LLR 기반의 MPE-FEC 상위계층 복호 방식

김철승,김민혁,김남수,정지원,Kim, Chul-Seung,Kim, Min-Hyuk,Park, Tae-Doo,Kim, Nam-Soo,Jung, Ji-Won 한국정보통신학회 2009 한국정보통신학회논문지 Vol.13 No.10

이동체에 대해서 위성을 이용한 통신 방식을 규정하고 있는 DVB-SSP 표준화에서는 Physical Layer와 Upper Layer의 두 단계로 부호화 및 복호화를 한다. 수신단에서 Physical Layer의 복호 방식인 LDPC 복호 후 Upper Layer의 erasure RS 복호를 위해, CRC 검사를 수행하여 수신된 데이터에서 1 bit의 오류발생에도 IP 패킷 모두를 삭제함으로써 복호 시 비효율성을 증가시킬 수 있다. 따라서 본 논문에서는 LDPC 복호기에 출력되는 LLR 값을 이용하여 IP 패킷 전체를 삭제하는 것이 아니라 LLR 값이 낮은 비트만 선택적으로 삭제하는 방식을 제안하며, 이를 시뮬레이션 하여 기존의 CRC 방식과 비교하였다. DVB-SSP is a new broadcasting system for hybrid satellite communications, which supports mobile handheld systems and fixed terrestrial systems. An upper layer, including erasure Reed-Solomon error correction combined with cyclic redundancy check. However, a critical factor must be considered in upper layer decoding. If there is only one bit error in an IP packet, the entire IP packet is considered as unreliable bytes, even if it contains correct bytes. If, for example, there is one real byte error, in an IP packet of 512 bytes, 511 correct bytes are erased from the frame. Therefore, this paper proposed upper layer decoding methods; LLR-based decoding. By means of simulation we show that the performance of the proposed decoding algorithm is superior to that of the conventional one.

양식어장 보호를 위한 원격감시시스템의 구축방안에 관한 연구

김철승,정중식,박성현,Kim, Chul-Seung,Jeong, Jung-Sik,Park, Sung-Hyeon 해양환경안전학회 2004 海洋環境安全學會誌 Vol.10 No.2

국민소득 증가에 따라 고급해산물의 수요가 늘어나고 있으며, 어패류 및 해조류를 포함하는 양식어업은 국내어업에 대한 총수입중 $50.6\%$를 차지하고 있는 어가의 주 소득원 중의 하나이다. 최근 국내어장에서 불규칙하게 발생하는 어패류 도난사건의 피해액은 매년 건당 수십만에서 수천만원 이상으로 증가하고 있는 실정이다. 본 연구에서는 국내 영세어가에 적용할 수 있는 양식어장 보호를 위한 레이더 감시시스템의 모델을 제안하고, 시스템의 구축방안을 제시하였다. 국외에서 양식어장보호 감시시스템이 개발된 바가 있지만 구축비용이 고가이므로 국내 영세어가에 적용하기에는 어렵다. As GNP increases, many peoples need the seafood with high quality. In Korea, aquaculture is one of major incomes for fishing households and records $50.6\%$ of total incomes for domestic fishery. The loss of aquaculture farm due to thievery at sea increases every year. In this research, we propose the system model for development of radar surveillance system, which protects aquaculture farms. For the proposed system, general requirements are described Our system is cost-effective when it is applied to domestic fishing households.

무선 랜 규격에서의 고속 알고리즘을 이용한 LDPC 복호기 구현

김철승,김민혁,박태두,정지원,Kim, Chul-Seung,Kim, Min-Hyuk,Park, Tae-Doo,Jung, Ji-Won 한국정보통신학회 2010 한국정보통신학회논문지 Vol.14 No.12

본 연구에서는 무선 랜 표준안인 802.11n에서 채널 부호화 알고리즘으로 채택된 LDPC부호의 복호 알고리즘의 저복잡도에 대해 연구를 하였다. 샤논의 한계에 근접하기 위해서는 큰 블록 사이즈의 LDPC 부호어 길이와 많은 반복횟수를 요구한다. 이는 많은 계산량을 요구하며, 그리고 이에 따른 전력 소비량(power consumption)을 야기 시키므로 본 논문에서는 세 가지 형태의 저복잡도 LDPC 복호 알고리즘을 제시한다. 첫째로 큰 블록 사이즈와 많은 반복 횟수는 많은 계산량과 전력 소모량을 요구하므로 성능 손실 없이 반복횟수를 줄일 수 있는 부분 병렬 방법을 이용한 복호 알고리즘, 둘째로 early stop 알고리즘에 대해 연구 하였고, 셋째로 비트 노드 계산과 체크 노드 계산 시 일정한 신뢰도 값보다 크면 다음 반복 시 계산을 하지 않는 early detection 알고리즘에 대해 연구 하였다. 위 세가지 알고리즘을 적용하여 FPGA 칩에 구현한 결과 N=648, R=1/2일 때, 복호 속도는 알고리즘을 적용하지 않았을 때 보다 거의 두배에 가까운 110Mbps이고, 약 45%의 디바이스 사용량이 감소하였다. In this paper, we first review LDPC codes in general and a belief propagation algorithm that works in logarithm domain. LDPC codes, which is chosen 802.11n for wireless local access network(WLAN) standard, require a large number of computation due to large size of coded block and iteration. Therefore, we presented three kinds of low computational algorithms for LDPC codes. First, sequential decoding with partial group is proposed. It has the same H/W complexity, and fewer number of iterations are required with the same performance in comparison with conventional decoder algorithm. Secondly, we have apply early stop algorithm. This method reduces number of unnecessary iterations. Third, early detection method for reducing the computational complexity is proposed. Using a confidence criterion, some bit nodes and check node edges are detected early on during decoding. Through the simulation, we knew that the iteration number are reduced by half using subset algorithm and early stop algorithm is reduced more than one iteration and computational complexity of early detected method is about 30% offs in case of check node update, 94% offs in case of check node update compared to conventional scheme. The LDPC decoder have been implemented in Xilinx System Generator and targeted to a Xilinx Virtx5-xc5vlx155t FPGA. When three algorithms are used, amount of device is about 45% off and the decoding speed is about two times faster than convectional scheme.

IEEE1394 기반 AV 콘텐츠 공유를 위한 DLNA DMS 설계 및 구현

김철승,김구수,엄영익,Kim, Chul-Seung,Kim, Gu-Su,Eom, Young-Ik 한국정보처리학회 2006 정보처리학회논문지D Vol.13 No.7

With the progress of home network technologies, the importance of the home network middleware for control and management of the digital appliances is increasing. Furthermore, by the technological growth of the AV equipments and the popularization of video contents, IEEE1394 for the transmission of AV data has spread fast. However, DLNA(Digital Living Network Alliance), which is a standard of the home network middleware, does not consider the transmission of AV data over IEEE1394. In this paper, we describe the problem occurring when the AV contents are transmitted over IEEE1394 in DLNA and propose the scheme for transmission of AV contents over IEEE1394. In addition, by the verification test of DLNA compatibility, we show that our proposed scheme can provide the share of AV contents without regard to the manufactures and transmission media. 홈 네트워크 기술의 발달로 가전기기와 정보기기의 제어 및 관리를 위한 홈 네트워크 미들웨어 기술에 대한 중요성이 확대되고 있다. 또한 AV(Audio Video) 기기의 발전과 영상 콘텐츠의 급속한 보급으로 인해 AV 전송을 위한 IEEE1394의 사용이 증가되고 있다. 그러나 홈 네트워크 미들웨어 표준인 DLNA(Digital Living Network Alliance)에서는 IEEE1394를 통한 AV 데이터 전송에 대한 고려가 미흡하다. 본 논문에서는 DLNA를 통해 EEE1394 상에서 AV 콘텐츠를 공유할 때 발생하는 문제점을 설명하고, 이를 해결하기 위한 AV 콘텐츠의 전송과 공유 방법을 제안한다. 또한 본 논문에서 제안한 기법의 DLNA 호환성 검증을 통하여, 댁내에서 가전기기 및 정보기기의 제조사 및 전송매체에 구애받지 않는 AV 콘텐츠 공유가 가능함을 보인다.

PTT를 이용한 자전거 운동 중 지속적인 혈압의 예측

김철승,문기욱,권정훈,엄광문,Kim, Chul-Seung,Moon, Ki-Wook,Kwon, Jung-Hoon,Eom, Gwang-Moon 대한의용생체공학회 2006 의공학회지 Vol.27 No.6

The purpose of this work is to predict the systolic blood pressure (BP) during exercise from pulse transit time (PTT) for warning of possible danger. PTT was calculated as the time between R-peak of ECG and the peak of differential photoplethysmograph (PPG). For the PTT-BP model, we used regress equations from previous studies and 3 kinds of new models combining linear and nonlinear regress equation. The model parameters were estimated with the data measured under low to middle intensity exercise, and then was tested with the data measured under high intensity exercise. Predicted BP values after high intensity exercise were compared with those measured by cuff-type sphygmomanometer. The results showed that the error between measured and predicted values were acceptable for the monitoring BP. We tested PTT-BP models 1 month after the identification without further calibration. Models could predict the BP and the errors between measured and predicted BP were about 5mmHg. The suggested system is expected to be helpful in recognizing any danger during exercise.

양성돌발성 두위현훈의 역학

김철승 ( Chul Seung Kim ),박상묵 ( Sang Muk Park ) 대한임상검사과학회 2008 대한임상검사과학회지(KJCLS) Vol.40 No.1

Benign paroxysmal positional vertigo (BPPV) is one of the most common clinical entities encountered in a dizzness clinic. Retrosepective review was performed for the patient’s diagnosed as BPPV at Sunchon “S” hospital dizzness center. Variables for statistical analysis included age, sex, involved canal presence of recent head tramua, presence of chronic otitis media, history of middle ear surgery, underlying disease such as hypertension or diabetics, headache, central lesion. From July 2004 to May 2005, we sampled the 600 dizzness patient``s who visited the dizzness center. Dizzness could be classified into BPPV, vestibulopathy. Among these patients, 256 patients had BPPV, 222 patients had vesibulopathy and 97 patients had Normal. Among these BPPV patients, 80 patients had lateral canalolithiasis BPPV (31.3%), 28 patients had lateral cupulolithiasis BPPV (10.9%), 90 patients had posterior canalolithiasis BPPV (35.2%), 7 patients had multicanalolithiasis BPPV (2.3%), 52 patients simultaneously had BPPV, other vestibular disease, and central lesion (20.3%).

〈속보논문〉 PTT를 이용한 운동 중 혈압 예측을 위한 Local과 Global Fitting의 비교

金哲承(Chul-Seung KIM),文基旭(Ki-Wook MOON),嚴光文(Gwang-Moon EOM) 대한전기학회 2007 전기학회논문지 Vol.56 No.12

The purpose of this work is to compare the local fitting and global fitting approaches while applying regression model to the PTT-BP data for the prediction of exercise blood pressures. We used linear and nonlinear regression models to represent the PTT-BP relationship during exercise. PTT-BP data were acquired both under resting state and also after cycling exercise with several load conditions. PTT was calculated as the time between R-peak of ECG and the peak of differential photo-plethysmogram. For the identification of the regression models, we used local fitting which used only the resting state data and global fitting which used the whole region of data including exercise BP. The results showed that the global fitting was superior to the local fitting in terms of the coefficient of determination and the RMS (root mean square) error between the experimental and estimated BP. The nonlinear regression model which used global fitting showed slightly better performance than the linear one (no significant difference). We confirmed that the wide-range of data is required for the regression model to appropriately predict the exercise BP.

양성돌발성 체위현훈의 치료

김철승 ( Chul Seung Kim ) 대한임상검사과학회 2008 대한임상검사과학회지(KJCLS) Vol.40 No.2

Benign paroxysmal positional vertigo (BPPV) is one of the most common clinical entities encountered in a dizziness clinic. Treatment of this disease, canalith repositioning procedures, have been reported to be successful in 44-90%. Treatment requires only one treatment visit in most patients. However, there are significant numbers of patients who require multiple treatment visits for relief. The goal of this study is to identify variables that may be associated with these difficult to treat cases. Retrospective review was performed for the patients diagnosed as BPPV at St. Carollo dizziness center. Variables for statistical analysis included age, sex, involved canal, presence of bilateral disease, presence of recent head trauma, presence of chronic otitis media, history of middle ear surgery, history of otologic surgery, unilateral vestibular loss, underlying disease such as hypertension or diabetes, change of involved canal during treatment course and number of treatment visits. Two hundred patients with BPPV who received treatment were identified from JAN. 2006 to JUN. 2007. 87% required one treatment visit, 5% required second treatment visit, and 95% were successfully treated after three treatment visits. Variables such as bilateral disease, post-traumatic BPPV, duration of symptom before treatment and change of involved canal during treatment were significantly related with number of treatments. Patient‘s with bilateral BPPV or with recent head trauma or longer duration of symptom are more likely to require multiple visits for canalith repositioning.

뒤반고리관 양성발작성 두위현기증 어지럼증 환자 이석정복술 치료에 영향을 주는 인자 분석

김철승 ( Chul-seung Kim ) 대한임상검사과학회 2018 대한임상검사과학회지(KJCLS) Vol.50 No.3

순천성가롤로병원 어지럼증 센터에 내원한 어지럼증 환자 중 뒤반고리관 양성발작성 두위현기증은 머리나 몸을 움직일 때 갑자기 빙빙도는 느낌 또는 회전성 어지럼증을 호소하는 가장 흔한 질환이다. 대부분 환자들은 1회 치료로 증상이 호전된다. 하지만, 세 번 이상 여러번 치료를 요구하는 경우도 있다. 이석정복술에 의한 뒤반고리관 양성발작성 두위현기증환자의 어지럼증 증상 회복에 영향을 주는 인자을 분석하였다. 어지럼증 환자 중 어지럼증 센터에 내원한 뒤반고리관 양성발작성두위현기증 환자를 분류하였다. 2008년 3월부터 2010년 11월까지 165명의 뒤반고리관 양성발작성두위현기증 환자 치료율을 조사하였다. 1회 치료성공율이 57.6%, 2회 치료성공율이 17.6%, 3회 치료성공율이 3.6%, 3회 이상 치료성공율이 21.2%였다. 뒤반고리관 양성발작성두위현기증 치료에 영향을 주는 인자는 외상 후, 내과적 질환, 뇌경색, 작은혈관 질환, 척추뇌바닥동맥기능부전증, 뇌혈관질환, 뇌질환, 안뜰신경염이다. 위와 같은 치료에 영향을 주는 인자들을 고려한다면 구토, 오심, 실신 등을 쉽게 치료 할 수 있을 것이다. 또한, 어지럼증 증상의 회복을 위한 이석정복술과 연관질환을 병행 치료하면 일상생활에 많은 불편함을 주고, 고통을 주는 어지럼증에서 호전될 수 있을 것이다. 앞으로 어지럼증을 유발하는 많은 인자들을 조사하고, 분석할 필요가 있을 것이다. Posterior canal benign paroxysmal positional vertigo (PCBPPV) is the most common disease among patients who visited the st. Carollo hospital dizziness center with the head suddenly feeling rolling or rotational dizziness caused by head and body movements. Most patients showed improvements in symptoms after a single treatment. On the other hand, there are more causes requiring multiple treatments. This study examined the factors affecting the canalithiasis repositioning maneuver for symptom recovery of dizziness, which is posterior BPPV. Dizziness patients who visited the dizziness center of PCBPPV were classified. From March 2008 to November 2010, the cure rate of 165 posterior BPPVs patients was investigated. The success rate after the first, second, third, and further treatments was 57.6%, 17.6%, 10.3%, and 14.5%, respectively. The factors affecting treatment of PCBPPVs included traumatic, medical disease, cerebral infarction, small vessel disease, vestbro basilar artery insufficiency (VBI), cerebrovascular disease, brain disease, and vestibuloplasty (P<0.05). Vomiting, nausea, and syncope can be treated easily by considering the factors affecting these treatments. If the related diseases are combined with the treatment of the canalithiasis repositioning maneuver for symptom recovery of dizziness, the results will show an improvement in daily life that is free from painful dizziness.

이석 정복술 후 어지럼증 치료 효과

김철승(Chul-Seung Kim) 한국산학기술학회 2021 한국산학기술학회논문지 Vol.22 No.7

본 연구는 2018년 5월부터 2019년 12월까지 전남 O 병원 어지럼증 센터에 방문한 환자 중 비디오눈떨림검사 시행한 후 반고리관별로 BPPV로 진단된 222명을 연구대상으로 하였다. 1차 이석 정복술 후 치료 시기 및 치료 후 어지럼증 지속시간과 예후 인자와의 상관관계를 1~10일 간격으로 조사하였다. 연구 결과 내과적질환(p<0.001), 메니에르씨병(p=0.006), 두통(p=0.006), 중이염(p=0.006), 청력소실(p=0.006)의 예후 인자가 존재하는 환자는 30일 이후에도 재발하는 비율이 높았다. 외상 후(p<0.001), 내과적질환(p<0.001), 메니에르씨병(p=0.006), 편두통(p=0.006), 두통(p=0.006), 소혈관질환(p=0.006), 뇌경색(p=0.006), 뇌혈관질환(p<0.001), 안뜰신경염(p=0.006), 중이염(p=0.006), 척추-뇌바닥기능부전증(p<0.001), 뇌 질환(p=0.006), 청력소실(p=0.006)이 존재하면 수회에 걸쳐 이석 정복술을 시행하더라도 어지럼증이 한달 이후에도 나타나는 경우가 많았다. 결론적으로, 30일 이후에 이석 정복술을 시행했음에도 불구하고 내과적질환, 메니에르씨병, 편두통, 두통, 소혈관질환, 안뜰신경염, 중이염, 뇌 질환, 청력소실 예후 인자가 존재하면 어지럼증이 지속되는 것을 간과해서는 안 될 것이다. This study was conducted on 222 patients who visited the dizziness center at O Hospital in Jeollanam-do from May 2018 to December 2019 and were diagnosed with Benign Paroxysmal Positional Vertigo by the semicircular canal after a video nystagmus test. After the first Canalith Repositioning Maneuver (CRM) treatment, the correlation between the treatment duration and dizziness and the prognostic factors were studied in one to 10-day intervals. According to the study, patients with the prognosis factors of internal diseases (p<0.001), Meniere"s disease (p=0.006), headache (p=0.006), otitis media (p=0.006), and hearing loss (p=0.006) were more likely to recur after 30 days. Dizziness often recurred in patients with post-traumatic (p<0.001), internal disease (p<0.001), Meniere"s disease (p=0.006), migraine (p=0.006), headache (p=0.006), small vessel disease (p=0.006), cerebral infarction (p=0.006), cerebrovascular disease (p<0.001), vestibulopathy (p=0.006), otitis media (p=0.006), vertebrobasilar insufficiency (p<0.001), brain disease (p=0.006) and hearing loss (p=0.006), even after one month from several CRM treatments. In conclusion, persistent dizziness should not be overlooked if the prognosis factors of internal disease, Meniere"s disease, migraine, headache, small vessel disease, vestibulopathy, otitis media, brain disease, and hearing loss exist, even after 30 days from CRM.