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Estimates of Partial Safety Factors of Circumferential Through-Wall Cracked Pipes Based on Elastic-Plastic Crack Initiation Criterion (탄소성 균열개시조건에 대한 원주방향 관통균열 배관의 부분안전계수 계산)

  • Lee, Jae-Bin;Huh, Nam-Su
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.38 no.11
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    • pp.1257-1264
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    • 2014
  • Efforts are presently underway for developing an optimal design methodology for GEN-IV nuclear reactors based on target failure probabilities. A typical example is the system-based code, in which the results are represented in the form of partial safety factors (PSFs). Thus, a PSF is one of the crucial elements in either component design or integrity assessment based on target failure probabilities during the operation period. In the present study, a procedure for calculating the PSF of a circumferential through-wall cracked pipe based on the elastic-plastic crack initiation criterion is established, in which the importance of each input variable is assessed. Elastic-plastic J-integrals are calculated using the GE/EPRI and reference stress methods, and the PSF values are calculated using both first- and second-order reliability methods. Moreover, the effect of statistical distributions of assessment variables on the PSF is also evaluated.

Integrity Evaluation of Railway Bogie Using Infrared Thermography Technique (적외선 열화상 기술을 이용한 철도차량 대차 건전성 평가)

  • Kim, Jeong-Guk
    • Journal of the Korean Society for Nondestructive Testing
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    • v.31 no.2
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    • pp.144-149
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    • 2011
  • The lock-in thermography was employed to evaluate the integrity of railway bogies. Prior to the actual application on railway bogies, in order to assess the detectability of known flaws, the calibration reference panel was prepared with various dimensions of artificial flaws. The panel was composed of structural steel, which was the same material with actual bogies. Through lock-in thermography evaluation, the optimal frequency of heat source was determined for the best flaw detection. Based on the defects information, the actual defect assessments on railway bogie were conducted with different types of railway bogies, which were used for the current operation. In summary, the defect assessment results with thermography method showed a good agreement as compared with the conventional inspection techniques. Moreover, it was found that the novel infrared thermography technique could be an effective way for the inspection and the detection of surface defects on bogies since the infrared thermography method provided rapid and non-contact mode for the investigation of railway bogies.

Study on Activity, Type and Establishment of Community Supported Agriculture in USA and Japan (미국과 일본의 CSA운동의 등장, 유형 및 활동사례)

  • 정진영;손상목;김영호
    • Korean Journal of Organic Agriculture
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    • v.9 no.1
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    • pp.1-16
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    • 2001
  • With increasing global concern that intensively synthetic-chemical based farming systems accelerated the decline in environmental quality, the sustainability of modem agriculture became the subject of great concern. It is well known that the movement of Community Supported Agriculture(CSA) has been contributed significantly to the development of organic agriculture in USA and Japan. It was supposed that CSA could be one of the best way to promote the movement of organic agriculture since there is little reliability on the organically grown food by consumer. In this paper it was focussed to study the movement of CSA in USA and Europe in order to provide an idea for establishment and movement of CSA in Korea to support the organic agriculture. In a CSA system, the farmer grows food for a group of shareholders who pledge to buy a portion of the farm's crop that season. This arrangement gives growers up-front cash to finance their operation and higher prices for produce, since the middleman has been eliminated. For most shareholder for CSA saving money is a secondary consideration, but fresh safe products and environmentally sound farming system. People become shareholder of CSA since they expect an organic farming which can ; \circled1protect the environment, minimize pollution, promote health, \circled2replenish and maintain long-term soil fertility by providing optimal conditions for soil biological activity, \circled3maintain diversity within the farming system and its surroundings and protect plant and wildlife habit, \circled4recycle materials and resources to the greatest extent possible within the farm and its surrounding community, \circled5maintain the integrity of organic food and processed products through each step of the process from planting to consumption, \circled6develop and adopt new technologies with consideration for their long range social and ecological impact. In all CSAs, the farmer develops a crop plan and a budget, which details costs for a growing season, including fair wages for the farmers. Experienced Information on increasing shareholder retention, the future of CSA, and getting started such as ideas for ongoing marketing, printed materials that set realistic expectations, working members, production, pick-up and delivery, setting prices, and receiving feedback were also briefly introduced.

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Urethroplasty of Urethral Defect with Longitudinal Tubed Flap of Scrotal Skin after Fournier's Gangrene (Necrotizing Fascitis) (회음부 괴사성 근막염후 발생한 요도 결손의 치료를 위한 음낭피부 종축관피판을 이용한 요도성형술)

  • Min, Hee-Joon;Roh, Tai-Suk;Kim, Ji-Ye;Kim, Sug-Won
    • Archives of Plastic Surgery
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    • v.37 no.5
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    • pp.667-670
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    • 2010
  • Purpose: The management of urethral defect represents one of the most challenging clinical problems in uroplastic surgery. Especially for defect after Fournier's Gangrene, optimal management is still a hard problem. During extensive urethral reconstruction, to overcome the poor vascularity due to periurethral scarred tissue and limitation of the choice of local flap, we report our experience with one-stage reconstruction of urethral defect using a longitudinal tubed flap of scrotal skin. Methods: A 72-year-old man with several years of diabetes mellitus history visited for swelling and pain of scrotal area. After diagnosis of Fournier's Gangrene, radical debridement was performed and 6 cm of urethral defect on border of penile-scrotal ventral area was made. Rectangular scrotal skin flap (6×2.5cm) based on external spermatic fascia was elevated and tubed longitudinally. After transfer the flap to the defect area, end-to-end anastomosis was performed bilaterally. Results: 4 weeks after the operation, the patient started voiding him-self and urethrography showed good fluence of contrast agent. Long term evaluation reveals stable performance characteristics without any complications. Conclusion: We suggest a one-stage reconstruction of extensive urethral defect using a longitudinal tubed flap of scrotal skin. Advantages of this procedures are simple, one-stage reconstruction with the reliable scrotal skin flap based on external spermatic fascial vasculature, and no donor morbidity.

A Study on the Computer-Aided Design of Dies for Hot Extrusion of Structural Shapes from Aluminum Alloys (알루미늄합금 형재의 열간압출 금형설계 자동화에 관한 연구)

  • Choe, Jae-Chan;Kim, Byeong-Min;Lee, Jin-Hui;Jo, Hae-Yong;Lee, Jong-Su;Hong, Seong-Seok;Jo, Nam-Chun
    • Journal of the Korean Society for Precision Engineering
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    • v.7 no.3
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    • pp.26-36
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    • 1990
  • This paper describes the Computer Aided Design (CAD) of dies for direct hot extrusion of structural shapes such as Z's and U's from aluminum alloys. A simple analysis of the direct extrusion process is developed and used to formulate a disign procedure for determining the optimal shape of the extrusion dies. A computer software system has been developed to design flat-faced dies for non-lubricated hot extrusion process. This software is a system of computer programs which are written to logical design procedure. Computer programs are based on empirical and analytical relationships, as well as on established knowledge based system. In the interactive mode of operation, the reaults at various tages of the design process are plotted on a screen. At any stage, the designer can interact with the computer to change or modify the design, based on his experience. The output from the program is (a) the design of the flat-faced die, (b) information on extrusion load, reduction ratio, and other process variables, etc. The implementation of this CAD system is expected to (a) provide scientific basis and rationalize the die design procedure, (b) optimize extrusion variables to maximize yield and production rate, (c) improve utilization of existing press capacity, etc.

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The Method of Deciding Design Level of Service with Optimal User Cost (사용자비용최적화를 통한 도로 설계서비스수준 산정방안)

  • 장재남;이용택;김호덕;장명순
    • Journal of Korean Society of Transportation
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    • v.18 no.2
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    • pp.17-26
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    • 2000
  • LOS(Level of Service), the qualitative measure describing operational condition of highway, must be evaluated as quantative index in terms of user service. So, This study is focused on developing the user cost function that user cost is measured in the variation of V/C, MOE(Measure of Effectiveness) of LOS in basic Section of highway. The user cost is calculated as the sum of accident cost, operation cost, travel time cost. The data is collected in the four basic section of Singal-Ansan and Jung bu Highway. As the result of user cost function analysis, the user cost is the lowest When V/C is 0.54. Considering the V/C ratio(0.7) of Basic Section in rural highway suggested in KHCM, We find out that the LOS suggested KHCM increase the user cost of highway.

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A Study on the Factors Affecting Cigarette Weight (II) (담배의 중량변화 요인에 판하여 (제2보))

  • 진학용;김남원;안기영;이태호
    • Journal of the Korean Society of Tobacco Science
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    • v.1 no.2
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    • pp.127-137
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    • 1979
  • Three factors affecting cigarette weight, tobacco shreds length(cut width 0.9mm), moisture content and filling grower were studied for domestic brands. The results were obtained as follows. 1. When the moisture contents war법 changed by one per cent consecutively. filling power of tobacco shreds and cigarette weight were changed by 3.9 - 7.9 per cent for the former and by 5.7 - 7.6 per cent for the later. The longer the length of tobacco, shreds, the wider are the changing radios, and vice versa. 2. At constant moisture content (12 %), filling Power and cigarette weight were varied by 3.8- 22.8 per cent and by 2.9-29.4 per cent respectively due to the fluctuation of tobacco shreds length, The range of this variation was increased by reducing moisture content , and was decreased by increasing the moisture content. 3. The higher the blending ratio of shreds longer than 2 mm, the lower are the cigarette weights. 4. The operation standard weight of domestic brands was found 1- 9 per cent higher compared with the observed optimal cigarette weight in this study.

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Evaluation of Flotation Efficiency and Particle Separation Characteristics of Carbon Dioxide Bubbles using Collision Efficiency Model (단일포집자충돌(SCC) 모델을 이용한 이산화탄소기포의 입자분리특성과 부상효율 평가)

  • Lee, Jun-Young;Kim, Seong-Jin;Yoo, Young-Hoon;Chung, Paul-Gene;Kwon, Young-Ho;Park, Yang-Kyun;Kwak, Dong-Heui
    • Journal of Korean Society on Water Environment
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    • v.28 no.1
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    • pp.129-136
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    • 2012
  • In this century, scientists realized that carbon dioxide gas in the atmosphere cause a greenhouse effect which affects the planet's temperature. Therefore lots of attempts have carried out to decrease the discharge of carbon dioxide gas in the field. The dissolved carbon dioxide flotation (DCF) process was developed as an alternative of DAF process to decrease the discharge and reuse of carbon dioxide as well as to save energy consumption. To investigate the particle separation characteristics and the flotation efficiency of carbon dioxide, SCC model was employed in the DCF process which has been applied extensively for the evaluation and simulation in the DAF process. The simulation results by the SCC model revealed the predicted curve of flotation efficiency became decreased gradually over the optimal pressure range of saturator about 1.6 atm in accordance with the experiment results of the DCF pilot plant and the size distribution and the bubble volume concentration of CO2 bubbles depending on the operation pressure of saturator. The findings through the simulation results led to the conclusion that there was no significant difference between CO2 bubbles and air bubbles, affecting on the practical flotation efficiency, in terms of the initial collision and attachment efficiency.

A Feasibility Study for Renewable Energy from Sewage Sludge Biogas (하수슬러지 Biogas의 신재생에너지화 타당성 연구)

  • Kang, Ho;Lee, Hye Mi;Cho, Sang Sun;Park, Sun Uk;Jeong, Ji Hyun
    • Journal of Korean Society on Water Environment
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    • v.26 no.5
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    • pp.754-760
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    • 2010
  • This study was carried out not only to evaluate optimal operating condition to increase biogas production, but also to estimate feasibility of renewable energy from anaerobic digester of sewage sludge. Semi- continuous Fed and Mixed Reactors (SCFMRs) were operated in various condition to quantify the reactor variables. The result of SCFMR operation showed that the biogas productivity and total volatile solids (TVS) removal of total solids (TS) 4% reactor at hydraulic retention time (HRT) 20 days with Organic Loading Rate (OLR) of 1.45kg/m3d were 0.39m3/m3d and 26.7%, respectively which was two times higher than that of TS 2.5% reactor. Consequently the daily biogas production of 20,000m3 would be possible from the total volume of 52,000m3 of anaerobic digesters of the municipal wastewater treatment plant in D city. In feasibility study for the Biogas utilization, combined heat and power system (CHP) and CNG gasification were examined. In case of CHP, the withdrawal period of capital cost for gas-engine (GE) and micro gas-turbine (MGT) were 7.7 years and 9.1 years respectively. biogas utilization as Clean Natural Gas (CNG) shows lower capital cost and higher profit than that of CHP system. CNG gasificaion after biogas purification is likely the best alternative for Biogas utilization which have more economic potential than CHP system. The withdrawal period of capital cost appeared to be 2.3 years.

Groundwater Quality Monitoring Network Design Using Integer Programming (정수계획법을 이용한 지하수 수질관측망의 설계)

  • Lee, Sang-Il;Kim, Hak-Min
    • Journal of Korea Water Resources Association
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    • v.32 no.5
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    • pp.557-564
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    • 1999
  • Monitoring of groundwater Quality is essential for the preservation of groundwater resources. In practice. however, groundwater monitoring network is designed based on the experience and intuition of experts or on the convenience. This study proposes a simulation-optimization approach for the optimal design of monitoring networks. In it, the predicted three-dimensional concentration data are used as the input of an optimization problem. Various design objectives and constraints are considered and the problem is formulatcu as the 0-1 integer programming. The methodology was applied to a sanitary landfill site. The results show that the monitoring network configuration changes as the monitoring goal, operation time and constraints vary. The proposed method turns out to be an efficient tool for the wide range of groundwater Quality monitoring network design problems.oblems.

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