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DS/CDMA 통신에서 다경로 페이딩 간섭 제거를 위한 반복적 최소 자승 역전파 신경망 알고리즘
김광준(Kwang-Joon Kim),나상동(Sang-Dong Na) 한국정보과학회 1999 정보과학회논문지 : 시스템 및 이론 Vol.26 No.4
DS/CDMA 시스템은 이동통신 시스템에서 다중경로, 고의적인 반방해 전파 및 동일대역폭을 공유하기 위한 다중 사용자에 의해 발생되는 협대역 간섭과 부가적인 백색 가우시안 잡음을 제거한다. 본 논문에서는 다계층 퍼셉트론을 기반으로 한 역전파 신경망을 이용한 정합 필터 채낼 모델이 DS/CDMA 이동 통신 시스템에서 직접 순차 확산 스펙트럼의 협대역 간섭을 억압하기 위해 나타내었다. 정합 필터 수신기 구조에서 보다 빠른 수렴성과 성능 개선을 위해 역전파 에러를 이용한 반복적 최소 자승 역전파 알고리즘을 이용하였다. 동일 채널 간섭과 협대역 간섭을 고려하면서 신호 대 잡음비와 전송 전력비에 따른 컴퓨터 시뮬레이션 결과는 역전파 신경망을 이용한 정합 필터의 비트 에러율이 직접 순차 확산 스펙트럼의 RAKE 수신기의 비트 에러 율보다 적음을 입증하였다. DS/CDMA system rejected narrow-band interference and additional White Gaussian noise which are occurred at multipath, intentional jammer and multiuser to share same bandwidth in mobile communication systems. Because of having not sufficiently obtained processing gain which is related to system performance, they were not effectively suppressed. In this paper, the matched filter channel model using backpropagation neural network based on complex multilayer perceptron is presented for suppressing interference of narrow-band of direct sequence spread spectrum receiver in mobile communication systems. Recursive least square backpropagation algorithm with backpropagation error is used for fast convergence and better performance in matched filter receiver scheme. According to signal noise ratio and transmission power ratio, computer simulation results show that bit error ratio of matched filter using backpropagation neural network improved than that of RAKE receiver of direct sequence spread spectrum considering of co-channel and narrow-band interference.
입자유동가공을 이용한 오프셋 교차구멍에 대한 디버링 연구
김광준(Kwang Joon Kim),김영관(Young Gwan Kim),김권희(Kwon Hee Kim) 대한기계학회 2019 大韓機械學會論文集A Vol.43 No.7
버는 드릴링, 절삭 등의 기계가공 과정에서 소재의 소성변형에 의해 발생하는 의도치 않은 잔여물이다. 특히, 빗겨서 생성된 교차구멍에서의 버는 가공품의 내부 깊은 곳에 생성되어 접근이 매우 어렵고, 형태가 복잡하여 버의 제거가 쉽지 않다. 본 연구는 빗겨서 직교하는 교차구멍을 입자유동 방식으로 디버링하는 경우, 여러 가공 변수들의 영향을 알아보았다. 실험은 Al6061 소재에 대하여 L8 직교배열표를 이용하여 유동거리, 연마재 입자크기, 연마액 농도, 연마액 점도, 그리고 유속을 변수로 선정하여 진행하였다. 민감도 분석을 통하여 디버링의 완성도는 유동거리에 따라 크게 의존하며 유속의 영향은 상대적으로 작다는 것을 알 수 있었다. Burr is an unintentional residue caused by plastic deformation of the workpiece during machining such as drilling and milling. Burrs generated in the intersecting holes deep inside the work piece are difficult to access and remove. In this work, the effects of various AFM process parameters are investigated for holes intersecting at right angle with offset. Burr edge is formed in the wall of the primary hole by the secondary hole. Experiments were carried out for AL6061 specimens with flow distance, abrasive particle size, abrasive particle concentration, abrasive fluid viscosity and flow speed allocated in L8(2<SUP>5</SUP>) orthogonal array. The mean value analysis indicates that deburring is strongly dependent on the flow distance while the effect of flow speed is minimal.
광학이성질체 의약품 개발에서 안전성과 유효성 평가에 대한 규제 요건
김광준(Kwang Joon Kim),최인(In Choi),서규화(Kyuhwa Seo),한효경(Hyo-Kyung Han),이원재(Wonjae Lee) 대한약학회 2011 약학회지 Vol.55 No.5
This study was performed to investigate the current regulatory guidances of safety and efficacy evaluation for the development and approval of stereoisomeric drugs in US, EU, Canada and Japan. The important categories for the development of stereoisomeric drugs are classified as 1) development of a single enantiomer as a new active substance 2) development of a racemate as a new active substance 3) development of a new single enantiomer from an approved racemate. The regulatory documents adopted in major countries for the safety and efficacy evaluation of stereoisomeric drugs were investigated with the focus on three major categories mentioned above. For the regulatory approval of stereoisomeric drugs in Korea, it is expected that the investigated results obtained in this study will be useful for the basic materials to ensure the safety and efficacy of stereoisomeric drugs as well as the stereochemical issues in chiral drug development in domestic pharmaceutical company.
점탄성 제진 요소의 복소동강성계수 산출을 위한 상용유한요소 코드 이용시 복소탄성계수의 정하중 의존성 반영 방법
김광준(Kim, Kwang-Joon),신윤호(Shin, Yun-Ho) 한국소음진동공학회 2006 한국소음진동공학회 논문집 Vol.16 No.4
Little attention has been paid to static-strain-dependence of dynamic complex modulus of viscolelastic materials in computational analysisso far. Current commercial Finite Element Method (FEM) codes do not take such characteristics into consideration in constitutive equations of viscoelastic materials. Recent experimental observations that static-strain-dependence of dynamic complex modulus of viscolelastic materials, especially filled rubbers, are significant, however, require that solutions somehow are necessary. In this study, a simple technique of using a commercial FEM code, ABAQUS, is introduced, which seems to be far more cost/time saving than development of a new software with such capabilities. A static-strain-dependent correction factor is used to reflect the influence of static-strains in Merman model, which is currently the base of the ABAQUS. The proposed technique is applied to viscoelastic components of rather complicated shape to predict the dynamic stiffness under static-strain and the predictions are compared with experimental results.
중환자실 환자의 정맥주사용 글루타민 투여에 따른 임상효과 평가
김광준 ( Kwang Joon Kim ),장혜영 ( Hey Young Jang ),강민구 ( Min Ku Kang ) 한국정맥경장영양학회 2019 한국정맥경장영양학회지 Vol.11 No.1
Purpose: To evaluate the clinical effect of intravenous glutamine administration on patients admitted to the intensive care unit in general hospitals. Methods: Patients with more than 7 days in an intensive care unit were evaluated. The experimental group was the patients who received intravenous glutamine administration for more than 3 days. The laboratory results, intensive care unit length of stay, hospital length of stay, 30 days mortality, and hospital mortality were evaluated with a comparative group. Results: The mean number of administration days of intravenous glutamine was 10.12±8.93 days, and the average daily dose was 0.33±0.10 g/kg/day. No adequate improvement in the laboratory results of glutamine-treated group was observed. The intensive care unit length of stay (21.16±15.83 vs. 16.48±11.06, P=0.007), hospital length of stay (35.94±30.75 vs. 27.34±19.09, P=0.010), 30 days mortality (20.0% vs. 10.0%, P=0.034), and hospital mortality (26.3% vs. 13.0%, P=0.001) were higher in the glutamine-treated group. Conclusion: The use of intravenous glutamine on intensive care unit patients did not improve the clinical effect. Further large-scale multi-center studies will be needed to assess the proper administration of intravenous glutamine on intensive care unit patients.