• Title/Summary/Keyword: Technology Residual Life Analysis

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A Study on Design of Fillet Weld Size for Stiffener in the Hull Bottom of Crude Oil Tanker (Crude Oil Tanker 선저부 보강재 필렛 용접부 각장 설계에 관한 연구)

  • Kang, Bong-Gook;Shin, Sang-Beom;Park, Dong-Hwan
    • Journal of Welding and Joining
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    • v.32 no.1
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    • pp.79-86
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    • 2014
  • The purpose of this study is to determine the proper fillet weld size for the stiffeners on hull bottom plate of crude oil tanker. To achieve it, the effective notch stress and hot spot stress of the fillet weld with leg length specified in the rule were evaluated by using comprehensive FE analyses. Based on the results, the fatigue damages at each location of weld were calculated. Meanwhile the transitional behavior of initial welding distortion in the hull bottom plate under the design conditions was investigated by using a non-linear FEA. Welding distortion and residual stress introduced during fabrication process were considered as initial imperfections. According to FE analysis results, if the fillet leg length satisfies the design criteria of the classification society, the concern on the root failure at the fillet welds in the bottom hull plate during the design life can be negligible. In addition, considering the transitional behavior of the distortion during the service life, the fillet leg length should be minimized.

Spatiotemporal chlorine residual prediction in water distribution networks using a hierarchical water quality simulation technique (계층적 수질모의기법을 이용한 상수관망시스템의 시공간 잔류염소농도 예측)

  • Jeong, Gimoon;Kang, Doosun;Hwang, Taemun
    • Journal of Korea Water Resources Association
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    • v.54 no.9
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    • pp.643-656
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    • 2021
  • Recently, water supply management technology is highly developed, and a computer simulation model plays a critical role for estimating hydraulics and water quality in water distribution networks (WDNs). However, a simulation of complex large water networks is computationally intensive, especially for the water quality simulations, which require a short simulation time step and a long simulation time period. Thus, it is often prohibitive to analyze the water quality in real-scale water networks. In this study, in order to improve the computational efficiency of water quality simulations in complex water networks, a hierarchical water-quality-simulation technique was proposed. The water network is hierarchically divided into two sub-networks for improvement of computing efficiency while preserving water quality simulation accuracy. The proposed approach was applied to a large-scale real-life water network that is currently operating in South Korea, and demonstrated a spatiotemporal distribution of chlorine concentration under diverse chlorine injection scenarios.

Improvement in Thin-layer Chromatography in a Quantitative Assay of Glycerol in Biodiesel (개선된 thin-layer chromatography를 이용한 바이오디젤 중의 글리세롤 정량분석)

  • Lee, Sang-Eun;Choi, Woo-Seok;Kang, Do-Hyung;Lee, Hyeon-Yong;Jung, Kyung-Hwan
    • Journal of Life Science
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    • v.23 no.4
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    • pp.537-541
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    • 2013
  • We analyzed glycerol using thin-layer chromatography (TLC) and compared the separation resolution of some mobile phases. When acetonitrile:distilled water (85:15 v/v) was used as a mobile phase, the band of glycerol on the TLC was more distinctly and rapidly separated. Using TLC analysis, we prepared a calibration curve for the glycerol concentration vs. the area of the glycerol band in which the glycerol concentration of the x-axis was converted into a log-scale ranging from 3.0 to 0.0625 (%, w/v). Based on this calibration curve, the residual glycerol concentration (0.2 [%, w/v]) in biodiesel was determined successfully using TLC analysis. When the results of the TLC analysis were compared with those of a chemical and enzymatic assay, the results were fairly similar. We conclude that TLC without additional analytical instruments can be used as an alternative method for the quantitative analysis of the concentration of glycerol in biodiesel.

Analysis of the Relationship between Concrete Slab Track Life and Secondary Compression Characteristics in Soft Clay (점토의 2차 압축특성과 콘크리트궤도 수명과의 상관성 분석)

  • Lee, Sang-Cheol;Cho, Kook-Hwan
    • Journal of the Korean Society for Railway
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    • v.19 no.2
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    • pp.195-203
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    • 2016
  • Concrete slab track was applied to the Gyeoungbu High Speed Railroad step 2 and the Honam High Speed Railroad. Concrete slab track incurs higher construction cost and lower maintenance cost than existing gravel track. For these reasons, the use of concrete slab track has increased in Korea. The biggest problem in the use of concrete slab track is repairing damage from settlement that can occur while trains are in service. High speed railroad design standards require allowable residual settlement of concrete slab track of less than 25mm. In order to satisfy the requirement of long term stability of concrete slab track, it is necessary to manage the secondary compression settlement within the allowable residual settlement. This study is to evaluate the secondary compression settlement with the variation of the secondary compression index, thickness of soft ground, and concrete slab track life. Statistical analysis is performed to determine the probability of distribution of areas where serious problems will be caused after the concrete slab track is constructed.

Assessment of Fatigue Life of Out-Of-Plane Gusset Welded Joints using 3D Crack Propagation Analysis (3차원 피로균열 진전해석을 통한 면외거셋 용접이음의 피로수명 평가)

  • Jeong, Young-Soo;Kainuma, Shigenobu;Ahn, Jin-Hee;Lee, Wong-Hong
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.22 no.1
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    • pp.129-136
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    • 2018
  • The estimation of the fatigue design life for large welded structures is usually performed using the liner cumulative damage method such as Palmgren-Miner rule or the equivalent damage method. When a fatigue crack is detected in a welded steel structure, the residual service life has to be estimated base on S-N curve method and liner elastic fracture mechanics. In this study, to examine the 3D fatigue crack behavior and estimate the fatigue life of out-of-plane gusset fillet welded joint, the fatigue tests were carried out on the model specimens. Investigations of three-dimensional fatigue crack propagation on gusset welded joint was used the finite element analysis of FEMAP with NX NASTRAN and FRANC3D. Fatigue crack growth analysis was carried out to demonstrate the effects of aspect ratio, initial crack length and stress ratio on out-of-plane gusset welded joints. In addition, the crack behaviors of fatigue tests were compared with those of the 3D crack propagation analysis in terms of changes in crack length and aspect ratio. From this analysis result, SIFs behaviors and crack propagation rate of gusset welded joint were shown to be similar fatigue test results and the fatigue life can also be predicted.

Measurement of Effective Half-life Using Dual Time I-131 Whole Body Scan in Patients with Differentiated Thyroid Cancer Treated by High Dose Therapy (고용량 방사성옥소 치료를 받은 갑상선분화암 환자에서 Dual Time I-131 Whole Body Scan을 이용한 유효반감기의 측정)

  • Yoon, Jae Sik;Lee, Jae Gon;Lee, Ki Hyun;Lim, Kwang Seok;Choi, Hak Ki;Lee, Sang Mi
    • The Korean Journal of Nuclear Medicine Technology
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    • v.18 no.1
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    • pp.98-103
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    • 2014
  • Purpose: The effective half life of I-131 is useful to calculate radiation dose, period of hospitalization, and exposure dose of surrounding people from patient. However, it is difficult to measure. This study estimates the effective half life in whole body and thyroid in using of value of residual radioactivity obtained from the early and delay images of Dual time I-131 whole body scan. Also, the correlations between the effective half life and serum creatinine, GFR, and administration dose were investigated in this study. Materials and Methods: The targets were 50 patients administration high dose of I-131 from February to August in 2013, having normal range of serum creatinine and over $30{\mu}IU/mL$ of TSH levels. After administration radioactive I-131, the early scan in the 3rd day and the delay scan in the 5-6th days were performed. To measure the residual radioactivity in the whole body and thyroid, ROI was set and then background radioactivity was corrected to estimate. The effective half life was estimated by calculating the ratio of measured values between the early and delay images. To compare the effective half lives of the whole body and thyroid, it was analyzed by Independent t-test, and each correlation of the effective half life, GFR, serum creatinine, and the dose of administration were analyzed by calculating the pearson's correlation coefficient. All of the analysis were determined to be statistically significant when P<0.05. Results: The effective half life of the whole body was $17.06{\pm}5.50$ hours and of the thyroid was $17.22{\pm}5.41$ hours. The two effective half life did not show significant difference (P=0.887). As the value of GFR was increased, the effective half life of whole body (r=-0.407, P=0.003) and of thyroid (r=-0.473, P=0.001) were significantly decreased; as the value of serum creatinine was increased, the effective half life of whole body (r=0.309, P=0.029) and of thyroid (r=0.371, P=0.008) were significantly increased. In the administration dose, effective half life did not have correlations. Conclusion: The effective half life of I-131 of patients treated for their thyroids were estimated only by using the images of Dual time I-131 whole body scan. Also, the correlations with the effective life, GFR, and serum creatinine were examined. This study might be utilized for a study on optimization for the period of hospitalization of patients treated by high dose of I-131 and on evaluation for internal absorbed dose of MIRD schema in application of the effective half life.

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Fatigue evaluation and CFRP strengthening of diaphragm cutouts in orthotropic steel decks

  • Ke, Lu;Li, Chuanxi;He, Jun;Lu, Yongjun;Jiao, Yang;Liu, Yongming
    • Steel and Composite Structures
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    • v.39 no.4
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    • pp.453-469
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    • 2021
  • The cracking at the transverse diaphragm cutout is one of the most severe fatigue failures threatening orthotropic steel decks (OSDs), whose mechanisms and crack treatment techniques have not been fully studied. In this paper, full-scale experiments were first performed to investigate the fatigue performance of polished cutouts involving the effect of an artificial geometrical defect. Following this, comparative experimental testing for defective cutouts strengthened with carbon fiber-reinforced polymer (CFRP) was carried out. Numerical finite element analysis was also performed to verify and explain the experimental observations. Results show that the combinative effect of the wheel load and thermal residual stress constitutes the external driving force for the fatigue cracking of the cutout. Initial geometrical defects are confirmed as a critical factor affecting the fatigue cracking. The principal stress 6 mm away from the free edge of the cutout can be adopted as the nominal stress of the cutout during fatigue evaluation, and the fatigue resistance of polished cutouts is higher than Grade A in AASHTO specification. The bonded CFRP system is highly effective in extending the fatigue life of the defective cutouts. The present study provides some new insights into the fatigue evaluation and repair of OSDs.

Design of Portable Welded-Nitrogen Vessel (11 kg, 10 L and 50 bar) for Shipbuilding (선박용 휴대형 질소용기(11 kg, 10 L 및 50 bar)의 두께 및 외형 설계)

  • Seong, Hansaem;Kim, Jaeyeol;Eom, Taejin;Kawk, Hyo Seo;Lee, Kwang O;Kim, Chul
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.41 no.4
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    • pp.263-270
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    • 2017
  • The shipbuilding industry uses large stationary tanks to store low-pressure air, which is used to open and close large shut-off valves. However, when supplying air from the tank to a distant valve, there are problems related to the need for supplementary pipes and the pressure drop during transportation. In this study, a portable welded vessel for storing high-pressure nitrogen (11 kg, 10 L, and 50 bar) was designed to prevent air leakage and improve the convenience of workers. This pressure vessel was elliptical to reduce the number of welded parts, which are structurally weak. The thickness and ratio of the major and minor axes of the pressure vessel were calculated to verify its structure stability at the working pressure (50 bar), and that the proposed weight and capacity were satisfactory. The residual stress caused by the welding process was calculated by performing a transient thermal-structural coupled field analysis using the ANSYS parametric design language (APDL), and the fatigue life of the vessel was verified based on the Goodman criterion.

A Comparison Analysis of Life Cycle Cost (LCC) of Pumps - In the Focus on Comparison of Excellent and General Products in Water Industry - (Pump의 생애주기 비용(LCC) 비교 분석 - 물산업 우수제품과 일반제품의 비교를 중심으로 -)

  • Park, Woopyung;Choi, Yong;Jeon, Si Young;Kim, Jinho;Kang, Seongmi
    • Korean Journal of Construction Engineering and Management
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    • v.23 no.3
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    • pp.66-73
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    • 2022
  • In order to induce users to purchase excellent products in the water industry that satisfy the technical standards of excellent products, in this study, it is to present the advantages of the cost aspect of the pumps as the objective basis. It will be to promote technology development of domestic water companies and to create a virtuous cycle structure in the water industry. In order to present an objective basis for the merits in terms of cost, an economic evaluation was conducted through life cycle cost analysis. For the LCC analysis, initial cost (pump cost and installation cost), operation cost (energy cost and maintenance cost) and demolition cost (disposal cost and residual value) are searched and calculated. As the results of comparison on two capacity of pumps, the energy cost of the excellent pump is 212 million KRW lower than the that of general pump in the large pump. The cost of excellent pump was 17 million KRW lower than that of general pump in small capacity pump. As the results of sensibility test, if the product is developed in the direction of improving pump efficiency and increasing the replacement cycle of consumables, it is predicted that the effect on LCC will be large.

Network vision of disaster prevention management for seashore reclaimed u-City (해안매립 신도시의 재해 예방관리 네트워크 비젼)

  • Ahn, Sang-Ro
    • Proceedings of the Korean Geotechical Society Conference
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    • 2009.09a
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    • pp.117-129
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    • 2009
  • This paper studied the safety management network system of infrastructure which constructed smart sensors, closed-circuit television(CCTV) and monitoring system. This safety management of infrastructure applied to bridge, cut slop and tunnel, embankment etc. The system applied to technologies of standardization guidelines, data acquirement technologies, data analysis and judgment technologies, system integration setup technology, and IT technologies. It was constructed safety management network system of various infrastructure to improve efficient management and operation for many infrastructure. Integrated safety management network system of infrastructure consisted of the real-time structural health monitoring system of each infrastructure, integrated control center, measured data transmission using i of tet web-based, collecting data using sf ver, early alarm system which the dangerous event of infrastructure occurred. Integrated control center consisted of conference room, control room to manage and analysis the data, server room to present the measured data and to collect the raw data. Early alarm system proposed realization of warning and response within 5 minute or less through development of sensor-based progress report and propagation automation system using the media such as MMS, VMS, EMS, FMS, SMS and web services of report and propagation. Based on this, the most effective u-Infrastructure Safety Management System is expected to be stably established at a less cost, thus making people's life more comfortable. Information obtained from such systems could be useful for maintenance or structural safety evaluation of existing structures, rapid evaluation of conditions of damaged structures after an earthquake, estimation of residual life of structures, repair and retrofitting of structures, maintenance, management or rehabilitation of historical structures.

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