• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.446-450
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• 2008

Urban transits of metropolises have been used by many citizens due to the merits of environment friendly traffic, mass transportation, safety and scheduled operation. It is very important to keep safety for the increased passengers. When the accidents as like fire occur, rapid evacuation from fire site is one of the most effective methods to decrease casualties. Furthermore, overseas buyers sometimes request the verification results of the passenger evacuation from rolling stock. In this study, algorithm for passenger flow analysis based on DEM(Discrete Element Method) is newly developed and made simulation program package. And, we applied it to the evacuation problem for urban transits. By using the developed program, we compared the simulation results of the effects of the location and size of door and elapsed time qualitatively and quantitatively.

• 대한기계학회논문집B
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• 제32권3호
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• pp.173-180
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• 2008

Diurnal variation of the flow over a forest canopy on a mountain slope is simulated numerically. In the daytime, the earth surface is heated by the solar radiation and the flow goes up the mountain due to the buoyancy force, and during the night, the air is drained downward along the slope owing to the cooling of the surface by radiation. In this flow process the forest canopy that consists of leaf region and the trunk region plays a dominant role as a momentum sink to the flow, thus the modeling of the leaf area region and trunk region is critical to the successful flow simulation. In the present study, a field measurement in an experimental forest in the State of Oregon in the United States is numerically analyzed. The resistance to the flow in the leaf region is directly related to the leaf area density (LAD), and the trunk is modeled as a cylinder.

• Asian Journal of Innovation and Policy
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• 제3권2호
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• pp.172-192
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• 2014

This study aims to analyze the valuation of technology firms in the stock market to answer how before-market entities should be valuated. This study analyzes 230 market reports of 2012 for technology firms in the KOSDAQ under several hypotheses. The results are as follows: 90% used the 3 multiples methods consisting of PER multiples with 80%, PBR multiples 8.7% and EBITDA multiples 1.7%. The average of PER multiples was 15 with the range of 6.9 to 83. That of PBR multiples is 2.27. Forecasting for cash flow is not applied over 4 years, but mainly 2-3 years. The accuracy of forecasting was 18.8%, 34.4% and 8% according to the different definitions. No differences were found in the accuracy of forecasting between valuation methods, between the industries having more intangible assets and the industries having less, and between startups and general companies and between ages and listed ages.

• 대한안전경영과학회지
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• 제12권3호
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• pp.215-221
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• 2010

Many researches and projects are actively implemented in the academic world and industrial world in order to increase the productivity through changing utility layout. Effective layout makes the flow of parts and products go on wheels and helps labor forces and utilities to be used efficiently. In this study, we looked at effect on utility layout change through a case of a company making a fuel tank of vehicle in Korea. Due to the layout improvement, this company could have flowshop system on welding line, so the stock in line was decreased, checking the number of stock became easier than before and it was possible to evaluate exact cycle time per unit. Through not only confirming qualitative effect, but also checking quantitative effect such as UPH(Unit per Hour), we obtained the conclusion that the layout improvement increased the productivity.

• 펄프종이기술
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• 제31권3호
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• pp.35-46
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• 1999

Mathematical modeling provided a systematic analysis for the dynamic behavior of stock fluid in a paper machine pressurized headbox. Dynamic responses of liquid level, sheet basis weight and hydraulic pressure were predicted from the simulation model which represents the system. A unit step and asinusoidal wave load were considered as the input forcing functions in the headbox. Results are summarized as follows : 1. The dependence of sheet basis weight on liquid level in the pressurized-headbox was non -linear. 2. Liquid level in the head-box showed first-order lag with a unit step forcing to fluid input rate ; 3 . The amplitude of wave response of liquid level was inversely proportional to the time content for the sinusoidal input changes ; 4.Sheet basis weight showed second-order oscillating underamped responses for the step input load of flow rate ; 5. The damping factor in the second-order system was a function of air-pressure in the headbox ; and, 6. Dead-time existed in the measuring process for the headbox slice pressure.

• The Journal of Asian Finance, Economics and Business
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• 제6권2호
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• pp.247-255
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• 2019

This study examines the different roles of cash flow in assessing investment returns in the Association of Southeast Asian Nations (ASEAN). The analysis covers over 900 listed firms across Malaysia, Indonesia, Philippines, Singapore and Thailand for the period post the Asian financial crisis of 2001-2017. Firm-level panel data analysis shows that cash flow factors are important in all contexts of cash return on assets, earnings quality and market value multiple across the region even after controlling for typical measures of profitability. The results suggest that firms should manage cash flow prudently in considerations of firm value from the shareholder's perspective, measured directly using stock return. Cash profitability on assets should become an important firm performance indicator, whilst higher cash component over reported earnings is preferred. The market also tends to respond favourably to cash flow yield as a price multiple in valuation, outpacing the role of earnings yield. Such findings are robust across the pre and post subprime crisis periods, across estimation methods pertaining to finance panel standard errors, as well as across static and dynamic considerations of returns. It is hence sensible to consider cash flow factors in the research pertaining to asset pricing and factor investing in the ASEAN region.

• 펄프종이기술
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• 제33권4호
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• pp.21-27
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• 2001

Korean traditional paper (Hanji) making technology has adopted two kinds of sheet forming processes, which called "Oebal-choji": and "Ssangbal-choji". The sheet forming process of Oebal-choji is an original method developed in Korea. At first, paper stock is dipped onto the mold and flow away in the forward direction. Then, paper stock is scooped again and rhythmically rocked from side to side, this work is repeated several times. Through this operation the fibers intertwine and paper layers are formed. Ssangbal-choji is almost same as the Nagashizuki, which used in Japan. In this method, paper stock is scooped onto the mold and rhythmically rocked backwards and forwards several times, the water drains slowly through the bamboo screen and then sheet is formed. Tamezuki method is used in Japan and China. This is a method in which the mold is dipped into the paper stock once and left to drain. In the Ssangbal-choji and Nagashizuki methods, the most of excess solution is cast out while in the Tamezuki all of it is allowed to drain through the mold. This study was carried out to investigate the physical properties of the Hanjis that were made by Oebal-choji, Ssangbal-choji, Nagashizuki, and Tamezuki sheet forming processes. The results were follows; Physical properties of the Oebal-choji Hanji were better than those of Ssangbal-choji, Nagashizuki, and Tamezuki. Oebal-choji Hanji made little difference of paper strength between MD and CD, but Ssangbal-chjo and Nagashizuki Hanjis made wide difference. And there are no difference of paper strength between MD and CD on the Tamezuki Hanji. On the confocal laser scanning microscopy (CLSM) observation of the Hanjis, Oebal-choji made well crossed fiber orientation than those of other forming processes.r forming processes.

• Journal of the Korean Data and Information Science Society
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• 제21권6호
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• pp.1289-1303
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• 2010

The need for statistical process control to check the performance of a process is becoming more important in chemical and pharmaceutical industries. This study illustrates the method to determine whether a process is in control and how to produce and interpret control charts. In the experiment, a stream of green dyed water and a stream of pure water were continuously mixed in the process. The concentration of the dye solution was measured before and after the mixer via a spectrophotometer. The in-line mixer provided benefits to the dye and water mixture but not for the stock dye solution. The control charts were analyzed, and the pre-mixer process was in control for both the stock and mixed solutions. The R and X-bar charts showed virtually all of the points within control limits, and there were no patterns in the X-bar charts to suggest nonrandom data. However, the post-mixer process was shown to be out of control. While the R charts showed variability within the control limits, the X-bar charts were out of control and showed a steady increase in values, suggesting that the data was nonrandom. This steady increase in dye concentration was due to discontinuous, non-steady state flow. To improve the experiment in the future, a mixer could be inserted into the stock dye tank. The mixer would ensure that the dye concentration of the stock solution is more uniform prior to entering the pre-mixer ow cell. Overall, this would create a better standard to judge the water and dye mixture data against as well.

• 암석학회지
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• 제24권2호
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• pp.91-105
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• 2015

청송 북동부에서 중태산과 갈평지 관입체는 영양소분지에서 각각 가송동층과 도계동층을 관입하여 각각 병반과 암주로 산출된다. 그리고 청송 암맥군은 도계동층을 관입하며 갈평지 암주에 매우 밀접하게 조합되어있다. 이 암맥군은 방사상으로 갈평지에 수렴되고 전체 윤곽이 타원형 분포를 나타낸다. 또한 암맥들은 유상엽리, 구과상, 석정상 구조를 나타내는 유문암맥들이며 하나의 단일 관입상을 나타낸다. 암맥들의 방향성은 관입체에서 응력상태에 의하여 지배되는 것으로 해석할 수 있다. 즉 암맥들은 일반적으로 갈평지 암주의 관입에 의해 퇴적암류의 도움작용 동안에 최고 주응력축에 직각으로 발생하는 방사상 단열에 따르는 수직 인장절리를 따라 주입해 방사상 패턴을 나타낸다. 이 패턴은 본역에서 이 암맥들이 대부분 방사상 절리들 속으로 주입을 충분히 설명해줄 수 있다.

• 해양환경안전학회지
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• 제23권1호
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• pp.104-111
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• 2017

본 연구는 원심펌프 내부 유동장 특성에 대한 시뮬레이션 및 시각화에 중점을 둔다. 3D 수치해석은 Reynolds Average Navier-stock 코드를 k-${\varepsilon}$ 표준 2차방정식 난류 모델로 처리하여 수행하였다. 시뮬레이션은 흡입측, 임펠러, 토출측 영역에서 조도로 인한 마찰 손실과 임펠러 웨어링에서 체적 손실을 포함한다. 해석과 실험사이의 성능곡선 비교결과 최대 5 %의 작은 차이를 보이며 동일한 추세를 나타냈다. 최고 효율점에서 속도 벡터는 고르게 나타났지만 비 설계점에서는 현저한 변화가 나타났고, 텅 부근의 임펠러 유로토출부에서 강력한 재순환 영역이 나타났다. 비교적 일정한 압력분포가 텅 부근임에도 불구하고 임펠러 주위에 관찰되었다. 볼류트 내에서 기하학적으로 인해 형성된 나선형 와류가 이 영역에서 유동장이 상대적으로 난류이고 불안정하다는 것을 증명하였다.