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유용욱,김지현,지운,강준구 대한토목학회 2019 대한토목학회논문집 Vol.39 No.5
하천 내 흐름에 대한 식생 밀도의 영향을 조사하기 위해 버드나무가 활착된 하천 규모의 자연형 수로에서 유동 측정 실험을 수행하였다. 식생 내 흐름에 대한 하천 규모 실험은 식생의 반 잠김 조건에 대해 수행되었다. 수로 내 식생대(vegetation patch)는 교차로 형성된 사주의 형상으로 배 열되었고 식생 구간과 비식생 구간에서의 흐름을 비교하였다. 3차원 유동 구조는 초음파 유속계(Acoustic Doppler Velocimeter)에 의해 측정 되었고 종방향 속도의 연직 분포는 다양한 지점에서의 측정값으로부터 분석되었다. 유속은 식생대의 밀도에 따라 다른 양상을 보여 주는데, 식 생 구간와 비식생 구간에서의 흐름 속도의 차이는 밀집된 식생대 주변에서 크게 나타나며 흐름 분포의 형태는 식생대의 하류방향 하단에서 복잡 한 모습을 나타낸다. 하류에 위치한 식생대 주변의 흐름은 상류에 설치된 식생대에 의해 교란된 흐름에도 불구하고 유사한 분포를 보여준다. This study experimentally investigated the effects of high and low densities of vegetation patches on the flow characteristics in a stream-scale outdoor experimental channel with rooted willows. Stream-scale experiments on vegetated flows were carried out for an emergent condition of vegetation. Vegetation patches were arranged by alternate bar formation and the flows in vegetated and non-vegetated sections were compared. Three-dimensional flow structure was measured by ADV (Acoustic Doppler Velocimeter) and the vertical distributions of longitudinal velocity were mainly analyzed from the measurements at various points. Flow velocities show different patterns depending on the density of vegetation patches. The difference in flow velocity between in the vegetated and non-vegetated sections appear to large in the dense patches and the flow becomes complicated at the downstream edge of the patch. Despite the upstream flow disturbed by the first patch, the flows over the second patch show the similar pattern.
‘구석기문화’라는 개념의 발생 과정과 그 효용성에 대하여
유용욱 한국구석기학회 2011 한국구석기학보 Vol.- No.23
So-called "palaeolithic culture" has gained a great currency since its emergence as a semantic equivalence with the "civilization" in the 19th century. This article overviews the trajectory of its usage, transference and propagation in the context of the development of archaeological perspectives on the past humans' materialistic evidences. It can be drawn that various theoretical tenets such as darwinian evolutionism, diffusionism, and phylogeny have contributed to the formulation of palaeolithic culture as a vague conceptual tool; some struggles for its integrative manifestation are exemplified by Childe's "archaeological culture" and the "Mousterian Debates." On the contrary, East Asian archaeology has been inherently dependent on the "culture" of transcendent meanings, biased by each county's social evolutionism and nationalism which were highly valued as a zeitgeist of civilized modernization in the early 20th century. Three examples for those biased exploitation of the term "culture" are demonstrated by the works of Choi Namsun, Torii Ryuzo, and Jia Lanpo respectively. It is concluded that the use of the term "(Palaeolithic) culture" should be accompanied by strict awareness of its explicit meaning as the "materialistic entity resulting from patterned collective behaviors with chronological and temporal significance"; and that in Korean Palaeolithic research in particular, more rigorous consideration for using "culture" as a methodological unit should be ensured so that such an ambiguous culture-based nomenclature, the "pebble-tool cultural tradition" for example, need to be more conceptually redefined.
소목(Caesalpinia sappan) 추출물의 Streptococcus mutans에 대한 성장, 산생성, 부착 및 비수용성 글루칸 합성 억제에 미치는 영향
유용욱,유현희,김윤정,유미선,서세정,이황,이흥수 대한구강보건학회 2003 大韓口腔保健學會誌 Vol.27 No.2
Streptococcus mutans is known as the causative bacterial playing the most important role in forming plaque and it is being noticed as major causative bacteria of dental caries. Therefore, development of more effective, substantial and safe preventive agent against dental caries and periodontal disease is honestly required. The present study was designed to investigate the effect of chloroform extract(CE), n-butanol extract(BE),methanol extract(ME) and water extract(WE) of Caesalpinia on the growth, acid production, adhesion, and insoluble glucan synthesis of Streptococcus mutans. The CE, BE, ME and WE decreased the growth and acid production of S.mutans than that of control, especially, the ME was more effective than other extracts. The effect of CE, BE, ME and WE on the adherences to saliva-coated hydroxyapatite bead(S-HA) were evaluated. At the concentration of 2,000 ㎍/㎖, the CE showed 32% rate of bacterial adherence to S-HA, whereas, other extracts of the same concentration producedgreater than 50% rate. The CE and BE were significantly decreased the reduction rates of water insoluble glucan formation from sucrose by crude glucosyltransferase of S.mutans. Thus, the application of C. sappan can be considered a useful and a practical method for the prevention of dental caries.
Effects of lactoferrin admistration on tooth eruption and bone remodeling in newborn rats
유용욱,김민정,김현진 대한구강해부학회 2021 대한구강해부학회지 Vol.42 No.1
Tooth eruption is composed of tooth movement through a sequential process that includes tooth development and bone remodeling. The relation between the tooth germ and alveolar bone occurs during bone remodeling of the final position in the dental arch. Lactoferrin (LF) is an iron-binding glycoprotein and one of the regulatory functions of LF has been suggested to have a modulator role in bone remodeling. Since tooth eruption and bone remodeling are closely linked, this study aimed to evaluate the effects of LF administration on tooth eruption and bone remodeling during tooth development in newborn rats. Sprague-Dawley rats were divided into four groups as; vehicle control and LF group (12 ㎍/g/day) with six-day and ten-day administration. Newborn rats in LF group were given daily dose of 12 ㎍/g during postnatal six days and ten days, whereas the vehicle control group was injected with sterile saline. Tooth eruption levels of incisor teeth were assessed macroscopically. Histological examination was carried out under light microscope to inspect alveolar bone containing the molar tooth germs. Tartrate-resistant acid phosphatase (TRAP) staining was also performed to evaluate the osteoclastogenic appearance. The LF group observed the acceleration of tooth eruption in incisor teeth at day ten. Through the histological analysis, the bone matrix in the occlusal portion of the second molar tooth germ in LF-treated rats (12 ㎍/g/day) with ten-day administration was resorbed and, at day six, an increase of the number of osteoclasts in the alveolar process of the bony crypt was exhibited when compared with control groups. These findings appear to indicate a novel role of LF as a modulator during bone remodeling during tooth eruption dissimilar to a physiological regulator of bone growth previously reported in experimental models.
유용욱,유현희,김강주,차정단,김혜경,이영은,최나영 한국식품영양과학회 2005 Journal of medicinal food Vol.8 No.4
Methicillin-resistant Staphylococcus aureus(MRSA) bacteria have been responsible for substantial morbidityand mortality in hospitals because they usually have multidrug resistance. Some natural products are candidates as new an-tibiotic substances. In the present study, we investigated the antimicrobial activity of berberine, the main antibacterial sub-stance of Coptidis rhizoma (Coptis chinensis Franch) andPhellodendri cortex (Phellodendron amurense Ruprecht), againstclinical isolates of MRSA, and the effects of berberine on the adhesion to MRSA and intracellular invasion into human gin-gival fibroblasts (HGFs). Berberine showed antimicrobial activity against all tested strains of MRSA. Minimum inhibitionconcentrations (MICs) of berberine against MRSA ranged from 32 to 128 .g/mL. Ninety percent inhibition of MRSA wasobtained with 64 .g/mL or less of berberine. In the checkerboard dilution test, berberine markedly lowered the MICs of ampi-cillin and oxacillin against MRSA. An additive effect was found between berberine and ampicillin, and a synergistic effectwas found between berberine and oxacillin against MRSA. In the presence of 150 .g/mL berberine, MRSA adhesion andintracellular invasion were notably decreased compared with the vehicle-treated control group. These results suggest thatberberine may have antimicrobial activity and the potential to restore the effectiveness of .-lactam antibiotics against MRSA,and inhibit the MRSA adhesion and intracellular invasion in HGFs.
유용욱 서울역사편찬원 2014 서울과 역사 Vol.- No.88
This article is an attempt to reconstruct the cultural phase of initial human occupation in Seoul and mainstream Han River Area(mHRA) by investigating palaeolithic settlement patterns and lithic assemblage characteristics. The palaeolithic assemblage in the mHRA is, compared to those of southern/northen Han tributaries and Imjin River, yet to be documented because of erosion‑dominant fluvial environment and of vigorous development projects during the urbanization of metropolitan Seoul Area. The palaeolithic settlement around the mHRA can be divided into three groups: 1) the northeastern suburb group includes Godeokdong of Seoul, Minrakdong of Uijeongbu, Deokso, Hopyeongdong, and Jisaewul of Namyangju ; in particular, it is noteworthy that such major technological shift as utilization of obsidian and production of microblade industry well‑demonstrated in the Hopyeongdong assemblage around MIS 2 ; 2) the southeastern suburb group includes palaeolithic sites, like Pyeongchangri and Samri in Yongin, Seongnam and Gwangju ; they are mostly small‑scaled settlements located on the low mountainous region and their lithic assemblages are predominantly composed of quartz tools ; 3) the downstream Han River group includes localities on the floodplain of Goyang, Paju, and Gimpo area ; their lithic assemblages are similar to those of the Imjin River Basin in that they commonly includes Acheulian‑like handaxe and other large cutting tools. The initial palaeolithic settlement in this area was possibly formed by centripetal population migrations from the adjacent area and its approximate age is around MIS 3 (60‑50 kya). Hominids in the mHRA might have undergone techno‑cultural adaptation under the stressful environmental condition approaching MIS 2 ; this adaptation process is reflected on the diversification of lithic raw material, change of site location(the altitude), and reduction of the number of tool types by the emergence of specialized, functionally integrated lithic tools. It is highly anticipated that this palaeolithic dynamics of the mHRA can be more vividly illustrated when culturally implicative data is newly discovered in the area. 본고는 서울을 중심으로 흐르는 한강 본류역에 분포하는 구석기 유적의 입지와 출토 유물의 성격을 통해 이 지역에 최초로 인구 점거가 이루어지는 시점의 문화상을 복원하기 위한 시도이다. 한강 본류역의 구석기 문화는 남한강 및 북한강, 그리고 임진강과 같은 인접 하계망 지역에 비해 그다지 많은 연구가 이루어진 예가 없는데, 그것은 침식 위주의 하천 환경과 도시화에 따른 대규모 개발의 영향 때문이다. 한강 본류역의 구석기 유적은 크게 세 가지 군으로 나눌 수 있다. 1) 서울 동북 외곽 지역은 서울 시내의 고덕동, 의정부 민락동, 남양주 덕소, 호평동, 지새울 유적이 해당한다. 호평동 유적에서는 MIS 2기를 전후해서 잔돌날 및 흑요석의 사용례가 주목할 만하다. 2) 서울 동남 외곽 지역은 용인, 성남, 광주 지역을 포함하며 평창리, 삼리 등의 유적이 분포한다. 대부분 구릉성 산지에 분포하는 소규모 유적으로서 석영계 석재가 지속적으로 사용된다. 3) 한강 하류 지역은 고양, 파주, 김포 일대의 충적대지에 유적이 분포하고 있다. 인근의 임진강 유역에서 발견되는 주먹도끼와 같은 대형 석기 위주이다. 한강 본류역의 구석기 유적은 인근 지역에서 인구가 구심 이동을 통해 형성되었을 가능성이 크며, 그 연대는 대략 MIS 3기가 시작되는 약 60,000~50,000 BP에 해당한다. 한강 유역에 거주하던 고인류는 환경적인 스트레스가 증가하는 MIS 2기에 접어들면서 자체적인 기술적, 문화적 적응 과정을 거치게 된다. 이러한 과정은 석재의 다양화, 이동성 증가에 따른 유적 입지(해발고도)의 변화, 전문적인 석기의 등장과 함께 석기 형식 수효의 감소라는 측면에 반영되고 있다. 차후 서울 내부에서 문화적 맥락이 뚜렷한 구석기 유적이 발견되면 한강 본류역 구석기 문화의 보다 구체적인 면모를 밝힐 수 있을 것으로 기대된다.
댐 붕괴흐름의 해석해(Ritter의 해)를 이용한 월파유속 분석
유용욱,이종인,김영택 한국수자원학회 2008 한국수자원학회논문집 Vol.41 No.7
본 연구는 수리실험으로 얻어진 권파에 의한 월파수괴의 유속을 댐붕괴흐름과 비교하여 거동의 유사성을 검토하였다. 댐붕괴흐름은 해석해가 간략하고 월파 거동과 유사함으로 인해 월파의 유속산정에 이용되어왔다. 월파는 일반적으로 많은 연행기포로 인해 기존의 유속측정기법을 적용하는데 제한을 받게 되므로, 본 실험에서는 기포나 기포조직모양을 이용한 기포영상유속계를 이용하여 월파 유속을 측정하였다. 실험결과로부터 월파의 유속단면을 검토하였고, 단면의 최대유속과 수심평 The present study examines similarity of behavior between an overtopping wave generated by a plunging wave and a dam-break flow through hydraulic model tests. The dam-break flow has been employed to estimate the overtopping effect on the basis of the dam