열처리 및 단조조건에 따른 알루미늄 6056 소재의 특성변화 및 자동차의 피스톤 블록 설계

김민석,정병덕,박효영,최정묵,김정민,박준식,Kim, Min Seok,Jung, Hyung Duck,Park, Hyo young,Choi, Jeong Mook,Kim, Jeong Min,Park, Joon Sik 한국재료학회 2015 한국재료학회지 Vol.25 No.10

The mechanical properties and microstructures of Aluminum 6056 alloys were investigated for their use in the fabrication of a piton block. The EN-AW6056 alloys exhibited a tensile strength of 375 MPa for a solution treatment temperature of $550^{\circ}C$ for 2 h followed by an aging treatment at $190^{\circ}C$ for 4 h. The microstructures of the heat treated specimen showed that the $Mg_2Si$ phase with a size of 3~5 um was dispersed throughout the aluminum matrix when the heat treatment was done. Moreover, in order to identify the forgeability of the specimen, upsetting tests were done. For up to 80 % of the upsetting ratio, the specimen maintained its original shape, and at above 80 % of the upsetting ratio, the specimen underwent crack development. The specimen was successfully forged without any defects with the examined material conditions. The material conditions together with the forging conditions are discussed in terms of the microstructures and mechanical properties.

2.3 GHz 대역에서 단일 Half-LO 주파수를 이용한 Double-Conversion Down Mixer 설계

김민석,문주영,윤상원,Kim Min-Seok,Moon Ju-Young,Yun Sang-Won 한국전자파학회 2006 한국전자파학회논문지 Vol.17 No.8

본 논문에서는 Half-LO 주파수를 이용하는 새로운 방식의 double-conversion down mixer를 2.3 GHz 대역에서 설계하였다. 제안된 mixer에서는 Half-LO 주파수를 2개의 HEMT에 인가하여 두 HEMT에서의 변환 방식을 gate type과 resistive type으로 다르게 함으로서 IF 주파수를 얻게 된다. 기존의 sub-harmonic mixers와 같이 Half-LO 주파수를 사용하지만 제안된 mixer는 Half-LO의 second harmonic 성분을 이용하지 않고 Half-LO의 기본 주파수를 이용하여 주파수 변환을 하고 두 번째 HEMT에서 Resistive mixer type으로 IF 신호를 얻기 때문에 기존의 능동 mixer보다 향상된 선형성을 얻을 수 있다. 2.3 GHz 대역에서 설계 제작된 mixer는 Half-LO 전력 10 dBm을 이용하여 5dB의 변환 손실과 16.25dBm의 IIP3 특성을 얻을 수 있었다. In this paper, we designed the double conversion down mixer by using Half-LO frequency in 2.3 GHz band. The IF frequency is obtained by supplying two LO frequencies to HEMT in both gate type and resistive type. The proposed mixer uses Half-LO frequency the same way as conventional sub-harmonic mixers. However the proposed one uses fundamental component of Half-LO frequency in first stage instead of using second harmonic components of Half-LO frequency, and the IF frequency is obtained by resistive type mixer in second stage, thereby the proposed mixer can improve linearity in comparison with conventional active mixer. We can verify that the proposed mixer has an conversion loss of 5dBm and IIP3 of 16.25dBm by using 10 dBm Power.

심층신경망 구조에 따른 구개인두부전증 환자 음성 인식 향상 연구

김민석,정재희,정보경,윤기무,배아라,김우일,Kim, Min-seok,Jung, Jae-hee,Jung, Bo-kyung,Yoon, Ki-mu,Bae, Ara,Kim, Wooil 한국음향학회 2019 韓國音響學會誌 Vol.38 No.6

본 논문에서는 구개인두부전증(VeloPharyngeal Insufficiency, VPI) 환자의 음성을 효과적으로 인식하기 위해 컨볼루션 신경망 (Convolutional Neural Network, CNN), 장단기 모델(Long Short Term Memory, LSTM) 구조 신경망을 은닉 마르코프 모델(Hidden Markov Model, HMM)과 결합한 하이브리드 구조의 음성 인식 시스템을 구축하고 모델 적응 기법을 적용하여, 기존 Gaussian Mixture Model(GMM-HMM), 완전 연결형 Deep Neural Network(DNN-HMM) 기반의 음성 인식 시스템과 성능을 비교한다. 정상인 화자가 PBW452단어를 발화한 데이터를 이용하여 초기 모델을 학습하고 정상인 화자의 VPI 모의 음성을 이용하여 화자 적응의 사전 모델을 생성한 후에 VPI 환자들의 음성으로 추가 적응 학습을 진행한다. VPI환자의 화자 적응 시에 CNN-HMM 기반 모델에서는 일부층만 적응 학습하고, LSTM-HMM 기반 모델의 경우에는 드롭 아웃 규제기법을 적용하여 성능을 관찰한 결과 기존 완전 연결형 DNN-HMM 인식기보다 3.68 % 향상된 음성 인식 성능을 나타낸다. 이러한 결과는 본 논문에서 제안하는 LSTM-HMM 기반의 하이브리드 음성 인식 기법이 많은 데이터를 확보하기 어려운 VPI 환자 음성에 대해 보다 향상된 인식률의 음성 인식 시스템을 구축하는데 효과적임을 입증한다. This paper proposes speech recognition systems employing Convolutional Neural Network (CNN) and Long Short Term Memory (LSTM) structures combined with Hidden Markov Moldel (HMM) to effectively recognize the speech of VeloPharyngeal Insufficiency (VPI) patients, and compares the recognition performance of the systems to the Gaussian Mixture Model (GMM-HMM) and fully-connected Deep Neural Network (DNNHMM) based speech recognition systems. In this paper, the initial model is trained using normal speakers' speech and simulated VPI speech is used for generating a prior model for speaker adaptation. For VPI speaker adaptation, selected layers are trained in the CNN-HMM based model, and dropout regulatory technique is applied in the LSTM-HMM based model, showing 3.68 % improvement in recognition accuracy. The experimental results demonstrate that the proposed LSTM-HMM-based speech recognition system is effective for VPI speech with small-sized speech data, compared to conventional GMM-HMM and fully-connected DNN-HMM system.

Simplexity in Hydrology: 복잡함과 간단함 사이에서의 균형

김민석,Kim, Min-Seok 한국수자원학회 2021 물과 미래(한국수자원학회지) Vol.54 No.9

소아 환자에서 엡스타인-바 바이러스 뇌염에 동반된 양안 외향신경마비

김민석,최진,정재호,Kim Min Seok,Jin Choi,Jae Ho Jung 대한안과학회 2013 대한안과학회지 Vol.54 No.8

Purpose: To report 2 cases that presented with bilateral abducens nerve palsy associated with Epstein-Barr virus (EBV) encephalitis in children. Case summary: Case 1. A 14-month-old boy presented with fever and esodeviation of the left eye that started 5 days earlier. On the ophthalmic examination, 45-PD esotropia of the left eye and limitation of abduction in both eyes were observed. On neurological examination, there were no abnormalities. Serologic test and polymerase chain reaction (PCR) from cerebrospinal fluid (CSF) were positive for EBV. The patient was treated with systemic acyclovir and prednisolone. Part-time occlusion therapy of the right eye for 2 hours/day was also prescribed. The patient underwent a 6.5-millimeter recession of the medial rectus and a 6-millimeter resection of the lateral rectus on the left eye 7 months after the presentation. The patient showed orthotropia 1 week after the surgery without neurologic sequelae. Case 2. A 13-year-old boy presented with headaches and fever that started 5 days before and altered consciousness with seizures 2 days previously. Serological test for viral infection was normal, except for EBV, and CSF examination showed viral infection. After the patient recovered consciousness, he complained of diplopia. A 30-PD esotropia of his left eye with bilateral limitation of abduction was present. Alternating full-time occlusion of both eyes was prescribed. At 4 months after presentation, diplopia disappeared and the patient showed orthotropia without abduction limitation; however, anticonvulsants were prescribed to control seizures. Conclusions: In children, EBV encephalitis can be accompanied by acquired bilateral abducens nerve palsy. Residual nerve palsy and other neurologic sequelae can remain after several months.

소유역에서의 토사유출 산정을 위한 GeoWEPP model과 USLE의 비교.적용 연구 - 이천시 단월동 유역을 사례로

김민석,김진관,양동윤,Kim, Min-Seok,Kim, Jin-Kwan,Yang, Dong-Yoon 대한자원환경지질학회 2007 자원환경지질 Vol.40 No.1

GIS와 연계시켜 만든 분산형 모델의 대표적인 경험식인 USLE model과 물리학기반의 GeoWEPP model을 경기도 이천시에 위치한 소유역에 적용하여 2004년 1월에서 2005년 1월까지 1년간의 토사유출량을 비교하였다. 연구기간동안의 유출된 토사량은 실제관측결과 270.54 ton, USLE 모델 적용 시 358.1 ton, 그리고 GeoWEPP 모델 적용 시 283.30 ton으로 각각 산출되었다. 각각의 모델을 적용한 산출량은 실제 산출량보다 과대하게 산출되었으며, 산출결과만을 볼 때, GeoWEPP 모델을 적용한 토사유출량이 USLE 적용 산출량 보다 관측량에 더 근사한 산출량을 보였다. 모델 적용 산출량이 과대산출 된 원인으로는 실험웨어를 월류하여 빠져나간 부유물에 대한 양이 포함되지 않았기 때문으로 판단된다. The empirical USLE and the physically-based GeoWEPP which were distributed model linked with GIS (Geographical Information System) were applied to small natural catchment located in Icheon-si, Gyeonggi-do, South Korea. The results using by two models were total sediment yield from study catchment between January, 2004 and January, 2005. During the study period, the observed total sediment yield was 270.54 ton and the total sediment yield computed by USLE and GeoWEPP model were 358.1 ton and 283.30 ton, respectively. Each of results computed by USLE and GeoWEPP overestimated more than the observed total sediment yield, but, based on the results, the total sediment yield computed by GeoWEPP approximated to the observed result. We suggest that the reason why the total sediment yield using by models overestimated was that computed amounts by two models did not contain the amount of suspended sediment flowed over the weir.

「내외수 연계 내수침수예측시스템」 기술 소개

김민석,육지문,문영일,Kim, Min-Seok,Yuk, Ji-Mun,Mun, Yeong-Il 한국수자원학회 2017 물과 미래(한국수자원학회지) Vol.50 No.4

강우의 시간해상도와 자료기간에 따른 설계홍수량의 변동성

김민석,이정환,문영일,Kim, Min-Seok,Lee, Jung-Hwan,Moon, Young-Il 한국수자원학회 2018 한국수자원학회논문집 Vol.51 No.7

대부분의 수문분석은 시 단위 강우를 기반으로 확률강우량과 강우시간분포를 산정하고, 확률강우량과 강우시간분포의 자료기간을 달리 적용하는 방법으로 강우-유출분석을 수행하고 있다. 본 연구에서는 자료형태(시 단위와 분 단위 강우자료)와 확률강우량과 강우시간분포의 다른 자료기간 적용에 따른 설계홍수량 변화를 정량화 하고자, 자료형태와 자료기간에 따라 지점빈도해석을 통한 확률강우량 산정과 Huff의 4분위 방법을 통한 강우시간분포를 산정하였다. 또한, 확률강우량과 설계강우 시간분포의 자료기간을 달리 적용한 강우-유출분석으로 설계홍수량 변동분석을 실시하였다. 분석결과, 자료형태에서는 분 단위 강우가 시 단위 강우보다 더욱 정확하고 효과적인 강우분석을 수행할 수 있는 것으로 나타났으며, 확률 강우량과 강우시간분포의 다른 자료기간을 적용하여 산정된 설계홍수량의 차 보다 자료형식에 따른 설계홍수량 결과가 보다 큰 차이를 보이는 것으로 나타났다. 이는 향후 분 단위 강우를 활용한 수문분석에 크게 기여할 것으로 판단된다. Most hydrological analysis such as probability rainfall and rainfall time distributions have typically carried out based on hourly rainfall and rainfall - runoff analysis have carried out by applying different periods of rainfall time distribution and probability rainfall. In this study, to quantify the change of design flood due to the data type (hourly and minutely rainfall data) and the probability rainfall and application of different data period to the rainfall time distribution, probability rainfall is calculated by point frequency analysis according to data type and period and rainfall time distribution was calculated by Huff's quartile distributions. In addition, the change analysis of design flood was carried out by rainfall - runoff analysis applying different data periods of design rainfall time distribution. and probability rainfall. As a result, rainfall analysis using minute rainfall data was more accurate and effective than using hourly rainfall data. And the design flood calculated by applying different data period of rainfall time distribution and probability rainfall made a large difference than by applying different data type. It is expected that this will contribute to the hydrological analysis using minutely rainfall.

유완소(劉完素)의 중풍론(中風論)에 관(關)한 고찰(考察)

김민석,정승현,신길조,이원철,Kim, Min-Seok,Jung, Seung-Hyun,Shin, Gil-Cho,Lee, Won-Chul 대한한방내과학회 1997 大韓韓方內科學會誌 Vol.18 No.1

In this study, the purpose was to consider the conception, the causes, the pathology, the treatment and the prescription of 'Zhong Feng(中風)' through Liu Wan-Su's works. The results are obtained as fallows. First, Liu Wan-Su regarded Zhong Feng(中風) as 'Feng Re(風熱)'. He thought the causes and the pathology of Zhong Feng(中風) that pathologically fever was due to excess of feelings and 'Heart-fire(心火)', was due to intemperate living, so he thought the leading causes of Zhong Feng(中風) were Feng Re(風熱) and Heart-fire(心火) and emphasized the internal causes of Zhong Feng(中風). But he excluded absolutely external causes. He also insisted that Feng Re(風熱) was cause in a fat and a thin person. Second, according to symptom of the limbs and 'Jiu Qiao(九竅)', he classified Zhong Feng(中風) into 'Zhong Fu(中腑)' and 'Zhong Zang(中臟)'. And in the treatment of Zhong Feng(中風), the three principle was set up that 'Sweating .method(發表法)' in the case of Zhong Fu(中腑), 'Passing method(通滯法)' in Zhong Zang(中臟) and 'Nutrient method(養筋法)', in case that both symptom would not revealed. And in the prescription of Zhong Feng(中風), he presented 'Xumingtang(續命湯)', 'Sanhuatang(三化湯)' and 'Daqinfantang(大秦?湯)' to them each.

갑상선독성주기마비 증례; 마비증상시와 회복 후에 연속적으로 시행한 신경전도 검사 결과

김민석,박정아,석정임,Kim, Min Suck,Park, Jung A,Seok, Jung Im 대한임상신경생리학회 2015 Annals of Clinical Neurophysiology Vol.17 No.2