• ETRI Journal
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• 제27권5호
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• pp.557-562
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• 2005

Low-density parity-check (LDPC) codes have recently emerged due to their excellent performance. However, the parity check (H) matrices of the previous works are not adequate for hardware implementation of encoders or decoders. This paper proposes a hybrid parity check matrix which is efficient in hardware implementation of both decoders and encoders. The hybrid H-matrices are constructed so that both the semi-random technique and the partly parallel structure can be applied to design encoders and decoders. Using the proposed methods, the implementation of encoders can become practical while keeping the hardware complexity of the partly parallel decoder structures. An encoder and a decoder are designed using Verilog-HDL and are synthesized using a $0.35 {\mu}m$ CMOS standard cell library.

• 대한전자공학회논문지SD
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• 제43권7호
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• pp.50-57
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• 2006

Low-density parity check (LDPC) code는 최근 그 우수한 성능으로 인하여 4세대 무선 이동 통신용 채널 코딩으로 주목받고 있고 유럽의 고화질 위성방송 규격으로 채택되었다. 그러나 기존의 연구들이 제안한 parity check matrix (H-matrix)는 실제로 하드웨어로 구현함에 있어서 인코더 혹은 디코더에 제약을 가지고 있다. 이러한 문제점을 해결하고자 본 논문에서는 인코더와 디코더 양쪽 모두 효율적으로 하드웨어로 구현이 가능한 hybrid H-matrix 구조를 제안한다. Hybrid H-matrix는 semi-random 방식과 partly parallel 방식을 결합하여 하드웨어로 구현시 partly parallel 방식이 가지는 디코더의 복잡도가 감소되는 장점을 유지하면서 인코더 또한 semi-random 방식을 사용하여 복잡도가 감소된다. 제안한 구조를 사용하여 LDPC 인코더와 디코더를 설계하고 합성하여 기존의 결과와 비교하였다.

• 대한전자공학회논문지SD
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• 제43권9호
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• pp.31-37
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• 2006

Low Density Parity Check (LDPC) code는 최근 그 우수한 성능으로 인하여 4세대 무선 이동 통신용 채널 코딩으로 주목받고 있다. 또한 유럽 디지털 위성 방송 규격인 DVB-S2는 LDPC 코드를 채널 코딩방식으로 채택하였다. 본 논문에서는 인코더와 디코더 양쪽 모두 효율적으로 하드웨어 구현이 가능한 hybrid H-matrix 구조를 이용한 DVB-S2 LDPC 복호기 구조를 제안한다. Hybrid H-matrix는 semi-random 방식과 partly parallel 방식을 결합하여 부호기와 복호기를 동시에 효율적으로 구현할 수 있다. 제안된 복호기 구조에서는 다양한 코드율에 사용되는 Variable Node processor Unit (VNU)을 재사용하기 위한 새로운 VNU와 최적화된 블록 메모리 배치 방법을 이용하였다. 제안된 구조를 이용하여 코드율 1/2의 DVB-S2 LDPC 복호기를 설계하였고 그 결과를 기존의 복호기와 비교하였다.

• Wind and Structures
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• 제31권4호
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• pp.363-371
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• 2020

Proper understanding of offshore wind speed variability is of essential importance in practice, which provides useful information to a wide range of coastal and marine activities. In this paper, long-term wind speed data recorded at various offshore stations are analyzed in the framework of fractal dimension analysis. Fractal analysis is a well-established data analysis tool, which is particularly suitable to determine the complexity in time series from a quantitative point of view. The fractal dimension is estimated using the conventional box-counting method. The results suggest that the wind speed data are generally fractals, which are likely to exhibit a persistent nature. The mean fractal dimension varies from 1.31 at an offshore weather station to 1.43 at an urban station, which is mainly associated with surface roughness condition. Monthly variability of fractal dimension at offshore stations is well-defined, which often possess larger values during hotter months and lower values during winter. This is partly attributed to the effect of thermal instability. In addition, with an increase in measurement interval, the mean and minimum fractal dimension decrease, whereas the maximum and coefficient of variation increase in parallel.

• 자원환경지질
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• 제49권4호
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• pp.315-323
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• 2016

본 연구는 경기육괴 남서 연변부 홍성지역에 발달하는 편마암 내 돔 구조를 보고한다. 서해안 제1봉 오서산 주변으로 발달하여 오서산 돔으로 명명된 이 편마암 돔은 주로 신원생대-고생대의 정편마암 및 준편마암, 변성염기성화산암, 변성조립현무암으로 주로 구성된다. 이들 암석들은 혼성암화작용을 경험하였으며, 내부에는 부분용융에 의해 형성된 우백질(화강암질) 물질이 엽리면을 절단하거나 이에 평행한 패치 혹은 광맥의 형태로 빈번하게 관입되어있다. 오서산 돔은 전체적으로 동심 구조 및 외부를 향하는 내부 엽리를 보이나, 일부 영역에 발달하는 엽리는 복잡한 방향 변화를 보이거나 내부를 향하는 형태를 보이기도 한다. 그간 오서산 돔 내부에서 보고된 암석학적, 연대학적 정보들을 종합해보면, 오서산 돔은 후기 트라이아스기에 빠르게 상부지각으로 융기하였으며 이와 유사한 시기에 일부 부분용융작용 및 화강암의 관입을 경험하였다. 더불어 주변으로는 후기 트라이아스기의 운동동시성 화강암에 의해 관입되어 있는 확장성 전단대 및 퇴적분지 발달이 보고된 바 있다. 이러한 양상은 오서산 돔이 후기 트라이아스기 확장성 운동 및 이에 수반된 다이어퍼 상승흐름과 연관되어 형성되었을 가능성을 지시할 수 있다. 또 다른 시각에서 편마암 내 돔 구조의 발달이 후기 트라이아스기~중기 쥬라기 퇴적분지의 구조역전 과정에서 1) 충상단층 내지는 역단층에 수반되었거나, 2) 독립적인 습곡들의 상호 간섭에 의해 야기되었을 가능성 역시 배재할 수는 없다. 하지만 돔의 북측 날개부가 후기 트라이아스기 화강암에 의해 절단되어 있는 양상이나 남측 날개부가 압축변형 과정에서 재활성된 단층에 의해 절단되어 있는 양상을 미루어 보았을 때, 편마암 내 돔 구조의 발달 시기는 후기 트라이아스기 혹은 그 이전일 가능성이 높다.

• 자원환경지질
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• 제2권4호
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• pp.73-90
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• 1969

The area studied is a southwestern part of Okcheon geosynclinal zone which streches diagonally across the Korean peninsula in the mid-central parts of South Korea, and is bounded by Charyeong mountain chains in the north and by Sobaek mountain chains in the south. The general trend of the zone is of NE-SW direction known as Sinian direction. Okcheon system of pre-Cambrian age occupies southwestern portion of Okcheon geosynclinal zone, and Choseon and Pyeongan systems of Cambrian to Triassic age in northeastern portion of the zone. It was defined by the writer that the former was called "Okcheon Paleogeosynclinal zone" and the latter "Okcheon Neogeosynclinal zone," although T. Kobayashi named them "Metamorphosed Okcheon zone" and "Non-metamorphosed Okcheon zone" respectively and thought that sedimentary formations in both zones were same in origin and of Paleozonic age, and C.M. Son also described that Okchon system was of post-Choseon (Ordovician) and pre-Kyeongsang (Cretaceous) in age. According to the present study two zones are separated by great fault so that the geology in both zones is not only entirely different in origin and age, but also their geolosical structures are discontinuous. Stratigraphy and structure of Okcheon system are clearly established and defined by the writer and its age is definitely pre-Cambrian. It is clarified by present study that the meta-sediments in and at vicinity of Charyeong mountain chains are correlated to Weonnam series of pre-Cambrian age which occupies and continues from northeast to southwest in and at south of Sobaek mountain chains, and both metasediments constitute basement of Okcheon system. Pyeongan, Daedong and Kyeongsang systems were deposited in few narrow intermontain basins in Okcheon paleogeosynclinal zone after it was emerged at the end of Carboniferous period. Granites of Jurassic and Cretaceous ages and volcanics of Cretaceous age are cropped out in the zone. Jurassic granite is aligned generally with the trend of Okcheon geosynclinal zone, whereas Cretaceous granite lacks of trend in distribution. Many isoclinal folds and thrust faults caused by Taebo orogeny at the end of Jurassic period are also parallel with Sinian directieon and dip steeply to northwest. Charyeong, Noryeong, Sobaek, and Deogyu mountain chains are located in areas of anticlinorium, and Kyongsang system in narrow synclinal zones. Folds in Okcheon neogeosynclinal zone are generally of N 70-80W direction but deviate to Sinian direction at the western parts of the zone. This phenomena is interpreted by the fact that the folds were originated by Songrim disturbance at the end of Triassic period and later partly modified by Taebo orogeny. Thrust faults of Taebo orogeny coentinue from Okcheon paleogeosynclinal zone into neogeosynclinal zone, forming imbricated structure as previously described. Strike-slip faults perpendicular to Sinian direction and shear faults diagonally across it by 55 degrees also prevail in neogeosynclinal zone. It is concluded from viewpoints on geology and geological structure that l)Okchon geosyncline had changed its location and affected by numerous disturbances through geologic time, and 2)mountain chains in the area such as Charyeong, Noryeong, Sobaek, and Deogyu were originated as folded mountains. Differing from others, however, Sobaek range was probably formed at the time of Songrim disturbance and modified later by Taebo orogeny. It is cut by Danyang-Jeomchon fault at the vicinity of Joryeong near Munkyeong village and does not continue to southwest beyond the fault, whereas southwestern portion of erstwhile Sobaek range continues to Taebaek rangd northeastward from Deogyusan passing through Sangju, Yecheon, and Andong. From these evidences, the writer has newly defined the erstwhile Sobaek range in such a way that Sobaek range is restricted only to northeastern portion and Deogyu range is named for the southwestern portion of previous Bobaek range.