DVB-S2 기반 고속 LDPC 복호를 위한 효율적인 CNU 계산방식에 관한 연구

임병수,김민혁,정지원,Lim, Byeong-Su,Kim, Min-Hyuk,Jung, Ji-Won 한국정보통신학회 2012 한국정보통신학회논문지 Vol.16 No.9

본 논문은 DVB-S2 기반 고속 LDPC 복호를 하기 위한 효율적인 CNU(Check Node Update) 계산방식에 대해 분석하였다. LDPC의 복호 속도는 CNU 계산 과정에 의존한다. 기존의 CNU 계산방식에서 LUT를 고려한 SP(Sum-Product)방식은 속도가 늦어지는 단점이 있다. 이에 본 논문에서는 SC-NMS(Self-Corrected Normalized Min-Sum) 방식을 제안한다. LUT 연산을 제거한 MS(Min-Sum) 방식에 정규화 계수 '${\alpha}$'를 곱하는 Normalized Min-Sum(NMS) 방식은 MP 방식보다 성능은 약간 감소하지만 critical path를 없애고 클럭 주기를 줄일 수 있어 구현에 있어서 고속화를 위한 효율적인 CNU 계산방식이다. 또한, 복호과정에서 반복 시 이전 반복에서의 엣지 값과 현재 반복에서의 엣지 값을 비교하여 부호가 바뀌면 신뢰성이 없음을 간주하여 현재 엣지에 "0"을 할당하는 SC(Self-Corrected) 방식을 연구하였다. SC-NMS 방식을 적용하여 시뮬레이션 한 결과, SC-NMS 방식은 SP 방식에 비해 0.1dB의 성능열화를 보였지만, 계산의 복잡도와 복호 속도를 고려했을 때, SC-NMS 방식이 최적의 CNU 계산 방식이라는 것을 확인하였다. In this paper, efficient CNU(Check Node Update) algorithms are analyzed for high speed LDPC decoding in DVB-S2 standard. In aspect to CNU methods, there are some kinds of CNU methods. Among of them, MP (Min Product) method is quite often used in LDPC decoding. However MP needs LUT (Look Up Table) that is critical path in LDPC decoding speed. A new SC-NMS (Self-Corrected Normalized Min-Sum) method is proposed in the paper. NMS needs only normalized scaling factor instead of LUT and compensates the overestimation of MP approximation. In addition, SC method is proposed. It gives a faster convergence toward a decoded codeword. If a message change its sign between two iterations, it is not reliable and to avoid to propagate noisy information, its module is set to 0. The performance of SC-NMS has a little degrade compare to MP by 0.1 dB, however considering computational complexity and decoding speed, SC-NMS algorithm is optimal method for CNU algorithm.

전자현미경 시료 제작에 있어 Ultrasonic bath의 유용성에 관한 연구

임병수,최정목,강대영,Lim, Byung-Soo,Choi, Jeung-Mok,Kang, Dae-Young 한국현미경학회 1998 Applied microscopy Vol.28 No.3

The present study was carried out to investigate the effect of ultrasonic bath in tissue preparation for transmission electron microscopy. The method used standard reagents and media, and employed ultrasonic bath agitation to accelerate fluid exchange. The liver kidney, stomach and cardiac muscle tissues of male Sprague-Dawley rats were used for the experiment, and the experimental design was divided into 4 groups; The control group using rotators (Traditional method, 1,625 mins) and the three experimental groups using ultrasonic bath (UB) in the primary fixation through the infiltration processes (UB I; 62.5 mins, UB II; 125 mins, UB III; 250 mins). The results were as follows; 1. In the control group, tissues were easily sectioned, and showed well preserved intact membranes, and cell organelles such as mitochondria, lysosome, peroxisome, rough endoplasmic reticulum and smooth endoplasmic reticulum. 2. In the UB treated group I, tissues showed holes due to the inadequate removal of both water and fluids used in the dehydration process. Also the mitochondria of cell organelles, especially, showed swollen intracristal spaces and dense matrices due to poor fixation. 3. In the UB treated group II, tissues showed good preservation of cell organelles and specimen slice sections. Also, no holes were observed. 4. In the UB treated group III, tissues showed leaching of structural components in the cytoplasm, but no holes were observed. In conclusion, the ultrasonic bath procedure takes approximately 120 minutes from specimen fixation to resin infiltration and gives excellent results.

DVB-S2 기반 고속 LDPC 복호를 위한 Horizontal Shuffle Scheduling 방식에 관한 연구

임병수,김민혁,정지원,Lim, Byeong-Su,Kim, Min-Hyuk,Jung, Ji-Won 한국정보통신학회 2012 한국정보통신학회논문지 Vol.16 No.10

DVB-S2에 적용되는 Shannon의 채널 용량 한계에 근접한 LDPC 부호는 복호화의 낮은 복잡도와 좋은 거리 특성으로 오류마루 현상인 나타나지 않고, 완성 병렬 처리가 가능하다. 하지만 구현상에 있어서 큰 블록 사이즈 및 많은 반복 횟수 때문에 복호과정에서 고속화가 어렵다. 이에 본 논문에서는 HSS(Horizontal Shuffle Scheduling) 방식을 연구하여 최적의 반복횟수를 제시한다. 고속 복호를 위한 복호과정의 한 방법으로 HSS 방식은 체크 노드를 중심으로 체크 노드가 업데이트 되는 과정에서 비트 노드도 같이 업데이트 되기 때문에 한 번의 반복이 끝났을 때 비트노드는 여러 번 반복한 효과를 가지게 된다. 결국 기존에 제시된 반복횟수보다 HSS 방식을 적용하였을 때 더 적은 반복 횟수로 동일한 성능을 얻을 수 있다. HSS 방식을 적용하여 시뮬레이션 한 결과, 각각의 부호화율에서 동일한 성능으로 최소 30% ~ 최대 50% 만큼 반복횟수를 줄일 수 있음을 확인하였다. DVB-S2 employs LDPC codes which approach to the Shannon's limit, since it has characteristics of a good distance, error floor does not appear. Furthermore it is possible to processes full parallel processing. However, it is very difficult to high speed decoding because of a large block size and number of many iterations. This paper present HSS algorithm to reduce the iteration numbers without performance degradation. In the flooding scheme, the decoder waits until all the check-to-variable messages are updated at all parity check nodes before computing the variable metric and updating the variable-to-check messages. The HSS algorithm is to update the variable metric on a check by check basis in the same way as one code draws benefit from the other. Eventually, LDPC decoding speed based on HSS algorithm improved 30% ~50% compared to conventional one without performance degradation.

4가지 접촉식 초음파를 이용한 생체계측 시 백내장수술 후 굴절력 예측의 비교

임병수,이상규,김은철,Byung Su Lim,Sang Kyu Lee,Eun Chul Kim 대한안과학회 2014 대한안과학회지 Vol.55 No.11

Purpose: To compare ocular biometry measured using 4 applanation ultrasonographic biometry devices and evaluate the accuracies of the refractive outcomes after cataract surgery. Methods: A total of 60 eyes in 60 patients who received cataract surgery were included in the present study. The axial length was measured using applanation ultrasonographic biometry devices (Aviso?, Hi-Scan<SUP>Ⓡ, UD-6000<SUP>Ⓡ, P37-II<SUP>Ⓡ). Additionally, keratometry was measured using an autokeratometer (Topcon KR 8000) and the SRK/T formula was used to calculate intraocular lens (IOL) power. Two months after cataract surgery, the refractive outcome was determined, and results from the 4 different applanation ultrasonographic biometry devices were compared. Results: Axial lengths were 23.52 ± 1.45 mm, 23.51 ± 1.04 mm, 23.54 ± 1.58 mm, and 23.52 ± 1.38 mm measured using Aviso<SUP>Ⓡ, Hi-Scan<SUP>Ⓡ, UD-6000<SUP>Ⓡ, and P37-II<SUP>Ⓡ, respectively with no statistically significant differences observed (p = 0.92). The mean absolute error (MAE) of the Aviso<SUP>Ⓡ, Hi-Scan<SUP>Ⓡ, UD-6000?, and P37-II<SUP>Ⓡ was 0.41 ± 0.32 diopter (D), 0.40 ± 0.30 D, 0.36 ± 0.26 D, and 0.39 ± 0.26 D, respectively. The mean numerical error (MNE) was 0.39 ± 0.37 D, 0.36 ± 0.32 D, 0.26 ± 0.29 D, and 0.38 ± 0.32 D, respectively. The differences between the 4 different applanation ultrasonographic biometry devices were not statistically significant (<EM>p</EM> = 0.90, <EM>p </EM>= 0.81). Conclusions: The ocular biometric measurements and prediction of postoperative refraction using Aviso<SUP>Ⓡ, Hi-Scan?, UD-6000<SUP>Ⓡ, P37-II<SUP>Ⓡ showed no significant differences. J Korean Ophthalmol Soc 2014;55(11):1631-1635

Kaolin을 이용한 Mullite 합성에 미치는 광화제 첨가 효과

임병수,강경인,소유영,박성,이병하,Lim, Byung-Soo,Kang, Kyong-In,So, You-Young,Park, Sung,Lee, Byung-Ha 한국세라믹학회 1999 한국세라믹학회지 Vol.36 No.1

본 연구에서는 fine ceramics의 합성법을 traditional ceramics 합성에 적용하여 합성한 내화재료용 mullite에 광화제를 첨가함으로서 광화제가 mullite 생성에 미치는 영향을 관찰하고자 한다. 출발물질로 하동 kaolin과 boehmite를 사용하였으며, 여기에 광화제로 MnO와 TiO2를 액상으로 첨가하였다. 그 결과 3.5 wt% MnO를 첨가한 경우, 1,25$0^{\circ}C$에서 미반응 silica와 alumina가 존재하지 않는 단일상의 mullite를 합성할 수 있었으며, TiO2 첨가시 2~3.5wt% MnO의 경우 mullite 생성 온도를 약 10$0^{\circ}C$ 낮출 수 있었다. 이때의 mullite 생성율은 1$650^{\circ}C$에서 84%이며, 부피 비중과 흡수율 및 상온에서 꺾임강도는 각각 2.72, 0.27%, 180MPa을 나타내어 광화제를 첨가하지 않은 경우보다 특성도 향상함을 알 수 있었다. In this study, the formation of mullite phase with mineralizer have been investiagated Hadong Kaolin and boehmite were used as starting materials and also of TiCl4 and MnCl4 aquous solution were used as a mineralizer. In the addition of 3.5% MnO as a mineralizer, mullite single phase could be obtained at 125$0^{\circ}C$ without any other second phases. However in the addition of TiO2 as a mineralizer, mullite single phase is obtained at above 135$0^{\circ}C$. Therefore the formation of mullite is lowered in the case of MnO as a mineralizer than of TiO2. Because it is easy to obtain mullite single phase in the case of MnO addition, all the characteristics improved. The values of bulk density, water absorption and bending strength at room temperature were 2.72g/㎤, 0.27% and 180 MPa, respectively.

GDI 엔진의 고압연료 System NVH 개발

임병수(Byoungsoo Lim),안상준(Sangjun Ahn),김재헌(Jaeheon Kim),강구태(Kootae Kang) 한국자동차공학회 2010 한국자동차공학회 학술대회 및 전시회 Vol.2010 No.11

Gasoline Direct Injection(GDI) Engines require a high pressure fuel system, i.e. high pressure fuel pump, injectors, fuel rail and high pressure line, in order to enable the injection of fuel directly into the combustion chambers. But high pressure fuel system emits an unpleasant noise during normal operation, particularly at engine idle. This paper focuses on how to reduce the acoustic noise caused by the individual high pressure fuel system using the S/W and H/W methods.

[展望] 자동차용 재료의 전망

임병수(Byeong Soo Lim) 한국자동차공학회 1985 오토저널 Vol.7 No.1

초음파를 이용한 구조물 내부의 균열 및 미소 결함 검출

임병수(Byeongsoo Lim),배시연(Siyeon Bae),정찬서(Chanseo Jeong) 한국자동차공학회 2004 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

The initiation and growth of internal defects usually cause the failure of long term operated structural components at high temperature. Therefore, by investigating the internal defects of material, the integrity of the system can be maintained and the unexpected failure can be prevented. The main purpose of this study is to investigate the possibility of the application of ultrasound to the measurement and estimation of the creep damage. In this study, the phased array ultrasound and backward ultrasound were employed to detect the internal defects caused by creep. The former is suitable for the detection of defects existing deep in structure while the latter is for the defects on the surface or in shallow region. Using the newly developed P92 steel. both creep and NDE ultrasound tests were performed. The results of defect inspection were checked by microstructure examination. Reliable information on the size and position of crack were obtained and successful estimation of the amount of micro-voids and their distribution proved to be obtainable by the ultrasound inspection technique. The width of the creep degraded zone was confirmed by the width of ultrasonic signal, and the severity of degradation was confirmed by ultrasonic amplitude.

냉간가공된 알루미늄 점용접의 피로수명 개선

임병수(Byeongsoo Lim),류승진(Seungjin Ryu),김대욱(D. Kim) 한국자동차공학회 2005 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2005 No.5_2

The use of aluminum alloys is an attractive possible option in order to reduce the weight of automobile body structures to achieve the subsequent improvement of fuel economy and driving performance. Aluminum resistance spot welding(Al RSW), similar to current steel automobile body construction, may be considered one of the manufacturing methods for an aluminum body structure. Due to the unreliable durability of weld-bonded joints, applications of Al RSW are limited. A patented post-weld cold working process was used to improve the fatigue strength of Al RSW. The post-weld cold working process includes that special shaped indenters are pressed or driven into the structure in order to induce the compressive residual stresses. The effect of the post-weld cold working process parameters on the fatigue strength of the Al RSW was investigated. Comparisons of the fatigue properties and qualitative results between the as-welded RSW specimens and the post-weld cold worked RSW specimens are discussed.

[論文] 연강의 결정학적 경계가 기계적 성질에 미치는 영향

임병수(Byeong Soo Lim),이창훈(Chang Hoon Lee) 한국자동차공학회 1984 오토저널 Vol.6 No.4

The experimental investigation has been made to determine the effect of crystallographic boundaries and chemical composition on the strength and hardness using mild steels of SAE 1016 and 1022.<br/> Through heat treatments and quantitative analysis, different microstructures varying in grain size from 4.4㎛ to 23.2㎛ and in Fe₃C particle spacing from 0.56㎛ to 2.46㎛ were obtained.<br/> Mechanical properties of yield strength, tensile strength and micro vickers hardness were measured and the relationship between these properties and microstructures were obtained.<br/> Some of the conclusions are as follows; When mild steels are strengthened by both grain size hardening and Fe₃C precipitation hardening mechanisms;<br/> (1) the yield strength, σ_y, can be expressed in kg/mm²as σ_y=σ_t+2.35d^-½+0.0022λ^-1<br/> where σ_t: constant, d: grain size(mm), λ:Fe₃C particle spacing(mm).<br/> (2) the micro vickers hardness, MVH, can bc cxprcssed as <br/> MVH(P=500g)=H_o+5.29d^-½+0.0132λ^-1(SAE 1016)<br/> MVH(P=500g)=H_o+3.32d^-½+0.0111λ^-1(SAE 1022)<br/> where H_o is constant.<br/> (3) the tensile strength, σ_t,s. can be expressed in kg/mm² as<br/> σ_t,s^mix σ_o+1.72d^-½<br/> where σ_o is constant.<br/>