• Journal of the Korean Institute of Gas
• /
• v.15 no.2
• /
• pp.69-74
• /
• 2011

As a way to propose a method for the establishment of practical damage-minimizing plan for chemical plants, the release scenario was established by using API-581 BRD and the effect zone was estimated by the KS-RBI program supporting the quantitative cause analysis. And the risk assessment was performed. As a result, we found that to minimize the damage of a chemical plant, it is effective to use four release hole diameters (small, medium, large and rupture) and release time estimated according to the classes of detection and isolation systems. In addition, it can be safely said that through appling the damage areas considering weighted average by failure frequency and worst-case simultaneously, industrial sites can come up with the effective emergency response plan.

• Journal of the Korean Institute of Gas
• /
• v.11 no.4
• /
• pp.23-28
• /
• 2007

Damage ranges of accidents of the chemical facilities were estimated by the KS-RBI(Ver.3.0) program supporting the quantitative cause analysis, and the consequences were compared with the results of K-CARM(Ver2.0) program which assesses the quantitative risk in an usual method. As a result we found that the consequences of the KS-RBI program were similar to those of the K-CARM program. Therefore, the KS-RBI program could be applied to the quantitative risk assessment. In addition, it can be safely said that through appling the damage ranges of accidents by weighted average, industrial sites can come up with the effective plans of mitigation and emergency.

• Journal of the Korea Society of Computer and Information
• /
• v.10 no.4 s.36
• /
• pp.385-396
• /
• 2005

In this paper, a new structural approach to on-line signature verification is presented. A primitive pattern is defined as a part segmented by a local minimal position of speed. And a structural description of signature is composed of subpatterns which are defined as such forms as rotation shape, cusp shape and bell shape, acquired by composition of the primitives regarding the directional changes. As the matching method to find identical parts between two signatures, a modified DP(dynamic programming) matching algorithm is presented. And also, variation and complexity of local parts are computed from the training samples, and reference model and decision boundary are derived from these. Error rate, execution time and memory usage are compared among the functional approach, the parametric approach and the proposed structural approach. It is found that the average error rate can be reduced from 14.2% to 4.05% when the local parts of a signature are weighted and the complexity is used as a factor of decision threshold. Though the error rate is similar to that of functional approaches. time consumption and memory usage of the proposed structural approach are shown to be very effective.

• Journal of the Korean Data and Information Science Society
• /
• v.28 no.4
• /
• pp.863-874
• /
• 2017

Wins above replacement (WAR) is the most commonly used statistics of the many sabermetrics that measure baseball players' abilities. The advantage of a WAR is that it enables to compare performances of players even though they have different roles such as pitcher and hitter. However, WAR is difficult to obtain with common records. Thus, in this paper, we have calculated the sabermetrics variable based on Korean professional baseball records for the past three years (2014-2016). Using these variables, we suggest starting pitcher ability index that can replace WAR. Starting pitcher ability index was calculated by means of arithmetic mean, weighted average and principal component regression. Then, compared to the WAR, the most relevant method was selected, which would be useful to identify for the starting pitcher ability.

• Journal of the Korean Geotechnical Society
• /
• v.35 no.4
• /
• pp.5-14
• /
• 2019

The typical four conditions related to internal erosion were set from the results of the regular dam safety inspection for 17,500 dams, and a questionnaire survey was conducted for dam safety experts to quantify these four typical current dam conditions with scores between 0 and 10, respectively. In addition, we proposed 'possible score range' for each condition to minimize the decision limits for dam managers to quantify dam conditions while helping to quantify various dam conditions except 4 representative conditions. A case study based on 'quantified score' and 'possible score range' for each condition showed that this method consistently reflects the dangerousness of the dam and provides a reasonable probability of failure. This helps to overcome limitations of dam rating determination by weighted average, and it will help to evaluate dangerous dams as dangerous dams.

• Animal Bioscience
• /
• v.34 no.9
• /
• pp.1451-1459
• /
• 2021

Objective: The objectives of the study were to evaluate reproductive performance and selection response through genetic trend of community-based breeding programs (CBBPs) of Bonga sheep. Methods: Reproduction traits data were collected between 2012 and 2018 from Bonga sheep CBBPs. Phenotypic performance was analyzed using the general linear model procedures of Statistical Analysis System. Genetic parameters were estimated by univariate animal model for age at first lambing (AFL) and repeatability models for lambing interval (LI), litter size (LS), and annual reproductive rate (ARR) traits using restricted maximum likelihood method of WOMBAT. For correlations bivariate animal model was used. Best model was chosen based on likelihood ratio test. The genetic trends were estimated by the weighted regression of the average breeding value of the animals on the year of birth/lambing. Results: The overall least squares mean±standard error of AFL, LI, LS, and ARR were 375±12.5, 284±9.9, 1.45±0.010, and 2.31±0.050, respectively. Direct heritability estimates for AFL, LI, LS, and ARR were 0.07±0.190, 0.06±0.120, 0.18±0.070, and 0.25±0.203, respectively. The low heritability for both AFL and LI showed that these traits respond little to selection programs but rather highly depend on animal management options. The annual genetic gains were -0.0281 days, -0.016 days, -0.0002 lambs and 0.0003 lambs for AFL, LI, LS, and ARR, respectively. Conclusion: Implications of the result to future improvement programs were improving management of animals, conservation of prolific flocks and out scaling the CBBP to get better results.

• Journal of Aerospace System Engineering
• /
• v.16 no.6
• /
• pp.8-17
• /
• 2022

This paper presents a novel geometric modeling technique to predict the mechanical properties of an aircraft wing's skin-stringer integrated panel. Due to mechanical and adhesive fastening, this panel is vulnerable to stress concentration and debonding, so we designed it to integrate the skin and stringer using three-dimensional woven composites. Geometric modeling was conducted by measuring the geometric parameters of the specimen and defining the pattern of the yarns as functions. We used a weighted average model with iso-strain and iso-stress assumptions to predict the mechanical properties of the panel parts. We then compared the results of a finite element analysis with a compression test to verify the accuracy of our model. Our proposed technique proved to be more efficient than the traditional experimental method for predicting the mechanical properties of skin-stringer integrated panels.

• The Journal of the Acoustical Society of Korea
• /
• v.42 no.2
• /
• pp.94-101
• /
• 2023

A deep neural network composed of encoders and decoders, such as U-Net, used for speech enhancement, concatenates the encoder to the decoder through skip-connection. Skip-connection helps reconstruct the enhanced spectrum and complement the lost information. The features of the encoder and the decoder connected by the skip-connection are incompatible with each other. In this paper, for complex-valued spectrum based speech enhancement, Self-Attention (SA) method is applied to skip-connection to transform the feature of encoder to be compatible with the features of decoder. SA is a technique in which when generating an output sequence in a sequence-to-sequence tasks the weighted average of input is used to put attention on subsets of input, showing that noise can be effectively eliminated by being applied in speech enhancement. The three models using encoder and decoder features to apply SA to skip-connection are studied. As experimental results using TIMIT database, the proposed methods show improvements in all evaluation metrics compared to the Deep Complex U-Net (DCUNET) with skip-connection only.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.59 no.1
• /
• pp.44-54
• /
• 2023

In this study, the second-order Nomoto's nonlinear expansion model was implemented as a Tagaki-Sugeno fuzzy model based on the heading angular velocity to design the automatic steering system of a ship considering nonlinear elements. A Tagaki-Sugeno fuzzy PID controller was designed using the applied fuzzy membership functions from the Tagaki-Sugeno fuzzy model. The linear models and fuzzy membership functions of each operating point of a given nonlinear expansion model were simultaneously tuned using a genetic algorithm. It was confirmed that the implemented Tagaki-Sugeno fuzzy model could accurately describe the given nonlinear expansion model through the Zig-Zag experiment. The optimal parameters of the sub-PID controller for each operating point of the Tagaki-Sugeno fuzzy model were searched using a genetic algorithm. The evaluation function for searching the optimal parameters considered the route extension due to course deviation and the resistance component of the ship by steering. By adding a penalty function to the evaluation function, the performance of the automatic steering system of the ship could be evaluated to track the set course without overshooting when changing the course. It was confirmed that the sub-PID controller for each operating point followed the set course to minimize the evaluation function without overshoot when changing the course. The outputs of the tuned sub-PID controllers were combined in a weighted average method using the membership functions of the Tagaki-Sugeno fuzzy model. The proposed Tagaki-Sugeno fuzzy PID controller was applied to the second-order Nomoto's nonlinear expansion model. As a result of examining the transient response characteristics for the set course change, it was confirmed that the set course tracking was satisfactorily performed.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.35 no.3
• /
• pp.57-66
• /
• 2023

In order to understand the economic feasibility of an offshore wind farm, this paper analyzed the differences in LCOE (levelized cost of energy) according to the support type and construction method of the substructure in terms of LCOE and sensitivity analysis was conducted according to the main components of LCOE. As for the site to be studied, the Southwest Offshore Wind Farm was selected, and the capital expenditures were calculated according to the size of the offshore wind farm and the installation unit. As a result of the sensitivity analysis, major components showed high sensitivity to availability, turbine related cost, weighted average cost of capital and balance of system related cost. Moreover, the post-piling jacket method, which was representatively applied to the substructure of the offshore wind farm in Korea, was selected as a basic plan to calculate the capital expenditures, and then the capital expenditures of the pre-piling jacket method and the tripod method were calculated and compared. As a result of analyzing the LCOE, it was confirmed that the pre-piling jacket method of the supporting structure lowers the LCOE and improves economic feasibility as the installation number of turbines increases.