• 한국수자원학회논문집
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• 제44권2호
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• pp.157-167
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• 2011

본 연구에서는 복단면개수로및 불규칙한 하상을보이는 횡단면 상에서의 수위-유량곡선 및단위유량횡분포예측을 위한 유한요소모형을 개발하였다. 지배방정식은 정상류와 종방향 등류를 가정한 운동량방정식을 이용하며, 수면은 횡단면에 걸쳐 일정하다고 가정한다. 홍수터 식생의 영향을 반영하기 위해 식생항력이 지배방정식에 포함되었으며, 수치해를 구하기 위해 유한요소법을 적용하였다. 단면형상과 Manning의 조도계수, 식생정보, 종방향 하상경사를 입력자료로 수위-유량 곡선을 예측 가능하며, 주어진 수위에서의 흐름방향 단위유량의 횡방향 분포를 예측할 수 있다. 개발된 모형의 검증을 위해 실측자료 및 Darby and Thorne (1996)의 모형 결과, 그리고 비선형 k-$\epsilon$ 모형의 결과와도 비교하였다. 검증된 모형의 알고리즘을 2차원 모형의 상류단 경계조건 설정에 활용하여, 유입유량을 절점별 단위유량으로 분배시켰을 때와 그렇지 않았을 때의 결과를 비교하였다.

• 한국방재학회:학술대회논문집
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• 한국방재학회 2007년도 정기총회 및 학술발표대회
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• pp.195-198
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• 2007

The type, the length, and the install space of the grate inlets in main street were designed with the consideration of discharge calculated with street surface rainfall. However, the discharge that was not intercepted at transverse grate inlets in steep local roads increases inundation areas around main street Therefore, it is necessary to analyze the flow characteristics and interception capacity at transverse grate inlets in steep local roads. Hydraulic experimental apparatus which can be changed the longitudinal slopes($2{\sim}10%$) of street, the size ($20{\sim}50cm$) and the types(TYPE I, II) of grate inlet was installed for this study. The range of the experimental discharges were from $2{\ell}/sec$ to $24{\ell}/sec$. The interception discharges of transverse grate inlets per unit width changing the longitudinal slope of steep local road were calculated by the hydraulic experimental results. The design method of transverse grate inlets was developed by the interception discharges per unit width. This design method was applied to decide the space and size of transverse grate inlets.

• 한국수자원학회논문집
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• 제36권3호
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• pp.465-480
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• 2003

본 연구에서는 도로의 측구 부분을 수리모형으로 제작하여 빗물받이의 차집능력을 검토하였다. 측구의 유량은 도로의 차선(2-4차선) 및 빗물받이 간격(10-30m)을 고려하여 4-15l/sec의 유량을 사용하였고, 도로의 종방향 경사는 0, 2, 5, 7%를 선택하였으며, 측구의 횡경사는 4, 7, 10%를 사용하였다. 유입부의 규모는 $30\times40cm,\;40\times50cm,\;40\times100cm,\;40\times150cm$의 4종류를 사용하였으며, 총 실험 횟수는 240회이다. 측구의 횡경사가 클수록 전체적인 빗물받이의 차집유량은 증가하였다. 차집효율은 흐름폭과 유량이 작을 수록 증가하였고, 종방향 경사가 급할 수록 감소함을 알 수 있었다. 실험의 결과로부터 유입부 규모에 따른 차집유량을 계산할 수 있는 경험식을 제시하였다. 도로의 차선별, 종경사별, 측구의 횡경사별, 유입부 규모별로 적정 빗물받이 간격을 제시할 수 있어서 도로의 빗물받이 설계에 기초자료를 제공하였다.

• 한국정밀공학회지
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• 제21권10호
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• pp.42-49
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• 2004

Electrical discharge machining (EDM) is one of the most extensively used non-conventional material removal process. The recent trend in reducing the size of product has given micro EDM a significant amount of research attention. Micro EDM is capable of machining not only micro holes and micro shafts as small as a few micrometers in diameter but also complex three dimensional micro cavities. But, longitudinal tool wear by electrical discharge is indispensable and this affects the machining accuracy in micro EDM process. Therefore, newly developed tool wear compensation strategy called round trip method is suggested and verified by experiment. In this method, machining depth of cut, overlap effect and critical travel length are also considered.

• 한국가시화정보학회지
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• 제21권1호
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• pp.57-66
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• 2023

In this study, we investigate the effects of a single roughness element on Venturi cavitation. The single roughness element of hemispherical shape is installed at the throat inlet of a Venturi tube. Since the wake behind the roughness element induces an additional pressure drop, cavitation inception occurs at a higher Cavitation number for the Venturi model with the single roughness element than for the Venturi model with no roughness. Cavitation bubbles form along the wake of the roughness element and lengthen in the streamwise direction as the Cavitation number decreases, forming a longitudinal cavitation. With a further decrease in the Cavitation number, the longitudinal cavitation bubble merges with the sheet cavitation initiated from the exit edge of the Venturi tube throat, followed by the shedding of cloud cavitation. The merging of the longitudinal cavitation and sheet cavitation is accompanied by a sudden decrease in the discharge coefficient and an increase in the pressure loss coefficient as it chokes the flow inside the Venturi tube.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.1582-1583
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• 2011

Recently, it has been found that trifluoroiodomethane ( $CF_3I$) gas can replace $SF_6$ gas as a prospective substitute gas. For quantitative understanding of gas discharge phenomena, we should know electron collision cross sections and electron transport coefficients. Using electron collision cross sections of $CF_3I$ and Xe, we calculated elecron drift velocity, longitudinal coefficient, effective ionization coefficient in $CF_3I$-Xe mixtures using a two-term approximation of the Boltzmann equation. We also compared the electron transport coefficients in pure gas and those of 10%, 20%, 50%, and 70% $CF_3I$-Xe mixture gases. The present data may be showed appropriate ratios of $CF_3I$-Xe mixture gas for replacing the $SF_6$ gas.

• 물과 미래
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• 제16권4호
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• pp.237-243
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• 1983

본 연구는 수리모형 실험을 통하여 지류로부터 유입 된 오염원이 합류후에 여하히 의석확산하는 가에 대하여 규명하였다. 본류와 지류의 유량을 변화시키면서 정성적인 확산경향, 유황, 유속, 수리적인 특성을 관찰하였다. 희석확산의 결과는 오염원으로부터의 거리 및 오염의 진행시간에도 많은 영향을 받으나 무엇보다도 그 지점의 유체의 유속이 빠를수록 그리고 유량비가 클수록 오염물질의 희석확산의 효과는 크게 나타났다. 또한, 유속이 커질수록 종방향의 확산속도는 상대적으로 증가하고 횡방향의 확산속도는 감소된다. 이는 속도 분포에 의한 확산이 커지기 때문인 것으로 사료된다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.1481_1482
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• 2009

Pure Xe, Kr and Ne atoms and Mixures of Xe-Ne used in fluorescent induction lamps(FILs). However standard regulation of FILs is not made up until now. Therefore, the electron transport coefficients, the electron drift velocity W, the longitudinal diffusion coefficient NDL and the ionization coefficient $\alpha$/N in pure Xe, Kr, Ne gases and Xe-Ne mixtures(1:9, 5:5, 7:3) were calculated over the wide E/N range from 0.01 to 500 Td at 1 Torr by two-term approximation of the Boltzman equation.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2008년도 제34회 동계학술대회 초록집
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• pp.207-207
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• 2008

• 중환자간호학회지
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• 제12권1호
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• pp.22-35
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• 2019

Purpose : This study was to determine the levels of environmental stressor, posttraumatic stress disorder, and quality of life in intensive care units (ICU) survivors after intensive care, and to explore the factors affecting posttraumatic stress disorder and quality of life. Methods: With a longitudinal survey design, data were collected from 116 patients who were discharged from the ICU of a university hospital. The environmental stressor, posttraumatic stress disorder, and quality of life were measured immediately following and 1 month after the ICU discharge. Results: Of all the subjects, 16.4% experienced posttraumatic stress disorder after discharge. Multiple regression analysis revealed that ICU environmental stressors, experience of ICU readmission, using psychotropic drugs and narcotic analgesics, and ICU admission after surgery or cardiac intervention accounted for 22.2% of posttraumatic stress disorder. Posttraumatic stress disorder and sedation status when entering ICU accounted for 28.3% of the quality of life 1 month after ICU discharge. Conclusion: Nursing interventions focused on ICU environmental stressors would not only reduce environmental stress but also contribute to the reduction of posttraumatic stress disorder and later improvement of quality of life.