• ETRI Journal
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• v.30 no.6
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• pp.807-817
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• 2008

We present a low-density parity-check (LDPC)-based, threaded layered space-time-frequency system with emphasis on the iterative receiver design. First, the unbiased minimum mean-squared-error iterative-tree-search (U-MMSE-ITS) detector, which is known to be one of the most efficient multi-input multi-output (MIMO) detectors available, is improved by augmentation of the partial-length paths and by the addition of one-bit complement sequences. Compared with the U-MMSE-ITS detector, the improved detector provides better detection performance with lower complexity. Furthermore, the improved detector is robust to arbitrary MIMO channels and to any antenna configurations. Second, based on the structure of the iterative receiver, we present a low-complexity belief-propagation (BP) decoding algorithm for LDPC-codes. This BP decoder not only has low computing complexity but also converges very fast (5 iterations is sufficient). With the efficient receiver employing the improved detector and the low-complexity BP decoder, the proposed system is a promising solution to high-data-rate transmission over selective-fading channels.

• JSTS:Journal of Semiconductor Technology and Science
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• v.12 no.3
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• pp.341-352
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• 2012

This paper presents a Processing Engine (PE) which is used in Low Density Parity Codec (LDPC) application with a novel charge-recovery logic called pseudo-NMOS boost logic (pNBL), to achieve high-speed and low power dissipation. pNBL is a high-overdriven and low area consuming charge recovery logic, which belongs to boost logic family. Proposed Processing Engine is used in LDPC circuit to reduce operating power dissipation and increase the processing speed. To demonstrate the performance of proposed PE, a test chip is designed and fabricated with 0.18 2m CMOS technology. Simulation results indicate that proposed PE with pNBL dissipates only 1 pJ/cycle when working at the frequency of 403 MHz, which is only 36% of PE with the conventional static CMOS gates. The measurement results show that the test chip can work as high as 609 MHz with the energy dissipation of 2.1 pJ/cycle.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2014.06a
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• pp.246-247
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• 2014

케이블 방송망에서 최대 10Gbps 테이터 전송을 위해 최근 북미에서 표준화된 DOCSIS 3.1(Data over Cable Service Interface Specifications Version 3.1)에서는 고차 혼합 변조(Mixed Modulation) 방식을 제시하였다. DOCSIS 3.1 은 하향 데이터 전송을 위해 최대 192MHz 의 대역에서 4K 또는 8K 다중 직교 반송파를 사용한다. 특히 채널 오류 정정을 위한 채널 부호화 방법으로 유럽의 차세대 케이블 방송 표준인 DVB-C2(Digital Video Broadcasting - Cable Version 2)에 정의된 BCH(Bose, Chaudhuri, and Hocquenghem)와 LDPC(Low Density Parity Check) 연접부호를 사용한다. 단, DOCSIS 3.1 에서는 DVB-C2 와 달리 부호율 8/9 의 Short Mode 부호만을 사용하며 최대 16384-QAM 까지 사용한다. 하나의 부호율을 사용하기 때문에 QAM 차수에 따른 요구 SNR 의 차가 크게 된다. 주어진 채널 상황에서 최적의 전송용량을 얻기 위해 QAM 차수에 따른 요구 SNR 의 차를 줄일 수 있는 방법으로 혼합 변조가 도입되었으며, 본 논문에서는 혼합 변조에 따른 수신 성능을 제시한다.

• Korean Journal of Veterinary Research
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• v.59 no.4
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• pp.181-185
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• 2019

The traditional calculation of gestation length (GL) in Holstein cows relies solely on the insemination day and has a high error rate for actual calving dates. The present study was conducted to develop a more accurate method of estimating GL. Among 3,578 Holstein cows, the number of fetuses had a significant (p < 0.05) effect, with GLs of 282.4 ± 2.5 days for singletons and 276.0 ± 1.6 days for twins. Within the singleton group, the GLs were 284.6 ± 1.9 days for males and 280.3 ± 1.5 days for females, a significant difference (p < 0.05). However, within the twin group, there was no difference in GLs among twin males, twin females, or twins of both sexes. Gestation was significantly shorter for singleton males born from June to August but significantly longer for twin males born in the May to June period (p < 0.05). Neither parity nor housing type was associated with any significant difference in GL. In order to predict the calving dates of Holstein cows accurately and improve their management, calculations should consider the number and sex of fetuses as well as the insemination season.

• The Journal of Korean Obstetrics and Gynecology
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• v.23 no.4
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• pp.95-108
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• 2010

Purpose: This study was to investigate the correlation among body weight, body composition, delivery method, parity, weight gain during pregnancy and obesity before pregnancy of patients who received postpartum care in one oriental medicine hospital. Mothods: From September 1, 2009 to August 31, 2008, we included 34 postpartum patients who had body composition analysis when admission and discharge among 47 postpartum patients who were hospitalized and received postpartum care in $\bigcirc\bigcirc$ University $\bigcirc\bigcirc$ Hospital. We used SPSS 14.0 for window to test for statistical significance. Results: After postpartum care, body weight and BMI of mothers was significantly decreased and the weight loss was almost body water. Mothers who had cesarean section had relatively severe edema and mothers who had been overweight before pregnancy had high BMI, body fat and abdominal fat. After delivery, body fat percentage was increased highly and body weight retention lasted long in mothers who had gained over 12.5kg during pregnancy. Conclusion: Living habits including diet has a significant effect on weight change of mothers during early puerperium, therefore it is required to teach mothers about breast-feeding, diet, and exercise to help their weight return to normal.

• Korean Parent-Child Health Journal
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• v.3 no.1
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• pp.15-26
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• 2000

These days Women have repented their past when they were inactive in attaining their own rights and they've payed attentions in gaining their fundamental rights, especially health rights. The spread of contraception use is important to fulfill women's health right. There are a lot of meanings in the contraception use. It makes women can control their reproductive activities such as pregnancy, delivery, and raising children etc. It gives each woman has autonomy of her life. The review reveals high contraceptive rate and high experienced artificial abortion rate in Korea. It means Korean married couples use contraception inefficiently. From 1970's to 1980's, most of the researches in contraceptions were descriptive and survey studies. Since 1990's, the studies have researched in the feministic perspectives. In order to understand experiences of contraceptive behaviors, qualitative researches through indepth interview did. But the number of researches were limited. The relating factors to contraceptive behavior are knowledge, communication between couples, efficiency of contraceptives, self efficacy, attitudes toward contraception, national policy, mass media, public opinion, age, parity, abortion history, ever-used contraceptive method and educational level. Theses factors affect contraception directly and indirectly. Therefore. researches about contraceptives in the future must focus on development of contraceptive behavior assessment tools and further study should be comprehensive and multidementional.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.11
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• pp.19-23
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• 2010

In this paper, we propose a combining scheme for partial IR based hybrid ARQ in MIMO systems. The proposed combining scheme is a symbol-level combining scheme for repeatedly transmitted systematic symbols in partial IR based hybrid ARQ. In this paper, it is shown that the proposed combining scheme can also enhance the detection performance of the parity symbols that are newly transmitted in each retransmission. Simulation results show that the proposed combining scheme significantly improves the performance of the partial IR based hybrid ARQ compared to the cases of the conventional bit-level combining scheme, especially with the ZF detection.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.5
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• pp.1149-1159
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• 1998

This paper presents the Controllable Self-Checking(CSC) Checker at which can be used the Fault-Tolerant System with the redundancy. According to the critical level of output(of system), especially, it can be instructed the time if it has to check the output or not. We adop the deterministic test, performed on-line, to detect the faults with a minimal test set. The results show the Parity 2-rail checker(P-TRC) which is designed much simpler than the checker has the higher fault coverage than the existent checker.

• The Journal of Information Technology
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• v.4 no.1
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• pp.71-79
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• 2001

This paper presents an adaptive back propagation algorithm that update the learning parameter by the generated error, adaptively and configuration of the range for the initial connecting weight according to the different maximum target value from minimum target value. This algorithm is expected to escaping from the local minimum and make the best environment for the convergence. On the simulation tested this algorithm on three learning pattern. The first was 3-parity problem learning, the second was $7{\times}5$ dot alphabetic font learning and the third was handwritten primitive strokes learning. In three examples, the probability of becoming trapped in local minimum was reduce. Furthermore, in the alphabetic font and handwritten primitive strokes learning, the neural network enhanced to loaming efficient about 27%~57.2% for the standard back propagation(SBP).

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.6
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• pp.1255-1260
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• 2011

In this paper, we study on the reliability of Very High-rate Power Line Communication (VH-PLC) for Smart Grid, so that the resultant data rate is over 400Mbps at a physical layer. Firstly, reviewing the research trend of the PLC, we discuss the required techniques for supporting the Smart Grid. Considering a pre-specification with the value of several parameters, we investigate a multi-carrier modulation technique to overcome limitations of higher rate transmission under power line channel environments. Then, we propose a system specification of the VH-PLC in the sense of enhancing two features. One is resolving the problem of the co-existence of the deployed high-speed PLC according to the published standardization of KS X 4600-1 in Korea. The other is getting better performance on the grid adopting the diverse element techniques, such as multi-carrier modulation, a subcarrier utilization mode, a variable rate LDPC (Low Density Parity Check) code, and a time and frequency diversity technique. Further, a simulation tool, composed of an Event-Driven simulator and a Time-Driven simulator, is developed for the purpose of verifying the system performance and continuously cross-checking the test bench signal of the proposed VH-PLC system.