• Structural Engineering and Mechanics
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• 제18권3호
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• pp.343-362
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• 2004

Rocking response of rigid bodies with rectangular footprint, freely standing on horizontal rigid plane is studied analytically. Bodies are subjected to simulated single component of horizontal earthquakes. The effect of baseline correction, applied to simulated excitations, on the rocking response is first examined. The sensitiveness of rocking motion to the details of earthquakes and geometric properties of rigid bodies is investigated. Due to the demonstrated sensitivity of rocking response to these factors, prediction of rocking stability must be made in the framework of probability theory. Therefore, using a large number of simulated earthquakes, the effects of duration and shape of intensity function of simulated earthquakes on overturning probability of rigid bodies are studied. In the case when a rigid body is placed on any floor of a building, the corresponding probability is compared to that of a body placed on the ground. For this purpose, several shear frames are employed. Finally, the viability of the energy balance equation, which was introduced by Housner in 1963 and widely used by nuclear power industry to estimate the rocking stability of bodies, is evaluated. It is found that the equation is robust. Examples are also given to show how this equation can be used.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.149-149
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• 2016

Ceramic is widely known material due to its outstanding mechanical property. Besides, Zirconia(ZrO2) has a low thermal conductivity so it is advantage in a heat insulation. Because of these superior properties, ZrO2 is attracted to many fields using ultra high temperature for example vehicle engines, aerospace industry, turbine, nuclear system and so on. However brittle fracture is a disadvantage of the ZrO2. In order to overcome this problem, we can make the ceramic materials to the forms of ceramic nanoparticles, ceramic nanowhiskers and these forms can be used to an agent of composite materials. In this work, we selected Au catalyzed Vapor-Liquid-Solid mechanism to synthesize ZrO2 nanowhiskers. The ZrO2 whiskers are grown through Hot-wall Chemical Vapor Deposition(Hot wall CVD) using ZrCl4 as a powder source and Au film as a catalyst. This Hot wall CVD method is known to comparatively cost effective. The synthesis condition is a temperature of $1100^{\circ}C$, a pressure of 760torr(1atm) and carrier gas(Ar) flow of 500sccm. To observe the morphology of ZrO2 scanning electron microscopy is used and to identify the crystal structure x-ray diffraction is used.

• 비파괴검사학회지
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• 제29권6호
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• pp.570-578
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• 2009

Excitation and propagation of guided waves are very complex problems in pipes due to their dispersive nature. Pipes are commonly used in the oil, chemical or nuclear industry and hence must be inspected regularly to ensure continued safe operation. The normal mode expansion(NME) method is given for the amplitude with which any propagating waveguide mode is generated in the pipes by applied surface tractions. Numerical results are calculated based on the NME method using different sources, i.e., non-axisymmetric partial loading and quasi-axisymmetric loading sources. The sum of amplitude coefficients for 0~nineth order of the harmonic modes are calculated based on the NME method and the dispersion curves in pipes. The superimposed total field which is namely the angular profile, varies with propagating distance and circumferential angle. This angular profile of guided waves provides information for setting the transducer position to find defects in pipes.

• 한국실내디자인학회논문집
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• 제19권2호
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• pp.225-233
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• 2010

At this point in time South Korea is rapidly metastasizing to a aging society. A major cause of aging can be summarized as increased life expectancy, decrease of nuclear family and birthrate, and South Korea's progress is faster than any other country. From the 1970s, western society has changed social welfare to deinstitutionalization and community care because of problems about economic reason and facilities protection, so the type of elderly social service has also changed from the facility welfare service which is accommodated old people in certain facility to community welfare service which provides various welfare services with living together. Public facilities for low income group which are supported by government are lower, 6.6%, than the United States or Japan, 50%. They are divided into private manage facilities and subscription elderly facilities. These subscription elderly residential facilities show poor administration because of focusing on development and market analysis for investment returns. Therefore, in order to vitalize the elderly welfare residential facilities in Korea, we need plans about systematic services facilities for welfare and phased medical treatments. Therefore, the purpose of this study is that (1) the types and functions of residents for community elderly residential facilities in elderly welfare policies of U.S., and supported policies are researched as a transcendental model, (2) data about operating system with the principles of the market is analyzed, and (3) basic data about welfare facility plan for community residential elderly people is provided.

• 한국해양공학회지
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• 제22권5호
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• pp.100-105
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• 2008

A106 Carbon Steel has recently been used as the material for pipes, nozzles, and tank shells in nuclear power plants. Its corrosion resistance gives the steel many advantages for use in structures under high temperature and high pressure. This steel is also expected to be used as a structural material in the shipbuilding industry for applications involving severe conditions, such as high temperature and pressure. In this study, the mechanical properties of A106 carbon steel were evaluated in regard to its corrosion times. The tensile and yielding strengths decreased as the corrosion time increased. In particular, the tensile strength was influenced by corrosion. In addition, an acoustic emission (AE) technique was used to clarify the microscopic damage to specimens that had undergone corrosion for a certain period. It was found that AE parameters, such as events, energy, duration time, and amplitude were useful for evaluating the degree of damage and remaining life of the corroded specimen. Various properties of the waveform and frequency range were also seen, based on the degree of damage to the specimen from the corrosion time.

• 한국생산제조학회지
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• 제21권4호
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• pp.658-665
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• 2012

Micro-EDM is widely used in metallic pattern, electronics, nuclear power and industry in the form of precision process. The improvement of Electro Discharge Machining has been on a steady progress since $19^{th}$ century. The technology has overcome the limits of the traditional precision process, enabling micro-EDM, micro electrolytic machining, micro drilling, micro punching and laser beam machining, which create versatile products with smaller sizes. What have been known about the major feature of Micro-EDM is high thermal energy so that their products are free from the hardness of their products as long as they are electrical conductor. However, each metal is suspected to have different features and natures even if they are created through the same procedure. In this thesis, the methodology of Micro-EDM and how to categorize them are explained. Also, the nature of the examined materials with surface shape and surface roughnes are analyzed. The results of the experiments are expected to understand surface roughness and workability of other materials for Micro-EDM.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.922-925
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• 2002

Klystron which is micro wave amplifier tube are mainly used in fields of science such as accelerator, nuclear fusion, broadcasting, communication fields, and defense industry fields, tract. The quality of Klystron anode and cavity are determined by form accuracy and roughness of the worked surface. Therefore anode and cavity are restricted the from accuracy strictly and the surface roughness be under Rmax 0.03S. As a work material of anode and cavity, the oxygen-free copper, that is used for optical pares of aerospace and laser mirror is selected. An outside diameter of material is $\Phi$100 mm and an inside diameter is $\Phi$30~33 mm. In this study, to find the optimum ultra precision cuffing condition of oxygen-free copper with diamond turning machine, the surface roughness is examined for various diamond toot nose radius, main spindle speed, fred rate and depth of cut. As a result of experiment, we could machined the anode and cavity with a surface roughness within Ra 3.2 nm, a form accuracy within 0.01 $\mu\textrm{m}$.

• 한국실내디자인학회논문집
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• 제15권5호
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• pp.141-148
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• 2006

Recently, human's life is more longer and the birth rate continually decrease by the development of medical technology. In 2026 the ratio of the elderly will come up to 20.8% and be a 'post-aged society'. Development of economy and industrialization not only accelerate the urbanization and formation of nuclear family, but also change the changing of traditional society and one's value. So the issue of society and value's changing in the elderly increase the centralizing in the silver industry, and by the recent research about the elderly, they not want to live with their children, but want to live independently. This study is meaningful at the next generation of Ubiquitous society and post-aged society, proposing the smart silver town in urban type and let the elderly keeping the existing life in city. It realize the concept of 'Aging in Place' and propose the smart silver town in urban type which appropriate to behavior of the elderly, and being satisfy with various requirements of the elderly. This study point up the combination of physical elements and electronic elements through the smart technology, and making an smart environment to compose the smart silver town in urban type which react the behavior of the elderly.

• 대한산업공학회지
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• 제41권3호
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• pp.259-266
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• 2015

Among many energy resources, natural gas has recently received a remarkable amount of attention, particularly from the electrical generation industry. This is in part due to increasing shale gas production, providing an environment-friendly fossil fuel, and high risk of nuclear power. Because South Korea, the world's second largest LNG importing nation after Japan, has no international natural gas pipelines and relies on imports in the form of LNG, the natural gas has been traditionally procured by long term LNG contracts at relatively high price. Thus, there is a need of developing an Asian LNG trading hub, where LNG can be traded at more competitive spot prices. In a natural gas spot market, the amount of natural gas to be bought should be carefully determined considering a limited storage capacity and future pricing dynamics. In this work, the problem to find the optimal amount of natural gas in a spot market is formulated as a Markov decision process (MDP) in risk neutral environment and the optimal base stock policy which depends on a stage and price is established. Taking into account price and demand uncertainties, the basestock target levels are simply approximated from dynamic programming. The simulation results show that the basestock policy can be one of effective ways for procurement of LNG in a spot market.

• Journal of Applied Biological Chemistry
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• 제59권1호
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• pp.19-23
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• 2016

A phenol substance was extracted from Pinus koraiensis Siebold et Zucc leaf extracts and its biological efficacy was measured. The highest content of the phenol substance contained in Pinus koraiensis Siebold et Zucc leaves was 13.5 mg/g, which was obtained when it was extracted with 80% ethanol. At a concentration of 200 mg/mL, the phenolic substances extracted with 80% ethanol and water showed antimicrobial activities against Helicobacter pylori, producing clear zones of 10 and 12 mm diameter, respectively. Pinus koraiensis Siebold et Zucc. leaf extracts were separated using a Sephadex LH-20 column and 4 fractions were obtained (fractions A-D). Fractions C and D showed the greatest inhibitory activity against Helicobacter pylori producing 10.1 and 12.3 mm clear zones, respectively. These two fractions were purified using a Sephadex LH-20 and MCI-gel column ($H_2O{\rightarrow}100%$ ethanol). Purified compounds A and B were identified as syringic acid and compound C was identified as p-coumaric acid based on $^1H$-nuclear magnetic resonance (NMR), $^{13}C$-NMR, and fast atom bombardment mass spectrometry spectra. When two or more purified compounds were mixed, a synergistic effect of anti-Helicobacter pylori activity was evident. This result indicates that extracts of Pinus koraiensis Siebold et Zucc leaves could be considered a functional food because of their high antimicrobial properties.