• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.208-211
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• 2001

This paper presents the considerations of the high frequency modulation method for the metal halide lamp electronic ballast. The acousitc resonance phenomenon is occurred, if the metal halide lamp is driven at constant high frequency. The frequency modulation method therefore, is used to avoid the acoustic resonance phenomenon, but the crest factor of lamp current is increased. In this paper, the driving characteristic of the metal halide lamp according to the waveshape and frequency variations of modulating signal is considered with a viewpoint of crest factor.

• Molecules and Cells
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• 제42권5호
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• pp.379-385
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• 2019

Non-coding RNAs (ncRNAs) comprise various RNA species, including small ncRNAs and long ncRNAs (lncRNAs). ncRNAs regulate various cellular processes, including transcription and translation of target messenger RNAs. Recent studies also indicate that ncRNAs affect organismal aging and conversely aging influences ncRNA levels. In this review, we discuss our current understanding of the roles of ncRNAs in aging and longevity, focusing on recent advances using the roundworm Caenorhabditis elegans. Expression of various ncRNAs, including microRNA (miRNA), tRNA-derived small RNA (tsRNA), ribosomal RNA (rRNA), PIWI-interacting RNA (piRNA), circular RNA (circRNA), and lncRNA, is altered during aging in C. elegans. Genetic modulation of specific ncRNAs affects longevity and aging rates by modulating established aging-regulating protein factors. Because many aging-regulating mechanisms in C. elegans are evolutionarily conserved, these studies will provide key information regarding how ncRNAs modulate aging and lifespan in complex organisms, including mammals.

• IMMUNE NETWORK
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• 제20권6호
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• pp.46.1-46.13
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• 2020

Neutrophils are innate immune cells that constitute the first line of defense against invading pathogens. Due to this characteristic, they are exposed to diverse immunological environments wherein sources for nutrients are often limited. Recent advances in the field of immunometabolism revealed that neutrophils utilize diverse metabolic pathways in response to immunological challenges. In particular, neutrophils adopt specific metabolic pathways for modulating their effector functions in contrast to other immune cells, which undergo metabolic reprogramming to ensure differentiation into distinct cell subtypes. Therefore, neutrophils utilize different metabolic pathways not only to fulfill their energy requirements, but also to support specialized effector functions, such as neutrophil extracellular trap formation, ROS generation, chemotaxis, and degranulation. In this review, we discuss the basic metabolic pathways used by neutrophils and how these metabolic alterations play a critical role in their effector functions.

• 대한의용생체공학회:의공학회지
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• 제43권1호
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• pp.1-10
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• 2022

Non-alcoholic fatty liver disease(NAFLD) is excessive hepatic lipid accumulation mainly caused by obesity. This study aimed to evaluate whether micro-current stimulation(MCS) could modulate lipid metabolism regarding the Sirt1/AMPK pathway, fatty acid β-oxidation pathway, and lipolysis and lipogenesis-related factors in FL83B cells. For the NAFLD cell model, FL83B cells were treated with oleic acid for lipid accumulation. MCS were stimulated for 1 hr and used frequency 10 Hz, duty cycle 50%, and biphasic rectangular current pulse. The intensity of MCS was divided into 50, 100, 200, and 400 ㎂. Through the results of Oil red O staining, it was confirmed that MCSs with the intensity of 200 ㎂ and 400 ㎂ significantly reduced the degree of lipid droplet formation. Thus, these MCS intensities were applied to western blot analysis. Western blot analysis was performed to analyze the effects of MCS on lipid metabolism. MCS with the intensity of 400 ㎂ showed that significantly activated the Sirt1/AMPK pathway, a key pathway for regulating lipid metabolism in hepatocytes, and fatty acid β-oxidation-related transcription factors. Moreover, it activated the lipolysis pathway and suppressed lipogenesis-related transcription factors such as SREBP-1c, FAS, and PPARγ. In the case of MCS with the intensity of 200 ㎂, only PGC1α and SREBP-1c showed significant differences compared to cells treated only with oleic acid. Taken together, these results suggested that MCS with the intensity of 400 ㎂ could alleviate hepatic lipid accumulation by modulating lipid metabolism in hepatocytes.

• 한국재료학회지
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• 제25권11호
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• pp.616-621
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• 2015

Atmospheric pressure plasma is used in the biological and medical fields. Miniaturization and safety are important in the application of apply atmospheric plasma to bio devices. In this study, we made a small, pocket-sized inverter for the discharge of atmospheric plasma. We used pulse power to control the neutral gas temperature at which the, when plasma was discharged. We used direct current of 5 V of bias(voltage). The output voltage is about 1 to 2 kilo volts the frequency is about 80 kilo hertz. We analyzsed the characteristics of the atmospheric plasma using OES(Optical emission spectroscopy) and the Current-Voltage characteristic of pulse power. By calculating of the current voltage characteristics, we were able to determine that, when the duty ratio increased, the power that actually effects the plasma discharge also increased. To apply atmospheric plasma to human organisms, the temperature is the most important factor, we were able to control the temperature by modulating the pulse power duty ratio. This means we can use atmospheric plasma on the human body or in other areas of the medical field.

• Journal of Biosystems Engineering
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• 제38권2호
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• pp.113-120
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• 2013

Purpose: Stem cells provide new opportunities in the regenerative medicine for human or animal tissue regeneration. In this study, we report an efficient method for the modulating behaviors of electro-active stem cells by micro-electric current stimulation (mES) without using chemical agents, such as serum or induction chemicals. Methods: Dental pulp stem cells (DPSCs) were cultured on the tissue culture dish in the mES system. To find a suitable mES condition to promote the DPSC functions, the response surface analysis was used. Results: We found that a working micro-current of 38 ${\mu}A$ showed higher DPSC proliferation compared with other working conditions. The mES altered the expressions of intracellular and extracellular proteins compared to those in unstimulated cells. The mES with 38 ${\mu}A$ significantly increased osteogenesis of DPSCs compared with ones without mES. Conclusions: Our findings indicate that mES may induce DPSC proliferation and differentiation, resulting in applying to DPSCs-based human or animal tissue regeneration.

• 전력전자학회논문지
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• 제12권4호
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• pp.291-299
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• 2007

영구자석 동기전동기를 단위 전류 당 최대 토크 운전 점에서 운전하기 위해서는 전동기의 상전류 및 온도에 따라 변화하는 인덕턴스 및 역기전력 상수와 같은 전동기의 파라미터들에 대한 정확한 값을 알고 있어야 한다. 전동기 파라미터의 온라인 추정을 위한 적응 추정 기법은 정확한 값을 추정하는 데 어려움이 있고 복잡한 수학 연산을 필요로 하기 때문에 실질적인 응용에는 적합하지 못하다. 본 논문의 목적은 느린 동적 부하를 가지는 벡터 제어 영구자석 동기전동기 구동장치를 위한 단순한 단위 전류 당 최대 토크 운전 점 추적 제어 전략을 제안하는 것이다. 제안된 방식은 전류 위상각을 조절하고 지령 전력의 변화를 관측함으로써 단위 전류 당 최대 토크 운전 점들을 찾아간다. 전류 위상각 조절 전략은 부하 변동이 지령 전력에 미치는 영향을 감지할 수 있도록 설계된다. 따라서, 제안된 방식은 부하 변동에 관계없이 영구자석 동기전동기의 단위 전류 당 최대 토크 운전 점들을 추적할 수 있다. 컴퓨터 시뮬레이션과 실험을 통하여 제안된 방식의 효용성을 보인다.

• The Journal of Korean Physical Therapy
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• 제23권1호
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• pp.77-82
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• 2011

Purpose: Recently, many studies have demonstrated that application of external stimulation can modulate cortical excitability of the human brain. We attempted to observe cortical excitability using functional magnetic resonance imaging (fMRI) during the application of transcranial direct current stimulation (tDCS) or functional electrical stimulation (FES). Methods: We recruited two healthy subjects without a history of neurological or psychiatric problems. fMRI scanning was done during? each constant anodal tDCS and FES session, and each session was repeated three times. The tDCS session consisted of three successive phases (resting phase: 60sec dummy cycle: 10sec tDCS phase: 60sec). The FES session involved stimulation of wrist extensor muscles over two successive phase (resting phase: 15sec FES phase: 15sec). Results: The average map of the tDCS and FES analyses showed that the primary sensory-motor cortex area was activated in all subjects. Conclusion: Our findings show that cortical activation can be induced by constant anodal tDCS and FES. They suggest that the above stimuli have the potential for facilitating brain plasticity and modulating neural excitability if applied as specific therapeutic interventions for brain injured patients.

• Asian-Australasian Journal of Animal Sciences
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• 제20권2호
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• pp.295-306
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• 2007

The growth and health of the fetus and neonate are directly influenced by the nutritional and physiological status of sows. Sows are often under catabolic conditions due to restrict feeding program during pregnancy and low voluntary feed intake during lactation. The current restrict feeding program, which aims at controlling energy intake during gestation, results in an inadequate supply of dietary protein for fetal and mammary gland growth. Low voluntary feed intake during lactation also causes massive maternal tissue mobilization. Provision of amino acids and fatty acids with specific functions may enhance the performance of pregnant and lactating sows by modulating key metabolic pathways. These nutrients include arginine, branched-chain amino acids, glutamine, tryptophan, proline, conjugated linoleic acids, docosahexaenoic acid, and eicosapentaenoic acid, which can enhance conception rates, embryogenesis, blood flow, antioxidant activity, appetite, translation initiation for protein synthesis, immune cell proliferation, and intestinal development. The outcome is to improve sow reproductive performance as well as fetal and neonatal growth and health. Dietary supplementation with functional amino acids and fatty acids holds great promise in optimizing nutrition, health, and production performance of sows and piglets. (Supported by funds from Texas Tech, USDA, NLRI-RDA-Korea, and China NSF).

• 대한의생명과학회지
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• 제18권3호
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• pp.218-226
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• 2012

Dopamine is an enteric neurotransmitter that regulates gastrointestinal motility. This study was done to investigate whether dopamine modulates spontaneous pacemaker activity in cultured interstitial cells of Cajal (ICCs) from mouse using whole cell patch clamp technique, RT-PCR and live $Ca^{2+}$ imaging analysis. ICCs generate pacemaker inward currents at a holding potential of -70 mV and generate pacemaker potentials in current-clamp mode. Dopamine did not change the frequency and amplitude of pacemaker activity in small intestinal ICCs. On the contrary dopamine reduced the frequency and amplitude of pacemaker activity in large intestinal ICCs. RT-PCR analysis revealed that Dopamine2 and 4-receptors are expressed in c-Kit positive ICCs. Dopamine2 and 4 receptor agonists inhibited pacemaker activity in large intestinal ICCs mimicked those of dopamine. Domperidone, dopamine2 receptor antagonist, increased the frequency of pacemaker activity of large intestinal ICCs. In $Ca^{2+}$-imaging, dopamine inhibited spontaneous intracellular $Ca^{2+}$ oscillations of ICCs. These results suggest that dopamine can regulate gastrointestinal motility through modulating pacemaker activity of large intestinal ICCs and dopamine effects on ICCs are mediated by dopamine2 receptor and intracellular $Ca^{2+}$ modulation.