• Journal of Ocean Engineering and Technology
• /
• v.22 no.2
• /
• pp.91-98
• /
• 2008

In order to establish a design guide for the bottom plate structure of a 4.3 ton aluminum planning boat, the feasibilities of bottom plate scantling of the ship are investigated based on the results of structural strength analysis and a simple equation and evaluation system are developed for initial structural design purposes. This study consists of 5 steps: First, the background, necessity, and purpose of this study are explained briefly, Second, the principal dimensions of this ship, the position of the considered bottom plate members and material characteristics are introduced. Third, the equivalent design pressure concept is introduced and evaluated based on experience and experimental data. Fourth, the strength of bottom plate members are examined using elasto-plastic nonlinear structural analysis, and response levels and several boundary conditions are reviewed based on the analysis results. Finally, in order to suggest design guides in respect to the ship's structural design, a simple design equation and evaluation system for bottom plate members are suggested for boats in the 4.3 ton aluminumboat range through the introduction of safety factorsbased on the ultimate design pressure concept.

• International Journal of Computer Science & Network Security
• /
• v.21 no.4
• /
• pp.1-8
• /
• 2021

The subject of navigation has drawn a large interest in the last few years. Navigation problem (or path planning) finds the path between two points, source location and destination location. In smart cities, solving navigation problem is essential to all residents and visitors of such cities to guide them to move easily between locations. Also, the navigation problem is very important in case of moving robots that move around the city or part of it to get some certain tasks done such as delivering packages, delivering food, etc. In either case, solution to the navigation is essential. The core to navigation systems is the navigation algorithms they employ. Navigation algorithms can be classified into navigation algorithms that depend on maps and navigation without the use of maps. The map contains all available routes and its directions. In this proposal, we consider the first class. In this paper, we are interested in getting path planning solutions very fast. In doing so, we employ a parallel platform, Reconfigurable mesh (R-Mesh), to compute the path from source location to destination location. R-Mesh is a parallel platform that has very fast solutions to many problems and can be deployed in moving vehicles and moving robots. This paper presents two algorithms for path planning. The first assumes maps with linear streets. The second considers maps with branching streets. In both algorithms, the quality of the path is evaluated in terms of the length of the path and the number of turns in the path.

• The Journal of Korean Society for School & Community Health Education
• /
• v.23 no.4
• /
• pp.1-15
• /
• 2022

Objectives: The purpose of this study was to examine the mediating effect of Stress coping method in the relationship between Covid-19 stress and academic burnout of university students in the long-lasting Covid-19 situation. Methods: The subjects of this study were 323 college students and data were collected by on-line questionnaire survey. The collected data was analyzed using SPSS 23.0 and t-test, ANOVA, multiple linear regression analysis were conducted. Also mediation analysis was performed according to the Baron & Kenny method. Results: The results were as follows. First, students with high Covid-19 stress had high academic burnout by regression analysis. Second, in the stress coping method, the active coping method lowered academic burnout, and the passive coping method increased academic burnout. Third, the active coping method showed a partial mediating effect in the relationship between Covid-19 stress and the academic burnout(p<.01). Conclusions: In order to help college students cope with academic burnout caused by Covid-19 stress, it is recommended to guide students to use active coping method through counseling and education. Ultimately, it is necessary to support students to use various coping methods according to their situation appropriately.

• Mass Spectrometry Letters
• /
• v.14 no.4
• /
• pp.166-172
• /
• 2023

The utilization of methyl 2-aminobenzoate as a biocide and pesticide has raised concerns regarding its potential toxicity. To assess its safety, it is crucial to determine its quantity and related toxicity using reference materials (RMs) or certified reference materials (CRMs). As an RM and CRM containing methyl 2-aminobenzoate within a biocidal product matrix is currently unavailable, this study aimed to produce a high-quality RM containing methyl 2-aminobenzoate, ensuring its homogeneity and stability, following the ISO Guide 35 and ISO 17034. The study determined that the produced RM exhibited homogeneity, as indicated by a calculated F-value (1.91) smaller than the critical F-value (3.02). In the assessment of isochronous short-term stability, the slope of the linear regression for the RM showed no statistically significant difference from zero when stored at temperatures of 4, 18, and 60 ℃ for 4 weeks. Regarding classical long-term stability, the RM demonstrated sustained stability over the course of one year when stored at 4 ℃. This study has successfully developed an RM for monitoring methyl 2-aminobenzoate in biocides and pesticides. Its quality underwent rigorous evaluation, confirming both homogeneity and stability.

• Radiation Oncology Journal
• /
• v.32 no.1
• /
• pp.23-30
• /
• 2014

Purpose: The goal of this study is to determine whether the magnitude of overlap between planning target volume (PTV) and rectum ($Rectum_{overlap}$) or PTV and bladder ($Bladder_{overlap}$) in prostate cancer volumetric-modulated arc therapy (VMAT) is predictive of the dose-volume relationships achieved after optimization, and to identify predictive equations and cutoff values using these overlap volumes beyond which the Quantitative Analyses of Normal Tissue Effects in the Clinic (QUANTEC) dose-volume constraints are unlikely to be met. Materials and Methods: Fifty-seven patients with prostate cancer underwent VMAT planning using identical optimization conditions and normalization. The PTV (for the 50.4 Gy primary plan and 30.6 Gy boost plan) included 5 to 10 mm margins around the prostate and seminal vesicles. Pearson correlations, linear regression analyses, and receiver operating characteristic (ROC) curves were used to correlate the percentage overlap with dose-volume parameters. Results: The percentage $Rectum_{overlap}$ and $Bladder_{overlap}$ correlated with sparing of that organ but minimally impacted other dose-volume parameters, predicted the primary plan rectum $V_{45}$ and bladder $V_{50}$ with $R^2$ = 0.78 and $R^2$ = 0.83, respectively, and predicted the boost plan rectum $V_{30}$ and bladder $V_{30}$ with $R^2$ = 0.53 and $R^2$ = 0.81, respectively. The optimal cutoff value of boost $Rectum_{overlap}$ to predict rectum $V_{75}$ >15% was 3.5% (sensitivity 100%, specificity 94%, p < 0.01), and the optimal cutoff value of boost $Bladder_{overlap}$ to predict bladder $V_{80}$ >10% was 5.0% (sensitivity 83%, specificity 100%, p < 0.01). Conclusion: The degree of overlap between PTV and bladder or rectum can be used to accurately guide physicians on the use of interventions to limit the extent of the overlap region prior to optimization.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.29 no.5
• /
• pp.239-246
• /
• 2017

In case of observing only wave height and period in the field, various wave characteristics are mainly calculated by wave by wave analysis method. In this paper, an wave by wave analysis program using MATLAB language is developed. It is possible to perform a function such as 1) correction for mean water level, 2) calculation for zero crossing time, 3) calculation for individual wave height, 4) time interval by using zero upcrossing and downcrossing method. The applicability of the developed program to the data of 0.2 second interval observed by using the WaveGuide Radar installed on HeMOSU-1 was examined. Tidal level variation removal and zero crossing time estimation were determined by linear or quadratic interpolation. It was judged that the Goda method was appropriate for calculating individual wave height, and the method proposed in this study seems to be improved through subsequent research. Due to the fineness of the sample, it can be seen that characteristics of representative waves are different from the results calculated by zero upcrossing and downcrossing method.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.40 no.2
• /
• pp.119-133
• /
• 2022

Due to the improvement of surveying, mapping and communication techniques, various apps for road direction guides and vehicle navigations have been developed. Although such a development has impacted on walking and driving, there is a limit to improving the daily convenience of the socially impaired people. This is mainly due to the fact that the software have been developed for normal pedestrians and drivers. Therefore, visually impaired people still have problems with the confusion of direction and/or non-provision of risk factors in walking. This study aimed to propose a scheme which constructs data for mobility-impaired or traffic-impaired people based on various geospatial information. The factors and components related to walking for the visually impaired are selected by geospatial data and a walking route guidance network that can be applied to a commercial software. As a result, it was confirmed that road direction guidance would be possible if additional contents, such as braille blocks (dotted/linear), sound signals, bus stops, and bollards are secured. In addition, an initial version of the application software was implemented based on the suggested data model and its usefulness was evaluated to a visually impaired person. To advance the stability of the service in walking for the visually impaired people, various geospatial data obtained by multiple institutes are necessary to be combined, and various sensors and voice technologies are required to be connected and utilized through ICT (Information and Communications Technologies) technology in near future.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.40 no.5
• /
• pp.445-454
• /
• 2020

Non-breakaway crashworthy sliding posts move rigidly with a vehicle in the early stage of vehicle impact. During this stage, a vehicle imparts its linear momentum to the post, experiencing first-stage speed loss followed by second-stage loss from the crush of the energy-absorbing pipe (EAP) installed under the guide rail. An EAP is the key element of a crashworthy sliding post and should be confined to the post foundation. This paper covers the development of an EAP for a sliding post of 507 kg, which is a sliding post type frequently used in Korea for cantilever signs. Detailed explanations of the designs for an EAP structure using LS-DYNA impact simulation are given, and the crashworthiness of the systems are confirmed through crash tests. The EAP presented in this paper can accommodate impacts from 0.9 ton-60 km/h to 1.3 ton-80 km/h, and is applicable to foundations up to 2.7 m in length.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.06a
• /
• pp.1223-1227
• /
• 2005

Fine microgroove is the key component to fabricate micro-grating, micro-grating lens and so on. Conventional groove fabrication methods such as etching and lithography have some problems in efficiency and surface integrity. This study deals with the creation of ultra-precision micro grooves using non-rotational diamond tool and CNC machining center. The shaping type machining method proposed in the study allows to produce V-shaped grooves of $40\mu{m}$ in depth with enough dimensional accuracy and surface. For the analysis of machining characteristics in micro V-grooving, three components of cutting forces and AE signal are measured and processed. Experimental results showed that large amplitude of cutting forces and AE appeared at the beginning of every cutting path, and cutting forces had a linear relation with the cross-sectional area of uncut chip thickness. From the results of this study, proposed micro V-grooving technique could be successfully applied to forming the precise optical parts like prism patterns on light guide panel of TFT-LCD.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.10a
• /
• pp.596-599
• /
• 2004

The robotic $CO_2$ welding is a manufacturing process to produce high quality joints for metal and it could provide a capability of full automation to enhance productivity. Despite the widespread use in the various manufacturing industries, the full automation of the robotic $CO_2$ welding has not yet been achieved partly because the mathematical model for the process parameters of a given welding task is not fully understood and quantified. Several mathematical models to control welding quality, productivity, microstructure and weld properties in arc welding processes have been studied. However, it is not an easy task to apply them to the various practical situations because the relationship between the process parameters and the bead geometry is non-linear and also they are usually dependent on the specific experimental results. Practically, it is difficult, but important to know how to establish a mathematical model that can predict the result of the actual welding process and how to select the optimum welding condition under a certain constraint. In this research, an attempt has been made to develop an intelligent algorithm to predict the weld geometry (top-bead width, top-bead height, back-bead width and back-bead height) as a function of key process parameters in the robotic $CO_2$welding. To achieve this above objective, Taguchi method was employed using five different process parameters (tip gap, gas flow rate, welding speed, arc current, welding voltage) as a guide for optimization of process parameters.