• Progress in Superconductivity and Cryogenics
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• v.3 no.2
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• pp.77-83
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• 2001

The thermal characteristics of solid nitrogen are investigated by experiment and analysis for the purpose of evaluating its feasibility as a cooling medium for HTS (high T$_{c}$ superconductor) magnets. A cryostat to refrigerate a liquid-nitrogen container well below its freezing temperature with a 2-stage GM cryocooler is designed and constructed. The spatial distribution of temperature is measure as a function of time during the freezing and melting processes. from which the thermal diffusivity of solid nitrogen can be approximately calculated. the freezing process is formulated and solved by the integral method with an assumption of phase equilibrium at the solid-liquid interface and experimental observation. It may be concluded that the thermal diffusion in solid phase is much slower than in liquid and the degree of super-saturation is quite severe in the solidification of nitrogen.n.

• Progress in Superconductivity and Cryogenics
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• v.15 no.3
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• pp.29-34
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• 2013

This paper introduces design processes of 10 MW class superconducting generator for wind Turbine. Superconducting generator can produce 5 times stronger magnetic field than permanent magnet at least, which enables large scale wind turbine to function as a lighter, smaller and more highly efficient system. These processes are targeted for higher efficiency and shorter high temperature superconductor (HTS) wires to fabricate 10 MW class superconducting generator. Three different approaches will be described in these design processes. First design process focuses on the number of rotor poles. Secondly, 270 and 360 A operating current of superconducting field coil can be adapted as a design parameter in this process. Lastly, 3 and 6 kV line to line voltage of stator coil will be used to design 10 MW class superconducting generator.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.56.3-57
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• 2016

We present a recent progress on calibration of stellar isochrones based on a set of high-resolution spectra for 170 G- and K-type dwarfs in the solar neighborhood. We compare observed magnitudes of these stars in a number of broad passbands [UB(B_T)V(V_T)RIJHK] with model magnitudes generated using ATLAS9 synthetic library at the previously derived set of spectroscopic parameters. We find systematic offsets in colors from these passbands, which are mainly revealed as a function of effective temperature of stars. In order to remove these systematic color mismatches, we derive correction functions and apply them to the model spectra.

• 시스템엔지니어링워크숍
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• s.1
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• pp.145-149
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• 2003

Systems engineering test and evaluation technology development program for (Korea) Express Tilting Train(TTX) system in progress is a national large system development program that is not only a large-size and complex but also muti-disciplinary in nature. For the TTX test and evaluation technology development, verification requirements that could verify system function and performance, should be derived from system specification. Hereafter, this could be listed as items of test. System engineering process establishes traceability between items of test and system requirements. These tasks could be accomplished by the schema. Using the Core, a system engineering tool, TTX program could be database and oter system related to TTX program will be developed effectively and efficiency.

• Progress in Superconductivity and Cryogenics
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• v.5 no.2
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• pp.66-70
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• 2003

Transient magnetic diffusion process in a melt-cast Bi2Sr2CaCu20X(Bi-2212) tube was studied by experimental and numerical analyses. The transient diffusion partial differential equation is transformed into an ordinary differential equation by integral method. The penetration depth of magnetic field into a superconducting tube is obtained by solving the differential equation numerically. The results show that the penetration depth as a function of time which is somewhat different from the results by Bean's critical state model. The reason of the difference between the present results and that of Bean's model is discussed and compared in this paper. This experiment measure the magnetic flux density in the supercondutor after supply direct-current of Bi-2212 rounded by copper coil. This study was discussed of valid of a previous numerical solution which is compared by the penetrate time and the magnetic flux density difference of between the present results and the numerical solution.

• 제어로봇시스템학회:학술대회논문집
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• 1989.10a
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• pp.250-254
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• 1989

This study is to develop the interactive program for work-cell layout of SCAPA type robot using PC. To make the program interactively, we made use of the software which have the function of menu, dialog box, and graphic. By using the mouse, we can progress the program quickly and easily. It has 2 1/2 dimension and provides that one can layout the elements(robot, peripheral device, and etc.), create the work path, and calculate the robot cycle time. By comparing with cycle times of any number of work-cell layout for the same work, we can evaluate work-cell layout and select one work-cell layout to be considered optimal one which has the least cycle time.

• Environmental Mutagens and Carcinogens
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• v.23 no.4
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• pp.115-130
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• 2003

Idiopathic Parkinson's disease (IPD) represents a common neurodegenerative disorder. While epidemiological studies have suggested a number of risk factors including age, gender, race, and inherited disorder, the cumulative evidence supports the view that environmental or occupational exposure to certain chemicals may contribute to the initiation and progress of Parkinsonism. More recently, clinical and laboratory investigations have led to the theory that dysregulation of iron, an essential metal to body function, may underlie IPD by initiating free radical reaction, diminishing the mitochondrial energy production, and provoking the oxidative cytotoxicity. The participation of iron in neuronal cell death is especially intriguing in that iron acquisition and regulation in brain are highly conservative and thus vulnerable to interference from other metals that bear the similar chemical reactivity. Manganese neurotoxicity, induced possibly by altering iron homeostasis, is such an example. In fact, the current interest in manganese neurotoxicology stems from two primary concerns: its clinical symptoms that resemble Parkinson's disease and its increased use as an antiknock agent to replace lead in gasoline. This article will commence with addressing the current understanding of iron-associated neurodegenerative damage. The major focus will then be devoted to the mechanism whereby manganese alters iron homeostasis in brain.

• Molecules and Cells
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• v.41 no.1
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• pp.65-72
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• 2018

Autophagy is an evolutionally conserved cytoplasmic degradation system in which varieties of materials are sequestered by a double membrane structure, autophagosome, and delivered to the lysosomes for the degradation. Due to the wide varieties of targets, autophagic activity is essential for cellular homeostasis. Recent genetic evidence indicates that autophagy has a crucial role in the regulation of animal lifespan. Basal level of autophagic activity is elevated in many longevity paradigms and the activity is required for lifespan extension. In most cases, genes involved in autophagy and lysosomal function are induced by several transcription factors including HLH-30/TFEB, PHA-4/FOXA and MML-1/Mondo in long-lived animals. Pharmacological treatments have been shown to extend lifespan through activation of autophagy, indicating autophagy could be a potential and promising target to modulate animal lifespan. Here we summarize recent progress regarding the role of autophagy in lifespan regulation.

• Progress in Medical Physics
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• v.4 no.2
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• pp.27-36
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• 1993

A relative efficiency of a HPGe detector as a function of the incident gamma ray energy in the range 120 keV to 1500 keV was measured using 21 gamma rays emitted by a $\^$152/Eu source. A semiempirical expression was then determined which can reproduce the measured values reasonably well. The two results are compared to a Monte Carlo simulation calculation.

• Nuclear Medicine and Molecular Imaging
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• v.43 no.3
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• pp.165-173
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• 2009

Nuclear cardiology in Korea is less active, compared to nuclear oncology, but it has been specialized and ramified. Lately, sophisticated nuclear cardiac imaging methods provide more convenience for patients. It is necessary to accurately estimate the recent progress in the imaging devices for nuclear cardiology. Myocardial perfusion imaging is a well established study to evaluate heart function. Myocardial perfusion SPECT and PET have been used for assessment of coronary artery disease with various radiopharmaceuticals. And of late, the development of advanced imaging devices - multi-pinhole technique and high definition imaging technique - and software made the scanning time shorter and expanded the application field. Therefore, it is required to review the nuclear cardiology hardware/software for the clinical practice and research. In this review, the characteristics about recently-developed SPECT/PET and software for nuclear cardiology are described. It is hoped that this information would contribute to improving the activity of nuclear cardiac research in Korea where the research for the fusion imaging combining a and nuclear imaging is drawing more attention.