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박재용,유진식,황승민,임민규,오영규,김용대,한석영,맹주성 한국공작기계학회 2008 한국공작기계학회 추계학술대회논문집 Vol.2008 No.-
An active micro-mixer, which is composed of an oscillating micro-stirrer in the micro-channel to provide effective mixing was optimized. The effects of molecular diffusion and disturbance by the stirrer were considered with regard to two types of mixer models: the simple straight micro-channel and micro-channel with an oscillating stirrer. Two types of mixer models were studied by analyzing mixing behaviors such as their interaction after the stirrer. The mixing was calculated by Lattice Boltzmann methods using the D2Q9 model. In this study, the time-averaged mixing index formula was used to estimate the mixing performance of time-dependent flow. The mixing indices of the two models were compared. From the results, it was found that the mixer with an oscillating stirrer was much more enhanced' and stabilized. Therefore, an approximate optimization of an active micro-mixer with an oscillating stirrer was performed using Kriging method with OLHD (Optimal Latin Hypercube Design) in order to determine the optimal design variables. The design parameters were established as the frequency, the length and the angle of the stirrer. The optimal values were obtained as 1.5754, 0.803D and ±45°, respectively. It was found that the mixing index of the optimal design increased by 83.36% compared with that of the original design.
목재펠릿과 주택용 목재펠릿보일러의 품질기준에 관한 국내외 비교연구
이승록, 한규성 충북대학교 농업과학기술연구소 2022 農業科學硏究 Vol.38 No.2
Wood pellets, a representative bioenergy source, are actively used world widely. Wood pellets made in the domestic volume were around 0.65 million tons in 2021 and the scale was generally grow- ing up, which implies that South Korea’s wood pellet processing technology has reached a significant level. To guarantee a reasonable supply of wood pellet fuels as carbon-neutral sources, quality standards for related products and combustion equipment standards must be clearly established. In line with this, the authors compared major changes in domestic wood pellet quality standards with ISO standards. South Korea's wood pellet quality standards policy has undergone various changes over a period of a decade and has been improved to an equivalent level to the internationally. In addition, it was confirmed that the ‘Clean Air Conversion Act’ to be discharged for biomass-using facilities such as wood pellets have been gradually strengthened as the times change. Also comparing domestic and foreign quality standards based on small-scale combustion equipment which is using wood pellets as fuel, the authors found that domestic standards need to make improvements to meet the EU's combustor emission gas quality stan- dard level.
황승민,박재용,임민규,오영규,한석영 한국공작기계학회 2009 한국공작기계학회 춘계학술대회논문집 Vol.2009 No.-
This paper presents a reliability-based topology optimization (RBTO) using bi-directional evolutionary structural optimization (BESO). Topology optimization is formulated as volume minimization problem with probabilistic displacement constraint. Young's modulus, external load and thickness are considered as uncertain variables. In order to compute reliability index, four methods, i.e., RIA, PMA, SLSV and ADL(adaptive-loop), are used. Reliability-based topology optimization design process is conducted to obtain optimal topology satisfying displacement and reliability index constraints with the above four methods, and then each result is compared with respect to numerical stability and computing time.
임민규,박재용,황승민,오영규,박재용,한석영 한국공작기계학회 2009 한국공작기계학회 춘계학술대회논문집 Vol.2009 No.-
The objective of this work is to integrate reliability analysis into topology optimization problems. The reliability index determines design domain and uncertainty value. The elemental sensitivity numbers are calculated from finite element analysis and then converted to the nodal sensitivity numbers in the design domain. A mesh-independency filter using nodal variables is introduced to determine the addition of elements and eliminate unnecessary structural details below a certain length scale in the design. To further enhance the convergence of the optimization process, the accuracy of elemental sensitivity numbers is improved by its historical information. Application of the RBTO model gives a different topology relative to DTO. It is found that the RBTO model yields more reliable optimal topologies than those produced by DTO.
신규승 경희대학교 산학협력기술연구원 1999 산학협력기술연구논문집 Vol.5 No.-
Period doublings of parametrically coupled logistic map are investigated. As results of this, coupling, splittings of bifurcation diagrams and intruding of quasi-periodicities into a certain class of period doublings are observed.
이승일,장규희 홍익대학교 산업디자인 연구소 2004 미술디자인 논문집 Vol.- No.9
The woodcut of flowers and birds is a field that has not been almost covered in studies of old prints. This seems related to the lack of modernistic studies on the paintings of flowers and birds (hwajohwa). During the Chosun Period, this painting genre was popular among high officials and commoners as well as in painters' circles. While having received influence from China and its neighboring countries, it is used to create unique painting styles with the change of the times. This suggests that the painting genre has played an important role in the Korean painting history-and so should not be easily ignored. Since there was much influence from Japan during the Japanese colonial period, however, those flowers-and-birds paintings were recognized to belong to a Japanese painting genre even after the restoration of Korea's independence in 1945. That would be why little attention is being paid to the painting genre today. As a result, such recognition has led to the lack of studies regarding the flowers-and-birds paintings, and in turn it has influenced a lack of understanding concerning the importance of those woodcuts, in addition to the reality that there are few remaining woodcuts of flowers and birds. Accordingly, this study is focused on the flowers-and-birds woodcut that has not been almost dealt with in the previous studies on old prints. Its purposes are to promote the understanding about the woodcut confirm its position as an old printing area and provide a new basis for the study of flowers-and-birds paintings. The woodcut of flowers and birds is a form of woodprint which is same as a pure colored style of flowers-and-birds paintings in its expression and includes all pieces of work created using wood-engraving techniques. In this study, the woodcut of flowers and birds is considered as including both of the simple flowers-and-birds paintings printed from woodblock and the ones colored in specific styles on the woodblock prints. This study focuses on the Chosun Period compared to other periods in the number of available pieces of flowers-and-birds woodcut. To examine their characteristics, it categorizes those woodblock prints into flowers-and-birds woodcut for space decoration, book, flowers-and-birds woodcut, writing paper with flowers and birds, envelopes with flowers and birds, and character paintings with flowers and birds according to the purposes for which they were used and into beast woodcut and floral woodcut according to what is the subject matter used with. Mostly, the flowers-and-birds woodcut for space decoration-in other words, produced for the purpose of decorating everyday living spaces-engraves the outlines forming its frame and the patterns of trees, flowers, birds, waves, and rocks infine lines emphasizing their characteristics, texture, and shapes and has a style colored with a brush on the engraving. The book flowers-and-birds woodcut is divided into two main types: One reveals its subject through its used subject matters, and the other focuses on documentary and decorative characteristics. When categorized as wiring paper or an envelope, most pieces of woodcut contain flowers and birds as their main subject matters. In particular, they were created as part of the way to express one's own unique personality, so there were many dilettantes who enjoyed working on them. Since most bear a engraver's signature, it is not difficult to infer when and where they were created and to find out information about their users. Shown in character paintings, flowers and birds are printed from their woodblock patterns engraved in black-colored letters. Their bold contrast of black and white makes a strong visual impression, and the rare overlaps between subject matters gives a weak sense of spatiality, but a strong sense of planarity. In the categorization based on the used subject matters, most of the floral woodcut works discovered have been made for a decorative purpose rather than with an incantatory intention, while a significant number of beast woodcut works with flowers and grass as their main subject matters seem to have come from an incantatory intention, even though they bear a decorative purpose in part. In general, the woodcut of flowers and birds is not a simple woodblock engraving print with a single color, but a piece of work colored and finished with a brush on the print. This way of creation would probably be attempted to avoid having to draw a rough sketch whenever it was produced in large quantities. This serves as a main factor that makes the woodcut distinct from the pure-colored paintings of flowers and birds. The patterns printed from the engraving give the iconographic contour accuracy and definition so that undesired expressions can be minimized. And the woodblock-printed book is planned precisely, but not created temporarily or impromptu, so the overall iconographic composition can maintain balance and stability. Therefore, the finished work could be equipped with refinement and delicacy, although there might be limits in liberal expressions. These are some of critical features shown in the woodcut of flowers and birds, which are why the woodcut works are balanced and stable in their iconographic composition. So far, this study has focused on the flowers-and-birds woodcut, which has been seldom discussed in the existing studies, reviewing its meanings and historical background as well as types and characteristics. Most of difficulties in conducting the study came from the lack of studies on the woodcut and the shortage of its remaining works. If this study leaves something to be desired, the reason is that those difficulties acted as obstacles to a comprehensive and detailed discussion.
잡초성벼의 superoxide dismutase cDNA cloning과 재배벼로의 형질전환
박상규,박종석,이승인,서석철,김병극,조윤래,서학수 한국환경농학회 2002 한국환경농학회지 Vol.21 No.2
냉해나 한발등의 환경스트레스에 대해 저항성을 유발하는 유전자를 환경스트레스에 강한 잡초성벼로부터 선발하고 이들 유전자를 재배벼에 도입하여 도입유전자 산물의 과량 발현을 통해 냉해나 한발 등에 대한 저항성이 향상된 벼를 선발하고자 하였다. 잡초성벼인 Bhutan 14Ad로부터 냉해 및 한발 저항성 유전자로 알려진 superoxide dismutase (SOD) cDNA를 분리하고자 mRNA를 분리하고 이 분리된 mRNA를 이용해 reverse transcriptase PCR방법으로 SOD cDNA를 cloning 하였다. 그 결과 2종의 SOD cDNA가 cloning되어 SOD-A, SOD-B로 명명하였다. 이들 cDNA의 염기서열을 결정한 결과 이들은 아미노산 서열 상동성이 88.4%를 나타내었으며, SOD-A는 oryza sativa 계열의 Cu/Zn SOD유전자인 GenBank accession No. L36320와 99.3%로 동일하였으며, SOD-B는 accession No. D01000과 100% 동일하였다. 이들 SOD-A와 SOD-B cDNA를 재배벼인 낙동벼에 형질전환하여 형질전환체 벼를 선발하였으며, 이들 형질전환체 벼의 냉해저항성 및 한발저항성 검정을 통해 저항성이 향상된 형질전환체 벼를 선발하고 있다. Two different cDNA clones for superoxide dismutase (SOD) were isolated from an weedy rice variety (Oryza sativa, cv. Bhutanl4Ad) and were introduced into a cultivated rice variety (Oryza sativa, cv. Nakdong) in order to develop the environmental stress-resistant rice plants. Sequence analysis of the cloned cDNAs indicated that the deduced amino acid sequence of SOD-A is 88.4% identical to that of SOD-B. Furthermore, the nucleotide sequence of SOD-A is 99.3% identical to that of a Cu/Zn SOD gene of Oryza sativa (GenBank accession No. L36320). The nucleotide sequence of SOD-B was identical to that of the previously published SOD gene (Accession No. D01000). A cultivated rice variety, Nakdong-byeo, was transformed with chimenc SOD genes containing a actin promoter of rice and pin2 terminator using a particle bombardment technique. Transformed calli were selected on an selection medium containing phosphinothricin (PPT). Transgenic rice plants were regenerated from the PPT-resistant calli. PCR analysis with genomic DNAs from transgenic plants revealed that transgenes are introduced into rice genome.