• 한국어병학회지
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• 제33권2호
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• pp.177-184
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• 2020

In an attempt to find a feed additive showing an anti-scuticociliate effect, extracts from Citrus unshiu Peel were tested against virulent scuticociliate infection. The most effective anti-scuticociliate killing activity in vitro was observed in the extract squeezed from homogenizing water-soaked dried tangerine peel (DTP). In addition, we have investigated the effect of DTP as a feed additive on growth rate and anti-parasitic activity of olivaceus flounder. DTP extract added diets (0.1, 0.5, 1, and 5%/feed weight) were fed to flounder for 7 days for checking a growth rate and 14 days for a challenging test. As a result, the feed conversion rate was significantly improved only in 1% DPT extract group compared to the control and 0.5% DTP extract fed group showed 100% of survival rate in the challenge test, all of which indicating that DTP extract would be a potential feed additive against scuticociliatosis.

• 대한토목학회논문집
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• 제42권2호
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• pp.257-261
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• 2022

건축물의 디자인 자유도 향상, 작업자 안전 향상, 비교적 쉬운 납기예측 등의 이점으로 건설 산업에 적용된 3D 프린팅 기술(Additive manufacturing, AM)은 각종 효과성의 검증과 산업적용이 진행되고 있다. 다만, 기존기술대비 낮은 성숙도로 인해, 건축AM기술의 전주기에 발생하는 새로운 문제들을 해소하기 위한 연구들이 진행 중이다. 본 논문에서는 이러한 문제점 중에서도 현장 환경에 건축물을 적층 시공하는 과정에서, 낮은 시공표면평탄이 적층 제조 형상물에 미치는 영향을 확인한다. 특히 레이저 스캐닝을 통한 3차원 재구성 및 정량 분석을 통해, 낮은 평탄도로 인한 불균일한 적층형상물을 분석하고, 이를 해소하기 위한 적층시공전략을 제안한다.

• 한국분말재료학회지
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• 제30권6호
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• pp.463-469
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• 2023

Aluminum alloys, known for their high strength-to-weight ratios and impressive electrical and thermal conductivities, are extensively used in numerous engineering sectors, such as aerospace, automotive, and construction. Recently, significant efforts have been made to develop novel aluminum alloys specifically tailored for additive manufacturing. These new alloys aim to provide an optimal balance between mechanical properties and thermal/electrical conductivities. In this study, nine combinatorial samples with various alloy compositions were fabricated using direct energy deposition (DED) additive manufacturing by adjusting the feeding speeds of Al6061 alloy and Al-12Si alloy powders. The effects of the alloying elements on the microstructure, electrical conductivity, and hardness were investigated. Generally, as the Si and Cu contents decreased, electrical conductivity increased and hardness decreased, exhibiting trade-off characteristics. However, electrical conductivity and hardness showed an optimal combination when the Si content was adjusted to below 4.5 wt%, which can sufficiently suppress the grain boundary segregation of the α-Si precipitates, and the Cu content was controlled to induce the formation of Al₂Cu precipitates.

• 마이크로전자및패키징학회지
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• 제29권4호
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• pp.41-47
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• 2022

Ag sintering technologies have received great attention as it was applied to the inverter of Tesla's electric vehicle Model III. Ag sinter bonding technology has advantages in heat dissipation design as well as high-temperature stability due to the intrinsic properties of the material, so it is useful for practical use of SiC and GaN devices. This study was carried out to understand the sinter joining temperature effect on the robust Ag sintered joints in air without pressure within 10 min. Electroplated Ag finished Cu dies (3 mm × 3 mm × 2 mm) and substrates (10 mm × 10 mm × 2 mm) were introduced, respectively, and nano Ag paste was applied as a bonding material. The sinter joining process was performed without pressure in air with the bonding temperature as a variable of 175 ℃, 200 ℃, 225 ℃, and 250 ℃. As results, the bonding temperature of 175 ℃ caused 13.21 MPa of die shear strength, and when the bonding temperature was raised to 200 ℃, the bonding strength increased by 157% to 33.99 MPa. When the bonding temperature was increased to 225 ℃, the bonding strength of 46.54 MPa increased by about 37% compared to that of 200 ℃, and even at a bonding temperature of 250 ℃, the bonding strength exceeded 50 MPa. The bonding strength of Ag sinter joints was directly influenced by changes in the necking thickness and interfacial connection ratio. In addition, developments in the morphologies of the joint interface and porous structure have a significant effect on displacement. This study is systematically discussed on the relationship between processing temperatures and bonding strength of Ag sinter joints.

• 대한약침학회지
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• 제22권3호
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• pp.122-130
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• 2019

Objectives: The medicinal plants are believed to enhance the natural resistance of the body to infections. Some of the main constituents of the plant and derived materials such as, proteins, lectins and polysaccharides have anti-inflammatory effects. Portulaca oleracea (P. oleracea) were used traditionally for dietary, food additive, spice and various medicinal purposes. This review article is focus on the anti-asthmatic effects of P. oleracea and its constituents. Methods: Various databases, such as the PubMed, Scopus, and Google Scholar, were searched the keywords including "Portulaca oleracea", "Quercetin", "Anti-inflammatory", "Antioxidant", "Cytokines", "Smooth muscle ", and " Relaxant effects " until the end of Jul 2018. Results: P. oleracea extracts and its constituents increased $IFN-{\gamma}$, IL-2, $IFN{\gamma}/IL-4$ and IL- 10/IL-4 ratio, but decreased secretion of $TNF-{\alpha}$, IL-4 and chemokines in both in vitro and in vivo studies. P. oleracea extracts and quercetin also signifcantly decreased production of NO, stimulated ${\beta}$-adrenoceptor and/or blocking muscarinic receptors in tracheal smooth muscles. Conclusion: P. oleracea extracts and quercetin showed relatively potent anti-asthmatic effects due to decreased production of NO, inflammatory cytokines and chemokines, reduced oxidant while enhanced antioxidant markers, and also showed potent relaxant effects on tracheal smooth muscles via stimulatory on ${\beta}$-adrenoceptor or/and blocking muscarinic receptors.

• Natural Product Sciences
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• 제11권3호
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• pp.160-164
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• 2005

The effects of Cymbopogon citratus essential oil (Lemongrass oil) and its main component, citral (84.30%), on antibiotic-susceptible and -resistant strains of Salmonella enteritidis and S. typhimurium were assessed. C. citratus oil and citral significantly inhibited all strains of the two Salmonella species examined, with minimum inhibiting concentrations (MICs) ranging from 0.5 mg/ml to 8.0 mg/ml. The combined effects of C. citratus oil and citral (84.30%) were evaluated using a checkerboard microtiter assay. Essential oil fractions of C. citratus and citral exhibited strong synergistic or additive effects with streptomycin or kanamycin against S. typhimurium strains with fractional inhibitory concentration (FIC) indices in the range of 0.28 to 1.00. In conclusion, a combination of streptomycin and lemongrass oil or its main component, citral, may be useful for reducing the minimum effective dose of antibiotic required for the treatment of resistant S. typhimurium infections.

• 한국연초학회지
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• 제9권1호
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• pp.45-55
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• 1987

For some basic information in tobacco breeding, the modes of inheritance and heritabilities for the twelve agronomic and chemical characters were estimated in the study of eight varieties partial diallel set. Additive gene actions were significant for all characters except total nitrogen content and dominance gene effects were also significant for all characters. Yield, number of leaves per plant, leaf length and leaf shape index were inherited as partial dominance, and overdominance was detected for plant height, stem diameter, internode length, total alkaloid, total nitrogen and total sugar content. Dominant gene showed increasing effects in yield, plant height, stem diameter, internode length, leaf width and total sugar content, but showed decreasing effects in the other characters. The broad heritability was very high for all characters. and the narrow heritability was high in days to flower and yield, but low in internode length, total alkaloid, total nitrogen and total sugar content.

• 한국재료학회지
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• 제2권4호
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• pp.306-310
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• 1992

Effects of hafnium, boron and zirconium on the ductility of Ni$_3$(Al, Fe) intermetallic compounds were studied using tensile test and SIMS analysis. Ni$_3$(Al, Fe) alloy with 0.1 at.% Hf, 0.05 at.% B and 0.1 at.% Zr additions showed maximum elongations of about 30% at 300K, 10% at 300K and 14% at 473K, respectively. The fracture mode of the alloy without the additive was the mixture of intergranular and transgranular fractures, but the addition of Hf, Zr or B changed the fracture mode to transgranular only. SIMS analysis showed that the beneficial effects of Hf, Zr or B segregation on the grain boundary strength are consistent with the grain boundary cohesion theory.

• Asian-Australasian Journal of Animal Sciences
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• 제11권4호
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• pp.441-444
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• 1998

The negative direct-maternal genetic correlation $(r_{dm})$ for weaning weight is inflated when data are analyzed with model ignoring sire-by-year interactions (SY). An analytical study investigating the consequences of ignoring SY was undertaken. The inflation of negative correlation could be due to a functional relationship of design matrices for additive direct and maternal genetic effects to that for sire effects within which SY effects were nested. It was proven that the maternal genetic variance was inflated by the amount of reduction for sire variance; the direct genetic variance was inflated by four times the change for maternal genetic variance; and the direct-maternal genetic covariance was deflated by twice the change for maternal genetic variance. The findings were agreed to the results in previous studies.

• 한국식품영양과학회지
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• 제27권3호
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• pp.508-517
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• 1998

We investigated the effects of godulbaegi extracts on the physiochemical properties of biological membranes as membrane stability and fluidity employing the phospholipid liposomal membrances as a biomembrane-mimetic system. The addition of the godulbaegi extracts to the phospholipid exterted great effects stagbilized the barrier function of the liposomal membranes in proportion to the concentration of the additive and significantly increased the membranes fluidity. The values of the fluorescence polarization of 1,6-diphenyl 1,3,5-hexatriene (DPH) decreased gradually as the temperature increased, and decreased abruptly near the phase transition temperature (Tm) of the liposome from gel to liquid crystalline state as usual. These results suggest that the activities of the godulbaegi extracts to enhance the stability and fluidity of the liposomal membranes have implication in their biological activities.