• 대한수학회지
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• 제48권3호
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• pp.475-486
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• 2011

The paper deals with repeated low-density burst error detecting codes with a specied weight or less. Linear codes capable of detecting such errors have been studied. Further codes capable of correcting and simultaneously detecting such errors have also been dealt with. The paper obtains lower and upper bounds on the number of parity-check digits required for such codes. An example of such a code has also been provided.

• Journal of applied mathematics & informatics
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• 제9권1호
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• pp.231-238
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• 2002

In this paper, we study cyclic codes detecting a subclass of close-closed loop bursts viz. low-density close-closed loop bursts. A subclass of CT close-closed loop berets called CT low-density close-closed loop bursts is also studied.

• 대한전자공학회논문지TC
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• 제42권8호
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• pp.1-10
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• 2005

본 논문에서는 대수 이론과 관련된 일반화된 치환 행렬로부터 저밀도 부호의 명시적 구성을 고찰하였으며, 순환공식과 치환행렬에 관한 재킷 역 블록 행렬을 설계하였다. 설계 결과로부터 제안 기법은 저밀도 부호를 얻기 위한 간단하며, 고속화된 기법임을 알 수 있다. 또한, $\pi$-회전 LDPC(low density parity check) 부호와 같은 구조화 LDPC 부호 역시 저밀도 재킷 역 블록 행렬임을 증명하였다.

• 한국통신학회논문지
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• 제32권3C호
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• pp.205-215
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• 2007

This paper presents low latency and/or computation algorithms of iterative codes of turbo codes, turbo product codes and low density parity check codes for use in wireless broadband communication systems. Due to high coding complexity of iterative codes, this paper focus on lower complexity and/or latency algorithms that are easily implementable in hardware and further accelerate the decoding speed.

• 펄프종이기술
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• 제30권4호
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• pp.69-78
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• 1998

Papers loaded with 10-40% $TiO_2$ by dry weight were calendered under the various combinations of calendering conditions such as calender type, linear pressure, and roll temperature. After being calendered, light scattering coefficient, surface roughness, density, and tensile strength of the papers were measured and the results were summerized as follows: 1. To increase the light scattering coefficient of $TiO_2$-highly-loaded paper further by calendering, the calender roll pressure and temperature should be kept low. Under these conditions, the physical strength of the paper was not significantly affected. 2. At low roll temperature, soft nip calender and machine calender type showed the same relationship between paper density and its roughness. At high roll temperature, soft nip calender type gave much lower roughness than machine calender type at the same density. 3. At high roll temperature of both calenders, the density as well as the tensile strength of the TiO$_2$-loaded paper was increased significantly.

• 펄프종이기술
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• 제37권2호
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• pp.38-46
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• 2005

Experimental work was carried out in order to produce a novel grade of ink-jet paper that has both high print-out quality and price competitiveness. Usually, silica and PVOH has been used for ink-jet paper to design the coating layer that has a hydrophilic and micro-porous structure. However, poor rheological characteristics and low productivity of the silica-PVOH system make the price of the ink-jet paper high. The main focus of this study was replacing the conventional silica (coating pigment) PVOH (binder) coating system with the new PCC (coating pigment) cationic starch (binder) coating system, and optimizing thecoating technology associated with PPC-cationic starch system. In this study, ink-jet print quality of PCC-coated papers was compared with that of silica-coated paper. Two types of PCC were used: conventional type and colloid type. It turned out that PCC C, a conventional coating pigment, has not given a desirable result: it showed high dot reproduction, but it gave low optical density. In spite of low dot reproduction, the qualities of PCC A were comparable or superior to those of silica in optical density, color reproduction, and the uniformity of printing surface. It was also shown that the problems that are happened when the dosage level of cationic starch was too low were varied with ink-type used in each printer. However, in the case of low binder level, the produced image was widely spread resulting fromtoo low optical density of images, or from the lack of bonding ability to set ink into coating surface.

• 전력전자학회논문지
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• 제10권6호
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• pp.618-625
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• 2005

본 논문은 CRT 표시장치에서 고전류밀도를 구현하기 위한 전자총의 히터와 캐소드의 최적의 저전력설계와 실험을 수행하였다. CRT 표시장치에서 밝기, 고휘도, 고해상도와 대화면화를 위해서는 전자총 캐소드(cathode)의 고전류밀도가 필수적이다. 이를 위해서는 함침형 캐소드가 사용되며, 고전류밀도를 얻기 위해 히터의 동작온도를 높여야하는데 이에 비례하여 소비전력도 증가한다. 본 논문에서는 고전류밀도 캐소드 히터의 저전력 설계를 위하여 히터의 리드형태(Lead Type), 코팅(Coating)법, 발열부의 1차 및 2차 코일링의 피치와 권선수를 달리한 샘플을 제작, 시험하였다.

• 펄프종이기술
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• 제38권2호
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• pp.16-21
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• 2006

Uneven ink transfer of a print can be traced to several causes such as an incomplete contact between the paper surface and ink film, a coarse pattern of a continuous ink film after transfer, uneven absorption, etc. Uneven ink transfer was studied in this points by the Tollenaar. Uneven distributions of printed density are reflected in low ${\ulcorner}m{\lrcorner}$ values of the print. Tollenaar's smoothness coefficient ${\ulcorner}m{\lrcorner}$ value was important factor that deciding printed quality which was easily obtain by densitometry. Limiting print density $D_{\infty}$ that obtained Tollenaar's formulation working as a influence factor at the printed quality. In this study, we obtained limiting print density $D_{\infty}$ and smoothness coefficient ${\ulcorner}m{\lrcorner}$ value of domestic newspapers and foreign newspapers. And we analyzed about properties of the newspaper. The result of this study, smoothness coefficient ${\ulcorner}m{\lrcorner}$ value and limiting print density $D_{\infty}$ showed the good results in the low porosity and low roughness newspaper. Datum which obtained by this study was used as printability factor for the quality control and improvement of domestic newspaper and wished to apply as a basic data for the domestic newspaper quality.

• 대한전자공학회논문지TC
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• 제47권11호
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• pp.36-42
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• 2010

이 논문은 유클리드 기하학과 Circulant Permutation Matrices에서 병렬 구성을 기반으로 하는 Quasi-cyclic Low-density parity-check (QC-LDPC) 코드의 생성을 위한 하이브리드한 접근방식을 나타낸다. 이 방법으로 생성된 코드는 넓은 둘레(Large Girth)와 저밀도(Low Density)를 가진 규칙적인 코드로 나타내어진다. 시뮬레이션 결과는 이 코드들이 반복 복호(Iterative Decoding)를 통해 좋은 성능을 갖는것과 부호화되지 않은 시스템에서 좋은 코딩 이득을 달성하는 것을 보인다.

• Journal of the Korean Wood Science and Technology
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• 제27권4호
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• pp.57-64
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• 1999

This research was carried out to investigate the effects of density, resin and particle types on the physical and mechanical properties of the composites made from various wood particles mixed with coating paper. The experiment was designed to apply with three particles (flake, chip, and fiber) and three resin types (urea, phenol and PMDI resin). The mixed ratio of coating paper to wood particle was fixed on 50 to 50% in each board making. And also it was designed to apply for four density levels (0.6, 0.7, 0.8 and 0.9 g/$cm^3$) and four mixed formulations of coating paper to wood particle (10:90, 20:80, 30:70, and 40:60 %) to analyze clearly the effects of PMDI resin. Coating paper-wood particle composites have acceptable bending strength (MOR, MOE) though the mixed ratio of coating paper was increased, but have low internal bond strength and poor dimensional stability (WA, TS, LE). Composites with high density had higher mechanical properties but showed lower physical properties than composites with low density. In conclusion, at least up to 20% mixed ratios, coating paper-wood particle composites have acceptable physical and mechanical properties, and PMDI resin has possibility for coating paper-wood particle composite manufacture.