• International Journal of Automotive Technology
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• 제5권3호
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• pp.155-164
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• 2004

The direct injection gasoline spray-wall interaction was characterized inside a heated pressurized chamber using various visualization techniques, including high-speed laser-sheet macroscopic and microscopic movies up to 25,000 frames per second, shadowgraph, and double-spark particle image velocimetry. Two hollow cone high-pressure swirl injectors having different cone angles were used to inject gasoline onto a heated plate at two different impingement angles. Based on the visualization results, the overall transient spray impingement structure, fuel film formation, and preliminary droplet size and velocity were analyzed. The results show that upward spray vortex inside the spray is more obvious at elevated temperature condition, particularly for the wide-cone-angle injector, due to the vaporization of small droplets and decreased air density. Film build-up on the surface is clearly observed at both ambient and elevated temperature, especially for narrow cone spray. Vapor phase appears at both ambient and elevated temperature conditions, particularly in the toroidal vortex and impingement plume. More rapid impingement and faster horizontal spread after impingement are observed for elevated temperature conditions. Droplet rebounding and film break-up are clearly observed. Post-impingement droplets are significantly smaller than pre-impingement droplets with a more horizontal velocity component regardless of the wall temperature and impingement angle condition.

• Journal of Advanced Marine Engineering and Technology
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• 제30권5호
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• pp.636-644
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• 2006

Recently, there were some successful examples that the laser welding was introduced into production line. However, the spread of laser welding is not sufficient in many industries. There are several reasons why it is difficult to penetrate the laser welding into production lines. Because it is different from reflection, absorption and permeation of laser beam according to material and surface condition. Moreover, there are significant problems in processing such as absorption and scattering of beam by the induced plasma or plume. Therefore, understanding of mechanism on formation of weld defect in laser welding of the laminated core for motor is very important. In this paper, it was analyzed in terms of materials which was source of defect in laser welding and conventional arc welding. As a results of analysis, insulation coating film of the laminated core was judged to main factor of weld defect. it could be well aware as tracing carbon volume, and it was deduced that weld defect by insulation coating film was caused by difference of mechanism between the two heat sources.

• 대한토목학회논문집
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• 제12권3호
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• pp.153-162
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• 1992

시스템 분석에 의한 합리적인 장기(長期) 용수공급(用水供給) 계획(計劃)의 수립을 위하여 동적(動的) 입지선정문제(立地選定問題)의 유형으로 수학적 모형을 정립하였고, 복잡한 혼합 정수계획 문제를 푸는 대신에 스프레드 쉬트를 이용한 간단한 계산모형으로 실제적인 해를 구할 수 있음을 보였다. 분석의 결과로서는 용수 공급시설 및 용수로의 최적의 건설 시기와 기간별 최적 용수공급 운영 양상이 정해진다. 시스템 분석을 통한 합리적(合理的)인 용수공급 계획의 수립이 주먹 구구식의 계획수립에 비하여 약 15% 정도의 예산 절감(節減) 효과(效果)가 있을 수도 있음을 사례분석을 통하여 간접적으로 보여준다.

• 소성∙가공
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• 제23권7호
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• pp.425-430
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• 2014

The aim of the current study was to predict the plastic deformation behavior of a heated slab during hot rough rolling. FE-simulations were performed to investigate the metal flow and to locate the position of surface material from the slab through the rough rolling and onto the strip, using a material point tracking technique. In addition, experimental hot rolling trials were conducted where artificial defects were impressed onto a heated slab in order to validate the FE-simulation results. The simulated results show the same tendency of deformation behavior as the experimental measurements. The movement of slab defects from the side surface towards the strip center is directly linked to the extent of lateral spread during the rolling.

• Journal of Information Technology Applications and Management
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• 제20권2호
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• pp.1-14
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• 2013

Learning accounting has always been a challenge for non-accounting students and managers. Understanding accounting information requires more than a numerical description of financial and income statements. Current accounting practice presents accounting reports in the form of tables with values or in two or three dimensional graphs generated by a spread sheet program. The present study proposes an alternative visualization with metaphor from nature as a learning device for novice users and managers. After surveying various kinds of plants, the lotus flower was chosen as an attractive analogy because every part of the plant from leaves to roots is usable and can have economic value. Moreover, lotus flowers, whether man-made or natural, can easily be part of a familiar, natural ecology representing both beauty and serenity. Results from online survey respondents (n = 220) showed that there was no significant difference on overall usability of the Lotus visualization between expert users and novice users. However, verbally-oriented users differed Significantly from visually-oriented users in their usability assessment, perceived usefulness, and intention to use the Lotus visualization.

• 품질경영학회지
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• 제30권4호
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• pp.86-93
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• 2002

There are many different factors used in calculating control limits of control chart for variable data. Specially these factors are divided into two groups such as "no given standard" and "given standard"(namely, for analysis and management), but many kind of factors give rise to confusion. Therefore, It is necessary to manifest relationships among factors for easy application regardless of subgroup size. Many SQC textbooks show us plainly these factors, but do not have enough for adequate explanation of relationships among factors. Besides, notation of these factors of SQC textbook isn't coincide with another one, so necessity to the coincidence for the notation of the factors is highlighted during my work recently. In this study, the close examination about relationships among various factors (A-A3, B3-B6, D1-D4, C4, d2, d3 etc) was carried out. Spread sheet results are presented for getting factors according to subgroup size, by grouping as the case of "no given standard" and "given standard". How are these factors to be applied in statistical package (ex, Minitab) have been analyzed using a series of sample data. analyzed using a series of sample data.

• Structural Engineering and Mechanics
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• 제49권5호
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• pp.645-660
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• 2014

This paper presents the design and project of an innovative concept for a Single Point Incremental Forming (SPIF) Machine. Nowadays, equipment currently available for conducting SPIF result mostly from the adaptation of conventional CNC machine tools that results in a limited range of applications in terms of materials and geometries. There is also a limited market supply of equipment dedicated to Incremental Sheet Forming (ISF), that are costly considering low batches, making it unattractive for industry. Other factors impairing a quicker spread of SPIF are large forming times and poor geometrical accuracy of parts. The following sections will depict the development of a new equipment, designed to overcome some of the limitations of machines currently used, allowing the development of a sounding basis for further studies on the particular features of this process. The equipment here described possesses six-degrees-of freedom for the tool, for the sake of improved flexibility in terms of achievable tool-paths and an extra stiffness provided by a parallel kinematics scheme. A brief state of the art about the existing SPIF machines is provided to support the project's guidelines.

• 한국방사선학회논문지
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• 제3권2호
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• pp.5-10
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• 2009

심근영상의 SPECT(Single Photon Emission Computed tomography)검사는 감마선을 방출하는 방사성의약품을 환자에게 정맥주사한 후 이 의약품이 심장에 고루 퍼지면 관심부위를 촬영하여 질병으로 인한 변화를 컴퓨터를 이용하여 진단하는 검사법이다. 기능적인 정보를 담고 있는 심근관류 영상은 비침습적인 심근질환 검사에 유용한 방법이지만, 물리적 인자들에 의해 잡음과 낮은 해상도는 판도하는데 어려움을 주게 된다. 본 논문은 심근영상을 레벨 셋 알고리즘을 이용하여 영상을 분할하고 분할된 영역을 3차원으로 구현하여 판독에 도움을 주는 방안을 제안하였다. 판독의 어려움을 해결하기 위하여 레벨 셋을 이용하여 관심부위인 좌심실 영역을 분할하였고 분할된 영역을 3차원영상으로 모델링하였다.

• 한국산학기술학회논문지
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• 제11권6호
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• pp.2240-2245
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• 2010

심근영상의 SPECT(Single Photon Emission Computed tomography)검사는 감마선을 방출하는 방사성의약품을 환자에게 정맥주사한 후 이 의약품이 심장에 고루 퍼지면 관심부위를 촬영하여 질병으로 인한 변화를 컴퓨터를 이용하여 진단하는 검사법이다. 기능적인 정보를 담고 있는 심근관류 영상은 비침습적인 심근질환 검사에 유용한 방법이지만, 물리적 인자들에 의해 잡음과 낮은 해상도는 판도하는데 어려움을 주게 된다. 본 논문은 심근영상을 레벨 셋 알고리즘을 이용하여 영상을 분할하고 분할된 영역을 3차원으로 구현하여 판독에 도움을 주는 방안을 제안하였다. 판독의 어려움을 해결하기 위하여 레벨 셋을 이용하여 관심부위인 좌심실 영역을 분할하였고 분할된 영역을 3차원영상으로 모델링 하였다.

• 한국물환경학회지
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• 제26권3호
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• pp.432-438
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• 2010

LIDMOD2 was developed for evaluation of low impact development (LID) and best management practice (BMP) by modification of Site Evaluation Tool (SET). The modification includes employment of SCS-CN method for annual runoff simulation, unit load method for annual pollutant loads simulation, and the method proposed by Korean TMDL for calculating pollutant reduction by BMPs. The CN values were updated with regionalized parameters within Nack-Dong River basin because these are important parameters for simulating hydrology. LIDMOD2 was tested by applying to Andong Bus terminal. As a simulation results, pollutant loads and surface runoff will be significantly increased by post-development without LID compared with those from pre-development. LID technique was simulated to efficiently reduce surface runoff and pollutant load and increase infiltration. LIDMOD2 is screening level tool and easy to use because LIDMOD2 is based on spread sheet and most of parameters are regionalized. LIDMOD2 was illustrate that it could evaluate LID well by summarizing and graphing annual hydrology, annual pollutant loading, and hydrograph for event storm. The calculation methods related with pollutant loads are employed from the guideline of Korean TMDL and it can be useful tool for Korean TMDL to evaluate the effect of LID/BMP on developing area.