• 폴리머
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• 제31권3호
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• pp.233-238
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• 2007

Poly(glycolic acid) (PGA)와 poly [(R) -3-hydrokybutyrate] (P3HB) 및 poly(butylenes succinate-co-L-lactate) (PBSL) 복합재료를 체내에서 서로 다른 가수분해속도를 보완하여 저가의 의료용 흡수성 복합재료로 응용하고자 연구하였다. 그 결과 PBSL/PGA와 P3HB/PGA 복합섬유는 인산염 완충용액 중에서 가수분해되는 것이 확인되었으며, PBSL/PGA 복합섬유는 PGA의 분해에 의해 발생된 glycolic acid에 의해 PBSL의 분해가 촉진되는 메카니즘이 확인되었다. PBSL/PGA 복합섬유는 lipase PS가 존재함에 의해 상당히 빠른 가수분해가 발생하는 것이 확인되었으며, 대기중에서는 거의 가수분해가 발생되지 않는 것을 알 수 있었다. P3HB/PGA 복합섬유 역시 대기중에서 적당한 인장강도를 유지하고 있는 것이 확인된 것으로 보아 본 연구를 통하여 이들 복합섬유는 의료용 흡수성 복합재료와 환경 적합재료로서 응용이 가능할 것으로 판단된다.

• Elastomers and Composites
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• 제39권2호
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• pp.142-152
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• 2004

서로 다른 두 종류의 폴리스타일렌(PS)을 injection 기계를 이용하여 인장 시편을 만들고, 온도와 인장 속도에 따른 crazing 거동 특성을 연구하기 위하여 다양한 시험을 하였다. 기계적물성은 craze 형성뿐만 아니라 다양한 시험 변수에 의해 영향을 받으며, brittle-ductile transition 이하의 온도에서의 인장 응력 및 최대 신율은 분자량, 인장 속도의 증가 및 온도의 감소에 따라 증가하며 craze의 수와 평균 길이 또한 증가한다. Crazing 응력도 동일한 형태로 증가함을 보여준다. 그러나, 이러한 특성은 인장 강도에 미치는 영향과 비교했을 때 보다 의존도는 상대적으로 낮다. Craze 형성과 성장에 필요한 시간으로 설명할 수 있는 crazing 응력과 인장 응력간의 차이는 분자량, 인장 속도에 따라 비례적으로 그리고, 온도가 감소함에 따라 증가함을 보여 준다. Crazing 은 ${\beta}$-relaxation 온도 근처에서 활성화된다. 이 온도에서는 crazing 응력이 급격하게 감소함을 나타낸다. 인장 평가시 craze 밀도가 적용된 응력에 따라 기하 급수적으로 증가되는데, 개시 단계에서는 craze는 서서히 형성되며, 일단 일정한 수만큼의 craze가 형성이 되면 craze 밀도가 급속도로 증가했다.

• 대한화장품학회지
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• 제33권4호
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• pp.231-238
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• 2007

본 연구에서는 0.3 % 나문재 에틸아세테이트 추출물(이하 추출물) 함유 제품의 안정성을 평가하였다. 추출물 함유 크림을 12주 동안 온도별 저장($0^{\circ}C,\;25^{\circ}C,\;37^{\circ}C$ 및 $45^{\circ}C$)과 태양광선에의 노출 조건에서 4주 간격으로 pH, 흡광도 및 점도의 변화를 측정하였다. 온도별 저장조건에서 추출물이 함유되어 있지 않은 대조군 크림은 상기 온도 조건에서 pH 변화가 거의 없었다. 추출물 함유 크림의 경우는 $0^{\circ}C\;{\sim}\;37^{\circ}C$에서 pH가 0.08 감소하였고, $45^{\circ}C$ 저장과 태양광선 노출 시는 각각 0.51 및 0.66 감소하였다 12주 동안 $0\;{\sim}\;37^{\circ}C$에서는 추출물 함유 제품의 흡광도 변화가 거의 없었다. 반면에 $45^{\circ}C$ 저장과 태양광선 노출시킨 경우는 흡광도가 각각 7.6 % 및 7.4 % 감소하였다. 크림으로부터 추출물을 용출시킨 에탄올 용액을 태양광선에 직접 노출시켰을 때 4주 만에 흡광도가 48.3% 감소한 것에 비해서는 작은 감소를 나타낸다. 이는 추출물이 크림 내에서 비교적 안정화되어 있음을 나타낸다. 온도별 저장 조건에서 12주 후 추출물 함유 크림과 대조군 크림의 점도를 측정하였다. 추출물 함유 크림은 초기 점도보다 평균 1,748 cPs 증가를 나타내었고, 대조군은 평균 951 cPs 증가하였다. 태양광선 노출 조건에서 대조군은 12주 후 오히려 점도가 4,022 cPs나 큰 감소폭을 나타내었다. 반면에 동일 조건에서 추출물 함유 크림의 점도는 2,483 cPs 증가하였다. 이는 나문재 추출물이 태양광선에 대항하는 보호제로 작용하여 크림의 점도를 유지시켜 제품을 안정화시키는데 기여한 것으로 보여진다. 첨부해서, 추출물 함유 크림과 대조군 크림은 12주 동안 동일한 실험 조건에서, 냄새나 색상 변화가 거의 없었다. 이와 같은 결과들은 나문재 추출물을 함유한 크림은 비교적 안정하지만 장기간 보관 시에는 안정성에 문제가 나타날 수 있음을 시사한다. 따라서 제품 응용시 나문재 성분들이 항산화 효과를 발휘하고 제품 안정에 기여할 수 있도록 보완 연구가 필요하다고 생각된다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2016년도 춘계 학술논문 발표대회
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• pp.132-133
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• 2016

The Present that environmentally friendly policies at issue in the world recently, construction sector and other sectors are working on reducing CO₂. Cement production during in the construction sector, CO₂ is being caused in large quantities. Therefore, this study was secure the basic date that not use cement and use blast furnace slag and fly ash HFA, polysilicon in industrial byproducts about cement non-cement matrix.

• International Journal of Computer Science & Network Security
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• 제21권11호
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• pp.345-353
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• 2021

Cloud computing represent a new era of computing that's forms through the combination of service-oriented architecture (SOA), Internet and grid computing with virtualization technology. Virtualization is a concept through which every cloud is enable to provide on-demand services to the users. Most IT service provider adopt cloud based services for their users to meet the high demand of computation, as it is most flexible, reliable and scalable technology. Energy based performance tradeoff become the main challenge in cloud computing, as its acceptance and popularity increases day by day. Cloud data centers required a huge amount of power supply to the virtualization of servers for maintain on- demand high computing. High power demand increase the energy cost of service providers as well as it also harm the environment through the emission of CO₂. An optimization of cloud computing based on energy-performance tradeoff is required to obtain the balance between energy saving and QoS (quality of services) policies of cloud. A study about power usage of resources in cloud data centers based on workload assign to them, says that an idle server consume near about 50% of its peak utilization power [1]. Therefore, more number of underutilized servers in any cloud data center is responsible to reduce the energy performance tradeoff. To handle this issue, a lots of research proposed as energy efficient algorithms for minimize the consumption of energy and also maintain the SLA (service level agreement) at a satisfactory level. VM (virtual machine) consolidation is one such technique that ensured about the balance of energy based SLA. In the scope of this paper, we explore reinforcement with fuzzy logic (RFL) for VM consolidation to achieve energy based SLA. In this proposed RFL based active VM consolidation, the primary objective is to manage physical server (PS) nodes in order to avoid over-utilized and under-utilized, and to optimize the placement of VMs. A dynamic threshold (based on RFL) is proposed for over-utilized PS detection. For over-utilized PS, a VM selection policy based on fuzzy logic is proposed, which selects VM for migration to maintain the balance of SLA. Additionally, it incorporate VM placement policy through categorization of non-overutilized servers as- balanced, under-utilized and critical. CloudSim toolkit is used to simulate the proposed work on real-world work load traces of CoMon Project define by PlanetLab. Simulation results shows that the proposed policies is most energy efficient compared to others in terms of reduction in both electricity usage and SLA violation.

• Asian-Australasian Journal of Animal Sciences
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• 제33권1호
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• pp.24-34
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• 2020

Objective: The effects of Pleurotus ostreatus on the feed utilization of broad bean stalks (BBS), rape straw (RS), paddy straw (PS), and corn stalk (CS) was examined. Methods: The four roughages were co-cultured with Pleurotus ostreatus. The chemical composition; enzyme activities of laccase, carboxymethylcellulase (CMCase) and xylanase; carbohydrate and protein fractions (based on The Cornell Net Carbohydrate and Protein System [CNCPS]) were assessed at different days after inoculation (7, 14, 21, 28 d) and un-inoculated roughages (control, 0 d). The digestibility of nutrient components and the gas production of roughage with various incubation times were monitored at 0, 2, 4, 6, 9, 12, 24, 36, 48, 60, and 72 h using an in vitro ruminal fermentation method. Results: A higher CMCase activity (0.1039 U/mL) and earlier time to peak (14 d) were detected in Pleurotus ostreatus cultured with CS (p<0.05). Significantly, the incubation length-dependent responses of cumulative gas production were observed from 24 to 72 hours post fermentation (p<0.05), and these incubation length-dependent effects on cumulative gas production of PS and CS appeared earlier (24 h) for PS and CS than those (48 h) for BBS and RS (p<0.05). The fast-degradable carbohydrate (CA) content for all four roughages significantly increased over time (p<0.05). Nonetheless, increased degradation efficiency for CA treated with Pleurotus ostreatus was detected at both 21 and 28 days of incubation (p<0.05). With the exception of PS (p<0.05), there were no significant difference among the roughages (p>0.05) in slowly-degradable carbohydrate (CB2) at different incubation times (p<0.05). Conclusion: Assessment of the alterations in chemical composition, CNCPS system fractions, and the fermentation kinetics after biological pretreatment may yield a valuable database for evaluating the biological pretreatment of Pleurotus ostreatus in ruminant feed.

• Fibers and Polymers
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• 제6권1호
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• pp.19-27
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• 2005

High-speed melt spinning of syndiotactic polystyrene was carried out using high and low molecular weight poly­mers, HM s-PS and LM s-PS, at the throughput rates of 3 and 6 g/min. The effect of take-up velocity on the structure and properties of as-spun fibers was investigated. Wide angle X-ray diffraction (WAXD) patterns of the as-spun fibers revealed that the orientation-induced crystallization started to occur at the take-up velocities of 2-3 km/min. The crystal modification was a-form. Birefringence of as-spun fibers showed negative value, and the absolute value of birefringence increased with an increase in the take-up velocity. The cold crystallization temperature analyzed through the differential scanning calorimetry (OSC) decreased with an increase in the take-up velocity in the low speed region, whereas as the melting temperature increased after the on-set of orientation-induced crystallization. It was found that the fiber structure development proceeded from lower take-up velocities when the spinning conditions of higher molecular weight and lower throughput rate were adopted. The highest tensile modulus of 6.5 GPa was obtained for the fibers prepared at the spinning conditions of LM s-PS, 6 g/min and 5 km/min, whereas the highest tensile strength of 160 MPa was obtained for the HM s-PS fibers at the take-up velocity of 2 km/min. Elongation at break of as-spun fibers showed an abrupt increase, which was regarded as the brittle-duc­tile transition, in the low speed region, and subsequently decreased with an increase in the take-up velocity. There was a uni­versal relation between the thermal and mechanical properties of as-spun fibers and the birefringence of as-spun fibers when the fibers were still amorphous. The orientation-induced crystallization was found to start when the birefringence reached -0.02. After the starting of the orientation-induced crystallization, thermal and mechanical properties of as-spun fibers with similar level of birefringence varied significantly depending on the processing conditions.

• 한국임상수의학회지
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• 제34권5호
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• pp.335-340
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• 2017

Methicillin-resistant staphylococci (MRS), which are often multi-drug resistant (MDR), are important pathogens in both human and veterinary healthcare. The purpose of this study was to characterize the antimicrobial resistance of MRS isolated from dog ears in Korea. From 827 dog ears, staphylococci were cultured from both ears with otitis externa (n = 161, 41.0%) and healthy ears (n = 135, 31.1%). The prevalence of coagulase-positive staphylococci (CoPS) in ears with otitis externa (58.4%) was significantly higher (p < 0.05) than in healthy ears (28.2%), while the prevalence of coagulase-negative staphylococci (CoNS) in healthy ears (74.8%) was higher (P < 0.05) than in ears with otitis externa (41.6%). Forty-six (35.1%) and 74 (44.8%) CoPS and CoNS isolates, respectively, were determined to be MRS. Antimicrobial resistance in MRS was most frequently observed for penicillin (76.7%), ampicillin (61.7%), kanamycin (61.7%), erythromycin (47.5%), tetracycline (47.5%), and trimethoprim/sulfamethoxazole (46.7%). Overall, the MDR isolates were resistant to significantly more (P < 0.05) antimicrobial agents tested than methicillin-sensitive staphylococci in this study. These results provide therapeutic guidelines for the treatment of otitis externa in dogs from Korean veterinary hospitals, and the significant associated health concern to companion animals and their human contacts.

• Asian-Australasian Journal of Animal Sciences
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• 제5권3호
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• pp.455-459
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• 1992

Five type of formulated diet from agricultural by-products (ABP) were fed to four breedtype of cattle in feedlot. The ABP used are palm kernel cake (PKC), palm press fibre (PPF), palm oil mill effluent (POME), cocoa pod (COP), coffee pulp (COF) and pineapple waste (PAP). The formulated diets are PS (52% PKC, 15% PPF and 30% POME), PF (57% PKC, 20% PPF and 20% POME), PA (2% PKC and 55% PAP), CO (42% PKC and 55% COP) and CF (67% PKC and 30% COF) with 1% urea, 1% NaCl and 1% vitamins premix. The cattle breedtypes are Kedah-Kelantan (KK), Brahman-KK (BK), Hereford-KK (HK) and Sahiwal-Friesian (SF). The result showed that breedtype significantly affect all the carcass characteristic except dressing percentage. Each breedtype has it's specific carcass characteristics. HK cattle gave high marbling, BK has high % of carcass bone, KK has high % of carcass meat and low % of carcass fat (lean meat type) and SF has high % of carcass fat. Diet-type significantly affect the deposition of fat in the carcass. High moisture diets (PA and CO) produced significantly higher % carcass bone, the lowest % carcass fat and the highest % carcass meat (65.3%). PF, CF, PA and CO diets produced 63.4%, 59.9%, 55.3% and 54.1% carcass meat respectively.

• Bulletin of the Korean Chemical Society
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• 제32권1호
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• pp.71-76
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• 2011

An efficient nucleophilic [$^{18}F$]fluorination has been studied to reduce byproducts and preparation time. Instead of conventional aqueous solution of $K_2CO_3-K_{222}$, several organic solution containing inert organic salts were used to release [$^{18}F$]fluoride ion and anion bases captured in the polymer cartridge, concluding that methanol solution is the best choice. Comparing to azeotropic drying process, one min was sufficient to remove methanol completely, resulting in about 10% radioactivity saving by reducing drying time. The polymer cartridge, Chromafix$^{(R)}$ (PS-$HCO_3$) was pretreated with several anion bases to displace pre-loaded bicarbonate base. Phosphate bases showed better results than carbonate bases in terms of lower basicity. tert-Butanol solvent used as a reaction media played another critical role in nucleophilic [18F]fluorination by suppressing eliminated side product. Consequent [$^{18}F$]fluorination under the present condition afforded fast preparation of reaction solution and high radiochemical yields (98% radio-TLC, 84% RCY) with 94% of precursor remained.