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.

A mobility-based load control scheme in Hierarchical Mobile IPv6 networks

Pack, Sangheon,Kwon, Taekyoung,Choi, Yanghee Springer-Verlag 2010 WIRELESS NETWORKS Vol.16 No.2

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.

An Adaptive Power Saving Mechanism in IEEE 802.11 Wireless IP Networks

Pack Sangheon,Choi Yanghee The Korea Institute of Information and Commucation 2005 Journal of communications and networks Vol.7 No.2

Reducing energy consumption in mobile hosts (MHs) is one of the most critical issues in wireles/mobile networks. IP paging protocol at network layer and power saving mechanism (PSM) at link layer are two core technologies to reduce the energy consumption of MHs. First, we investigate the energy efficiency of the current IEEE 802.11 power saving mechanism (PSM) when IP paging protocol is deployed over IEEE 802.11 networks. The result reveal that the current IEEE 802.11 PSM with a fixed wakeup interval (i.e., the static PSM) exhibits a degraded performance when it is integrated with IP paging protocol. Therefore, we propose an adaptive power saving mechanism in IEEE 802.11-based wireless IP networks. Unlike the static PSM, the adaptive PSM adjusts the wake-up interval adaptively depending on the session activity at IP layer. Specifically, the MH estimates the idle periods for incoming sessions based on the exponentially weighted moving average (EWMA) scheme and sets its wake-up interval dynamically by considering the estimated idle period and paging delay bound. For performance evaluation, we have conducted comprehensive simulations and compared the total cost and energy consumption, which are incurred in IP paging protocol in conjunction with various power saving mechanisms: The static PSM, the adaptive PSM, and the optimum PSM. Simulation results show that the adaptive PSM provides a closer performance to the optimum PSM than the static PSM.

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>

Real-Time Quantitative PCR with SYBR Green I for Living Modified Roundup Ready Soybean

Pack, In-Soon,Jeong, Soon-Chun,Lee, Kyu-Hwa,Yoon, Won-Kee,Park, Sang-Kyu,Kim, Chang-Gi,Kim, Hwan-Mook Korean Society of ToxicologyKorea Environmental Mu 2005 Toxicological Research Vol.21 No.3

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>