• Title/Summary/Keyword: strength model

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Effect Analysis of Offshore Wind Farms on VHF band Communications (VHF 대역 통신에 대한 해상풍력 발전단지의 영향성 분석)

  • Oh, Seongwon;Park, Taeyong
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.28 no.2
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    • pp.307-313
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    • 2022
  • As the development of renewable energy expands internationally to cope with global warming and climate change, the share of wind power generation has been gradually increasing. Although wind farms can produce electric power for 24 h a day compared to solar power plants, Their interfere with the operation of nearby radars or communication equipment must be analyzed because large-scale wind power turbines are installed. This study analyzed whether a land radio station can receive sufficient signals when a ship sailing outside the offshore wind farm transmits distress signals on the VHF band. Based on the geographic information system digital map around the target area, wind turbine CAD model, and wind farm layout, the area of interest and wind farm were modeled to enable numerical analysis. Among the high frequency analysis techniques suitable for radio wave analysis in a wide area, a dedicated program applying physical optics (PO) and shooting and bouncing ray (SBR) techniques were used. Consequently, the land radio station could receive the electromagnetic field above the threshold of the VHF receiver when a ship outside the offshore wind farm transmitted a distress communication signal. When the line of sight between the ships and the land station are completely blocked, the strength of the received field decreases, but it is still above the threshold. Hence, although a wind farm is a huge complex, a land station can receive the electromagnetic field from the ship's VHF transmitter because the wave length of the VHF band is sufficiently long to have effects such as diffraction or reflection.

Systematic Review of the Effects of Blood Flow Exercise for Health-care Promotion: A Focus on Korean Domestic Research (헬스케어 증진을 위한 혈류조절 가압 운동의 효과에 대한 체계적 문헌고찰 ; 국내 연구 중심으로)

  • Seo, Tae-Hwa;Kim, Dong-Won
    • Journal of Korea Entertainment Industry Association
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    • v.14 no.8
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    • pp.447-454
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    • 2020
  • The purpose of this study was to determine the clinical effects of blood flow regulation exercise for improving patients' health care and its usefulness as a rehabilitation model for various diseases by analyzing and examining the existing literature. A literature review of Korean academic journals published over a 10-year period, from 2010 to 2019, was conducted using words such as "blood flow regulation," "blood flow restriction," "low-intensity exercise," and "Kaatsu." Kaatsu is a blood flow regulation exercise developed in 1966 by Dr. Yoshiaki Sato of Japan. It is an efficient and effective exercise method that uses blood flow regulation bands that increase the secretion of growth hormones to develop muscles within a short time, improves blood circulation and metabolism to prevent and improve adult diseases, shortens the rehabilitation period, and improves cardiovascular function. The study participants consisted of 10 patients, of whom four were elderly, four had obesity, one was a stroke patient, and one was a trauma patient. The results of this study show that the blood flow regulation exercise, which is a low-intensity exercise, has the same effect as high-intensity exercise, which supports the evidence that it is a highly efficient exercise method for muscle development and rehabilitation of the elderly, adolescents, and patients with injuries who have difficulty in general exercising. For future studies, further reviews are necessary to verify the effectiveness of the exercise method according to blood flow regulation site and type of disease.

Analysis of CO/CO2 Ratio Variability According to the Origin of Greenhouse Gas at Anmyeon-do (안면도 지역 온실기체 기원에 따른 CO/CO2 비율 변동성 분석 연구)

  • Kim, Jaemin;Lee, Haeyoung;Kim, Sumin;Chung, Chu-Yong;Kim, Yeon-Hee;Lee, Greem;Choi, Kyung Bae;Lee, Yun Gon
    • Atmosphere
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    • v.31 no.5
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    • pp.625-635
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    • 2021
  • South Korea established the 2050 Carbon Neutral Plan in response to the climate crisis, and to achieve this policy, it is very important to monitor domestic carbon emissions and atmospheric carbon concentration. Both CO2 and CO are emitted from fossil fuel combustion processes, but the relative ratios depend on the combustion efficiency and the strength of local emission regulations. In this study, the relationship between CO2 and CO was analyzed using ground observation data for the period of 2018~2020 at Anmyeon-do site and the CO/CO2 ratio according to regional origin during high CO2 cases was investigated based on the footprint simulated from Stochastic Time-Inverted Lagrangian Transport (STILT) model. CO2 and CO showed a positive correlation with correlation coefficient of 0.66 (p < 0.01), and averaged footprints during high CO2 cases confirmed that air particles mainly originated from eastern and north-eastern China, and inland of Korean Peninsula. In addition, it was revealed that among the cases of high CO2 concentration, when the CO/CO2 ratio is high, the industrial area of eastern China is greatly affected, and when the ratio is low, the contribution of the domestic region is relatively high. The ratio of CO2 and CO in this study is significant in that it can be used as a useful factor in determining the possibility of domestic and foreign origins of climate pollutants.

Damage Analysis of Manganese Crossings for Turnout System of Sleeper Floating Tracks on Urban Transit (도시철도 침목플로팅궤도 분기기 망간크로싱의 손상해석)

  • Choi, Jung-Youl;Yoon, Young-Sun;Ahn, Dae-Hee;Han, Jae-Min;Chung, Jee-Seung
    • The Journal of the Convergence on Culture Technology
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    • v.8 no.5
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    • pp.515-524
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    • 2022
  • The turnout system of the sleeper floating tracks (STEDEF) on urban transit is a Anti-vibration track composed of a wooden sleeper embedded in a concrete bed and a sleeper resilience pad under the sleeper. Therefore, deterioration and changes in spring stiffness of the sleeper resilience pad could be cause changes in sleeper support conditions. The damage amount of manganese crossings that occurred during the current service period of about 21 years was investigated to be about 17% of the total amount of crossings, and it was analyzed that the damage amount increased after 15 years of use (accumulated passing tonnage of about 550 million tons). In this study, parameter analysis (wheel position, sleeper support condition, and dynamic wheel load) was performed using a three-dimensional numerical model that simulated real manganese crossing and wheel profile, to analyze the damage type and cause of manganese crossing that occurred in the actual field. As a result of this study, when the voided sleeper occurred in the sleeper around the nose, the stress generated in the crossing nose exceeded the yield strength according to the dynamic wheel load considering the design track impact factor. In addition, the analysis results were evaluated to be in good agreement with the location of damage that occurred in the actual field. Therefore, in order to minimize the damage of the manganese crossing, it is necessary to keep the sleeper support condition around the nose part constant. In addition, by considering the uniformity of the boundary conditions under the sleepers, it was analyzed that it would be advantageous to to replace the sleeper resilience pad together when replacing the damaged manganese crossing.

A study on the measurement and processing of medical service experience data - From the perspective of realizing patient-centeredness - (의료서비스 경험데이터의 측정 및 가공에 관한 연구 -환자중심성 실현 관점에서-)

  • Jinho, Ahn;Jungmin, Choi
    • Journal of Service Research and Studies
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    • v.13 no.3
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    • pp.147-159
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    • 2023
  • This study is a study to develop a model for measurement and processing of experience data, which is emerging as a core value in quality management of medical services. In the theoretical background, a literature study was conducted on the importance of experience in medical service, measurement and processing of experience data, and realization of patient-centeredness. Based on these literature and theoretical background research results, operational definitions were performed for the following four research variables, and statistical tests were conducted. Hypothesis 1 is the effect of measuring experience data from the perspective of three factors on persona modeling, Hypothesis 2 is the effect of persona modeling on service blueprint visualization, Hypothesis 3 is the effect of service blueprint visualization on realization of patient-centeredness, and Hypothesis 4 is persona modeling This is the effect that modeling has on the realization of patient-centeredness. After data-based testing of factor analysis, reliability analysis, and correlation analysis, all four hypotheses were adopted as a result of verification using regression analysis. In conclusion, in an era where it is difficult to recognize the value of having only good medical staff and medical equipment in hospitals, it was possible to grasp the meaning that what kind of medical service experience is continuously obtained is more important to patients than the effectiveness of medical staff and medical equipment. In the era of the service economy, the core of hospital service competitiveness is providing attractive experiences, which is the real strength of hospitals, so the measurement and processing of experience data, which is the subject of this study, will have an important meaning in realizing patient-centeredness and realizing smart hospitals.

Study on collapse mechanism and treatment measures of portal slope of a high-speed railway tunnel

  • Guoping Hu;Yingzhi Xia;Lianggen Zhong;Xiaoxue Ruan;Hui Li
    • Geomechanics and Engineering
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    • v.32 no.1
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    • pp.111-123
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    • 2023
  • The slope of an open cut tunnel is located above the exit of the Leijia tunnel on the Changgan high-speed railway. During the excavation of the open cut tunnel foundation pit, the slope slipped twice, a large landslide of 92500 m3 formed. The landslide body and unstable slope body not only caused the foundation pit of the open cut tunnel to be buried and the anchor piles to be damaged but also directly threatened the operational safety of the later high-speed railway. Therefore, to study the stability change in the slope of the open cut tunnel under heavy rain and excavation conditions, a 3D numerical calculation model of the slope is carried out by Midas GTS software, the deformation mechanism is analyzed, anti-sliding measures are proposed, and the effectiveness of the anti-sliding measures is analyzed according to the field monitoring results. The results show that when rainfall occurs, rainwater collects in the open cut tunnel area, resulting in a transient saturation zone on the slope on the right side of the open cut tunnel, which reduces the shear strength of the slope soil; the excavation at the slope toe reduces the anti-sliding capacity of the slope toe. Under the combined action of excavation and rainfall, when the soil above the top of the anchor pile is excavated, two potential sliding surfaces are bounded by the top of the excavation area, and the shear outlet is located at the top of the anchor pile. After the excavation of the open cut tunnel, the potential sliding surface is mainly concentrated at the lower part of the downhill area, and the shear outlet moves down to the bottom of the open cut tunnel. Based on the deformation characteristics and the failure mechanism of the landslides, comprehensive control measures, including interim emergency mitigation measures and long-term mitigation measures, are proposed. The field monitoring results further verify the accuracy of the anti-sliding mechanism analysis and the effectiveness of anti-sliding measures.

Pullout Resistance of Pressurized Soil-Nailing by Cavity Expansion Theory (공팽창이론에 의한 압력식 쏘일네일링의 인발저항력 산정)

  • Seo, Hyung-Joon;Park, Sung-Won;Jeong, Kyeong-Han;Choi, Hang-Seok;Lee, In-Mo
    • Journal of the Korean Geotechnical Society
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    • v.25 no.7
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    • pp.35-46
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    • 2009
  • Pressure grouting is a common technique in geotechnical engineering to increase the stiffness and strength of the ground mass and to fill boreholes or void space in a tunnel lining and so on. Recently, the pressure grouting has been applied to a soil-nailing system which is widely used to improve slope stability. The soil-nailing design has been empirically performed in most geotechnical applications because the interaction between pressurized grouting paste and the adjacent ground mass is complicated and difficult to analyze. The purpose of this study is to analyze the increase of pullout resistance induced by pressurized grouting with the aid of performing laboratory model tests and field tests. In this paper, two main causes of pullout resistance increases induced by pressurized grouting were verified: the increase of mean normal stress and the increase of coefficient of pullout friction. From laboratory tests, it was found that dilatancy angle could be estimated by modified cavity expansion theory using the measured wall displacements. The radial displacement increases with dilatancy angle decrease and the dilatancy angle increases with injection pressure increase. The measured pullout resistance obtained from field tests is in good agreement with the estimated one from the modified cavity expansion theory.

A Study on the Determination of Bearing Capacity of Soft Silty Ground and Polluted Silty Ground with Wastewater and Factory Waste Oil (연약한 실트지반과 생활오폐수와 공장폐유로 오염된 실트지반의 지지력 결정에 관한 연구)

  • Ahn, Jong-Pil;Park, Sang-Bum
    • Journal of the Korean Geotechnical Society
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    • v.24 no.4
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    • pp.5-13
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    • 2008
  • Laboratory model test with soft silty ground (ML) and polluted silty ground with wastewater and factory waste oil ($ML_p$) was conducted and the applicability of changes of bearing capacity from the increase of pollutants was compared and analyzed with existing findings. As silty ground polluted with wastewater and factory waste oil had increased contents of pollutants, plasticization of ground was fostered compared to soft silt ground due to the influence of pollutants, and characteristics of ground strength decreased. Critical surcharge value of soft silty ground $q_{cr}=4.14c_u$, ultimate bearing capacity value $q_{ult}=9.53c_u$, critical surcharge value of silty ground polluted with wastewater and factory waste oil $q_{cr}=1.78c_u$ and ultimate bearing capacity value $q_{ult}=4.39c_u$. Critical surcharge and ultimate bearing capacity of silty ground polluted with wastewater and factory waste oil were less than those of soft silty ground. It meant that shearing resistance due to the increase of pollutants decreased and rather a smaller value was obtained.

Short-Term Precipitation Forecasting based on Deep Neural Network with Synthetic Weather Radar Data (기상레이더 강수 합성데이터를 활용한 심층신경망 기반 초단기 강수예측 기술 연구)

  • An, Sojung;Choi, Youn;Son, MyoungJae;Kim, Kwang-Ho;Jung, Sung-Hwa;Park, Young-Youn
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2021.05a
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    • pp.43-45
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    • 2021
  • The short-term quantitative precipitation prediction (QPF) system is important socially and economically to prevent damage from severe weather. Recently, many studies for short-term QPF model applying the Deep Neural Network (DNN) has been conducted. These studies require the sophisticated pre-processing because the mistreatment of various and vast meteorological data sets leads to lower performance of QPF. Especially, for more accurate prediction of the non-linear trends in precipitation, the dataset needs to be carefully handled based on the physical and dynamical understands the data. Thereby, this paper proposes the following approaches: i) refining and combining major factors (weather radar, terrain, air temperature, and so on) related to precipitation development in order to construct training data for pattern analysis of precipitation; ii) producing predicted precipitation fields based on Convolutional with ConvLSTM. The proposed algorithm was evaluated by rainfall events in 2020. It is outperformed in the magnitude and strength of precipitation, and clearly predicted non-linear pattern of precipitation. The algorithm can be useful as a forecasting tool for preventing severe weather.

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Simulation of the effect of inclusions length and angle on the failure behavior of concrete structure under 3D compressive test: Experimental test and numerical simulation

  • Mohammad Saeed, Amini;Vahab, Sarfarazi;Kaveh, Asgari;Xiao, Wang;Mojtaba Moheb, Hoori
    • Steel and Composite Structures
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    • v.46 no.1
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    • pp.53-73
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    • 2023
  • Man-made structure materials like concrete usually contain inclusions. These inclusions affect the mechanical properties of concrete. In this investigation, the influence of inclusion length and inclination angle on three-dimensional failure mechanism of concrete under uniaxial compression were performed using experimental test and numerical simulation. Approach of acoustic emission were jointly used to analyze the damage and fracture process. Besides, by combining the stress-strain behavior, quantitative determination of the thresholds of crack stress were done. concrete specimens with dimensions of 120 mm × 150 mm × 100 mm were provided. One and two holes filled by gypsum are incorporated in concrete samples. To build the inclusion, firstly cylinder steel tube was pre-inserting into the concrete and removing them after the initial hardening of the specimen. Secondly, the gypsum was poured into the holes. Tensile strengths of concrete and gypsum were 2.45 MPa and 1.5 MPa, respectively. The angle bertween inclusions and axial loadind ary from 0 to 90 with increases of 30. The length of inclusion vary from 25 mm to 100 mm with increases of 25 mm. Diameter of the hole was 20 mm. Entirely 20 various models were examined under uniaxial test. Simultaneous with experimental tests, numerical simulation (Particle flow code in two dimension) were carried out on the numerical models containing the inclusions. The numerical model were calibrated firstly by experimental outputs and then failure behavior of models containing inclusions have been investigated. The angle bertween inclusions and axial loadind vary from 0 to 90 with increases of 15. The length of inclusion vary from 25 mm to 100 mm with increases of 25 mm. Entirely 32 various models were examined under uniaxial test. Loading rate was 0.05 mm/sec. The results indicated that when inclusion has occupied 100% of sample thickness, two tensile cracks originated from boundaries of sample and spread parallel to the loading direction until being integrated together. When inclusion has occupied 75% of sample thickness, four tensile cracks originated from boundaries of sample and spread parallel to the loading direction until being integrated together. When inclusions have occupied 50% and 25% of sample thickness, four tensile cracks originated from boundaries of sample and spread parallel to the loading direction until being integrated together. Also the inclusion was failed by one tensile crack. The compressive strength of samples decease with the decreases of the inclusions length, and inclusion angle had some effects on that. Failure of concrete is mostly due to the tensile crack. The behavior of crack, was affected by the inclusion length and inclusion number.