk co-precipitates were prepared from skim milk by heat and salt coagulation of milk proteins. Meat chunks were mixed with the curing ingredients and chilled water in a Hobart mixer for 5 minutes, followed by addition of milk co-precipitates along with condiments and spice mix and again mixed for 5 minutes. Treated chunks were stuffed in aluminium moulds and cooked in steam without pressure for 1.5 h. After cooking, treated meat blocks were compared for different physico-chemical and sensory attributes. Meat blocks incorporated with 10% MCP were significantly better (p<0.05) than those incorporated with 0, 15 and 20% MCP in cooking yield, percent shrinkage and moisture retention. Sensory scores were also marginally higher for meat blocks incorporated with 10% MCP than product incorporated with 15 and 20% MCP, besides being significantly higher than control. On the basis of above results 10% MCP was considered optimum for the preparation of restructured buffalo meat blocks. Instrumental texture profile analysis revealed that meat blocks incorporated with 10% MCP were significantly better (p<0.05) in hardness/ firmness than control although, no significant (p>0.05) differences were observed in cohesiveness, springiness, gumminess and chewiness of both type of samples.