• Title/Summary/Keyword: Non-Eroding

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Erosion Characteristics of Kaolinite with respect to Contents of Silt (실트함량에 따른 카올리나이트의 침식특성 평가)

  • Lee, Ju-Hyung;Park, Jae-Hyun;Chung, Mun-Kyung;Kwak, Ki-Seok
    • 한국방재학회:학술대회논문집
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    • 2008.02a
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    • pp.593-596
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    • 2008
  • The scour phenomenon involves the erosive potential of flowing water and the relative ability of the soil to resist erosion. The scour phenomenon in cohesive soils is much different from that in non-cohesive soils. Granular soils resist erosion by their buoyant weight and the friction between the particles. The soil particles are dislodged individually from the bed under the action of the eroding fluid. Scour in cohesive soils is much slower and more dependent on soil properties than that in non-cohesive soils. Therefore the analysis models for estimating erosion characteristics of cohesive soils should consider not only flowing water but also the relative ability of the soil to resist erosion. In this study, erosion characteristics for the clay-silt mixed soil will be analyzed as a fundamental study for development of bridge scour analysis and design system considering scour resistance capacity of a soil. For this analysis, the relationship between scour characteristics and soil properties was evaluated through scour rate test with Kaolinite samples remolded using various loading and contents of silt.

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Difficulties in Caring for Psychiatric Patient as Experienced by Non-Psychiatric Nurses (비정신과 간호사가 경험한 정신질환자 간호의 어려움)

  • Joung, Jaewon;Jang, Mi Young;Shim, Jihyun;Ko, Yoonhi;Shin, Sung Hee
    • Journal of Korean Academy of Nursing
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    • v.47 no.1
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    • pp.49-59
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    • 2017
  • Purpose: The purpose of this study was to identify non-psychiatric nurses' difficulties in caring for patients with mental illness. Methods: Data were collected from eighteen general medical-surgical nurses working at a university hospital in Seoul, Korea. This study involved two focus group discussions and three in-depth individual interviews. All interviews were recorded and transcribed as they were spoken, and data were analyzed using qualitative content analysis. Results: General medical-surgical nurses experienced difficulties in 3 categories, 9 subcategories, 27 codes. The three categories were 'nurse' related factors, 'patient' related factors, 'resource' related factors. The nine categories were 'unpreparedness', 'nursing barriers due to stigma', 'undervaluing and avoidance of psychiatric nursing', 'eroding into the trap of a vicious cycle', 'facing unapproachable patients', 'dealing with unhelpful family members', 'burdening already overburdened staff', 'obstructive environment', and 'isolation of staff with heavy responsibilities'. Conclusion: The results of this study indicate the need to develop psychiatric mental health education programs for non-psychiatric nurses. Education about psychiatric mental health and support from institutions for non-psychiatric nurses can reduce their negative attitude toward psychiatric patients and difficulties in caring for psychiatric patients.

Thermal Performance Evaluations of Tungsten/Yttria as Nozzle Throat Insert Material for Long Duration Firing (장시간 연소 텅스텐/이트리아 노즐목 삽입재의 내열성능 평가)

  • Kang, Yoon-Goo;Park, Jong-Ho
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.38 no.2
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    • pp.200-205
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    • 2010
  • Heat-resistance of W/$Y_2O_3$ as throat insert material was evaluated to develop rocket motor keeping thrust uniformly under condition of high-temperature, high-pressure and long-burn time. Test was conducted with varying burn time, and test results were compared with CIT. Test showed that ablation rate was decreased according as burn time was increased, and that ablation rate of W/$Y_2O_3$ was about 55 % of CIT. Macro/micro structures of throat insert did not show a peculiar phenomenon by increased burn time. In addition, the vacuum heat treatment is effective for the prevention of crack in throat insert.

Thermal Performance Evaluations on High-Erosion Resistance Materials for Very Small Nozzle Throat Inserts (장시간 연소용 초소형 저삭마 목삽입재 선정을 위한 내열성능 평가)

  • Kang, Yoon-Goo;Park, Jong-Ho
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.37 no.12
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    • pp.1245-1251
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    • 2009
  • This paper describes the research on the non-eroding throat insert materials under condition of high-temperature, high-pressure, and long-burn time. C/SiC, CIT and W/$Y_2O_3$ were chosen and tested in thermal protection evaluation motor of burning time 20 seconds. From the test results, a heat resistance of W/$Y_2O_3$ was the most excellent among them, but was happened crack on material surface. Thermal reaction characteristics and heat resistance of these materials and feasibility of W/$Y_2O_3$ as throat material were ascertained.

High Velocity Impact Analysis of Kevlar29/Phenolic Composite Plate (케블라 복합재 평판의 고속충돌 특성 수치해석)

  • Ahn, Jeoung-Hee;Kweon, Jin-Hwe;Choi, Jin-Ho
    • Composites Research
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    • v.22 no.2
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    • pp.18-23
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    • 2009
  • Failure of Kevlar29/Phenolic composite plate under high velocity impact of FSP(Fragment Simulation Projectile) is investigated using a non-linear explicit finite element code, LS-DYNA. Composite laminate and impactor are idealized by solid element and interface between laminas are modeled by tied-break element in LS-DYNA. Interaction between impactor and laminate is simulated face-to-face eroding contact algorithm. When the stress level meets a failure criteria, the layer in the element is eroded. Numerical results are verified by existing test results.

The Impact of Disclosure Quality on Crash Risk: Focusing on Unfaithful Disclosure Firms (공시품질이 주가급락에 미치는 영향: 불성실공시 지정기업을 대상으로)

  • RYU, Hae-Young
    • The Journal of Industrial Distribution & Business
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    • v.10 no.6
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    • pp.51-58
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    • 2019
  • Purpose - Prior studies reported that the opacity of information caused stock price crash. If managers fail to disclose unfavorable information about the firm over a long period of time, the stock price is overvalued compared to its original value. If the accumulated information reaches a critical point and spreads quickly to the market, the stock price plunges. Information management by management's disclosure policy can cause information uncertainty, which will lead to a plunge in stock prices in the future. Thus, this study aims at examining the impact of disclosure quality on crash risk by focusing on the unfaithful disclosure firms. Research design, data, and methodology - This study covers firms listed on KOSPI and KOSDAQ from 2004 to 2013. Firms excluded from the sample are non-December firms, capital-eroding firms, and financial firms. The financial data used in the research was extracted from the KIS-Value and TS2000 database. Unfaithful disclosure firm designation data was collected from the Korea Exchange's electronic disclosure system (kind.krx.co.kr). Stock crash is measured as a dummy variable that equals one if a firm experiences at least one crash week over the fiscal year, and zero otherwise. Results - Empirical results as to the relation between unfaithful disclosure corporation designation and stock price crashes are as follows: There was a significant positive association between unfaithful disclosure corporation designation and stock price crash. This result supports the hypothesis that firms that have previously exhibited unfaithful disclosure behavior are more likely to suffer stock price plunges due to information asymmetry. Second, stock price crashes due to unfaithful disclosures are more likely to occur in Chaebol firms. Conclusions - While previous studies used estimates as a proxy for information opacity, this study used an objective measure such as unfaithful disclosure corporation designation. The designation by Korea Exchange is an objective evidence that the firm attempted to conceal and distort information in the previous year. The results of this study suggest that capital market investors need to investigate firms' disclosure behaviors.

Dynamic Characteristics of Multiple Bars in the Channels with Erodible Banks (하안침식을 고려한 복렬사주의 동적 거동 특성 분석)

  • Jang, Chang-Lae
    • Journal of Korea Water Resources Association
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    • v.46 no.1
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    • pp.25-34
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    • 2013
  • In this study, the development processes of multiple bars in the channels with erodible banks were investigated by double Fourier analysis. The initially straight channels in the experiment flume were widened with eroding the side banks, and the multiple bars were generated and grew due to stalling of the sediment on the bed. The bars migrated downstream and the size of the bars increased with time. The flow was separated around the bars, and the bed and banks near the bars were scoured due to the impinged secondary flow. The morphologic changes were accelerated by the bank erosion, which affected the fluctuations of sediment discharge downstream. The double Fourier analysis of the bed waves showed that 1-1 mode (alternate bar) was dominant at the initial stage of the channel development. As time increased, 2-3 mode (central or multiple bars) was dominant due to the increased width to depth ratio. Moreover, the number of bars in a cross section of the channel were increased due to the non linearity of alternate bars. The width to depth ratio was increased by the bank erosion, which affected the bar migration and the bar wavelength. However, the dimensionless tractive force was decreased by it.