• Geomechanics and Engineering
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• v.35 no.1
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• pp.67-80
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• 2023

Due to the nature of the conjunctive Cone Penetration Test(CPT), which does not verify the actual sample directly, geotechnical engineers commonly classify the underground geomaterials using CPT results with the classification diagrams proposed by various researchers. However, such classification diagrams may fail to reflect local geotechnical characteristics, potentially resulting in misclassification that does not align with the actual stratification in regions with strong local features. To address this, this paper presents an objective method for more accurate local CPT soil classification criteria, which utilizes C4.5 decision tree models trained with the CPT results from the clay-dominant southern coast of Korea and the sand-dominant region in South Carolina, USA. The results and analyses demonstrate that the C4.5 algorithm, in conjunction with oversampling, outlier removal, and pruning methods, can enhance and optimize the decision tree-based CPT soil classification model.

• Journal of Auto-vehicle Safety Association
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• v.16 no.1
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• pp.49-54
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• 2024

This paper provides an analysis of the experimental procedures and results to ensure the reliability of the system manufactured for testing the hydrogen permeability of a 175 L compressed hydrogen container for a hydrogen bus. Based on the hydrogen permeability standard of 6 cc/(h·L), it was injected into the permeability test chamber at 10% intervals, and the permeated hydrogen concentration according to the injected amount was measured and compared with the actual amount of hydrogen permeated. As a result of the experiment, the measured value represented 96.34% of the actual permeation amount, which can be used as basic data for the hydrogen bus vessel permeability test system being built in Korea.

• Smart Structures and Systems
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• v.23 no.2
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• pp.107-122
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• 2019

As one of the most important parameters in structural health monitoring, structural frequency has many advantages, such as convenient to be measured, high precision, and insensitive to noise. In addition, frequency-change-ratio based method had been validated to have the ability to identify the damage occurrence and location. However, building a precise enough finite elemental model (FEM) for the test structure is still a huge challenge for this frequency-change-ratio based damage detection technique. In order to overcome this disadvantage and extend the application for frequencies in structural health monitoring area, a novel method was developed in this paper by combining the cross-model cross-mode (CMCM) model updating algorithm with the frequency-change-ratio based method. At first, assuming the physical parameters, including the element mass and stiffness, of the test structure had been known with a certain value, then an initial to-be-updated model with these assumed parameters was constructed according to the typical mass and stiffness distribution characteristic of shear buildings. After that, this to-be-updated model was updated using CMCM algorithm by combining with the measured frequencies of the actual structure when no damage was introduced. Thus, this updated model was regarded as a representation of the FEM model of actual structure, because their modal information were almost the same. Finally, based on this updated model, the frequency-change-ratio based method can be further proceed to realize the damage detection and localization. In order to verify the effectiveness of the developed method, a four-level shear building was numerically simulated and two actual shear structures, including a three-level shear model and an eight-story frame, were experimentally test in laboratory, and all the test results demonstrate that the developed method can identify the structural damage occurrence and location effectively, even only very limited modal frequencies of the test structure were provided.

• Proceedings of the KSR Conference
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• 2001.10a
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• pp.131-138
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• 2001

This paper describes the result of endurance test of the brake system of the Korean EMU on the Sangju test track. The purpose of the test is to prove the endurance of brake system. Test conditions are more severe than actual operation on the commercial line. As of October, test result is good without severe problems. 100,000km of test operation will be continued by the end of this year to check the endurance of the brake system.

• Proceedings of the KSR Conference
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• 2002.05a
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• pp.336-343
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• 2002

This paper describes the result of endurance test on the Sangju test track. The purpose of the test is to prove the endurance of the Korean EMU for the commercial operation. Test conditions are more severe than actual operation on the commercial line. But endurance test come to an end well without severe problem. Hereafter, Korean EMU will be applied the quality certification of railroad supplies as a testing vehicle and their components will be applied in a new line.

• Korean Journal of Food Science and Technology
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• v.25 no.5
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• pp.481-486
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• 1993

A computeized least-cost formulation program was applied to process emulsion-type sausages. The input data in formulation were utilized with the database which had been established in the previous study. The formulation results may provide Korean meat processors with actual examples. Meat-grade system made these examples more useful. The results of manufacturing test were as follows. The actual cohesiveness from manufactured sausages didn't correspond to the predicted values, but increased as the predicted values increased. These gabs caused by the different processing conditions between the model system and the actual processing. Hardness as well as cohesiveness could be used as the desirable index of a sausage texture. Comparing the cohesiveness and hardness of commercial frankfurters with those of test sausages, bind value constraint of $0.16{\sim}0.17$ in this test formula can be utilized for an actual formulation.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.7
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• pp.67-74
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• 2009

This paper describes the speed control functions of the typical steam turbine speed controllers and the test results of generator load rejection simulations. The goal of the test is to verify the speed controller's ability to limit the steam turbine's peak speed within a predetermined level in the event of generator load loss. During normal operations, the balance between the driving force of the steam turbine and the braking force of the generator load is maintained and the speed of the turbine-generator is constant. Upon the generator's load loss, in other word, the load rejection, the turbine speed would rapidly increase up to the peak speed at a fast acceleration rate. It is required that the speed controller has the ability to limit the peak speed below the overspeed trip point, which is typically 110[%] of rated speed. If an actual load rejection occurs, a substantial amount of stresses will be applied to the turbine as well as other equipments, In order to avoid this unwanted situation, not an actual test but the other method is necessary. We are currently developing the turbine control system for another nuclear power plant and have plan to do the simulation suggested in this paper.

• Journal of the Korean School Mathematics Society
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• v.18 no.3
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• pp.335-352
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• 2015

In this paper, we selected 145 students from engineering college students who took P University's the Scholastic Level Assessment and registered the Basic Mathematics Class among the students who achieved 4th~7th grade in the mathematics B-type of the College Scholastic Ability Test. We compared and analyzed the correlation among the chosen students' grade for the College Scholastic Ability Test, test results of the Scholastic Level Assessment and mid-term test of the Basic Mathematics Subject, type of college entrance and actual condition survey of students in order to derive optimized teaching method for general mathematics subjects which can possibly increase the students' academic ability.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.5
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• pp.97-103
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• 2004

Nowadays, many kinds of research for airship are studying with increasing of interests of airship. But these are far from perfect. The data acquisition from the actual flight test has lots of difficulties because of the characteristics from the slow dynamic response and high sensitivity for external environment. In this paper, through the actual flight test, appropriateness of the mathematical dynamic model applied here was verified by comparing the test data with simulation data in same control conditions.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.4
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• pp.830-837
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• 2011

A turbine control system which has been operated for years in a nuclear power plant was retrofitted with a newly developed digital control system. After completion of the retrofit, turbine valve tests were performed to ensure the integrity of each valve's control function. The sequence of each valve test is composed of a closing process and a reopening process. To minimize megawatt variation which normally occurs during the test sequence, we employed a kind of compensator algorithm in the new digital control system which also have been used in the old system. There were difficulties finding optimal parameter settings for our new compensator algorithm because the power plant didn't allow us to perform necessary tuning procedures while the turbine is on load operation. Therefore an alternative measure for the compensator tuning which is independent of the turbine actual operation had to be implemented. So, a process model for the test was required to overcome this situation. We analyzed the operation data of the test and implemented the process model by use of input and output variable relations. Also we verified the process model by use of another condition's operating data. The result shows that the output of model is similar to the actual operation data.