• 전력전자학회논문지
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• 제22권3호
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• pp.216-222
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• 2017

The rotor position of a PM synchronous motor is commonly estimated from the mathematical model for the sensorless control without rotor position sensors. For the magnet flux-based rotor position estimator in the stationary reference frame, the magnet flux estimator for estimating rotor position and speed includes the integrator. The integrator in the magnet flux estimator may accumulate the offset of the current sensors and the voltage drift. This continuous accumulation of the offset may cause the drift and overflow in the integrator, such that the estimated rotor position and speed may fail to track the real rotor position and speed. In this paper, the magnet flux estimator without integrator is proposed to avoid overflow in the integrator. The proposed rotor position and speed estimator based on magnet flux estimator are verified through simulation and experiment.

• 대한전자공학회논문지
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• 제22권3호
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• pp.60-67
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• 1985

본 논문에서는 VLSI layout CAD에 있어서의 새로운 그로발 라우팅(global routing) 기법을 제안하고 이에 관하여 논하였다. 종래의 그로발 라우터에서는 핀의 위치를 모두 셀의 중앙에 두었기 때문에 신호선의 채널 사용량을 정확히 산출할 수 없었다. 그 결과 디테일드 라우팅 (detailed routing)시 배선량 overflow가 발생하여 100% 결선을 저해하는 많은 요인을 내포하고 있었다. 본 논문에서는 이러한 문제점을 모두 보완하기 위하여 핀순서를 고려한 새로운 방법의 그로발 라우팅 알고리즘을 제안하였다. 이 알고리즘을 사용하여 그로발 라우터를 실현하고, 계산기상의 실험 결과를 통하여 제안한 알고리즘의 유용성을 보였다.

• The Journal of Korean Physical Therapy
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• 제12권1호
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• pp.9-13
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• 2000

The purpose of this study was to determine the overflow effect and cross training effect of isometric quadriceps training that performed in specific angle of unilateral let. Ten healthy students with an average age of 24 years$(24.1\pm1.3)$, were participated in this study. Then 5 subjects in each group were chosen at random to train using only right quadriceps muscle two time per day(group 2), five times a week and the other 5 subjects(group 1) were chosen to train one times per day, five times a week for 2 weeks at only 50 degrees (contract 6 seconds, rest 10 seconds, 3 sets). Before and after the training, isometric quadriceps muscle testing of the both leg was Performed at three different angles, 60, 50 and 40 degrees respectively by BHN-COM (isokinetic dynamometer) in sitting position. The data was analyzed with paired t-test to determine significant difference between before and after training. In this study, we have found that the isometric quadriceps muscle training on specific angle of right side produced overflow effect In healthy subjects. However, increasing the peak torque of specific angle(training angle) of trained limb did not have an effect on increasing the peak torque of contralateral limb. These results demonstrate that the cross training effect did nut found in this study but a alight increase of peak torque of the untrained limb would recognized the possibility of cross training effect.

• 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.

• 한국정보과학회논문지:데이타베이스
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• 제33권5호
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• pp.495-512
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• 2006

최근 다양한 응용 분야에서 이동 객체의 현재 위치를 기반으로 미래 위치를 검색하기 위한 필요성이 증가되고 있다. 이와 함께, 대용량의 이동 객체를 빠르게 검색하기 위한 색인 구조의 필요성이 증가되고 있다. 기존에 제안된 색인 구조들은 이동 객체의 위치를 검색하는 과정에서 불필요한 노드의 확장을 유발시켜 검색 성능이 저하되는 문제점이 있다. 이러한 문제점을 해결하기 위해 본 논문에서는 객체의 이동성을 고려한 공간 분할 방식의 색인 구조를 제안한다. 제안하는 색인 구조는 노드의 오버플로우를 처리하기 위해 형제 노드와 병합 분할을 수행하고 형제 노드와 병합을 수행하여 오버플로우를 처리할 수 없을 경우에는 이동성을 고려하여 분할을 수행한다. 제안하는 색인 구조는 분할된 영역들 사이에 겹침 영역이 발생하지 않으며 속도, 이동 객체가 노드의 영역을 벗어나는 시간, 노드의 갱신 시간과 같은 파라미터를 고려하여 분할 위치를 판별한다. 중간 노드에서는 공간 분할 방식의 색인 구조에서 발생하는 연속 분할을 방지하기 위한 분할 위치를 판별한다. 제안하는 색인 구조의 우수성을 입증하기 위해 이동 객체에 대한 검색 성능을 비교 분석한다. 성능 평가 결과 제안하는 색인 구조는 현재 위치 검색에 대해서는 $17%{\sim}264%$ 그리고 미래 위치 검색에 대해서는 $107%{\sim}19l%$ 성능 향상을 나타낸다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1999년도 고액공존금속의 성형기술 심포지엄(III) SYMPOSIUM ON SEMISOLID FORMING TECHNOLOGY(III)
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• pp.15-32
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• 1999

A relationship between stress and stain is very important to design a die to avoid defects of products during semi-solid forming process. Since the liquid will be of eutectic composition in alloys liquid segregation will result in significant or undesirable situation. The materials used in this experiment are A 357. A390, Al2024 alloys that is fabricated by the electro-magnetic stirring process from Pechiney in France. The compression test was performed by induction heating equipment and MTS. In order to prevent the liquid segregation these measured temperature would be useful to control of strain rate during compression test. The liquid segregation is controlled as change of the strain rate and solid fraction during the compression process, The characteristics of flow between solid and liquid phase considering liquid segregation is examined through the above experiments. In the case of medium and high volume fractions of solid the distribution of strain rate is calculated by using compression test data of semi-solid materials (SSM). The thixoforming experiments with the designed die are carried out successfully. The die filling patterns of SSM for variation of die temperature and pressing force have been investigated. The hardness of the thixoformed scroll products is evaluated in terms of the microstructure for each position.

• 한국반도체및디스플레이장비학회:학술대회논문집
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• 한국반도체및디스플레이장비학회 2007년도 춘계학술대회
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• pp.174-178
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• 2007

The cleaning process to remove small particles, ions, and other polluted sources is one of the major parts in the recent semiconductor industry because it can cause fatal errors on the quality of the final products. According to the other reports, the major factors of bath's fluid motion are the cleaning method, nozzle, the geometry (of bath, guide and wafer), and the position (of guide and wafer). So to enhance cleaning efficiency in the bath, these factors must be controlled. The purpose of this study is to analyze and visualize fluid motion in the cleaning bath as basic data for designing the nozzle system and finding the process control parameters. For that, we used the general CFD code FLUENT.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년 영문 학술대회
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• pp.877-880
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• 2008

In this article, in order to fabricate polymer based electrospray device with super hydrophobic nozzle we use PTFE(polyfluorotetraethylene) plate and PMMA(polymethylmethacrylate). To obtain the super hydrophobic surface nozzle, PTFE surface is treated by argon and oxygen plasma treatment process. And evaluate the treated surface, perform measuring contact angle, SEM(Scanning Electron Microscope) and AFM(Atomic Force Microscope). We compare the performance of the super hydrophobic PTFE surface nozzle with raw PTFE and PMMA surface nozzle. For the ion beam treated PTFE nozzle, the liquid doesn't overflow and it keeps initial position and meniscus shape. From these results, we expect in cease of superhydrophobic surface nozzle jetting becomes more stable and repeatable.

• 한국자동차공학회논문집
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• 제17권3호
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• pp.45-53
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• 2009

Die casting process of Mg alloys for high temperature applications was studied to produce an engine oil pan. The aim of this paper is to evaluate die casting processes of the Aluminium oil pan and in parallel to apply new Mg alloy for die casting the oil pan. Temperature distributions of the die and flow pattern of the alloys in cavity were simulated to diecast a new Mg alloy by the flow simulation software. Dies have to be modified according to material characteristics because melting temperature and heat capacity are different. We changed the shape and position of runner, gate, vent hole and overflow by the simulation results. After several trial and error, oil pans of AE44 and MRI153M Mg alloys are produced successfully without defect. Sleeve filling ratio, cavity filling time and shot speed of die casting machine are important parameter to minimize the defect for die casting Magnesium alloy.

• 대한교통학회지
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• 제26권4호
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• pp.275-285
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• 2008

"물류산업"은 장래 우리나라의 새로운 성장산업의 하나로 인식되고 있다. 그간 우리나라는 중국화물의 환적거점으로 기능을 하였으나, 최근 중국 자체항만의 성장으로 대형선단이 중국으로 이동하고 있다. 결과적으로 한국의 물류중심의 입지가 위기를 맞고 있다. 이러한 시점에서 물류혁신과 국제경쟁력 강화를 위해 새로운 전략이 필요하게 되었고, 본 연구에서는 "부가가치물류클러스터"를 새로운 전략으로 제안하고 있다. 특히 본 연구는 한국의 입지적 산업적 장점을 극대화할 수 있는 한국형 부가가치물류클러스터를 제안하고 있다. 추가적으로 한국 항만이 동북아 물류거점으로 성장할 수 있도록 한국형 부가가치물류클러스터 모형이 제안되었다. 클러스터 구성요소, 물류산업과 타 산업 간의 연관성 분석과 같은 다양한 분석과정이 한국형 부가가치물류클러스터 모형을 개발하기 위해 단계별로 시행되었다. 또한 한국형 부가가치물류클러스터 모형을 물동량 감소로 최근 위기를 맞고 있는 광양항에 적용하였다.