• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.23 no.1
• /
• pp.8-15
• /
• 2011

Cooling load reduction was analysed of a ventilation system adopting a regenerative evaporative cooler. The regenerative evaporative cooler is a kind of indirect evaporative cooler which cools the air down to its inlet dewpoint temperature in principle without change in the humidity ratio. The regenerative evaporative cooler was found able to cool the ventilation air to $18{\sim}21^{\circ}C$ when the outdoor condition ranges $25{\sim}35^{\circ}C$ and 0.01~0.02 kg/kg. When the outdoor humidity ratio is lower than 0.018 kg/kg, the regenerative evaporative cooler was found to provide cooling performance enough to compensate the ventilation load completely and to supply additional cooling as well. Energy simulation during the summer was carried out for a typical office building with the ventilation system using the regenerative evaporative cooler. The results showed that the seasonal cooling load can be reduced by about 40% by applying the regenerative evaporative cooler as a ventilation conditioner. The reduction was found to increase as the outdoor temperature increases and the outdoor humidity ratio decreases.

• Journal of Microbiology and Biotechnology
• /
• v.2 no.3
• /
• pp.166-173
• /
• 1992

The expression of Bacillus subtilis $\alpha$-amylase from the phoA-amyE fusion gene in recombinant E. coli was investigated under various environmental conditions. The overexpression of cloned $\alpha$-amylase caused retardations in cell growth and synthesis of alkaline phosphatase (AP) from the chromosomal phoA gene. The change of culture temperature from $37^\circ{C}$ to $30^\circ{C}$ increased the specific activities of both $\alpha$-amylase and $\beta$-lactamase by six and two times, respectively, whereas the AP activity remained unchanged. The experiments with chlorampenicol (a translation inhibitor) suggested the enhancement of $\alpha$-amylase activity at $30^\circ{C}$, and this was partly due to the stability of $\alpha$-amylase itself. The further decrease of the temperature to $25^\circ{C}$ slowed down both the cell growth and cloned-gene expression rate. The $\alpha$-amylase activity showed a maximum at pH of 7.4 while alkaline phosphatase was most effectively produced at pH of 8.3.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.22 no.10
• /
• pp.687-696
• /
• 2010

In this study, FDD algorithm was developed using the normalized distance method and general pattern classifier method that can be applied to constant air volume air handling unit(CAV AHU) system. The simulation model using TRNSYS and EES was developed in order to obtain characteristic data of CAV AHU system under the normal and the faulty operation. Sensitivity analysis of fault detection was carried out with respect to fault progress. When differential pressure of mixed air filter increased by more than about 105 pascal, FDD algorithm was able to detect the fault. The return air temperature is very important measurement parameter controlling cooling capacity. Therefore, it is important to detect measurement error of the return air temperature. Measurement error of the return air temperature sensor can be detected at below $1.2^{\circ}C$ by FDD algorithm. FDD algorithm developed in this study was found to indicate each failure modes accurately.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.22 no.8
• /
• pp.545-552
• /
• 2010

Research and development efforts to reduce $CO_2$ emission are in progress to cope with global warming. $CO_2$ emission from fossil fuel fired power plants is a major greenhouse gas source and the post-combustion $CO_2$ capture is considered as a short or medium term option to reduce $CO_2$ emissions. In this study, the application of the post-combustion $CO_2$ capture system, which is based on chemical absorption and stripping processes, to typical fossil fuel fired power plants was investigated. A coal fired plant and a natural gas fired combined cycle plant were selected. Performance of the MEA-based $CO_2$ capture system combined with power plants was analyzed and overall plant performance including the energy consumption of the $CO_2$ capture process was investigated.

• Microbiology and Biotechnology Letters
• /
• v.40 no.3
• /
• pp.220-225
• /
• 2012

In order to investigate the ethanol fermentation properties of alcohol yeasts a laboratorial strain (CEN.PK2-1D) and two industrial alcohol yeasts (JHS100 and JHS200) of Saccharomyces cerevisiae were cultured in a pure YP medium with 300 g/L glucose and cassava hydrolysate. Spot assay and cell viability tests showed that both the JHS100 and JHS200 strains exhibited higher ethanol tolerance than the CEN.PK2-1D strain. The JHS100 strain demonstrated the highest cell growth, glucose consumption and ethanol production. In particular, an anaerobic batch fermentation of the JHS100 strain using cassava hydrolysate with 250 g/L glucose resulted in a 106.1 g/L ethanol concentration, 0.42 g/g ethanol yield and 3.15 g/L-hr ethanol productivity, which were 53%, 13%, 53% higher than the corresponding values for the CEN.PK2-1D strain. By changing the pure YP medium to cassava hydrolysate, 19% and 17% decreases in ethanol yield and productivity for the CEN.PK2-1D strain were observed, whereas the cultures of the JHS100 and JHS200 stains showed similar ethanol productivities and only an 8% decrease in ethanol yield. Furthermore, the JHS100 and JHS200 stains produced lower levels of glycerol and acetate byproducts than the CEN.PK2-1D strain. Consequently, the outstanding ethanol fermentation performance of the industrial strains might be owing to rapid cell growth, high ethanol tolerance, low nitrogen requirements and the low formation of by-products.

• Microbiology and Biotechnology Letters
• /
• v.16 no.4
• /
• pp.297-302
• /
• 1988

The protoplasts of Saccharomyces cerevisiae D-71, a thermophilic strain and Zygosaccharomyces rouxii SR-S, an osmotolerant strain were fused, and a fusant (FS-RN 1) was selected, then was characterized for its genetic stability, DNA content, cell capacity, growth rate, tolerance to salts and chemicals, $\beta$-fructofuranosidase level and ethanol fermenting activity. After 6 months of preservation, 5.8% of the fusant clones were segregated to parental types. The DNA content and cell capacity of the fusant were greater than those of the parental strains. Lag period of growth for the fusant was longer than those for the parents. The fusant colonies showed pink-color reaction to triphenyltetrazolium chloride(TTC) test. The fusant appeared to have resistances to NaCl at moderate levels between both parental strains, and resistances to KCI, sodium propionate and cycloheximide similar to either one of the parents. $\beta$-Fructofuranosidase activity of the fusant was 24.2$\times$10$^{-3}$/IU/g(dry wt) for 3 days culture. Ethanol yields ofter 4 days of fermentation by the fusant at 3$0^{\circ}C$ were : 6.0%(v/v) from 40% of glucose and 8.8%(v/v) from 20% of sucrose.

• Applied Biological Chemistry
• /
• v.39 no.3
• /
• pp.195-199
• /
• 1996

We have cloned several E. coli sfs genes which stimulate mal gene expression with $crp^{{\ast}1}$). One the genes (pPVC2) was sequenced and potential CRP binding site is located in the upstream of the putative promoter in the regulatory region. In order to investigate the regulation of the sfs1 gene by the cAMP-CRP complex, we have constructed the sfs-lacZ fusion gene in this research. The overall transcriptional stimulations of sfs1 gene in the presence cAMP were confirmed by ${\beta}-galactosidase$ activity and Western blot analysis of sfs1-lacZ fusion gene. Transcriptional regulation by cAMP-CRP was also confirmed by Northern blot analysis. End-labelled DNA of the DNA fragment in sfs1 regulation region were used for gel retardation assay to examine the CRP-DNA complex in the presence of cAMP. Results here indicate that CRP binding site in the regulatory region of sfs1 gene is positive regulator for the expression of sfs1 gene.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
• /
• v.28 no.1
• /
• pp.1-8
• /
• 2022

With the spread of COVID-19 worldwide, non-face-to-face services have grown rapidly, but at the same time, the problem of plastic waste is getting worse. Accordingly, eco-friendly policies such as carbon neutrality and sustainable circular economy are being promoted worldwide. Due to the high demand for eco-friendly products, the packaging industry is trying to develop eco-friendly packaging materials using PLA and PBAT and create new business models. On the other hand, Ulva australis occurs in large quantities in the southern seas of Korea and off the coast of Jeju Island, causing marine environmental problems. In this study, lactic acid was produced through dilute acid pretreatment, enzymatic saccharification, and fermentation processes to utilize Ulva australis as a new alternative energy raw material. In general, seaweeds vary in carbohydrate content and sugar composition depending on the species, harvest location, and time. Seaweed is mainly composed of polysaccharides such as cellulose, alginate, mannan, and xylan, but does not contain lignin. It is difficult to expect high extraction yield of the complex polysaccharide constituting Ulva australis with only one process. However, the fusion process of dilute acid and enzymatic saccharification presented in this study can extract most of the sugars contained in Ulva australis. Therefore, the fusion process is considered to be able to expect high lactic acid production yield when a commercial-scale production process is established.

• Applied Biological Chemistry
• /
• v.31 no.1
• /
• pp.26-32
• /
• 1988

This study was performed to construct killer wine yeasts which might suppress the growth of wild yeasts, reduce the consumption of starter and condense the fermentation period. Saccharomyces cerevisiae M524, a commercial wine yeast, was treated with N-methyl-N'-nitro-N-nitrosoguanidine to induce auxotrophic mutants, i.e., CHM $2(thr^-)$, CHM 3 $(asp^-)$ and CHM 6 $(tyr^-)$. These auxotrophs were fused successfully with a killer yeast, S. cerevisiae $1368R({\alpha}\;his\;4\;kar\;1-1(kil-k)\;(k_0)$, respiratory deficient) using sphoroplast techniques and the fusants were designated as CHF 21$(th^-\;kil^+)$, CHF 22$(thr^-\;kil^+)$, CHF 31$(asp^-\;kil^+)$ and GHF 61$(tyr^-\;kil^+)$. Combined cultivation of CHF 31 with 1368R or S. cerevisiae $5{\times}47$ (killer sensitive) proved out that CHF 31 had the characteristic of killing and produced the same amount of ethanol as the prototroph, M524.

• Journal of Microbiology and Biotechnology
• /
• v.23 no.9
• /
• pp.1339-1346
• /
• 2013

Conventional chemotherapeutic regimens often accompany severe side effects and fail to induce complete regression of chemoresistant or relapsing metastatic cancers. The need for establishing more efficacious anticancer strategies led to the development of a combined modality treatment of chemotherapy in conjunction with immunotherapy or radiotherapy. It has been reported that poly-gamma-glutamate (${\gamma}$-PGA), a natural polymer composed of glutamic acids, increases antitumor activity by activating antigen-presenting cells and natural killer (NK) cells. Here, we investigated the antitumor effect of ${\gamma}$-PGA in combination with cyclophosphamide in a murine melanoma model. Whereas cyclophosphamide alone directly triggered apoptosis of tumor cells in vitro, ${\gamma}$-PGA did not show cytotoxicity in tumor cells. Instead, it activated macrophages, as reflected by the upregulation of surface activation markers and the secretion of proinflammatory factors, such as nitric oxide and tumor necrosis factor ${\alpha}$. When the antitumor effects were examined in a mouse model, combined treatment with cyclophosphamide and ${\gamma}$-PGA markedly suppressed tumor growth and metastasis. Notably, ${\gamma}$-PGA treatment dramatically increased the NK cell population in lung tissues, coinciding with decreased metastasis and increased survival. These data collectively suggest that ${\gamma}$-PGA can act as an immunotherapeutic agent that exhibits a synergistic antitumor effect in combination with conventional chemotherapy.