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Ghim, Sa-Youl Korean Society of Life Science 2001 Journal of Life Science Vol.11 No.2
The pyrR gene of the pyrimidine biosynthesis (pyr) operon of the thermophile Bacillus caldolyticus, encoding a uracil phosphoribosyltransferase (UPRTase), turned to rely as a pyr operon regulator. It has been proposed that PyrR mediates transcriptional termination-antitermination at three intercistronic regions of the par operon (S.-Y Ghim and J. Neuhard, J. Bacteriol.,176, 3698-3707, 1994). In this research, a plasmid carrying the pyrR region of B. caldolyticus could restore a pyrimidine regulation in a pyrR mutant of B. subtilis. Expression of pyrR was found to increase 6-7 fold during pyrimidine starvation. Additionally, a highly conserved nucleotide sequence which may constitute the binding site for a PyrR protein (PyrR-binding loop) in transcript was staggested. Alternative antiterminator and terminator structures involving three conserved motifs in front of the pyrR, pyrP and pyrB genes, respectively, are proposed to account for the observed regulation pattern.
Ghim, G.,Lee, J. Pergamon ; Elsevier Science Ltd 2016 Applied thermal engineering Vol.106 No.-
The existence of temperature gliding in non-azeotropic mixture working fluids provides a promising opportunity for greatly improved resource utilization in organic Rankine cycle (ORC) systems for geothermal applications. The condensation heat transfer degradation associated with working fluid mixtures is an unavoidable penalty that may reduce the utilization and system benefits by necessitating larger heat exchangers. The objective of the current study is an experimental investigation of condensation heat transfer for R245fa, n-pentane, and a composition of their mixture. Quasi-local condensation heat transfer coefficients are measured in a straight horizontal smooth tube with flow conditions at mass flux G=100 and 150kg(m<SUP>2</SUP>s)<SUP>-1</SUP>, local equilibrium quality x=0.05-0.80, and reduced pressures P<SUB>r</SUB>=0.05-0.15. The reduced condensation heat transfer coefficients from the test are compared with the predictions from already established mixture correction methods in the literature. Pure components R245fa and n-pentane condensation heat transfer data are well predicted by Shah (1979) correlations for all test conditions. However, their non-azeotropic mixture condensation heat transfer data require additional correction parameter to account for the heat transfer degradation. This correction parameter is correlated by the temperature gliding gradient of mixture fluids. Test data with mixture working fluids from current study are reasonably well predicted by the corrected in-tube correlation.
Dry Deposition of Reactive Nitrogen and Sulfur Compounds in the Greater Seoul Area
Ghim, Young Sung,Kim, Jin Young 한국화학공학회 2002 Korean Journal of Chemical Engineering Vol.19 No.1
While deposition is a removal process of pollutants from the atmosphere, it is an intake process of such pollutants into the ground. It is suggested that surface waters in the Greater Seoul Area, used as a source of drinking water, have been affected by severe air pollution. In this work, the dry deposition of reactive nitrogen and sulfur species was estimated for three typical days in each season for the year of 1997. The CIT (California Institute of Technology) photochemical model incorporated with a gaseous oxidation reaction of SO_2 was used. The study revealed that reactive nitrogen deposition was the largest in summer and sulfur deposition was the largest in winter. Most of the reactive nitrogen was deposited in the form of HNO_3 and NO_2, but HNO_3 deposition is highly dependent on the season according to the extent of photochemical production. On the other hand, the contribution of sulfate to the total deposition of sulfur was minimal partly because of low deposition velocity and of the neglect of possible inflow from the boundaries. Approximately 53% of the reactive nitrogen and 30% of the sulfur emitted in the study area was deposited in the ground in the dry form on an annual basis.
Condensation heat transfer of low GWP ORC working fluids in a horizontal smooth tube
Ghim, G.,Lee, J. Pergamon Press ; Elsevier Science Ltd 2017 INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER - Vol.104 No.-
The objective of the current study is to conduct an experimental investigation of condensation heat transfer for the ORC (organic Rankine cycle) working fluids R245fa, Novec®649 and HFE-7000 over a wide range of parameters. Quasi-local condensation heat transfer coefficients are measured in a straight horizontal 7.75-mm-ID smooth tube with flow conditions at mass flux G=150-700kg (m<SUP>2</SUP>-s)<SUP>-1</SUP>, local equilibrium quality x=0.05-0.95, and reduced pressure, P<SUB>r</SUB>=0.05-0.15. Test data reveal that the environmentally friendly fluids have lower condensation heat transfer coefficients when compared to R245fa. The 141 measured condensation heat transfer coefficients are compared to six well-known correlations. Among the six correlations verified with test data, the Shah correlation shows the best predictive performance for the three fluids tested.
INHIBITION OF HUMAN NEUTROPHIL ELASTASE BY DIFFERENT CLASSES OF ANTIBIOTICS
Ghim, Sa-Youl,Kang, Kooil 고신대학교 의학부 1988 高神大學校 醫學部 論文集 Vol.4 No.1
사람의 혈액에 있는 호중구 엘라스테이즈에 관한 연구의 진척은, 약물로 사용가능한 생체내 혹은 인공합성의 저해제 개발을 동반해 오고 있다. 정제된 호중구 엘라스테이즈에 12종의 항생제를 처리하였더니 20mM 미만의 lC_(50)을 보인 것은 oxytetracycline, cefamandole, gentamicin, amikacin, cloxacillin, methicillin, chloramphenicol 등이었고, 10mM 농도에서 50% 이상의 저해율을 나타낸 것은 methicillin, cefamandole, oxytetracycline 등이었다. 그 결과는 세포벽 합성이나 단백질 합성을 저해하는 일반적 항생제의 약리학적 기전과는 다른 차원에서 항생제가 숙주의 조직을 보호할 수 있는 가능성을 보여준 모델이 존재한다는 것을 in vitro 실험에서 확인할 수 있었다.
Synthetic Biology for Biofuels: Building Designer Microbes from the Scratch
Ghim, Cheol-Min,Kim, Tae-Sung,Mitchell, Robert J.,Lee, Sung-Kuk 한국생물공학회 2010 Biotechnology and Bioprocess Engineering Vol.15 No.1
The ultimate goal in the production of biofuels is to produce fuels identical or similar to petroleum-derived transportation fuels more efficiently and in commercial quantities. Synthetic biologists have been engineering microbes to synthesize biofuels, such as butanol and fatty acid- or isoprenoid-based fuels, which are nearly identical to gasoline and diesel. One of the most urgent demands along this direction is to attain a solid framework for characterizing and standardizing the biological parts and devices. It seems quite promising because biotechnologies specially based on miniaturizations have been making a big contribution to this work. Therefore, in this review, recent advances and difficulties in the biofuel field are discussed, along with the advances of synthetic biology, which will make it possible to create designer microorganisms that produce economically viable next generation biofuels, aside from bioethanol, from corn or sugar cane, and biodiesel from plant or animal oils.