• Restorative Dentistry and Endodontics
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• 제12권1호
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• pp.65-76
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• 1986

Carious dentin can be classified, on the basis of their clinical characteristics, into three groups; sound, sclerotic and active carious dentin. Active carious dentin differs from sclerotic dentin by its abscence of variable bacteria within tubles and amount of chemical content. But the apatite molecules of active carious dentin are not fully studied. The purpose of this study was to observed the physico-chemical characteristics of deep carious dentin. The samples of sound, sclerotic and active carious dentin were obtained respectively from 300 freshly extracted carious teeth. Bacterial-rich zone of superficial soft dentin layer was removed with hand instruments from all samples in advance. The samples were powdered and sieved (200 mesh) before analyses. Identification and estimation of the crystallinity of the samples were carried with X-ray diffraction and infrared absorption analyses. Measurements were made on a Rigaku Denki (Rigaku, geiger flex III, Japan) X-ray diffractometer with Cu-target at 30 Kv, 30 mA and are traced on a monochromatic tracer. Infrared absorption analysis was made on FT-IR spectrophometer (Nicolet Instrument Co.) using KBr pellets containing the samples and was recorded on data process (Model IR-80. Nicolet Instrument, Co). The following conclusions were as follows; 1. The nature of the main inorganic structure of sound, sclerotic and active carious dentin proved to be hydroxyapatite. 2. It was difficult to determine the identification due to their crystallinity of sound, sclerotic and active carious dentin. But sound dentin was the highest in crystallinity among them. 3. The magnesium whitlockite was to be found in active carious dentin, but not in sound and sclerotic dentin. 4. The carbonate content was highest in sound dentin, but the lowest was in active carious dentin.

• 한국해양공학회지
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• 제26권6호
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• pp.7-13
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• 2012

This paper presents a numerical study of the wave loads acting on offshore structures using a Cartesian-grid-based flow simulation method. Finite volume discretization with a volume-of-fluid (VOF) method is adopted to solve two-phase Navier-Stokes equations. Among the many variations of the VOF method, the CICSAM scheme is applied. The body boundary conditions are satisfied using a porosity function, and wave generation is carried out by using transient (wave or damping) zone approaches. In order to validate the present numerical method, three different basic offshore structures, including a sphere, Pinkster barge, and Wigley model, are numerically investigated. First, diffraction and radiation problems are solved using the present numerical method. The wave exciting and drift forces from the diffraction problems are compared with potential-based solutions. The added mass and wave damping forces from the radiation problems are also compared with the potential results. Next, the wave-induced motion responses of the structures are calculated and compared with the existing experimental data. The comparison results are fairly good, showing the validity of the present numerical method.

• Industrial Engineering and Management Systems
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• 제15권4호
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• pp.396-402
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• 2016

In this study, hydraulic analysis of water-supply networks in Marivan was performed by modeling. WATERGEMS was used for modeling and it was calibrated using existing rules and regulations. The purpose of this research is modeling urban water network and its analysis based on hydraulic criteria and meeting pressure conditions at the nodes and complying the economic speed. To achieve this goal, first the pipelines of city streets was designed in AutoCAD on a map of the city. It should be mentioned that it was tried to prevent from creating additional loops in the network and the optimal network was designed by a combination of annular and branch loops. In the next step, the pipes were called in WATERGEMS and then we continue the operation by the allocation of elevation digits to the pipes. Since the topography of this city is very specific and unique, the number of pressure zones was increased. Three zones created only covers about 20% of the population in the city. In this dissertation, the design was performed on the city's main zone with the largest density in the Figures 1,320-1,340. In the next step, the network triangulation was conducted. Finally, the Debiw as allocated based on the triangulation conducted and considering the density of the city for year of horizon. Ultimately, the network of Marivan was designed and calibrated according to hydraulic criteria and pressure zoning. The output of this model can be used in water-supply projects, improvement and reform of the existing net-work in the city, and various other studies. Numerous and various graphs obtained in different parts of a network modelled can be used in the analysis of critical situation, leakage.

• 한국해양공학회지
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• 제28권3호
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• pp.236-244
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• 2014

This study considered a seagrass habitat in order to analyze the characteristics of a marine environment of seagrass located in the Seomjin river estuary, through an analysis of the distribution of the water depth, field observation, and three-dimensional numerical experiments using an EFDC model. The seagrass habitat was usually distributed at D.L(-) 0.5~0.0 m, and was hardly seen in the intertidal zone higher than that range. The distribution of the water temperature was within the range of $7.0{\sim}23.2^{\circ}C$, and the seagrass was demonstrated to have a strong tolerance to changes in the water temperature. In addition, the salinity distribution was found to be 27.2~31.0 psu, with suspended solids of 32.1 mg/L, which were higher than the previous research results (Huh et al., 1998), implying that there may be a reduction in the amount of deposits caused by the suspended solids. As for the sedimentary facies, they were comprised of 62.7% sand, 19.1% silt, and 18.2% clay, indicating that the arenaceous was superior and the sedimentary facies were similar to that of Dadae Bay. According to a numerical experiment, the maximum tidal current was 75 cm/s, while the tidal residual current was 10 cm/s, confirming that it sufficiently adapted to strong tidal currents. The erosion and deposition are predicted to be less than 1.0 cm/year. Thus, it is judged that the resuspension of sediments due to tidal currents and the changes in sedimentary facies are insignificant.

• 한국군사과학기술학회지
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• 제22권6호
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• pp.745-753
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• 2019

Recently, with the development of long-range / high-altitude guided weapon system for defense against ballistic missile, test range and firing altitude for guided weapons are increasing. Due to the increase in the test range and the intercepting altitude, it is expected to increase the range of safety area required for the firing test. Comparing to the foreign countries which have many desert or non-residence, in the domestic circumstances where the population is concentrated and distributed, it is more important to predict the falling area and to set the safety area for safely carry out the long-range / high-altitude intercept test. In this paper, we consider the following three points. The first is the booster fall trajectory modeling, the second is the shroud fall trajectory modeling, and finally, the debris dispersion modeling for the missile intercept. Especially, the AUTODYN model was used to predict debris falling area which produced in the high-speed guided missile intercepting test.

• 한국수자원학회논문집
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• 제35권3호
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• pp.295-306
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• 2002

지표하부에 이중 저류체계를 고려해주는 수정 TOPMODEL을 일반화된 지표하 투수량계수 감소함수와 연결시켰으며, 대공극으로의 수직배수 효과, 지표저류 효과, 토양층 내에서의 상대 저류 부족량에 대한 영향을 검토하기 위해 세가지 형태의 지하수 충전함수를 도입하였다. 이러한 접근은 사면 수문학에 대한 30가지 형태의 모형구조를 제공한다. 개발된 모형들은 설마천 유역의 여러 강우사상에 적용되었다. Monte-carlo 모의를 통한 수행결과는 지수함수적 투수량계수 감소형태가 설마천 유역의 물리적인 수문모의에 적절함을 제시하였고, 대공극 흐름을 표현해 주는 재충전 함수가 일반화시킨 수정 TOPMODEL의 예측적 향상에 기여하였다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2016년도 학술발표회
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• pp.65-65
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• 2016

위어나 낙차공 같은 수공구조물 직하류부에서는 다양한 형태의 흐름조건이 발생한다. 낙차공 하류에서 발생하는 독특한 흐름형태 중 하나는 정상파형도수를 갖는 파형흐름이다. 이 연구에서는강 등(2010)이 수리실험을 수행한 바 있는 계단형 위어 하류부에서의 형성되는 파형흐름을 3차원 수치해석을 수행한다. 위어 구조물 위를 통과하는 난류흐름을 해석하기 위해서 Spalart-Allamaras 1방정식 모형을 이용한 URANS 수치모의와 DES (detached eddy simulation)을 실시하였다. 위어 주변에서의 자유수면 변동, 파상도수, 자유수면에서의 와류 그리고 바닥부근에서의 재순환 영역의 형상과 크기, 선정된 종방향 위치들에서의 흐름방향유속분포 등의 항으로 수치해석결과를 실험값과 비교하여 수치모의의 적절성과 난류모델들의 성능을 평가한다.

• 지질공학
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• 제31권3호
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• pp.269-281
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• 2021

Land creeping is the imperceptibly slow, steady, downward movement o f slope-forming soil or rock. Because creep-related failures occur frequently on a large scale without notice, they can be hazardous to both property and human life. Korea Forest Service has operated the prevention and response system from land creeping which has been on the rise since 2018. We categorized and proposed three survey steps (e.g., preliminary, regional, detailed) for investigation of creeping susceptibility site with a focus on geophysical mapping of a selected test site, Yongheung-dong, Pohang, Korea. The combination of geophysical (dipole-dipole electrical resistivity tomography and reciprocal seismic refraction technique, well-logging), geotechnical studies (standard penetrating test, laboratory tests), field mapping (tension cracks, uplift, fault), and comprehensive interpretation of their results provided the reliable information of the subsurface structures including the failure surface. To further investigate the subsurface structure including the sliding zone, we performed high-resolution geophysical mapping in addition to the regional survey. High-resolution seismic velocity structures are employed for stability analysis because they provided more simplified layers of weathering rock, soft rock, and hard rock. Curved slip plane of the land creeping is effectively delineated with a shape of downslope sliding and upward pushing at the apex of high resistive bedrock in high-resolution electrical resistivity model with clay-mineral contents taken into account. Proposed survey steps and comprehensive interpretation schemes of the results from geological, geophysical, and geotechnical data should be effective for data sets collected in a similar environment to land-creeping susceptibility area.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2015년도 학술발표회
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• pp.53-53
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• 2015

Basin-scale motions in a stratified lake rely on interactions of spatially and temporally varying wind force, bathymetry, density variation, and earth's rotation. These motions provide a major driving force for vertical and horizontal mixing of inorganic and organic materials, dissolved oxygen, storm water and floating debris in stratified lakes. In Lake Tahoe, located between California and Nevada, USA, basin-scale circulations are obviously important because they are directly associated with the fate of the suspended particulate materials that degrade the clarity of the lake. A three-dimensional hydrodynamic model, ELCOM, was applied to Lake Tahoe to investigate the underlying mechanisms that determine the characteristics of basin-scale circulations. Numerical experiments were designed to examine the relative effects of various mechanisms responsible for the horizontal circulations for two different seasons, summer and winter. The unique double gyre, a cyclonic northern gyre and an anti-cyclonic southern gyre, occurred during the winter cooling season when wind stress curl, stratification, and Coriolis effect were all incorporated. The horizontal structure of the upwelling and downwelling formed due to basin-scale internal waves found to be closely related to the rotating direction of each gyre. In the summer, the spatially varying wind field and the Coriolis effect caused a dominant anti-cyclonic gyre to develop in the center of the lake. In the winter, a significant wind event excited internal waves, and a persistent (2 week long) cyclonic gyre formed near the upwelling zone. Mechanism of the persistent cyclonic gyre is explained as a geostrophic circulation ensued by balancing of the baroclinc pressure gradient (or baroclinic instability) and Coriolis effect. Topographic effect, examined by simulating a flat bathymetry with constant depth of 300m, was found to be significant during the winter cooling season but not as significant as the wind curl and baroclinic effects.

• The Plant Pathology Journal
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• 제39권4호
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• pp.335-350
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• 2023

Physoderma fungal species cause faba bean gall (FBG) which devastates faba bean (Vicia faba L.) in the Ethiopian highlands. In three regions (Amahara, Oromia, and Tigray), the relative importance, distribution, intensity, and association with factors affecting FBG damage were assessed for the 2019 (283 fields) and 2020 (716 fields) main cropping seasons. A logistic regression model was used to associate biophysical factors with FBG incidence and severity. Amhara region has the highest prevalence of FBG (95.7%), followed by Tigray (83.3%), and the Oromia region (54%). Maximum FBG incidence (78.1%) and severity (32.8%) were recorded from Amhara and Tigray areas, respectively. The chocolate spot was most prevalent in West Shewa, Finfinne Special Zone, and North Shewa of the Oromia region. Ascochyta blight was found prevalent in North Shewa, West Shewa, Southwest Shewa of Oromia, and the South Gondar of Amhara. Faba bean rust was detected in all zones except for the South Gonder and North Shewa, and root rot disease was detected in all zones except South Gonder, South Wollo, and North Shewa of Amahara. Crop growth stage, cropping system, altitude, weed density, and fungicide, were all found to affect the incidence and severity of the FBG. Podding and maturity stage, mono-cropping, altitude (>2,400), high weed density, and non-fungicide were found associated with increased disease intensities. However, crop rotation, low weed infestation, and fungicide usage were identified as potential management options to reduce FBG disease.