• 제목/요약/키워드: Breakdown Structure

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Development of a Risk Management Procedure Model for the Construction Project Using Construction Risk Management System (CRMS를 활용한 건설공사의 리스크관리 절차모형 개발)

  • Kim, Chang Hak;Kang, Leen Seok;Park, Hong Tae
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.30 no.4D
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    • pp.423-432
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    • 2010
  • This study suggested CRMS (construction risk management system) which is a new risk analysis model after analyzing existing risk management process for to guarantee a successful performance at the construction planning and work phase. CRMS is risk management procedures in order that the contractor identify, analyze and administrate the risk during performing construction project. This model may give much help to quantify and be ready the right managing methods about identified risk by the contractor. Especially, the most important and difficult things of all risk management may be to identify risk in the project. This study make more focusing on the developing a procedure that can identify risk more easily in the construction project. The risk is divided into global risk and local risk of a project. Also, this study suggests methods which are using the RBS (risk breakdown structure) related with WBS. This result will be useful as basic materials for developing computerizing system for risk management.

DEVELOPMENT OF BUILDING INFORMATION MODEL FOR RESOURCES OPTIMIZATION IN CONSTRUCTION PROJECT

  • Gopal M. Naik;Rokhsareh Badamahgan
    • International conference on construction engineering and project management
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    • 2013.01a
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    • pp.634-639
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    • 2013
  • The aim of the study is to develop the 3D visualization of Building Information Model and integrated 4D model for optimization of resources in the construction project. This study discuss the process of methodology and creation of 4D model of the project and simulate it to monitor the workflow at the site. Different stages of the construction process and activities are generated by using Revit and MS Project. MS project has been used for creation of the schedules and these are linked with the Revit for 3D modeling. The time used as the fourth dimension and 4D model created by using Navisworks Time liner software. Narges shopping center is presented as a case study to realize the actual uses and benefits of Building Information Model (BIM). Narges shopping mall is located in Tehran, Iran. As a part of Hekmat master plan, Narges shopping center is an 11 stores building with a total area of 30000 Sq.m. This shopping and entertainment center is comprised of 150 retails and two multi-use public halls with a capacity of 400 persons each and underground parking with total 400 parking space. The main purpose of architecture was to create an urban public center along with its revolving, spiral like form and an ever changing continuous façade by means of different colors, materials, which is in harmony with the other building of the master plan. The approximate cost of the project is $17 million and duration of the project schedule is 30 months. The developed Building Information Model enabled us to identify the potential collisions or clashes between various structural and architectural systems. 4D model has been used for limiting the interaction between subcontractors installing the different systems so rework could be avoided and productivity maximized. It is also observed that the utility of BIM for construction stimulation and clash detection is the best suitable method. Clash detection before the implementation of work is highly recommended to avoid rework.

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Analysis of Electrical Characteristics due to Deep Level Defects in 4H-SiC PiN Diodes (4H-SiC PiN 다이오드의 깊은 준위 결함에 따른 전기적 특성 분석)

  • Tae-Hee Lee;Se-Rim Park;Ye-Jin Kim;Seung-Hyun Park;Il Ryong Kim;Min Kyu Kim;Byeong Cheol Lim;Sang-Mo Koo
    • Korean Journal of Materials Research
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    • v.34 no.2
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    • pp.111-115
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    • 2024
  • Silicon carbide (SiC) has emerged as a promising material for next-generation power semiconductor materials, due to its high thermal conductivity and high critical electric field (~3 MV/cm) with a wide bandgap of 3.3 eV. This permits SiC devices to operate at lower on-resistance and higher breakdown voltage. However, to improve device performance, advanced research is still needed to reduce point defects in the SiC epitaxial layer. This work investigated the electrical characteristics and defect properties using DLTS analysis. Four deep level defects generated by the implantation process and during epitaxial layer growth were detected. Trap parameters such as energy level, capture-cross section, trap density were obtained from an Arrhenius plot. To investigate the impact of defects on the device, a 2D TCAD simulation was conducted using the same device structure, and the extracted defect parameters were added to confirm electrical characteristics. The degradation of device performance such as an increase in on-resistance by adding trap parameters was confirmed.

Design and simulation of 500 MHz single cell superconducting RF cavity for SILF

  • Yanbing Sun;Wei Ma;Nan Yuan;Yulin Ge;Zhen Yang;Liping Zou;Liang Lu
    • Nuclear Engineering and Technology
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    • v.56 no.1
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    • pp.195-206
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    • 2024
  • Shenzhen Innovation Light source Facility (SILF) is a 3.0 GeV fourth generation diffraction limited synchrotron light source currently under construction in Shenzhen. The SILF storage ring is proposed to use two 500 MHz single cell superconducting radio frequency (SRF) cavities to provide 2.4 MV RF voltage. In this study, we examined the geometric structure of mature CESR superconducting cavities and adopted a beam-pipe-type extraction scheme for high-order modes (HOM). One of the objectives of SRF cavity design and optimization in this study is to reduce Ep/Eacc and Bp/Eacc as much as possible to reduce power loss and ensure stable operation of the cavity. To reduce the risk of beam instability and thermal breakdown, the HOM and Multipacting (MP) are simulated. Moreover, the mechanical properties of the cavity are analyzed, including frequency sensitivity from pressure of liquid helium (LHe), stress, tuning, Lorentz force detuning (LFD), the microphone effect, and buckling. By comprehensive design and optimization of 500 MHz single-cell SRF cavities, a superconducting cavity for SILF storage ring was developed. This paper will detailed present the design and simulation.

1985년 인구 및 주택센서스 확정결과보고

  • 경제기
    • Korea journal of population studies
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    • v.10 no.2
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    • pp.99-145
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    • 1987
  • Change in the future household members is closely related to the change in the size and structure of the population which, in turn, is affected by factors of fertility and mortality and the household itself due to changing social values on family. This study aims to estimate the number of households and to thereby analyze the characteristics of household, using a household projection method chosen by reviewing various methods for Korea. In selecting the method of estimating households, the irregularity of the source data should be carefully taken into consideration with a society like the Korean society which is changing rapidly. The review on the proojection methods suggests the breakdown of the ages into two groups, namely 34 years old or less and 35 years old or more, for projecting the households for Korea. Thus, the Exponential Method for the former age group and the Net Transitional Method for the latter are adopted in this study. As a result, the number of households is expected to increase from 12,956 thousand in 1995 to 20,006 thousand in 2030 or by 54% during this period. The average number of members per household will decrease from 3.3 persons in 1995 to 2.5 persons in 2030. One of the main features of change in the housohold structure will be a rapid increase in the number of one person households and a decrease in the number of households with three generations or more.

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Rheological Behavior of Semi-Solid Ointment Base (Vaseline) in Steady Shear Flow Fields (정상전단유동장에서 반고형 연고기제(바셀린)의 레올로지 거동)

  • Song, Ki-Won;Kim, Yoon-Jeong;Lee, Chi-Ho
    • Journal of Pharmaceutical Investigation
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    • v.37 no.3
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    • pp.137-148
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    • 2007
  • Using a strain-controlled rheometer [Rheometrics Dynamic Analyzer (RDA II)], the steady shear flow properties of a semi-solid ointment base (vaseline) have been measured over a wide range of shear rates at temperature range of $25{\sim}60^{\circ}C$. In this article, the steady shear flow properties (shear stress, steady shear viscosity and yield stress) were reported from the experimentally obtained data and the effects of shear rate as well as temperature on these properties were discussed in detail. In addition, several inelastic-viscoplastic flow models including a yield stress parameter were employed to make a quantitative evaluation of the steady shear flow behavior, and then the applicability of these models was examined by calculating the various material parameters (yield stress, consistency index and flow behavior index). Main findings obtained from this study can be summarized as follows : (1) At temperature range lower than $40^{\circ}C$, vaseline is regarded as a viscoplastic material having a finite magnitude of yield stress and its flow behavior beyond a yield stress shows a shear-thinning (or pseudo-plastic) feature, indicating a decrease in steady shear viscosity as an increase in shear rate. At this temperature range, the flow curve of vaseline has two inflection points and the first inflection point occurring at relatively lower shear rate corresponds to a static yield stress. The static yield stress of vaseline is decreased with increasing temperature and takes place at a lower shear rate, due to a progressive breakdown of three dimensional network structure. (2) At temperature range higher than $45^{\circ}C$, vaseline becomes a viscous liquid with no yield stress and its flow character exhibits a Newtonian behavior, demonstrating a constant steady shear viscosity regardless of an increase in shear rate. With increasing temperature, vaseline begins to show a Newtonian behavior at a lower shear rate range, indicating that the microcrystalline structure is completely destroyed due to a synergic effect of high temperature and shear deformation. (3) Over a whole range of temperatures tested, the Herschel-Bulkley, Mizrahi-Berk, and Heinz-Casson models are all applicable and have an almostly equivalent ability to quantitatively describe the steady shear flow behavior of vaseline, whereas the Bingham, Casson,and Vocadlo models do not give a good ability.

The Experience of Parents Whose Child is Dying with Cancer (암 환아 부모의 경험에 대한 질적 연구)

  • ;;Ida Martinson
    • Journal of Korean Academy of Nursing
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    • v.22 no.4
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    • pp.491-505
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    • 1992
  • The purpose of this research was to understand the structure of the lived experience of parents of a child terminally ill with cancer The research question was “What is the structure of the experience of parents of a child terminally ill with cancer\ulcorner” The sample consisted of 17 parents of children admitted to the cancer units of two university hospitals in Seoul. The unstructured interviews were carried out from October 10, 1991 through January 10, 1992. They were audio-recorded and analysed using Van Kaam's method. Parents ascribed the cause of the cancer to the mother's emotional imbalance during pregnancy, the mother's stress, failure to observe religious rites, food, the parent's sin, misfortune and pollution. The theme clusters were tension, fear and depression experienced during pregnancy, stress that children suffer from abusive parents, failure to observe religious activites, bad luck, and sins committed during a previous life. When the child suffered a recurrence of cancer, the parents experienced negative emotions, nervousness, sorrow. depression and death. The theme clusters were feelings of despair, helplessness, regret, guilt, insecurity, emptyness and apathy. The long struggle with cancer resulted in the loss of economic security, loss of psychological and physical well being, and social withdrawal. The theme clusters were the economic burden of medical cost, giving up treatment, debt, limited medical insurance coverage and blood transfusion. The loss of psychological well being included stress, lack of support systems, inability to carry out responsibilities, lack of trust of the medical ten family breakdown, inappropriate expression of emotion and not disclosing the diagnosis to the child. Physically the parents suffered fatigue, insomnia, loss of appetite, loss of weight, dizzness, headache, psychosomatic symptoms, and increased consumption of liquor and cigarettes. Social withdrawal was manifested by taking time off from work to look after the child, decrease of outside social activities and feelings of isolation. Influences on family life were spousal conflicts, negative response of siblings, separation of the family members and economic hardship. The theme clusters were blaming a spouse for the cause of the illness and disagreements, maladjustment, lonliness, hostility and depression of siblings. The high price of medical care over the long period was a major factor influencing the life of the family. Positive experiences during the child's long illness were the strengthening of support systems and religious beliefs and financial help from social organizations. The support of one's spouse primarily helped to overcome the stress of the long illness. In addition, support was received from parents of other children with cancer and from nurses and religious leaders. The nurse, by providing empathetic support, should be a person with whom parents can express their feelings and share their experiences.

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Characteristics of $Ta_{2}O_{5}$ Films by RF Reactive Sputtering (RF 반응성 스펏터링으로 제조한 $Ta_{2}O_{5}$ 막의 특성)

  • Park, Wug-Dong;Keum, Dong-Yeal;Kim, Ki-Wan;Choi, Kyu-Man
    • Journal of Sensor Science and Technology
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    • v.1 no.2
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    • pp.173-181
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    • 1992
  • Tantalum pentoxide($Ta_{2}O_{5}$) thin films on p-type (100) silicon wafer were fabricated by RF reactive sputtering. Physical properties and structure of the specimens were examined by XRD and AES. From the C-V analysis, the dielectric constant of $Ta_{2}O_{5}$ films was in the range of 10-12 in the reactive gas atmosphere in which 10% of oxygen gas is mixed. The ratio of Ta : 0 was 1 : 2 and 1 : 2.49 by AES and RBS examination, respectively. The heat-treatment at $700^{\circ}C$ in $O_{2}$ ambient led to induce crystallization. When the heat-treatment temperature was $1000^{\circ}C$, the dielectric constant was 20.5 in $O_{2}$ ambient and 23 in $N_{2}$ ambient, respectively. The crystal structure of $Ta_{2}O_{5}$ film was pseudo hexagonal of ${\delta}-Ta_{2}O_{5}$. The flat band voltage shift(${\Delta}V_{FB}$) of the specimens and the leakage current density were decreased for higher oxygen mixing ratio. The maximum breakdown field was 2.4MV/cm at the oxygen mixing ratio of 10%. The $Ta_{2}O_{5}$ films will be applicable to hydrogen ion sensitive film and gate oxide material for memory device.

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An Analytical Study on Crack Behavior Inside Standard Compact Tension Specimen with Holes (구멍들을 가진 표준 CT 시험편 내에서의 크랙 거동에 대한 해석적 연구)

  • Lee, Jung Ho;Cho, Jae Ung
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.40 no.6
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    • pp.531-537
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    • 2016
  • The damage and fracture of machine or structure are caused by the crack happened from the defect existed at the inside of material. The properties of crack propagation and growth characteristic must be considered because there are many cases at which these cracks are densely existed. Therefore, this study investigates the fracture property due to the position of crack and hole inside the standard compact tension (C. T.) specimen. When the concentrated load is applied eccentrically at the standard C. T. specimen, the fracture mechanical behavior due to the existence or non-existence and the position of hole near crack is investigated. As the result of analysis study, model 3 (in case of the distance of 2mm on the horizontal direction between the end part and hole as the specimen model existed with one hole near the crack) has the maximum deformation, stress and deformation energy of the most values among three models. As the distance between the crack and hole inside the specimen becomes nearer, the maximum stress becomes higher in cases of three models. Apart from the number of holes, it is seen that the maximum stress becomes higher near the crack when the hole exists near the crack inside the specimen. If the hole inside the machine or the mechanical structure is punctured by using the result of this study, it is thought that the occurred breakage or breakdown can be prevented by reducing the fracture stress happened at the specimen.

Development of Household Projection Model and Its Application for Korea (우리 나라에 적합한 가구추계방법에 관한 연구)

  • 장영식;변용찬;김유경
    • Korea journal of population studies
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    • v.21 no.1
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    • pp.129-161
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    • 1998
  • Change in the future household members is closely related to the change in the size and structure of the population which, in turn, is affected by factors of fertility and mortality and the household itself due to changing social values on family. This study aims to estimate the number of households and to thereby analyze the characteristics of household, using a household projection method chosen by reviewing various methods for Korea. In selecting the method of estimating households, the irregularity of the source data should be carefully taken into consideration with a society like the Korean society which is changing rapidly. The review on the proojection methods suggests the breakdown of the ages into two groups, namely 34 years old or less and 35 years old or more, for projecting the households for Korea. Thus, the Exponential Method for the former age group and the Net Transitional Method for the latter are adopted in this study. As a result, the number of households is expected to increase from 12,956 thousand in 1995 to 20,006 thousand in 2030 or by 54% during this period. The average number of members per household will decrease from 3.3 persons in 1995 to 2.5 persons in 2030. One of the main features of change in the housohold structure will be a rapid increase in the number of one person households and a decrease in the number of households with three generations or more.

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