• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.406-411
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• 2003

One of the trends on information storage device is focused on the development of micro-optical devices with OFH (Optical Flying Head). Many different types of sliders for OFH and optical component systems have been introduced in the literature. However, the important issue on the mechanical system, which consists of suspension, swing arm and VCM (Voice Coil Motor) part has not been discussed up to date. In this research, we analyses the suspension, which is used for the small form factor MO drive. The analysis is in process two ways. One is probabilistic analysis, another is dynamic shock analysis. Probabilistic analysis is a technique you can use to assess the effect of uncertain input parameters and assumptions on your analysis model. Using a probabilistic analysis you can and out how much the results of a finite elements analysis are affected by uncertainties in the model. Dynamic shock analysis is used for the mobile applications. The mechanical robustness of the suspension simulating the shock responses of a disk-suspension is proposed in this paper.

• Korea-Australia Rheology Journal
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• 제19권1호
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• pp.27-33
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• 2007

The co-extrusion of multi-layer films has been studied with the focus on its process stability. As in the single-layer film casting process, the productivity of the industrially important multi-layer film casting and the quality of thus produced films have often been hampered by various instabilities occurring in the process including draw resonance, a supercritical Hopfbifurcation instability, frequently encountered when the draw ratio is raised beyond a certain critical value. In this study, this draw resonance instability along with the neck-in of the film width has been investigated for a three-layer film casting using a varying width non-isothermal 1-D model of the system with Phan-Thien and Tanner (PTT) constitutive equation known for its robustness in portraying extensional deformation processes. The effects of various process conditions, e.g., the aspect ratio, the thickness ratio of the individual film layers, and cooling of the process, on the stability have been examined through the nonlinear stability analysis.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2004년도 학술발표회
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• pp.521-526
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• 2004

It is necessary to analyze the unsteady flow in the pipe network for the better operation and controls, but there are some problems in actual pipe network simulation, such as collecting a large amount of information in the field, operating highly upgraded computer system, and keeping a big storage device to run analysis program. The skeletonization method is used to cope with the problems in this paper. It is expected to reduce computation time, researcher's efforts, and costs for the analyzing the pipe network. The impact of individual pipe elements to the behavior of the water distribution system can be accounted in the process of skeletonization. However it is also important to study continuously about how to apply the skeletonization method for each of different cases, because inadequate uses may bring simulation to a false result. This paper introduces basic theories and skeletonizing examples in the actual pipe network in Dae-gu city.

• 한국지하수토양환경학회지:지하수토양환경
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• 제20권3호
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• pp.51-64
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• 2015

In the present study, we develop two history matching techniques based on Markov chain Monte Carlo method where radial basis function and Gaussian distribution generated by unconditional geostatistical simulation are employed as the random walk transition kernels. The Bayesian inverse methods for aquifer characterization as the developed models can be effectively applied to the condition even when the targeted information such as hydraulic conductivity is absent and there are transient hydraulic head records due to imposed stress at observation wells. The model which uses unconditional simulation as random walk transition kernel has advantage in that spatial statistics can be directly associated with the predictions. The model using radial basis function network shares the same advantages as the model with unconditional simulation, yet the radial basis function network based the model does not require external geostatistical techniques. Also, by employing radial basis function as transition kernel, multi-scale nested structures can be rigorously addressed. In the validations of the developed models, the overall predictabilities of both models are sound by showing high correlation coefficient between the reference and the predicted. In terms of the model performance, the model with radial basis function network has higher error reduction rate and computational efficiency than with unconditional geostatistical simulation.

• EDISON SW 활용 경진대회 논문집
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• 제6회(2017년)
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• pp.259-269
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• 2017

Gust load is a very important load factor in designing various structures of an aircraft and judging its stability. This is because the blast effect on the aircraft in operation increases the risk of damage to the structure of the aircraft and causes a negative impact such as shortening the fatigue life by generating vibration. Particularly in the case of wing, a change in angle of attack is caused by gust load, and an additional lift acts on the wing, thereby being exposed to various excitational environments. Severe structural damage to the aircraft may occur if the natural frequencies of the aircraft wing are close to or coincident with the frequencies of the gust load applied to the wing. Recent trends of research include flight dynamics analysis considering discontinuous gusts or structural optimization of the blades under gust load. A number of studies have been conducted to interpret gust load response in consideration of irregularities in gusts. In this paper, we tried to imagine the situation of the aircraft subjected to the gust load as realistic as possible, and proposed an algorithm to track back the critical gust profile according to given aircraft characteristics from the viewpoint of preliminary engineering prediction.

• 융합보안논문지
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• 제14권5호
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• pp.49-56
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• 2014

본 논문에서는 기존의 제안된 LDP(Local Directional Pattern)에 기반하여 지역적인 얼굴특징을 표현하는 방법을 제안한다. 제안된 방법은 눈과 입과 같은 얼굴의 영구적인 특징과 표정이 변하면서 발생하는 일시적인 특징을 효과적으로 표현할 수 있도록 얼굴특징별로 크기와 형태를 달리하는 중첩 가능한 블록을 설정하고 이를 바탕으로 얼굴 특징벡터를 구성한다. 제안된 중첩 블록설정 및 특징 표현 방법은 기하학적 특징을 기반으로 하는 접근 방법의 장점을 수용할 뿐만 아니라 각 얼굴특징의 움직임 특성을 이용하여 얼굴검출에 대한 오류를 수용할 수 있고, 블록사이즈의 가변성으로 인한 공간정보를 유지할 수 있어 표본오차를 줄일 수 있는 장점이 있다. 실험결과, 제안된 방법은 기존 방법에 비해 인식률이 향상됨을 확인하였고, 기존 얼굴 특징 벡터보다 길이가 짧기 때문에 연산량 또한 감소하는 것을 확인하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1987년도 정기총회 및 창립40주년기념 학술대회 학회본부
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• pp.454-456
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• 1987

A more specialized area of transient evaluations is transmission line fault-detecting and protection system. During the first cycle or two following a power system fault, a high-speed protective relay is expected to make a decision as to the severity or location of the fault, usually based on 60 Hz information, i.e. the phase and magnitude of 60 Hz voltage or current signals. It is precisely at this time however that the signal is badly corrupted by noise, in the form of a de offset or frequencies above 50 Hz. One of several possible sources of transients in protection measuring signals is in the primary system for which protection is required in its response to the impact of short circuit fault on-set. Other sources are in the primary voltage and current transducers from which protection signals are derived, and, often of particular importance, in the interface circuits between the transducer secondaries and the comparator and measuring elements of the protection system. However, the noise signals that will be described in this paper are due to the main power system only and do not include errors due to current or voltage transducers.

• 전력전자학회논문지
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• 제23권1호
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• pp.32-39
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• 2018

A new dc link voltage controller for a three-phase Vienna rectifier is proposed in this study. This method uses load current and duty information to control dc link voltage. The load current affects the capacitor current and varies the output voltage. Existing methods do not perfectly consider the load current. By considering load current with duty compensation in the proposed method, the transient response is improved by the load variation regardless of the input voltage. The effectiveness of the proposed method is compared with other control methods when the load changes rapidly using PSIM simulation and experiment.

• Journal of Astronomy and Space Sciences
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• 제14권1호
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• pp.80-86
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• 1997

지구 주변의 방사선대에 존재하는 고에너지 입자들은 위성계의 전자 재료, 부품, 및 집적 회로 등에 일시적 또는 장기적인 영향을 준다. 따라서 이러한 고에너지 입자들에 의한 우주 방사선 환경에 대한 정보를 아는 것은 매우 중요하다. 총 방사선의 양을 측정하는 장치로서 MOSFET을 개량한 RADFET을 많이 사용하는데, 본 연구에서는 $Co^{60}{\gamma}-ray$를 이용하여 TOT500 RADFET을 보정하였다. 그 결과, 방사선에 대한 RADFET의 특성 곡선 변화가 온도의 변화에 매우 민감한 것을 확인하였다. 또한, 우리별 1호에서의 TDERUF과를 위성의 온도와 비교하였으며, 그 결과 TDE 실험에 나타난 특이한 형상은 지구에 의한 위성의 식 현상에서 비롯된 온도 변화가 주된 원인이었음을 확인하였다.

• 전자공학회논문지T
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• 제35T권1호
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• pp.14-21
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• 1998

GaAs MESFET는 동작점에 따라 선형영역, 포화영역으로 구분된 모델을 사용함에 따라, GaAs MESFET 회로 해석을 위한 컴퓨터 시뮬레이션 시 영역의 경계점에서의 1차 및 2차 미분 불연속으로 인한 해의 발산 문제가 발생하곤 하였다. 본 논문에서는 선형영역과 포화영역을 모두 포함한 통합된 채널길이변조식을 제안하였다. 새로이 제안된 채널길이변조식을 이용하여 전류-전압 모델과 커패시턴스-전압 모델을 제안하였다. 제안된 전류-전압 모델은 Shur의 모델과 비교하였으며 제안된 커패시턴스-전압 모델은 디바이스 시뮬레이션 결과와 비교하였다. 비교된 결과로부터 제안된 모델들은 기존의 모델과 유사한 결과를 얻었으며 연속성이 개선될 것으로 기대된다.