• 한국연소학회:학술대회논문집
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• 2000.05a
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• pp.142-151
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• 2000

Dump combustor is a combustor having a dump plane to make coherent structures. A non-premixed flame dump combustor of simple geometry was constructed. We conducted basic experiments such as frequency response on the combustor to confirm the characteristics of the phenomena as a typical dump combustion and unsteady combustion. Furthermore we visualized the flame front behavior by CH chemiluminescence and high speed motion analysis. In spite of the lack of another data such as velocity, species concentration and temperature, the results showed not only the periodic motion of flame front but the ignition process of vortex ring flame. Also we could check out Rayleigh criterion by combining the visualization data with the pressure data.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.4
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• pp.34-40
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• 2012

In wireless communication system, fading is an unavoidable problem. Hence, errors in form of BER are introduced with the transmitted signal. It is necessary to recognize the behavior of these errors in different fading channels. To obtain the mathematical solution for the average bit error rate(BER) of coherent MPSK, some techniques are presented. In this paper, the impact of diversity is also analyzed over slow and flat Rician fading channel. In here, the value of modulation index, M is varied and the effects of its variation are also depicted. So, these performance curves with different diversity values and fading parameter are useful to design and evaluate the radio channel for faithful communication system.

• Journal of Mechanical Science and Technology
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• v.19 no.6
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• pp.1366-1377
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• 2005

Experimental study was carried out in an atmospheric pressure, laboratory-scale dump combustor showing features of combustion instabilities. Flame structure and heat release rates were obtained from OH emission spectroscopy. Qualitative comparisons were made between line-integrated OH chemiluminescence image and Abel-transformed one. Local Rayleigh index distributions were also examined. Mean temperature, normalized standard deviation and temperature fluctuations were measured by coherent anti-Stokes Raman spectroscopy (CARS). To see the periodic behavior of oscillating flames, phase-resolved measurements were performed with respect to the pressure wave in the combustor. Results on system damping and driving characteristics were provided as a function of equivalence ratio. It also could be observed that phase resolved temperatures have been changed in a well-defined manner, while its difference between maximum and minimum reached up to 280K. These results would be expected to play an important role in better understanding of driving mechanisms and thermo-acoustic interactions.

• Journal of the Korean Geotechnical Society
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• v.15 no.4
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• pp.167-173
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• 1999

In this paper the failure behavior of the reinforced earth retaining wall structures according to the deformed types of the face was studied by model test using carbon rods. In model test the behavior of the face for the model of the reinforced earth wall was divided into three cases : the displacement of the top part(case 1), the lateral displacement(case 2) and the displacement of the lower part (case 3). The photographic method was applied to examine the failure line of the deformed wall with the naked eye. The failure line shows a parabolic shape for case 1, a large circular arc for case 2 and a logarithmic spiral for case 3 in the experimental results. The design failure line for the coherent gravity structure hypothesis was most similar to the failure line for the case of the lower part displacement.

• Journal of the Korean Home Economics Association
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• v.51 no.2
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• pp.187-193
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• 2013

This study investigated the relation between participation in bullying, peer relationship and children's social status. We examined the classified types of social status among 700 fifth and sixth grade elementary schools students. The data were obtained by administering a self-reported questionnaire. Differences were identified with participation in bullying behavior, intimacy friendship and peer support as peer relationship. The collected data were subjected to a descriptive and F-test analysis using the SPSS software program. The results conveyed that social status was different according to the gender difference. Rejected boys presented more bully, reinforce, assistant and victim behaviors. Neglected boys were more victims of bullying. Defensive behavior was more apparent in popular and neglected boys. Furthermore, such boys had high intimate friendships. Popular boys presented distinctively more peer support. Rejected boys represented less intimate friendship and peer support. On the other hand, popular girls portrayed more defensive behavior. However, rejected girls and neglected girls had less defensive behaviors. Victim behaviors were less coherent in popular and neglected girls. Intimate friendship and peer support were mostly apparent in popular girls. Rejected boys represented less intimate friendship and peer support.

• Journal of the Korean Society of Safety
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• v.20 no.3 s.71
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• pp.27-33
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• 2005

The shape memory effect in Ti-50.4at.%Ni alloy after solution treatment at 1273K for 2h and aged at 350, 450, $550^{\circ}C$ for 0.5, 1, 1.5, 2, 4, 10hrs had been investigated by differential scanning calorimetry measurement. It was found that ageing in the temperature range of $350^{\circ}C{\sim}550^{\cric}C$ induced complex transformation behavior, involving the R-phase and multiple-stage martensitic transformation. Usually aged Ni-rich NiTi alloys undergo martensitic transformation on cooling from high temperatures in two step : Austenite to R-phase and then R-phase to Martensite (normal behavior). In sample aged at $350^{\circ}C$ two distinct DSC peaks arised giving evidence of intermediate stages of martensite transformation. This results in the nucleation and growth of coherent $Ni_4Ti_3$-precipitate. These explain all features of the evolution of DSC charts during ageing including the number of distinct DS peaks and their positions.

• Journal of Korean society of Dental Hygiene
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• v.18 no.2
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• pp.239-251
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• 2018

Objectives: The purpose of this study was to investigate the effects of dental hygiene students' clinical practice stress, satisfaction and major satisfaction on career preparation behaviors. Methods:This study was conducted targeting the dental hygiene students who have clinical practice experience. The final 305 subjects were analyzed using SPSS 22.0 program. Results: The correlation between clinical practice stress and career satisfaction and career preparation behavior decreases with the higher degree of clinical practice and career preparation behavior. Analysis results about the affecting factors on the level of satisfaction with major satisfaction factors showed the highest factor of preparation behavior, followed by clinical practice and clinical practice stress in order. Analysis results about the affecting factors on the showed the highest factor of preparation behavior, followed by clinical practice and clinical practice stress in order. Conclusions: The results of this study showed that the higher the satisfaction of clinical practice and the higher the satisfaction of career, the more positive the career preparation behavior. Therefore, it's recommended to support continuous education programs to be coherent with dental hygiene student's career preparation behavior based on reinforcing individual competency by obtaining self-confidence and satisfaction from clinical practice.

• Korean Journal of Social Welfare
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• v.42
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• pp.41-82
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• 2000

The purpose of this study is to provide empirical findings about intragenerational and intergenerational discrepancies in eldercare attitude and behavior in Korea. Specifically, intragenerational discrepancies refer to phenomena in which eldercare attitude and behavior diverge from each other within the caregiving and care-receiving generations, respectively. Intergenerational discrepancies, on the other hand, refer to two kinds of phenomena, one in which eldercare attitudes are different between caregiver and care-receiver and the other in which eldercare behavior is differently recognized between the two parties. For the last couple decades, these kinds of discrepancies tended to be simply assumed without any coherent theoretical and/or empirical rationales. Thus, the current study tried to investigate the degree, pattern, and characteristics associated with the discrepancies. Analysis of data collected from 276 matched pairs of caregivers (i.e., daughters-in-law) and care-receivers (i.e., the elderly) in Kwangju and its suburb areas has indicated a substantial amount of both intra- and inter-generational discrepancies. In other words, both caregivers and care-receivers were found to be experiencing huge discrepancies between attitude and behavior in their respective generation: the factual discrepancies in attitude between the two generations were quite salient: the cognitive discrepancies in behavior between them were salient, too. In addition, it was also found' that the extent to which the discrepancies became salient differed for the three subdimensions of eldercare (i.e., emotional, economic, and physical care), and that such discrepancies have intimate relationships with a set of sociodemographic characteristics for caregivers - notably, age, educational attainment, area of residence, household income - on the one hand, and those for care-receivers - notably, gender, age, educational attainment, cohabitation, family size, inheritance, owned property - on the other. A series of theoretical, empirical, and clinical implications stemming from the findings were suggested and fully discussed in the context of Korean society.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.365-366
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• 2002

The sliding wear behavior of ultra high molecular weight polyethylene (UHMWPE) was examined on a novel low temperature degradation-free zirconia/alumina composite material and conventional alumina and zirconia ceramics used for femoral head in total hip joint replacement. The wear of UHMWPE pins against these ceramic disks was evaluated by performing linear reciprocal sliding and repeat pass rotational sliding tests for one million cycles in bovine serum. The weight loss of polyethylene against the novel low temperature degradation-free zirconia/alumina composite disks was much less than those against conventional ceramics for all tests. The mean weight loss of the polyethylene pins was more io the linear reciprocal sliding test than in the repeal pass rotational sliding lest for all kinds of disk materials. Neither the coherent transfer film nor the surface damage was observed on the surface of the novel zirconia/alumina composite disks during the test. The observed r,'stilts indicated that the wear of the polyethylene was closely related to contacting materials and kinematic motions. In conclusion, the novel zirconia/alumina composite leads the least wear of polyethylene among the tested ceramics and demonstrates the potential as lhe alternative materials for femoral head in total hip joint replacement.

• Journal of Magnetics
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• v.14 no.1
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• pp.11-14
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• 2009

We investigated the I-V curves and differential tunneling conductance of two, CoFeB/MgO/CoFeB-based, magnetic tunnel junctions (MTJs): one with a low tunneling magnetoresistance (TMR; 22%) and the other with a high TMR (352%). This huge TMR difference was achieved by different MgO sputter conditions rather than by different annealing or deposition temperature. In addition to the TMR difference, the junction resistances were much higher in the low-TMR MTJ than in the high-TMR MTJ. The low-TMR MTJ showed a clear parabolic behavior in the dI/dV-V curve. This high resistance and parabolic behavior were well explained by the Simmons' simple barrier model. However, the tunneling properties of the high-TMR MTJ could not be explained by this model. The characteristic tunneling properties of the high-TMR MTJ were a relatively low junction resistance, a linear relation in the I-V curve, and conduction dips in the differential tunneling conductance. We explained these features by applying the coherent tunneling model.