• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.5
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• pp.173-178
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• 2016

When a ballast track of a high-speed train is constructed on a bridge, the displacement of the bridge decks can occur because they are not fixed to the rails. Moreover, relative displacements occur between the bridge and rails caused by temperature changes and external loads. The current longitudinal resistance criteria (UIC Code 774-3, KR C-08080) on ballast tracks with continuous welded rails (CWRs) do not take into account the longitudinal movement of the bridge and the frictional force between the ballast and slabs. In addition, the magnitude of the longitudinal resistance, k, is calculated somewhat conservatively and, (therefore?) it acts as an unfavorable element in the design of long span and continuous railway bridges. Thus, in order to replicate the actual behavior more effectively, the longitudinal resistance of CWRs should take into account the additional rigidity between the slab and track. In this study, the longitudinal resistances of the ballasted track on the bridge were analyzed by carrying out an experimental study with a test setup designed to simulate the deck and bed track. In the test results, the maximum longitudinal resistances of the tests were similar to the resistances of the current codes, however, the measured longitudinal stiffness designed to limit the displacement of the tests were much smaller in comparison with the longitudinal stiffness on the codes.

• Journal of Korea Water Resources Association
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• v.39 no.4 s.165
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• pp.313-320
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• 2006

In this study, hydraulic characteristics of thalweg line occurred near the single groyne and recirculation zone around downstream of the structure were discussed from the experiments which conducted in fixed flat-bed channel flume. The thalweg line is the stream line where the maximum velocity occurs and flow separation appeared at the tip of groyne changes the thalweg alignment. In this study, the variations in flow fields which were caused by different length and permeability of groyne were measured by LSPIV(Large Scale Particle Image Velocimetry), and also the characteristics of thalweg line and separation area were analyzed. From these results, it is found that length to thalweg line from the channel wall $T_{CL}$ and height of separation area $S_h$ vary the channel width up to 75%, 50% in the change of length and permeability of groyne, however the Froude number does not affect on $T_{CL}$ and $S_h$. Velocity along the thalweg $U_{CL}$ Increased by twice the mean velocity, and the maximum velocity occurred in downstream where the distance $5{\sim}6$ times of groyne length away from the groyne, which does not get affected by length and permeability of groyne and Froude number.

• Clean Technology
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• v.27 no.4
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• pp.325-331
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• 2021

In this study, bio-carbons were produced by activation process from unused biomass (Grade 3 wood pellet and spent coffee grounds) to determine the removal performance of formaldehyde and acetaldehyde. The activation experiments were conducted in a fixed bed reactor using CO₂ as an activation agent. The temperature of the activation reactor and input of CO₂ were 900 ℃ and 1 L min^-1 for all the experiments. The maximum BET surface area of about 788 m² g^-1 was obtained for bio-carbon produced from Grade 1 wood pellet, whereas about 544 m² g^-1 was achieved with bio-carbon produced from spent coffee grounds. In all the experiments, the bio-carbons produced were mainly found to have micro-porous nature. A lower ash amount in raw material was favored for the high surface area of bio-carbons. In the removal test of formaldehyde and acetaldehyde, the bio-carbon produced from spent coffee grounds showed excellent adsorption performance compared with woody biomass (Grade 1 wood pellet and Grade 3 wood pellet). In addition, the comparative experiment of commercial impregnated activated carbon and bio-carbon produced from spent coffee grounds was conducted. In terms of formaldehyde removal performance, the commercial impregnated bio-carbon was excellent, while bio-carbon produced from spent coffee grounds was excellent in acetaldehyde removal.

• Applied Chemistry for Engineering
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• v.32 no.4
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• pp.478-482
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• 2021

The catalytic yields of partial oxidation of methane (POM) to hydrogen over Ln(1)-Ni(5)/SBA-15 (Ln = Dy, Eu, Pr, and Tb) were investigated in a fixed bed flow reactor under atmosphere. As 1 wt% of Eu was added to Ni(5)/SBA-15 catalyst, the O1s and Si2p core electron levels of Eu(1)-Ni(5)/SBA-15 showed the chemical shift by XPS. XPS analysis also demonstrated that the atomic ratio of O1s, Ni2p_3/2, and Si2p increased to 1.284, 1.298, and 1.058, respectively, and exhibited O^-, and O^2- oxygen and metal ions such as Eu³⁺, Ni⁰, Ni²⁺, and Si⁴⁺ on the catalyst surface. The yield of hydrogen on the Eu(1)-Ni(5)/SBA-15 was 57.2%, which was better than that of Ln(1)-Ni(5)/SBA-15 (Ln = Dy, Pr, and Tb), the catalytic activity was kept steady even 25 h. As 1 wt% of Eu was added to Ni(5)/SBA-15, the oxygen vacancies caused by strong metal-support interaction (SMSI) effect due to the strong interaction between metals and carrier are made. They are resulted in increasing the dispersion of Ni⁰, and Ni²⁺ nano particles on the surface of catalyst, and are kept catalytic activity.

• Journal of the Korea Convergence Society
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• v.12 no.7
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• pp.273-282
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• 2021

Nursing home plays a role in providing elderly care in the context of China's rapid population aging, but little understanding of the efficiency of the nursing homes. In this paper, we investigated the efficiency in nursing homes using Data Envelopment Analysis (DEA) and Malmquist index (MPI) for the modeling of the number of nursing home beds, fixed assets, and medical personnel as input variables, and the number of elderly people of self-care, the number of elderly people of partial self-care, the number of bed-ridden elderly people and the income of nursing homes as output variables. Stratification analysis showed that the top two provinces in the DEA-CCR yield were Beijing and Shanghai in the five-year survey period. Four provinces (Beijing, Jiangsu, Shandong, and Shanghai) scored 1.00 in terms of DEA-BCC yield. The MPI analysis showed that Hainan ranked the highest five-year average in the included provinces. In terms of resource utilization, internal management, operation scale, and other aspects, the nursing homes in the provinces with high-efficiency evaluation results show high efficiency and technological progress, whereas the areas with low-efficiency evaluation showed a feature of the improving technical efficiency.

• Clean Technology
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• v.15 no.4
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• pp.258-264
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• 2009

Thermodynamic measurements were performed to show the possibility of recovering $CO_2$ from fuel gas (the mixture of $CO_2$ and $H_2$) by forming gas hydrates with water where water was dispersed in the pores of silica gel particles having nominal 100 nm of pore diameter. The hydrate-phase equilibria for the ternary $CO_2+H_2$+water in pores were measured and $CO_2$ concentrations in vapor and hydrate phase were determined under the hydrate-vapor two phase region at constant 274.15 K. It was shown that the inhibition effect appeared due to silica gel pores, and the corresponding equilibrium dissociation pressures became higher than those of bulk water hydrates at a specific temperature. In addition, direct measurement of $CO_2$ content in the hydrate phase showed that the retrieved gas from the dissociation of hydrate contained more than 95 mol% of $CO_2$ when 42 mol% of $CO_2$ and balanced Hz mixture was applied. Compared with data obtained in case of bulk water hydrates, which showed just 83 mol% of $CO_2$ where 2-stage hydrate slurry reactor was intended to utilize this property, the hydrate formation in porous silica gel has enhanced the feasibility of $CO_2$ separation process. Hydrate formation as not for slurry but solid particle makes it possible to used fixed bed reactor, and can be a merit of well-understood technologies in the industrial field.

• Applied Chemistry for Engineering
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• v.34 no.6
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• pp.674-678
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• 2023

The effect of Pt was investigated to the catalytic methane decomposition of CH₄ to H₂ over Pt(1)-Fe(30)/MCM-41 and Fe(30)/MCM-41 using a fixed bed flow reactor under atmosphere. The Fe₂O₃ and Pt crystal phase behavior of fresh Pt(1)-Fe(30)/MCM-41 were obtained via XRD analysis. SEM, EDS analysis, and mapping were performed to show the uniformed distribution of nano particles such as Fe, Pt, Si, O on the catalyst surface. XPS results showed O^2-, O^- species and metal ions such as Pt⁰, Pt²⁺, Pt⁴⁺, Ft⁰, Fe²⁺, Fe³⁺ etc. When 1 wt% of Pt was added to Fe(30)/MCM-41, automic percentage of Fe2p increased from 13.39% to 16.14%, and Pt4f was 1.51%. The yield of hydrogen over Pt(1)-Fe(30)/MCM-41 was 3.2 times higher than Fe(30)/MCM-41. The spillover effect of H₂ from Pt to Fe increased the reduction of Fe particles and moderate interaction of Fe, Pt and MCM-41 increased the uniform dispersion of fine nanoparticles on the catalyst surface, and improved hydrogen yield.

• Journal of Korean Society of Rural Planning
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• v.30 no.1
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• pp.57-66
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• 2024

This study aimed to develop a precise vegetation cover classification model for small streams using the combination of drone remote sensing and support vector machine (SVM) techniques. The chosen study area was the Idong stream, nestled within Geosan-gun, Chunbuk, South Korea. The initial stage involved image acquisition through a fixed-wing drone named ebee. This drone carried two sensors: the S.O.D.A visible camera for capturing detailed visuals and the Sequoia+ multispectral sensor for gathering rich spectral data. The survey meticulously captured the stream's features on August 18, 2023. Leveraging the multispectral images, a range of vegetation indices were calculated. These included the widely used normalized difference vegetation index (NDVI), the soil-adjusted vegetation index (SAVI) that factors in soil background, and the normalized difference water index (NDWI) for identifying water bodies. The third stage saw the development of an SVM model based on the calculated vegetation indices. The RBF kernel was chosen as the SVM algorithm, and optimal values for the cost (C) and gamma hyperparameters were determined. The results are as follows: (a) High-Resolution Imaging: The drone-based image acquisition delivered results, providing high-resolution images (1 cm/pixel) of the Idong stream. These detailed visuals effectively captured the stream's morphology, including its width, variations in the streambed, and the intricate vegetation cover patterns adorning the stream banks and bed. (b) Vegetation Insights through Indices: The calculated vegetation indices revealed distinct spatial patterns in vegetation cover and moisture content. NDVI emerged as the strongest indicator of vegetation cover, while SAVI and NDWI provided insights into moisture variations. (c) Accurate Classification with SVM: The SVM model, fueled by the combination of NDVI, SAVI, and NDWI, achieved an outstanding accuracy of 0.903, which was calculated based on the confusion matrix. This performance translated to precise classification of vegetation, soil, and water within the stream area. The study's findings demonstrate the effectiveness of drone remote sensing and SVM techniques in developing accurate vegetation cover classification models for small streams. These models hold immense potential for various applications, including stream monitoring, informed management practices, and effective stream restoration efforts. By incorporating images and additional details about the specific drone and sensors technology, we can gain a deeper understanding of small streams and develop effective strategies for stream protection and management.

• Journal of the Korean Society of Radiology
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• v.7 no.2
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• pp.113-120
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• 2013

Nowadays, the medical system towards patients changes into the medical services. As the human rights are improved and the capitalism is enlarged, the rights and needs of patients are gradually increasing. Also, based on this change, several systems in hospitals are revised according to the convenience and needs of patients. Thus, the cases of mobile portable among examinations are getting augmented. Because the number of mobile portable examinations in patient's room, intensive care unit, operating room and recovery room increases, neighboring patients are unnecessarily exposed to radiation so that the examination is legally regulated. Hospitals have to specify that "In case that the examination is taken out of the operating room, emergency room or intensive care units, the portable medical X-ray protective blocks should be set" in accordance with the standards of radiation protective facility in diagnostic radiological system. Some keep this regulation well, but mostly they do not keep. In this study, we shielded around the Collimator where the radiation is detected and then checked the change of dose regarding that of angles in portable tube and collimator before and after shielding. Moreover, we tried to figure out the effects of shielding on dose according to the distance change between patients' beds. As a result, the neighboring areas around the collimator are affected by the shielding. After shielding, the radiation is blocked 20% more than doing nothing. When doing the portable examination, the exposure doses are increased $0^{\circ}C$, $90^{\circ}C$ and $45^{\circ}C$ in order. At the time when the angle is set, the change of doses around the collimator decline after shielding. In addition, the exposure doses related to the distance of beds are less at 1m than 0.5m. In consideration of the shielding effects, putting the beds as far as possible is the best way to block the radiation, which is close to 100%. Next thing is shielding the collimator and its effect is about 20%, and it is more or less 10% by controlling the angles. When taking the portable examination, it is better to keep the patients and guardians far enough away to reduce the exposure doses. However, in case that the bed is fixed and the patient cannot move, it is suggested to shield around the collimator. Furthermore, $90^{\circ}C$ of collimator and tube is recommended. If it is not possible, the examination should be taken at $0^{\circ}C$ and $45^{\circ}C$ is better to be disallowed. The radiation-related workers should be aware of above results, and apply them to themselves in practice. Also, it is recommended to carry out researches and try hard to figure out the ways of reducing the exposure doses and shielding the radiation effectively.

• Applied Chemistry for Engineering
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• v.21 no.6
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• pp.648-652
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• 2010

Catalytic activities of the partial oxidation of methane (POM) to hydrogen were investigated over Pd(5)/Ti-SPK and Pd(5)/Zr-SPK in a fixed bed flow reactor (FBFR) under atmosphere, and the catalysts were characterized by BET, XPS, XRD. The BET surface areas, pore volume and pore width of Horvath-Kawaze, micro pore area and volume of t-plot of Pd(5)/Ti-SPK and Pd(5)/Zr-SPK were $284m^2/g$, $0.233cm^3/g$, 3.9 nm, $30m^2/g$, $0.015cm^3/g$ and $396m^2/g$, $0.324cm^3/g$, 3.7nm, $119m^2/g$, $0.055cm^3/g$, repectively. The nitrogen adsorption isotherms were type IV with hysteresis. XPS showed that Si 2p and O 1s core electronlevels of Ti-SPK and Zr-SPK substituted Ti and Zr shifted to slightly lower binding energies than SPK. The oxidation states of Pd on the surface of catalysts were $Pd^0$ and $Pd^{+2}$. XRD patterns showed that crystal structures of fresh catalyst changed amorphous into crystal phase after reaction. The conversion and selectivity of POM to hydrogen over Pd(5)/Ti-SPK and Pd(5)/Zr-SPK were 77, 84% and 78, 72%, respectively, at 973 K, $CH_4/O_2$ = 2, GHSV = $8.4{\times}10^4mL/g_{cat}{\cdot}h$ and were kept constant even after 3 days in stream. These results confirm superior activity, thermal stability, and physicochemical properties of catalyst in POM to hydrogen.