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Conservation for the Seismic Models of Intake Tower with Nonlinear Behaviors and Fluid Structure Interaction (비선형거동과 구조물유체상호작용을 고려한 취수탑 내진모델의 보수성평가)

  • Lee, Gye-Hee;Lee, Myoung-Kyu;Hong, Kwan-Young
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.24 no.6
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    • pp.17-24
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    • 2020
  • In this study, series of nonlinear seismic analysis were performed on a reinforced concrete intake tower surrounded by water. To consider the fluid effect around the structure, analysis models were composed using an added mass and CEL approach. At this time, the implicit method was used for the added mass model, and the explicit method was used for the fluid structure interaction model. The input motions were scaled to correspond to 500, 1000, and 2400 years return period of the same artificial earthquake. To estimate the counteractivity of the fluid coupled model, models without fluid effect were constructed and used as a reference. The material models of concrete and reinforcement were selected to consider the nonlinear behavior after yielding, and analysis were performed by ABAQUS. As results, in the acceleration response spectrum of the structure, it was found that the influence of the surrounding fluid reducing the peak frequency and magnitude corresponding to the fundamental frequency of the structure. However, the added mass model did not affect the peak value corresponding to the higher mode. The sectional moments were increased significantly in the case of the added mass model than those of the reference model. Especially, this amplification occurred largely for a small-sized earthquake response in which linear behavior is dominant. In the fluid structure interaction model, the sectional moment with a low frequency component amplifies compared to that of the reference model, but the sectional moment with a high requency component was not amplified. Based in these results, it was evaluated that the counteractivity of the additive mass model was greater than that of the fluid structure interaction model.

Development of an Input File Preparation Tool for Offline Coupling of DNDC and DSSAT Models (DNDC 지역별 구동을 위한 입력자료 생성 도구 개발)

  • Hyun, Shinwoo;Hwang, Woosung;You, Heejin;Kim, Kwang Soo
    • Korean Journal of Agricultural and Forest Meteorology
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    • v.23 no.1
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    • pp.68-81
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    • 2021
  • The agricultural ecosystem is one of the major sources of greenhouse gas (GHG) emissions. In order to search for climate change adaptation options which mitigate GHG emissions while maintaining crop yield, it is advantageous to integrate multiple models at a high spatial resolution. The objective of this study was to develop a tool to support integrated assessment of climate change impact b y coupling the DSSAT model and the DNDC model. DNDC Regional Input File Tool(DRIFT) was developed to prepare input data for the regional mode of DNDC model using input data and output data of the DSSAT model. In a case study, GHG emissions under the climate change conditions were simulated using the input data prepared b y the DRIFT. The time to prepare the input data was increased b y increasing the number of grid points. Most of the process took a relatively short time, while it took most of the time to convert the daily flood depth data of the DSSAT model to the flood period of the DNDC model. Still, processing a large amount of data would require a long time, which could be reduced by parallelizing some calculation processes. Expanding the DRIFT to other models would help reduce the time required to prepare input data for the models.

Radon Hazard Review of Spilled Groundwater and Tap Water in Incheon Metropolitan City Subway Station (인천광역시 지하철 역사 내 지하수 및 수돗물의 라돈 위해성 검토)

  • Lee, Yoo-Sang;Lee, Sang-Bok;Kang, Min-Seok;Jeong, Dong-Ha;Kim, Jin-Hong;Oh, Yoon-Sik;Choi, Se-Rin;Park, Jeong-Soo;Kim, Sungchul
    • Journal of radiological science and technology
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    • v.44 no.6
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    • pp.671-677
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    • 2021
  • Interest in the everyday hazards of radon has recently increased as such, this study attempted to examine the dangers of radon in spilled groundwater by comparing the radon concentrations of the drained groundwater and tap water used in recirculating systems in Incheon Subway restrooms. At five stations of Incheon Subway Line 1 and three stations of Line 2, drained groundwater is recirculated and used in restrooms for toilet flushing. Stations restroom tap water for hand washing that used as a control and the measured values of each were compared. With the cooperation of Incheon Transportation Corporation, samples of spilled groundwater and tap water were collected sealed to prevent contact with the air, and a DURRIDGE RAD7 was used as the experimental equipment. The collected samples were subjected to radial equilibration for approximately 3.5 h, at which the radon concentration reached its maximum, and then calculated as 10 measurements using the RAD7 underwater radon measurement mode. In all eight stations, the radon concentration in tap water was lower than the recommended amount. However, in an average of 7 out of the eight stations, the radon concentration in the effluent groundwater was 100 times higher than that in tap water. Since high radon concentrations in groundwater runoff can be harmful to humans, and there is no accurate standard for radon concentrations in domestic water, it is necessary to continuously monitor radon in water and prepare a guidance of recommended values.

Calculation of Expected Life of Hydrogen Pressure Vessels by Fracture and Fatigue Mechanics assuming Semi-elliptical Cracks and Analysis of the Effect of Thickness and Radius (반타원형 균열을 가정한 파괴 및 피로역학에 의한 수소 압력용기의 예상 수명 계산과 두께와 내경이 미치는 영향 분석)

  • Kim, Jeong Hwan;Lee, Hwa Young;Lee, Min-Kyung;Lee, Jae-Hun;Lyu, Geunjun
    • Journal of the Korean Institute of Gas
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    • v.25 no.6
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    • pp.53-65
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    • 2021
  • While the hydrogen refueling station is rapidly expanded and installed, the safety inspection of the hydrogen pressure vessel in the station should be very important. Of these, according to ASME, hydrogen embrittlement tests must be performed for hydrogen vessel that store hydrogen above a certain pressure. The main test method for hydrogen embrittlement inspection is to carry out fracture tests and fatigue fracture tests in a high pressure hydrogen atmosphere, which allows the durability limit of the pressure vessel to be measured and the endurable limit to be determined in the hydrogen atmosphere. In detail, the critical crack depth can be calculated by the stress intensity factor(K), and the service life can be determined by da/dN (fatigue growth rate). API579-1/ ASME FFS-1 part 9 exemplifies the calculation method according to the mode of crack-like flaws, but for various shapes such as plates and cylinders, there are about 55 modes according to the shape and location of the crack. Due to the fairly complex formula, it is not easily accessible. In this study, we will show you how to calculate fracture mechanics numerically via Excel and VBA. In addition, this was applied to analyze the effects of the thickness and inner diameter of the pressure vessel on the service life.

Analysis of Built and Walking Environment for Coastal Ferry Terminal using IPA -Focusing on Yeosu Coastal Ferry Terminal- (IPA를 이용한 연안여객터미널의 시설 및 보행특성 분석 -여수연안여객터미널을 중심으로-)

  • Song, Tea-Han;Kim, Hwa-Young
    • Journal of Korea Port Economic Association
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    • v.37 no.3
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    • pp.93-104
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    • 2021
  • A coastal ferries, which serve as a mode between mainland and offshore islands, are frequently used by islanders and travelers visiting islands. Therefore, it is located in a place with good accessibility to the downtown so that users can use it conveniently. However, research on the built environment and walking environment of coastal ferry terminals has not been conducted to ensure that elderly islanders and general travelers can use comfortably the coastal ferry terminal. In this study, with a focus on the coastal ferry terminal space, the walking section was set as 1)the accessibility of the coastal ferry terminal, 2)the built environment for using the coastal ferry terminal, and 3)walking environment in the ferry boarding and disembarkation at the coastal ferry terminal, and 4, 5)walking environment in the ferry. An evaluation tool was developed to measure the walking environment for each walking section, and the importance and satisfaction of users were analyzed using the IPA for the Yeosu Coastal Ferry Terminal. As a result, in the process of approaching the ferry terminal, 'convenience of using public transportation by foot' and 'convenience of using signposts guiding the location and direction of the ferry terminal' were investigated as concentrated areas. On the other hand, the built environment inside the ferry terminal and the walking environment showed that the satisfaction of the users was high. Regarding the walking environment from the ferry terminal to the ferry, the 'surface walking environment of the walking path', 'convenience of walking with luggage', 'convenience of walking in the slope section', and 'convenience of walking in the ferry ramp section' showed low satisfaction. This study can be used as basic data for improving the facilities and walking environment of Yeosu Coastal Ferry Terminal and is expected to be used as data for comparative research with other coastal ferry terminals.

Entomopathogenic Fungi-mediated Pest Management and R&D Strategy (곤충병원성 진균을 활용한 해충 관리와 개발 전략)

  • Lee, Se Jin;Shin, Tae Young;Kim, Jong-Cheol;Kim, Jae Su
    • Korean journal of applied entomology
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    • v.61 no.1
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    • pp.197-210
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    • 2022
  • Entomopathogenic fungi can be used to control a variety of sucking and chewing insects, with little effect on beneficial insects and natural enemies. Approximately 170 entomopathogenic fungal insecticides have been registered and used worldwide, with the recent focus being on the mode of action and mechanism of insect-fungal interactions. During the initial period of research and development, the industrialization of entomopathogenic fungi focused on the selection of strains with high virulence. However, improvement in productivity, including securing resistance to environmental stressors, is a major issue that needs to be solved. Although conidia are the primary application propagules, efforts are being made to overcome the limitations of blastospores to improve the economic feasibility of the production procedure. Fungal transformation is also being conducted to enhance insecticidal activity, and molecular biology is being used to investigate functions of various genes. In the fungi-based pest management market, global companies are setting up cooperative platforms with specialized biological companies in the form of M&As or partnerships with the aim of implementing a tank-mix strategy by combining chemical pesticides and entomopathogenic fungi. In this regard, understanding insect ecology in the field helps in providing more effective fungal applications in pest management, which can be used complementary to chemicals. In the future, when fungal applications are combined with digital farming technology, above-ground applications to control leaf-dwelling pests will be more effective. Therefore, for practical industrialization, it is necessary to secure clear research data on intellectual property rights.

Analysis of Failure Behavior of FRP Rebar Reinforced Concrete Slab based on FRP Reinforced Ratio (FRP 보강근비에 따른 FRP 보강 콘크리트 슬래브의 파괴거동 분석)

  • Jang, Nag-Seop;Kim, Young-Hwan;Oh, Hong-Seob
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.25 no.5
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    • pp.173-181
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    • 2021
  • Reinforced concrete structures are exposed to various environments, resulting in reinforcement corrosion due to moisture and ions penetration. Reinforced concrete corrosion causes a decrease in the durability performance of reinforced concrete structures. One solution to mitigate such issues is using FRP rebars, which offer several advantages such as high tensile strength, corrosion resistance, and light-weight than conventional rebars, in reinforced concrete instead of conventional steel rebars. The FRP rebar used should be examined at the limit state because FRP reinforced concrete has linear behavior until its fracture and can generate excessive deflection due to the low elastic modulus. It should be considered while designing FRP reinforced concrete for flexure. In the ultimate limit state, the flexural strength of FRP reinforced concrete as per ACI 440.1R is significantly lower than the flexural strength by applying both the environmental reduction and strength reduction factors accounting for the material uncertainty of FRP rebar. Therefore, in this study, the experimental results were compared with the deflection of the proposed effective moment of inertia referring to the local and international standards. The experimental results of GFRP and BFRP reinforced concrete were compared with the flexural strength as determined by ACI 440.1R and Fib bulletin 40. The flexural strength obtained by the experimental results was more similar to that obtained by Fib bulletin 40 than ACI 440.1R. The flexural strength of ACI 440.1R was conservatively evaluated in the tension-controlled section.

An Analysis of Temperature Change and TI MI using Tissue Mimicking Phantom in Ultrasonic Examination (초음파검사에서 인체모의 매질팬텀을 이용한 온도 변화와 TI MI 분석)

  • Cheol-Min, Jeon;Jae-Bok, Han;Jong-Gil ,Kwak;Jong-Nam, Song
    • Journal of the Korean Society of Radiology
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    • v.16 no.6
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    • pp.751-759
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    • 2022
  • Currently, ultrasound examination for diagnostic ultrasound and health examination purposes is widely used, and it is showing an increasing trend due to the application of health insurance. However, the risk of ultrasound has not been clearly identified so far, and in this study, surface and deep temperature changes according to frequency and mode were measured by using a tissue mimicking phantom and TI and MI values were compared. A simulated phantom was manufactured by adding a small amount of kappa-caraginan powder with acoustic characteristics similar to that of the human body and potassium chloride for solidification, and the change of surface and depth temperature was measured using a surface thermometer and a probe thermometer. As a result, the convex probe using low frequency showed a higher temperature increase than the linear probe using high frequency, so there was a significant difference, and the temperature increase was the highest on the surface, and the depth of 1cm showed a temporary temperature increase, but there was no significant temperature change. There was no change in the deep temperature of 5 cm to 15 cm, and the TI and MI values did not change during the test time. Since only the surface temperature rose during the 15-minute test and there was no temperature change in the core, so it is not expected to show a temperature change that is harmful to the human body. However, it is thought that prolonged examination of one area may cause temperature rise, so it should be avoided.

Hepatitis B Vaccination Coverage and Related Factors among Aged 19 or Older in Republic of Korea (한국 19세 이상 성인들의 B형간염 백신 접종률 및 관련 요인)

  • Lee, Sok Goo;Jeon, So Youn
    • Journal of agricultural medicine and community health
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    • v.47 no.2
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    • pp.99-108
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    • 2022
  • Objectives: This study aimed to identify the vaccination coverage for hepatitis B among aged 19 or older, and at the same time to determine the reasons for vaccination or non-vaccination. Methods: The survey was conducted through a Mixed-Mode Random Digit Dialing Survey (RDD) method. The survey included hepatitis B vaccination status, reasons of vaccination and non-vaccination, sources of information on vaccination, and other related factors. Results: The vaccination coverage for hepatitis B among adults 19 years of age and older were 38.0%, 32.5%, and 26.9% for the first, second, and third doses. A related factors with high rate of hepatitis B vaccination was women, younger than 65 years of age, rural residents, having a job, highly educated, health insurance subscribers, living with spouse, family members living together. In addition, the vaccination rate was higher in those who was aware of the states recommended adult vaccination, were explained by a doctor about the need for adult vaccination, kept their vaccination records, and recognized that it helped prevent infectious diseases, and had seen promotional materials. Conclusions: In the future, it is necessary to check the antibody retention rate along with the hepatitis B vaccination coverage of adults on a regular basis. In addition, in order to accurately and quickly identify the hepatitis B vaccination coverage, it is necessary to prepare a plan to improve the computerized registration rate to manage adult vaccination records.

BEEF MEAT TRACEABILITY. CAN NIRS COULD HELP\ulcorner

  • Cozzolino, D.
    • Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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    • 2001.06a
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    • pp.1246-1246
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    • 2001
  • The quality of meat is highly variable in many properties. This variability originates from both animal production and meat processing. At the pre-slaughter stage, animal factors such as breed, sex, age contribute to this variability. Environmental factors include feeding, rearing, transport and conditions just before slaughter (Hildrum et al., 1995). Meat can be presented in a variety of forms, each offering different opportunities for adulteration and contamination. This has imposed great pressure on the food manufacturing industry to guarantee the safety of meat. Tissue and muscle speciation of flesh foods, as well as speciation of animal derived by-products fed to all classes of domestic animals, are now perhaps the most important uncertainty which the food industry must resolve to allay consumer concern. Recently, there is a demand for rapid and low cost methods of direct quality measurements in both food and food ingredients (including high performance liquid chromatography (HPLC), thin layer chromatography (TLC), enzymatic and inmunological tests (e.g. ELISA test) and physical tests) to establish their authenticity and hence guarantee the quality of products manufactured for consumers (Holland et al., 1998). The use of Near Infrared Reflectance Spectroscopy (NIRS) for the rapid, precise and non-destructive analysis of a wide range of organic materials has been comprehensively documented (Osborne et at., 1993). Most of the established methods have involved the development of NIRS calibrations for the quantitative prediction of composition in meat (Ben-Gera and Norris, 1968; Lanza, 1983; Clark and Short, 1994). This was a rational strategy to pursue during the initial stages of its application, given the type of equipment available, the state of development of the emerging discipline of chemometrics and the overwhelming commercial interest in solving such problems (Downey, 1994). One of the advantages of NIRS technology is not only to assess chemical structures through the analysis of the molecular bonds in the near infrared spectrum, but also to build an optical model characteristic of the sample which behaves like the “finger print” of the sample. This opens the possibility of using spectra to determine complex attributes of organic structures, which are related to molecular chromophores, organoleptic scores and sensory characteristics (Hildrum et al., 1994, 1995; Park et al., 1998). In addition, the application of statistical packages like principal component or discriminant analysis provides the possibility to understand the optical properties of the sample and make a classification without the chemical information. The objectives of this present work were: (1) to examine two methods of sample presentation to the instrument (intact and minced) and (2) to explore the use of principal component analysis (PCA) and Soft Independent Modelling of class Analogy (SIMCA) to classify muscles by quality attributes. Seventy-eight (n: 78) beef muscles (m. longissimus dorsi) from Hereford breed of cattle were used. The samples were scanned in a NIRS monochromator instrument (NIR Systems 6500, Silver Spring, MD, USA) in reflectance mode (log 1/R). Both intact and minced presentation to the instrument were explored. Qualitative analysis of optical information through PCA and SIMCA analysis showed differences in muscles resulting from two different feeding systems.

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