• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.723-726
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• 2002

In the recent years, as the research and the development of micro and precision machinery become active, the interest of micro actuators using SMA(Shape Memory Alloy) has been increased. The dynamic characteristic analysis of SMA is necessary for actuator application and many common researches report the material characteristics of SMA sufficiently. However, the research of dynamic characteristics is very deficient. In this paper, the helical spring is fabricated with NiTi SMA wire of high resistivity The farce, response speed, temperature, and displacement are measured by digital force gauge, infrared thermometer, and laser displacement sensor so that the dynamic characteristics of this SMA actuator is analyzed.

• 한국정밀공학회지
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• 제22권1호
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• pp.53-60
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• 2005

The wire rope of container crane is a important component to container transfer system and is used in a myriad of various applications such as elevator, mine hoist, construction machinery, and so on. If it happen wire rope failures in operating, it may lead to the safety accident and economic loss, which is productivity decline, competitive decline of container terminal, etc. To solve this problem, we developed the active and portable wire rope fault detecting system. The developed system consists of three parts that are the fault detecting, signal processing, and remote monitoring part. All detected signal has external noise or disturbance according to circumstances. Therefore we applied to discrete wavelet transform to extract a signal from noisy data that was used filter. As experimental result, we can reduce the expense for container terminal because of extension of exchange period of wire rope for container crane and this system is possible to apply in several fields to use wire rope.

• BMB Reports
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• 제51권5호
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• pp.219-224
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• 2018

Necroptosis is an emerging form of programmed cell death occurring via active and well-regulated necrosis, distinct from apoptosis morphologically, and biochemically. Necroptosis is mainly unmasked when apoptosis is compromised in response to tumor necrosis factor alpha. Unlike apoptotic cells, which are cleared by macrophages or neighboring cells, necrotic cells release danger signals, triggering inflammation, and exacerbating tissue damage. Evidence increasingly suggests that programmed necrosis is not only associated with pathophysiology of disease, but also induces innate immune response to viral infection. Therefore, necroptotic cell death plays both physiological and pathological roles. Physiologically, necroptosis induce an innate immune response as well as premature assembly of viral particles in cells infected with virus that abrogates host apoptotic machinery. On the other hand, necroptosis per se is detrimental, causing various diseases such as sepsis, neurodegenerative diseases and ischemic reperfusion injury. This review discusses the signaling pathways leading to necroptosis, associated necroptotic proteins with target-specific inhibitors and diseases involved. Several studies currently focus on protective approaches to inhibiting necroptotic cell death. In cancer biology, however, anticancer drug resistance severely hampers the efficacy of chemotherapy based on apoptosis. Pharmacological switch of cell death finds therapeutic application in drug- resistant cancers. Therefore, the possible clinical role of necroptosis in cancer control will be discussed in brief.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1577-1580
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• 2003

In the recent years, as the research and the development of micro and precision machinery become active, the interest of micro actuators using SMA(Shape Memory Alloy) has been increased. The dynamic characteristic analysis of SMA is necessary for actuator application and many common researches report the material characteristics of SMA sufficiently. However, the research on dynamic characteristics is very deficient. In this paper, the helical spring are fabricated with NiTi SMA wire of high resistivity. The force, response speed, temperature, and displacement are measured by digital force gauge, infrared thermometer, and laser displacement sensor so that the dynamic characteristics of this SMA is analyzed. Also, bidirectional actuator was fabricated and experimented for its performance.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제5B권4호
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• pp.382-391
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• 2005

Increasing of the nonlinear type power electronics equipment, power conditioning systems (PCS) have been researched and developed for many years in order to compensate for harmonic disturbances and reactive power. PCS's not only improve harmonic current and power factor in the ac grid line but also achieves energy saving used by the renewable energy source (RES). In this paper, the implementation of a current controlled voltage source inverter (CCVSI) using RES for PCS is presented. The basic principle and control algorithm is theoretically analyzed and the design methodology of the system is discussed. The proposed system could achieve power quality control (PQC) to reduce harmonic current and improve power factor, and demand side management (DSM) to supply active power simultaneously, which are both operated by the polarized ramp time (PRT) current control algorithm and the grid-interactive current control algorithm. A 1KVA test model of the CCVSI has been built using IGBT controlled by a digital signal processor (DSP). To verify the proposed system, a comprehensive evaluation with theoretical analysis, simulation and experimental results is presented.

• Journal of Biosystems Engineering
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• 제25권1호
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• pp.1-10
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• 2000

This study was conducted to develop the mathmatical model for predicting the side thrust which is generated by the shearing action on the vertical surfaces of the sides of the track. Experiments were conducted with the three different shear plates with grouser length of 1, 3 and 5 cm for two different soil condition using soil bin system. The measured side thrust were compared with the values predicted by the new model developed in this study and by Bekker's model respectively. The values of side thrust predicted by the new model were more close to the measured values than those of the side thrust predicted by Bekker's model . The total thrust measured were also compared with the values predicted by the conventional model which considers only bottom thrust effect and by the new model which contains not only bottom thurst but side thrust effect. The values of the thrust predicted by conventional modelwere lower than measured values for both of the soil conditions and the three levels of grouser length. The maximum errors of conventional model were increased with the increase of grouser length. but the values of the total thrust predicted by the model developed in this study were well matched to the measured ones for both of the soil conditions and the three levels of grouser lengths.

• Agricultural and Biosystems Engineering
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• 제4권1호
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• pp.34-38
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• 2003

A mathematical model was developed for estimating the mechanical interrelation between characteristics of soil and main design factors of a tracked vehicle, and predicting the tractive performance of the tracked vehicle. Based on the mathematical model, a computer simulation program (TPPMTV) was developed in the study. The model considered the continuous change in tension for the whole track of a tracked vehicle, the analysis of shape and tension of the track segment between sprocket and first roadwheel, and the side thrust on both sides of grouser by the active earth pressure theory in predicting the tractive performance of a tracked vehicle. Also, the model contained not only sinkage depth of the track but the pressure distribution under the track in analyzing the side thrust. The effectiveness of the developed model was verified by performing the draw bar pull tests with a tracked vehicle reconstructed for test in loam soil with moisture content of 18.92％. The predicted drawbar pulls by the model were well matched to the measured ones. Such results implied that the model developed in the study could estimate the drawbar pulls well at various soil conditions, and would be very useful as a simulation tool for designing a tracked vehicle and predicting its tractive performance.

• Journal of Biosystems Engineering
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• 제34권4호
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• pp.254-259
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• 2009

Conventional methods for pathogen detection and identification are labor-intensive and take several days to complete. Recently developed biosensors have shown potential for the rapid detection of foodborne pathogens. In this study, an impedimetric biosensor was developed for rapid detection of Salmonella typhimurium. To develop the biosensor, an interdigitated microelectrode (IME) was fabricated by using semiconductor fabrication process. Anti-Salmonella antibodies were immobilized based on either avidin-biotin binding or self assembled monolayer (SAM) on the surface of the IME to form an active sensing layer. To evaluate effect of antibody immobilization methods on sensitivity of the sensor, detection limit of the biosensor was analyzed with Salmonella samples innoculated in phosphate buffered saline (PBS) or food extract. The impedimetric biosensor based on SAM immobilization method produced better detection limit. The biosensor could detect 107 CFU/mL of Salmonella in pork meat extract. This method may provide a simple, rapid, and sensitive method to detect foodborne pathogens.

• 한국정밀공학회지
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• 제18권11호
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• pp.107-115
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• 2001

Most of rotating machineries supported by contact bearing accompany lowering efficiency, vibration and wear. Moreover, because of vibration, which is occurred in rotating shaft, they have the limits of driving speed and precision. The rotor system has parametric variations or external disturbances such as mass unbalance variations in long operation. Therefore, it is necessary to research about magnetic bearing, which is able to support the shaft without mechanical contact and to control rotor vibration without being affected by external disturbances or parametric changes. Magnetic bearing system in the paper is composed of position sensor, digital controller, actuating amplifier and electromagnet. This paper applied the robust control method using quantitative feedback theory (QFT) to control the magnetic bearing. It also proposed design skill of optimal controller, in case the system has structured uncertainty, unstructured uncertainty and disturbance. Reduction of vibration is verified at critical rotating speed even external disturbance exists. Unbalance response, a serious problem in rotating machinery, is improved by magnetic bearing using QFT algorithm.

• Journal of Plant Biotechnology
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• 제37권1호
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• pp.57-66
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• 2010

Programmed cell death systems are important for an active type of cell deaths. Among them, a type of programmed cell death, autophagy is activated in cancer cells in response to multiple stresses and has been demonstrated to promote tumor cell survival and drug resistance. Thus, in the area of cancer, over the time frame form around the 1940s to date, of the 155 small molecules, 73% are other than "synthetic", with 47% actually being either "natural products" or "directly derived therefrom". Autophagy has multiple physiological functions in multicellular organisms, including protein degradation and organelle turnover. Genes and proteins that constitute the basic machinery of the autophagic process were first identified in the yeast system and some of their mammalian orthologues have been characterized as well. Numerous oncogenes, including Akt1, Bcl-2, NF1, PDPK1, class I PI3K, PTEN, and Ras and oncosuppressors, inculuding Bec-1, Bif-1, DAPK-1, p53 and UVRAG suppress or promote the autophagy pathway. Regulation of autophagy in tumors is governed by similar principles of the normal cells, only in a much more complicated manner, given the frequently observed abnormal PI3K activation in cancer and the multitude of interactions between the PI3K/AKT/mTOR pathway and other cell signaling cascades, often also deregulated in tumor cells. Autophagy induction by some anticancer agents underlines the potential utility of its induction as a new cancer treatment modality of development for natural medicines.