• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 춘계학술대회 논문집
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• pp.837-841
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• 2004

In order to improve the speed of railway, several parameters and/or technical issues, which are affecting speed improvement negatively, need to be considered in addition to the enhancement of physical performance of the railway system such as maximum speed, speed at curve, and speed at turnout track. The parameters under complicated situation of railway system are from the areas of rolling stocks, track, power system, signalling, etc. In general, two different aspects of technical issues can be evaluated; Technical issues in the hardware aspect and technical issues in the software aspect. The hardware parameters include running performance, braking performance, and power performance, while the software factors are rules, regulations, and riding quality. In this investigation, a comparison study between hardware and software aspects in technical issues was conducted to provide technical information on the amendment of railway speed-up regulations.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2005년도 학술발표회(2)
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• pp.1141-1142
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• 2005

• Journal of Welding and Joining
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• 제22권1호
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• pp.26-31
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• 2004

• 대한인간공학회지
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• 제36권5호
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• pp.485-498
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• 2017

Objective: This study aims to survey and compare three systemic accident investigation techniques of Accimap, STAMP and FRAM, based on the application studies of the Sewol ferry accident. Background: Traditional accident investigation methods such as domino models, FTA, etc. work well for losses caused by physical component failures or actions of human in relatively simple systems, but are unable to depict mechanisms generating errors and violations in the current complex socio-technical systems. For better understanding the structure and behavior of the socio-technical systems, systemic techniques have been developed and used. Method: This study was mainly based on survey of literatures through surfing webpages of ScienceDirect and Google, and ergonomics relevant journals. The key words of Sewol, Sewol ferry, Sewol ferry accident, etc. were used in the survey. Results: Three systemic accident investigation methods included similar actors in the Sewol ferry accident including government, Ministry of Ocean and Fisheries, Korean Coast Guard, Korean Register of Shipping, Korea Shipping Association, Chonghaejin Marine Company, crew members. The methods graphically represented each level's failures or performance variabilities of relevant functions and relationships between them. It was shown that the systemic methods consider the entire system, ranging from the environment in which the accident occurred, to the role of government in shaping the system of work. Each method has its own comparative pros and cons, but the Accimap has advantages in terms of time of analysis, data required, model complexity and degree of comprehensiveness. Conclusion: This study reviewed and compared three systemic accident investigation methods, which showed that there are systemic characteristics and pros and cons in the methods. Application: The results would be used as a guideline when selecting accident investigation methods.

• Journal of Pharmaceutical Investigation
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• 제16권2호
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• pp.72-75
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• 1986

A convenient high performance liquid chromatographic method was established for the quantitative determination and content uniformity test of aclatonium napadisilate preparation. This method was more simple to make the sample solution for injection, and easy to determine the content in the preparation. Aclatonium napadisilate was chromatographed using a $Lichrosorb-NH_2$ column $(4mm\;{\times}\;25\;cm$, and acetonitrile-water mixture (83:17) as an eluent at a flow rate of 1.8 ml/min. RI-detector response was linear over a range of $0.5{\sim}2.0%$ aclatonium napadisilate under above conditions. Reproducibility studies gave relative standard deviation of 1.29%.

• Applied Microscopy
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• 제43권2호
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• pp.88-97
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• 2013

Technical investigation to figure out the problems arising during in-situ heating electron backscatter diffraction (EBSD) analysis inside scanning electron microscopy (SEM) was carried out. EBSD patterns were successfully acquired up to $830^{\circ}C$ without degradation of EBSD pattern quality in steels. Several technical problems such as image drift and surface microstructure pinning were taking place during in-situ experiments. Image drift problem was successfully prevented in constant current supplying mode. It was revealed that the surface pinning problem was resulted from the $TiO_2$ oxide particle formation during heating inside SEM chamber. Surface pinning phenomenon was fairly reduced by additional platinum and carbon multi-layer coating before in-situ heating experiment, furthermore was perfectly prevented by improvement of vacuum level of SEM chamber via leakage control. Plane view in-situ observation provides better understanding on the overall feature of recrystallization phenomena and cross sectional in-situ observation provides clearer understanding on the recrystallization mechanism.

• Structural Engineering and Mechanics
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• 제14권2호
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• pp.237-243
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• 2002

It is well known that torsionally unbalanced buildings are more vulnerable to earthquake hazards than are the regular structural systems. In this paper, a parametric investigation is presented, in order to observe the amplification in the internal forces, when increased eccentricities are used instead of the ones corresponding to the 5% accidental eccentricity. A series of five, ten-story framed and walled structures, with rather high torsional irregularity coefficients, are selected and a numerical test procedure is applied. Numerical results show that the maximum amplification in the internal forces at the most critical beams and columns at the flexible sides of the structures is about 10%. It is concluded that, more serious measures in the codes are needed in the case of this rather dangerous type of irregularity.

• International Journal of Fluid Machinery and Systems
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• 제3권4호
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• pp.285-291
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• 2010

To provide required flow rates of cooling or circulating water properly, approach flow conditions of vertical pump systems should be in compliance with state of the art acceptance criteria. The direct inflow should be vortex free, with low pre-rotation and symmetric velocity distribution. Physical model investigations are common practice and the best tool of prediction to evaluate, to optimize and to document flow conditions inside intake structures for vertical pumping systems. Optimization steps should be accomplished with respect to installation costs and complexity on site. The report shows evaluation of various approach flow conditions inside a compact waste water pumping station. The focus is on the occurrence of free surface vortices and the evaluation of air entrainment for various water level and flow rates. The presentation of the results includes the description of the investigated intake structure, occurring flow problems and final recommendations.

• Steel and Composite Structures
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• 제45권6호
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• pp.831-837
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• 2022

Numerical investigation on dynamic characteristics of sandwich plates under periodic and thermal loads has been presented by assuming that the plate has three layers which are a foam core and two skins. The foam core made of Aluminum has porosities with uniform and graded dispersions. The sandwich plate has been supposed to be affected by periodical compressive loads. Also, temperature variation causes uniform thermal load. The formulation has been established based upon a higher-order plate theory and Ritz method has been used to solve the equations of motion. The stability boundaries have also been obtained performing Bolotin's method. It will be indicated that stability boundaries of the sandwich plate depend on periodical load parameters, porosities, skin thickness and temperature.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 추계학술대회 논문집
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• pp.694-698
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• 2005

전기철도에 있어서 열차의 운행속도향상은 지속적으로 추구해야할 당면한 과제이며, 이를 위해서는 철도시스템 전반에 걸친 검토가 이루어져야 한다. 열차의 고속화는 차량기술 뿐만 아니라, 선로 구축물, 신호시스템, 운영기술, 전차선로, 급전시스템 등이 상호 연계되어 종합적으로 경제성을 고려하여 추진되어야 한다. 특히, 전기철도 급전계통의 경우만 보더라도 고속열차가 기존운영선로에 투입될 경우 차량의 집전성능향상, 전압강하대책, 설비용량대책, 궤도노반, 분기기, 신호의 고속화, 전차선로 구조물 검토 등 여러 가지 기술검토가 반드시 수반되어야 한다. 본 논문에서는 이 가운데 AT급전계통에서의 신규의 고속화 열차 투입에 따른 급전계통의 기술검토에 대한 접근방안을 제시하고 실 계통을 대상으로 부하용량 변화의 정도를 예측함으로써, 향후 국내 노선의 전반에 걸쳐 적용 가능함을 입증할 수 있었다.