• Advances in aircraft and spacecraft science
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• 제10권3호
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• pp.223-243
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• 2023

There is a burgeoning demand for minimizing the mass of satellites because of its direct impact on reducing launch-to-orbit cost. This must be done without compromising the structure's efficiency. The present paper introduces a relatively low-cost and easily implementable approach for optimizing structural mass to a maximum natural frequency. The natural frequencies of the satellite are of utmost pertinence to the application requirements, as the sensitive electronic instrumentation and onboard computers should not be affected by the vibrations of the satellite structure. This methodology is applied to a realistic model of Al-Azhar University micro-satellite in partnership with the Egyptian Space Agency. The procedure used in structural design can be summarized in two steps. The first step is to select the most favorable primary structural configuration among several different candidate variants. The nominated variant is selected as the one scoring maximum relative dynamic stiffness. The second step is to use perforation patterns reduce the overall mass of structural elements in the selected variant without changing the weight. The results of the presented procedure demonstrate that the mass reduction percentage was found to be 39% when compared to the unperforated configuration that had the same plate thickness. The findings of this study challenge the commonly accepted notion that isogrid perforations are the most effective means of achieving the goal of reducing mass while maintaining stiffness. Rather, the study highlights the potential benefits of exploring a wider range of perforation unit cells during the design process. The study revealed that rectangular perforation patterns had the lowest efficiency in terms of modal stiffness, while triangular patterns resulted in the highest efficiency. These results suggest that there may be significant gains to be made by considering a broader range of perforation shapes and configurations in the design of lightweight structures.

• 한국항공우주학회지
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• 제37권10호
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• pp.1017-1026
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• 2009

우주비행체의 주 전력원인 태양전지 시스템은 태양광을 직접 바라본 상태에서 운용되어, 우주의 가혹한 열적/기계적 환경에 직접 노출되므로, 제작/시험 중 발생될 수 있는 미세한 균열, 정전기 및 열 충격 등이 궤도 운용 중 태양전지 시스템의 기능상실로 이어질 가능성을 갖는다. 또한 태양전지 시스템의 전력생성 기본 유닛인 태양전지에 발생된 미세한 균열 또는 열 충격에 따른 태양전지의 내부 파손의 발견을 위해서는 고가의 장비와 복잡한 시험 절차, 그리고 많은 시간을 필요로 하게 된다. 따라서 태양전지 시스템 기능의 건전성을 쉽고, 빠르게 확인하기 위해, 정성적인 태양전지 기능 건전성 평가 방법이 요구된다. 본 논문에서는 요즘 우주비행체에서 가장 많이 사용되는 갈륨-비소 계열의 다접합 태양전지가 갖는 전계발광현상을 이용해 복잡한 반도체 구조를 가지는 태양전지의 기능 건전성을 보다 간단하고 저비용으로 그리고 빠르게 평가하는 방법에 대한 이론적, 기술적 근거를 설명하였다. 또한 이를 실제의 우주용 태양전지 시스템에 적용하기 위한 기술적 사항들과 적용 제한 조건들에 대하여 기술하였다.

• 한국수정란이식학회지
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• 제27권2호
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• pp.113-119
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• 2012

Epigenetic modification including genome-wide DNA demethylation is essential for normal embryonic development. Insufficient demethylation of somatic cell genome may cause various anomalies and prenatal loss in the development of nuclear transfer embryos. Hence, the source of nuclear donor often affects later development of nuclear transfer (NT) embryos. In this study, appropriateness of porcine embryonic germ (EG) cells as karyoplasts for NT with respect to epigenetic modification was investigated. These cells follow methylation status of primordial germ cells from which they originated, so that they may contain less methylated genome than somatic cells. This may be advantageous to the development of NT embryos commonly known to be highly methylated. The rates of blastocyst development were similar among embryos from EG cell nuclear transfer (EGCNT), somatic cell nuclear transfer (SCNT), and intracytoplasmic sperm injection (ICSI) (16/62, 25.8% vs. 56/274, 20.4% vs. 16/74, 21.6%). Genomic DNA samples from EG cells (n=3), fetal fibroblasts (n=4) and blastocysts from EGCNT (n=8), SCNT (n=14) and ICSI (n=6) were isolated and treated with sodium bisulfite. The satellite region (GenBank Z75640) that involves nine selected CpG sites was amplified by PCR, and the rates of DNA methylation in each site were measured by pyrosequencing technique. The average methylation degrees of CpG sites in EG cells, fetal fibroblasts and blastocysts from EGCNT, SCNT and ICSI were 17.9, 37.7, 4.1, 9.8 and 8.9%, respectively. The genome of porcine EG cells were less methylated than that of somatic cells (p<0.05), and DNA demethylation occurred in embryos from both EGCNT (p<0.05) and SCNT (p<0.01). Interestingly, the degree of DNA methylation in EGCNT embryos was approximately one half of SCNT (p<0.01) and ICSI (p<0.05) embryos, while SCNT and ICSI embryos contained demethylated genome with similar degrees. The present study demonstrates that porcine EG cell nuclear transfer resulted in hypomethylation of DNA in cloned embryos yet leading normal preimplantation development. Further studies are needed to investigate whether such modification affects long-term survival of cloned embryos.

• Journal of Yeungnam Medical Science
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• 제16권1호
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• pp.108-113
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• 1999

저자들은 최근 58세 여자의 좌측 대퇴하부에 발생한 투명세포육종 1예를 경험하였기에 문헌고찰과 함께 보고한다.

• Journal of Animal Science and Technology
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• 제54권3호
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• pp.219-226
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• 2012

Gender specificity in muscle growth and development is well known. Genesis of muscle is dependent on proliferation and differentiation potential of resident myogenic satellite cells (MSCs) present in muscle fibers. Multipotential capacity of forming myocyte, osteocyte, and adipocyte like cell makes MSCs a unique stem cell. To understand the molecular mechanism involved in determination of muscle quality due to difference in hormone concentration of different gender of animals, MSCs were isolated from bovine skeletal muscle and cultured in male, female, and castrated serum supplemented media. DNA microarray used consisted of 24,000 spots with 70 mer oligo in each spot. A total of 88 genes were up-regulated and 551 genes were down-regulated by more than two fold. Among up-regulated gene, 33, 34, and 21 genes were found up-regulated in cells grown in male, female, and castrated serum, respectively. Interestingly, male serum showed 4, female 11 and castrated male showed 4 genes expressed highly in each gender. Further study on the highly up-regulated gene may unfold the mystery of gender specificity found in muscle development. Also, the identification of differentially expressed genes in gender-specific serum will add information on infrastructure of bovine genome research.

• 한국동물생명공학회지
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• 제36권4호
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• pp.314-322
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• 2021

Paired box protein, PAX7, is a key molecule for the specification, maintenance and skeletal muscle regeneration of muscle satellite cells. In this study, we identified and characterized the cDNA and amino acid sequences of PAX7 from black sea bream (Acanthopagrus schlegelii) via molecular cloning and sequence analysis. A. schlegelii PAX7 cDNA was comprised of 1,524 bp encoding 507 amino acids and multiple sequence alignment analysis of the translated amino acids showed that it contained three domains including paired DNA-binding domain, homeobox domain and OAR domain which were well conserved across various animal species investigated. Pairwise Sequence Alignment indicated that A. schlegelii PAX7 had the same amino acid sequences with that of yellowfin seabream (A. latus) and 99.8% identity and similarity with that of gilt-head bream (Sparus aurata). Molecular phylogenetic analysis confirmed that A. schlegelii PAX7 formed a monophyletic group with those of teleost and most closely related with those of the fish that belong to Sparidae family including A. latus and S. aurata. In the investigation of its tissue specific mRNA expression, the expression was specifically identified in skeletal muscle tissue and a weak expression was also shown in gonad tissue. The cultured cells derived from skeletal muscle tissues expressed PAX7 mRNA at early passage but the expression was not observed after several times of subculture.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2017년도 추계학술대회
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• pp.157-158
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• 2017

본 논문에서는 고출력 리튬이온 18650 셀(cell) 200개를 사용하여 고출력 어플리케이션의 운용 범위와 동적 특성을 적용한 스크리닝 방법을 제안하였다. 전기적 특성 실험 기반 배터리 용량과 OCV(open circuit voltage)의 요소를 고려한 16개의 내부 파라미터를 추출하고 표준편차 기반 가중치를 선정하였다. 선정된 가중치를 각각의 요소에 적용하여 단위 셀의 대표 값을 결정하고 셀 스크리닝을 수행하였다. 기존의 스크리닝 기법과 제안된 스크리닝 기법을 200개의 단위 셀에 적용하여 두 기법의 차이를 비교 분석하였다.

• 한국수산과학회지
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• 제40권3호
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• pp.128-132
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• 2007

We identified a microsatellite marker, Poli121TUF, which appears to be significantly linked (P<0.001) with a lymphocystis disease virus (LCDV)-resistance gene in the olive flounder, Paralichthys olivaceus. The olive flounder is an economically important food fish, that is widely cultured in Korea, Japan, and China. Lymphocystis disease has spread in these countries and has seriously reduced the economic value of the fish. LCDV causes lymphocystis cells (LC) to form on the body surface, fins, gills, mouth, and intestine. Fish with LC lose commercial value due to their deformed appearance. The identified micro satellite marker can be used as a candidate locus for marker-assisted selection (MAS) in order to enhance the efficiency of selection for LCDV resistance in the olive flounder.

• Journal of Genetic Medicine
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• 제1권1호
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• pp.11-16
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• 1997

A nine month old male child presenting degenerating right ulna (massive osteolysis) has been followed up for two years. The bone completely disappeared due to abscesses on the right forearm and without orthopedic or haematological complications. Repeated lymphocyte cultures showed somatic pairing (mostly chromosome pair 5), end to end association involving chromosome 14, 21, 21 and 16, and satellite enlargement in a high proportion of cells with an otherwise normal 46,XY karyotype. These observations are compared with 13 other types of orthopaedic patients, and we opine that cumulative picture of chromosomal aberrations appears to correspond with the present rare anomaly "Mono Ostolic Osteolysis" involving right ulna. None of the controls or any other orthopaedic anomaly studied hereunder exhibits this chromosomal picture.

• 천문학회보
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• 제35권1호
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• pp.28.1-28.1
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• 2010

Ground-based solar observations have several merits such as wider field of view and higher time cadence than those of satellite observations. The Domeless Solar Telescope of Hida Observatory is designed to acquire solar surface images at the highest possible spatial resolution using two types of spectrographs: a vertical spectrograph with the highest wavelength resolution in the world, and a horizontal spectrograph that can take images of the sun in multi-wavelength over the entire visible solar spectrum. The temporal variation of fine features such as chromospheric grains in the supergranulation cells and facular points in the network region has been obtained using DST Ca II K lines compared with Hinode Ca II H lines. This analysis is expected to provide a fundamental tool for research of diverse phenomena on the solar surface.