• 한국정밀공학회지
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• 제21권6호
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• pp.122-130
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• 2004

It is well known that a specific experimental method, the Split Hopkinson Pressure Bar (SHPB) technique is a best experimental technique to determine the dynamic material properties under the impact compressive loading conditions with strain-rate of the order of 10$^3$/s∼10$^4$/s. This type of experimental procedure has been widely used with proper modification on the test setups to determine the varying dynamic response of materials for the dynamic boundary conditions such as tensile and fracture as well. In this paper, dynamic compressive deformation behaviors of a rubber and an Ethylene Copolymer materials widely used for the isolation of vibration from varying structures under dynamic loading are estimated using a Split Hopkinson Pressure Bar technique.

• 충청수학회지
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• 제32권3호
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• pp.261-280
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• 2019

We apply a reduced-order method based on B-spline Galerkin finite elements formulation to Rosenau-RLW equation for the first time and explain their process in detail. The ensemble of snapshots is very large generally, and it is difficult to apply POD to the ensemble of snapshots directly. Hence, we try to pick up important snapshots among the whole data. In this paper, we represent three different reduced-order schemes. First, the classical POD technique is examined. Second, (equally sampled snapshots) are exploited for POD technique. Finally, afterward sampling snapshots by CVT, for those snapshots, POD technique is implemented again.

• Clinics in Shoulder and Elbow
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• 제16권1호
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• pp.58-62
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• 2013

서론: 최근 임상 연구와 논문의 활성화 속에 높은 신뢰도를 보장하는 방법을 따르는 예들은 아직 많지 않다. 이에 연구의 편향을 최소화하는 무작위 추출의 개념과 바른 방법에 대해 알아보고자 한다. 대상 및 방법: 최근까지 발표된 무작위 추출에 대한 문헌 고찰을 통해 무작위 추출의 기본 개념 및 필요성을 정리하고 바른 무작위 추출을 위한 조건 및 무작위 추출의 종류별 방법들(단순 무작위 추출, 순열화 블록 무작위추출, 계층화)에 대해 살펴 보았다. 결과 및 결론: 무작위 추출은 임상 연구에서 편향을 줄이고 통계적 검사를 이용한 자료 분석의 보장된 유효성을 제공한다. 이렇듯 보다 신뢰도 높은 연구 결과를 도출해 낼 수 있는 방법인 무작위 추출에 대한 개념 재정립 및 바른 무작위 추출 방법의 제안은 연구자들에게 꼭 필요한 과정이라 할 수 있겠다.

• 대한의용생체공학회:의공학회지
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• 제16권4호
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• pp.425-430
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• 1995

핵자기 공명 뇌기능 영상에서 상관관계를 이용한 데이터 해석기법이 많이 사용되고 있다. 이 논문에서 새롭게 제안된 CLT 기법은 상관관계(CCT)를 이용한 기법을 변화시켜서, 이 CCT기법의 단점을 보완하고자 하였다. CLT기법은 다음의 두 단계로 이루어진다. 첫째, 잡음을 포함한 CCT기법의 상관계수결과로 부터 잡음은 제거하고 실제 자극반응 픽셀들은 추출한다. 둘째, 이산적인 분포를 가지는 반응 픽셀들을 두 가지의 선별법으로 군집을 이루도록 한다. 이 CLT기법을 이용해서 실제 자극에 반응하는 픽셀들은 서로 모이게 하였고, 잡음에 기인한 오류의 픽셀들은 제거 되어질 수 있었다. 본 논문에서 제안된 CLT기법은 기존의 다른 기법에 비해 여러 잇점이 있고, 특히 잡음에 강한 특성이 있다.

• Archives of Plastic Surgery
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• 제38권3호
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• pp.273-278
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• 2011

Purpose: It has always been an aspiration for Asians to look more balanced and feminine, considering their facial features regarding relatively flat midface with marked prominences of the zygoma. Many studies have been dealt in this subject. However, the authors would like to emphasize the concept and introduce the technique of repositioning of the malar complex to a cosmetically beneficial point and stationing it on proper position by fixation on zygoma body and arch. Methods: From January 1998 to December 2007, this method was performed in 50 patients of mild to moderate prominence and malposition of the malar complex. A simplified technique of lateral orbital osteotomy and oblique osteotomy on zygomatic arch through intraoral and preauricular incision was developed. Then, liberal malar complex can be moved to a supero-posterior direction and repositioned to a more cosmetically beneficial point. To maintain the stationed position and to protect from vector affected by the attached masticating muscle to zygomatc bone, fixation was done on both zygoma body and arch. Results: We have obtained satisfactory results using this procedure without any observable complications. The advantages of this procedure are proper exposure, inconspicuous scar, safe, more natural contour, improved stability, and shorter healing time. Conclusion: The authors suggest that reduction malarplasty should be approached with underlying concept of repositioning and fixation. In mild moderate malar prominent cases, our technique will provide with maintenance of aesthetic concept, equal to the malar reduction performed under coronal approach and provide with more natural facial contour with stability even with less invasive surgical approach.

• 한국기계가공학회지
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• 제13권1호
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• pp.85-91
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• 2014

The rotation of a spindle unit must be accurate for high-quality machining and to improve the quality of the machine tools. Therefore, the proper measurement of the rotation accuracy and ensuring a proper analysis are very important. Separate processes are necessary because spindle errors and roundness errors associated with the test balls can both factor into the measured rotation error values. We used three methods to discern test ball errors and analyzed which could be deemed as the most proper technique in a test of the rotation accuracy of the main spindle of a machine tool.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집B
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• pp.423-425
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• 2001

The Proper Orthogonal Decomposition (POD) technique was applied to investigate the effects of Reynolds number and the characteristics of the organized motions or coherent structures as a function of downstream position from x/D=2 to 6 in a turbulent axisymmetric shear layer at Reynolds numbers of 78,400, 117,600, and 156,800. Data were collected simultaneously using the 138 hot-wire probe used by Citriniti and George (2000). The POD was then applied to a double Fourier transform in time and azimuthal direction of the double velocity correlation tensor. The lowest azimuthal mode for all POD modes, which dominated the dynamics at x=D = 3 in the previous experiments, dies off rapidly downstream. This is consistent with a trend toward homogeneity in the downstream evolution, and suggests that some residual value may control the growth rate of the far jet. On the other hand, for the higher azimuthal modes, the peak shifts to lower mode numbers and actually increases with downstream distance. These mixing layer data, normalized by similarity variables for the mixing layer, collapse at all downstream positions and are nearly independent of Reynolds numbers.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2004년도 임시총회 및 추계학술발표회
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• pp.223-226
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• 2004

The importance of a proper sample preparation and analysis technique has getting attention due to the complicity of toxic elements of interest from environmental samples depend on analytical purposes. It is critical to use proper analytical method to evaluate trace elements concentration in many environmental samples especially for making remediation decisions. Therefore, it is critical to apply a proper sampling and analytical method such as EPA publication SW-846 (Test Methods for Evaluating Solid Waste, Physical/chemical Methods). The objective of this study was to compare the USEPA Methods 3050B, modified 3050B, 305 la, and KBSI method (modified EPA 3052 Method) in term of recovery rate of metals. The NIST SRM (Montana soil) was used to compare the extraction and digestion efficiency. After sample has been collected the analysis were achieved by ICP-MS (Elan 6100, Perkin Elmer) as well as ICP-AES (Ultima 2C, JY) for trace elements and major elements.

• 한국주조공학회지
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• 제20권6호
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• pp.400-406
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• 2000

Computer simulation for the predictions of casting defects is very important to produce high quality castings with less cost. Complicate shaped Al solenoid housing part was selected to be cold chamber die cast and a numerical simulation technique was applied for the optimization of the chill vent position and gating. A first design led to insufficient central flow. This flow left the last filled areas falling into the inner portion of the part. And last filled area did not fit the chill vent position. So these resulted in a high possibility of air entrapment in the casting and the design was not proper for the part. The design was improved by using a proper gating system, a more chill vent and proper overflow positions. New design provided a homogenous mold filling pattern and the last filled areas that being located at the overflow and chill vent. Casting plan which produce good quality solenoid housing part was established by using the computer simulation.

• 한국재료학회지
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• 제30권12호
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• pp.693-700
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• 2020

Direct water quenching technique can be used in hot stamping process to obtain higher cooling rate compared to that of the normal die cooling method. In the direct water quenching process, setting proper water flow rate in consideration of material thickness and the size of the area directly cooled in the component is important to ensure uniform microstructure and mechanical properties. In this study, to derive proper water flow rate conditions that can achieve uniform microstructure and mechanical properties, microstructure and hardness distribution in various water flow rate conditions are measured for 3.2 mm thick boron steel sheet. Hardness distribution is uniform under the flow condition of 1.5 L/min or higher. However, due to the lower cooling rate in that area, the lower flow conditions result in a drastic decrease in hardness in some areas in the hot-stamped part, resulting in low martensite fraction. From these results, it is found that the selection of proper water flow rate is an important factor in hot stamping with direct water quenching process to ensure uniform mechanical properties.