• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.6D
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• pp.779-784
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• 2011

Freeway FFS (Free-Flow Speed) under the state of LOS (Level of Service) A has been regarded as a homogeneous state to all levels of traffic volume. The features of low-density FFS is served as the basic data for a decision on limited maximal speed, accident analysis, simulation modeling etc. A few researches for the macroscopic characteristics of design and operation speed have been reported, and any study for the microscopic features of freeway free-flow speed under the state of low density has not been done. Therefore, the characteristics of low-density FFS according to the level of traffic volume (1-3 veh/30 sec) and daily hour periods (0-5, 6-8, 9-11, 12-19, 20-23) is microscopically analyzed in this study with huge volume and speed data. It was found that speed distributions are changed and show different behaviors under the conditions of traffic volume levels and daily time periods. V85s (85th percentile speed) at early morning and night periods decrease when levels of traffic volume increase, whereas V85s at day time do not show considerable differences. Especially, FFSs of levels of traffic volume at early morning and night periods, despite low density, is analyzed as heterogeneity, but homogeneity at day time.

• Geophysics and Geophysical Exploration
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• v.14 no.4
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• pp.324-334
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• 2011

Seismic wave velocity change has been monitored due to the accumulation of micro-cracks by uniaxial loads on the rock samples from Seokmo Island with stepwise increase in 5 stages. After the load was applied up to 95% of UCS, P- and S-wave velocities varied in ranges of 0.9 ~ 18.3% and 2.8 ~ 14.8% of fresh rock sample velocities, respectively. Unlike seismic velocity of the dry rock samples that showed overall decreases after the loading, velocity changes of saturated rock samples were much more complicated. These seemed to be due to the mixture of two contradictory mechanisms; i.e. accumulation of micro-crack causes an increase in porosity and a decrease in wave velocity, while saturation causes an increase in wave velocity. Most of tested rocks showed a trend of velocity increase with low axial load and then velocity decrease at later stages. Starting stage of velocity decrease differs from samples to samples. After the failure of rock occurred, noticeable increases of porosity and decreases of wave velocity have been observed. It showed overall trend that the more the quartz contents and the lower the silicate, the higher the Young's modulus.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.3
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• pp.224-232
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• 2006

The paper proposes the artificial neural network(ANN) sensorless control of induction motor drive with adaptive fuzzy logic controller(AFLC). Also, this paper proposes the speed control of induction motor using AFC and estimation of speed using ANN controller. The back propagation neural network technique is used to provide a real time adaptive estimation of the motor speed. The error between the desired state variable and the actual one is back-propagated to adjust the rotor speed, so that the actual state variable will coincide with the desired one. The proposed control algorithm is applied to induction motor drive system controlled AFLC and him controller. And this paper is proposed the results to verify the effectiveness of the AFLC and ANN controller.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.4 s.175
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• pp.839-847
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• 2000

This paper presents modal analysis and mean conveying velocity (M.C.V.) control of bowl parts feeder activated by piezoactuators. Bowl parts feeders are being widely used in many industry fields for automatic assembly line. In general, the electromagnet has been and being used as exciting actuator of these vibratory bowl feeders. However, because of complexity of its mechanism and limited capability of the electromagnet actuator, there exist various impending problems such as severe noise, nonlinear motion of parts, passive characteristics and so forth. As one of solutions for these problems, piezoelectric actuators as new actuating technology have been proposed recently to excite the bowl parts feeder. In this paper, modal analysis of the proposed model has been performed to examine the modal characteristics of the model by using commercial FEM software and modeling with respects to MCV is constructed. Finally, MCV of the parts is to be controlled to track the desired one with PID controller.

• The Transactions of the Korean Institute of Power Electronics
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• v.6 no.3
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• pp.273-281
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• 2001

In this paper, we propose a CMAC(Cerebellar Model Articulation Controller) neural network for controlling a non-linear system. CMAC is a neural network that models the human cerebellum. CMAC uses a table look-up method to resolve the complex non-linear system instead of numerical calculation method. It is very fast learn compared with other neural networks. It does not need a calculation time to generate control signals. The simulation results show that the proposed CMAC controllers for a simple non-linear function and a DC Motor speed control reduce tracking errors and improve the stability of its learning controllers. The validity of the proposed CMAC controller is also proved by the real-time tension control.

• Journal of the Korean Society for Railway
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• v.10 no.6
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• pp.735-741
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• 2007

A turnout system which permits trains to pass from one track to another is a combination of the switch, the crossing, lead rails which are necessary to connect the switch and the crossing, two guard rails and a switch machine for operating the switch. In Korea, it has been planned to adopt the high speed tilting train which is suitable for the circumstance of Korea and operates at the maximum speed of 180 km/h, at conventional lines by the year of 2010. For the present, the prototype of the tilting train has been fabricated, and has undergoing a trial run. In this study, evaluation of noise around the turnout system induced by the tilting train has been implemented through the field measurements.

• Korean journal of applied entomology
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• v.33 no.1
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• pp.39-50
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• 1994

In the course of the taxonomic study on onbatid mites from Korea, the author obtained one nau genus, 5 new species, 1 new subspecies, and 5 species unrecorded in Korea for th first time. They are Koreonbates foliatus gen. n, sp. n., Hermannio neotricha sp. n., Xyiobates geonjiensis sp. n., Defectamems sungohi sp. n., Protoripoda flagellato sp. n., Liocarus gommatus coreanus ssp. n., Liocarus polychoihomus Wen, 1991, Tectodamoeus armatus Aok, 1984, T striatus Enami et Aoki, 1988. Oripoda trilabiata Hammer, 1961, and Dometorino tuberculata Aoki, 1984. And keys to the species and subspec~es of genera Liacorus, Defectamems, and Protoripoda are present All the specimens are deposited at the Lab of Plant Protection, Coli, ot Agr, Won Kwang Univ., hi, Korea. KEY WORDS Taxonomic, Acari, Oribatei, Korea.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.24 no.5
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• pp.425-431
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• 2006

Recently, the government has adjusted the 4th National Master Plan in an effect to achieve balanced national land development. However, the current traffic accident index ranks among the lowest in OECD countries, ranking 25th out of 29 countries. Therefore, this study is aimed at indicating problems with National Expressway and local roads developing a solution by analyzing the problems and suggesting the most appropriate design speed for inter-changes where the traffic accidents occur frequently. With the results, it is to obtain a design speed decision formula at interchange branch points to prevent traffic accidents, secure safe and optimal road conditions and maximize traffic load capability.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.168-168
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• 2011

정보화 사회가 도래함으로 개인별 정보 이용량이 급격히 증가하였고 스마트폰과 같은 모바일 기기의 개발로 정보 이용량이 최고치를 갱신 중이다. 이러한 흐름 속에 사람들은 빠른 처리 속도와 고도의 저장 능력을 요구하게 되고 이에 따라 새로운 Random Access Memory에 대한 연구가 활발히 진행되고 있다. 현재 Dynamic Random Access Memory (DRAM)가 눈부신 발전과 성과를 이룩하고 있지만 전원 공급이 중단 될 경우 저장된 내용들이 지워진다는 단점을 가지고 있다. DRAM의 장점에 이러한 단점을 보완할 수 있는 차세대 반도체 소자로 주목 받고 있는 것이 Magnetic Random Access Memory (MRAM)이다. DRAM에서 Capacitor와 유사한 기능을 하는 MTJ stack은 tunneling magnetoresistance (TMR) 현상을 나타내는 자기저항 박막을 이용하여 MRAM 소자에 집적된다. 본 연구에서는 MRAM의 자성 재료로 구성된 MTJ stack을 효과적으로 식각하고 우수한 식각 profile을 얻는 동시에 재증착의 문제를 해결하는데 목적을 둔다. 본 IrMn 자성 박막의 식각 연구는 유도결합 플라즈마 반응성 이온 식각 (Inductively Coupled Plasma Reactive Ion Etching: ICPRIE)법을 이용하여 진행되었다. 특히 본 연구에서는 종래의 $Cl_2$, $BCl_3$ 그리고 HBr과 같은 부식성 가스가 아닌 부식성이 없는 $CH_4$가스를 선택하여 그 농도를 변화시키면서 식각하였고 더 나아가 $O_2$를 첨가하면서 그 효과를 극대화하려고 시도하였다. IrMn 자성 박막의 식각 속도, TiN 하드 마스크에 대한 식각 선택도 그리고 profile 등이 조사되었고 최종적으로 X-ray photoelectron spectroscopy (XPS)를 이용하여 식각 메카니즘을 이해하려고 하였다.

• The Journal of the Acoustical Society of Korea
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• v.17 no.4
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• pp.3-13
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• 1998

본 논문은 음성 다이어링 시스템을 구현하기 위한 한국어 단독 숫자음 및 연속 숫 자음 인식에 관한 것이다. 단독 숫자음의 인식은 미지의 입력 음성을 재귀 신경망을 이용하 여 모델링된 각 모델에 인가하고, 신경 회로망의 출력 노드의 상태열을 검사하여 적절한 상 태 전이를 하며 최고의 확률값을 출력하는 모델을 인식된 결과로 출력한다. 연속 숫자음의 인식은 미지의 연속 숫자음을 재귀 신경 회로망을 이용한 연속 숫자음 모델에 입력하고, 신 경 회로망의 출력에 대하여 적절한 상태 전이에 대한 검사와 레벨 빌딩(Level Building)을 수행하여 최소의 오차를 가지는 모델열을 인식된 결과로 출력한다. 재귀 신경 회로망을 이 용하여 음절 모델을 만드는 과정에서 재귀 노드는 예상치가 주어지지 않으므로 신경 회로망 의 학습에서 제외되어 현저한 학습 속도의 저하를 가져온다. 따라서 본 논문에서는 재귀 신 경 회로망의 학습 속도를 향상시키기 위한 2가지 방법을 제안 한다. 첫 번째는 재귀 신경 회로망의 재귀 노드의 예상치를 실험적으로 주어줌으로써 학습 속도의 향상을 도모하였다. 두 번째는 음절 모델의 출력노드의 개수와 음절 모델의 세그먼트 경계를 알고리듬을 이용하 여 자동적으로 조절하였다. 실험결과, 단독어의 경우 음절 '에'에 포함하는 한국어 11개의 숫 자음에 대하여 화자 종속의 경우 97.3%, 화자 독립의 경우 80.5%의 인식률을 얻었으며, 연 속 숫자음의 경우는 21종류의 연속 숫자음에 대하여 화자 종속에서 88.2%, 화자 독립의 경 우 81.3%의 인식률을 얻을 수 있었다.