• Korean Journal of Food Science and Technology
• /
• v.15 no.1
• /
• pp.56-61
• /
• 1983

Direct production of biomass from starch using amylolytic yeast, Sporobolomyces holsaticus FRI Y-5 was studied with varying the ratios between carbon and other nutrient sources in the medium. It was investigated under condition of constant C/P and C/S ratio to influence the initial concentration of starch $(S_o)$ and C/N ratio on its growth which is described as the specific growth rate $({\mu})$, cell yield (Y), the maximum concentration of cell $(X_m)$, and productivity (P). They were very dependent on both $S_o$ and C/N ratio. The form of the relationship between and ${\mu}$ and $S_o$ was observed to be similar to saturation kinetics at C/N = 100 but presented substrate inhibition at other C/N ratios. As $S_o$ was changed from 22.5 to 90 g/l, Y was observed to vary with C/N ratios but seemed to decrease as a wholes. $X_m$ was linearly related to $S_o$ at more than C/N = 50 but at less than C/N = 10 substrate inhibition was presented. P increased suddenly to $S_o$ = 45 g/l and then changed decreasingly at less than C/N = 50, but at more than C/N = 100 it changed increasingly. The effect of C/P ratio and C/S ratio on the yeast growth was also investigated at constant $S_o$ and C/N ratio. ${\mu}$ was dependent on C/P and C/S ratios, but Y, independent on them. But $X_m$ was reliant upon C/P ratio but not upon C/S ratio.

• Journal of Korean Society of Water and Wastewater
• /
• v.26 no.6
• /
• pp.825-831
• /
• 2012

The retrofitting of a thickening unit process is widely considered in municipal wastewater treatment plants in Korea to enhance the anaerobic digestion efficiency. The authors examined the effect of feed concentration (2-34.1 g VS/L) and feed to microorganism (F/M) ratio (0.50-1.35 g VS/g VS) on anaerobic batch digestion of sewage sludge. Methane yield over 90 mL $CH_4/g$ $VS_{feed}$ was found at a feed concentration in the range of 12-26 g VS/L and a F/M ratio below 0.6 g VS/g VS. A high F/M ratio decreased methane yield and rate with oragnic acid accumulation. As sudden increase of sewage sludge concentration prior to anaerobic digestion would jeopardize the digester performance due to the rasied F/M ratio, gradual increase of the sludge feed concentration or an additional biomass retention in the digester is recommended.

• KSBB Journal
• /
• v.9 no.4
• /
• pp.365-371
• /
• 1994

The effects of ratios of initial concentration of carbon source to the initial concentration of nitrogen source in the fermentation media on both the yields of PHB fermentation variables and the accumulation of poly-${\beta}$-hydroxybutyric acid(PHB) were investigated. The fermentation media were composed of the combination of varing glucose concentrations, 10, 20, 25, 30, 40, $50g/\ell$ and the NH4Cl concentrations 0.33, 0.4, 0.5, 1.5, 3, $5g/\ell$. The yield of biomass on glucos, Yx/s, decreased very slowly according to the increase of the ratio of C to N. And the yield became constant at 0.35(g biomass/g glucose) with the ratio higher than 70. The yield of residual biomass, Yx/s, also decreased with the ratio of C to N and finally showed a constant value of 0.065(g residual biomass/g glucose) when the ratio was higher than 65. In accordance with the augmentation of the ratio, the yield of PHB, YPHB/S, however, increased and showed the maximum value of 0.35 (g PHB/g glucose) between 40 and 60 of the ratio. The maximum yield of PHB to the change of biomass, YPHB/S, was 0.87(g PHB/g biomass), and the yie1d YPHB/RX, was 4.2(g PHB/g residual biomass). The maximum accumulation percent of PHB to the final biomass was 81% when the ratio was higher than 67.

• Journal of Nutrition and Health
• /
• v.16 no.3
• /
• pp.200-208
• /
• 1983

The present studies were designed to compare the effects of both dietary fat levels and P / S ratio on lipid components in plasma and tissues. Changes in plasma HDL-cholesterol, cholesterol and TG, and also in tissue cholesterol and TG were determined in young rats fed diets providing total dietary fat as 10%, 25% or 45% of calories and P / S ratio as 0.2 or 4.0. Plasma cholesterol levels were getting higher as dietary fat levels increased at P / S 0.2. Plasma cholesterol was lower in rats fed dietary fat either 25% or 45 %, each with P / S 4.0. But at 10% no change in plasma cholesterol were observed by P / S 4.0 because of a possible insufficiency of the absolute amount of PUFA. HDL-cholesterol was rather less sensitive to the modification of dietary fat level, but was reduced in rats fed diets of P / S 4.0 at either 25% or 45% fat, even though HDL-cholesterol were increased in the group of 10% with P / S 0.2. Total cholesterol per g- liver were significantly increased as dietary fat levels increased. Liver cholesterol levels were higher in rats fed diets of P / S 4.0 at higher fat levels (25% or 45%) which possibly suggested that a reduction of plasma cholesterol by high PUFA diet was not at least from a decreased synthesis of cholesterol in liver. However, in muscle no significant differences were found by feeding high P / S ratio at each levels of fat. At 10% fat level, compared to 25% or 45%, cholesterol level was lower in g-liver but higher in g- muscle. Plasma TG was decreased as more dietary fat were supplied at P / S ratio, but no consistant response obtained at low P / S ratio. TG per g-liver were reduced by feeding P / S 4.0 diet at 10% or 45% fat level but no differences were found in muscle. P / S 4.0 diet was more efficient in lowering plasma cholesterol TG and HDL-cholesterolt levels only if fat level was more than 25% of the total calories And young rats were more resistant to dietary fat modification.

• Geomechanics and Engineering
• /
• v.24 no.1
• /
• pp.57-65
• /
• 2021

The effects of initial soil fabric and aspect ratio (AR) on the small-strain stiffness (G0) of granular soils are studied by employing discrete element method (DEM) numerical analysis. Elongated clumps composed of subspheres were adopted, and the G0 values were obtained by DEM simulations of drained triaxial tests under different densities and initial confining pressure (p0). The DEM simulations indicate that the initial soil fabric has an insignificant effect on G0. The effect of the AR on G0 is related to the initial density. Namely, for dense specimens, G0 first increases with increasing AR, reaching a plateau value when the AR ≥ 1.5. However, for loose specimens, G0 gradually increases as the AR increases. Microscopic examination reveals that G0 uniquely depends on the coordination number of the particles (CN-particle) rather than the subspheres (CN-sphere) at the particulate level for the effects of initial soil fabric and AR. Finally, Poisson's ratio ν0 is also determined by CN-particle. In addition, based on data in literature and this study, ν0 can be fitted as ν0 = 5.920(G0/(p0)1/3)-0.99, which can be used to predict ν0 of granular soils based on the measured G0.

• Journal of Periodontal and Implant Science
• /
• v.29 no.1
• /
• pp.251-264
• /
• 1999

본 연구는 조기발병형 치주염의 서로 다른 4가지 표현형에 있어서 Porphyromonas gingivalis(Pg) 381과 Actinobacillus actinomycetemcomitans(Aa) Y4에 대한 상승된 IgG subclass의 양상을 평가하기 위해 시행하였다. Subform I(distinctive localized juvenile periodontitis pattern)에서 3명 subform II(post juvenile periodontitis pattern)에서 19명, subform III (localized but rapidly progressing pattern)에서 15명, subform IV(distinctive rapidly progressing periodontitis pattern)에서 15명의 환자를 조사하여 Pg에 대한 그들의 total IgG level과 각각의 IgG subclass level 및 Aa에 대한 IgG level을 검사했다. Pg에 대한 total IgG level은 subform II와 IV보다 subform I과 III에서 훨씬 높게 나타났다. IgG3 level이 subform I과 IV사이에서 현저한 차이가 있다는 점을 제외하고는, 다른 IgG subclass level에서 subform 사이에 아무런 차이가 없었다. Pg에 대한 IgG subclass는 single class 혹은 다양한 group에서 상승되어 나타났으며, IgG1+2+4가 가장 흔하게 발견되었고, 다음으로 IgG4 단독, IgG2 단독, IgG2+4, IgG2+3+4의 순으로 발견되었다. IgG2와 IgG4가 빈번히 상승되어 발견되었는데, 특히 severe form(subform III & IV)에서 그러했다. 뿐만 아니라, IgG level은 subform II, III, IV와 일치하여 점차적으로 증가하였고, 반면에 IgG1/IgG4 ratio는 그와 일치하여 감소되었다. 이러한 ratio의 감소는 단백질성의 오래된 항원의 과부하로 인해 immunoglobulin gene의 전환을 가능하게 한다는 것을 나타내고 있다. Aa에 대한 IgG2 level은 다른 유형보다 subform I에서 상당히 높았다. Pg에 대한 IgG2 levels이 subform I의 국소 부위에서 발생하는 disease activity와 밀접한 관련이 있으며, Aa의 경우에는 이러한 관련성이 나타나지 않았다. Pg에 대한 IgG2 level은 18-25세에서 훨씬 높은 동시에 26-35세에서는 감소했으며 결국 30대 후반에서는 더 높은 수치로 되돌아갔다. 이러한 결과는 Pg에 대한 IgG2 및 IgG responsiveness (single 혹은 combined)가 EOP의 severe form의 발달에 중요하게 작용하며 IgG2 levels은 IgG1/IgG4 ratio와 더불어 EOP의 localized type이 generalized type으로 계속 진행하는 것을 조절하는 역할을 하는 것으로 보인다는 것을 강하게 시사하였다.

• Advances in concrete construction
• /
• v.7 no.2
• /
• pp.97-105
• /
• 2019

In this paper, the workability and static stability were evaluated using a proposed test method. Workability and static stability represent a key property of self-compacting concrete (SCC) in fresh state. A number of standardized test methods were developed to assess these properties. However, no accelerated test method reliably predicts both workability and static stability of SCC. In the present work, a modified K-slump test method was developed to evaluate workability and static stability of SCC. In order to take implicit mixture variations of SCC constituents that can affect fresh SCC properties, a central composite design was adopted to highlight the effect of gravel to sand ratio (G/S), gravel 3/8 to gravel 8/15 ratio (G1/G2), water to cement ratio (W/C), marble powder to cement ratio (MP/C) and superplasticizer content (SP) on workability measured with slump and flow time (T50) tests and static stability measured with sieve stability test (Pi), segregation test index (SSI), Penetration test (Pd) and the proposed K-slump test (Km). The obtained results show that G/S ratio close to 1 and G1/G2 ratio close to 60% can be considered as optimal values to achieve a good workability while ensuring a sufficient static stability of SCC. Acceptable relationships were obtained between Slump flow, Pi, Pd and Km. Results show that the proposed K-slump test allow to assess both workability and static stability of fresh SCC mixtures.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2010.05a
• /
• pp.821-822
• /
• 2010

• Journal of the Korea Institute of Building Construction
• /
• v.4 no.2
• /
• pp.97-103
• /
• 2004

In this study, the experiment was carried out to investigate and analyze the influence of coarse aggregate's mix ratio and maximum size on the properties of concrete. The main experimental variables were water/cement ratio 45% and 65%, coarse aggregate/fine aggregate ratio 90%, 130% and 170%, maximum size of coarse aggregate 15mm, 25mm and 40mm. According to the test results, the principal conclusions are summarized as follows. 1) The slump and flow of fresh concrete were found to be higher in the order of G/S ratio 170%, 130%, 90%, also in the order of maximum size 40mm, 25mm, 15mm. 2) The compressive strength of hardened concrete were found to be higher in the order of G/S ratio 170%, 130%, 90%, also in the order of maximum size 15mm, 25mm, 40mm.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2002.05a
• /
• pp.69-74
• /
• 2002

The following results are achieved from a mortar flow test depending on stainless steel slag fineness, replacement ratio, and a research on material age compressive strength, strength activity index. 1. Flow is proportional to the stainless steel slag fineness within the limits of 4000~8000$\textrm{cm}^2$/g, but in the case of fineness 20000$\textrm{cm}^2$/g flow decreases at all conditions except the case of replacement ratio 10%. 2. As stainless steel slag replacement ratio increases, Mortar of flow somewhat decreases. 3. As stainless steel slag blends, compressive strength decreases, but in proportion to the increase of age, compressive strength increases. 4. As stainless steel slag replacement ratio, compressive strength decreases. 5. In the case of stainless steel slag fineness 6000$\textrm{cm}^2$/g and 20.000$\textrm{cm}^2$/g, compressive strength of revelation ratio has the maximum value when it's replacement ratio is 10%.