• Journal of the Korean Solar Energy Society
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• v.27 no.3
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• pp.23-28
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• 2007

In this study, we analyzed the maximum output power characteristics of crystalline silicon photovoltaic module by change of environmental effects. The electrical, optical and thermal property of PV modules were investigated during outdoor test period about 70 days. There was a fluctuation in maximum output power by change in transmittance caused by environment effects like rain, snow and dust. The effects of external environmental change were analyzed using climate data. Also local thermal temperature variation and transmittance imbalance on surface of PV module which might lead degradation of constituent material were detected using infrared camera. The further analysis is describe in the following paper.

• Journal of Korean Medicine Rehabilitation
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• v.19 no.1
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• pp.187-199
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• 2009

Objectives : The electroacupuncture was generally has been used in oriental medicine doctors. In recent years, there have been a few studies about safety and stability of acupuncture needle in itself, but then again research of acupuncture needle safety and stability on applying electroacupuncture have been insignificant. Therefore we investigated the safety and change in mechanical characteristic of acupuncture needle in electroacupuncture therapy. Methods : We observed mechanical characteristic change by SEM(Scanning Electron Microscope) and EDX(Energy Dispersive X-ray Spectroscopy), evaluated the hardness by vickers hardness tester. We used MTT assay and cell stain to study about biocompatibility of electroacupuncture. Results : In this study, any corrosion of material, alternation of elements, and change of hardness were not observed in surface analysis using SEM and EDX. In cytotoxity evaluation using MTT assay and cell stain, cell survival rate was low when practicing the electroacupuncture for more than 3 hours. Conclusions : Change of mechanical property was not observed based on the test results using surface analysis and hardness estimation by the electroacupuncture. And considering the biocompatibility, electroacupuncture was thought to be safe in an hour based on cytotoxity evaluation using MTT assay and cell stain.

• Proceedings of the Korean Institute of Interior Design Conference
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• 2007.05a
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• pp.255-259
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• 2007

Contemporary society is a digital and information-oriented society and a change by digital and information-oriented has made a new society principle and creature. The principle and creature has made society changed having influence on office space. The 21st century business space attachs great importance to the public space as the value of work place, namely, the place of gathering and client meeting which is society space and a thing which grants it with the biggest investment worth is a new order. This kind of society change has been making an appearance in contemporary office space as features of Narrative, Nodal, Neighbourly, Nomadic. These kinds of trends which are not exclusive mutually are stipulated as new trials to business space holding a lot of overriding features in common. These kinds of features brought into relief according to society change can be seen as key words speaking for contemporary office space and have a significance to contemplate and study for the office space of a new concept made an appearance together with society change. It is expected to contribute to revitalization programs with the far-reaching effect of understanding about ideal office work circumstances and work shape which the 21st century wants standing on the features of these new concepts.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.5 no.4
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• pp.394-399
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• 1995

Dielectric properties and crystal structure changes with temperature were observed on $(Na_{0.5}Sr_{0.5})(Ti_{0.5}Nb_{0.5})O_{3}$ which had a superstructure due to oxygen octahedron tilting. Dielectric loss peak observed at 380 K was found to have a relation with a primitive cell change from tetragonal to cubic, however, in this case, dielectric constant variation was not observed. Therefore it was found that the dielectric loss was more senstive than the dielectric constant for detecting the structure change. After the structure change of primitive cell from tetragonal to cubic, X-ray diffraction peaks of superstructure, which completely disappear above 500 K, were still observed. And no dielectric property variations were found with the disappearence of superstucture.

• Proceedings of the KIEE Conference
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• 2005.11a
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• pp.223-225
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• 2005

An external electrode fluorescent lamps (EEFLs) have the advantage of a long lifetime in the early stages of the study on plasma discharge, interest in the lamp continues. Studies on the operation of external electrode fluorescent lamps have focused mainly on its use of a type of high frequency (MHz). By performing high brightness using a square wave operation method with the low frequency below 100kHz, which is applied to a narrowed tube type lamp that has several mm of lamp diameter, an EEFL presented the possibility of using it as a light source for backlights. However, because an EEFL generates plasma using wall charges, which considers the impedance characteristics of glass based on the structural principle in discharge, it can be significantly affected by frequency. Thus, this study verifies the change in the characteristics of electromagnetic fields according to the change in frequency through a Maxwell's electromagnetic field simulation and examines the relationship between the change in the EEFL frequency and brightness by measuring the optical characteristics. In addition, the characteristics of the transformation of energy orbits were verified by investigating the characteristics of the wavelength according to the change in frequency through the OES.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.7
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• pp.408-413
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• 2016

The dielectric thin films applied to multi-colored semitransparent thin film solar cells have been extensively studied. In this work, we prepared GeSbTe and GeTe chalcogenide thin films using magnetron sputtering, and investigated their optical and phase-change properties to replace the dielectric films. The changes of surface morphology, sheet resistance, and X-ray diffraction of the Te-based chalcogenide films support the fact that the amorphous stability of GeTe films is superior to that of GeSbTe films. While both amorphous GeSbTe and GeTe films thinner than 30 nm have optical transparency between 5% and 60%, GeTe films transmit more visible light than GeSbTe films. It is confirmed by computer simulation that the color of semitransparent silicon thin film solar cells can be adjusted with the addition of GeSbTe or GeTe films. Since it is possible to adjust the contrast of the solar cells by exploiting the phase-change property, the two kinds of chalcogenide films are anticipated to be used as an optical layer in semitransparent solar cells.

• Journal of the Korean Society for Heat Treatment
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• v.4 no.3
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• pp.54-62
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• 1991

The effect of tempering temperature on the ultrasonic propagation velocity at SCM 440 steel quenched from $870^{\circ}C$ and $1000^{\circ}C$ has been studied by metallurgical and crystallographical observation. The measurements of ultrasonic velocity were made on the specimen by appling an immersion ultrasonic pulse-echo technique with a constant frequency of 10 MHz. The quenched microstructure of this steel was a lath martensite. As the tempering temperature was increased, the martensite was transformed into the tempered martensite composed of cementite and carbide. The ultrasonic velocity increased with increasing the tempering temperature. It was thought that these were resulted from the microstructural transformation. The change of ultrasonic propagation velocity with quenching and tempering heat treatment was resulted from microstrain due to the change of internal stress. Considering these results concerning to the change of ultrasonic propagation velocity. the phenomena of microstructural transformation were estimated. Consequently, it was thought that the degree of quenching and tempered heat treatment of steel could be nondestructively evaluated with the change of ultrasonic propagation velocity.

• Journal of the Korean Ceramic Society
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• v.54 no.5
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• pp.406-412
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• 2017

$70V_2O_5-10Fe_2O_3-13P_2O_5-7B_2O_3$ glasses were prepared to study the electrical conductivity and catalytic properties of the structural change with crystallization. The structural changes were analyzed by determining the molecular volume from the sample density; using X-Ray Diffraction (XRD) analysis, which indicated that $V_2O_5$, $VO_2$ and $B_2O_3$ crystals in heat-treated more than 1h samples. Especially a new crystalline phase of non-stoichiometric $Fe_{0.12}V_2O_5$ was formed after 6 h heat treatment. The V-O bonding change after crystallization was analyzed by Fourier Transform Infrared Spectroscopy (FTIR); V ion change from $V^{5+}$ to $V^{4+}$ was shown by XPS. Conductivity and catalytic properties were examined based on the polaronic hopping of V and Fe ions, which exhibited different valence states with crystallization.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.11
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• pp.57-62
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• 2019

This paper describes the prediction of eigenfrequencies due to changes in stiffness and mass in the connection area of the lap joint beam in terms of linear and torsional stiffness as well as connection length. The sensitivities of mass and stiffness in the finite element model were derived by using the first-order differential and algebraic equation and were thereafter applied to obtain new natural frequencies that were compared with theoretical exact solutions. Newly predicted natural frequencies due to only a change in stiffness were in relatively good agreement with those in lower modes for rigid joints, while further investigation was needed for flexible joints. On the other hand, only the change in mass resulted in a large discrepancy in the flexible joint case. It may be strongly anticipated that this study will provide a useful tool for estimating modal parameters by change in any design variable, such as the structural dimension, material property, or connection type for a large-scale structure, even though the proposed methodology is currently limited to a jointed beam.

• The Korean Society of Law and Medicine
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• v.15 no.1
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• pp.185-209
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• 2014

While the local health insurance and the employment-based insurance were integrated in July 2000, the insured is divided into employment-based insured and the local insured and the relevant premium has been applied to both groups. The health insurance premium having the feature of social solidarity has to be determined depending on income, that is, the ability to pay in accordance with the principles of social insurance. While employment-based insurance premium has been determined depending on the earned income, the local insurance premium for the local insured has been determined by scoring gross income(evaluated income), property and possession of automobiles. A variety of improvement approaches has been implemented including introduction of the employment-based insurance premium ceiling system (2002) and the change of property scoring system for the local insured (2006). However, the health insurance system which was merged in 2000 has been implemented up to now without significant change even though there were lots of socio-demographic change including increase of income level and the population structure such as low birth and aging. In other words, it is required to implement the premium rating system securing the income-based equity. Nevertheless, it was inevitable to apply the diverse rating standards in the early stage because it was very difficult to verify the income of the self-employed. Although the income verification rate was significantly increased from 23% in 1989 to 44% in 2010, the irrational standards including property, automobiles, living standard and activity rate have been still applied to the local insured because it is difficult to secure the validity of insurance premium rating system and it severely lacks of security. This paper investigated whether the current insurance premium rating system for the local insured imposing the premium on the basis of 'gender' and 'age' complies with the basic human rights secured by the current Constitution of the Republic of Korea with respect to the practical and theoretic irrationality of insurance premium rating system and standards for he local insured. In accordance with the analysis results, this paper proposed the approach to improve the system.