• Journal of the Korean Ceramic Society
• /
• v.22 no.5
• /
• pp.23-28
• /
• 1985

A model for degradation of $eta$-$Al_2O_3$ is derived from sress generated by Poiseuille pressure capillary effect and effulent flux in charging process of Na-S Battery. Critical current density for degradation increase with increasing the crack length and crack tip radius. radius 10-7cm and crack length 10-5cm Dependence of crack growth velocity on crack lengh is seperated two regions that is for a large crack length it is predominated by Poiseuille pressure and effulent fluex but in the case of small crack length it is controlled by capillary effect.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.34 no.2
• /
• pp.192-197
• /
• 1989

Two sweet corn hybrids, 'Tanok l' and 'Golden Cross Bantam 70 (GCB 70)' were grown at five plant densities, of 4, 167. 5,556, 6,667. 8, 333, and 11, 111 plants per 10 ares, with or without tiller removal, to determine effects of tiller removal on growth and yield of sweet corn hybrids at various plant densities. Tillers were pulled when less than 15 cm tall. The number of tillers per plant linearly decreased as plant density increased. The two hybrids had similar plant height, ear length and diameter, ear weight and the number of ears per plant and 10 ares. Tanok 1 lodged approximately 20％ at above 8,333 plants per 10 ares, while GCB 70 did not lodge at all, at any plant density. Tanok 1 had higher leaf area index (LAI), ear and stover yields than GCB 70. Except for root lodging and LAI, hybrid x plant density interaction was not significant at 5％ probability level. Plant density did not affect silking data. Increasing plant density linearly increased plant height, LAI, and stover yield, but linearly decreased ear length, ear weight, and the number of ears per plant. Increase in LAI was greater in Tanok 1 than in GCB 70, with increasing plant density. The relationships between the number of ears and ear yield per 10 ares and plant density were Quadratic. The optimum plant density was estimated to be approximately 6500 plants per 10 ares, using the equation based on ear yield. Except for ear height and LA I, hybrid x tiller removal and plant density x tiller removal interactions were not significant. Hybrid x plant density x tiller removal interaction was not significant for any characters. When averaged over hybrids and plant densities, tiller removal reduced plant height and ear and stover yields by about 3, 10, and 16％, respectively, but did not significantly affect silking date, root lodging, ear length and diameter and the number of ears per plant and per 10 ares. The results indicate that the optimum plant density is approximately 6500 plants per 10 ares, regardless of tiller removal and tillers are not to be removed at any plant density.

• Journal of the Korean Vacuum Society
• /
• v.17 no.5
• /
• pp.408-418
• /
• 2008

The rectangular resonant cavity was designed and characterized as a microwave plasma source for focused ion beam. The optimum cavity was calculated analytically and analyzed in detail by using HFSS(High Frequency Structure Simulator). Since the resonant cavity can be affected by the permittivity of quartz chamber and plasma, the cavity is designed to be changeable in one direction. By observing the microwave input power at which the breakdown begins, the optimum cavity length for breakdown is measured and compared with the calculated one, showing in good agreement with the optimum length reduced by 10cm according to the permittivity change in the presence of quartz chamber. The shape of breakdown power curve as a function of pressure appears to be similar to Paschen-curve. After breakdown, plasma densities increase with microwave power and the reduced effective permittivity in the cavity with plasma results in larger optimum length. However, it is not possible to optimize the cavity condition for high density plasmas with increased input power, because too high input power causes expansion of density cutoff region where microwave cannot penetrate. For more accurate microwave cavity design to generate high density plasma, plasma column inside and outside the density cutoff region needs to be treated as a conductor or dielectric.

• Proceedings of the IEEK Conference
• /
• 2002.06e
• /
• pp.99-102
• /
• 2002

In this work, we evaluated the performance of soft iterative decoder with soft block decoder in optical storage system. Because optical storage system requires run- length limited code in general, adaptation of the soft decoders such as turbo code or LDPC(low density parity check code) is difficult without soft block decoders. The performance of the overall optical detection system is evaluated and the simplified channel detection is also proposed.

• Journal of the Optical Society of Korea
• /
• v.17 no.4
• /
• pp.296-299
• /
• 2013

A low density lipoprotein (LDL) cholesterol testing device, structured with serial reflected face-to-face mirror (SRM) allowing spectrophotometry measurements, is presented. The spectrophotometry has been employed to measure the amount of light that a sample absorbs, but it generally should have had path length longer than 10 mm to secure enough sensitivity. Such requirement of path length has often been problematic in implementing a thin type of lab on a disc (LOD). We developed the SRM system which was implemented in a detection chamber with 1.4mm thickness, providing path length longer than 10mm, and thus straightforwardly being applicable to LOD as thin as a compact disc. The experimental results show that the SRM system gives not only a much thinner design compared to the conventional spectrophotometry-based LOD but also a comparable performance to already commercialized spectrometers.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
• /
• 2001.11a
• /
• pp.169-172
• /
• 2001

There are many people who suffer from simulation sickness when immersing in virtual reality. In this study, we analyzed two photoplethysmogram(PPG) parameters - a second derivative parameter and power spectral density ratios - in order to relate PPG parameters with simulation sickness. 36 young, healthy subjects were participated in the experiment, and each subject was equipped with a PPG electrode during his or her immersion. Simulation sickness section was defined as a 7 - second section which starts from the point where a subject reported simulation sickness, and normal section as a same-length section where no physical stimuli was presented to him or her. We compared the PPG parameters of the simulation sickness sections with the normal sections, - d/a ratio is believed to have lower value during vasodilation and higher value during vasoconstriction, however, we could not find much difference in the parameter between normal and simulation sickness sections. We also compared 1 to 10Hz power spectral density ratios in normal sections with in simulation sickness section, and found that 6 density ratios among them have different value. Therefore, the density ratios might be utilized as parameters to detect simulation sickness of subjects.

• Journal of the Korean Society for Precision Engineering
• /
• v.20 no.9
• /
• pp.173-179
• /
• 2003

In optical storage device system, there are several research topics to increase its recording density. The main idea is reducing wave length of laser diode and magnifying the number of numerical aperture (NA). In conventional optical system NA cannot be over the unity in the air because of its diffraction limit. But it is possible to overcome its limitation of unity in near field using Solid Immersion Lens. In this work, the mathematical Solid Immersion Lens (SIL) design process was illustrated by using near field theory. Also, numerical SIL design parameters were calculated by means of CODE V. Through the work, we propose the new type of SIL for high density optical recording systems.

• Proceedings of the KIEE Conference
• /
• 1997.07a
• /
• pp.260-263
• /
• 1997

In this paper, we describe the mechanical strain effects on the critical current density of HTS (BSCCO) pancake-type-magnet. Firstly the strain of pancake coil is calculated in terms of coil length, which is also a function of angle, and then the critical current density degradation due to strain is calculated along the coil. We assumed that the critical current density degradation pattern is same with that of $Nb_{3}Sn$. We also modelled the effects of magnetic field on the critical curent degradation, and the results are compared with those with null magnetic field.

• Structural Engineering and Mechanics
• /
• v.42 no.2
• /
• pp.191-210
• /
• 2012

The Force Density Method (FDM) is a well known and extremely versatile tool in form finding of cable nets. In its linear formulation such method makes it possible to find all the possible equilibrium configurations of a net of cables having a certain given connectivity and given boundary conditions on the nodes. Each singular configuration corresponds to an assumed force density distribution. Its improvement as Non-Linear Force Density Method (NLFDM) introduces the possibility of imposing assigned relative distances among the nodes, the tensile level in the elements and/or their initial undeformed length. In this paper an Extended Force Density Method (EFDM) is proposed, which makes it possible to set conditions in terms of given fixed nodal reactions or, in other words, to fix the positions of a certain number of nodes and, at the same time, to impose the intensity of the reaction force. Through such extension, the (EFDM) enables us to deal with form findings problems of cable nets subjected to given constraints and, in particular, with mixed structures, made of cables and struts. The efficiency and the robustness of method are assessed through comparisons with other form finding techniques in dealing with characteristic applications to the prestress design of cable systems. As a further extension, the EFDM is applied to structures having some parts not yet geometrically defined, as can happen in designing new creative forms.

• Ocean and Polar Research
• /
• v.34 no.1
• /
• pp.85-91
• /
• 2012

Physical properties such as sound speed contrast (h) and density contrast (g) of the interested target are key parameters to understand acoustic characteristics by using theoretical scattering models. The density and sound speed of moon jellyfish (common jellyfish, Aurelia aurita s.l.) were measured. Sound speed contrast (h) was measured from travel time difference (time-of-flight method) of an acoustic signal in a water tank for APOP studies (Acoustic Properties Of zooplankton). Density contrast (g) was measured by the displacement volume and wet weight (dual-density method). The sound speed remained almost constant as the moon jellyfish increased in bell length. The mean values${\pm}$standard deviation of h and g were $1.0005{\pm}0.0012$ and $0.9808{\pm}0.0195$), respectively. These results will provide important input for use in theoretical scattering models for estimating the acoustic target strength of jellyfish.