• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 춘계학술대회 논문집
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• pp.201-204
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• 1999

Polarization mode dispersion (PMD) restrict the bend-width of single mode optical filer, and it is important parameter in the optical fiber having long-length. Although fiber has perfect circular symmetry, fiber bending, twisting and laws governing manufacture cause additional Polarization mode dispersion. The effect of polarization mode dispersion in general single mode fiber of long length is discussed in this paper. Measurement of PMD with random mode coupling were conducted in two kind of fibers using different laws governing manufacture and interferometric method.

• 대한치과교정학회지
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• 제28권5호
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• pp.813-823
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• 1998

마찰력은 치아이동시 활주이동부에 유해한 인자로 인식되어져 왔으나 치아이동에 저항하는 고정원에 있어서는 유리한 인자로 받아들여질 수 있다. 즉 마찰력이 작은 결찰법들을 이용하여 효과적인 치아이동을 도모하는 반면 마찰력이 큰 결찰법들을 이용하여 브라켓의 걸림에 의해 치아이동이 거의 일어나지 않게 하면 고정원을 강화할 수 있다. 인공타액하에서 시간경과에 따른 교정선과 브라켓 사이의 마찰력 변화, 탄성 모듈과 스테인레스 강 결찰선을 이용하여 각각 결찰양식을 달리 하였을 때의 마찰력 변화 그리고 결찰재의 재료를 달리 하였을 때의 마찰력 변화를 알아보기 위하여 .018"x.025" 슬롯의 상악 중절치용 standard edgewise twin 브라켓과 .017"x.022" 스테인레스 강 교정선을 탄성 모듈, .009" 스테인레스 강 결찰선 그리고 .012" 스테인레스 강 결찰선을 이용하여 다양하게 결찰하였다. 또한 통상적인 방법으로 결찰한 탄성 모듈 결찰군을 결찰 직후와 1주 간격으로 4주간 마찰력을 측정하여 다음과 같은 결과를 얻었다. ${\cdot}$탄성 모듈 whole tie시 시간경과에 따른 마찰력은 4주 경과시 가장 높았으나 3주, 2주, 1주, 결찰 직후간에는 통계학적으로 유의한 차이가 없었다 (p>0.n). ${\cdot}$탄성 모듈로 결찰시 마찰력은 twisting tie가 가장 높았고 double overlay tie, whole tie, half tie 순으로 나타났으나 twisting tie와 double overlay tie 간에는 통계학적으로 유의한 차이가 없었다 (p>0.05). ${\cdot}$스테인레스 강 결찰선으로 결찰시 half tie 군이 whole tie 군보다 낮은 마찰력을 보였으며 ligature tying plier로 결찰한 경우가 needle holder로 결찰한 경우보다 더 높았고 .012" 결찰선을 이용한 경우가 .009" 결찰선을 이용한 경우보다 더 높았다 (p<0.05). ${\cdot}$통상적인 방법으로 탄성 모듈과 스테인레스 강 결찰선을 이용하여 결찰한 경우 두 군간에 유의한 차이가 없었다(p>0.05).

• 한국정밀공학회지
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• 제25권8호
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• pp.72-79
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• 2008

To meet demand of big capacity and high speed rotation for washing machine, more stress from bending and twisting are complexly loaded onto the shaft supporting the horizontal drum, causing problems in fracture strength and fatigue life. Shafting system is mainly divided into flange and shaft. Shaft and flange connected by inserting shaft serration into flange on the process of die casting. When the system is operating, the gap is formed between serration and flange. But, Serration has various design factors and the optimal values can't be easily determined. Using a design of experiment (DOE) based on the FEM (Finite Element Method), this study was performed investigating the interaction effect between the various design factors as well as the main effect of the each design factor under bending, twist and vibration and proposed optimum design using box-behnken method among response surface derived from regression equation of simulation-based DOE.

• 대한기계학회논문집A
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• 제31권5호
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• pp.601-608
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• 2007

To meet demand of big capacity and high speed rotation for washing machine, more stress from bending and twisting are complexly loaded onto the shaft supporting the horizontal drum, causing problems in fracture strength and fatigue life. Shafting system is mainly divided into flange and shaft. Flange is located between the drum and shaft, transferring power from the shaft to drum, and acting as a supporter of the back of the drum. Because section of flange has various design factors according to configuration of flange, the optimum conditions can’t be easily determined. Using a design of experiment (DOE), this study was performed investigating the interaction effect between factors as well as the main effect of the each design factor under bending and twist and proposed optimum condition using center composition method among response surface derived from regression equation of simulation-based DOE.

• 멤브레인
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• 제30권1호
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• pp.66-77
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• 2020

본 연구에서는 정삼투 중공사막 모듈에서 중공사막의 가닥을 비틀어 배치하였을 때의 효과를 알아보기 위해 CFD전산 유체 역학 프로그램을 통해 5개의 다른 각도로 비틀린 중공사막 모듈을 설계하고 시뮬레이션하여 비틀리지 않은 모듈과 비교하였다. 실험 결과, 중공사막이 비틀렸을 때, 모듈 내부의 유도 용액의 농도가 비틀리지 않을 때에 비해 고르게 분포하였다. 모듈 입구의 압력은 중공사막의 비틀림과 관계없이 일정한 값을 보였지만 출구의 압력은 중공사막이 비틀린 정도가 커질수록 증가하는 추세를 보였다. 출구의 압력이 높아짐에 따라 막 내부의 유체 속도가 감소하고 모듈 체류 시간이 증가하여 막사이의 물질 교환이 원활하게 이루어질 것으로 예측된다. 이는 결과적으로 막이 비틀려 있을 때의 모듈 플럭스가 투과 수량이 차지하는 비율이 그렇지 않을 때에 비해 2배 증가하였다.

• Korean Journal of Acupuncture
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• 제26권4호
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• pp.23-38
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• 2009

Objectives : The purpose of this study was to identify the effect of the tonification & sedation manipulation for LI4 and KI7 on lacking of sweating in cold environment. Methods: The participants were divided into 3 groups as intact group without acupuncture, acupuncture group inserting and twisting with LI4 tonificaton and KI7 sedation method(LI4-tonify KI7-purge) and acupuncture group inserting and twisting with LI4 sedation and KI7 tonificaton method(LI4-purge KI7-tonify). We obtained baseline data at cold condition with the temperature $14{\pm}1^{\circ}C$. After making the participant staying in cold condition for 10 minute, we measured sweating rate in skin surface, body temperature, oxygen saturation, pulse rate, systolic blood pressure, diastolic blood pressure, deoxy-Hb and oxy-Hb in subcutaneous. Results : After acupuncture in cold environment, the sweating rate in skin surface significantly decreased in KI7-purge LI4-tonify group comparing the intact groups. The body temperature significantly increased in LI4-tonify KI7-purge and LI4-purge KI7-tonify groups comparing the intact group. The oxygen saturation significantly increased in LI4-tonify KI7-purge group comparing the intact group. Conclusions : These findings indicated that LI4 tonificaton and KI7 sedation method(LI4-tonify KI7-purge) could be effective for production of sweating in cold condition.

• Advances in nano research
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• 제12권5호
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• pp.529-547
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• 2022

Graphene is one of the strongest, stiffest, and lightest nanoscale materials known to date, making it a potentially viable and attractive candidate for developing lightweight structural composites to prevent high-velocity ballistic impact, as commonly encountered in defense and space sectors. In-plane twist in bilayer graphene has recently revealed unprecedented electronic properties like superconductivity, which has now started attracting the attention for other multi-physical properties of such twisted structures. For example, the latest studies show that twisting can enhance the strength and stiffness of graphene by many folds, which in turn creates a strong rationale for their prospective exploitation in high-velocity impact. The present article investigates the ballistic performance of twisted bilayer graphene (tBLG) nanostructures. We have employed molecular dynamics (MD) simulations, augmented further by coupling gaussian process-based machine learning, for the nanoscale characterization of various tBLG structures with varying relative rotation angle (RRA). Spherical diamond impactors (with a diameter of 25Å) are enforced with high initial velocity (V_i) in the range of 1 km/s to 6.5 km/s to observe the ballistic performance of tBLG nanostructures. The specific penetration energy (E_p^*) of the impacted nanostructures and residual velocity (V_r) of the impactor are considered as the quantities of interest, wherein the effect of stochastic system parameters is computationally captured based on an efficient Gaussian process regression (GPR) based Monte Carlo simulation approach. A data-driven sensitivity analysis is carried out to quantify the relative importance of different critical system parameters. As an integral part of this study, we have deterministically investigated the resonant behaviour of graphene nanostructures, wherein the high-velocity impact is used as the initial actuation mechanism. The comprehensive dynamic investigation of bilayer graphene under the ballistic impact, as presented in this paper including the effect of twisting and random disorder for their prospective exploitation, would lead to the development of improved impact-resistant lightweight materials.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2001년도 춘계학술대회 논문집
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• pp.63-67
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• 2001

Springback after drawing and trimming is regarded as one of the most influential factors during forming structural frames since the part dimensions have dominant effect on assembly quality at later stages. In this study, analytical results were obtained from a commercial FEM package for an outer rear frame of an automobile. In terms of springback and twist the effect of forming process is compared and discussed between open and closed-ends forming

• 한국염색가공학회지
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• 제11권6호
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• pp.18-23
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• 1999

PET POY(pre-oriented-yam) were treated by false twister to high bulky. False twister have many processing parameters velocity ratio(VR), belt cross angle$(\theta)$, 1st heater temp. and K(twisting tension/untwisting tension). we analyzed the effect of properties of textured polyester yam on processing condition. Initial modulus, thermal stress, No. of snarl is decreased by 1st heater. In VR=1.97, Dry and wet shrinkage is increased but is decreased by 1st heater in VR=1.564. K/S and cristallinity tend to increase by decreasing VR.

• 대한기계학회논문집
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• 제12권4호
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• pp.662-669
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• 1988

본 연구에서는 기존 자동차 소음기를 모델로하여 여러가지로 형상을 변화시켜 가면서 음향학적인 소음감소특성을 실험적으로 해석하였다. 또한 자동차에 부착되는 소음기는 배기가스의 유동이 있는 상태에서 음파의 대류현상이 존재하므로 이에 대한 모델로서, 공기 유동이 있는 경우에 대하여 각종 소음기 모델의 소음 감소 특성을 유 동속도별로 측정하여 해석하였다.