Stabilization of Bacillus subtilis Lipase A by increasing the residual packing

Abraham1, Tajo,Pil Pack1, Seung,Je Yoo, Young Taylor Francis 2005 Biocatalysis and biotransformation Vol.23 No.3

<P>Introduction of well-packed residues to the interior of a protein structure could be considered as a stabilization strategy since the reduction of buried cavities might stabilize protein structure. In this study, the less-packed residues with no water-contact were selected as target sites for increasing residual packing. When Lipase A from Bacillus subtilis (179 amino acids) was used as a model system, 43 less-packed residues were initially considered by analyzing their residual packing value and residual exposure ratio. Among the 43 residues, small amino acids such as GLY and ALA were chosen as target sites. Packing increases of ALA to VAL and GLY to ALA were estimated, by molecular modeling, to give 0.5368∼⃒0.7433  kcal mol −1 stabilization. Mutants of Lipase A such as A38V, A75V, G80A, A105V A146V, and G172A were obtained via protein engineering. Thermostability assays revealed that A38V, G80A and G172V were the most stable mutants. This procedure for selecting the target residues for improved thermostability of Lipase A could be applied for improving the thermostability of other proteins and enzymes.</P>

디젤하이브리드 배터리 관리 시스템 개발

최경덕(Kyeongduck Choi),유상길(Sanggil Yoo),강희선(Heesun Kang),박상민(Sangmin Pack) 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

This paper discusses on development of a BMS(Battery Management System) for D-HEV(Diesel-Hybrid Electronic Vehicle) including algorithm of battery(Lithium) SOC(State of Charge) estimation. The algorithm accurately estimates the remaining battery capacity for automated battery management. In this paper, a BMS including technique for battery monitoring(Pack-Voltage, Pack-Current, Cell-Voltage, Pack-Temperature), communication method, digital input/output control, a battery thermal control, and battery protection method is developed.

Quantitative analysis of specific target DNA oligomers using a DNA-immobilized packed-column system

Pack, Seung Pil,Heo, Tae-Hwe,Devarayapalli, Kamakshaiah Charyulu,Makino, Keisuke Springer-Verlag 2011 ANALYTICAL AND BIOANALYTICAL CHEMISTRY Vol.401 No.2

발전용 증기터빈 내부간극 관리방안

백민식(Min-Sik Pack),이시연(Si-Yeon Lee),양보석(Bo-Suk Yang),최성철(Sung-Choul Choi),이재근(Jae-Geun Lee) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.11

This paper presents a control plan of clearances for power plant steam turbine with the characteristics of internal clearances. Internal clearances on the interstage of blades and shaft gland seals on the steam turbine which are installed in tandem compound was changed when the rotor turned in the cylindrical sleeve bearing due to the generation of oil film wedge. This presented concern is very useful to prevent the rubbing damage of seal edge between the fixed and moving parts in steam turbine due to the misalignment at the rotating and stationary parts. This method is applied for the unbalanced clearances distribution to the left and right sides in the turbine casing. A considerable amount of unbalanced clearances distribution trend is determined according to the rotating speed of shaft, bearing size, type of journal bearing, bearing load, lubrication oil viscosity, oil temperature, oil pressure and surface roughness of shaft.

Protein Thermostabilizing Factors: High Relative Occurrence of Amino Acids, Residual Properties, and Secondary Structure Type in Different Residual State

Pack, S. P.,Kang, T. J.,Yoo, Y. J. HUMANA PRESS INC 2013 Applied biochemistry and biotechnology Vol.171 No.5

Risk assessment of toxicants on WHO TobReg priority list in mainstream cigarette smoke using human-smoked yields of Korean smokers

Pack, Eun Chul,Kim, Hyung Soo,Jang, Dae Yong,Koo, Ye Ji,Yu, Hong Hyeon,Lee, Seung Ha,Lim, Kyung Min,Choi, Dal Woong Elsevier 2019 Environmental research Vol.169 No.-

<P><B>Abstract</B></P> <P>Recently, the World Health Organization Study Group on Tobacco Product Regulation (WHO TobReg) announced a priority list of 38 toxicants among the more than 7000 chemicals found in cigarette smoke, building upon previous lists of toxicants in cigarette smoke. Here, we conducted a comprehensive study on the quantitative exposure and risk characterization of these priority toxicants in mainstream cigarette smoke listed by the WHO TobReg. The human-smoked toxicant yields estimated from spent cigarette butts of a total of 361 smokers using the part-filter method (PFM) were applied to current exposure and risk estimation for the first time. The PFM can estimate human-smoked yields of toxicants using smokers’ maximum mouth-level exposure. The human-smoked yield of each toxicant was converted to systemic uptake by considering bioavailability. Risk indicators—including the incremental lifetime cancer risk (ILCR), cumulative ILCR, hazard quotient (HQ), hazard indices (HIs), and margin of exposure (MOE)—were estimated from the systemic uptake of toxicants combined with Korean exposure factors by gender and age group as well as for total smokers. It was demonstrated that cigarette smoking results in significant cancer and non-cancer health risks. A sensitivity analysis showed that the human-smoked toxicant yield is one of the most important contributors to risk level variations. Our risk estimation suggested that previous risk assessments might have ignored or underestimated the uncertainty of risk assessment. In conclusion, we assessed the risk level of the 38 toxicants on the priority list developed by the WHO TobReg and provided a Korean-specific priority list for the regulations on the emission of cigarette smoke.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Comprehensive risks of toxicants in the mainstream cigarette smoke of Korean smokers were assessed. </LI> <LI> Human-smoked yield using the part-filter method was applied to risk estimation for the first time. </LI> <LI> Cigarette smoking was found to have significant cancer risks or non-cancer hazards. </LI> <LI> Human-smoked yield was determined as a greater contributor to risk level variations. </LI> <LI> The WHO TobReg priority list was reevaluated with risk levels, and a Korean-specific priority list was provided. </LI> </UL> </P>

RA-PSM: a rate-aware power saving mechanism in multi-rate wireless LANs

Pack, Sangheon,Min, Seongman,Song, Taewon,Kim, Wonjung,Choi, Nakjung,Park, Hyunhee Springer-Verlag 2016 WIRELESS NETWORKS Vol.22 No.6

<P>Improving energy efficiency is one of the most important issues in wireless local area networks (WLANs) and a power saving mechanism (PSM) has been proposed in IEEE 802.11 WLANs. However, the conventional PSMs do not consider multi-rate transmissions and thus the waiting time for retrieving buffered frames from the access point can be unnecessarily long and more energy can be consumed. In this paper, we propose a rate-aware power saving mechanism (RA-PSM) in multi-rate WLANs. In RA-PSM, a station sets its contention window size inversely proportional to the transmission rate and thus a station with higher transmission rate can request the buffered frames at the access point with higher priority. As a result, the overall channel waiting time can be reduced and the energy consumption can be saved accordingly. Analytical and simulation results demonstrate that RA-PSM can reduce the average channel waiting time and the energy consumption by up to 77 and 40.3 %, respectively, compared with the conventional IEEE 802.11 PSM.</P>

Silica - Pillared H-magadiites : Interlamellar Base - Catalyzed Hydrolysis of Tetraethylorthosilicate in Pure Water Suspension

Pack, U Hyon,Kwon, Oh Yun,Park, Kyeong Won 한국공업화학회 1999 Journal of Industrial and Engineering Chemistry Vol.5 No.2

The silica-pillared H^+-magadiites were prepared by interlamellar base-catalyzed hydrolysis of tetraethylorthosilicate [TEOS, Si(OC₂H_5)₄] intercalated into the interlayers of H^+-magadiite. The interlamellar hydrolysis of TEOS were conducted between 10 min to 40 min in 0.00%, 0.05%, 0.10% and 0.20% NH₃-water solution, affording siloxane-pillared H^+-magadiites with gallery height of 24.8∼30.3Å. Calcination of samples at 538℃ in air resulted in silica-pillared H^+-magadiites with a large specific surface areas between 551 and 1020 ㎡/g, depending on the aging time and NH₃ concentration. The reaction in pure water and 0.05% NH₃ solution afforded optimum specific surface areas and mesopores with narrow pore size distribution. The reaction in 0.10% and 0.20% NH₃ solution resulted in sharp decrease of specific surface areas and poorly-ordered basal spacings, implying the partial destruction in the layered structure of H^+-magadiite.

Contact Line Instability Caused by Air Rim Formation under Nonsplashing Droplets

Pack, Min,Kaneelil, Paul,Kim, Hyoungsoo,Sun, Ying American Chemical Society 2018 Langmuir Vol.34 No.17

<P>Drop impact is fundamental to various natural and industrial processes such as rain-induced soil erosion and spray-coating technologies. The recent discovery of the role of air entrainment between the droplet and the impacting surface has produced numerous works, uncovering the unique physics that correlates the air film dynamics with the drop impact outcomes. In this study, we focus on the post-failure air entrainment dynamics for <I>We</I> numbers well below the splash threshold under different ambient pressures and elucidate the interfacial instabilities formed by air entrainment at the wetting front of impacting droplets on perfectly smooth, viscous films of constant thickness. A high-speed total internal reflection microscopy technique accounting for the Fresnel reflection at the drop-air interface allows for in situ measurements of an entrained air rim at the wetting front. The presence of an air rim is found to be a prerequisite to the interfacial instability which is formed when the capillary pressure in the vicinity of the contact line can no longer balance the increasing gas pressure near the wetting front. A critical capillary number for the air rim formation is experimentally identified above which the wetting front becomes unstable where this critical capillary number inversely scales with the ambient pressure. The contact line instabilities at relatively low <I>We</I> numbers (<I>We</I> ∼ O(10)) observed in this study provide insight into the conventional understanding of hydrodynamic instabilities under drop impact which usually require <I>We</I> ≫ 10.</P> [FIG OMISSION]</BR>

A Molecular Framework for Risk Assessment of a Virus-Tolerant Transgenic Pepper Line

Pack, In-Soon,Kim, Yu-Jin,Youk, Eun-Soo,Lee, Woo-Kyu,Yoon, Won-Kee,Park, Kee-Woong,Kim, Chang-Gi,Harn, Chee-Hark,Kim, Hwan-Mook,Jeong, Soon-Chun 한국작물학회 2012 Journal of crop science and biotechnology Vol.15 No.2

The Cucumber mosaic virus coat protein (CMV-CP) gene-transgenic pepper lines exhibit high tolerance to Cucumber mosaic virus (CMV) strains. In this study, E7, one of the CMVP0-CP transgenic chili pepper events selected by screening was further characterized. Southern blotting and inverse PCR analysis revealed that the E7 event contains a single copy of the inserted gene cassette whose flanking sequences appear to be noncoding and intergenic. We searched for pepper-specific DNA sequence candidates as an endogenous reference gene for GM-pepper detection. We found that only one copy of CaSIG4 and lipocalin genes are present in the pepper genome and their sequences were determined to be pepper-specific. The characterization of the genomic sequences flanking the transgene, as well as the availability of the pepper-specific single copy CaSIG4 and lipocalin genes as endogenous reference genes, enabled the design of E7-event-specific PCR-based quantitative detection methods. The CMV-CP protein levels in the CMV-inoculated wild-type pepper tissues were approximately 60 times higher than those in the uninoculated and CMV-inoculated E7 pepper tissues. These results suggested that the amount of CMV-CP expressed in transgenic pepper tissue was negligible relative to the amount of CMV-CP in the virus-infected wild-type pepper consumed by human beings. This work may prove useful for risk assessment studies of transgenic pepper lines. Furthermore, the characterized single copy genes, lipocalin and CaSIG4, may be used to develop a method to detect gene copy number variations in the pepper genome.