Al 1050 합금에 과공정 Al-Si 합금의 레이저 클래딩에서 평균출력의 영향에 대한 연구

이형근,Lee, Hyoung-Keun 대한용접접합학회 2011 대한용접·접합학회지 Vol.29 No.2

This study produced hypereutectic Al-Si clad layer on 1050 Al alloy by a novel laser cladding method. Pure Si powder was mixed with organic binder to make fluid paste which could be screen-printed on the 1050 Al alloy plate. Pulsed Nd:YAG laser was irradiated on the Si paste layer to melt and alloy with Al substrate. Different laser power of 99 W, 179 W and 261 W, was used to see the difference of the microstructure, composition and hardness of the clad layers. When laser power of 179 W was used, the clad layer had overall Si content of 38wt% and composed of fine primary Si particles and fine eutectic phase. At laser power of 261 W, the clad layer had overall Si content of 24wt% and composed of mainly fine eutectic phase. Vickers hardness of HV176.7 and HV150.3 on the clad layer was obtained at laser power of 179 W and 261 W, respectively.

SO2 와 NOx 동시제거를 위한 흡수제의 반응성

이형근,최원길,조항대,민병무 ( Hyung Keun Lee,Won Kil Choi,Hang Dae Jo,Byung Moo Min ) 한국화학공학회 1996 화학공학의이론과응용 Vol.2 No.1

신경학적 손상에 의한 언어장애인 음성 인식률 개선(H/W, S/W)에 관한 연구

이형근,김순협,양기웅,Lee, Hyung-keun,Kim, Soon-hub,Yang, Ki-Woong 한국정보통신학회 2019 한국정보통신학회논문지 Vol.23 No.11

신경학적 손상에 의한 언어장애인/비장애인 간의 일상적인 휴대폰 통화시 신경학적 손상으로 인한 발음의 정확도와 언어장애인의 발음 특징이 결합되어 원활한 의사소통을 저해하는 경우가 많다. 이러한 문제점을 개선하기 위하여 제한하는 방법은 언어장애인 특성에 맞춘 단어의 모호성(out of vocabulary) 개선과, 언어 장애인 구강 특성에 따른 어려운 발성 부분을 인위적으로 보정해주는 유도선이 포함된 MEMS(Micro Electro-mechanical System) Microphone 장치 개선이다. S/W적 개선은 도치기능이 포함된 결정트리이며, 연속어 특성을 감안하여 개선된 matrix-vector rnn 방법을 제시하였다. H/W와 S/W 특성을 감안하여 유사 사전을 만들어 원활한 의사소통을 위한 말명료도 향상에 기여하였다. In everyday mobile phone calls between the disabled and non-disabled people due to neurological impairment, the communication accuracy is often hindered by combining the accuracy of pronunciation due to the neurological impairment and the pronunciation features of the disabled. In order to improve this problem, the limiting method is MEMS (micro electro mechanical systems), which includes an induction line that artificially corrects difficult vocalization according to the oral characteristics of the language impaired by improving the word of out of vocabulary. mechanical System) Microphone device improvement. S/W improvement is decision tree with invert function, and improved matrix-vector rnn method is proposed considering continuous word characteristics. Considering the characteristics of H/W and S/W, a similar dictionary was created, contributing to the improvement of speech intelligibility for smooth communication.

Clozapine 투여로 인한 타액 과잉분비에 대한 Clonidine의 치료효과

이형근,박인준,권영준,정희연,Lee, Hyung-Keun,Park, In-Joon,Kwon, Young-Joon,Jeong, Hee-Yeon 대한생물정신의학회 2000 생물정신의학 Vol.7 No.1

Background : Hypersalivation can be a troublesome side effect of clozapine, limiting its usefulness in the management of some cases of schizophrenia. But the pharmacodynamic basis of clozapine-induced hypersalivation remains obscure. Object : The aim of this study was to evaluate the effect of the ${\alpha}_2$-adrenergic agonist clonidine on clozapine-induced hypersalivation in the patients who were receiving clozapine. Method : Twenty one schizophrenic inpatients on clozapine participated in the study. The amount of saliva was measured on the 7th day at 8pm after starting clozapine treatment. Of them, 15 patients who had experienced hypersalivation was treated with 0.1mg/day of clonidine. Result : Of 21 schizophrenic patients treated with clozapine in the psychiatric inpatient clinic, 15(71.4%) complained hypervalivation. After clonidine treatment, mean salivary flow-rate was decreased significantly in these patients. Conclusion : Clozapine-induced hypersalivation could be decreased by administration of ${\alpha}_2$-adrenergic agonist clonidine and compliance could be improved. Also our study supports the notion that increased adrenergic tone contributes to clozapine-induced hypersalivation. Clozapine의 부작용 중 타액의 과잉분비의 원인을 알아보기 위하여 순천향대학교 천안병원 신경정신과에 입원한 환자 중 정신분열병 환자 21명(남자 12명, 여자 9명)을 대상으로 시행한 본 연구결과는 다음과 같다. 1) 정신분열병 환자에게 clozapine을 투여한 후 타액의 분비는 유의하게 증가하였다. 2) Clozapine을 투여한 후 타액의 과잉분비를 보인 정신분열병 환자에게 clonidine을 투여한 후 타액의 분비는 유의하게 감소하였다. 3) Clozapine에 의한 타액의 과잉분비는 ${\alpha}$-아드레날린성 작용에 의한다는 것을 강하게 시사한다.

차분 위성 항법을 위한 위치영역 필터의 설계

이형근,지규인,Lee, Hyung Keun,Jee, Gyu-In,Rizos, Chris 한국항행학회 2004 韓國航行學會論文誌 Vol.8 No.1

차분 위성 항법에 있어서 빈번한 동적 변화를 수반하는 항체에 대하여 편향되지 않은 위치 추정치를 생성하기 위해서는 위상 평활화 코드 필터가 널리 사용되고 있다. 위치추정, 오차해석, 고장진단, 그리고 미지정수 결정 등 보정위성항법시스템의 다양한 응용분야에 있어서 정확한 오차공분산 정보는 중요한 역할을 담당한다. 반면, 기존의 위상 평활화 코드 필터 알고리즘들은 대부분 누적위상 측정오차에 의한 시전달 오차를 무시하므로 실재에 비하여 낙관적인 오차공분산 정보를 생성할 위험성을 내포하고 있다. 위상 평활화 코드 기법의 활용에 있어서 일관성 있고 적절한 오차공분산 정보를 생성하기 위하여 본 논문에서는 Stepwise Optimal Position Projection Filter와 Stepwise Unbiased Position Projection Filter 알고리즘을 제안하였다. 제안된 필터는 기존의 필터에 비하여 누적위상의 특성에 기인하는 시전달 오차의 특성을 정확하고 상세하게 고려하여 주며 잦은 가시위성의 변화도 함께 고려할 수 있는 장점을 가진다. 몬테카를로 시뮬레이션에 의하여 수신기 Kalman 필터, 기존의 위상 평활화 코드 필터, 그리고 제안된 두 필터들의 성능을 비교 분석 하였다. Consistent and realistic error covariance information is important for position estimation, error analysis, fault detection, and integer ambiguity resolution for differential GNSS. In designing a position domain carrier-smoothed-code filter where incremental carrier phases are used for time-propagation, formulation of consistent error covariance information is not easy due to being bounded and temporal correlation of propagation noises. To provide consistent and correct error covariance information, this paper proposes two recursive filter algorithms based on carrier-smoothed-code techniques: (a) the stepwise optimal position projection filter and (b) the stepwise unbiased position projection filter. A Monte-Carlo simulation result shows that the proposed filter algorithms actually generate consistent error covariance information and the neglection of carrier phase noise induces optimistic error covariance information. It is also shown that the stepwise unbiased position projection filter is attractive since its performance is good and its computational burden is moderate.

유색 잡음 환경하에서 Cumulant를 이용한 한국어 단모음 인식

이형근,양원영,조용수,Lee, Hyung-Gun,Yang, Won-Young,Cho, Yong-Soo 한국음향학회 1994 韓國音響學會誌 Vol.13 No.2

본 논문에서는 3차 Cumulant를 이용하여 음성의 특징벡타를 추출하고, 이것을 신경회로망의 입력으로 사용하는 음성 인식 방법을 제시한다. 3차 이상의 고차 cumulant를 이용하면 Gaussian 잡음과 음성 신호의 분리가 가능하며, 충분히 많은 데이타를 사용할 경우 음성 데이타를 AR 모델링한 계수값을 bias 없이 추출할 수 있다. 또한 기존의 2차 statistics를 이용한 특징 벡타 추출 방법과 비교할 때 잡음이 큰 경우에도 분산은 크지만 bias가 작아 보다 잡음에 강한 특징벡타를 추출할 수 있다. 한국어 단모음에 대한 모의실험을 통하여 유색 잡음 환경에서 SNR이 커질수록 3차 cumulant를 이용한 방법이 기존의 2차 statistics를 이용한 방법보다 높은 인식율을 나타냄을 보인다. This paper presents a speech recognition method utilizing third-order cumulants as a feature vector and a neural network for recognition. The use of higher-order cumulants provides desirable uncoupling between the gaussian noise and speech, which enables us to estimate the coefficients of AR model without bias. Unlike the conventional method using second-order statistics, the proposed one exhibits low bias even in SNR as low as 0 dB at the expense of higher variance. It is confirmed through computer simulation that recognition rate of korean single-vowels with the cumulant-based method is much higher than the results with the conventional method even in low SNR.

회전벡터와 좌표전환

이형근,Lee, Hyeong-Geun 제어로봇시스템학회 2011 제어로봇시스템학회지 Vol.17 No.3

F-RPN(Failure-RPN)을 이용한 장비 고장률 개선 연구: 반도체 식각 공정을 중심으로

이형근,홍용민,강성우,Lee, Hyung-Geun,Hong, Yong-Min,Kang, Sung-Woo 대한안전경영과학회 2021 대한안전경영과학회지 Vol.23 No.3

The purpose of this study is to present a novel indicator for analyzing machine failure based on its idle time and productivity. Existing machine repair plan was limited to machine experts from its manufacturing industries. This study evaluates the repair status of machines and extracts machines that need improvement. In this study, F-RPN was calculated using the etching process data provided by the 2018 PHM Data Challenge. Each S(S: Severity), O(O: Occurence), D(D: Detection) is divided into the idle time of the machine, the number of fault data, and the failure rate, respectively. The repair status of machine is quantified through the F-RPN calculated by multiplying S, O, and D. This study conducts a case study of machine in a semiconductor etching process. The process capability index has the disadvantage of not being able to divide the values outside the range. The performance of this index declines when the manufacturing process is under control, hereby introducing F-RPN to evaluate machine status that are difficult to distinguish by process capability index.

연구발표 초록 ( 분리기술 (Ⅲ) ) : 초임계유체에서 이성체혼합물의 용해도거동이 분리에 미치는 영향

이형근,김춘호,김성현,최청송 ( Hyung Keun Lee,Choon Ho Kim,Sung Hyun Kim,Chung Song Choi ) 한국화학공학회 1991 추계학술발표회 Vol.- No.-

저출력 펄스형 Nd:YAG 레이저를 사용한 클래딩에서 클래딩 변수들이 용착효율에 미치는 영향 분석 및 최적화

이형근,Lee, Hyoung-Keun 대한용접접합학회 2007 대한용접·접합학회지 Vol.25 No.4

The optimization of the cladding parameters was studied to maximize the deposition efficiency in the laser cladding using a low power pulsed Nd:YAG laser. STS304 stainless steel plate and Co alloy powder were used as a substrate and powder for cladding, respectively. The six cladding parameters were selected through preliminary experiments and their effects on the deposition efficiency were analyzed statistically. Experiments were designed and carried out using the Taguchi experimental method using a L18 orthogonal array. It was found from the results of analysis of variance(ANOVA) that the powder feed position and powder feed angle had the most significant effects on the deposition efficiency, but the powder feed rate and laser focal position had nearly no effects. The deposition efficiency could be maximized at 0mm of the powder feed position and 50o of the powder feed angle in the experimental range. From this experimental analysis, a new laser cladding head with 20o of the powder feed angle was designed and manufactured. With a new laser cladding head, the highest deposition efficiency of 12.2% could be obtained.