• Journal of the Korean Society for Heat Treatment
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• v.28 no.6
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• pp.300-309
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• 2015

The aim of the present study was to predict the variations in microstructure and deformation occurring during gas carburizing and quenching processes of a SCM420H planetary gear in a real production environment using the finite element method (FEM). The motivation for the present study came from the fact that previous FEM simulations have a limitation of the application to the real heat treatment process because they were performed with material properties provided by commercial programs and heat transfer coefficients (HTC) measured from laboratory conditions. Therefore, for the present simulation, many experimentally measured material properties were employed; phase transformation kinetics, thermal expansion coefficients, heat capacity, heat conductivity and HTC. Particularly, the HTCs were obtained by converting the cooling curves measured with a STS304 gear without phase transformations using an oil bath with an agitator in a real heat treatment factory. The FEM simulation was successfully conducted using the aforementioned material properties and HTC, and then the predicted results were well verified with experimental data, such as the cooling rate, microstructure, hardness profile and distortion.

• Journal of the Korea Organic Resources Recycling Association
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• v.31 no.2
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• pp.53-61
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• 2023

Most of the sewage sludge is organic waste containing a large amount of organic substances decomposable by microorganisms by biological treatment. As for existing sewage sludge treatment methods, reduction and fuel conversion are being carried out using technologies such as drying, incineration, torrefaction, carbonization. However, the disadvantage of high energy consumption has been pointed out as latent heat of 539 kcal/kg is consumed based on drying. Therefore, in this study, we intend to produce solid fuel through hydrothermal carbonization(HTC), which is a thermochemical treatment. To evaluate the value of solid fuel, the characteristics of carbonization and fuel ratio were analyzed. As a result, as the hydrothermal carbonization reaction temperature increased, the lower heating value also increased by about 500 kcal/kg due to the increase in the degree of carbonization. H/C, O/C, ratio showed a decreasing trend from 1.78, 0.46 to 1.57, 0.32. When the ratio of ash to combustible content (fixed carbon + volatile) of dry sludge was 0.25 or more, it was derived that the degree of carbonization and calorific value did not increase even when hydrothermal carbonization was performed.

• Asian-Australasian Journal of Animal Sciences
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• v.27 no.10
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• pp.1513-1520
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• 2014

The present aim was to investigate the effects of traditional Chinese medicine prescriptions (TCM) on body temperature, blood physiological parameters, nutrient apparent digestibility and growth performance of beef cattle under heat stress conditions. Twenty-seven beef cattle were randomly divided into three groups as following; i) high temperature control (HTC), ii) traditional Chinese medicine prescriptions I+high temperature (TCM I) and iii) traditional Chinese medicine prescriptions II+high temperature (TCM II) (n = 9 per group). The results showed that the mean body temperature declined in TCM II treatment (p<0.05). Serum $T_3$ and $T_4$ levels with TCM I and TCM II treatments elevated (p<0.05), and serum cortisol levels of TCM I treatments decreased (p<0.05), compared with the HTC group. Total protein, albumin, globulin in TCM II treatments elevated and blood urea nitrogen levels of both TCM treatments increased, but glucose levels of both TCM treatments decreased, compared with the HTC group (p<0.05). The apparent digestibility of organic matter and crude protein with TCM I treatment increased, and the apparent digestibility of acid detergent fiber elevated in both TCM treatments (p<0.05). Average daily feed intake was not different among three groups, however average daily gain increased and the feed:gain ratio decreased with both TCM treatments, compared with the HTC group (p<0.05). The present results suggest that dietary supplementation with TCM I or TCM II improves growth performance of heat stressed beef cattle by relieving heat stress responses and increasing nutrient apparent digestibility.

• Clean Technology
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• v.29 no.4
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• pp.272-278
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• 2023

There is a lot of interest in methods for pollutants using adsorption, and recent research is being conducted to show that biochar can be used to remove organic and inorganic pollutants. In particular, wood waste as waste biomass requires a biomass recycling method, and a method to increase the adsorption capacity of biochar produced using wood waste is needed. Biochar is created by Hydrothermal carbonization (HTC) using, which uses low temperature and high pressure, has low energy consumption and does not require moisture removal pretreatment, and biochar is created through chemical activation using KOH, NaOH, and ZnCl₂ chemicals. The adsorption characteristics of biochar were determined by analyzing iodine adsorptivity, specific surface area, pore diameter, pore volume, pore distribution, and SEM according to the activation. The results of analyzing the selecting biochar by activating the biochar produced at HTC 300℃, 4 hr by KOH, NaOH, and ZnCl₂ chemicals, the specific surface area was 774~1.387 m²/g, showing a high specific surface area similar to activated carbon, and it was confirmed that micropores with an average pore diameter in the range of 21~24 Å were formed. As a result of SEM observation, the surface was uniform with a certain shape depending on activation. It was confirmed that one pore was developed and the number of pores increased.

• Proceedings of the Korean Nuclear Society Conference
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• 2004.10a
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• pp.425-426
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• 2004

• Proceedings of the Korea Information Processing Society Conference
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• 2017.04a
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• pp.171-173
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• 2017

최근 모바일 컴퓨팅은 어플리케이션 실행, 이미지 처리, 동영상 인코딩, 게임 등의 모바일 컴퓨팅 작업 처리를 위한 높은 성능의 컴퓨팅 능력을 요구한다. 모바일 컴퓨팅의 성능을 향상하기 위해 모바일 클라우드 컴퓨팅(Mobile Cloud Computing)을 도입하였다. 기존 모바일 클라우드 컴퓨팅에서는 모바일 컴퓨팅 작업의 처리를 위해 고-성능 컴퓨팅(High-Performance Computing)방법을 적용한 오프로드가 연구되고 있다. 고-성능 컴퓨팅의 목적은 단일작업의 처리속도 향상이므로 다중 작업처리를 위한 모바일 클라우드 컴퓨팅에는 적합하지 않다. 또한 고-성능 컴퓨팅은 모바일 클라우드 사용자에게 동등한 컴퓨팅 성능을 제공하지 못하는 문제점을 내재한다. 본 논문에서는 모바일 클라우드 컴퓨팅 기반 다중 작업 처리를 위한 Multitasking Mechanism for High-Throughput Computing(M2-HTC)을 제안한다. M2-HTC는 모바일 클라우드에서 처리중인 작업과 사용 가능한 컴퓨팅 리소스를 활용하여 다중 모바일 컴퓨팅 작업의 처리시간을 최소화하는 기법이다.

• Carbon letters
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• v.25
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• pp.103-112
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• 2018

Hierarchically porous, chemically activated carbon materials are readily derived from biomass using hydrothermal carbonization (HTC) and chemical activation processes. In this study, empty fruit bunches (EFB) were chosen as the carbon source due to their sustainability, high lignin-content, abundance, and low cost. The lignin content in the EFB was condensed and carbonized into a bulk non-porous solid via the HTC process, and then transformed into a hierarchical porous structure consisting of macro- and micropores by chemical activation. As confirmed by various characterization results, the optimum activation temperature for supercapacitor applications was determined to be $700^{\circ}C$. The enhanced capacitive performance is attributed to the textural property of the extremely high specific surface area of $2861.4m^2\;g^{-1}$. The prepared material exhibited hierarchical porosity and surface features with oxygen functionalities, such as carboxyl and hydroxyl groups, suitable for pseudocapacitance. Finally, the as-optimized nanoporous carbons exhibited remarkable capacitive performance, with a specific capacitance of $402.3F\;g^{-1}$ at $0.5A\;g^{-1}$, a good rate capability of 79.8% at current densities from $0.5A\;g^{-1}$ to $10A\;g^{-1}$, and excellent life cycle behavior of 10,000 cycles with 96.5% capacitance retention at $20A\;g^{-1}$.

• Journal of the Korea Computer Graphics Society
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• v.22 no.5
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• pp.49-56
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• 2016

Mobile Virtual Reality Head Mount Displays such as Google Cardboard and Samsung Gear VR are being released, as well as PC-based VR HMDs such as Oculus Rift and HTC Vive. However, when the user wears HMD, it hides the external view of the user. Therefore, it may happen that the user is struck by the surrounding objects such as furniture, and there is no definite solution to this problem. In this paper, we propose a method to reduce the risk of injuries by visualizing the location and information of obstacles scanned by using a RGB-D camera.

• Journal of the Microelectronics and Packaging Society
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• v.16 no.1
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• pp.27-31
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• 2009

In this paper, the polymer adhesive bonding technology using wafer-level technology was investigated and warpage results were analyzed. Si and glass wafer was bonded after adhesive polymer layer and dam pattern for uniform state was patterned on glass wafer. In this study, warpage result decreased as the low of bonding temperature of Si wafer, bonding pressure and height of adhesive bonding layer. The availability of adhesive polymer bonding was confirmed by TC, HTC, Humidity soak test after dicing. The result is that defect has not found without reference to warpage.

• Journal of Soil and Groundwater Environment
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• v.21 no.1
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• pp.22-27
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• 2016

Hydrothermal carbonization (HTC) is a carbonization method of thermochemical process at a relatively low temperature (180-250℃). It is reacted by water containing raw material. In this study, it was selected for effective disposal method of food waste because food waste in Korea has large amount water. 5 kg, 10 kg, 15 kg of food waste were reacted for 6 hours at 200℃ for selecting the optimum amount of raw material. Since the derived optimum amount, food waste was reacted for 2 hours, 4 hours and 6 hours at 200℃ and 1.5 MPa. After carbonization, it was analyzed to evaluated the properties by ultimate analysis, iodine adsorption, BET surface area and SEM. After analyzing the characteristics, it can be utilized as a basic data for applied.