• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.07b
• /
• pp.1002-1005
• /
• 2002

We have synthesized novel stilbenequinone derivatives(ASQ, PSQ) and investigated the properties of their electron drift mobility. Characteristics of the ionization potential Ip and electron affinity Ea of the ASQ were investigated by determining both oxidation and reduction potentials. There were estimated Ip = 7.1 eV and Ea = 3.6 eV. The electron drift mobility of ASQ mixture(R:t-Bu 10wt%) was $1.5{\times}10^{-5}cm^2/V{\cdot}sec$ at $6.15{\times}10^{5}V/cm$ and $1.3{\mu}m$ thickness.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.18 no.7
• /
• pp.667-674
• /
• 2005

In this paper the gate overlap length of the LDMOST is optimized for obtaining longer device lifetime. The LDMOSI device with drift region is fabricated using the $0.25\;{\mu}m$ CMOS Process. The gate overlap lengths on drift region are $0.1\;{\mu}m,\;0.4\;{\mu}m\;0.8\;{\mu}m\;and\;1.1\;{\mu}m$, respectively. The breakdown voltages, on-resistances and hot-carrier degradations of the fabricated LDMOST devices are characterized. The LDMOST device with gate overlap length of $0.4\;{\mu}m$ showed the longest on-resistance lifetime, 0.02 years and breakdown voltage of 22 V and on-resistance of $23\;m\Omega{\cdot}mm^2$.

• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.17 no.1
• /
• pp.46-51
• /
• 2009

This paper presents results from field studies carried out to monitor off-target droplet movement of endosulfan insecticide applied to the Korea chestnut tree area. As a results, mean airborne drift values were recorded 25m as average from downwind of a single flight line(sample line) in mountain terrain and mean effective swath width was recorded 19.5m as average in a plain. In terms of characteristics of geography of Korea aerial application is mainly carried out in mountain terrain. The equipment, weather conditions, and appropriate aerial spray technic are required for effective aerial application. In particular, the pilot can get effective results when he only sprays with consideration of environment factors since there is much turbulence in mountain terrain. Eventually, the most effective factor of droplets drift is to estimate the local weather conditions exactly.

• Applied Microscopy
• /
• v.38 no.4
• /
• pp.383-386
• /
• 2008

In performing in situ heating transmission electron microscopy (TEM) for materials characterizations, arising concerns such as specimen drifts and unintentional Cu contamination are discussed. In particular, we analysed the thermal and mechanical characteristics of in situ heating holders to estimate thermal drift phenomena. From the experimental results, we suggest an empirical model to describe the thermal drift behavior so that we can design an effective plan for in situ heating experiment. Practical approaches to minimize several hindrances arisen from the experiment are proposed. We believe that our experimental recommendations will be useful for a microscopist fascinated with the powerful potential of in situ heating TEM.

• Structural Engineering and Mechanics
• /
• v.28 no.3
• /
• pp.317-334
• /
• 2008

Seismic performance of coupling beams not designed for ductility is examined. Eight 1:4 scale coupling beam specimens, with seven reinforced concrete sections and one composite section, were tested under cycles of push-pull action. Characteristics of the specimens include moderate shear span ratio in the range of 2.5-3.5, high main reinforcement ratio at 3-4% and small to large stirrup spacing with 90- degree hooks. All the reinforced concrete specimens failed in a brittle manner. Displacement ductility of specimens with large stirrup spacing (${\geq}$140 mm) is in the range of 3 to 5. Seismic performance of the specimens is also examined using the ultimate drift angle and the amount of energy dissipated. Correlating the test data, an empirical relationship is proposed to estimate the ultimate drift angle of a class of coupling beams considered in the study not designed for ductility.

• Earthquakes and Structures
• /
• v.10 no.3
• /
• pp.589-611
• /
• 2016

This paper presents an analytical study aimed at evaluating the seismic performance of steel moment resisting frames (MRFs) retrofitted with different approaches. For this, 3, 6 and 12 storey MRFs having four equal bays of 5 m were selected as the case study models. The models were designed with lateral stiffness insufficient to satisfy code drift and hinge limitations in zones with high seismic hazard. Three different retrofit strategies including traditional diagonal bracing system and energy dissipation devices such as buckling restrained braces and viscoelastic dampers were used for seismic upgrading of the existing structures. In the nonlinear time history analysis, a set of ground motions representative of the design earthquake with 10% exceedance probability in fifty years was taken into consideration. Considering the local and global deformations, the results in terms of inter-storey drift index, global damage index, plastic hinge formations, base shear demand and roof drift time history were compared. It was observed that both buckling-restrained braces and viscoelastic dampers allowed for an efficient reduction in the demands of the upgraded frames as compared to traditional braces.

• Ocean Science Journal
• /
• v.42 no.1
• /
• pp.19-30
• /
• 2007

This study analyzed the current meter records along with wind records for over 500 days obtained in the Kangjin Bay, South Sea, Korea spanning from March, 2003 to Nov. 2005. Various analyses include descriptive statistics, harmonic analysis of tidal constituents, spectra and coherence, the principal axis, progressive vector diagrams. These analyses can illustrate the response of residual current to the local wind resulting in the net drift with rotational motion. Current speed ranges from -28 to 33 (cm/sec), with standard deviations from 6.5 to 12.9 (cm/sec). The harmonic analyses of the tidal current show the average form number, 0.12 with semi-diurnal type and the rectilinear orientation of the major axis toward northeast. The magnitudes of the semi-major range from 12.7 to 17.7 (cm/sec) for M2 harmonics, while for S2 harmonics, they range from 6.3 to 10.4 (cm/sec), respectively. In the spectral and coherency analysis of residual current and wind, a periodicity of 13.6 (day) is found to be most important in both records and plays an important role in the net drift of residual current. The progressive vector diagrams of residual current and wind show two types of behaviors such as unidirectional drift and rotational motion. It was also found that 3 % rule holds approximately to drive 1 (cm/sec) drift current by 30 (cm/sec) wind speed based on the correlation of the semi-major axis of wind and residual current.

• Journal of Biosystems Engineering
• /
• v.26 no.3
• /
• pp.221-228
• /
• 2001

Chemical application, one of the most important crop management processes happened to cause spray drift, that would threaten farmers in field as well as dwellers in rural region. Spray drift was affected by micro-meteorological parameters. A study to evaluate short distance drift characteristics of a boom sprayer in paddy fields has been undergoing. This study is the first step of the research. Main purpose of the was conducted to develop a mean wind profile and to get information on turbulence intensities above and within rice canopy. Wind in rice paddy field were measured at every 10cm from 10 to 180cm above the ground using a 2-dimensional probe and a hot wire anemometer system. Main results were summarized as follows. 1. Mean wind profile was modeled as; Equations. see full-text 2. Roughness length and zero-displacement in rice canopy were analyzed to be respectively 0.04 and 0.7∼0.72 times of the canopy height. The values are smaller comparing to those of other crops because rice canopy is flexible and uniform comparing to other crops. 3. Turbulence intensities (Tl) was greater as close to the ground and became constant at heights greater than 1.5Hc. where Tl’s were 0.4 and 0.15 in horizontal and vertical direction respectively.

• Journal of Positioning, Navigation, and Timing
• /
• v.9 no.2
• /
• pp.117-124
• /
• 2020

In this paper, the symmetric position drift of the integration approach in pedestrian dead reckoning (PDR) system with dual foot-mounted IMU is analyzed. The PDR system that uses the inertial sensor attached to the shoe is called the IA-based PDR system. Since this system is designed based on the inertial navigation system (INS), it has the same characteristics as the error of the INS, then zero-velocity update (ZUPT) is used to correct this error. However, an error that cannot be compensated perfectly by ZUPT exists, and the trend of the position error is the symmetric direction along the side of the shoe(left, right foot) with the IMU attached. The symmetric position error along the side of the shoe gradually increases with walking. In this paper, we analyze the causes of symmetric position drift and show the results. It suggests the possibility of factors other than the error factors that are generally considered in the PDR system based on the integration approach.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.33 no.2
• /
• pp.123-129
• /
• 2020

We analyzed the drift current by charged particles according to the loading methods applied into a closed cell by electronic ink at a reflective-type display panel using an electrophoretic mechanism. For this experiment, various panels were fabricated with injection voltages for electronic ink taking values in the range -4~0 V. The size of each cell was 220 ㎛ × 220 ㎛ and height of the barrier rib was 54.28 ㎛. The electronic ink was fabricated by mixing electrically neutral fluid and single-charge white particles. Drift current was measured by moving charged particles. A biasing voltage of 6 V was applied to the display panel. As a result, the drift current was proportional to the injection voltage for electronic ink, but it decreased in case of an injection voltage above -3 V. Our experimentation ascertained that the concentration of charged particles injected into closed cells is controlled by the injection voltage and the selective injection of charged particles above movable q/m is possible.