• Journal of the Korea Institute of Building Construction
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• v.11 no.4
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• pp.353-362
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• 2011

High Strength Concrete (HSC) has weakness that in a fire, it is spalled and brittles. The phenomenon of spalling is made by water vapor's being confined in watertight concrete. This study is aimed to evaluate explosive spalling properties of high strength concrete with ${\square}100{\times}100{\times}200$ mm specimen and ${\square}400{\times}400{\times}1500$ mm column. To prevent spalling of concrete, fireproof coating and PP fiber are used. As a result, ${\square}400{\times}400{\times}1500$ mm column was prevented spalling likes ${\times}100{\times}100{\times}200$ mm specimen. When concrete protected failure to explosive spalling, quantity heat ratio (which fireproof coating specimen to pp fiber mixed specimen) between ${\square}100{\times}100{\times}200$ mm and ${\square}400{\times}400{\times}1500$ mm was maximum value at 20 minute, but difference of quantity heat ratio decreased and quantity heat ratio of each specimen is almost same at 30 minute.

• Composites Research
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• v.36 no.4
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• pp.264-269
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• 2023

Spent coffee grounds (SCG) are a ubiquitous byproduct of coffee consumption, representing a significant waste management challenge, as well as an untapped resource for economic development and sustainability. Improper disposal of SCG can result in environmental problems such as methane emissions and leachate production. This study aims to investigate the physicochemical properties of SCG and their potential as a reinforcement material in polypropylene (PP) to fabricate an eco-friendly composite via extrusion and injection molding, with SCG filler ratios ranging from 5-20%. To evaluate the effect of SCG on the morphological and mechanical properties of the bio- composite, thermogravimetric analysis, SEM, tensile, flexural, and impact tests were conducted. The results demonstrated that the addition of SCG lead to a slight increase in brittleness of the composite but did not significantly affect its mechanical properties. Impressively, the presence of a significant organic component in SCG contributed to the enhanced thermal performance of PP/SCG composites. This improvement was evident in terms of increased thermal stability, delayed onset of degradation, and higher maximum degradation temperature as compared to pure PP. These findings suggest that SCG has potential as a filler material for PP composites, with the ability to enhance the material's properties without compromising overall performance.

• The Korean Journal of Rheology
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• v.5 no.1
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• pp.76-84
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• 1993

비상용 고분자 PP/PS 블렌드계에서 상용성을 높이기 위하여 상용화제 SEBS 블록 공중합체를 첨가하였다. 상용화제의 첨가량에 따른 유변학적 그리고 기계적 물성은 상용화 제를 첨가하지 않은 조성보다 물성의 향상을 가져왔다. 형태학적으로 분산상 크기 감소, 분 산분포와 유변학적 성질의 에멀젼 모델을 이용하여 상대적 계면장력을 계산하여 상용화제으 최적 농도를 조사하였다. 또한 상용화제가 더 이상 기계적 물성에 영향을 미치지 않는 농도 를 조사하였다. 형태학적, 유변학적 그리고 기계적 물성조사에 나타난 상용화제의 최적 농도 는 약 1wt%이었다.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.419-420
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• 2010

High strength concrete(HSC) is made with Fiber-cocktail to control the spalling of HSC. In this paper, the column is made with PP fiber of $1.5kg/m^3$ and steel fiber of 20, 30, $40kg/m^3$, and the test are observed the temperature of reinforced bars and concrete. The results that increasing of temperature is delay as increase of steel fiber's volume.

• Elastomers and Composites
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• v.38 no.2
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• pp.167-174
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• 2003

Thermoplastic vulcanizates (TPV) or dynamic vulcanizates are thermoplastic elastomers produced by simultaneous mixing and crosslinking of a rubber and a thermoplastic. The objective of the present work is to investigate the effects of different types of peroxides as curing agents on the properties of PP/EPDM TPVs. The mechanical properties change significantly with the chemical nature of the peroxides and the extent of crosslinking at a fixed PP/EPDM blend ratio. The tensile strength of the TPVs obtained with the various peroxides can be related to the solubility parameters of the polymers and of the peroxides. The Young's modulus of the peroxide-cured TPVs can be correlated with the delta torque values of equivalent thermoset EPDM vulcanizates, corresponding to the crosslinking efficiencies of the peroxides.

• Journal of Intelligence and Information Systems
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• v.2 no.1
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• pp.45-58
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• 1996

This paper describes an a, pp.oach to recognizing composite features of prismatic parts. AAG (Attribute Adjacency Graph) is adopted as the basis of describing basic feature, but it is extended to enhance the expressive power of AAG by adding face type, angles between faces and normal vectors. Our a, pp.oach is called Extended AAG (EAAG). To simplify the recognition procedure, feature classification tree is built using the graph types of EEA and the number of EAD's. Algorithms to find open faces and dimensions of features are exemplified and used in decomposing composite feature. The processing sequence of recognized features is automatically determined during the decomposition process of composite features.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.2
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• pp.188-196
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• 2010

The objective of this study was to characterize the litter sizes in Huanghuai goats with high prolificacy (HP, five or more kids born per litter on at least one occasion), and to compare their peripheral blood concentrations of progesterone and estradiol with those of goats with poor prolificacy (PP, up to three kids born per litter on any occasion). The circulating concentrations of progesterone and estradiol were measured by radioimmunoassay from daily blood samples taken during natural estrus cycles and at 1-5 days after ovariectomy. Estrus was synchronized using two doses of a prostaglandin analog. Litter size for the HP goats increased up to a parity of five and decreased thereafter. The percentage of goats with litter sizes of $\geq$4 from parities 3 to 6 ranged from 44.5% to 58.3%. Although small differences in litter size were obtained for goats of parities three, four and six relative to five, parity five does had the highest mean litter size. Progesterone concentrations began to rise earlier and were higher in the HP than in the PP goats on most days of the luteal phase, but not during the follicular phase of the cycle or after ovariectomy. There was a significant difference between the two groups (p<0.05) in the magnitude of the progesterone plateau. Mean estradiol concentrations in the HP group remained significantly higher than in the PP group (p<0.05) during the estrus cycle. There were two estradiol peaks in the HP goats during the early luteal phase, but only one in the PP group. Measurements of individual corpora lutea (CL) in vitro showed that there was a greater prevalence of small CL (<6 mm in diameter) in the HP group than in the PP group (p<0.05). After ovariectomy, the estradiol level on day 1 was significantly higher than at the nadir during the estrus cycle in both the HP (p<0.01) and PP (p<0.05) goats, while levels decreased by 12.3% and 26.2% respectively compared with the mid-luteal period in HP and PP goats (p<0.05). The overall mean estradiol concentrations in HP goats were lower than in the PP group, but no significant differences were found between groups at 1-5 days after ovariectomy.

• Journal of Korean Society for Quality Management
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• v.25 no.4
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• pp.79-87
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• 1997

In this paper, we obtain maximum likelihood estimator(MLE) of a parallel system reliability for the Marshall and Olkin's bivariate exponential model with birariate type 1 consored data. The asymptotic normal distribution of the estimator is obtained. Also we construct an a, pp.oximate confidence interval for the reliability based on MLE. We present a numerical study for obtaining MLE and a, pp.oximate confidence interval of the reliability.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.16 no.4
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• pp.180-195
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• 2011

A balanced trophic model for Sinjido marine ecosystem was constructed using ECOPATH model and data obtained 1994 in the region. The model integrates available information on biomass and food spectrum, and analyses ecosystem properties, dynamics of the main species populations and the key trophic pathways of the system, and then compares these results with those of other marine environments. The model comprises 17 groups of benthic algae, phytoplankton, zooplankton, gastropoda, polychaeta, bivalvia, echinodermata, crustacean, cephalopoda, goby, flatfish, rays and skates, croaker, blenny, conger, flatheads, and detritus. The model shows trophic levels of 1.0~4.0 from primary producers and detritus to top predator as flathead group. The model estimates total biomass(B) of 0.1 $kgWW/m^2$, total net primary production(PP) of 1.6 $kgWW/m^2/yr$, total system throughput(TST) of 3.4 $kgWW/m^2/yr$ and TST's components of consumption 7%, exports 43%, respiratory flows 4% and flows into detritus 46%. The model also calculates PP/TR of 0.012, PP/B of 0.015, omnivory index(OI) of 0.12, Fin's cycling index(FCI) of 0.7%, Fin's mean path length(MPL) of2.11, ascendancy(A) of 4.1 $kgWW/m^2/yr$ bits, development capacity(C) of 8.2 $kgWW/m^2/yr$ bits and A/C of 51%. In particular this study focuses the analysis of mixed trophic impacts and describes the indirect impact of a groupb upon another through mediating one based on 4 types. A large proportion of total export in TST means higher exchange rate in the study region than in semi enclosed basins, which seems by strong tidal currents along the channels between islands, called Sinjido, Choyakdo and Saengildo. Among ecosystem theory and cycling indices, B, TST, PP/TR, FCI, MPL and OI are shown low, indicating the system is not fully mature according to Odum's theory. Additionally, high A/C reveals the maximum capacity of the region is small. To sum up, the study region has high exports of trophic flow and low capacity to develop, and reaches a development stage in the moment. This is a pilot research applied to the Sinjido in terms of trophic flow and food web system such that it may be helpful for comparison and management of the ecosystem in the future.

• Polymer Science and Technology
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• v.4 no.6
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• pp.452-459
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• 1993

이상 PPS 및 poly(arylene sulfides)라는 통칭으로 불리우는 PPS 유사한 구조의 polymer들에 대한 중합 반응에 대하여 발표 문헌들을 정리하여 보았다. PPS는 중합 반응 자체가 고온 고압하에서 이루어지므로 공정상 어려움이 있으나 단량체 cost가 싼 장점이 있을 뿐 아니라 유사한 구조의 polymer들이 무정형에서 부터 PPS보다 훨씬 더 높은 결정성 혹은 내열성을 나타내므로 공중합 혹은 block 공중합체를 합성하므로서 새로운 물성의 polymer가 개발될 가능성이 높은 고분자 소재로 생각된다.