• Journal of the Korean Geotechnical Society
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• v.15 no.6
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• pp.71-86
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• 1999

The displacements of soil nailed wall and the nail tensile force for 11 soil nailing sites were investigated by using measurements obtained from inclinometer and strain gauge. The maximum horizontal displacement which occurred between 5% and 15% of the final excavation depth was found to be below 0.3% and 0.2% of excavation depth for well and poorly constructed sites. It was also found that the maximum horizontal displacements for 0.4%, 0.3% and 0.2% of excavation depth occurred when the ratios of nail length to final excavation depth were 0.5, 0.5~0.6 and 0.6~0.7. But the maximum horizontal displacement increased by 0.3% of excavation depth when the ratio was above 0.7. This was probably due to the shallow excavation depth and the deep soil stratum. The non-dimensional maximum tensile force of nail, K, from ground surface to $(0.6H_f)$ of the final excavation depth was less than 0.8 and decreased linearly between $(0.6H_f)$ and the final excavation depth. Also, the maximum tensile force was found to reach up to 60% of the ultimate tensile force at final excavation.

• Journal of the Korean GEO-environmental Society
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• v.15 no.7
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• pp.23-30
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• 2014

This paper deals with the characteristics of deformation of the underground corrugated steel plate culverts constructed in the areas where the minimum depth of within 1.5 m soil cover is not secured in the bottom of highways. The underground corrugated steel plate culverts at shallow depth are often designed and constructed with the consideration of the minimum depth of soil cover according to the design standards, which was made in order to minimize any deformation. Additionally, if under unfavorable conditions, slabs are set up for stress relaxation to disperse and minimize the weight of loads transferred to the corrugated steel plate culverts. Nevertheless, if the underground corrugated steel plate culverts are built in areas where the minimum depth of soil cover inevitably cannot be secured, there may occur some deformation. In this paper, a research was carried out to identify the characteristics of deformation in areas where the minimum depth of soil cover is not secured. The result shows that there existed the deterioration of pavement and in its smoothness around the corners of slabs for stress relaxation. To this end, this paper studied the structural stability of the underground corrugated steel plate culverts established in the areas with no minimum depth of soil cover secured, with the consideration of causes and solutions of pavement deterioration.

• Journal of Korea Water Resources Association
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• v.47 no.11
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• pp.1077-1086
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• 2014

The flood wave generated due to dam break is affected by initial depth upstream since it is related with hydraulic characteristics propagating downstream, and flow resistance stress has influence on the celerity, travel distance, and approaching depth of shock wave in implementing numerical simulation. In this study, a shallow water flow model employing SU/PG scheme was developed and verified by analytic solutions; propagation characteristics of dam break according to flow resistance and initial depth were analyzed. When bottom frictional stress was applied, the flow depth was relatively higher while the travel distance of shock wave was shorter. In the case of Coulomb stress, the flow velocity behind the location of dam break became lower compared with other cases, and showed values between no stress and turbulent stress at the reach of shock wave. The value of Froude number obtained by no frictional stress at the discontinuous boundary was the closest to 1.0 regardless of initial depth. The adaption of Coulomb stress gave more appropriate results compared with turbulent stress at low initial depth. However, as the initial depth became increased, the dominance of flow resistance terms was weakened and the opposite result was observed.

• Journal of Periodontal and Implant Science
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• v.29 no.4
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• pp.893-914
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• 1999

Tooth mobility may be the decisive factor that determines whether dental treatment of any kind is undertaken. Although tooth mobility in isolation says little in itself, the finding of increased tooth mobility is of both diagnostic and prognostic importance. Only the detection of an increase or decrease in mobility makes an evaluation possible. Thus prior to treatment, we must understand the pathologic process causing the observed the tooth mobility and decide whether the pattern and degree of observed tooth mobility is reversible or irreversible. And then it must be decided whether retention and treatment or extraction and replacement. The purpose of this study was to compare tooth mobility at different time period during root planing and flap operation and to relate changes in mobility to each treatment method. Twenty-one patients (287 teeth) with chronic adult periodontitis were treated with root planing(control group) and flap operation(experimental group), and each group was divided 3 subgroups based upon initial probing pocket depth (1-3mm, 4-6mm, 7mm and more). Tooth mobility was measured with $Periotest^{(R)}$ at the day of operation, 4 days, 1 week, 2 weeks, 3 weeks, 4 weeks, 8 weeks, 12 weeks after each treatment. Tooth mobility, attachment loss, radiographic bone loss, and bleeding on probing were measured at the day of operation, 4 weeks, 8 weeks and 12 weeks after treatment. 1. In group initial probing depth was 1-3mm, tooth mobility had no significant difference after root planing and flap operation. 2 . In group initial probing depth was 4-6mm, 7mm and more, tooth mobility had decreased in 12 weeks after root planing(p<0.01). And the mobility had increased after flap operation(p<0.01) and was at peak in 1 week, and decreased at initial level in 4 weeks, below the initial level in 12 weeks(p<0.01). 3. In 1 week, significant difference in tooth mobility between control and experimental group was found(p<0.01) but, in 12 weeks no difference between two groups was found. 4. Change of immediate tooth mobility after treatment was more larger in deep pocket than in shallow one. In group with the same probing pocket depth, the change of tooth mobility in molar group was greater than that of premolar group. 5. Tooth mobility before treatment was more strongly correlated with radiographic bone loss (r=0.5325) than probing depth, attachment loss and bleeding on probing, in 12 weeks after treatment, was more strongly correlated with attachment loss($r^2$=0.4761) than probing depth and bleeding on probing. Evaluation of the treatment effect and the prognosis after root planing and flap operation were meaningful on tooth initial probing depth 4mm and more. After flap operation, evaluation of the prognosis should be performed at least in 4 weeks and in 12 weeks after treatment, no difference in tooth mobility between two groups was observed. Radiographic bone loss and attachment loss were good clinical indicators to evaluate tooth mobility.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.39 no.3
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• pp.205-210
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• 1994

This experiment was conducted to investigate of soil hardening degree before sowing, furrow depth at sowing and flooding time after sowing at furrowing in flooded rice paddy field that many people have an interest in as direct sowing method most recently. As hardening period was increased, the percentage of seedling stand and seed floating at flooding were increased slightly, while buried depth of stem at maximum tillering stage and cone penetration depth were decreased, respectively. Therefore, optimum degree of soil hardening was about 3 days after draining, at this time, cone penetration degree was about 6~7cm. According to furrow depth was more and more deep, buried depth of stem was increased gradually, but percentage of seedling stand was decreased considerbly. Also, root distribution ratio on surpace horizon and lodging degree were increased gradually according to furrow depth become more and more shallow. As flooding time after sowing was late, percentage of seedling stand and panicle number per $m^2$ were decreased slightly. These results apparently indicated that sowing after 3 days hardening when cone penetration degree was 6~7cm, furrow depth 3~4cm degree and flooding time just after sowing the best method to good establish of seedling stand.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.39 no.4
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• pp.326-336
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• 2003

In order to modify the construction of gizzard shad coastal purse seine net with possible to the laborsaving of fishing operation in the coastal small fishing vessels, the model experiments were carried out on the model nets for several conventional nets using in the field and the experimental nets was manufactured as 1/100 and 1/60 of the full scale net. The results obtained are summarized as follows；1. In the case of the conventional net and reduction rate 75% in conventional net with purse line the fishing efficiency decreased, the lead line was upward for the surface and the pursing depth of pursing line was very shallow to 2∼3m. 2. In the case of the net having maximum depth in center part designed in this study, the length of float and lead line was 60% of conventional net, the depth of net was fixed 20m to selvage line of the both of the end and extend gradually with 50m, 40m, 30m to the center. Among the these net, depth of pursing line was 20∼23m for 50m and 7∼15m for 40m, 30m the depth of net. These results were suitable for interception of fish school in fishing ground, but several problems will be caused by the depth and current of fishing ground.

• Journal of the Korean Geographical Society
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• v.42 no.1 s.118
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• pp.121-132
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• 2007

This paper examines the spatial and temporal variability in the water depth caused by artificial structures in Geum Estuary of South Korea. Water depth data set extracted from marine maps of 1979, 1990, 1996 and 2004 were used in a GIS to derive volumetric estimates of gains and losses of sedimentary material. Artificial structures caused above 2m in water depth to be shallow between 1979 and 2002 in the estuary system, particularly through disturbance of a natural transport in suspended sediment concentrations. The mutt significant change in suspended sediment transport were observed in area affected by embankment for fresh water, inducing the water depth shallower than before in almost 80% of the area. This was probably because of an continuous abundant mud supply from coastal river oven after blocking the fresh water. The spatial analysis made it possible to identify area wide patterns of water depth change subject to many different type of artificial structures, which tanner be acquired by traditional field sampling. It is anticipated thai this research could be used as a valuable reference to confirm the outputs from past field researches for sedimental process in more visual and quantitative manner.

• KIPS Transactions on Software and Data Engineering
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• v.11 no.5
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• pp.211-220
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• 2022

Recently, research on smart factories triggered by the 4th industrial revolution is being actively conducted. Accordingly, the manufacturing industry is conducting various studies to improve productivity and quality based on deep learning technology with robust performance. This paper is a study on the method of detecting tire surface defects in the visual inspection stage of the tire manufacturing process, and introduces a tire surface defect detection method using a depth image acquired through a 3D camera. The tire surface depth image dealt with in this study has the problem of low contrast caused by the shallow depth of the tire surface and the difference in the reference depth value due to the data acquisition environment. And due to the nature of the manufacturing industry, algorithms with performance that can be processed in real time along with detection performance is required. Therefore, in this paper, we studied a method to normalize the depth image through relatively simple methods so that the tire surface defect detection algorithm does not consist of a complex algorithm pipeline. and conducted a comparative experiment between the general normalization method and the normalization method suggested in this paper using YOLO V3, which could satisfy both detection performance and speed. As a result of the experiment, it is confirmed that the normalization method proposed in this paper improved performance by about 7% based on mAP 0.5, and the method proposed in this paper is effective.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.39 no.6
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• pp.531-536
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• 1994

Drainage duration before seeding and furrow depth desirable for establishment and growth in direct drill seeding of rice on puddled paddy soil were investigated. Furrow depths tested were 2, 4 and 6cm in combination with drainage duration 2, 4, and 6days. Dongjinbyeo was used and seeded on May 11, 1993. Seedling establishment were improved by longer drainage duration and by shallower furrow. Lodging occurred moderately at furrow depth of 2cm with 4 and 6days of surface drainage before seeding. This lodging might be attributable to the shallow burying of shoot below soil surface. Rice yield was highest at furrow depth of 4cm with 4days drainage before seeding. In considering seedling establishment and yield, desirable drainage duration before seeding and furrow depth might be 4days and 4cm, respectively. Cone(115g) penetration depth, dropped at 1m above soil surface, was 6 to 7cm on the date after 4days drainage before seeding.

• Korean Journal of Environmental Biology
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• v.35 no.2
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• pp.101-104
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• 2017

Asteroid specimens of the genus Diplopteraster were collected by trawling nets at a depth of 93 m on 05 November 2016 from the Korea Strait ($33^{\circ}41^{\prime}N$, $127^{\circ}26^{\prime}E$). The specimens were identified as Diplopteraster multipes(M. Sars, 1866), which belongs to the family Pterasteridae, order Velatida. This species is similar to other Diplopteraster species in its pentagonal stellate shape, but is distinguished by having each paxilla composed of a protruded spine, more than eight spiracles, and regularly reticulated muscular bands. It is not commonly found in shallow water. This is the first report of the genus Diplopteraster and D. multipes in Korea.