• 소성∙가공
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• 제24권2호
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• pp.107-114
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• 2015

The current study presents a geometric measurement and analysis of the section profile for a feature line surface on an automotive outer panel. A feature line surface is the geometry which is a visually noticeable creased line on a smooth panel. In the current study the section profile of a feature line surface is analyzed geometrically. The section profile on the real press panel was measured using a coordinate measuring machine. The section profiles from the CAD model and the real panel are aligned using the same coordinate system defined by two holes near the feature line. In the aligned section profiles the chord length and height of the curved part were measured and analyzed. The results show that the feature line surface on the real panel is doubled in width size.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 추계학술대회 논문집
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• pp.128-131
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• 2007

It is very important that there are saving resource and energy in the future as well as in these day. Weight saving of structural parts, which are formed by extrusion, plays a key role in manufacturing field. Especially these aluminum parts used in the car need other processes to vary the cross section in the axial direction. Thus, applications of these parts are limited by high cost. if the cross section of the parts is variable by only extrusion, application of extruded aluminum parts will more increase. Therefore, a new CNC extruder which can control the section area of a car part was invented the nation's first. Using the extrusion machine, the experiment and FE analysis were performed during the varied section extrusion process.

• 대한조선학회논문집
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• 제42권4호
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• pp.421-426
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• 2005

Scattering center extraction schemes for radar cross section reduction of large complex targets, like warships, was developed, which are an 1-D radar image method(range profile), and a direct analysis based on an object precision method. The analysis result of partial dihedral model shows that the presented direct analysis method is more efficient than the 1-D radar image method for scattering center extraction of interested targets, in terms of radar cross section reduction design, not signal processing. In order to verify the accuracy of the direct analysis method, a scattering center analysis of an naval weapon system was carried out, and the result was coincident with that of another well-known RCS analysis program. Finally, an analysis result of RCS and its scattering center of an 120m class warship-like model presented that the direct analysis method can be an efficient and powerful tools for radar cross section reduction of large complex targets.

• 한국방재학회 논문집
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• 제3권3호
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• pp.125-132
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• 2003

본 연구에서는 국지성 이상호우에 대한 하천의 치수 안전도를 분석하기 위하며 서울의 도시하천중 지방2급 하천인 홍제천을 연구 대상하천으로 선정하였고, 최근 발생한 이상호우 중에서 서울에 많은 피해를 입힌 2001년 7월 14일${\sim}$15일 강우 310.1mm와 서울지역 가능최대강수량(PMP)740.0mm를 적용 강우로 선정하였다. 홍제천의 치수 안전도를 분석한 결과, 계획빈도인 50년인 경우, 안전단면이 85%, 관리단면이 15%, 위험단면은 발생치 않았으나, 100년 빈도에서 안전단면이 5% 감소하고 관리단면이 4% 위험단면은 2% 증가하였다. 빈도가 증가함에 따라 증감율은 작게 나타났고 200년 빈도 이후에는 관리단면은 거의 변화가 없었으며 위험단면이 다소 증가하여 300년 빈도에서는 50년 빈도에 비해 8%, 500년 빈도에서는 12% 증가하였고 1000년 빈도에서는 위험단면이 19%, 관리단면이 13% 크게 증가하였다.

• 한국지리정보학회지
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• 제12권4호
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• pp.95-112
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• 2009

하천의 흐름해석 분야에서 모형이 요구하는 입력자료 중 하천단면은 매우 중요한 요소이다. 수치모형을 이용해서 자연하천의 2차원 흐름을 모의하고자 할 때 정확한 계산치를 얻기 위해서는 실제 하천단면의 하상을 정확하게 반영하여야 한다. 그러나 하천단면의 하상을 실제 상태의 모습 그대로 반영하는 것은 거의 불가능하다. 본 연구에서는 현재 실무에서 사용하는 하천측량 자료인 HEC단면과 ArcView를 연계하여 등간격 하도단면을 생성하고 유한요소망을 구축하는 방법을 제안하였다. 연구 대상지역은 한강 본류 구간과 낙동강 본류 구간을 선정하였고 등간격 하도단면 구축결과 실측 단면자료와 잘 일치함을 확인할 수 있었다. 또한 본 연구에서 제안한 등간격 하도단면을 이용하면 2차원 흐름해석 및 수질해석을 위한 양질의 유한요소망을 구축하여 유한요소해석 등에 유용하게 사용될 수 있을 것이다.

• 한국화재소방학회논문지
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• 제25권2호
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• pp.80-87
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• 2011

합성보의 내화성능을 확인하기 위한 재하가열시험 결과, 내화성능이 부족한 경우 단면의 변경을 통하여 그 성능을 향상시킬 수 있다. 하지만 변경조건이 다양하다면 다수의 실험을 실시해야 하기 때문에 많은 시간 및 비용이 필요하다. 본 연구에서는 비대칭 H형강 합성보 단면에서 내화성능에 가장 큰 영향을 미치는 부분을 열전달해석을 수행하여 확인하고, 이후 단면변경을 통한 내화성능 향상 추세를 열전달해석 및 비선형구조해석으로 확인하여 1시간 내화성능을 가질 수 있는 변경된 단면을 제시하였다.

• 지역사회간호학회지
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• 제11권2호
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• pp.499-512
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• 2000

The number of deliveries by cesarean section has increased internationally. However, The cesarean section rate is different by country to country. It is because each country has different social and cultural background and. practices its unique delivery policies. Hence, it is very important to understand the uniqueness that one country faces related with the cesarean section. In Korea, there have been many researches on the clinical. maternal. hospital and community factors and so on. However, few studies have attempted to reveal the physician factors in Korea because it is difficult to approach hospital records. So, in this study, the physician factors that influence the increase of cesarean section rate in Korea was investigated, and preliminary research agenda for policy establishment to keep the cesarean section rate from excessive increase was provided. In this study, all 2744 cesarean section deliveries performed by 36 physicians at the hospital was considered. and detailed delivery records of 12 months selected randomly from January 1996 to August 1998 was reviewed retrospectively. Chi-square analysis is used to examine the homogeneity of distribution of maternal, fetal, and clinical factors. In addition, multiple regression analysis is used to examine the effect of physician characteristics on the cesarean section rate. Physician characteristics as independent variable and the cesarean section rate as dependent variable was put in this analysis. Follows are the results of this study. 1) Total cesarean section rate is 34.8%. primary cesarean section rate is 12.5 % and repeated cesarean section rate is 22.3 %. Among the indications for the primary cesarean section, 15.6 % is for breech presentation. 40.2 % is for dystocia. 7.6 % is for fetal distress. and 36.6 % is for others. 2) There is positive correlation between physician's age and the cesarean section rate (p<0.001). And statistically significant correlation is found between the physician's educational attainment and the cesarean section rate (p<0.001). A physician with Ph.D degree has lower cesarean section rate than a physician with B.A only and M.A. degree (p<0.001). However. physician's gender, location of graduated university. position at the hospital, and the religious belief were not shown statistically significant relations with the cesarean section rate. 3) Among all cesarean sections in this study, only 15.4 % is performed during weekend. While 18.2 % is performed on monday only. This suggests that physicians may not prefer weekend operation of cesarean section. In addition, 86.1 % among all cesarean section operations is performed from 6 a.m. to 6 p.m. So the cesarean section rate could be related with a day of the week and a time of the day. From this results. there is a possibility that the physicians' personal comfort may influence the cesarean section rate.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2006년도 정기 학술대회 논문집
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• pp.764-771
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• 2006

The use of 3-D finite elements for the eigen analysis of beam-like structures with arbitrary section shape may not be practical in certain cases, from the aspect of CPU time. In this connection, this paper presents a systematic algorithm for decomposing an arbitrary section into finite number of basic ones and computing essential sectional quantities required for the eigen analysis using the beam theory. The numerical accuracy of the proposed method is assesed from the comparison with the 3-D finite . element method.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(I)
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• pp.291-294
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• 2005

In the present study, a numerical analysis was performed for interior connections of continuous flat plate to analyze the effect of column section shape on the behavioral characteristics of the connections. For the purpose, a computer program for nonlinear FE analysis was developed, and the validity was verified. Through the parametric study, the variations of shear stress distribution around the connection were investigated. According to the result of numerical analysis, the column section shape has a serious effect on the behavior of the connections. As the length of the cross section of column in the direction of lateral load increases, the effective area and the shear strength at the sides providing the torsional resistance decrease considerably. Therefore the strength model for the flat plate-column connections should be modified by considering the effect of column section shape on the behavior of the connections.

• Structural Engineering and Mechanics
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• 제68권1호
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• pp.67-80
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• 2018

Recently, U-section decks have been more and more used in metro and light rail bridges as an innovative concept in bridge deck design and a successful alternative to conventional box girders because of their potential advantages. U-section may be viewed as a single vent box girder eliminating the top slab connecting the webs, with the moving vehicles travelling on the lower deck. U-section bridges thus solve many problems like limited vertical clearance underneath the bridge lowest point, besides providing built-in noise barriers. Beam theory in mechanics assumes that plane section remains plane after bending, but it was found that shearing forces produce shear deformations and the plane section does not remain plane. This phenomenon leads to distortion of the cross section. For a box or a U section, this distortion makes the central part of the slab lagging behind those parts closer to the webs and this is known as shear lag effect. A sample real-world double-track U-section metro bridge is modelled in this paper using a commercial finite element analysis program and is analysed under various loading conditions and for different geometric variations. The three-dimensional finite element analysis is used to demonstrate variations in the transverse bending moments in the deck as well as variations in the longitudinal normal stresses induced in the cross section along the U-girder's span thus capturing warping and shear lag effects which are then compared to the stresses calculated using conventional beam theory. This comparison is performed not only to locate the distortion, warping and shear lag effects typically induced in U-section bridges but also to assess the main parameters influencing them the most.