• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 추계 학술발표회 제20권2호
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• pp.821-824
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• 2008

This paper presents a systematic approach for estimating material performance of concrete mixture design based on satisfaction curves developed from statistical evaluation of existing or newly obtained material property related data. In performance based material design (PBMD) method, concrete material used for construction of a structure is designed considering a structure's specified performance requirements based on its usage and characteristics such as environmental conditions, structure types, expected design life, etc.Satisfaction curves express the probabilities that one component of substrates (i.e., aggregate size, cement content, etc) of concrete mixture will sustain different criterion value for a given concrete mixture design. This study presents a statistical analysis method for setting up concrete material parameter versus concrete criterion relationships in the form of satisfaction curves and for estimating confidence bounds on these satisfaction curves. This paper also presents an analysis method to combine multiple satisfaction curves to form one unique satisfaction curve that can relate the performance of concrete to a single evaluating value. Based on several evaluated mixture design examples for various material properties, the validity of the proposed method is discussed in detail.

• 한국축산식품학회지
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• 제33권4호
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• pp.549-554
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• 2013

Food safety is important issue for consumers and recently the usage of food ingredients especially food preservatives are limited by regulations. However, some manufacturers use food preservatives instead of improving their hygienic production. Therefore, the levels of sodium benzoate and potassium sorbate of 147 vacuum packaged Kashar (fresh) cheese samples produced in Black Sea Region, Turkey were investigated and some microbiological properties were determined. Research results demonstrated that the production of vacuumed Kashar cheese in Black Sea Region was not standardized for all production periods depending on the microbiological properties. Coliform and E. coli counts detected in the cheese samples showed that necessary hygienic conditions were not provided for Kashar cheese production. Staphylococcus aureus was not determined in the cheese samples. The sodium benzoate and potassium sorbate were analyzed by HPLC-DAD. Potassium sorbate levels (69.39 mg/kg) of Kashar cheese samples were determined to be lower than the maximum permitted concentration of Turkish Food Codex. Although the utilization of sodium benzoate is prohibited by the Codex, the average level of sodium benzoate of cheese samples was detected to be 68.63 mg/kg. Sodium benzoate can be naturally occurred in fresh cheese at concentrations of up to 50 mg/kg.

• 콘크리트학회논문집
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• 제13권2호
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• pp.184-191
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• 2001

최근 급속한 산업화 및 생활수준의 향상에 따라 폐유리의 발생량이 급격히 증대하고 있으며 이중 대부분은 재활용되지 못하고 최종처분 되고 있어 심각한 자원낭비 및 환경오염문제를 야기하고 있다. 따라서 본 연구에서는 국내에서 발생되고 있는 폐유리중 대표적인 갈색, 녹색, 무색 폐유리 및 이들을 혼합한 폐유리를 파쇄하여 콘크리트용 잔골재로서의 재활용 가능성을 분석하기 위한 기초적 실험연구를 수행하였다. 시험결과 슬럼프 및 다짐계수는 폐유리 잔골재의 입형이 모가나고 각이져 있고 상대적으로 유리입도가 잔골재보다 크기때문에 감소하였으며, 공기량은 폐유리 잔골재가 0.6mm이상의 입자를 많이 함유하고 있어 증가하는 것으로 나타났다. 또한 압축강도, 인장강도, 휨강도는 폐유리 잔골재의 혼입량이 많아질수록 감소하였으며, 적정 혼입률은 30% 이하가 바람직하고 유동성 확보를 위해서는 적정한 혼화제를 사용해야 한다는 결론을 얻을 수 있었다.

• Journal of Forest and Environmental Science
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• 제36권3호
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• pp.219-224
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• 2020

Urea formaldehyde resins are widely used in the manufacturing of wood composite and their usage is always combined with release of formaldehyde characterized to be hazardous to health during and after the manufacturing of the products. This study investigates the effectiveness of wood-based adhesive from oil of pyrolysed Triplochiton scleroxylon sawdust for the production of composite board. The wood-derived Pyrolytic Oil (PyO) was blended with Urea Formaldehyde (UF) resin to formed Pyrolytic Oil-Urea Formaldehyde (PyOUF). The obtained PyOUF called Wood-Based Adhesives at four blends and control (UF) viz; 1:1, 1:2, 1:3, 2:1, 1:3 were further employed to prepare the composite board and test for their bonding strength by physical (water absorption-WA and thickness swelling-Th.S) and mechanical properties (modulus of elasticity-MOE, modulus of rupture-MOR, and impact bending-IB). Data obtained was analysed using analysis of variance at α 0.05. The result of analysis of variance conducted on physical properties show significant difference (p≤0.05) between the WA values obtained when testing the different blending proportion of PyOUF and likewise between 2 and 24 h of immersion. PyOUF had significant effect (p≤0.05) on Th. S for 24 h but no significant different (p>0.05) for the 2 h period of soaking. The analysis of variance on mechanical properties of the composite board (MOE, MOR, and IB) show significance differences (p≤0.05) between the strength values obtained when testing the different ratios of PyO with UF. PyO content influenced the properties of the boards and it is evident that PyO can be used in the manufacture of composite board.

• 대한한의학원전학회지
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• 제37권2호
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• pp.77-99
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• 2024

Objectives : This study examined the possibility of therapeutic application of natural pigments in the Joseon Period other than aesthetic purposes. Methods : The medicinal properties of natural pigments as written in the texts Sangayorok, Gyuhapchongseo, Imwongyeongjeji were searched and analyzed in the texts Bencaogangmu, Encyclopedia of Eastern Medicine, and the Encyclopedia of Chinese Medicinals focusing on their Qi, flavor, effects and application. Of the conditions they treated, we examined whether they treated skin conditions using external application. The Korean Medical effects of these pigments were examined based on the content of the skin chapter of the Donguibogam. Results : We were able to extract 47 kinds of natural pigments, most of which had cold nature and bitter tasting properties. In addition, most of the pigments had the effect of treating skin conditions, illnesses due to micro-organisms, and of detoxifying. Conclusions : After consideration of medicinal properties and effects of the herbs that were used as pigments in the Joseon period, it could be concluded that as these herbs not only function as pigments but also hold properties that prevent skin conditions, their therapeutic functions could have been considered when using them as pigments.

• 한국식품영양학회지
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• 제19권4호
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• pp.515-525
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• 2006

Survey was done to total 250 people to analyze characteristics of water quality in 5 widely used mineral water springs-(Teajosan(a), Leechungmukong(b), Onju(c), Yeongin(d), Crown(e))-in Chung-nam area and local mineral water usage. And the content of mineral and physico-chemical properties were compared in 5 sites. The largest users of mineral water spring was $40{\sim}50's$ of ages. Among those mineral water spring users, 52.5% had regular dietary habit and 32% showed improvement in lift habit after using mineral water spring. The mineral water spring users were engaged in student, housewife, professional, self-employed, etc. Those who were highly interested in health were likely to use mineral spring water more often regardless of age and occupation. Five mineral water springs differed in contents of mineral. The average content of minerals was $Ca\;28.5mg/{\ell},\;K\;1.5mg/{\ell},\;Mg\;5.3mg/{\ell},\;Na\;14.3mg/{\ell}$. 'K index' was an indicator of healthy water, and 'O index' was an indicator of tasty water. According to K indek and O index, waters of a b, c and e area were classified as 'tasty and healthy water', and water of e area had the highest values in both K and O index d area was classified as 'tasty water.'

• 한국식품영양과학회지
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• 제46권1호
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• pp.140-145
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• 2017

본 연구에서는 식품으로 활용하기 위해 제조된 잣송이 추출물의 이화학적 품질 특성과 항산화 활성을 탐색하였다. 잣송이 추출물은 수분과 탄수화물이 구성성분 대부분을 차지하고 있었으며, 특히 대조군으로 사용된 매실 추출물보다 수분함량은 낮고 당 함량은 높아 유의적으로 높은 점도를 나타내었다. 또한, 갈색도와 색도는 모두 낮아 매실 추출물과 비교해 숙성 중 Maillard 갈변 반응의 정도가 상대적으로 낮았음을 시사해주었다. 잣송이 추출물은 매실 추출물보다 플라보노이드 함량은 유의적으로 다르지 않았으나 유기산 함량과 갈변도는 1/10 수준으로 유의적으로 낮았고, 총환원력은 매실 추출물의 60% 수준으로 측정되었다. 그런데도 잣송이 추출물에서 매실 추출물과 유사한 높은 금속 소거능과 라디칼 소거 활성이 관찰되었다. 또한, 잣송이 추출물 속 플라보노이드 총량보다도 많은 양인 6.6 mM quercetin과 비교할 때 2배나 높은 SOD 유사 활성을 나타내었다. 이는 잣송이 추출물에 quercetin보다 항산화 활성이 높은 플라보노이드가 존재할 가능성을 보여주며, 플라보노이드 조성에 대한 후속연구의 필요성을 시사해주었다. 본 연구는 잣송이 추출물이 제조법과 용도가 유사한 매실 추출물에 버금가는 항산화 활성을 부여하면서도 상대적으로 높은 당 함량과 낮은 유기산 함량으로 매실 추출물과는 관능적 측면에서 차별화될 수 있는 식품으로서의 활용 가능성을 보여주었다.

• Tribology and Lubricants
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• 제36권2호
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• pp.88-95
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• 2020

In this study, we investigate the mechanical properties of high manganese steel, and the friction and wear characteristics of brake friction material containing this steel, for passenger car application, with the aim of replacing copper and copper alloys whose usage is expected to be restricted in the future. These steels are prepared using a vacuum induction melting furnace to produce binary and ternary alloys. The hardness and tensile strength of the high manganese steel decrease and the elongation increases with increase in manganese content. This material exhibits high values of hardness, tensile strength, and elongation; these properties are similar to those of 7-3 brass used in conventional friction materials. We fabricate high manganese steel fibers to prepare test pad specimens, and evaluate the friction and wear characteristics by simulating various braking conditions using a 1/5 scale dynamometer. The brake pad material is found to have excellent friction stability in comparison with conventional friction materials that use 7-3 brass fibers; particularly, the friction stability at high temperature is significantly improved. Additionally, we evaluate the wear using a wear test method that simulates the braking conditions in Europe. It is found that the amount of wear of the brake pad is the same as that in the case of the conventional friction material, and that the amount of wear of the cast iron disc is reduced by approximately 10. The high manganese steel is expected to be useful in the development of eco-friendly, copper-free friction material.

• 한국도로학회논문집
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• 제19권2호
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• pp.17-24
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• 2017

PURPOSES : This study aims to develop a sealant for use in the installation of Weigh-In-Motion (WIM) sensor for asphalt concrete or cement concrete pavements. METHODS : In order to investigate the properties of various sealants that were mixed with latex and carbon fiber, various test methods were adopted, such as bituminous bond strength test, softening point test, and cone penetration test. To evaluate moisture susceptibility, the BBS test was conducted under moist condition. The bond strength ratio (BSR) was calculated based on tensile strength ratio method. RESULTS : The sealant's properties significantly varied according to the amount of latex or carbon fiber. The usage of latex marginally enhanced the cone penetration test result, notwithstanding reduced asphalt content. This implies that the sealant will be proper cold temperature reason. Moreover, the addition of latex and carbon fiber evidently increased the softening point. This indicates that the tendency of the material to flow at elevated temperatures is encountered during service. With the addition of latex and carbon fiber, the moisture susceptibility measured with BSR improved marginally, while the bond strength under dry condition decreased marginally. Sealant F displays the highest bond strength and BSR under limited test conditions. CONCLUSIONS : According to the proportion of latex and carbon fiber mixed, properties of sealant, such as softening point, cone penetration, and BSR varied marginally. This indicates that the sealant has to be applied considering the environmental condition, to improve service life.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2009년도 춘계 학술대회 제21권1호
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• pp.423-424
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• 2009

최근 자원의 재활용 및 알칼리-골재반응의 대책으로 F/a의 사용이 증가하는 추세이다. 그러나 F/a 치환량 증가에 따른 미연소탄소의 AE제 흡착으로 인하여 공기연행성능이 저하되어, 동결융해 작용에 의한 내구성 저하의 위험성이 고조되고 있다. 따라서 본 연구에서는 F/a 치환량 및 AE제 종류변화에 따른 굳지 않은 콘크리트의 공기연행성능을 분석함으로써 F/a를 다량 사용한 콘크리트의 기포안정성 향상을 위한 기초자료로 제시하고자 한다.