• Journal of the Society of Naval Architects of Korea
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• v.37 no.4
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• pp.92-105
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• 2000

A study for the structural strength evaluation on the slender doubler plate has been performed through the systematic evaluation process. In order to estimate the proper static strength of doubler plate subjected to the longitudinal in-plane compression, elasto-plastic large deflection analysis is introduced including the contact effect between main plate and doubler. The characteristics of stiffness and strength variation are discussed based on their results. Also, in order to compare the doubler structure with the original strength of main plate without doubler, a simple formula for the evaluation of the equivalent flat plate thickness is derived based on the additional series analysis of flat plate structure. Using this derived equation, the thickness change of a equivalent flat plate is analyzed according to the variation of various design parameters of doubler plate and some design guides are suggested in order to maintain the original strength of main plate without doubler reinforcement. Finally, correlation between derived equivalent flat plate formula and the developed buckling strength formulas by author et al. is discovered and these relations are formulated for the future development of simple strength evaluation formula of doubler plate structure.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.35 no.6
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• pp.109-120
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• 2023

The High-Frequency Radar (HFR) is an equipment designed to measure real-time surface ocean currents in broad maritime areas.It emits radio waves at a specific frequency (HF) towards the sea surface and analyzes the backscattered waves to measure surface current vectors (Crombie, 1955; Barrick, 1972).The Seasonde HF Radar from Codar, utilized in this study, determines the speed and location of radial currents by analyzing the Bragg peak intensity of transmitted and received waves from an omnidirectional antenna and employing the Multiple Signal Classification (MUSIC) algorithm. The generated currents are initially considered ideal patterns without taking into account the characteristics of the observed electromagnetic wave propagation environment. To correct this, Antenna Pattern Measurement (APM) is performed, measuring the strength of signals at various positions received by the antenna and calculating the corrected measured vector to radial currents.The APM principle involves modifying the position and phase information of the currents based on the measured signal strength at each location. Typically, experiments are conducted by installing an antenna on a ship (Kim et al., 2022). However, using a ship introduces various environmental constraints, such as weather conditions and maritime situations. To reduce dependence on maritime conditions and enhance economic efficiency, this study explores the possibility of using unmanned aerial vehicles (drones) for APM. The research conducted APM experiments using a high-frequency radar installed at Dangsa Lighthouse in Dangsa-ri, Wando County, Jeollanam-do. The study compared and analyzed the results of APM experiments using ships and drones, utilizing the calculated radial currents and surface current fields obtained from each experiment.

• Journal of Korean Academy of Nursing
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• v.23 no.2
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• pp.187-206
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• 1993

The study was done to better understand problem behavior in high school students as described in family system theory, which explains the individual’s problem within the family interactions. The purpose of the study 1. To analyze the difference in the parents’ relationship as a couple between the two groups. 2. To analyze the difference in the parent-adolecent relationship between the two groups. 3. To analyze the difference in the family function (cohesion adaptability) between the two groups. The method of the study The staudy subjects consisted of a total of 176 families (528 persons), 109 high school students (End grade) with problem behavior and their parents (problem family group) ,and 69 high school students (same grade) with normal behavior and their parents (normal family group) residing in the Seoul area. Data were gathered from structured, self-reporting qestionaires which included a Couple Relation measurement (95 items) , Parent-Adolescent communication measurement (20 items), Family Cohesion Adaptability Scale (20 items) by DavidH. Olson et al., and a behavior evaluation tool. The results of the study 1. The results as related to the hypothesis were as follows. Hypothesis 1 : “satisfaction within The couple's relationship of the parents of problem family group will be lower than the normal family group was supported significantly(t=3.07, p=.005). Hypothesis 2: “The parent-adolescent relationship of the problem family group will be more negative and problematic than the normal family group” was supported significantly(t=4.06, p=.000). Hypothesis 3: “The family function (cohesion adaptability) of the problem family group will be lower than the normal family group" was supported significantly(t=2.20, p=.022) 2. The results of related analysis were as follows 1) Analysis of a causal relation between the couple’s relationship, the parent-adolescent relationship, family function and adolescent behavior showed that the Above 3 variables influenced adolescent behavior.. In cases where couple’s relation-ship, the parent-adolescent’s relationship, the family function are the better, their adolescent’s behavior is better. 2) Discriminant analysis of the research tool showed The discriminant ability of couple’s relationship tool was 75.57%, the Parent-Adolescent communication tool, 67.05, the family adaptability cohesion tool.67. 61%. In summary, interpersonal relationships in the family subsystems are interactive and their relation influences the behaviors. of adolescents in the family. Therefore, family therapy would be a more effective method than individual therapy, to resolve negative problem for adolscents, and the research tool used in this study are very useful for family system diagnosis and nursing intervention.

• Journal of Korea Port Economic Association
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• v.26 no.3
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• pp.18-41
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• 2010

The purpose of this paper is to show the empirical measurement way for predicting the seaport efficiency by using Super SBM(Slack-based Measure) with Wilcoxson signed-rank test under CRS(constant returns to scale) condition for 20 Korean ports during 11 years(1997-2007) for 3 inputs(port investment amount, birthing capacity, and cargo handling capacity) and 5 outputs(Export and Import Quantity, Number of Ship Calls, Port Revenue, Customer Satisfaction Point for Port Service and Container Cargo Throughput). The main empirical results of this paper are as follows. First, Super SBM model has well reflected the real data according to the Wilcoxon signed rank test, because p values have exceeded the significance level. Second,Super-SBM has shown about 87% of predicting ratio for the ports efficiency and the optimal size of investment in domestic seaport. The policy implication to the Korean seaports and planner is that Korean seaports should introduce the new methods like Super-SBM method with Wilcoxon signed rank test for predicting the efficiency of port performance and the optimal size of investment as indicated by Panayides et al.(2009, pp.203-204).

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.33 no.3
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• pp.159-165
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• 1997

This paper presents the optimum dimension of 89 ton class stow-net vessel with stern-fishing. The model of basic design is developed by using the optimization techniques referring to objective function and numerous constraints as follows; speed, fishing quantity, fishing days, catch per unit effort(CPUE), and weight/ratio of main dimensions, etc. Thus, the basic design of stow-net fishing vessel is built up by using the optimization of the design variables called the economic optimization criteria, and the objective function represents the criterion which is cost benefit ratio(CBR). The main conclusions are as follows. 1. S/W for decision of optimum hull size is developed in 89 ton class stow-net fishing vessel which is constructed with optimization of the design variables called the economic optimization criteria. 2. For optimum ship dimensions in 89 ton class stow-net fishing vessel, the hull dimensions can be obtained in the range of L= 27.3m, B = 6.6m, D = 2.80m, Cb = 0.695, T/D = 0.80, $\Delta$(displacement)=281.7ton with 10 knots.