• Mycobiology
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• 제50권1호
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• pp.55-65
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• 2022

Lichen is a symbiotic mutualism of mycobiont and photobiont that harbors diverse organisms including endolichenic fungi (ELF). Despite the taxonomic and ecological significance of ELF, no comparative investigation of an ELF community involving isolation of a pure culture and high-throughput sequencing has been conducted. Thus, we analyzed the ELF community in Parmotrema tinctorum by culture and metabarcoding. Alpha diversity of the ELF community was notably greater in metabarcoding than in culture-based analysis. Taxonomic proportions of the ELF community estimated by metabarcoding and by culture analyses showed remarkable differences: Sordariomycetes was the most dominant fungal class in culture-based analysis, while Dothideomycetes was the most abundant in metabarcoding analysis. Thirty-seven operational taxonomic units (OTUs) were commonly observed by culture-and metabarcoding-based analyses but relative abundances differed: most of common OTUs were underrepresented in metabarcoding. The ELF community differed in lichen segments and thalli in metabarcoding analysis. Dissimilarity of ELF community intra lichen thallus increased with thallus segment distance; inter-thallus ELF community dissimilarity was significantly greater than intra-thallus ELF community dissimilarity. Finally, we tested how many fungal sequence reads would be needed to ELF diversity with relationship assays between numbers of lichen segments and saturation patterns of OTU richness and sample coverage. At least 6000 sequence reads per lichen thallus were sufficient for prediction of overall ELF community diversity and 50,000 reads per thallus were enough to observe rare taxa of ELF.

• 한국수소및신에너지학회논문집
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• 제34권6호
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• pp.767-772
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• 2023

In this study, combustion experiments were conducted at various engine speeds under full-load conditions using a single-cylinder diesel engine by blending butanol, pentanol, and octanol with diesel at a volume ratio of 10%. Experimental results revealed that higher alcohol-diesel blends resulted in lower brake torque and brake power than pure diesel due to the lower calorific value and the cooling effect during evaporation. An evident improvement in the brake thermal efficiency of the blended fuels was observed at engine speeds below 2,000 rpm, with the butanol blend exhibiting the highest thermal efficiency overall. Furthermore, the brake-specific fuel consumption of the higher alcohol-diesel blends was lower than that of pure diesel at speeds below 2,200 rpm. When using blended fuels, the exhaust gas temperature decreased under lean mixture conditions due to heat loss to the air and the cooling effect from fuel evaporation.

• 한국초전도ㆍ저온공학회논문지
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• 제25권3호
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• pp.28-33
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• 2023

Magnetic relaxation properties of pure MgB₂ powder samples and diluted water-treated MgB₂ powder samples were investigated. The magnetic field H-dependence, m(H), and the time t-dependence, m(t), of the magnetic moment m were measured and analyzed using the PPMS-VSM magnetometer equipment, respectively. The m(t) reduction rates of pure MgB₂ powder samples and diluted water-treated MgB₂ powder samples decreased to about 0.7 ~ 1.8% and 0.6 ~ 1.0% for about 7200 s, respectively, at temperature T = 15 K. The magnetic relaxation properties of the two types of MgB₂ powders were analyzed by calculating the magnetic relaxation rate S = -dln(M_irr)/dln(t) values according to Anderson-Kim theory. The magnetic relaxation ratio S values of the two types of MgB₂ powder samples were almost similar. As a result of the quantum creep effect, the constant magnetic relaxation rate S characteristic was confirmed at a temperature range of T = 10 K or less.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제30권6호
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• pp.455-464
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• 2004

The purpose of this study was to evaluate and compare the influence of Steroid topical irrigation and implant surface on bone healing in the irradiated rabbit tibia. Implant to bone contact surface ratio and the pattern of bone healing around hydroxyapatite(HA) coated implant and pure titanium (Ti) implant which were inserted into the irradiated rabbit tibia were compared. 16 Korean house mature male rabbits were used as experimental animal. Each rabbit received 15 Gy of irradiation. 4 weeks after the irradiation, two holes were prepared in the irradiated tibia of each rabbits, where two surface type of implants were inserted :1) HA coated type and 2) pure Ti type. Right before placing implants, one group of rabbit received steroid irrigation and the other group did saline. After the irrigation, two implants of HA coated type and pure Ti type were inserted into the tibia of each rabbits. Each rabbit were sacrificed at 2nd, 4th, and 8th week after the implantation and the specimens were observed by the light microscope. The pattern of bone healing and histomorphometric analysis of the implant-bone interface were done. The results were as follows. 1. All implants inserted into the irradiated tibia of rabbit did not show any sign of clinical mobility and the bone around implants inserted into the irradiated tibia of rabbit did not show any resorption. 2. The bone to implant contact surface ratio around HA coated implants that received steroid irrigation got more bone to implant contact surface ratio than that of the saline irrigation. This result showed statistically significant(p<0.05). There was no statistically significant difference in 8th week group. 3. Though there was no statistically significant difference HA coated implants had more bone to implant contact surface ratio than pure Ti implant in 2nd and 4th groups, and there was no difference in 8th week group. 4. All implants inserted into the irradiated tibia of rabbit had exhibited successful osseointegraion.

• 한국해양공학회지
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• 제12권2호통권28호
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• pp.57-64
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• 1998

This study is concerned with criterion for membrane to shell conversion in two-dimensional elastic-plastic finite element analysis using membrane/shell mixed element. It is well known that in the sheet metal forming some parts of the sheet deform under almost pure stretching (membrane) conditions, whereas other parts in contact with sharp tooling surfaces can develop significant bending strains. The membrane analysis has a short computational time however, in the membrane analysis the bending effects can not be condidered at all. On the other hand, the shell analysis allows the consideration of bending effects, but involves too much computational time. So Onatel),2), Yang et al3),4) developed the membrane/shell mixed element. Onate introduced the energy ratio parameter and Yang et al introduced the ratio of thickness to radius of curvature as the criterion. In the present study we propose a new criterion by using the angle between both side elements in the nodal point.

• 한국약용작물학회지
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• 제20권3호
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• pp.159-164
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• 2012

In this study, we investigated the antibacterial activity, antioxidative activity and whitening effect of 75% ethanol extracts from different parts of Prunus sargentii. The total phenolic compound content of the branch extract was 277.92 mg/g as the highest level. In the measurement of DPPH radical scavenging ability, $SC_{50}$ values of the cork layer and branch extract were 26.79 ${\mu}g/m{\ell}$ and 30.13 ${\mu}g/m{\ell}$. In nitric oxide (NO) scavenging ability, $SC_{50}$ values of the branch and leaf extract were 49.19 ${\mu}g/m{\ell}$ and 55.55 ${\mu}g/m{\ell}$. All extracts exhibited higher NO scavenging ability than ascorbic acid used as positive control. On the other hand, in antibacterial activity against Staphylococcus epidermidis and Staphylococcus aureus by disc diffusion assay, the pure bark extract showed the highest activity. Moreover, tyrosinase inhibitory activity of cork layer, pure bark and branch extracts showed higher activity than arbutin used as positive control. In the cytotoxicity measurement by MTT assay, leaf extract was exhibited Raw 264.7 cell viabilities of 44.68~61.83% as cytotoxic result in tested concentration. In conclusion, the branch extract of Prunus sargentii will be a functional materials without damage compared to other parts such as pure bark or cork layer in the plant.

• 한국가스학회지
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• 제10권1호
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• pp.38-42
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• 2006

본 연구에서는 순수한 프로판 냉매를 사용하여 액화석유가스(LPG)를 액화 및 냉동 저장할 수 있는 냉동 사이클에 대한 모사기법을 소개하였다. 프로판을 액화시키기 위한 2차 냉매로써는 물을 사용하였다. 전체 냉동 사이클의 모사를 위한 열역학 모델로서는 Peng-Robinson 상태방정식을 사용하였다. 프로판 성분과 LPG구성성분의 증기압의 좀 더 정확한 추산을 위하여 Twu 등이 제안한 새로운 alpha function을 사용하였다. 또한 액상의 밀도를 정확하게 추산하기 위해서는 Peng-Robinson상태방정식 대신에 API모델식을 사용하였다. 모사를 위하여 Simulation Science사의 PRO/II with PROVISION version 7.1 범용성 화학공정 모사기를 사용하였다 본 연구를 통하여 국내에서 실제로 가동되고 있는 LPG 저장을 위한 냉동 사이클을 성공적으로 모사할 수 있었다.

• 대한금속재료학회지
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• 제46권9호
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• pp.545-553
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• 2008

Dynamic deformation behavior of ultra-fine-grained pure coppers fabricated by equal channel angular pressing (ECAP) was investigated in this study. Dynamic torsional tests were conducted on four copper specimens using a torsional Kolsky bar, and then the test data were analyzed by their microstructures and tensile properties. The 1-pass ECAP'ed specimen consisted of fine dislocation cell structures elongated along the ECAP direction, which were changed to very fine, equiaxed subgrains of 300~400 nm in size as the pass number increased. The dynamic torsional test results indicated that maximum shear stress increased with increasing ECAP pass number. Adiabatic shear bands were not found at the gage center of the dynamically deformed torsional specimen of the 1- or 4-pass ECAP'ed specimen, while some weak bands were observed in the 8-pass ECAP'ed specimen. These findings suggested that the grain refinement according to the ECAP was very effective in strengthening of pure coppers, and that ECAP'ed coppers could be used without serious reduction in fracture resistance under dynamic torsional loading as adiabatic shear bands were hardly formed.

• Journal of Gastric Cancer
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• 제15권2호
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• pp.105-112
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• 2015

Purpose: Intracorporeal anastomosis is the most difficult procedure during pure single-incision distal gastrectomy (SIDG) that affects its generalization. We introduced unaided delta-shaped anastomosis (uDelta), a novel anastomosis technique, for gastroduodenostomy after pure SIDG, and compared the results with those of previously reported Roux-en-Y anastomosis (RY). Materials and Methods: Between March 2014 and March 2015, SIDG with D1+ lymph node dissection was performed for early gastric cancer through a 2.5-cm transumbilical incision without any additional port. uDelta was performed by the operator alone, without any intracorporeal assistance. Results: uDelta was performed on 11 patents, and uncut RY was performed on 5-patients without open or multiport conversion. R0 resection was performed in all cases. No significant differences were observed in mean age and body mass index between patients who underwent uDelta or RY. Mean operation times were $214.5{\pm}36.2$ minutes for uDelta and $240.8{\pm}65.9$ minutes for RY, which was not significantly different. Reconstruction time for uDelta was shorter than that for RY, with marginal statistical significance ($26.1{\pm}8.3$ minutes vs. $38.0{\pm}9.1$ minutes, P=0.05). There were no intraoperative transfusions, 30-day mortality, or anastomosis-related complications in either group. Average length of hospital stay was $8.2{\pm}1.9$ days in the uDelta group and $7.2{\pm}0.8$ days in the RY group (P=0.320). Conclusions: After carefully considering indications, uDelta can be a feasible and can be a reproducible reconstruction method after SIDG in early gastric cancer.

• 자원리싸이클링
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• 제1권1호
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• pp.69-77
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• 1992

본 연구는 충주 동양 골석광산에서 사분 및 수선처리하고 버려지는 저온위의 백운암질 골석정광을 회수할 목적으로, 이 광산에서 산출되는 비교적 순수한 골석과 백운석에 대한 부선특성을 조사하고, 이를 기초로 상기 골석광미 시과에 대한 Batch 부선실험을 행하였다. 그 결과를 요약하면 다음과 같다. 1) 비교적 순수한 골석 부선시에는 여러가지 기포제 중에서 Dowfroth 250을 사용하는 것이 가장 효과적이었으며, 그 사용성은 본 실험조건에서 50mg/l(200g/t)정도이다. 2) 골석 부선시 기포제로서 Dowfroth 250을 사용하는 경과, 적당한 광액의 pH는 pH6~pH9의 범위이다. 3) 저온위의 백운암질 골석광미로 부터 골석을 부선 할 경과 본 실험의 조건 하에서 회수 가능한 골석정광의 품위는 CaO 1,.40%, 백색도 84.5 로서 이때의 실수율은 53% 정도였다.