• Microbiology and Biotechnology Letters
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• v.38 no.3
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• pp.273-277
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• 2010

Undecylprodiginine and streptorubin B are red-pigmented antibiotics produced by Streptomyces coelicolor A3(2). In this study, we investigated the correlation between productivity of these red-pigmented antibiotics and stress of pH shock. Biosynthesis of these red-pigmented antibiotics is enhanced at acidic pH shock on solid R2YE medium. The optimal pH shock is pH 4 which led to 1.6 fold and two-fold increase in the production of undecylprodiginine and streptorubin B as compared with control, respectively. In addition, the extract of pH 4 shocked cells exhibited a remarkable activity against Trichophyton mentagrophytes. However, neutral and basic pH shock did not give raise to promote a production of these red-pigmented antibiotics as well as antifungal activity. Thus, although the acidic pH shock is simple and easy method, it should be extremely effective approach to enhance a productivity of these red-pigmented antibiotics and other secondary metabolites.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.15 no.3
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• pp.60-67
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• 2016

In cumulative transfer functions, as number of transfer increase, the impact of individual transfer to transfer cost increase linearly or non linearly. This function can effectively explain various passengers's travel behavior who choose their travel routes in integrated transit line networks including bus and railway modes. Using the function, it is possible to simulate general situations such that even though more travel times are expected, less number of transfer routes are preferred. However, because travel cost with cumulative transfer function is known as non additive cost function types in route search algorithms, finding an optimal route in integrated transit networks is confronted by the insolvable enumeration of all routes in many cases. This research proposes a methodology for finding an optimal path considering cumulative transfer function. For this purpose, the reversal phenomenon of optimal path generated in route search process is explained. Also a heuristic methodology for selecting an optimal route among multiple routes predefined by the K path algorithm. The incoming link based entire path deletion method is adopted for finding K ranking path thanks to the merit of security of route optimality condition. Through case studies the proposed methodology is discussed in terms of the applicability of real situations.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2012.03a
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• pp.107-107
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• 2012

3종 복합소재인 양모와 나일론, 레이온의 염색공정은 먼저 알칼리 욕에서 반응성염료로 레이온을 염색한 후, 산성욕에서 산성염료로 양모와 나일론을 염색하는 것이 일반적이다. 그런데 양모, 나일론, 레이온은 알칼리에 민감하므로 면 염색 시 적용되는 강알칼리인 수산화나트륨을 사용하면 섬유의 취화로 인하여 강도와 촉감저하 등의 문제가 발생하게 된다. 따라서 본 연구에서는 알칼리 중 탄산나트륨과 중탄산나트륨을 사용하여 염료를 투입하지 않고 염색공정을 거친 후 백도와 인장강도를 측정하여 황변 및 강도 변화 여부를 알아보았다. 레이온 70%, 양모 19%, 나일론 11%의 혼용율을 가지는 전처리 된 편물(130$g/m^2$, 32 inch, 18 gauge)에 탄산나트륨(시약 1급) 20g/l과 중탄산나트륨(시약 1급) 20g/l 각각을 투입하고 반응성염색공정($60^{\circ}C$, 60 min)으로 처리한 경우와 반응성 염색 후 산성염색공정($98^{\circ}C$, 60 min)으로 처리한 경우로 나누어 측색을 통해 백도와 L, a, b값을 측정하고 KS K 0521에 따라 인장강도 시험을 실시하였다. 그 결과, 탄산나트륨 투입시 백도 값이 중탄산나트륨에 비해 10% 정도 낮아지고 L, a, b값도 상대적으로 yellow 방향으로 이동해 있는 것으로 나타났다. 이것은 황변이 일어남을 의미하며 육안으로 확인하였다. 또한 인장강도 측정결과를 통해 소다회 처리 시 중조에 비해 30% 정도의 강도 저하가 일어남을 확인할 수 있었다. 그러나 반응성염색 후 산성염색을 거치게 되면 황변과 강도 저하 현상이 회복되는 경향을 나타내었다. 즉, 천연/나일론 편물을 반응성염색 시 알칼리로 탄산나트륨을 사용하면 염색공정 상에서 중탄산나트륨에 비해 황변이 일어나 염료 고유의 색상 발현에 영향을 줄 수 있고 강도 또한 30% 정도 저하되지만, 후에 산성염색 공정을 거치면 산 조건과 욕중 효과를 통해 일부 개선됨을 확인하였다. 이와 별도로 이번에는 시판되는 반응성염료 5종과 산성염료 3종을 조합하여 탄산나트륨과 중탄산나트륨 투입에 따른 염색실험을 실시하고 측색(DataColor SF600 광원D65, Strength)을 통해 염착량을 비교하였다. 그 결과, 중탄산나트륨으로 염색하면 탄산나트륨에 비해 모두 염착량이 저하되었으며, 염료의 구조적 차이와 컬러별로도 그 차이는 다양하였다. 그 중 저온에너지형 반응성염료는 탄산나트륨 투입에 비해 47~60% 정도로 가장 양호하였으며, 일부 반응성염료는 20%까지 떨어지는 값을 나타내었다. 이것은 탄산나트륨보다 중탄산나트륨의 알칼리 정도가 낮으므로 반응성염료의 염착이 적은 것으로 생각되며, 저에너지형 반응성염료의 경우에는 낮은 온도나 알칼리 조건에서도 상대적으로 높은 고착률을 나타내므로 적절한 반응성염료의 선택을 통해 그 차이를 극복할 수 있을 것으로 사료된다. 이상의 결과를 통해 탄산나트륨과 중탄산트륨의 알칼리 정도가 강도와 염착량에 미치는 영향의 차이를 고려하여 최적의 현장 처방을 선정해야 함을 알 수 있었다.

• The Korean Journal of Ecology
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• v.16 no.4
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• pp.501-514
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• 1993

In order to study the ecotypic variation of Robinia pseudo-acacza L. distributed in southern area of Korean peninsula, 15 local populations(Daejin, Sokcho, Kangneung, Mt. Surak, Hongcheon, Kwangneung, Namhansanseong, Chungju, Yesan, Andong, Jeonju, Dalseong, Changweon, Mokpo and Wando), located from $34^{\circ}18'N\;to\;38^{\circ}36'N$, were selected based on their latitudes and geographical distances. Seeds of these populations were collected and their germination and growth of seedlings were investigated. The optimum temperature of seed germination tends to decrease with ascending latitudes. The optimum temperatures of local populations were classified into three types: the north central type of $25^{\circ}C$(Daejin, Sokcho, Kangneung, Mt. Surak, Hongcheon, Kwangneung), the south central type of $30^{\circ}C$(Narnhansanseong. Chungju, Yesan, Andong, Jeonju), and the southern type of $35^{\circ}C$(Dalseong, Changweon, Mokpo, Wando). The optimum temperature for the growth of seedlings was $25^{\circ}C$ for all populations. The populations were also classified into three types : north central type, south central type and southern type based on the ranking on the growth of seedlings at 5 different temperatures of 15, 20, 25, 30 and $35^{\circ}C$, and the results of seedling growth showed similar patterns to those of the seed germination.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.8
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• pp.1296-1303
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• 2014

This study was conducted to develop predictive models for the growth of Bacillus cereus on carrot treated with slightly acidic electrolyzed water (SAcEW) and ultrasonication (US) at different storage temperatures. In addition, the inactivation of B. cereus by US with SAcEW was investigated. US treatment with a frequency of 40 kHz and an acoustic energy density of 400 W/L at $40^{\circ}C$ for 3 min showed the maximum reduction of 2.87 log CFU/g B. cereus on carrot, while combined treatment of US (400 W/L, $40^{\circ}C$, 3 min) with SAcEW reached to 3.1 log CFU/g reduction. Growth data of B. cereus on carrot treated with SAcEW and US at different temperatures (4, 10, 15, 20, 25, 30, and $35^{\circ}C$) were collected and used to develop predictive models. The modified Gompertz model was found to be more suitable to describe the growth data. The specific growth rate (SGR) and lag time (LT) obtained from the modified Gompertz model were employed to establish the secondary models. The newly developed secondary models were validated using the root mean square error, bias factor, and accuracy factor. All results of these factors were in the acceptable range of values. After compared SGR and LT of B. cereus on carrot, the results showed that the growth of B. cereus on carrot treated with SAcEW and US was slower than that of single treatment. This result indicates that shelf life of carrot treated with SAcEW and US could be extended. The developed predictive models might also be used to assess the microbiological risk of B. cereus infection in carrot treated with SAcEW and US.

• 한국생물공학회:학술대회논문집
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• 2002.04a
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• pp.534-537
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• 2002

An agarase gene from Bacillus cereus ASK202 was expressed in high levels by E. coli BL21(DE3)/pEBA1 using pET28a(+) vector system with the inducible T7 promoter in the presence of isopropyl- ${\beta}$ -thiogalactopyranoside. The open reading frame encodes 761 amino acid residues with a calculated molecular weight of 83,300 daltons and a potential signal peptide about 36 amino acid residues at the N-terminus. E. coli BL21(DE3)/pEBA1 produce 1280 unit/ ${\ell}$ of agarase. The optimum physical condition for the agarase activity was pH 5.6, and $40^{\circ}C$, respectively. The agarase activity was stable up pH $4.0{\sim}9.0$ and $4{\sim}40^{\circ}C$. The km and maximum rate of metabolism for agar were 0.068mg/$m{\ell}$ and 0.094mg/$m{\ell}{\cdot}min$, respectively.

• Journal of Life Science
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• v.7 no.3
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• pp.228-233
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• 1997

A thiol protease has been isolated and partially purified from encysted brine shrimp Artemia franciscana using a four-step procedure(filtration, salting out, gel filtration and ion exchange chromatography). The optimum pH of the enzyme for caseinolytic activity was appeared to be 3.0, and the enzymematic activity was stable up to pH 6.0 but lost completely at the pH higher than 8.0. The optimal temperature of the enzyme was appeared to be 35$^{\circ}$C, and ninety percent of the enzyme activity was lost at 45$^{\circ}$C. Various metal ions, e.g., zinc, copper, iron, inhibited the enzyme activity; however, heavy metal chelator, e.g., EDTA, stimulated the enzyme activity. The protease was concluded to be a member of the thiol group protease, since it was inhibited by thiol protease inhibitors and iodoacetate. The protease was also concluded to be a acid protease based on optimum pH.

• Applied Biological Chemistry
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• v.36 no.5
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• pp.370-375
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• 1993

Five electrophoretic bands of crude enzyme extracted from rice leaves were found to possess both chitinase and ${\beta}-1,3-glucanase$ activities. These $chitinase/{\beta}-1,3-glucanase$ were resolved into acidic and basic fractions of protein by DEAE-cellulose and chitin affinity column chromatography. The optimal pH and temperature for ${\beta}-1,3-glucanase$ activity of two fractions were in the same extent as pH 5 and $60^{\circ}C$, whereas those for chitinase activity differed from one another; pH 3 and $60^{\circ}C$ for the acidic and pH 4 and $50^{\circ}C$ for the basic fraction, respectively. In addition, lysozyme activity was found in both fractions.

• Journal of Korean Society of Transportation
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• v.34 no.6
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• pp.570-579
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• 2016

This study proposes a concept of Stepwise Transfer Coefficient(STC) which implies greater transfer cost with increasing the number of transfers. Thus, the public transport information system provides the choice sets of travel routes by the consideration of not only transportation time but also the optimum number of transfers. However, path choice problems that involve STC are found to include non additive cost, which requires additional route enumeration works. Discussions on route enumeration in actual transportation networks is very complicated, thereby warranting a theoretical examination of route search considering STC. From these points of view, this study results in a probability based transit trip assignment model including STC. This research also uses incoming link based entire route deletion method. The entire route deletion method proposed herein simplifies construction of an aggregation of possible routes by theoretically supporting the process of enumeration of the different routes from origin to destination. Conclusively, the STC reflected route based logit model is proposed as a public transportation transit trip assignment model.

• Applied Chemistry for Engineering
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• v.10 no.2
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• pp.218-224
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• 1999

Continuous ion exchange characteristics of the synthetic coolant contained Ni, Co and Ag ions of low concentration in acidic-oxidizing conditions have been studied to suggest the guideline for the optimum operation of mixed-bed demincralizer during the shutdown period of a pressurized water reactor (PWR). In the effect of the form of cation resins on the removal capacity of metal ions, the performance of a $H^+$-form resin was about 6% higher than that of a $Li^+$-form resin. Mixed-bed of cation and anion resins in comparison with nonmixed-bed of them, had no affected on the removal capacity of metal ions but very slightly increased the slope of breakthrough curves of metal ions. In the effect related to acidic-oxidizing conditions of the coolant, the addition of boric acid very slightly decreased the slope of breakthrough curves of metal ions, while the addition of hydrogen peroxide slightly decreased the removal capacity of metal ions.