• Restorative Dentistry and Endodontics
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• v.31 no.5
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• pp.352-358
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• 2006

The purpose of this study was to investigate the influence of thickness on the degree of cure of dual-cured composite core. 2, 4, 6, 8 mm thickness Luxacore Dual and Luxacore Self (DMG Inc, Hamburg, Germany) core composites were cured by bulk or incremental filling with halogen curing unit or self-cure mode The specimens were stored at $37^{\circ}C$ for 24 hours and the Knoop's hardness of top and bottom surfaces were measured. The statistical analysis was performed using ANOVA and Tukey's test at p = 0.05 significance level. In self cure mode, polymerization is not affected by the thickness. In Luxacore dual, polymerization of the bottom surface was effective in 2, 4 and 6 (incremental) mm specimens. However the 6 (bulk) and 8 (bulk, incremental) mm filling groups showed lower bottom/top hardness ratio (p < 0.05). Within the limitation of this experiment, incremental filling is better than bulk filling in case of over 4 mm depth, and bulk filling should be avoided.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.2 s.332
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• pp.9-14
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• 2005

This paper reports the hot carrier induced RF performance degradation of bulk dynamic threshold voltage MOSFET (B-DTMOS) compared with bulk MOSFET (B-MOS). In the normal and moderate mode operations, the degradations of cut-off frequency $(f_{T})$ and minimum noise figure $(F_{min})$ of B-DTMOS are less significant than those of B-MOS devices. Our experimental results show that the RF performance degradation is more significant than the U performance degradation after hot carrier stressing. Also, the degradation characteristics of RF power Performance of B-DTMOS due to hot carrier effects are measured for the first time.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.162-162
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• 2012

ZnPc and CuPc molecules stacked similar way in the film, but showed different growth modes in thermal evaporation. The distribution of CuPc crystals did not change by the film thickness, whereas the distribution of ZnPc became random as the increase of the film thickness. The disc type nanograins of CuPc were quite regularly distributed at the initial growth regime and the regular distribution of nanograins was kept during the film growth. On the other hand, ZnPc consisted in ellipsoid shaped nanograins and the distribution of nanograins was not regular in the initial growth regime. The irregular distribution of nanograins changed to the regular mode at the later growth regime by showing structure factor in GISAXS measurement. The different initial nanograin distribution in ZnPc and CuPc was related to the different nanostructure in the mixed layer with C60 to form the bulk heterojunction.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1166-1171
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• 2004

The combustion instability acts as a serious obstacle for the lean premixed combustion of gas turbine and even causes the fatal damage to the combustor and whole system. In this experiment, the pressure fluctuation is highly related to the stabilizing position of flame and fuel injection location. The fuel injection location is connected with the convection time of the fresh mixture, which is important time scale to refresh the mixtures near the flame stabilization location. The flame is extremely unstable when the alternative stabilization occurs and bulk mode frequency (${\sim}10Hz$) of pressure fluctuation is observed in this condition. It was found that the convection time scale of the fresh reactant coincided with the time scale of the bulk mode fluctuation. Hence this phenomenon results from the local equivalence ratio change caused by the pressure fluctuation induced by thermo-acoustic effects.

• Journal of the Korean Institute of Telematics and Electronics
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• v.20 no.6
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• pp.52-57
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• 1983

We report a theoretical study on wave propagation in magneto-optic thin-film waveguides. The field distribution and phase velocity of the guided hybrid modes are analyzed in terms of the phase difference of basic system modes and the Faraday rotation of the magneto-optic thin film. Splitting of the phase constant curves due to the F araday rotation is discussed. The present hybridmode analysis leads to a conversion matrix which shows that the distance dependence of the mode conversion in the guide is different from that in the bulk medium.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.3
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• pp.511-518
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• 1997

The technique of fretting fatigue test was developed and fretting fatigue tests of A12024-T4 were conducted under several conditions. The newly developed calibration methods for measuring surface contact tractions showed good linearity and repeatability. The plate type specimen to which tow bridge type pads were attached and vision system was used to observe the crack behaviour. The oblieque cracks appeared in the early stage of crack growth and they became mode I cracks as they grow about 1 mm. The mode I transition points were found to be longer when surface tractions are higher or bulk stress is lower. Before the crack becomes mode I crack, 'well point' where crack grow about rate is minimum, was detected under every experimental condition. The crack behaviour was found to be affected by surface tractions, contact area, bulk stress. It was also found that partial slip and stick condition is most detrimental and the crack starts from the boundary of stick and slip. For gross slip crack started at the outside edge of pad. After crack mode transition, fretting fatigue cracks showed almost same behaviour of plain mode I fatigue cracks. Equivalent stress intensity factor was used to analyze the behaviour of fretting fatigue cracks and it was found that stress intensity factors can be applied to fretting fatigue cracks.

• Journal of the Korean Vacuum Society
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• v.9 no.4
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• pp.400-405
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• 2000

We investigated the effect of TMIn (trimethly-indium) source depletion on InGaAs, InGaAsP and 1.55 $\mu\textrm{m}$ InGaAs/InGaAsP SMQW by using EPISON ultrasonic monitor for measuring the concentration of metalorganic/carrier gas mixtures. And the problems for the growth reproducibility in MOCVD was solved by using an EPISON ultrasonic monitor with closed-loop mode under the condition of TMIn source depletion. The saturation pressure of TMIn was dramatically decreased over consumption of 80%. In the case of bulk epilayer, Up-shifting of 300 arcsec to Ga-rich direction and FWHM broadening by a factor of two in DCXRD spectrum were observed due to the TMIn source depletion. In the case of SMQW, Up-shifting of 300 arcsec to Ga-rich direction in DCXRD spectrum and blue-shift of 40 nm in PL spectrum were observed due to the TMIn source depletion. However, good reproducibility ($\Delta\theta$<$\pm$100 arcsec) was achieved even the condition of 95% of TMIn consumption, when we used the EPISON with closed-loop mode.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.3299-3305
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• 2011

Railroad is considered a representative echo-friendly mode, but there are many civil complaints due to dusts arising in the process of bulk cargo transportation. The freight station which is handling coal are slowly decreasing because of civil complaints. Generally gondolas and hopper cars kinds of freight cars have a role to carry coal such as anthracite and bituminous coal. The railroad competitiveness in the field of bulk cargo transportation is diminishing because there are cost increase and dust emission in the process of transshipment. In this study, we analysed the logistics process of bulk cargo transportation in the point of railroad and we could draw the problems from the logistics process. The results could be used to study various alternatives to improve the process of coal transportation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.9B
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• pp.783-792
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• 2003

We consider a finite-buffer discrete-time queueing system with fixed-size bulk-service discipline: Geo/ $G^{B}$1/K＋B. The main purpose of this paper is to present a performance analysis of this system that has a wide range of applications in Asynchronous Transfer Mode (ATM) and other related telecommunication systems. For this purpose, we first derive the departure-epoch probabilities based on the embedded Markov chain method. Next, based on simple rate in and rate out argument, we present stable relationships for the steady-state probabilities of the queue length at different epochs: departure, random, and arrival. Finally, based on these relationships, we present various useful performance measures of interest such as the moments of number of packets in the system at three different epochs and the loss probability. The numerical results are presented for a deterministic service-time distribution - a case that has gained importance in recent years.s.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.528-530
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• 2008

The effect of consolidation temperature on the microstructure, density and mechanical properties (especially, wear property) of $Al_{92.5}-Fe_{2.5}-Cr_{2.5}-Ti_{2.5}$ alloy fabricated by gas atomization and magnetic pulsed compaction was investigated. All consolidated alloys consisted of homogeneously distributed fine-grained fcc-Al matrix and intermetallic compounds. Relative higher mechanical properties in the MPCed specimen were attributed to the retention of the nanostructure in consolidated bulk without cracks. The as consolidated bulk by magnetic pulsed compaction showed the enhanced wear properties than that of a general consolidation process. In addition, the wear mechanism and fracture mode of MPCed bulk was discussed.