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유용성의 측면에서 기하학적, 열적 비대칭 사다리꼴 휜의 최적화
강형석,Kang, Hyung-Suk 대한기계학회 2003 大韓機械學會論文集B Vol.27 No.5
Optimum fin effectiveness of geometrically and thermally asymmetric trapezoidal fins is represented as a function of the ratio of the fin bottom to top Biot numbers, the ratio of the fin tip to top Biot numbers and fin shape factor. Optimum fin effectiveness is taken as 98% of the maximum fin effectiveness by comparing the increasing rate of fin effectiveness with that of dimensionless fin length. For this analysis, two dimensional separation of variables method is used. Also, the value of the slope of upper surface of the fin and fin efficiency corresponding to optimum effectiveness are presented.
강형석,이섭,권오춘,안욱수,배지훈,Kang, Hyong-Seok,Lee, Sub,Kwon, Oh-Choon,Ahn, Wook-Su,Bae, Chi-Hoon 대한흉부심장혈관외과학회 2000 Journal of Chest Surgery (J Chest Surg) Vol.33 No.8
Descending necrotizing mediastinitis(DNM) is one of the most lethal form of mediastinitis originating from an oropharyngeal infection. It requires an early and aggressive sugical treatment, but the operative approach and optimal form of mediastinal drainage remains controversial. We report a case of DNM in a 45-year-old male who underwent right cervicomediastinotomy to drain the deep neck space, upper mediastinum and anterior mediastinal drainage was accomplished through a subxiphoid approach. After this procedure, he steadily improved and was dischrged on hospital day 36. We report this case with a brief review of the literature.
Exynos4210 프로세서 상에서 실시간 리눅스 커널 패치의 성능 평가
강형석,이준우,최진영,김강희,Kang, Hyeongseok,Lee, Joonwoo,Choi, Jinyoung,Kim, Kanghee 한국정보처리학회 2013 정보처리학회논문지. 컴퓨터 및 통신시스템 Vol.2 No.7
최근에 지능화된 자동차, 로봇, 공장 등에 대한 관심이 높아지면서 지능화된 모션 제어 응용을 손쉽게 작성할 수 있는 소프트웨어 플랫폼에 대한 필요성이 날로 커지고 있다. 이를 위해서 그 기능과 각종 하드웨어 지원이 풍부한 범용 운영체제를 사용하는 것이 바람직하지만, 일반적으로 개별 응용의 실시간 응답성이 항상 보장되지는 않는다. 본 논문은 범용 운영체제로서 리눅스가 산업용 실시간 시스템에 적합한지 평가하기 위해 ARM 기반 프로세서 Exynos4210 상에서 Xenomai 실시간 리눅스 패치를 적용하고 모션 제어 응용의 실시간 성능을 평가하였다. 평가결과, 백그라운드 작업 부하의 간섭에도 불구하고 모션 제어 응용에게 1ms 미만의 제어 주기를 안정적으로 제공할 수 있음을 확인하였다. Recently, there is a growing need for an open software platform where developers easily write intelligent motion control applications for smart cars, smart robots, smart factories, and so on. To this end, a general-purpose operating system with rich functionalities and various hardware supports can be a candidate for such a platform, but it is known to have limitations in guaranteeing the responsiveness of individual applications. In this paper, to assess the suitability of Linux to be such a platform, we evaluate the real-time performance of Xenomai-patched Linux on an ARM-based processor Exynos4210 with motion control applications. Experimental results show that it is possible to stably provide motion cycle times below 1ms to such applications even with background workloads.
충돌제트를 갖는 회전원판 위 3차원 경계층의 난류특성 (I) - 평균유동장 -
강형석,유정열,최해천,Kang, Hyung Suk,Yoo, Jung Yul,Choi, Haecheon 대한기계학회 1998 大韓機械學會論文集B Vol.22 No.9
The objective of the present study is to investigate experimentally the mean flow characteristics of the three-dimensional turbulent boundary layer over a rotating disk with an impinging jet at the center of the disk, which may be regarded as one of the simplest models for the flow in turbomachinery. A relatively strong radial outflow (crossflow) generated from the impinging jet is added to the radial outflow (crossflow) induced by the centrifugal force in order to create the three-dimensional boundary layer. A new calibration technique has been introduced to determine the velocity direction and magnitude using an I-wire probe, where the uncertainties are ${\pm}1.5^{\circ}$ and ${\pm}0.35\;m/s$, respectively, in the laminar boundary layer region, compared with the known exact solutions. The flow in the tangential direction is of similar type to that associated with a favorable pressure gradient, considering that no wake region appears in wall coordinate velocity profiles and the Clauser shape factor is between 4.0 and 5.3. The flow angle is significantly changed by the crossflow generated by the impinging jet.
약계자 영역에서의 순시 무효전력을 이용한 매입형 영구자석 동기전동기의 센서리스 속도제어
강형석(Hyoung-Seok Kang),김원석(Won-Seok Kim),김영조(Young-Jo Kim),김영석(Young-Seok Kim) 대한전기학회 2006 대한전기학회 학술대회 논문집 Vol.2006 No.7
For the interior permanent magnet synchronous motor(IPMSM) drive to operate above the base speed in the constant horsepower region, field weakening control is applied. However, the field weakening control was not almost applied to sensorless control of the interior permanent magnet synchronous motor. In this paper, field weakening control is applied to the sensorless control of IPMSM based on an instantaneos reactive power. The effectiveness of the proposed system is verified by the experimental results.
매입형 영구자석 동기전동기의 속도 센서리스에 관한 연구
강형석(Hyoung-Seok kang),김영석(Young-Seok Kim) 대한전기학회 2007 대한전기학회 학술대회 논문집 Vol.2007 No.10
본 논문은 매입형 영구자석 동기전동기의 속도 센서리스의 제어 방법에 관한 것이다. 매입형 영구자석 동기전동기의 센서리스 구동을 위하여 적응 적분바이너리 관측기와 적용 슬라이딩 모드 관측기를 이용하였다. 두 관측기의 성능 비교를 위하여 매입형 영구자석 동기전동기의 고정자 전압방정식으로부터 각각 관측기를 구성하였고, 동일한 시스템에서의 실험을 통하여 관측기의 성능을 비교하였다.
Word2vec 및 fastText 임베딩 모델의 성능 비교
강형석(Hyungsuc Kang),양장훈(Janghoon Yang) 한국디지털콘텐츠학회 2020 한국디지털콘텐츠학회논문지 Vol.21 No.7
Due to the simple structure and excellent performance of a word2vec embedding model, it is one of the widely used models in the field of natural language processing but it also has some limitations. In order to overcome these limitations, fastText embedding models applicable to general languages were proposed and then a specific fastText model suitable for Korean was also developed recently. This study aims to compare and evaluate several word2vec and fastText models through similarity tests, analogy tests and sentiment analysis tasks. This study shows that unlike the results of previous studies that proposed fastText models, the fastText models cannot be concluded to be superior to word2vec model, at least in terms of analogy tests and sentiment analysis tasks. In particular, in the case of a specific downstream task, word2vec embeddings with less computational complexity can achieve desired performance as good as fastText embeddings.
고정된 휜 체적에 기준한 원관 내부반경이 변하는 환형 휜의 최적화
강형석(Hyung Suk Kang) 대한기계학회 2010 大韓機械學會論文集B Vol.34 No.3
원관 내부반경이 변하는 사각형상 환형 훤의 최적 값들이 변수 분리법에 의하여 제시된다. 최적의 열손실이 존재할 수 있는 주위 대류특성계수의 범위가 나열된다. 최적 열손실, 그와 관련된 최적의 훤 유용성, 훤 길이 그리고 훤 높이가 원관 내부반경, 내부유체 대류특성계수, 훤 체적, 그리고 주위 대류특성계수의 함수로 표현된다. 결과 중 하나는 훤 체적과 훤 바닥반경이 고정되었을 때 최적 열손실, 유용성 그리고 훤 길이는 원관 내부반경의 증가에 따라 선형적으로 증가함을 보여준다. Optimum values of fin performance and dimensions for an annular fin with a rectangular profile and a pipe with variable inner radius are determined by using a variable separation method. The range of ambient convection characteristic number that results in optimum heat loss is listed. The optimum heat loss, corresponding optimum fin effectiveness, fin length, and fin height are presented as a function of the inner radius of the pipe, inner fluid convection characteristic number, fin volume, and ambient convection characteristic number. One of the results shows that the optimum heat loss, fin effectiveness and fin length increase linearly with the inner radius of the pipe when both the fin volume and fin-base radius are fixed.
적응 적분바이너리 관측기를 이용한 매입형 영구자석 동기전동기의 센서리스 속도제어
姜炯錫(Hyoung-Seok Kang),金榮石(Young-Seok Kim) 대한전기학회 2007 전기학회논문지 Vol.56 No.1
A control approach for the sensorless speed control of interior permanent magnet synchronous motor(IPMSM) based on adaptive integral the binary is proposed. With a main loop regulator and an auxiliary loop regulator, the binary observer has a property of the chattering alleviation in the constant boundary layer. However, the width of the constant boundary limits the steady state estimation accuracy and robustness. In order to improve the steady state performance of the binary observer, the binary observer is formed by adding extra integral augmented switching the hyperplane equation. By mean of integral characteristics, the rotor speed can be finely estimated and utilized for a sensorless speed controller for IPMSM. The proposed adaptive integral binary observer applies an adaptive scheme, because the parameters of the dynamic equations such as the machine inertia or the viscosity friction coefficient is not well known and these values can be easily changed generally during normal operation. Therefore, the observer can overcome the problem caused by using the dynamic equations, and the rotor speed estimation is constructed by using the Lyapunov function. The experimental results of the proposed algorithm are presented to demonstrate the effectiveness of the approach.