• Journal of Broadcast Engineering
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• v.27 no.2
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• pp.198-206
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• 2022

This paper proposes a method to solve problems that may occur when SPIHT(set partition in hierarchical trees) is used in a dedicated codec for compressing complex holograms with ultra-high resolution. The development of codecs for complex holograms can be largely divided into a method of creating dedicated compression methods and a method of using anchor codecs such as HEVC and JPEG2000 and adding post-processing techniques. In the case of creating a dedicated compression method, a separate conversion tool is required to analyze the spatial characteristics of complex holograms. Zero-tree-based algorithms in subband units such as EZW and SPIHT have a problem that when coding for high-resolution images, intact subband information is not properly transmitted during bitstream control. This paper proposes a method of dividing wavelet subbands to solve such a problem. By compressing each divided subbands, information throughout the subbands is kept uniform. The proposed method showed better restoration results than PSNR compared to the existing method.

• Journal of the Korean Wood Science and Technology
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• v.31 no.2
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• pp.38-44
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• 2003

This study was carried out to evaluate the feasibility of using HDF as surface panels as well as core materials for flush door manufacturing. Six core constructions were developed and applied to manufacture door specimens and conventional skin door specimen was also manufactured for comparison. Door specimens were tested under changing interior environmental condition for 3~4 months during winter and summer seasons. During the test period, deformation of doors were measured weekly, and temperature and relative humidity of testing area were also recorded. From this study, it was concluded that HDF can be used to manufacture quality flush doors and core construction developed in this study showed good quality compared to conventional skin door. Deformation of doors increased as temperature and relative humidity of the surrounding environment increased. Flush doors generally showed less deformation than skin doors, and evaluated to be stable and good quality when compared to skin door.

• Composites Research
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• v.20 no.6
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• pp.8-14
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• 2007

Debonding failure characteristics of the composite skin-stiffener specimens were experimentally investigated. The influences of bonding methods, types of stiffener shape and various secondary bonding parameters were evaluated. Present test results combined with the previous test results[1] showed that the failure displacement of the skin-stiffener specimens well evaluates the skin-stiffener debonding failure strength of the composite stiffened panels. The specimens with an open type stiffener had lower bending stiffness and larger failure displacement than those with a closed type stiffener. Secondary bonding and co-curing with adhesive had better failure strength than co-curing without adhesive film. Secondary bonded specimens failed by adhesive failure and co-cured specimens failed by delamination failure. As the bondline thickness was thinner, the skin-stiffener specimens had higher failure strength. The fillets had no influence on failure strength of the specimens. The influence of the surface roughness was shown according to types of stiffener shape.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3A
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• pp.457-464
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• 2006

Fiber-reinforced composite materials due to their high specific strength, high stiffness and light weight are becoming increasingly used in many engineering industry, especially in the aerospace, marin and civil, etc. In this paper, the buckling load and mode shapes of composite laminates with elliptical cross-section including transverse shear deformations are analyzed. For solving this problems, a versatile flat shell element has been developed by combining a membrane element with drilling degree-of-freedom and a plate bending element. Also, an improved shell element has been established by the combined use of the addition of enhanced assumed strain and the substitute shear strain fields. The combined influence of shell geometry and elliptical cross-sectional parameter, fiber angle, and lay-up on the buckling loads of elliptical cylinder is examined. The critical buckling loads and mode shapes analyzed here may serve as a benchmark for future investigations.

• Applied Chemistry for Engineering
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• v.23 no.4
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• pp.372-376
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• 2012

Carbon nanotubes (CNT) are considered as one of ideal nano-fillers in the field of composites with their excellent electrical, mechanical, and thermal properties. Therefore CNT composites are increasingly used in fabricating conductive materials, structural materials with high strength and low weight, and multifunctional materials. The main problem of the CNT composites is difficulty in the dispersion of CNT in the polymer matrix. In this study multi-walled carbon nanotubes (MWNT) were pretreated by the physical process utilizing a wrapping method. After the pretreatment polymer/MWNT nanocomposites were prepared by melt processing. The effect of functionalization MWNT by wrapping with styrene acrylonitrile (SAN) on the mechanical and electrical properties of acrylonitrile butadiene styrene resin (ABS)/MWNT composites was studied by comparing the properties of ABS mixed with the neat MWNT. Electrical and mechanical properties of ABS/MWNT nanocomposites were studied as a function of the functionalization and content of MWNT. The tensile strength of the ABS/MWNT nanocomposites increased, but the impact strength decreased. The polymer wrapping in ABS system has little effect on the improvement of electrical properties.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.4
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• pp.409-417
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• 2014

Since the oil price has been significantly jumped for recent some years, the diesel engine of the merchant ship has been mainly used the heavy oil of low quality. Thus, it has been often exposed to severely corrosive environment more and more because temperature of the exhaust gas in a combustion chamber is getting higher and higher with increasing of using the heavy oil of low quality. As a result, wear and corrosion of most parts surrounded with combustion chamber is more serious compared to the other parts of the engine. Therefore, an optimum weldment for these parts is very important to prolong their lifetime in a economical point of view. In this study, four types of filler metals such as Inconel 625, 718, 1.25Cr-0.5Mo and 0.5Mo were welded with SMAW and GTAW methods in the forged steel which would be generally used with piston crown material. And the corrosion properties of weld metal, heat affected zone and base metal were investigated using electrochemical methods such as measurement of corrosion potential, anodic polarization curves, cyclic voltammogram and impedance etc. in 35% H2SO4 solution. The weld metal and base metal exhibited the best and worst corrosion resistance in all cases of filler metals. In particular, the weld metal welded with filler metals of Inconel 718 revealed the best corrosion resistance among the filler metals, and Inconel 625 followed the Inconel 718. Hardness relatively indicated higher value in the weld metal compared to the base metal. Furthermore, Inconel 625 and 718 indicated higher values of hardness compared to 1.25cr-0.5Mo and 0,5Mo filler metals in the weld metal.

• 건축구조
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• v.17 no.3
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• pp.41-47
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• 2010

현대산업사회에서는 혁신적인 디자인, 초대형, 장스팬 등 구조엔지니어링이 필요한 다양한 건축물들이 시공되고 있으며, 포스트텐션 공법은 이러한 기술적 요구를 수용하는데 있어 좋은 해결방법의 하나로 적용이 늘어나고 있는 공법이다. 이에 본지에서는 지난호(3월)의 "포스트텐션 공법의 소개"에 이어 경제성을 비교분석하여 포스트텐션 공법적용의 장점을 소개하고자 한다. 경제성 비교에서는 공법에 사용되는 인건비와 재료비 등의 직접비용을 제외한 공기, 유지관리, 해제 등 다양한 요소들이 고려되며, 각 건물의 특성에 따라 달라지므로 명확한 경제성 분석을 하기는 힘들다. 그러므로 본 기사에서는 포스트텐션 공법의 경제성에 영향을 주는 요소들을 분석하고, 각 구조 공법의 상대비용을 비교하여 포스트텐션 공법 적용을 위한 가이드라인을 제공하고자 한다.

• Electrical & Electronic Materials
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• v.3 no.1
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• pp.36-44
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• 1990

본 연구는 34wt%(5Ce-Didymium)-Fe-1wt%B 합금의 분말입도, 성형압력 및 소결온도 에 따른 자기적 성질에 관하여 연구하였다. 그리고 각각의 자기적 성질에 영향을 주는 인자를 알아내기 위하여 밀도측정, 미세조직 및 자구를 관찰하였다. 미세조직은 금속현미경을 이용하여 관찰하였으며 자구는 Bitter법으로 관찰하였다. 결과는 아래와 같다. (1)분말의 입도와 결정립 크기가 작아질수록 경질자기 특성은 증가하였으며 소결온도가 증가할수록 경질자기 특성도 증가하였다. 그러자 압력은 1000kg/$cm^{2}$일때 가장 좋은 경질자기 특성이 얻어졌다. (2)결정립이 클수록 자구의 구조는 복잡했으며 미세한 결정립일수록 큰 결정립에 비해 큰 보자력을 갖는다. 포화된 후에는 거의 모든 결정립이 단자구였으며 열적으로 탈자되었을 경우에는 모두가 multi-domain였다. (3)가장 우수한 경질자기 특성은 3-5.mu.m의 분말을 사용하여 1080.deg.C에서 소결한 후 590.deg.C에서 열처리한 시편에서 얻어졌으며 (BH)$_{max}$는 214.6kJ.m$_{-3}$이다.

• Journal of the Korean Society of Tobacco Science
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• v.30 no.1
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• pp.66-76
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• 2008

생물학적으로 활성이 있는 물질들의 생체 내 대사를 이해하고 인체 독성 및 질환의 발현을 예측할 수 있는 가장 좋은 시험방법은 생체 내 독성 평가법이다. 담배연기의 생체 내 독성 평가법에는 14일 흡입독성시험, 90일 흡입독성 시험 및 피부도말 종양발생 시험 등이 있다. 90일 흡입독성 시험은 담배의 일반적인 독성 정보를 제공한다. 생체 내 독성평가는 담배 첨가물, 재료품 또는 제품 설계를 변경할 경우 담배연기 독성이 증가 또는 감소되었는 지를 평가할 수 있으며 이 결과는 제품보증에 활용될 수 있다. 캐나다의 독성평가자료 제출 및 EU 등의 담배첨가물에 대한 규제는 향 후 이런 생체 내 시험에 대한 지속적이고도 구체적인 요구를 할 것으로 사료된다.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2001.11a
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• pp.216-217
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• 2001

인류문명과 같이 시작한 천연염색은 생산량의 한정 염색물의 견뢰도 불량, 염색시 얼룩생성의 용이 등의 문제점으로 인해 화학염료가 발명되면서 점차 쇠퇴되었다. 그러나 천연염료로 염색한 염색물은 합성염료로 염색한 염색물에 비하여 그 색상이 자여스럽고 우아하며, 염색재료 대부분 한약재인 것이 많아 약리 효과를 갖는것이 많고, 최근 대두되고 있는 공해문제 해소에도 많은 장점을 가지고 있어 이에 대한관심이 점차 높아지고 있다. 일반적으로 동물성 섬유(견, 모)는 단백질 섬유로서 매여제를 쓰지 않고도 염색이 잘되는 편이지만, 식물성 섬유인 면, 마 등은 섬유소이므로 색소의 흡착이 불량하여 염색보조제로 전처리 한 다음, 주매염제를 처리해야 좋은 결과를 얻을 수 있다ㅣ. 식물성 섬유의 일종인 인피섬유로 이루어진 한지의 천연염색 효과 향상을 위해 염색 보조제로 전처리 한 것과 무처리 한지의 염색특성을 구명하기 위해 본 실험을 실시하였다.