• 한국농공학회지
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• 제14권1호
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• pp.2503-2519
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• 1972

The studies were carried out to find the cause and the quantitative evaluation of sea dike materials loss which is occured during the period of construction works for the tideland reclamation projects on the west coast of Korea. Major subjects to studies were to establish the typical relationships between the tidal flow and the movement of dike materials, the tidal-flow and the erosion, the dike materials and the ratio of material movement(losses), construction methods and the ratio of materials movement (losses). Based on the above subjects, the studies were made for the purpose of obtain the following informations; (1) Collecting and evaluaing the data of dike material losses due to foundation settlement, from designed existing dikes on the west coast. (2) By the field investigation at A-San Sea Dike, Pyong Taek Project, the Comparison would be made by the relationships between the tide velocity and the movement of dike foundation under the natural conditions and the period of construction so that find out the relationship between the dike materials of foundation situation and settlements. With regard to the dike construction works, it is so difficult to calculate the exact quantity of material losses due to the foundation settlements. The major factors that affect the settlement losses of the dike materials are: (1) Topographical variation (2) Swepting the sectional area of dike by the tide velocity. (3) Dumping riprap to the outerside of dike during the period of construction works. (4) Sectional area losses by the cause of occurence of the new tide channels. (5) material losses by the heavy storms. (6) Consolidation settlement by the foundation weakness. (7) Material losses by the earth materials by tide flow. Most hi호 material losses were occured by the Consolidation settlement due to the foundation weakness, the maximum tide velocities due to decrease the cross sectional area of the gaps and erosion of foundation due to the range of tide, Inner and outerside of dike, or dike material loses due to the tide flow. Final conclusion would be obtained by the continuous measurement of consolidation settlement at the stage of final clusure of the dike. (It is scheduled to close on the end of 1972) However, intermediate conclusion can be introduced as follows: (1) The estimation of material(losses) during the period of construction works for the existing sea-dikes up to date were only empirical. The material losses at the general closure for design was estimated at 10% of the riprap, 20% of the earth materials, and 20% of the riprap, 40% of the earth materials at the final closure of the dike. The final closure estimated double quantity to the general closure, but it is still doubt. (2) The ratio of consolidation settlements was found smaller than the calculated quantity. It can be foreseen that settlement speeds is higher thom the calculated speeds. (3) The movement of dike foundation under the natural conditions were not so depends on the geological conditions of the foundation. (4) When the tide velocities was estimated 100 at the normal tide, it was estimated 125 at the high tide and 55 at the low tide. The tide velocities at the low tide shows apparently lower than the high tide and the higher velocities at the deep water depth.

• 한국안전학회지
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• 제15권4호
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• pp.119-122
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• 2000

The truss bridge is composed of numerous steel beams. In long span bridges the size of beams is getting larger, so the number of plate girders is increasing instead of rolled beams. This plate girder has long welding lines at the intersection of steel plates. The improper welding at the intersection line causes the steel bridge to be structurally unsafe. In this paper the loss of member section from improper welding was measured and the experimental testing was performed to get the S-N curve from testing models with sectional losses. The improper welding resulted in the lowering of structural safety and the shortening of life cycle.

• 한국방재학회:학술대회논문집
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• 한국방재학회 2008년도 정기총회 및 학술발표대회
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• pp.401-404
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• 2008

The vegetation in the surrounding area of river is a primary factor to increase water level during flood. The influence of vegetation on the river flow in a bank has been investigated by using a hydraulic experiment. For a hydraulic experiment square-shaped piers are used as a model of unsubmerged rigid vegetation in a open channel. For fully developed uniform flows, the water elevation of the experiment was measured as varying the interval of piers and the porosity which presents the fraction of water flowing area in the cross-sectional area. The Manning's roughness coefficient, which implicates energy losses due to the vegetation, was obtained by using the experimental data. As a result, the energy losses were varied when the distance of piers and the porosity of area were changed, and the Manning's coefficient increased nonlinearly when a water elevation increased.

• 대한기계학회논문집B
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• 제27권10호
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• pp.1412-1419
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• 2003

Heat regenerator occupied by regenerative materials improves thermal efficiency of combustion system through the recovery of sensible heat of exhaust gases. By using one-dimensional two-phase fluid dynamics model, the unsteady thermal flow of regenerator with spherical particles, was numerically analyzed to evaluate the heat transfer and pressure losses and to derive the design parameter for heat regenerator. It is confirmed that the computational results, such as air preheat temperature, exhausted gases outlet temperature, and pressure losses, agreed well with the experimental data. The thermal flow in heat regenerator varies with porosity, configuration of regenerator and diameter of regenerative particle. As the gas velocity increases with decreasing the cross-sectional area of the regenerator, the heat transfer between gas and particle enhances and pressure losses decrease. As particle diameter decreases, the air is preheated higher and the exhaust gases are cooled lower with the increase of pressure losses. Assuming a given exhaust gases temperature at the regenerator outlet, the regenerator need to be linearly lengthened with inlet Reynolds number of exhaust gases, which is defined as a regenerator design parameter.

• 디지털융복합연구
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• 제16권11호
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• pp.267-274
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• 2018

본 연구는 경영자능력이 한국채택국제회계기준 도입 이후 영업권손상차손 인식에 있어서 경영자의 기회주의적인 재량적 재무보고에 대하여 어떤 영향을 미치는 가를 실증적으로 분석하였다. 2011년~2014년 사이에 영업권을 인식한 1,482개 기업-년 표본을 대상으로, 영업권손상차손을 종속변수로, 영업권손상징후와 경영자능력, 이익조정 관련 변수들을 독립변수로 포함하여 회귀분석을 수행하였다. 분석결과, 경영자능력이 높은 경우, 손상징후에 따라 영업권손상차손이 보다 적절히 인식되고 있으며, 손상차손을 이익유연화 수단으로 이용되는 정도가 감소하였다. 본 연구는 영업권손상차손의 인식에 있어서 경영자의 기회주의적인 재무보고 성향이 경영자능력에 따라 달라질 수 있음을 보여주는 첫 번째 실증분석으로 연구의 유용성이 있으며, 향후에는 경영자능력이나, 영업권손상 징후, 그리고 이익조정 측정방법에 대한 보다 심층적인 연구를 통해 본 연구의 결과를 다양한 연구주제로 확장시킬 수 있을 것이다.

• 한국산학기술학회논문지
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• 제16권6호
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• pp.3722-3730
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• 2015

하수 처리용으로 사용되는 소형 원심 압축기의 베인 없는 디퓨져와 볼류트 케이싱의 성능 개선을 수행하였다. 기존의 두 모델은 임펠러가 동일하나, 베인 없는 디퓨져의 폭과 길이 및 볼류트 케이싱의 형상은 서로 다르다. 기존 모델에 대한 실험과 유동해석 결과를 바탕으로 베인 없는 디퓨져와 볼류트 케이싱의 설계를 변경하였다. 세 모델에 대한 연구 결과로부터, 볼류트 케이싱의 단면적 및 입구 반경 길이는 볼류트 혀와 베인 없는 디퓨져 및 임펠러와의 상호작용 강도에 영향을 주었고, 시스템 손실량에 변화를 나타내었다. 베인 없는 디퓨져 폭이 감소하면 임펠러의 효율은 증가했지만 디퓨져에서의 손실도 증가하였다. 결과적으로 개선된 모델의 효율이 설계 점에서 기존 대비 약 2.88%p 향상된 것이 유동해석 결과로 확인되었다.

• 동력기계공학회지
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• 제21권1호
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• pp.70-79
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• 2017

The output power of turbine is greatly affected by the losses generated within the passage. In order to develop a better turbine or loss models, an experimental study was conducted using a linear cascade experimental apparatus. The total pressure loss and flow structures were measured at two cross-sectional planes located downstream of blade row. Measurement was conducted in a steady state for the several different locations of the blade row along the rotational direction. The blade row moved by 20 % of the pitch, and tip clearance was varied from 2% to 8%. Axial-type blades were used and its blade chord was 200mm. A square nozzle was applied and its size was $200mm{\times}200mm$. The experiment was conducted at a Reynolds number of $3{\times}10^5$ based on the chord. Nozzle flow angle sets to $65^{\circ}$ based on the axial direction and the solidity of blade row was 1.38. From the experimental results, the total pressure loss was greatly varied in the receding region than in the entering region. The flow properties within the blade passage were strongly changed according to the location of blade row.

• The Journal of Asian Finance, Economics and Business
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• 제8권10호
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• pp.207-218
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• 2021

The present research intends to examine the herding aspect during the COVID-19 outbreak. The study is conducted to achieve specific objectives, so the underlying sampling technique is purposive sampling. The considered data source is the Pakistan Stock Exchange (PSX). Daily stock prices of 528 listed companies in PSX have been taken from the official website of PSX from 1998 to 2021. The current study envisions investigating the herding aspects for pre-pandemic and the time covering the pandemic period. The study has also targeted ten sectors of PSX. The present study's motive is to investigate investors' herding prospects before and during the pandemic in the Pakistan Stock Exchange (PSX) and its selected sectors. Daily closing stock prices of listed companies have been collected from the official website of PSX to calculate the stock returns. The Cross-Sectional Absolute Deviation (CSAD) has been used as a herding measure. Findings revealed that herding has not been observed in PSX during both time spans and even not during the bullish and bearish trends. However, robust sectoral evidence has been observed during the pandemic. It implies that investors in PSX tend to follow the crowd irrespective of making their own decisions to avoid further losses.

• 대한토목학회논문집
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• 제28권1A호
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• pp.15-24
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• 2008

본 논문에서는 프리캐스트 바닥판을 사용한 단순 강합성보에 교축방향으로 프리스트레스를 도입하는 경우, 콘크리트의 장기거동과 PS강재의 릴렉세이션에 의해 발생하는 프리스트레스의 손실과 장기처짐을 계산하기 위한 장기거동해석방법을 제시하였다. 또한 제시된 해석방법을 이용하여 장기거동해석을 수행하였으며, 이를 통해 합성보의 기하형상, 콘크리트강도 및 초기프리스트레스가 프리캐스트 바닥판을 사용한 강합성보의 장기거동에 미치는 영향을 평가하였다. 해석결과 합성보 기하형상의 영향에서 프리스트레스의 손실과 장기처짐에 영향을 미치는 주요인자는 각각 보의 단면적과 단면2차모멘트였다. 마지막으로, 총 프리스트레스 손실에서 크리프에 의한 손실과 건조수축에 의한 손실의 특성을 분석하여 소요 초기프리스트레스의 산정방법을 제안하였다.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2000년도 유체기계 연구개발 발표회 논문집
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• pp.219-225
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• 2000

Primary function of a centrifugal compressor volute is to serve the flow from the impeller and diffuser to pipe system. But losses in volutes at off-design lead to poor stage efficiency and reduction of operating range. This is largely caused by the interaction between the impeller and volute flow fields. The magnitude of distortion is increased as the operating point is away from the design point and, as a result, the interaction between the impeller and volute is stronger. The objective of present study is to find the characteristics of tile flow in the diffuser and volute of the centrifugal compressor with rectangular cross-sectional volute. The measurements are carried out in two cases with the existence and nonexistence of the volute casing. The detailed pressure is presented by comparing the experimental results obtained at two cases with each others.