• Journal of the Korean Society of Marine Environment & Safety
• /
• v.27 no.7
• /
• pp.1106-1115
• /
• 2021

In this study, a fin that controls ship stern flow was attached on stern hull of a 80k bulk carrier to improve resistance performance. The rectangular cross-sectional fin was attached at several locations on the hull, and angle to streamline was changed with constant length, breadth, and thickness. The resistance performance and wake on propeller plane of the hull with and without the fin were analyzed using model-scale computational fluid dynamics simulation. The analysis results were extrapolated to full-scale to compare the performance and wake of the full-scale ship. First, the fin changed path of bilge vortex that flowed into the propeller along the stern hull without the fin to transom stern. This change increased pressure of the stern hull and upper region of the propeller, so pressure resistance and total resistance of the hull were reduced - the nearer the fin location to after perpendicular (AP) and base line of the hull, the larger the reduction of the resistances. Second, nominal wake fraction of the hull with the fin was lower than that without the fin. This dif erence was in proportion to the angle of the fin, but the total resistance reduction was in proportion until a certain angle at which the reduction was maximum. The largest total resistance reduction was approximately 2.1% at 12.5% of length between perpendiculars from the AP, 10% of draft from the base line, and 14° with respect to the streamline.

• Tunnel and Underground Space
• /
• v.32 no.6
• /
• pp.451-463
• /
• 2022

Whenever a mineshaft accidentally collapses, speedy risk assessment is both required and crucial. But onsite safety diagnosis by humans is reportedly difficult considering the additional risk of collapse of the unstable mineshaft. Generally, drones equipped with high-speed lidar sensors can be used for such inspection. However, the drone technology is restrictively applicable at very shallow depth, failing in mineshafts with depths of hundreds of meters because of the limit of wireless communication and turbulence inside the mineshaft. In previous study, a three-dimensional (3D) scanning system with a single channel lidar was fabricated and operated using towed cable in a mineshaft to a depth of 200 m. The rotation and pendulum movement errors of the measuring unit were compensated for by applying the data of inertial measuring unit and comparing the similarity between the scan data of the adjacent depths (Kim et al., 2020). However, the errors grew with scan depth. In this paper, a multi-channel lidar sensor to obtain a continuous cross-sectional image of the mineshaft from a winch system pulled from bottom upward. In this new approach, within overlapped region viewed by the multi-channel lidar, rotation error was compensated for by comparing the similarity between the scan data at the same depth. The fabricated system was applied to scan 0-165 m depth of the mineshaft with 180 m depth. The reconstructed image was depicted in a 3D graph for interpretation.

• Journal of Digital Policy
• /
• v.1 no.2
• /
• pp.9-15
• /
• 2022

The World Economic Forum has included Water-Energy-Food among the three major risk groups in the world, and Water-Energy-Food is related to the development strategies of countries and the lives of their citizens. This study calculates the combined Water-Energy-Food use efficiency in China for 2011-2020 based on the SBM-Malmquist index. The results show that the overall combined Water-Energy-Food efficiency in China is low, but shows an upward trend. There is a clear variability in the combined Water-Energy-Food utilization efficiency in China, with an overall geographic distribution pattern of East > Middle > West. Only Beijing and Shanghai have reached the real above effective nationwide, and all other provinces have inefficiency between input and output. The Malmquist index of integrated Water-Energy-Food utilization efficiency is 1.136, with an up ward trend, and technical efficiency and technological progress lead the improvement of integrated Water-Energy-Food utilization efficiency in China at the sametime. The Water-Energy-Food issue should be raised to a strategic level as soon as possible, and policy support should be provided for its development. Each region should establish a cross-regional coordinating body to formulate targeted measures according to the province's food production and water distribution, so as to promote economic transformation from sloppy development to green development as soon as possible.

• The Journal of Engineering Geology
• /
• v.32 no.4
• /
• pp.671-684
• /
• 2022

This study verified the stability of a high-strength combined buried pile retaining wall and its applicability in the field. A cast-in-place (C.I.P) retaining wall and the high-strength combined embedded pile retaining wall were compared and analyzed numerically. The numerical analysis assessed the ground behavior and stability (and thus field applicability) of a high-strength combined buried pile retaining wall using data measured in the field. The experimental results showed that the cross-sectional force and displacement of the high-strength bonded pile retaining wall were reduced by 13.6~19.7%, the shear force increased by 0.7~4.7%, and the bending moment increased by 4.5~8.8% relative to the values for the C.I.P retaining wall. Examination of the amount of subsidence in the ground around the excavation showed that the maximum settlement of the C.I.P retaining wall was 46.89 mm and that at the high-strength combined buried pile retaining wall was 39.37 mm. Overall, designing a high-strength combined embedded pile retaining wall by applying the maximum bending moment and shear force calculated using the elastic beam method to the site ground was shown to achieve the safety of all members, as member forces were generated within the elastic region.

• The Journal of Korean Academy of Prosthodontics
• /
• v.61 no.1
• /
• pp.33-43
• /
• 2023

Pathological wear across the entire dentition causes problems such as collapsed occlusal plane, reduced vertical dimension, anterior premature contact, inadequate anterior guidance, and tooth migration, thereby induce symptoms such as temporomandibular joint disorder, reduced masticatory efficiency, and tooth hypersensitivity. For the treatment of patients with excessive wear, evaluation of vertical dimension should be preceded along with analysis of the cause. The patient in this case was a 45-year-old female with a history of orthognathic surgery. Through clinical examination, radiographic examination, and model analysis, overall tooth wear, interdental spacing in the anterior maxillary region, retruded condylar position, and insufficient interocclusal space for prosthetic restoration were confirmed. Full mouth rehabilitation with increased vertical dimension was planned, the patient's adaptation to the new vertical dimension was evaluated with a removable occlusal splint and temporary prosthesis, and cross-mounting was performed based on the temporary restoration to fabricate the definitive zirconia prosthesis, maintaining the adjusted vertical dimension. It showed satisfactory functional and esthetic results through stable restoration of the occlusal relationship.

• Korean Journal of Environmental Biology
• /
• v.39 no.4
• /
• pp.581-589
• /
• 2021

Using visible-near infrared(Vis-NIR) spectra combined with machine learning methods, the feasibility of quick and non-destructive classification of Convolvulaceae species was studied. The main aim of this study is to classify six Convolvulaceae species in the field in different geographical regions of South Korea using a handheld spectrometer. Spectra were taken at 1.5 nm intervals from the adaxial side of the leaves in the Vis-NIR spectral region between 400 and 1,075 nm. The obtained spectra were preprocessed with three different preprocessing methods to find the best preprocessing approach with the highest classification accuracy. Preprocessed spectra of the six Convolvulaceae sp. were provided as input for the machine learning analysis. After cross-validation, the classification accuracy of various combinations of preprocessing and modeling ranged between 43.4% and 98.6%. The combination of Savitzky-Golay and Support vector machine methods showed the highest classification accuracy of 98.6% for the discrimination of Convolvulaceae sp. The growth stage of the plants, different measuring locations, and the scanning position of leaves on the plant were some of the crucial factors that affected the outcomes in this investigation. We conclude that Vis-NIR spectroscopy, coupled with suitable preprocessing and machine learning approaches, can be used in the field to effectively discriminate Convolvulaceae sp. for effective weed monitoring and management.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
• /
• v.7 no.2
• /
• pp.437-444
• /
• 2017

Stress concentrations around discontinuities, such as a hole in cross section of a structural member, have great importance because the most materials failure around the region may be occurred. Stress on the point applied by concentrated load reaches much larger value than the average stress in structural member. In this paper, stress analysis was performed for the plate with a partial through-hole to find the difference of the principal stress distribution. The difference between maximum principal stress and minimum principal stress in photoelasticity is equal to the value obtained by multiplying the isochromatic fringe order by the fringe constant of the material divided by the distance through which the light passes, that is, the thickness of the specimen. Since the difference of principal stress is proportional to the photoelastic fringe order, the distribution of the principal stress difference by the finite element analysis can be compared with the photoelasticity experimental result. ANSYS Workbench, that is the finite element software, is used to compute the differences of principal stresses at the specific points on the measured lines. The computation values obtained by ANSYS are compared with the experimental measurements by photoelasticity, and two results are comparable to each other. In addition, the stress concentration factor is obtained using the stress distribution analyzed from the variation of hole depth. Stress concentration factor is increasing, as the depth of hole increase.

• The Journal of the Society of Stroke on Korean Medicine
• /
• v.9 no.1
• /
• pp.25-32
• /
• 2008

Objectives : Metabolic syndrome (MetS) is associated with increasing risk of cardiovascular morbidity and mortality but the risk of stroke associated with the MetS is less well established. The objective of this study was to evaluate the prevalence of MetS in stroke patients. Methods : We analyzed the data of 806 patients with acute ischemic stroke from Hanbang Stroke Registry supported by the Ministry of Science and Technology of Korea. Subjects' enrollment was done in the oriental medical hospitals of 4 universities located in the metropolitan region from April 2007 to August 2008. We analyzed all registered data and evaluated the prevalence of MetS and specific components of MetS. Results : The prevalence of MetS in stroke patients according to American Heart Association/National Heart Lung and Blood Institute (AHA/NHLBI) criteria was 59.6%. The prevalence according to the International Diabetes Federation (IDF) criteria was 41.6%. The prevalence of female patients was higher than that of male patients (71.8% vs 51% by AHA/NHLBI criteria; 61.7% vs 27.7% by IDF criteria). The prevalence of central obesity, low HDL cholesterol and hypertension was higher in female patients. There was no significant relationship between MetS and stroke subtype. Conclusions : This work gives us the basic data on the association between MetS and risk of stroke. There should be the prospective cohort studies to evaluate MetS and the risk of stroke.

• The Journal of the Society of Stroke on Korean Medicine
• /
• v.8 no.1
• /
• pp.22-27
• /
• 2007

Objectives : This study was aimed to assess the distribution of metabolic syndrome according to Sasang constitution(SC) in acute stroke patients. Methods : We assessed the type of SC of acute stroke patients in the oriental medical hospitals of 3 universities located in metropolitan region from October 2005 to June 2007 by Ouestionnaire for the Sasang Constitution Classification II(QSCC II). Then, we investigated the general characteristics, the prevalence of each factor of the metabolic syndrome and the prevalence of the metabolic syndrome according to SC. Results : 338 subjects were included into the final analysis. 1. This study showed that the proportion of So-yang was highest of all constitutions(45.9%). 2. The prevalence of high TG, low HDL-chol, high BP, high FBS of Tae-um were higher than those of the other constitutions, but the differencecs were not statistically significant. The prevalence of high WC of Tae-um was significantly higher than other constitutions(p<0.001). 3. The prevalence of metabolic syndrome of Tae-um was significantly higher than other constitutions (p=0.002). Conclusion : There were significant differences in the prevalence of metabolic syndrome according to SC in acute stroke patients. For the further research, it seems to be necessary to construct fundamental databases for stroke by increasing the number of patients and by diagnosing SC more delicately.

• The Journal of the Society of Stroke on Korean Medicine
• /
• v.7 no.1
• /
• pp.40-45
• /
• 2006

Objectives : This study was aimed to assess the distribution of Sasang constitution(SC) in acute stroke patients. Methods : We assessed the type of SC of acute stroke patients in the oriental medical hospitals of 3 universities located in metropolitan region from October 2005 to October 2006 by Questionnaire for the Sasang Constitution Clssification II(QSCCII). We investigated general characteristics, stroke type, blood test results, alcohol drinking, smoking and dietary preferences according to SC. Results : 236 subjects were included into the final analysis. 1. This study showed that the proportion of So-yang was highest of all constitutions(45.3%). And the body weight, body mass index, the waist circumference(WC), the hip circumference(HC), and the WC/HC ratio recorded the significantly high result in Tae-eum. 2. In the TOAST classification, SVO was the major type occupying 81.7% in the total subjects. 3. In Tae-eum, total cholesterol, triglyceride and 2 hours postprandial plasma glucose level were the highest and fasting glucose was significantly highest of all constitutions. Conclusion : From this study, we could roughly seize the distribution of Sasang constitution in acute stroke patients. For the further research, it seems to be necessary to construct fundamental databases for stroke by increasing the number of patients and by analyzing delicate characteristics of each constitution type.