• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.3
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• pp.644-653
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• 1998

In resistance spot weld, the assurance of weld quality has been a long-standing problem. Since the weld nuggets if resustance spot welding form between the workpieces, visual detection of defects in usually impossible. Welding quality of resistance spot welding can be verified by non destructive and destructive inspections such as X-Ray inspection and testing of weld strength. But these tests, in addition to being time-consuming and costly, can entail risks due to sampling basis. The purpose of this study is the development of the monitoring system based on fuzzy inference, aimed at diagonosis of quality in resistance spot welding. The fuzzy inference system consists of fuzzy input variables, fuzzy membership functions and fuzzy rules. For inferring the welding quality(strength), the experimental data of the spot welding were acquired in various welding conditions with the monitoring system designed. Some fuzzy input variables-maximum, slop and difference values of electrode movement signals-were extracted from the experimental data. It was confirmed that the fuzzy inference values of strength have a .${\pm}$5% error in comparison with actual values for the selected welding conditions(9-10.5KA, 10-14 cycle, 250-300 $kg_f$). This monitoring system can be useful in improving the quality assurance and reliability of the resistance spot welding process.

• The Korean Journal of Emergency Medical Services
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• v.24 no.1
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• pp.77-84
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• 2020

Purpose: This study was conducted to determine effective chest compression methods that could be used when performing cardiopulmonary resuscitation in rocking boats. Methods: Tests were conducted for four minutes using manual and mechanical chest compressions on two mannequins, placed in boats, and moving at a speed of 35km/hours on calm sea surfaces with wave heights of 0.5m and wind speeds of 2-3m/s (testing for two minutes, followed by rest, then a second round of testing for two minutes). To compare the quality of the chest compressions, data were analyzed using mannequins (Resusci Anne Q-CPR, Laerdal, Norway) and then statistically processed. Results: When chest compressions were administered in the moving rescue boat, an accuracy analysis showed that the pressure speed of the hand and mechanical techniques were normal, h owever, the pressure depth accuracies were 49.04% for manual techniques and 0% for mechanical techniques. The relaxation accuracies during compressions were 2.07% for manual techniques and 95.4% for mechanical techniques. Conclusion: When administering chest compressions in rocking rescue boats, mechanical rather than manual techniques should be preferentially considered.

• Smart Structures and Systems
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• v.5 no.2
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• pp.153-171
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• 2009

In this paper, the analytical fault detection and diagnosis (FDD) is presented using model-based and signal-based methodology with wavelet analysis on signals obtained from sensors and sensor networks. In the model-based FDD, we present the modeling of contact interface found in soft materials, including the biomedical contacts. Fingerprint analysis and signal-based FDD are also presented with an experimental framework consisting of a mechanical pneumatic system typically found in manufacturing automation. This diagnosis system focuses on the signal-based approach which employs multi-resolution wavelet decomposition of various sensor signals such as pressure, flow rate, etc., to determine leak configuration. Pattern recognition technique and analytical vectorized maps are developed to diagnose an unknown leakage based on the established FDD information using the affine mapping. Experimental studies and analysis are presented to illustrate the FDD methodology. Both model-based and wavelet-based FDD applied in contact interface and manufacturing automation have implication towards better quality of life by applying theory and practice to understand how effective diagnosis can be made using intelligent FDD. As an illustration, a model-based contact surface technology an benefit the diabetes with the detection of abnormal contact patterns that may result in ulceration if not detected and treated in time, thus, improving the quality of life of the patients. Ultimately, effective diagnosis using FDD with wavelet analysis, whether it is employed in biomedical applications or manufacturing automation, can have impacts on improving our quality of life.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.2
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• pp.121-129
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• 2016

The noise pattern of a household refrigerator is dependent on the characteristics of its operating cycle which is repeated with a specific pattern depending on various parameters, such as room temperature and performance of its mechanical parts. Analysis of noise pattern is essential prior to evaluation of sound quality of a refrigerator. In this study, 14 units of refrigerator were classified into 4 types according to noise pattern and sort of mechanical part, which helps to analyze characteristics of refrigerator noise. Sound quality metrics(loudness, sharpness, roughness, and fluctuation strength) were calculated to compare noise pattern of the 4 types of refrigerator. The results of this study can be useful to decide noise performance of refrigerator.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1131-1135
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• 2005

Since human is vulnerable to emotional, physical and environmental distractions, most human inspectors cannot sustain a consistent 8-hour inspection in a day specifically for small components like door locking levers. As an alternative for human inspection, presented in this study is the development of a machine vision inspection system (MVIS) purposely for door locking levers. Comprises the development is the structure of the MVIS components, designed to meet the demands, features and specifications of door locking lever manufacturing companies in increasing their production throughput upon keeping the quality assured. This computer-based MVIS is designed to perform quality measures of detecting missing portions and defects like burr on every door locking lever. NI Vision Builder software for Automatic Inspection (AI) is found to be the optimum solution in configuring the needed quality measures. The proposed software has measurement techniques such as edge detecting and pattern-matching which are capable of gauging, detecting missing portion and checking alignment. Furthermore, this study exemplifies the incorporation of the optimized NI Builder inspection environment to the pre-inspection and post-inspection subsystems.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.6
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• pp.569-577
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• 2010

Nonplanar surface geometries of components are frequently encountered in real ultrasonic inspection situations. Use of rigid array transducers can lead to beam defocusing and reduction of defect image quality due to the mismatch between the planar array and the changing surface. When a flexible array is used to fit the complex surface profile, the locations of array elements should be known to compute the delay time necessary for adaptive heam focusing. An alternative method is to employ the time reversal focusing technique that does not require a prior knowledge about the properties and structures of the specimen and the transducer. In this paper, a time reversal method is applied to simulate beam focusing of flexible arrays and imaging of point-like defects contained in specimens with nonplanar surface geometry. Quantitative comparisons are made for the performance of a number of array techniques in terms of the ability to focus and image three point-like reflectors positioned at regular intervals. The sinusoidal profile array studied here exhibits almost the same image quality as the flat, reference case.

• Journal of Positioning, Navigation, and Timing
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• v.8 no.4
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• pp.175-181
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• 2019

This paper suggests a velocity integration algorithm for Synthetic Aperture Radar (SAR) motion measurement to reduce discontinuity of range error. When using position data from Embedded GPS/INS (EGI) to form SAR image, the discontinuity of the data degrades SAR image quality. In this paper, to reduce the discontinuity of EGI position data, EGI velocity integration is suggested which obtains navigation solution by integrating velocity data from EGI. Simulation shows that the method improves SAR image quality by reducing the discontinuity of range error. INS is a similar algorithm to EGI velocity integration in the way that it also obtains navigation solution by integrating velocity measured by IMU. Comparing INS and EGI velocity integration according to grades of IMU and GPS, EGI velocity integration is more suitable for the real system. Through this, EGI velocity integration is suggested, which improves SAR image quality more than existing algorithms.

• Korean journal of food and cookery science
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• v.20 no.5
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• pp.480-488
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• 2004

The purpose of this study was to determine gain the most desirable mixture ratio for the ingredients of Backhapbyung. Sensory examination and mechanical test were conducted on the texture, water contents and color degree of Backhapbyung with various ratios of liliibulbs powder and sugar added to nonglutinous rice flour. The results of sensory evaluation showed that Backhapbyung composed of put 8% (24g) liliibulbs powder, 40g sugar, 40ml water and 276g nonglutinous rice flour had the highest overall score in terms of acceptability, after-swallowing and taste of flavor, and overall quality preference. Overall among the recipes tested, that with 6% (24g) liliibulbs powder, 40g sugar, 40 ml water and 282g nonglutinous rice flour showed the highest marks in springiness, cohesiveness, gumminess and chewiness. The moisture content was 33.54% nonglutinous rice flour, and 11.8% liliibulbs powder. The overall quality of sensory examination for bitterness was positively correlated with the hardness of sensory examination and the mechanical examination for adhesiveness. The overall quality of sensory examination for chewiness was positively correlated with the moistness of sensory examination and the mechanical examination for cohesiveness. From the above results, the best mixture ratio of Backhapbyung, with a moisture content of 37.18%, is 8% (24g) of liliibulbs powder, 40g sugar, 40ml water, and 3g salt and 276g nonglutinous rice flour.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.1
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• pp.8-15
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• 2018

Recently, the manufacturing market for low-cost airlines has led to an increase in aircraft demand. Most processes in the production of these aircrafts are manual such as drilling, sealing, and swaging. A drilling and riveting machine is a numerical-control based equipment that automatically performs drilling, sealing, and swaging operations. The accuracy of the drilled holes and the exit burr length has a significant impact on the quality of the aircraft wing during assembly. This study was conducted to identify the conditions necessary to maintain a uniform quality by controlling the rotation speed of the spindle, which directly affects the hole diameter and the quality of the exit burr.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.5
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• pp.67-76
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• 2022

The customer demand for diverse colors in home appliances has increased. However, this has led to issues for manufacturers, such as ensuring cost effectiveness and high-level quality control. To resolve these issues, production engineers utilize computer-aided engineering (CAE) tools for injection-molding processes and assess the suitability of process parameters for products manufactured using the in-mold labeling method. CAE can solve various problems in manufacturing processes, thereby increasing production efficiency and decreasing manufacturing cost. In addition, it can be used analyze customer complaints related to surface defects, such as part differences and irregular spacing between parts, and ultimately reduce product returns. In this study, CAE was used to solve quality problems and implement the most economical manufacturing process.