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표면부착형 영구자석 동기전동기의 자속기반 센서리스 제어 알고리즘의 추정자속 옵셋 제거 기법
김학준(Hack-Jun Kim),조관열(Kwan-Yuhl Cho),김학원(Hag-Wone Kim),이광운(Kwang-Woon Lee) 전력전자학회 2017 전력전자학회 논문지 Vol.22 No.3
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.
지능형 전장인식 서비스를 위한 지식베이스 구축 방안 연구
조세현(Se-Hyeon Jo),김학준(Hack-Jun Kim),진소연(So-Yeon Jin),이우신(Woo-Sin Lee) 한국컴퓨터정보학회 2020 韓國컴퓨터情報學會論文誌 Vol.25 No.4
본 논문에서는 지능형 전장인식 서비스를 위한 자연어처리 기반 지식베이스 구축 방안에 대해 연구한다. 현재의 지휘통제체계는 수집된 전장정보와 전술데이터를 등록, 저장, 공유 등의 기본적인 수준에서 관리 및 활용하고 있으며, 분석관에 의한 정보/데이터 융합 및 상황 분석/판단이 수행되고 있다. 이는 분석가의 시간적 제약과 인지적 한계로 일반적으로 하나의 해석만이 도출되며 편향된 사고가 반영될 수 있다. 따라서 지휘통제체계의 전장상황인식 및 지휘결심지원 지능화가 필수적이다. 이를 위해서는 지휘통제체계에 특화된 지식베이스를 구축하고 이를 기반으로 하는 지능형 전장인식 서비스 개발이 선행되어야 한다. 본 논문에서는, 민간 데이터인 엑소브레인 말뭉치에서 제시된 개체명 중 의미 있는 상위 250개 타입을 적용하고 전장정보를 적절히 표현하기 위해 무기체계 개체명 타입을 추가 식별하였다. 이를 바탕으로 멘션 추출, 상호참조해결 및 관계 추출 과정을 거치는 전장인식 지식베이스 구축 방안을 제시하였다. In this paper, we propose a method to build a knowledge base based on natural language processing for intelligent battlefield awareness service. The current command and control system manages and utilizes the collected battlefield information and tactical data at a basic level such as registration, storage, and sharing, and information fusion and situation analysis by an analyst is performed. This is an analyst’s temporal constraints and cognitive limitations, and generally only one interpretation is drawn, and biased thinking can be reflected. Therefore, it is essential to aware the battlefield situation of the command and control system and to establish the intellignet decision support system. To do this, it is necessary to build a knowledge base specialized in the command and control system and develop intelligent battlefield awareness services based on it. In this paper, among the entity names suggested in the exobrain corpus, which is the private data, the top 250 types of meaningful names were applied and the weapon system entity type was additionally identified to properly represent battlefield information. Based on this, we proposed a way to build a battlefield-aware knowledge base through mention extraction, cross-reference resolution, and relationship extraction.
대퇴골두 무혈성 괴사의 조직학적 분석과 자기공명영상과의 관계
손원용(Won Yong Shon),김학준(Hack Jun Kim),심재학(Jae Hak Shim),김성연(Sung Yon Kim),김철환(Chul Hwan Kim) 대한고관절학회 1999 Hip and Pelvis Vol.11 No.1
We performed a retrospective study on 20 patients to correlate MRI findings with histopathologic results upon avascular necrosis of femoral head which were obtained after total hip arthroplasties. 17 femoral heads were male and 3 femoral heads were female. The average age of the patients at surgery was 50 years(ranging from 21 to 75 years old). The etiologies of AVN in the femoral head were alchol overuse in 17 and idiopathic in 3 femoral heads. The specimens were analysed histologically using Arlet and Durroux classification and 4 types of histological findings were drawn on the map of femoral head. Contiguous, 4.8 mm coronal 1.5 Tessler MRI (Magnetic 63 SP4000, Siemens, Germany) sections were compared with the corresponding histologic sections. Type 4 lesion was seen as a low intensity signal on both Tl and T2 weighted MRI images. Type 3 lesions showed as intermedite to low intensity signals in Tl and T2 weight MRI images. Type 1,2 lessions were not distinguishable on MRI findings. The MRI signal cannot predict particular histopathologic pattern in the later stages of avascular necrosis of femoral head
손원용 ( Won Yong Shon ),전승주 ( Seung Ju Jeon ),나경욱 ( Kyoung Wook Rha ),김학준 ( Hack Jun Kim ) 대한고관절학회 1998 Hip and Pelvis Vol.10 No.1
We now report the results of Harris Precoat femoral stem(Zimmer, Inc.,Warsaw,IN) of fourty hips in twenty-nine patients at a 5-7.5 year follow up.In this study, cemented precoat femoral stem was used in sixty-one, nonselected hip patients from October 1990 to May 1993 in our department. Twelve patients(13 hips) had been lost to follow up. At the final follow up, seven patients(7 hips) had died and one hips were too ill for detailed follow up. Radiographies were available for 36 hips of 26 patients who were alive for the entire follow up period. The average age at the time of the procedure was 54 years(range 27-76). There were twenty-three men(thirty-four hips) and six women(six hip). The femoral component had been revised for aseptic loosening in three hips(8%).One additional hip showed definite radiographic loosening. Hence, the prevalaence of radiographic failure was 11%(four hips). Three of them had suboptimal cement mantle(C1 or C2) Subsidence without radiolucency between cement interface occured in one hip. No femoral osteolysis was seen in stable component. These results show that cementation techinques is one of the most important factors for durability of cemented femoral stem, early debonding between stem-cement interface may develop even in this precoated femoral stem and also once debonding may produce premature failure of cemented femoral fixation.