Determination of Kinetic Parameters of Growth and Carotenogenesis in the Red Yeast Xanthophyllomyces dendrorhous

박기문,Min Woo Song,이재흥 한국생물공학회 2009 Biotechnology and Bioprocess Engineering Vol.14 No.4

Glucose-limited continuous culture experiments with Xanthophyllomyces dendrorhous ATCC 24202 were carried out in a 2.5 L jar fermentor at 20o C and pH 4.5. A reciprocal plot of the steady-state data at a dilution rate of 0.037~0.096 h-1 was used to estimate a maximum specific growth rate constant of 0.11 h-1 and a Monod constant of 260 mg/L. The degree of carotenogenesis in X. dendrorhous was also investigated in terms of the residence time, which is the reciprocal of the dilution rate. The carotenoid content related to the residence time appeared to assume a typical form of saturation kinetics. The maximum carotenoid content for the strain was estimated to be 0.6 μg/mg dry cell weight. The saturation constant, which was tentatively defined in this work, was found to be 7.2 h.

다층 플럭스코아드아크 용접한 API 2W Gr.50 강재의 피로균열전파의 시험편간 변동

손혜정(Hye-Jung Sohn),공유식(Yu-Sik Kong),김선진(Seon-Jin Kim) 대한조선학회 2011 대한조선학회 학술대회자료집 Vol.2011 No.6

Flux Cored Arc Welding (FCAW) is a common practice to join the thick plate such as structural members of large scale offshore structures and very larger container ships. The objective of this paper is to investigate the statistical variability of fatigue crack growth rate for FCAWwd API 2W Gr.50 TMCP steel weldment typically applied for offshore structures. Experimental fatigue crack growth tests were performed on ASTM standard CT specimens. The assessment of the statistical distribution of fatigue crack growth experimental data was studied. The results indicates that the material properties, the three different zones WM, HAZ and BM have strong dependency on inter-specimen variability of the fatigue crack growth.

에탄올 생산 균주 Saccharomyces cerevisiae ATCC 248858의 비성장속도에 관한 수학적 모형연구

김휘동,허병기 한국생물공학회 1998 KSBB Journal Vol.13 No.6

An이ew식과 Aiba삭을 조합하여 에탄올 생산단주인 Saccharomyces cerevisiae ATCC 24858의 비성장속도를 당농도와 에탄올 농도의 함수로 표현하였다. 기침의 저해영향을 받지 않는 최대 당농도 $S_m$은 150 g/L이며 기질의 저해영향은 기질농도 S와 $S-S_{max}$항의 함수로 표현되었다. 최대 비성장 속도 ${\mu}max 는 0.49 hr^{-1}, Monod상수 K_s$는 19 g/L, Andrew식의 기질저해상수 $K_1$는 139 g/L이였다. 또한 비성장속도에 영향을 마치지 앓는 최대알콜농도 Pm이 존재하였으며 그 값은 2 g/L 이였다. 따라서 Aiba식에서 비성장속도에 영향을 미치는 에탄올 농도항은 P-Pm으보 표현되었다. 본 연구의 알코올생산균주에 대한 비성장속도의 완성된 수식은 디음과 같으며 이 수식에 위한 계산값은 평균오차 6% 내외의 범위에서 실험값과 일치하였다. The mathematical model of specific growth rate of Saccharomyces cerevisiae ATCC 24858 is proposed as a function of sugar and ethanol concentrations by the combination of Andrew's equation and Aiba's equation. The maximum concentration of sugar Sm, which was the highest concentration of sugar not having any effect on the growth inhibition, was 150 g/L and the substrate inhibition was expressed as a function of (S-Sm). The maximum specific growth inhibition, was 150 g/L and the substrate inhibition was expressed as a function of (S-Sm). The maximum specific growth rate ${\mu}m$, Monod's constant Ks, and Andrew's inhibition constant KI were 0.49 hr-1, 19 g/L, and 139 g/L, respectively. The maximum ethanol concentration, Pm, which did not show any inhibition effect on the specific growth rate was found to be 2 g/L. Therefore, the ethanol inhibition was represented as a function of (P-Pm). The final mathematical model for the specific growth rate of the microorganism in this work is proposed as the following. And the average percent of errors between the calculated specific growth rate and the experimental values was 5.96%.

Nb/Fe-C-(Si) 주조접합재에서 등온열처리시 계면반응층의 성장에 관한 연구

정병호 ( Jeong Byeong Ho ),김무길 ( Kim Mu Gil ),정상훈 ( Jeong Sang Hun ),박홍일 ( Park Hong Il ),안용식 ( An Yong Sig ),이성열 ( Lee Seong Yeol ) 한국열처리공학회 2003 熱處理工學會誌 Vol.16 No.5

N/A In order to study the interfacial reaction between Nb thin sheet and Fe-C-(Si) alloy with different chemical compositions, they were case-bonded. The growth of carbide layer formed at the interface after isothermal heat treatment at 1173K, 1223K, 1273K and 1323K for various times was investigated. The carbide formed at the interface was NbC and the thickness of NbC layer was increased linearly in proportional to the heat treating time. Therefore, It was found that the growth of NbC layer was controlled by the interfacial reaction. The growth rate constant of NbC layer was slightly increased with increase of carbon content when the silicon content is similar in the cast irons. However, as silicon content increases with no great difference in carbon content, the growth of NbC layer was greatly retarded. The calculated activation energy for the growth of NbC layer was varied in the range of 447.4-549.3kJ/㏖ with the compositions of cast irons.

다층 플럭스코아드아크 용접한 API 2W Gr. 50 강재의 피로균열전파율의 변동성 고찰

손혜정(Hye-Jeong Sohn),김선진(Seon-Jin Kim) 한국해양환경·에너지학회 2012 한국해양환경공학회 학술대회논문집 Vol.2012 No.5

Most of the components of marine and offshore structures are subjected to cyclic loading during their service time due to action of seawater waves and the sea environment in general. Fatigue failures in these structures can take place at sites of high stress concentraction that can be classified into two major categories, that is, base material and weld jaints. However, tt is well known that a considerable amount of scatter is showen in experimental results relating to fatigue crack growth even under identical and constant amplitude cyclic loading conditions. And also, it is well known that the Flux Cored Arc Welding(FCAW) is a common practice to join the thick plate such as structural members of large scale offshore structures and very larger container ships. The objective of this study is to investigate the variability of fatigae crack growth arte (FCGR) for the FCAWed API 2W Gr. 50 steel weldment typically applied for offshore structures. In order to investigate clearly the variability of fatigue crack growth rate for the materials of three different zones WM, HAZ and BM, experimental fatigue crack growth tests for each five specimens were performed on ASTM standard compact tension (CT) specimens under constant amplitude cyclic loading. It was showen that the variability of FCGR for WM specimen was higher then those of HAZ and BM, espacially in low driving force regio, and the probability distribution of FCGR was followed well Weibull distribution.

FSW 용접한 Al 7075-T651 용접재의 피로균열전파의 실험적 고찰

손혜정(Hye-Jeong Sohn),김치옥(Chi-Ok Kim),김선진(Seon-Jin Kim) 대한조선학회 2011 대한조선학회 학술대회자료집 Vol.2011 No.6

The experimental investigation focuses on statistical variability of fatigue crack growth rate in friction stir welded Al 7075-T651 aluminum alloy on the three different zones, base meta (BM)l, weld metal (WM) and heat affected zone (HAZ). Friction stir welding is a new solid state joining method offering several advantages. The objective of this work is to investigate the fatigue crack growth rate behavior of FSWed 7075-T651 Al alloy under optimal FSW conditions. Fatigue crack growth tests were carried out on compact tension specimens (CT) under constant stress intensity factor range control according to ASTM standard. FCGR experiments were conducted at an Ratio of 0.1 and sinusoidal frequency of 10Hz with the three different zones specimens at constant stress intensity factor range 8, 11.5 and 15 MPa(m)1/2. The variability of fatigue crack growth rate showed strong dependency on three different zones WM, HAZ and BM.

강재의 피로균열전파율에 미치는 시험편 크기의 영향

김선진(SEON-JIN KIM),안석환(SEOK-HWAN AHN) 한국해양공학회 2000 韓國海洋工學會誌 Vol.14 No.2

This paper describes the effect of specimen size on fatigue crock growth rate for the offshore structural high-tensile-strength steel, BS4360 and machine structural steel, SM45C. The purpose of the present study is to investigate the effect of stress ratio, aspect ratio, specimen width and specimen thickness on the fatigue crack growth behavior. Compact tension specimens with a LT orientation for BS4360 and SM45C steels were used. All testing was done at constant stress intensity factor range controlled fatigue crack growth condition. The investigation demonstrates that the fatigue crack growth rate is increased with increasing stress ratio and specimen thickness, and is decreased with increasing specimen width. The fatigue crack growth rate is unaffected by aspect ratio until α/W=0.50, but is increased by increasing aspect ratio from α/W=0.55.

Mass dynamics of coarse woody debris in an old-growth deciduous forest of Gwangneung, Korea

윤태경,손요환,노남진,김래현,서경원,이수경,이궁,이임균,임종환 한국산림과학회 2011 Forest Science And Technology Vol.7 No.4

We investigated the mass dynamics of coarse woody debris (CWD) in an old-growth deciduous forest dominated by Quercus serrata, Carpinus laxiflora, and C. cordata in a 1 ha permanent plot of the Gwangneung Experiment Forest, Korea, from 2002 through 2010. CWD mass varied from 16.8 to 34.2 Mg ha71, and the ratio of CWD mass to stand biomass varied from 0.06 to 0.13. The mean CWD mass input and loss rates were 4.81 Mg ha71 yr71 and 2.28 Mg ha71 yr71, respectively. A large heterogeneity of CWD mass, as represented by the spatial coefficient of variation (127.2%) and annual coefficient of variation (178.5%), might be inherent in the old-growth temperate forest, which consisted of large biomass trees. The decay rate constant, as estimated from the wood density change, was 0.049 yr71. However, the large variation of annual CWD mass input could cause the overestimation of decay rate constant (0.167 yr71) as calculated from the ratio of CWD mass input to CWD mass. According to the CWD decay class classification, class II (72.8%) comprised the majority of CWD mass. The proportion of CWD mass to total CWD mass was 57.5% for Q. serrata, 25.0% for C. laxiflora, and 10.4% for C. cordata, respectively, and corresponded to the proportion of stem biomass to total stem biomass. These data support the stability of the current status in this old-growth deciduous forest as representing the climax stage. Due to the relatively short-term measurement of CWD mass compared with the whole life span of CWD, additional long-term studies with various approaches are required to enhance the knowledge of CWD mass dynamics in this forest.

Experimental study on the transition to turbulence in secondary acoustic instability in a quarter wavelength resonator

임대원,윤성환 한국마린엔지니어링학회 2023 한국마린엔지니어링학회지 Vol.47 No.6

This study explores the intricate dynamics of secondary acoustic instability within a quarter-wavelength resonator, with a specific focus on the interplay between pressure coupling constant (βM) and flame behavior. Experimental results reveal a strong correlation between key parameters, (growth rate) and (decay rate), with βM, shedding light on the mechanisms governing sec-ondary acoustic instability. The flame thickness reduction, observed as βM increases, amplifies the flame front's susceptibility to pres-sure and temperature perturbations. This heightened sensitivity triggers rapid secondary acoustic instability, characterized by increased in the amplification zone. Simultaneously, the absolute value of in the damping zone decreases, emphasizing the pivotal role of βM in shaping these dynamic behaviors. The observed trends underscore βM's significant influence on the growth and decay rates, contributing to a comprehensive understanding of the complex thermos-acoustic phenomena.

Physiochemical Characteristics of Lactobacillus acidophilus KH-l Isolated from the Feces of a Breast-Fed Infant

Yu, K.H.,Kang, S.N.,Park, S.Y. The Korean Society of Food Science and Nutrition 2005 Preventive Nutrition and Food Science Vol.10 No.4

Three lactobacillus strains, two from infant feces, and one from cow's milk, were selected among 172 isolates, from multiple sources, for further study based on the antimicrobial activities against six strains of pathogenic bacteria and identified as Lactobacillus acidophilus. The strains revealed a wide scope of spectrum against pathogenic bacteria. Viable Lactobacillus acidophilus KH-l cell counts at pH 2.0 were slightly decreased to $1.42\times10^7$ CFU/mL from $4.18\times10^7$ CFU/mL, while remaining at $3.42\times10^7$ CFU/mL at pH 4.0 with the survival rate of $33.97\%\;and\;81.82\%$, respectively. At the concentration of $0.1\%$ oxgall, L acidophilus KH-l kept growing up to $3.12\times10^7$ CFU/mL with a mean growth rate constant (k) of 0.25, and cell number was slightly decreased to $1.21\times10^7$ CFU/mL (k=0.19) with $0.3\%$ oxgall, but remained at $7.6\times10^6$ CFU/mL (k=0.17) with $0.5\%$ oxgall. L. acidophilus KH-l had a $D_{60}$ value of 7.14, with viable cell numbers $1.4\times10^5$ CFU/mL after heat treatment at $60^{\circ}C$ for 30 minutes. Stability of L acidophilus KH-l at $-20^{\circ}C$ was significantly higher, when the strain was cultivated under the optimum growth temperature $(54.41\%\;and\;54.35\%)$ than at the temperature $(13.53\%)$.