• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.1227-1228
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• 2006

This paper presents the results of a grid-connected photovoltaic(PV) system modeling that contain incremental conductance MPPT(Maximum Power Point Tracking) controller by PSCAD/EMTDC simulator and investigates the influence that can occur in the grid-connected PV system from aspect of power quality, i.e. voltage drop, total harmonic distortion(THD) and total demand distortion(TDD). The measured data the PV array modeling of PSCAD/EMTDC in Cheongwadae, Seoul, Korea is used in the paper.

• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.479-481
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• 2007

This paper presented a actual conditions on a false-tripping of ELB(Earth Leakage Breakers) and an assessment of the harmonics due to non-linear electronic equipment such as personal computers, rectifier, electric furnace and test equipments in plant installations. Actual conditions on a failure of ELB were surveyed and analyzed by making up a question to safety managers of plant installations. Also, power quality measurements such as harmonic currents, voltage and current waveform and current imbalance were made at various plant installations where nuisance tripping of ELB is often occurred. The results of this study can be used in making decisions regarding cause of ELB trip and operating and tripping characteristics test of ELB when subjected to distorted current waveform.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1687-1688
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• 2006

This paper presents the results of a grid-connected photovoltaic (PV) system modeling that contain incremental conductance MPPT(Maximum Power Point Tracking) controller by PSCAD/EMTDC simulator and investigates the influence that tan occur in the grid-connected PV system from aspect of power quality, i.e. voltage drop, total harmonic distortion(THD) and total demand distortion(TDD). The measured data the PV array modeling of PSCAD/EMTDC in Cheongwadae, Seoul, Korea is used in the paper.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.563-564
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• 2007

In recent years, equipment and network standards have been increasing in both number and complexity. Two standards that will soon be introduced to KOREA are the HV standards for assessing distorting and fluctuating loads, IEC 61000-3-6. Utility engineers, being under increasing time constraints, are turning more and more to software to quickly solve problems. This paper describes the methodology used to implement the above standards in Microsoft Excel in order to assist utility engineers to readily apply these standards in practical situations.

• The Journal of the Acoustical Society of Korea
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• v.40 no.3
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• pp.241-246
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• 2021

Modern loudspeaker systems are changing an active loudspeaker system that have multiple input channels and power amplifier. So, we cannot measure these active loudspeakers with IEC 60268-5 standard. This paper introduces an IEC 60268-21 standard that can measure an active loudspeaker having many analog and digital and wireless or wired inputs and having various control parameters.

• Medical Lasers
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• v.10 no.2
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• pp.115-119
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• 2021

A giant thyroid mass can be associated with severe compressive symptoms, requiring surgery for treatment. This paper reports the case of an 82-year-old man who presented with a giant thyroid mass that was suspected of being a metastatic papillary thyroid carcinoma on fine-needle aspiration cytology. A harmonic scalpel was used to excise the giant thyroid mass. A pectoralis major myocutaneous flap was used for reconstruction. The histopathology assessment confirmed the metastases in the lymph node and papillary thyroid carcinoma in the resected gland.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.6_3
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• pp.1239-1246
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• 2022

This paper introduces the effect of grease on the degradation characteristics of bearings used as key components of packaging equipment and automation systems. Bearings parts are installed to fix and support the rotating body of the system, and performance degradation of the bearings has a great effect on the life of the system too. When bearings are used in various devices and systems, the grease is applied to reduce friction and improve fatigue life. Determining the type of lubricant (grease) is important because it has a great influence on the operating environment and lifespan and ensures long lifespan of systems and facilities. However, studies that simultaneously compared and analyzed the change in mechanical degradation characteristics and the comparison of chemical degradation characteristics according to grease types under actual operating conditions are insufficient. In this paper, three types of small harmonic drive, high-load reducer, and low-load reducer grease used in power transmission joint modules are experimentally selected and finally injected into ball bearings with a load (19,500N) to improve bearing durability. Degradation characteristics were tested by attaching to test equipment. At this time, after the durability test under the same load conditions, the mechanical degradation characteristics, that is temperature, vibration according to the three greases types. In addition, the chemical degradation characteristics of the corresponding grease was compared to present the results of mutual correlation analysis.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.24 no.2
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• pp.183-191
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• 2006

The accuracy of the upward continuation is assessed through the gravity modeling using an ultra-high degree spherical harmonic expansion. The difficulties in the numerical calculation of Legendre function with ultra-high degree, underflow and/or overflow, is successfully resolved in 128 bit calculation scheme. Using the generated Legendre function, the gravity anomaly with spatial resolution of $1'{\times}1'$ on the geoid is calculated. The generated gravity anomaly is degraded and extracted with various noise levels and data intervals, then upward continuation is applied to each data sets. The comparison between the upward continued gravity disturbances and the directly calculated from the spherical harmonics showed that the accuracy on the direct method was significantly better than that of Poisson method. In addition, it is verified that the denser and less noised gravity data on the geoid generates better gravity disturbance vectors at an altitude. Especially, it is found that the gravity noise level less than 5mGal, and the data interval less than 2arcmin is necessary for next generation precision INS navigation which requires the accuracy of 5mGal or better at an altitude.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.1
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• pp.1-7
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• 2007

Generally, an electric railroad feeding system has many problems due to the different characteristics in contrast with a load of general three-phase AC electric power system. One of them is harmonics problem caused by the switching device existing in the feeding system, and moreover, the time-varying dynamic loads of rail way is inherently another cause to increase this harmonics problem. In Korea power systems, the electric railroad feeding system is directly supplied from the substation of KEPCO. Therefore, if voltages fluctuation or unbalanced voltages are created by the voltage and current distortion or voltage drop during operation, it affects directly the source of supply. The trainloads of electric railway system have non-periodic but iterative harmonic characteristics as operating condition, because the electric characteristic of the electric railroad feeding system is changed by physical conditions of the each trainload. According to the traditional study, the estimation of harmonics has been performed by deterministic way using the steady state data at the specific time. This method is easy to analyze harmonics, but it has limits in some cases which needs an assessment of dynamic load and reliability. Therefore, this paper proposes the probabilistic estimation method, moments matching method(MW) in order to overcome the drawback of deterministic method. In this paper, distributions for each harmonics are convolved to obtain the moments and cumulants of TDD(Total Demand Distortion), and this can be generalized for any number of trains. For the case study, the electric railway system of LAT(Intra Airport Transit) in Incheon International Airport is modeled using PSCAD/EMTDC dynamic simulator. The raw data of harmonics for the moments matching method is acquired from simulation of the LAT model.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.29 no.1
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• pp.37-40
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• 2018

Background and Objectives : This study aimed to evaluate patients' subjective and objective outcomes after laryngeal microsurgery for benign vocal fold (VF) lesions, and to identify usefulness of surgical treatment. Materials and Methods : The authors reviewed the 102 patients medical records, retrospectively who received laryngeal microsurgery for benign VF lesions from January 2013 to August 2017. Subjective voice were measured using the Voice Handicap Index (VHI). Objective voice were recorded with Multi-Dimensional Voice Program (MDVP) just before surgery, and after at least 3 months of surgery. Results : Benign VF lesions were categorized as VF nodule (n=34, 33%), VF Polyp (n=47, 26%), Intracordal cyst (n=15, 15%), Reinke's edema (n=6, 6%), and VF Papilloma (n=2, 2%). Post-operative voice assessment at VHI scores showed statistically significant reductions in all of functional, physical and emotional parts (p<0.001). MDVP were showed significant improvement of Jitter (P=0.001), Shimmer (p<0.001) and Noise to Harmonic Ratio (NHR) (p=0.001). Conclusion : Laryngeal microsurgery for benign vocal fold lesions is effective treatment with statistically significant improvement at subjective and objective vocal quality assessment.