• The Journal of Korean Academy of Prosthodontics
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• v.9 no.1
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• pp.29-34
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• 1969

Occlusal force is a critical factor affecting the condition and structure of the periodontium. When the occlusal forces exceed the physiologic adaptive capacity of the tissues, tissue damage ensues. Such damage is referred to as trauma from occlusion. Excessive pressure causes compression, degeneration and realignment of the periodontal ligament fibers so that they are paralleled perpendicular to the tooth and bone. By inducing excessive occlusal forces with a high amalgam filling on rat's molar, the author observed histologic alterations of the periodontal ligament fibers by means of Hematoxylin-eosin, Van Gieson and Aldenyde fuchsin stainings. The results of the study were observed as follows: 1) The excessive occlusal forces altered arrangement of the collagenous fibers. 2) The arrangement of the oblique fibers showed appreciable differences between the control group and the group subjected to 10 days experimental trauma from occlusion. 3) The realignment of the transseptal fibers was not found. 4) The arrangement of the oblique fibers after 15 days of trauma from occusion was similar to that of 10 days experimental group. 5) The oxytalan fibers were more abundant at the cementum rather than at the alveolar bone. 6) The excessive occlusal forces produced funnel-shaped widening of the oxytalan fibers, which followed wavy course. 7) The oxytalan fibers appeared to be distributed mainly around the middle third of the root rather than that of the apical third of the root during the experimental trauma from occlusion.

• Journal of The Korean Astronomical Society
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• v.26 no.2
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• pp.89-98
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• 1993

Magnetostatic models of starspots of late type main sequence stars$(G5V\~K5V)$ have been constructed to investigate their physical characteristics by using the similarity law suggested by Schluter and Temesvary(1958) and later employed by Deinzer(1965) and Yun(1968). The starspots are assumed to be single, circular and in horizontal magnetostatic equilibrium. In the present study we considered only those model spots whose area covers less than $12\%$ of the entire stellar surface as suggested by observations. The computed surface field strength of our model spots ranges from $10^3$\;to\;several\;10^3$ gauss and their magnetic flux is found to be $10\~100$ times that of sunspots. The field strength is sensitive to spectral type, which increases with later spectral type. In contrast to the field strength, the area of starspots depends strongly on the total magnetic flux. Finally, it is noted that the computed field strength of model spots belonging to $G0V\~G5V$ falls below the equipartition field strength at their parent stellar surface unless the coverage is less than $2\%$. This suggests that the observed spot on $G0V\~G5V$ stars is likely to be a group of small starspots.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.3
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• pp.245-249
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• 2010

Two dimensional(2D) pair-photonic crystals (pair-PCs) have been fabricated by a multiple-exposure nanosphere lithography (MENSL) method using the self-assembled nanospheres as lens-mask patterns and the collimated laser beam as a multiple-exposing source. The arrays of the 2D pair-PCs exhibited variable lattice structures and shape the control of rotating angle (${\Theta}$), tilting angle (${\gamma}$) and the exposure conditions. In addition, the base period or filling factor of pair-PCs as well as their shapes could be changed by experimental conditions and nanosphere size. A 1.18-${\mu}m$-thick resist was spincoated on Si substrate and the multiple exposure was carried out at change of ${\gamma}$ and ${\Theta}$. Images of prepared 2D pair-PCs were observed by SEM. We believe that the MENSL method is a suitable useful tool to realize the pair-periodic arrays of large area.

• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.1
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• pp.57-64
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• 2013

The functional characteristic of LISN circuit, which is used for measurements of conductive noise in mains power line, is basically related to frequency characteristics of passive elements like inductors used in the circuit as well as the frequency response of inductors is highly related to the resins used in the varnishing process. The significant problem in determination of an inductor's frequency characteristic is the intrinsic resistance, inductance and parasitic capacitance. In this triplet, the parasitic capacitance is the major limiting factor of inductor's frequency range. This capacitance depends on inductor design parameters and materials filling the spaces of coil like resin and its coherency after curing process. In this paper, two similar inductors were designed and built. The first inductor was not varnished while the second one was varnished with VPI technology. VPI, or Vacuum, Pressure, Impregnation technology is one of the most reliable methods performing good insulating conditions for electrical circuits and windings based on resins. The measured results show that implying varnishing technology does not significantly affect the frequency response. However, due to mechanical solidity aspects and improved environmental protection, it is better to varnish the inductors.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.43.2-44
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• 2018

One of the keys to interpreting the characteristics and evolution of interstellar medium in the Milky Way is to understand the distribution of hot gas ($10^5-10^6K$). Gases in this phase are difficult to observe because they are in low density and lack of easily observable tracers. Hot gases are observed mainly in the emission of the FUV ($912-1800{\AA}$), EUV ($80-912{\AA}$), and X-rays (T> $10^6K$) of which attenuation is very high. Of these, FUV emission lines originated from high-stage ions such as O VI and C IV can be the most effective tracers of hot gases. To determine the spatial distribution of O VI and C IV emissions, we have analyzed the spectra obtained from FIMS (Far-ultraviolet IMaging Spectrograph), which covers about 80 percent of the sky. The hot gas volume filling factor, which varies widely from 0.1 to 0.9 depending on the supernova explosion frequency and the evolution model, has been calculated from the O VI and C IV maps. The hot gas generation models has been verified from the global distribution of O VI and C IV emissions, and a new complementary model has been proposed in this study.

• Korean Journal of Human Ecology
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• v.13 no.1
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• pp.123-133
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• 2004

To investigate the factors that contribute to consumer satisfaction with the purchase of clothing, questionnaires were distributed and then consumer groups were classified according to their fashion life style on the internet shopping. The results were as follows: 1. Consumers groups were classified into trendy, Indifferent, brand inclined, conservative, and practicality- minded group by the fashion life style of the internet users. 2. From the analysis of the satisfaction factors on the internet clothing shopping, the factors were product variety, shopping convenience, customer service, confidence in order filling. 3. The most important consumer satisfaction factors according to the fashion life style were as follows: the trendy group considered the variety of clothing design most important. As for the Indifferent group, the tn, diversified collection of the products, and the convenience of unlimited time and space access that the internet site provided, were highly appreciated. With regard to the brand-inclined group, the presentation of product information and the convenience of unlimited time and space factors were highly appreciated. For the conservative group, the time and space factor were highly regarded, As far as the practicality-minded group was concerned, product price and size, the convenience of unlimited time and space access, and punctual delivery schedule were focused.

• The Journal of Industrial Distribution & Business
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• v.9 no.6
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• pp.25-35
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• 2018

Purpose - In this study, the importance of interpersonal relations in the workplace as well as its correlation to satisfaction of social workers were investigated. In addition, effects of organizational culture as well as its implications for human resource management in social welfare workers were outlined. Research design, data, and methodology - A questionnaire was conducted on job satisfaction measured by the Minnesota Job Satisfaction (MSQ) questionnaire. For reliability, the questionnaire was distributed and collected by the self - filling method. From the collected data, reliability analysis, validity analysis (exploratory factor analysis) and multiple regression analysis were used. Cronbach's alpha was used to measure the reliability of the measurement variables and validity analysis was conducted to see if the questionnaires had the same concept as well as SPSS 19.0. Results - The results showed that group culture, hierarchical culture, and rational culture had significant positive effects on job satisfaction. Developmental culture had no effect on the job satisfaction levels. Conclusions - It is important to maintain the hierarchy in order to improve the efficiency of social welfare organizations, but social welfare organizations must accept external opinions and actively listen to the opinions of the employees in the organization.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2002.02a
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• pp.253-259
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• 2002

Micro cell structures with high aspect ratio were fabricated by injection molding method. The mold inserts had dimension $1.9cm\times8.3cm$ composed of a lot of micro posts and were fabricated by LIGA process. The size of the micro posts was $157{\mu}m\times157{\mu}m\times500{\mu}m$ and the gaps between two adjacent posts were $50{\mu}m$. Using Polymethylmethacrylate (PMMA) injection molding was performed. The key experimental variables were temperature, pressure, and time. By controlling these, good shaped mim cell structures with $50{\mu}m$ in wall thickness and $500{\mu}m$ in depth were obtained. In order to understand micro molding mechanism, shape changes of molded PMMA were studied with experimental variables. And the durability of mold insert was investigated, too. The results show that the most important factor in molding processes was the mold temperature that is closely related to the filling of the melt into the micro cavity. And the holding time before cooling showed a great effect on the quality of molded PMMA.

• Progress in Superconductivity and Cryogenics
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• v.17 no.1
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• pp.14-16
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• 2015

Due to the considerable development of the technology of second generation high-temperature superconductors and a significant improvement in their mechanical and transport properties in the last few years it is possible to use HTS tapes in the magnetic levitation systems. The advantages of tapes on a metal substrate as compared with bulk YBCO material primarily in the strength, and the possibility of optimizing the convenience of manufacturing elements of levitation systems. In the present report presents the results of the magnetic levitation force measurements between the stack of HTS tapes containing $n=2{\div}200$ of tapes $12mm{\times}12mm$ and NdFeB permanent magnet in the FC and ZFC regimes. It was found a non- linear dependence of the levitation force from the height of the array of stack in both modes: linear growth at small thickness gives way to flattening and constant at large number of tapes in the stack. Established that the levitation force of stacks comparable to that of bulk samples. The numerical calculations using finite element method showed that without the screening of the applied field the levitation force of the bulk superconductor and the layered superconductor stack with a critical current of tapes increased by the filling factor is exactly the same, and taking into account the screening force slightly different.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.8
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• pp.726-730
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• 2007

Two dimensional photonic crystals (2D PCs) have been fabricated by a double exposure holographic method using a He-Cd laser with a wavelength of 442nm. The arrays of the 2D PCs exhibit variable lattice structures from square to triangle according to a change of rotating angle $({\gamma})$ for double exposure beams. In addition, the period and filling factor of PCs as well as the forms (dot or antidot) could be controlled by experimental conditions. $A l.18-{\mu}m-thick$ resist was spin-coated on Si substrate and the 1st holographic exposure was carried out at incident angle $({\theta})$ of $11^{\circ}$. Then the sample was rotated to ${\gamma}=45^{\circ}{\sim}90^{\circ}$ and the 2nd holographic process was performed at ${\theta}=11^{\circ}$. The variation of diffraction efficiency during the exposure process was observed using a He-Ne laser in real time. The images of 2D PCs prepared were analyzed by SEM and AFM. We believe that the double holographic method is a tool suitable to realize the 2D PCs with a periodic array of large area.