• Proceedings of the Korea Water Resources Association Conference
• /
• 2007.05a
• /
• pp.1803-1807
• /
• 2007

본 연구에서는 개념적인 강우-유출모형인 Tank 모형에 대하여 유역의 다양한 유출특성을 잘 반영할 수 있는 매개변수를 산정하는 데에 그 목적을 두었다. 이를 위한 최적화 알고리즘은 다목적 유전자 알고리즘인 NSGA-II를 선정하여 Tank 모형과 결합하였으며, 4가지의 목적함수를 대상으로 다양한 함수값을 나타내는 비지배관계의 최적군을 생산하였다. 수 백개로 나타나는 최적군의 다양한 해들 중, 특정 목적함수에 대하여서만 정도가 높거나 낮은 편협한 해들을 배제하고 두루 정도가 높은 값을 나타내는 소수의 비지배해들을 추출하기 위하여 선호적 순서화 기법이 적용되었다. 그 결과 많은 해들 중 단 4개의 해가 최우선해의 위치를 갖는 것으로 나타났으며, 이러한 방법론으로 최적화된 해의 적합성을 살펴보고자 국부최적화 기법인 Powell 방법과 기존에 널리 쓰여온 유전자 알고리즘인 SGA(Simple Generic Algoritm)의 결과와 비교 검정을 수행하였다. 비교한 결과 NSGA-II를 적용하여 산정된 매개변수가 4가지 목적함수 및 관측유량과의 통계치에서 두루 양호한 결과를 나타내었다. 또한 관측유량과 함께 도식하여 살펴본 결과, NSGA-II의 최우선해가 타 자동보정 기법에 비하여 상대적으로 관측치에 보다 잘 부합되는 모의유량을 계산하는 것으로 나타났다.

• Journal of the Korea Furniture Society
• /
• v.11 no.2
• /
• pp.25-35
• /
• 2000

This study was carried out to investigate the wood properties for development the proper uses of lesser-known tree species. The tested species are Tamiang(Hydnocarpus woodii) Bangelem (Strombosia zeylanica) and Kamasulan(Anisophyllea ferruginea) grown in Indonesia. fundamental wood properties such as anatomical, physical and chemical properties and characteristics related to wood processing were examined. The results are summarized as follows : These species are diffuse porous, interlocked grained and coarse textured wood. Exceptionally, texture of Tamiang is fine. The heartwoods of these species are not distinguished clearly to the sapwoods. These species have high specific gravity, high shrinkage, and excellent strength properties. However, Tamiang has moderate specific gravity. Sawing characteristics are poor for these species except Tamiang. Sawing characteristics is moderate for Tamiang. Drying characteristics are moderate for Tamiang and Bangelem, and Poor for Kamasulan. The surfacing characteristics by planer are moderate f3r all these species. Bending property and durability are poor. Ash content is low in Bangelem.

• Journal of Elementary Mathematics Education in Korea
• /
• v.14 no.1
• /
• pp.65-80
• /
• 2010

The aims of our study are to investigate the nature of mathematical reasoning and the teaching of mathematical reasoning in school mathematics. We analysed the process of shaping deduction in ancient Greek based on Netz's study, and discussed on the comparison between his study and Freudenthal's local organization. The result of our analysis shows that mathematical reasoning in elementary school has to be based on children's natural language and their intuitions, and then the mathematical necessity has to be formed. And we discussed on the sequences and implications of teaching of the sum of interior angles of polygon composed the discovery by induction, justification by intuition and logical reasoning, and generalization toward polygons.

• Journal for History of Mathematics
• /
• v.27 no.3
• /
• pp.197-210
• /
• 2014

Species like insects and fishes have, in many cases, non-overlapping time intervals of one generation and their descendant one. So the population dynamics of such species can be formulated as discrete models. In this paper various discrete population models are introduced in chronological order. The author's investigation starts with the Malthusian model suggested in 1798, and continues through Verhulst model(the discrete logistic model), Ricker model, the Beverton-Holt stock-recruitment model, Shep-herd model, Hassell model and Sigmoid type Beverton-Holt model. We discuss the mathematical and practical significance of each model and analyze its properties. Also the stability properties of stationary solutions of the models are studied analytically and illustratively using GSP, a computer software. The visual outputs generated by GSP are compared with the analytical stability results.

• Fire Science and Engineering
• /
• v.10 no.3
• /
• pp.10-18
• /
• 1996

In foreign country such as USA and Japan, considerable research has been done regarding the spread of smoke in room of fire involvement by using computer. but, in our country it has not been, so, this paper presents a detailed qualitative description of phenomena which occure during typical fire scenarios through numberical analysis. The governing equations are solved by using FVM method with non-staggered grid. The SIMPLE method for pressure-velocity couple and power-law scheme for convention terms are used. It shows that a plume is formed, hot plume gases impinge on the ceiling and they spread across it. then, it eventually reaches the bounding walls of the enclosure. It takes 20s for smoke to fill the enclosure.

• Culinary science and hospitality research
• /
• v.10 no.4
• /
• pp.67-83
• /
• 2004

한국음식이 미국 내에서 하나의 민족음식으로서 점차 인식되고 있음에도 불구하고, 미국인들이 지각하는 한국음식과 한국레스토랑의 인식과 관련한 연구는 미비한 실정이다. 지금까지 대부분의 연구는 한국을 방문한 외국인들이 지각하고 인식하는 한국음식에 관한 연구에 초점이 맞추어져 왔다. 그러므로, 한국음식과 한국레스토랑에 관한 미국인들의 인식과 한국레스토랑의 포지셔닝(positioning)에 관한 연구는 미국 내에서 한국레스토랑을 운영하는 메니져(manager)들에게 중요한 정보를 제공할 수 있을 것이다. 본 연구는 미국 마이애미 지역의 대학생들을 대상으로 하여 아시안 음식과 레스토랑에 관하여 대학생들이 지각하는 이미지를 확인하였으며, 인지된 대학생들의 아시안 레스토랑과 음식에 관한 이지미는 한국레스토랑의 포지셔닝과 비교분석하기 위하여 도식으로 표현되었다. 그리고 이러한 이미지 포지셔닝 연구는 남부 플로리다(South Florida) 지역에서 한국 레스토랑을 운영하는 메니져들에게 경쟁력 있는 마케팅 전략을 제시해 줄 수 있을 것이다. 따라서, 본 연구의 목적은 미국 마이애미 지역의 대학생들이 한국, 중국, 일본, 베트남, 태국 레스토랑과 음식을 어떻게 인식하고 있는가에 관한 기초 분석연구이다. 각 아시안 레스토랑의 포지셔닝을 확인하며, 본 연구에서 분석된 기초 자료들은 레스토랑 운영자들에게 중요한 마케팅 자료로 제공될 수 있을 것이다.

• Journal of the Korea Furniture Society
• /
• v.11 no.1
• /
• pp.13-23
• /
• 2000

This study was carried out to investigate the wood properties for development the proper uses of lesser-known tree species. The tested species are Kebambang(Pentace sp.), Bawang-bawang(Dysoxylum alliaceum Bl .), Garu buaya( Gonystylus brunescens A. Shaw)grown in Indonesia. fundamental wood properties such as anatomical, physical, mechanical and chemical properties and characteristics related to wood processing were examined. The results are summarized as follows : The woods of these species are diffuse porous, coarse textured, and interlocked grained. The heartwood of Kebambang is distinguished clearly to the sapwood, but the heartwood of other species are not distinguished clearly to the softwood. The woods of Kebambang and Bawang-bawang have the moderate weight density and the low strength properties, but Garu buaya has the high weight density and the high strength properties. The woods of these species has high shrinkage. The sawing characteristics of Kebambang are excellent but the other species are moderate. The machining characteristics by planer and drying characteristics of these species are moderate. These woods has poor characteristics in bending processing and decay durability. The wood of Bawang-bawang has high content of the extractives and lignin.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.33 no.4
• /
• pp.17-26
• /
• 2005

Numerical investigation has been made on the aerodynamic characteristics of supersonic air-launching rocket, as a new concept launching mechanism. Parametric study on the variations of launching velocity, incident angle and mounting location of the rocket has been performed using three dimensional Euler equations. Influential factors at separating stage of the rocket were extracted through comprehensive analyses, and, the response surface models were constructed for those factors. From the study, the aerodynamic behavior of the air-launching rocket at supersonic speed and useful guidelines for the optimal mounting location of the rocket have been obtained.

• Journal of the Korean Chemical Society
• /
• v.36 no.2
• /
• pp.223-229
• /
• 1992

Mechanistic studies on the metal-exchange reactions of sparteine copper(II) dichloride [$SpCuCl_2$] with Hg(II) ion and Hg(0) metal have been carried out with the aid of Cyclic Voltammetry and UV-visible spectrophotometry. The metal exchange reaction of $SpCuCl_2$ with both Hg(II) ion and Hg(0) metal follows pseudo-first order kinetics. Rate constants and activation parameters of metal exchange reaction have been evaluated and reported. Experimental results indicate that the rate determining step for the exchange reaction is the cleavage of Cu(II)-N bond in the transient binuclear complex of Cu(II) and mercury(II) bound to sparteine ligand.

• Computational Structural Engineering
• /
• v.7 no.2
• /
• pp.147-153
• /
• 1994

A method for shape design sensitivity analysis for axisymmetric shells of general shapes is developed. The basic approach is to divide the structures into many segments : For each of the segments, the formula for a shallow arch or shell can be applied and the results assembled. To interconnect those segments, the existing sensitivity formula, obtained for a variation only in the direction perpendicular to the plane on which the structure is mapped, has been extended to include a variation normal to the middle surface. The method follows the adjoint variable approach based on the material derivative concept as established in the literature. Numerical examples are taken to illustrate the method and the applicability to practical design problems.