• Particle and aerosol research
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• 제13권3호
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• pp.105-110
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• 2017

Real-time measurements of fine particles from stack emission gases are necessary due to the needs of continuous environmental monitoring of PM10 and PM2.5. The porous tube dilutor using hot and cold dilutions was developed to measure fine particles without condensable particles from highly humid emission gases and compared to the commercialized ejector-type dilutor. Particle size distributions were measured at the emission gases from a diesel engine and a coal-fired boiler. The porous tube dilutor could successfully measure the accumulation mode particles including relatively large particles more than $3{\mu}m$ without nuclei particles, while the ejector dilutor detected some condensable particles and could not detect large particles. The porous tube dilutor could successfully remove the already condensed water droplet particles generated by a humidifier in a $30m^3$ chamber.

• Economic and Environmental Geology
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• 제42권6호
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• pp.541-548
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• 2009

The Dongrae thermal water area located at the southeastern marginal part of the Korean Peninsula is one of the oldest hot springs in Korea. The Dongrae thermal water shows Na-Cl type of water chemistry, whereas the shallow cold groundwater is Ca(-Na)-$HCO_3$ type. In this paper, we discuss the age of the Dongrae hot spring, i.e. groundwater cycle among meteoric water-surface water-shallow groundwater-hot spring water. The $^{87}Sr/^{86}Sr$ ratios of the thermal water in Dongrae area range from 0.705663 to 0.705688 and are lower than those of groundwater, surface water and rain water as well as aquifer bearing granite. These Sr isotopic signatures in the Dongrae thermal water indicate that the circulation rate between thermal water and current meteoric water including groundwater, surface water and rain water in the Dongrae area should be very slow. The $^{14}C$ age of the Dongrae hot spring water range from $1,271{\pm}36$ BP(before present) to $2,467{\pm}36$ BP whereas that of the shallow groundwater is $-495{\pm}33$ BP. This suggests that the period of groundwater cycle among meteoric water, surface water, shallow groundwater and hot spring should be more than 1,270 years. Then, it also indicates that the present Dongrae hot spring may be a mixed water between the old thermal water heated for at least 1,270 years and the present shallow cold groundwater.

• Korean Journal of Fisheries and Aquatic Sciences
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• 제24권2호
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• pp.137-143
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• 1991

This study was carried out with sardine to develope a new type of fish protein concentrate. Chopped sardine meat was thermally treated in two different ways, autoclaved at $121^{\circ}C$ for 1 min and boiled at $95^{\circ}C$ for 5 min. The heat treated meat was pressed, controlled to PH 7.8 with $3\%$ (w/v) of $NaHCO_3$ and hot-air dried(at $40^{\circ}C$). The dried meat was powdered (50mesh), air and vacuum packed in laminated film bag(PET/AL. foil/CCP) and stored at room temperature for 60 days. The results of product quality analysis are as follows : 1. Proximate contents of moisture, crude lipid and protein of the autoclaved and boiled product were in the range of $10.0{\~}10.2\%,\;9.0{\~}9.1\%$ and $73.8{\~}74.4\%$, respectively. Yields of the both products were $40\%$ and $32.5\%$. 2. Values of emulsion activity, emulsion stability and foam expansion of the autoclaved product were $48.7\%$, $44.1\%\;and\;44.0\%$, respectively. These values were higher than those of boiled product. 3. Water holding capacity and digestibility of the both products were in the range of $5.0{\~}5.3\%$ and $78.0{\~}78.2\%$, respectively.

• Journal of agriculture & life science
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• 제46권6호
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• pp.59-65
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• 2012

This study evaluated the baby-leaf growth, leaf red color intensity, and phytochemical compounds, such as total phenols and total flavonoids using domestic Amaranthus accessions, to select promising germplasm for the use of baby-leaf vegetable. The 39 accessions, upper 15% of 262 Amaranthus germplasm collection showing high red color intensity in baby-leaf, measured as Hunter's a value, were primarily selected. The eleven accessions including IT199970, showing stable red color intensity in baby-leaf both in high-temperature and low temperature cultivation, were finally selected as promising germplasm for the use of baby-leaf vegetable Amaranthus. The leaf red color intensities when they were cultivated at low temperature period were generally higher than those at low temperature period, and all the eleven selected germplasm, including four Amaranthus sub-species and five unknown species, showed stable red color expression in baby-leaf. The total phenol and total flavonoid contents were also presented for finally selected germplasm including their baby-leaf fresh weights. These finally selected germplasm could be potentially used as baby-leaf vegetable resources, through fortifying the color balance of salad vegetable.

• Journal of Aerospace System Engineering
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• 제17권6호
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• pp.1-8
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• 2023

Research, such as developing alternative energy in the transportation field, including aviation, is being actively conducted to solve the issue of current climate change. Interest in ammonia fuel as a carbon free energy (CFE) source is increasing due to the ease of liquefaction and transportation and similarity in energy density to that of methanol. However, explosiveness and toxicity of ammonia make it difficult to handle. Therefore, in this study, stable ammonia production was attempted using relatively easy-to-handle urea water solution (UWS). High temperature steam was used to promote the hydrolysis of ammonia. In order to determine the causes for ammonia production below the theoretical equivalent ratio, it was suggested that there were not enough collisions to promote the hydrolysis based on the kinetic theory of gases. The hydrolysis of unreacted isocyanic acid (HNCO) was tested according to the change in water supply. As a result, an increased amount of ammonia produced was confirmed. The increased amount of ammonia produced in a certain section was dependent on the steam temperature and the flow rate of water supplied.

• Korean journal of food and cookery science
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• 제26권6호
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• pp.872-886
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• 2010

Six kinds of sunsik containing different contents of brown rice(BR; 20, 30, and 50%) were prepared and subjected to various processing conditions(with or without roasting at $200^{\circ}C$ for 20 min e.g., designated as RBR50 or BR50) to assess their functionality as ready-to-eat foods. They were also assessed for their nutritional and sensory properties and oxidative stability. Dietary fiber contents were proportionate to the levels of added BR. Protein was highest in RBR50 (p<0.001), which also had the highest amounts of free and structural amino acids. The amount of free amino acids tended to increase with roasting, although most amino acids were present in structural form. Oleic acid and linoleic acid were the predominant fatty acids in all prepared sunsik, and RBR50 presented noticeably higher peroxidability index due to its higher amount of linoleic acid(p<0.05). Nevertheless, RBR50 showed good oxidative stability; this phenomenon was observed in all sunsik with roasted BR but not in those with non-roasted BR. It is implied that potential antioxidants might have been newly formed or converted from their precursors while BR was roasted. Roasting process also had an impact on the sensory properties of sunsik, e.g., sunsik with added roasted BR showed lower dissolution and darker color intensity compared to its counterpart sunsik.

• Journal of Korean Tunnelling and Underground Space Association
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• 제25권4호
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• pp.261-283
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• 2023

This study aimed to review the performance stability of PET (Polyethylene terephthalate) fiber reinforcing materials among the synthetic fiber types for which the application of performance reinforcing materials to fiber-reinforced concrete is being reviewed by examining short-term and long-term performance changes. To this end, the residual performance was analyzed after exposing the PET fiber to an acid/alkali environment, and the flexural strength and equivalent flexural strength of the PET fiber-reinforced concrete mixture by age were analyzed, and the surface of the PET fiber collected from the concrete specimen was examined using a scanning microscope (SEM). The changes in were analyzed. As a result of the acid/alkali environment exposure test of PET fiber, the strength retention rate was 83.4~96.4% in acidic environment and 42.4~97.9% in alkaline environment. It was confirmed that the strength retention rate of the fiber itself significantly decreased when exposed to high-temperature strong alkali conditions, and the strength retention rate increased in the finished yarn coated with epoxy. In the test results of the flexural strength and equivalent flexural strength of the PET fiber-reinforced concrete mixture, no reduction in flexural strength was found, and the equivalent flexural strength result also did not show any degradation in performance as a fiber reinforcement. Even in the SEM analysis results, no surface damage or cross-sectional change of the PET reinforcing fibers was observed. These results mean that no damage or cross-section reduction of PET reinforcing fibers occurs in cement concrete environments even when fiber-reinforced concrete is exposed to high temperatures in the early stage or depending on age, and the strength of PET fibers decreases in cement concrete environments. The impact is judged to be of no concern. As the flexural strength and equivalent flexural strength according to age were also stably expressed, it could be seen that performance degradation due to hydrolysis, which is a concern due to the use of PET fiber reinforcing materials, did not occur, and it was confirmed that stable residual strength retention characteristics were exhibited.

• Journal of the Microelectronics and Packaging Society
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• 제24권4호
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• pp.39-46
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• 2017

This paper presents the fabrication of ceramic insulation layer on metallic heat spreading substrate, i.e. an insulated metal substrate, for planar type heater. Aluminum alloy substrate is preferred as a heat spreading panel due to its high thermal conductivity, machinability and the light weight for the planar type heater which is used at the thermal treatment process of semiconductor device and display component manufacturing. An insulating layer made of ceramic dielectric film that is stable at high temperature has to be coated on the metallic substrate to form a heating element circuit. Two technical issues are raised at the forming of ceramic insulation layer on the metallic substrate; one is delamination and crack between metal and ceramic interface due to their large differences in thermal expansion coefficient, and the other is electrical breakdown due to intrinsic weakness in dielectric or structural defects. In this work, to overcome those problem, selected metal oxide buffer layers were introduced between metal and ceramic layer for mechanical matching, enhancing the adhesion strength, and multi-coating method was applied to improve the film quality and the dielectric breakdown property.

• Proceedings of the Korean Vacuum Society Conference
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.264-264
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• 2016

최근에 charge trap flash (CTF) 기술은 절연막에 전하를 트랩과 디트랩 시킬 때 인접한 셀 간의 간섭현상을 최소화하여 오동작을 줄일 수 있으며 낸드 플래시 메모리 소자에 적용되고 있다. 낸드 플래시 메모리는 고집적화, 대용량화와 비휘발성 등의 장점으로 인해 핸드폰, USB, MP3와 컴퓨터 등에 이용되고 있다. 기존의 실리콘 기반의 플래시 메모리 소자는 좁은 밴드갭으로 인해 투명하지 않고 고온에서의 공정이 요구되는 문제점이 있다. 따라서, 이러한 문제점을 개선하기 위해 실리콘의 대체 물질로 산화물 반도체 기반의 플래시 메모리 소자들이 연구되고 있다. 산화물 반도체 기반의 플래시 메모리 소자는 넓은 밴드갭으로 인한 투명성을 가지고 있으며 저온에서 공정이 가능하여 투명하고 유연한 기판에 적용이 가능하다. 다양한 산화물 반도체 중에서 비정질 In-Ga-Zn-O (a-IGZO)는 비정질임에도 불구하고 우수한 전기적인 특성과 화학적 안정성을 갖기 때문에 많은 관심을 받고 있다. 플래시 메모리의 고집적화가 요구되면서 절연막에 high-k 물질을 atomic layer deposition (ALD) 방법으로 적용하고 있다. ALD 방법을 이용하면 우수한 계면 흡착력과 균일도를 가지는 박막을 정확한 두께로 형성할 수 있는 장점이 있다. 또한, high-k 물질을 절연막에 적용하면 높은 유전율로 인해 equivalent oxide thickness (EOT)를 줄일 수 있다. 특히, HfOx와 AlOx가 각각 trap layer와 blocking layer로 적용되면 program/erase 동작 속도를 증가시킬 수 있으며 넓은 밴드갭으로 인해 전하손실을 크게 줄일 수 있다. 따라서 본 연구에서는 ALD 방법으로 AlOx와 HfOx를 게이트 절연막으로 적용한 a-IGZO 기반의 thin-film transistor (TFT) 플래시 메모리 소자를 제작하여 메모리 특성을 평가하였다. 제작 방법으로는, p-Si 기판 위에 열성장을 통한 100 nm 두께의 SiO2를 형성한 뒤, 채널 형성을 위해 RF sputter를 이용하여 70 nm 두께의 a-IGZO를 증착하였다. 이후에 소스와 드레인 전극에는 150 nm 두께의 In-Sn-O (ITO)를 RF sputter를 이용하여 증착하였고, ALD 방법을 이용하여 tunnel layer에 AlOx 5 nm, trap layer에 HfOx 20 nm, blocking layer에 AlOx 30 nm를 증착하였다. 최종적으로, 상부 게이트 전극을 형성하기 위해 electron beam evaporator를 이용하여 platinum (Pt) 150 nm를 증착하였고, 계면 결함을 최소화하기 위해 퍼니스에서 질소 가스 분위기, $400^{\circ}C$, 30 분의 조건으로 열처리를 했다. 측정 결과, 103 번의 program/erase를 반복한 endurance와 104 초 동안의 retention 측정으로부터 큰 열화 없이 메모리 특성이 유지되는 것을 확인하였다. 결과적으로, high-k 물질과 산화물 반도체는 고성능과 고집적화가 요구되는 향후 플래시 메모리의 핵심적인 물질이 될 것으로 기대된다.

• Economic and Environmental Geology
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• 제53권2호
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• pp.213-220
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• 2020

When CO₂ foam is injected into the saline aquifer, the relative permeability of CO₂ decreases and its viscosity increases, thereby reducing mobility in porous media and ultimately improving CO₂ storge with enhanced sweep efficiency. In general, surfactants were used to fabricate CO₂ foam. Recently, nanoparticles have been used to form stable foam than surfactant. This paper introduces CO₂ storage technology using nanoparticle stabilized CO₂ foam. If the surface of the hydrophilic nanoparticles is partially modified into a CO₂-philic portion, the particles have an affinity for CO₂ and water, thus forming a stable CO₂ foam even in deep saline aquifers under high temperature and high salinity conditions, thereby it can be stored in the pores of the rock. In terms of economics, injection method using nanopaticle-stabilized CO₂ foam is more expensive than the conventional CO₂ injection, but it is estimated that it will have price competitiveness because the injection efficiency is improved. From an environmental point of view, it is possible to inject chemical substances such as surfactants and nanomaterials into aquifers or reservoirs for specific purposes such as pollutant removal and oil production. However, some studies have shown that nanoparticles and surfactants are toxic to aquatic animals, so environmentally proven substances should be used. Therefore, further research and development will be needed to study the production and injection of nanoparticle-stabilized CO₂ foam that are environmentally safe and economically reasonable.