• Journal of Wetlands Research
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• v.21 no.3
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• pp.207-214
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• 2019

This study investigated the flow characteristics in an annular flume with a free water surface using the Acoustic Doppler Velocimeter(ADV) in the laboratory. The flow was driven by the rotation of the inner cylinder in a way designed not to interfere with flocculation of cohesive sediments. The effect of the inner cylinder for the longitudinal velocities showed highest near the moving boundary and decreased towards the outer wall. At the lower longitudinal velocity, there was a peak in turbulent kinetic energy near the bed, whereas it moved upward to with increasing of the velocity. The longitudinal velocities estimated using the power law were in good agreement with the measured values than the values predicted by the log-law with roughness lengths. The average friction velocities evaluated by Reynolds shear stress were smaller than the values calculated using the log-law and power law when increasing the longitudinal velocity.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.2
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• pp.187-192
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• 2021

This study proposes a system for take-off in a forest or similar complex environment using an object detector. In the simulator, a raspberry pi is mounted on a quadcopter with a length of 550mm between motors on a diagonal line, and the experiment is conducted based on edge computing. As for the images to be used for learning, about 150 images of 640⁎480 size were obtained by selecting three points inside Kunsan University, and then converting them to black and white, and pre-processing the binarization by placing a boundary value of 127. After that, we trained the SSD_Inception model. In the simulation, as a result of the experiment of taking off the drone through the model trained with the verification image as an input, a trajectory similar to the takeoff was drawn using the label.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.524-524
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• 2023

하천 내 식생의 분포는 흐름저항의 증가와 수위상승에 큰 영향을 미치는 요소 중 하나이다. 동일한 단면정보를 가졌더라도 식생이 분포하는 하도는 식생이 없는 하도에 비해 흐름저항으로 인해 유속이 현저히 느려져 홍수위 상승을 유발하기 때문이다. 따라서 식생의 종류, 크기, 분포 형태, 잎의 밀도 등에 따라 흐름저항계수를 정량화하며 흐름을 정확히 예측하는 것이 필요하다. 본 연구에서는 2019년 한국건설기술연구원 하천실험센터에서 진행된 식생하도에 대한 실규모 실험의 조건과 지형정보를 HEC-RAS(Hydrologic Engineering Center's River Analysis System) 1차원 수치모형에 입력하고, 식생 패치의 분포를 고려한 Manning's n의 공간적 분포 및 적용방식에 따른 수면 경사 재현 정확도에 대한 민감도 분석을 수행하였다. 실험은 상단 폭 11 m, 경사 1:2(V:H)의 사다리꼴 단면을 가진 실규모 수로에서 70 m 길이의 구간을 대상으로 진행되었다. 실험 구간 내 6개의 압력식 수위계를 설치해 수위 측정 및 수면 경사 산정을 실행하였다. 실험 조건으로 적용된 인공 식생패치의 분포 및 밀도 조건은 3가지로 큰 패치와 작은 패치로 구성된 조밀한 조건, 단일 패치로 구성된 조밀한 조건, 단일 패치로 구성된 성긴 조건이었으며, 모두 정수(emergent)상태로 진행되었다. 적용된 패치의 형상은 내성천에서 조사된 자연 형태의 식생패치 형태를 참고하였으며, 버드나무 종을 모사하였다. 실험 조건에 따라 유량은 각각 평균 1.5 cms와 2.7 cms로 공급하였으며, 평균 수심은 약 1 m로 측정되었다. 위 실험 내용을 바탕으로 수치모의를 위한 경계조건과 지형정보를 수립하였으며 모의 케이스는 크게 두 가지로, 수로 내 식생의 분포를 종방향으로 고려한 케이스와 횡방향으로 고려하여 조도계수를 적용한 케이스로 분류하였다. 모의에 적용된 조도계수는 실험에서 획득한 데이터와 베르누이 방정식을 활용하여 산정되었으며, 두 케이스에 대한 모의 결과는 실험에서 관측된 수위와 비교하였다. 본 연구에 따르면 여러 개의 식생패치가 정수상태로 존재하는 하천에 대한 1차원 수치모의 시 식생의 분포를 종방향으로 고려하여 하나의 구간조도계수를 적용하는 방식이 종횡단면의 식생패치 위치를 고려한 조도계수를 세분화하여 적용하는 방식에 비해 수위 계산 정확도가 상대적으로 높은 것으로 나타났다.

• Journal of the Korean Geotechnical Society
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• v.22 no.3
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• pp.37-43
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• 2006

An analytical solution method capable of determining the geometric configuration and developed tensile forces of mooring lines associated with fixed plate/pile or drag anchors has been developed. The solution method, satisfying complete equilibrium conditions, is capable of analyzing multi-segmented mooring lines that can consist of either chains, cables, or synthetic wires embedded in layered seafloor soils. The solution method utilizes a systematic iterative search method based on specific boundary conditions. This paper describes the principles associated with the development of the solution for the mooring line analysis. Comparisons of predictions with results from a series of field tests of mooring lines on various types of drag anchors are also described. Comparisons include the tension in anchor, the length of mooring line on the bottom, and the angle of mooring line at the water surface buoy. The results indicate that the analytical solution method is capable of predicting the behavior of mooring lines with high degree of accuracy.

• Journal of Korea Society of Industrial Information Systems
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• v.28 no.6
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• pp.29-43
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• 2023

Consumers should look at the ingredients of cosmetics or food for their health and purchase them after checking whether they contain allergy-causing ingredients. Therefore, this paper aimed to develop an artificial intelligence-based smartphone application for automatically recognizing the ingredients displayed on a curved container and delivering it to consumers in an easy-to-understand manner. The app needs to allow consumers to immediately comprehend the restricted ingredients by recognizing the ingredients' words in the cropped image. Two major issues should be solved during the development process: First, although there were flat containers for cosmetics or food, most were curved containers. Thus, it was necessary to recognize the ingredient table displayed on the curved containers. Second, since the ingredients' words were displayed on the curved surface, the transformed or line-changed words also needed to be recognized. The proposed new methods were enough to solve the above two problems. The application developed through various tests verified that there was no problem recognizing the ingredients' words contained in a cylindrical curved container.

• Journal of the Korean GEO-environmental Society
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• v.18 no.5
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• pp.45-53
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• 2017

IPM bridge was developed to revise the problems of IAB bridge by Nam et al, (2016). This research conducted the p-y analysis to examine the parameter traits among the protruded length (H), penetrated length (L) of pile bent and soil conditions. From the results, the maximum bending moment happened in the top segment of pile bent, because it is integrated to the upper structure. Also, the maximum shear force was shown in the boundary of the sand and weathered soil zones according to the analysis soil conditions. The maximum member force and unbraced length is converged when the ratio (L/H) of protruded length (H) and penetrated length (L) is 1.0. The larger material force is happened, if the pile bent is penetrated shallowly compared to the protruded length. The definite inflection points were shown in the horizontal displacement curve from the p-y analysis, also the smaller penetrated length made the curve grade slower.

• Journal of the Korean Institute of Landscape Architecture
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• v.46 no.3
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• pp.58-69
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• 2018

This study investigated root damage characteristics and correlations between roadside trees and street furniture through the investigation of the root damage conditions and the current status of roadside trees and street furniture in Seo-gu, Daejeon City where the occurrence of pavement uplift is frequent. The study area was divided into six areas by species of trees as Metasequoia glyptostroboides and Platanus occidentalis focusing on the streets that were installed with trees chest height and 8cm round planted at the time of the development of the Dunsan-dong Housing Site Development in Seo-gu, Daejeon metropolitan city (1990~1994). The damage rate of roadside protection frames (95.3%) was higher than that of curbstones (19.7%) at the study site. Streets without a protective frame were more likely to have damaged pavement. In addition, the frequency of breakage of protective frames was lowered when a drinking water area was increased to more than a certain level. The frequency of the type of uplift in the sidewalk pavement surfaces is in the order of tail type > mounding type > irregular type, and the frequency of the uplift direction is the highest in Direction 1 ($0{\sim}44^{\circ}C$), Direction 2 ($45{\sim}89^{\circ}$), and Direction 3 ($95{\sim}134^{\circ}$) when $180^{\circ}$ of the street direction is based on $90^{\circ}$ parallel to the curbstone. The uplift length is about 31~60cm and it is most often at a height of 3~6cm. When comparing the results of uplift deformation, Metasequoia glyptostroboides was found to be higher than the deformation of Platanus occidentalis. In addition, it can be seen that the larger the length, width and height of the ridge, the larger the deformation becomes. The relationship between the diameter at breast height, the dimension of the pavement width, the frequency of the ridge phenomenon and the deformation amount is not necessarily proportional, and there seems to be a gap due to external factors such as soil humidity and planting base. Therefore there is a need for a multi-directional approach in reducing uplift.

• Journal of the Korean Geotechnical Society
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• v.35 no.10
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• pp.47-66
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• 2019

A parametric numerical analysis according to diameter, length, and N values of soil was conducted for the PHC pile socketed into weathered rock through sandy soil layers. In the numerical analysis, the Mohr-Coulomb model was applied to PHC pile and soils, and the contacted phases among the pile-soil-cement paste were modeled as interfaces with a virtual thickness. The parametric numerical analyses for 10 kinds of pile diameters were executed to obtain the load-settlement relationship and the axial load distribution according to N-values. The load-settlement curves were obtained for each load such as total load, total skin friction, skin friction of the sandy soil layer, skin friction of the weathered rock layer and end bearing resistance of the weathered rock. As a result of analysis of various load levels from the load-settlement curves, the settlements corresponding to the inflection point of each curve were appeared as about 5~7% of each pile diameter and were estimated conservatively as 5% of each pile diameter. The load at the inflection point was defined as the mobilized bearing capacity ($Q_m$) and it was used in analyses of pile bearing capacity. And SRF was appeared above average 70%, irrespective of diameter, embedment length of pile and N value of sandy soil layer. Also, skin frictional resistance of sandy soil layers was evaluated above average 80% of total skin frictional resistance. These results can be used in calculating the bearing capacity of prebored PHC pile, and also be utilized in developing the bearing capacity prediction method and chart for the prebored PHC pile socketed into weathered rock through sandy soil layers.

• Korean Journal of Environment and Ecology
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• v.36 no.6
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• pp.676-683
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• 2022

Due to the effects of rapid changes in the living environment since 2000 and the recent unforeseen pandemic, people are refraining from domestic and international traveling and movement, and outdoor activities for health and the public value of forest trails, called Dullegil Trail in Korea, have become more important. This study estimated the environmental value of the tentatively named "East-West Trail," which connects the forest trails crossing Chungcheong and Gyeongsang Provinces using CVM (Contingent Valuation Method). It surveyed visitors to the East-West Trail, and 725 questionnaires were used for analysis. The average characteristics of respondents were those who exercised 2-3 times per week, visited a forest trail not far from their residence with friends or family, and showed a tendency to spend 50 thousand Korean won or more per visit. Visitors to the Dullegil Trail felt that there was a shortage of information boards on the forest trail, and they preferred a shelter in appropriate locations. We used a double-bounded dichotomous choice (BDDC) logit model proposed by Hanemann to measure the conservation value of the East-West Trail. It was estimated that the environmental value that a visitor to the East-West Trail could obtain was 30,087 won per trip. The estimated environmental value of the East-West Trail can be converted to about 94 billion won total visitors annually based on the population belonging to the direct-use zone near the East-West Trail. As there has been no study on the environmental value of forest trails using CVM, the results of this study will be able to suggest the feasibility of the government policies on forest trails.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.6
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• pp.737-747
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• 1999

To estimate biomass and distribution of the Antarctic krill (Euphausia superba), hydroacoustic survey was conducted on board of R/V Yuzhmorgeologiya, which was chartered by Korea Antarctic Research Program (KARP) group from 18 to 21 December 1998, in the northern part of the South Shetland Islands, Antarctic Ocean, The scientific echo sounder (towing body type) used was EK- 500 (SIMRAD, Norway) with echo integrator (BI-500) at 38 kHz frequency and recorded mean backscattering cross-section coefficient (SA) per 1 $mile^2$ of sea surface. Also, Bongo net sampling was carried out to determine the size of krill and CTD (Conductivity, Temperature and Depth) casting to understand physical structure. Water column was divided into 5 layers (22$\~$65 m, 65$\~$115 m, l15$\~$65 m, 165$\~$215 m and 215$\~$315 m) to know vertical distribution of krill biomass. The standard length of krill collected was between 30 mm and 51 mm, and adult krill had single mode (41 mm). Maximum horizontal length of krill patch was about 35 nautical mile and vertical thickness was about 275 m. High density of krill was appeared in frontal area between Circumpolar Deep Water (>$1^{\circ}C$) and very low temperature water mass (< $-0.5^{\circ}C$) that originate from Weddell Sea. According to the results calculated using target strength equation, krill density was totally higher in continental slope and open water areas than in coastal area. In the study area, krill seems to distribute in depth; density was low at first layer ($\={\rho}=17.0\;g/m^2$) and higher at fourth layer ($\={\rho}=40.19\;g/m^2$). The estimated krill biomass at total survey area and water column was about 2.77 million metric ion ($\={\rho}=151.0\;g/m^2$) and coefficient of valiance ( CV, $\%$) was 19.92. The proportions and biomass of krill biomass at each layer were as follows; layer 1 ($11.3\%$, 0.31 million metric ton, CV=16.24), layer 2 ($13.3\%$, 0.37 million metric ton, CV=34.91), layer 3 ($23.7\%$, 0.66 million metric ton, CV=41.5), layer 4 ($26.6\%$, 0.74 million metric ton, CV=27.84) and layer 5 ($25\%$, 0.69 million metric ton, CV= 26.83).