• Journal of Environmental Science International
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• v.21 no.3
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• pp.305-312
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• 2012

This work is to study the variations of adsorption characteristics of binary vapor according to packing system of double-layer bed by fixed bed experiment. Breakthrough curves of single and binary vapor composed of acetone and benzene on single-layer and double-layer adsorption bed composed of activated carbon (AC) and silica-aluminar (SA) were compared. Adsorptions of binary vapor on double-layer bed were influenced by the differences of surface area between adsorbents as well as the polarity difference between adsorbent and adsorbate. The roll-up phenomenon of acetone vapor was happened by replacement with competing adsorption between acetone vapor and benzene vapor on AC bed, but it was not happened on SA bed because acetone vapor and benzene vapor had less difference in affinity with SA bed. The breakthrough times of acetone vapor and benzene vapor on AC/SA double-layer bed were three times and 1.4 times larger respectively than on SA/AC double-layer bed, the differences of breakthrough times were relatively larger than the equilibrium adsorption capacities according to packing system of double-layer bed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.40-41
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• 2006

In this work, we developed the 0-3 type piezoelectric composite to incorporate the advantages of both ceramic and polymer. The PVDF-PZT composites were fabricated with various mixing ratio by 3-roll mi11 mixer. The composite solutions were coated on ITO bottom-electrode deposited on PET (polyethylene terephthalate) polymer film by the conventional screen-printing method. After depositing the top-electrode of silver-paste, 4kV/mm of DC field was applied at $120^{\circ}C$ for 30min to poling the 0-3 composite film. The value of $d_{33}$ was increased as the PZT weight percent was increases. But the $g_{33}$ value showed the maximum at 65 wt% of PZT powder.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2011.11a
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• pp.63-63
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• 2011

통상적으로 코팅가공시 수지의 흐름성을 개선하기 위해서 코팅수지(점도 : 50,000~60,000 Cps)의 점도를 10,000 Cps 이하로 낮추어서 작업을 진행한다. 이때 MEK(Methyl Ethyl Ketone), TOL(Toluene), DMF(Dimethyl Formamide) 등과 같은 유기용제를 사용하여 점도를 조절한다. 본 연구는 기존에 표면처리 코팅용 수지 배합시 유기용제를 사용하는 대신 물을 사용하여 점도 조절이 가능한 표면처리 코팅용 hydrophilic PU 수지를 연구하였다. Prepolymer 법으로 합성한 수지가 One-shot법으로 합성한 수지보다 water dilution 안정성이 우수하며, 친수성 polyol과 소수성 polyol의 비율이 6/4정도가 될 때 water dilution된 수지의 안전성, 투습도 등의 물성이 가장 이상적으로 발현 되는 것을 확인 할수 있었고, 50part의 물과 희석 후 5일 이후에도 상분리가 되지 않음을 확인 할 수 있었다. 개발된 수지의 적용성을 평가한 결과, J-knife를 이용하여 knife over roll 방식으로 $200{\mu}m$의 gap으로 80/120/$140^{\circ}C{\times}10m/min.$의 다단건조 공정으로 진행했을 때 최적의 물성을 얻을 수 있었다.

• Journal of Institute of Convergence Technology
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• v.2 no.1
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• pp.1-6
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• 2012

The cold chain system in South-East Asia is requiring to maintain freshness of refrigerated or frozen food. In this study, Thermal storage system using Phase change material (PCM) was developed and evaluated its performance about temperature and cold keeping time. For various application of cold chain system, we developed portable cold box, cold roll container and freezing station. Keeping time on laboratory tests of portable cold box in case of refrigeration and freezing were 6 hours and 4 hours, respectively. Cold container was developed to 2.5 ton scale. Evaluation in Indonesia, it was showed to keep the setting temperature of $-10^{\circ}C$ over 40 hours at $30^{\circ}C$ of ambient air. Freezing station using PCM was kept over 24 hours under $-20^{\circ}C$.

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.496-499
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• 1995

Amorphous $Co_{80+x}TM_{12}B_{8-x}$ (TM = Ti, Zr, Hf, Nb and x = 0, 2, 4 at%) alloys were prepared by single roll melt spinning technique. Saturation magnetization of the amorphous ribbons was measured by SQUID and vibrating sample magnetometer from 5 to 800 K under applied fields up to 10 kOe. Typical thermo-magnetization curves were observed and the average values of the spectroscopic splitting g factor were estimated from the ferromagnetic resonance curve. For all the amorphous alloys studied here the saturation magnetization in the temperature range 5 K up to about $0.3T_{c}$ can be described by the Bloch relation: $M_{s}(T)\;=\;M_{s}(0)(1-BT^{3/2}-CT^{5/2})$. From the values of $M_{s}(0)$, B and spectroscopic splitting g factor the spin wave stiffness constants were calculated.

• Journal of the Semiconductor & Display Technology
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• v.20 no.3
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• pp.51-56
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• 2021

Using an inkjet printing process, we have investigated a droplet formation of poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) near the orifice of a piezoelectric inkjet head. With an attempt to form the smallest droplet without any satellites, we have applied various waveforms such as the unipolar, bipolar, and M-shaped waveforms. It is found that the droplet velocity and volume vary depending sensitively on the waveform width and voltage. Of those, the M-shaped waveform is shown to provide the smallest droplet volume, followed by the bipolar and then unipolar waveforms. The droplet printed on a PET film roll by the M-shaped waveform has the diameter as small as 46.1 ㎛. It is likely that the second short unipolar in the M-shape waveform increases the droplet velocity gradient, rendering the droplet smaller.

• Journal of the Semiconductor & Display Technology
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• v.21 no.4
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• pp.132-137
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• 2022

In this paper, we have studied the quadrature error reduction for the single drive 3-axis MEMS Gyroscope. There was a limitation of the previous study which is the z-axis quadrature error was large. To reduce this value, design methodologies were presented. And the methodologies included a different mesh application, z-rate spring structure change, and mass compensation for balancing of the structure. We conducted the modal analysis, drive mode analysis and sense mode analysis using COMSOL Multiphysics. As a result, a drive resonant frequency was 26003 Hz, with the x-sense, y-sense, z-sense being 26749 Hz, 26858 Hz, 26920 Hz, respectively. And the Mechanical sensitivity was computed at 2000 degrees per second(dps) input angular rate while the sensitivity for roll, pitch, and yaw was computed 0.011, 0.012, and 0.011 nm/dps respectively. And z-axis quadrature error was successfully improved, 2.78 nm to 0.95 nm, which the improvement rate was about 66 %.

• Wind and Structures
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• v.37 no.3
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• pp.191-209
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• 2023

This work investigates the subcritical free-shear prism wake at Re=22,000 by the Koopman analysis using the Dynamic Mode Decomposition (DMD) algorithm. The Koopman model linearized nonlinearities in the stochastic, homogeneous anisotropic turbulent wake, generating temporally orthogonal eigen tuples that carry meaningful, coherent structures. Phenomenological analysis of dominant modes revealed their physical interpretations: Mode 1 renders the mean-field dynamics, Modes 2 describes the roll-up of the Strouhal vortex, Mode 3 describes the Bloor-Gerrard vortex resulting from the Kelvin-Helmholtz instability inside shear layers, its superposition onto the Strouhal vortex, and the concurrent flow entrainment, Modes 6 and 10 describe the low-frequency shedding of turbulent separation bubbles (TSBs) and turbulence production, respectively, which contribute to the beating phenomenon in the lift time history and the flapping motion of shear layers, Modes 4, 5, 7, 8, and 9 are the relatively trivial harmonic excitations. This work demonstrates the Koopman analysis' ability to provide insights into free-shear flows. Its success in subcritical turbulence also serves as an excellent reference for applications in other nonlinear, stochastic systems.

• Journal of the Korean Society of Food Culture
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• v.23 no.5
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• pp.639-645
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• 2008

The objective of this study was to assess the quality characteristics of morning-rolls containing various levels (0, 4, 8, and 12%) of bamboo leaf powder. The results demonstrated that morning-roll volume decreased with increasing amounts of bamboo leaf powder, and as the bamboo leaf powder content increased, the Hunter's color 'L', 'a' and 'b' values were significantly reduced (p<0.05). For the amylogram characteristics, the addition of bamboo leaf powder to the flour reduced peak viscosity, holding strength, final viscosity, and setback. The results of the sensory evaluation demonstrated that control (0%) and 8% addition of bamboo leaf powder had the best scores in taste, color, flavor, texture, appearance, softness, wetness, residual mouth feel, and overall acceptability. Thus, it appears that by using 8% additions of bamboo leaf powder, the functionality, nutritional composition, taste, color, and flavor of morning-rolls containing bamboo leaf powder can be developed. This result will support the development of better quality bamboo-leaf morning-rolls.

• International journal of advanced smart convergence
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• v.13 no.3
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• pp.66-79
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• 2024

The model developed in this study holds significant importance in predicting carbon emissions in maritime transport. By utilizing ship data and EEDI (Energy Efficiency Design Index) guidelines, the model presents a highly accurate prediction tool, providing a solid foundation for maximizing operational efficiency and effectively managing carbon emissions in ship operations. The model's accuracy was demonstrated by an R² score of 0.95 and a Mean Absolute Percentage Error (MAPE) of 1.4%. Through SHAP (SHapley Additive exPlanations) and Partial Dependence Plots (PDP), it was identified that Speed Over Ground and relative wind speed are the most significant variables, both showing a positive correlation with increased CO2 emissions. Additionally, environmental factors such as exceeding an average draft of 22(m), a Leeway over 5°, and a current angle exceeding 200° were found to increase emissions significantly. Specific ranges of wind and swell wave angles also notably affected emissions. Conversely, lower pitch, roll, and rudder angle were associated with reduced emissions, indicating that stable ship operation enhances efficiency.