• Current Optics and Photonics
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• v.7 no.2
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• pp.200-206
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• 2023

Near-infrared (NIR) sensing technology using CMOS image sensors is used in many applications, including automobiles, biological inspection, surveillance, and mobile devices. An intuitive way to improve NIR sensitivity is to thicken the light absorption layer (silicon). However, thickened silicon lacks NIR sensitivity and has other disadvantages, such as diminished optical performance (e.g. crosstalk) and difficulty in processing. In this paper, a pixel structure for NIR sensing using a stacked CMOS image sensor is introduced. There are two photodetection layers, a conventional layer and a bottom photodiode, in the stacked CMOS image sensor. The bottom photodiode is used as the NIR absorption layer. Therefore, the suggested pixel structure does not change the thickness of the conventional photodiode. To verify the suggested pixel structure, sensitivity was simulated using an optical simulator. As a result, the sensitivity was improved by a maximum of 130% and 160% at wavelengths of 850 nm and 940 nm, respectively, with a pixel size of 1.2 ㎛. Therefore, the proposed pixel structure is useful for NIR sensing without thickening the silicon.

• Journal of the Korean GEO-environmental Society
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• v.20 no.5
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• pp.23-29
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• 2019

In general, pipe laying works are performed by constructing underground facilities such as pipes and then refilling the rest of the area with sand or soil. However, there are many problems in the compaction process such as difficulties in tampering around the underground facility and low compaction efficiency. Such problems cause deformation and damage to the underground pipes during refilling work and ultimately cause road sinks. Construction methods using CLSM are one of the typical methods to solve these issues, and recently, studies on CLSM using coal ash, which has similar engineering properties as sand, have been actively performed to protect environment and recycle resources. While many studies have been conducted to recycle fly ash in many ways, the demand for recycling bottom ash is increasing as most of the bottom ash is not recycled and reclaimed at ash disposal sites. Therefore, in order to find bottom ash applications using eco-friendly soil binders that are environmentally beneficial and conform with CLSM standards, this study investigated flow characteristics and strength change characteristics of eco-friendly soil binders, weathered granite soil, a typical site-generated soil, bottom ash, and fly ash mixed soil and evaluated the soil pollution to present CLSM application methods using bottom ash.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.1
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• pp.39-46
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• 2005

We fabricate and analyze fully depleted optical thyristors (DOTs) using quarter wavelength reflector stacks (QWRS). QWRS are employed as bottom mirrors to enhance the emission efficiency as well as the optical sensitivity. In order to analyze their switching characteristics, S-shape nonlinear current-voltage curves are simulated and the reverse full-depletion voltages (Vneg's) of DOTs are obtained as function of semiconductor parameters by using a finite difference method (FDM). The fabricated DOTs show sufficient nonlinear s-shape I-V characteristics and switching voltage changes of these devices with and without bottom mirrors show 1.82 V and 1.52 V, respectively. Compared to a conventional DOT, this device with the bottom mirrors shows about 20％ and 46% enhancement in switching voltage change and spontaneous emission efficiency, respectively.

• Asian-Australasian Journal of Animal Sciences
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• v.24 no.9
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• pp.1303-1313
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• 2011

This study was conducted to provide the basic information to allow improved scientific assessment of velvet antler's quality by investigating the change of chemical composition during different antler growth stages in elk (Cervus elaphus canadensis). Twenty four antlers were harvested from elk stags (aged 4-5 years) on 65 days (VA65), 80 days (VA80) and 95 days (VA95) after button casting, and the chemical composition of each antler was determined in five sections (top, upper, middle, base, and bottom). Crude protein and ether extract content was the highest in the top section, whereas ash content was the highest in the bottom section in all groups (p<0.05). Glycosaminoglycan (GAG) content was higher in the VA65 group than in the VA95 group in the upper section of antler (p<0.05). The collagen content was higher in the VA65 group compared to the VA95 group in the middle and bottom sections (p<0.05), and increased downward from the top to the bottom section. The proportions of certain amino acids, including aspartic acid, glutamic acid and isoleucine were higher (p<0.05), whereas proline and glycine were lower in the top section of antler compared to all other sections (p<0.05). The proportion of linoleic acid, 11,14,17-eicosatrienoic acid, total ${\omega}$-3 and ${\omega}$-6 fatty acids and polyunsaturated fatty acids (PUFAs) for all sections in the VA65 group was higher than in the VA95 group (p<0.05). These results suggested that the quality of velvet antler is strongly influenced by antler development stage.

• Journal of Korean Society of Water and Wastewater
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• v.31 no.6
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• pp.599-609
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• 2017

Desalination plants have been recently constructed in many parts of the world due to water scarcity caused by population growth, industrialization and climate change. Most seawater desalination plants are designed with a submarine pipeline for intake and discharge. Submarine pipelines are installed directly on the bottom of the water body if the bottom is sandy and flat. Intake is located on a low-energy shoreline with minimal exposure to beach erosion, heavy storms, typhoons, tsunamis, or strong underwater currents. Typically, HDPE (High Density Polyethylene) pipes are used in such a configuration. Submarine pipelines cause many problems when they are not properly designed; HDPE pipelines can be floated or exposed to strong currents and wind or tidal action. This study examines the optimal design method for the trench depth of pipeline, analysis of on-bottom stability and dilution of the concentrate based on the desalination plant conducted at the Pacific coast of Peru, Chilca. As a result of this study, the submarine pipeline should be trenched at least below 1.8 m. The same direction of pipeline with the main wind is a key factor to achieve economic stability. The concentrate should be discharged as much as high position to yield high dilution rate.

• 한국전산유체공학회:학술대회논문집
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• 1996.05a
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• pp.52-57
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• 1996

Mixing is most important for developing an electric washer which transforms angular momentum from rotating solid wall to laundry clothes inside it. For magnification of this mixing effect, some inventions are introduced to washing machine system, i. e., washing plate, washing rod, and even for washing cap in a model of a Korean manufacture. However, the previous efforts show dissatisfaction up till now. In this paper, a triumph to enhance mixing effects to increase washing performance is presented and verified by numerical investigation. The present model to simulate a washing tub is the simple circular cylinder with two endwall disks which is completely filled with a viscous liquid. The present improvement is to change mounting position of a bottom disk of the model cylinder. Therefore, the aim of this work just proposes a new idea, which is numerically inspected, to a producer of washing machine, In detail, this invention is alternating the mounting position of a rotating bottom disk. Actually skewed pulsator is placed in steady of a flat disk, so the two endwall disks at top and bottom are not in parallel. The angle between an inclined bottom disk and the horizontal plane is fixed as 5 degree and physical domain to consider poses a sliced cylinder. Flow fields in both a right circular cylinder and the present improved model are fully depicted by numerical integration on a body fitted nonorthogonal regular uniform grid system. Numerical data to explain flow structure are plotted for understanding of the effects of the inclined disk. Also enhanced mixing effects by the inclined rotating disk are gauged by accurate numerical data used in this work.

• Geotechnical Engineering
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• v.11 no.4
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• pp.125-140
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• 1995

Generally, the groundwater pressure is not considered in the design of concrete lining of bottom drainage tunnel. This design method implies that the phreatic surface is drawdown to the bottom of tullnel. When tile groundwater is continually supplied without changing of groundwater table, there is a possibility at which the groundwater pressure acting on the tunnel lining after the completion of tunnel. Therefore, the safety of tunnel lining must be checked in this case. In this paper, the stability of bottom drainage tunnel which is affected by groundwater discharge is analzed by using of the Finite Element Method at the 2 sections of subway where the groundwater level has a tittle change during the construction. As the result of analysis, the grouting for the water tightness and the permanent monitoring system of tunnel are required for maintaining of long-term stability of bottom drainage tunnel for the case of groundwater plassure acting on the tunnel lining is greater than that of design stage.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.4
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• pp.281-285
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• 2020

Oxide semiconductor devices have become increasingly important because of their high mobility and good uniformity. The channel length of oxide semiconductor thin film transistors (TFTs) also shrinks as the display resolution increases. It is well known that reducing the channel length of a TFT is detrimental to the current saturation because of drain-induced barrier lowering, as well as the movement of the pinch-off point. In an organic light-emitting diode (OLED), the lack of current saturation in the driving TFT creates a major problem in the control of OLED current. To obtain improved current saturation in short channels, we fabricated indium gallium zinc oxide (IGZO) TFTs with single gate and double gate structures, and evaluated the electrical characteristics of both devices. For the double gate structure, we connected the bottom gate electrode to the source electrode, so that the electric potential of the bottom gate was fixed to that of the source. We denote the double gate structure with the bottom gate fixed at the source potential as the BGFP (bottom gate with fixed potential) structure. For the BGFP TFT, the current saturation, as determined by the output characteristics, is better than that of the conventional single gate TFT. This is because the change in the source side potential barrier by the drain field has been suppressed.

• Journal of the Korean Geosynthetics Society
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• v.12 no.4
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• pp.87-98
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• 2013

This study was performed a series of the isotropic compression-expansion tests and the drained triaxial tests with various the relative densities 40%, 60%, 80% and 95% for bottom ash. Using the tests results the characteristic of the parameters of Lade's single hardening constitutive model were investigated. The soil parameters Kur and n representing elastic behavior are not much affected by the change of the relative density. The other parameters such as failure criterion(m, ${\eta}_1$), hardening function(c, p) and plastic potential(${\psi}_2$, ${\mu}$) are in a positive linear relationship with the relative density. Since the soil parameters h and ${\alpha}$ representing yield function do not change much to the change of relative density and also closely related to failure criterion, they can be replaced by failure criterion ${\eta}_1$. We also observed that predicted values from the Lade's single hardening constitutive model were well consistent with the observed data.

• Journal of the Korean Institute of Gas
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• v.18 no.6
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• pp.40-44
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• 2014

In this study, it is analyzed that a change in the shape of small propane containers made of STS304 when increasing of internal pressure. When internal pressure of a small propane container increased, bottom of end plate is convexly changed. This test is applied to a water bath pressure test to analyze the characteristics of the container. Water bath is able to analyze relationship between internal pressure and volume. In result, shape change section is confirmed because bottom of end plate is convexly changed. In addition, this section tend to decrease internal pressure because a volume increment increase out of proportion to pressure. The results of this study are expected to contribute to improving the safety of the pressure vessel, as well as various small propane container.