• Structural Engineering and Mechanics
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• 제89권1호
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• pp.1-11
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• 2024

This article introduces a novel analytical model for examining the impact of porosity on shear correction factors (SCFs) in functionally graded porous beams (FGPB). The study employs uneven and logarithmic-uneven modified porosity-dependent power-law functions, which are distributed throughout the thickness of the FGP beams. Additionally, a modified exponential-power law function is used to estimate the effective mechanical properties of functionally graded porous beams. The correction factor plays a crucial role in this analysis as it appears as a coefficient in the expression for the transverse shear stress resultant. It compensatesfor the assumption that the shear strain is uniform across the depth of the cross-section. By applying the energy equivalence principle, a general expression for static SCFs in FGPBs is derived. The resulting expression aligns with the findings obtained from Reissner's analysis, particularly when transitioning from the two-dimensional case (plate) to the one-dimensional case (beam). The article presents a convenient algebraic form of the solution and provides new case studies to demonstrate the practicality of the proposed formulation. Numerical results are also presented to illustrate the influence of porosity distribution on SCFs for different types of FGPBs. Furthermore, the article validates the numerical consistency of the mechanical property changesin FG beams without porosity and the SCF by comparing them with available results.

• 한국초지조사료학회지
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• 제26권4호
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• pp.193-198
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• 2006

유용유전자 도입을 통한 신품종 오차드그래스를 개발할 목적으로 Agrobacterium을 이용한 효율적인 형질전환 체계를 확립하였다. 오차드그래스 성숙종자 유래의 캘러스를 standard binary vector인 pIG121Hm을 가지고 있는 Agrobacterium을 이용하여 감염시킨 후 공동배양하여 형질전환 시켰다. Agrobacterium을 이용한 형질전환에 있어서 중요한 인자로 작용하는 AS 첨가와 오차드그래스 품종에 따른 캘러스의 형질전환 효율의 차이를 GUS 유전자의 발현정도로 조사하였다. 'Roughricer' 품종의 형질전환 효율이 가장 우수하였으며, Agrobacterium 감염시에 접종배지와 공동배양배지에 $200{\mu}M$의 AS를 첨가해 주었을 때 형질전환 효율이 증가하는 것으로 나타났다. 50 mg/L의 hygromycin이 첨가된 선발배지에서 살아남은 캘러스로부터 정상적인 식물체가 재분화 되었으며 이들 형질 전환체에 대한 GUS 염색과 PCR 분석을 실시한 결과 발현벡터의 T-DNA 영역이 형질전환식물체의 genome에 성공적으로 도입되었음을 확인할 수 있었다. 본 연구를 통하여 확립된 효율적인 형질전환시스템은 환경스트레스 내성 신품종 오차드그래스의 개발에 유용하게 이용될 수 있을 것이다.

• 과학교육연구지
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• 제36권1호
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• pp.106-119
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• 2012

이 연구에서는 5개 대학부설 과학영재교육원의 중등 화학반 교재를 고안한 분석틀에 의해 비교 분석하였고, N대학교 부설 과학영재교육원 학생들의 설문 조사를 통하여 영재 교육 프로그램의 내용과 운영에 대한 학생들의 인식을 조사하였다. 이를 토대로 올바른 영재교육에 대한 시사점을 찾고자 하였다. 고안한 분석틀은 교재 내용, 활동의 유형, 활동의 수준, 실험 활동의 개방도, 창의적 사고력 유형 등 6가지 범주에 따른 준거로 구성되었다. 교재분석결과 대체로 단원 내용이 적절하게 배분되어 이루어졌지만 첨단과학이나 융합과학 등의 내용이 부족했다. 활동의 유형은 대부분이 강의나 실험활동으로 다양한 활동들로 이루어진 프로그램이 개발되어야 할 것이다. 또한 지적 선행 학습이나 과학적 사고력 증진을 위한 학습활동의 비율이 높았다. 활동의 수준 분석 결과 창의적 활동이 매우 부족했고 실험활동의 개방도에서는 2수준 이상의 활동 비율이 낮았다. 그리고 창의적 사고력 유형분석에서는 확산적 사고력과 연관적 사고력을 촉진하는 활동이 부족함을 보였다. 진정한 영재교육이 이루어지기 위해서는 과학영재교육 프로그램 개발이 요구된다. 리커트 방식의 설문지와 면담을 통해 분석한 프로그램 내용에 대한 응답은 전반적으로 N대학교 부설 영재교육원 프로그램의 내용과 자신의 능력향상, 운영방식 등에 매우 긍정적인 반응을 보였다.

• Genomics & Informatics
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• 제4권1호
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• pp.1-10
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• 2006

Epigenetic alterations are common features of human solid tumors, though global DNA methylation has been difficult to assess. Restriction Landmark Genomic Scanning (RLGS) is one of technology to examine epigenetic alterations at several thousand Notl sites of promoter regions in tumor genome. To assess sequence information for Notl sequences in RLGS gel, we cloned 1,161 unique Notl-linked clones, compromising about 60% of the spots in the soluble region of RLGS profile, and performed BLAT searches on the UCSC genome server, May 2004 Freeze. 1,023 (88%) unique sequences were matched to the CpG islands of human genome showing a large bias of RLGS toward identifying potential genes or CpG islands. The cloned Notl-loci had a high frequency (71%) of occurrence within CpG islands near the 5' ends of known genes rather than within CpG islands near the 3' ends or intragenic regions, making RLGS a potent tool for the identification of gene-associated methylation events. By mixing RLGS gels with all Notl-linked clones, we addressed 151 Notl sequences onto a standard RLGS gel and compared them with previous reports from several types of tumors. We hope our sequence information will be useful to identify novel epigenetic targets in any types of tumor genome.

• Asian Pacific Journal of Cancer Prevention
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• 제15권9호
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• pp.4039-4044
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• 2014

Background: The aim of this study was to investigate the anti-cancer effects and mechanisms of immunochemotherapy of 5-fluorouracil (5-FU) and interleukin-2 (IL-2) on non-small cell lung cancer (NSCLC) A549 cells. Materials and Methods: In order to detect whether 5-FU+IL-2 could effectively inhibit tumor growth in vivo, we established an A549-bearing nude mouse model. The cytotoxicity of natural killer (NK) cells was evaluated using a standard chromium release assay. To evaluate the relevance of NK cells in 5-FU+IL-2-mediated tumor inhibitory effects, we depleted NK cells in A549-bearing mice by injecting anti-asialo-GM-1 antibodies. Effects of 5-FU+IL-2 on the expression and promoter activity of NKG2D ligands (MICA/MICB) in A549 cells in vitro were also assessed. Results: In A549-bearing nude mice, combination therapy significantly inhibited tumor growth in comparison with monotherapy with 5-FU or IL-2 and enhanced the recognition and lysis of tumor cells by NK cells. Further study of mechanisms showed that NK cells played a vital role in the anticancer immune response of 5-FU+IL-2 immunochemotherapy. In addition, the combination therapy synergistically stimulated the expression and promoter activity of MICA/MICB. Conclusions: 5-FU and IL-2 immunochemotherapy significantly inhibited tumor growth and activated NK cytotoxicity in vivo, and these effects were partly impaired after depleting NK cells in tumor-bearing mice. Combination treatment of 5-FU and IL-2 upregulated the expression and the promoter activity of MICA/MICB in A549 cells, which enhanced the recognition of A549 cells by NK cells. All of the data indicated that immunochemotherapy of 5-FU and IL-2 may provide a new treatment option for patients with lung cancer.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2009년도 추계학술발표대회
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• pp.12.1-12.1
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• 2009

Nano-hydroxyapatite (N-HAp)has shown the pivotal role in producing bone-regenerative materials since it has similarity to natural bone minerals in terms of size, morphology, and the composition. Currently, the combination of biopolymers and N-HAp is recognizedas an attractive approach in generating hybrid scaffolds for bone tissueengineering. Surface engineering is an important issue since it determines whether cells can effectively adhere and proliferate on porous scaffolds. We aim to develop a synthetic approach to porous 3D scaffolds by immobilizing N-HAp on pore surfaces. The discrete nano-level anchoring of N-HAp on the scaffold pore surface is achieved using surface-repellent stable colloidal N-HAp with surface phosphate functionality. This rational surface engineering enables surface-anchored N-HAp to express its overall intrinsic bioactivity,since N-HAp is not phase-mixed with the polymers. The porous polymer scaffolds with surface-immobilized N-HAp provide more favorable environments thanconventional bulk phase-mixed polymer/N-HAp scaffolds in terms of cellular interaction and growth. In vitro biological evaluation using alkalinephosphatase activity assay supports that immobilized N-HAp on pore surfaces of polymer scaffolds contributed to the more enhanced in vitro osteogenicpotential. Besides, the scaffolds with surface-exposed N-HAp provide favorable environments for enhanced in vivo bone tissue growth, estimated by characteristic biomarkers of bone formation such as collagen. The results suggest that newly developed hybrid scaffolds with surface-immobilized N-HApmay serve as a useful 3D substrate with pore surfaces featuring excellent bonetissue-regenerative properties. Acknowledgement. This research was supported by a grant (code #: 2009K000430) from 'Center for Nanostructured Materials Technology' under '21st Century Frontier R&D Programs' of the Ministry of Education, Science and Technology, Korea.

• 한국수자원학회논문집
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• 제40권10호
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• pp.783-791
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• 2007

본 연구에서는 과학기술부의 21C 프론티어 사업 중 하나인 수자원의 지속적 확보기술개발사업단에서 연구 개발 중인 수자원 확보기술을 대상으로 기술평가 모형을 구축하였다. 이는 개발기술의 가치평가를 통하여 R&D가 효율적으로 사용되고 개발된 기술이 실용화 단계까지 성공적으로 갈 수 있도록 기여함에 있다. 수자원 확보기술의 성격을 반영할 수 있도록 정량적 평가뿐만 아니라 정성적 평가가 모두 가능한 2개의 계층으로 이루어진 평가틀이 구축되었다. 4개의 평가기준과 26개의 평가속성들의 가중치는 계층분석과정(AHP, Analytic Hierarchy Process)기법을 이용하여 산정되었다. 구축된 기술평가틀을 2개의 수자원 확보기술 가치평가에 적용시켜 평가틀이 어떻게 사용될 수 있는지 또한 제시하였다.

• 대한간호학회지
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• 제41권4호
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• pp.500-509
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• 2011

Purpose: Time-driven activity-based costing was applied to analyze the nursing activity cost and efficiency of a medical unit. Methods: Data were collected at a medical unit of a general hospital. Nursing activities were measured using a nursing activities inventory and classified as 6 domains using Easley-Storfjell Instrument. Descriptive statistics were used to identify general characteristics of the unit, nursing activities and activity time, and stochastic frontier model was adopted to estimate true activity time. Results: The average efficiency of the medical unit using theoretical resource capacity was 77%, however the efficiency using practical resource capacity was 96%. According to these results, the portion of non-added value time was estimated 23% and 4% each. The sums of total nursing activity costs were estimated 109,860,977 won in traditional activity-based costing and 84,427,126 won in time-driven activity-based costing. The difference in the two cost calculating methods was 25,433,851 won. Conclusion: These results indicate that the time-driven activity-based costing provides useful and more realistic information about the efficiency of unit operation compared to traditional activity-based costing. So time-driven activity-based costing is recommended as a performance evaluation framework for nursing departments based on cost management.

• Asian-Australasian Journal of Animal Sciences
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• 제20권5호
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• pp.653-660
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• 2007

In this study, we have investigated sequence variants in the PRNP gene of 20 individuals belonging to the Korean cattle, and have analyzed and compared genetic features between varieties of other cattle breeds. Of the 73 sequence variants identified in Korean cattle, 27 were identified for the first time in this study, whereas 46 of these polymorphisms had previously been isolated. We discovered a 2.6 kb SNP hot spot region localized on the putative promoter region of the PRNP gene. Furthermore, the copy numbers of the octapeptide repeat (24 bp indel) which is detected on the coding sequence (CDS) of the PRNP exhibited a completely homozygous 6/6 genotype which is dominant in other cattle breeds. We also characterized a new 19 bp/10 bp allele located on the putative promoter region of the PRNP gene, which represented 0.71 in allele frequency. To the best of our knowledge, this report is the first to address polymorphisms of the PRNP gene structure in Korean cattle in which BSE has yet to be discovered. Therefore, our findings may prove useful with regard to our current understanding of allelic diversity in bovine species, and may also provide new insights into the genetic factors associated with susceptibility or resistance to BSE.

• Asian Pacific Journal of Cancer Prevention
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• 제15권22호
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• pp.9667-9672
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• 2014

Background: Pancreatic adenocarcinoma is a malignant gastrointestinal cancer with significant morbidity and mortality. Despite severe side effects of chemotherapy, the use of immunotherapy combined with chemotherapy has emerged as a common clinical treatment. In this study, we investigated the efficacy of the combined doxorubicin and interferon-${\alpha}$ (IFN-${\alpha}$) therapy on murine pancreatic cancer Panc02 cells in vitro and in vivo and underlying mechanisms. Materials and Methods: A Panc02-bearing mouse model was established to determine whether doxorubicin and interferon-${\alpha}$ (IFN-${\alpha}$) could effectively inhibit tumor growth in vivo. Cytotoxicity of natural killer (NK) cells and cytotoxic T lymphocytes (CTLs) was evaluated using a standard LDH release assay. To evaluate the relevance of NK cells and CD8 T cells to the combination therapy-mediated anti-tumor effects, they were depleted in tumor-bearing mice by injecting anti-asialo-GM-1 antibodies or anti-CD8 antibodies, respectively. Finally, the influence of doxorubicin+interferon-${\alpha}$ (IFN-${\alpha}$) on the ligands of NK and T cells was assessed by flow cytometry. Results: The combination therapy group demonstrated a significant inhibition of growth of Panc02 in vivo, resulting from activated cytotoxicity of NK cells and CTLs. Depleting CD8 T cells or NK cells reduced the anticancer effects mediated by immunochemotherapy. Furthermore, the doxorubicin+IFN-a treatment increased the expression of major histocompatibility complex class I (MHC I) and NKG2D ligands on Panc02 cells, suggesting that the combined therapy may be a potential strategy for enhancing immunogenicity of tumors. All these data indicate that the combination therapy using doxorubicin and interferon-${\alpha}$ (IFN-${\alpha}$) may be a potential strategy for treating pancreatic adenocarcinoma.