• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 1998년도 춘계학술대회논문집
• /
• pp.175-178
• /
• 1998

Tracings streamlines in global coordinate, especially with finite element mesh, requires much computation due to C0 continuity of velocity field. In this study, a new approach is presented for the determination of streamlines from velocity field obtained by FE analysis. It is shown that amount of calculation can be drastically reduced and boundary of element can be easily treated. The approach is applied to the problem of free surface of deforming workpieces in shape rolling.

• 대한조선학회지
• /
• 제8권1호
• /
• pp.1-16
• /
• 1971

Ship hulls obtained by the streamline tracing method usually have characteristically drooped keel lines at the bottom, and a flattening of these bottoms would contribute considerably in utilizing these analytically obtainable hull forms in practical usage. In this dissertation, the author deals with a study on the determination of a practical hull form by the streamline tracing method with a particular emphasis on the bottom flattening problem. Investigations are centered around the form and the terms of bottom doublet distribution. Several examples are computed by varying bottom doublet sheet systematically while the main side source distribution is kept the same. The following conclusions are obtained based on those computed results: after the strength of a bottom doublet sheet can be determined more easily and efficiently by employing the concept of a control plane. If the distance from the distributed plane of the bottom doublet sheet to the control plane is defined as the control distance, the strength of the bottom doublet sheet, the flatness of traced lines, and the increment of the beam length ratio by adding the bottom doublet sheet are all related to the control distance by linear equations near the design bottom. It is observed that a better result can be obtained by using a "line-sampling method" for ${\zeta}_K>2T/L$, and a "plane-sampling method" for ${\zeta}_K{\leq}2T/L$, provided that the check points are sampled in the range ${\xi}{\leq}0.7$.

• 대한조선학회지
• /
• 제8권2호
• /
• pp.45-52
• /
• 1971

The object of this study is to determine theoretical ship form which minimises wave making resistance under given conditions and developes theoretical ship form planing. By employing the streamline tracing method 1967's Korean Standard Ship Form of 10,000 G.T. linear has been reformed and tested at towing tank of Inha Institute of Technology. The design process and the reformed ship forms had been reported already in reference[4]. In this paper, resistance performance is experimentally observed with three models(original, theoretical, and reformed form) of 2m long in the towing tank, and total resistance of theoretical and reformed ship forms are decreased by 24.9% and 19.7% and wave making resistance by 66.4% and 47.7% compare to original ship form respectively.

• 대한조선학회지
• /
• 제14권2호
• /
• pp.1-9
• /
• 1977

Streamlines around a ship's hull can be calculated by using streamline tracing method replacing the ship section with distribution of singularity. The influence of frame lines on the stream surrounding a hull surface, however, can not be found. Jinnaka studied on streamlines for Lewis form by applying the slender body theory. The influence of frame lines on stream surrounding a hull surface is well found in Jinnaka's method. In this paper streamline calculation method for chine type has been developed by using conformal transformation and applying slender body theory as Jinnaka did. Three kinds of model-one of series 62 for chine type, V.L.C.C. and high speed craft built in Korea for Lewis form-were used for streamline calculation;

• 한국원자력학회:학술대회논문집
• /
• 한국원자력학회 1997년도 춘계학술발표회논문집(1)
• /
• pp.304-309
• /
• 1997

A method to mitigate the thermal stratification flow of a horizontal pipe line is proposed by heating external bottom of the pipe with electrical heat tracing. Unsteady two dimensional model has been used to numerically investigate an effect of the external Denting to the thermally stratified flow. The dimensionless governing equations are solved by using the control volume formulation and SIMPLE algorithm. Temperature distribution, streamline profile and Nusselt numbers of fluids and pipe walls with time are analyzed in case of externally heating condition. no numerical result of this study shows that the maximum dimensionless temperature difference between the hot and the cold sections of pipe inner wall is 0.424 at dimensionless time 1,500 ann the thermal stratification phenomena is disappeared at about dimensionless time 9,000. This result means that external heat tracing can mitigate the thermal stratification phenomena by lessening $\Delta$ $T_{ma}$ about 0.1 and shortening the dimensionless time about 132 in comparison with no external heat tracing.rnal heat tracing.

• 에너지공학
• /
• 제6권2호
• /
• pp.119-128
• /
• 1997

수평배관의 열성층 유동을 완화하기 위하여 아래부분에 Heat Tracing을 한 수평배관의 외부 가열에 의한 열성층 유동과 열전달 특성을 수치적으로 해석하기 위하여 비정상 2차원 모델을 이용하였다. 무차원 지배방정식은 제어체적방법과 SIMPLE 알고리즘을 사용하여 해를 구하였다. Heat Tracing이 있는 수평배관 내부 열성층 유동의 등온선, 유선분포, Nusselt수, 온도 분포를 해석하였다. 무차원 시간 1,500에서 최대 무차원 온도차가 0.424로 계산되어졌고 무차원 시간 9,000 이후에는 열성층 현상이 없어졌다.

• 대한조선학회지
• /
• 제10권2호
• /
• pp.19-28
• /
• 1973

This paper deals with a problem for determining the bulbous bow ship from which pertains to the study of the theoretical ship form planing method. In this paper has been determined the bulbous bow ship form which is a similar in geometric particulars with the conventional liner ship G.T.10, 000 by adopting the variable method for finding the optimum ship form by A.Y.C. Lee and the streamline tracing method by T. Inui and P.C. Pien. Each resistance performance is examined by the towing test and is compared with one another. The followings are the outcome of this study: Among the 5 type models, the bulbous bow ship form M.S. B 1120 is the most excellent for the resistance performance. The effect for the wave resistance is very sharp according to the difference of the bottom flattening of theoretical ship form. The optimum value of the bulbous bow for wave resistance can be obtained by the variable method mentioned above, and for the series of(Main hull+Bulb)opt., ${\alpha}=75/25$, the value is $f{\approx}0.11$.

• 산업공학
• /
• 제21권2호
• /
• pp.177-188
• /
• 2008

Recently, due to emerging technologies such as radio frequency identification(RFID), global positioning system(GPS), and wireless mobile communication technologies, it is possible to build up the infrastructure for tracking and tracing product logistics data at any place and at any time. However, for implementing the infrastructure, it is necessary to develop a suitable management method for product logistics data. To this end, this study deals with a resource description framework(RDF) based modeling and application method for product logistics data in the ubiquitous environment. It will give us the capability to control product logistics data, which leads to streamline logistics operations.