• 아시안잔디학회지
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• 제21권2호
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• pp.163-175
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• 2007

본 실험은 키토산의 처리가 켄터키 블루그래스의 생육에 미치는 영향에 대하여 조사하기 위해 실시되었다. 키토산은 잔디가 이식된 후 10일 후에 300, 500, 800배 희석되어 각각 처리되었다. 실험은 뿌리길이, 지상부 생채중 및 건물중, 지하부 생채중 및 건물중, 엽록소 함량변화에 대하여 조사하였다. 캔터키 블루그래스의 엽장에 대한 효과는 키토산 300배 처리 시 평균 26.2cm로 늦은 생장률을 나타내어 무처리 시 평균 17.1cm 생장률 보다 현저히 높은 수치를 나타냈다. 엽수에 대한 키토산 처리와 효과에 있어 캔터키 블루그래스는 키토산 500배 처리 시 31.7매로 엽수가 무처리 21.4매보다 많은 것으로 확인되었다. 또한 캔터키 블루그래스의 키토산 처리에 의한 뿌리 길이의 변화는 무처리에서 16.8cm인 것으로 나타났으며 키토산 500배 처리시 27.4cm로 뿌리 길이의 생육이 증가하는 것으로 나타났다. 엽록소 함량은 무처리 시에서 $19.9mg/100cm^2$로 나타났고, 키토산 300배 처리에서 $25.5mg/100cm^3$로 최대 증가를 나타내었다. 따라서, 본 실험결과 엽수, 뿌리 길이의 생장, 지상부 생채중과 건물중, 지하부 생채중과 건물중은 키토산 500배 처리농도에서 가장 높은 생장 특성을 나타내었다.

• 미생물학회지
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• 제21권2호
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• pp.71-78
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• 1983

The number of aerobic free-living nitrogen fixation bacteria and factors in soil at different stands covered with Pinus rigida, Quercus acutissima and Zoysia japonica in Cheongju area were investigated from Feb. to Sept 1981. 1. The numbers of $N_2-fixation$ bacteria, according to the seasonal changes, increased gradually from winter to spring and summer. But the growth pattern revealed some differences in accordance with plant cover stands : the numbers increased abruptly in May at Pinus, May-June at Quercus and Apr. May at Zoysia stand. The pick of numbers represented in Aug. Sept, at Pinus, Jul-Aug. at Quercus and May-Jun. at Zoysia stand, respectively. 2. The interrelationship between the monthly changes of enviotnmental factors and numbers of $N_2-fixation$ bacteria at different stands, mainly depends upon the soil temperature than other soil factors (r=0.71-0.84). The numbers of $N_2-fixation$ bacteria may increase 5-7 times according to increase $10^{\circ}C$ of soil temperature, and optimal range was $20{\sim}30^{\circ}C$ for growth. Equation of the interrelation between soil temperature and numbers could be stated as follows : log y=ax+b. 3. In the case of high soil temperature, the bacterial numbers presented high level in drought periods. Therefore, the $N_2-fixation$ bacterial species in these soil seem to consist of resistant to desication. 4. The influence of soil organic matter for growth of $N_2-fixation$ bacteria indicated low conrelation. The reason may seen the content of organic matter in these soil existed abundantly above the quantities of limitation for growth. 5. In artifical gradients, the $N_2-fixation$ bacteria were predominated at $20{\sim}30^{\circ}C$ same as natural condition, pH7-8, and 20-30% of soil water contents. 6. The vertical distribution of bacteria marked decreasing trends from surface to lower layers, and the decreasing degree was shown well in Zoysia, Quercus and Pinus stand in order. But in the trees, the numbers increased at 30cm layer estimated the region of root than 20cm layer. 7. Both catalase megative and positive group of $N_2-fixation$ bacteria in soil increased according to the rise of the soil temperature. Catalase positive group was revealed as dominant group in winter, and catalase negative group revealed in summer. The change of dominant pattern was shown during Feb. to Apr.

• Journal of Periodontal and Implant Science
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• 제29권3호
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• pp.621-636
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• 1999

When mucoperiosteal flaps are positioned and sutured to desirable position, the wound contains several interface between tissues which differ fundamentally in composition & biological reaction. Thus the C-T surface of the flap will, on one hand, oppose another vascularized surface, and on the other, the avascular dental material for example, when root resoptions, fractured root, endodontic perforation, deep root carious lesions were filled with amalgam, glass ionomer, resin etc. Recently, a number of case report described the successful treatment of a subgingival root lesion with restorative material & free gingival graft, open flap surgery, but more objective research was needed . Most of study on restorative materials were concerned for cytotoxicity not for actual healing event on that materials and its influencing factors such as biocompatibility, surface wettability, surface topography . The aim of this in vitro study was to evaluate the effect of amalgam, resin modified glass ionomer, composite resin per se, and their surface roughness on the growth of human gingival fibroblast. The cells were obtained and placed on culture flask and incubated for 3 days with the prepared test materials. Then count the attached cell number with hemocytometer,(n=12) and 2 samples were examined with SEM about attachment cell morphology . Another 4 samples were evaluated on their surface roughness with Talysurf and average surface roughness value(Ra) were obtained. Statistical difference in attached cell number, roughness value were analyzed using ANOVA. The number of attached cell was as follows, for root dentin specimen 16.7${\pm}$4.41, resin modified glass ionomer 14.0${\pm}$4.15, resin 8.13${\pm}$3.63, amalgam 0.72${\pm}$3.33(${\times}10^3$). Between root dentin and resin-modified glass ionomer, no significant difference was observed, but resin, amalgam showed a significant less cell numbers than for root dentin, resin modified glass ionomer cement. SEM examination expressed many cell surface attachment apparatus in root dentin and resin modified glass ionomer specimens. For resin specimen, cell attachment was observed but exposed less appratus. The average surface roughness value are following results. Dentin specimen 0.6972${\pm}$ 0.104, resin modified glass ionomer 0.0822${\pm}$0.009, resin 0.0875${\pm}$0.005, amalgam 4.2145${\pm}$0.985(${\mu}m$). Between root dentin, resin-modified glass ionomer, and resin, no significant difference was observed, but amalgam showed a significant more rough surface than other groups. When evlauated the interrelationship between cell attachment and surface roughness, therefore, there was weak reverse correlation.(pearson correlation : - 0.593) These results suggest that resin modified glass ionomer have the favorable healing potential when used for subgingival restoration. And for relationship between cell attachment and surface characteristics, further investigations were needed.

• 생명과학회지
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• 제25권4호
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• pp.390-396
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• 2015

본 연구는 항산화 기능이 뛰어나다고 알려진 며느리배꼽(Persicaria perfoliata)의 캘러스를 사용하여, 어떤 식물호르몬이 부정근 형성에 영향을 미치는지 알아보기 위한 실험이다. 며느리배꼽의 잎으로부터 캘러스를 유도하고 이로부터 부정근 형성을 관찰하였다. 캘러스 유도의 최적 조건을 구한 결과 1% sucrose, 4.5 μM 2.4-D, 1/2 MS였다. 어떤 식물호르몬이 이 식물의 캘러스에서 부정근 형성 효과를 가지고 있는지 알아보기 위하여 GA₃, IAA, 2iP, 2,4-D를 캘러스 조직에 각각 첨가한 결과, GA₃와 IAA를 첨가한 배지에서만 부정근이 나타났음을 확인 할 수 있었다. 이를 자세히 조사하기 위해서 GA₃와 IAA의 농도별(0.1, 1, 10 mg/l) 부정근 형성, 길이 및 직경을 알아본 결과, 높은 수준의 GA₃ 또는 낮은 수준의 IAA처리에서 더 많은 부정근 형성을 보였다. 이 두 호르몬 중 어떤 것이 더욱 더 중요한 역할을 하는지 알아보기 위하여 옥신 유입 저해제인 NPA와 지베렐린 생합성 저해제인 PBZ를 처리한 실험을 한 결과, GA₃가 IAA 보다 부정근 형성에 더욱 더 중요한 역할이라는 것을 알았다. 하여 지베렐린의 수준을 증가 또는 감소시킨다고 알려진 식물호르몬(IAA, 2iP, kinetin, ABA)들을 GA₃와 혼용 처리한 결과, 이 역시 지베렐린이 부정근을 형성하는데 중요한 역할을 한다는 것을 재확인 하였다. 본 연구는 지베렐린이 며느리배꼽의 캘러스에서 부정근 형성을 증진시킨다는 것을 처음으로 밝힌다.

• Journal of Chest Surgery
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• 제49권4호
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• pp.250-257
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• 2016

Background: Generalization of standardized surgical techniques to treat aortic valve (AV) and aortic root diseases has benefited large numbers of patients. As a consequence of the proliferation of patients receiving aortic root surgeries, surgeons are more frequently challenged by reoperative aortic root procedures. The aim of this study was to evaluate the outcomes of redo-aortic root replacement (ARR). Methods: We retrospectively reviewed 66 patients (36 male; mean age, $44.5{\pm}9.5years$) who underwent redo-ARR following AV or aortic root procedures between April 1995 and June 2015. Results: Emergency surgeries comprised 43.9% (n=29). Indications for the redo-ARR were aneurysm (n=12), pseudoaneurysm (n=1), or dissection (n=6) of the residual native aortic sinus in 19 patients (28.8%), native AV dysfunction in 8 patients (12.1%), structural dysfunction of an implanted bioprosthetic AV in 19 patients (28.8%), and infection of previously replaced AV or proximal aortic grafts in 30 patients (45.5%). There were 3 early deaths (4.5%). During follow-up (median, 54.65 months; quartile 1-3, 17.93 to 95.71 months), there were 14 late deaths (21.2%), and 9 valve-related complications including reoperation of the aortic root in 1 patient, infective endocarditis in 3 patients, and hemorrhagic events in 5 patients. Overall survival and event-free survival rates at 5 years were $81.5%{\pm}5.1%$ and $76.4%{\pm}5.4%$, respectively. Conclusion: Despite technical challenges and a high rate of emergency conditions in patients requiring redo-ARR, early and late outcomes were acceptable in these patients.

• Journal of Periodontal and Implant Science
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• 제38권4호
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• pp.679-690
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• 2008

Purpose: The aim of this study was to investigate the effects of EMD on demineralized root surface using human periodontal ligament cells and compare the effects of root conditioning materials(tetracycline(TCN), EDTA). Material and Methods: Dentin slices were prepared from the extracted teeth and demineralized with TCN and EDTA. Demineralized dentin slices were incubated at culture plate with 25, 50 and $100{\mu}g/ml$ concentration of EMD. Cell attachment, alkaline phosphatase activity test, protein synthesis assay and scanning electronic microscopic examination were done. Results: Cells were attached significantly higher in EMD treated group at 7 and 14 days. Cell numbers were significantly higher in EMD treated group. Alkaline phosphatase activity was significantly higher in EMD treated group at 7 and 14 days. Protein synthesis was significantly higher in EMD treated group at 7 and 14 days. Conclusion: Enamel matrix derivatives enhance the biologic activities of human periodontal ligament cells on demineralized root surface and its effects are dependent on the concentration of EMD.

• 대한전자공학회논문지TE
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• 제37권5호
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• pp.7-16
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• 2000

본 논문은 고속 지수 선택기를 이용한 여분 부동 소수점 이진수의 제산/스퀘어-루트 설계 및 구현에 관하여 기술하였다. 본 제산/스퀘어-루트는 처리 속도 25㎒를 갖는 여분 이진수의 가산 방식을 사용하여 올림수 지연을 제거함으로써 비트 크기에 관계없이 일정한 시간으로 가산을 수행한다. 각각의 반복 단계에 널리 사용된 제산과 스퀘어-루트에 대해 16-비트 VLSI 회로를 설계하였다. 이것은 매번 16개 클럭마다 시프트된 이진수를 여분 가산하여 제산 및 스퀘어-루트를 실행한다. 또한 이 회로는 비복원 방법을 사용하여 지수 비트를 얻는다. 지수 선택 논리의 간단한 회로를 구현하기 위하여 나머지 비트의 주요 세 자리를 사용하였다. 결과적으로, 이 회로의 성능은 새로운 지수 선택 가산 논리를 적용하여 지수 결정 영역을 병렬 처리함으로써 한층 더 연산 처리 속도를 높인 것이다. 이전에 동일한 알고리즘을 사용하여 제안된 설계보다 13% 빠른 속도 증가를 보였다.

• Restorative Dentistry and Endodontics
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• 제45권1호
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• pp.7.1-7.9
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• 2020

Objectives: This study was performed to assess the anatomy of mandibular first molars. Materials and Methods: In this in vivo study, cone-beam computed tomography (CBCT) volumes of 312 bilateral intact first mandibular molars from 156 patients (79 men and 77 women; average age, 35.6 ± 11.2 years) were investigated in terms of the direction of each canal's curvature in the buccolingual and mesiodistal dimensions (direction of the position of the apex in relation to the longitudinal axis of the root), the presence of an isthmus (a narrow, ribbon-shaped communication between 2 root canals) in 3 segments (0-2, 2-4, and 4-6 mm) from the apex), and the presence and number of accessory canals (smaller canals besides the main root canals, connecting the pulp to the periodontium). Data were analyzed statistically (α = 0.05). Results: Mesiolingual canals were mostly buccally and distally inclined, while mesiobuccal and distolingual canals were mostly distally curved. Isthmuses were more common in younger patients (χ² test, p < 0.05). The average numbers of accessory canals in the apical, middle, and coronal segments were 9.9 ± 4.2, 6.9 ± 2.9, and 9.3 ± 3.0 canals per segment, respectively (analysis of variance, p < 0.001). Age and sex were not associated with the number of accessory canals (p > 0.05). Conclusions: The complex anatomy of these teeth deserves attention during non-surgical or surgical endodontic treatment. Around the apex, isthmuses might be more prevalent in younger and female individuals.

• 한국작물학회지
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• 제24권1호
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• pp.66-72
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• 1979

동일주에서 발생한 근을 이등분하여 생육환경을 바르게 하였을 때 근부와 지상부의 형질에 미치는 영향을 조사하였던 바 그 결과를 요약하면 1. 근의 생육에 좋은 환경에서 성장한 편보다 과습 과건등 좋지 못한 환경에서 성장한 편이 근수는 적고 근장은 짧았으며 근중은 가벼웠다. 2. 또 근의 양편 모두 생육에 좋은 환경에서 성장한 주보다 한편만이 좋지 못한 환경에서 성장한 주가 근수는 적고 근장은 짧았으며 근중은 가벼웠다. 3. 따라서 동일주에서 한편의 근을 생육환경을 불량하게 하였을 때 그 근에 직접 부착되어 있는 지상부의 생육에만 영향을 미치는 것이 아니고 일주전체에 영향이 있는 경향으로 4. 근의 양편 모두 생육에 좋은 환경에서 성장한 주보다 한편만이 좋지 못한 환경에서 성장한 주가 출수기는 지연되고 간장과 수장이 짧았으며 유효경비율도 낮았다. 5. 수량은 근의 생육량과 정의 유의상관을 보여 근의 생육이 좋은 환경에서 성장한 주에 비하여 임쪽이 좋지 못한 환경에서 성장한 주의 수량이 감수되었는데 감수정도는 과건>과습, 사토> 식양토 순위였다.

• Preventive Nutrition and Food Science
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• 제13권3호
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• pp.157-165
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• 2008

Cancer-preventive effects of ethanol extract of elm tree root (EEE) were investigated. In the in vitro cytotoxicity assay, colon cancer cells were incubated with a chloroform fraction of EEE (CF-EEE). CF-EEE significantly inhibited the proliferation of cells and induced apoptotic cell death in a dose-dependent manner. For the assessment of chemopreventive efficacy in vivo, male F344 rats were fed with EEE (0.5 or 1%) in diet for 8 weeks, and were subcutaneously injected with 1,2-dimethylhydrazine (DMH) to induce colonic aberrant crypt foci (ACF). EEE (0.5 and 1%) significantly decreased both the numbers of AC (1191.1/colon) and ACF (529.3/colon) induced by DMH. In addition, in the Western blot analysis on the colonic mucosa, administration of EEE triggered expression of caspase-3, a key factor of an apoptotic cascade. These results suggest that extract of elm tree root may have potential chemopreventive principles that lead to apoptosis of cancer cells, and thereby suppress colorectal carcinogenesis during the initiation stage.