Simplified 2-Dimensional Scaled Min-Sum Algorithm for LDPC Decoder

Keol Cho,Wang-Heon Lee,Ki-Seok Chung 대한전기학회 2017 Journal of Electrical Engineering & Technology Vol.12 No.3

Among various decoding algorithms of low-density parity-check (LDPC) codes, the minsum (MS) algorithm and its modified algorithms are widely adopted because of their computational simplicity compared to the sum-product (SP) algorithm with slight loss of decoding performance. In the MS algorithm, the magnitude of the output message from a check node (CN) processing unit is decided by either the smallest or the next smallest input message which are denoted as min1 and min2, respectively. It has been shown that multiplying a scaling factor to the output of CN message will improve the decoding performance. Further, Zhong et al. have shown that multiplying different scaling factors (called a 2-dimensional scaling) to min1 and min2 much increases the performance of the LDPC decoder. In this paper, the simplified 2-dimensional scaled (S2DS) MS algorithm is proposed. In the proposed algorithm, we figure out a pair of the most efficient scaling factors which multiplications can be replaced with combinations of addition and shift operations. Furthermore, one scaling operation is approximated by the difference between min1 and min2. The simulation results show that S2DS achieves the error correcting performance which is close to or outperforms the SP algorithm regardless of coding rates, and its computational complexity is the lowest comparing to modified versions of MS algorithms.

Self-Adaptive Termination Check of Min-Sum Algorithm for LDPC Decoders Using the First Two Minima

( Keol Cho ),( Ki-seok Chung ) 한국인터넷정보학회 2017 KSII Transactions on Internet and Information Syst Vol.11 No.4

Low-density parity-check (LDPC) codes have attracted a great attention because of their excellent error correction capability with reasonably low decoding complexity. Among decoding algorithms for LDPC codes, the min-sum (MS) algorithm and its modified versions have been widely adopted due to their high efficiency in hardware implementation. In this paper, a self-adaptive MS algorithm using the difference of the first two minima is proposed for faster decoding speed and lower power consumption. Finding the first two minima is an important operation when MS-based LDPC decoders are implemented in hardware, and the found minima are often compressed using the difference of the two values to reduce interconnection complexity and memory usage. It is found that, when these difference values are bounded, decoding is not successfully terminated. Thus, the proposed method dynamically decides whether the termination-checking step will be carried out based on the difference in the two found minima. The simulation results show that the decoding speed is improved by 7%, and the power consumption is reduced by 16.34% by skipping unnecessary steps in the unsuccessful iteration without any loss in error correction performance. In addition, the synthesis results show that the hardware overhead for the proposed method is negligible.

Prediction of the Risk of Hepatocellular Carcinoma in Chronic Hepatitis C Patients after Sustained Virological Response by Aspartate Aminotransferase to Platelet Ratio Index

( Keol Lee ),( Dong Hyun Sinn ),( Geum-youn Gwak ),( Hyun Chin Cho ),( Sin-ho Jung ),( Yong-han Paik ),( Moon Seok Choi ),( Joon Hyeok Lee ),( Kwang Cheol Koh ),( Seung Woon Paik ) 대한간학회 2016 Gut and Liver Vol.10 No.5

Background/Aims: Following sustained virological response (SVR) for chronic hepatitis C (CHC) infection, patients with advanced fibrosis require regular monitoring for hepatocellular carcinoma (HCC). The aspartate aminotransferase to platelet ratio index (APRI) is a simple noninvasive surrogate marker known to reflect fibrosis. Methods: We retrospectively analyzed 598 patients who achieved SVR with interferonbased therapy for CHC. Results: Over a median of 5.1 years of follow-up, there were eight patients diagnosed with HCC and a 5-year cumulative incidence rate of 1.3%. The median pretreatment APRI was 0.83, which decreased to 0.29 after achieving SVR (p<0.001). Both the pre- and posttreatment indices were associated with HCC development. The 5-year cumulative HCC incidence rates were 0% and 2.8% for patients with pretreatment APRI <1.0 and ≥1.0, respectively (p=0.001) and 0.8% and 12.8% for patients with posttreatment APRI <1.0 and ≥1.0, respectively (p<0.001). Pretreatment APRI at a cutoff of 1.0 had a 100% negative predictive value until 10 years after SVR. Conclusions: HCC development was observed among CHC patients who achieved SVR. The pre- and post-treatment APRI could stratify HCC risk, indicating that the APRI could be a useful marker to classify HCC risk in CHC patients who achieved SVR. However, given the small number of HCC patients, this finding warrants further validation. (Gut Liver 2016;10:796-802)

The Korean Society of Gastroenterology & SIDDS 2058 : Slide Session ;K-LI-05 : Liver ; Incidence and Risk Factors for Hepatocellular Carcinoma in Chronic Hepatitis C Patients Who Achieved Sustained Virological Response.

( Keol Lee ),( Dong Hyun Sinn ),( Geum Youn Gwak ) 대한내과학회 2014 대한내과학회 추계학술대회 Vol.2014 No.1

Background: For chronic hepatitis C patients (CHC) who achieved sustained virological response (SVR), controversy exists whether patients should be screened for hepatocellular carcinoma (HCC).Methods: A total of 618 CHC patients who achieved SVR between Jan 1999 to Dec. 2010 were followed up for a median of 5.1 years (range: 0.1 ~ 14.3 years). Results: HCC was diagnosed in 8 patients. The cumulative incidence rate of HCC was 0.2%, 1.3% and 4.7% at 3 years, 5years and 10 years, respectively. The median time to development of HCC was 3.8 years after achieving SVR (range: 2.0 ~ 8.9 years), and 3 of 8 patients (38%) developed HCC even after 5 years from SVR. Post-treatment platelet levels (p5 ng/mL), and diabetes mellitus (P < 0.05). The area under receiver operating characteristics (AUROC) at 5 years were 0.956, 0.956, and 0.725 for post treatment platelet levels, post treatment APRI and post treatment AFP levels, respectively. Conclusions: Although the incidence rate was low, CHC patients who achieved SVR developed HCC, even after 5 years from achieving SVR. Long term follow-up is required for CHC patients who achieved SVR, especially for patients with risk factors including low post-treatment platelet, AFP level, and diabetes mellitus.

Case studies on the flipped classroom with a MOOC in college contexts

Keol Lim,Mi Hwa Kim 한국디지털정책학회 2019 디지털융복합연구 Vol.17 No.9

BRIEF COMMUNICATION : Esophageal Mast Cell Infiltration in a 32-Year-Old Woman with Noncardiac Chest Pain

( Keol Lee ),( Hee Jin Kwon ),( In Young Kim ),( Kwai Han Yoo ),( Seulkee Lee ),( Yang Won Min ),( Poong Lyul Rhee ) 대한간학회 2016 Gut and Liver Vol.10 No.1

Noncardiac chest pain (NCCP) is one of the most common esophageal symptoms and lacks a clearly defined mechanism. The most common cause of NCCP is gastroesophageal reflux disease (GERD). One of the accepted mechanisms of NCCP in a patient without GERD has been altered visceral sensitivity. Mast cells may play a role in visceral hypersensitivity in irritable bowel syndrome. In this case, a patient with NCCP and dysphagia who was unresponsive to proton pump inhibitor treatment had an increased esophageal mast cell infiltration and responded to 14 days of antihistamine and antileukotriene treatment. We suggest that there may be a relationship between esophageal symptoms such as NCCP and esophageal mast cell infiltration. (Gut Liver 2016;10:152-155)

Neuromyositis: A Rare Extramuscular Manifestation of Dermatomyositis

( Chan Keol Park ),( Su-jin Yoo ),( In Seol Yoo ),( Jinhyun Kim ),( Seung Cheol Shim ),( Seong Wook Kang ) 대한류마티스학회 2019 대한류마티스학회지 Vol.26 No.3

Dermatomyositis (DM) and polymyositis (PM) are representative idiopathic inflammatory myopathies characterized by symmetric and progressive proximal muscle weakness. Especially, DM is identified by characteristic skin lesions and has many extramuscular manifestations including various cardiac abnormalities, interstitial lung disease, and malignancy. However, involvement of peripheral nervous system in DM/PM is very rare and less known. The term “Neuromyositis” was introduced by Senator in 1893 to describe the concomitant involvement of the peripheral nervous system in DM/PM. Since then, a very few cases of neuromyositis have been reported mainly in the United States and Europe. Therefore, the pathogenetic mechanism and disease progression are unclear. In recent years, a few more cases were reported in Asia, specifically, China and Japan; however, none in Korea. Here, we describe a case of DM-associated neuromyositis in a 42-year-old man in Korea and review previous publications through literature research. (J Rheum Dis 2019;26:211-218)

Simplified 2-Dimensional Scaled Min-Sum Algorithm for LDPC Decoder

Cho, Keol,Lee, Wang-Heon,Chung, Ki-Seok The Korean Institute of Electrical Engineers 2017 Journal of Electrical Engineering & Technology Vol.12 No.3

Among various decoding algorithms of low-density parity-check (LDPC) codes, the min-sum (MS) algorithm and its modified algorithms are widely adopted because of their computational simplicity compared to the sum-product (SP) algorithm with slight loss of decoding performance. In the MS algorithm, the magnitude of the output message from a check node (CN) processing unit is decided by either the smallest or the next smallest input message which are denoted as min1 and min2, respectively. It has been shown that multiplying a scaling factor to the output of CN message will improve the decoding performance. Further, Zhong et al. have shown that multiplying different scaling factors (called a 2-dimensional scaling) to min1 and min2 much increases the performance of the LDPC decoder. In this paper, the simplified 2-dimensional scaled (S2DS) MS algorithm is proposed. In the proposed algorithm, we figure out a pair of the most efficient scaling factors which multiplications can be replaced with combinations of addition and shift operations. Furthermore, one scaling operation is approximated by the difference between min1 and min2. The simulation results show that S2DS achieves the error correcting performance which is close to or outperforms the SP algorithm regardless of coding rates, and its computational complexity is the lowest comparing to modified versions of MS algorithms.

A Transient Modeling Of A Fluorescent Lamp At Startup Time

Jung-Keol Ham,Soo Young Lee,Soo Hyun Baek,Ki Young Lee 전력전자학회 1995 ICPE(ISPE)논문집 Vol.1995 No.10

Fluorescent lamps are widely accepted to energy efficient commercial lighting applications. In designing a fluorescent lamp system, a ba11ast des ign heavi1y re1ies on the characterist ic of a fluorescent 1 amp under cons i derat i on. Espe-cially, at startup time, the tran­sient characteristic of a fluores­cent lamp puts much tighter specifi­cations of a design.<br/> In this paper, based on the transient characteristic at the startup time, a transient behavioral model of a fluorescent lamp is pre­sented wi th an equivalent circuit. The model is applicable to the wide range of f1uorescent 1 amps provided by different manufacturers.<br/> The experimental results are compared with the results provided by PSPICE simulation. The result shows the mode 1 i s effect ive i n practice. As a result, we could identify more accurate startup con­straints to decide the design of either an electromechanical or an electronic ballast.

Characteristic evaluation of collected strains of Hypsizygus marmoreus based on ITS rDNA sequence

Youn-Keol Nam,Youn-Lee Oh,Won-Sik Kong,Kab-Yeul Jang,Pyung-Gyun Shin,Min-Ji Oh,Eun-Seon Kim,Sung-I Woo,Chang-Duck Koo 한국버섯학회 2015 버섯 Vol.19 No.2

The aim of this study was to analyze the genetic diversity of collected strains of Hypsizygus marmoreus based on their rDNA ITS sequences. The size of ITS rDNA regions of H. marmoreus strains, collected form various regions. A phylogenetic trees based on the ITS region revealed that the strains could be classified into 4 different groups including Villosiclava virens, Hypsizygus marmoreus, Lepista irina, Lyophyllum Decastes, Lyophyllum shimeji, Pleurotus floridanus.