• 한국조경학회지
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• 제26권3호
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• pp.143-151
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• 1998

To develop restoration technologies of natural environment, which is destroyed through the urbanization, industrialization, and the increase of leisure industry, the development of environmental restoration material and those application is greatly needed. Concerning this current issue, an experiment has been conducted to test and an experiment has been conducted to test and analyze the conditions of nutritonal propagation of willow cutting, which is known as a plant with rapid propagation and good growth capability under bad soil conditions and its wide ecological amplitude. 24 various kinds of willow cuttings -2~6 cuttings for each species -were placed into the earth for 57 days and measured the lengths and the diameters of willow cuttings, the possibility of root formation, the total number, and the total length of new shoots and roots. 23 among 24 willow cuttings tested were showing a great growing capacity and a number of new shoots and roots were observed in a relatively short time. This proved that salix is an adequate plant material for quick environmental restoraton . Besides, those willow cuttings could be classified for different site conditions through comparing the ratio of the underground part to the aboveground in total length. The results are as follows; S. dependens, S. matsudana, S. babylonica are the most suitable species for quick vegetaton and S. gracilistyla,S. myricoides,S. alba 'sercia' for erosioni control.

• 대한기계학회논문집A
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• 제24권5호
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• pp.1075-1083
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• 2000

The prediction of the inelastic behavior of the structure is an essential part of reliability assessment procedure, because most of the failures are induced by the inelastic deformation, such as creep and plastic deformation. During decades, there has been much progress in understanding of the inelastic behavior of the materials and a lot of inelastic constitutive equations have been developed. These equations consist of the definition of inelastic strain and the evolution of the state variables introduced to quantify the irreversible processes occurred in the material. With respect to the definition of the inelastic strain, the inelastic constitutive models can be categorized into elastoplastic model, unified viscoplastic model and separated viscoplastic model and the different integration methods have been applied to each category. In the present investigation, the generalized integration method applicable for various types of constitutive equations is developed and implemented into ABAQUS by means of UMAT subroutine. The solution of the non-linear system of algebraic equations arising from time discretization with the generalized midpoint rule is determined using line-search technique in combination with Newton method. The strategy to control the time increment for the improvement of the accuracy of the numerical integration is proposed. Several numerical examples are considered to demonstrate the efficiency and applicability of the present method. The prediction of the inelastic behavior of the structure is an essential part of reliability assessment procedure, because most of the failures are induced by the inelastic deformation, such as creep and plastic deformation. During decades, there has been much progress in understanding of the inelastic behavior of the materials and a lot of inelastic constitutive equations have been developed. These equations consist of the definition of inelastic strain and the evolution of the state variables introduced to quantify the irreversible processes occurred in the material. With respect to the definition of the inelastic strain, the inelastic constitutive models can be categorized into elastoplastic model, unified viscoplastic model and separated viscoplastic model and the different integration methods have been applied to each category. In the present investigation, the generalized integration method applicable for various types of constitutive equations is developed and implemented into ABAQUS by means of UMAT subroutine. The solution of the non-linear system of algebraic equations arising from time discretization with the generalized midpoint rule is determined using line-search technique in combination with Newton method. The strategy to control the time increment for the improvement of the accuracy of the numerical integration is proposed. Several numerical examples are considered to demonstrate the efficiency and applicability of the present method.

• 분석과학
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• 제34권4호
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• pp.153-159
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• 2021

In this study, we describe the development of a new high-performance liquid chromatography (HPLC) method for the simultaneous analysis of six bioactive compounds (including gallic acid, epicatechin 3-gallate, quercitrin, afzelin, quercetin, and kaempferol) from Orostachys japonicus. The extraction method was investigated and optimization of the extraction time (min), solvent composition (%), and solvent to material ratio were conducted. As a result, 30 min extraction with 50% methanol and 40:1 mL/g of solvent: material ratio achieved the highest extraction efficiency with a yield of 3.32 mg/g. Furthermore, the developed HPLC method was validated and the correlation coefficient (R) values were within the satisfactory range of 0.9995-0.9999 over the linearity range of 1.53-417 ㎍/mL. The limit of detection and limit of quantification for the six active components were between 0.03-0.08 ㎍/mL and 0.08-0.26 ㎍/mL, respectively. With these newly optimized and developed methods, four batches of O. japonicus were analyzed to confirm the high extraction efficiency of the method and the feasibility of an application.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.426-426
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• 2009

Diagnostic X-ray system is general and basic medical equipment to be used in mostly medical organizations, but being bombed of radioactivity is a big weak point when irradiates a X-ray to the human body so that ICRP restricted the radiation exposure tolerance of the human body. In order to reduce being bombed, the many research and development is now advanced. A lots of diagnostic X-ray machines have currently used due to the increase of occurrence efficiency of X-ray and precisely the output control by using the inverter which is a high speed switching semiconductors. For getting the confidence of the X-ray machine, the same radiation occurrence, same evaluation, and same irradiation condition are necessary when evaluates X-ray irradiation. It is the most important part for the accuracy of the test result and the patient safety. This paper has produced the high voltage occurrence system of full-wave rectification method by using the LC resonance inverter, and evaluated the irradiation reproducibility in order to use it in diagnosis of the patient.

• 한국기계가공학회지
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• 제19권12호
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• pp.14-20
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• 2020

Currently, the automotive market is intensively researching eco-friendly vehicles such as EV vehicles and hydrogen vehicles. Further, research and developments for the future markets such as autonomous vehicles and the connective cars are coped up continuously along with the rising fuel economy regulations and the emission regulations. In this development, various sensors, batteries, and control devices are fused in order to decrease the weight of the vehicle. Moreover, since the fuel economy regulation is an issue, research on the weight reduction of body parts is underway. Therefore, in this work, a study is conducted to obtain the optimal design of the Dash part that separates the engine room and the passenger seat of the vehicle body by combining lightweight materials with high rigidity materials. The optimal design was obtained using the Finite Element Analysis. Further, AL5083 was used as the lightweight material and ASBC1470 was used for high strength materials. The parts made with this combination of materials had strength equivalent to that of the existing steel and the weight was reduced by 10%.

• 한국전기전자재료학회논문지
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• 제13권3호
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• pp.254-258
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• 2000

Current leads of high $T_{c}$ superconductor were fabricated with Bi excess B $i_{2.2}$/S $r_{1.8}$/C $a_{1}$/C $u_{2}$/ $O_{x}$ composition by rapid cooling method. The dimensions of final samples were fixed 3 mm and 8 mm diameter with 50 mm length each To control uniform density the samples were preformed by CIP(Cold Isostatic Press) process and followed by partial or full melting process after raising up to 90$0^{\circ}C$ for 30min. Plate shaped microstructure was clearly observed adjacent to the Ag tube wall and the size of plate was about 100$\mu$m. However the severe destruction of growth orientation was shown in the inner growth part. critical temperature ( $T_{c}$) was about 53~71K after directional growth while Tc was decreased about 77~80 K before directional growth. After directional growth critical current( $I_{c}$) and critical current density( $J_{c}$) in the specimen of 8 mm diameter at 50 K were about 110 A and 280 A/c $m^2$ respectively.pectively.ely.

• 한국전기전자재료학회논문지
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• 제22권6호
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• pp.516-521
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• 2009

X-ray system which is usefully used in diagnosis of the patient, being bombed of radioactivity is a big weak point when irradiates a X-ray to the human body so that ICRP restricted the radiation exposure tolerance of the human body. In order to reduce being bombed, the many research and development is now advanced. A lots of diagnostic X-ray machines have currently used due to the increase of occurrence efficiency of X-ray and precisely the output control by using the inverter which is a high speed switching semiconductors. For getting the confidence of the X-ray machine, the same radiation occurrence, same evaluation, and same irradiation condition are necessary when evaluates X-ray irradiation. It is the most important part for the accuracy of the test result and the patient safety. This research has produced the high voltage occurrence system of full-wave rectification method by using the LC resonance inverter, and evaluated the irradiation reproducibility in order to use it in diagnosis of the patient.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.226-226
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• 2010

The effects of paste components on the properties of porous $TiO_2$ film electrodes prepared through screen-printing technique were investigated in order to efficiently control and optimize the main fabrication step of the dye-sensitized solar cells (DSC). The screen-printed porous $TiO_2$ films were characterized by ultraviolet-visible (UV-Vis) spectroscopy and scanning electron microscopy (SEM), and applied as a part of the DSC for the energy conversion. The fabricated DSC were evaluated by a solar simulator. The experimental results indicate that the microstructural characteristics of the printed films and the performances of the DSC are dependent on the paste compositions. As a result that the efficiency of DSC prepared by manufactured paste was 0.5%~1% higher than existing paste.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.613-617
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• 2004

This paper presents an experimental study on vibration characteristics of an automotive roof with viscoelastic material. The goal of the study is to extract modal parameters (natural frequency, loss factor, and mode shape) of automotive roof with unconstrained and constrained layer damping treatment. To determine the effective position of the viscoelastic patch on a roof, vibration tests have been carried out for two cases; Aluminum plate with viscoelastic patch on maximum strain energy, and aluminum plate with viscoelastic patch on nodal line. From the result of aluminum plate, it is found that the viscoelastic patch should be attached on the Place with maximum strain energy Part. For the automotive root five Patches of unconstrained or constrained viscoelastic material have been attached on the position of maximum strain energy. This paper addresses that the proper position of viscoelastic patch is very important and the concept of maximum strain energy may be a good criterion f3r the placement of viscoelastic patch.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 추계학술대회 논문집 Vol.16
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• pp.259-262
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• 2003

Superconducting flux flow transistor(SFFT) is based on a control of the Abrikosov vortex flowing along a channel. The induced voltage by moving of the Abrikosov vortex in SFFT is greatly affected by the thickness and width, of channel. In order to fabricate a reproducibility channel in SFFT, we have researched the variation of the critical characteristics of YBCO thin films with the etching time using ICP(Inductively coupled plasma) system. It was certified that the velocity of vortex decreased with increasing the width of channel and was saturated faster in low bias from a simulation. An etching mechanism of YBCO thin films by ICP system was also certified by AFM(Atomic Force Microscope) and by measuring the critical current density with etching time. As measurement result, we could analyze that we should optimize the etching thickness of channel part to construct a flux flow transistor with desired characteristics.