• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1992년도 봄 학술발표회 논문집
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• pp.134-139
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• 1992

This study introduces simple derivation of optimum load factors based on both cornell's MFOSM (Mean First Order End Moment) methods and Lind - Hasofers AFOSM (Advanced First Order 2nd Moment) methods and demonstrates the relationship between the optimum reliability, the load factors, the probability distributions selected to model the load, and a measure of relative failure cost. Although some of the cost parameters cannot be evaluated accurately and the upper tail characteristics of the distributions of the random loads remain uncertainty, this optimum reliability formulation provides insight on which Parameters are most significant in selecting appropriate load criteria for structure design.

• 소성∙가공
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• 제16권6호
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• pp.432-437
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• 2007

Sidewall curl is the curvature that results from non-uniform through-thickness strain present in the sheet stamping process which involves material flow over a die radius. In order to understand and control sidewall curl for tight fit-up tolerances, an analytical model that can provide a reliable measure for the amount of curl would be very helpful. In this study, a model is developed based on the moment-curvature relationship during bending-under-tension operations. The analytical model includes the variables of applied tensile force, the yield strength, the elastic modulus, the bending radius, and the sheet thickness, which are the primary factors affecting sidewall curl during sheet stamping operations. For the accuracy of analytical model, six possible deformation patterns are proposed on the basis of material properties and bending geometries.

• 소성∙가공
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• 제16권6호
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• pp.438-442
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• 2007

Sidewall curl is the curvature that results from non-uniform through-thickness strain present in the sheet stamping process which involves material flow over a die radius. In order to understand and control curl for tight fit-up tolerances, an analytical model that can provide a reliable measure for the amount of curl would be very helpful. In this study, a model is developed based on the moment-curvature relationship during bending-under-tension operations. For the verification of analytical model, sidewall curl is experimentally measured after deformation of a strip using a bending-under-tension test system. The results show a consistent relationship between the theoretically predicted value and the experimentally obtained one, especially in regions of high curl.

• 제어로봇시스템학회논문지
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• 제2권3호
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• pp.220-228
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• 1996

This paper presents a extended stochastic Petri net (ESPN) model for CTN(Circulated Token with No duration) service in the data link layer of IEC/ISA fieldbus. It is assumed that a station on the fieldbus has a specified minimum token holding time, a finite capacity buffer, and one transmitter queue with the highest priority. The mean transmission (or service) time at a station and the mean token rotation time for the symmetric fieldbus system atr derived using the presented SPN model and the moment generating function. These performance measures are represented in terms of the minimum token holding time, the number of stations, the arrival rate of messages, and the mean length of messages. The presented performance measure are validated by computer simulations.

• 센서학회지
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• 제11권4호
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• pp.191-199
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• 2002

This paper presents the design concept, theoretical investigation, and fabrication of a six-degree of freedom (6-DOF) turbulent flow micro sensor utilizing the piezoresistive effect in silicon. Unlike other flow sensors, which typically measure just one component of wall shear stress, the proposed sensor can independently detect six components of force and moment on a test particle in a turbulent flow. By combining conventional and four-terminal piezoresistors in Si (111), and arranging them suitably on the sensing area, the total number of piezoresistors used in this sensing chip is only eighteen, much fewer than the forty eight piezoresistors of the prior art piezoresistive 6-DOF force sensor.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.283-284
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• 2006

In this paper 3-point weighing method is adopted to measure the unbalance moment of small-sized precision spinning elements using electronic scales with 0.1 mgf resolution. Firstly methods to eliminate the fixture error and to reduce the effects of frictional force that is known as side effect, are proposed. A measuring system is developed and various experiments are performed to verify the proposed approach. The measured and calculated values are analysed in statistical methods, and this provides the errors of the measuring system. The results show that the proposed theory and test procedures gives reliable unbalance moments and gravitational centers.

• 한국자동차공학회논문집
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• 제9권6호
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• pp.65-75
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• 2001

Modern vehicles require a high degree of refinement including good driveability. Vehicle driveability, which becomes a key decisive factor f3r marketability, is affected by many parameters such as engine control and the dynamic characteristics in drive lines. Therefore engine and drive train characteristics should be considered to achieve a well balanced vehicle response simultaneously. This paper describes experimental procedures which have been developed to measure engine torque and investigate shuffle characteristics. To analyze the vehicle dynamic behavior, fractional torques and inertia mass moment of engine, and drive train were measured. Shuffle characteristics during tip-in condition were investigated in an experimental vehicle at 2nd and 3rd gear stages. It was found that the shuffle characteristics were caused by sudden changes of engine torque and have a different vibration frequency with gear stage variation. Inertia mass moment of engine including flywheel rotation showed a key factor for the shuffle characteristics.

• 한국정보시스템학회지:정보시스템연구
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• 제29권1호
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• pp.289-301
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• 2020

Purpose This study analyzes whether Internet search of cryptocurrency has a causal relationship to return and volatility of cryptocurrency. Design/methodology/approach Google Trend was used as a measure of the level of Internet search, and the parametric tests of Granger causality in the 1st moment and the 2nd moment were adopted as the analysis method. We used Bitcoin's dollar-based price, which is the No. 1 market value among cryptocurrency. Findings The results showed that the Internet search measured by Google Trends has a causal relationship to cryptocurrency in both average and volatility, while there is a difference in causality and its degree according to the search area and category that Google Trend user should set. Because the Granger causality is based on the improvement of prediction, the analysis results of this study indicate that Internet search can be used as a leading indicator in predicting return and volatility of cryptocurrency.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.654-657
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• 2000

In the winding system, the constant tension control is too important. In this study, we've used a variable PID system as a function of a radius of winding roll. As a result, it was possible to measure a winding roll radius in the real time by making a mathematical model for measuring a winding roll radius. Finally, we've compared PID parameters as a function of winding roll radius after getting PID parameters in terms of the Ziegler & Nichols(ZN) method.

• 한국작물학회지
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• 제11권
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• pp.105-117
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• 1972

본연구는 맥류의 도복에 관여하는 주요형질의 상호관계를 구명함과 아울러 주요 대소맥 품종의 내도복성정도를 분류하고, 내도복성 품종 선발의 기준을 인정하여 보고자 한 것이며, 그 결과를 요약하면 다음과 같다. 1. 포장도복과 도복지수는 고도의 정의 상관(대맥 r=0.44-0.67 소맥 r=0.46-0.68)이 있으며 지상부 Bending moment에 간자체의 정도를 가미한 지수로서 도복저항성 검정에 가장 유효하다. 2. 간의 Bending stiffness를 표시하는 좌절시 Bending moment와 단면 2차 moment와는 정의 높은 상관(대백 r=0.59, 소맥 r=0.46-0.53)을 보였다. 3. 간의 Bending stiffness(좌절시 Bending moment 단면 2차 moment)와 간에의 건물집적량을 표시하는 단위간건물중과는 높은 정의 상관 (대맥 r=0.35-1.40, 소맥 r=0.33-0.76)을 보였다. 4. 도복지수와 단위간건물중 (대맥 r=-0.51～-0.70, 소맥 r=-0.65～-0.83) 좌절시 Bending moment (대맥 r=-0.29～-0.69, 소맥 r=-0.54～-0.89)과는 특히 높은 부의 상관을 보였으며, 소맥의 경우는 좌절하중, 단면 2차 moment, 단면계수와는 높은 부의 상관을 보였다. 5. 간외경은 간내경보다 간의 물리적 특성과 상관이 높으며 좌절하중 (대맥 r=0.42-0.56, 소맥 r=0.39-0.44), 좌절시 Bending moment (대맥 r=0.40-0.41, 소맥 r=0.38-0.49), 단면 2차 moment (대맥 r=0.56-0.97, 소맥 r=0.0.28-0.28), 단면계수(소맥 r=0.22-0.96)와는 정의 높은 상관이 있었고, 간벽후와 물리적특성과도 정의 상관을 보였다. 6. 간장은 포장도복과는 품종군에 따라서는 정의 상관은 보이나, 간의 강도를 고려한다면 내도복저항성품종 선발의 지표로서 이용하기는 어려울 것으로 보인다. 7. 대소맥의 많은 품종의 내도복성 정도를 분류한 결과, 한국품종중 대맥은 내도복저항성품종이 많고, 대맥은 내도복성인 품종의 분포가 대맥보다 적었으나, 일본품종들을 대소맥 모두 내도복저항성인 품종이 많았다. 8. 내도복저항성인 품종의 선발을 위하여는 도복지수가 대맥 1.67 소맥 1.76 정도 이하인 것은 고도의 저항성이 있었다.