• 대한기계학회논문집A
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• 제20권10호
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• pp.3079-3094
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• 1996

Recently, the high-precision vibration attenuation technology becomes the essence fo the seccessful development of high-integrated and ultra-precision industries, and is expected to continue playing a key role in the enhancement of manufacturing technology. Vibration isolation system using an air-spring is widely employed owing to its excellent isolation characteristics in a wide frequency range. It has, however, some drawbacks such as low-stiffness and low-damping features and can be easily excited by exogenous disturbances, and then vibration of table is remained for a long time. Consequently, the need for active vibration control for an air-spring vibration isolation system becomes inevitable. Furthermore, for an air-spring isolation table to be successfully employed in a variety of manufacturing sites, it should have a guaranteed robust performance not only to exogenous disturbances but also to uncertainties due to various equipments which might be put on the table. In this study, an active vibration suppression control system using H.inf. theory is designed and experiments are performed to verify its robust performance. An air-spring vibration isolation table with voice-coil-motors as its actuators is designed and built. The table is modeled as 3 degree-of-freedom system. An active control system is designed based on $H_\infty$control theory using frequency-shaped weighting functions. Analysis on its performance and frequency responce properties are done through numerical simulations. Robust characteristics of$H_\infty$ control on disturbances and model uncertainties are experimentally verified through (i) the transient response to the impact excitation of the table, (ii) the steady-state response to the harmonic excitation, and (iii) the response to the mass change of the table itself. An LQG controller is also designed and its performance is compared with the $H_\infty$ controller.

• Molecules and Cells
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• 제39권8호
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• pp.631-638
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• 2016

Glutathione peroxidase 3 (GPx3), an antioxidant enzyme, acts as a modulator of redox signaling, has immunomodulatory function, and catalyzes the detoxification of reactive oxygen species (ROS). GPx3 has been identified as a tumor suppressor in many cancers. Although hyper-methylation of the GPx3 promoter has been shown to down-regulate its expression, other mechanisms by which GPx3 expression is regulated have not been reported. The aim of this study was to further elucidate the mechanisms of GPx3 regulation. GPx3 gene analysis predicted the presence of ten glucocorticoid response elements (GREs) on the GPx3 gene. This result prompted us to investigate whether GPx3 expression is regulated by the glucocorticoid receptor (GR), which is implicated in tumor response to chemotherapy. The corticosteroid dexamethasone (Dex) was used to examine the possible relationship between GR and GPx3 expression. Dex significantly induced GPx3 expression in H1299, H1650, and H1975 cell lines, which exhibit low levels of GPx3 expression under normal conditions. The results of EMSA and ChIP-PCR suggest that GR binds directly to GRE 6 and 7, both of which are located near the GPx3 promoter. Assessment of GPx3 transcription efficiency using a luciferase reporter system showed that blocking formation of the GR-GRE complexes reduced luciferase activity by 7-8-fold. Suppression of GR expression by siRNA transfection also induced down-regulation of GPx3. These data indicate that GPx3 expression can be regulated independently via epigenetic or GR-mediated mechanisms in lung cancer cells, and suggest that GPx3 could potentiate glucocorticoid (GC)-mediated anti-infla-mmatory signaling in lung cancer cells.

• 전력전자학회논문지
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• 제4권4호
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• pp.349-356
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• 1999

본 논문에서는 철도차량용 보조전원장치에 순시전압제어기법을 적용할 때 발생하는 문제들의 해결방안을 제시한다. 비선형부하나 과도상태에서 빠른 응답특성을 얻기 위해 순시전압제어기법을 사용할 때 LC 필터의 공진문제와 존재하는 정상상태 오차가 더욱 심각해진다. 인버터 출력측 LC 필터에 기인하는 공진현상을 억제하기 위해 전압전달함수의 제동비를 증가시키기 위한 방안으로 필터 커패시터 궤환제어기가 고려되었다. 그리고 교류전압 순시제어시 존재하는 정상상태 오차를 제거하기 위하여 고이득 전달함수를 기존의 PI 제어기에 첨가하였다. 이론적인 분석이 시뮬레이션 결과와 함께 잘 설명되어져 있다. 제안된 기법의 타당성을 5kVA급 시제품에 대한 시뮬레이션과 실험을 통하여 입증하였다.

• 센서학회지
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• 제15권2호
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• pp.120-126
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• 2006

Physicochemical and electrical properties for hydrogen gas sensors based on Pd-deposited $WO_3$ thin films were investigated as a function of Pd thickness, annealing temperature, and operating temperature. $WO_3$ thin films were deposited on an insulating material by thermal evaporator. XRD, FE-SEM, AFM, and XPS were used to evaluate the crystal structure, microstructure, surface roughness, and chemical property, respectively. The deposited films were grown $WO_3$ polycrystalline with rhombohedral structure after annealing at $500^{\circ}C$. The addition effect of Pd is not the crystallinity but the suppression of grain growth of $WO_3$. Pd was scattered an isolated small spherical grain on $WO_3$ thin film after annealing at $500^{\circ}C$ and it was agglomerated as an irregular large grain or diffused into $WO_3$ after annealing at $600^{\circ}C$. 2 nm Pd-deposited $WO_3$ thin films operated at $250^{\circ}C$ showed good response and recovery property.

• Journal of Microbiology and Biotechnology
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• 제28권1호
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• pp.65-76
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• 2018

Although there has been a steady increase in the prevalence of food allergies worldwide in recent decades, no effective therapeutic strategies have been developed. Modulation of the gut microbiota composition and/or function through probiotics has been highlighted as a promising target for protection against food allergies. In this study, we aimed to investigate the allergy-reducing effects of a probiotic mixture (P5: Lactococcus lactis KF140, Pediococcus pentosaceus KF159, Lactobacillus pentosus KF340, Lactobacillus paracasei 698, and Bacillus amyloliquefaciens 26N) in mice with ovalbumin (OVA)-induced food allergy. Administration of P5 significantly suppressed the oral OVA challenge-induced anaphylactic response and rectal temperature decline, and reduced diarrhea symptoms. Moreover, P5 also significantly inhibited the secretion of IgE, Th2 cytokines (interleukin (IL)-4, IL-5, IL-10, and IL-13), and Th17 cytokines (IL-17), which were increased in mice with OVA-induced food allergy, and induced generation of CD4+Foxp3+ regulatory T cells. These results revealed that P5 may have applications as a preventive agent against food allergy.

• 한국발생생물학회지:발생과생식
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• 제17권3호
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• pp.179-186
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• 2013

Neural stem cells are found in adult mammalian brain regions including the subgranular zone (SGZ) of the dentate gyrus (DG) and the subventricular zone (SVZ). In addition to these two regions, other neurogenic regions are often reported in many species. Recently, the subcallosal zone (SCZ) has been identified as a novel neurogenic region where new neuroblasts are spontaneously generated and then, by Bax-dependent apoptosis, eliminated. However, the development of SCZ in the postnatal brain is not yet fully explored. The present study investigated the precise location and amount of neuroblasts in the developing brain. To estimate the importance of programmed cell death (PCD) for SCZ histogenesis, SCZ development in the Bax-knockout (KO) mouse was examined. Interestingly, an accumulation of extra neurons with synaptic fibers in the SCZ of Bax-KO mice was observed. Indeed, Bax-KO mice exhibited enhanced startle response to loud acoustic stimuli and reduced anxiety level. Considering the prevention of PCD in the SCZ leads to sensory-motor gating dysfunction in the Bax-KO mice, active elimination of SCZ neuroblasts may promote optimal brain function.

• 한국소음진동공학회논문집
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• 제23권4호
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• pp.356-364
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• 2013

This paper presents a tracking gain-up controller design method to control effectively the vibration of tracking actuator caused by external shocks and remaining velocity after seek control. A pole placement constraint is considered to assure a desired transient response against the vibration of tracking actuator. A loop gain-up constraint is introduced to hold the tracking gain-up loop gain and control bandwidth within allowable bounds. The pole placement constraint is expressed by a matrix inequality and the loop gain-up constraint is considered as an objective function so that genetic algorithm can be applied. Finally, a tracking gain-up controller is obtained by integrating a genetic algorithm with LMI design approach. The proposed tracking gain-up controller design method is applied to the track-following system of a DVD recording device and its effectiveness is evaluated through the experimental results.

• 대한한의학회지
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• 제30권6호
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• pp.53-68
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• 2009

Objectives: This study demonstrates the neurological effects of Bojungikki-tang and Bojungikki-tang-gamibang on the focal cerebral ischemia of rats with ischemic damage caused by middle cerebral artery occlusion (MCAO). Methods: Rats were treated with Bojungikki-tang and Bojungikki-tang-gamibang extracts for about five days after MCAO, and the size and volume of cerebral infarction and the ratio of cerebral edema were observed. From the immunohistochemical view, significant changes of outbreak of Bax, Bcl-2, c-Fos, HSP72, and iNOS were observed in the brain tissues. Results: Bojungikki-tang repressed only brain edema and iNOS revelation led by focal cerebral ischemia, when considering significance. In contrast, Bojungikki-tang-gamibang demonstrated significant suppression of cerebral infarction, brain edema, Bax, c-Fos, HSP72, and iNOS induced by focal cerebral ischemia. Conclusions: Bojungikki-tang is considered functional treatment for cerebral ischemic damage; it can be effective to relieve secondary brain edema and immune response. Bojungikki-tang-gamibang can have a direct function to alleviate brain infarct and to control the natural death of nerve cells which cerebral ischemic damage brings about.

• 한국정보과학회논문지:소프트웨어및응용
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• 제32권5호
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• pp.335-345
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• 2005

개인화된 마케팅에서 고객 만족과 마케팅 효율을 최대화하는 것은 중요하다. 개인화된 캠페인이 수행됨에 따라 여러 캠페인이 동시에 수행되곤 한다. 이 논문에서 우리는 동시에 여러 개인화된 캠페인을 수행할 때 발생하는 중복 추천 문제를 제기한다. 이는 특정 고객에게 상당히 많은 양의 캠페인이 쏟아지게 되는 문제를 말한다. 이 이슈를 해결하기 위한 다중캠페인 할당 문제를 모델링 한다. 그리고 이 문제의 해결 방법으로 동적계획법을 비롯한 여러 휴리스틱 알고리즘들을 제안한다. 필드 데이타의 실험을 통해 제기된 문제 모델의 중요성과 제안된 알고리즘의 효율성을 입증한다.

• 동력기계공학회지
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• 제11권4호
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• pp.38-43
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• 2007

Pulsation is an inherent phenomenon in reciprocating compressors. It interacts with piping to cause vibrations and performance problems. Indiscriminately connecting to a compressor can be dangerous and cost money in the form of broken equipment and piping, poor performance, inaccurate metering, unwanted vibration, and sometimes noise. Piping connected to a compressor can materially affect the performance and response. To minimize these detrimental effects, reciprocating compressor system should be equipped by pulsation suppression system. The system usually comprises bottle volume, called snubber. Snubber is one of the most important parts in hydrogen compressing system. It has installed reciprocating hydrogen compressor. One of these components is snubber which has function to reduce pulsation waveform and to remove the impurities in the hydrogen gas. A snubber has an inclined plate as a buffer, which is installed inside snubber. When the pressure loss and the pulsation of pressure within a snubber is minimized, the snubber could get more applicability. Therefore, a study to find an optimum geometric size on a several snubbers which have different buffer width, has been conducted using a numerical analysis.