• 한국환경과학회지
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• 제20권5호
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• pp.555-564
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• 2011

This study examines the potential restoration of abandoned channels of the Mangyeong River in South Korea. To analyze the morphological changes and equilibrium conditions, a flow duration analysis was performed to obtain the discharge of 255 m3/s with a recurrence interval of 1.5 year. It is a gravel-bed stream with a median bed diameter of 36 mm. The reach-averaged results using HEC-RAS showed that the top width is 244 m, the mean flow depth is 1.11 m, the width/depth ratio is very high at 277, the channel velocity is 1.18 m/s, and the Froude number is also high at 0.42. The hydraulic parameters vary in the vicinity of the three sills which control the bed elevation. The total sediment load is 6,500 tons per day and the equivalent sediment concentration is 240 mg/l. The Engelund-Hansen method was closer to the field measurements than any other method. The bed material coarser than 33 mm will not move. The methods of Julien-Wargadalam and Lacey gave an equilibrium channel width of 83 m and 77 m respectively, which demonstrates that the Mangyeong River is currently very wide and shallow. The planform geometry for the Mangyeong River is definitely straight with a sinuosity as low as 1.03. The thalweg and mean bed elevation profiles were analyzed using field measurements in 1976, 1993 and 2009. The measured profiles indicated that the channel has degraded about 2 m since 1976. The coarse gravel material and large width-depth ratio increase the stability of the bed material in this reach.

• Geomechanics and Engineering
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• 제8권5호
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• pp.663-674
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• 2015

Many seismically vulnerable regions in India and worldwide are located on deep soil deposits which extend to several hundred meters of depth. It has been well recognized that the earthquake shaking is altered by geological conditions at the location of building. As seismic waves propagates through uppermost layers of soil and rock, these layers serve as filter and they can increase the duration and amplitude of earthquake motion within narrow frequency bands. The amplification of these waves is largely controlled by mechanical properties of these layers, which are function of their stiffness and damping. Stiffness and damping are further influenced by soil type and thickness. In the current study, an attempt has been made to study the seismic site response of deep soils. Three hypothetical homogeneous soil models (e.g., soft soil, medium soil and hard soil) lying on bedrock are considered. Depth of half space is varied from 30 m to 2,000 m in this study. Controlled synthetic motions are used as input base motion. One dimensional equivalent linear ground response analyses are carried out using a computer package DEEPSOIL. Conventional approach of analysing up to 30 m depth has been found to be inadequate for deep soil sites. PGA values are observed to be higher for deeper soil profiles as compared to shallow soil profiles indicating that deeper soil profiles are more prone to liquefaction and other related seismic hazards under earthquake ground shaking. The study recommends to deal the deeper soil sections more carefully for estimating the amplification factors for seismic hazard assessment at the surface.

• Radiation Oncology Journal
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• 제7권1호
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• pp.101-112
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• 1989

The treatment planning and dosimetry of small fields for stereotactic radiosurgery with 10 MV x-ray isocentrically mounted linear accelerator is presented. Special consideration in this study was given to the variation of absorbed dose with field size, the central axis percent depth doses and the combined moving beam dose distribution. The collimator scatter correction factors of small fields $(1\times1\~3\times3cm^2)$ were measured with ion chamber at a target chamber distance of 300cm where the projected fields were larger than the polystyrene buildup caps and it was calibrated with the tissue equivalent solid state detectors of small size (TLD, PLD, ESR and semiconductors). The central axis percent depth doses for $1\timesl\;and\;3\times3cm^2$ fields could be derived with the same acuracy by interpolating between measured values for larger fields and calculated zero area data, and it was also calibrated with semiconductor detectors. The agreement between experimental and calculated data was found to be under $2\%$ within the fields. The three dimensional dose planning of stereotactic focusing irradiation on small size tumor regions was performed with dose planning computer system (Therac 2300) and was verified with film dosimetry. The more the number of strips and the wider the angle of arc rotation, the larger were the dose delivered on tumor and the less the dose to surrounding the normal tissues. The circular cone, we designed, improves the alignment, minimizes the penumbra of the beam and formats ball shape of treatment area without stellate patterns. These dosimetric techniques can provide adequate physics background for stereotactic radiosurgery with small radiation fields and 10MV x-ray beam.

• 수산해양기술연구
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• 제41권4호
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• pp.271-278
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• 2005

In order to study the catch situation of the octopus pot fishery in the coastal waters of Gangneung, catch quantities and weight per month and depth, the soaking time & loss of fishing gear were studied based on 62 fishing times (1 set consisted of 150 pots which is equivalent to 1 fishing time) over a period of 10 months from February to December 2003 using commercial fishing vessels and training ships. The monthly CPUE was generally high in the months of june - September, and during this period July showed the highest quantity (134g/pot, 19.21kg/haul). In consideration of the fact that octopus below the weight of 2kg is protected in foreign countries, the majority of the catch was small with 76% (486 octopuses) below 1kg. The octopus catch quantity was high in depth of more than 40m, and the average catch number per set of pots in depths of over 50m was the highest with 13 octopuses. CPUE(g/pot) was the highest at a depth of over 60m recording 101. In terms of catch quantity per soaking time (4-18 days) the highest was on the 7th day, and 13-18 days also recorded high catches, and this suggests the possibility of ghost - fishing with the loss of fishing gear. Loss of fishing gear was the highest in terms of loss frequency and amount at depths of 20-30m. Consequently, it seems that octopus pot fishing at depths of more than 30m would relieve friction with other types of fishing and increase fishing efficiency.

• Journal of Periodontal and Implant Science
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• 제40권5호
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• pp.220-226
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• 2010

Purpose: This study was performed to evaluate the periodontal wound healing effect of particulate equine bone mineral on canine alveolar bone defects. Methods: Twelve adult male beagle dogs were used as study subjects. The mandibular second and fourth premolars were extracted prior to the experimental surgery, and the extraction sites were allowed to heal for 8 weeks. After periodontal probing, two-walled defects were created at the mesial and distal sides of the mandibular third premolars bilaterally, and the defects were filled with equine particulate bone with collagen membrane or bovine particulate bone with collagen membrane, or collagen membrane alone. The defects without any treatment served as negative controls. After probing depth measurement, animals were sacrificed at 10, 16, and 24 post-surgery weeks for micro-computed tomographic and histomorphometric analysis. Results: The equine particulate bone-inserted group showed significantly decreased values of probing depth and first bone contact compared to the negative control and collagen membrane alone groups at weeks 10, 16, and 24 (P<0.05). There were no significant differences in the new cementum length, newly-formed bone area, or newly-formed bone volume between equine particulate bone- and bovine particulate bone-inserted groups, both of which showed significantly increased values compared to the negative control and collagen membrane alone groups (P<0.05). Conclusions: Equine particulate bone showed significant differences in probing depth, first bone contact, new cementum length, newly formed bone area, and bone volume fraction values when compared to the negative control and collagen membrane alone groups. There were no significant differences between equine and bovine particulate bone substitutes in these parameters; therefore, we can conclude that equine particulate bone is equivalent to bovine bone for periodontal regeneration.

• 터널과지하공간
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• 제26권3호
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• pp.181-191
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• 2016

이산화탄소 지중저장 시 암석 내부의 공극구조는 지층 내 이산화탄소의 거동에 큰 영향을 미친다. 본 연구에서는 포항분지 영일만 지역에서 채취한 시추코어를 대상으로 X선 단층촬영 기법을 이용해 3차원 영상을 취득하고, 그 내부에 대한 정량적인 분석을 실시하였다. 세 가지 목표지층인 심도 740 m, 780 m, 810 m 부근에서 채취한 사암 시료(T1, T2, T3)의 공극률은 각각 25.22%, 23.97%, 6.28%로 분석되었다. 등가직경, 공극 부피, 공극 표면적, 국부두께 분석을 수행하였으며, 그 결과 T1, T2 시료가 T3 시료에 비해 이산화탄소 지중저장에 더 적합한 것으로 나타났다. 본 연구의 분석 결과는 이산화탄소 주입 조건 결정, 지층 내 이산화탄소 유동 해석 등에 기초자료로 이용될 수 있을 것으로 기대된다.

• 한국안광학회지
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• 제16권3호
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• pp.293-297
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• 2011

목적: 본 연구는 고령의 성인을 대상으로 굴절이상과 안광학 성분들 사이의 연관성을 알아보고자 하였다. 방법: 안과적 수술을 받지 않은 고령의 95명을 대상으로 굴절이상과 각막곡률반경, 각막굴절력, 안축장, 전방깊이, 수정체 두께를 측정하고 분석하였다. 결과: 안축장(AL)/각막곡률반경(CR) 비와 각막굴절력, 안축장, 전방깊이는 양의 상관관계를 보였고(r=0.510, r=0.439 r=0.411), AL/CR 비와 각막곡률반경과는 음의 상관관계를 나타냈다(r = -0.516). 각 막굴절력과 안축장 사이에서 가장 높은 연관성(r = -0.545, p=0.000)을 보였으며 굴절이상과 AL/CR 비는 음의 상관관계로 분석되었다(r = -0.359). 결론: 눈의 굴절이상을 진단하는데 AL/CR 비가 고령의 성인에서 중요한 지표자료임을 알 수 있었다.

• Journal of Radiation Protection and Research
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• 제21권4호
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• pp.263-271
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• 1996

ANSI N13.32에서는 선량제의 방향에 따른 반응도가 성능시험의 합격판정의 범주는 아니지만 이에 관한 연구를 요구하고 있다. 본 연구에서는 ANSI N13.32의 말단팬텀 즉, 손가락과 손목팬텀내의 $7mg/cm^2$ 깊이에서 MCNP 코드를 사용하여 단일에너지를 가진 광자 및 ISO narrow X-선 빔에 대하여 선량당량환산인자와 방향의존성인자를 도출하였다. X-선 빔에 대하여는 이들 데이터를 B. Grosswent의 연구 결과와 비교하였다. 그 결과 선량당량환산인자는 낮은 에너지 영역에서 최대 7%를 그리고 다른 에너지 영역에서는 2% 이내였으며, 방향의존성인자는 최대 3% 정도로 잘 일치하였다. 또한 60keV 이하의 낮은 에너지 영역에서 발생된 방향의존성인자는 손가락 팬텀의 경우에 주축을 따라 수평회전각이 증가할수록 감소하지만 그 에너지 영역 이상에서 $90^{\circ}$까지는 증가하고 있음을 알 수 있었다.

• Journal of Communications and Networks
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• 제5권4호
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• pp.309-318
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• 2003

This paper presents an in-depth study of a UWB indoor radio channel between 1 and 9 GHz, which was used for the subsequent development of a new statistical UWB multipath channel model, focusing on short range indoor scenarios. The channel sounding process was carried out covering different indoor environments, such as laboratories, halls or corridors. A combination of new and traditional parameters has been used to accurately model the channel impulse response in order to perform a precise temporal estimation of the received pulse shape. This model is designed specifically for UWB digital systems, where the received pulse is correlated with an estimated replica of itself. The precision of the model has been verified through the comparison with measured data from equivalent scenarios and cases, and highly satisfactory results were obtained.

• 천문학회보
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• 제40권1호
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• pp.75.3-75.3
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• 2015

Large area infrared surveys are often accompanied with follow-up optical spectroscopic surveys that has a significant legacy value even for other areas of research. Using these spectral database, we have performed a search for MgII absorption lines in the optical spectrum of background quasar. Over the ~4deg2 of AKARI North Ecliptic Pole survey field and Spitzer First Look Survey field, 18 and 16 MgII absorber systems are identified respectively. The redshift range for the background quasars was 1.0<$z_{qso}$<3.4, while the redshift range for the absorber was 0.6<$z_{abs}$<1.6. Galaxies responsible for MgII absorptions are identified in the deep optical images (CFHT r-band), yet the identification still remains ambiguous for 60% of the systems due to the limited image depth and the source crowdedness. The impact parameter ranges 20-60kpc, and the rest-frame equivalent width of MgII absorption ranges $0.7-4{\AA}$. The most critical part in the identification of MgII absorber galaxies is the existence of deep optical images in addition to the high S/N quasar spectrum with R>3000.