• 한국정밀공학회지
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• 제13권12호
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• pp.78-85
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• 1996

The determination of the optimum biarc curve passing through a given set of points along involute curve is studied. The method adopted is that of finding the optimum no. of span and the optimum length of the span such that the error between the biarc curve and involute curve is minimum. Irregular curve span method is effectively used to describe the involute curve with reduced length of NC-Code.

• 대한수학회보
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• 제60권5호
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• pp.1265-1280
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• 2023

The aim of this paper is to investigate Betchov-Da Rios equation by using null Cartan, pseudo null and partially null curve in Minkowski spacetime. Time derivative formulas of frame of s parameter null Cartan, pseudo null and partially null curve are examined, respectively. By using the obtained derivative formulas, new results are given about the solution of Betchov-Da Rios equation. The differential geometric properties of these solutions are obtained with respect to Lorentzian causal character of s parameter curve. For a solution of Betchov-Da Rios equation, it is seen that null Cartan s parameter curves are space curves in three-dimensional Minkowski space. Then all points of the soliton surface are flat points of the surface for null Cartan and partially null curve. Thus, it is seen from the results obtained that there is no surface corresponding to the solution of Betchov-Da Rios equation by using the pseudo null s parameter curve.

• 제어로봇시스템학회논문지
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• 제12권10호
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• pp.1012-1017
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• 2006

By breaking the symmetry of the velocity profile in the S-curve, we developed a fast starting and smooth ending motion profile, named asymmetric S-curve(AS-curve). The problem for generating motion profile is formulated, and the algorithm for the AS-curve is derived and the flow chart of the AS-curve is illustrated. By various simulations, the derived algorithm is tested and shows the validity. This AS-curve can be applied to the high precision machines where fast and vibrationless motion is required in the near future.

• 복식
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• 제50권
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• pp.5-22
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• 2000

The study on the past costume should be done first for the creation of new style of fashion. That is one of the reasons why we have to annalize characteristic style in each period. Before the latter of nineteenth century one must have made the costume by draping design. Because the complicated clothes can be expressed by draping deign think that the subject draping design is even more important than other subject. But there haven't been the studies that analyzed the pattern of Art Nouveau style by draping design in Korea. Art Nouveau style is a certain one that was relatively more changeable than the ones of other periods. The purpose of this study is the analysis about the patterns of hourglass and S-curve style which represented the Art Nouveau style. The results of the study summarized as follows. 1. Bodice pattern : In the front Hourglass silhouette has the princess line for fitting bodice while S-curve silhouette has the wide midriff due to the blousing. There is the yoke in S-curve one. In the pattern of back bodice we can't see the much differences but Hourglass silhouette is used the princess line like the front one while S-curve is made use of the waist darts for fitting back. 2. Sleeve pattern : Hourglass silhouette is made of two pieces the upper part and lower part besides S-curve is consisted of one pieces. The former has the big upper part in order to the emphasis of the shoulder and the tight lower part. The latter is the tight sleeve that similar to the basic sleeve pattern at present. 3. Skirt pattern: There is partially a gored line in the front skirt in Hourglass silhouette however S-curve silhouette is consisted of the six pieces gored skirt. At this part we can also see the fact that s-curve is more complicated than Hourglass silhouette. 4. Others: Wecan find out the differences between Hourglass and S-curve pattern easily at the parts of the collar flounce wing and so on. Summing up, the patterns of S-curve style are more expanded than those of Hourgalss style for the most part.

• 농업과학연구
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• 제25권2호
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• pp.247-259
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• 1998

선행하중공법과 병행하여 연직배수재를 설치한 연약지반에서 초기에 신뢰성 있는 최종 침하량을 예측할 수 있는 방법을 확립하기 위하여, 실측자료를 이용한 역해석에 의해서 점증재하와 일시재하로 고려하여 Curve fitting 방법으로 역해석한 결과를 비교분석하고, 쌍곡선방법, Tan의 방법, Asaoka방법, Monden방법등으로 예측한 최종침하량과 비교하여 다음과 같은 결론을 얻었다. 1. 점증재하로 성토된 연약지반에 대해서 일시재하와 점증재하에 의한 예측 침하곡선이 일치하는 시간은 성토개시일로부터 성토기간의 약 2배 정도의 시간이 경과한 이후로 나타났다. 2 연직 드레인이 타입된 지반에 대해서 쌍곡선 방법, Tan의 방법, Asaoka방법, Monden방법, Curve fitting I, Curve fitting II(simple), 그리고 Curve fitting II(Carrillo)방법에 의하여 해석한 결과, Curve fitting II(simple) 방법을 기준으로할 때, 쌍곡선방법은 26~55%정도 과다추정되었고, Tan의 방법은 6~20%정도 과대 추정되었고, Monden방법은 Tan의 방법과 유사하게 나타났으며, Curve fitting I방법과 Asaoka방법은 최대 10%의 차이를 나타내었다. 3. 역해석에 의해서 최종침하량을 예측할 경우에 Asaoka 방법, 일시재하에 의한 Curve fitting I방법, 점증재하에 의한 Curve fitting II방법 등을 사용하는 것이 적합하다고 판단된다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집A
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• pp.834-840
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• 2001

Gear is general mechanical elements that used for power transmission between two shafts that interval is comparatively short. and it delivers big power as accurate ratio of speed. The profile of Spur gear which is the most basic factor is divided into Trochoidal fillet curve and Involute curve. Involute curve is used a lot of a shaped curve of machine parts such as a gear, a scroll compressor and a collar of centrifugal pump. However, It is poor to study the modeling of Trochoidal fillet curve and the three dimensions model shaped mathematical curve. This paper describes a mathematical model of profile shifted involute gear. and this model is based on Camus's theory. We draw three dimensions gear have accurate mathematical function using ADS, VisualLISP. and To check accuracy and perfection, we make a program of checking Interference. and use for this study.

• 소성∙가공
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• 제29권6호
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• pp.316-322
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• 2020

The flow stress curve is usually determined via uniaxial tensile or simple compression test. However, the flow stress curve up to high strain cannot be obtained using these two tests. This study presents a simple method for obtaining the flow stress curve up to high strain via FE analysis, a simple compression test, and an indentation test. In order to draw the flow stress curve up to high strain, the indentation test was carried out with the pre-stained specimen using the simple compression test. The flow stress curve of Al6110 was evaluated up to high strain using the proposed method, and the result was compared with the flow stress curve of the uniaxial tensile test of the initial material.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집E
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• pp.789-794
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• 2001

In this study, a program for the off-design performance prediction of multi-stage axial-compressors is developed based on stage-stacking method. To account for the increased losses at off-design conditions, generalized performance curve is applied. The purpose of this study is to investigate the influence of the choice of generalized performance curve and stator exit angle. For this purpose, we tested various generalized performance curves and stator exit angles. In conclusion, Muir's pressure coefficient curve gives a good prediction results regardless of the efficiency curve for a low-stage compressors. On the other hand, for high-stage compressors, The combination of Muir's pressure coefficient curve and Stone's efficiency curve gives a optimistic results. Stator exit angle has a small effect on overall performance curve.

• Structural Engineering and Mechanics
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• 제53권5호
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• pp.881-896
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• 2015

In this study, a method for fatigue performance estimation of deepwater steel catenary riser (SCR) under short-term vortex-induced vibration was investigated for selected S-N curves. General tendency between S-N curve capacity and fatigue performance was analysed. SCRs are generally used to transport produced oil and gas or to export separated oil and gas, and are exposed to various environmental loads in terms of current, wave, wind and others. Current is closely related with VIV and it affects fatigue life of riser structures significantly. In this regards, the process of appropriate S-N curve selection was performed in the initial design stage based on the scale of fabrication-related initial imperfections such as welding, hot spot, crack, stress concentration factor, and others. To draw the general tendency, the effects of stress concentration factor (SCF), S-N curve type, current profile, and three different sizes of SCRs were considered, and the relationship between S-N curve capacity and short-term VIV fatigue performance of SCR was derived. In case of S-N curve selection, DNV (2012) guideline was adopted and four different current profiles of the Gulf of Mexico (normal condition and Hurricane condition) and Brazil (Amazon basin and Campos basin) were considered. The obtained results will be useful to select the S-N curve for deepwater SCRs and also to understand the relationship between S-N curve capacity and short-term VIV fatigue performance of deepwater SCRs.

• 한국농공학회논문집
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• 제56권1호
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• pp.101-107
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• 2014

It has been known that Terzaghi's consolidation theory is not well consistent with the consolidation phenomenon on the soft clay ground, but this theory has still been adopted normally in practice because there is no method for estimating the consolidation settlement and rate easier than Terzaghi's theory. It is impossible to map whole part of consolidation settlement vs time curve to the curve of Terzaghi'z average degree of consolidation. If the primary consolidation and the secondary compression are happened same time, it would be useless of trying to find the end of primary consolidation, but it is needed for using Terzaghi's theory that the end of consolidation is determined to the time of beginning consistency between the final settlement analyzed with curve fitting and the experimented consolidation settlement.