• Journal of Korean Tunnelling and Underground Space Association
• /
• v.4 no.1
• /
• pp.71-78
• /
• 2002

In this study, the influence of the presence of discontinuity planes on the load transfer mechanism and the pattern of loosening zone was studied based on the laboratory test. The trap-door and the reaction plates are installed as the bottom plane of the model box. The vertical discontinuity plane is installed in the dry sand. Various overburden heights and locations of discontinuity planes are applied as major factors in this study. The results show that at higher overburden heights over about 1.5 times the excavation width, the ratio of the transferred stress to the insitu stress converges to a certain value even if the overburden height increases further. The results also show that the discontinuity plane gives relatively larger influence on the load transfer mechanism, that produces the unsymmetrical load concentration, when the discontinuity plane locates within the tunnel width. When the discontinuity plane locates outside the tunnel width, the unsymmetrical load concentration is reduced considerably.

• Korean journal of applied entomology
• /
• v.43 no.2
• /
• pp.129-134
• /
• 2004

A simple and easy method was developed to monitor fungus gnats, Bradysia agrestis on sweet pepper in greenhouses. The larvae of B. agrestis were more attracted to potato discs than other sweetpotato, carrot, garlic, radish, and onion discs. The average numbers of B. agrestis found in each disc were 9.7 (potato), 6.0 (sweetpotato), 4.3 (carrot), 0.7 (garlic), 3.8 (radish), and 1.0 (onion). The number of larvae also increased by the size of disc surface and resulted in 2.1 larvae in 10${\times}$10${\times}$10 mm, 3.4 larvae in 20${\times}$20${\times}$10mm, and 3.9 larvae in 30${\times}$30${\times}$10 mm. The adults were more attracted to a yellow sticky trap (50.0 numbers) than a blue (18.0 numbers) or a white (3.7 numbers) traps. The optimal height for installing sticky trap in the greenhouse was determined as less than 50 cm from the rockwool bed based on the adults caught in the traps; 50.0 in less than 50 cm, 4.3 in 50-100 cm, and 2.0 in more than 100 cm height.

• Nuclear Engineering and Technology
• /
• v.4 no.3
• /
• pp.214-222
• /
• 1972

In the optic,11 grade LiF crystal, the electron traps corresponding to the thermoluminescence(abbreviated to TL) glow peak develop as irradiation dose is increased. Originally the electron trap of the crystal has two levels but as the dose reaches to the order of 10$^4$rontgen, it attains five levels as observed in the TL glow curves. The five trap depths are determined from the glow peak temperatures for two different heating rates, $\theta$=6.6$^{\circ}C$/sec and 3.4$^{\circ}C$/sec. The electron trap depths have the following values E$_1$=0.79 eV, E$_2$=0.93 eV, E$_3$=1.02 eV, E$_4$=1.35 eV, E$_{5}$=1.69eV. The special feature of thermoluminescence of optical grade LiF is that the traps, except E$_1$and E$_2$corresponding to 12$0^{\circ}C$ glow peak and 15$0^{\circ}C$ glow peak for $\theta$=6.6$^{\circ}C$/sec, have severe thermal instability, namely E$_3$, E$_4$and E$_{5}$ levels disappear during bleaching process. These defects in the optical grade LiF crystal seem annealed out during the course of TL measurement. The fresh or long time unused LiF(Mg) crystal shows only two glow peaks at 17$0^{\circ}C$ and 23$0^{\circ}C$ for $\theta$=6.6$^{\circ}C$/sec, but upon sensitization with r-ray irradiation, it converts to the six glow peak state. The four electron traps, E$_1$, E$_2$, E$_3$, and E$_{6}$ created by r-ray irradiation and corresponding to the glow peaks at T=10$0^{\circ}C$ 13$0^{\circ}C$, 15$0^{\circ}C$ and 29$0^{\circ}C$ are stable and not easily annealed out thermally, The sensitization essentially required to LiF(Mg) dosimeter is to give the crystal the stable six levels in the electron trap. In optical grade LiF, the plot between logarithm of total TL output versus logarithm of r-ray dose gives more supra-linear feature than that of LiF(Mg). However, if one takes the height of 12$0^{\circ}C$ glow peak(S=6.6$^{\circ}C$/sec), instead of the total TL output, the curve becomes close to that of LiF(Mg).

• Journal of Korean Society for Atmospheric Environment
• /
• v.29 no.6
• /
• pp.780-788
• /
• 2013

This study attempted to determine important meteorological parameters related to airborne pollen concentrations in urban areas. Hourly pollen measurement data were prepared from a regular sampling with a volumetric Burkard spore trap at a site in the Ulsan city, during the spring season (March~May) of 2011. Results showed that the daily mean and maximum concentrations for total pollen counts during the spring season were statistically significantly correlated with both air temperature and wind speed; daily mean pollen concentration was the most highly related to daily maximum temperature (r=0.567, p<0.001). It was also identified that pollen concentration has a stronger relationship with wind speed at the rural site than at the urban one, which confirms that strong wind conditions over the pollen sources area can be favorable for pollen dispersal, resulting in increases in airborne pollen concentrations downwind. From the results of an oak-pollen episode analysis, it was found that there was a significant relationship between hourly variation of oak pollen concentrations and dynamic meteorological factors, such as wind and mixing height (representing the boundary layer depth); especially, a strong southwestern wind and elevated mixing height was associated with high nocturnal concentrations of oak pollen. This study suggests that temperature, wind, and mixing height can be important considerations in explaining the pollen concentration variations. Additional examination of complex interactions of multiple meteorological parameters affecting pollen behavior should be carried out in order to better understand and predict the temporal and spatial pollen distribution in urban areas.

• Proceedings of the KIEE Conference
• /
• 1993.07b
• /
• pp.1265-1267
• /
• 1993

The switching and the retention characteristics with the injection conditions(pulse height and pulse width) were investigated in the nonvolatile MNOS memories with thin oxide layer of $23{\AA}$ thick. The shift of flatband voltage was measured using the fast ramp C-V method and experimental results were analized using the previously developed models. It was shown that the experimental results were described quit well by the trap-assisted and modified Fowler-Nordheim tunneling models for the voltage pulse of $15V{\sim}19V,\;24V{\sim}25V$, respectively. However, the direct tunneling model was agreement with experimental values in all range of pulse height. As increasing the initial shift of the flatband voltage, the decay rate was increased. But for the same initial shift of the flatband voltage, the decay rate was smaller for low and long pulse than for high and short one.

• Proceedings of the KIEE Conference
• /
• 1996.07c
• /
• pp.1428-1430
• /
• 1996

Thin Silicon oxynitride(SiON) films have been chemically deposited using 193nm ArF Excimer Laser CVD, with $Si_{2}H_{8}$, $N_{2}O$, and $NH_3$ as the reactive gases and $N_2$ as the carrier gas. Experimental results show that deposition rate and refractive index have a strong dependence on substrate temperature, chamber pressure, gas ratio, laser power and laser beam height. Electrical characterization of oxynitride films demonstrates that for $NH_{3}/N_{2}O$ flow ratios ranging from 0.25 to 1, the leakage currents, the interface trap density and the capacitances (dielect ric constant) increase and the dielectric breakdown fields decrease

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.51 no.7
• /
• pp.322-327
• /
• 2002

Temperature-dependent current-voltage characteristics of organic light-emitting diodes(OLEDs) were studied in a device structure of ITO/TPD/Alq$_3$/Al to understand conduction mechanism. The current-voltage characteristics were measured in the temperature range of 8K ~ 300K. We analyzed an electrical conduction mechanism of the OLEDS using space-charge-limited current(SCLC) and Fowler-Nordheim tunneling. In the temperature range above 150k, the conduction mechanism could be explained by space charge limited current from the inversely proportional temperature dependence of exponent m. The characteristic trap energy is found to be about 0.15ev. At low temperatures below 150k, the Fowler-Nordheim tunneling conduction mechanism is dominant. We have obtained a zero field barrier height to be about 0.6~0.8eV.

• Electrical & Electronic Materials
• /
• v.5 no.3
• /
• pp.310-319
• /
• 1992

LPCVD 방법으로 625.deg.C와 560.deg.에서 증착한 다결정 실리콘에 As이온주입량을 lx$10^{13}$-lx$10^{16}$/$cm^{2}$로 변화시키면서 열처리 전, 후의 미세구조와 전기적 특성 변화를 조사하였다. 625.deg.C에서 증착한 시편은 columnar구조를 하고 있어 표면이 매우 거칠었으며 900.deg.C, 30분 열처리 후에는 As doping 농도에 관계없이 결정립 크기는 200-300.angs.정도였다. 560.deg.C에서 증착한 시편은 비정질 상태로열처리 후에는 1000.angs.이상의 큰 결정립을 갖는 타원형의 결정립으로 성장하였으며 표면이 매우 smooth하였다. 같은 doping 농도에서 전기 전도도와 Hall mobility는 비정질 상태로 증착한 시편이 큰 결정립으로 인하여 다결정 상태로 증착한 시편에 비해 크게 되었다. Grain boundary trapping model에 의해 계산한 potential barrier height는 As doping 농도가 증가함에 따라 감소하였으며 grain boundary trap density는 증착 온도, As doping 농도 및 결정립 크기에 크게 관계없이 3.6~5*$10^{12}$/$cm^{2}$로 측정되었다.

• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.33A no.4
• /
• pp.106-111
• /
• 1996

Schottky diodes are fabricated on laser annealed and unannealed polysilicon substrate and their electrical characteristics are studied and analyzed. Current of laser annealed devices are larger than that of unannealed devices because of grain growth, decrease of grain boundary and trap density, lowering of grain boundary barrier height, decrease of dopant segregation. At low forward bias (<0.7V), currents of unanealed devices are larger. Soft breakdown voltages of laser annealed devices are larger than that of unannealed devices.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.41 no.2
• /
• pp.95-100
• /
• 2005

In order to improve the gill nets for croaker, Miichthys miiuy which is proper to the fishermen's income ans fisheries resource management, we had studied to the net height of present gill nets (mesh size 160mm, 50 mesh in depth), experimental gill nets-I(mesh size 150mm, 68 mesh in depth) and experimental gill nets-II(mesh size 142mm, 75 mesh in depth) in wter using the gill nets design ans analysis simulation system, and then investigated and analyzed the catch efficiency of each gill nets through the field fishing experiments. The net height of emperimental gill nets-I and experimental gill nets-II in water were estimated respectively about 1.5 times and 1.3 times higher than present gill nets which the net height is about 3.5m as the results of simulation considering the current of fishing fields. Total number of croakers which were caught by the persent gill nets was 62(body length 300~1,200mm), total catch weight was 398.7kg (mean 0.6kg/sheet). Total number of croakers which were caught by the experimental gill nets- I was 68(body length 600~1,100mm), total catch weight was 391.6kg (mean 1.2kg/sheet). Total number of croakers which were caught by the experimental gill nets-II was 28(body length 400~900mm), total catch weight was 99.2kg (mean 0.3kg/sheet).