• The korean journal of orthodontics
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• v.19 no.1 s.27
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• pp.77-93
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• 1989

The purpose of the present study were to disclose whether the depth of the mandibular antegonial notch can be used as an indicator of mandibular growth potential. The patients composed of 76 samples and were classified following 3 groups, based on the depth of mandibular antegonial notch : Deep notch group (more than 3mm), Neutral notch group (1-3mm), Shallow notch group (less than 1mm). For each case, the first lateral cephalograms were taken prior to the start of treatment and the second films 3-4 years after. The results were as follows; 1. Deep notch group had a shorter corpus, less ramus height and greater genial angle than did Shallow notch group. 2. Deep notch group had a more retrusive mandibular position than Shallow notch group. 3. Deep notch group had longer total anterior facial height and longer anterior lower facial height group. 4. Deep notch group grow vertical clockwise growth pattern, while Shallow notch group grow horizontal counterclockwise growth pattern. 5. Deep notch group had less mandibular growth than Shallow notch group during observation period.

• Ocean Systems Engineering
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• v.12 no.4
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• pp.439-459
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• 2022

This paper describes experimental studies of impact pressure generated by breaking regular waves in shallow water on a vertical cylinder. Experimental work was carried out in a shallow water flume using a 1:30 - scale model of a vertical rigid circular hollow cylinder with a diameter 0.2 m. This represents a monopile for shallow water offshore wind turbines, subjected to depth induced breaking regular waves of frequencies of 0.8 Hz. The experimental setup included a 1 in 10 sloping bed followed by horizontal bed with a constant 0.8 m water depth. To determine the breaking characteristics, plunging breaking waves were generated. Free surface elevations were recorded at different locations between the wave paddle to the cylinder. Wave impact pressures on the cylinder at a number of elevations along its height were measured under breaking regular waves. The depth-induced wave breaking characteristics, impact pressures, and wave run-up during impact for various cylinder locations are presented and discussed.

• Current Research on Agriculture and Life Sciences
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• v.18
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• pp.33-42
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• 2000

A field case study was performed to investigate the effect of shallow ponding in paddy field on irrigation water requirement of direct seeded rice. In addition, an economic analysis was made to see the effect of no-till direct seeded rice on cost reduction. A field study was performed at a 2.1ha paddy field in Kimjae city, Chonbuk province from 1991 to 1999. Various direct seeding methods such as dryland seeding, wetland seeding, and no-till wetland seeding were introduced. Then, cost reductions due to the direct seeding and no-till were calculated. In addition, to investigate the effect of shallow ponding on irrigation water requirement, field measurements such as irrigation water volume, drainage water volume, rainfall depth, and ponding depth, were made at a 40a plot within the same area in 1988 and 1990. The results of the shallow ponding study showed that the irrigation water depth, rainfall, and the drainage depth were 379mm, 458mm, and 448mm in 1988 growing season, and 274mm, 819mm, and 736mm in 1990, respectively. The shallow ponding irrigation method saved irrigation water by about 20% with higher yield compared with the traditional method. The economic analysis showed that won \640,000 per ha can be saved by direct seeding due to no nursery cost, and \1,220,000 per ha due to no-till and no nursery cost. The yields ranged 540 to 640 kg per 10a during the study period with an average of 590kg per 10a. If these cropping techniques with no-till direct seeding and shallow ponding depth for rice cropping prove to be advantageous with further study, they can be adopted for the most of the paddy fields in Korea.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2002.10a
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• pp.477-480
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• 2002

The purpose of this study Was to investigate the effects of ponding depth treatment on water balance in paddy fields. Three ponding depth treatment, shallow, traditional, and deep were used. Daily values of rainfall amount, ponding depth, irrigation water, drainage water, evapotranspiration, and infiltration were measureed in the field. The results showed that irrigation water depths were 198mm, 195mm, and 355mm in shallow, traditional, and deep ponding, respectively. The three treatments did not show any statistical difference in growth and yields. Shallow depth treatment showed the largest yield.

• Journal of computational fluids engineering
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• v.20 no.4
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• pp.93-101
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• 2015

This paper provides numerical results of the simulation for the flow around the hull and the propeller of KCS model ship advancing in shallow water conditions. A finite volume method is used to solve the unsteady Reynolds averaged Navier-Stokes(RANS) equations, where the wave-making problem is solved by using a volume-of-fluid(VOF) method. The wave formed near the hull surface in shallow water conditions shows a deep trough dominant pattern that causes the loss of buoyancy followed by hull squat. The flow past the hull increases as the depth of water decreases. However, the axial flow velocity around the stern shows a reduction in magnitude by the effect of shallow water accompanied by the hull-propeller interaction. As a results, the thrust and torque coefficient increase about 8.3% and 6.2%, respectively for a depth of h/T=3.0 corresponding to a depth Froude number of $F_h=0.693$. The resistance coefficient increases about 11.6% at this Froude number condition.

• Journal of the Society of Naval Architects of Korea
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• v.59 no.6
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• pp.345-354
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• 2022

It is easy for a ship passing through confined waters to be exposed in dangers of collisions and grounding due to different hydrodynamic responses. Since marine accidents can cause significant impacts on environments, global economy, and human lives, it is necessary to study the effect of shallow water on hydrodynamic performance of a ship. In this paper, the effect of water depth on resistance performance was investigated using CFD analysis as an initial study for improving navigational safety of a large container ship under confined waters. After a CFD set-up for deep water condition was validated and verified by comparing CFD analysis with model test results, CFD calculations according to ship speed and water depth were conducted. The features were investigated in terms of tendency and physical knowledge related to resistance performance. The increase of resistance due to shallow water effect was reviewed with empirical formula suggested from SWABE JIP. Speed loss due to shallow water effect was additionally reviewed from estimated delivered power according to ship speed and water depth.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.171-171
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• 2000

차세대 반도체 제조에서 Design rule 이 점점 더 shrink 됨에 따라 shallow junction 분석의 중요성이 강조되고 있다. 이러한 shallow junction에 대한 분석방법중의 하나인 SIMS 분석에 있어서 depth resolution을 향상시키는 것이 중요하며, 일차이온의 에너지를 낮추어 줌으로써 이러한 효과를 달성할 수 있다. 그러나 최근의 연구에 따르면 O2+를 이용한 low energy SIMS 분석 시에 non-zero incidence angle로 분석할 경우 surface roughness가 발생한다는 사실이 보고되었으며, surface roughness를 줄이고 분석 초기의 transient region을 줄이기 위한 방법으로 oxygen flooding을 사용하는 경우 특정 각도에서 surface roughness가 여전히 존재할 뿐 아니라 분석 초기영역에서의 sputter rate이 변화하는 문제가 있음이 보고된바 있다. 본 연구에서는 2keV O2+ 일차이온을 이용하여 oxygen flooding 하에서 기존 조건인 60도 incidence로 분석하는 방법의 문제점을 파악하고 incidence angle을 45도로 바꾸어 분석하는 방법을 검토하였다. 그 결과 기존의 분석조건에서는 분석도중 표면부근에서 sputter rate이 변화하고 surface roughness가 증가하는 것을 확인하였고, 그로 인하여 oxygen flooding을 하지 않은 경우와 많은 차이가 발생하는 것을 발견하였다. Incidence angle을 45도로 바꾼 결과 이러한 문제가 해결되는 것을 확인하였으며, 특히 GaAs $\delta$layer 분석을 통하여 이 분석조건이 기존의 분석조건에 비하여 획기적으로 향상되는 것을 확인 할 수 있었다. 또한 여러 가지 shallow junction 분석을 통하여 이 분석방법이 상당히 신뢰성이 있음을 알 수 있었다. 그러나 여전히 oxygen flooding을 하지 않은 경우에 비하여 다소간의 차이가 있는 것이 발견되었는데, 이는 주로 표면에 잔존하는 산화막에 의한 효과와 oxygen flooding에서 보다 더 depth resolution이 좋음으로 인하여 발생하는 것으로 추정되었으며 그 밖에 다른 가능성도 제기되었다. 따라서 이 방법은 표면 산화막이 거의 없는 시료에 대하여 적용한다면 oxygen flooding을 하지 않은 경웨 비하여 transient region이 거의 없고 junction depth를 보다 신뢰성 있게 측정할 수 잇는 장점이 있는 것으로 판단되었다. As, P의 저 에너지이온 주입시료에 대해 이 분석방법을 적용할 경우 C+s 분석법에 비하여 depth resolution을 비교적 쉽게 향상시킬 수 있었고, oxygen follding을 쓰지 않은 경우에 비해서는 검출한도를 약 100배 정도 향상시킬 수 있었다. 그러나 2.5keV Cs+ 분석법에 비하면 아직 depth resolution이 불충분하여 실제로 shallow As 분석에 적용하기에는 다소 문제점이 있었다.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.3
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• pp.409-420
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• 2021

The decrease in under keel clearance (UKC) due to the increase of draft that occurs during advancing and turning of very large vessels of different types was analyzed based on computational fluid dynamics (CFD). The trim change in the Duisburg test case (DTC) container ship was much smaller than that of the KRISO very large crude oil carrier 2 (KVLCC2). The sinkage of both ships increased gradually as the water depth became shallower. The amount of sinkage change in DTC was greater than that in KVLCC2. The maximum heel angle was much larger for DTC than for KVLCC2. Both ships showed outward heel angles up to medium-deep water. However, when the water depth became shallow, an inward heel was generated by the shallow water effect. The inward heel increased rapidly in very shallow water. For DTC, the reduction ratio was very large at very shallow water. DTC appeared to be larger than KVLCC2 in terms of the decreased UKC because of shallow water in advancing and turning. In this study, a new result was derived showing that a ship turning in a steady state due to the influence of shallow water can incline inward, which is the turning direction.

• Journal of the Korean earth science society
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• v.37 no.5
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• pp.277-285
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• 2016

We introduce a depth scaling strategy to improve the accuracy of frequency-domain elastic full waveform inversion (FWI) using the new pseudo-Hessian matrix for seismic data without low-frequency components. The depth scaling strategy is based on the fact that the damping factor in the Levenberg-Marquardt method controls the energy concentration in the gradient. In other words, a large damping factor makes the Levenberg-Marquardt method similar to the steepest-descent method, by which shallow structures are mainly recovered. With a small damping factor, the Levenberg-Marquardt method becomes similar to the Gauss-Newton methods by which we can resolve deep structures as well as shallow structures. In our depth scaling strategy, a large damping factor is used in the early stage and then decreases automatically with the trend of error as the iteration goes on. With the depth scaling strategy, we can gradually move the parameter-searching region from shallow to deep parts. This flexible damping factor plays a role in retarding the model parameter update for shallow parts and mainly inverting deeper parts in the later stage of inversion. By doing so, we can improve deep parts in inversion results. The depth scaling strategy is applied to synthetic data without lowfrequency components for a modified version of the SEG/EAGE overthrust model. Numerical examples show that the flexible damping factor yields better results than the constant damping factor when reliable low-frequency components are missing.

• Journal of the Korean Geotechnical Society
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• v.30 no.6
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• pp.41-49
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• 2014

Intensive rainfall causes frequent slope failures at the shallow depths of slopes. Because soil layers at shallow depths of slopes usually become dense, and its permeability and soil strength vary according to depth, forensic studies and stability analyses of shallow slope failure need to consider the depth-variant soil properties. In this study, the effect of depth-variant soil properties on surface failure of slopes during rain infiltration is investigated using numerical analysis. Three different cases considering depth-variant soil properties were conducted and the results were compared. For the analysis, undisturbed soils at three different depths were sampled at actual slope failure sites and the properties including strength and permeability characteristics at each depth were obtained. Stability analysis and seepage analysis were conducted using actual rainfall records. The comparison of the results shows that analysis could lead to an erroneous conclusion according to the way of considering depth-variant soil properties. The case in which depth-variant soil properties were considered predicted similar failure times and failure shapes with the actual failure. Therefore it is recommended that the depth-variant soil properties should be considered for the analysis of shallow slope failure during rain infiltration.