• 에너지공학
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• 제27권3호
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• pp.1-9
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• 2018

본 연구에서는 양면수광형 태양광 발전시스템의 바닥면 적용을 목적으로 개발된 고반사율 인조잔디를 적용하여 태양광 모듈의 발전성능 옥외실증평가를 실시하였다. 사용된 모듈은 60셀 규격의 단면수광형 모듈과 2종의 양면수광형 모듈이며, 양면수광형 모듈들은 각각 split-type과 일반 box-type의 정션박스가 부착된 모델이다. 평가결과 양면모듈의 split-type 정션박스가 일반 box-type 정션박스 대비 후면출력개선에 크게 도움이 되었고, 이는 energy yield 향상으로 이어졌다. 양면수광형 모듈은 단면모듈 대비 일반 시멘트 바닥면에서는 평균적으로 28-29%, 인조잔디 바닥면에서는 29-33% 정도의 발전량 향상 (bifacial gain)을 보였다. 인조잔디의 경우 반사율을 높힌 시편의 경우 반사율(Albedo)이 0.18로 기존의 단모 및 장모의 반사율 0.14-0.15 보다 우수한 것으로 평가되었고, 이는 bifacial gain의 기존 29-30% 수준에서 33%로의 개선을 달성하였다.

• Mycobiology
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• 제51권5호
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• pp.372-378
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• 2023

Lkh1, a LAMMER kinase homolog in the fission yeast Schizosaccharomyces pombe, acts as a negative regulator of filamentous growth and flocculation. It is also involved in the response to oxidative stress. The lkh1-deletion mutant displays slower cell growth, shorter cell size, and abnormal DNA content compared to the wild type. These phenotypes suggest that Lkh1 controls cell size and cell cycle progression. When we performed microarray analysis using the lkh1-deletion mutant, we found that only four of the up-regulated genes in the lkh1-deletion were associated with the cell cycle. Interestingly, all of these genes are regulated by the Mlu1 cell cycle box binding factor (MBF), which is a transcription complex responsible for regulating the expression of cell cycle genes during the G1/S phase. Transcription analyses of the MBF-dependent cell-cycle genes, including negative feedback regulators, confirmed the up-regulation of these genes by the deletion of lkh1. Pull-down assay confirmed the interaction between Lkh1 and Yox1, which is a negative feedback regulator of MBF. This result supports the involvement of LAMMER kinase in cell cycle regulation by modulating MBF activity. In vitro kinase assay and NetPhosK 2.0 analysis with the Yox1T40,41A mutant allele revealed that T40 and T41 residues are the phosphorylation sites mediated by Lkh1. These sites affect the G1/S cell cycle progression of fission yeast by modulating the activity of the MBF complex.

• Biotechnology and Bioprocess Engineering:BBE
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• 제10권3호
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• pp.192-197
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• 2005

The effects of macronutrients $(NO_3^-,\; NH_4^+\;and\;PO_4^{3-})$ on cell growth and triterpenoids production in Centella asiatica cell suspension cultures were analyzed using the Box­Behnken response surface model experimental design. In screening and optimization experiments, $PO_4^{3-}$ as a single factor significantly influenced cell growth where increasing the phosphate level from 0.1 to 2.4 or 2.6 mM, elevated cell growth from 3.9 to $14\~16g/L$. The optimum values predicted from the response surface model are 5.05mM $NH_4^+$, 15.0mM $NO_3^-$ and 2.6mM $PO_4^{3-}$, yielding 16.0g/L cell dry weight with $99\%$ fitness to the experimental data. While the $NH_4^+-NO_3^-$ interaction influenced cell growth positively in the optimization experiment, $NH_4^+$ and $NO_3^-$ as single factors; and interactions of $NO_3^--PO_4^{3-},\;NH_4^+-PO_4^{3-}$ and $NH_4^+-NO_3^-$ were all negative in the screening experiment. Cell growth and the final pH level were positively affected by $PO_4^{3-}$, but negatively affected by $NH_4^+\;and\;NH_4^+-PO_4^{3-}$ interactions. The different effects of factors and their interactions on cell growth and final pH are influenced by a broad or narrow range of macronutrient concentrations. The productions of triterpenoids however were lower than 4mg/g cell dry weight.

• 핵의학기술
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• 제14권2호
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• pp.177-180
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• 2010

PET 검사의 의료보험 급여화 및 연구용 수요가 증가하면서 작업종사자들의 피폭이 문제가 되고 그 문제점들을 해결하기 위해 고가의 의료장비 구입이 필요하게 되었다. 하지만 cyclotron실에서 운영하는 장비들은 수 천만원에서 수 억원을 호가하는 고가의 장비들이 많이 있어 의료기관에서 구입하기 어려운 점이 있다. 작업자가 원하는 기능만 갖춘 장비를 해당 부속품 구입이 가능하다면 적은 비용으로도 충분히 자체 제작할 수 있다. 국립암센터 핵의학과에서는 적은 비용으로 장비를 제작, 사용하고 작업자의 업무까지 개선한 두가지 의료장비를 사례 별로 소개하려고 한다. 첫 번째 사례는 방사성동위원소($^{18}F$) 분주장치로 국립암센터 핵의학과 cyclotron실에서는 의공학과와의 협력으로 시중에서 구할 수 있는 아크릴판 1개, 3-way valve 7개, tubing 등을 구하여 분주기 본체를 만들어 hot cell 내부에 설치하고, switching box를 hot cell 밖에 설치하여 외부에서 분주장치를 조절할 수 있게 제작하였다. 이 제작된 분주기 본체를 cyclotron에서 생산된 방사성동위원소 transfer line에 설치하였다. 두 번째 사례는 $^{18}F$-FDG 자동 분주기로 국립암센터 핵의학과 cyclotron실에서는 의공학과와의 협력으로 분주기의 본체가 되는 부분은 cavro pump syringe를 사용하였고, 일정량을 분주할 수 있는 프로그램은 의공학과가 자체 제작하였다. $^{18}F$-FDG 자동 분주기는 hot cell 내부에 설치하고 자동분주기에 케이블선을 사용하였으며 hot cell 밖의 PC에 연결하여 PC에서 $^{18}F$-FDG 자동 분주기를 조절할 수 있게 제작하였다. 첫 번째 사례인 방사성동위원소($^{18}F$) 분주장치는 2007년 3월부터 현재까지 국립암센터에 cyclotron실에서 사용해 본 결과 생산된 방사성동위원소를 switching box를 사용하여 간단하게 원하는 방사성의약품 합성 module로 보낼 수 있었고, collecting vial 내 transfer line을 조정하여 생산된 방사성동위원소를 여러 합성 module로 분배할 수도 있게 되었다. 두 번째 사례인 $^{18}F$-FDG 자동 분주기는 2009년 8월부터 현재까지 국립암센터에 cyclotron실에서 사용해 본 결과 원하는 vial에 방사성의약품을 분배할 수 있었다. 두 가지 사례를 통하여 국립암센터 핵의학과 cyclotron실에서 고가의 장비를 최소가격으로 자체 제작하여 비용 절감 효과를 얻을 수 있었고 작업종사자의 방사선 피폭량을 감소시켰으며 다수의 부서가 협력하여 자발적으로 공동의 문제를 해결하는 프로세스를 확립시켰다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2026-2031
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• 2007

Hydrogen is receiving much research attention as an alternative substitute for hydrocarbon fuels these days due to its cleanliness and renewability. However, hydrogen should be used with caution because of its high propensity for leak and wide flammable range. This study deals with a situation that hydrogen leaks and then forms a flammable mixture inside 1kW class residential fuel cell. The residential fuel cell was modeled as a box-shaped chamber with vent openings at the top and bottom, filled with various components such as reformer, desulfurizer, fuel cell stack and humidifier. Computational fluid dynamics (CFD) was used to simulate the diffusion, buoyant flow and accumulation of leaked hydrogen in the modeled chamber. From the simulation, the risk region vulnerable to flame was identified and the methods to minimize such hazardous region was discussed. When the vent openings are 1% of the total surface, as the quantity of hydrogen leakage increases the risk regions increases accordingly. As the vent openings of the total surface increased from 1% to 2.3%, averaged hydrogen mole fraction is under 1% in the system.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.296-296
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• 2016

ITO films doped with a small amount of high-permittivity materials not only retain the basic properties of ITO films but also improve some of their properties. We report the highly conductive and transparent (ITO:Zr) films with various substrate (RT to 300oC) temperatures on glass substrate for the HIT solar cell applications. We observed a decrease in sheet resistance from 36 to $11.8{\Omega}/{\Box}$ with the increasing substrate temperature from RT to 300oC, respectively. The ITO:Zr films showed also lowest resistivity of $1.38{\times}10-4{\Omega}.cm$ and high mobility of 42.37cm-3, respectively. The surface and grain boundaries are improved with the increase of substrate temperature as shown by SEM and AFM surface morphologies. The highly conductive and transparent ITO:Zr films were employed as front electrode in HIT solar cell and the best performance of device was found to be Voc = 710 mV, Jsc = 33.70 mA/cm2, FF = 0.742, ${\eta}=17.76%$ at the substrate temperature of $200^{\circ}C$.

• BMB Reports
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• 제44권9호
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• pp.595-600
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• 2011

Pax 6, a member of the paired box (Pax) family, has been implicated in oncogenesis. However, its therapeutic potential has been never examined in breast cancer. To explore the role of Pax6 in breast cancer development, a lentivirus based short hairpin RNA (shRNA) delivery system was used to knockdown Pax6 expression in estrogen receptor (ER)-positive (MCF-7) and ER-negative (MDA-MB-231) breast cancer cells. Effect of Pax6 silencing on breast cancer cell proliferation and tumorigenesis was analyzed. Pax6-RNAi-lentivirus infection remarkably downregulated the expression levels of Pax6 mRNA and protein in MCF-7 and MDA-MB-231 cells. Accordingly, the cell viability, DNA synthesis, and colony formation were strongly suppressed, and the tumorigenesis in xenograft nude mice was significantly inhibited. Moreover, tumor cells were arrested at G0/G1 phase after Pax6 was knocked down. Pax6 facilitates important regulatory roles in breast cancer cell proliferation and tumor progression, and could serve as a diagnostic marker for clinical investigation.

• 한국가시화정보학회지
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• 제16권2호
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• pp.23-30
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• 2018

The present study compares flow fields reconstructed by data assimilation method with different combinations of parameters. As a data assimilation method, Vortex-in-Cell-sharp (VIC#), which supplements additional constraints and multigrid approximation to Vortex-in-Cell-plus (VIC+), is used to reconstruct flow fields from scattered particle tracks. Two parameters, standard deviation of Gaussian radial basis function (RBF) and grid spacing, are mainly tested using artificial data sets which contain few particle tracks. Consequent flow fields are analyzed in terms of flow structure sizes. It is demonstrated that sizes of the flow structures are proportional to an actual scale of the standard deviation of RBF. It implies that a combination of larger grid spacing and smaller standard deviation which preserves the actual standard deviation is able to save computational resources in case of a low track density. In addition, a simple comparison using an experimental data filled with dense particle tracks is conducted.

• 식물조직배양학회지
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• 제27권6호
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• pp.423-428
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• 2000

In 1997 when cloned sheep Dolly and soon after Polly were born, it had become head-line news because in the former the nucleus that gave rise to the lamb came from cells of six-year-old adult sheep and in the latter case a foreign gene was inserted into the donor nucleus to make the cloned sheep produce human protein, factor IX, in e milk. In the last few years, once the realm of science fiction, cloned mammals especially in livestock have become almost commonplace. What the press accounts often fail to convey, however, is that behind every success lie hundreds of failures. Many of the nuclear-transferred egg cells fail to undergo normal cell divisions. Even when an embryo does successfully implant in the womb, pregnancy often ends in miscarriage. A significant fraction of the animals that are born die shortly after birth and some of those that survived have serious developmental abnormalities. Efficiency remains at less than one % out of some hundred attempts to clone an animal. These facts show that something is fundamentally wrong and enormous hurdles must be overcome before cloning becomes practical. Cloning researchers now tent to put aside their effort to create live animals in order to probe the fundamental questions on cell biology including stem cells, the questions of whether the hereditary material in the nucleus of each cell remains intact throughout development, and how transferred nucleus is reprogrammed exactly like the zygotic nucleus. Stem cells are defined as those cells which can divide to produce a daughter cell like themselves (self-renewal) as well as a daughter cell that will give rise to specific differentiated cells (cell-differentiation). Multicellular organisms are formed from a single totipotent stem cell commonly called fertilized egg or zygote. As this cell and its progeny undergo cell divisions the potency of the stem cells in each tissue and organ become gradually restricted in the order of totipotent, pluripotent, and multipotent. The differentiation potential of multipotent stem cells in each tissue has been thought to be limited to cell lineages present in the organ from which they were derived. Recent studies, however, revealed that multipotent stem cells derived from adult tissues have much wider differentiation potential than was previously thought. These cells can differentiate into developmentally unrelated cell types, such as nerve stem cell into blood cells or muscle stem cell into brain cells. Neural stem cells isolated from the adult forebrain were recently shown to be capable of repopulating the hematopoietic system and produce blood cells in irradiated condition. In plants although the term$\boxDr$ stem cell$\boxUl$is not used, some cells in the second layer of tunica at the apical meristem of shoot, some nucellar cells surrounding the embryo sac, and initial cells of adventive buds are considered to be equivalent to the totipotent stem cells of mammals. The telomere ends of linear eukaryotic chromosomes cannot be replicated because the RNA primer at the end of a completed lagging strand cannot be replaced with DNA, causing 5' end gap. A chromosome would be shortened by the length of RNA primer with every cycle of DNA replication and cell division. Essential genes located near the ends of chromosomes would inevitably be deleted by end-shortening, thereby killing the descendants of the original cells. Telomeric DNA has an unusual sequence consisting of up to 1,000 or more tandem repeat of a simple sequence. For example, chromosome of mammal including human has the repeating telomeric sequence of TTAGGG and that of higher plant is TTTAGGG. This non-genic tandem repeat prevents the death of cell despite the continued shortening of chromosome length. In contrast with the somatic cells germ line cells have the mechanism to fill-up the 5' end gap of telomere, thus maintaining the original length of chromosome. Cem line cells exhibit active enzyme telomerase which functions to maintain the stable length of telomere. Some of the cloned animals are reported prematurely getting old. It has to be ascertained whether the multipotent stem cells in the tissues of adult mammals have the original telomeres or shortened telomeres.

• 미생물학회지
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• 제54권3호
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• pp.200-207
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• 2018

높은 염분 농도에서 glycine betaine은 Bacillus subtilis 안으로 유입되어 세포 생장이 지속될 수 있게 한다. 뿐만 아니라 최근 연구 결과에 따르면 저온에서도 glycine betaine이 세포 생장을 지속시키는 것으로 알려져 있다. 저온에서 Bacillus subtilis의 생장을 저해시키는 세포 대사 활동으로는 세포막 운송과 단백질 합성을 들 수 있다. 세포막 구조와 관련하여 저온에서 세포막 운송에 영향을 주는 유전자들로는 bkdR과 des가 있고, 단백질 합성 과정에서 RNA helicase 유전자인 ydbR과 yqfR들은 저온 민감성을 보인다. 따라서 Bacillus subtilis 저온 민감성 유전자 결손 세포들에 대한 glycine betaine의 효과를 조사하여 저온에서의 glycine betaine 생리적 기능에 대해 알아보고자 하였다. 이 결과 glycine betaine의 존재 유무에 따라 야생형 Bacillus subtilis와 ydbR과 yqfR 결손 균주의 저온생장에 큰 차이를 보였다($T_d$차이 190~686 min). 반면에 bkdR이나 des 결손균주의 경우에는 glycine betaine 존재 유무에 따라 차이를 보이지 않았다. Glycine betaine의 전구체인 choline으로 대치하여도 저온에서의 생장은 같은 결과를 보였다. Glycine betaine의 영향이 세포막 구조와 관련이 있는 유전자 bkdR과 des 결손균주에 미치는 영향이 적은 것을 알아보기 위해 세포막에 영향을 주는 세제의 효과를 조사하였다. Triton X-100과 N-lauryl sarcosine 세제에 의해 bkdR 결손 균주가 야생형에 비해 더 영향 받는 것을 확인하였고 이는 bkdR 결손이 저온에서 막 구조를 변형하여 glycine betaine의 투과에 영향을 미치는 것으로 보인다.