• International Journal of Naval Architecture and Ocean Engineering
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• 제5권4호
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• pp.580-597
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• 2013

Three materials SUS304, 9% Ni steel and Al 5083-O alloy, which are considered possible candidate for International Maritime Organization (IMO) type B Cargo Containment System, were studied. Monotonic tensile, fatigue, fatigue crack growth rate and Crack Tip Opening Displacement tests were carried out at room, intermediate low ($-100^{\circ}C$) and cryogenic ($-163^{\circ}C$) temperatures. The initial yield and tensile strengths of all materials tended to increase with decreasing temperature, whereas the change in elastic modulus was not as remarkable. The largest and smallest improvement ratio of the initial yield strengths due to a temperature reduction were observed in the SUS304 and Al 5083-O alloy, respectively. The fatigue strengths of the three materials increased with decreasing temperature. The largest increase in fatigue strength was observed in the Al 5083-O alloy, whereas the 9% Ni steel sample showed the smallest increase. In the fatigue crack growth rate test, SUS304 and Al 5083-O alloy showed a decrease in the crack propagation rate, due to decrease in temperature, but no visible improvement in da/dN was observed in the case of 9% Ni steel. In the Crack Tip Opening Displacement (CTOD) test, CTOD values were converted to critical crack length for the comparison with different thickness specimens. The critical crack length tended to decrease in the case of SUS304 and increase for the Al 5083-O alloy with decreasing temperature. In case of 9% Ni steel, change of critical crack length was not observed due to temperature decrease. In addition, the changing material properties according to the temperature of the LNG tank were analyzed according to the international code for the construction and equipment of ships carrying liquefied gases in bulk (IGC code) and the rules of classifications.

• Parasites, Hosts and Diseases
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• 제35권3호
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• pp.149-154
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• 1997

저장 곡류 해충으로 알려져 있는 긴털가루진드기(rophnwpkescentios)가 우리 나라 가옥 내 집먼지 서식 진드기류 중 제 3의 우점종으로 밝혀짐에 따라 알레르기성 질환을 야기하는 원인 항원으로 작용할 가능성이 높아져 연구의 대상이 되고 있다. 본 연구에서는 진단, 치료 및 면역학 적 연구에 필요한 다량의 항원을 공급하기 위하여 대량 사육방법의 개발을 시도하여 다음과 같은 결과를 얻었다. 긴털가루진드기를 대량 사육하는데 가장 적합한 사육배지로는 실험동물사료 분말 로 사육 10주 후 1,251.5배의 개체 증가를 보였고 효소분말과 실험동물 사료분말의 혼합배지 (1 : 1)에서도 사육 10주 후 1.203.1배의 개체 증가를 보여 거의 같은 성적을 보였다. 사육조건으 로 가장 적합한 온도와 상대습도는 $25^{\circ}C$. 64% RH로서 9주 후 960배로 가장 높은 증식결과를 보였고, $^25{\circ}C$와 75% RH에서도 935.4배의 개체 증가로 거의 동일한 결과를 나타냈다 사육용기 표면적을 $79{\;}cm^2,{\;}154{\;}cm^2{\;}및{\;}227{\;}cm^2$로 사육 비교한 결과 각각 860.8배. 924.6배 및 1,250.8 배의 개체 증가를 보여 현저한 차이는 보이지 않았다.

• Corrosion Science and Technology
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• 제20권4호
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• pp.210-229
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• 2021

To safely operate domestic nuclear power plants approaching the end of their design life, the material degradation management strategy of the components is important. Among studies conducted to improve the soundness of nuclear reactor components, research methods for understanding the degradation of reactor internals and preparing management strategies were surveyed. Since the IGSCC (Intergranular Stress Corrosion Cracking) initiation and propagation process is associated with metal dissolution at the crack tip, crack initiation sensitivity was decreased in the hydrogenated water with decreased crack sensitivity but occurrence of small surface cracks increased. A stress of 50 to 55% of the yield strength of the irradiated materials was required to cause IASCC (Irradiation Assisted Stress Corrosion Cracking) failure at the end of the reactor operating life. In the threshold-stress analysis, IASCC cracks were not expected to occur until the end of life at a stress of less than 62% of the investigated yield strength, and the IASCC critical dose was determined to be 4 dpa (Displacement Per Atom). The stainless steel surface oxide was composed of an internal Cr-rich spinel oxide and an external Fe and Ni-rich oxide, regardless of the dose and applied strain level.

• 화훼연구
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• 제19권1호
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• pp.8-14
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• 2011

본 연구는 두 품종의 장미 삽목묘의 묘령에 따른 생장과 수량에 미치는 영향을 조사하고 국내 육성 절화장미의 효과적인 삽목번식법을 개발하고자 수행하였다. 장미는 스탠다드 계통인 'Pink Aurora'와 스프레이 계통인 'Yellow King' 품종을 사용하였다. 삽수는 5매엽을 사용하였고 서로 다른 날짜에 암면큐브($5cm{\times}5cm{\times}5cm$, UR, 한국)에 삽목하였다. 2009년 1월 20일에 삽목하여 30일이 경과한 삽목묘와 2009년 1월 2일에 삽목하여 48일이 경과한 묘를 사용하여 2009년 4월 18일에 암면슬래브($10cm{\times}15cm{\times}100cm$, UR, 한국)에 정식하였다. 2009년 1월부터 7월까지 재배하는 동안에 2번 수확하여 절화의 품질을 조사하였다. 정식전의 생육을 조사한 결과 48일이 경과한 묘는 두 품종 모두 신초와 뿌리가 생장하였다. 그러나 30일이 경과한 묘는 'Pink Aurora'의 경우 신초와 뿌리가 생장하지 않았고, 'Yellow King'은 신초는 생장하였고 뿌리는 생장하였으나 배지에서 육안으로 확인할 수 없었다. 이러한 결과로 'Yellow King'이 'Pink Aurora'보다 생장속도가 빠른 것으로 판단된다. 정식 후의 생장과 절화 수량은 스탠다드 계통인 'Pink Aurora'는 30일 경과한 묘보다 48일이 경과한 묘에서 수량이 더 많이 나타났지만, 평균 절화 생체중은 30일이 경과한 묘보다 작았다. 'Yellow King' 품종은 30일이 경과한 묘에서 절화장, 화폭, 5매엽수, 절화 생체중, 수량이 40일 경과한 묘보다 더 높았다. 'Pink Aurora' 품종은 48일이 경과한 묘에서 다른 처리에 비해 더 좋은 생육을 보였다. 'Yellow King' 품종은 뿌리의 상처가 작았던 30일이 경과한 묘에서 더 높은 수량을 보였다. 이러한 결과는 품종에 따른 성숙도의 차이로 판단되며 다양한 품종을 대상으로 한 실험이 필요하다고 생각된다.

• 한국재료학회지
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• 제30권6호
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• pp.292-300
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• 2020

In this study, the effect of tempering on the stretch-flangeability is investigated in 980 MPa grade dual-phase steel consisting of ferrite and martensite phases. During tempering at 300 ℃, the strength of ferrite increases due to the pinning of dislocations by carbon atoms released from martensite, while martensite is softened as a consequence of a reduction in its carbon super-saturation. This strength variation results in a considerable increase in yield strength of the steel, without loss of tensile strength. The hole expansion test shows that steel tempered for 20 min (T20 steel) exhibits a higher hole expansion ratio than that of steel without tempering (T0 steel). In T0 steel, severe plastic localization in ferrite causes easy pore formation at the ferrite-martensite interface and subsequent brittle crack propagation through the highly deformed ferrite area during hole expansion testing; this propagation is mainly attributed to the large difference in hardness between ferrite and martensite. When the difference in hardness is not so large (T20 steel), on the other hand, tempered martensite can be considerably deformed together with ferrite, thereby delaying pore formation and hindering crack propagation by crack blunting. Eventually, these different deformation and fracture behaviors contribute to the superior stretch-flangeability of T20 steel.

• Journal of Microbiology
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• 제45권2호
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• pp.133-138
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• 2007

This study addresses the susceptibility of Spodoptera frugiperda (Sf9 and Sf21), Trichoplusia ni (Hi5), and S. exigua (Se301) cells to the Bombyx mori nucleopolyhedrovirus (BmNPV). Although these cells have classically been considered nonpermissive to BmNPV, the cytopathic effect, an increase in viral yield, and viral DNA synthesis by BmNPV were observed in Sf9, Sf21, and Hi5 cells, but not in Se301 cells. Very late gene expression by BmNPV in these cell lines was also detected via ${\beta}-galactosidase$ expression under the control of the polyhedrin promoter. Sf9 cells were most susceptible to BmNPV in all respects, followed by Sf21 and Hi5 cells in decreasing order, while the Se301 cells evidenced no distinct viral replication. This particular difference in viral susceptibility in each of the cell lines can be utilized for our understanding of the mechanisms underlying the host specificity of NPVs.

• 대한화학회지
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• 제38권12호
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• pp.885-890
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• 1994

텅스텐 전극을 작업전극으로 사용하여 산성수용액에서 아닐린의 전기화학적 중합을 순환 전압-전류법으로 연구하였다. 아닐린 분자는 2전자 전이에 의하여 탈수소 아닐린이온으로 산화하고, 중성아닐린을 공격하여 중합체를 만든다. 그러나 백금전극의 경우와는 다르게 중합과정은 주로 아닐린의 산화에 의해서 일어난다. 성장속도는 백금전극의 경우와 비교하여 느린 것으로 나타났다. 분해생성물은 벤조퀴논이 아니라 p-phenylenediamine(p-PDA)으로 확인 되었는데 이것은 1.0 V 이하의 전위에서 p-PDA의 산화가 관측되지 않은 결과와도 일치한다.

• 전자공학회논문지S
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• 제35S권2호
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• pp.70-78
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• 1998

Spike detection in long-term EEG monitoring forepilepsy by wavelet transform(WT), artificial neural network(ANN) and the expert system is presented. First, a small set of wavelet coefficients is used to represent the characteristics of a singlechannel epileptic spikes and normal activities. In this stage, two parameters are also extracted from the relation between EEG activities before the spike event and EEG activities with the spike. then, three-layer feed-forward network employing the error back propagation algorithm is trained and tested using parameters obtained from the first stage. Spikes are identified in individual EEG channels by 16 identical neural networks. Finally, 16-channel expert system based on the context information of adjacent channels is introducedto yield more reliable results and reject artifacts. In this study, epileptic spikes and normal activities are selected from 32 patient's EEG in consensus among experts. The result showed that the WT reduced data input size and the preprocessed ANN had more accuracy than that of ANN with the same input size of raw data. Ina clinical test, our expert rule system was capable of rejecting artifacts commonly found in EEG recodings.

• Plant Biotechnology Reports
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• 제2권3호
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• pp.179-189
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• 2008

We established an efficient plant regeneration system for Catharanthus roseus L. (G.) Don through somatic embryogenesis. Embryogenic callus was induced from hypocotyl of seed germinated in vitro. Somatic embryogenesis in Catharanthus has been categorized into three distinct stages: (1) initiation and proliferation of embryo; (2) maturation, and; (3) germination or plantlet conversion. Beside plant growth regulators, various stages of embryogenesis were screened for their response to a wide variety of factors (pH, gelrite, light, sugar alcohols, polyethyleneglycol and amino acids), which affect embryogenesis. All of the tested factors had a small to marked influence on embryogeny and eventual conversion to plantlets. The plantlets were acclimatized successfully in a greenhouse. To our knowledge, this is the first report describing a detailed study of various cultural factors which regulate embryogenesis in C. roseus. The results discussed in this paper may be used in mass propagation to produce medicinal raw material, and the embryo precursor cells could be used in genetic modification programmes that aim to improve the alkaloid yield as well.

• 한국해양공학회지
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• 제8권1호
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• pp.114-122
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• 1994

X-ray stress constant, K, was determined for the diffraction line of (211)plane by using Cr-K$\alpha$ radiation. K was -340.87 MPa/deg. Fatigue crack propagation tests of SS41 steel were conducted under stress ratios of 0.1, 0.3 and 0.5. The half-value breadth of X-ray diffraction profile was measured at and beneath the fracture surface. The half-value breadth, B, on the fracture surface was found to increase with increasing $K_max$. The value of B was influenced by stress ratio in SS41 steel. The half-value breadth took the maximum value at the borden of reversed plastic zone, while it approached to the initial (pre-fatigue) value near the boundary of monotonic plastic zone. The maximum depth of the plasticzone was evaluated on the basis of the half-value breadth distribution. The depth $\omega$$_y$ is related to $K_max$by the following equation : $\omega$$_y$ = $\alpha$($K_max$/$\sigma$$_y$$)^2$ where .sigma.$\sigma$$_y$ is the yield strength obtength obtained in tension test .alpha.is 0.136 for SS41 steel.