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장수영,윤성기,김철순,오동호,Chang, Su-Young,Youn, Sung-Kie,Kim, Cheol-Soon,Oh, Dong-Ho 대한기계학회 2000 大韓機械學會論文集A Vol.24 No.7
A study on the topology optimization of Hard-Disk-Driver(HDD) actuator arm in free vibration is presented. The purpose of this research is to increasse the natural frequency of the first lateral mode of the HDD actuator arm under the constraint of total moment of inertia, so as to facilitate the position control of high speed actuator am. The first lateral mode is an important factor in the position control process. Thus the topology optimization for 2-D model of the HDD actuator arm is considered. A new objective function corresponding to multieigenvalue optimization is suggested to improve the solution of the eigenvalue optimization problem. The material density of the structure is treated as the design variable and the intermediate density is penalized. The effects of different element types and material property functions on the final topology are studied. When the problem is discretized using 8-node element of a uniform density, the smoothly-varying density field is obtained without checker-board patterns incurred. As a result of the study an improved design of the HDD actuator arm is suggested. Dynamic characteristics of the suggested design are compared computationally with those of the old design. With the same amount of the moment of inertia, the natural frequency of the first lateral mode or the suggested design is subsequently increased over the existing one.
Periodogram을 이용한 움직임 추정에서의 속도 Pairing
장수영,이병욱,Chang, Soo-Young,Lee, Byung-Uk 한국통신학회 2003 韓國通信學會論文誌 Vol.28 No.4C
움직이는 여러 개 물체의 속도를 추정하능 방법으로 피리오도그램(periodogram)을 사용하는 방법이 있다. 이는 영상 시퀀스를 프레임별로 수직과 수평 방향으로 투사를 한 후 시간축 FFT를 실행한다. 차원 주파수 도메인에서 원점을 지나는 직선상의 화소들의 에너지를 합하여 움직이는 물체의 속도를 추정하게 된다. 물체가 두 개 이상일 경우에는 각각의 움직이는 속도에 해당하는 여러 개의 피크 값들을 검출하게 된다. 이 피크 값들을 짝지어 주게 되면 물체 각각의 속도가 나오게 된다. 본 논문의 방법은 기존의 수평, 수직 투사이외에, 투사의 방향을 추가하여 수평 수직 방향 속도 성분을 짝지워줬다. 기존의 논문들에 비해 간단한 계산으로 움직이는 물체의 속도를 효과적으로 짝지울 수 있다. A fast multiple object motion detection method using periodogram has been proposed. Each frame is projected to vertical and horizontal directions, and then temporal FFT is applied. A line in two dimensional frequency domain indicates velocity. To estimate the velocity of an object, we intergrate along a line which passes through the origin in frequency domain. If a frame contains multiple moving objects, multiple peaks are detected corresponding to the velocity of each object. After pairing these peaks, we can determine the velocities of an object. In the proposal method we can easily pair horizontal and vertical velocity components efficiently with simple computation by combining projections in 45$^{\circ}$ and 135 $^{\circ}$ directions in addition to the vertical and horizontal direction.
AR 모델 및 LSQ 기반 변류기 2차 전류 복원 기법
張洙榮(Soo-Young Chang),李東圭(Dong-Gyu Lee),姜相熙(Sang-Hee Kang) 대한전기학회 2006 전기학회논문지A Vol.55 No.6
The current flowing though a power line is measured by a current transformer (CT). Since a CT is a kind of transformer, saturation of magnetic flux in the core may occur when a large primary current flows. This saturation makes the secondary current of a CT distorted and causes problems in the protection point of view. Because of the current distortion, a protection relay cannot collect the correct information showing how the primary power system changed. Consequently, the current distortion may cause the mal-operation or operation time delay of protective relay. In this paper, an algorithm based on AR model and LSQ is proposed to compensate the saturated CT secondary currents. Various test results indicate that the proposed algorithm can accurately compensate a severely distorted secondary current and is not affected by remanence.
장수영(Sooyoung Chang),김원정(Wonjung Kim) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11
Superabsorbent polymers (SAPs) consist of hydrophilic cross-linked polymer networks that can absorb and retain a great amount of water relative to their own mass, so that they are widely used for diapers and drug delivery media. We examine the water absorption of sodium polyacrylate through its swelling. We experimentally observed the one- and two-dimensional swelling of sodium polyacrylate in confined channels. Sodium polyacrylates are typically used in the form of grain to increase the surface area, and our systematic experiments show the dependence of swelling on the size of the grains. The results provide the basis of the hydrodynamic analysis of the water flow through hydrogels with expansion.
한국인 영어 학습자의 영어 단어 경계 인지 시 변이음 단서 사용 연구
장수영(Chang,Sooyoung),박한상(Park,Hansang) 한국음성학회 2011 말소리와 음성과학 Vol.3 No.3
This study investigates how Korean students employ acoustic-phonetic cues in perceiving word boundaries of near-homophonous English phrases. For this study, 60 Korean college students participated in the experiment of discriminating word boundaries for 42 pairs of stimuli comprising the allophonic cues of aspiration and glottal stop. Results were analysed in terms of the correctness of responses and the correlation between correctness and confidence. Results showed that stimuli pairs of the glottal stop cue give a higher correctness but those of aspiration a relatively lower correctness. Comparison of the results of this study with those of the previous studies of English and Japanese speakers showed that Korean and Japanese speakers of English give a substantially lower correctness than native speakers of English, while Korean learners of English as a foreign language provide a lower correctness than Japanese speakers of English as a second language.
장수영(Chang Soo-Young),김명숙(Kim Myungsook) 한국영어학학회 2006 영어학연구 Vol.- No.21
Although "sentence stress" in English takes a very important role in its daily conversations and communication, Korean students are not familiar with its concept. It is partly because they are used to the phonological system of their own language, Korean, which is syllabled-timed, and partly because they are not exposed to actual practices for speaking English, which is stress-timed. This paper is a case study of English sentence stress patterns realized in Korean college students with a main focus on their errors and inconsistencies, in order to prove that understanding sentence stress is a very basic and critical step toward a proper level of communication between English speakers. The case study tells us that most Korean students do not have a proper understanding of English sentence stress, and that they make errors which can be easily found in most speakers of syllable-timed language, such as inconsistent stress assignments, improper placements of pauses, and poor understanding of rhythmic structure of English. However, when a student has been exposed to enough practices for speaking, he or she is likely to give a proper sentence stress pattern as expected.