• 한국수산과학회지
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• 제18권1호
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• pp.15-22
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• 1985

The study on computation time, accuracy, and convergency characteristic of the implicit finite difference method is presented with the variation of the space increment and time step in a two-dimensional transient heat conduction problem with a dirichlet boundary condition. Numerical analysis were conducted by the model having the conditions of the solution domain from 0 to 3m, thermal diffusivity of 1.26 $m^2/h$, initial condition of 272 K, and boundary condition of 255.4 K. The results obtained are summarized as follows : 1) The degree of influence with respect to the accuracy of the time step and space increment in the alternating-direction implicit method and Crank-Nicholson implicit method were relatively small, but in case of the fully implicit method showed opposite tendency. 2) To prescribe near the zero for the space increment and tine step in a two dimensional transient problem were good in a accuracy aspect but unreasonable in a computational time aspect. 3) The reasonable condition of the space increment and the time step considering accuracy and computation time could be generalized with the Fourier modulus increment, F, ana dimensionless space increment, X, irrespective of the solution domain.

• 한국해양공학회지
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• 제25권2호
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• pp.120-126
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• 2011

The fatigue damages in structural details of offshore plants can be accumulated due to various environmental loadings such as swell, wave, wind and current. It is known that load histories acting on mooring and riser systems show stationary and ergodic bimodal wide-banded process. This paper provides refined approach to obtain time signals representing stress range histories from wide-banded bimodal spectrum which consists of ideally narrow-banded and fully separated two spectrums. Variations of the probabilistic characteristics for time signals according to frequency and sampling time increments are compared with the reference data to be the probabilistic characteristics such as zero-crossing period, peak period, and irregularity factor obtained from an assumed ideal spectrum. It is proved that the sampling time increment more affects on the probabilistic characteristics than frequency increment. The fatigue damages according to the frequency and sampling time increments are also compared with the ones with minimum increment condition which are thought to be exact fatigue damage. It is concluded that the maximum sampling time increment to obtain reliable time signals should be determined that ratio of applied maximum sampling time increment and minimum period is less than approximately 0.08.

• 한국의류학회지
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• 제27권6호
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• pp.665-674
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• 2003

The purpose of this study was to develop a grading increment at armhole area by apparel CAD(Computer Aided Design) system. In developing a grading increment at armhole area, we analyzed ease values of armhole area in bodice and sleeve by manual drafting patterns of five sizes. We suggested grading increments applied Pythagorean theorem to development the grading increment of the armhole of sleeve. The results and discussions of this study were as follows: 1. In drafting each size, the ease values were not identical. It was difficult to draft perfectly the same armhole line shape between sizes. 2. According to our developed grading increments applied Pythagorean theorem, the ease values were identical between sizes and difference of the armhole length between sizes was also identical. 3. The grading formulas were made out for apparel CAD system. Once grading increment or formula is set in the computer, it can be easily altered to various clothing items at any time. The efficiency of grading work will be also improved and grading time will be reduced.

• 한국농공학회지
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• 제20권3호
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• pp.4750-4770
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• 1978

Under the various variations of the sample thickness, the load increment ratio and the load increment duration, this consolidation test of the clay in the Asan Bay was tried for the comparison with the standard consolidation test. The results gained are as follows; 1. The void ratio variations of the leached-clay samples were increasingly high, according as the sample thickness thinned and the load increment duration and the laod increment ratio increased. 2. The coefficient of consolidation were increased with the increment of the sample thickness, of the load increment ratio and of the load increment duration. Near the pre-consolidation load, the coefficient of secondary consolidation had the maximum value and lessened with the increment of the sample thicknss, and of the load increment duration 3. The value of the pre-consolidation load increased in proportion to the increment of the sample thickness and the decrease of the load increment ratio and the load increment duration. 4. The compression indices increased as the increment of load increased and decreased as the sample thickness increased. 5. The initial compression ratio increased as the sample thickness, the load increment ratio and the load increment duration decreased. The ratio of primary compression to the secondary decreased with the increment of the sample thickness and of the load increment ratio. 6. The time at the completion of psimary consolidation increased with the increment of the sample thickness and of the consolidation load, and with the decrease of the load increment ratio. 7. The compression indicses increaed as the sample thickness lessened and decreased as the load increment ratio increased. The coefficient of consolidation increased according as the sample thickness, the load increment ratio and the load increment duration went up. The settlement at the construction site should be calculated highly in proportion as the sample thickness lessened and the load increment ratio increased. The consolidation ratio is thought to be accelerated if the sample thickness and the load increment ratio becomes higher and the load increment duration longer.

• 한국농공학회지
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• 제30권3호
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• pp.38-50
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• 1988

carried out to present a rheology model which is able to treat time-dependent properties of clay. The results were summarized as follow ; 1. The slope (a(e1)) of deviator stress in strain rate test was independent on axial strain, and pore water pressure was decreased with increment of strain rate. 2. The pore water pressure in a stress relaxation condition was not changed when the strain rate before stress relaxation was 0.05%/min., but it was increased with increment of time when the strain rate before stress relaxation was 0.2%/min 3. The greater the stress condition (q/qmax) and the strain rate before creep test became, the greater the increment rate of axial strain in creep test became. 4. SEKIGUCHI's constitutive equation was slightly overpredicted while empirical equation proposed in the study was well coincided with measured values. 5. The constitutive equation induced by a strain function could be dealed with a behavior of the pore water pressure increased with increment of elapsed time after primary consolidation.

• 한국주조공학회지
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• 제13권5호
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• pp.432-440
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• 1993

Ductile cast iron has a good ductility and toughness than those of gray cast iron, because the shape of graphite is spheroidal. Also, it has been reported that, additional strengthening and toughening of the ductile cast iron can be obtainded from the proper combination of matrix structures by the heat treatment and addition of alloying elements. In this study the effect of special heat treatment and addition of alloying elements(Ni, Mo) on the multi-phase(ferrite-bainite-martensite) structures, strength and toughness of ductile cast iron were studied systematically. In water quenching from $770^{\circ}C$, the martensite volume(%) increased, but the ferrite volume(%) decreased with increment of Ni content. In as cast, pearlite volume(%) and hardness increased with increment of Mo and Ni contents. And with the increment of the destabilization austempering holding time, the bainite volume(%) increased but the martensite volume(%) decreased. As destabilization austempering holding time is same, bainite volume(%) decreased, martensite increased with the increment of Ni and Mo contents. The hardness and tensile strength decreased, but impact energy increased with the decrease of Ni and Mo contents, and increment of holding time of destabilization austempering treatment.

• 한국식품조리과학회지
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• 제16권5호
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• pp.453-459
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• 2000

Quality characteristics of Yaksik prepared with glutinuous rice soaked for different time lengths were investigated. Moisture contents increased with the increment of soaking time. In Hunter's color value, the lightness decreased and redness and yellowness increased by the increment of soaking time. Samples prepared with a commercial formula showed increased red and yellow colors due to the addition of caramel sauce. The firmness decreased with the increment of soaking time during storage. However, the samples prepared with 2 hr-soaking were retrograded rapidly. In peroxide value, there were no differences among samples. In microbiological evaluation, samples prepared with a commercial formula had prolonged shelf lives probably due to the preservatives contained. Samples prepared with 6 hr-soaking showed the highest score in sensory evaluation.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.773-777
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• 1995

This thesis attempt to explore the shape of stress wave propagation of 3-dimensional stress field which is made in the process of time increment. A finite element code about 3-dimensional stress wave propagation is developed for investigating the changing shape of the fracture by the impact load. The Finite Element Code, which is the solution for the 3-dimensional stress wave analysis, based on Galerkins and Newmark- .betha. method at time increment step. The tensile stress and compressive stress become larger with the order of the middle, the upper and the opposite layers when the impact load is applied. In a while the shear stress become larger according to the order of the upper, the middle and the opposite layers when impact load applied.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1545-1548
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• 2003

In rigid-plastic finite element method, there is a heavy computation time and convergence problem. In this study. static-explicit rigid-plastic finite element method will be introduced. This method is the way that restrict the convergence interval. In result, convergence problem and computation time due to large non-linearity in the existing numerical analysis method were no longer a critical problem. Also, we investigated the effect of punch stroke and the strain increment this method. It is expected that various results from the numerical analysis will give very useful information for the design of tools in sheet metal forming process.

• 한국방사선학회논문지
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• 제13권5호
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• pp.675-681
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• 2019

근골격계 수술 전 CT 촬영 후 3차원 체적영상을 Increment별로 구현하는 과정에서 시간이 많이 소요되지 않고 데이터의 양도 많지 않은 적절한 Increment를 찾아 제안하고자 한다. 이에 본 연구에서는 손, 무릎, 발인체팬텀을 CT로 검사후, MMWP 프로그램을 사용하여 3차원 체적영상을 구현하여 재현성 평가를 하였다. 첫 실험으로는 각 Increment에 따른 세 가지 인체팬텀 별 데이터양을 분석하였다. 두번째 실험으로는 재현성평가와 실측 길이를 비교하였다. Increment에 따라 각 팬텀별로 이미지 데이터양을 분석한 결과 Increment를 0.1mm 로 설정했을 때보다 1.0mm 로 설정하였을 때 1/10 정도로 데이터양이 줄어드는 것을 확인할 수 있었다. 구현성 평가를 하였을 때 손 팬텀은 0.7mm, 무릎 팬텀과 발 팬텀은 0.6mm 부터 gap이 생성되었고 실제 팬텀과 실측 길이를 비교하였을 때 길이가 많이 차이나서 구현성이 낮아지는 것을 확인할 수 있었다. Increment가 1.0mm 에 가까울수록 이미지 수가 적고, 3D 구현 시간이 적게 소요되지만 gap이 생성되면 구현성이 급격이 낮아지는 것을 확인할 수 있었다. 따라서 영상의 gap이 생성되기 전 Increment를 알아내어 적용하는 것이 수술 전 진단을 내리기에 가장 적합하다. 본 연구를 통해 CT 촬영후 VRT Rendering을 통한 3D 영상 구현시 정확한 Increment 설정을 증명할 수 있는 지표가 되기를 기대한다.