• 대한기계학회논문집B
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• 제28권2호
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• pp.207-214
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• 2004

The burning velocities of conventional and oxygen-enriched methane flame in various equivalence ratio were determined by experiments. The validity of existing reaction mechanisms was examined in oxygen-enriched flame on the basis of the experiment results. Modified reaction mechanism is suggested, which was able to predict burning velocity of oxygen enriched flame as well as methane-air flame. Complementary study on reaction mechanisms shows the following results : Present experiment data were found to be more reliable in comparison with existing ones in a oxygen-enrichment condition. It was found that some modification in existing reaction mechanisms is necessary, since discrepancy between measurements and predictions is increasing with oxygen enrichment ratio. The sensitivity analysis was performed to discriminate the dominantly affecting reactions on the burning velocity in various oxygen enrichment and equivalence ratio. A modified GRI 3.0 reaction mechanism based on our experiment results was suggested, in which reaction rate coefficients of (R38) H+O$_2$<=>O+OH in GRI 3.0 reaction mechanisms were corrected based on sensitivity analysis results. This mechanism showed a good agreement in predicting the burning velocity and number density of NO in oxygen-enriched flame and would provide proper reaction information of oxygen-enriched flame at this stage.

• 한국CDE학회논문집
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• 제5권4호
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• pp.380-392
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• 2000

This paper proposes a qualitative reasoning approach for the spatial configuration of mechanisms that could be applied in the early phase of the conceptual design. The spatial configuration problem addressed in this paper involves the relative direction and position between the input and output motion, and the orientation of the constituent primitive mechanisms of a mechanism. The knowledge of spatial configuration of a primitive mechanism is represented in a matrix form called spatial configuration matrix. This matrix provides a compact and convenient representation scheme for the spatial knowledge, and facilitates the manipulation of the relevant spatial knowledge. Using this spatial knowledge of the constituent primitive mechanisms, the overall configuration of a mechanism is described and identified by a spatial configuration state matrix. This matrix is obtained by using a qualitative reasoning method based on sign algebra and is used to represent the qualitative behavior of the mechanism. The matrix-based representation scheme allows handling the involved spatial knowledge simultaneously and the proposed reasoning method enables the designer to predict the spatial behavior of a mechanism without knowing specific dimension of the components of the mechanism.

• Asian Pacific Journal of Cancer Prevention
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• 제15권2호
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• pp.1057-1060
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• 2014

Adiposity is a well-recognized risk factor of type 2 diabetes and cardiovascular disease, and recently there is increasing evidence that excess body weight is an avoidable cause of cancer, including gastrointestinal, endometrial, esophageal adenocarcinoma, colorectal, postmenopausal breast, prostate, and renal malignancies. The mechanisms whereby adiposity is associated with tumor development remains not well understood. There are some most studied hypothesized mechanisms such as, high levels of insulin and free levels of insulin-like growth factors, sex hormones, adipocytokines, and inflammatory cytokines, adiposity-induced hypoxia, and so on. The potential mechanisms and conclusions in adiposity associated with increased risk for developing malignancy, and the underlying cellular and molecular mechanisms will be studied very well in the near future.

• 동의생리병리학회지
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• 제22권2호
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• pp.315-320
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• 2008

This study investigated the signaling mechanisms contributed to the vasodilatory effects of HMC05, a herbal prescription. HMC05 acted in an endothelium-independent manner. To elucidate the fundamental mechanisms of its vascular actions, we focused on the signaling molecules involved in actin-myosin filament regulation including 20 kDa myosin light chains (LC20), Rho-associated kinase (ROCK), PKC, JNK and extracellular signal-regulated protein kinase (ERK) in the endothelium-denuded thoracic aorta or isolated smooth muscle cells (SMCs). It lowered the phosphorylation level of LC20 and showed that ROCK, ERK, JNK and $PKC{\alpha}$ pathways played important roles in the effects, as confirmed by the observations with a specific inhibition or activation, and with the activity and the subcellular localization of these molecules. In particular, HMC05 dramatically inhibited the activity of ERK and the downstream signaling of ROCK. It also changed the subcellular localization of the phophorylated $PKC{\alpha}$ as well as the amount of phosphorylation. Taken together, these data indicate that the vascular relaxation effects of HMC05 are attributed to the regulation of these signaling mechanisms.

• Journal of Biosystems Engineering
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• 제38권2호
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• pp.129-137
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• 2013

Purpose: Modeling has been used for elucidating the mechanism of complex biosystems. In spite of importance and uniqueness of adolescent calcium (Ca) metabolism characterized by a threshold Ca intake, its regulatory mechanism has not been covered and even not proposed. Hence, this study aims at model-based proposing potential mechanisms regulating adolescent Ca metabolism. Methods: Two different hypothetic mechanisms were proposed. The main mechanism is conceived based on Ca-protein binding which induces renal Ca filtration, while additional mechanism assumed that active renal Ca re-absorption regulated Ca metabolism in adolescents. Mathematical models were developed to represent the proposed mechanism and simulated them whether they could produce adolescent Ca profiles in serum and urine. Results: Simulation showed that both mechanisms resulted in the unique behavior of Ca metabolism in adolescents. Based on the simulation insulin-like growth factor-1 (IGF-1) is suggested as a potential regulator because it is related to both growth, a remarkable characteristic of adolescence, and Ca metabolism including absorption and bone accretion. Then, descriptive modeling is employed to conceptualize the hypothesized mechanisms governing adolescent Ca metabolism. Conclusions: This study demonstrated that modeling is a powerful tool for elucidating an unknown mechanism by simulating potential regulatory mechanisms in adolescent Ca metabolism. It is expected that various analytic applications would be plausible in the study of biosystems, particularly with combination of experimental and modeling approaches.

• 생물환경조절학회지
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• 제10권3호
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• pp.197-206
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• 2001

오존층 파괴에 의해 지표면에 도달하는 자외선, 특히 UV-B(ultraviolet-B radiation, 280∼320nm)의 방사량이 증가하고 있다. UV-B는 유전자의 직접적인 손상, 호르몬 분해, 광합성 억제 등 생리·생화학적 대사기구에 영향을 미쳐 육상 생태계와 안정된 식량 확보에 큰 위협이 되고 있다. 그러나 식물은 UV-B에 대한 방어 기능을 갖고 있으며 형태적 적응, 광 회복 기능, UV-흡수물질의 생합성 촉진 등을 통해 UV-B로부터 생체를 보호한다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 추계학술대회 논문집
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• pp.25-26
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• 2007

At the time when nanostructured materials (NSMs) are becoming a major focus of materials research, the attention of researchers is turning more to their mechanical performance. In contrast with conventional coarse grained materials, which are either strong or ductile, but rarely both at the same time, it is expected that with NSMs both high strength and ductility can be achieved and confirmed by several experimental studies. In spite of the significant interest and efforts in the mechanical properties of NSMs, deformation mechanisms during plastic deformation as well as elastic deformation are not well established yet. In this talk, the deformation mechanisms of NSMs under various grain sizes, temperatures and strain rates were investigated. It is based on recent modelling that appears to provide a conclusive description of the phenomenology and the mechanisms underlying the mechanical properties of NSMs. Based on the theoretical model that provides an adequate description of the grain size dependence of elasticity and plasticity covering all grain size range from coarse down to the nanoscale, the tensile deformation response of NSMs, especially focusing on the deformation mechanisms was investigated.

• 한국공작기계학회논문집
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• 제14권4호
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• pp.41-48
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• 2005

In recent years, the need for multi-stage gear drives which highly reduce output speed has been increased. However, the design of multi-stage gear drives has been carried out by a limited number of experts. The consideration for the direction of input and output axes also makes their design very difficult. The purpose of this study is to develop an algorithm for automatically generating complex multi-stage gear drives and to implement a design supporting system for multi-stage gear drives. There are 4 stages in the proposed algorithm, and major design parameters, such as the direction of input and output axes, reduction ratio, etc. are set up in the first stage. In the second stage, all mechanisms are generated, and various rules are applied to select feasible mechanisms. In the third stage, the gear ratio of each stage is divided from total gear ratio. Next, the specifications of gears for feasible mechanisms are calculated and their bending strength and surface durability are estimated. In the forth stage, appraised indexes are calculated and provided to support the estimation of the generated gear drives.

• Journal of Ginseng Research
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• 제36권1호
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• pp.16-26
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• 2012

Ginseng is one of the most widely used herbal medicines and is reported to have a wide range of therapeutic and pharmacological applications. Ginseng may also be potentially valuable in treating cardiovascular diseases. Research concerning cardiovascular disease is focusing on purified individual ginsenoside constituents of ginseng to reveal specific mechanisms instead of using whole ginseng extracts. The most commonly studied ginsenosides are $Rb_1$, $Rg_1$, $Rg_3$, $Rh_1$, Re, and Rd. The molecular mechanisms and medical applications of ginsenosides in the treatment of cardiovascular disease have attracted much attention and been the subject of numerous publications. Here, we review the current literature on the myriad pharmacological functions and the potential benefits of ginseng in this area. In vitro investigations using cell cultures and in vivo animal models have indicated ginseng's potential cardiovascular benefits through diverse mechanisms that include antioxidation, modifying vasomotor function, reducing platelet adhesion, influencing ion channels, altering autonomic neurotransmitters release, and improving lipid profiles. Some 40 ginsenosides have been identified. Each may have different effects in pharmacology and mechanisms due to their different chemical structures. This review also summarizes results of relevant clinical trials regarding the cardiovascular effects of ginseng, particularly in the management of hypertension and improving cardiovascular function.

• 한국통신학회논문지
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• 제33권5B호
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• pp.356-363
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• 2008

1983년 미국에서 보편적서비스 지원을 위한 기금제도(USF: Universal Service Fund)가 도입된 이래 각국 정부는 저렴한 요금으로 모든 국민들이 기본적인 통신서비스를 제공받을 수 있도록 보편적서비스 지원제도를 운영하고 있다. 국내에서도 2000년 이래 보편적서비스 지원제도가 도입되었고, 최근에 제도개선논의가 활발히 전개되고 있다. 본고에서는 주요국의 보편적서비스 손실금 지원제도를 비교분석하고 국내 제도 개선시 시사점을 찾아보고자 한다.