• Journal of Species Research
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• 제9권4호
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• pp.448-454
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• 2020

Nine free-living heterotrophic flagellates were cultured from marine intertidal sediments and freshwater sediments from Korea. These species are described with uninterpreted records based on light microscopy of living cells and reported taxonomically for the first time from Korea. Diagnostics of these species are as follows; Notosolenus hemicircularis: 9-11.8 ㎛ long with flagellar reservoir, ventrally flattened and dorsally convex with hyaline semicircular collar around short anterior neck, and 8 ridges on cell surface. Thecamonas tranhens: 4.5-7.1 ㎛ long, plastic with proboscis comprising an anterior flagellum surrounded by membranous sleeve. Bodomorpha minima: 4.5-7.0 ㎛ long, rigid with small rostrum in anterior end and active anterior flagellum. Cercomonas hiberna: 5.6-10.9 ㎛ long, very plastic with pseudopodia, cytoplasmic strand and 1 or 2 contractile vacuoles. Cercomonas pellucida: 7.5-13 ㎛ long, plastic with pseudopodia, cytoplasmic strand and single contractile vacuole. With nucleus closely connected to basal bodies. Eocercomonas echina: 4.7-6.5 ㎛ long, plastic with pseudopodia, cytoplasmic strand and 1 or 2 contractile vacuoles. Paracercomonas astra: 5.7-7.3 ㎛ long, moderately metabolic with pseudopodia, cytoplasmic strand and 1 or 2 contractile vacuoles. Paracercomonas minima: 5-9 ㎛ long, metabolic with pseudopodia, cytoplasmic strand and single contractile vacuole. Paracercomonas producta: 6.1-9.9 ㎛ long, very metabolic with pseudopodia, long cytoplasmic strand and single contractile vacuole.

• Journal of the Korean Wood Science and Technology
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• 제50권4호
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• pp.237-245
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• 2022

This study examined the structural performance of experimental parallel strand lumber (PSL) from a Larch veneer strand. The prototype of PSL from a Larch veneer strand was manufactured in the experimental laboratory and tested. The bending and dowel bearing strength were determined from the modulus of elasticity (MOE), modulus of rupture (MOR), and dowel bearing strength based on a 5% offset yield load. The test results indicated that the average MOR of PSL was higher than that of 2 × 4 dimension lumber, and the average MOE of PSL was lower than that of 2 × 4 dimension lumber. A linear relationship was observed between the MOR and MOE. The allowable bending stress of PSL was derived as specified in ASTM D2915 and compared with other research. The dowel bearing strength of PSL in parallel to the grain was approximately double that perpendicular to the grain of PSL. A comparison of several theoretical calculations based on each national code for the dowel bearing strength was conducted, and some theoretical equations produced results closer to the experimental results when it was parallel to the grain, but the difference was higher in the case perpendicular to the grain. The test results showed that PSL made with Japanese larch veneer strands appeared to be suitable for a raw material of structural composite lumber (SCL) appeared to be used as a raw material for SCL.

• Radiation Oncology Journal
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• 제8권2호
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• pp.137-144
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• 1990

Filter elution 방법으로 EL 4백서 백혈병 세포 및 C57BL/6백서 유래의 비장 임파구에 대한 Co-60 $\gamma$ 선의 DNA single-strand breaks (SSB) 효과를 정량적으로 측정하였다. 임파구는 [${^3}H$]thymidine을 표지하기 위하여lipopolysaccharide (LPS, 20 $\mug/ml$)를 첨가하여 자극하고 부유 상태의 EL 4 세포 및 임파구를 $0^{\circ}C$에서 0 Gy, 1 Gy, 5 Gy, 10 Gy 또는 15 Gy조사하였으며, elution용액의 pH는 12.1로 하였다. $\gamma$ 선 조사에 따른 single-strand breaks의 수는 방사선 조사량에 따라 증가 하였으며 21 ml elution 양을 기준으로 한 strand scission factor (SSF)는 EL 4 세포에서 $0.01301\pm0.00096\;Gy^{-1}(n=5)$이었고, 임파구는 $0.01097\pm0.00091\;Gy^{-1}(n=5)$를 나타내므로 본 실험에서는 EL 4 세포가 정상 임파구에 비하여 방사선에 의한 DNA SSB가 민감함을 알 수 있었다(p<0.005). 본 연구 결과 DNA strand breaks의 측정법을 이용하여 방사선의 특성 및 생물학적 효과의 파악은 물론 나아가 기존의 방호제 및 새로운 약제의 DNA에 대한 효과를 판별할 수 있을 것이다.

• Radiation Oncology Journal
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• 제11권2호
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• pp.219-225
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• 1993

각 방사선량의 조사에 따른 사람 정상임파구, 마우스 정상임파구, 그리고 EL-4마우스 백혈병 세포의 DNA double strand breaks 발생율에 대하여 비교분석 하였던 바 다음과 같은 결과를 얻었다. LPS와 PHA를 첨가하여 각각 배양한 마우스 정상임파구의 DNA double strand breaks의발생율을 strand scission factor의 기울기로 비교평가해 본 바 LPS를 첨가배양한 군이 DNA DSB가 더 많이 형성되었다(P<0.005). 이것으로 볼 때 DNA double strand breaks발생에 있어서는 B cells이 T cells보다 더 민감하였다. 또한 EL-4 백혈병 세포는 정상 임파구보다 유의하게 DNA DSB가 더 많이 형성된 것이 관찰되었다(p<0.005). 한편 사람 정상임파구와 마우스 정상임파구 사이의 intrinsic radiosensitivity는 시험관내 실험에서 비교적 유사한 kinetics를 나타냈으나, 마우스 정상임파구가 사람 정상임파구보다 DNA DSB수율이 더 낮았다. 그래서 방사선을 조사하고 3.5시간이 지난후에 $10\%$ DNA DSB발생에 필요한 선량을 두 군간에 비교평가해 본 바 마우스 정상임파구의 선량이 더 높게 나타났다. 이상의 실험결과를 정확하게 설명하기는 어 렵지만 아마도 환경적인 요인과 유전적인 요인 때문인 것으로 사료되었다. 그리고 본 연구결과는 방사선조사에 따른 임상반응의 이해와 cytometric assessment의 방사선 생물학적 parameter로 이용될 수 있을 것으로 판단되었다.

• 대한토목학회논문집
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• 제34권6호
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• pp.1723-1730
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• 2014

최근 건설기술이 발전함에 따라 강연선을 이용한 구조물 시공이 증가하고 있는 추세이다. 현재 강연선의 긴장력 계측을 위한 방법으로는 로드셀과 가속도계를 이용한 간접 추정방식을 주로 이용하고 있다. 그러나, 강연선이 PSC거더 내부에 삽입되어 시공되는 경우에는 장력측정에는 많은 어려움이 있다. 따라서, 본 연구에서는 강연선의 긴장력을 효과적으로 계측하기 위해 전기저항식 스트랜드미터를 개발하였다. 변형률 센서 부착 위치별, 스트랜드미터의 두께와 재료에 따른 영향을 실험을 통해 검토하여 최적의 스트랜드미터를 제안하였다. 또한, 29.9m의 PSC거더에 대한 실규모 검증실험을 수행하여 현장 적용성을 평가한 결과, 하중-변형률의 신뢰도가 높게 평가되었다.

• Journal of Radiation Protection and Research
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• 제41권4호
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• pp.339-343
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• 2016

Background: Evaluation of deoxyribonucleic acid (DNA)-strand break is important to elucidate the biological effect of ionizing radiations. The conventional methods for DNA-strand break evaluation have been achieved by Agarose gel electrophoresis and others using an electrical property of DNAs. Such kinds of DNA-strand break evaluation systems can estimate DNA-strand break, according to a molecular weight of DNAs. However, the conventional method needs pretreatment of the sample and a relatively long period for analysis. They do not have enough sensitivity to detect the strand break products in the low-dose region. Materials and Methods: The sample is water, methanol and plasmid DNA solution. The plasmid DNA pUC118 was multiplied by using Escherichia coli JM109 competent cells. The resonance frequency and Q-value were measured by means of microwave dielectric absorption spectroscopy. When a sample is located at a center of the electric field, resonance curve of the frequency that existed as a standing wave is disturbed. As a result, the perturbation effect to perform a resonance with different frequency is adopted. Results and Discussion: The resonance frequency shifted to higher frequency with an increase in a concentration of methanol as the model of the biological material, and the Q-value decreased. The absorption peak in microwave power spectrum of the double-strand break plasmid DNA shifted from the non-damaged plasmid DNA. Moreover, the sharpness of absorption peak changed resulting in change in Q-value. We confirmed that a resonance frequency shifted to higher frequency with an increase in concentration of the plasmid DNA. Conclusion: We developed a new technique for an evaluation of DNA damage. In this paper, we report the evaluation method of DNA damage using microwave dielectric absorption spectroscopy.

• 복식
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• 제57권8호
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• pp.37-47
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• 2007

This study is considered about the fabrics of the tomb of King Muryeong at the Baekje(百濟) Period. First, there were silk fabrics such as compound woven silk(錦), twill damask(綾), complex gause(羅) and plain weaved silk(平絹). All of compound woven silk(錦) are the warp-faced compound tabby(經錦) of plain weave and the density is various from high to low one. The twill damask(綾) was a variation of twill damask weaved with a six strand warp thread. The complex gause(羅) made patterns as a set of 2 strand, 4 strand, 6 strand and 8 strand warp threads are weaved alternately with the weft. There were three kinds of plain weaved silk(平絹). The first was weaved densely without space between strands. The second was weaved with a small space between strands. And the third was weaved with a two strand warp thread, having a space between the threads. On the other hand, several pieces of well preserved ramie cloth were excavated. Of the, the densest one has the density of 125 strand/inch for the warp and the weft. In addition, strings made of flax thread were found. This suggests that flax fabrics may be found additionally if the hardened lumps of fabrics are resolved and analyzed. Other materials discovered include knits, knotted strings, embroideries, threads and floss. Pieces considered knits and knotted strings occupy a large part of fabrics excavated from King Muryeong's Tomb, and in particular knotted strings show various knotting methods. In addition, embroideries such as chain stitch and button hole stitch are clearly observed. What is more, there are silk threads and hemp threads, which are presumed to have been used for dangling ornaments such as Yeongrak(瓔珞) and beads or for sewing. Besides, floss was found between fabrics.

• 한국추진공학회지
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• 제17권2호
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• pp.39-45
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• 2013

추진제를 고에너지 금속 분말 연소시스템에 점화원으로 적용을 위한 기초 연구로서 strand burner를 이용하여 HTPB/AP/Al, HTPE/AP/Al 추진제의 연소특성을 고찰하였다. 실험은 아르곤을 사용하여 ~300 psia 까지 가압하였으며, 2개의 석영창을 이용하여 가시화하였다. 추진제 점화를 위해서 10 W의 $CO_2$ 레이저를 사용하였으며, 연소 속도 측정은 초고속 카메라를 활용한 프레임 분석 기법 및 광다이오드를 이용한 연소시간 분석 기법을 적용하였다. 스펙트로메터를 이용하여 300 nm ~ 800 nm, 1500 nm ~ 5000 nm 의 방출 스펙트럼을 분석하여 추진제 연소반응 시 발생하는 화학종을 확인하였다.

• 한국구조물진단유지관리공학회 논문집
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• 제12권5호
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• pp.101-108
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• 2008

본 연구는 콘크리트에서 인발실험(pullout test)을 통해서 인장을 가하지 않은 강연선의 부착특성을 파악하기 위한 것이다. 인장을 가하지 않은 강연선의 부착특성은 이형철근이나 인장이 가해진 강연선과는 다르게 나타난다. 본 연구에서 인장을 가하지 않은 강연선을 철근과 같은 용도로 사용하고 설계하기 위해서는 인장을 가하지 않은 강연선의 부착특성에 관한 연구가 필요하다. 본 연구는 묻힘 길이($10d_b{\sim}60d_b$), 콘크리트 피복두께(45mm, 70mm, 100mm), 그리고 강연선의 직경(12.7mm : SWPC7B, 9.3mm : SWPC7A)을 주요변수로 선정하였다. 실험결과, 묻힘길이가 증가함에 따라 상대적으로 평균부착응력은 감소하는 경향을 보여주고 있으며, 묻힘길이가 ($60d_b$) 이상 확보된다면 인장을 가하지 않은 강연선의 부착성능에 기여할 수 있을 거라 판단된다.

• Radiation Oncology Journal
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• 제13권2호
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• pp.113-120
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• 1995

Purpose : To investigate the effect of alkaloid fraction from Korean ginseng on radiation-induced DNA double strand breaks (dsb) formation and repair in murine lymphocytes Materials and Methods : We used the neutral filter elution technique to assay $^{60}Co\;{\gamma}$ ray-induced DNA double strand breaks formation and repair in C57BL/6 mouse spleen lymphocytes for evaluating the dose-response relationship in the presence of alkaloid fraction as a radioprotective agent. The lymphocytes were stimulated with Phytohemagglutinin (PHA, 2 u g/ml) to label $^3[H]-thymidine.$ Isotope-labelled lymphocytes in suspension were exposed to 100 Gy at $0^{\cdot}C$ in the alkaloid fraction-treated group and elution procedure was performed at PH 9.6. The extents of formation of radiation-induced DNA double strand breaks and repair were compared respectively via strand scission factor (SSF) and relative strand scission factor (RSSF). Results: Alkaloid fraction reduced the formation of double strand breaks with dose modification factor of 2 15, compared to control group Rejoining of DNA dsb appeared to take place via two components. The first fast component was completed within 20.4 minutes, but the second slow component was not completed until 220.2 minutes after irradiation. About $30\%$ of dsb formed by irradiation was ultimately unrejoined despite the administration of alkaloid fraction. The administration of alkaloid fraction had a great effect on the second slow component of repair; the half-time of fast component repair was not changed, but that of slow component was 621.8 minutes. Conclusion: Neutral filter elution assay Proved to be a very effective method to quantitate the extents of DNA dsb formation and its repair. By using this technique, we were able to evaluate the efficiency of alkaloid fraction from Korean ginseng as a valuable radioprotector. Alkaloid fraction can be used prophylactically to prevent or ameliorate the severe radiation damages in workers and neighbors around the atomic power plants. For more refined study, however, more advanced purification of alkaloid fraction wil be needed in the near future.