• 천문학회지
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• 제56권1호
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• pp.59-73
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• 2023

The second generation of stars in the globular clusters (GCs) of the Milky Way (MW) exhibit unusually high N, Na, or Al, compared to typical Galactic halo stars at similar metallicities. The halo field stars enhanced with such elements are believed to have originated in disrupted GCs or escaped from existing GCs. We identify such stars in the metallicity range -3.0 < [Fe/H] < 0.0 from a sample of ~36,800 giant stars observed in the Sloan Digital Sky Survey and Large Sky Area Multi-Object Fiber Spectroscopic Telescope survey, and present their dynamical properties. The N-rich population (NRP) and N-normal population (NNP) among our giant sample do not exhibit similarities in either in their metallicity distribution function (MDF) or dynamical properties. We find that, even though the MDF of the NRP looks similar to that of the MW's GCs in the range of [Fe/H] < -1.0, our analysis of the dynamical properties does not indicate similarities between them in the same metallicity range, implying that the escaped members from existing GCs may account for a small fraction of our N-rich stars, or the orbits of the present GCs have been altered by the dynamical friction of the MW. We also find a significant increase in the fraction of N-rich stars in the halo field in the very metal-poor (VMP; [Fe/H] < -2.0) regime, comprising up to ~20% of the fraction of the N-rich stars below [Fe/H] = -2.5, hinting that partially or fully destroyed VMP GCs may have in some degree contributed to the Galactic halo. A more detailed dynamical analysis of the NRP reveals that our sample of N-rich stars do not share a single common origin. Although a substantial fraction of the N-rich stars seem to originate from the GCs formed in situ, more than 60% of them are not associated with those of typical Galactic populations, but probably have extragalactic origins associated with Gaia Sausage/Enceladus, Sequoia, and Sagittarius dwarf galaxies, as well as with presently unrecognized progenitors.

• Journal of Animal Science and Technology
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• 제59권10호
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• pp.22.1-22.7
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• 2017

Background: Very limited information exists on the ruminal degradation kinetics of nutrients in garlic stalk. The present study aimed to survey the annual yield of garlic stalk in Korea and determine its feed-nutritive value for ruminants. Methods: In Experiment 1, garlic stalk was incubated in situ in the rumen of two Hanwoo steers ($360{\pm}15kg$ body weight) and removed after 12, 24, or 48 h to determine the ruminal degradation kinetics of DM and NDF. Rice straw was also included for comparison. In Experiment 2, In Experiment 2, six male Corriedale sheep were randomized to two dietary treatments to determine the apparent digestibility of nutrients in garlic stalk. Diets included a control ration without garlic stalk (60% concentrate mix +40% ryegrass) or a treatment ration (70% control diet +30% garlic stalk). Results: The Korean national yield of garlic stalk (sun-dried basis) in 2016 was estimated to be 31,910 tons, with the southern coastal regions producing the highest quantity. Compared with rice straw, garlic stalk had lower NDF, higher ADF, and greater effective degradabilities of DM and NDF, resulting in a greater TDN value (56.3%), which was higher than that obtained for rice straw (43.7%). Conclusion: These results provide basic information on the ruminal DM and NDF degradation kinetics of garlic stalk, which would be helpful for the efficient utilization of this by-product in ruminant diets

• Journal of Forest and Environmental Science
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• 제29권4호
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• pp.257-274
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• 2013

Ecological and ethnomedicinal survey of plants was conducted in one hundred and twenty homesteads in Mbala, Amuda, Umuaku, and Nneato communities of Nneochi Local Governement Area, Abia State-Nigeria. A total of ninety-one medicinal plant species belonging to seventy-eight genera and forty-eight families, used in the treatment of malaria, yellow fever, fibroid, hepatitis, convulsion, hypertension, diabetes, insomnia, ulcer, rashes, low sperm count, snake bite, among others, were documented. Plant remedies were prepared mostly as infusions or decoctions from different plant parts with mainly water, and palm wine/gin sometimes. The highest number of medicinal plant species (73) was recorded in Mbala, followed by Amuda (71), Umuaku (68) and Nneato (61). Medicinal plant species diversity was highest in Amuda (Simpson 1-D=0.9621;H=3.663), followed by Umuaku (Simpson 1-D=0.9481; H=3.471), Mbala (Simpson 1-D=0.9345; H=3.341), and Nneato (Simpson 1-D=0.9307; H=3.277), respectively. Similarity in medicinal plant species was highest between Umuaku and Nneato (76.71%), followed by Amuda and Umuaku (75.95%), Mbala and Amuda (71.43%), while Mbala and Nneato had the lowest similarity (59.52%). The results of the study showed that traditional medicine is pivotal in the treatment of ailments in the study area, and that the indigenous people of Nneochi have recognized the need to conserve medicinal plants of importance ex situ within homesteads due to threats from unsustainable exploitation and deforestation.

• Ocean and Polar Research
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• 제28권3호
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• pp.225-236
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• 2006

Seagrass meadows are considered as critical habitats for a wide variety of marine organisms in coastal and estuarine ecosystems. In many cases, studies on the spatial/temporal distribution of seagrass have depended on direct observations using SCUBA diving. As an alternative method fur studying seagrass distribution, an application of hydroacoustic technique has been assessed for mapping seagrass distribution in Dongdae Bay, on the south coast of Korea, in September 2005. Data were collected using high frequency transducer (420 kHz split-beam), which was installed with towed body system. The system was linked to DGPS to make goo-referenced data. Additionally, in situ seagrass distribution has been observed using underwater cameras and SCUBA diving at four stations in order to compare with acoustic data. Acoustic survey was conducted along 23 transects with 3-4 blot ship speed. Seagrass beds were vertically limited to depths less than 3.5m and seagrass height ranged between 55 and 90cm at the study sites. Dense seagmss beds were mainly found at the entrance of the bay and at a flat area around the center of the bay. Although the study area was a relatively small, the vertical and spatial distributions of the seagrass were highly variable with bathymetry and region. Considering dominant species, Zostera marina L., preliminary estimation of seagrass biomass with acoustic and direct sampling data was approximately $56.55g/m^2$, and total biomass of 104 tones (coefficient variation: 25.77%) was estimated at the study area. Hydroacoustic method provided valuable information to understand distribution pattern and to estimate seagrass biomass.

• 터널과지하공간
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• 제25권4호
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• pp.332-340
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• 2015

광산지역에서 발생하는 지반침하는 인명과 지표시설물에 막대한 피해를 초래할 우려가 있으므로 지반침하 발생지역에 대한 일련의 현장조사와 지반안정성 분석은 체계적으로 수행되어야 한다. 본 연구에서는 충청북도 청원군에 위치한 석회석 광산의 일부 지점에서 발생한 지반침하의 원인을 규명하기 위하여 현장조사와 지반안정성 분석을 수행하였다. 이를 위하여 조사지역 암반의 공학적 특성을 조사하고, 전기비저항 탐사를 통해 지표 부근 연약대의 분포양상을 파악하였으며, 이 결과들을 토대로 침하원인 규명을 위한 전산해석을 수행하였다. 해석결과, 본 광산지역에서 발생된 지반침하는 석회암층에서 발달된 용식공동에 의한 것으로 분석되었다.

• Structural Monitoring and Maintenance
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• 제1권1호
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• pp.131-157
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• 2014

Special track systems used to divert a train to other directions or other tracks are generally called 'railway turnout'. A traditional turnout system consists of steel rails, switches, crossings, steel plates, fasteners, screw spikes, timber bearers, ballast and formation. The wheel rail contact over the crossing transfer zone has a dip-like shape and can often cause detrimental impact loads on the railway track and its components. The large impact also emits disturbing noises (either impact or ground-borne noise) to railway neighbors. In a brown-field railway track where an existing aged infrastructure requires renewal or maintenance, some physical constraints and construction complexities may dominate the choice of track forms or certain components. With the difficulty to seek for high-quality timbers with dimensional stability, a methodology to replace aged timber bearers in harsh dynamic environments is to adopt an alternative material that could mimic responses and characteristics of timber in both static and dynamic loading conditions. A critical review has suggested an application of an alternative material called fibre-reinforced foamed urethane (FFU). The full-scale capacity design makes use of its comparable engineering characteristics to timber, high-impact attenuation, high damping property, and a longer service life. A field trial to investigate in-situ behaviours of a turnout grillage system using an alternative material, 'fibre-reinforced foamed urethane (FFU)' bearers, has been carried out at a complex turnout junction under heavy mixed traffics at Hornsby, New South Wales, Australia. The turnout junction was renewed using the FFU bearers altogether with new special track components. Influences of the FFU bearers on track geometry (recorded by track inspection vehicle 'AK Car'), track settlement (based on survey data), track dynamics, and acoustic characteristics have been measured. Operational train pass-by measurements have been analysed to evaluate the effectiveness of the replacement methodology. Comparative studies show that the use of FFU bearers generates higher rail and sleeper accelerations but the damping capacity of the FFU help suppress vibration transferring onto other track components. The survey data analysis suggests a small vertical settlement and negligible lateral movement of the turnout system. The static and dynamic behaviours of FFU bearers appear to equate that of natural timber but its service life is superior.

• 한국해양학회지:바다
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• 제12권1호
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• pp.43-49
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• 2007

원자력발전소 온배수 영향 조사 과정상 문제점을 평가하고 대안으로서 조사 표준 지침을 제시하였다. 관측이나 온배수 확산 모델링 단독으로 이루어진 지금까지의 방법으로는 시간에 따른 온배수에 의한 수온 분포의 변화를 정량적으로 파악하는데 한계가 있으므로, 관측과 온배수 확산 수치모델링의 상호 보완적인 조사를 병행하는 것이 바람직하다. 현장 관측은 원자력발전소 인근 해역의 모든 자연적 열원의 영향을 고려한 열수지 모형의 개념에 근거한 조사가 중요하며, 수치모델링의 결과를 기준 수온분포로서 활용하고자 할 경우에는 수치모델링에 의한 현상 재현이 통계적 유의수준에 도달한 경우에 한정하도록 하였다. 또한, 과거의 순환 및 확산 모델링의 문제점을 개선하기 위한 대안으로서 표준코드의 개발을 제안하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2006년도 추계 학술발표회
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• pp.66-75
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• 2006

As construction for road tunnel is increasing, various geotechnical conditions can be faced during the construction stage. Especially, if the tunnel is located in limestone area, many kinds of site investigations such as in-situ boring, electrical resistance survey, TSP(Tunnel Seismic Prediction) and etc., are conducted before and during the construction. By conducting these preliminary tests, location, size, and filling materials in limestone cavities can be approximately estimated. Once some cavities which can be harmful for tunnel safety are predicted, methods for ground reinforcement and tunnel excavation, corresponding those ground conditions, have to be established and verified by measurement data and numerical analysis. If necessary, invert lining should be also considered. In this paper, by studying some cases of tunnels constructed in limestone area, predicted problems during construction and rational countermeasures for those are presented.

• Geomechanics and Engineering
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• 제24권3호
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• pp.281-293
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• 2021

Uncertainties in geomechanical input parameters which mainly related to inappropriate data acquisition and estimation due to lack of sufficient calibration information, have led wellbore instability not yet to be fully understood or addressed. This paper demonstrates a workflow of employing Quantitative Risk Assessment technique, considering these uncertainties in terms of rock properties, pore pressure and in-situ stresses to makes it possible to survey not just the likelihood of accomplishing a desired level of wellbore stability at a specific mud pressure, but also the influence of the uncertainty in each input parameter on the wellbore stability. This probabilistic methodology in conjunction with Monte Carlo numerical modeling techniques was applied to a case study of a well. The response surfaces analysis provides a measure of the effects of uncertainties in each input parameter on the predicted mud pressure from three widely used failure criteria, thereby provides a key measurement for data acquisition in the future wells to reduce the uncertainty. The results pointed out that the mud pressure is tremendously sensitive to UCS and SHmax which emphasize the significance of reliable determinations of these two parameters for safe drilling. On the other hand, the predicted safe mud window from Mogi-Coulomb is the widest while the Hoek-Brown is the narrowest and comparing the anticipated collapse failures from the failure criteria and breakouts observations from caliper data, indicates that Hoek-Brown overestimate the minimum mud weight to avoid breakouts while Mogi-Coulomb criterion give better forecast according to real observations.

• 대한공간정보학회지
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• 제12권4호
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• pp.13-19
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• 2004

현재까지 경지정리 조사설계를 위한 토양조사결과 처리, 토양도 제작 분석 및 그에 따른 적절한 건설기계 선정은 모두 수작업에 의해 이루어져 왔다. 본 연구에서는 지리정보시스템을 이용하여 이러한 작업을 전산화하였다. 다양한 토양 분포 양상을 띠는 산간지역경지정리 조사설계 지구의 현장조사 및 실내분석 시험치에 대한 자료를 수집하여 기본도와 주제도를 작성하고, 데이터베이스를 구축하였다. 이를 분석하여 대상지역의 경지정리시 사용되는 적절한 건설기계 선정방안을 제시하고 기존의 수작업 내용과 비교 검증하였다.