• 소성∙가공
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• 제29권1호
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• pp.11-19
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• 2020

For microstructural analysis of a friction stir welded (FSWed) joint of advanced high-strength steels, dual phase (DP) and complex phase (CP) steels, are studied. FSWed joints are successfully fabricated in the following four cases: (i) DP/DP; (ii) CP/CP; (iii) DP/CP, where the advancing side is DP and the retreating side is CP; (iv) CP/DP, where the advancing side is CP and the retreating side is DP. The stir zone (SZ) of (i) the DP/DP joint mainly consists of lath martensite, while the stir zone of (ii) the CP/CP joint consists not only of lath martensite but also of bainite. In the case of (iii) DP/CP and (iv) CP/DP, they exhibit a similar microstructure including acicular-shaped phases in the joints; however, cross-sections of the joints show differences in material mixing in each case. In (iv) the CP/DP joint, temperature towards the CP steel is sufficient to cause softening, thus leading to better mixing than that in (iii) DP/CP. The phases of the SZ in each of the four cases are formed by phase transformation during the FSWed process; however, the transformed phase volume fraction of CP steel is lower than that of DP steel, indicating that dynamic recrystallization occurs mainly in CP steel. The hardness values of the SZ are significantly higher than those of the base materials, especially, the SZ of (iii) the DP/CP joint has the highest value due to highest fraction of lath martensite.

• Clinical and Experimental Pediatrics
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• 제54권10호
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• pp.409-413
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• 2011

Purpose: Few studies have been conducted on the recent status of infectious mononucleosis (IM) in Korean children. The aim of this study was to evaluate the recent trend in the clinical manifestations of Epstein-Barr virus (EBV)-associated IM as well as the clinical differences according to age. Methods: A retrospective study was performed on 81 children hospitalized with EBV-associated IM who fulfilled the serological criteria for the diagnosis of EBV infection (viral capsid antigen immunoglobulin M positive). The patients were divided into 3 age groups: <5 years, 5 to 9 years, and ${\geq}10$ years. We evaluated the recent trend in clinical manifestations and the differences in clinical and laboratory findings among the 3 age groups. Results: Thirty (37%) children were under 5 years of age, 38 (46.9%) were 5 to 9 years of age, and 13 (16%) were 10 years of age or older. The differences in the symptoms and signs among the 3 age groups were not statistically significant, except for headache. The mean duration of fever was 7.7 days (range, 0 to 18 days). A comparison of liver enzyme elevation among the age groups showed an association with advancing age (26.6%, 63.1%, and 76.9%, respectively, P=0.04) Conclusion: This study showed that EBV-associated IM in Korean children continues to occur mostly in children under 10 years of age. In children with EBV-associated IM, the incidence of headache and liver enzyme elevation, the duration of fever, and the proportion of females to males were all positively associated with advancing age.

• Journal of Chest Surgery
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• 제30권3호
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• pp.293-299
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• 1997

고려대학교 구로병원에서는 1994년 8월부터 국내에서는 처음으로 새로운 이엽성 기계판막인 ATS(Advancing The Standard)을 이용, 21명의 환자에게 28개의 판막을 치환하였다. 환자는 평균연령 27세로 10명의 남자와 11명의 여자로 수술전후의 NYHA 기능적분류는 평균 2.9에서 1.4로 감소하였다. 심초음파상의 심박출 지수는 55.5에서 59.8으로 다소 상승하였다. 치환후 승모판 전후의 압력차는 양호하였으며,용혈 여부를 확인하기위한 LDH치는 다소 상승하였으나 임상적 중요성은 없었다. 판막과 관련된 합병증은 없었으며, 항응고제 투여와 관련된 뇌출혈이 1례 있었다. 사망례는 없었으며, 현재는 모든 환자에

• 패션비즈니스
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• 제11권1호
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• pp.38-47
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• 2007

In the modern society that is advancing rapidly, the hair art is also advancing and subdividing. The purpose of this study is to investigate unique field of formative as characteristics and forms of copper wire, focused on such a harmony of hair art, the present thesis aims at developing concept of hair art as a creative way, and recognizing the formative characteristics of copper wire as analyze and arrange the concept of hair art, formative, a way of practical application, material aspect, through literature, academic journals, photo data, and researched about prior piece, for example, architecture and costume with hair art, and then pieces of hair art were made. Influenced by the theory, applied the social phenomenon and the formative principles, produced the five pieces which includes balance, composure, flying, harmony, way, spring etc. The results of this research are outlined below. Firstly, It showed that the copper wire can express the mysterious and beautiful formative world, and it could know the possibility of design. Secondly, formative activity using copper wire can differ according to approach and interpretation, and it can be a works with aesthetic value. Thirdly, hair could be express the art of the three-dimensional forms which constitute the mixture of line, surface and space. So, hair art has enlarged the fields with development of technique, and changed to recognition of the hair art, and opened up a new field. Hair art will be positive fields to maximize the possibility, and not only the beauty artist but also the public will be communicate each other.

• Journal of the Korean Data and Information Science Society
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• 제21권4호
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• pp.719-727
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• 2010

오랜 역사를 가지는 전통 놀이인 윷놀이에서 윷의 정의를 살펴보고 윷의 형태에 대한 고찰을 한다. 윷의 확률에 관한 선행연구에서의 성과와 개선점을 살펴본다. 좋은 윷에 대한 개념의 설정을 위해 사위의 확률순서를 정의하며, 윷의 등의 확률에 따른 사위의 순서를 구한다. 윷의 분포에 대하여 변형된 이항분포로써의 윷이항분포를 정의하며 평균과 분산을 구한다. 윷놀이에서 한 사람의 차례에서 말이 가는 기대거리를 구하고 특성을 살펴본다. 좋은 윷을 위한 두 개의 지표를 제안하며, 사위의 확률순서를 함께 고려하여, 좋은 윷을 위한 등의 확률을 찾아본다. 이때, 네 개의 윷의 등의 확률이 모두 같아야 한다는 조건을 배제한다. 또한 윷의 표준화를 위한 제안을 한다.

• 한국건설관리학회:학술대회논문집
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• 한국건설관리학회 2004년도 제5회 정기학술발표대회 논문집
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• pp.59-66
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• 2004

건설엔지니어링의 사업비는 공사비의 $3\~5$ 정도에 지나지 않으나, 최종 사업목적물의 성능을 결정하는데 커다란 영향을 미치고 있어 매우 중요하다. 그러나 그동안 정부 및 민간업체에서는 시공분야보다 건설엔지니어링분야의 기술개발투자 및 경쟁력을 강화하기 위한 대책마련이 미흡하였다. 따라서, 본 연구에서는 선진외국의 해외진출 지원제도를 조사 $\cdot$ 분석하였고, 해외출장 및 관련전문가의 면담조사로 국내업체의 해외진출시 문제점 및 애로사항을 조사 $\cdot$ 분석하였다 본고에서는 건설엔지니어링업체의 기술력 향상방안과 해외시장으로 진출하기 위한 정부 및 민간차원의 해외진출 활성화 방안을 마련하였다. 특히, 국내업체의 해외진출 활성화 방안으로, 해외정보 수집지원방안, 조세 및 보조금 지원방안, 타 기관과의 전략적 제휴방안 등을 제안하였다.

• Journal of the Korean Data and Information Science Society
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• 제27권3호
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• pp.663-676
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• 2016

한국의 프로야구는 정규시즌 중의 성적이 4위인 팀이 와일드카드인 1승을 안고 5위 팀과 싸워 2승을 먼저 하는 팀이 준 플레이오프에 진출한다. 준 플레이오프 진출 팀이 3위 팀과 싸워 3승을 먼저 하는 팀이 플레이오프에 진출하고 이 팀이 다시 2위 팀과 싸워 3승을 먼저 하는 팀이 코리언 시리즈에 진출하게 된다. 코리언시리즈 진출 팀은 1위 팀과 싸워 먼저 4승을 거두는 팀이 최종 우승팀이 된다. 이러한 포스트 시즌 경기방식을 따를 경우 상위 포스트 시즌 경기에 진출한 각 순위의 팀이 우승할 확률은 팀의 승률에 따라 결정됨을 알 수 있다. 본 연구에서는 Bernoulli 시행인 경우와 서로 독립인 경우만을 가정하는 경우 한국시리즈와 같은 우승 결정방식에서 상위 팀들이 우승할 확률을 추정하는 방법을 제안하였다. 본 연구의 결과를 이용하면 시즌 중의 각 팀 간의 승률이나 포스트 시즌 중매 경기에 대한 각 팀 간의 승률을 이용하여 포스트 시즌 진출 팀들의 최종 우승확률을 추정할 수 있다.

• 한국정밀공학회지
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• 제19권7호
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• pp.71-79
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• 2002

A new rapid prototyping process, Variable Lamination Manufacturing using a 4-axis-controlled hotwire cutter and expandable polystyrene foam sheet as a laminating material of the part (VLM-S), has been developed to reduce building time and to improve the surface finish of parts. The objective of this study is to reconstruct the surface of the original 3D CAD model in order to generate mid-slice data using the advancing front technique. The generation of 3D layers by a 4 axis-controlled hot-wire cutter requires a completely different procedure to generate toolpath data unlike the conventional RP CAD systems. The cutting path data for VLM-S are created by VLM-Slicer, which is a special CAD/CAM software with automatic generation of 3D toolpath. For the conventional sheet type system like LOM, the STL file would be sliced into 2D data only. However, because of using the thick layers and a sloping edge with the firstorder approximation between the top and bottom layers, VLM-Slicer requires surface reconstruction, mid-slice, and the toolpath data generation as well as 2D slicing. Surface reconstruction demands the connection between the two neighboring cross-sectional contours using the triangular facets. VLM-S employs thick layers with finite thickness, so that surface reconstruction is necessary to obtain a sloping angle of a side surface and the point data at a half of the sheet thickness. In the process of the toolpath data generation the surface reconstruction algorithm is expected to minimize the error between the ruled surface and the original parts..

• Journal of Mechanical Science and Technology
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• 제20권5호
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• pp.710-716
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• 2006

Micro-PIV system with a high speed CCD camera is used to measure the flow field near the advancing meniscus of a water slug in microchannels. Image shifting technique combined with meniscus detecting technique is proposed to measure the relative velocity of the liquid near the meniscus in a moving reference frame. The proposed method is applied to an advancing front of a slug in microchannels with rectangular cross section. In the case of hydrophilic channel, strong flow from the center to the side wall along the meniscus occurs, while in the case of the hydrophobic channel, the fluid flows in the opposite direction. Further, the velocity near the side wall is higher than the center region velocity, exhibiting the characteristics of a strong shear-driven flow. This phenomenon is explained to be due to the existence of small gaps between the slug and the channel wall at each capillary corner so that the gas flows through the gaps inducing high shear on the slug surface. Simulation of the shape of a static droplet inside a cubic cell obtained by using the Surface Evolver program is supportive of the existence of the gap at the rectangular capillary corners. The flow fields in the circular capillary, in which no such gap exists, are also measured. The results show that a similar flow pattern to that of the hydrophilic rectangular capillary (i.e., center-to-wall flow) is always exhibited regardless of the wettability of the channel wall, which is also indicative of the validity of the above-mentioned assertion.

• Asian-Australasian Journal of Animal Sciences
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• 제17권12호
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• pp.1657-1662
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• 2004

The forage potential of mulberry (Morus alba) was evaluated under Malaysian conditions. The yield and nutrient composition of plant fractions of mulberry (whole plant, leaf and stem fractions) were determined at four harvest stages, namely, 3 (W3), 5 (W5), 7 (W7) and 9 (W9) weeks in a randomized block design. The study was conducted over a 9-month period to assess the persistence of the crop to repeated harvests. Fresh and dry matter (DM) yields of all plant fractions increased significantly (p<0.01) with increasing intervals between harvests, with highest DM yields at W9. The leaf to stem ratio declined significantly (p<0.01) from 5.2 (W3) to 0.9 (W9), indicating predominance of the stem fraction with advancing maturity. The nutritional composition of plant fractions was also significantly influenced (p<0.01) by advancing plant maturity at harvest. Crude protein (CP), ash and the metabolisable energy content of plant fractions declined significantly (p<0.01) from W3 to W9, while there was a corresponding significant increase (p<0.01) in the acid detergent fibre, neutral detergent fibre and acid detergent lignin. From this study it was concluded that the optimum stage to harvest the whole plant is 5 weeks, which is a compromise between yield, nutrient composition (CP and fibre components), and the annual number of cuts, with good crop persistence to repeated harvests. Fresh mulberry whole plant can provide a valuable supplemental source of nutrients to poor quality basal diets.