시그모이드 추정과 임계 판정 가중 오차를 사용한 새로운 SDD 등화의 자기적응 성능 개선

오길남(Kil Nam Oh) 한국산학기술학회 2016 한국산학기술학회논문지 Vol.17 No.8

고차 QAM 시스템에 대한 자기적응 등화에서 눈 모형이 완전히 닫힌 등화 초기에 적용하여 눈 모형을 빠르게 열뿐만 아니라 정상상태 오차 레벨을 크게 낮추는 새로운 SDD 알고리즘을 제안한다. 제안 방법은 M-QAM 응용에서, 관찰에 가장 인접한 두 심볼을 추정의 기반으로 함으로써 기존 SDD의 계산 복잡성을 최소화하고, QAM 차수에 무관하게 연판정을 크게 단순화하였다. 아울러 심볼 추정에 임계 함수에 비해 오판정 회피가 우수한 시그모이드 함수를 적용, 추정의 신뢰도를 높였 다. 또한 등화기 갱신을 위한 오차 발생 시 임계 함수에 의한 심볼 판정 값을 오차에 가중하여 오차 변동 범위를 확장함으로 써 제안한 자기적응 등화기의 초기화 성능을 개선하였다. 결과적으로 제안 방법은 기존 SDD의 계산 복잡성과 초기화 및 수렴 특성을 현저히 개선하였다. 부가 잡음이 존재하는 다중경로 채널 조건에서 64-QAM 및 256-QAM에 대한 모의실험을 통해 CMA와 제안한 2-SDD 및 가중된 2-SDD의 두 가지 형태의 성능을 비교하고 제안 방법의 유용성을 확인하였다. For the self-adaptive equalization of higher-order QAM systems, this paper proposes a new soft decision-directed (SDD) algorithm that opens the eye patterns quickly as well as significantly reducing the error level in the steady-state when it is applied to the initial equalization stage with completely closed eye patterns. The proposed method for M-QAM application minimized the computational complexity of the existing SDD by the symbol estimated based on the two symbols closest to the observation, and greatly simplified the soft decision independently of the QAM order. Furthermore, in the symbol estimating it increased the reliability of the estimates by applying the superior properties of the sigmoid function and avoiding the erroneous estimation of the threshold function. In addition, the initialization performance was improved when an error is generated to update the equalizer, weighting the symbol decision by the threshold function to the error, resulting in an extension of the range of error fluctuations. As a result, the proposed method improves remarkably the computational complexity and the properties of initialization and convergence of the traditional SDD. Through simulations for 64-QAM and 256-QAM under multipath channel conditions with additive noise, the usefulness of the proposed methods was confirmed by comparing the performance of the proposed 2-SDD and two forms of weighted 2-SDD with CMA.

Multi-strategy structural damage detection based on included angle of vectors and sparse regularization

Huan-Lin Liu,Ling Yu,Ziwei Luo,Zexiang Chen 국제구조공학회 2020 Structural Engineering and Mechanics, An Int'l Jou Vol.75 No.4

Recently, many structural damage detection (SDD) methods have been proposed to monitor the safety of structures. As an important modal parameter, mode shape has been widely used in SDD, and the difference of vectors was adopted based on sensitivity analysis and mode shapes in the existing studies. However, amplitudes of mode shapes in different measured points are relative values. Therefore, the difference of mode shapes will be influenced by their amplitudes, and the SDD results may be inaccurate. Focus on this deficiency, a multi-strategy SDD method is proposed based on the included angle of vectors and sparse regularization in this study. Firstly, inspired by modal assurance criterion (MAC), a relationship between mode shapes and changes in damage coefficients is established based on the included angle of vectors. Then, frequencies are introduced for multi-strategy SDD by a weighted coefficient. Meanwhile, sparse regularization is applied to improve the ill-posedness of the SDD problem. As a result, a novel convex optimization problem is proposed for effective SDD. To evaluate the effectiveness of the proposed method, numerical simulations in a planar truss and experimental studies in a six-story aluminum alloy frame in laboratory are conducted. The identified results indicate that the proposed method can effectively reduce the influence of noises, and it has good ability in locating structural damages and quantifying damage degrees.

동기식 디지털 이중화 시스템을 위한 그룹핑 기법

고요한(Yo Han Ko),박창환(Chang Hwan Park),박경원(Kyung Won Park),전원기(Won Gi Jeon),백종호(Jong Ho Paik),이석필(Seok Pil Lee),조용수(Yong Soo Cho) 한국통신학회 2009 韓國通信學會論文誌 Vol.34 No.4C

본 논문에서는 OFDMA(Orthogonal Frequency Division Multiple Access) 기반 동기식 디지털 이중화(Synchronous Digital Duplexing) 방식에 적합한 그룹핑 기법을 제안한다. SDD 방식은 상호 레인징(mutual ranging) 과정을 통해 획득한 상호 시간 정보와 상호 채널 정보를 이용하여 상ㆍ하향링크 신호를 동시에 전송 가능하기 때문에 자원 할당의 유연성과 데이터 전송 효율이 증가하는 장점을 갖는다. 그러나 AP(access point)와 각 SS(subscriber station), SS와 다른 SS 사이의 상호 시간 지연과 상호 채널 길이의 합이 CP(cyclic prefix) 길이보다 긴 경우에는 OFDMA 심볼의 직교성을 유지하기 위해 추가의 CS(cyclic suffix)를 삽입해야하는 단점이 있다. 본 논문에서는 SDD 방식에서 추가의 CS가 필요한 경우에 CS 길이를 최소화하기 위하여 셀 내에 존재하는 AP 혹은 SS를 그룹으로 구분하여 송ㆍ수신 시간을 제어하는 그룹핑 기법을 제안하며, 모의실험을 통해 성능을 비교 분석한다. In this paper, we propose a grouping technique for the SDD(Synchronous Digital Duplexing) based on OFDMA(Orthogonal Frequency Division Multiple Access). The SDD has advantages of increasing data efficiency and flexibility of resource since SDD can transmit uplink signals and downlink signals simultaneously by using mutual time information and mutual channel information, obtained during mutual ranging process. However, the SDD has a disadvantage of requiring additional CS to maintain orthogonality of OFDMA symbols when the sum of mutual time difference and mutual channel length between AP(access point) and SS(subscriber station) or among SSs are larger than CP length. In order to minimize the length of CS for the case of requiring additional CS in SDD, we proposes a grouping technique which controls transmit timing and receive timing of AP and SS in a cell by classifying them into groups. Performances of the proposed grouping technique are evaluated by computer simulation.

옥내 환경에서 무선 전송을 위한 동기식 디지털 이중화 방식

박창환(Chang Hwan Park),고요한(Yo Han Ko),박경원(Kyung Won Park),전원기(Won Gi Jeon),백종호(Jong Ho Paik),이석필(Seok Pil Lee),조용수(Yong Soo Cho) 한국통신학회 2008 韓國通信學會論文誌 Vol.33 No.12C

본 논문에서는 무선 전송 시스템에서 OFDMA(Orthogonal Frequency Division Multiple Access) 방식을 사용하여 상향링크 신호와 하향링크 신호를 동시에 전송하면서 자원의 효율을 높이고 자원 할당의 유연성을 향상시킬 수 있는 디지털 이중화 방식으로 SDD(Synchronous Digital Duplexing) 방식을 제안한다. SDD 방식은 상·하향링크 신호를 동시에 송·수신하기 위해 상호 레인징(mutual ranging) 과정을 통하여 AP(access point)와 각 SS(subscriber station), SS와 다른 SS 사이의 상호 시간 동기 정보와 상호 채널 정보를 획득한다. 획득한 정보는 전송시간 선택 및 CS 삽입 여부 판단, CS 길이 설정, FFT 구간 재설정 등에 이용된다. 제안된 SDD 방식이 무선채널에서 사용되는 기존의 이중화 방식인 TDD(Time Division Duplexing), FDD(Frequency Division Duplexing)와 비교하여 옥내 환경에서 적합한 이중화 방식임을 확인한다. In this paper, we propose a new digital duplexing scheme, called SDD(Synchronous Digital Duplexing), which can increase data efficiency and flexibility of resource by transmitting uplink signal and downlink signal simultaneously. In order to transmit uplink data and downlink data simultaneously, the proposed SDD obtains mutual informations between AP(access point) and each SSs(subscriber station), SS and other SSs by mutual ranging procedure. These informations are used for selection of transmission time, decision of CS insertion, setting of CS length, and FFT duration resetting, etc. It is shown that the proposed SDD is appropriate for duplexing scheme in indoor environments over the conventional TDD(Time Division Duplexing) and FDD(Frequency Division Duplexing).

계절성 우울증의 신경내분비계 소견

박진한,신정호,송인권 大韓神經精神醫學會 1994 신경정신의학 Vol.33 No.1

The authors investigated neuroendocrine findings of HPA and HPT axes by DCT, DST, and TRH stimulation tests in patients with seasonal depressive disorder(SDD). Subjects were consisted of 11 inpatients(3 males, 8 females) with SDD and 10 control inpatients(10 females) with non-seasonal depressive disorder(NSDD) at the Department of Psychiatry, Yonsei University Wonju Medical College from Sep. 1, 1991 to Dec. 31, 1992. The results were as the following: 1) For DCT in SDD patients, 8 patients(72.6%) showed abnormal cortisol secretion, two(18.2%) with distorted diurnality and six(54.5%) with over-secretion pattern, which did not show significant difference from the control patients. 2) For DST, non-suppression rate was similiar in both group(36.4% for SDD vs 40.0% for NSDD). 3) Blunted TRH stimulation test was noted in 5 among 11 SDD patients(45.5%) compared to 1 among 10 control patients(10.0%). 4) With DST and TRH stimulation test result, the diagnostic senstivity for patients with SDD(63.7%) was higher than that for NSDD patients(50.0%). 5) In patients with SDD, symptoms of decreased libido, increased duration of sleep and daytime drowsiness items by Boyce and Parker were more prevalent(p<0.05), and symptoms of early morning awakening, decreased duration of sleep were less prevalent(p<0.05).

SYMMETRIC DIVISION DEG (SDD) INDEX, SDD AND RANDIC MATRICES

K. Srinivasa Rao,B. AMUDHA 장전수학회 2021 Proceedings of the Jangjeon mathematical society Vol.24 No.3

In this paper, the symmetric division deg index of a graph is studied and several bounds for this index are obtained. Also relations between SDD and Randic indices are obtained by means of SDD and Randic matrices.

A hybrid self-adaptive Firefly-Nelder-Mead algorithm for structural damage detection

Chu-Dong Pan,Ling Yu,Ze-Peng Chen,Wen-Feng Luo,Huan-Lin Liu 국제구조공학회 2016 Smart Structures and Systems, An International Jou Vol.17 No.6

Structural damage detection (SDD) is a challenging task in the flied of structural health monitoring (SHM). As an exploring attempt to the SDD problem, a hybrid self-adaptive Firefly-Nelder-Mead (SA-FNM) algorithm is proposed for the SDD problem in this study. First of all, the basic principle of firefly algorithm (FA) is introduced. The Nelder-Mead (NM) algorithm is incorporated into FA for improving the local searching ability. A new strategy for exchanging the information in the firefly group is introduced into SA-FNM for reducing the computation cost. A random walk strategy for the best firefly and a self-adaptive control strategy of three key parameters,such as light absorption, randomization parameter and critical distance, are proposed for preferably balancing the exploitation and exploration ability of the SA-FNM. The computing performance of the SA-FNM is evaluated and compared with the basic FA by three benchmark functions. Secondly, the SDD problem is mathematically converted into a constrained optimization problem, which is then hopefully solved by the SA-FNM algorithm. A multi-step method is proposed for finding the minimum fitness with a big probability. In order to assess the accuracy and the feasibility of the proposed method, a two-storey rigid frame structure without considering the finite element model (FEM) error and a steel beam with considering the model error are taken examples for numerical simulations. Finally, a series of experimental studies on damage detection of a steel beam with four damage patterns are performed in laboratory. The illustrated results show that the proposed method can accurately identify the structural damage. Some valuable conclusions are made and related issues are discussed as well.

옥내 환경에서 무선 전송을 위한 동기식 디지털 이중화 방식

박창환,고요한,박경원,전원기,백종호,이석필,조용수 한국통신학회 2008 韓國通信學會論文誌 Vol.33 No.12

본 논문에서는 OFDM(Orthogonal Frequency Division Multiplexing) 기반의 무선 통신시스템에서 상향링크와 하향링크의 신호에 다른 부반송파를 할당함으로써 이중화(duplexing)의 유연성과 효율성과 향상시킬 수 있는 디지털 이중화 방식으로 SDD(Synchronous Digital Duplexing)방식을 제안한다. SDD 방식은 상호 레인징(mutual ranging) 과정을 통하여 인접한 모든 SS(Subscriber Station)의 시간 동기를 획득하고 이를 이용한 각 SS의 심볼 타이밍 구간 재설정으로 ISI(Inter-Symbol Interference)와 ICI(Inter-Carrier Interfernce)의 영향없이 상향링크와 하향링크 신호를 동시에 송·수신할 수 있는 방식이다. 제안된 SDD 방식이 기존의 이중화 방식인 TDD(Time Division Duplexing), FDD(Frequency Division Duplexing), Zipper와 비교하여 옥내 환경에서 적합한 이중화 방식임을 확인한다.

A Synchronous Digital Duplexing Technique for OFDMA-Based Indoor Communications

PARK, Chang-Hwan,KO, Yo-Han,KIM, Yeong-Jun,PARK, Kyung-Won,JEON, Won-Gi,PAIK, Jong-Ho,LEE, Seok-Pil,CHO, Yong-Soo The Institute of Electronics, Information and Comm 2009 IEICE TRANSACTIONS ON COMMUNICATIONS - Vol.92 No.7

<P>In this paper, we propose a new digital duplexing scheme, called synchronous digital duplexing (SDD), which can increase data efficiency and flexibility of resource by transmitting uplink signal and downlink signal simultaneously in wireless communication. In order to transmit uplink and downlink signals simultaneously, the proposed SDD obtains mutual information among subscriber stations (SSs) with a mutual ranging symbol. This information is used for selection of transmission time, decision on cyclic suffix (CS) insertion, determination of CS length, and re-establishment of FFT starting point.</P>

만성치주염 환자에 대한 저용량 독시싸이클린의 임상적 효과

김윤식,백정원,김창성,최성호,김종관,Kim, Yoon-Sik,Paik, Jeong-Won,Kim, Chang-Sung,Choi, Seong-Ho,Kim, Chong-Kwan 대한치주과학회 2002 Journal of Periodontal & Implant Science Vol.32 No.2

Periodontal disease is a complex infectious disease caused by bacteria in the oral mucosa, which results in gingival inflammation, breakdown of periodontal tissues, bone resorption, and finally tooth loss. Mechanical plaque control methods-scaling and root planing are effective methods to stop the progression of such periodontal disease. It was reported that subantimicrobial dose of doxycycline(SDD) regimen could improve clinical conditions of periodontal tissues without causing the overgrowth of opportunistic organisms that was a typical antibiotic side effect. Therefore pharmacological therapy, used in conjunction with mechanical therapy could be considered a useful treatment modality in the treatment of chronic periodontal disease. In this study, 30 patients diagnosed as moderate to advanced chronic periodontitis were divided into 2 groups. In this double-blind, placebo-controlled study, the patients were administered 20mg doxycycline capsule or placebo capsule b.i.d. for 4months, after scaling and root planing. Clinical parameters-bleeding on probing, pocket depth and clinical attachment level were compared and evaluated between these groups at periods of first visit, 1 month, 2 months, 3 months, 4 months. The results were as follows ; 1. In case of moderate periodontitis, pocket depth showed significant reduction after treatment in both the control & experiment groups, when compared with the baseline values(p<0.01), but in case of advanced periodontitis, only the experiment group showed significant reduction after treatment when compared with the baseline values(p<0.05). Statistically significant reduction in pocket depth was observed in the experiment group compared to the control group(p<0.05). 2. In case of moderate periodontitis, clinical attachment level showed significant reduction after treatment in both the control & experiment groups, when compared with the baseline values(p<0.01), but in case of advanced periodontitis, only the experiment group showed significant reduction after treatment when compared with the baseline values(p<0.05). Statistically significant reduction in clinical attachment level was observed in the experiment group compared to the control group(p<0.05). 3. Bleeding on probing improved after treatment in both the groups. In case of moderate periodontitis, the experiment group showed statistically significant reduction of bleeding on probing when compared with the control group at 1 and 4 months after treatment(p<0.05). In case of advanced periodontitis, treatment resulted in statistically significant reduction of bleeding on probing in both the groups(p<0.05). These results indicate that the use of subantimicrobial dose of doxycycline is a useful supplement to mechanical treatment for periodontal patients in ameliorating the clinical parameters such as periodontal pocket, attachment level, and bleeding on probing.