• 한국가스학회지
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• 제12권3호
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• pp.13-19
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• 2008

열병합발전용으로 사용되는 여러 가지 원동기 중 천연가스 엔진은 1 MW 이하의 발전용량을 갖는 원동기로 가장 널리 사용되고 있다. 이론공연비 연소방식과 삼원촉매를 채택한 300 kW급 천연가스 엔진은 강화된 배기규제를 만족시킬 수 있지만 이론공연비 연소방식은 희박 연소방식에 비해 효율이 대체적으로 낮기 때문에 최적 점화시기(MBT) 제어가 필요하다. 그러나 MBT 운전조건은 노킹이 발생되기 쉬워 높은 흡기온도 조건에서 운전되는 엔진에 대해서는 노킹제어가 이루어져야 한다. 본 연구에서는 높은 흡기온도가 요구되는 열병합발전용 천연가스엔진을 대상으로 흡기온도에 따른 엔진성능과 노킹특성에 대하여 실험한 결과를 제시하였다.

• Archives of Pharmacal Research
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• 제29권7호
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• pp.605-616
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• 2006

A wide variety of drugs and endogenous bioactive amines are organic cations (OCs). Approximately 40% of all conventional drugs on the market are OCs. Thus, the transport of xenobiotics or endogenous OCs in the body has been a subject of considerable interest, since the discovery and cloning of a family of OC transporters, referred to as organic cation transporter (OCTs), and a new subfamily of OCTs, OCTNs, leading to the functional characterization of these transporters in various systems including oocytes and some cell lines. Organic cation transporters are critical in drug absorption, targeting, and disposition of a drug. In this review, the recent advances in the characterization of organic cation transporters and their distribution in the small intestine are discussed. The results of the in vitro transport studies of various OCs in the small intestine using techniques such as isolated brush-border membrane vesicles, Ussing chamber systems and Caco-2 cells are discussed, and in vivo knock-out animal studies are summarized. Such information is essential for predicting pharmacokinetics and pharmacodynamics and in the design and development of new cationic drugs. An understanding of the mechanisms that control the intestinal transport of OCs will clearly aid achieving desirable clinical outcomes.

• BMB Reports
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• 제36권1호
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• pp.35-42
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• 2003

Heterocyclic amines (HCAs) are potent mutagens generated during the cooking of meat and fish, and several of these compounds produce tumors in conventional experimental animals. During the past 5 years or so, HCAs have been tested in a number of novel in vivo murine models, including the following: lacZ, lacI, cII, c-myc/lacZ, rpsL, and $gpt{\Delta}$ transgenics, $XPA^{-/-}$, $XPC^{-/-}$, $Msh2^{+/-}$, $Msh2^{-/-}$ and $p53^{+/-}$ knock-outs, Apc mutant mice ($Apc^{{\Delta}716}$, $Apc^{1638N}$, $Apc^{min}$), and $A33^{{\Delta}N{\beta}-cat}$ knock-in mice. Several of these models have provided insights into the mutation spectra induced in vivo by HCAs in target and non-target organs for tumorigenesis, as well as demonstrating enhanced susceptibility to HCA-induced tumors and preneoplastic lesions. This review describes several of the more recent reports in which novel animal models were used to examine HCA-induced mutagenesis and carcinogenesis in vivo, including a number of studies which assessed the inhibitory activities of chemopreventive agents such as 1,2-dithiole-3-thione, conjugated linoleic acids, tea, curcumin, chlorophyllin-chitosan, and sulindac.

• 대한불안의학회지
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• 제1권1호
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• pp.25-30
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• 2005

In the 40 years since the first benzodiazepine was brought into clinical use there has been a substantial growth in understanding the molecular basis of action of these drugs and the role of their receptors in anxiety disorders. Benzodiazepine receptors are present throughout the brain with the highest concentration in cortex, and it potentiate and prolong the synaptic action of the inhibitory neurotransmitter GABA. Central benzodiazepine receptors and $GABA_A$ receptors are part of the same macromolecular complex. Abnormalities of these $GABA_A$-benzodiazepine receptors as a result of drug challenge tests and neuroimaging studies may underlie some anxiety disorders. The role of $GABA_A$-benzodiazepine receptors in the action of benzodiazepine and as a factor in anxiety disorder, in both animal and humans including knock-out and knock in technique, may lead to new anxiolytics that have potentially significant therapeutic gains without unwanted side effects.

• 한국수소및신에너지학회논문집
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• 제26권1호
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• pp.28-34
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• 2015

HCCI (Homogeneous Charged Compression Ignition) hydrogen engine has relatively narrower operation range caused by backfire occurrence due to the rapid pressure rising by using higher compression ratio and significant reaction velocity. In this study, to grasp of backfire process and characteristic in the HCCI research hydrogen engine, in-cylinder pressure, intake pressure and backfire limit range are analyzed with compression ratio and intake valve open timing, experimentally. As the result, it is observed that knock is occurred just before backfire occurrence in HCCI hydrogen engine but not spark igntion type, this phenomenon is always the same for the above variables. Also backfire limit range are expanded up to 50% for the more retarding intake valve open timing in this operating conditions.

• Molecules and Cells
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• 제27권2호
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• pp.243-250
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• 2009

Recent studies suggest a novel role of $HIF-1{\alpha}$ under nonhypoxic conditions, including antibacterial and antiviral innate immune responses. However, the identity of the pathogen-associated molecular pattern which triggers $HIF-1{\alpha}$ activation during the antiviral response remains to be identified. Here, we demonstrate that cellular administration of double-stranded nucleic acids, the molecular mimics of viral genomes, results in the induction of $HIF-1{\alpha}$ protein level as well as the increase in $HIF-1{\alpha}$ target gene expression. Whole-genome DNA microarray analysis revealed that double-stranded nucleic acid treatment triggers induction of a number of hypoxia-inducible genes, and induction of these genes are compromised upon siRNA-mediated $HIF-1{\alpha}$ knock-down. Interestingly, $HIF-1{\alpha}$ knock-down also resulted in down-regulation of a number of genes involved in antiviral innate immune responses. Our study demonstrates that $HIF-1{\alpha}$ activation upon nucleic acid-triggered antiviral innate immune responses plays an important role in regulation of genes involved in not only hypoxic response, but also immune response.

• 한국수소및신에너지학회논문집
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• 제26권6호
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• pp.560-566
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• 2015

HCCI (Homogeneous Charge Compression Ignition) hydrogen engine has relatively narrower operation range caused by knock occurrence due to the rapid pressure rising by using higher compression ratio. In this study, EGR as one of the countermeasure methods is considered to extend operation range of HCCI hydrogen engine. Also, the effects of hydrogen EGR are compared with the effects of EGR using hydrocarbon fuel. Hydrocarbon EGR is carried out by adding carbon dioxide to exhaust gas of HCCI hydrogen engine. As the results, EGR has positive effects on a HCCI hydrogen engine in reducing rate of pressure rise as same as the other engines used hydrocarbon fuels. However, the effects of hydrogen EGR are better than those of hydrocarbon EGR in decreasing minimum compression ratio and rate of pressure rise. When applying EGR to HCCI hydrogen engine by 20% rate, the rate of pressure rise decreases by 58% and it results in about 48% increase of the operation range in terms of supply energy.

• Nuclear Engineering and Technology
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• 제35권5호
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• pp.497-505
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• 2003

This paper describes a computational approach to the quantification of primary damage under irradiation and demonstrates the effect of neutron energy spectra on the formation of the displacement cascade. The development of displacement cascades in ${\alpha}-Iron$ has been simulated using the MOLDY code - a molecular dynamics code for simulating radiation damage. The primary knock-on atom energy, key input to the MOLDY code, was determined from the SPECTER code calculation on two neutron spectra. The two neutron spectra include; (i) neutron spectrum in the instrumented irradiation capsule of the high-flux advanced neutron application reactor (HANARO), and (ii) neutron spectrum at the inner surface of the reactor pressure vessel steel for the Younggwang nuclear power plant No.5 (YG 5). Minor differences in the normalized neutron spectra between the two spectra produce similar values of PKA energy, which are 4.7 keV for HANARO and 5.3 keV for YG 5. This similarity implies that primary damage to the components of the commercial nuclear reactors should be well simulated by irradiation in the HANARO. Moreover, the application of the MD calculations corroborates this statement by comparing cascades simulation results.

• 한국수소및신에너지학회논문집
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• 제16권2호
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• pp.191-198
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• 2005

Adding hydrogen gas in natural gas leads to stable combustion in internal combustion engine and its performances rely on compression ratio. To analyze the effects of compression ratio and rate of hydrogen addition on the engine performance, the characteristics of overall engine performance including emission were investigated by using the medium duty natural gas fueled engine. As results, it was found that compression ratio occurred knock was nearby compression ratio, $\varepsilon$=14 for the case that hydrogen was enriched in the natural gas fueled engine. But slight knock was occurred at $\varepsilon$=14.7 in the case of neat natural gas. Also HC and $CO_2$ were reduced around 80% and 20% respectively when the rate of hydrogen addition was increased to 50% and compression ratio from $\varepsilon$=13 to $\varepsilon$=14.7.

• The Plant Pathology Journal
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• 제24권1호
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• pp.1-7
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• 2008

Fusarium verticillioides (teleomorph Gibberella moniliformis) is associated with maize worldwide causing ear rot and stalk rot, and produces fumonisins, a group of mycotoxins detrimental to humans and animals. While research tools are available, our understanding of the molecular mechanisms associated with fungal virulence and fumonisin biosynthesis in F. verticillioides is still limited. One of the restraints that hampers F. verticillioides gene characterization is the fact that homologous recombination (HR) frequency is very low (<2%). Screening for a true gene knock-out mutant is a laborious process due to a high number of ectopic integrations. In this study, we generated a F. verticillioides mutant (SF41) deleted for FvKU70, a gene directly responsible for non-homologous end-joining mechanism, with the aim of improving HR frequency. Here, we demonstrate that FvKU70 deletion does not impact key Fverticillioides phenotypes, e.g., development, secondary metabolism, and virulence, while dramatically improving HR frequency. Significantly, we also confirmed that a high percentage (>85%) of the HR mutant strains harbor a desired mutation with no additional copy of the mutant allele inserted in the genome. We conclude that SF41 is suitable for use as a type strain when performing high-throughput gene function studies in F. verticillioides.