• Advances in concrete construction
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• 제9권2호
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• pp.217-225
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• 2020

The recovery of waste proves a solution with two impacts: the environmental impact by the reduction of pollution and the gain of the occupied space by this waste, and the economic impact by the use of these lasts in the building and in the area of public works. The present research consists in recovering a waste marble (thrown powder exposed to the different meteorological phenomena) generated by the quarry marble of Fil-fila, located at the east side of Skikda in the north-east of Algeria, and add it, as sand in the composition of sand concrete. To carry out this research, we analyzed the evolution brought by the substitution of ordinary sand by marble waste sand, with 25%, 50%, 75% and 100% on the properties in the fresh state (density, workability and air content) and in the cured state (compressive strength, tensile strength, surface hardness and sound velocity). For durability we tested water absorption by immersion and chloride penetration. The results obtained are compared with control samples of 0% of substitution rate. In order to have a good filling of the voids in the granular skeleton; we added a quantity of limestone recycled fines from the quarries and for a good workability a super-plasticizing additive. The results showed that the partial substitution modified both the fresh and the hardened characteristics of the tested concretes, the durability parameters also improved.

• KIEAE Journal
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• 제7권5호
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• pp.135-142
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• 2007

This is an experimental study on the structural characteristics of reinforced concrete beams using of the oyster shells as a substitute fine aggregate of concrete. In this study, the main factors consist of the grain sizes and the percentage of substitution of oyster shells to fine aggregate in the equal water cement ratio. The results of the study showed as followed. The initial load value of them represented similar constant within 10% of the maximum load value in each test beam. But the maximum load value and the ultimate load value decreased with increased grain size and the rate of substitution. As the grain size of oyster shells became smaller, the load values of them were somewhat higher. The deflection among deformation properties of reinforced concrete beams with oyster shells represented typical curves like that of normal reinforced concrete. In the deformation of steel and concrete, the deformation was proportionated to the load till yield point and from yield point until approaching the ultimate load point. One type was typical curve of the load and the deformation and the other type irregularly was changed to very small deformation for the load increase centering around load axis. After the analyzing structural behaviors and the properties of reinforced concrete test beams with oyster shells, the most excellent grain size of oyster shells represented 1.0mm and less or 5.0mm and less with taking uniformly, and the percentage of practicable substitution of them to fine aggregate was about 30%.

• 비파괴검사학회지
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• 제24권1호
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• pp.29-37
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• 2004

22Cr-5Ni 2상 스테인리스강의 합금원소 중 몰리브덴(Mo) 원소를 텅스텐(W)으로 치환하여 크리프거동에 미치는 영향을 조사하였다. 그리프시험은 $600^{\circ}C$와 $650^{\circ}C$의 온도에서 실시하였다. $650^{\circ}C$ 크리프 시에는 취약한 금속간화합물인 ${\sigma}$상이 석출하였으며 이것은 크리프수명을 급격히 감소시키는 역할을 하였다. Mo에 대한 W원소의 치환은 일반적으로 ${\sigma}$상의 석출을 지연시킨다고 알려져 있으나, 2wt.%까지 W 치환을 실시한 본 연구범위에서는 크리프 수명 및 최소 크리프속도에 뚜렷한 영향을 미치지 못하였다. 크리프손상의 정도를 평가하기 위하여 크리프시편에 대한 초음파검사를 실시하였다 크리프온도 $600^{\circ}C$에서는 크리프시편의 수명이 증가함에 따라 음속이 비례적으로 증가하였으나 $650^{\circ}C$에서는 반대로 감소하였다.

• 한국정보과학회논문지:소프트웨어및응용
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• 제34권7호
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• pp.595-602
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• 2007

본 논문에서는 미지의 아미노산 서열이 신호 펩티다제 I에 의해 절단되는 분비성 단백질인지를 판별하고, 분비성 단백질일 경우에는 절단 위치를 예측하는 방법을 제안한다. 아미노산의 소수성을 이용한 전처리를 수행하여 분비성 단백질의 선도서열인 신호서열의 존재와 절단 위치를 추정한다. 전처리를 통해서 신호서열 아닌 서열을 초기에 제외함으로써 신호서열 예측의 정확도를 높인다. 지지벡터기계를 신호서열의 예측에 효과적으로 적용하기 위해서, 생물학적 정보와 관련된 아미노산 서열간의 거리를 제안한다. 아미노산의 세포내 위치를 예측할 수 있는 소수성 척도와 아미노산의 진화적인 관계를 나타낼 수 있는 치환행렬을 이용하여 아미노산 서열간의 거리를 정의한다. Swiss-Prot release 50 단백질 자료에 대하여 교차타당성 기법을 사용하여 실험한 결과 제안한 방법은 신호서열중에 98.9%를 신호서열로 판별하였고, 88%의 절단위치 예측정확도를 보였다. 기존의 방법과의 비교실험을 통해서 제안한 방법이 신호서열의 예측에 더욱 효과적임을 확인하였다.

• 분석과학
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• 제17권5호
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• pp.375-380
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• 2004

고진공 및 고압장치를 이용하여 온도와 압력변화에 따른 친핵성치환반응을 속도론적으로 연구하여, 속도상수와 활성화파라미터 및 Hammett ${\rho}$값을 구하였다. ${\Delta}V^{\ddag}$, ${\Delta}{\beta}^{\ddag}$ 및 ${\Delta}S^{\ddag}$는 모두 음의 값을 나타내었으며, 모든 압력 조건에서 친핵체의 치환기효과 ${\rho}x$는 음의 값을 나타내었다. 압력이 증가함에 따라 반응속도는 증가하였으며, 진공상태에서의 반응속도는 다소 감소함을 알 수 있었으며, 반응은 $S_N2$ 반응메카니즘을 따름을 알 수 있었다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2018년도 추계 학술논문 발표대회
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• pp.40-41
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• 2018

The purpose of this study is to compare the amount of critical chloride of rebar embedded in concrete according to the substitution rate of admixture. In order to determine the starting point of corrosion of rebar, electrodes were embedded in concrete, chloride was supplied, and OCP of rebar was observed in real time. The amount of the contaminants in the concrete surrounding the rebar was judged to be the critical corrosion chloride contents of the rebar at the start of the corrosion. As a result of the comparative evaluation, it was confirmed that the critical chloride contents of the rebar decreased with increasing the substitution ratio of the admixture.

• Bulletin of the Korean Chemical Society
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• 제31권10호
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• pp.2801-2805
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• 2010

A nucleophilic substitution reaction of 4-chloro-7-nitrobenzofurazan (NBF-Cl) with anilines in MeOH-MeCN mixtures was conducted at 25, 35, and $45^{\circ}C$. Based on the higher $\beta_{nuc}$ values (1.0 - 1.6) of the reaction and a good correlation of the rate constants with the reduction potentials of the aniline nucleophiles, the present reaction was initiated by a single electron transfer (SET). After this step, the reaction proceeds through a transition state similar to the normal $S_NAr$-Ad.E pathway.

• Mycobiology
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• 제33권2호
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• pp.109-112
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• 2005

The internal transcribed spacer (ITS) regions including the 3'-end of 18S rRNA gene, 5.8S rRNA gene and the 5'-end of the 28S rRNA gene of Rhizopus spp. were amplified by PCR and analyzed by DNASIS program. Length polymorphism of these region ranged from 564 bp in R. oryzae to 789bp in R. stolonifer. The length and sequence of 5.8S was very conserved with $154{\sim}155\;bp$. The sequence of ITS2 was more variable than that of ITS1. The base substitution rates were ranged from 0 to 0.6069 per site, and higher rate was found in R. stolonifer. In general, transition was usually more frequent than transversion. On the basis of sequencing results, four groups were clustered with value of 61.9% similarity; R. oryzae, R. micros pores, R. homothallicus, and R. stolonifer groups.

• 한국산업융합학회 논문집
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• 제7권3호
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• pp.299-303
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• 2004

A systematic investigation for the reactivity and solvent effect was studied on the reaction of optical resolving agents with the optically active assistant compounds. The reaction rate constants of the nucleophillic substitution reactions were determined by means of conductometric method The linear solvent energy relationship based on the solvent parameters and the thermodynamic parameters was discussed on the reactions of various physiological active compounds and optical resolving agents The reaction mechanism was discussed from the kinetic results compared with the optical purity.

• Bulletin of the Korean Chemical Society
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• 제15권8호
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• pp.654-658
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• 1994

Rate constants have been measured spectrophotometrically for the nucleophilic substitution reactions of p-and m-nitrophenyl 2-furoates (4 and 5, respectively) with alkali metal ethoxides ($EtO^-M^+$) in absolute ethanol at 25$^{\circ}$C. The reactivity of $EtO^-M^+$ toward 4 is in the order $EtO^-K^+$ > $EtO^-Na^+$> $EtO^-Li^+$ > $EtO^-K^+$+ 18-crown-6 ether. This is further confirmed by an ion pairing treatment method. The present result indicates that (1) ion paired $EtO^-M^+$ is more reactive than dissociated $EtO^-$ ; (2) the alkali metal ions ($K^+,\;Na^+,\;Li^+$) behave as a catalyst; (3) the catalytic effect increases with increasing the size of the metal ion. A similar result has been obtained for the reaction of 5, however, the catalytic effects shown by the metal ions are more significant in the reaction of 5 than in that of 4.